mcs/mcs/expression.cs

   1 //
   2 // expression.cs: Expression representation for the IL tree.
   3 //
   4 // Author:
   5 //   Miguel de Icaza (miguel@ximian.com)
   6 //   Marek Safar (marek.safar@gmail.com)
   7 //
   8 // Copyright 2001, 2002, 2003 Ximian, Inc.
   9 // Copyright 2003-2008 Novell, Inc.
  10 // Copyright 2011 Xamarin Inc.
  11 //
  12
  13 using System;
  14 using System.Collections.Generic;
  15 using System.Linq;
  16 using SLE = System.Linq.Expressions;
  17 using System.Text;
  18
  19 #if STATIC
  20 using MetaType = IKVM.Reflection.Type;
  21 using IKVM.Reflection;
  22 using IKVM.Reflection.Emit;
  23 #else
  24 using MetaType = System.Type;
  25 using System.Reflection;
  26 using System.Reflection.Emit;
  27 #endif
  28
  29 namespace Mono.CSharp
  30 {
  31         //
  32         // This is an user operator expression, automatically created during
  33         // resolve phase
  34         //
  35         public class UserOperatorCall : Expression {
  36                 protected readonly Arguments arguments;
  37                 protected readonly MethodSpec oper;
  38                 readonly Func<ResolveContext, Expression, Expression> expr_tree;
  39
  40                 public UserOperatorCall (MethodSpec oper, Arguments args, Func<ResolveContext, Expression, Expression> expr_tree, Location loc)
  41                 {
  42                         this.oper = oper;
  43                         this.arguments = args;
  44                         this.expr_tree = expr_tree;
  45
  46                         type = oper.ReturnType;
  47                         eclass = ExprClass.Value;
  48                         this.loc = loc;
  49                 }
  50
  51                 public override bool ContainsEmitWithAwait ()
  52                 {
  53                         return arguments.ContainsEmitWithAwait ();
  54                 }
  55
  56                 public override Expression CreateExpressionTree (ResolveContext ec)
  57                 {
  58                         if (expr_tree != null)
  59                                 return expr_tree (ec, new TypeOfMethod (oper, loc));
  60
  61                         Arguments args = Arguments.CreateForExpressionTree (ec, arguments,
  62                                 new NullLiteral (loc),
  63                                 new TypeOfMethod (oper, loc));
  64
  65                         return CreateExpressionFactoryCall (ec, "Call", args);
  66                 }
  67
  68                 protected override void CloneTo (CloneContext context, Expression target)
  69                 {
  70                         // Nothing to clone
  71                 }
  72
  73                 protected override Expression DoResolve (ResolveContext ec)
  74                 {
  75                         //
  76                         // We are born fully resolved
  77                         //
  78                         return this;
  79                 }
  80
  81                 public override void Emit (EmitContext ec)
  82                 {
  83                         var call = new CallEmitter ();
  84                         call.Emit (ec, oper, arguments, loc);
  85                 }
  86
  87                 public override void FlowAnalysis (FlowAnalysisContext fc)
  88                 {
  89                         arguments.FlowAnalysis (fc);
  90                 }
  91
  92                 public override SLE.Expression MakeExpression (BuilderContext ctx)
  93                 {
  94 #if STATIC
  95                         return base.MakeExpression (ctx);
  96 #else
  97                         return SLE.Expression.Call ((MethodInfo) oper.GetMetaInfo (), Arguments.MakeExpression (arguments, ctx));
  98 #endif
  99                 }
 100         }
 101
 102         public class ParenthesizedExpression : ShimExpression
 103         {
 104                 public ParenthesizedExpression (Expression expr, Location loc)
 105                         : base (expr)
 106                 {
 107                         this.loc = loc;
 108                 }
 109
 110                 protected override Expression DoResolve (ResolveContext rc)
 111                 {
 112                         Expression res = null;
 113                         using (rc.With (ResolveContext.Options.DontSetConditionalAccessReceiver, false)) {
 114                                 res = expr.Resolve (rc);
 115                         }
 116
 117                         var constant = res as Constant;
 118                         if (constant != null && constant.IsLiteral) {
 119                                 if (res is NullLiteral)
 120                                         return res;
 121
 122                                 return Constant.CreateConstantFromValue (res.Type, constant.GetValue (), expr.Location);
 123                         }
 124
 125                         return res;
 126                 }
 127
 128                 public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
 129                 {
 130                         return expr.DoResolveLValue (ec, right_side);
 131                 }
 132
 133                 public override object Accept (StructuralVisitor visitor)
 134                 {
 135                         return visitor.Visit (this);
 136                 }
 137
 138                 public override bool HasConditionalAccess ()
 139                 {
 140                         return false;
 141                 }
 142         }
 143
 144         //
 145         //   Unary implements unary expressions.
 146         //
 147         public class Unary : Expression
 148         {
 149                 public enum Operator : byte {
 150                         UnaryPlus, UnaryNegation, LogicalNot, OnesComplement,
 151                         AddressOf,  TOP
 152                 }
 153
 154                 public readonly Operator Oper;
 155                 public Expression Expr;
 156                 ConvCast.Mode enum_conversion;
 157
 158                 public Unary (Operator op, Expression expr, Location loc)
 159                 {
 160                         Oper = op;
 161                         Expr = expr;
 162                         this.loc = loc;
 163                 }
 164
 165                 // <summary>
 166                 //   This routine will attempt to simplify the unary expression when the
 167                 //   argument is a constant.
 168                 // </summary>
 169                 Constant TryReduceConstant (ResolveContext ec, Constant constant)
 170                 {
 171                         var e = constant;
 172
 173                         while (e is EmptyConstantCast)
 174                                 e = ((EmptyConstantCast) e).child;
 175
 176                         if (e is SideEffectConstant) {
 177                                 Constant r = TryReduceConstant (ec, ((SideEffectConstant) e).value);
 178                                 return r == null ? null : new SideEffectConstant (r, e, r.Location);
 179                         }
 180
 181                         TypeSpec expr_type = e.Type;
 182
 183                         switch (Oper){
 184                         case Operator.UnaryPlus:
 185                                 // Unary numeric promotions
 186                                 switch (expr_type.BuiltinType) {
 187                                 case BuiltinTypeSpec.Type.Byte:
 188                                         return new IntConstant (ec.BuiltinTypes, ((ByteConstant) e).Value, e.Location);
 189                                 case BuiltinTypeSpec.Type.SByte:
 190                                         return new IntConstant (ec.BuiltinTypes, ((SByteConstant) e).Value, e.Location);
 191                                 case BuiltinTypeSpec.Type.Short:
 192                                         return new IntConstant (ec.BuiltinTypes, ((ShortConstant) e).Value, e.Location);
 193                                 case BuiltinTypeSpec.Type.UShort:
 194                                         return new IntConstant (ec.BuiltinTypes, ((UShortConstant) e).Value, e.Location);
 195                                 case BuiltinTypeSpec.Type.Char:
 196                                         return new IntConstant (ec.BuiltinTypes, ((CharConstant) e).Value, e.Location);
 197
 198                                 // Predefined operators
 199                                 case BuiltinTypeSpec.Type.Int:
 200                                 case BuiltinTypeSpec.Type.UInt:
 201                                 case BuiltinTypeSpec.Type.Long:
 202                                 case BuiltinTypeSpec.Type.ULong:
 203                                 case BuiltinTypeSpec.Type.Float:
 204                                 case BuiltinTypeSpec.Type.Double:
 205                                 case BuiltinTypeSpec.Type.Decimal:
 206                                         return e;
 207                                 }
 208
 209                                 return null;
 210
 211                         case Operator.UnaryNegation:
 212                                 // Unary numeric promotions
 213                                 switch (expr_type.BuiltinType) {
 214                                 case BuiltinTypeSpec.Type.Byte:
 215                                         return new IntConstant (ec.BuiltinTypes, -((ByteConstant) e).Value, e.Location);
 216                                 case BuiltinTypeSpec.Type.SByte:
 217                                         return new IntConstant (ec.BuiltinTypes, -((SByteConstant) e).Value, e.Location);
 218                                 case BuiltinTypeSpec.Type.Short:
 219                                         return new IntConstant (ec.BuiltinTypes, -((ShortConstant) e).Value, e.Location);
 220                                 case BuiltinTypeSpec.Type.UShort:
 221                                         return new IntConstant (ec.BuiltinTypes, -((UShortConstant) e).Value, e.Location);
 222                                 case BuiltinTypeSpec.Type.Char:
 223                                         return new IntConstant (ec.BuiltinTypes, -((CharConstant) e).Value, e.Location);
 224
 225                                 // Predefined operators
 226                                 case BuiltinTypeSpec.Type.Int:
 227                                         int ivalue = ((IntConstant) e).Value;
 228                                         if (ivalue == int.MinValue) {
 229                                                 if (ec.ConstantCheckState) {
 230                                                         ConstantFold.Error_CompileTimeOverflow (ec, loc);
 231                                                         return null;
 232                                                 }
 233                                                 return e;
 234                                         }
 235                                         return new IntConstant (ec.BuiltinTypes, -ivalue, e.Location);
 236
 237                                 case BuiltinTypeSpec.Type.Long:
 238                                         long lvalue = ((LongConstant) e).Value;
 239                                         if (lvalue == long.MinValue) {
 240                                                 if (ec.ConstantCheckState) {
 241                                                         ConstantFold.Error_CompileTimeOverflow (ec, loc);
 242                                                         return null;
 243                                                 }
 244                                                 return e;
 245                                         }
 246                                         return new LongConstant (ec.BuiltinTypes, -lvalue, e.Location);
 247
 248                                 case BuiltinTypeSpec.Type.UInt:
 249                                         UIntLiteral uil = constant as UIntLiteral;
 250                                         if (uil != null) {
 251                                                 if (uil.Value == int.MaxValue + (uint) 1)
 252                                                         return new IntLiteral (ec.BuiltinTypes, int.MinValue, e.Location);
 253                                                 return new LongLiteral (ec.BuiltinTypes, -uil.Value, e.Location);
 254                                         }
 255                                         return new LongConstant (ec.BuiltinTypes, -((UIntConstant) e).Value, e.Location);
 256
 257
 258                                 case BuiltinTypeSpec.Type.ULong:
 259                                         ULongLiteral ull = constant as ULongLiteral;
 260                                         if (ull != null && ull.Value == 9223372036854775808)
 261                                                 return new LongLiteral (ec.BuiltinTypes, long.MinValue, e.Location);
 262                                         return null;
 263
 264                                 case BuiltinTypeSpec.Type.Float:
 265                                         FloatLiteral fl = constant as FloatLiteral;
 266                                         // For better error reporting
 267                                         if (fl != null)
 268                                                 return new FloatLiteral (ec.BuiltinTypes, -fl.Value, e.Location);
 269
 270                                         return new FloatConstant (ec.BuiltinTypes, -((FloatConstant) e).Value, e.Location);
 271
 272                                 case BuiltinTypeSpec.Type.Double:
 273                                         DoubleLiteral dl = constant as DoubleLiteral;
 274                                         // For better error reporting
 275                                         if (dl != null)
 276                                                 return new DoubleLiteral (ec.BuiltinTypes, -dl.Value, e.Location);
 277
 278                                         return new DoubleConstant (ec.BuiltinTypes, -((DoubleConstant) e).Value, e.Location);
 279
 280                                 case BuiltinTypeSpec.Type.Decimal:
 281                                         return new DecimalConstant (ec.BuiltinTypes, -((DecimalConstant) e).Value, e.Location);
 282                                 }
 283
 284                                 return null;
 285
 286                         case Operator.LogicalNot:
 287                                 if (expr_type.BuiltinType != BuiltinTypeSpec.Type.Bool)
 288                                         return null;
 289
 290                                 bool b = (bool)e.GetValue ();
 291                                 return new BoolConstant (ec.BuiltinTypes, !b, e.Location);
 292
 293                         case Operator.OnesComplement:
 294                                 // Unary numeric promotions
 295                                 switch (expr_type.BuiltinType) {
 296                                 case BuiltinTypeSpec.Type.Byte:
 297                                         return new IntConstant (ec.BuiltinTypes, ~((ByteConstant) e).Value, e.Location);
 298                                 case BuiltinTypeSpec.Type.SByte:
 299                                         return new IntConstant (ec.BuiltinTypes, ~((SByteConstant) e).Value, e.Location);
 300                                 case BuiltinTypeSpec.Type.Short:
 301                                         return new IntConstant (ec.BuiltinTypes, ~((ShortConstant) e).Value, e.Location);
 302                                 case BuiltinTypeSpec.Type.UShort:
 303                                         return new IntConstant (ec.BuiltinTypes, ~((UShortConstant) e).Value, e.Location);
 304                                 case BuiltinTypeSpec.Type.Char:
 305                                         return new IntConstant (ec.BuiltinTypes, ~((CharConstant) e).Value, e.Location);
 306
 307                                 // Predefined operators
 308                                 case BuiltinTypeSpec.Type.Int:
 309                                         return new IntConstant (ec.BuiltinTypes, ~((IntConstant)e).Value, e.Location);
 310                                 case BuiltinTypeSpec.Type.UInt:
 311                                         return new UIntConstant (ec.BuiltinTypes, ~((UIntConstant) e).Value, e.Location);
 312                                 case BuiltinTypeSpec.Type.Long:
 313                                         return new LongConstant (ec.BuiltinTypes, ~((LongConstant) e).Value, e.Location);
 314                                 case BuiltinTypeSpec.Type.ULong:
 315                                         return new ULongConstant (ec.BuiltinTypes, ~((ULongConstant) e).Value, e.Location);
 316                                 }
 317                                 if (e is EnumConstant) {
 318                                         var res = TryReduceConstant (ec, ((EnumConstant)e).Child);
 319                                         if (res != null) {
 320                                                 //
 321                                                 // Numeric promotion upgraded types to int but for enum constant
 322                                                 // original underlying constant type is needed
 323                                                 //
 324                                                 if (res.Type.BuiltinType == BuiltinTypeSpec.Type.Int) {
 325                                                         int v = ((IntConstant) res).Value;
 326                                                         switch (((EnumConstant) e).Child.Type.BuiltinType) {
 327                                                                 case BuiltinTypeSpec.Type.UShort:
 328                                                                 res = new UShortConstant (ec.BuiltinTypes, (ushort) v, e.Location);
 329                                                                 break;
 330                                                                 case BuiltinTypeSpec.Type.Short:
 331                                                                 res = new ShortConstant (ec.BuiltinTypes, (short) v, e.Location);
 332                                                                 break;
 333                                                                 case BuiltinTypeSpec.Type.Byte:
 334                                                                 res = new ByteConstant (ec.BuiltinTypes, (byte) v, e.Location);
 335                                                                 break;
 336                                                                 case BuiltinTypeSpec.Type.SByte:
 337                                                                 res = new SByteConstant (ec.BuiltinTypes, (sbyte) v, e.Location);
 338                                                                 break;
 339                                                         }
 340                                                 }
 341
 342                                                 res = new EnumConstant (res, expr_type);
 343                                         }
 344                                         return res;
 345                                 }
 346                                 return null;
 347                         }
 348                         throw new Exception ("Can not constant fold: " + Oper.ToString());
 349                 }
 350
 351                 protected virtual Expression ResolveOperator (ResolveContext ec, Expression expr)
 352                 {
 353                         eclass = ExprClass.Value;
 354
 355                         TypeSpec expr_type = expr.Type;
 356                         Expression best_expr;
 357
 358                         TypeSpec[] predefined = ec.BuiltinTypes.OperatorsUnary [(int) Oper];
 359
 360                         //
 361                         // Primitive types first
 362                         //
 363                         if (BuiltinTypeSpec.IsPrimitiveType (expr_type)) {
 364                                 best_expr = ResolvePrimitivePredefinedType (ec, expr, predefined);
 365                                 if (best_expr == null)
 366                                         return null;
 367
 368                                 type = best_expr.Type;
 369                                 Expr = best_expr;
 370                                 return this;
 371                         }
 372
 373                         //
 374                         // E operator ~(E x);
 375                         //
 376                         if (Oper == Operator.OnesComplement && expr_type.IsEnum)
 377                                 return ResolveEnumOperator (ec, expr, predefined);
 378
 379                         return ResolveUserType (ec, expr, predefined);
 380                 }
 381
 382                 protected virtual Expression ResolveEnumOperator (ResolveContext ec, Expression expr, TypeSpec[] predefined)
 383                 {
 384                         TypeSpec underlying_type = EnumSpec.GetUnderlyingType (expr.Type);
 385                         Expression best_expr = ResolvePrimitivePredefinedType (ec, EmptyCast.Create (expr, underlying_type), predefined);
 386                         if (best_expr == null)
 387                                 return null;
 388
 389                         Expr = best_expr;
 390                         enum_conversion = Binary.GetEnumResultCast (underlying_type);
 391                         type = expr.Type;
 392                         return EmptyCast.Create (this, type);
 393                 }
 394
 395                 public override bool ContainsEmitWithAwait ()
 396                 {
 397                         return Expr.ContainsEmitWithAwait ();
 398                 }
 399
 400                 public override Expression CreateExpressionTree (ResolveContext ec)
 401                 {
 402                         return CreateExpressionTree (ec, null);
 403                 }
 404
 405                 Expression CreateExpressionTree (ResolveContext ec, Expression user_op)
 406                 {
 407                         string method_name;
 408                         switch (Oper) {
 409                         case Operator.AddressOf:
 410                                 Error_PointerInsideExpressionTree (ec);
 411                                 return null;
 412                         case Operator.UnaryNegation:
 413                                 if (ec.HasSet (ResolveContext.Options.CheckedScope) && user_op == null && !IsFloat (type))
 414                                         method_name = "NegateChecked";
 415                                 else
 416                                         method_name = "Negate";
 417                                 break;
 418                         case Operator.OnesComplement:
 419                         case Operator.LogicalNot:
 420                                 method_name = "Not";
 421                                 break;
 422                         case Operator.UnaryPlus:
 423                                 method_name = "UnaryPlus";
 424                                 break;
 425                         default:
 426                                 throw new InternalErrorException ("Unknown unary operator " + Oper.ToString ());
 427                         }
 428
 429                         Arguments args = new Arguments (2);
 430                         args.Add (new Argument (Expr.CreateExpressionTree (ec)));
 431                         if (user_op != null)
 432                                 args.Add (new Argument (user_op));
 433
 434                         return CreateExpressionFactoryCall (ec, method_name, args);
 435                 }
 436
 437                 public static TypeSpec[][] CreatePredefinedOperatorsTable (BuiltinTypes types)
 438                 {
 439                         var predefined_operators = new TypeSpec[(int) Operator.TOP][];
 440
 441                         //
 442                         // 7.6.1 Unary plus operator
 443                         //
 444                         predefined_operators [(int) Operator.UnaryPlus] = new TypeSpec [] {
 445                                 types.Int, types.UInt,
 446                                 types.Long, types.ULong,
 447                                 types.Float, types.Double,
 448                                 types.Decimal
 449                         };
 450
 451                         //
 452                         // 7.6.2 Unary minus operator
 453                         //
 454                         predefined_operators [(int) Operator.UnaryNegation] = new TypeSpec [] {
 455                                 types.Int,  types.Long,
 456                                 types.Float, types.Double,
 457                                 types.Decimal
 458                         };
 459
 460                         //
 461                         // 7.6.3 Logical negation operator
 462                         //
 463                         predefined_operators [(int) Operator.LogicalNot] = new TypeSpec [] {
 464                                 types.Bool
 465                         };
 466
 467                         //
 468                         // 7.6.4 Bitwise complement operator
 469                         //
 470                         predefined_operators [(int) Operator.OnesComplement] = new TypeSpec [] {
 471                                 types.Int, types.UInt,
 472                                 types.Long, types.ULong
 473                         };
 474
 475                         return predefined_operators;
 476                 }
 477
 478                 //
 479                 // Unary numeric promotions
 480                 //
 481                 static Expression DoNumericPromotion (ResolveContext rc, Operator op, Expression expr)
 482                 {
 483                         TypeSpec expr_type = expr.Type;
 484                         if (op == Operator.UnaryPlus || op == Operator.UnaryNegation || op == Operator.OnesComplement) {
 485                                 switch (expr_type.BuiltinType) {
 486                                 case BuiltinTypeSpec.Type.Byte:
 487                                 case BuiltinTypeSpec.Type.SByte:
 488                                 case BuiltinTypeSpec.Type.Short:
 489                                 case BuiltinTypeSpec.Type.UShort:
 490                                 case BuiltinTypeSpec.Type.Char:
 491                                         return Convert.ImplicitNumericConversion (expr, rc.BuiltinTypes.Int);
 492                                 }
 493                         }
 494
 495                         if (op == Operator.UnaryNegation && expr_type.BuiltinType == BuiltinTypeSpec.Type.UInt)
 496                                 return Convert.ImplicitNumericConversion (expr, rc.BuiltinTypes.Long);
 497
 498                         return expr;
 499                 }
 500
 501                 protected override Expression DoResolve (ResolveContext ec)
 502                 {
 503                         if (Oper == Operator.AddressOf) {
 504                                 return ResolveAddressOf (ec);
 505                         }
 506
 507                         Expr = Expr.Resolve (ec);
 508                         if (Expr == null)
 509                                 return null;
 510
 511                         if (Expr.Type.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
 512                                 Arguments args = new Arguments (1);
 513                                 args.Add (new Argument (Expr));
 514                                 return new DynamicUnaryConversion (GetOperatorExpressionTypeName (), args, loc).Resolve (ec);
 515                         }
 516
 517                         if (Expr.Type.IsNullableType)
 518                                 return new Nullable.LiftedUnaryOperator (Oper, Expr, loc).Resolve (ec);
 519
 520                         //
 521                         // Attempt to use a constant folding operation.
 522                         //
 523                         Constant cexpr = Expr as Constant;
 524                         if (cexpr != null) {
 525                                 cexpr = TryReduceConstant (ec, cexpr);
 526                                 if (cexpr != null)
 527                                         return cexpr;
 528                         }
 529
 530                         Expression expr = ResolveOperator (ec, Expr);
 531                         if (expr == null)
 532                                 Error_OperatorCannotBeApplied (ec, loc, OperName (Oper), Expr.Type);
 533
 534                         //
 535                         // Reduce unary operator on predefined types
 536                         //
 537                         if (expr == this && Oper == Operator.UnaryPlus)
 538                                 return Expr;
 539
 540                         return expr;
 541                 }
 542
 543                 public override Expression DoResolveLValue (ResolveContext ec, Expression right)
 544                 {
 545                         return null;
 546                 }
 547
 548                 public override void Emit (EmitContext ec)
 549                 {
 550                         EmitOperator (ec, type);
 551                 }
 552
 553                 protected void EmitOperator (EmitContext ec, TypeSpec type)
 554                 {
 555                         switch (Oper) {
 556                         case Operator.UnaryPlus:
 557                                 Expr.Emit (ec);
 558                                 break;
 559
 560                         case Operator.UnaryNegation:
 561                                 if (ec.HasSet (EmitContext.Options.CheckedScope) && !IsFloat (type)) {
 562                                         if (ec.HasSet (BuilderContext.Options.AsyncBody) && Expr.ContainsEmitWithAwait ())
 563                                                 Expr = Expr.EmitToField (ec);
 564
 565                                         ec.EmitInt (0);
 566                                         if (type.BuiltinType == BuiltinTypeSpec.Type.Long)
 567                                                 ec.Emit (OpCodes.Conv_U8);
 568                                         Expr.Emit (ec);
 569                                         ec.Emit (OpCodes.Sub_Ovf);
 570                                 } else {
 571                                         Expr.Emit (ec);
 572                                         ec.Emit (OpCodes.Neg);
 573                                 }
 574
 575                                 break;
 576
 577                         case Operator.LogicalNot:
 578                                 Expr.Emit (ec);
 579                                 ec.EmitInt (0);
 580                                 ec.Emit (OpCodes.Ceq);
 581                                 break;
 582
 583                         case Operator.OnesComplement:
 584                                 Expr.Emit (ec);
 585                                 ec.Emit (OpCodes.Not);
 586                                 break;
 587
 588                         case Operator.AddressOf:
 589                                 ((IMemoryLocation)Expr).AddressOf (ec, AddressOp.LoadStore);
 590                                 break;
 591
 592                         default:
 593                                 throw new Exception ("This should not happen: Operator = "
 594                                                      + Oper.ToString ());
 595                         }
 596
 597                         //
 598                         // Same trick as in Binary expression
 599                         //
 600                         if (enum_conversion != 0) {
 601                                 using (ec.With (BuilderContext.Options.CheckedScope, false)) {
 602                                         ConvCast.Emit (ec, enum_conversion);
 603                                 }
 604                         }
 605                 }
 606
 607                 public override void EmitBranchable (EmitContext ec, Label target, bool on_true)
 608                 {
 609                         if (Oper == Operator.LogicalNot)
 610                                 Expr.EmitBranchable (ec, target, !on_true);
 611                         else
 612                                 base.EmitBranchable (ec, target, on_true);
 613                 }
 614
 615                 public override void EmitSideEffect (EmitContext ec)
 616                 {
 617                         Expr.EmitSideEffect (ec);
 618                 }
 619
 620                 public static void Error_Ambiguous (ResolveContext rc, string oper, TypeSpec type, Location loc)
 621                 {
 622                         rc.Report.Error (35, loc, "Operator `{0}' is ambiguous on an operand of type `{1}'",
 623                                 oper, type.GetSignatureForError ());
 624                 }
 625
 626                 public override void FlowAnalysis (FlowAnalysisContext fc)
 627                 {
 628                         FlowAnalysis (fc, false);
 629                 }
 630
 631                 public override void FlowAnalysisConditional (FlowAnalysisContext fc)
 632                 {
 633                         FlowAnalysis (fc, true);
 634                 }
 635
 636                 void FlowAnalysis (FlowAnalysisContext fc, bool conditional)
 637                 {
 638                         if (Oper == Operator.AddressOf) {
 639                                 var vr = Expr as VariableReference;
 640                                 if (vr != null && vr.VariableInfo != null)
 641                                         fc.SetVariableAssigned (vr.VariableInfo);
 642
 643                                 return;
 644                         }
 645
 646                         if (Oper == Operator.LogicalNot && conditional) {
 647                                 Expr.FlowAnalysisConditional (fc);
 648
 649                                 var temp = fc.DefiniteAssignmentOnTrue;
 650                                 fc.DefiniteAssignmentOnTrue = fc.DefiniteAssignmentOnFalse;
 651                                 fc.DefiniteAssignmentOnFalse = temp;
 652                         } else {
 653                                 Expr.FlowAnalysis (fc);
 654                         }
 655                 }
 656
 657                 //
 658                 // Converts operator to System.Linq.Expressions.ExpressionType enum name
 659                 //
 660                 string GetOperatorExpressionTypeName ()
 661                 {
 662                         switch (Oper) {
 663                         case Operator.OnesComplement:
 664                                 return "OnesComplement";
 665                         case Operator.LogicalNot:
 666                                 return "Not";
 667                         case Operator.UnaryNegation:
 668                                 return "Negate";
 669                         case Operator.UnaryPlus:
 670                                 return "UnaryPlus";
 671                         default:
 672                                 throw new NotImplementedException ("Unknown express type operator " + Oper.ToString ());
 673                         }
 674                 }
 675
 676                 static bool IsFloat (TypeSpec t)
 677                 {
 678                         return t.BuiltinType == BuiltinTypeSpec.Type.Double || t.BuiltinType == BuiltinTypeSpec.Type.Float;
 679                 }
 680
 681                 //
 682                 // Returns a stringified representation of the Operator
 683                 //
 684                 public static string OperName (Operator oper)
 685                 {
 686                         switch (oper) {
 687                         case Operator.UnaryPlus:
 688                                 return "+";
 689                         case Operator.UnaryNegation:
 690                                 return "-";
 691                         case Operator.LogicalNot:
 692                                 return "!";
 693                         case Operator.OnesComplement:
 694                                 return "~";
 695                         case Operator.AddressOf:
 696                                 return "&";
 697                         }
 698
 699                         throw new NotImplementedException (oper.ToString ());
 700                 }
 701
 702                 public override SLE.Expression MakeExpression (BuilderContext ctx)
 703                 {
 704                         var expr = Expr.MakeExpression (ctx);
 705                         bool is_checked = ctx.HasSet (BuilderContext.Options.CheckedScope);
 706
 707                         switch (Oper) {
 708                         case Operator.UnaryNegation:
 709                                 return is_checked ? SLE.Expression.NegateChecked (expr) : SLE.Expression.Negate (expr);
 710                         case Operator.LogicalNot:
 711                                 return SLE.Expression.Not (expr);
 712                         case Operator.OnesComplement:
 713                                 return SLE.Expression.OnesComplement (expr);
 714                         default:
 715                                 throw new NotImplementedException (Oper.ToString ());
 716                         }
 717                 }
 718
 719                 Expression ResolveAddressOf (ResolveContext ec)
 720                 {
 721                         if (ec.CurrentIterator != null) {
 722                                 UnsafeInsideIteratorError (ec, loc);
 723                         } else if (!ec.IsUnsafe) {
 724                                 UnsafeError (ec, loc);
 725                         }
 726
 727                         Expr = Expr.DoResolveLValue (ec, EmptyExpression.UnaryAddress);
 728                         if (Expr == null || Expr.eclass != ExprClass.Variable) {
 729                                 ec.Report.Error (211, loc, "Cannot take the address of the given expression");
 730                                 return null;
 731                         }
 732
 733                         if (!TypeManager.VerifyUnmanaged (ec.Module, Expr.Type, loc)) {
 734                                 return null;
 735                         }
 736
 737                         IVariableReference vr = Expr as IVariableReference;
 738                         bool is_fixed;
 739                         if (vr != null) {
 740                                 is_fixed = vr.IsFixed;
 741                                 vr.SetHasAddressTaken ();
 742
 743                                 if (vr.IsHoisted && ec.CurrentIterator == null) {
 744                                         AnonymousMethodExpression.Error_AddressOfCapturedVar (ec, vr, loc);
 745                                 }
 746                         } else {
 747                                 IFixedExpression fe = Expr as IFixedExpression;
 748                                 is_fixed = fe != null && fe.IsFixed;
 749                         }
 750
 751                         if (!is_fixed && !ec.HasSet (ResolveContext.Options.FixedInitializerScope)) {
 752                                 ec.Report.Error (212, loc, "You can only take the address of unfixed expression inside of a fixed statement initializer");
 753                         }
 754
 755                         type = PointerContainer.MakeType (ec.Module, Expr.Type);
 756                         eclass = ExprClass.Value;
 757                         return this;
 758                 }
 759
 760                 Expression ResolvePrimitivePredefinedType (ResolveContext rc, Expression expr, TypeSpec[] predefined)
 761                 {
 762                         expr = DoNumericPromotion (rc, Oper, expr);
 763                         TypeSpec expr_type = expr.Type;
 764                         foreach (TypeSpec t in predefined) {
 765                                 if (t == expr_type)
 766                                         return expr;
 767                         }
 768                         return null;
 769                 }
 770
 771                 //
 772                 // Perform user-operator overload resolution
 773                 //
 774                 protected virtual Expression ResolveUserOperator (ResolveContext ec, Expression expr)
 775                 {
 776                         CSharp.Operator.OpType op_type;
 777                         switch (Oper) {
 778                         case Operator.LogicalNot:
 779                                 op_type = CSharp.Operator.OpType.LogicalNot; break;
 780                         case Operator.OnesComplement:
 781                                 op_type = CSharp.Operator.OpType.OnesComplement; break;
 782                         case Operator.UnaryNegation:
 783                                 op_type = CSharp.Operator.OpType.UnaryNegation; break;
 784                         case Operator.UnaryPlus:
 785                                 op_type = CSharp.Operator.OpType.UnaryPlus; break;
 786                         default:
 787                                 throw new InternalErrorException (Oper.ToString ());
 788                         }
 789
 790                         var methods = MemberCache.GetUserOperator (expr.Type, op_type, false);
 791                         if (methods == null)
 792                                 return null;
 793
 794                         Arguments args = new Arguments (1);
 795                         args.Add (new Argument (expr));
 796
 797                         var res = new OverloadResolver (methods, OverloadResolver.Restrictions.BaseMembersIncluded | OverloadResolver.Restrictions.NoBaseMembers, loc);
 798                         var oper = res.ResolveOperator (ec, ref args);
 799
 800                         if (oper == null)
 801                                 return null;
 802
 803                         Expr = args [0].Expr;
 804                         return new UserOperatorCall (oper, args, CreateExpressionTree, expr.Location);
 805                 }
 806
 807                 //
 808                 // Unary user type overload resolution
 809                 //
 810                 Expression ResolveUserType (ResolveContext ec, Expression expr, TypeSpec[] predefined)
 811                 {
 812                         Expression best_expr = ResolveUserOperator (ec, expr);
 813                         if (best_expr != null)
 814                                 return best_expr;
 815
 816                         foreach (TypeSpec t in predefined) {
 817                                 Expression oper_expr = Convert.ImplicitUserConversion (ec, expr, t, expr.Location);
 818                                 if (oper_expr == null)
 819                                         continue;
 820
 821                                 if (oper_expr == ErrorExpression.Instance)
 822                                         return oper_expr;
 823
 824                                 //
 825                                 // decimal type is predefined but has user-operators
 826                                 //
 827                                 if (oper_expr.Type.BuiltinType == BuiltinTypeSpec.Type.Decimal)
 828                                         oper_expr = ResolveUserType (ec, oper_expr, predefined);
 829                                 else
 830                                         oper_expr = ResolvePrimitivePredefinedType (ec, oper_expr, predefined);
 831
 832                                 if (oper_expr == null)
 833                                         continue;
 834
 835                                 if (best_expr == null) {
 836                                         best_expr = oper_expr;
 837                                         continue;
 838                                 }
 839
 840                                 int result = OverloadResolver.BetterTypeConversion (ec, best_expr.Type, t);
 841                                 if (result == 0) {
 842                                         if ((oper_expr is UserOperatorCall || oper_expr is UserCast) && (best_expr is UserOperatorCall || best_expr is UserCast)) {
 843                                                 Error_Ambiguous (ec, OperName (Oper), expr.Type, loc);
 844                                         } else {
 845                                                 Error_OperatorCannotBeApplied (ec, loc, OperName (Oper), expr.Type);
 846                                         }
 847
 848                                         break;
 849                                 }
 850
 851                                 if (result == 2)
 852                                         best_expr = oper_expr;
 853                         }
 854
 855                         if (best_expr == null)
 856                                 return null;
 857
 858                         //
 859                         // HACK: Decimal user-operator is included in standard operators
 860                         //
 861                         if (best_expr.Type.BuiltinType == BuiltinTypeSpec.Type.Decimal)
 862                                 return best_expr;
 863
 864                         Expr = best_expr;
 865                         type = best_expr.Type;
 866                         return this;
 867                 }
 868
 869                 protected override void CloneTo (CloneContext clonectx, Expression t)
 870                 {
 871                         Unary target = (Unary) t;
 872
 873                         target.Expr = Expr.Clone (clonectx);
 874                 }
 875
 876                 public override object Accept (StructuralVisitor visitor)
 877                 {
 878                         return visitor.Visit (this);
 879                 }
 880
 881         }
 882
 883         //
 884         // Unary operators are turned into Indirection expressions
 885         // after semantic analysis (this is so we can take the address
 886         // of an indirection).
 887         //
 888         public class Indirection : Expression, IMemoryLocation, IAssignMethod, IFixedExpression {
 889                 Expression expr;
 890                 LocalTemporary temporary;
 891                 bool prepared;
 892
 893                 public Indirection (Expression expr, Location l)
 894                 {
 895                         this.expr = expr;
 896                         loc = l;
 897                 }
 898
 899                 public Expression Expr {
 900                         get {
 901                                 return expr;
 902                         }
 903                 }
 904
 905                 public bool IsFixed {
 906                         get { return true; }
 907                 }
 908
 909                 public override Location StartLocation {
 910                         get {
 911                                 return expr.StartLocation;
 912                         }
 913                 }
 914
 915                 protected override void CloneTo (CloneContext clonectx, Expression t)
 916                 {
 917                         Indirection target = (Indirection) t;
 918                         target.expr = expr.Clone (clonectx);
 919                 }
 920
 921                 public override bool ContainsEmitWithAwait ()
 922                 {
 923                         throw new NotImplementedException ();
 924                 }
 925
 926                 public override Expression CreateExpressionTree (ResolveContext ec)
 927                 {
 928                         Error_PointerInsideExpressionTree (ec);
 929                         return null;
 930                 }
 931
 932                 public override void Emit (EmitContext ec)
 933                 {
 934                         if (!prepared)
 935                                 expr.Emit (ec);
 936
 937                         ec.EmitLoadFromPtr (Type);
 938                 }
 939
 940                 public void Emit (EmitContext ec, bool leave_copy)
 941                 {
 942                         Emit (ec);
 943                         if (leave_copy) {
 944                                 ec.Emit (OpCodes.Dup);
 945                                 temporary = new LocalTemporary (expr.Type);
 946                                 temporary.Store (ec);
 947                         }
 948                 }
 949
 950                 public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool isCompound)
 951                 {
 952                         prepared = isCompound;
 953
 954                         expr.Emit (ec);
 955
 956                         if (isCompound)
 957                                 ec.Emit (OpCodes.Dup);
 958
 959                         source.Emit (ec);
 960                         if (leave_copy) {
 961                                 ec.Emit (OpCodes.Dup);
 962                                 temporary = new LocalTemporary (source.Type);
 963                                 temporary.Store (ec);
 964                         }
 965
 966                         ec.EmitStoreFromPtr (type);
 967
 968                         if (temporary != null) {
 969                                 temporary.Emit (ec);
 970                                 temporary.Release (ec);
 971                         }
 972                 }
 973
 974                 public void AddressOf (EmitContext ec, AddressOp Mode)
 975                 {
 976                         expr.Emit (ec);
 977                 }
 978
 979                 public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
 980                 {
 981                         return DoResolve (ec);
 982                 }
 983
 984                 protected override Expression DoResolve (ResolveContext ec)
 985                 {
 986                         expr = expr.Resolve (ec);
 987                         if (expr == null)
 988                                 return null;
 989
 990                         if (ec.CurrentIterator != null) {
 991                                 UnsafeInsideIteratorError (ec, loc);
 992                         } else if (!ec.IsUnsafe) {
 993                                 UnsafeError (ec, loc);
 994                         }
 995
 996                         var pc = expr.Type as PointerContainer;
 997
 998                         if (pc == null) {
 999                                 ec.Report.Error (193, loc, "The * or -> operator must be applied to a pointer");
1000                                 return null;
1001                         }
1002
1003                         type = pc.Element;
1004
1005                         if (type.Kind == MemberKind.Void) {
1006                                 Error_VoidPointerOperation (ec);
1007                                 return null;
1008                         }
1009
1010                         eclass = ExprClass.Variable;
1011                         return this;
1012                 }
1013
1014                 public override object Accept (StructuralVisitor visitor)
1015                 {
1016                         return visitor.Visit (this);
1017                 }
1018         }
1019
1020         /// <summary>
1021         ///   Unary Mutator expressions (pre and post ++ and --)
1022         /// </summary>
1023         ///
1024         /// <remarks>
1025         ///   UnaryMutator implements ++ and -- expressions.   It derives from
1026         ///   ExpressionStatement becuase the pre/post increment/decrement
1027         ///   operators can be used in a statement context.
1028         ///
1029         /// FIXME: Idea, we could split this up in two classes, one simpler
1030         /// for the common case, and one with the extra fields for more complex
1031         /// classes (indexers require temporary access;  overloaded require method)
1032         ///
1033         /// </remarks>
1034         public class UnaryMutator : ExpressionStatement
1035         {
1036                 class DynamicPostMutator : Expression, IAssignMethod
1037                 {
1038                         LocalTemporary temp;
1039                         Expression expr;
1040
1041                         public DynamicPostMutator (Expression expr)
1042                         {
1043                                 this.expr = expr;
1044                                 this.type = expr.Type;
1045                                 this.loc = expr.Location;
1046                         }
1047
1048                         public override Expression CreateExpressionTree (ResolveContext ec)
1049                         {
1050                                 throw new NotImplementedException ("ET");
1051                         }
1052
1053                         protected override Expression DoResolve (ResolveContext rc)
1054                         {
1055                                 eclass = expr.eclass;
1056                                 return this;
1057                         }
1058
1059                         public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
1060                         {
1061                                 expr.DoResolveLValue (ec, right_side);
1062                                 return DoResolve (ec);
1063                         }
1064
1065                         public override void Emit (EmitContext ec)
1066                         {
1067                                 temp.Emit (ec);
1068                         }
1069
1070                         public void Emit (EmitContext ec, bool leave_copy)
1071                         {
1072                                 throw new NotImplementedException ();
1073                         }
1074
1075                         //
1076                         // Emits target assignment using unmodified source value
1077                         //
1078                         public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool isCompound)
1079                         {
1080                                 //
1081                                 // Allocate temporary variable to keep original value before it's modified
1082                                 //
1083                                 temp = new LocalTemporary (type);
1084                                 expr.Emit (ec);
1085                                 temp.Store (ec);
1086
1087                                 ((IAssignMethod) expr).EmitAssign (ec, source, false, isCompound);
1088
1089                                 if (leave_copy)
1090                                         Emit (ec);
1091
1092                                 temp.Release (ec);
1093                                 temp = null;
1094                         }
1095                 }
1096
1097                 [Flags]
1098                 public enum Mode : byte {
1099                         IsIncrement    = 0,
1100                         IsDecrement    = 1,
1101                         IsPre          = 0,
1102                         IsPost         = 2,
1103
1104                         PreIncrement   = 0,
1105                         PreDecrement   = IsDecrement,
1106                         PostIncrement  = IsPost,
1107                         PostDecrement  = IsPost | IsDecrement
1108                 }
1109
1110                 Mode mode;
1111                 bool is_expr, recurse;
1112
1113                 protected Expression expr;
1114
1115                 // Holds the real operation
1116                 Expression operation;
1117
1118                 public UnaryMutator (Mode m, Expression e, Location loc)
1119                 {
1120                         mode = m;
1121                         this.loc = loc;
1122                         expr = e;
1123                 }
1124
1125                 public Mode UnaryMutatorMode {
1126                         get {
1127                                 return mode;
1128                         }
1129                 }
1130
1131                 public Expression Expr {
1132                         get {
1133                                 return expr;
1134                         }
1135                 }
1136
1137                 public override Location StartLocation {
1138                         get {
1139                                 return (mode & Mode.IsPost) != 0 ? expr.Location : loc;
1140                         }
1141                 }
1142
1143                 public override bool ContainsEmitWithAwait ()
1144                 {
1145                         return expr.ContainsEmitWithAwait ();
1146                 }
1147
1148                 public override Expression CreateExpressionTree (ResolveContext ec)
1149                 {
1150                         return new SimpleAssign (this, this).CreateExpressionTree (ec);
1151                 }
1152
1153                 public static TypeSpec[] CreatePredefinedOperatorsTable (BuiltinTypes types)
1154                 {
1155                         //
1156                         // Predefined ++ and -- operators exist for the following types:
1157                         // sbyte, byte, short, ushort, int, uint, long, ulong, char, float, double, decimal
1158                         //
1159                         return new TypeSpec[] {
1160                                 types.Int,
1161                                 types.Long,
1162
1163                                 types.SByte,
1164                                 types.Byte,
1165                                 types.Short,
1166                                 types.UInt,
1167                                 types.ULong,
1168                                 types.Char,
1169                                 types.Float,
1170                                 types.Double,
1171                                 types.Decimal
1172                         };
1173                 }
1174
1175                 protected override Expression DoResolve (ResolveContext ec)
1176                 {
1177                         expr = expr.Resolve (ec);
1178
1179                         if (expr == null || expr.Type == InternalType.ErrorType)
1180                                 return null;
1181
1182                         if (expr.Type.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
1183                                 //
1184                                 // Handle postfix unary operators using local
1185                                 // temporary variable
1186                                 //
1187                                 if ((mode & Mode.IsPost) != 0)
1188                                         expr = new DynamicPostMutator (expr);
1189
1190                                 Arguments args = new Arguments (1);
1191                                 args.Add (new Argument (expr));
1192                                 return new SimpleAssign (expr, new DynamicUnaryConversion (GetOperatorExpressionTypeName (), args, loc)).Resolve (ec);
1193                         }
1194
1195                         if (expr.Type.IsNullableType)
1196                                 return new Nullable.LiftedUnaryMutator (mode, expr, loc).Resolve (ec);
1197
1198                         return DoResolveOperation (ec);
1199                 }
1200
1201                 protected Expression DoResolveOperation (ResolveContext ec)
1202                 {
1203                         eclass = ExprClass.Value;
1204                         type = expr.Type;
1205
1206                         if (expr is RuntimeValueExpression) {
1207                                 operation = expr;
1208                         } else {
1209                                 // Use itself at the top of the stack
1210                                 operation = new EmptyExpression (type);
1211                         }
1212
1213                         //
1214                         // The operand of the prefix/postfix increment decrement operators
1215                         // should be an expression that is classified as a variable,
1216                         // a property access or an indexer access
1217                         //
1218                         // TODO: Move to parser, expr is ATypeNameExpression
1219                         if (expr.eclass == ExprClass.Variable || expr.eclass == ExprClass.IndexerAccess || expr.eclass == ExprClass.PropertyAccess) {
1220                                 expr = expr.ResolveLValue (ec, expr);
1221                         } else {
1222                                 ec.Report.Error (1059, loc, "The operand of an increment or decrement operator must be a variable, property or indexer");
1223                         }
1224
1225                         //
1226                         // Step 1: Try to find a user operator, it has priority over predefined ones
1227                         //
1228                         var user_op = IsDecrement ? Operator.OpType.Decrement : Operator.OpType.Increment;
1229                         var methods = MemberCache.GetUserOperator (type, user_op, false);
1230
1231                         if (methods != null) {
1232                                 Arguments args = new Arguments (1);
1233                                 args.Add (new Argument (expr));
1234
1235                                 var res = new OverloadResolver (methods, OverloadResolver.Restrictions.BaseMembersIncluded | OverloadResolver.Restrictions.NoBaseMembers, loc);
1236                                 var method = res.ResolveOperator (ec, ref args);
1237                                 if (method == null)
1238                                         return null;
1239
1240                                 args[0].Expr = operation;
1241                                 operation = new UserOperatorCall (method, args, null, loc);
1242                                 operation = Convert.ImplicitConversionRequired (ec, operation, type, loc);
1243                                 return this;
1244                         }
1245
1246                         //
1247                         // Step 2: Try predefined types
1248                         //
1249
1250                         Expression source = null;
1251                         bool primitive_type;
1252
1253                         //
1254                         // Predefined without user conversion first for speed-up
1255                         //
1256                         // Predefined ++ and -- operators exist for the following types:
1257                         // sbyte, byte, short, ushort, int, uint, long, ulong, char, float, double, decimal
1258                         //
1259                         switch (type.BuiltinType) {
1260                         case BuiltinTypeSpec.Type.Byte:
1261                         case BuiltinTypeSpec.Type.SByte:
1262                         case BuiltinTypeSpec.Type.Short:
1263                         case BuiltinTypeSpec.Type.UShort:
1264                         case BuiltinTypeSpec.Type.Int:
1265                         case BuiltinTypeSpec.Type.UInt:
1266                         case BuiltinTypeSpec.Type.Long:
1267                         case BuiltinTypeSpec.Type.ULong:
1268                         case BuiltinTypeSpec.Type.Char:
1269                         case BuiltinTypeSpec.Type.Float:
1270                         case BuiltinTypeSpec.Type.Double:
1271                         case BuiltinTypeSpec.Type.Decimal:
1272                                 source = operation;
1273                                 primitive_type = true;
1274                                 break;
1275                         default:
1276                                 primitive_type = false;
1277
1278                                 // ++/-- on pointer variables of all types except void*
1279                                 if (type.IsPointer) {
1280                                         if (((PointerContainer) type).Element.Kind == MemberKind.Void) {
1281                                                 Error_VoidPointerOperation (ec);
1282                                                 return null;
1283                                         }
1284
1285                                         source = operation;
1286                                 } else {
1287                                         Expression best_source = null;
1288                                         foreach (var t in ec.BuiltinTypes.OperatorsUnaryMutator) {
1289                                                 source = Convert.ImplicitUserConversion (ec, operation, t, loc);
1290
1291                                                 // LAMESPEC: It should error on ambiguous operators but that would make us incompatible
1292                                                 if (source == null)
1293                                                         continue;
1294
1295                                                 if (best_source == null) {
1296                                                         best_source = source;
1297                                                         continue;
1298                                                 }
1299
1300                                                 var better = OverloadResolver.BetterTypeConversion (ec, best_source.Type, source.Type);
1301                                                 if (better == 1)
1302                                                         continue;
1303
1304                                                 if (better == 2) {
1305                                                         best_source = source;
1306                                                         continue;
1307                                                 }
1308
1309                                                 Unary.Error_Ambiguous (ec, OperName (mode), type, loc);
1310                                                 break;
1311                                         }
1312
1313                                         source = best_source;
1314                                 }
1315
1316                                 // ++/-- on enum types
1317                                 if (source == null && type.IsEnum)
1318                                         source = operation;
1319
1320                                 if (source == null) {
1321                                         expr.Error_OperatorCannotBeApplied (ec, loc, Operator.GetName (user_op), type);
1322                                         return null;
1323                                 }
1324
1325                                 break;
1326                         }
1327
1328                         var one = new IntConstant (ec.BuiltinTypes, 1, loc);
1329                         var op = IsDecrement ? Binary.Operator.Subtraction : Binary.Operator.Addition;
1330                         operation = new Binary (op, source, one);
1331                         operation = operation.Resolve (ec);
1332                         if (operation == null)
1333                                 throw new NotImplementedException ("should not be reached");
1334
1335                         if (operation.Type != type) {
1336                                 if (primitive_type)
1337                                         operation = Convert.ExplicitNumericConversion (ec, operation, type);
1338                                 else
1339                                         operation = Convert.ImplicitConversionRequired (ec, operation, type, loc);
1340                         }
1341
1342                         return this;
1343                 }
1344
1345                 void EmitCode (EmitContext ec, bool is_expr)
1346                 {
1347                         recurse = true;
1348                         this.is_expr = is_expr;
1349                         ((IAssignMethod) expr).EmitAssign (ec, this, is_expr && (mode == Mode.PreIncrement || mode == Mode.PreDecrement), true);
1350                 }
1351
1352                 public override void Emit (EmitContext ec)
1353                 {
1354                         //
1355                         // We use recurse to allow ourselfs to be the source
1356                         // of an assignment. This little hack prevents us from
1357                         // having to allocate another expression
1358                         //
1359                         if (recurse) {
1360                                 ((IAssignMethod) expr).Emit (ec, is_expr && (mode == Mode.PostIncrement || mode == Mode.PostDecrement));
1361
1362                                 EmitOperation (ec);
1363
1364                                 recurse = false;
1365                                 return;
1366                         }
1367
1368                         EmitCode (ec, true);
1369                 }
1370
1371                 protected virtual void EmitOperation (EmitContext ec)
1372                 {
1373                         operation.Emit (ec);
1374                 }
1375
1376                 public override void EmitStatement (EmitContext ec)
1377                 {
1378                         EmitCode (ec, false);
1379                 }
1380
1381                 public override void FlowAnalysis (FlowAnalysisContext fc)
1382                 {
1383                         expr.FlowAnalysis (fc);
1384                 }
1385
1386                 //
1387                 // Converts operator to System.Linq.Expressions.ExpressionType enum name
1388                 //
1389                 string GetOperatorExpressionTypeName ()
1390                 {
1391                         return IsDecrement ? "Decrement" : "Increment";
1392                 }
1393
1394                 bool IsDecrement {
1395                         get { return (mode & Mode.IsDecrement) != 0; }
1396                 }
1397
1398
1399                 public override SLE.Expression MakeExpression (BuilderContext ctx)
1400                 {
1401                         var target = ((RuntimeValueExpression) expr).MetaObject.Expression;
1402                         var source = SLE.Expression.Convert (operation.MakeExpression (ctx), target.Type);
1403                         return SLE.Expression.Assign (target, source);
1404                 }
1405
1406                 public static string OperName (Mode oper)
1407                 {
1408                         return (oper & Mode.IsDecrement) != 0 ? "--" : "++";
1409                 }
1410
1411                 protected override void CloneTo (CloneContext clonectx, Expression t)
1412                 {
1413                         UnaryMutator target = (UnaryMutator) t;
1414
1415                         target.expr = expr.Clone (clonectx);
1416                 }
1417
1418                 public override object Accept (StructuralVisitor visitor)
1419                 {
1420                         return visitor.Visit (this);
1421                 }
1422
1423         }
1424
1425         //
1426         // Base class for the `is' and `as' operators
1427         //
1428         public abstract class Probe : Expression
1429         {
1430                 public Expression ProbeType;
1431                 protected Expression expr;
1432                 protected TypeSpec probe_type_expr;
1433
1434                 protected Probe (Expression expr, Expression probe_type, Location l)
1435                 {
1436                         ProbeType = probe_type;
1437                         loc = l;
1438                         this.expr = expr;
1439                 }
1440
1441                 public Expression Expr {
1442                         get {
1443                                 return expr;
1444                         }
1445                 }
1446
1447                 public override bool ContainsEmitWithAwait ()
1448                 {
1449                         return expr.ContainsEmitWithAwait ();
1450                 }
1451
1452                 protected Expression ResolveCommon (ResolveContext rc)
1453                 {
1454                         expr = expr.Resolve (rc);
1455                         if (expr == null)
1456                                 return null;
1457
1458                         ResolveProbeType (rc);
1459                         if (probe_type_expr == null)
1460                                 return this;
1461
1462                         if (probe_type_expr.IsStatic) {
1463                                 rc.Report.Error (7023, loc, "The second operand of `is' or `as' operator cannot be static type `{0}'",
1464                                         probe_type_expr.GetSignatureForError ());
1465                                 return null;
1466                         }
1467
1468                         if (expr.Type.IsPointer || probe_type_expr.IsPointer) {
1469                                 rc.Report.Error (244, loc, "The `{0}' operator cannot be applied to an operand of pointer type",
1470                                         OperatorName);
1471                                 return null;
1472                         }
1473
1474                         if (expr.Type == InternalType.AnonymousMethod || expr.Type == InternalType.MethodGroup) {
1475                                 rc.Report.Error (837, loc, "The `{0}' operator cannot be applied to a lambda expression, anonymous method, or method group",
1476                                         OperatorName);
1477                                 return null;
1478                         }
1479
1480                         return this;
1481                 }
1482
1483                 protected virtual void ResolveProbeType (ResolveContext rc)
1484                 {
1485                         probe_type_expr = ProbeType.ResolveAsType (rc);
1486                 }
1487
1488                 public override void EmitSideEffect (EmitContext ec)
1489                 {
1490                         expr.EmitSideEffect (ec);
1491                 }
1492
1493                 public override void EmitPrepare (EmitContext ec)
1494                 {
1495                         expr.EmitPrepare (ec);
1496                 }
1497
1498                 public override void FlowAnalysis (FlowAnalysisContext fc)
1499                 {
1500                         expr.FlowAnalysis (fc);
1501                 }
1502
1503                 public override bool HasConditionalAccess ()
1504                 {
1505                         return expr.HasConditionalAccess ();
1506                 }
1507
1508                 protected abstract string OperatorName { get; }
1509
1510                 protected override void CloneTo (CloneContext clonectx, Expression t)
1511                 {
1512                         Probe target = (Probe) t;
1513
1514                         target.expr = expr.Clone (clonectx);
1515                         target.ProbeType = ProbeType.Clone (clonectx);
1516                 }
1517
1518         }
1519
1520         /// <summary>
1521         ///   Implementation of the `is' operator.
1522         /// </summary>
1523         public class Is : Probe
1524         {
1525                 Nullable.Unwrap expr_unwrap;
1526                 MethodSpec number_mg;
1527                 Arguments number_args;
1528
1529                 public Is (Expression expr, Expression probe_type, Location l)
1530                         : base (expr, probe_type, l)
1531                 {
1532                 }
1533
1534                 protected override string OperatorName {
1535                         get { return "is"; }
1536                 }
1537
1538                 public LocalVariable Variable { get; set; }
1539
1540                 public override Expression CreateExpressionTree (ResolveContext ec)
1541                 {
1542                         if (Variable != null)
1543                                 ec.Report.Error (8122, loc, "An expression tree cannot contain a pattern matching operator");
1544
1545                         Arguments args = Arguments.CreateForExpressionTree (ec, null,
1546                                 expr.CreateExpressionTree (ec),
1547                                 new TypeOf (probe_type_expr, loc));
1548
1549                         return CreateExpressionFactoryCall (ec, "TypeIs", args);
1550                 }
1551
1552                 Expression CreateConstantResult (ResolveContext rc, bool result)
1553                 {
1554                         if (result)
1555                                 rc.Report.Warning (183, 1, loc, "The given expression is always of the provided (`{0}') type",
1556                                         probe_type_expr.GetSignatureForError ());
1557                         else
1558                                 rc.Report.Warning (184, 1, loc, "The given expression is never of the provided (`{0}') type",
1559                                         probe_type_expr.GetSignatureForError ());
1560
1561                         var c = new BoolConstant (rc.BuiltinTypes, result, loc);
1562                         return expr.IsSideEffectFree ?
1563                                 ReducedExpression.Create (c, this) :
1564                                 new SideEffectConstant (c, this, loc);
1565                 }
1566
1567                 public override void Emit (EmitContext ec)
1568                 {
1569                         if (probe_type_expr == null) {
1570                                 if (ProbeType is WildcardPattern) {
1571                                         expr.EmitSideEffect (ec);
1572                                         ProbeType.Emit (ec);
1573                                 } else {
1574                                         EmitPatternMatch (ec);
1575                                 }
1576                                 return;
1577                         }
1578
1579                         EmitLoad (ec);
1580
1581                         if (expr_unwrap == null) {
1582                                 ec.EmitNull ();
1583                                 ec.Emit (OpCodes.Cgt_Un);
1584                         }
1585                 }
1586
1587                 public override void EmitBranchable (EmitContext ec, Label target, bool on_true)
1588                 {
1589                         if (probe_type_expr == null) {
1590                                 EmitPatternMatch (ec);
1591                         } else {
1592                                 EmitLoad (ec);
1593                         }
1594
1595                         ec.Emit (on_true ? OpCodes.Brtrue : OpCodes.Brfalse, target);
1596                 }
1597
1598                 public override void EmitPrepare (EmitContext ec)
1599                 {
1600                         base.EmitPrepare (ec);
1601
1602                         if (Variable != null)
1603                                 Variable.CreateBuilder (ec);
1604                 }
1605
1606                 void EmitPatternMatch (EmitContext ec)
1607                 {
1608                         var no_match = ec.DefineLabel ();
1609                         var end = ec.DefineLabel ();
1610
1611                         if (expr_unwrap != null) {
1612                                 expr_unwrap.EmitCheck (ec);
1613
1614                                 if (ProbeType.IsNull) {
1615                                         ec.EmitInt (0);
1616                                         ec.Emit (OpCodes.Ceq);
1617                                         return;
1618                                 }
1619
1620                                 ec.Emit (OpCodes.Brfalse_S, no_match);
1621                                 expr_unwrap.Emit (ec);
1622                                 ProbeType.Emit (ec);
1623                                 ec.Emit (OpCodes.Ceq);
1624                                 ec.Emit (OpCodes.Br_S, end);
1625                                 ec.MarkLabel (no_match);
1626                                 ec.EmitInt (0);
1627                                 ec.MarkLabel (end);
1628                                 return;
1629                         }
1630
1631                         if (number_args != null && number_args.Count == 3) {
1632                                 var ce = new CallEmitter ();
1633                                 ce.Emit (ec, number_mg, number_args, loc);
1634                                 return;
1635                         }
1636
1637                         var probe_type = ProbeType.Type;
1638
1639                         Expr.Emit (ec);
1640                         ec.Emit (OpCodes.Isinst, probe_type);
1641                         ec.Emit (OpCodes.Dup);
1642                         ec.Emit (OpCodes.Brfalse, no_match);
1643
1644                         bool complex_pattern = ProbeType is ComplexPatternExpression;
1645                         Label prev = ec.RecursivePatternLabel;
1646                         if (complex_pattern)
1647                                 ec.RecursivePatternLabel = ec.DefineLabel ();
1648
1649                         if (number_mg != null) {
1650                                 var ce = new CallEmitter ();
1651                                 ce.Emit (ec, number_mg, number_args, loc);
1652                         } else {
1653                                 if (TypeSpec.IsValueType (probe_type))
1654                                         ec.Emit (OpCodes.Unbox_Any, probe_type);
1655
1656                                 ProbeType.Emit (ec);
1657                                 if (complex_pattern) {
1658                                         ec.EmitInt (1);
1659                                 } else {
1660                                         ec.Emit (OpCodes.Ceq);
1661                                 }
1662                         }
1663                         ec.Emit (OpCodes.Br_S, end);
1664                         ec.MarkLabel (no_match);
1665
1666                         ec.Emit (OpCodes.Pop);
1667
1668                         if (complex_pattern)
1669                                 ec.MarkLabel (ec.RecursivePatternLabel);
1670
1671                         ec.RecursivePatternLabel = prev;
1672
1673                         ec.EmitInt (0);
1674                         ec.MarkLabel (end);
1675                 }
1676
1677                 void EmitLoad (EmitContext ec)
1678                 {
1679                         Label no_value_label = new Label ();
1680
1681                         if (expr_unwrap != null) {
1682                                 expr_unwrap.EmitCheck (ec);
1683
1684                                 if (Variable == null)
1685                                         return;
1686
1687                                 ec.Emit (OpCodes.Dup);
1688                                 no_value_label = ec.DefineLabel ();
1689                                 ec.Emit (OpCodes.Brfalse_S, no_value_label);
1690
1691                                 if (Variable.HoistedVariant != null)
1692                                         ec.EmitThis ();
1693
1694                                 expr_unwrap.Emit (ec);
1695                         } else {
1696                                 if (Variable?.HoistedVariant != null)
1697                                         ec.EmitThis ();
1698
1699                                 expr.Emit (ec);
1700
1701                                 // Only to make verifier happy
1702                                 if (probe_type_expr.IsGenericParameter && TypeSpec.IsValueType (expr.Type))
1703                                         ec.Emit (OpCodes.Box, expr.Type);
1704
1705                                 ec.Emit (OpCodes.Isinst, probe_type_expr);
1706                         }
1707
1708                         if (Variable != null) {
1709                                 bool value_on_stack;
1710                                 if (probe_type_expr.IsGenericParameter || probe_type_expr.IsNullableType) {
1711                                         ec.Emit (OpCodes.Dup);
1712                                         ec.Emit (OpCodes.Unbox_Any, probe_type_expr);
1713                                         value_on_stack = true;
1714                                 } else {
1715                                         value_on_stack = false;
1716                                 }
1717
1718                                 if (Variable.HoistedVariant != null) {
1719                                         Variable.HoistedVariant.EmitAssignFromStack (ec);
1720
1721                                         if (expr_unwrap != null) {
1722                                                 ec.MarkLabel (no_value_label);
1723                                         } else if (!value_on_stack) {
1724                                                 Variable.HoistedVariant.Emit (ec);
1725                                         }
1726                                 } else {
1727                                         //
1728                                         // It's ok to have variable builder created out of order. It simplifies emit
1729                                         // of statements like while (condition) { }
1730                                         //
1731                                         if (!Variable.Created)
1732                                                 Variable.CreateBuilder (ec);
1733
1734                                         Variable.EmitAssign (ec);
1735
1736                                         if (expr_unwrap != null) {
1737                                                 ec.MarkLabel (no_value_label);
1738                                         } else if (!value_on_stack) {
1739                                                 Variable.Emit (ec);
1740                                         }
1741                                 }
1742                         }
1743                 }
1744
1745                 protected override Expression DoResolve (ResolveContext rc)
1746                 {
1747                         if (ResolveCommon (rc) == null)
1748                                 return null;
1749
1750                         type = rc.BuiltinTypes.Bool;
1751                         eclass = ExprClass.Value;
1752
1753                         if (probe_type_expr == null)
1754                                 return ResolveMatchingExpression (rc);
1755
1756                         var res = ResolveResultExpression (rc);
1757                         if (Variable != null) {
1758                                 if (res is Constant)
1759                                         throw new NotImplementedException ("constant in type pattern matching");
1760
1761                                 Variable.Type = probe_type_expr;
1762                                 var bc = rc as BlockContext;
1763                                 if (bc != null)
1764                                         Variable.PrepareAssignmentAnalysis (bc);
1765                         }
1766
1767                         return res;
1768                 }
1769
1770                 public override void FlowAnalysis (FlowAnalysisContext fc)
1771                 {
1772                         base.FlowAnalysis (fc);
1773
1774                         if (Variable != null)
1775                                 fc.SetVariableAssigned (Variable.VariableInfo, true);
1776                 }
1777
1778                 public override void FlowAnalysisConditional (FlowAnalysisContext fc)
1779                 {
1780                         if (Variable == null) {
1781                                 base.FlowAnalysisConditional (fc);
1782                                 return;
1783                         }
1784
1785                         expr.FlowAnalysis (fc);
1786
1787                         fc.DefiniteAssignmentOnTrue = fc.BranchDefiniteAssignment ();
1788                         fc.DefiniteAssignmentOnFalse = fc.DefiniteAssignment;
1789
1790                         fc.SetVariableAssigned (Variable.VariableInfo, fc.DefiniteAssignmentOnTrue);
1791                 }
1792
1793                 protected override void ResolveProbeType (ResolveContext rc)
1794                 {
1795                         if (!(ProbeType is TypeExpr) && rc.Module.Compiler.Settings.Version == LanguageVersion.Experimental) {
1796                                 if (ProbeType is PatternExpression) {
1797                                         ProbeType.Resolve (rc);
1798                                         return;
1799                                 }
1800
1801                                 //
1802                                 // Have to use session recording because we don't have reliable type probing
1803                                 // mechanism (similar issue as in attributes resolving)
1804                                 //
1805                                 // TODO: This is still wrong because ResolveAsType can be destructive
1806                                 //
1807                                 var type_printer = new SessionReportPrinter ();
1808                                 var prev_recorder = rc.Report.SetPrinter (type_printer);
1809
1810                                 probe_type_expr = ProbeType.ResolveAsType (rc);
1811                                 type_printer.EndSession ();
1812
1813                                 if (probe_type_expr != null) {
1814                                         type_printer.Merge (rc.Report.Printer);
1815                                         rc.Report.SetPrinter (prev_recorder);
1816                                         return;
1817                                 }
1818
1819                                 var vexpr = ProbeType as VarExpr;
1820                                 if (vexpr != null && vexpr.InferType (rc, expr)) {
1821                                         probe_type_expr = vexpr.Type;
1822                                         rc.Report.SetPrinter (prev_recorder);
1823                                         return;
1824                                 }
1825
1826                                 var expr_printer = new SessionReportPrinter ();
1827                                 rc.Report.SetPrinter (expr_printer);
1828                                 ProbeType = ProbeType.Resolve (rc);
1829                                 expr_printer.EndSession ();
1830
1831                                 if (ProbeType != null) {
1832                                         expr_printer.Merge (rc.Report.Printer);
1833                                 } else {
1834                                         type_printer.Merge (rc.Report.Printer);
1835                                 }
1836
1837                                 rc.Report.SetPrinter (prev_recorder);
1838                                 return;
1839                         }
1840
1841                         base.ResolveProbeType (rc);
1842                 }
1843
1844                 Expression ResolveMatchingExpression (ResolveContext rc)
1845                 {
1846                         var mc = ProbeType as Constant;
1847                         if (mc != null) {
1848                                 if (!Convert.ImplicitConversionExists (rc, ProbeType, Expr.Type)) {
1849                                         ProbeType.Error_ValueCannotBeConverted (rc, Expr.Type, false);
1850                                         return null;
1851                                 }
1852
1853                                 if (mc.IsNull)
1854                                         return new Binary (Binary.Operator.Equality, Expr, mc).Resolve (rc);
1855
1856                                 var c = Expr as Constant;
1857                                 if (c != null) {
1858                                         c = ConstantFold.BinaryFold (rc, Binary.Operator.Equality, c, mc, loc);
1859                                         if (c != null)
1860                                                 return c;
1861                                 }
1862
1863                                 if (Expr.Type.IsNullableType) {
1864                                         expr_unwrap = new Nullable.Unwrap (Expr);
1865                                         expr_unwrap.Resolve (rc);
1866                                         ProbeType = Convert.ImplicitConversion (rc, ProbeType, expr_unwrap.Type, loc);
1867                                 } else if (ProbeType.Type == Expr.Type) {
1868                                         // TODO: Better error handling
1869                                         return new Binary (Binary.Operator.Equality, Expr, mc, loc).Resolve (rc);
1870                                 } else if (ProbeType.Type.IsEnum || (ProbeType.Type.BuiltinType >= BuiltinTypeSpec.Type.Byte && ProbeType.Type.BuiltinType <= BuiltinTypeSpec.Type.Decimal)) {
1871                                         var helper = rc.Module.CreatePatterMatchingHelper ();
1872                                         number_mg = helper.NumberMatcher.Spec;
1873
1874                                         //
1875                                         // There are actually 3 arguments but the first one is already on the stack
1876                                         //
1877                                         number_args = new Arguments (3);
1878                                         if (!ProbeType.Type.IsEnum)
1879                                                 number_args.Add (new Argument (Expr));
1880
1881                                         number_args.Add (new Argument (Convert.ImplicitConversion (rc, ProbeType, rc.BuiltinTypes.Object, loc)));
1882                                         number_args.Add (new Argument (new BoolLiteral (rc.BuiltinTypes, ProbeType.Type.IsEnum, loc)));
1883                                 }
1884
1885                                 return this;
1886                         }
1887
1888                         if (ProbeType is PatternExpression) {
1889                                 if (!(ProbeType is WildcardPattern) && !Convert.ImplicitConversionExists (rc, ProbeType, Expr.Type)) {
1890                                         ProbeType.Error_ValueCannotBeConverted (rc, Expr.Type, false);
1891                                 }
1892
1893                                 return this;
1894                         }
1895
1896                         // TODO: Better error message
1897                         rc.Report.Error (150, ProbeType.Location, "A constant value is expected");
1898                         return this;
1899                 }
1900
1901                 Expression ResolveResultExpression (ResolveContext ec)
1902                 {
1903                         if (Variable != null) {
1904                                 if (expr is NullLiteral) {
1905                                         ec.Report.Error (8117, loc, "Cannot use null as pattern matching operand");
1906                                         return this;
1907                                 }
1908
1909                                 CheckExpressionVariable (ec);
1910                         }
1911
1912                         TypeSpec d = expr.Type;
1913                         bool d_is_nullable = false;
1914
1915                         //
1916                         // If E is a method group or the null literal, or if the type of E is a reference
1917                         // type or a nullable type and the value of E is null, the result is false
1918                         //
1919                         if (expr.IsNull)
1920                                 return CreateConstantResult (ec, false);
1921
1922                         if (d.IsNullableType) {
1923                                 var ut = Nullable.NullableInfo.GetUnderlyingType (d);
1924                                 if (!ut.IsGenericParameter) {
1925                                         d = ut;
1926                                         d_is_nullable = true;
1927                                 }
1928                         }
1929
1930                         TypeSpec t = probe_type_expr;
1931                         bool t_is_nullable = false;
1932                         if (t.IsNullableType) {
1933                                 if (Variable != null) {
1934                                         ec.Report.Error (8116, loc, "The nullable type `{0}' pattern matching is not allowed. Consider using underlying type `{1}'",
1935                                                                          t.GetSignatureForError (), Nullable.NullableInfo.GetUnderlyingType (t).GetSignatureForError ());
1936                                 }
1937
1938                                 var ut = Nullable.NullableInfo.GetUnderlyingType (t);
1939                                 if (!ut.IsGenericParameter) {
1940                                         t = ut;
1941                                         t_is_nullable = true;
1942                                 }
1943                         }
1944
1945                         if (t.IsStruct) {
1946                                 if (d == t) {
1947                                         //
1948                                         // D and T are the same value types but D can be null
1949                                         //
1950                                         if (d_is_nullable && !t_is_nullable) {
1951                                                 expr_unwrap = Nullable.Unwrap.Create (expr, true);
1952                                                 return this;
1953                                         }
1954
1955                                         //
1956                                         // The result is true if D and T are the same value types
1957                                         //
1958                                         return CreateConstantResult (ec, true);
1959                                 }
1960
1961                                 var tp = d as TypeParameterSpec;
1962                                 if (tp != null)
1963                                         return ResolveGenericParameter (ec, t, tp);
1964
1965                                 //
1966                                 // An unboxing conversion exists
1967                                 //
1968                                 if (Convert.ExplicitReferenceConversionExists (d, t))
1969                                         return this;
1970
1971                                 //
1972                                 // open generic type
1973                                 //
1974                                 if (d is InflatedTypeSpec && InflatedTypeSpec.ContainsTypeParameter (d))
1975                                         return this;
1976                         } else {
1977                                 var tps = t as TypeParameterSpec;
1978                                 if (tps != null)
1979                                         return ResolveGenericParameter (ec, d, tps);
1980
1981                                 if (t.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
1982                                         if (Variable != null) {
1983                                                 ec.Report.Error (8208, loc, "The type `{0}' pattern matching is not allowed", t.GetSignatureForError ());
1984                                         } else {
1985                                                 ec.Report.Warning (1981, 3, loc,
1986                                                         "Using `{0}' to test compatibility with `{1}' is identical to testing compatibility with `object'",
1987                                                         OperatorName, t.GetSignatureForError ());
1988                                         }
1989                                 }
1990
1991                                 if (TypeManager.IsGenericParameter (d))
1992                                         return ResolveGenericParameter (ec, t, (TypeParameterSpec) d);
1993
1994                                 if (TypeSpec.IsValueType (d)) {
1995                                         if (Convert.ImplicitBoxingConversion (null, d, t) != null) {
1996                                                 if (d_is_nullable && !t_is_nullable) {
1997                                                         expr_unwrap = Nullable.Unwrap.Create (expr, false);
1998                                                         return this;
1999                                                 }
2000
2001                                                 return CreateConstantResult (ec, true);
2002                                         }
2003                                 } else {
2004                                         if (Convert.ImplicitReferenceConversionExists (d, t)) {
2005                                                 var c = expr as Constant;
2006                                                 if (c != null)
2007                                                         return CreateConstantResult (ec, !c.IsNull);
2008
2009                                                 //
2010                                                 // Do not optimize for imported type or dynamic type
2011                                                 //
2012                                                 if (d.MemberDefinition.IsImported && d.BuiltinType != BuiltinTypeSpec.Type.None &&
2013                                                         d.MemberDefinition.DeclaringAssembly != t.MemberDefinition.DeclaringAssembly) {
2014                                                         return this;
2015                                                 }
2016
2017                                                 if (d.BuiltinType == BuiltinTypeSpec.Type.Dynamic)
2018                                                         return this;
2019
2020                                                 //
2021                                                 // Turn is check into simple null check for implicitly convertible reference types
2022                                                 //
2023                                                 return ReducedExpression.Create (
2024                                                         new Binary (Binary.Operator.Inequality, expr, new NullLiteral (loc), Binary.State.UserOperatorsExcluded).Resolve (ec),
2025                                                         this).Resolve (ec);
2026                                         }
2027
2028                                         if (Convert.ExplicitReferenceConversionExists (d, t))
2029                                                 return this;
2030
2031                                         //
2032                                         // open generic type
2033                                         //
2034                                         if ((d is InflatedTypeSpec || d.IsArray) && InflatedTypeSpec.ContainsTypeParameter (d))
2035                                                 return this;
2036                                 }
2037                         }
2038
2039                         return CreateConstantResult (ec, false);
2040                 }
2041
2042                 Expression ResolveGenericParameter (ResolveContext ec, TypeSpec d, TypeParameterSpec t)
2043                 {
2044                         if (t.IsReferenceType) {
2045                                 if (d.IsStruct)
2046                                         return CreateConstantResult (ec, false);
2047                         }
2048
2049                         if (expr.Type.IsGenericParameter) {
2050                                 if (expr.Type == d && TypeSpec.IsValueType (t) && TypeSpec.IsValueType (d))
2051                                         return CreateConstantResult (ec, true);
2052
2053                                 expr = new BoxedCast (expr, d);
2054                         }
2055
2056                         return this;
2057                 }
2058
2059                 public override object Accept (StructuralVisitor visitor)
2060                 {
2061                         return visitor.Visit (this);
2062                 }
2063         }
2064
2065         class WildcardPattern : PatternExpression
2066         {
2067                 public WildcardPattern (Location loc)
2068                         : base (loc)
2069                 {
2070                 }
2071
2072                 protected override Expression DoResolve (ResolveContext rc)
2073                 {
2074                         eclass = ExprClass.Value;
2075                         type = rc.BuiltinTypes.Object;
2076                         return this;
2077                 }
2078
2079                 public override void Emit (EmitContext ec)
2080                 {
2081                         ec.EmitInt (1);
2082                 }
2083         }
2084
2085         class RecursivePattern : ComplexPatternExpression
2086         {
2087                 MethodGroupExpr operator_mg;
2088                 Arguments operator_args;
2089
2090                 public RecursivePattern (ATypeNameExpression typeExpresion, Arguments arguments, Location loc)
2091                         : base (typeExpresion, loc)
2092                 {
2093                         Arguments = arguments;
2094                 }
2095
2096                 public Arguments Arguments { get; private set; }
2097
2098                 protected override Expression DoResolve (ResolveContext rc)
2099                 {
2100                         type = TypeExpression.ResolveAsType (rc);
2101                         if (type == null)
2102                                 return null;
2103
2104                         var operators = MemberCache.GetUserOperator (type, Operator.OpType.Is, true);
2105                         if (operators == null) {
2106                                 Error_TypeDoesNotContainDefinition (rc, type, Operator.GetName (Operator.OpType.Is) + " operator");
2107                                 return null;
2108                         }
2109
2110                         var ops = FindMatchingOverloads (operators);
2111                         if (ops == null) {
2112                                 // TODO: better error message
2113                                 Error_TypeDoesNotContainDefinition (rc, type, Operator.GetName (Operator.OpType.Is) + " operator");
2114                                 return null;
2115                         }
2116
2117                         bool dynamic_args;
2118                         Arguments.Resolve (rc, out dynamic_args);
2119                         if (dynamic_args)
2120                                 throw new NotImplementedException ("dynamic argument");
2121
2122                         var op = FindBestOverload (rc, ops);
2123                         if (op == null) {
2124                                 // TODO: better error message
2125                                 Error_TypeDoesNotContainDefinition (rc, type, Operator.GetName (Operator.OpType.Is) + " operator");
2126                                 return null;
2127                         }
2128
2129                         var op_types = op.Parameters.Types;
2130                         operator_args = new Arguments (op_types.Length);
2131                         operator_args.Add (new Argument (new EmptyExpression (type)));
2132
2133                         for (int i = 0; i < Arguments.Count; ++i) {
2134                                 // TODO: Needs releasing optimization
2135                                 var lt = new LocalTemporary (op_types [i + 1]);
2136                                 operator_args.Add (new Argument (lt, Argument.AType.Out));
2137
2138                                 if (comparisons == null)
2139                                         comparisons = new Expression[Arguments.Count];
2140
2141                                 int arg_comp_index;
2142                                 Expression expr;
2143
2144                                 var arg = Arguments [i];
2145                                 var named = arg as NamedArgument;
2146                                 if (named != null) {
2147                                         arg_comp_index = op.Parameters.GetParameterIndexByName (named.Name) - 1;
2148                                         expr = Arguments [arg_comp_index].Expr;
2149                                 } else {
2150                                         arg_comp_index = i;
2151                                         expr = arg.Expr;
2152                                 }
2153
2154                                 comparisons [arg_comp_index] = ResolveComparison (rc, expr, lt);
2155                         }
2156
2157                         operator_mg = MethodGroupExpr.CreatePredefined (op, type, loc);
2158
2159                         eclass = ExprClass.Value;
2160                         return this;
2161                 }
2162
2163                 List<MethodSpec> FindMatchingOverloads (IList<MemberSpec> members)
2164                 {
2165                         int arg_count = Arguments.Count + 1;
2166                         List<MethodSpec> best = null;
2167                         foreach (MethodSpec method in members) {
2168                                 var pm = method.Parameters;
2169                                 if (pm.Count != arg_count)
2170                                         continue;
2171
2172                                 // TODO: Needs more thorough operator checks elsewhere to avoid doing this every time
2173                                 bool ok = true;
2174                                 for (int ii = 1; ii < pm.Count; ++ii) {
2175                                         if ((pm.FixedParameters [ii].ModFlags & Parameter.Modifier.OUT) == 0) {
2176                                                 ok = false;
2177                                                 break;
2178                                         }
2179                                 }
2180
2181                                 if (!ok)
2182                                         continue;
2183
2184                                 if (best == null)
2185                                         best = new List<MethodSpec> ();
2186
2187                                 best.Add (method);
2188                         }
2189
2190                         return best;
2191                 }
2192
2193                 MethodSpec FindBestOverload (ResolveContext rc, List<MethodSpec> methods)
2194                 {
2195                         for (int ii = 0; ii < Arguments.Count; ++ii) {
2196                                 var arg = Arguments [ii];
2197                                 var expr = arg.Expr;
2198                                 if (expr is WildcardPattern)
2199                                         continue;
2200
2201                                 var na = arg as NamedArgument;
2202                                 for (int i = 0; i < methods.Count; ++i) {
2203                                         var pd = methods [i].Parameters;
2204
2205                                         int index;
2206                                         if (na != null) {
2207                                                 index = pd.GetParameterIndexByName (na.Name);
2208                                                 if (index < 1) {
2209                                                         methods.RemoveAt (i--);
2210                                                         continue;
2211                                                 }
2212                                         } else {
2213                                                 index = ii + 1;
2214                                         }
2215
2216                                         var m = pd.Types [index];
2217                                         if (!Convert.ImplicitConversionExists (rc, expr, m))
2218                                                 methods.RemoveAt (i--);
2219                                 }
2220                         }
2221
2222                         if (methods.Count != 1)
2223                                 return null;
2224
2225                         return methods [0];
2226                 }
2227
2228                 public override void EmitBranchable (EmitContext ec, Label target, bool on_true)
2229                 {
2230                         operator_mg.EmitCall (ec, operator_args, false);
2231                         ec.Emit (OpCodes.Brfalse, target);
2232
2233                         base.EmitBranchable (ec, target, on_true);
2234                 }
2235
2236                 static Expression ResolveComparison (ResolveContext rc, Expression expr, LocalTemporary lt)
2237                 {
2238                         if (expr is WildcardPattern)
2239                                 return new EmptyExpression (expr.Type);
2240
2241                         var recursive = expr as RecursivePattern;
2242                         expr = Convert.ImplicitConversionRequired (rc, expr, lt.Type, expr.Location);
2243                         if (expr == null)
2244                                 return null;
2245
2246                         if (recursive != null) {
2247                                 recursive.SetParentInstance (lt);
2248                                 return expr;
2249                         }
2250
2251                         // TODO: Better error handling
2252                         return new Binary (Binary.Operator.Equality, lt, expr, expr.Location).Resolve (rc);
2253                 }
2254
2255                 public void SetParentInstance (Expression instance)
2256                 {
2257                         operator_args [0] = new Argument (instance);
2258                 }
2259         }
2260
2261         class PropertyPattern : ComplexPatternExpression
2262         {
2263                 LocalTemporary instance;
2264
2265                 public PropertyPattern (ATypeNameExpression typeExpresion, List<PropertyPatternMember> members, Location loc)
2266                         : base (typeExpresion, loc)
2267                 {
2268                         Members = members;
2269                 }
2270
2271                 public List<PropertyPatternMember> Members { get; private set; }
2272
2273                 protected override Expression DoResolve (ResolveContext rc)
2274                 {
2275                         type = TypeExpression.ResolveAsType (rc);
2276                         if (type == null)
2277                                 return null;
2278
2279                         comparisons = new Expression[Members.Count];
2280
2281                         // TODO: optimize when source is VariableReference, it'd save dup+pop
2282                         instance = new LocalTemporary (type);
2283
2284                         for (int i = 0; i < Members.Count; i++) {
2285                                 var lookup = Members [i];
2286
2287                                 var member = MemberLookup (rc, false, type, lookup.Name, 0, Expression.MemberLookupRestrictions.ExactArity, loc);
2288                                 if (member == null) {
2289                                         member = MemberLookup (rc, true, type, lookup.Name, 0, Expression.MemberLookupRestrictions.ExactArity, loc);
2290                                         if (member != null) {
2291                                                 Expression.ErrorIsInaccesible (rc, member.GetSignatureForError (), loc);
2292                                                 continue;
2293                                         }
2294                                 }
2295
2296                                 if (member == null) {
2297                                         Expression.Error_TypeDoesNotContainDefinition (rc, Location, Type, lookup.Name);
2298                                         continue;
2299                                 }
2300
2301                                 var pe = member as PropertyExpr;
2302                                 if (pe == null || member is FieldExpr) {
2303                                         rc.Report.Error (-2001, lookup.Location, "`{0}' is not a valid pattern member", lookup.Name);
2304                                         continue;
2305                                 }
2306
2307                                 // TODO: Obsolete checks
2308                                 // TODO: check accessibility
2309                                 if (pe != null && !pe.PropertyInfo.HasGet) {
2310                                         rc.Report.Error (-2002, lookup.Location, "Property `{0}.get' accessor is required", pe.GetSignatureForError ());
2311                                         continue;
2312                                 }
2313
2314                                 var expr = lookup.Expr.Resolve (rc);
2315                                 if (expr == null)
2316                                         continue;
2317
2318                                 var me = (MemberExpr)member;
2319                                 me.InstanceExpression = instance;
2320
2321                                 comparisons [i] = ResolveComparison (rc, expr, me);
2322                         }
2323
2324                         eclass = ExprClass.Value;
2325                         return this;
2326                 }
2327
2328                 static Expression ResolveComparison (ResolveContext rc, Expression expr, Expression instance)
2329                 {
2330                         if (expr is WildcardPattern)
2331                                 return new EmptyExpression (expr.Type);
2332
2333                         return new Is (instance, expr, expr.Location).Resolve (rc);
2334                 }
2335
2336                 public override void EmitBranchable (EmitContext ec, Label target, bool on_true)
2337                 {
2338                         instance.Store (ec);
2339
2340                         base.EmitBranchable (ec, target, on_true);
2341                 }
2342         }
2343
2344         class PropertyPatternMember
2345         {
2346                 public PropertyPatternMember (string name, Expression expr, Location loc)
2347                 {
2348                         Name = name;
2349                         Expr = expr;
2350                         Location = loc;
2351                 }
2352
2353                 public string Name { get; private set; }
2354                 public Expression Expr { get; private set; }
2355                 public Location Location { get; private set; }
2356         }
2357
2358         abstract class PatternExpression : Expression
2359         {
2360                 protected PatternExpression (Location loc)
2361                 {
2362                         this.loc = loc;
2363                 }
2364
2365                 public override Expression CreateExpressionTree (ResolveContext ec)
2366                 {
2367                         throw new NotImplementedException ();
2368                 }
2369         }
2370
2371         abstract class ComplexPatternExpression : PatternExpression
2372         {
2373                 protected Expression[] comparisons;
2374
2375                 protected ComplexPatternExpression (ATypeNameExpression typeExpresion, Location loc)
2376                         : base (loc)
2377                 {
2378                         TypeExpression = typeExpresion;
2379                 }
2380
2381                 public ATypeNameExpression TypeExpression { get; private set; }
2382
2383                 public override void Emit (EmitContext ec)
2384                 {
2385                         EmitBranchable (ec, ec.RecursivePatternLabel, false);
2386                 }
2387
2388                 public override void EmitBranchable (EmitContext ec, Label target, bool on_true)
2389                 {
2390                         if (comparisons != null) {
2391                                 foreach (var comp in comparisons) {
2392                                         comp.EmitBranchable (ec, target, false);
2393                                 }
2394                         }
2395                 }
2396         }
2397
2398         /// <summary>
2399         ///   Implementation of the `as' operator.
2400         /// </summary>
2401         public class As : Probe {
2402
2403                 public As (Expression expr, Expression probe_type, Location l)
2404                         : base (expr, probe_type, l)
2405                 {
2406                 }
2407
2408                 protected override string OperatorName {
2409                         get { return "as"; }
2410                 }
2411
2412                 public override Expression CreateExpressionTree (ResolveContext ec)
2413                 {
2414                         Arguments args = Arguments.CreateForExpressionTree (ec, null,
2415                                 expr.CreateExpressionTree (ec),
2416                                 new TypeOf (probe_type_expr, loc));
2417
2418                         return CreateExpressionFactoryCall (ec, "TypeAs", args);
2419                 }
2420
2421                 public override void Emit (EmitContext ec)
2422                 {
2423                         expr.Emit (ec);
2424
2425                         ec.Emit (OpCodes.Isinst, type);
2426
2427                         if (TypeManager.IsGenericParameter (type) || type.IsNullableType)
2428                                 ec.Emit (OpCodes.Unbox_Any, type);
2429                 }
2430
2431                 protected override Expression DoResolve (ResolveContext ec)
2432                 {
2433                         if (ResolveCommon (ec) == null)
2434                                 return null;
2435
2436                         type = probe_type_expr;
2437                         eclass = ExprClass.Value;
2438                         TypeSpec etype = expr.Type;
2439
2440                         if (expr is TupleLiteral && TupleLiteral.ContainsNoTypeElement (etype)) {
2441                                 ec.Report.Error (8307, expr.Location, "The first operand of an `as' operator may not be a tuple literal without a natural type");
2442                                 type = InternalType.ErrorType;
2443                                 return this;
2444                         }
2445
2446                         if (type == null) {
2447                                 type = InternalType.ErrorType;
2448                                 return this;
2449                         }
2450
2451                         if (!TypeSpec.IsReferenceType (type) && !type.IsNullableType) {
2452                                 if (TypeManager.IsGenericParameter (type)) {
2453                                         ec.Report.Error (413, loc,
2454                                                 "The `as' operator cannot be used with a non-reference type parameter `{0}'. Consider adding `class' or a reference type constraint",
2455                                                 probe_type_expr.GetSignatureForError ());
2456                                 } else {
2457                                         ec.Report.Error (77, loc,
2458                                                 "The `as' operator cannot be used with a non-nullable value type `{0}'",
2459                                                 type.GetSignatureForError ());
2460                                 }
2461                                 return null;
2462                         }
2463
2464                         if (expr.IsNull && type.IsNullableType) {
2465                                 return Nullable.LiftedNull.CreateFromExpression (ec, this);
2466                         }
2467
2468                         // If the compile-time type of E is dynamic, unlike the cast operator the as operator is not dynamically bound
2469                         if (etype.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
2470                                 return this;
2471                         }
2472
2473                         Expression e = Convert.ImplicitConversionStandard (ec, expr, type, loc);
2474                         if (e != null) {
2475                                 e = EmptyCast.Create (e, type);
2476                                 return ReducedExpression.Create (e, this).Resolve (ec);
2477                         }
2478
2479                         if (Convert.ExplicitReferenceConversionExists (etype, type)){
2480                                 if (TypeManager.IsGenericParameter (etype))
2481                                         expr = new BoxedCast (expr, etype);
2482
2483                                 return this;
2484                         }
2485
2486                         if (InflatedTypeSpec.ContainsTypeParameter (etype) || InflatedTypeSpec.ContainsTypeParameter (type)) {
2487                                 expr = new BoxedCast (expr, etype);
2488                                 return this;
2489                         }
2490
2491                         if (etype != InternalType.ErrorType) {
2492                                 ec.Report.Error (39, loc, "Cannot convert type `{0}' to `{1}' via a built-in conversion",
2493                                         etype.GetSignatureForError (), type.GetSignatureForError ());
2494                         }
2495
2496                         return null;
2497                 }
2498
2499                 public override object Accept (StructuralVisitor visitor)
2500                 {
2501                         return visitor.Visit (this);
2502                 }
2503         }
2504
2505         //
2506         // This represents a typecast in the source language.
2507         //
2508         public class Cast : ShimExpression {
2509                 Expression target_type;
2510
2511                 public Cast (Expression cast_type, Expression expr, Location loc)
2512                         : base (expr)
2513                 {
2514                         this.target_type = cast_type;
2515                         this.loc = loc;
2516                 }
2517
2518                 public Expression TargetType {
2519                         get { return target_type; }
2520                 }
2521
2522                 protected override Expression DoResolve (ResolveContext ec)
2523                 {
2524                         expr = expr.Resolve (ec);
2525                         if (expr == null)
2526                                 return null;
2527
2528                         type = target_type.ResolveAsType (ec);
2529                         if (type == null)
2530                                 return null;
2531
2532                         if (type.IsStatic) {
2533                                 ec.Report.Error (716, loc, "Cannot convert to static type `{0}'", type.GetSignatureForError ());
2534                                 return null;
2535                         }
2536
2537                         if (type.IsPointer) {
2538                                 if (ec.CurrentIterator != null) {
2539                                         UnsafeInsideIteratorError (ec, loc);
2540                                 } else if (!ec.IsUnsafe) {
2541                                         UnsafeError (ec, loc);
2542                                 }
2543                         }
2544
2545                         eclass = ExprClass.Value;
2546
2547                         Constant c = expr as Constant;
2548                         if (c != null) {
2549                                 c = c.Reduce (ec, type);
2550                                 if (c != null)
2551                                         return c;
2552                         }
2553
2554                         var res = Convert.ExplicitConversion (ec, expr, type, loc);
2555                         if (res == expr)
2556                                 return EmptyCast.Create (res, type);
2557
2558                         return res;
2559                 }
2560
2561                 protected override void CloneTo (CloneContext clonectx, Expression t)
2562                 {
2563                         Cast target = (Cast) t;
2564
2565                         target.target_type = target_type.Clone (clonectx);
2566                         target.expr = expr.Clone (clonectx);
2567                 }
2568
2569                 public override object Accept (StructuralVisitor visitor)
2570                 {
2571                         return visitor.Visit (this);
2572                 }
2573         }
2574
2575         public class ImplicitCast : ShimExpression
2576         {
2577                 bool arrayAccess;
2578
2579                 public ImplicitCast (Expression expr, TypeSpec target, bool arrayAccess)
2580                         : base (expr)
2581                 {
2582                         this.loc = expr.Location;
2583                         this.type = target;
2584                         this.arrayAccess = arrayAccess;
2585                 }
2586
2587                 protected override Expression DoResolve (ResolveContext ec)
2588                 {
2589                         expr = expr.Resolve (ec);
2590                         if (expr == null)
2591                                 return null;
2592
2593                         if (arrayAccess)
2594                                 expr = ConvertExpressionToArrayIndex (ec, expr);
2595                         else
2596                                 expr = Convert.ImplicitConversionRequired (ec, expr, type, loc);
2597
2598                         return expr;
2599                 }
2600         }
2601
2602         public class DeclarationExpression : Expression, IMemoryLocation
2603         {
2604                 LocalVariableReference lvr;
2605
2606                 public DeclarationExpression (FullNamedExpression variableType, LocalVariable variable)
2607                 {
2608                         VariableType = variableType;
2609                         Variable = variable;
2610                         this.loc = variable.Location;
2611                 }
2612
2613                 public LocalVariable Variable { get; set; }
2614                 public Expression Initializer { get; set; }
2615                 public FullNamedExpression VariableType { get; set; }
2616
2617                 public void AddressOf (EmitContext ec, AddressOp mode)
2618                 {
2619                         if (!Variable.Created)
2620                                 Variable.CreateBuilder (ec);
2621
2622                         if (Initializer != null) {
2623                                 lvr.EmitAssign (ec, Initializer, false, false);
2624                         }
2625
2626                         lvr.AddressOf (ec, mode);
2627                 }
2628
2629                 protected override void CloneTo (CloneContext clonectx, Expression t)
2630                 {
2631                         var target = (DeclarationExpression) t;
2632
2633                         target.VariableType = (FullNamedExpression) VariableType.Clone (clonectx);
2634
2635                         if (Initializer != null)
2636                                 target.Initializer = Initializer.Clone (clonectx);
2637                 }
2638
2639                 public override Expression CreateExpressionTree (ResolveContext rc)
2640                 {
2641                         rc.Report.Error (8198, loc, "An expression tree cannot contain out variable declaration");
2642                         return null;
2643                 }
2644
2645                 bool DoResolveCommon (ResolveContext rc)
2646                 {
2647                         CheckExpressionVariable (rc);
2648
2649                         var var_expr = VariableType as VarExpr;
2650                         if (var_expr != null) {
2651                                 type = InternalType.VarOutType;
2652                         } else {
2653                                 type = VariableType.ResolveAsType (rc);
2654                                 if (type == null)
2655                                         return false;
2656                         }
2657
2658                         if (Initializer != null) {
2659                                 Initializer = Initializer.Resolve (rc);
2660
2661                                 if (var_expr != null && Initializer != null && var_expr.InferType (rc, Initializer)) {
2662                                         type = var_expr.Type;
2663                                 }
2664                         }
2665
2666                         Variable.Type = type;
2667                         lvr = new LocalVariableReference (Variable, loc);
2668
2669                         eclass = ExprClass.Variable;
2670                         return true;
2671                 }
2672
2673                 protected override Expression DoResolve (ResolveContext rc)
2674                 {
2675                         if (DoResolveCommon (rc))
2676                                 lvr.Resolve (rc);
2677
2678                         return this;
2679                 }
2680
2681                 public override Expression DoResolveLValue (ResolveContext rc, Expression right_side)
2682                 {
2683                         if (lvr == null && DoResolveCommon (rc))
2684                                 lvr.ResolveLValue (rc, right_side);
2685
2686                         return this;
2687                 }
2688
2689                 public override void Emit (EmitContext ec)
2690                 {
2691                         throw new NotImplementedException ();
2692                 }
2693
2694                 public override void EmitPrepare (EmitContext ec)
2695                 {
2696                         Variable.CreateBuilder (ec);
2697                 }
2698         }
2699
2700         //
2701         // C# 2.0 Default value expression
2702         //
2703         public class DefaultValueExpression : Expression
2704         {
2705                 Expression expr;
2706
2707                 public DefaultValueExpression (Expression expr, Location loc)
2708                 {
2709                         this.expr = expr;
2710                         this.loc = loc;
2711                 }
2712
2713                 public Expression Expr {
2714                         get {
2715                                 return this.expr;
2716                         }
2717                 }
2718
2719                 public override bool IsSideEffectFree {
2720                         get {
2721                                 return true;
2722                         }
2723                 }
2724
2725                 public override bool ContainsEmitWithAwait ()
2726                 {
2727                         return false;
2728                 }
2729
2730                 public override Expression CreateExpressionTree (ResolveContext ec)
2731                 {
2732                         Arguments args = new Arguments (2);
2733                         args.Add (new Argument (this));
2734                         args.Add (new Argument (new TypeOf (type, loc)));
2735                         return CreateExpressionFactoryCall (ec, "Constant", args);
2736                 }
2737
2738                 protected override Expression DoResolve (ResolveContext ec)
2739                 {
2740                         type = expr.ResolveAsType (ec);
2741                         if (type == null)
2742                                 return null;
2743
2744                         if (type.IsStatic) {
2745                                 ec.Report.Error (-244, loc, "The `default value' operator cannot be applied to an operand of a static type");
2746                         }
2747
2748                         if (type.IsPointer)
2749                                 return new NullLiteral (Location).ConvertImplicitly (type);
2750
2751                         if (TypeSpec.IsReferenceType (type))
2752                                 return new NullConstant (type, loc);
2753
2754                         Constant c = New.Constantify (type, expr.Location);
2755                         if (c != null)
2756                                 return c;
2757
2758                         eclass = ExprClass.Variable;
2759                         return this;
2760                 }
2761
2762                 public override void Emit (EmitContext ec)
2763                 {
2764                         LocalTemporary temp_storage = new LocalTemporary(type);
2765
2766                         temp_storage.AddressOf(ec, AddressOp.LoadStore);
2767                         ec.Emit(OpCodes.Initobj, type);
2768                         temp_storage.Emit(ec);
2769                         temp_storage.Release (ec);
2770                 }
2771
2772 #if !STATIC
2773                 public override SLE.Expression MakeExpression (BuilderContext ctx)
2774                 {
2775                         return SLE.Expression.Default (type.GetMetaInfo ());
2776                 }
2777 #endif
2778
2779                 protected override void CloneTo (CloneContext clonectx, Expression t)
2780                 {
2781                         DefaultValueExpression target = (DefaultValueExpression) t;
2782
2783                         target.expr = expr.Clone (clonectx);
2784                 }
2785
2786                 public override object Accept (StructuralVisitor visitor)
2787                 {
2788                         return visitor.Visit (this);
2789                 }
2790         }
2791
2792         /// <summary>
2793         ///   Binary operators
2794         /// </summary>
2795         public class Binary : Expression, IDynamicBinder
2796         {
2797                 public class PredefinedOperator
2798                 {
2799                         protected readonly TypeSpec left;
2800                         protected readonly TypeSpec right;
2801                         protected readonly TypeSpec left_unwrap;
2802                         protected readonly TypeSpec right_unwrap;
2803                         public readonly Operator OperatorsMask;
2804                         public TypeSpec ReturnType;
2805
2806                         public PredefinedOperator (TypeSpec ltype, TypeSpec rtype, Operator op_mask)
2807                                 : this (ltype, rtype, op_mask, ltype)
2808                         {
2809                         }
2810
2811                         public PredefinedOperator (TypeSpec type, Operator op_mask, TypeSpec return_type)
2812                                 : this (type, type, op_mask, return_type)
2813                         {
2814                         }
2815
2816                         public PredefinedOperator (TypeSpec type, Operator op_mask)
2817                                 : this (type, type, op_mask, type)
2818                         {
2819                         }
2820
2821                         public PredefinedOperator (TypeSpec ltype, TypeSpec rtype, Operator op_mask, TypeSpec return_type)
2822                         {
2823                                 if ((op_mask & Operator.ValuesOnlyMask) != 0)
2824                                         throw new InternalErrorException ("Only masked values can be used");
2825
2826                                 if ((op_mask & Operator.NullableMask) != 0) {
2827                                         left_unwrap = Nullable.NullableInfo.GetUnderlyingType (ltype);
2828                                         right_unwrap = Nullable.NullableInfo.GetUnderlyingType (rtype);
2829                                 } else {
2830                                         left_unwrap = ltype;
2831                                         right_unwrap = rtype;
2832                                 }
2833
2834                                 this.left = ltype;
2835                                 this.right = rtype;
2836                                 this.OperatorsMask = op_mask;
2837                                 this.ReturnType = return_type;
2838                         }
2839
2840                         public bool IsLifted {
2841                                 get {
2842                                         return (OperatorsMask & Operator.NullableMask) != 0;
2843                                 }
2844                         }
2845
2846                         public virtual Expression ConvertResult (ResolveContext rc, Binary b)
2847                         {
2848                                 Constant c;
2849
2850                                 var left_expr = b.left;
2851                                 var right_expr = b.right;
2852
2853                                 b.type = ReturnType;
2854
2855                                 if (IsLifted) {
2856                                         if (rc.HasSet (ResolveContext.Options.ExpressionTreeConversion)) {
2857                                                 b.left = Convert.ImplicitConversion (rc, b.left, left, b.left.Location);
2858                                                 b.right = Convert.ImplicitConversion (rc, b.right, right, b.right.Location);
2859                                         }
2860
2861                                         if (right_expr.IsNull) {
2862                                                 if ((b.oper & Operator.EqualityMask) != 0) {
2863                                                         if (!left_expr.Type.IsNullableType && BuiltinTypeSpec.IsPrimitiveType (left_expr.Type))
2864                                                                 return b.CreateLiftedValueTypeResult (rc, left_expr.Type);
2865                                                 } else if ((b.oper & Operator.BitwiseMask) != 0) {
2866                                                         if (left_unwrap.BuiltinType != BuiltinTypeSpec.Type.Bool)
2867                                                                 return Nullable.LiftedNull.CreateFromExpression (rc, b);
2868                                                 } else {
2869                                                         b.left = Convert.ImplicitConversion (rc, b.left, left, b.left.Location);
2870                                                         b.right = Convert.ImplicitConversion (rc, b.right, right, b.right.Location);
2871
2872                                                         if ((b.Oper & (Operator.ArithmeticMask | Operator.ShiftMask)) != 0)
2873                                                                 return Nullable.LiftedNull.CreateFromExpression (rc, b);
2874
2875                                                         return b.CreateLiftedValueTypeResult (rc, left);
2876                                                 }
2877                                         } else if (left_expr.IsNull) {
2878                                                 if ((b.oper & Operator.EqualityMask) != 0) {
2879                                                         if (!right_expr.Type.IsNullableType && BuiltinTypeSpec.IsPrimitiveType (right_expr.Type))
2880                                                                 return b.CreateLiftedValueTypeResult (rc, right_expr.Type);
2881                                                 } else if ((b.oper & Operator.BitwiseMask) != 0) {
2882                                                         if (right_unwrap.BuiltinType != BuiltinTypeSpec.Type.Bool)
2883                                                                 return Nullable.LiftedNull.CreateFromExpression (rc, b);
2884                                                 } else {
2885                                                         b.left = Convert.ImplicitConversion (rc, b.left, left, b.left.Location);
2886                                                         b.right = Convert.ImplicitConversion (rc, b.right, right, b.right.Location);
2887
2888                                                         if ((b.Oper & (Operator.ArithmeticMask | Operator.ShiftMask)) != 0)
2889                                                                 return Nullable.LiftedNull.CreateFromExpression (rc, b);
2890
2891                                                         return b.CreateLiftedValueTypeResult (rc, right);
2892                                                 }
2893                                         }
2894                                 }
2895
2896                                 //
2897                                 // A user operators does not support multiple user conversions, but decimal type
2898                                 // is considered to be predefined type therefore we apply predefined operators rules
2899                                 // and then look for decimal user-operator implementation
2900                                 //
2901                                 if (left.BuiltinType == BuiltinTypeSpec.Type.Decimal) {
2902                                         b.left = Convert.ImplicitConversion (rc, b.left, left, b.left.Location);
2903                                         b.right = Convert.ImplicitConversion (rc, b.right, right, b.right.Location);
2904
2905                                         return b.ResolveUserOperator (rc, b.left, b.right);
2906                                 }
2907
2908                                 c = right_expr as Constant;
2909                                 if (c != null) {
2910                                         if (c.IsDefaultValue) {
2911                                                 //
2912                                                 // Optimizes
2913                                                 //
2914                                                 // (expr + 0) to expr
2915                                                 // (expr - 0) to expr
2916                                                 // (bool? | false) to bool?
2917                                                 //
2918                                                 if (b.oper == Operator.Addition || b.oper == Operator.Subtraction ||
2919                                                         (b.oper == Operator.BitwiseOr && left_unwrap.BuiltinType == BuiltinTypeSpec.Type.Bool && c is BoolConstant)) {
2920                                                         b.left = Convert.ImplicitConversion (rc, b.left, left, b.left.Location);
2921                                                         return ReducedExpression.Create (b.left, b).Resolve (rc);
2922                                                 }
2923
2924                                                 //
2925                                                 // Optimizes (value &/&& 0) to 0
2926                                                 //
2927                                                 if ((b.oper == Operator.BitwiseAnd || b.oper == Operator.LogicalAnd) && !IsLifted) {
2928                                                         Constant side_effect = new SideEffectConstant (c, b.left, c.Location);
2929                                                         return ReducedExpression.Create (side_effect, b);
2930                                                 }
2931                                         } else {
2932                                                 //
2933                                                 // Optimizes (bool? & true) to bool?
2934                                                 //
2935                                                 if (IsLifted && left_unwrap.BuiltinType == BuiltinTypeSpec.Type.Bool && b.oper == Operator.BitwiseAnd) {
2936                                                         return ReducedExpression.Create (b.left, b).Resolve (rc);
2937                                                 }
2938                                         }
2939
2940                                         if ((b.oper == Operator.Multiply || b.oper == Operator.Division) && c.IsOneInteger)
2941                                                 return ReducedExpression.Create (b.left, b).Resolve (rc);
2942
2943                                         if ((b.oper & Operator.ShiftMask) != 0 && c is IntConstant) {
2944                                                 b.right = new IntConstant (rc.BuiltinTypes, ((IntConstant) c).Value & GetShiftMask (left_unwrap), b.right.Location);
2945                                         }
2946                                 }
2947
2948                                 c = b.left as Constant;
2949                                 if (c != null) {
2950                                         if (c.IsDefaultValue) {
2951                                                 //
2952                                                 // Optimizes
2953                                                 //
2954                                                 // (0 + expr) to expr
2955                                                 // (false | bool?) to bool?
2956                                                 //
2957                                                 if (b.oper == Operator.Addition ||
2958                                                         (b.oper == Operator.BitwiseOr && right_unwrap.BuiltinType == BuiltinTypeSpec.Type.Bool && c is BoolConstant)) {
2959                                                         b.right = Convert.ImplicitConversion (rc, b.right, right, b.right.Location);
2960                                                         return ReducedExpression.Create (b.right, b).Resolve (rc);
2961                                                 }
2962
2963                                                 //
2964                                                 // Optimizes (false && expr) to false
2965                                                 //
2966                                                 if (b.oper == Operator.LogicalAnd && c.Type.BuiltinType == BuiltinTypeSpec.Type.Bool) {
2967                                                         // No rhs side-effects
2968                                                         Expression.Warning_UnreachableExpression (rc, b.right.StartLocation);
2969                                                         return ReducedExpression.Create (c, b);
2970                                                 }
2971
2972                                                 //
2973                                                 // Optimizes (0 & value) to 0
2974                                                 //
2975                                                 if (b.oper == Operator.BitwiseAnd && !IsLifted) {
2976                                                         Constant side_effect = new SideEffectConstant (c, b.right, c.Location);
2977                                                         return ReducedExpression.Create (side_effect, b);
2978                                                 }
2979                                         } else {
2980                                                 //
2981                                                 // Optimizes (true & bool?) to bool?
2982                                                 //
2983                                                 if (IsLifted && left_unwrap.BuiltinType == BuiltinTypeSpec.Type.Bool && b.oper == Operator.BitwiseAnd) {
2984                                                         return ReducedExpression.Create (b.right, b).Resolve (rc);
2985                                                 }
2986
2987                                                 //
2988                                                 // Optimizes (true || expr) to true
2989                                                 //
2990                                                 if (b.oper == Operator.LogicalOr && c.Type.BuiltinType == BuiltinTypeSpec.Type.Bool) {
2991                                                         // No rhs side-effects
2992                                                         Expression.Warning_UnreachableExpression (rc, b.right.StartLocation);
2993                                                         return ReducedExpression.Create (c, b);
2994                                                 }
2995                                         }
2996
2997                                         if (b.oper == Operator.Multiply && c.IsOneInteger)
2998                                                 return ReducedExpression.Create (b.right, b).Resolve (rc);
2999                                 }
3000
3001                                 if (IsLifted) {
3002                                         var lifted = new Nullable.LiftedBinaryOperator (b);
3003
3004                                         TypeSpec ltype, rtype;
3005                                         if (b.left.Type.IsNullableType) {
3006                                                 lifted.UnwrapLeft = new Nullable.Unwrap (b.left);
3007                                                 ltype = left_unwrap;
3008                                         } else {
3009                                                 ltype = left;
3010                                         }
3011
3012                                         if (b.right.Type.IsNullableType) {
3013                                                 lifted.UnwrapRight = new Nullable.Unwrap (b.right);
3014                                                 rtype = right_unwrap;
3015                                         } else {
3016                                                 rtype = right;
3017                                         }
3018
3019                                         lifted.Left = b.left.IsNull ?
3020                                                 Nullable.LiftedNull.Create (ltype, b.left.Location) :
3021                                                 Convert.ImplicitConversion (rc, lifted.UnwrapLeft ?? b.left, ltype, b.left.Location);
3022
3023                                         lifted.Right = b.right.IsNull ?
3024                                                 Nullable.LiftedNull.Create (rtype, b.right.Location) :
3025                                                 Convert.ImplicitConversion (rc, lifted.UnwrapRight ?? b.right, rtype, b.right.Location);
3026
3027                                         return lifted.Resolve (rc);
3028                                 }
3029
3030                                 b.left = Convert.ImplicitConversion (rc, b.left, left, b.left.Location);
3031                                 b.right = Convert.ImplicitConversion (rc, b.right, right, b.right.Location);
3032
3033                                 return b;
3034                         }
3035
3036                         public bool IsPrimitiveApplicable (TypeSpec ltype, TypeSpec rtype)
3037                         {
3038                                 //
3039                                 // We are dealing with primitive types only
3040                                 //
3041                                 return left == ltype && ltype == rtype;
3042                         }
3043
3044                         public virtual bool IsApplicable (ResolveContext ec, Expression lexpr, Expression rexpr)
3045                         {
3046                                 // Quick path
3047                                 if (left == lexpr.Type && right == rexpr.Type)
3048                                         return true;
3049
3050                                 return Convert.ImplicitConversionExists (ec, lexpr, left) &&
3051                                         Convert.ImplicitConversionExists (ec, rexpr, right);
3052                         }
3053
3054                         public PredefinedOperator ResolveBetterOperator (ResolveContext ec, PredefinedOperator best_operator)
3055                         {
3056                                 if ((OperatorsMask & Operator.DecomposedMask) != 0)
3057                                         return best_operator;
3058
3059                                 if ((best_operator.OperatorsMask & Operator.DecomposedMask) != 0)
3060                                         return this;
3061
3062                                 int result = 0;
3063                                 if (left != null && best_operator.left != null) {
3064                                         result = OverloadResolver.BetterTypeConversion (ec, best_operator.left_unwrap, left_unwrap);
3065                                 }
3066
3067                                 //
3068                                 // When second argument is same as the first one, the result is same
3069                                 //
3070                                 if (right != null && (left != right || best_operator.left != best_operator.right)) {
3071                                         result |= OverloadResolver.BetterTypeConversion (ec, best_operator.right_unwrap, right_unwrap);
3072                                 }
3073
3074                                 if (result == 0 || result > 2)
3075                                         return null;
3076
3077                                 return result == 1 ? best_operator : this;
3078                         }
3079                 }
3080
3081                 sealed class PredefinedStringOperator : PredefinedOperator
3082                 {
3083                         public PredefinedStringOperator (TypeSpec type, Operator op_mask, TypeSpec retType)
3084                                 : base (type, type, op_mask, retType)
3085                         {
3086                         }
3087
3088                         public PredefinedStringOperator (TypeSpec ltype, TypeSpec rtype, Operator op_mask, TypeSpec retType)
3089                                 : base (ltype, rtype, op_mask, retType)
3090                         {
3091                         }
3092
3093                         public override Expression ConvertResult (ResolveContext ec, Binary b)
3094                         {
3095                                 //
3096                                 // Use original expression for nullable arguments
3097                                 //
3098                                 Nullable.Unwrap unwrap = b.left as Nullable.Unwrap;
3099                                 if (unwrap != null)
3100                                         b.left = unwrap.Original;
3101
3102                                 unwrap = b.right as Nullable.Unwrap;
3103                                 if (unwrap != null)
3104                                         b.right = unwrap.Original;
3105
3106                                 b.left = Convert.ImplicitConversion (ec, b.left, left, b.left.Location);
3107                                 b.right = Convert.ImplicitConversion (ec, b.right, right, b.right.Location);
3108
3109                                 //
3110                                 // Start a new concat expression using converted expression
3111                                 //
3112                                 return StringConcat.Create (ec, b.left, b.right, b.loc);
3113                         }
3114                 }
3115
3116                 sealed class PredefinedEqualityOperator : PredefinedOperator
3117                 {
3118                         MethodSpec equal_method, inequal_method;
3119
3120                         public PredefinedEqualityOperator (TypeSpec arg, TypeSpec retType)
3121                                 : base (arg, arg, Operator.EqualityMask, retType)
3122                         {
3123                         }
3124
3125                         public override Expression ConvertResult (ResolveContext ec, Binary b)
3126                         {
3127                                 b.type = ReturnType;
3128
3129                                 b.left = Convert.ImplicitConversion (ec, b.left, left, b.left.Location);
3130                                 b.right = Convert.ImplicitConversion (ec, b.right, right, b.right.Location);
3131
3132                                 Arguments args = new Arguments (2);
3133                                 args.Add (new Argument (b.left));
3134                                 args.Add (new Argument (b.right));
3135
3136                                 MethodSpec method;
3137                                 if (b.oper == Operator.Equality) {
3138                                         if (equal_method == null) {
3139                                                 if (left.BuiltinType == BuiltinTypeSpec.Type.String)
3140                                                         equal_method = ec.Module.PredefinedMembers.StringEqual.Resolve (b.loc);
3141                                                 else if (left.BuiltinType == BuiltinTypeSpec.Type.Delegate)
3142                                                         equal_method = ec.Module.PredefinedMembers.DelegateEqual.Resolve (b.loc);
3143                                                 else
3144                                                         throw new NotImplementedException (left.GetSignatureForError ());
3145                                         }
3146
3147                                         method = equal_method;
3148                                 } else {
3149                                         if (inequal_method == null) {
3150                                                 if (left.BuiltinType == BuiltinTypeSpec.Type.String)
3151                                                         inequal_method = ec.Module.PredefinedMembers.StringInequal.Resolve (b.loc);
3152                                                 else if (left.BuiltinType == BuiltinTypeSpec.Type.Delegate)
3153                                                         inequal_method = ec.Module.PredefinedMembers.DelegateInequal.Resolve (b.loc);
3154                                                 else
3155                                                         throw new NotImplementedException (left.GetSignatureForError ());
3156                                         }
3157
3158                                         method = inequal_method;
3159                                 }
3160
3161                                 return new UserOperatorCall (method, args, b.CreateExpressionTree, b.loc);
3162                         }
3163                 }
3164
3165                 class PredefinedPointerOperator : PredefinedOperator
3166                 {
3167                         public PredefinedPointerOperator (TypeSpec ltype, TypeSpec rtype, Operator op_mask)
3168                                 : base (ltype, rtype, op_mask)
3169                         {
3170                         }
3171
3172                         public PredefinedPointerOperator (TypeSpec ltype, TypeSpec rtype, Operator op_mask, TypeSpec retType)
3173                                 : base (ltype, rtype, op_mask, retType)
3174                         {
3175                         }
3176
3177                         public PredefinedPointerOperator (TypeSpec type, Operator op_mask, TypeSpec return_type)
3178                                 : base (type, op_mask, return_type)
3179                         {
3180                         }
3181
3182                         public override bool IsApplicable (ResolveContext ec, Expression lexpr, Expression rexpr)
3183                         {
3184                                 if (left == null) {
3185                                         if (!lexpr.Type.IsPointer)
3186                                                 return false;
3187                                 } else {
3188                                         if (!Convert.ImplicitConversionExists (ec, lexpr, left))
3189                                                 return false;
3190                                 }
3191
3192                                 if (right == null) {
3193                                         if (!rexpr.Type.IsPointer)
3194                                                 return false;
3195                                 } else {
3196                                         if (!Convert.ImplicitConversionExists (ec, rexpr, right))
3197                                                 return false;
3198                                 }
3199
3200                                 return true;
3201                         }
3202
3203                         public override Expression ConvertResult (ResolveContext ec, Binary b)
3204                         {
3205                                 if (left != null) {
3206                                         b.left = Convert.UserDefinedConversion (ec, b.left, left, Convert.UserConversionRestriction.ImplicitOnly, b.loc) ?? EmptyCast.Create (b.left, left);
3207                                 } else if (right != null) {
3208                                         b.right = Convert.UserDefinedConversion (ec, b.right, right, Convert.UserConversionRestriction.ImplicitOnly, b.loc) ?? EmptyCast.Create (b.right, right);
3209                                 }
3210
3211                                 TypeSpec r_type = ReturnType;
3212                                 Expression left_arg, right_arg;
3213                                 if (r_type == null) {
3214                                         if (left == null) {
3215                                                 left_arg = b.left;
3216                                                 right_arg = b.right;
3217                                                 r_type = b.left.Type;
3218                                         } else {
3219                                                 left_arg = b.right;
3220                                                 right_arg = b.left;
3221                                                 r_type = b.right.Type;
3222                                         }
3223                                 } else {
3224                                         left_arg = b.left;
3225                                         right_arg = b.right;
3226                                 }
3227
3228                                 return new PointerArithmetic (b.oper, left_arg, right_arg, r_type, b.loc).Resolve (ec);
3229                         }
3230                 }
3231
3232                 [Flags]
3233                 public enum Operator {
3234                         Multiply        = 0 | ArithmeticMask,
3235                         Division        = 1 | ArithmeticMask,
3236                         Modulus         = 2 | ArithmeticMask,
3237                         Addition        = 3 | ArithmeticMask | AdditionMask,
3238                         Subtraction = 4 | ArithmeticMask | SubtractionMask,
3239
3240                         LeftShift       = 5 | ShiftMask,
3241                         RightShift      = 6 | ShiftMask,
3242
3243                         LessThan        = 7 | ComparisonMask | RelationalMask,
3244                         GreaterThan     = 8 | ComparisonMask | RelationalMask,
3245                         LessThanOrEqual         = 9 | ComparisonMask | RelationalMask,
3246                         GreaterThanOrEqual      = 10 | ComparisonMask | RelationalMask,
3247                         Equality        = 11 | ComparisonMask | EqualityMask,
3248                         Inequality      = 12 | ComparisonMask | EqualityMask,
3249
3250                         BitwiseAnd      = 13 | BitwiseMask,
3251                         ExclusiveOr     = 14 | BitwiseMask,
3252                         BitwiseOr       = 15 | BitwiseMask,
3253
3254                         LogicalAnd      = 16 | LogicalMask,
3255                         LogicalOr       = 17 | LogicalMask,
3256
3257                         //
3258                         // Operator masks
3259                         //
3260                         ValuesOnlyMask  = ArithmeticMask - 1,
3261                         ArithmeticMask  = 1 << 5,
3262                         ShiftMask               = 1 << 6,
3263                         ComparisonMask  = 1 << 7,
3264                         EqualityMask    = 1 << 8,
3265                         BitwiseMask             = 1 << 9,
3266                         LogicalMask             = 1 << 10,
3267                         AdditionMask    = 1 << 11,
3268                         SubtractionMask = 1 << 12,
3269                         RelationalMask  = 1 << 13,
3270
3271                         DecomposedMask  = 1 << 19,
3272                         NullableMask    = 1 << 20
3273                 }
3274
3275                 [Flags]
3276                 public enum State : byte
3277                 {
3278                         None = 0,
3279                         Compound = 1 << 1,
3280                         UserOperatorsExcluded = 1 << 2
3281                 }
3282
3283                 readonly Operator oper;
3284                 Expression left, right;
3285                 State state;
3286                 ConvCast.Mode enum_conversion;
3287
3288                 public Binary (Operator oper, Expression left, Expression right, bool isCompound)
3289                         : this (oper, left, right, State.Compound)
3290                 {
3291                 }
3292
3293                 public Binary (Operator oper, Expression left, Expression right, State state)
3294                         : this (oper, left, right)
3295                 {
3296                         this.state = state;
3297                 }
3298
3299                 public Binary (Operator oper, Expression left, Expression right)
3300                         : this (oper, left, right, left.Location)
3301                 {
3302                 }
3303
3304                 public Binary (Operator oper, Expression left, Expression right, Location loc)
3305                 {
3306                         this.oper = oper;
3307                         this.left = left;
3308                         this.right = right;
3309                         this.loc = loc;
3310                 }
3311
3312                 #region Properties
3313
3314                 public bool IsCompound {
3315                         get {
3316                                 return (state & State.Compound) != 0;
3317                         }
3318                 }
3319
3320                 public Operator Oper {
3321                         get {
3322                                 return oper;
3323                         }
3324                 }
3325
3326                 public Expression Left {
3327                         get {
3328                                 return this.left;
3329                         }
3330                 }
3331
3332                 public Expression Right {
3333                         get {
3334                                 return this.right;
3335                         }
3336                 }
3337
3338                 public override Location StartLocation {
3339                         get {
3340                                 return left.StartLocation;
3341                         }
3342                 }
3343
3344                 #endregion
3345
3346                 /// <summary>
3347                 ///   Returns a stringified representation of the Operator
3348                 /// </summary>
3349                 string OperName (Operator oper)
3350                 {
3351                         string s;
3352                         switch (oper){
3353                         case Operator.Multiply:
3354                                 s = "*";
3355                                 break;
3356                         case Operator.Division:
3357                                 s = "/";
3358                                 break;
3359                         case Operator.Modulus:
3360                                 s = "%";
3361                                 break;
3362                         case Operator.Addition:
3363                                 s = "+";
3364                                 break;
3365                         case Operator.Subtraction:
3366                                 s = "-";
3367                                 break;
3368                         case Operator.LeftShift:
3369                                 s = "<<";
3370                                 break;
3371                         case Operator.RightShift:
3372                                 s = ">>";
3373                                 break;
3374                         case Operator.LessThan:
3375                                 s = "<";
3376                                 break;
3377                         case Operator.GreaterThan:
3378                                 s = ">";
3379                                 break;
3380                         case Operator.LessThanOrEqual:
3381                                 s = "<=";
3382                                 break;
3383                         case Operator.GreaterThanOrEqual:
3384                                 s = ">=";
3385                                 break;
3386                         case Operator.Equality:
3387                                 s = "==";
3388                                 break;
3389                         case Operator.Inequality:
3390                                 s = "!=";
3391                                 break;
3392                         case Operator.BitwiseAnd:
3393                                 s = "&";
3394                                 break;
3395                         case Operator.BitwiseOr:
3396                                 s = "|";
3397                                 break;
3398                         case Operator.ExclusiveOr:
3399                                 s = "^";
3400                                 break;
3401                         case Operator.LogicalOr:
3402                                 s = "||";
3403                                 break;
3404                         case Operator.LogicalAnd:
3405                                 s = "&&";
3406                                 break;
3407                         default:
3408                                 s = oper.ToString ();
3409                                 break;
3410                         }
3411
3412                         if (IsCompound)
3413                                 return s + "=";
3414
3415                         return s;
3416                 }
3417
3418                 public static void Error_OperatorCannotBeApplied (ResolveContext ec, Expression left, Expression right, Operator oper, Location loc)
3419                 {
3420                         new Binary (oper, left, right).Error_OperatorCannotBeApplied (ec, left, right);
3421                 }
3422
3423                 public static void Error_OperatorCannotBeApplied (ResolveContext ec, Expression left, Expression right, string oper, Location loc)
3424                 {
3425                         if (left.Type == InternalType.ErrorType || right.Type == InternalType.ErrorType)
3426                                 return;
3427
3428                         string l, r;
3429                         l = left.Type.GetSignatureForError ();
3430                         r = right.Type.GetSignatureForError ();
3431
3432                         ec.Report.Error (19, loc, "Operator `{0}' cannot be applied to operands of type `{1}' and `{2}'",
3433                                 oper, l, r);
3434                 }
3435
3436                 void Error_OperatorCannotBeApplied (ResolveContext ec, Expression left, Expression right)
3437                 {
3438                         Error_OperatorCannotBeApplied (ec, left, right, OperName (oper), loc);
3439                 }
3440
3441                 public override void FlowAnalysis (FlowAnalysisContext fc)
3442                 {
3443                         //
3444                         // Optimized version when on-true/on-false data are not needed
3445                         //
3446                         if ((oper & Operator.LogicalMask) == 0) {
3447                                 left.FlowAnalysis (fc);
3448                                 right.FlowAnalysis (fc);
3449                                 return;
3450                         }
3451
3452                         left.FlowAnalysisConditional (fc);
3453                         var left_fc_ontrue = fc.DefiniteAssignmentOnTrue;
3454                         var left_fc_onfalse = fc.DefiniteAssignmentOnFalse;
3455
3456                         fc.DefiniteAssignmentOnTrue = fc.DefiniteAssignmentOnFalse = fc.DefiniteAssignment = new DefiniteAssignmentBitSet (
3457                                 oper == Operator.LogicalOr ? left_fc_onfalse : left_fc_ontrue);
3458                         right.FlowAnalysisConditional (fc);
3459
3460                         if (oper == Operator.LogicalOr)
3461                                 fc.DefiniteAssignment = (left_fc_onfalse | (fc.DefiniteAssignmentOnFalse & fc.DefiniteAssignmentOnTrue)) & left_fc_ontrue;
3462                         else
3463                                 fc.DefiniteAssignment = (left_fc_ontrue | (fc.DefiniteAssignmentOnFalse & fc.DefiniteAssignmentOnTrue)) & left_fc_onfalse;
3464                 }
3465
3466                 public override void FlowAnalysisConditional (FlowAnalysisContext fc)
3467                 {
3468                         if ((oper & Operator.LogicalMask) == 0) {
3469                                 base.FlowAnalysisConditional (fc);
3470                                 return;
3471                         }
3472
3473                         left.FlowAnalysisConditional (fc);
3474                         var left_fc_ontrue = fc.DefiniteAssignmentOnTrue;
3475                         var left_fc_onfalse = fc.DefiniteAssignmentOnFalse;
3476
3477                         fc.DefiniteAssignmentOnTrue = fc.DefiniteAssignmentOnFalse = fc.DefiniteAssignment = new DefiniteAssignmentBitSet (
3478                                 oper == Operator.LogicalOr ? left_fc_onfalse : left_fc_ontrue);
3479                         right.FlowAnalysisConditional (fc);
3480
3481                         var lc = left as Constant;
3482                         if (oper == Operator.LogicalOr) {
3483                                 fc.DefiniteAssignmentOnFalse = left_fc_onfalse | fc.DefiniteAssignmentOnFalse;
3484                                 if (lc != null && lc.IsDefaultValue)
3485                                         fc.DefiniteAssignmentOnTrue = fc.DefiniteAssignmentOnFalse;
3486                                 else
3487                                         fc.DefiniteAssignmentOnTrue = new DefiniteAssignmentBitSet (left_fc_ontrue & (left_fc_onfalse | fc.DefiniteAssignmentOnTrue));
3488                         } else {
3489                                 fc.DefiniteAssignmentOnTrue = left_fc_ontrue | fc.DefiniteAssignmentOnTrue;
3490                                 if (lc != null && !lc.IsDefaultValue)
3491                                         fc.DefiniteAssignmentOnFalse = fc.DefiniteAssignmentOnTrue;
3492                                 else
3493                                         fc.DefiniteAssignmentOnFalse = new DefiniteAssignmentBitSet ((left_fc_ontrue | fc.DefiniteAssignmentOnFalse) & left_fc_onfalse);
3494                         }
3495                 }
3496
3497                 //
3498                 // Converts operator to System.Linq.Expressions.ExpressionType enum name
3499                 //
3500                 string GetOperatorExpressionTypeName ()
3501                 {
3502                         switch (oper) {
3503                         case Operator.Addition:
3504                                 return IsCompound ? "AddAssign" : "Add";
3505                         case Operator.BitwiseAnd:
3506                                 return IsCompound ? "AndAssign" : "And";
3507                         case Operator.BitwiseOr:
3508                                 return IsCompound ? "OrAssign" : "Or";
3509                         case Operator.Division:
3510                                 return IsCompound ? "DivideAssign" : "Divide";
3511                         case Operator.ExclusiveOr:
3512                                 return IsCompound ? "ExclusiveOrAssign" : "ExclusiveOr";
3513                         case Operator.Equality:
3514                                 return "Equal";
3515                         case Operator.GreaterThan:
3516                                 return "GreaterThan";
3517                         case Operator.GreaterThanOrEqual:
3518                                 return "GreaterThanOrEqual";
3519                         case Operator.Inequality:
3520                                 return "NotEqual";
3521                         case Operator.LeftShift:
3522                                 return IsCompound ? "LeftShiftAssign" : "LeftShift";
3523                         case Operator.LessThan:
3524                                 return "LessThan";
3525                         case Operator.LessThanOrEqual:
3526                                 return "LessThanOrEqual";
3527                         case Operator.LogicalAnd:
3528                                 return "And";
3529                         case Operator.LogicalOr:
3530                                 return "Or";
3531                         case Operator.Modulus:
3532                                 return IsCompound ? "ModuloAssign" : "Modulo";
3533                         case Operator.Multiply:
3534                                 return IsCompound ? "MultiplyAssign" : "Multiply";
3535                         case Operator.RightShift:
3536                                 return IsCompound ? "RightShiftAssign" : "RightShift";
3537                         case Operator.Subtraction:
3538                                 return IsCompound ? "SubtractAssign" : "Subtract";
3539                         default:
3540                                 throw new NotImplementedException ("Unknown expression type operator " + oper.ToString ());
3541                         }
3542                 }
3543
3544                 public static CSharp.Operator.OpType ConvertBinaryToUserOperator (Operator op)
3545                 {
3546                         switch (op) {
3547                         case Operator.Addition:
3548                                 return CSharp.Operator.OpType.Addition;
3549                         case Operator.BitwiseAnd:
3550                         case Operator.LogicalAnd:
3551                                 return CSharp.Operator.OpType.BitwiseAnd;
3552                         case Operator.BitwiseOr:
3553                         case Operator.LogicalOr:
3554                                 return CSharp.Operator.OpType.BitwiseOr;
3555                         case Operator.Division:
3556                                 return CSharp.Operator.OpType.Division;
3557                         case Operator.Equality:
3558                                 return CSharp.Operator.OpType.Equality;
3559                         case Operator.ExclusiveOr:
3560                                 return CSharp.Operator.OpType.ExclusiveOr;
3561                         case Operator.GreaterThan:
3562                                 return CSharp.Operator.OpType.GreaterThan;
3563                         case Operator.GreaterThanOrEqual:
3564                                 return CSharp.Operator.OpType.GreaterThanOrEqual;
3565                         case Operator.Inequality:
3566                                 return CSharp.Operator.OpType.Inequality;
3567                         case Operator.LeftShift:
3568                                 return CSharp.Operator.OpType.LeftShift;
3569                         case Operator.LessThan:
3570                                 return CSharp.Operator.OpType.LessThan;
3571                         case Operator.LessThanOrEqual:
3572                                 return CSharp.Operator.OpType.LessThanOrEqual;
3573                         case Operator.Modulus:
3574                                 return CSharp.Operator.OpType.Modulus;
3575                         case Operator.Multiply:
3576                                 return CSharp.Operator.OpType.Multiply;
3577                         case Operator.RightShift:
3578                                 return CSharp.Operator.OpType.RightShift;
3579                         case Operator.Subtraction:
3580                                 return CSharp.Operator.OpType.Subtraction;
3581                         default:
3582                                 throw new InternalErrorException (op.ToString ());
3583                         }
3584                 }
3585
3586                 public override bool ContainsEmitWithAwait ()
3587                 {
3588                         return left.ContainsEmitWithAwait () || right.ContainsEmitWithAwait ();
3589                 }
3590
3591                 public static void EmitOperatorOpcode (EmitContext ec, Operator oper, TypeSpec l, Expression right)
3592                 {
3593                         OpCode opcode;
3594
3595                         switch (oper){
3596                         case Operator.Multiply:
3597                                 if (ec.HasSet (EmitContext.Options.CheckedScope)) {
3598                                         if (l.BuiltinType == BuiltinTypeSpec.Type.Int || l.BuiltinType == BuiltinTypeSpec.Type.Long)
3599                                                 opcode = OpCodes.Mul_Ovf;
3600                                         else if (!IsFloat (l))
3601                                                 opcode = OpCodes.Mul_Ovf_Un;
3602                                         else
3603                                                 opcode = OpCodes.Mul;
3604                                 } else
3605                                         opcode = OpCodes.Mul;
3606
3607                                 break;
3608
3609                         case Operator.Division:
3610                                 if (IsUnsigned (l))
3611                                         opcode = OpCodes.Div_Un;
3612                                 else
3613                                         opcode = OpCodes.Div;
3614                                 break;
3615
3616                         case Operator.Modulus:
3617                                 if (IsUnsigned (l))
3618                                         opcode = OpCodes.Rem_Un;
3619                                 else
3620                                         opcode = OpCodes.Rem;
3621                                 break;
3622
3623                         case Operator.Addition:
3624                                 if (ec.HasSet (EmitContext.Options.CheckedScope)) {
3625                                         if (l.BuiltinType == BuiltinTypeSpec.Type.Int || l.BuiltinType == BuiltinTypeSpec.Type.Long)
3626                                                 opcode = OpCodes.Add_Ovf;
3627                                         else if (!IsFloat (l))
3628                                                 opcode = OpCodes.Add_Ovf_Un;
3629                                         else
3630                                                 opcode = OpCodes.Add;
3631                                 } else
3632                                         opcode = OpCodes.Add;
3633                                 break;
3634
3635                         case Operator.Subtraction:
3636                                 if (ec.HasSet (EmitContext.Options.CheckedScope)) {
3637                                         if (l.BuiltinType == BuiltinTypeSpec.Type.Int || l.BuiltinType == BuiltinTypeSpec.Type.Long)
3638                                                 opcode = OpCodes.Sub_Ovf;
3639                                         else if (!IsFloat (l))
3640                                                 opcode = OpCodes.Sub_Ovf_Un;
3641                                         else
3642                                                 opcode = OpCodes.Sub;
3643                                 } else
3644                                         opcode = OpCodes.Sub;
3645                                 break;
3646
3647                         case Operator.RightShift:
3648                                 if (!(right is IntConstant)) {
3649                                         ec.EmitInt (GetShiftMask (l));
3650                                         ec.Emit (OpCodes.And);
3651                                 }
3652
3653                                 if (IsUnsigned (l))
3654                                         opcode = OpCodes.Shr_Un;
3655                                 else
3656                                         opcode = OpCodes.Shr;
3657                                 break;
3658
3659                         case Operator.LeftShift:
3660                                 if (!(right is IntConstant)) {
3661                                         ec.EmitInt (GetShiftMask (l));
3662                                         ec.Emit (OpCodes.And);
3663                                 }
3664
3665                                 opcode = OpCodes.Shl;
3666                                 break;
3667
3668                         case Operator.Equality:
3669                                 opcode = OpCodes.Ceq;
3670                                 break;
3671
3672                         case Operator.Inequality:
3673                                 ec.Emit (OpCodes.Ceq);
3674                                 ec.EmitInt (0);
3675
3676                                 opcode = OpCodes.Ceq;
3677                                 break;
3678
3679                         case Operator.LessThan:
3680                                 if (IsUnsigned (l))
3681                                         opcode = OpCodes.Clt_Un;
3682                                 else
3683                                         opcode = OpCodes.Clt;
3684                                 break;
3685
3686                         case Operator.GreaterThan:
3687                                 if (IsUnsigned (l))
3688                                         opcode = OpCodes.Cgt_Un;
3689                                 else
3690                                         opcode = OpCodes.Cgt;
3691                                 break;
3692
3693                         case Operator.LessThanOrEqual:
3694                                 if (IsUnsigned (l) || IsFloat (l))
3695                                         ec.Emit (OpCodes.Cgt_Un);
3696                                 else
3697                                         ec.Emit (OpCodes.Cgt);
3698                                 ec.EmitInt (0);
3699
3700                                 opcode = OpCodes.Ceq;
3701                                 break;
3702
3703                         case Operator.GreaterThanOrEqual:
3704                                 if (IsUnsigned (l) || IsFloat (l))
3705                                         ec.Emit (OpCodes.Clt_Un);
3706                                 else
3707                                         ec.Emit (OpCodes.Clt);
3708
3709                                 ec.EmitInt (0);
3710
3711                                 opcode = OpCodes.Ceq;
3712                                 break;
3713
3714                         case Operator.BitwiseOr:
3715                                 opcode = OpCodes.Or;
3716                                 break;
3717
3718                         case Operator.BitwiseAnd:
3719                                 opcode = OpCodes.And;
3720                                 break;
3721
3722                         case Operator.ExclusiveOr:
3723                                 opcode = OpCodes.Xor;
3724                                 break;
3725
3726                         default:
3727                                 throw new InternalErrorException (oper.ToString ());
3728                         }
3729
3730                         ec.Emit (opcode);
3731                 }
3732
3733                 static int GetShiftMask (TypeSpec type)
3734                 {
3735                         return type.BuiltinType == BuiltinTypeSpec.Type.Int || type.BuiltinType == BuiltinTypeSpec.Type.UInt ? 0x1f : 0x3f;
3736                 }
3737
3738                 static bool IsUnsigned (TypeSpec t)
3739                 {
3740                         switch (t.BuiltinType) {
3741                         case BuiltinTypeSpec.Type.Char:
3742                         case BuiltinTypeSpec.Type.UInt:
3743                         case BuiltinTypeSpec.Type.ULong:
3744                         case BuiltinTypeSpec.Type.UShort:
3745                         case BuiltinTypeSpec.Type.Byte:
3746                                 return true;
3747                         }
3748
3749                         return t.IsPointer;
3750                 }
3751
3752                 static bool IsFloat (TypeSpec t)
3753                 {
3754                         return t.BuiltinType == BuiltinTypeSpec.Type.Float || t.BuiltinType == BuiltinTypeSpec.Type.Double;
3755                 }
3756
3757                 public Expression ResolveOperator (ResolveContext rc)
3758                 {
3759                         eclass = ExprClass.Value;
3760
3761                         TypeSpec l = left.Type;
3762                         TypeSpec r = right.Type;
3763                         Expression expr;
3764                         bool primitives_only = false;
3765
3766                         //
3767                         // Handles predefined primitive types
3768                         //
3769                         if ((BuiltinTypeSpec.IsPrimitiveType (l) || (l.IsNullableType && BuiltinTypeSpec.IsPrimitiveType (Nullable.NullableInfo.GetUnderlyingType (l)))) &&
3770                                 (BuiltinTypeSpec.IsPrimitiveType (r) || (r.IsNullableType && BuiltinTypeSpec.IsPrimitiveType (Nullable.NullableInfo.GetUnderlyingType (r))))) {
3771                                 if ((oper & Operator.ShiftMask) == 0) {
3772                                         if (!DoBinaryOperatorPromotion (rc))
3773                                                 return null;
3774
3775                                         primitives_only = BuiltinTypeSpec.IsPrimitiveType (l) && BuiltinTypeSpec.IsPrimitiveType (r);
3776                                 }
3777                         } else {
3778                                 // Pointers
3779                                 if (l.IsPointer || r.IsPointer)
3780                                         return ResolveOperatorPointer (rc, l, r);
3781
3782                                 // User operators
3783                                 if ((state & State.UserOperatorsExcluded) == 0) {
3784                                         expr = ResolveUserOperator (rc, left, right);
3785                                         if (expr != null)
3786                                                 return expr;
3787                                 }
3788
3789                                 bool lenum = l.IsEnum;
3790                                 bool renum = r.IsEnum;
3791                                 if ((oper & (Operator.ComparisonMask | Operator.BitwiseMask)) != 0) {
3792                                         //
3793                                         // Enumerations
3794                                         //
3795                                         if (IsEnumOrNullableEnum (l) || IsEnumOrNullableEnum (r)) {
3796                                                 expr = ResolveSingleEnumOperators (rc, lenum, renum, l, r);
3797
3798                                                 if (expr == null)
3799                                                         return null;
3800
3801                                                 if ((oper & Operator.BitwiseMask) != 0) {
3802                                                         expr = EmptyCast.Create (expr, type);
3803                                                         enum_conversion = GetEnumResultCast (type);
3804
3805                                                         if (oper == Operator.BitwiseAnd && left.Type.IsEnum && right.Type.IsEnum) {
3806                                                                 expr = OptimizeAndOperation (expr);
3807                                                         }
3808                                                 }
3809
3810                                                 left = ConvertEnumOperandToUnderlyingType (rc, left, r.IsNullableType);
3811                                                 right = ConvertEnumOperandToUnderlyingType (rc, right, l.IsNullableType);
3812                                                 return expr;
3813                                         }
3814                                 } else if ((oper == Operator.Addition || oper == Operator.Subtraction)) {
3815                                         if (IsEnumOrNullableEnum (l) || IsEnumOrNullableEnum (r)) {
3816                                                 //
3817                                                 // Enumerations
3818                                                 //
3819                                                 expr = ResolveEnumOperators (rc, lenum, renum, l, r);
3820
3821                                                 //
3822                                                 // We cannot break here there is also Enum + String possible match
3823                                                 // which is not ambiguous with predefined enum operators
3824                                                 //
3825                                                 if (expr != null) {
3826                                                         left = ConvertEnumOperandToUnderlyingType (rc, left, false);
3827                                                         right = ConvertEnumOperandToUnderlyingType (rc, right, false);
3828
3829                                                         return expr;
3830                                                 }
3831                                         } else if (l.IsDelegate || r.IsDelegate) {
3832                                                 //
3833                                                 // Delegates
3834                                                 //
3835                                                 expr = ResolveOperatorDelegate (rc, l, r);
3836
3837                                                 // TODO: Can this be ambiguous
3838                                                 if (expr != null)
3839                                                         return expr;
3840                                         }
3841                                 }
3842                         }
3843
3844                         //
3845                         // Equality operators are more complicated
3846                         //
3847                         if ((oper & Operator.EqualityMask) != 0) {
3848                                 return ResolveEquality (rc, l, r, primitives_only);
3849                         }
3850
3851                         expr = ResolveOperatorPredefined (rc, rc.BuiltinTypes.OperatorsBinaryStandard, primitives_only);
3852                         if (expr != null)
3853                                 return expr;
3854
3855                         if (primitives_only)
3856                                 return null;
3857
3858                         //
3859                         // Lifted operators have lower priority
3860                         //
3861                         return ResolveOperatorPredefined (rc, rc.Module.OperatorsBinaryLifted, false);
3862                 }
3863
3864                 static bool IsEnumOrNullableEnum (TypeSpec type)
3865                 {
3866                         return type.IsEnum || (type.IsNullableType && Nullable.NullableInfo.GetUnderlyingType (type).IsEnum);
3867                 }
3868
3869
3870                 // at least one of 'left' or 'right' is an enumeration constant (EnumConstant or SideEffectConstant or ...)
3871                 // if 'left' is not an enumeration constant, create one from the type of 'right'
3872                 Constant EnumLiftUp (ResolveContext ec, Constant left, Constant right)
3873                 {
3874                         switch (oper) {
3875                         case Operator.BitwiseOr:
3876                         case Operator.BitwiseAnd:
3877                         case Operator.ExclusiveOr:
3878                         case Operator.Equality:
3879                         case Operator.Inequality:
3880                         case Operator.LessThan:
3881                         case Operator.LessThanOrEqual:
3882                         case Operator.GreaterThan:
3883                         case Operator.GreaterThanOrEqual:
3884                                 if (left.Type.IsEnum)
3885                                         return left;
3886
3887                                 if (left.IsZeroInteger)
3888                                         return left.Reduce (ec, right.Type);
3889
3890                                 break;
3891
3892                         case Operator.Addition:
3893                         case Operator.Subtraction:
3894                                 return left;
3895
3896                         case Operator.Multiply:
3897                         case Operator.Division:
3898                         case Operator.Modulus:
3899                         case Operator.LeftShift:
3900                         case Operator.RightShift:
3901                                 if (right.Type.IsEnum || left.Type.IsEnum)
3902                                         break;
3903                                 return left;
3904                         }
3905
3906                         return null;
3907                 }
3908
3909                 //
3910                 // The `|' operator used on types which were extended is dangerous
3911                 //
3912                 void CheckBitwiseOrOnSignExtended (ResolveContext ec)
3913                 {
3914                         OpcodeCast lcast = left as OpcodeCast;
3915                         if (lcast != null) {
3916                                 if (IsUnsigned (lcast.UnderlyingType))
3917                                         lcast = null;
3918                         }
3919
3920                         OpcodeCast rcast = right as OpcodeCast;
3921                         if (rcast != null) {
3922                                 if (IsUnsigned (rcast.UnderlyingType))
3923                                         rcast = null;
3924                         }
3925
3926                         if (lcast == null && rcast == null)
3927                                 return;
3928
3929                         // FIXME: consider constants
3930
3931                         var ltype = lcast != null ? lcast.UnderlyingType : rcast.UnderlyingType;
3932                         ec.Report.Warning (675, 3, loc,
3933                                 "The operator `|' used on the sign-extended type `{0}'. Consider casting to a smaller unsigned type first",
3934                                 ltype.GetSignatureForError ());
3935                 }
3936
3937                 public static PredefinedOperator[] CreatePointerOperatorsTable (BuiltinTypes types)
3938                 {
3939                         return new PredefinedOperator[] {
3940                                 //
3941                                 // Pointer arithmetic:
3942                                 //
3943                                 // T* operator + (T* x, int y);         T* operator - (T* x, int y);
3944                                 // T* operator + (T* x, uint y);        T* operator - (T* x, uint y);
3945                                 // T* operator + (T* x, long y);        T* operator - (T* x, long y);
3946                                 // T* operator + (T* x, ulong y);       T* operator - (T* x, ulong y);
3947                                 //
3948                                 new PredefinedPointerOperator (null, types.Int, Operator.AdditionMask | Operator.SubtractionMask),
3949                                 new PredefinedPointerOperator (null, types.UInt, Operator.AdditionMask | Operator.SubtractionMask),
3950                                 new PredefinedPointerOperator (null, types.Long, Operator.AdditionMask | Operator.SubtractionMask),
3951                                 new PredefinedPointerOperator (null, types.ULong, Operator.AdditionMask | Operator.SubtractionMask),
3952
3953                                 //
3954                                 // T* operator + (int y,   T* x);
3955                                 // T* operator + (uint y,  T *x);
3956                                 // T* operator + (long y,  T *x);
3957                                 // T* operator + (ulong y, T *x);
3958                                 //
3959                                 new PredefinedPointerOperator (types.Int, null, Operator.AdditionMask, null),
3960                                 new PredefinedPointerOperator (types.UInt, null, Operator.AdditionMask, null),
3961                                 new PredefinedPointerOperator (types.Long, null, Operator.AdditionMask, null),
3962                                 new PredefinedPointerOperator (types.ULong, null, Operator.AdditionMask, null),
3963
3964                                 //
3965                                 // long operator - (T* x, T *y)
3966                                 //
3967                                 new PredefinedPointerOperator (null, Operator.SubtractionMask, types.Long)
3968                         };
3969                 }
3970
3971                 public static PredefinedOperator[] CreateStandardOperatorsTable (BuiltinTypes types)
3972                 {
3973                         TypeSpec bool_type = types.Bool;
3974
3975                         return new [] {
3976                                 new PredefinedOperator (types.Int, Operator.ArithmeticMask | Operator.BitwiseMask | Operator.ShiftMask),
3977                                 new PredefinedOperator (types.UInt, Operator.ArithmeticMask | Operator.BitwiseMask),
3978                                 new PredefinedOperator (types.Long, Operator.ArithmeticMask | Operator.BitwiseMask),
3979                                 new PredefinedOperator (types.ULong, Operator.ArithmeticMask | Operator.BitwiseMask),
3980                                 new PredefinedOperator (types.Float, Operator.ArithmeticMask),
3981                                 new PredefinedOperator (types.Double, Operator.ArithmeticMask),
3982                                 new PredefinedOperator (types.Decimal, Operator.ArithmeticMask),
3983
3984                                 new PredefinedOperator (types.Int, Operator.ComparisonMask, bool_type),
3985                                 new PredefinedOperator (types.UInt, Operator.ComparisonMask, bool_type),
3986                                 new PredefinedOperator (types.Long, Operator.ComparisonMask, bool_type),
3987                                 new PredefinedOperator (types.ULong, Operator.ComparisonMask, bool_type),
3988                                 new PredefinedOperator (types.Float, Operator.ComparisonMask, bool_type),
3989                                 new PredefinedOperator (types.Double, Operator.ComparisonMask, bool_type),
3990                                 new PredefinedOperator (types.Decimal, Operator.ComparisonMask, bool_type),
3991
3992                                 new PredefinedStringOperator (types.String, Operator.AdditionMask, types.String),
3993                                 // Remaining string operators are in lifted tables
3994
3995                                 new PredefinedOperator (bool_type, Operator.BitwiseMask | Operator.LogicalMask | Operator.EqualityMask, bool_type),
3996
3997                                 new PredefinedOperator (types.UInt, types.Int, Operator.ShiftMask),
3998                                 new PredefinedOperator (types.Long, types.Int, Operator.ShiftMask),
3999                                 new PredefinedOperator (types.ULong, types.Int, Operator.ShiftMask)
4000                         };
4001
4002                 }
4003                 public static PredefinedOperator[] CreateStandardLiftedOperatorsTable (ModuleContainer module)
4004                 {
4005                         var types = module.Compiler.BuiltinTypes;
4006
4007                         //
4008                         // Not strictly lifted but need to be in second group otherwise expressions like
4009                         // int + null would resolve to +(object, string) instead of +(int?, int?)
4010                         //
4011                         var string_operators = new [] {
4012                                 new PredefinedStringOperator (types.String, types.Object, Operator.AdditionMask, types.String),
4013                                 new PredefinedStringOperator (types.Object, types.String, Operator.AdditionMask, types.String),
4014                         };
4015
4016                         var nullable = module.PredefinedTypes.Nullable.TypeSpec;
4017                         if (nullable == null)
4018                                 return string_operators;
4019
4020                         var bool_type = types.Bool;
4021
4022                         var nullable_bool = nullable.MakeGenericType (module, new[] { bool_type });
4023                         var nullable_int = nullable.MakeGenericType (module, new[] { types.Int });
4024                         var nullable_uint = nullable.MakeGenericType (module, new[] { types.UInt });
4025                         var nullable_long = nullable.MakeGenericType (module, new[] { types.Long });
4026                         var nullable_ulong = nullable.MakeGenericType (module, new[] { types.ULong });
4027                         var nullable_float = nullable.MakeGenericType (module, new[] { types.Float });
4028                         var nullable_double = nullable.MakeGenericType (module, new[] { types.Double });
4029                         var nullable_decimal = nullable.MakeGenericType (module, new[] { types.Decimal });
4030
4031                         return new[] {
4032                                 new PredefinedOperator (nullable_int, Operator.NullableMask | Operator.ArithmeticMask | Operator.BitwiseMask | Operator.ShiftMask),
4033                                 new PredefinedOperator (nullable_uint, Operator.NullableMask | Operator.ArithmeticMask | Operator.BitwiseMask),
4034                                 new PredefinedOperator (nullable_long, Operator.NullableMask | Operator.ArithmeticMask | Operator.BitwiseMask),
4035                                 new PredefinedOperator (nullable_ulong, Operator.NullableMask | Operator.ArithmeticMask | Operator.BitwiseMask),
4036                                 new PredefinedOperator (nullable_float, Operator.NullableMask | Operator.ArithmeticMask),
4037                                 new PredefinedOperator (nullable_double, Operator.NullableMask | Operator.ArithmeticMask),
4038                                 new PredefinedOperator (nullable_decimal, Operator.NullableMask | Operator.ArithmeticMask),
4039
4040                                 new PredefinedOperator (nullable_int, Operator.NullableMask | Operator.ComparisonMask, bool_type),
4041                                 new PredefinedOperator (nullable_uint, Operator.NullableMask | Operator.ComparisonMask, bool_type),
4042                                 new PredefinedOperator (nullable_long, Operator.NullableMask | Operator.ComparisonMask, bool_type),
4043                                 new PredefinedOperator (nullable_ulong, Operator.NullableMask | Operator.ComparisonMask, bool_type),
4044                                 new PredefinedOperator (nullable_float, Operator.NullableMask | Operator.ComparisonMask, bool_type),
4045                                 new PredefinedOperator (nullable_double, Operator.NullableMask | Operator.ComparisonMask, bool_type),
4046                                 new PredefinedOperator (nullable_decimal, Operator.NullableMask | Operator.ComparisonMask, bool_type),
4047
4048                                 new PredefinedOperator (nullable_bool, Operator.NullableMask | Operator.BitwiseMask, nullable_bool),
4049
4050                                 new PredefinedOperator (nullable_uint, nullable_int, Operator.NullableMask | Operator.ShiftMask),
4051                                 new PredefinedOperator (nullable_long, nullable_int, Operator.NullableMask | Operator.ShiftMask),
4052                                 new PredefinedOperator (nullable_ulong, nullable_int, Operator.NullableMask | Operator.ShiftMask),
4053
4054                                 string_operators [0],
4055                                 string_operators [1]
4056                         };
4057                 }
4058
4059                 public static PredefinedOperator[] CreateEqualityOperatorsTable (BuiltinTypes types)
4060                 {
4061                         TypeSpec bool_type = types.Bool;
4062
4063                         return new[] {
4064                                 new PredefinedEqualityOperator (types.String, bool_type),
4065                                 new PredefinedEqualityOperator (types.Delegate, bool_type),
4066                                 new PredefinedOperator (bool_type, Operator.EqualityMask, bool_type),
4067                                 new PredefinedOperator (types.Int, Operator.EqualityMask, bool_type),
4068                                 new PredefinedOperator (types.UInt, Operator.EqualityMask, bool_type),
4069                                 new PredefinedOperator (types.Long, Operator.EqualityMask, bool_type),
4070                                 new PredefinedOperator (types.ULong, Operator.EqualityMask, bool_type),
4071                                 new PredefinedOperator (types.Float, Operator.EqualityMask, bool_type),
4072                                 new PredefinedOperator (types.Double, Operator.EqualityMask, bool_type),
4073                                 new PredefinedOperator (types.Decimal, Operator.EqualityMask, bool_type),
4074                         };
4075                 }
4076
4077                 public static PredefinedOperator[] CreateEqualityLiftedOperatorsTable (ModuleContainer module)
4078                 {
4079                         var nullable = module.PredefinedTypes.Nullable.TypeSpec;
4080
4081                         if (nullable == null)
4082                                 return new PredefinedOperator [0];
4083
4084                         var types = module.Compiler.BuiltinTypes;
4085                         var bool_type = types.Bool;
4086                         var nullable_bool = nullable.MakeGenericType (module, new [] { bool_type });
4087                         var nullable_int = nullable.MakeGenericType (module, new[] { types.Int });
4088                         var nullable_uint = nullable.MakeGenericType (module, new[] { types.UInt });
4089                         var nullable_long = nullable.MakeGenericType (module, new[] { types.Long });
4090                         var nullable_ulong = nullable.MakeGenericType (module, new[] { types.ULong });
4091                         var nullable_float = nullable.MakeGenericType (module, new[] { types.Float });
4092                         var nullable_double = nullable.MakeGenericType (module, new[] { types.Double });
4093                         var nullable_decimal = nullable.MakeGenericType (module, new[] { types.Decimal });
4094
4095                         return new [] {
4096                                 new PredefinedOperator (nullable_bool, Operator.NullableMask | Operator.EqualityMask, bool_type),
4097                                 new PredefinedOperator (nullable_int, Operator.NullableMask | Operator.EqualityMask, bool_type),
4098                                 new PredefinedOperator (nullable_uint, Operator.NullableMask | Operator.EqualityMask, bool_type),
4099                                 new PredefinedOperator (nullable_long, Operator.NullableMask | Operator.EqualityMask, bool_type),
4100                                 new PredefinedOperator (nullable_ulong, Operator.NullableMask | Operator.EqualityMask, bool_type),
4101                                 new PredefinedOperator (nullable_float, Operator.NullableMask | Operator.EqualityMask, bool_type),
4102                                 new PredefinedOperator (nullable_double, Operator.NullableMask | Operator.EqualityMask, bool_type),
4103                                 new PredefinedOperator (nullable_decimal, Operator.NullableMask | Operator.EqualityMask, bool_type)
4104                         };
4105                 }
4106
4107                 //
4108                 // 7.2.6.2 Binary numeric promotions
4109                 //
4110                 bool DoBinaryOperatorPromotion (ResolveContext rc)
4111                 {
4112                         TypeSpec ltype = left.Type;
4113                         if (ltype.IsNullableType) {
4114                                 ltype = Nullable.NullableInfo.GetUnderlyingType (ltype);
4115                         }
4116
4117                         //
4118                         // This is numeric promotion code only
4119                         //
4120                         if (ltype.BuiltinType == BuiltinTypeSpec.Type.Bool)
4121                                 return true;
4122
4123                         TypeSpec rtype = right.Type;
4124                         if (rtype.IsNullableType) {
4125                                 rtype = Nullable.NullableInfo.GetUnderlyingType (rtype);
4126                         }
4127
4128                         var lb = ltype.BuiltinType;
4129                         var rb = rtype.BuiltinType;
4130                         TypeSpec type;
4131                         Expression expr;
4132
4133                         if (lb == BuiltinTypeSpec.Type.Decimal || rb == BuiltinTypeSpec.Type.Decimal) {
4134                                 type = rc.BuiltinTypes.Decimal;
4135                         } else if (lb == BuiltinTypeSpec.Type.Double || rb == BuiltinTypeSpec.Type.Double) {
4136                                 type = rc.BuiltinTypes.Double;
4137                         } else if (lb == BuiltinTypeSpec.Type.Float || rb == BuiltinTypeSpec.Type.Float) {
4138                                 type = rc.BuiltinTypes.Float;
4139                         } else if (lb == BuiltinTypeSpec.Type.ULong || rb == BuiltinTypeSpec.Type.ULong) {
4140                                 type = rc.BuiltinTypes.ULong;
4141
4142                                 if (IsSignedType (lb)) {
4143                                         expr = ConvertSignedConstant (left, type);
4144                                         if (expr == null)
4145                                                 return false;
4146                                         left = expr;
4147                                 } else if (IsSignedType (rb)) {
4148                                         expr = ConvertSignedConstant (right, type);
4149                                         if (expr == null)
4150                                                 return false;
4151                                         right = expr;
4152                                 }
4153
4154                         } else if (lb == BuiltinTypeSpec.Type.Long || rb == BuiltinTypeSpec.Type.Long) {
4155                                 type = rc.BuiltinTypes.Long;
4156                         } else if (lb == BuiltinTypeSpec.Type.UInt || rb == BuiltinTypeSpec.Type.UInt) {
4157                                 type = rc.BuiltinTypes.UInt;
4158
4159                                 if (IsSignedType (lb)) {
4160                                         expr = ConvertSignedConstant (left, type);
4161                                         if (expr == null)
4162                                                 type = rc.BuiltinTypes.Long;
4163                                 } else if (IsSignedType (rb)) {
4164                                         expr = ConvertSignedConstant (right, type);
4165                                         if (expr == null)
4166                                                 type = rc.BuiltinTypes.Long;
4167                                 }
4168                         } else {
4169                                 type = rc.BuiltinTypes.Int;
4170                         }
4171
4172                         if (ltype != type) {
4173                                 expr = PromoteExpression (rc, left, type);
4174                                 if (expr == null)
4175                                         return false;
4176
4177                                 left = expr;
4178                         }
4179
4180                         if (rtype != type) {
4181                                 expr = PromoteExpression (rc, right, type);
4182                                 if (expr == null)
4183                                         return false;
4184
4185                                 right = expr;
4186                         }
4187
4188                         return true;
4189                 }
4190
4191                 static bool IsSignedType (BuiltinTypeSpec.Type type)
4192                 {
4193                         switch (type) {
4194                         case BuiltinTypeSpec.Type.Int:
4195                         case BuiltinTypeSpec.Type.Short:
4196                         case BuiltinTypeSpec.Type.SByte:
4197                         case BuiltinTypeSpec.Type.Long:
4198                                 return true;
4199                         default:
4200                                 return false;
4201                         }
4202                 }
4203
4204                 static Expression ConvertSignedConstant (Expression expr, TypeSpec type)
4205                 {
4206                         var c = expr as Constant;
4207                         if (c == null)
4208                                 return null;
4209
4210                         return c.ConvertImplicitly (type);
4211                 }
4212
4213                 static Expression PromoteExpression (ResolveContext rc, Expression expr, TypeSpec type)
4214                 {
4215                         if (expr.Type.IsNullableType) {
4216                                 return Convert.ImplicitConversionStandard (rc, expr,
4217                                         rc.Module.PredefinedTypes.Nullable.TypeSpec.MakeGenericType (rc, new[] { type }), expr.Location);
4218                         }
4219
4220                         var c = expr as Constant;
4221                         if (c != null)
4222                                 return c.ConvertImplicitly (type);
4223
4224                         return Convert.ImplicitNumericConversion (expr, type);
4225                 }
4226
4227                 protected override Expression DoResolve (ResolveContext ec)
4228                 {
4229                         if (left == null)
4230                                 return null;
4231
4232                         if ((oper == Operator.Subtraction) && (left is ParenthesizedExpression)) {
4233                                 left = ((ParenthesizedExpression) left).Expr;
4234                                 left = left.Resolve (ec, ResolveFlags.VariableOrValue | ResolveFlags.Type);
4235                                 if (left == null)
4236                                         return null;
4237
4238                                 if (left.eclass == ExprClass.Type) {
4239                                         ec.Report.Error (75, loc, "To cast a negative value, you must enclose the value in parentheses");
4240                                         return null;
4241                                 }
4242                         } else
4243                                 left = left.Resolve (ec);
4244
4245                         if (left == null)
4246                                 return null;
4247
4248                         right = right.Resolve (ec);
4249                         if (right == null)
4250                                 return null;
4251
4252                         Constant lc = left as Constant;
4253                         Constant rc = right as Constant;
4254
4255                         // The conversion rules are ignored in enum context but why
4256                         if (!ec.HasSet (ResolveContext.Options.EnumScope) && lc != null && rc != null && (left.Type.IsEnum || right.Type.IsEnum)) {
4257                                 lc = EnumLiftUp (ec, lc, rc);
4258                                 if (lc != null)
4259                                         rc = EnumLiftUp (ec, rc, lc);
4260                         }
4261
4262                         if (rc != null && lc != null) {
4263                                 int prev_e = ec.Report.Errors;
4264                                 Expression e = ConstantFold.BinaryFold (ec, oper, lc, rc, loc);
4265                                 if (e != null || ec.Report.Errors != prev_e)
4266                                         return e;
4267                         }
4268
4269                         // Comparison warnings
4270                         if ((oper & Operator.ComparisonMask) != 0) {
4271                                 if (left.Equals (right)) {
4272                                         ec.Report.Warning (1718, 3, loc, "A comparison made to same variable. Did you mean to compare something else?");
4273                                 }
4274                                 CheckOutOfRangeComparison (ec, lc, right.Type);
4275                                 CheckOutOfRangeComparison (ec, rc, left.Type);
4276                         }
4277
4278                         if (left.Type.BuiltinType == BuiltinTypeSpec.Type.Dynamic || right.Type.BuiltinType == BuiltinTypeSpec.Type.Dynamic)
4279                                 return DoResolveDynamic (ec);
4280
4281                         return DoResolveCore (ec, left, right);
4282                 }
4283
4284                 Expression DoResolveDynamic (ResolveContext rc)
4285                 {
4286                         var lt = left.Type;
4287                         var rt = right.Type;
4288                         if (lt.Kind == MemberKind.Void || lt == InternalType.MethodGroup || lt == InternalType.AnonymousMethod ||
4289                                 rt.Kind == MemberKind.Void || rt == InternalType.MethodGroup || rt == InternalType.AnonymousMethod) {
4290                                 Error_OperatorCannotBeApplied (rc, left, right);
4291                                 return null;
4292                         }
4293
4294                         Arguments args;
4295
4296                         //
4297                         // Special handling for logical boolean operators which require rhs not to be
4298                         // evaluated based on lhs value
4299                         //
4300                         if ((oper & Operator.LogicalMask) != 0) {
4301                                 Expression cond_left, cond_right, expr;
4302
4303                                 args = new Arguments (2);
4304
4305                                 if (lt.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
4306                                         LocalVariable temp = LocalVariable.CreateCompilerGenerated (lt, rc.CurrentBlock, loc);
4307
4308                                         var cond_args = new Arguments (1);
4309                                         cond_args.Add (new Argument (new SimpleAssign (temp.CreateReferenceExpression (rc, loc), left).Resolve (rc)));
4310
4311                                         //
4312                                         // dynamic && bool => IsFalse (temp = left) ? temp : temp && right;
4313                                         // dynamic || bool => IsTrue (temp = left) ? temp : temp || right;
4314                                         //
4315                                         left = temp.CreateReferenceExpression (rc, loc);
4316                                         if (oper == Operator.LogicalAnd) {
4317                                                 expr = DynamicUnaryConversion.CreateIsFalse (rc, cond_args, loc);
4318                                                 cond_left = left;
4319                                         } else {
4320                                                 expr = DynamicUnaryConversion.CreateIsTrue (rc, cond_args, loc);
4321                                                 cond_left = left;
4322                                         }
4323
4324                                         args.Add (new Argument (left));
4325                                         args.Add (new Argument (right));
4326                                         cond_right = new DynamicExpressionStatement (this, args, loc);
4327                                 } else {
4328                                         LocalVariable temp = LocalVariable.CreateCompilerGenerated (rc.BuiltinTypes.Bool, rc.CurrentBlock, loc);
4329
4330                                         if (!Convert.ImplicitConversionExists (rc, left, temp.Type) && (oper == Operator.LogicalAnd ? GetOperatorFalse (rc, left, loc) : GetOperatorTrue (rc, left, loc)) == null) {
4331                                                 rc.Report.Error (7083, left.Location,
4332                                                         "Expression must be implicitly convertible to Boolean or its type `{0}' must define operator `{1}'",
4333                                                         lt.GetSignatureForError (), oper == Operator.LogicalAnd ? "false" : "true");
4334                                                 return null;
4335                                         }
4336
4337                                         args.Add (new Argument (temp.CreateReferenceExpression (rc, loc).Resolve (rc)));
4338                                         args.Add (new Argument (right));
4339                                         right = new DynamicExpressionStatement (this, args, loc);
4340
4341                                         //
4342                                         // bool && dynamic => (temp = left) ? temp && right : temp;
4343                                         // bool || dynamic => (temp = left) ? temp : temp || right;
4344                                         //
4345                                         if (oper == Operator.LogicalAnd) {
4346                                                 cond_left = right;
4347                                                 cond_right = temp.CreateReferenceExpression (rc, loc);
4348                                         } else {
4349                                                 cond_left = temp.CreateReferenceExpression (rc, loc);
4350                                                 cond_right = right;
4351                                         }
4352
4353                                         expr = new BooleanExpression (new SimpleAssign (temp.CreateReferenceExpression (rc, loc), left));
4354                                 }
4355
4356                                 return new Conditional (expr, cond_left, cond_right, loc).Resolve (rc);
4357                         }
4358
4359                         args = new Arguments (2);
4360                         args.Add (new Argument (left));
4361                         args.Add (new Argument (right));
4362                         return new DynamicExpressionStatement (this, args, loc).Resolve (rc);
4363                 }
4364
4365                 Expression DoResolveCore (ResolveContext ec, Expression left_orig, Expression right_orig)
4366                 {
4367                         Expression expr = ResolveOperator (ec);
4368                         if (expr == null)
4369                                 Error_OperatorCannotBeApplied (ec, left_orig, right_orig);
4370
4371                         if (left == null || right == null)
4372                                 throw new InternalErrorException ("Invalid conversion");
4373
4374                         if (oper == Operator.BitwiseOr)
4375                                 CheckBitwiseOrOnSignExtended (ec);
4376
4377                         return expr;
4378                 }
4379
4380                 public override SLE.Expression MakeExpression (BuilderContext ctx)
4381                 {
4382                         return MakeExpression (ctx, left, right);
4383                 }
4384
4385                 public SLE.Expression MakeExpression (BuilderContext ctx, Expression left, Expression right)
4386                 {
4387                         var le = left.MakeExpression (ctx);
4388                         var re = right.MakeExpression (ctx);
4389                         bool is_checked = ctx.HasSet (BuilderContext.Options.CheckedScope);
4390
4391                         switch (oper) {
4392                         case Operator.Addition:
4393                                 return is_checked ? SLE.Expression.AddChecked (le, re) : SLE.Expression.Add (le, re);
4394                         case Operator.BitwiseAnd:
4395                                 return SLE.Expression.And (le, re);
4396                         case Operator.BitwiseOr:
4397                                 return SLE.Expression.Or (le, re);
4398                         case Operator.Division:
4399                                 return SLE.Expression.Divide (le, re);
4400                         case Operator.Equality:
4401                                 return SLE.Expression.Equal (le, re);
4402                         case Operator.ExclusiveOr:
4403                                 return SLE.Expression.ExclusiveOr (le, re);
4404                         case Operator.GreaterThan:
4405                                 return SLE.Expression.GreaterThan (le, re);
4406                         case Operator.GreaterThanOrEqual:
4407                                 return SLE.Expression.GreaterThanOrEqual (le, re);
4408                         case Operator.Inequality:
4409                                 return SLE.Expression.NotEqual (le, re);
4410                         case Operator.LeftShift:
4411                                 return SLE.Expression.LeftShift (le, re);
4412                         case Operator.LessThan:
4413                                 return SLE.Expression.LessThan (le, re);
4414                         case Operator.LessThanOrEqual:
4415                                 return SLE.Expression.LessThanOrEqual (le, re);
4416                         case Operator.LogicalAnd:
4417                                 return SLE.Expression.AndAlso (le, re);
4418                         case Operator.LogicalOr:
4419                                 return SLE.Expression.OrElse (le, re);
4420                         case Operator.Modulus:
4421                                 return SLE.Expression.Modulo (le, re);
4422                         case Operator.Multiply:
4423                                 return is_checked ? SLE.Expression.MultiplyChecked (le, re) : SLE.Expression.Multiply (le, re);
4424                         case Operator.RightShift:
4425                                 return SLE.Expression.RightShift (le, re);
4426                         case Operator.Subtraction:
4427                                 return is_checked ? SLE.Expression.SubtractChecked (le, re) : SLE.Expression.Subtract (le, re);
4428                         default:
4429                                 throw new NotImplementedException (oper.ToString ());
4430                         }
4431                 }
4432
4433                 //
4434                 // D operator + (D x, D y)
4435                 // D operator - (D x, D y)
4436                 //
4437                 Expression ResolveOperatorDelegate (ResolveContext ec, TypeSpec l, TypeSpec r)
4438                 {
4439                         if (l != r && !TypeSpecComparer.Variant.IsEqual (r, l)) {
4440                                 Expression tmp;
4441                                 if (right.eclass == ExprClass.MethodGroup || r == InternalType.AnonymousMethod || r == InternalType.NullLiteral) {
4442                                         tmp = Convert.ImplicitConversionRequired (ec, right, l, loc);
4443                                         if (tmp == null)
4444                                                 return null;
4445                                         right = tmp;
4446                                         r = right.Type;
4447                                 } else if (left.eclass == ExprClass.MethodGroup || (l == InternalType.AnonymousMethod || l == InternalType.NullLiteral)) {
4448                                         tmp = Convert.ImplicitConversionRequired (ec, left, r, loc);
4449                                         if (tmp == null)
4450                                                 return null;
4451                                         left = tmp;
4452                                         l = left.Type;
4453                                 } else {
4454                                         return null;
4455                                 }
4456                         }
4457
4458                         MethodSpec method = null;
4459                         Arguments args = new Arguments (2);
4460                         args.Add (new Argument (left));
4461                         args.Add (new Argument (right));
4462
4463                         if (oper == Operator.Addition) {
4464                                 method = ec.Module.PredefinedMembers.DelegateCombine.Resolve (loc);
4465                         } else if (oper == Operator.Subtraction) {
4466                                 method = ec.Module.PredefinedMembers.DelegateRemove.Resolve (loc);
4467                         }
4468
4469                         if (method == null)
4470                                 return new EmptyExpression (ec.BuiltinTypes.Decimal);
4471
4472                         Expression expr = new UserOperatorCall (method, args, CreateExpressionTree, loc);
4473                         return new ClassCast (expr, l);
4474                 }
4475
4476                 //
4477                 // Resolves enumeration operators where only single predefined overload exists, handles lifted versions too
4478                 //
4479                 Expression ResolveSingleEnumOperators (ResolveContext rc, bool lenum, bool renum, TypeSpec ltype, TypeSpec rtype)
4480                 {
4481                         //
4482                         // bool operator == (E x, E y);
4483                         // bool operator != (E x, E y);
4484                         // bool operator < (E x, E y);
4485                         // bool operator > (E x, E y);
4486                         // bool operator <= (E x, E y);
4487                         // bool operator >= (E x, E y);
4488                         //
4489                         // E operator & (E x, E y);
4490                         // E operator | (E x, E y);
4491                         // E operator ^ (E x, E y);
4492                         //
4493                         Expression expr;
4494                         if ((oper & Operator.ComparisonMask) != 0) {
4495                                 type = rc.BuiltinTypes.Bool;
4496                         } else {
4497                                 if (lenum)
4498                                         type = ltype;
4499                                 else if (renum)
4500                                         type = rtype;
4501                                 else if (ltype.IsNullableType && Nullable.NullableInfo.GetUnderlyingType (ltype).IsEnum)
4502                                         type = ltype;
4503                                 else
4504                                         type = rtype;
4505                         }
4506
4507                         if (ltype == rtype) {
4508                                 if (lenum || renum)
4509                                         return this;
4510
4511                                 var lifted = new Nullable.LiftedBinaryOperator (this);
4512                                 lifted.Left = left;
4513                                 lifted.Right = right;
4514                                 return lifted.Resolve (rc);
4515                         }
4516
4517                         if (renum && !ltype.IsNullableType) {
4518                                 expr = Convert.ImplicitConversion (rc, left, rtype, loc);
4519                                 if (expr != null) {
4520                                         left = expr;
4521                                         return this;
4522                                 }
4523                         } else if (lenum && !rtype.IsNullableType) {
4524                                 expr = Convert.ImplicitConversion (rc, right, ltype, loc);
4525                                 if (expr != null) {
4526                                         right = expr;
4527                                         return this;
4528                                 }
4529                         }
4530
4531                         //
4532                         // Now try lifted version of predefined operator
4533                         //
4534                         var nullable_type = rc.Module.PredefinedTypes.Nullable.TypeSpec;
4535                         if (nullable_type != null) {
4536                                 if (renum && !ltype.IsNullableType) {
4537                                         var lifted_type = nullable_type.MakeGenericType (rc.Module, new[] { rtype });
4538
4539                                         expr = Convert.ImplicitConversion (rc, left, lifted_type, loc);
4540                                         if (expr != null) {
4541                                                 left = expr;
4542                                                 right = Convert.ImplicitConversion (rc, right, lifted_type, loc);
4543                                         }
4544
4545                                         if ((oper & Operator.BitwiseMask) != 0)
4546                                                 type = lifted_type;
4547
4548                                         if (left.IsNull) {
4549                                                 if ((oper & Operator.BitwiseMask) != 0)
4550                                                         return Nullable.LiftedNull.CreateFromExpression (rc, this);
4551
4552                                                 return CreateLiftedValueTypeResult (rc, rtype);
4553                                         }
4554
4555                                         if (expr != null) {
4556                                                 var lifted = new Nullable.LiftedBinaryOperator (this);
4557                                                 lifted.Left = expr;
4558                                                 lifted.Right = right;
4559                                                 return lifted.Resolve (rc);
4560                                         }
4561                                 } else if (lenum && !rtype.IsNullableType) {
4562                                         var lifted_type = nullable_type.MakeGenericType (rc.Module, new[] { ltype });
4563
4564                                         expr = Convert.ImplicitConversion (rc, right, lifted_type, loc);
4565                                         if (expr != null) {
4566                                                 right = expr;
4567                                                 left = Convert.ImplicitConversion (rc, left, lifted_type, loc);
4568                                         }
4569
4570                                         if ((oper & Operator.BitwiseMask) != 0)
4571                                                 type = lifted_type;
4572
4573                                         if (right.IsNull) {
4574                                                 if ((oper & Operator.BitwiseMask) != 0)
4575                                                         return Nullable.LiftedNull.CreateFromExpression (rc, this);
4576
4577                                                 return CreateLiftedValueTypeResult (rc, ltype);
4578                                         }
4579
4580                                         if (expr != null) {
4581                                                 var lifted = new Nullable.LiftedBinaryOperator (this);
4582                                                 lifted.Left = left;
4583                                                 lifted.Right = expr;
4584                                                 return lifted.Resolve (rc);
4585                                         }
4586                                 } else if (rtype.IsNullableType && Nullable.NullableInfo.GetUnderlyingType (rtype).IsEnum) {
4587                                         Nullable.Unwrap unwrap = null;
4588                                         if (left.IsNull || right.IsNull) {
4589                                                 if (rc.HasSet (ResolveContext.Options.ExpressionTreeConversion))
4590                                                         left = Convert.ImplicitConversion (rc, left, rtype, left.Location);
4591
4592                                                 if ((oper & Operator.RelationalMask) != 0)
4593                                                         return CreateLiftedValueTypeResult (rc, rtype);
4594
4595                                                 if ((oper & Operator.BitwiseMask) != 0)
4596                                                         return Nullable.LiftedNull.CreateFromExpression (rc, this);
4597
4598                                                 if (right.IsNull)
4599                                                         return CreateLiftedValueTypeResult (rc, left.Type);
4600
4601                                                 // Equality operators are valid between E? and null
4602                                                 expr = left;
4603                                                 unwrap = new Nullable.Unwrap (right);
4604                                         } else {
4605                                                 expr = Convert.ImplicitConversion (rc, left, Nullable.NullableInfo.GetUnderlyingType (rtype), loc);
4606                                                 if (expr == null)
4607                                                         return null;
4608
4609                                                 if ((oper & Operator.BitwiseMask) != 0)
4610                                                         type = rtype;
4611                                         }
4612
4613                                         if (expr != null) {
4614                                                 var lifted = new Nullable.LiftedBinaryOperator (this);
4615                                                 lifted.Left = expr;
4616                                                 lifted.Right = right;
4617                                                 lifted.UnwrapRight = unwrap;
4618                                                 return lifted.Resolve (rc);
4619                                         }
4620                                 } else if (ltype.IsNullableType && Nullable.NullableInfo.GetUnderlyingType (ltype).IsEnum) {
4621                                         Nullable.Unwrap unwrap = null;
4622                                         if (right.IsNull || left.IsNull) {
4623                                                 if (rc.HasSet (ResolveContext.Options.ExpressionTreeConversion))
4624                                                         right = Convert.ImplicitConversion (rc, right, ltype, right.Location);
4625
4626                                                 if ((oper & Operator.RelationalMask) != 0)
4627                                                         return CreateLiftedValueTypeResult (rc, ltype);
4628
4629                                                 if ((oper & Operator.BitwiseMask) != 0)
4630                                                         return Nullable.LiftedNull.CreateFromExpression (rc, this);
4631
4632                                                 if (left.IsNull)
4633                                                         return CreateLiftedValueTypeResult (rc, right.Type);
4634
4635                                                 // Equality operators are valid between E? and null
4636                                                 expr = right;
4637                                                 unwrap = new Nullable.Unwrap (left);
4638                                         } else {
4639                                                 expr = Convert.ImplicitConversion (rc, right, Nullable.NullableInfo.GetUnderlyingType (ltype), loc);
4640                                                 if (expr == null)
4641                                                         return null;
4642
4643                                                 if ((oper & Operator.BitwiseMask) != 0)
4644                                                         type = ltype;
4645                                         }
4646
4647                                         if (expr != null) {
4648                                                 var lifted = new Nullable.LiftedBinaryOperator (this);
4649                                                 lifted.Left = left;
4650                                                 lifted.UnwrapLeft = unwrap;
4651                                                 lifted.Right = expr;
4652                                                 return lifted.Resolve (rc);
4653                                         }
4654                                 }
4655                         }
4656
4657                         return null;
4658                 }
4659
4660                 static Expression ConvertEnumOperandToUnderlyingType (ResolveContext rc, Expression expr, bool liftType)
4661                 {
4662                         TypeSpec underlying_type;
4663                         if (expr.Type.IsNullableType) {
4664                                 var nt = Nullable.NullableInfo.GetUnderlyingType (expr.Type);
4665                                 if (nt.IsEnum)
4666                                         underlying_type = EnumSpec.GetUnderlyingType (nt);
4667                                 else
4668                                         underlying_type = nt;
4669                         } else if (expr.Type.IsEnum) {
4670                                 underlying_type = EnumSpec.GetUnderlyingType (expr.Type);
4671                         } else {
4672                                 underlying_type = expr.Type;
4673                         }
4674
4675                         switch (underlying_type.BuiltinType) {
4676                         case BuiltinTypeSpec.Type.SByte:
4677                         case BuiltinTypeSpec.Type.Byte:
4678                         case BuiltinTypeSpec.Type.Short:
4679                         case BuiltinTypeSpec.Type.UShort:
4680                                 underlying_type = rc.BuiltinTypes.Int;
4681                                 break;
4682                         }
4683
4684                         if (expr.Type.IsNullableType || liftType)
4685                                 underlying_type = rc.Module.PredefinedTypes.Nullable.TypeSpec.MakeGenericType (rc.Module, new[] { underlying_type });
4686
4687                         if (expr.Type == underlying_type)
4688                                 return expr;
4689
4690                         return EmptyCast.Create (expr, underlying_type);
4691                 }
4692
4693                 Expression ResolveEnumOperators (ResolveContext rc, bool lenum, bool renum, TypeSpec ltype, TypeSpec rtype)
4694                 {
4695                         //
4696                         // U operator - (E e, E f)
4697                         // E operator - (E e, U x)  // Internal decomposition operator
4698                         // E operator - (U x, E e)      // Internal decomposition operator
4699                         //
4700                         // E operator + (E e, U x)
4701                         // E operator + (U x, E e)
4702                         //
4703
4704                         TypeSpec enum_type;
4705
4706                         if (lenum)
4707                                 enum_type = ltype;
4708                         else if (renum)
4709                                 enum_type = rtype;
4710                         else if (ltype.IsNullableType && Nullable.NullableInfo.GetUnderlyingType (ltype).IsEnum)
4711                                 enum_type = ltype;
4712                         else
4713                                 enum_type = rtype;
4714
4715                         Expression expr;
4716                         if (!enum_type.IsNullableType) {
4717                                 expr = ResolveOperatorPredefined (rc, rc.Module.GetPredefinedEnumAritmeticOperators (enum_type, false), false);
4718                                 if (expr != null) {
4719                                         if (oper == Operator.Subtraction)
4720                                                 expr = ConvertEnumSubtractionResult (rc, expr);
4721                                         else
4722                                                 expr = ConvertEnumAdditionalResult (expr, enum_type);
4723
4724                                         enum_conversion = GetEnumResultCast (expr.Type);
4725
4726                                         return expr;
4727                                 }
4728
4729                                 var nullable = rc.Module.PredefinedTypes.Nullable;
4730
4731                                 //
4732                                 // Don't try nullable version when nullable type is undefined
4733                                 //
4734                                 if (!nullable.IsDefined)
4735                                         return null;
4736
4737                                 enum_type = nullable.TypeSpec.MakeGenericType (rc.Module, new[] { enum_type });
4738                         }
4739
4740                         expr = ResolveOperatorPredefined (rc, rc.Module.GetPredefinedEnumAritmeticOperators (enum_type, true), false);
4741                         if (expr != null) {
4742                                 if (oper == Operator.Subtraction)
4743                                         expr = ConvertEnumSubtractionResult (rc, expr);
4744                                 else
4745                                         expr = ConvertEnumAdditionalResult (expr, enum_type);
4746
4747                                 enum_conversion = GetEnumResultCast (expr.Type);
4748                         }
4749
4750                         return expr;
4751                 }
4752
4753                 static Expression ConvertEnumAdditionalResult (Expression expr, TypeSpec enumType)
4754                 {
4755                         return EmptyCast.Create (expr, enumType);
4756                 }
4757
4758                 Expression ConvertEnumSubtractionResult (ResolveContext rc, Expression expr)
4759                 {
4760                         //
4761                         // Enumeration subtraction has different result type based on
4762                         // best overload
4763                         //
4764                         TypeSpec result_type;
4765                         if (left.Type == right.Type) {
4766                                 var c = right as EnumConstant;
4767                                 if (c != null && c.IsZeroInteger && !right.Type.IsEnum) {
4768                                         //
4769                                         // LAMESPEC: This is quite unexpected for expression E - 0 the return type is
4770                                         // E which is not what expressions E - 1 or 0 - E return
4771                                         //
4772                                         result_type = left.Type;
4773                                 } else {
4774                                         result_type = left.Type.IsNullableType ?
4775                                                 Nullable.NullableInfo.GetEnumUnderlyingType (rc.Module, left.Type) :
4776                                                 EnumSpec.GetUnderlyingType (left.Type);
4777                                 }
4778                         } else {
4779                                 if (IsEnumOrNullableEnum (left.Type)) {
4780                                         result_type = left.Type;
4781                                 } else {
4782                                         result_type = right.Type;
4783                                 }
4784
4785                                 if (expr is Nullable.LiftedBinaryOperator && !result_type.IsNullableType)
4786                                         result_type = rc.Module.PredefinedTypes.Nullable.TypeSpec.MakeGenericType (rc.Module, new[] { result_type });
4787                         }
4788
4789                         return EmptyCast.Create (expr, result_type);
4790                 }
4791
4792                 public static ConvCast.Mode GetEnumResultCast (TypeSpec type)
4793                 {
4794                         if (type.IsNullableType)
4795                                 type = Nullable.NullableInfo.GetUnderlyingType (type);
4796
4797                         if (type.IsEnum)
4798                                 type = EnumSpec.GetUnderlyingType (type);
4799
4800                         switch (type.BuiltinType) {
4801                         case BuiltinTypeSpec.Type.SByte:
4802                                 return ConvCast.Mode.I4_I1;
4803                         case BuiltinTypeSpec.Type.Byte:
4804                                 return ConvCast.Mode.I4_U1;
4805                         case BuiltinTypeSpec.Type.Short:
4806                                 return ConvCast.Mode.I4_I2;
4807                         case BuiltinTypeSpec.Type.UShort:
4808                                 return ConvCast.Mode.I4_U2;
4809                         }
4810
4811                         return 0;
4812                 }
4813
4814                 //
4815                 // Equality operators rules
4816                 //
4817                 Expression ResolveEquality (ResolveContext ec, TypeSpec l, TypeSpec r, bool primitives_only)
4818                 {
4819                         Expression result;
4820                         type = ec.BuiltinTypes.Bool;
4821                         bool no_arg_conv = false;
4822
4823                         if (!primitives_only) {
4824
4825                                 //
4826                                 // a, Both operands are reference-type values or the value null
4827                                 // b, One operand is a value of type T where T is a type-parameter and
4828                                 // the other operand is the value null. Furthermore T does not have the
4829                                 // value type constraint
4830                                 //
4831                                 // LAMESPEC: Very confusing details in the specification, basically any
4832                                 // reference like type-parameter is allowed
4833                                 //
4834                                 var tparam_l = l as TypeParameterSpec;
4835                                 var tparam_r = r as TypeParameterSpec;
4836                                 if (tparam_l != null) {
4837                                         if (right is NullLiteral) {
4838                                                 if (tparam_l.GetEffectiveBase ().BuiltinType == BuiltinTypeSpec.Type.ValueType)
4839                                                         return null;
4840
4841                                                 left = new BoxedCast (left, ec.BuiltinTypes.Object);
4842                                                 return this;
4843                                         }
4844
4845                                         if (!tparam_l.IsReferenceType)
4846                                                 return null;
4847
4848                                         l = tparam_l.GetEffectiveBase ();
4849                                         left = new BoxedCast (left, l);
4850                                 } else if (left is NullLiteral && tparam_r == null) {
4851                                         if (TypeSpec.IsReferenceType (r))
4852                                                 return this;
4853
4854                                         if (r.Kind == MemberKind.InternalCompilerType)
4855                                                 return null;
4856                                 }
4857
4858                                 if (tparam_r != null) {
4859                                         if (left is NullLiteral) {
4860                                                 if (tparam_r.GetEffectiveBase ().BuiltinType == BuiltinTypeSpec.Type.ValueType)
4861                                                         return null;
4862
4863                                                 right = new BoxedCast (right, ec.BuiltinTypes.Object);
4864                                                 return this;
4865                                         }
4866
4867                                         if (!tparam_r.IsReferenceType)
4868                                                 return null;
4869
4870                                         r = tparam_r.GetEffectiveBase ();
4871                                         right = new BoxedCast (right, r);
4872                                 } else if (right is NullLiteral) {
4873                                         if (TypeSpec.IsReferenceType (l))
4874                                                 return this;
4875
4876                                         if (l.Kind == MemberKind.InternalCompilerType)
4877                                                 return null;
4878                                 }
4879
4880                                 //
4881                                 // LAMESPEC: method groups can be compared when they convert to other side delegate
4882                                 //
4883                                 if (l.IsDelegate) {
4884                                         if (right.eclass == ExprClass.MethodGroup) {
4885                                                 result = Convert.ImplicitConversion (ec, right, l, loc);
4886                                                 if (result == null)
4887                                                         return null;
4888
4889                                                 right = result;
4890                                                 r = l;
4891                                         } else if (r.IsDelegate && l != r) {
4892                                                 return null;
4893                                         }
4894                                 } else if (left.eclass == ExprClass.MethodGroup && r.IsDelegate) {
4895                                         result = Convert.ImplicitConversionRequired (ec, left, r, loc);
4896                                         if (result == null)
4897                                                 return null;
4898
4899                                         left = result;
4900                                         l = r;
4901                                 } else {
4902                                         no_arg_conv = l == r && !l.IsStruct;
4903                                 }
4904                         }
4905
4906                         //
4907                         // bool operator != (string a, string b)
4908                         // bool operator == (string a, string b)
4909                         //
4910                         // bool operator != (Delegate a, Delegate b)
4911                         // bool operator == (Delegate a, Delegate b)
4912                         //
4913                         // bool operator != (bool a, bool b)
4914                         // bool operator == (bool a, bool b)
4915                         //
4916                         // LAMESPEC: Reference equality comparison can apply to value/reference types when
4917                         // they implement an implicit conversion to any of types above. This does
4918                         // not apply when both operands are of same reference type
4919                         //
4920                         if (r.BuiltinType != BuiltinTypeSpec.Type.Object && l.BuiltinType != BuiltinTypeSpec.Type.Object) {
4921                                 result = ResolveOperatorPredefined (ec, ec.BuiltinTypes.OperatorsBinaryEquality, no_arg_conv);
4922                                 if (result != null)
4923                                         return result;
4924
4925                                 //
4926                                 // Now try lifted version of predefined operators
4927                                 //
4928                                 if (no_arg_conv && !l.IsNullableType) {
4929                                         //
4930                                         // Optimizes cases which won't match
4931                                         //
4932                                 } else {
4933                                         result = ResolveOperatorPredefined (ec, ec.Module.OperatorsBinaryEqualityLifted, no_arg_conv);
4934                                         if (result != null)
4935                                                 return result;
4936                                 }
4937
4938                                 //
4939                                 // The == and != operators permit one operand to be a value of a nullable
4940                                 // type and the other to be the null literal, even if no predefined or user-defined
4941                                 // operator (in unlifted or lifted form) exists for the operation.
4942                                 //
4943                                 if ((l.IsNullableType && right.IsNull) || (r.IsNullableType && left.IsNull)) {
4944                                         var lifted = new Nullable.LiftedBinaryOperator (this);
4945                                         lifted.Left = left;
4946                                         lifted.Right = right;
4947                                         return lifted.Resolve (ec);
4948                                 }
4949                         }
4950
4951                         //
4952                         // bool operator != (object a, object b)
4953                         // bool operator == (object a, object b)
4954                         //
4955                         // An explicit reference conversion exists from the
4956                         // type of either operand to the type of the other operand.
4957                         //
4958
4959                         // Optimize common path
4960                         if (l == r) {
4961                                 return l.Kind == MemberKind.InternalCompilerType || l.Kind == MemberKind.Struct ? null : this;
4962                         }
4963
4964                         if (!Convert.ExplicitReferenceConversionExists (l, r) &&
4965                                 !Convert.ExplicitReferenceConversionExists (r, l))
4966                                 return null;
4967
4968                         // Reject allowed explicit conversions like int->object
4969                         if (!TypeSpec.IsReferenceType (l) || !TypeSpec.IsReferenceType (r))
4970                                 return null;
4971
4972                         if (l.BuiltinType == BuiltinTypeSpec.Type.String || l.BuiltinType == BuiltinTypeSpec.Type.Delegate || l.IsDelegate || MemberCache.GetUserOperator (l, CSharp.Operator.OpType.Equality, false) != null)
4973                                 ec.Report.Warning (253, 2, loc,
4974                                         "Possible unintended reference comparison. Consider casting the right side expression to type `{0}' to get value comparison",
4975                                         l.GetSignatureForError ());
4976
4977                         if (r.BuiltinType == BuiltinTypeSpec.Type.String || r.BuiltinType == BuiltinTypeSpec.Type.Delegate || r.IsDelegate || MemberCache.GetUserOperator (r, CSharp.Operator.OpType.Equality, false) != null)
4978                                 ec.Report.Warning (252, 2, loc,
4979                                         "Possible unintended reference comparison. Consider casting the left side expression to type `{0}' to get value comparison",
4980                                         r.GetSignatureForError ());
4981
4982                         return this;
4983                 }
4984
4985
4986                 Expression ResolveOperatorPointer (ResolveContext ec, TypeSpec l, TypeSpec r)
4987                 {
4988                         //
4989                         // bool operator == (void* x, void* y);
4990                         // bool operator != (void* x, void* y);
4991                         // bool operator < (void* x, void* y);
4992                         // bool operator > (void* x, void* y);
4993                         // bool operator <= (void* x, void* y);
4994                         // bool operator >= (void* x, void* y);
4995                         //
4996                         if ((oper & Operator.ComparisonMask) != 0) {
4997                                 Expression temp;
4998                                 if (!l.IsPointer) {
4999                                         temp = Convert.ImplicitConversion (ec, left, r, left.Location);
5000                                         if (temp == null)
5001                                                 return null;
5002                                         left = temp;
5003                                 }
5004
5005                                 if (!r.IsPointer) {
5006                                         temp = Convert.ImplicitConversion (ec, right, l, right.Location);
5007                                         if (temp == null)
5008                                                 return null;
5009                                         right = temp;
5010                                 }
5011
5012                                 type = ec.BuiltinTypes.Bool;
5013                                 return this;
5014                         }
5015
5016                         return ResolveOperatorPredefined (ec, ec.BuiltinTypes.OperatorsBinaryUnsafe, false);
5017                 }
5018
5019                 //
5020                 // Build-in operators method overloading
5021                 //
5022                 Expression ResolveOperatorPredefined (ResolveContext ec, PredefinedOperator [] operators, bool primitives_only)
5023                 {
5024                         PredefinedOperator best_operator = null;
5025                         TypeSpec l = left.Type;
5026                         TypeSpec r = right.Type;
5027                         Operator oper_mask = oper & ~Operator.ValuesOnlyMask;
5028
5029                         foreach (PredefinedOperator po in operators) {
5030                                 if ((po.OperatorsMask & oper_mask) == 0)
5031                                         continue;
5032
5033                                 if (primitives_only) {
5034                                         if (!po.IsPrimitiveApplicable (l, r))
5035                                                 continue;
5036                                 } else {
5037                                         if (!po.IsApplicable (ec, left, right))
5038                                                 continue;
5039                                 }
5040
5041                                 if (best_operator == null) {
5042                                         best_operator = po;
5043                                         if (primitives_only)
5044                                                 break;
5045
5046                                         continue;
5047                                 }
5048
5049                                 best_operator = po.ResolveBetterOperator (ec, best_operator);
5050
5051                                 if (best_operator == null) {
5052                                         ec.Report.Error (34, loc, "Operator `{0}' is ambiguous on operands of type `{1}' and `{2}'",
5053                                                 OperName (oper), l.GetSignatureForError (), r.GetSignatureForError ());
5054
5055                                         best_operator = po;
5056                                         break;
5057                                 }
5058                         }
5059
5060                         if (best_operator == null)
5061                                 return null;
5062
5063                         return best_operator.ConvertResult (ec, this);
5064                 }
5065
5066                 //
5067                 // Optimize & constant expressions with 0 value
5068                 //
5069                 Expression OptimizeAndOperation (Expression expr)
5070                 {
5071                         Constant rc = right as Constant;
5072                         Constant lc = left as Constant;
5073                         if ((lc != null && lc.IsDefaultValue) || (rc != null && rc.IsDefaultValue)) {
5074                                 //
5075                                 // The result is a constant with side-effect
5076                                 //
5077                                 Constant side_effect = rc == null ?
5078                                         new SideEffectConstant (lc, right, loc) :
5079                                         new SideEffectConstant (rc, left, loc);
5080
5081                                 return ReducedExpression.Create (side_effect, expr);
5082                         }
5083
5084                         return expr;
5085                 }
5086
5087                 //
5088                 // Value types can be compared with the null literal because of the lifting
5089                 // language rules. However the result is always true or false.
5090                 //
5091                 public Expression CreateLiftedValueTypeResult (ResolveContext rc, TypeSpec valueType)
5092                 {
5093                         if (rc.HasSet (ResolveContext.Options.ExpressionTreeConversion)) {
5094                                 type = rc.BuiltinTypes.Bool;
5095                                 return this;
5096                         }
5097
5098                         // FIXME: Handle side effect constants
5099                         Constant c = new BoolConstant (rc.BuiltinTypes, Oper == Operator.Inequality, loc);
5100
5101                         if ((Oper & Operator.EqualityMask) != 0) {
5102                                 rc.Report.Warning (472, 2, loc, "The result of comparing value type `{0}' with null is always `{1}'",
5103                                         valueType.GetSignatureForError (), c.GetValueAsLiteral ());
5104                         } else {
5105                                 rc.Report.Warning (464, 2, loc, "The result of comparing type `{0}' with null is always `{1}'",
5106                                         valueType.GetSignatureForError (), c.GetValueAsLiteral ());
5107                         }
5108
5109                         return c;
5110                 }
5111
5112                 //
5113                 // Performs user-operator overloading
5114                 //
5115                 Expression ResolveUserOperator (ResolveContext rc, Expression left, Expression right)
5116                 {
5117                         Expression oper_expr;
5118
5119                         var op = ConvertBinaryToUserOperator (oper);
5120                         var l = left.Type;
5121                         if (l.IsNullableType)
5122                                 l = Nullable.NullableInfo.GetUnderlyingType (l);
5123                         var r = right.Type;
5124                         if (r.IsNullableType)
5125                                 r = Nullable.NullableInfo.GetUnderlyingType (r);
5126
5127                         IList<MemberSpec> left_operators = MemberCache.GetUserOperator (l, op, false);
5128                         IList<MemberSpec> right_operators = null;
5129
5130                         if (l != r) {
5131                                 right_operators = MemberCache.GetUserOperator (r, op, false);
5132                                 if (right_operators == null && left_operators == null)
5133                                         return null;
5134                         } else if (left_operators == null) {
5135                                 return null;
5136                         }
5137
5138                         Arguments args = new Arguments (2);
5139                         Argument larg = new Argument (left);
5140                         args.Add (larg);
5141                         Argument rarg = new Argument (right);
5142                         args.Add (rarg);
5143
5144                         //
5145                         // User-defined operator implementations always take precedence
5146                         // over predefined operator implementations
5147                         //
5148                         if (left_operators != null && right_operators != null) {
5149                                 left_operators = CombineUserOperators (left_operators, right_operators);
5150                         } else if (right_operators != null) {
5151                                 left_operators = right_operators;
5152                         }
5153
5154                         const OverloadResolver.Restrictions restr = OverloadResolver.Restrictions.ProbingOnly |
5155                                 OverloadResolver.Restrictions.NoBaseMembers | OverloadResolver.Restrictions.BaseMembersIncluded;
5156
5157                         var res = new OverloadResolver (left_operators, restr, loc);
5158
5159                         var oper_method = res.ResolveOperator (rc, ref args);
5160                         if (oper_method == null) {
5161                                 //
5162                                 // Logical && and || cannot be lifted
5163                                 //
5164                                 if ((oper & Operator.LogicalMask) != 0)
5165                                         return null;
5166
5167                                 //
5168                                 // Apply lifted user operators only for liftable types. Implicit conversion
5169                                 // to nullable types is not allowed
5170                                 //
5171                                 if (!IsLiftedOperatorApplicable ())
5172                                         return null;
5173
5174                                 // TODO: Cache the result in module container
5175                                 var lifted_methods = CreateLiftedOperators (rc, left_operators);
5176                                 if (lifted_methods == null)
5177                                         return null;
5178
5179                                 res = new OverloadResolver (lifted_methods, restr | OverloadResolver.Restrictions.ProbingOnly, loc);
5180
5181                                 oper_method = res.ResolveOperator (rc, ref args);
5182                                 if (oper_method == null)
5183                                         return null;
5184
5185                                 MethodSpec best_original = null;
5186                                 foreach (MethodSpec ms in left_operators) {
5187                                         if (ms.MemberDefinition == oper_method.MemberDefinition) {
5188                                                 best_original = ms;
5189                                                 break;
5190                                         }
5191                                 }
5192
5193                                 if (rc.HasSet (ResolveContext.Options.ExpressionTreeConversion)) {
5194                                         //
5195                                         // Expression trees use lifted notation in this case
5196                                         //
5197                                         this.left = Convert.ImplicitConversion (rc, left, oper_method.Parameters.Types[0], left.Location);
5198                                         this.right = Convert.ImplicitConversion (rc, right, oper_method.Parameters.Types[1], left.Location);
5199                                 }
5200
5201                                 var ptypes = best_original.Parameters.Types;
5202
5203                                 if (left.IsNull || right.IsNull) {
5204                                         //
5205                                         // The lifted operator produces a null value if one or both operands are null
5206                                         //
5207                                         if ((oper & (Operator.ArithmeticMask | Operator.ShiftMask | Operator.BitwiseMask)) != 0) {
5208                                                 type = oper_method.ReturnType;
5209                                                 return Nullable.LiftedNull.CreateFromExpression (rc, this);
5210                                         }
5211
5212                                         //
5213                                         // The lifted operator produces the value false if one or both operands are null for
5214                                         // relational operators.
5215                                         //
5216                                         if ((oper & Operator.RelationalMask) != 0) {
5217                                                 //
5218                                                 // CSC BUG: This should be different warning, csc reports CS0458 with bool? which is wrong
5219                                                 // because return type is actually bool
5220                                                 //
5221                                                 return CreateLiftedValueTypeResult (rc, left.IsNull ? ptypes [1] : ptypes [0]);
5222                                         }
5223
5224                                         if ((oper & Operator.EqualityMask) != 0 && ((left.IsNull && !right.Type.IsNullableType) || !left.Type.IsNullableType)) {
5225                                                 return CreateLiftedValueTypeResult (rc, left.IsNull ? ptypes [1] : ptypes [0]);
5226                                         }
5227                                 }
5228
5229                                 type = oper_method.ReturnType;
5230                                 var lifted = new Nullable.LiftedBinaryOperator (this);
5231                                 lifted.UserOperator = best_original;
5232
5233                                 if (left.Type.IsNullableType && !ptypes[0].IsNullableType) {
5234                                         lifted.UnwrapLeft = new Nullable.Unwrap (left);
5235                                 }
5236
5237                                 if (right.Type.IsNullableType && !ptypes[1].IsNullableType) {
5238                                         lifted.UnwrapRight = new Nullable.Unwrap (right);
5239                                 }
5240
5241                                 lifted.Left = Convert.ImplicitConversion (rc, lifted.UnwrapLeft ?? left, ptypes[0], left.Location);
5242                                 lifted.Right = Convert.ImplicitConversion (rc, lifted.UnwrapRight ?? right, ptypes[1], right.Location);
5243
5244                                 return lifted.Resolve (rc);
5245                         }
5246
5247                         if ((oper & Operator.LogicalMask) != 0) {
5248                                 // TODO: CreateExpressionTree is allocated every time
5249                                 oper_expr = new ConditionalLogicalOperator (oper_method, args, CreateExpressionTree,
5250                                         oper == Operator.LogicalAnd, loc).Resolve (rc);
5251                         } else {
5252                                 oper_expr = new UserOperatorCall (oper_method, args, CreateExpressionTree, loc);
5253                         }
5254
5255                         this.left = larg.Expr;
5256                         this.right = rarg.Expr;
5257
5258                         return oper_expr;
5259                 }
5260
5261                 bool IsLiftedOperatorApplicable ()
5262                 {
5263                         if (left.Type.IsNullableType) {
5264                                 if ((oper & Operator.EqualityMask) != 0)
5265                                         return !right.IsNull;
5266
5267                                 return true;
5268                         }
5269
5270                         if (right.Type.IsNullableType) {
5271                                 if ((oper & Operator.EqualityMask) != 0)
5272                                         return !left.IsNull;
5273
5274                                 return true;
5275                         }
5276
5277                         if (TypeSpec.IsValueType (left.Type))
5278                                 return right.IsNull;
5279
5280                         if (TypeSpec.IsValueType (right.Type))
5281                                 return left.IsNull;
5282
5283                         return false;
5284                 }
5285
5286                 List<MemberSpec> CreateLiftedOperators (ResolveContext rc, IList<MemberSpec> operators)
5287                 {
5288                         var nullable_type = rc.Module.PredefinedTypes.Nullable.TypeSpec;
5289                         if (nullable_type == null)
5290                                 return null;
5291
5292                         //
5293                         // Lifted operators permit predefined and user-defined operators that operate
5294                         // on non-nullable value types to also be used with nullable forms of those types.
5295                         // Lifted operators are constructed from predefined and user-defined operators
5296                         // that meet certain requirements
5297                         //
5298                         List<MemberSpec> lifted = null;
5299                         foreach (MethodSpec oper in operators) {
5300                                 TypeSpec rt;
5301                                 if ((Oper & Operator.ComparisonMask) != 0) {
5302                                         //
5303                                         // Result type must be of type bool for lifted comparison operators
5304                                         //
5305                                         rt = oper.ReturnType;
5306                                         if (rt.BuiltinType != BuiltinTypeSpec.Type.Bool)
5307                                                 continue;
5308                                 } else {
5309                                         if (!TypeSpec.IsNonNullableValueType (oper.ReturnType))
5310                                                 continue;
5311
5312                                         rt = null;
5313                                 }
5314
5315                                 var ptypes = oper.Parameters.Types;
5316                                 if (!TypeSpec.IsNonNullableValueType (ptypes [0]) || !TypeSpec.IsNonNullableValueType (ptypes [1]))
5317                                         continue;
5318
5319                                 //
5320                                 // LAMESPEC: I am not sure why but for equality operators to be lifted
5321                                 // both types have to match
5322                                 //
5323                                 if ((Oper & Operator.EqualityMask) != 0 && ptypes [0] != ptypes [1])
5324                                         continue;
5325
5326                                 if (lifted == null)
5327                                         lifted = new List<MemberSpec> ();
5328
5329                                 //
5330                                 // The lifted form is constructed by adding a single ? modifier to each operand and
5331                                 // result type except for comparison operators where return type is bool
5332                                 //
5333                                 if (rt == null)
5334                                         rt = nullable_type.MakeGenericType (rc.Module, new[] { oper.ReturnType });
5335
5336                                 var parameters = ParametersCompiled.CreateFullyResolved (
5337                                         nullable_type.MakeGenericType (rc.Module, new [] { ptypes[0] }),
5338                                         nullable_type.MakeGenericType (rc.Module, new [] { ptypes[1] }));
5339
5340                                 var lifted_op = new MethodSpec (oper.Kind, oper.DeclaringType, oper.MemberDefinition,
5341                                         rt, parameters, oper.Modifiers);
5342
5343                                 lifted.Add (lifted_op);
5344                         }
5345
5346                         return lifted;
5347                 }
5348
5349                 //
5350                 // Merge two sets of user operators into one, they are mostly distinguish
5351                 // except when they share base type and it contains an operator
5352                 //
5353                 static IList<MemberSpec> CombineUserOperators (IList<MemberSpec> left, IList<MemberSpec> right)
5354                 {
5355                         var combined = new List<MemberSpec> (left.Count + right.Count);
5356                         combined.AddRange (left);
5357                         foreach (var r in right) {
5358                                 bool same = false;
5359                                 foreach (var l in left) {
5360                                         if (l.DeclaringType == r.DeclaringType) {
5361                                                 same = true;
5362                                                 break;
5363                                         }
5364                                 }
5365
5366                                 if (!same)
5367                                         combined.Add (r);
5368                         }
5369
5370                         return combined;
5371                 }
5372
5373                 void CheckOutOfRangeComparison (ResolveContext ec, Constant c, TypeSpec type)
5374                 {
5375                         if (c is IntegralConstant || c is CharConstant) {
5376                                 try {
5377                                         c.ConvertExplicitly (true, type);
5378                                 } catch (OverflowException) {
5379                                         ec.Report.Warning (652, 2, loc,
5380                                                 "A comparison between a constant and a variable is useless. The constant is out of the range of the variable type `{0}'",
5381                                                 type.GetSignatureForError ());
5382                                 }
5383                         }
5384                 }
5385
5386                 /// <remarks>
5387                 ///   EmitBranchable is called from Statement.EmitBoolExpression in the
5388                 ///   context of a conditional bool expression.  This function will return
5389                 ///   false if it is was possible to use EmitBranchable, or true if it was.
5390                 ///
5391                 ///   The expression's code is generated, and we will generate a branch to `target'
5392                 ///   if the resulting expression value is equal to isTrue
5393                 /// </remarks>
5394                 public override void EmitBranchable (EmitContext ec, Label target, bool on_true)
5395                 {
5396                         if (ec.HasSet (BuilderContext.Options.AsyncBody) && right.ContainsEmitWithAwait ()) {
5397                                 left = left.EmitToField (ec);
5398
5399                                 if ((oper & Operator.LogicalMask) == 0) {
5400                                         right = right.EmitToField (ec);
5401                                 }
5402                         }
5403
5404                         //
5405                         // This is more complicated than it looks, but its just to avoid
5406                         // duplicated tests: basically, we allow ==, !=, >, <, >= and <=
5407                         // but on top of that we want for == and != to use a special path
5408                         // if we are comparing against null
5409                         //
5410                         if ((oper & Operator.EqualityMask) != 0 && (left is Constant || right is Constant)) {
5411                                 bool my_on_true = oper == Operator.Inequality ? on_true : !on_true;
5412
5413                                 //
5414                                 // put the constant on the rhs, for simplicity
5415                                 //
5416                                 if (left is Constant) {
5417                                         Expression swap = right;
5418                                         right = left;
5419                                         left = swap;
5420                                 }
5421
5422                                 //
5423                                 // brtrue/brfalse works with native int only
5424                                 //
5425                                 if (((Constant) right).IsZeroInteger && right.Type.BuiltinType != BuiltinTypeSpec.Type.Long && right.Type.BuiltinType != BuiltinTypeSpec.Type.ULong) {
5426                                         left.EmitBranchable (ec, target, my_on_true);
5427                                         return;
5428                                 }
5429                                 if (right.Type.BuiltinType == BuiltinTypeSpec.Type.Bool) {
5430                                         // right is a boolean, and it's not 'false' => it is 'true'
5431                                         left.EmitBranchable (ec, target, !my_on_true);
5432                                         return;
5433                                 }
5434
5435                         } else if (oper == Operator.LogicalAnd) {
5436
5437                                 if (on_true) {
5438                                         Label tests_end = ec.DefineLabel ();
5439
5440                                         left.EmitBranchable (ec, tests_end, false);
5441                                         right.EmitBranchable (ec, target, true);
5442                                         ec.MarkLabel (tests_end);
5443                                 } else {
5444                                         //
5445                                         // This optimizes code like this
5446                                         // if (true && i > 4)
5447                                         //
5448                                         if (!(left is Constant))
5449                                                 left.EmitBranchable (ec, target, false);
5450
5451                                         if (!(right is Constant))
5452                                                 right.EmitBranchable (ec, target, false);
5453                                 }
5454
5455                                 return;
5456
5457                         } else if (oper == Operator.LogicalOr){
5458                                 if (on_true) {
5459                                         left.EmitBranchable (ec, target, true);
5460                                         right.EmitBranchable (ec, target, true);
5461
5462                                 } else {
5463                                         Label tests_end = ec.DefineLabel ();
5464                                         left.EmitBranchable (ec, tests_end, true);
5465                                         right.EmitBranchable (ec, target, false);
5466                                         ec.MarkLabel (tests_end);
5467                                 }
5468
5469                                 return;
5470
5471                         } else if ((oper & Operator.ComparisonMask) == 0) {
5472                                 base.EmitBranchable (ec, target, on_true);
5473                                 return;
5474                         }
5475
5476                         left.Emit (ec);
5477                         right.Emit (ec);
5478
5479                         TypeSpec t = left.Type;
5480                         bool is_float = IsFloat (t);
5481                         bool is_unsigned = is_float || IsUnsigned (t);
5482
5483                         switch (oper){
5484                         case Operator.Equality:
5485                                 if (on_true)
5486                                         ec.Emit (OpCodes.Beq, target);
5487                                 else
5488                                         ec.Emit (OpCodes.Bne_Un, target);
5489                                 break;
5490
5491                         case Operator.Inequality:
5492                                 if (on_true)
5493                                         ec.Emit (OpCodes.Bne_Un, target);
5494                                 else
5495                                         ec.Emit (OpCodes.Beq, target);
5496                                 break;
5497
5498                         case Operator.LessThan:
5499                                 if (on_true)
5500                                         if (is_unsigned && !is_float)
5501                                                 ec.Emit (OpCodes.Blt_Un, target);
5502                                         else
5503                                                 ec.Emit (OpCodes.Blt, target);
5504                                 else
5505                                         if (is_unsigned)
5506                                                 ec.Emit (OpCodes.Bge_Un, target);
5507                                         else
5508                                                 ec.Emit (OpCodes.Bge, target);
5509                                 break;
5510
5511                         case Operator.GreaterThan:
5512                                 if (on_true)
5513                                         if (is_unsigned && !is_float)
5514                                                 ec.Emit (OpCodes.Bgt_Un, target);
5515                                         else
5516                                                 ec.Emit (OpCodes.Bgt, target);
5517                                 else
5518                                         if (is_unsigned)
5519                                                 ec.Emit (OpCodes.Ble_Un, target);
5520                                         else
5521                                                 ec.Emit (OpCodes.Ble, target);
5522                                 break;
5523
5524                         case Operator.LessThanOrEqual:
5525                                 if (on_true)
5526                                         if (is_unsigned && !is_float)
5527                                                 ec.Emit (OpCodes.Ble_Un, target);
5528                                         else
5529                                                 ec.Emit (OpCodes.Ble, target);
5530                                 else
5531                                         if (is_unsigned)
5532                                                 ec.Emit (OpCodes.Bgt_Un, target);
5533                                         else
5534                                                 ec.Emit (OpCodes.Bgt, target);
5535                                 break;
5536
5537
5538                         case Operator.GreaterThanOrEqual:
5539                                 if (on_true)
5540                                         if (is_unsigned && !is_float)
5541                                                 ec.Emit (OpCodes.Bge_Un, target);
5542                                         else
5543                                                 ec.Emit (OpCodes.Bge, target);
5544                                 else
5545                                         if (is_unsigned)
5546                                                 ec.Emit (OpCodes.Blt_Un, target);
5547                                         else
5548                                                 ec.Emit (OpCodes.Blt, target);
5549                                 break;
5550                         default:
5551                                 throw new InternalErrorException (oper.ToString ());
5552                         }
5553                 }
5554
5555                 public override void Emit (EmitContext ec)
5556                 {
5557                         if (ec.HasSet (BuilderContext.Options.AsyncBody) && right.ContainsEmitWithAwait ()) {
5558                                 left = left.EmitToField (ec);
5559
5560                                 if ((oper & Operator.LogicalMask) == 0) {
5561                                         right = right.EmitToField (ec);
5562                                 }
5563                         }
5564
5565                         //
5566                         // Handle short-circuit operators differently
5567                         // than the rest
5568                         //
5569                         if ((oper & Operator.LogicalMask) != 0) {
5570                                 Label load_result = ec.DefineLabel ();
5571                                 Label end = ec.DefineLabel ();
5572
5573                                 bool is_or = oper == Operator.LogicalOr;
5574                                 left.EmitBranchable (ec, load_result, is_or);
5575                                 right.Emit (ec);
5576                                 ec.Emit (OpCodes.Br_S, end);
5577
5578                                 ec.MarkLabel (load_result);
5579                                 ec.EmitInt (is_or ? 1 : 0);
5580                                 ec.MarkLabel (end);
5581                                 return;
5582                         }
5583
5584                         //
5585                         // Optimize zero-based operations which cannot be optimized at expression level
5586                         //
5587                         if (oper == Operator.Subtraction) {
5588                                 var lc = left as IntegralConstant;
5589                                 if (lc != null && lc.IsDefaultValue) {
5590                                         right.Emit (ec);
5591                                         ec.Emit (OpCodes.Neg);
5592                                         return;
5593                                 }
5594                         }
5595
5596                         EmitOperator (ec, left, right);
5597                 }
5598
5599                 public void EmitOperator (EmitContext ec, Expression left, Expression right)
5600                 {
5601                         left.Emit (ec);
5602                         right.Emit (ec);
5603
5604                         EmitOperatorOpcode (ec, oper, left.Type, right);
5605
5606                         //
5607                         // Emit result enumerable conversion this way because it's quite complicated get it
5608                         // to resolved tree because expression tree cannot see it.
5609                         //
5610                         if (enum_conversion != 0)
5611                                 ConvCast.Emit (ec, enum_conversion);
5612                 }
5613
5614                 public override void EmitSideEffect (EmitContext ec)
5615                 {
5616                         if ((oper & Operator.LogicalMask) != 0 ||
5617                                 (ec.HasSet (EmitContext.Options.CheckedScope) && (oper == Operator.Multiply || oper == Operator.Addition || oper == Operator.Subtraction))) {
5618                                 base.EmitSideEffect (ec);
5619                         } else {
5620                                 left.EmitSideEffect (ec);
5621                                 right.EmitSideEffect (ec);
5622                         }
5623                 }
5624
5625                 public override Expression EmitToField (EmitContext ec)
5626                 {
5627                         if ((oper & Operator.LogicalMask) == 0) {
5628                                 var await_expr = left as Await;
5629                                 if (await_expr != null && right.IsSideEffectFree) {
5630                                         await_expr.Statement.EmitPrologue (ec);
5631                                         left = await_expr.Statement.GetResultExpression (ec);
5632                                         return this;
5633                                 }
5634
5635                                 await_expr = right as Await;
5636                                 if (await_expr != null && left.IsSideEffectFree) {
5637                                         await_expr.Statement.EmitPrologue (ec);
5638                                         right = await_expr.Statement.GetResultExpression (ec);
5639                                         return this;
5640                                 }
5641                         }
5642
5643                         return base.EmitToField (ec);
5644                 }
5645
5646                 protected override void CloneTo (CloneContext clonectx, Expression t)
5647                 {
5648                         Binary target = (Binary) t;
5649
5650                         target.left = left.Clone (clonectx);
5651                         target.right = right.Clone (clonectx);
5652                 }
5653
5654                 public Expression CreateCallSiteBinder (ResolveContext ec, Arguments args)
5655                 {
5656                         Arguments binder_args = new Arguments (4);
5657
5658                         MemberAccess sle = new MemberAccess (new MemberAccess (
5659                                 new QualifiedAliasMember (QualifiedAliasMember.GlobalAlias, "System", loc), "Linq", loc), "Expressions", loc);
5660
5661                         CSharpBinderFlags flags = 0;
5662                         if (ec.HasSet (ResolveContext.Options.CheckedScope))
5663                                 flags = CSharpBinderFlags.CheckedContext;
5664
5665                         if ((oper & Operator.LogicalMask) != 0)
5666                                 flags |= CSharpBinderFlags.BinaryOperationLogical;
5667
5668                         binder_args.Add (new Argument (new EnumConstant (new IntLiteral (ec.BuiltinTypes, (int) flags, loc), ec.Module.PredefinedTypes.BinderFlags.Resolve ())));
5669                         binder_args.Add (new Argument (new MemberAccess (new MemberAccess (sle, "ExpressionType", loc), GetOperatorExpressionTypeName (), loc)));
5670                         binder_args.Add (new Argument (new TypeOf (ec.CurrentType, loc)));
5671                         binder_args.Add (new Argument (new ImplicitlyTypedArrayCreation (args.CreateDynamicBinderArguments (ec), loc)));
5672
5673                         return new Invocation (new MemberAccess (new TypeExpression (ec.Module.PredefinedTypes.Binder.TypeSpec, loc), "BinaryOperation", loc), binder_args);
5674                 }
5675
5676                 public override Expression CreateExpressionTree (ResolveContext ec)
5677                 {
5678                         return CreateExpressionTree (ec, null);
5679                 }
5680
5681                 public Expression CreateExpressionTree (ResolveContext ec, Expression method)
5682                 {
5683                         string method_name;
5684                         bool lift_arg = false;
5685
5686                         switch (oper) {
5687                         case Operator.Addition:
5688                                 if (method == null && ec.HasSet (ResolveContext.Options.CheckedScope) && !IsFloat (type))
5689                                         method_name = "AddChecked";
5690                                 else
5691                                         method_name = "Add";
5692                                 break;
5693                         case Operator.BitwiseAnd:
5694                                 method_name = "And";
5695                                 break;
5696                         case Operator.BitwiseOr:
5697                                 method_name = "Or";
5698                                 break;
5699                         case Operator.Division:
5700                                 method_name = "Divide";
5701                                 break;
5702                         case Operator.Equality:
5703                                 method_name = "Equal";
5704                                 lift_arg = true;
5705                                 break;
5706                         case Operator.ExclusiveOr:
5707                                 method_name = "ExclusiveOr";
5708                                 break;
5709                         case Operator.GreaterThan:
5710                                 method_name = "GreaterThan";
5711                                 lift_arg = true;
5712                                 break;
5713                         case Operator.GreaterThanOrEqual:
5714                                 method_name = "GreaterThanOrEqual";
5715                                 lift_arg = true;
5716                                 break;
5717                         case Operator.Inequality:
5718                                 method_name = "NotEqual";
5719                                 lift_arg = true;
5720                                 break;
5721                         case Operator.LeftShift:
5722                                 method_name = "LeftShift";
5723                                 break;
5724                         case Operator.LessThan:
5725                                 method_name = "LessThan";
5726                                 lift_arg = true;
5727                                 break;
5728                         case Operator.LessThanOrEqual:
5729                                 method_name = "LessThanOrEqual";
5730                                 lift_arg = true;
5731                                 break;
5732                         case Operator.LogicalAnd:
5733                                 method_name = "AndAlso";
5734                                 break;
5735                         case Operator.LogicalOr:
5736                                 method_name = "OrElse";
5737                                 break;
5738                         case Operator.Modulus:
5739                                 method_name = "Modulo";
5740                                 break;
5741                         case Operator.Multiply:
5742                                 if (method == null && ec.HasSet (ResolveContext.Options.CheckedScope) && !IsFloat (type))
5743                                         method_name = "MultiplyChecked";
5744                                 else
5745                                         method_name = "Multiply";
5746                                 break;
5747                         case Operator.RightShift:
5748                                 method_name = "RightShift";
5749                                 break;
5750                         case Operator.Subtraction:
5751                                 if (method == null && ec.HasSet (ResolveContext.Options.CheckedScope) && !IsFloat (type))
5752                                         method_name = "SubtractChecked";
5753                                 else
5754                                         method_name = "Subtract";
5755                                 break;
5756
5757                         default:
5758                                 throw new InternalErrorException ("Unknown expression tree binary operator " + oper);
5759                         }
5760
5761                         Arguments args = new Arguments (2);
5762                         args.Add (new Argument (left.CreateExpressionTree (ec)));
5763                         args.Add (new Argument (right.CreateExpressionTree (ec)));
5764                         if (method != null) {
5765                                 if (lift_arg)
5766                                         args.Add (new Argument (new BoolLiteral (ec.BuiltinTypes, false, loc)));
5767
5768                                 args.Add (new Argument (method));
5769                         }
5770
5771                         return CreateExpressionFactoryCall (ec, method_name, args);
5772                 }
5773
5774                 public override object Accept (StructuralVisitor visitor)
5775                 {
5776                         return visitor.Visit (this);
5777                 }
5778
5779         }
5780
5781         //
5782         // Represents the operation a + b [+ c [+ d [+ ...]]], where a is a string
5783         // b, c, d... may be strings or objects.
5784         //
5785         public class StringConcat : Expression
5786         {
5787                 Arguments arguments;
5788
5789                 StringConcat (Location loc)
5790                 {
5791                         this.loc = loc;
5792                         arguments = new Arguments (2);
5793                 }
5794
5795                 public override bool ContainsEmitWithAwait ()
5796                 {
5797                         return arguments.ContainsEmitWithAwait ();
5798                 }
5799
5800                 public static StringConcat Create (ResolveContext rc, Expression left, Expression right, Location loc)
5801                 {
5802                         if (left.eclass == ExprClass.Unresolved || right.eclass == ExprClass.Unresolved)
5803                                 throw new ArgumentException ();
5804
5805                         var s = new StringConcat (loc);
5806                         s.type = rc.BuiltinTypes.String;
5807                         s.eclass = ExprClass.Value;
5808
5809                         s.Append (rc, left);
5810                         s.Append (rc, right);
5811                         return s;
5812                 }
5813
5814                 public override Expression CreateExpressionTree (ResolveContext ec)
5815                 {
5816                         Argument arg = arguments [0];
5817                         return CreateExpressionAddCall (ec, arg, arg.CreateExpressionTree (ec), 1);
5818                 }
5819
5820                 //
5821                 // Creates nested calls tree from an array of arguments used for IL emit
5822                 //
5823                 Expression CreateExpressionAddCall (ResolveContext ec, Argument left, Expression left_etree, int pos)
5824                 {
5825                         Arguments concat_args = new Arguments (2);
5826                         Arguments add_args = new Arguments (3);
5827
5828                         concat_args.Add (left);
5829                         add_args.Add (new Argument (left_etree));
5830
5831                         concat_args.Add (arguments [pos]);
5832                         add_args.Add (new Argument (arguments [pos].CreateExpressionTree (ec)));
5833
5834                         var methods = GetConcatMethodCandidates ();
5835                         if (methods == null)
5836                                 return null;
5837
5838                         var res = new OverloadResolver (methods, OverloadResolver.Restrictions.NoBaseMembers, loc);
5839                         var method = res.ResolveMember<MethodSpec> (ec, ref concat_args);
5840                         if (method == null)
5841                                 return null;
5842
5843                         add_args.Add (new Argument (new TypeOfMethod (method, loc)));
5844
5845                         Expression expr = CreateExpressionFactoryCall (ec, "Add", add_args);
5846                         if (++pos == arguments.Count)
5847                                 return expr;
5848
5849                         left = new Argument (new EmptyExpression (method.ReturnType));
5850                         return CreateExpressionAddCall (ec, left, expr, pos);
5851                 }
5852
5853                 protected override Expression DoResolve (ResolveContext ec)
5854                 {
5855                         return this;
5856                 }
5857
5858                 void Append (ResolveContext rc, Expression operand)
5859                 {
5860                         //
5861                         // Constant folding
5862                         //
5863                         StringConstant sc = operand as StringConstant;
5864                         if (sc != null) {
5865                                 if (arguments.Count != 0) {
5866                                         Argument last_argument = arguments [arguments.Count - 1];
5867                                         StringConstant last_expr_constant = last_argument.Expr as StringConstant;
5868                                         if (last_expr_constant != null) {
5869                                                 last_argument.Expr = new StringConstant (rc.BuiltinTypes, last_expr_constant.Value + sc.Value, sc.Location);
5870                                                 return;
5871                                         }
5872                                 }
5873                         } else {
5874                                 //
5875                                 // Multiple (3+) concatenation are resolved as multiple StringConcat instances
5876                                 //
5877                                 StringConcat concat_oper = operand as StringConcat;
5878                                 if (concat_oper != null) {
5879                                         arguments.AddRange (concat_oper.arguments);
5880                                         return;
5881                                 }
5882                         }
5883
5884                         arguments.Add (new Argument (operand));
5885                 }
5886
5887                 IList<MemberSpec> GetConcatMethodCandidates ()
5888                 {
5889                         return MemberCache.FindMembers (type, "Concat", true);
5890                 }
5891
5892                 public override void Emit (EmitContext ec)
5893                 {
5894                         // Optimize by removing any extra null arguments, they are no-op
5895                         for (int i = 0; i < arguments.Count; ++i) {
5896                                 if (arguments[i].Expr is NullConstant)
5897                                         arguments.RemoveAt (i--);
5898                         }
5899
5900                         var members = GetConcatMethodCandidates ();
5901                         var res = new OverloadResolver (members, OverloadResolver.Restrictions.NoBaseMembers, loc);
5902                         var method = res.ResolveMember<MethodSpec> (new ResolveContext (ec.MemberContext), ref arguments);
5903                         if (method != null) {
5904                                 var call = new CallEmitter ();
5905                                 call.EmitPredefined (ec, method, arguments, false);
5906                         }
5907                 }
5908
5909                 public override void FlowAnalysis (FlowAnalysisContext fc)
5910                 {
5911                         arguments.FlowAnalysis (fc);
5912                 }
5913
5914                 public override SLE.Expression MakeExpression (BuilderContext ctx)
5915                 {
5916                         if (arguments.Count != 2)
5917                                 throw new NotImplementedException ("arguments.Count != 2");
5918
5919                         var concat = typeof (string).GetMethod ("Concat", new[] { typeof (object), typeof (object) });
5920                         return SLE.Expression.Add (arguments[0].Expr.MakeExpression (ctx), arguments[1].Expr.MakeExpression (ctx), concat);
5921                 }
5922         }
5923
5924         //
5925         // User-defined conditional logical operator
5926         //
5927         public class ConditionalLogicalOperator : UserOperatorCall
5928         {
5929                 readonly bool is_and;
5930                 Expression oper_expr;
5931
5932                 public ConditionalLogicalOperator (MethodSpec oper, Arguments arguments, Func<ResolveContext, Expression, Expression> expr_tree, bool is_and, Location loc)
5933                         : base (oper, arguments, expr_tree, loc)
5934                 {
5935                         this.is_and = is_and;
5936                         eclass = ExprClass.Unresolved;
5937                 }
5938
5939                 protected override Expression DoResolve (ResolveContext ec)
5940                 {
5941                         AParametersCollection pd = oper.Parameters;
5942                         if (!TypeSpecComparer.IsEqual (type, pd.Types[0]) || !TypeSpecComparer.IsEqual (type, pd.Types[1])) {
5943                                 ec.Report.Error (217, loc,
5944                                         "A user-defined operator `{0}' must have each parameter type and return type of the same type in order to be applicable as a short circuit operator",
5945                                         oper.GetSignatureForError ());
5946                                 return null;
5947                         }
5948
5949                         Expression left_dup = new EmptyExpression (type);
5950                         Expression op_true = GetOperatorTrue (ec, left_dup, loc);
5951                         Expression op_false = GetOperatorFalse (ec, left_dup, loc);
5952                         if (op_true == null || op_false == null) {
5953                                 ec.Report.Error (218, loc,
5954                                         "The type `{0}' must have operator `true' and operator `false' defined when `{1}' is used as a short circuit operator",
5955                                         type.GetSignatureForError (), oper.GetSignatureForError ());
5956                                 return null;
5957                         }
5958
5959                         oper_expr = is_and ? op_false : op_true;
5960                         eclass = ExprClass.Value;
5961                         return this;
5962                 }
5963
5964                 public override void Emit (EmitContext ec)
5965                 {
5966                         Label end_target = ec.DefineLabel ();
5967
5968                         //
5969                         // Emit and duplicate left argument
5970                         //
5971                         bool right_contains_await = ec.HasSet (BuilderContext.Options.AsyncBody) && arguments[1].Expr.ContainsEmitWithAwait ();
5972                         if (right_contains_await) {
5973                                 arguments[0] = arguments[0].EmitToField (ec, false);
5974                                 arguments[0].Expr.Emit (ec);
5975                         } else {
5976                                 arguments[0].Expr.Emit (ec);
5977                                 ec.Emit (OpCodes.Dup);
5978                                 arguments.RemoveAt (0);
5979                         }
5980
5981                         oper_expr.EmitBranchable (ec, end_target, true);
5982
5983                         base.Emit (ec);
5984
5985                         if (right_contains_await) {
5986                                 //
5987                                 // Special handling when right expression contains await and left argument
5988                                 // could not be left on stack before logical branch
5989                                 //
5990                                 Label skip_left_load = ec.DefineLabel ();
5991                                 ec.Emit (OpCodes.Br_S, skip_left_load);
5992                                 ec.MarkLabel (end_target);
5993                                 arguments[0].Expr.Emit (ec);
5994                                 ec.MarkLabel (skip_left_load);
5995                         } else {
5996                                 ec.MarkLabel (end_target);
5997                         }
5998                 }
5999         }
6000
6001         public class PointerArithmetic : Expression {
6002                 Expression left, right;
6003                 readonly Binary.Operator op;
6004
6005                 //
6006                 // We assume that `l' is always a pointer
6007                 //
6008                 public PointerArithmetic (Binary.Operator op, Expression l, Expression r, TypeSpec t, Location loc)
6009                 {
6010                         type = t;
6011                         this.loc = loc;
6012                         left = l;
6013                         right = r;
6014                         this.op = op;
6015                 }
6016
6017                 public override bool ContainsEmitWithAwait ()
6018                 {
6019                         throw new NotImplementedException ();
6020                 }
6021
6022                 public override Expression CreateExpressionTree (ResolveContext ec)
6023                 {
6024                         Error_PointerInsideExpressionTree (ec);
6025                         return null;
6026                 }
6027
6028                 protected override Expression DoResolve (ResolveContext ec)
6029                 {
6030                         eclass = ExprClass.Variable;
6031
6032                         var pc = left.Type as PointerContainer;
6033                         if (pc != null && pc.Element.Kind == MemberKind.Void) {
6034                                 Error_VoidPointerOperation (ec);
6035                                 return null;
6036                         }
6037
6038                         return this;
6039                 }
6040
6041                 public override void Emit (EmitContext ec)
6042                 {
6043                         TypeSpec op_type = left.Type;
6044
6045                         // It must be either array or fixed buffer
6046                         TypeSpec element;
6047                         if (TypeManager.HasElementType (op_type)) {
6048                                 element = TypeManager.GetElementType (op_type);
6049                         } else {
6050                                 FieldExpr fe = left as FieldExpr;
6051                                 if (fe != null)
6052                                         element = ((FixedFieldSpec) (fe.Spec)).ElementType;
6053                                 else
6054                                         element = op_type;
6055                         }
6056
6057                         int size = BuiltinTypeSpec.GetSize(element);
6058                         TypeSpec rtype = right.Type;
6059
6060                         if ((op & Binary.Operator.SubtractionMask) != 0 && rtype.IsPointer){
6061                                 //
6062                                 // handle (pointer - pointer)
6063                                 //
6064                                 left.Emit (ec);
6065                                 right.Emit (ec);
6066                                 ec.Emit (OpCodes.Sub);
6067
6068                                 if (size != 1){
6069                                         if (size == 0)
6070                                                 ec.Emit (OpCodes.Sizeof, element);
6071                                         else
6072                                                 ec.EmitInt (size);
6073                                         ec.Emit (OpCodes.Div);
6074                                 }
6075                                 ec.Emit (OpCodes.Conv_I8);
6076                         } else {
6077                                 //
6078                                 // handle + and - on (pointer op int)
6079                                 //
6080                                 Constant left_const = left as Constant;
6081                                 if (left_const != null) {
6082                                         //
6083                                         // Optimize ((T*)null) pointer operations
6084                                         //
6085                                         if (left_const.IsDefaultValue) {
6086                                                 left = EmptyExpression.Null;
6087                                         } else {
6088                                                 left_const = null;
6089                                         }
6090                                 }
6091
6092                                 left.Emit (ec);
6093
6094                                 var right_const = right as Constant;
6095                                 if (right_const != null) {
6096                                         //
6097                                         // Optimize 0-based arithmetic
6098                                         //
6099                                         if (right_const.IsDefaultValue)
6100                                                 return;
6101
6102                                         if (size != 0)
6103                                                 right = new IntConstant (ec.BuiltinTypes, size, right.Location);
6104                                         else
6105                                                 right = new SizeOf (new TypeExpression (element, right.Location), right.Location);
6106
6107                                         // TODO: Should be the checks resolve context sensitive?
6108                                         ResolveContext rc = new ResolveContext (ec.MemberContext, ResolveContext.Options.UnsafeScope);
6109                                         right = new Binary (Binary.Operator.Multiply, right, right_const).Resolve (rc);
6110                                         if (right == null)
6111                                                 return;
6112                                 }
6113
6114                                 right.Emit (ec);
6115                                 if (right_const == null) {
6116                                         switch (rtype.BuiltinType) {
6117                                         case BuiltinTypeSpec.Type.SByte:
6118                                         case BuiltinTypeSpec.Type.Byte:
6119                                         case BuiltinTypeSpec.Type.Short:
6120                                         case BuiltinTypeSpec.Type.UShort:
6121                                         case BuiltinTypeSpec.Type.Int:
6122                                                 ec.Emit (OpCodes.Conv_I);
6123                                                 break;
6124                                         case BuiltinTypeSpec.Type.UInt:
6125                                                 ec.Emit (OpCodes.Conv_U);
6126                                                 break;
6127                                         }
6128                                 }
6129
6130                                 if (right_const == null && size != 1){
6131                                         if (size == 0)
6132                                                 ec.Emit (OpCodes.Sizeof, element);
6133                                         else
6134                                                 ec.EmitInt (size);
6135                                         if (rtype.BuiltinType == BuiltinTypeSpec.Type.Long || rtype.BuiltinType == BuiltinTypeSpec.Type.ULong)
6136                                                 ec.Emit (OpCodes.Conv_I8);
6137
6138                                         Binary.EmitOperatorOpcode (ec, Binary.Operator.Multiply, rtype, right);
6139                                 }
6140
6141                                 if (left_const == null) {
6142                                         if (rtype.BuiltinType == BuiltinTypeSpec.Type.Long)
6143                                                 ec.Emit (OpCodes.Conv_I);
6144                                         else if (rtype.BuiltinType == BuiltinTypeSpec.Type.ULong)
6145                                                 ec.Emit (OpCodes.Conv_U);
6146
6147                                         Binary.EmitOperatorOpcode (ec, op, op_type, right);
6148                                 }
6149                         }
6150                 }
6151         }
6152
6153         //
6154         // A boolean-expression is an expression that yields a result
6155         // of type bool
6156         //
6157         public class BooleanExpression : ShimExpression
6158         {
6159                 public BooleanExpression (Expression expr)
6160                         : base (expr)
6161                 {
6162                         this.loc = expr.Location;
6163                 }
6164
6165                 public override Expression CreateExpressionTree (ResolveContext ec)
6166                 {
6167                         // TODO: We should emit IsTrue (v4) instead of direct user operator
6168                         // call but that would break csc compatibility
6169                         return base.CreateExpressionTree (ec);
6170                 }
6171
6172                 protected override Expression DoResolve (ResolveContext ec)
6173                 {
6174                         // A boolean-expression is required to be of a type
6175                         // that can be implicitly converted to bool or of
6176                         // a type that implements operator true
6177
6178                         expr = expr.Resolve (ec);
6179                         if (expr == null)
6180                                 return null;
6181
6182                         Assign ass = expr as Assign;
6183                         if (ass != null && ass.Source is Constant) {
6184                                 ec.Report.Warning (665, 3, loc,
6185                                         "Assignment in conditional expression is always constant. Did you mean to use `==' instead ?");
6186                         }
6187
6188                         if (expr.Type.BuiltinType == BuiltinTypeSpec.Type.Bool)
6189                                 return expr;
6190
6191                         if (expr.Type.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
6192                                 Arguments args = new Arguments (1);
6193                                 args.Add (new Argument (expr));
6194                                 return DynamicUnaryConversion.CreateIsTrue (ec, args, loc).Resolve (ec);
6195                         }
6196
6197                         type = ec.BuiltinTypes.Bool;
6198                         Expression converted = Convert.ImplicitConversion (ec, expr, type, loc);
6199                         if (converted != null)
6200                                 return converted;
6201
6202                         //
6203                         // If no implicit conversion to bool exists, try using `operator true'
6204                         //
6205                         converted = GetOperatorTrue (ec, expr, loc);
6206                         if (converted == null) {
6207                                 expr.Error_ValueCannotBeConverted (ec, type, false);
6208                                 return null;
6209                         }
6210
6211                         return converted;
6212                 }
6213
6214                 public override object Accept (StructuralVisitor visitor)
6215                 {
6216                         return visitor.Visit (this);
6217                 }
6218         }
6219
6220         public class BooleanExpressionFalse : Unary
6221         {
6222                 public BooleanExpressionFalse (Expression expr)
6223                         : base (Operator.LogicalNot, expr, expr.Location)
6224                 {
6225                 }
6226
6227                 protected override Expression ResolveOperator (ResolveContext ec, Expression expr)
6228                 {
6229                         return GetOperatorFalse (ec, expr, loc) ?? base.ResolveOperator (ec, expr);
6230                 }
6231         }
6232
6233         /// <summary>
6234         ///   Implements the ternary conditional operator (?:)
6235         /// </summary>
6236         public class Conditional : Expression {
6237                 Expression expr, true_expr, false_expr;
6238
6239                 public Conditional (Expression expr, Expression true_expr, Expression false_expr, Location loc)
6240                 {
6241                         this.expr = expr;
6242                         this.true_expr = true_expr;
6243                         this.false_expr = false_expr;
6244                         this.loc = loc;
6245                 }
6246
6247                 #region Properties
6248
6249                 public Expression Expr {
6250                         get {
6251                                 return expr;
6252                         }
6253                 }
6254
6255                 public Expression TrueExpr {
6256                         get {
6257                                 return true_expr;
6258                         }
6259                 }
6260
6261                 public Expression FalseExpr {
6262                         get {
6263                                 return false_expr;
6264                         }
6265                 }
6266
6267                 #endregion
6268
6269                 public override bool ContainsEmitWithAwait ()
6270                 {
6271                         return Expr.ContainsEmitWithAwait () || true_expr.ContainsEmitWithAwait () || false_expr.ContainsEmitWithAwait ();
6272                 }
6273
6274                 public override Expression CreateExpressionTree (ResolveContext ec)
6275                 {
6276                         Arguments args = new Arguments (3);
6277                         args.Add (new Argument (expr.CreateExpressionTree (ec)));
6278                         args.Add (new Argument (true_expr.CreateExpressionTree (ec)));
6279                         args.Add (new Argument (false_expr.CreateExpressionTree (ec)));
6280                         return CreateExpressionFactoryCall (ec, "Condition", args);
6281                 }
6282
6283                 protected override Expression DoResolve (ResolveContext ec)
6284                 {
6285                         expr = expr.Resolve (ec);
6286                         true_expr = true_expr.Resolve (ec);
6287                         false_expr = false_expr.Resolve (ec);
6288
6289                         if (true_expr == null || false_expr == null || expr == null)
6290                                 return null;
6291
6292                         eclass = ExprClass.Value;
6293                         TypeSpec true_type = true_expr.Type;
6294                         TypeSpec false_type = false_expr.Type;
6295                         type = true_type;
6296
6297                         //
6298                         // First, if an implicit conversion exists from true_expr
6299                         // to false_expr, then the result type is of type false_expr.Type
6300                         //
6301                         if (!TypeSpecComparer.IsEqual (true_type, false_type)) {
6302                                 Expression conv = Convert.ImplicitConversion (ec, true_expr, false_type, loc);
6303                                 if (conv != null && true_type.BuiltinType != BuiltinTypeSpec.Type.Dynamic) {
6304                                         //
6305                                         // Check if both can convert implicitly to each other's type
6306                                         //
6307                                         type = false_type;
6308
6309                                         if (false_type.BuiltinType != BuiltinTypeSpec.Type.Dynamic) {
6310                                                 var conv_false_expr = Convert.ImplicitConversion (ec, false_expr, true_type, loc);
6311                                                 //
6312                                                 // LAMESPEC: There seems to be hardcoded promotition to int type when
6313                                                 // both sides are numeric constants and one side is int constant and
6314                                                 // other side is numeric constant convertible to int.
6315                                                 //
6316                                                 // var res = condition ? (short)1 : 1;
6317                                                 //
6318                                                 // Type of res is int even if according to the spec the conversion is
6319                                                 // ambiguous because 1 literal can be converted to short.
6320                                                 //
6321                                                 if (conv_false_expr != null) {
6322                                                         if (conv_false_expr.Type.BuiltinType == BuiltinTypeSpec.Type.Int && conv is Constant) {
6323                                                                 type = true_type;
6324                                                                 conv_false_expr = null;
6325                                                         } else if (type.BuiltinType == BuiltinTypeSpec.Type.Int && conv_false_expr is Constant) {
6326                                                                 conv_false_expr = null;
6327                                                         }
6328                                                 }
6329
6330                                                 if (conv_false_expr != null) {
6331                                                         ec.Report.Error (172, true_expr.Location,
6332                                                                 "Type of conditional expression cannot be determined as `{0}' and `{1}' convert implicitly to each other",
6333                                                                         true_type.GetSignatureForError (), false_type.GetSignatureForError ());
6334                                                 }
6335                                         }
6336
6337                                         true_expr = conv;
6338                                         if (true_expr.Type != type)
6339                                                 true_expr = EmptyCast.Create (true_expr, type);
6340                                 } else if ((conv = Convert.ImplicitConversion (ec, false_expr, true_type, loc)) != null) {
6341                                         false_expr = conv;
6342                                 } else {
6343                                         if (false_type != InternalType.ErrorType) {
6344                                                 ec.Report.Error (173, true_expr.Location,
6345                                                         "Type of conditional expression cannot be determined because there is no implicit conversion between `{0}' and `{1}'",
6346                                                         true_type.GetSignatureForError (), false_type.GetSignatureForError ());
6347                                         }
6348                                         return null;
6349                                 }
6350                         }
6351
6352                         Constant c = expr as Constant;
6353                         if (c != null) {
6354                                 bool is_false = c.IsDefaultValue;
6355
6356                                 //
6357                                 // Don't issue the warning for constant expressions
6358                                 //
6359                                 if (!(is_false ? true_expr is Constant : false_expr is Constant)) {
6360                                         // CSC: Missing warning
6361                                         Warning_UnreachableExpression (ec, is_false ? true_expr.Location : false_expr.Location);
6362                                 }
6363
6364                                 return ReducedExpression.Create (
6365                                         is_false ? false_expr : true_expr, this,
6366                                         false_expr is Constant && true_expr is Constant).Resolve (ec);
6367                         }
6368
6369                         return this;
6370                 }
6371
6372                 public override void Emit (EmitContext ec)
6373                 {
6374                         Label false_target = ec.DefineLabel ();
6375                         Label end_target = ec.DefineLabel ();
6376
6377                         expr.EmitBranchable (ec, false_target, false);
6378                         true_expr.Emit (ec);
6379
6380                         //
6381                         // Verifier doesn't support interface merging. When there are two types on
6382                         // the stack without common type hint and the common type is an interface.
6383                         // Use temporary local to give verifier hint on what type to unify the stack
6384                         //
6385                         if (type.IsInterface && true_expr is EmptyCast && false_expr is EmptyCast) {
6386                                 var temp = ec.GetTemporaryLocal (type);
6387                                 ec.Emit (OpCodes.Stloc, temp);
6388                                 ec.Emit (OpCodes.Ldloc, temp);
6389                                 ec.FreeTemporaryLocal (temp, type);
6390                         }
6391
6392                         ec.Emit (OpCodes.Br, end_target);
6393                         ec.MarkLabel (false_target);
6394                         false_expr.Emit (ec);
6395                         ec.MarkLabel (end_target);
6396                 }
6397
6398                 public override void FlowAnalysis (FlowAnalysisContext fc)
6399                 {
6400                         expr.FlowAnalysisConditional (fc);
6401                         var expr_true = fc.DefiniteAssignmentOnTrue;
6402                         var expr_false = fc.DefiniteAssignmentOnFalse;
6403
6404                         fc.BranchDefiniteAssignment (expr_true);
6405                         true_expr.FlowAnalysis (fc);
6406                         var true_fc = fc.DefiniteAssignment;
6407
6408                         fc.BranchDefiniteAssignment (expr_false);
6409                         false_expr.FlowAnalysis (fc);
6410
6411                         fc.DefiniteAssignment &= true_fc;
6412                 }
6413
6414                 public override void FlowAnalysisConditional (FlowAnalysisContext fc)
6415                 {
6416                         expr.FlowAnalysisConditional (fc);
6417                         var expr_true = fc.DefiniteAssignmentOnTrue;
6418                         var expr_false = fc.DefiniteAssignmentOnFalse;
6419
6420                         fc.DefiniteAssignmentOnTrue = fc.DefiniteAssignmentOnFalse = fc.DefiniteAssignment = new DefiniteAssignmentBitSet (expr_true);
6421                         true_expr.FlowAnalysisConditional (fc);
6422                         var true_fc = fc.DefiniteAssignment;
6423                         var true_da_true = fc.DefiniteAssignmentOnTrue;
6424                         var true_da_false = fc.DefiniteAssignmentOnFalse;
6425
6426                         fc.DefiniteAssignmentOnTrue = fc.DefiniteAssignmentOnFalse = fc.DefiniteAssignment = new DefiniteAssignmentBitSet (expr_false);
6427                         false_expr.FlowAnalysisConditional (fc);
6428
6429                         fc.DefiniteAssignment &= true_fc;
6430                         fc.DefiniteAssignmentOnTrue = true_da_true & fc.DefiniteAssignmentOnTrue;
6431                         fc.DefiniteAssignmentOnFalse = true_da_false & fc.DefiniteAssignmentOnFalse;
6432                 }
6433
6434                 protected override void CloneTo (CloneContext clonectx, Expression t)
6435                 {
6436                         Conditional target = (Conditional) t;
6437
6438                         target.expr = expr.Clone (clonectx);
6439                         target.true_expr = true_expr.Clone (clonectx);
6440                         target.false_expr = false_expr.Clone (clonectx);
6441                 }
6442         }
6443
6444         public abstract class VariableReference : Expression, IAssignMethod, IMemoryLocation, IVariableReference
6445         {
6446                 LocalTemporary temp;
6447
6448                 #region Abstract
6449                 public abstract HoistedVariable GetHoistedVariable (AnonymousExpression ae);
6450                 public abstract void SetHasAddressTaken ();
6451
6452                 public abstract bool IsLockedByStatement { get; set; }
6453
6454                 public abstract bool IsFixed { get; }
6455                 public abstract bool IsRef { get; }
6456                 public abstract string Name { get; }
6457
6458                 //
6459                 // Variable IL data, it has to be protected to encapsulate hoisted variables
6460                 //
6461                 protected abstract ILocalVariable Variable { get; }
6462
6463                 //
6464                 // Variable flow-analysis data
6465                 //
6466                 public abstract VariableInfo VariableInfo { get; }
6467                 #endregion
6468
6469                 public virtual void AddressOf (EmitContext ec, AddressOp mode)
6470                 {
6471                         HoistedVariable hv = GetHoistedVariable (ec);
6472                         if (hv != null) {
6473                                 hv.AddressOf (ec, mode);
6474                                 return;
6475                         }
6476
6477                         Variable.EmitAddressOf (ec);
6478                 }
6479
6480                 public override bool ContainsEmitWithAwait ()
6481                 {
6482                         return false;
6483                 }
6484
6485                 public override Expression CreateExpressionTree (ResolveContext ec)
6486                 {
6487                         HoistedVariable hv = GetHoistedVariable (ec);
6488                         if (hv != null)
6489                                 return hv.CreateExpressionTree ();
6490
6491                         Arguments arg = new Arguments (1);
6492                         arg.Add (new Argument (this));
6493                         return CreateExpressionFactoryCall (ec, "Constant", arg);
6494                 }
6495
6496                 public override Expression DoResolveLValue (ResolveContext rc, Expression right_side)
6497                 {
6498                         if (IsLockedByStatement) {
6499                                 rc.Report.Warning (728, 2, loc,
6500                                         "Possibly incorrect assignment to `{0}' which is the argument to a using or lock statement",
6501                                         Name);
6502                         }
6503
6504                         return this;
6505                 }
6506
6507                 public override void Emit (EmitContext ec)
6508                 {
6509                         Emit (ec, false);
6510                 }
6511
6512                 public override void EmitSideEffect (EmitContext ec)
6513                 {
6514                         // do nothing
6515                 }
6516
6517                 //
6518                 // This method is used by parameters that are references, that are
6519                 // being passed as references:  we only want to pass the pointer (that
6520                 // is already stored in the parameter, not the address of the pointer,
6521                 // and not the value of the variable).
6522                 //
6523                 public void EmitLoad (EmitContext ec)
6524                 {
6525                         Variable.Emit (ec);
6526                 }
6527
6528                 public void Emit (EmitContext ec, bool leave_copy)
6529                 {
6530                         HoistedVariable hv = GetHoistedVariable (ec);
6531                         if (hv != null) {
6532                                 hv.Emit (ec, leave_copy);
6533                                 return;
6534                         }
6535
6536                         EmitLoad (ec);
6537
6538                         if (IsRef) {
6539                                 //
6540                                 // If we are a reference, we loaded on the stack a pointer
6541                                 // Now lets load the real value
6542                                 //
6543                                 ec.EmitLoadFromPtr (type);
6544                         }
6545
6546                         if (leave_copy) {
6547                                 ec.Emit (OpCodes.Dup);
6548
6549                                 if (IsRef) {
6550                                         temp = new LocalTemporary (Type);
6551                                         temp.Store (ec);
6552                                 }
6553                         }
6554                 }
6555
6556                 public void EmitAssign (EmitContext ec, Expression source, bool leave_copy,
6557                                         bool prepare_for_load)
6558                 {
6559                         HoistedVariable hv = GetHoistedVariable (ec);
6560                         if (hv != null) {
6561                                 hv.EmitAssign (ec, source, leave_copy, prepare_for_load);
6562                                 return;
6563                         }
6564
6565                         bool dereference = IsRef && !(source is ReferenceExpression);
6566                         New n_source = source as New;
6567                         if (n_source != null && n_source.CanEmitOptimizedLocalTarget (ec)) {
6568                                 if (!n_source.Emit (ec, this)) {
6569                                         if (leave_copy) {
6570                                                 EmitLoad (ec);
6571                                                 if (dereference)
6572                                                         ec.EmitLoadFromPtr (type);
6573                                         }
6574                                         return;
6575                                 }
6576                         } else {
6577                                 if (dereference)
6578                                         EmitLoad (ec);
6579
6580                                 source.Emit (ec);
6581                         }
6582
6583                         if (leave_copy) {
6584                                 ec.Emit (OpCodes.Dup);
6585                                 if (dereference) {
6586                                         temp = new LocalTemporary (Type);
6587                                         temp.Store (ec);
6588                                 }
6589                         }
6590
6591                         if (dereference)
6592                                 ec.EmitStoreFromPtr (type);
6593                         else
6594                                 Variable.EmitAssign (ec);
6595
6596                         if (temp != null) {
6597                                 temp.Emit (ec);
6598                                 temp.Release (ec);
6599                         }
6600                 }
6601
6602                 public override Expression EmitToField (EmitContext ec)
6603                 {
6604                         HoistedVariable hv = GetHoistedVariable (ec);
6605                         if (hv != null) {
6606                                 return hv.EmitToField (ec);
6607                         }
6608
6609                         return base.EmitToField (ec);
6610                 }
6611
6612                 public HoistedVariable GetHoistedVariable (ResolveContext rc)
6613                 {
6614                         return GetHoistedVariable (rc.CurrentAnonymousMethod);
6615                 }
6616
6617                 public HoistedVariable GetHoistedVariable (EmitContext ec)
6618                 {
6619                         return GetHoistedVariable (ec.CurrentAnonymousMethod);
6620                 }
6621
6622                 public override string GetSignatureForError ()
6623                 {
6624                         return Name;
6625                 }
6626
6627                 public bool IsHoisted {
6628                         get { return GetHoistedVariable ((AnonymousExpression) null) != null; }
6629                 }
6630         }
6631
6632         //
6633         // Resolved reference to a local variable
6634         //
6635         public class LocalVariableReference : VariableReference
6636         {
6637                 public LocalVariable local_info;
6638
6639                 public LocalVariableReference (LocalVariable li, Location l)
6640                 {
6641                         this.local_info = li;
6642                         loc = l;
6643                 }
6644
6645                 public override VariableInfo VariableInfo {
6646                         get { return local_info.VariableInfo; }
6647                 }
6648
6649                 public override HoistedVariable GetHoistedVariable (AnonymousExpression ae)
6650                 {
6651                         return local_info.HoistedVariant;
6652                 }
6653
6654                 #region Properties
6655
6656                 //
6657                 // A local variable is always fixed
6658                 //
6659                 public override bool IsFixed {
6660                         get {
6661                                 return true;
6662                         }
6663                 }
6664
6665                 public override bool IsLockedByStatement {
6666                         get {
6667                                 return local_info.IsLocked;
6668                         }
6669                         set {
6670                                 local_info.IsLocked = value;
6671                         }
6672                 }
6673
6674                 public override bool IsRef {
6675                         get { return local_info.IsByRef; }
6676                 }
6677
6678                 public override string Name {
6679                         get { return local_info.Name; }
6680                 }
6681
6682                 #endregion
6683
6684                 public override void FlowAnalysis (FlowAnalysisContext fc)
6685                 {
6686                         VariableInfo variable_info = VariableInfo;
6687                         if (variable_info == null)
6688                                 return;
6689
6690                         if (fc.IsDefinitelyAssigned (variable_info))
6691                                 return;
6692
6693                         fc.Report.Error (165, loc, "Use of unassigned local variable `{0}'", Name);
6694                         variable_info.SetAssigned (fc.DefiniteAssignment, true);
6695                 }
6696
6697                 public override void SetHasAddressTaken ()
6698                 {
6699                         local_info.SetHasAddressTaken ();
6700                 }
6701
6702                 void DoResolveBase (ResolveContext ec)
6703                 {
6704                         eclass = ExprClass.Variable;
6705                         type = local_info.Type;
6706
6707                         //
6708                         // If we are referencing a variable from the external block
6709                         // flag it for capturing
6710                         //
6711                         if (ec.MustCaptureVariable (local_info)) {
6712                                 if (local_info.AddressTaken) {
6713                                         AnonymousMethodExpression.Error_AddressOfCapturedVar (ec, this, loc);
6714                                 } else if (local_info.IsFixed) {
6715                                         ec.Report.Error (1764, loc,
6716                                                 "Cannot use fixed variable `{0}' inside an anonymous method, lambda expression or query expression",
6717                                                 GetSignatureForError ());
6718                                 } else if (local_info.IsByRef) {
6719                                         ec.Report.Error (8175, loc,
6720                                                 "Cannot use by-reference variable `{0}' inside an anonymous method, lambda expression, or query expression",
6721                                                 GetSignatureForError ());
6722                                 }
6723
6724                                 if (ec.IsVariableCapturingRequired) {
6725                                         AnonymousMethodStorey storey = local_info.Block.Explicit.CreateAnonymousMethodStorey (ec);
6726                                         storey.CaptureLocalVariable (ec, local_info);
6727                                 }
6728                         }
6729                 }
6730
6731                 protected override Expression DoResolve (ResolveContext ec)
6732                 {
6733                         local_info.SetIsUsed ();
6734
6735                         DoResolveBase (ec);
6736
6737                         if (local_info.Type == InternalType.VarOutType) {
6738                                 ec.Report.Error (8048, loc, "Cannot use uninitialized variable `{0}'",
6739                                         GetSignatureForError ());
6740
6741                                 type = InternalType.ErrorType;
6742                         }
6743
6744                         return this;
6745                 }
6746
6747                 public override Expression DoResolveLValue (ResolveContext ec, Expression rhs)
6748                 {
6749                         //
6750                         // Don't be too pedantic when variable is used as out param or for some broken code
6751                         // which uses property/indexer access to run some initialization
6752                         //
6753                         if (rhs == EmptyExpression.OutAccess || rhs.eclass == ExprClass.PropertyAccess || rhs.eclass == ExprClass.IndexerAccess)
6754                                 local_info.SetIsUsed ();
6755
6756                         if (local_info.IsReadonly && !ec.HasAny (ResolveContext.Options.FieldInitializerScope | ResolveContext.Options.UsingInitializerScope)) {
6757                                 if (rhs == EmptyExpression.LValueMemberAccess) {
6758                                         // CS1654 already reported
6759                                 } else {
6760                                         int code;
6761                                         string msg;
6762                                         if (rhs == EmptyExpression.OutAccess) {
6763                                                 code = 1657; msg = "Cannot pass `{0}' as a ref or out argument because it is a `{1}'";
6764                                         } else if (rhs == EmptyExpression.LValueMemberOutAccess) {
6765                                                 code = 1655; msg = "Cannot pass members of `{0}' as ref or out arguments because it is a `{1}'";
6766                                         } else if (rhs == EmptyExpression.UnaryAddress) {
6767                                                 code = 459; msg = "Cannot take the address of {1} `{0}'";
6768                                         } else {
6769                                                 code = 1656; msg = "Cannot assign to `{0}' because it is a `{1}'";
6770                                         }
6771                                         ec.Report.Error (code, loc, msg, Name, local_info.GetReadOnlyContext ());
6772                                 }
6773                         }
6774
6775                         if (eclass == ExprClass.Unresolved)
6776                                 DoResolveBase (ec);
6777
6778                         return base.DoResolveLValue (ec, rhs);
6779                 }
6780
6781                 public override int GetHashCode ()
6782                 {
6783                         return local_info.GetHashCode ();
6784                 }
6785
6786                 public override bool Equals (object obj)
6787                 {
6788                         LocalVariableReference lvr = obj as LocalVariableReference;
6789                         if (lvr == null)
6790                                 return false;
6791
6792                         return local_info == lvr.local_info;
6793                 }
6794
6795                 protected override ILocalVariable Variable {
6796                         get { return local_info; }
6797                 }
6798
6799                 public override string ToString ()
6800                 {
6801                         return String.Format ("{0} ({1}:{2})", GetType (), Name, loc);
6802                 }
6803
6804                 protected override void CloneTo (CloneContext clonectx, Expression t)
6805                 {
6806                         // Nothing
6807                 }
6808         }
6809
6810         /// <summary>
6811         ///   This represents a reference to a parameter in the intermediate
6812         ///   representation.
6813         /// </summary>
6814         public class ParameterReference : VariableReference
6815         {
6816                 protected ParametersBlock.ParameterInfo pi;
6817
6818                 public ParameterReference (ParametersBlock.ParameterInfo pi, Location loc)
6819                 {
6820                         this.pi = pi;
6821                         this.loc = loc;
6822                 }
6823
6824                 #region Properties
6825
6826                 public override bool IsLockedByStatement {
6827                         get {
6828                                 return pi.IsLocked;
6829                         }
6830                         set     {
6831                                 pi.IsLocked = value;
6832                         }
6833                 }
6834
6835                 public override bool IsRef {
6836                         get { return (pi.Parameter.ModFlags & Parameter.Modifier.RefOutMask) != 0; }
6837                 }
6838
6839                 bool HasOutModifier {
6840                         get { return (pi.Parameter.ModFlags & Parameter.Modifier.OUT) != 0; }
6841                 }
6842
6843                 public override HoistedVariable GetHoistedVariable (AnonymousExpression ae)
6844                 {
6845                         return pi.Parameter.HoistedVariant;
6846                 }
6847
6848                 //
6849                 // A ref or out parameter is classified as a moveable variable, even
6850                 // if the argument given for the parameter is a fixed variable
6851                 //
6852                 public override bool IsFixed {
6853                         get { return !IsRef; }
6854                 }
6855
6856                 public override string Name {
6857                         get { return Parameter.Name; }
6858                 }
6859
6860                 public Parameter Parameter {
6861                         get { return pi.Parameter; }
6862                 }
6863
6864                 public override VariableInfo VariableInfo {
6865                         get { return pi.VariableInfo; }
6866                 }
6867
6868                 protected override ILocalVariable Variable {
6869                         get { return Parameter; }
6870                 }
6871
6872                 #endregion
6873
6874                 public override void AddressOf (EmitContext ec, AddressOp mode)
6875                 {
6876                         //
6877                         // ParameterReferences might already be a reference
6878                         //
6879                         if (IsRef) {
6880                                 EmitLoad (ec);
6881                                 return;
6882                         }
6883
6884                         base.AddressOf (ec, mode);
6885                 }
6886
6887                 public override void SetHasAddressTaken ()
6888                 {
6889                         Parameter.HasAddressTaken = true;
6890                 }
6891
6892                 bool DoResolveBase (ResolveContext ec)
6893                 {
6894                         if (eclass != ExprClass.Unresolved)
6895                                 return true;
6896
6897                         type = pi.ParameterType;
6898                         eclass = ExprClass.Variable;
6899
6900                         //
6901                         // If we are referencing a parameter from the external block
6902                         // flag it for capturing
6903                         //
6904                         if (ec.MustCaptureVariable (pi)) {
6905                                 if (Parameter.HasAddressTaken)
6906                                         AnonymousMethodExpression.Error_AddressOfCapturedVar (ec, this, loc);
6907
6908                                 if (IsRef) {
6909                                         ec.Report.Error (1628, loc,
6910                                                 "Parameter `{0}' cannot be used inside `{1}' when using `ref' or `out' modifier",
6911                                                 Name, ec.CurrentAnonymousMethod.ContainerType);
6912                                 }
6913
6914                                 if (ec.IsVariableCapturingRequired && !pi.Block.ParametersBlock.IsExpressionTree) {
6915                                         AnonymousMethodStorey storey = pi.Block.Explicit.CreateAnonymousMethodStorey (ec);
6916                                         storey.CaptureParameter (ec, pi, this);
6917                                 }
6918                         }
6919
6920                         return true;
6921                 }
6922
6923                 public override int GetHashCode ()
6924                 {
6925                         return Name.GetHashCode ();
6926                 }
6927
6928                 public override bool Equals (object obj)
6929                 {
6930                         ParameterReference pr = obj as ParameterReference;
6931                         if (pr == null)
6932                                 return false;
6933
6934                         return Name == pr.Name;
6935                 }
6936
6937                 protected override void CloneTo (CloneContext clonectx, Expression target)
6938                 {
6939                         // Nothing to clone
6940                         return;
6941                 }
6942
6943                 public override Expression CreateExpressionTree (ResolveContext ec)
6944                 {
6945                         HoistedVariable hv = GetHoistedVariable (ec);
6946                         if (hv != null)
6947                                 return hv.CreateExpressionTree ();
6948
6949                         return Parameter.ExpressionTreeVariableReference ();
6950                 }
6951
6952                 protected override Expression DoResolve (ResolveContext ec)
6953                 {
6954                         if (!DoResolveBase (ec))
6955                                 return null;
6956
6957                         return this;
6958                 }
6959
6960                 public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
6961                 {
6962                         if (!DoResolveBase (ec))
6963                                 return null;
6964
6965                         if (Parameter.HoistedVariant != null)
6966                                 Parameter.HoistedVariant.IsAssigned = true;
6967
6968                         return base.DoResolveLValue (ec, right_side);
6969                 }
6970
6971                 public override void FlowAnalysis (FlowAnalysisContext fc)
6972                 {
6973                         VariableInfo variable_info = VariableInfo;
6974                         if (variable_info == null)
6975                                 return;
6976
6977                         if (fc.IsDefinitelyAssigned (variable_info))
6978                                 return;
6979
6980                         fc.Report.Error (269, loc, "Use of unassigned out parameter `{0}'", Name);
6981                         fc.SetVariableAssigned (variable_info);
6982                 }
6983         }
6984
6985         /// <summary>
6986         ///   Invocation of methods or delegates.
6987         /// </summary>
6988         public class Invocation : ExpressionStatement
6989         {
6990                 public class Predefined : Invocation
6991                 {
6992                         public Predefined (MethodGroupExpr expr, Arguments arguments)
6993                                 : base (expr, arguments)
6994                         {
6995                                 this.mg = expr;
6996                         }
6997
6998                         protected override MethodGroupExpr DoResolveOverload (ResolveContext rc)
6999                         {
7000                                 mg.BestCandidate.CheckObsoleteness (rc, loc);
7001
7002                                 return mg;
7003                         }
7004                 }
7005
7006                 protected Arguments arguments;
7007                 protected Expression expr;
7008                 protected MethodGroupExpr mg;
7009                 bool conditional_access_receiver;
7010
7011                 public Invocation (Expression expr, Arguments arguments)
7012                 {
7013                         this.expr = expr;
7014                         this.arguments = arguments;
7015                         if (expr != null) {
7016                                 loc = expr.Location;
7017                         }
7018                 }
7019
7020                 #region Properties
7021                 public Arguments Arguments {
7022                         get {
7023                                 return arguments;
7024                         }
7025                 }
7026
7027                 public Expression Exp {
7028                         get {
7029                                 return expr;
7030                         }
7031                 }
7032
7033                 public MethodGroupExpr MethodGroup {
7034                         get {
7035                                 return mg;
7036                         }
7037                 }
7038
7039                 public override Location StartLocation {
7040                         get {
7041                                 return expr.StartLocation;
7042                         }
7043                 }
7044
7045                 #endregion
7046
7047                 public override MethodGroupExpr CanReduceLambda (AnonymousMethodBody body)
7048                 {
7049                         if (MethodGroup == null)
7050                                 return null;
7051
7052                         var candidate = MethodGroup.BestCandidate;
7053                         if (candidate == null || !(candidate.IsStatic || Exp is This))
7054                                 return null;
7055
7056                         var args_count = arguments == null ? 0 : arguments.Count;
7057                         if (args_count != body.Parameters.Count)
7058                                 return null;
7059
7060                         var lambda_parameters = body.Block.Parameters.FixedParameters;
7061                         for (int i = 0; i < args_count; ++i) {
7062                                 var pr = arguments[i].Expr as ParameterReference;
7063                                 if (pr == null)
7064                                         return null;
7065
7066                                 if (lambda_parameters[i] != pr.Parameter)
7067                                         return null;
7068
7069                                 if ((lambda_parameters[i].ModFlags & Parameter.Modifier.RefOutMask) != (pr.Parameter.ModFlags & Parameter.Modifier.RefOutMask))
7070                                         return null;
7071                         }
7072
7073                         var emg = MethodGroup as ExtensionMethodGroupExpr;
7074                         if (emg != null) {
7075                                 var mg = MethodGroupExpr.CreatePredefined (candidate, candidate.DeclaringType, MethodGroup.Location);
7076                                 if (candidate.IsGeneric) {
7077                                         var targs = new TypeExpression [candidate.Arity];
7078                                         for (int i = 0; i < targs.Length; ++i) {
7079                                                 targs[i] = new TypeExpression (candidate.TypeArguments[i], MethodGroup.Location);
7080                                         }
7081
7082                                         mg.SetTypeArguments (null, new TypeArguments (targs));
7083                                 }
7084
7085                                 return mg;
7086                         }
7087
7088                         return MethodGroup;
7089                 }
7090
7091                 protected override void CloneTo (CloneContext clonectx, Expression t)
7092                 {
7093                         Invocation target = (Invocation) t;
7094
7095                         if (arguments != null)
7096                                 target.arguments = arguments.Clone (clonectx);
7097
7098                         target.expr = expr.Clone (clonectx);
7099                 }
7100
7101                 public override bool ContainsEmitWithAwait ()
7102                 {
7103                         if (arguments != null && arguments.ContainsEmitWithAwait ())
7104                                 return true;
7105
7106                         return mg.ContainsEmitWithAwait ();
7107                 }
7108
7109                 public override Expression CreateExpressionTree (ResolveContext ec)
7110                 {
7111                         Expression instance = mg.IsInstance ?
7112                                 mg.InstanceExpression.CreateExpressionTree (ec) :
7113                                 new NullLiteral (loc);
7114
7115                         var args = Arguments.CreateForExpressionTree (ec, arguments,
7116                                 instance,
7117                                 mg.CreateExpressionTree (ec));
7118
7119                         return CreateExpressionFactoryCall (ec, "Call", args);
7120                 }
7121
7122                 void ResolveConditionalAccessReceiver (ResolveContext rc)
7123                 {
7124                         if (!rc.HasSet (ResolveContext.Options.DontSetConditionalAccessReceiver) && expr.HasConditionalAccess ()) {
7125                                 conditional_access_receiver = true;
7126                         }
7127                 }
7128
7129                 bool statement_resolve;
7130                 public override ExpressionStatement ResolveStatement (BlockContext bc)
7131                 {
7132                         statement_resolve = true;
7133                         var es = base.ResolveStatement (bc);
7134                         statement_resolve = false;
7135
7136                         return es;
7137                 }
7138
7139                 protected override Expression DoResolve (ResolveContext rc)
7140                 {
7141                         ResolveConditionalAccessReceiver (rc);
7142                         return DoResolveInvocation (rc, null);
7143                 }
7144
7145                 public override Expression DoResolveLValue (ResolveContext rc, Expression right_side)
7146                 {
7147                         var sn = expr as SimpleName;
7148                         if (sn != null && sn.Name == "var" && sn.Arity == 0 && arguments?.Count > 1) {
7149                                 var targets = new List<Expression> (arguments.Count);
7150                                 var variables = new List<LocalVariable> (arguments.Count);
7151                                 foreach (var arg in arguments) {
7152                                         var arg_sn = arg.Expr as SimpleName;
7153                                         if (arg_sn == null || arg_sn.Arity != 0) {
7154                                                 rc.Report.Error (8199, loc, "The syntax `var (...)' as an lvalue is reserved");
7155                                                 return ErrorExpression.Instance;
7156                                         }
7157
7158                                         var lv = new LocalVariable (rc.CurrentBlock, arg_sn.Name, arg.Expr.Location);
7159                                         rc.CurrentBlock.AddLocalName (lv);
7160                                         variables.Add (lv);
7161
7162                                         targets.Add (new LocalVariableReference (lv, arg_sn.Location));
7163                                 }
7164
7165                                 var res = new TupleDeconstruct (targets, variables, right_side, loc);
7166                                 return res.Resolve (rc);
7167                         }
7168
7169                         if (right_side != null) {
7170                                 if (eclass != ExprClass.Unresolved)
7171                                         return this;
7172
7173                                 var res = DoResolveInvocation (rc, right_side);
7174                                 if (res == null)
7175                                         return null;
7176
7177                                 return res;
7178                         }
7179
7180                         return base.DoResolveLValue (rc, right_side);
7181                 }
7182
7183                 Expression DoResolveInvocation (ResolveContext ec, Expression rhs)
7184                 {
7185                         Expression member_expr;
7186                         var atn = expr as ATypeNameExpression;
7187
7188                         var flags = default (ResolveContext.FlagsHandle);
7189                         if (conditional_access_receiver)
7190                                 flags = ec.Set (ResolveContext.Options.DontSetConditionalAccessReceiver);
7191
7192                         if (atn != null) {
7193                                 member_expr = atn.LookupNameExpression (ec, MemberLookupRestrictions.InvocableOnly | MemberLookupRestrictions.ReadAccess);
7194                                 if (member_expr != null) {
7195                                         var name_of = member_expr as NameOf;
7196                                         if (name_of != null) {
7197                                                 return name_of.ResolveOverload (ec, arguments);
7198                                         }
7199
7200                                         member_expr = member_expr.Resolve (ec);
7201                                 }
7202                         } else {
7203                                 member_expr = expr.Resolve (ec);
7204                         }
7205
7206                         if (conditional_access_receiver)
7207                                 flags.Dispose ();
7208
7209                         if (member_expr == null)
7210                                 return null;
7211
7212                         //
7213                         // Next, evaluate all the expressions in the argument list
7214                         //
7215                         bool dynamic_arg = false;
7216                         if (arguments != null) {
7217                                 using (ec.With (ResolveContext.Options.DontSetConditionalAccessReceiver, false)) {
7218                                         arguments.Resolve (ec, out dynamic_arg);
7219                                 }
7220                         }
7221
7222                         TypeSpec expr_type = member_expr.Type;
7223                         if (expr_type.BuiltinType == BuiltinTypeSpec.Type.Dynamic)
7224                                 return DoResolveDynamic (ec, member_expr);
7225
7226                         mg = member_expr as MethodGroupExpr;
7227                         Expression invoke = null;
7228
7229                         if (mg == null) {
7230                                 if (expr_type != null && expr_type.IsDelegate) {
7231                                         invoke = new DelegateInvocation (member_expr, arguments, conditional_access_receiver, loc);
7232                                         invoke = invoke.Resolve (ec);
7233                                         if (invoke == null || !dynamic_arg)
7234                                                 return invoke;
7235                                 } else {
7236                                         if (member_expr is RuntimeValueExpression) {
7237                                                 ec.Report.Error (Report.RuntimeErrorId, loc, "Cannot invoke a non-delegate type `{0}'",
7238                                                         member_expr.Type.GetSignatureForError ());
7239                                                 return null;
7240                                         }
7241
7242                                         MemberExpr me = member_expr as MemberExpr;
7243                                         if (me == null) {
7244                                                 member_expr.Error_UnexpectedKind (ec, ResolveFlags.MethodGroup, loc);
7245                                                 return null;
7246                                         }
7247
7248                                         ec.Report.Error (1955, loc, "The member `{0}' cannot be used as method or delegate",
7249                                                         member_expr.GetSignatureForError ());
7250                                         return null;
7251                                 }
7252                         }
7253
7254                         if (invoke == null) {
7255                                 mg = DoResolveOverload (ec);
7256                                 if (mg == null)
7257                                         return null;
7258                         }
7259
7260                         if (dynamic_arg)
7261                                 return DoResolveDynamic (ec, member_expr);
7262
7263                         var method = mg.BestCandidate;
7264                         type = mg.BestCandidateReturnType;
7265                         if (conditional_access_receiver && !statement_resolve)
7266                                 type = LiftMemberType (ec, type);
7267
7268                         if (arguments == null && method.DeclaringType.BuiltinType == BuiltinTypeSpec.Type.Object && method.Name == Destructor.MetadataName) {
7269                                 if (mg.IsBase)
7270                                         ec.Report.Error (250, loc, "Do not directly call your base class Finalize method. It is called automatically from your destructor");
7271                                 else
7272                                         ec.Report.Error (245, loc, "Destructors and object.Finalize cannot be called directly. Consider calling IDisposable.Dispose if available");
7273                                 return null;
7274                         }
7275
7276                         IsSpecialMethodInvocation (ec, method, loc);
7277
7278                         eclass = ExprClass.Value;
7279
7280                         if (type.Kind == MemberKind.ByRef) {
7281                                 if (rhs == null && arguments?.ContainsEmitWithAwait () == true) {
7282                                         ec.Report.Error (8178, loc, "`await' cannot be used in an expression containing a call to `{0}' because it returns by reference",
7283                                                 GetSignatureForError ());
7284                                 }
7285
7286                                 if (rhs != EmptyExpression.OutAccess)
7287                                         return ByRefDereference.Create (this).Resolve (ec);
7288                         }
7289
7290                         return this;
7291                 }
7292
7293                 protected virtual Expression DoResolveDynamic (ResolveContext ec, Expression memberExpr)
7294                 {
7295                         Arguments args;
7296                         DynamicMemberBinder dmb = memberExpr as DynamicMemberBinder;
7297                         if (dmb != null) {
7298                                 args = dmb.Arguments;
7299                                 if (arguments != null)
7300                                         args.AddRange (arguments);
7301                         } else if (mg == null) {
7302                                 if (arguments == null)
7303                                         args = new Arguments (1);
7304                                 else
7305                                         args = arguments;
7306
7307                                 args.Insert (0, new Argument (memberExpr));
7308                                 this.expr = null;
7309                         } else {
7310                                 if (mg.IsBase) {
7311                                         ec.Report.Error (1971, loc,
7312                                                 "The base call to method `{0}' cannot be dynamically dispatched. Consider casting the dynamic arguments or eliminating the base access",
7313                                                 mg.Name);
7314                                         return null;
7315                                 }
7316
7317                                 if (arguments == null)
7318                                         args = new Arguments (1);
7319                                 else
7320                                         args = arguments;
7321
7322                                 MemberAccess ma = expr as MemberAccess;
7323                                 if (ma != null) {
7324                                         var inst = mg.InstanceExpression;
7325                                         var left_type = inst as TypeExpr;
7326                                         if (left_type != null) {
7327                                                 args.Insert (0, new Argument (new TypeOf (left_type.Type, loc).Resolve (ec), Argument.AType.DynamicTypeName));
7328                                         } else if (inst != null) {
7329                                                 //
7330                                                 // Any value type has to be pass as by-ref to get back the same
7331                                                 // instance on which the member was called
7332                                                 //
7333                                                 var mod = inst is IMemoryLocation && TypeSpec.IsValueType (inst.Type) ?
7334                                                         Argument.AType.Ref : Argument.AType.None;
7335                                                 args.Insert (0, new Argument (inst.Resolve (ec), mod));
7336                                         }
7337                                 } else {        // is SimpleName
7338                                         if (ec.IsStatic || ec.HasAny (ResolveContext.Options.FieldInitializerScope | ResolveContext.Options.BaseInitializer)) {
7339                                                 args.Insert (0, new Argument (new TypeOf (ec.CurrentType, loc).Resolve (ec), Argument.AType.DynamicTypeName));
7340                                         } else {
7341                                                 args.Insert (0, new Argument (new This (loc).Resolve (ec)));
7342                                         }
7343                                 }
7344                         }
7345
7346                         return new DynamicInvocation (expr as ATypeNameExpression, args, conditional_access_receiver, loc).Resolve (ec);
7347                 }
7348
7349                 protected virtual MethodGroupExpr DoResolveOverload (ResolveContext ec)
7350                 {
7351                         return mg.OverloadResolve (ec, ref arguments, null, OverloadResolver.Restrictions.None);
7352                 }
7353
7354                 public override void FlowAnalysis (FlowAnalysisContext fc)
7355                 {
7356                         if (mg.IsConditionallyExcluded)
7357                                 return;
7358
7359                         var da = conditional_access_receiver ? fc.BranchDefiniteAssignment () : null;
7360
7361                         mg.FlowAnalysis (fc);
7362
7363                         if (arguments != null)
7364                                 arguments.FlowAnalysis (fc);
7365
7366                         if (conditional_access_receiver)
7367                                 fc.DefiniteAssignment = da;
7368                 }
7369
7370                 public override string GetSignatureForError ()
7371                 {
7372                         return mg.GetSignatureForError ();
7373                 }
7374
7375                 public override bool HasConditionalAccess ()
7376                 {
7377                         return expr.HasConditionalAccess ();
7378                 }
7379
7380                 //
7381                 // If a member is a method or event, or if it is a constant, field or property of either a delegate type
7382                 // or the type dynamic, then the member is invocable
7383                 //
7384                 public static bool IsMemberInvocable (MemberSpec member)
7385                 {
7386                         switch (member.Kind) {
7387                         case MemberKind.Event:
7388                                 return true;
7389                         case MemberKind.Field:
7390                         case MemberKind.Property:
7391                                 var m = member as IInterfaceMemberSpec;
7392                                 return m.MemberType.IsDelegate || m.MemberType.BuiltinType == BuiltinTypeSpec.Type.Dynamic;
7393                         default:
7394                                 return false;
7395                         }
7396                 }
7397
7398                 public static bool IsSpecialMethodInvocation (ResolveContext ec, MethodSpec method, Location loc)
7399                 {
7400                         if (!method.IsReservedMethod)
7401                                 return false;
7402
7403                         if (ec.HasSet (ResolveContext.Options.InvokeSpecialName) || ec.CurrentMemberDefinition.IsCompilerGenerated)
7404                                 return false;
7405
7406                         ec.Report.SymbolRelatedToPreviousError (method);
7407                         ec.Report.Error (571, loc, "`{0}': cannot explicitly call operator or accessor",
7408                                 method.GetSignatureForError ());
7409
7410                         return true;
7411                 }
7412
7413                 public override void Emit (EmitContext ec)
7414                 {
7415                         if (mg.IsConditionallyExcluded)
7416                                 return;
7417
7418                         if (conditional_access_receiver)
7419                                 mg.EmitCall (ec, arguments, type, false);
7420                         else
7421                                 mg.EmitCall (ec, arguments, false);
7422                 }
7423
7424                 public override void EmitPrepare (EmitContext ec)
7425                 {
7426                         mg.EmitPrepare (ec);
7427
7428                         arguments?.EmitPrepare (ec);
7429                 }
7430
7431                 public override void EmitStatement (EmitContext ec)
7432                 {
7433                         if (mg.IsConditionallyExcluded)
7434                                 return;
7435
7436                         if (conditional_access_receiver)
7437                                 mg.EmitCall (ec, arguments, type, true);
7438                         else
7439                                 mg.EmitCall (ec, arguments, true);
7440                 }
7441
7442                 public override SLE.Expression MakeExpression (BuilderContext ctx)
7443                 {
7444                         return MakeExpression (ctx, mg.InstanceExpression, mg.BestCandidate, arguments);
7445                 }
7446
7447                 public static SLE.Expression MakeExpression (BuilderContext ctx, Expression instance, MethodSpec mi, Arguments args)
7448                 {
7449 #if STATIC
7450                         throw new NotSupportedException ();
7451 #else
7452                         var instance_expr = instance == null ? null : instance.MakeExpression (ctx);
7453                         return SLE.Expression.Call (instance_expr, (MethodInfo) mi.GetMetaInfo (), Arguments.MakeExpression (args, ctx));
7454 #endif
7455                 }
7456
7457                 public override object Accept (StructuralVisitor visitor)
7458                 {
7459                         return visitor.Visit (this);
7460                 }
7461         }
7462
7463         //
7464         // Implements simple new expression
7465         //
7466         public class New : ExpressionStatement, IMemoryLocation
7467         {
7468                 protected Arguments arguments;
7469
7470                 //
7471                 // During bootstrap, it contains the RequestedType,
7472                 // but if `type' is not null, it *might* contain a NewDelegate
7473                 // (because of field multi-initialization)
7474                 //
7475                 protected Expression RequestedType;
7476
7477                 protected MethodSpec method;
7478
7479                 public New (Expression requested_type, Arguments arguments, Location l)
7480                 {
7481                         RequestedType = requested_type;
7482                         this.arguments = arguments;
7483                         loc = l;
7484                 }
7485
7486                 #region Properties
7487                 public Arguments Arguments {
7488                         get {
7489                                 return arguments;
7490                         }
7491                 }
7492
7493                 //
7494                 // Returns true for resolved `new S()' when S does not declare parameterless constructor
7495                 //
7496                 public bool IsGeneratedStructConstructor {
7497                         get {
7498                                 return arguments == null && method == null && type.IsStruct && GetType () == typeof (New);
7499                         }
7500                 }
7501
7502                 public Expression TypeExpression {
7503                         get {
7504                                 return RequestedType;
7505                         }
7506                 }
7507
7508                 #endregion
7509
7510                 /// <summary>
7511                 /// Converts complex core type syntax like 'new int ()' to simple constant
7512                 /// </summary>
7513                 public static Constant Constantify (TypeSpec t, Location loc)
7514                 {
7515                         switch (t.BuiltinType) {
7516                         case BuiltinTypeSpec.Type.Int:
7517                                 return new IntConstant (t, 0, loc);
7518                         case BuiltinTypeSpec.Type.UInt:
7519                                 return new UIntConstant (t, 0, loc);
7520                         case BuiltinTypeSpec.Type.Long:
7521                                 return new LongConstant (t, 0, loc);
7522                         case BuiltinTypeSpec.Type.ULong:
7523                                 return new ULongConstant (t, 0, loc);
7524                         case BuiltinTypeSpec.Type.Float:
7525                                 return new FloatConstant (t, 0, loc);
7526                         case BuiltinTypeSpec.Type.Double:
7527                                 return new DoubleConstant (t, 0, loc);
7528                         case BuiltinTypeSpec.Type.Short:
7529                                 return new ShortConstant (t, 0, loc);
7530                         case BuiltinTypeSpec.Type.UShort:
7531                                 return new UShortConstant (t, 0, loc);
7532                         case BuiltinTypeSpec.Type.SByte:
7533                                 return new SByteConstant (t, 0, loc);
7534                         case BuiltinTypeSpec.Type.Byte:
7535                                 return new ByteConstant (t, 0, loc);
7536                         case BuiltinTypeSpec.Type.Char:
7537                                 return new CharConstant (t, '\0', loc);
7538                         case BuiltinTypeSpec.Type.Bool:
7539                                 return new BoolConstant (t, false, loc);
7540                         case BuiltinTypeSpec.Type.Decimal:
7541                                 return new DecimalConstant (t, 0, loc);
7542                         }
7543
7544                         if (t.IsEnum)
7545                                 return new EnumConstant (Constantify (EnumSpec.GetUnderlyingType (t), loc), t);
7546
7547                         if (t.IsNullableType)
7548                                 return Nullable.LiftedNull.Create (t, loc);
7549
7550                         return null;
7551                 }
7552
7553                 public override bool ContainsEmitWithAwait ()
7554                 {
7555                         return arguments != null && arguments.ContainsEmitWithAwait ();
7556                 }
7557
7558                 //
7559                 // Checks whether the type is an interface that has the
7560                 // [ComImport, CoClass] attributes and must be treated
7561                 // specially
7562                 //
7563                 public Expression CheckComImport (ResolveContext ec)
7564                 {
7565                         if (!type.IsInterface)
7566                                 return null;
7567
7568                         //
7569                         // Turn the call into:
7570                         // (the-interface-stated) (new class-referenced-in-coclassattribute ())
7571                         //
7572                         var real_class = type.MemberDefinition.GetAttributeCoClass ();
7573                         if (real_class == null)
7574                                 return null;
7575
7576                         New proxy = new New (new TypeExpression (real_class, loc), arguments, loc);
7577                         Cast cast = new Cast (new TypeExpression (type, loc), proxy, loc);
7578                         return cast.Resolve (ec);
7579                 }
7580
7581                 public override Expression CreateExpressionTree (ResolveContext ec)
7582                 {
7583                         Arguments args;
7584                         if (method == null) {
7585                                 args = new Arguments (1);
7586                                 args.Add (new Argument (new TypeOf (type, loc)));
7587                         } else {
7588                                 args = Arguments.CreateForExpressionTree (ec,
7589                                         arguments, new TypeOfMethod (method, loc));
7590                         }
7591
7592                         return CreateExpressionFactoryCall (ec, "New", args);
7593                 }
7594
7595                 protected override Expression DoResolve (ResolveContext ec)
7596                 {
7597                         if (RequestedType is TupleTypeExpr) {
7598                                 ec.Report.Error (8181, loc, "Tuple type cannot be used in an object creation expression. Use a tuple literal expression instead.");
7599                         }
7600
7601                         type = RequestedType.ResolveAsType (ec);
7602                         if (type == null)
7603                                 return null;
7604
7605                         eclass = ExprClass.Value;
7606
7607                         if (type.IsPointer) {
7608                                 ec.Report.Error (1919, loc, "Unsafe type `{0}' cannot be used in an object creation expression",
7609                                         type.GetSignatureForError ());
7610                                 return null;
7611                         }
7612
7613                         if (arguments == null) {
7614                                 Constant c = Constantify (type, RequestedType.Location);
7615                                 if (c != null)
7616                                         return ReducedExpression.Create (c, this);
7617                         }
7618
7619                         if (type.IsDelegate) {
7620                                 return (new NewDelegate (type, arguments, loc)).Resolve (ec);
7621                         }
7622
7623                         var tparam = type as TypeParameterSpec;
7624                         if (tparam != null) {
7625                                 //
7626                                 // Check whether the type of type parameter can be constructed. BaseType can be a struct for method overrides
7627                                 // where type parameter constraint is inflated to struct
7628                                 //
7629                                 if ((tparam.SpecialConstraint & (SpecialConstraint.Struct | SpecialConstraint.Constructor)) == 0 && !TypeSpec.IsValueType (tparam)) {
7630                                         ec.Report.Error (304, loc,
7631                                                 "Cannot create an instance of the variable type `{0}' because it does not have the new() constraint",
7632                                                 type.GetSignatureForError ());
7633                                 }
7634
7635                                 if ((arguments != null) && (arguments.Count != 0)) {
7636                                         ec.Report.Error (417, loc,
7637                                                 "`{0}': cannot provide arguments when creating an instance of a variable type",
7638                                                 type.GetSignatureForError ());
7639                                 }
7640
7641                                 return this;
7642                         }
7643
7644                         if (type.IsStatic) {
7645                                 ec.Report.SymbolRelatedToPreviousError (type);
7646                                 ec.Report.Error (712, loc, "Cannot create an instance of the static class `{0}'", type.GetSignatureForError ());
7647                                 return null;
7648                         }
7649
7650                         if (type.IsInterface || type.IsAbstract){
7651                                 if (!TypeManager.IsGenericType (type)) {
7652                                         RequestedType = CheckComImport (ec);
7653                                         if (RequestedType != null)
7654                                                 return RequestedType;
7655                                 }
7656
7657                                 ec.Report.SymbolRelatedToPreviousError (type);
7658                                 ec.Report.Error (144, loc, "Cannot create an instance of the abstract class or interface `{0}'", type.GetSignatureForError ());
7659                                 return null;
7660                         }
7661
7662                         bool dynamic;
7663                         if (arguments != null) {
7664                                 arguments.Resolve (ec, out dynamic);
7665                         } else {
7666                                 dynamic = false;
7667                         }
7668
7669                         method = ConstructorLookup (ec, type, ref arguments, loc);
7670
7671                         if (dynamic) {
7672                                 arguments.Insert (0, new Argument (new TypeOf (type, loc).Resolve (ec), Argument.AType.DynamicTypeName));
7673                                 return new DynamicConstructorBinder (type, arguments, loc).Resolve (ec);
7674                         }
7675
7676                         return this;
7677                 }
7678
7679                 void DoEmitTypeParameter (EmitContext ec)
7680                 {
7681                         var m = ec.Module.PredefinedMembers.ActivatorCreateInstance.Resolve (loc);
7682                         if (m == null)
7683                                 return;
7684
7685                         var ctor_factory = m.MakeGenericMethod (ec.MemberContext, type);
7686                         ec.Emit (OpCodes.Call, ctor_factory);
7687                 }
7688
7689                 //
7690                 // This Emit can be invoked in two contexts:
7691                 //    * As a mechanism that will leave a value on the stack (new object)
7692                 //    * As one that wont (init struct)
7693                 //
7694                 // If we are dealing with a ValueType, we have a few
7695                 // situations to deal with:
7696                 //
7697                 //    * The target is a ValueType, and we have been provided
7698                 //      the instance (this is easy, we are being assigned).
7699                 //
7700                 //    * The target of New is being passed as an argument,
7701                 //      to a boxing operation or a function that takes a
7702                 //      ValueType.
7703                 //
7704                 //      In this case, we need to create a temporary variable
7705                 //      that is the argument of New.
7706                 //
7707                 // Returns whether a value is left on the stack
7708                 //
7709                 // *** Implementation note ***
7710                 //
7711                 // To benefit from this optimization, each assignable expression
7712                 // has to manually cast to New and call this Emit.
7713                 //
7714                 // TODO: It's worth to implement it for arrays and fields
7715                 //
7716                 public virtual bool Emit (EmitContext ec, IMemoryLocation target)
7717                 {
7718                         bool is_value_type = type.IsStructOrEnum;
7719                         VariableReference vr = target as VariableReference;
7720
7721                         bool prepare_await = ec.HasSet (BuilderContext.Options.AsyncBody) && arguments?.ContainsEmitWithAwait () == true;
7722
7723                         if (target != null && is_value_type && (vr != null || method == null)) {
7724                                 if (prepare_await) {
7725                                         arguments = arguments.Emit (ec, false, true);
7726                                         prepare_await = false;
7727                                 }
7728
7729                                 target.AddressOf (ec, AddressOp.Store);
7730                         } else if (vr != null && vr.IsRef) {
7731                                 vr.EmitLoad (ec);
7732                         }
7733
7734                         if (arguments != null) {
7735                                 if (prepare_await)
7736                                         arguments = arguments.Emit (ec, false, true);
7737
7738                                 arguments.Emit (ec);
7739                         }
7740
7741                         if (is_value_type) {
7742                                 if (method == null) {
7743                                         ec.Emit (OpCodes.Initobj, type);
7744                                         return false;
7745                                 }
7746
7747                                 if (vr != null) {
7748                                         ec.MarkCallEntry (loc);
7749                                         ec.Emit (OpCodes.Call, method);
7750                                         return false;
7751                                 }
7752                         }
7753
7754                         if (type is TypeParameterSpec) {
7755                                 DoEmitTypeParameter (ec);
7756                                 return true;
7757                         }
7758
7759                         ec.MarkCallEntry (loc);
7760                         ec.Emit (OpCodes.Newobj, method);
7761                         return true;
7762                 }
7763
7764                 public override void Emit (EmitContext ec)
7765                 {
7766                         LocalTemporary v = null;
7767                         if (method == null && type.IsStructOrEnum) {
7768                                 // TODO: Use temporary variable from pool
7769                                 v = new LocalTemporary (type);
7770                         }
7771
7772                         if (!Emit (ec, v))
7773                                 v.Emit (ec);
7774                 }
7775
7776                 public override void EmitStatement (EmitContext ec)
7777                 {
7778                         LocalTemporary v = null;
7779                         if (method == null && TypeSpec.IsValueType (type)) {
7780                                 // TODO: Use temporary variable from pool
7781                                 v = new LocalTemporary (type);
7782                         }
7783
7784                         if (Emit (ec, v))
7785                                 ec.Emit (OpCodes.Pop);
7786                 }
7787
7788                 public virtual bool CanEmitOptimizedLocalTarget (EmitContext ec)
7789                 {
7790                         return true;
7791                 }
7792
7793                 public override void FlowAnalysis (FlowAnalysisContext fc)
7794                 {
7795                         if (arguments != null)
7796                                 arguments.FlowAnalysis (fc);
7797                 }
7798
7799                 public void AddressOf (EmitContext ec, AddressOp mode)
7800                 {
7801                         EmitAddressOf (ec, mode);
7802                 }
7803
7804                 protected virtual IMemoryLocation EmitAddressOf (EmitContext ec, AddressOp mode)
7805                 {
7806                         LocalTemporary value_target = new LocalTemporary (type);
7807
7808                         if (type is TypeParameterSpec) {
7809                                 DoEmitTypeParameter (ec);
7810                                 value_target.Store (ec);
7811                                 value_target.AddressOf (ec, mode);
7812                                 return value_target;
7813                         }
7814
7815                         value_target.AddressOf (ec, AddressOp.Store);
7816
7817                         if (method == null) {
7818                                 ec.Emit (OpCodes.Initobj, type);
7819                         } else {
7820                                 if (arguments != null)
7821                                         arguments.Emit (ec);
7822
7823                                 ec.Emit (OpCodes.Call, method);
7824                         }
7825
7826                         value_target.AddressOf (ec, mode);
7827                         return value_target;
7828                 }
7829
7830                 protected override void CloneTo (CloneContext clonectx, Expression t)
7831                 {
7832                         New target = (New) t;
7833
7834                         target.RequestedType = RequestedType.Clone (clonectx);
7835                         if (arguments != null){
7836                                 target.arguments = arguments.Clone (clonectx);
7837                         }
7838                 }
7839
7840                 public override SLE.Expression MakeExpression (BuilderContext ctx)
7841                 {
7842 #if STATIC
7843                         return base.MakeExpression (ctx);
7844 #else
7845                         return SLE.Expression.New ((ConstructorInfo) method.GetMetaInfo (), Arguments.MakeExpression (arguments, ctx));
7846 #endif
7847                 }
7848
7849                 public override object Accept (StructuralVisitor visitor)
7850                 {
7851                         return visitor.Visit (this);
7852                 }
7853         }
7854
7855         //
7856         // Array initializer expression, the expression is allowed in
7857         // variable or field initialization only which makes it tricky as
7858         // the type has to be infered based on the context either from field
7859         // type or variable type (think of multiple declarators)
7860         //
7861         public class ArrayInitializer : Expression
7862         {
7863                 List<Expression> elements;
7864                 BlockVariable variable;
7865
7866                 public ArrayInitializer (List<Expression> init, Location loc)
7867                 {
7868                         elements = init;
7869                         this.loc = loc;
7870                 }
7871
7872                 public ArrayInitializer (int count, Location loc)
7873                         : this (new List<Expression> (count), loc)
7874                 {
7875                 }
7876
7877                 public ArrayInitializer (Location loc)
7878                         : this (4, loc)
7879                 {
7880                 }
7881
7882                 #region Properties
7883
7884                 public int Count {
7885                         get { return elements.Count; }
7886                 }
7887
7888                 public List<Expression> Elements {
7889                         get {
7890                                 return elements;
7891                         }
7892                 }
7893
7894                 public Expression this [int index] {
7895                         get {
7896                                 return elements [index];
7897                         }
7898                 }
7899
7900                 public BlockVariable VariableDeclaration {
7901                         get {
7902                                 return variable;
7903                         }
7904                         set {
7905                                 variable = value;
7906                         }
7907                 }
7908
7909                 #endregion
7910
7911                 public void Add (Expression expr)
7912                 {
7913                         elements.Add (expr);
7914                 }
7915
7916                 public override bool ContainsEmitWithAwait ()
7917                 {
7918                         throw new NotSupportedException ();
7919                 }
7920
7921                 public override Expression CreateExpressionTree (ResolveContext ec)
7922                 {
7923                         throw new NotSupportedException ("ET");
7924                 }
7925
7926                 protected override void CloneTo (CloneContext clonectx, Expression t)
7927                 {
7928                         var target = (ArrayInitializer) t;
7929
7930                         target.elements = new List<Expression> (elements.Count);
7931                         foreach (var element in elements)
7932                                 target.elements.Add (element.Clone (clonectx));
7933                 }
7934
7935                 protected override Expression DoResolve (ResolveContext rc)
7936                 {
7937                         var current_field = rc.CurrentMemberDefinition as FieldBase;
7938                         TypeExpression type;
7939                         if (current_field != null && rc.CurrentAnonymousMethod == null) {
7940                                 type = new TypeExpression (current_field.MemberType, current_field.Location);
7941                         } else if (variable != null) {
7942                                 if (variable.TypeExpression is VarExpr) {
7943                                         rc.Report.Error (820, loc, "An implicitly typed local variable declarator cannot use an array initializer");
7944                                         return EmptyExpression.Null;
7945                                 }
7946
7947                                 type = new TypeExpression (variable.Variable.Type, variable.Variable.Location);
7948                         } else {
7949                                 throw new NotImplementedException ("Unexpected array initializer context");
7950                         }
7951
7952                         return new ArrayCreation (type, this).Resolve (rc);
7953                 }
7954
7955                 public override void Emit (EmitContext ec)
7956                 {
7957                         throw new InternalErrorException ("Missing Resolve call");
7958                 }
7959
7960                 public override void FlowAnalysis (FlowAnalysisContext fc)
7961                 {
7962                         throw new InternalErrorException ("Missing Resolve call");
7963                 }
7964
7965                 public override object Accept (StructuralVisitor visitor)
7966                 {
7967                         return visitor.Visit (this);
7968                 }
7969         }
7970
7971         /// <summary>
7972         ///   14.5.10.2: Represents an array creation expression.
7973         /// </summary>
7974         ///
7975         /// <remarks>
7976         ///   There are two possible scenarios here: one is an array creation
7977         ///   expression that specifies the dimensions and optionally the
7978         ///   initialization data and the other which does not need dimensions
7979         ///   specified but where initialization data is mandatory.
7980         /// </remarks>
7981         public class ArrayCreation : Expression
7982         {
7983                 FullNamedExpression requested_base_type;
7984                 ArrayInitializer initializers;
7985
7986                 //
7987                 // The list of Argument types.
7988                 // This is used to construct the `newarray' or constructor signature
7989                 //
7990                 protected List<Expression> arguments;
7991
7992                 protected TypeSpec array_element_type;
7993                 int num_arguments;
7994                 protected int dimensions;
7995                 protected readonly ComposedTypeSpecifier rank;
7996                 Expression first_emit;
7997                 LocalTemporary first_emit_temp;
7998
7999                 protected List<Expression> array_data;
8000
8001                 Dictionary<int, int> bounds;
8002
8003 #if STATIC
8004                 // The number of constants in array initializers
8005                 int const_initializers_count;
8006                 bool only_constant_initializers;
8007 #endif
8008                 public ArrayCreation (FullNamedExpression requested_base_type, List<Expression> exprs, ComposedTypeSpecifier rank, ArrayInitializer initializers, Location l)
8009                         : this (requested_base_type, rank, initializers, l)
8010                 {
8011                         arguments = new List<Expression> (exprs);
8012                         num_arguments = arguments.Count;
8013                 }
8014
8015                 //
8016                 // For expressions like int[] foo = new int[] { 1, 2, 3 };
8017                 //
8018                 public ArrayCreation (FullNamedExpression requested_base_type, ComposedTypeSpecifier rank, ArrayInitializer initializers, Location loc)
8019                 {
8020                         this.requested_base_type = requested_base_type;
8021                         this.rank = rank;
8022                         this.initializers = initializers;
8023                         this.loc = loc;
8024
8025                         if (rank != null)
8026                                 num_arguments = rank.Dimension;
8027                 }
8028
8029                 //
8030                 // For compiler generated single dimensional arrays only
8031                 //
8032                 public ArrayCreation (FullNamedExpression requested_base_type, ArrayInitializer initializers, Location loc)
8033                         : this (requested_base_type, ComposedTypeSpecifier.SingleDimension, initializers, loc)
8034                 {
8035                 }
8036
8037                 //
8038                 // For expressions like int[] foo = { 1, 2, 3 };
8039                 //
8040                 public ArrayCreation (FullNamedExpression requested_base_type, ArrayInitializer initializers)
8041                         : this (requested_base_type, null, initializers, initializers.Location)
8042                 {
8043                 }
8044
8045                 public bool NoEmptyInterpolation { get; set; }
8046
8047                 public ComposedTypeSpecifier Rank {
8048                         get {
8049                                 return this.rank;
8050                         }
8051                 }
8052
8053                 public FullNamedExpression TypeExpression {
8054                         get {
8055                                 return this.requested_base_type;
8056                         }
8057                 }
8058
8059                 public ArrayInitializer Initializers {
8060                         get {
8061                                 return this.initializers;
8062                         }
8063                 }
8064
8065                 bool CheckIndices (ResolveContext ec, ArrayInitializer probe, int idx, bool specified_dims, int child_bounds)
8066                 {
8067                         if (initializers != null && bounds == null) {
8068                                 //
8069                                 // We use this to store all the data values in the order in which we
8070                                 // will need to store them in the byte blob later
8071                                 //
8072                                 array_data = new List<Expression> (probe.Count);
8073                                 bounds = new Dictionary<int, int> ();
8074                         }
8075
8076                         if (specified_dims) {
8077                                 Expression a = arguments [idx];
8078                                 a = a.Resolve (ec);
8079                                 if (a == null)
8080                                         return false;
8081
8082                                 a = ConvertExpressionToArrayIndex (ec, a);
8083                                 if (a == null)
8084                                         return false;
8085
8086                                 arguments[idx] = a;
8087
8088                                 if (initializers != null) {
8089                                         Constant c = a as Constant;
8090                                         if (c == null && a is ArrayIndexCast)
8091                                                 c = ((ArrayIndexCast) a).Child as Constant;
8092
8093                                         if (c == null) {
8094                                                 ec.Report.Error (150, a.Location, "A constant value is expected");
8095                                                 return false;
8096                                         }
8097
8098                                         int value;
8099                                         try {
8100                                                 value = System.Convert.ToInt32 (c.GetValue ());
8101                                         } catch {
8102                                                 ec.Report.Error (150, a.Location, "A constant value is expected");
8103                                                 return false;
8104                                         }
8105
8106                                         // TODO: probe.Count does not fit ulong in
8107                                         if (value != probe.Count) {
8108                                                 ec.Report.Error (847, loc, "An array initializer of length `{0}' was expected", value.ToString ());
8109                                                 return false;
8110                                         }
8111
8112                                         bounds[idx] = value;
8113                                 }
8114                         }
8115
8116                         if (initializers == null)
8117                                 return true;
8118
8119                         for (int i = 0; i < probe.Count; ++i) {
8120                                 var o = probe [i];
8121                                 if (o is ArrayInitializer) {
8122                                         var sub_probe = o as ArrayInitializer;
8123                                         if (idx + 1 >= dimensions){
8124                                                 ec.Report.Error (623, loc, "Array initializers can only be used in a variable or field initializer. Try using a new expression instead");
8125                                                 return false;
8126                                         }
8127
8128                                         // When we don't have explicitly specified dimensions, record whatever dimension we first encounter at each level
8129                                         if (!bounds.ContainsKey(idx + 1))
8130                                                 bounds[idx + 1] = sub_probe.Count;
8131
8132                                         if (bounds[idx + 1] != sub_probe.Count) {
8133                                                 ec.Report.Error(847, sub_probe.Location, "An array initializer of length `{0}' was expected", bounds[idx + 1].ToString());
8134                                                 return false;
8135                                         }
8136
8137                                         bool ret = CheckIndices (ec, sub_probe, idx + 1, specified_dims, child_bounds - 1);
8138                                         if (!ret)
8139                                                 return false;
8140                                 } else if (child_bounds > 1) {
8141                                         ec.Report.Error (846, o.Location, "A nested array initializer was expected");
8142                                 } else {
8143                                         Expression element = ResolveArrayElement (ec, o);
8144                                         if (element == null)
8145                                                 continue;
8146 #if STATIC
8147                                         // Initializers with the default values can be ignored
8148                                         Constant c = element as Constant;
8149                                         if (c != null) {
8150                                                 if (!c.IsDefaultInitializer (array_element_type)) {
8151                                                         ++const_initializers_count;
8152                                                 }
8153                                         } else {
8154                                                 only_constant_initializers = false;
8155                                         }
8156 #endif
8157                                         array_data.Add (element);
8158                                 }
8159                         }
8160
8161                         return true;
8162                 }
8163
8164                 public override bool ContainsEmitWithAwait ()
8165                 {
8166                         foreach (var arg in arguments) {
8167                                 if (arg.ContainsEmitWithAwait ())
8168                                         return true;
8169                         }
8170
8171                         return InitializersContainAwait ();
8172                 }
8173
8174                 public override Expression CreateExpressionTree (ResolveContext ec)
8175                 {
8176                         Arguments args;
8177
8178                         if (array_data == null) {
8179                                 args = new Arguments (arguments.Count + 1);
8180                                 args.Add (new Argument (new TypeOf (array_element_type, loc)));
8181                                 foreach (Expression a in arguments)
8182                                         args.Add (new Argument (a.CreateExpressionTree (ec)));
8183
8184                                 return CreateExpressionFactoryCall (ec, "NewArrayBounds", args);
8185                         }
8186
8187                         if (dimensions > 1) {
8188                                 ec.Report.Error (838, loc, "An expression tree cannot contain a multidimensional array initializer");
8189                                 return null;
8190                         }
8191
8192                         args = new Arguments (array_data == null ? 1 : array_data.Count + 1);
8193                         args.Add (new Argument (new TypeOf (array_element_type, loc)));
8194                         if (array_data != null) {
8195                                 for (int i = 0; i < array_data.Count; ++i) {
8196                                         Expression e = array_data [i];
8197                                         args.Add (new Argument (e.CreateExpressionTree (ec)));
8198                                 }
8199                         }
8200
8201                         return CreateExpressionFactoryCall (ec, "NewArrayInit", args);
8202                 }
8203
8204                 void UpdateIndices (ResolveContext rc)
8205                 {
8206                         int i = 0;
8207                         for (var probe = initializers; probe != null;) {
8208                                 Expression e = new IntConstant (rc.BuiltinTypes, probe.Count, Location.Null);
8209                                 arguments.Add (e);
8210                                 bounds[i++] = probe.Count;
8211
8212                                 if (probe.Count > 0 && probe [0] is ArrayInitializer) {
8213                                         probe = (ArrayInitializer) probe[0];
8214                                 } else if (dimensions > i) {
8215                                         continue;
8216                                 } else {
8217                                         return;
8218                                 }
8219                         }
8220                 }
8221
8222                 protected override void Error_NegativeArrayIndex (ResolveContext ec, Location loc)
8223                 {
8224                         ec.Report.Error (248, loc, "Cannot create an array with a negative size");
8225                 }
8226
8227                 public override void FlowAnalysis (FlowAnalysisContext fc)
8228                 {
8229                         foreach (var arg in arguments)
8230                                 arg.FlowAnalysis (fc);
8231
8232                         if (array_data != null) {
8233                                 foreach (var ad in array_data)
8234                                         ad.FlowAnalysis (fc);
8235                         }
8236                 }
8237
8238                 bool InitializersContainAwait ()
8239                 {
8240                         if (array_data == null)
8241                                 return false;
8242
8243                         foreach (var expr in array_data) {
8244                                 if (expr.ContainsEmitWithAwait ())
8245                                         return true;
8246                         }
8247
8248                         return false;
8249                 }
8250
8251                 protected virtual Expression ResolveArrayElement (ResolveContext ec, Expression element)
8252                 {
8253                         element = element.Resolve (ec);
8254                         if (element == null)
8255                                 return null;
8256
8257                         var te = element as CompoundAssign.TargetExpression;
8258                         if (te != null) {
8259                                 for (int i = 1; i < initializers.Count; ++i) {
8260                                         if (initializers [i].ContainsEmitWithAwait ()) {
8261                                                 te.RequiresEmitWithAwait = true;
8262                                                 break;
8263                                         }
8264                                 }
8265
8266                                 if (!te.RequiresEmitWithAwait) {
8267                                         if (first_emit != null)
8268                                                 throw new InternalErrorException ("Can only handle one mutator at a time");
8269                                         first_emit = element;
8270                                         element = first_emit_temp = new LocalTemporary (element.Type);
8271                                 }
8272                         }
8273
8274                         return Convert.ImplicitConversionRequired (
8275                                 ec, element, array_element_type, loc);
8276                 }
8277
8278                 protected bool ResolveInitializers (ResolveContext ec)
8279                 {
8280 #if STATIC
8281                         only_constant_initializers = true;
8282 #endif
8283
8284                         if (arguments != null) {
8285                                 bool res = true;
8286                                 for (int i = 0; i < arguments.Count; ++i) {
8287                                         res &= CheckIndices (ec, initializers, i, true, dimensions);
8288                                         if (initializers != null)
8289                                                 break;
8290                                 }
8291
8292                                 return res;
8293                         }
8294
8295                         arguments = new List<Expression> ();
8296
8297                         if (!CheckIndices (ec, initializers, 0, false, dimensions))
8298                                 return false;
8299
8300                         UpdateIndices (ec);
8301
8302                         return true;
8303                 }
8304
8305                 //
8306                 // Resolved the type of the array
8307                 //
8308                 bool ResolveArrayType (ResolveContext ec)
8309                 {
8310                         //
8311                         // Lookup the type
8312                         //
8313                         FullNamedExpression array_type_expr;
8314                         if (num_arguments > 0) {
8315                                 array_type_expr = new ComposedCast (requested_base_type, rank);
8316                         } else {
8317                                 array_type_expr = requested_base_type;
8318                         }
8319
8320                         type = array_type_expr.ResolveAsType (ec);
8321                         if (array_type_expr == null)
8322                                 return false;
8323
8324                         var ac = type as ArrayContainer;
8325                         if (ac == null) {
8326                                 ec.Report.Error (622, loc, "Can only use array initializer expressions to assign to array types. Try using a new expression instead");
8327                                 return false;
8328                         }
8329
8330                         array_element_type = ac.Element;
8331                         dimensions = ac.Rank;
8332
8333                         return true;
8334                 }
8335
8336                 protected override Expression DoResolve (ResolveContext ec)
8337                 {
8338                         if (type != null)
8339                                 return this;
8340
8341                         if (!ResolveArrayType (ec))
8342                                 return null;
8343
8344                         //
8345                         // validate the initializers and fill in any missing bits
8346                         //
8347                         if (!ResolveInitializers (ec))
8348                                 return null;
8349
8350                         eclass = ExprClass.Value;
8351                         return this;
8352                 }
8353
8354                 byte [] MakeByteBlob ()
8355                 {
8356                         int factor;
8357                         byte [] data;
8358                         byte [] element;
8359                         int count = array_data.Count;
8360
8361                         TypeSpec element_type = array_element_type;
8362                         if (element_type.IsEnum)
8363                                 element_type = EnumSpec.GetUnderlyingType (element_type);
8364
8365                         factor = BuiltinTypeSpec.GetSize (element_type);
8366                         if (factor == 0)
8367                                 throw new Exception ("unrecognized type in MakeByteBlob: " + element_type);
8368
8369                         data = new byte [(count * factor + 3) & ~3];
8370                         int idx = 0;
8371
8372                         for (int i = 0; i < count; ++i) {
8373                                 var c = array_data[i] as Constant;
8374                                 if (c == null) {
8375                                         idx += factor;
8376                                         continue;
8377                                 }
8378
8379                                 object v = c.GetValue ();
8380
8381                                 switch (element_type.BuiltinType) {
8382                                 case BuiltinTypeSpec.Type.Long:
8383                                         long lval = (long) v;
8384
8385                                         for (int j = 0; j < factor; ++j) {
8386                                                 data[idx + j] = (byte) (lval & 0xFF);
8387                                                 lval = (lval >> 8);
8388                                         }
8389                                         break;
8390                                 case BuiltinTypeSpec.Type.ULong:
8391                                         ulong ulval = (ulong) v;
8392
8393                                         for (int j = 0; j < factor; ++j) {
8394                                                 data[idx + j] = (byte) (ulval & 0xFF);
8395                                                 ulval = (ulval >> 8);
8396                                         }
8397                                         break;
8398                                 case BuiltinTypeSpec.Type.Float:
8399                                         var fval = SingleConverter.SingleToInt32Bits((float) v);
8400
8401                                         data[idx] = (byte) (fval & 0xff);
8402                                         data[idx + 1] = (byte) ((fval >> 8) & 0xff);
8403                                         data[idx + 2] = (byte) ((fval >> 16) & 0xff);
8404                                         data[idx + 3] = (byte) (fval >> 24);
8405                                         break;
8406                                 case BuiltinTypeSpec.Type.Double:
8407                                         element = BitConverter.GetBytes ((double) v);
8408
8409                                         for (int j = 0; j < factor; ++j)
8410                                                 data[idx + j] = element[j];
8411
8412                                         // FIXME: Handle the ARM float format.
8413                                         if (!BitConverter.IsLittleEndian)
8414                                                 System.Array.Reverse (data, idx, 8);
8415                                         break;
8416                                 case BuiltinTypeSpec.Type.Char:
8417                                         int chval = (int) ((char) v);
8418
8419                                         data[idx] = (byte) (chval & 0xff);
8420                                         data[idx + 1] = (byte) (chval >> 8);
8421                                         break;
8422                                 case BuiltinTypeSpec.Type.Short:
8423                                         int sval = (int) ((short) v);
8424
8425                                         data[idx] = (byte) (sval & 0xff);
8426                                         data[idx + 1] = (byte) (sval >> 8);
8427                                         break;
8428                                 case BuiltinTypeSpec.Type.UShort:
8429                                         int usval = (int) ((ushort) v);
8430
8431                                         data[idx] = (byte) (usval & 0xff);
8432                                         data[idx + 1] = (byte) (usval >> 8);
8433                                         break;
8434                                 case BuiltinTypeSpec.Type.Int:
8435                                         int val = (int) v;
8436
8437                                         data[idx] = (byte) (val & 0xff);
8438                                         data[idx + 1] = (byte) ((val >> 8) & 0xff);
8439                                         data[idx + 2] = (byte) ((val >> 16) & 0xff);
8440                                         data[idx + 3] = (byte) (val >> 24);
8441                                         break;
8442                                 case BuiltinTypeSpec.Type.UInt:
8443                                         uint uval = (uint) v;
8444
8445                                         data[idx] = (byte) (uval & 0xff);
8446                                         data[idx + 1] = (byte) ((uval >> 8) & 0xff);
8447                                         data[idx + 2] = (byte) ((uval >> 16) & 0xff);
8448                                         data[idx + 3] = (byte) (uval >> 24);
8449                                         break;
8450                                 case BuiltinTypeSpec.Type.SByte:
8451                                         data[idx] = (byte) (sbyte) v;
8452                                         break;
8453                                 case BuiltinTypeSpec.Type.Byte:
8454                                         data[idx] = (byte) v;
8455                                         break;
8456                                 case BuiltinTypeSpec.Type.Bool:
8457                                         data[idx] = (byte) ((bool) v ? 1 : 0);
8458                                         break;
8459                                 case BuiltinTypeSpec.Type.Decimal:
8460                                         int[] bits = Decimal.GetBits ((decimal) v);
8461                                         int p = idx;
8462
8463                                         // FIXME: For some reason, this doesn't work on the MS runtime.
8464                                         int[] nbits = new int[4];
8465                                         nbits[0] = bits[3];
8466                                         nbits[1] = bits[2];
8467                                         nbits[2] = bits[0];
8468                                         nbits[3] = bits[1];
8469
8470                                         for (int j = 0; j < 4; j++) {
8471                                                 data[p++] = (byte) (nbits[j] & 0xff);
8472                                                 data[p++] = (byte) ((nbits[j] >> 8) & 0xff);
8473                                                 data[p++] = (byte) ((nbits[j] >> 16) & 0xff);
8474                                                 data[p++] = (byte) (nbits[j] >> 24);
8475                                         }
8476                                         break;
8477                                 default:
8478                                         throw new Exception ("Unrecognized type in MakeByteBlob: " + element_type);
8479                                 }
8480
8481                                 idx += factor;
8482                         }
8483
8484                         return data;
8485                 }
8486
8487                 public override SLE.Expression MakeExpression (BuilderContext ctx)
8488                 {
8489 #if STATIC
8490                         return base.MakeExpression (ctx);
8491 #else
8492                         var initializers = new SLE.Expression [array_data.Count];
8493                         for (var i = 0; i < initializers.Length; i++) {
8494                                 if (array_data [i] == null)
8495                                         initializers [i] = SLE.Expression.Default (array_element_type.GetMetaInfo ());
8496                                 else
8497                                         initializers [i] = array_data [i].MakeExpression (ctx);
8498                         }
8499
8500                         return SLE.Expression.NewArrayInit (array_element_type.GetMetaInfo (), initializers);
8501 #endif
8502                 }
8503 #if STATIC
8504                 //
8505                 // Emits the initializers for the array
8506                 //
8507                 void EmitStaticInitializers (EmitContext ec, FieldExpr stackArray)
8508                 {
8509                         var m = ec.Module.PredefinedMembers.RuntimeHelpersInitializeArray.Resolve (loc);
8510                         if (m == null)
8511                                 return;
8512
8513                         //
8514                         // First, the static data
8515                         //
8516                         byte [] data = MakeByteBlob ();
8517                         var fb = ec.CurrentTypeDefinition.Module.MakeStaticData (data, loc);
8518
8519                         if (stackArray == null) {
8520                                 ec.Emit (OpCodes.Dup);
8521                         } else {
8522                                 stackArray.Emit (ec);
8523                         }
8524
8525                         ec.Emit (OpCodes.Ldtoken, fb);
8526                         ec.Emit (OpCodes.Call, m);
8527                 }
8528 #endif
8529
8530                 //
8531                 // Emits pieces of the array that can not be computed at compile
8532                 // time (variables and string locations).
8533                 //
8534                 // This always expect the top value on the stack to be the array
8535                 //
8536                 void EmitDynamicInitializers (EmitContext ec, bool emitConstants, StackFieldExpr stackArray)
8537                 {
8538                         int dims = bounds.Count;
8539                         var current_pos = new int [dims];
8540
8541                         for (int i = 0; i < array_data.Count; i++){
8542
8543                                 Expression e = array_data [i];
8544                                 var c = e as Constant;
8545
8546                                 // Constant can be initialized via StaticInitializer
8547                                 if (c == null || (c != null && emitConstants && !c.IsDefaultInitializer (array_element_type))) {
8548
8549                                         var etype = e.Type;
8550
8551                                         if (stackArray != null) {
8552                                                 if (e.ContainsEmitWithAwait ()) {
8553                                                         e = e.EmitToField (ec);
8554                                                 }
8555
8556                                                 stackArray.EmitLoad (ec);
8557                                         } else {
8558                                                 ec.Emit (OpCodes.Dup);
8559                                         }
8560
8561                                         for (int idx = 0; idx < dims; idx++)
8562                                                 ec.EmitInt (current_pos [idx]);
8563
8564                                         //
8565                                         // If we are dealing with a struct, get the
8566                                         // address of it, so we can store it.
8567                                         //
8568                                         if (dims == 1 && etype.IsStruct && !BuiltinTypeSpec.IsPrimitiveType (etype))
8569                                                 ec.Emit (OpCodes.Ldelema, etype);
8570
8571                                         e.Emit (ec);
8572
8573                                         ec.EmitArrayStore ((ArrayContainer) type);
8574                                 }
8575
8576                                 //
8577                                 // Advance counter
8578                                 //
8579                                 for (int j = dims - 1; j >= 0; j--){
8580                                         current_pos [j]++;
8581                                         if (current_pos [j] < bounds [j])
8582                                                 break;
8583                                         current_pos [j] = 0;
8584                                 }
8585                         }
8586
8587                         if (stackArray != null)
8588                                 stackArray.PrepareCleanup (ec);
8589                 }
8590
8591                 public override void Emit (EmitContext ec)
8592                 {
8593                         if (!NoEmptyInterpolation && EmitOptimizedEmpty (ec))
8594                                 return;
8595
8596                         var await_field = EmitToFieldSource (ec);
8597                         if (await_field != null)
8598                                 await_field.Emit (ec);
8599                 }
8600
8601                 bool EmitOptimizedEmpty (EmitContext ec)
8602                 {
8603                         if (arguments.Count != 1 || dimensions != 1)
8604                                 return false;
8605
8606                         var c = arguments [0] as Constant;
8607                         if (c == null || !c.IsZeroInteger)
8608                                 return false;
8609
8610                         var m = ec.Module.PredefinedMembers.ArrayEmpty.Get ();
8611                         if (m == null || ec.CurrentType.MemberDefinition.DeclaringAssembly == m.DeclaringType.MemberDefinition.DeclaringAssembly)
8612                                 return false;
8613
8614                         m = m.MakeGenericMethod (ec.MemberContext, array_element_type);
8615                         ec.Emit (OpCodes.Call, m);
8616                         return true;
8617                 }
8618
8619                 protected sealed override FieldExpr EmitToFieldSource (EmitContext ec)
8620                 {
8621                         if (first_emit != null) {
8622                                 first_emit.Emit (ec);
8623                                 first_emit_temp.Store (ec);
8624                         }
8625
8626                         StackFieldExpr await_stack_field;
8627                         if (ec.HasSet (BuilderContext.Options.AsyncBody) && InitializersContainAwait ()) {
8628                                 await_stack_field = ec.GetTemporaryField (type);
8629                                 ec.EmitThis ();
8630                         } else {
8631                                 await_stack_field = null;
8632                         }
8633
8634                         EmitExpressionsList (ec, arguments);
8635
8636                         ec.EmitArrayNew ((ArrayContainer) type);
8637
8638                         if (initializers == null)
8639                                 return await_stack_field;
8640
8641                         if (await_stack_field != null)
8642                                 await_stack_field.EmitAssignFromStack (ec);
8643
8644 #if STATIC
8645                         //
8646                         // Emit static initializer for arrays which contain more than 2 items and
8647                         // the static initializer will initialize at least 25% of array values or there
8648                         // is more than 10 items to be initialized
8649                         //
8650                         // NOTE: const_initializers_count does not contain default constant values.
8651                         //
8652                         if (const_initializers_count > 2 && (array_data.Count > 10 || const_initializers_count * 4 > (array_data.Count)) &&
8653                                 (BuiltinTypeSpec.IsPrimitiveType (array_element_type) || array_element_type.IsEnum)) {
8654                                 EmitStaticInitializers (ec, await_stack_field);
8655
8656                                 if (!only_constant_initializers)
8657                                         EmitDynamicInitializers (ec, false, await_stack_field);
8658                         } else
8659 #endif
8660                         {
8661                                 EmitDynamicInitializers (ec, true, await_stack_field);
8662                         }
8663
8664                         if (first_emit_temp != null)
8665                                 first_emit_temp.Release (ec);
8666
8667                         return await_stack_field;
8668                 }
8669
8670                 public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType, TypeSpec parameterType)
8671                 {
8672                         // no multi dimensional or jagged arrays
8673                         if (arguments.Count != 1 || array_element_type.IsArray) {
8674                                 base.EncodeAttributeValue (rc, enc, targetType, parameterType);
8675                                 return;
8676                         }
8677
8678                         // No array covariance, except for array -> object
8679                         if (type != targetType) {
8680                                 if (targetType.BuiltinType != BuiltinTypeSpec.Type.Object) {
8681                                         base.EncodeAttributeValue (rc, enc, targetType, parameterType);
8682                                         return;
8683                                 }
8684
8685                                 if (enc.Encode (type) == AttributeEncoder.EncodedTypeProperties.DynamicType) {
8686                                         Attribute.Error_AttributeArgumentIsDynamic (rc, loc);
8687                                         return;
8688                                 }
8689                         }
8690
8691                         // Single dimensional array of 0 size
8692                         if (array_data == null) {
8693                                 IntConstant ic = arguments[0] as IntConstant;
8694                                 if (ic == null || !ic.IsDefaultValue) {
8695                                         base.EncodeAttributeValue (rc, enc, targetType, parameterType);
8696                                 } else {
8697                                         enc.Encode (0);
8698                                 }
8699
8700                                 return;
8701                         }
8702
8703                         enc.Encode (array_data.Count);
8704                         foreach (var element in array_data) {
8705                                 element.EncodeAttributeValue (rc, enc, array_element_type, parameterType);
8706                         }
8707                 }
8708
8709                 protected override void CloneTo (CloneContext clonectx, Expression t)
8710                 {
8711                         ArrayCreation target = (ArrayCreation) t;
8712
8713                         if (requested_base_type != null)
8714                                 target.requested_base_type = (FullNamedExpression)requested_base_type.Clone (clonectx);
8715
8716                         if (arguments != null){
8717                                 target.arguments = new List<Expression> (arguments.Count);
8718                                 foreach (Expression e in arguments)
8719                                         target.arguments.Add (e.Clone (clonectx));
8720                         }
8721
8722                         if (initializers != null)
8723                                 target.initializers = (ArrayInitializer) initializers.Clone (clonectx);
8724                 }
8725
8726                 public override object Accept (StructuralVisitor visitor)
8727                 {
8728                         return visitor.Visit (this);
8729                 }
8730         }
8731
8732         //
8733         // Represents an implicitly typed array epxression
8734         //
8735         class ImplicitlyTypedArrayCreation : ArrayCreation
8736         {
8737                 TypeInferenceContext best_type_inference;
8738
8739                 public ImplicitlyTypedArrayCreation (ComposedTypeSpecifier rank, ArrayInitializer initializers, Location loc)
8740                         : base (null, rank, initializers, loc)
8741                 {
8742                 }
8743
8744                 public ImplicitlyTypedArrayCreation (ArrayInitializer initializers, Location loc)
8745                         : base (null, initializers, loc)
8746                 {
8747                 }
8748
8749                 protected override Expression DoResolve (ResolveContext ec)
8750                 {
8751                         if (type != null)
8752                                 return this;
8753
8754                         dimensions = rank.Dimension;
8755
8756                         best_type_inference = new TypeInferenceContext ();
8757
8758                         if (!ResolveInitializers (ec))
8759                                 return null;
8760
8761                         best_type_inference.FixAllTypes (ec);
8762                         array_element_type = best_type_inference.InferredTypeArguments[0];
8763                         best_type_inference = null;
8764
8765                         if (array_element_type == null || InternalType.HasNoType (array_element_type) || arguments.Count != rank.Dimension) {
8766                                 ec.Report.Error (826, loc,
8767                                         "The type of an implicitly typed array cannot be inferred from the initializer. Try specifying array type explicitly");
8768                                 return null;
8769                         }
8770
8771                         //
8772                         // At this point we found common base type for all initializer elements
8773                         // but we have to be sure that all static initializer elements are of
8774                         // same type
8775                         //
8776                         UnifyInitializerElement (ec);
8777
8778                         type = ArrayContainer.MakeType (ec.Module, array_element_type, dimensions);
8779                         eclass = ExprClass.Value;
8780                         return this;
8781                 }
8782
8783                 //
8784                 // Converts static initializer only
8785                 //
8786                 void UnifyInitializerElement (ResolveContext ec)
8787                 {
8788                         for (int i = 0; i < array_data.Count; ++i) {
8789                                 Expression e = array_data[i];
8790                                 if (e != null)
8791                                         array_data [i] = Convert.ImplicitConversion (ec, e, array_element_type, Location.Null);
8792                         }
8793                 }
8794
8795                 protected override Expression ResolveArrayElement (ResolveContext ec, Expression element)
8796                 {
8797                         element = element.Resolve (ec);
8798                         if (element != null)
8799                                 best_type_inference.AddCommonTypeBound (element.Type);
8800
8801                         return element;
8802                 }
8803         }
8804
8805         sealed class CompilerGeneratedThis : This
8806         {
8807                 public CompilerGeneratedThis (TypeSpec type, Location loc)
8808                         : base (loc)
8809                 {
8810                         this.type = type;
8811                 }
8812
8813                 protected override Expression DoResolve (ResolveContext rc)
8814                 {
8815                         eclass = ExprClass.Variable;
8816
8817                         var block = rc.CurrentBlock;
8818                         if (block != null) {
8819                                 var top = block.ParametersBlock.TopBlock;
8820                                 if (top.ThisVariable != null)
8821                                         variable_info = top.ThisVariable.VariableInfo;
8822
8823                         }
8824
8825                         return this;
8826                 }
8827
8828                 public override Expression DoResolveLValue (ResolveContext rc, Expression right_side)
8829                 {
8830                         return DoResolve (rc);
8831                 }
8832
8833                 public override HoistedVariable GetHoistedVariable (AnonymousExpression ae)
8834                 {
8835                         return null;
8836                 }
8837         }
8838
8839         /// <summary>
8840         ///   Represents the `this' construct
8841         /// </summary>
8842
8843         public class This : VariableReference
8844         {
8845                 sealed class ThisVariable : ILocalVariable
8846                 {
8847                         public static readonly ILocalVariable Instance = new ThisVariable ();
8848
8849                         public void Emit (EmitContext ec)
8850                         {
8851                                 ec.EmitThis ();
8852                         }
8853
8854                         public void EmitAssign (EmitContext ec)
8855                         {
8856                                 throw new InvalidOperationException ();
8857                         }
8858
8859                         public void EmitAddressOf (EmitContext ec)
8860                         {
8861                                 ec.EmitThis ();
8862                         }
8863                 }
8864
8865                 protected VariableInfo variable_info;
8866
8867                 public This (Location loc)
8868                 {
8869                         this.loc = loc;
8870                 }
8871
8872                 #region Properties
8873
8874                 public override string Name {
8875                         get { return "this"; }
8876                 }
8877
8878                 public override bool IsLockedByStatement {
8879                         get {
8880                                 return false;
8881                         }
8882                         set {
8883                         }
8884                 }
8885
8886                 public override bool IsRef {
8887                         get { return type.IsStruct; }
8888                 }
8889
8890                 public override bool IsSideEffectFree {
8891                         get {
8892                                 return true;
8893                         }
8894                 }
8895
8896                 protected override ILocalVariable Variable {
8897                         get { return ThisVariable.Instance; }
8898                 }
8899
8900                 public override VariableInfo VariableInfo {
8901                         get { return variable_info; }
8902                 }
8903
8904                 public override bool IsFixed {
8905                         get { return false; }
8906                 }
8907
8908                 #endregion
8909
8910                 void CheckStructThisDefiniteAssignment (FlowAnalysisContext fc)
8911                 {
8912                         //
8913                         // It's null for all cases when we don't need to check `this'
8914                         // definitive assignment
8915                         //
8916                         if (variable_info == null)
8917                                 return;
8918
8919                         if (fc.IsDefinitelyAssigned (variable_info))
8920                                 return;
8921
8922                         fc.Report.Error (188, loc, "The `this' object cannot be used before all of its fields are assigned to");
8923                 }
8924
8925                 protected virtual void Error_ThisNotAvailable (ResolveContext ec)
8926                 {
8927                         if (ec.IsStatic && !ec.HasSet (ResolveContext.Options.ConstantScope)) {
8928                                 ec.Report.Error (26, loc, "Keyword `this' is not valid in a static property, static method, or static field initializer");
8929                         } else if (ec.CurrentAnonymousMethod != null) {
8930                                 ec.Report.Error (1673, loc,
8931                                         "Anonymous methods inside structs cannot access instance members of `this'. " +
8932                                         "Consider copying `this' to a local variable outside the anonymous method and using the local instead");
8933                         } else {
8934                                 ec.Report.Error (27, loc, "Keyword `this' is not available in the current context");
8935                         }
8936                 }
8937
8938                 public override void FlowAnalysis (FlowAnalysisContext fc)
8939                 {
8940                         CheckStructThisDefiniteAssignment (fc);
8941                 }
8942
8943                 public override HoistedVariable GetHoistedVariable (AnonymousExpression ae)
8944                 {
8945                         if (ae == null)
8946                                 return null;
8947
8948                         AnonymousMethodStorey storey = ae.Storey;
8949                         return storey != null ? storey.HoistedThis : null;
8950                 }
8951
8952                 public static bool IsThisAvailable (ResolveContext ec, bool ignoreAnonymous)
8953                 {
8954                         if (ec.IsStatic || ec.HasAny (ResolveContext.Options.FieldInitializerScope | ResolveContext.Options.BaseInitializer | ResolveContext.Options.ConstantScope))
8955                                 return false;
8956
8957                         if (ignoreAnonymous || ec.CurrentAnonymousMethod == null)
8958                                 return true;
8959
8960                         if (ec.CurrentType.IsStruct && !(ec.CurrentAnonymousMethod is StateMachineInitializer))
8961                                 return false;
8962
8963                         return true;
8964                 }
8965
8966                 public virtual void ResolveBase (ResolveContext ec)
8967                 {
8968                         eclass = ExprClass.Variable;
8969                         type = ec.CurrentType;
8970
8971                         if (!IsThisAvailable (ec, false)) {
8972                                 Error_ThisNotAvailable (ec);
8973                                 return;
8974                         }
8975
8976                         var block = ec.CurrentBlock;
8977                         if (block != null) {
8978                                 var top = block.ParametersBlock.TopBlock;
8979                                 if (top.ThisVariable != null)
8980                                         variable_info = top.ThisVariable.VariableInfo;
8981
8982                                 AnonymousExpression am = ec.CurrentAnonymousMethod;
8983                                 if (am != null && ec.IsVariableCapturingRequired && !block.Explicit.HasCapturedThis) {
8984                                         //
8985                                         // Hoisted this is almost like hoisted variable but not exactly. When
8986                                         // there is no variable hoisted we can simply emit an instance method
8987                                         // without lifting this into a storey. Unfotunatelly this complicates
8988                                         // things in other cases because we don't know where this will be hoisted
8989                                         // until top-level block is fully resolved
8990                                         //
8991                                         top.AddThisReferenceFromChildrenBlock (block.Explicit);
8992                                         am.SetHasThisAccess ();
8993                                 }
8994                         }
8995                 }
8996
8997                 protected override Expression DoResolve (ResolveContext ec)
8998                 {
8999                         ResolveBase (ec);
9000                         return this;
9001                 }
9002
9003                 public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
9004                 {
9005                         if (eclass == ExprClass.Unresolved)
9006                                 ResolveBase (ec);
9007
9008                         if (type.IsClass || type.IsReadOnly) {
9009                                 if (right_side == EmptyExpression.UnaryAddress)
9010                                         ec.Report.Error (459, loc, "Cannot take the address of `this' because it is read-only");
9011                                 else if (right_side == EmptyExpression.OutAccess)
9012                                         ec.Report.Error (1605, loc, "Cannot pass `this' as a ref or out argument because it is read-only");
9013                                 else
9014                                         ec.Report.Error (1604, loc, "Cannot assign to `this' because it is read-only");
9015                         }
9016
9017                         return this;
9018                 }
9019
9020                 public override int GetHashCode()
9021                 {
9022                         throw new NotImplementedException ();
9023                 }
9024
9025                 public override bool Equals (object obj)
9026                 {
9027                         This t = obj as This;
9028                         if (t == null)
9029                                 return false;
9030
9031                         return true;
9032                 }
9033
9034                 protected override void CloneTo (CloneContext clonectx, Expression t)
9035                 {
9036                         // Nothing
9037                 }
9038
9039                 public override void SetHasAddressTaken ()
9040                 {
9041                         // Nothing
9042                 }
9043
9044                 public override object Accept (StructuralVisitor visitor)
9045                 {
9046                         return visitor.Visit (this);
9047                 }
9048         }
9049
9050         /// <summary>
9051         ///   Represents the `__arglist' construct
9052         /// </summary>
9053         public class ArglistAccess : Expression
9054         {
9055                 public ArglistAccess (Location loc)
9056                 {
9057                         this.loc = loc;
9058                 }
9059
9060                 protected override void CloneTo (CloneContext clonectx, Expression target)
9061                 {
9062                         // nothing.
9063                 }
9064
9065                 public override bool ContainsEmitWithAwait ()
9066                 {
9067                         return false;
9068                 }
9069
9070                 public override Expression CreateExpressionTree (ResolveContext ec)
9071                 {
9072                         throw new NotSupportedException ("ET");
9073                 }
9074
9075                 protected override Expression DoResolve (ResolveContext ec)
9076                 {
9077                         eclass = ExprClass.Variable;
9078                         type = ec.Module.PredefinedTypes.RuntimeArgumentHandle.Resolve ();
9079
9080                         if (ec.HasSet (ResolveContext.Options.FieldInitializerScope) || !ec.CurrentBlock.ParametersBlock.Parameters.HasArglist) {
9081                                 ec.Report.Error (190, loc,
9082                                         "The __arglist construct is valid only within a variable argument method");
9083                         }
9084
9085                         return this;
9086                 }
9087
9088                 public override void Emit (EmitContext ec)
9089                 {
9090                         ec.Emit (OpCodes.Arglist);
9091                 }
9092
9093                 public override object Accept (StructuralVisitor visitor)
9094                 {
9095                         return visitor.Visit (this);
9096                 }
9097         }
9098
9099         /// <summary>
9100         ///   Represents the `__arglist (....)' construct
9101         /// </summary>
9102         public class Arglist : Expression
9103         {
9104                 Arguments arguments;
9105
9106                 public Arglist (Location loc)
9107                         : this (null, loc)
9108                 {
9109                 }
9110
9111                 public Arglist (Arguments args, Location l)
9112                 {
9113                         arguments = args;
9114                         loc = l;
9115                 }
9116
9117                 public Arguments Arguments {
9118                         get {
9119                                 return arguments;
9120                         }
9121                 }
9122
9123                 public MetaType[] ArgumentTypes {
9124                     get {
9125                                 if (arguments == null)
9126                                         return MetaType.EmptyTypes;
9127
9128                                 var retval = new MetaType[arguments.Count];
9129                                 for (int i = 0; i < retval.Length; i++)
9130                                         retval[i] = arguments[i].Expr.Type.GetMetaInfo ();
9131
9132                         return retval;
9133                     }
9134                 }
9135
9136                 public override bool ContainsEmitWithAwait ()
9137                 {
9138                         throw new NotImplementedException ();
9139                 }
9140
9141                 public override Expression CreateExpressionTree (ResolveContext ec)
9142                 {
9143                         ec.Report.Error (1952, loc, "An expression tree cannot contain a method with variable arguments");
9144                         return null;
9145                 }
9146
9147                 protected override Expression DoResolve (ResolveContext ec)
9148                 {
9149                         eclass = ExprClass.Variable;
9150                         type = InternalType.Arglist;
9151                         if (arguments != null) {
9152                                 bool dynamic;   // Can be ignored as there is always only 1 overload
9153                                 arguments.Resolve (ec, out dynamic);
9154                         }
9155
9156                         return this;
9157                 }
9158
9159                 public override void Emit (EmitContext ec)
9160                 {
9161                         if (arguments != null)
9162                                 arguments.Emit (ec);
9163                 }
9164
9165                 protected override void CloneTo (CloneContext clonectx, Expression t)
9166                 {
9167                         Arglist target = (Arglist) t;
9168
9169                         if (arguments != null)
9170                                 target.arguments = arguments.Clone (clonectx);
9171                 }
9172
9173                 public override object Accept (StructuralVisitor visitor)
9174                 {
9175                         return visitor.Visit (this);
9176                 }
9177         }
9178
9179         public class RefValueExpr : ShimExpression, IAssignMethod, IMemoryLocation
9180         {
9181                 FullNamedExpression texpr;
9182
9183                 public RefValueExpr (Expression expr, FullNamedExpression texpr, Location loc)
9184                         : base (expr)
9185                 {
9186                         this.texpr = texpr;
9187                         this.loc = loc;
9188                 }
9189
9190                 public FullNamedExpression TypeExpression {
9191                         get {
9192                                 return texpr;
9193                         }
9194                 }
9195
9196                 public override bool ContainsEmitWithAwait ()
9197                 {
9198                         return false;
9199                 }
9200
9201                 public void AddressOf (EmitContext ec, AddressOp mode)
9202                 {
9203                         expr.Emit (ec);
9204                         ec.Emit (OpCodes.Refanyval, type);
9205                 }
9206
9207                 protected override Expression DoResolve (ResolveContext rc)
9208                 {
9209                         expr = expr.Resolve (rc);
9210                         type = texpr.ResolveAsType (rc);
9211                         if (expr == null || type == null)
9212                                 return null;
9213
9214                         expr = Convert.ImplicitConversionRequired (rc, expr, rc.Module.PredefinedTypes.TypedReference.Resolve (), loc);
9215                         eclass = ExprClass.Variable;
9216                         return this;
9217                 }
9218
9219                 public override Expression DoResolveLValue (ResolveContext rc, Expression right_side)
9220                 {
9221                         return DoResolve (rc);
9222                 }
9223
9224                 public override void Emit (EmitContext ec)
9225                 {
9226                         expr.Emit (ec);
9227                         ec.Emit (OpCodes.Refanyval, type);
9228                         ec.EmitLoadFromPtr (type);
9229                 }
9230
9231                 public void Emit (EmitContext ec, bool leave_copy)
9232                 {
9233                         throw new NotImplementedException ();
9234                 }
9235
9236                 public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool isCompound)
9237                 {
9238                         expr.Emit (ec);
9239                         ec.Emit (OpCodes.Refanyval, type);
9240                         source.Emit (ec);
9241
9242                         LocalTemporary temporary = null;
9243                         if (leave_copy) {
9244                                 ec.Emit (OpCodes.Dup);
9245                                 temporary = new LocalTemporary (source.Type);
9246                                 temporary.Store (ec);
9247                         }
9248
9249                         ec.EmitStoreFromPtr (type);
9250
9251                         if (temporary != null) {
9252                                 temporary.Emit (ec);
9253                                 temporary.Release (ec);
9254                         }
9255                 }
9256
9257                 public override object Accept (StructuralVisitor visitor)
9258                 {
9259                         return visitor.Visit (this);
9260                 }
9261         }
9262
9263         public class RefTypeExpr : ShimExpression
9264         {
9265                 public RefTypeExpr (Expression expr, Location loc)
9266                         : base (expr)
9267                 {
9268                         this.loc = loc;
9269                 }
9270
9271                 protected override Expression DoResolve (ResolveContext rc)
9272                 {
9273                         expr = expr.Resolve (rc);
9274                         if (expr == null)
9275                                 return null;
9276
9277                         expr = Convert.ImplicitConversionRequired (rc, expr, rc.Module.PredefinedTypes.TypedReference.Resolve (), loc);
9278                         if (expr == null)
9279                                 return null;
9280
9281                         type = rc.BuiltinTypes.Type;
9282                         eclass = ExprClass.Value;
9283                         return this;
9284                 }
9285
9286                 public override void Emit (EmitContext ec)
9287                 {
9288                         expr.Emit (ec);
9289                         ec.Emit (OpCodes.Refanytype);
9290                         var m = ec.Module.PredefinedMembers.TypeGetTypeFromHandle.Resolve (loc);
9291                         if (m != null)
9292                                 ec.Emit (OpCodes.Call, m);
9293                 }
9294
9295                 public override object Accept (StructuralVisitor visitor)
9296                 {
9297                         return visitor.Visit (this);
9298                 }
9299         }
9300
9301         public class MakeRefExpr : ShimExpression
9302         {
9303                 public MakeRefExpr (Expression expr, Location loc)
9304                         : base (expr)
9305                 {
9306                         this.loc = loc;
9307                 }
9308
9309                 public override bool ContainsEmitWithAwait ()
9310                 {
9311                         throw new NotImplementedException ();
9312                 }
9313
9314                 protected override Expression DoResolve (ResolveContext rc)
9315                 {
9316                         expr = expr.ResolveLValue (rc, EmptyExpression.LValueMemberAccess);
9317                         type = rc.Module.PredefinedTypes.TypedReference.Resolve ();
9318                         eclass = ExprClass.Value;
9319                         return this;
9320                 }
9321
9322                 public override void Emit (EmitContext ec)
9323                 {
9324                         ((IMemoryLocation) expr).AddressOf (ec, AddressOp.Load);
9325                         ec.Emit (OpCodes.Mkrefany, expr.Type);
9326                 }
9327
9328                 public override object Accept (StructuralVisitor visitor)
9329                 {
9330                         return visitor.Visit (this);
9331                 }
9332         }
9333
9334         /// <summary>
9335         ///   Implements the typeof operator
9336         /// </summary>
9337         public class TypeOf : Expression {
9338                 FullNamedExpression QueriedType;
9339                 TypeSpec typearg;
9340
9341                 public TypeOf (FullNamedExpression queried_type, Location l)
9342                 {
9343                         QueriedType = queried_type;
9344                         loc = l;
9345                 }
9346
9347                 //
9348                 // Use this constructor for any compiler generated typeof expression
9349                 //
9350                 public TypeOf (TypeSpec type, Location loc)
9351                 {
9352                         this.typearg = type;
9353                         this.loc = loc;
9354                 }
9355
9356                 #region Properties
9357
9358                 public override bool IsSideEffectFree {
9359                         get {
9360                                 return true;
9361                         }
9362                 }
9363
9364                 public TypeSpec TypeArgument {
9365                         get {
9366                                 return typearg;
9367                         }
9368                 }
9369
9370                 public FullNamedExpression TypeExpression {
9371                         get {
9372                                 return QueriedType;
9373                         }
9374                 }
9375
9376                 #endregion
9377
9378
9379                 protected override void CloneTo (CloneContext clonectx, Expression t)
9380                 {
9381                         TypeOf target = (TypeOf) t;
9382                         if (QueriedType != null)
9383                                 target.QueriedType = (FullNamedExpression) QueriedType.Clone (clonectx);
9384                 }
9385
9386                 public override bool ContainsEmitWithAwait ()
9387                 {
9388                         return false;
9389                 }
9390
9391                 public override Expression CreateExpressionTree (ResolveContext ec)
9392                 {
9393                         Arguments args = new Arguments (2);
9394                         args.Add (new Argument (this));
9395                         args.Add (new Argument (new TypeOf (new TypeExpression (type, loc), loc)));
9396                         return CreateExpressionFactoryCall (ec, "Constant", args);
9397                 }
9398
9399                 protected override Expression DoResolve (ResolveContext ec)
9400                 {
9401                         if (eclass != ExprClass.Unresolved)
9402                                 return this;
9403
9404                         if (typearg == null) {
9405                                 //
9406                                 // Pointer types are allowed without explicit unsafe, they are just tokens
9407                                 //
9408                                 using (ec.Set (ResolveContext.Options.UnsafeScope)) {
9409                                         typearg = QueriedType.ResolveAsType (ec, true);
9410                                 }
9411
9412                                 if (typearg == null)
9413                                         return null;
9414
9415                                 if (typearg.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
9416                                         ec.Report.Error (1962, QueriedType.Location,
9417                                                 "The typeof operator cannot be used on the dynamic type");
9418                                 }
9419                         }
9420
9421                         type = ec.BuiltinTypes.Type;
9422
9423                         // Even though what is returned is a type object, it's treated as a value by the compiler.
9424                         // In particular, 'typeof (Foo).X' is something totally different from 'Foo.X'.
9425                         eclass = ExprClass.Value;
9426                         return this;
9427                 }
9428
9429                 static bool ContainsDynamicType (TypeSpec type)
9430                 {
9431                         if (type.BuiltinType == BuiltinTypeSpec.Type.Dynamic)
9432                                 return true;
9433
9434                         var element_container = type as ElementTypeSpec;
9435                         if (element_container != null)
9436                                 return ContainsDynamicType (element_container.Element);
9437
9438                         foreach (var t in type.TypeArguments) {
9439                                 if (ContainsDynamicType (t)) {
9440                                         return true;
9441                                 }
9442                         }
9443
9444                         return false;
9445                 }
9446
9447                 public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType, TypeSpec parameterType)
9448                 {
9449                         // Target type is not System.Type therefore must be object
9450                         // and we need to use different encoding sequence
9451                         if (targetType != type)
9452                                 enc.Encode (type);
9453
9454                         if (typearg is InflatedTypeSpec) {
9455                                 var gt = typearg;
9456                                 do {
9457                                         if (InflatedTypeSpec.ContainsTypeParameter (gt)) {
9458                                                 rc.Module.Compiler.Report.Error (416, loc, "`{0}': an attribute argument cannot use type parameters",
9459                                                         typearg.GetSignatureForError ());
9460                                                 return;
9461                                         }
9462
9463                                         gt = gt.DeclaringType;
9464                                 } while (gt != null);
9465                         }
9466
9467                         if (ContainsDynamicType (typearg)) {
9468                                 Attribute.Error_AttributeArgumentIsDynamic (rc, loc);
9469                                 return;
9470                         }
9471
9472                         enc.EncodeTypeName (typearg);
9473                 }
9474
9475                 public override void Emit (EmitContext ec)
9476                 {
9477                         ec.Emit (OpCodes.Ldtoken, typearg);
9478                         var m = ec.Module.PredefinedMembers.TypeGetTypeFromHandle.Resolve (loc);
9479                         if (m != null)
9480                                 ec.Emit (OpCodes.Call, m);
9481                 }
9482
9483                 public override object Accept (StructuralVisitor visitor)
9484                 {
9485                         return visitor.Visit (this);
9486                 }
9487         }
9488
9489         sealed class TypeOfMethod : TypeOfMember<MethodSpec>
9490         {
9491                 public TypeOfMethod (MethodSpec method, Location loc)
9492                         : base (method, loc)
9493                 {
9494                 }
9495
9496                 protected override Expression DoResolve (ResolveContext ec)
9497                 {
9498                         if (member.IsConstructor) {
9499                                 type = ec.Module.PredefinedTypes.ConstructorInfo.Resolve ();
9500                         } else {
9501                                 type = ec.Module.PredefinedTypes.MethodInfo.Resolve ();
9502                         }
9503
9504                         if (type == null)
9505                                 return null;
9506
9507                         return base.DoResolve (ec);
9508                 }
9509
9510                 public override void Emit (EmitContext ec)
9511                 {
9512                         ec.Emit (OpCodes.Ldtoken, member);
9513
9514                         base.Emit (ec);
9515                         ec.Emit (OpCodes.Castclass, type);
9516                 }
9517
9518                 protected override PredefinedMember<MethodSpec> GetTypeFromHandle (EmitContext ec)
9519                 {
9520                         return ec.Module.PredefinedMembers.MethodInfoGetMethodFromHandle;
9521                 }
9522
9523                 protected override PredefinedMember<MethodSpec> GetTypeFromHandleGeneric (EmitContext ec)
9524                 {
9525                         return ec.Module.PredefinedMembers.MethodInfoGetMethodFromHandle2;
9526                 }
9527         }
9528
9529         abstract class TypeOfMember<T> : Expression where T : MemberSpec
9530         {
9531                 protected readonly T member;
9532
9533                 protected TypeOfMember (T member, Location loc)
9534                 {
9535                         this.member = member;
9536                         this.loc = loc;
9537                 }
9538
9539                 public override bool IsSideEffectFree {
9540                         get {
9541                                 return true;
9542                         }
9543                 }
9544
9545                 public override bool ContainsEmitWithAwait ()
9546                 {
9547                         return false;
9548                 }
9549
9550                 public override Expression CreateExpressionTree (ResolveContext ec)
9551                 {
9552                         Arguments args = new Arguments (2);
9553                         args.Add (new Argument (this));
9554                         args.Add (new Argument (new TypeOf (type, loc)));
9555                         return CreateExpressionFactoryCall (ec, "Constant", args);
9556                 }
9557
9558                 protected override Expression DoResolve (ResolveContext ec)
9559                 {
9560                         eclass = ExprClass.Value;
9561                         return this;
9562                 }
9563
9564                 public override void Emit (EmitContext ec)
9565                 {
9566                         bool is_generic = member.DeclaringType.IsGenericOrParentIsGeneric;
9567                         PredefinedMember<MethodSpec> p;
9568                         if (is_generic) {
9569                                 p = GetTypeFromHandleGeneric (ec);
9570                                 ec.Emit (OpCodes.Ldtoken, member.DeclaringType);
9571                         } else {
9572                                 p = GetTypeFromHandle (ec);
9573                         }
9574
9575                         var mi = p.Resolve (loc);
9576                         if (mi != null)
9577                                 ec.Emit (OpCodes.Call, mi);
9578                 }
9579
9580                 protected abstract PredefinedMember<MethodSpec> GetTypeFromHandle (EmitContext ec);
9581                 protected abstract PredefinedMember<MethodSpec> GetTypeFromHandleGeneric (EmitContext ec);
9582         }
9583
9584         sealed class TypeOfField : TypeOfMember<FieldSpec>
9585         {
9586                 public TypeOfField (FieldSpec field, Location loc)
9587                         : base (field, loc)
9588                 {
9589                 }
9590
9591                 protected override Expression DoResolve (ResolveContext ec)
9592                 {
9593                         type = ec.Module.PredefinedTypes.FieldInfo.Resolve ();
9594                         if (type == null)
9595                                 return null;
9596
9597                         return base.DoResolve (ec);
9598                 }
9599
9600                 public override void Emit (EmitContext ec)
9601                 {
9602                         ec.Emit (OpCodes.Ldtoken, member);
9603                         base.Emit (ec);
9604                 }
9605
9606                 protected override PredefinedMember<MethodSpec> GetTypeFromHandle (EmitContext ec)
9607                 {
9608                         return ec.Module.PredefinedMembers.FieldInfoGetFieldFromHandle;
9609                 }
9610
9611                 protected override PredefinedMember<MethodSpec> GetTypeFromHandleGeneric (EmitContext ec)
9612                 {
9613                         return ec.Module.PredefinedMembers.FieldInfoGetFieldFromHandle2;
9614                 }
9615         }
9616
9617         /// <summary>
9618         ///   Implements the sizeof expression
9619         /// </summary>
9620         public class SizeOf : Expression {
9621                 readonly Expression texpr;
9622                 TypeSpec type_queried;
9623
9624                 public SizeOf (Expression queried_type, Location l)
9625                 {
9626                         this.texpr = queried_type;
9627                         loc = l;
9628                 }
9629
9630                 public override bool IsSideEffectFree {
9631                         get {
9632                                 return true;
9633                         }
9634                 }
9635
9636                 public Expression TypeExpression {
9637                         get {
9638                                 return texpr;
9639                         }
9640                 }
9641
9642                 public override bool ContainsEmitWithAwait ()
9643                 {
9644                         return false;
9645                 }
9646
9647                 public override Expression CreateExpressionTree (ResolveContext ec)
9648                 {
9649                         Error_PointerInsideExpressionTree (ec);
9650                         return null;
9651                 }
9652
9653                 protected override Expression DoResolve (ResolveContext ec)
9654                 {
9655                         type_queried = texpr.ResolveAsType (ec);
9656                         if (type_queried == null)
9657                                 return null;
9658
9659                         if (type_queried.IsEnum)
9660                                 type_queried = EnumSpec.GetUnderlyingType (type_queried);
9661
9662                         int size_of = BuiltinTypeSpec.GetSize (type_queried);
9663                         if (size_of > 0) {
9664                                 return new IntConstant (ec.BuiltinTypes, size_of, loc);
9665                         }
9666
9667                         if (!TypeManager.VerifyUnmanaged (ec.Module, type_queried, loc)){
9668                                 return null;
9669                         }
9670
9671                         if (!ec.IsUnsafe) {
9672                                 ec.Report.Error (233, loc,
9673                                         "`{0}' does not have a predefined size, therefore sizeof can only be used in an unsafe context (consider using System.Runtime.InteropServices.Marshal.SizeOf)",
9674                                         type_queried.GetSignatureForError ());
9675                         }
9676
9677                         type = ec.BuiltinTypes.Int;
9678                         eclass = ExprClass.Value;
9679                         return this;
9680                 }
9681
9682                 public override void Emit (EmitContext ec)
9683                 {
9684                         ec.Emit (OpCodes.Sizeof, type_queried);
9685                 }
9686
9687                 protected override void CloneTo (CloneContext clonectx, Expression t)
9688                 {
9689                 }
9690
9691                 public override object Accept (StructuralVisitor visitor)
9692                 {
9693                         return visitor.Visit (this);
9694                 }
9695         }
9696
9697         /// <summary>
9698         ///   Implements the qualified-alias-member (::) expression.
9699         /// </summary>
9700         public class QualifiedAliasMember : MemberAccess
9701         {
9702                 readonly string alias;
9703                 public static readonly string GlobalAlias = "global";
9704
9705                 public QualifiedAliasMember (string alias, string identifier, Location l)
9706                         : base (null, identifier, l)
9707                 {
9708                         this.alias = alias;
9709                 }
9710
9711                 public QualifiedAliasMember (string alias, string identifier, TypeArguments targs, Location l)
9712                         : base (null, identifier, targs, l)
9713                 {
9714                         this.alias = alias;
9715                 }
9716
9717                 public QualifiedAliasMember (string alias, string identifier, int arity, Location l)
9718                         : base (null, identifier, arity, l)
9719                 {
9720                         this.alias = alias;
9721                 }
9722
9723                 public string Alias {
9724                         get {
9725                                 return alias;
9726                         }
9727                 }
9728
9729                 public FullNamedExpression CreateExpressionFromAlias (IMemberContext mc)
9730                 {
9731                         if (alias == GlobalAlias)
9732                                 return new NamespaceExpression (mc.Module.GlobalRootNamespace, loc);
9733
9734                         int errors = mc.Module.Compiler.Report.Errors;
9735                         var expr = mc.LookupNamespaceAlias (alias);
9736                         if (expr == null) {
9737                                 if (errors == mc.Module.Compiler.Report.Errors)
9738                                         mc.Module.Compiler.Report.Error (432, loc, "Alias `{0}' not found", alias);
9739
9740                                 return null;
9741                         }
9742
9743                         return expr;
9744                 }
9745
9746                 public override FullNamedExpression ResolveAsTypeOrNamespace (IMemberContext mc, bool allowUnboundTypeArguments)
9747                 {
9748                         expr = CreateExpressionFromAlias (mc);
9749                         if (expr == null)
9750                                 return null;
9751
9752                         return base.ResolveAsTypeOrNamespace (mc, allowUnboundTypeArguments);
9753                 }
9754
9755                 protected override Expression DoResolve (ResolveContext rc)
9756                 {
9757                         return ResolveAsTypeOrNamespace (rc, false);
9758                 }
9759
9760                 public override string GetSignatureForError ()
9761                 {
9762                         string name = Name;
9763                         if (targs != null) {
9764                                 name = Name + "<" + targs.GetSignatureForError () + ">";
9765                         }
9766
9767                         return alias + "::" + name;
9768                 }
9769
9770                 public override bool HasConditionalAccess ()
9771                 {
9772                         return false;
9773                 }
9774
9775                 public override Expression LookupNameExpression (ResolveContext rc, MemberLookupRestrictions restrictions)
9776                 {
9777                         if ((restrictions & MemberLookupRestrictions.InvocableOnly) != 0) {
9778                                 rc.Module.Compiler.Report.Error (687, loc,
9779                                         "The namespace alias qualifier `::' cannot be used to invoke a method. Consider using `.' instead",
9780                                         GetSignatureForError ());
9781
9782                                 return null;
9783                         }
9784
9785                         return DoResolve (rc);
9786                 }
9787
9788                 protected override void CloneTo (CloneContext clonectx, Expression t)
9789                 {
9790                         // Nothing
9791                 }
9792
9793                 public override object Accept (StructuralVisitor visitor)
9794                 {
9795                         return visitor.Visit (this);
9796                 }
9797         }
9798
9799         /// <summary>
9800         ///   Implements the member access expression
9801         /// </summary>
9802         public class MemberAccess : ATypeNameExpression
9803         {
9804                 protected Expression expr;
9805
9806                 public MemberAccess (Expression expr, string id)
9807                         : base (id, expr.Location)
9808                 {
9809                         this.expr = expr;
9810                 }
9811
9812                 public MemberAccess (Expression expr, string identifier, Location loc)
9813                         : base (identifier, loc)
9814                 {
9815                         this.expr = expr;
9816                 }
9817
9818                 public MemberAccess (Expression expr, string identifier, TypeArguments args, Location loc)
9819                         : base (identifier, args, loc)
9820                 {
9821                         this.expr = expr;
9822                 }
9823
9824                 public MemberAccess (Expression expr, string identifier, int arity, Location loc)
9825                         : base (identifier, arity, loc)
9826                 {
9827                         this.expr = expr;
9828                 }
9829
9830                 public Expression LeftExpression {
9831                         get {
9832                                 return expr;
9833                         }
9834                 }
9835
9836                 public override Location StartLocation {
9837                         get {
9838                                 return expr == null ? loc : expr.StartLocation;
9839                         }
9840                 }
9841
9842                 protected override Expression DoResolve (ResolveContext rc)
9843                 {
9844                         var e = LookupNameExpression (rc, MemberLookupRestrictions.ReadAccess | MemberLookupRestrictions.DontSetConditionalAccess);
9845                         if (e != null)
9846                                 e = e.Resolve (rc, ResolveFlags.VariableOrValue | ResolveFlags.Type | ResolveFlags.MethodGroup);
9847
9848                         return e;
9849                 }
9850
9851                 public override Expression DoResolveLValue (ResolveContext rc, Expression rhs)
9852                 {
9853                         var e = LookupNameExpression (rc, MemberLookupRestrictions.None);
9854
9855                         if (e is TypeExpr) {
9856                                 e.Error_UnexpectedKind (rc, ResolveFlags.VariableOrValue, loc);
9857                                 return null;
9858                         }
9859
9860                         if (e != null)
9861                                 e = e.ResolveLValue (rc, rhs);
9862
9863                         return e;
9864                 }
9865
9866                 protected virtual void Error_OperatorCannotBeApplied (ResolveContext rc, TypeSpec type)
9867                 {
9868                         if (type == InternalType.NullLiteral && rc.IsRuntimeBinder)
9869                                 rc.Report.Error (Report.RuntimeErrorId, loc, "Cannot perform member binding on `null' value");
9870                         else
9871                                 expr.Error_OperatorCannotBeApplied (rc, loc, ".", type);
9872                 }
9873
9874                 public override bool HasConditionalAccess ()
9875                 {
9876                         return LeftExpression.HasConditionalAccess ();
9877                 }
9878
9879                 public static bool IsValidDotExpression (TypeSpec type)
9880                 {
9881                         const MemberKind dot_kinds = MemberKind.Class | MemberKind.Struct | MemberKind.Delegate | MemberKind.Enum |
9882                                 MemberKind.Interface | MemberKind.TypeParameter | MemberKind.ArrayType;
9883
9884                         return (type.Kind & dot_kinds) != 0 || type.BuiltinType == BuiltinTypeSpec.Type.Dynamic;
9885                 }
9886
9887                 public override Expression LookupNameExpression (ResolveContext rc, MemberLookupRestrictions restrictions)
9888                 {
9889                         var sn = expr as SimpleName;
9890                         const ResolveFlags flags = ResolveFlags.VariableOrValue | ResolveFlags.Type;
9891
9892                         if (sn != null) {
9893                                 expr = sn.LookupNameExpression (rc, MemberLookupRestrictions.ReadAccess | MemberLookupRestrictions.ExactArity);
9894
9895                                 //
9896                                 // Resolve expression which does have type set as we need expression type
9897                                 // with disable flow analysis as we don't know whether left side expression
9898                                 // is used as variable or type
9899                                 //
9900                                 if (expr is VariableReference || expr is ConstantExpr || expr is Linq.TransparentMemberAccess || expr is EventExpr) {
9901                                         expr = expr.Resolve (rc);
9902                                 } else if (expr is TypeParameterExpr) {
9903                                         expr.Error_UnexpectedKind (rc, flags, sn.Location);
9904                                         expr = null;
9905                                 }
9906                         } else {
9907                                 if ((restrictions & MemberLookupRestrictions.DontSetConditionalAccess) != 0) {
9908                                         using (rc.Set (ResolveContext.Options.DontSetConditionalAccessReceiver)) {
9909                                                 expr = expr.Resolve (rc, flags);
9910                                         }
9911                                 } else {
9912                                         expr = expr.Resolve (rc, flags);
9913                                 }
9914                         }
9915
9916                         if (expr == null)
9917                                 return null;
9918
9919                         var ns = expr as NamespaceExpression;
9920                         if (ns != null) {
9921                                 var retval = ns.LookupTypeOrNamespace (rc, Name, Arity, LookupMode.Normal, loc);
9922
9923                                 if (retval == null) {
9924                                         ns.Error_NamespaceDoesNotExist (rc, Name, Arity, loc);
9925                                         return null;
9926                                 }
9927
9928                                 if (Arity > 0) {
9929                                         if (HasTypeArguments)
9930                                                 return new GenericTypeExpr (retval.Type, targs, loc);
9931
9932                                         targs.Resolve (rc, false);
9933                                 }
9934
9935                                 return retval;
9936                         }
9937
9938                         var cma = this as ConditionalMemberAccess;
9939
9940                         MemberExpr me;
9941                         TypeSpec expr_type = expr.Type;
9942                         if (expr_type.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
9943                                 me = expr as MemberExpr;
9944                                 if (me != null)
9945                                         me.ResolveInstanceExpression (rc, null);
9946
9947                                 Arguments args = new Arguments (1);
9948                                 args.Add (new Argument (expr));
9949
9950                                 if (cma != null)
9951                                         return new DynamicConditionalMemberBinder (Name, args, loc);
9952
9953                                 return new DynamicMemberBinder (Name, args, loc);
9954                         }
9955
9956                         if (cma != null) {
9957                                 if (!IsNullPropagatingValid (expr.Type)) {
9958                                         expr.Error_OperatorCannotBeApplied (rc, loc, "?", expr.Type);
9959                                         return null;
9960                                 }
9961
9962                                 if (expr_type.IsNullableType) {
9963                                         expr = Nullable.Unwrap.Create (expr.Resolve (rc), true);
9964                                         expr_type = expr.Type;
9965                                 }
9966                         }
9967
9968                         if (!IsValidDotExpression (expr_type)) {
9969                                 Error_OperatorCannotBeApplied (rc, expr_type);
9970                                 return null;
9971                         }
9972
9973                         var lookup_arity = Arity;
9974                         bool errorMode = false;
9975                         Expression member_lookup;
9976                         while (true) {
9977                                 member_lookup = MemberLookup (rc, errorMode, expr_type, Name, lookup_arity, restrictions, loc);
9978                                 if (member_lookup == null) {
9979                                         //
9980                                         // Try to look for extension method when member lookup failed
9981                                         //
9982                                         if (MethodGroupExpr.IsExtensionMethodArgument (expr)) {
9983                                                 var methods = rc.LookupExtensionMethod (Name, lookup_arity);
9984                                                 if (methods != null) {
9985                                                         var emg = new ExtensionMethodGroupExpr (methods, expr, loc);
9986                                                         if (HasTypeArguments) {
9987                                                                 if (!targs.Resolve (rc, false))
9988                                                                         return null;
9989
9990                                                                 emg.SetTypeArguments (rc, targs);
9991                                                         }
9992
9993                                                         if (cma != null)
9994                                                                 emg.ConditionalAccess = true;
9995
9996                                                         // TODO: it should really skip the checks bellow
9997                                                         return emg.Resolve (rc);
9998                                                 }
9999                                         }
10000                                 }
10001
10002                                 if (errorMode) {
10003                                         if (member_lookup == null) {
10004                                                 var dep = expr_type.GetMissingDependencies ();
10005                                                 if (dep != null) {
10006                                                         ImportedTypeDefinition.Error_MissingDependency (rc, dep, loc);
10007                                                 } else if (expr is TypeExpr) {
10008                                                         base.Error_TypeDoesNotContainDefinition (rc, expr_type, Name);
10009                                                 } else {
10010                                                         Error_TypeDoesNotContainDefinition (rc, expr_type, Name);
10011                                                 }
10012
10013                                                 return null;
10014                                         }
10015
10016                                         if (member_lookup is MethodGroupExpr || member_lookup is PropertyExpr) {
10017                                                 // Leave it to overload resolution to report correct error
10018                                         } else if (!(member_lookup is TypeExpr)) {
10019                                                 // TODO: rc.SymbolRelatedToPreviousError
10020                                                 ErrorIsInaccesible (rc, member_lookup.GetSignatureForError (), loc);
10021                                         }
10022                                         break;
10023                                 }
10024
10025                                 if (member_lookup != null)
10026                                         break;
10027
10028                                 lookup_arity = 0;
10029                                 restrictions &= ~MemberLookupRestrictions.InvocableOnly;
10030                                 errorMode = true;
10031                         }
10032
10033                         TypeExpr texpr = member_lookup as TypeExpr;
10034                         if (texpr != null) {
10035                                 if (!(expr is TypeExpr) && (sn == null || expr.ProbeIdenticalTypeName (rc, expr, sn) == expr)) {
10036                                         rc.Report.Error (572, loc, "`{0}': cannot reference a type through an expression. Consider using `{1}' instead",
10037                                                 Name, texpr.GetSignatureForError ());
10038                                 }
10039
10040                                 if (!texpr.Type.IsAccessible (rc)) {
10041                                         rc.Report.SymbolRelatedToPreviousError (member_lookup.Type);
10042                                         ErrorIsInaccesible (rc, member_lookup.Type.GetSignatureForError (), loc);
10043                                         return null;
10044                                 }
10045
10046                                 if (HasTypeArguments) {
10047                                         return new GenericTypeExpr (member_lookup.Type, targs, loc);
10048                                 }
10049
10050                                 return member_lookup;
10051                         }
10052
10053                         me = member_lookup as MemberExpr;
10054
10055                         if (sn != null && me.IsStatic && (expr = me.ProbeIdenticalTypeName (rc, expr, sn)) != expr) {
10056                                 sn = null;
10057                         }
10058
10059                         if (cma != null) {
10060                                 me.ConditionalAccess = true;
10061                         }
10062
10063                         me = me.ResolveMemberAccess (rc, expr, sn);
10064
10065                         if (Arity > 0) {
10066                                 if (!targs.Resolve (rc, false))
10067                                         return null;
10068
10069                                 me.SetTypeArguments (rc, targs);
10070                         }
10071
10072                         return me;
10073                 }
10074
10075                 public override FullNamedExpression ResolveAsTypeOrNamespace (IMemberContext rc, bool allowUnboundTypeArguments)
10076                 {
10077                         FullNamedExpression fexpr = expr as FullNamedExpression;
10078                         if (fexpr == null) {
10079                                 expr.ResolveAsType (rc);
10080                                 return null;
10081                         }
10082
10083                         FullNamedExpression expr_resolved = fexpr.ResolveAsTypeOrNamespace (rc, allowUnboundTypeArguments);
10084
10085                         if (expr_resolved == null)
10086                                 return null;
10087
10088                         var ns = expr_resolved as NamespaceExpression;
10089                         if (ns != null) {
10090                                 FullNamedExpression retval = ns.LookupTypeOrNamespace (rc, Name, Arity, LookupMode.Normal, loc);
10091
10092                                 if (retval == null) {
10093                                         ns.Error_NamespaceDoesNotExist (rc, Name, Arity, loc);
10094                                 } else if (Arity > 0) {
10095                                         if (HasTypeArguments) {
10096                                                 retval = new GenericTypeExpr (retval.Type, targs, loc);
10097                                                 if (retval.ResolveAsType (rc) == null)
10098                                                         return null;
10099                                         } else {
10100                                                 targs.Resolve (rc, allowUnboundTypeArguments);
10101
10102                                                 retval = new GenericOpenTypeExpr (retval.Type, loc);
10103                                         }
10104                                 }
10105
10106                                 return retval;
10107                         }
10108
10109                         var tnew_expr = expr_resolved.ResolveAsType (rc);
10110                         if (tnew_expr == null)
10111                                 return null;
10112
10113                         TypeSpec expr_type = tnew_expr;
10114                         if (TypeManager.IsGenericParameter (expr_type)) {
10115                                 rc.Module.Compiler.Report.Error (704, loc, "A nested type cannot be specified through a type parameter `{0}'",
10116                                         tnew_expr.GetSignatureForError ());
10117                                 return null;
10118                         }
10119
10120                         var qam = this as QualifiedAliasMember;
10121                         if (qam != null) {
10122                                 rc.Module.Compiler.Report.Error (431, loc,
10123                                         "Alias `{0}' cannot be used with `::' since it denotes a type. Consider replacing `::' with `.'",
10124                                         qam.Alias);
10125
10126                         }
10127
10128                         TypeSpec nested = null;
10129                         while (expr_type != null) {
10130                                 nested = MemberCache.FindNestedType (expr_type, Name, Arity, false);
10131                                 if (nested == null) {
10132                                         if (expr_type == tnew_expr) {
10133                                                 Error_IdentifierNotFound (rc, expr_type);
10134                                                 return null;
10135                                         }
10136
10137                                         expr_type = tnew_expr;
10138                                         nested = MemberCache.FindNestedType (expr_type, Name, Arity, false);
10139                                         ErrorIsInaccesible (rc, nested.GetSignatureForError (), loc);
10140                                         break;
10141                                 }
10142
10143                                 if (nested.IsAccessible (rc))
10144                                         break;
10145
10146                                 //
10147                                 // Keep looking after inaccessible candidate but only if
10148                                 // we are not in same context as the definition itself
10149                                 //
10150                                 if (expr_type.MemberDefinition == rc.CurrentMemberDefinition)
10151                                         break;
10152
10153                                 expr_type = expr_type.BaseType;
10154                         }
10155
10156                         TypeExpr texpr;
10157                         if (Arity > 0) {
10158                                 if (HasTypeArguments) {
10159                                         texpr = new GenericTypeExpr (nested, targs, loc);
10160                                 } else {
10161                                         targs.Resolve (rc, allowUnboundTypeArguments && !(expr_resolved is GenericTypeExpr));
10162
10163                                         texpr = new GenericOpenTypeExpr (nested, loc);
10164                                 }
10165                         } else if (expr_resolved is GenericOpenTypeExpr) {
10166                                 texpr = new GenericOpenTypeExpr (nested, loc);
10167                         } else {
10168                                 texpr = new TypeExpression (nested, loc);
10169                         }
10170
10171                         if (texpr.ResolveAsType (rc) == null)
10172                                 return null;
10173
10174                         return texpr;
10175                 }
10176
10177                 public void Error_IdentifierNotFound (IMemberContext rc, TypeSpec expr_type)
10178                 {
10179                         var nested = MemberCache.FindNestedType (expr_type, Name, -System.Math.Max (1, Arity), false);
10180
10181                         if (nested != null) {
10182                                 Error_TypeArgumentsCannotBeUsed (rc, nested, expr.Location);
10183                                 return;
10184                         }
10185
10186                         var any_other_member = MemberLookup (rc, false, expr_type, Name, 0, MemberLookupRestrictions.None, loc);
10187                         if (any_other_member != null) {
10188                                 Error_UnexpectedKind (rc, any_other_member, "type", any_other_member.ExprClassName, loc);
10189                                 return;
10190                         }
10191
10192                         rc.Module.Compiler.Report.Error (426, loc, "The nested type `{0}' does not exist in the type `{1}'",
10193                                 Name, expr_type.GetSignatureForError ());
10194                 }
10195
10196                 protected override void Error_InvalidExpressionStatement (Report report, Location loc)
10197                 {
10198                         base.Error_InvalidExpressionStatement (report, LeftExpression.Location);
10199                 }
10200
10201                 public override void Error_TypeDoesNotContainDefinition (ResolveContext ec, TypeSpec type, string name)
10202                 {
10203                         if (ec.Module.Compiler.Settings.Version > LanguageVersion.ISO_2 && !ec.IsRuntimeBinder && MethodGroupExpr.IsExtensionMethodArgument (expr)) {
10204                                 ec.Report.SymbolRelatedToPreviousError (type);
10205
10206                                 var cand = ec.Module.GlobalRootNamespace.FindExtensionMethodNamespaces (ec, name, Arity);
10207                                 string missing;
10208                                 // a using directive or an assembly reference
10209                                 if (cand != null) {
10210                                         missing = "`" + string.Join ("' or `", cand.ToArray ()) + "' using directive";
10211                                 } else {
10212                                         missing = "an assembly reference";
10213                                 }
10214
10215                                 ec.Report.Error (1061, loc,
10216                                         "Type `{0}' does not contain a definition for `{1}' and no extension method `{1}' of type `{0}' could be found. Are you missing {2}?",
10217                                         type.GetSignatureForError (), name, missing);
10218                                 return;
10219                         }
10220
10221                         base.Error_TypeDoesNotContainDefinition (ec, type, name);
10222                 }
10223
10224                 public override string GetSignatureForError ()
10225                 {
10226                         return expr.GetSignatureForError () + "." + base.GetSignatureForError ();
10227                 }
10228
10229                 protected override void CloneTo (CloneContext clonectx, Expression t)
10230                 {
10231                         MemberAccess target = (MemberAccess) t;
10232
10233                         target.expr = expr.Clone (clonectx);
10234                 }
10235
10236                 public override object Accept (StructuralVisitor visitor)
10237                 {
10238                         return visitor.Visit (this);
10239                 }
10240         }
10241
10242         public class ConditionalMemberAccess : MemberAccess
10243         {
10244                 public ConditionalMemberAccess (Expression expr, string identifier, TypeArguments args, Location loc)
10245                         : base (expr, identifier, args, loc)
10246                 {
10247                 }
10248
10249                 public override bool HasConditionalAccess ()
10250                 {
10251                         return true;
10252                 }
10253         }
10254
10255         /// <summary>
10256         ///   Implements checked expressions
10257         /// </summary>
10258         public class CheckedExpr : Expression {
10259
10260                 public Expression Expr;
10261
10262                 public CheckedExpr (Expression e, Location l)
10263                 {
10264                         Expr = e;
10265                         loc = l;
10266                 }
10267
10268                 public override bool ContainsEmitWithAwait ()
10269                 {
10270                         return Expr.ContainsEmitWithAwait ();
10271                 }
10272
10273                 public override Expression CreateExpressionTree (ResolveContext ec)
10274                 {
10275                         using (ec.With (ResolveContext.Options.AllCheckStateFlags, true))
10276                                 return Expr.CreateExpressionTree (ec);
10277                 }
10278
10279                 protected override Expression DoResolve (ResolveContext ec)
10280                 {
10281                         using (ec.With (ResolveContext.Options.AllCheckStateFlags, true))
10282                                 Expr = Expr.Resolve (ec);
10283
10284                         if (Expr == null)
10285                                 return null;
10286
10287                         if (Expr is Constant || Expr is MethodGroupExpr || Expr is AnonymousMethodExpression || Expr is DefaultValueExpression)
10288                                 return Expr;
10289
10290                         eclass = Expr.eclass;
10291                         type = Expr.Type;
10292                         return this;
10293                 }
10294
10295                 public override void Emit (EmitContext ec)
10296                 {
10297                         using (ec.With (EmitContext.Options.CheckedScope, true))
10298                                 Expr.Emit (ec);
10299                 }
10300
10301                 public override void EmitBranchable (EmitContext ec, Label target, bool on_true)
10302                 {
10303                         using (ec.With (EmitContext.Options.CheckedScope, true))
10304                                 Expr.EmitBranchable (ec, target, on_true);
10305                 }
10306
10307                 public override void FlowAnalysis (FlowAnalysisContext fc)
10308                 {
10309                         Expr.FlowAnalysis (fc);
10310                 }
10311
10312                 public override SLE.Expression MakeExpression (BuilderContext ctx)
10313                 {
10314                         using (ctx.With (BuilderContext.Options.CheckedScope, true)) {
10315                                 return Expr.MakeExpression (ctx);
10316                         }
10317                 }
10318
10319                 protected override void CloneTo (CloneContext clonectx, Expression t)
10320                 {
10321                         CheckedExpr target = (CheckedExpr) t;
10322
10323                         target.Expr = Expr.Clone (clonectx);
10324                 }
10325
10326                 public override object Accept (StructuralVisitor visitor)
10327                 {
10328                         return visitor.Visit (this);
10329                 }
10330         }
10331
10332         /// <summary>
10333         ///   Implements the unchecked expression
10334         /// </summary>
10335         public class UnCheckedExpr : Expression {
10336
10337                 public Expression Expr;
10338
10339                 public UnCheckedExpr (Expression e, Location l)
10340                 {
10341                         Expr = e;
10342                         loc = l;
10343                 }
10344
10345                 public override bool ContainsEmitWithAwait ()
10346                 {
10347                         return Expr.ContainsEmitWithAwait ();
10348                 }
10349
10350                 public override Expression CreateExpressionTree (ResolveContext ec)
10351                 {
10352                         using (ec.With (ResolveContext.Options.AllCheckStateFlags, false))
10353                                 return Expr.CreateExpressionTree (ec);
10354                 }
10355
10356                 protected override Expression DoResolve (ResolveContext ec)
10357                 {
10358                         using (ec.With (ResolveContext.Options.AllCheckStateFlags, false))
10359                                 Expr = Expr.Resolve (ec);
10360
10361                         if (Expr == null)
10362                                 return null;
10363
10364                         if (Expr is Constant || Expr is MethodGroupExpr || Expr is AnonymousMethodExpression || Expr is DefaultValueExpression)
10365                                 return Expr;
10366
10367                         eclass = Expr.eclass;
10368                         type = Expr.Type;
10369                         return this;
10370                 }
10371
10372                 public override void Emit (EmitContext ec)
10373                 {
10374                         using (ec.With (EmitContext.Options.CheckedScope, false))
10375                                 Expr.Emit (ec);
10376                 }
10377
10378                 public override void EmitBranchable (EmitContext ec, Label target, bool on_true)
10379                 {
10380                         using (ec.With (EmitContext.Options.CheckedScope, false))
10381                                 Expr.EmitBranchable (ec, target, on_true);
10382                 }
10383
10384                 public override void FlowAnalysis (FlowAnalysisContext fc)
10385                 {
10386                         Expr.FlowAnalysis (fc);
10387                 }
10388
10389                 protected override void CloneTo (CloneContext clonectx, Expression t)
10390                 {
10391                         UnCheckedExpr target = (UnCheckedExpr) t;
10392
10393                         target.Expr = Expr.Clone (clonectx);
10394                 }
10395
10396                 public override object Accept (StructuralVisitor visitor)
10397                 {
10398                         return visitor.Visit (this);
10399                 }
10400         }
10401
10402         /// <summary>
10403         ///   An Element Access expression.
10404         ///
10405         ///   During semantic analysis these are transformed into
10406         ///   IndexerAccess, ArrayAccess or a PointerArithmetic.
10407         /// </summary>
10408         public class ElementAccess : Expression
10409         {
10410                 public Arguments Arguments;
10411                 public Expression Expr;
10412                 bool conditional_access_receiver;
10413
10414                 public ElementAccess (Expression e, Arguments args, Location loc)
10415                 {
10416                         Expr = e;
10417                         this.loc = loc;
10418                         this.Arguments = args;
10419                 }
10420
10421                 public bool ConditionalAccess { get; set; }
10422
10423                 public override Location StartLocation {
10424                         get {
10425                                 return Expr.StartLocation;
10426                         }
10427                 }
10428
10429                 public override bool ContainsEmitWithAwait ()
10430                 {
10431                         return Expr.ContainsEmitWithAwait () || Arguments.ContainsEmitWithAwait ();
10432                 }
10433
10434                 //
10435                 // We perform some simple tests, and then to "split" the emit and store
10436                 // code we create an instance of a different class, and return that.
10437                 //
10438                 Expression CreateAccessExpression (ResolveContext ec, bool conditionalAccessReceiver)
10439                 {
10440                         if (conditionalAccessReceiver)
10441                                 ec.Set (ResolveContext.Options.DontSetConditionalAccessReceiver);
10442
10443                         Expr = Expr.Resolve (ec);
10444
10445                         if (conditionalAccessReceiver)
10446                                 ec.With (ResolveContext.Options.DontSetConditionalAccessReceiver, false);
10447
10448                         if (Expr == null)
10449                                 return null;
10450
10451                         type = Expr.Type;
10452
10453                         if (ConditionalAccess && !IsNullPropagatingValid (type)) {
10454                                 Error_OperatorCannotBeApplied (ec, loc, "?", type);
10455                                 return null;
10456                         }
10457
10458                         if (type.IsArray) {
10459                                 var aa = new ArrayAccess (this, loc) {
10460                                         ConditionalAccess = ConditionalAccess,
10461                                 };
10462
10463                                 if (conditionalAccessReceiver)
10464                                         aa.SetConditionalAccessReceiver ();
10465
10466                                 return aa;
10467                         }
10468
10469                         if (type.IsPointer)
10470                                 return Expr.MakePointerAccess (ec, type, Arguments);
10471
10472                         FieldExpr fe = Expr as FieldExpr;
10473                         if (fe != null) {
10474                                 var ff = fe.Spec as FixedFieldSpec;
10475                                 if (ff != null) {
10476                                         return Expr.MakePointerAccess (ec, ff.ElementType, Arguments);
10477                                 }
10478                         }
10479
10480                         var indexers = MemberCache.FindMembers (type, MemberCache.IndexerNameAlias, false);
10481                         if (indexers != null || type.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
10482                                 var indexer = new IndexerExpr (indexers, type, this) {
10483                                         ConditionalAccess = ConditionalAccess
10484                                 };
10485
10486                                 if (conditionalAccessReceiver)
10487                                         indexer.SetConditionalAccessReceiver ();
10488
10489                                 return indexer;
10490                         }
10491
10492                         Error_CannotApplyIndexing (ec, type, loc);
10493
10494                         return null;
10495                 }
10496
10497                 public override Expression CreateExpressionTree (ResolveContext ec)
10498                 {
10499                         Arguments args = Arguments.CreateForExpressionTree (ec, Arguments,
10500                                 Expr.CreateExpressionTree (ec));
10501
10502                         return CreateExpressionFactoryCall (ec, "ArrayIndex", args);
10503                 }
10504
10505                 public static void Error_CannotApplyIndexing (ResolveContext rc, TypeSpec type, Location loc)
10506                 {
10507                         if (type != InternalType.ErrorType) {
10508                                 rc.Report.Error (21, loc, "Cannot apply indexing with [] to an expression of type `{0}'",
10509                                         type.GetSignatureForError ());
10510                         }
10511                 }
10512
10513                 public override bool HasConditionalAccess ()
10514                 {
10515                         return ConditionalAccess || Expr.HasConditionalAccess ();
10516                 }
10517
10518                 void ResolveConditionalAccessReceiver (ResolveContext rc)
10519                 {
10520                         if (!rc.HasSet (ResolveContext.Options.DontSetConditionalAccessReceiver) && HasConditionalAccess ()) {
10521                                 conditional_access_receiver = true;
10522                         }
10523                 }
10524
10525                 protected override Expression DoResolve (ResolveContext rc)
10526                 {
10527                         ResolveConditionalAccessReceiver (rc);
10528
10529                         var expr = CreateAccessExpression (rc, conditional_access_receiver);
10530                         if (expr == null)
10531                                 return null;
10532
10533                         return expr.Resolve (rc);
10534                 }
10535
10536                 public override Expression DoResolveLValue (ResolveContext ec, Expression rhs)
10537                 {
10538                         var res = CreateAccessExpression (ec, false);
10539                         if (res == null)
10540                                 return null;
10541
10542                         return res.ResolveLValue (ec, rhs);
10543                 }
10544
10545                 public override void Emit (EmitContext ec)
10546                 {
10547                         throw new Exception ("Should never be reached");
10548                 }
10549
10550                 public override void FlowAnalysis (FlowAnalysisContext fc)
10551                 {
10552                         Expr.FlowAnalysis (fc);
10553
10554                         Arguments.FlowAnalysis (fc);
10555                 }
10556
10557                 public override string GetSignatureForError ()
10558                 {
10559                         return Expr.GetSignatureForError ();
10560                 }
10561
10562                 protected override void CloneTo (CloneContext clonectx, Expression t)
10563                 {
10564                         ElementAccess target = (ElementAccess) t;
10565
10566                         target.Expr = Expr.Clone (clonectx);
10567                         if (Arguments != null)
10568                                 target.Arguments = Arguments.Clone (clonectx);
10569                 }
10570
10571                 public override object Accept (StructuralVisitor visitor)
10572                 {
10573                         return visitor.Visit (this);
10574                 }
10575         }
10576
10577         /// <summary>
10578         ///   Implements array access
10579         /// </summary>
10580         public class ArrayAccess : Expression, IDynamicAssign, IMemoryLocation {
10581                 //
10582                 // Points to our "data" repository
10583                 //
10584                 ElementAccess ea;
10585
10586                 LocalTemporary temp;
10587                 bool prepared;
10588                 bool? has_await_args;
10589                 bool conditional_access_receiver;
10590
10591                 public ArrayAccess (ElementAccess ea_data, Location l)
10592                 {
10593                         ea = ea_data;
10594                         loc = l;
10595                 }
10596
10597                 public bool ConditionalAccess { get; set; }
10598
10599                 public void AddressOf (EmitContext ec, AddressOp mode)
10600                 {
10601                         var ac = (ArrayContainer) ea.Expr.Type;
10602
10603                         if (!has_await_args.HasValue && ec.HasSet (BuilderContext.Options.AsyncBody) && ea.Arguments.ContainsEmitWithAwait ()) {
10604                                 LoadInstanceAndArguments (ec, false, true);
10605                         }
10606
10607                         LoadInstanceAndArguments (ec, false, false);
10608
10609                         if (ac.Element.IsGenericParameter && mode == AddressOp.Load)
10610                                 ec.Emit (OpCodes.Readonly);
10611
10612                         ec.EmitArrayAddress (ac);
10613                 }
10614
10615                 public override Expression CreateExpressionTree (ResolveContext ec)
10616                 {
10617                         if (ConditionalAccess)
10618                                 Error_NullShortCircuitInsideExpressionTree (ec);
10619
10620                         return ea.CreateExpressionTree (ec);
10621                 }
10622
10623                 public override bool ContainsEmitWithAwait ()
10624                 {
10625                         return ea.ContainsEmitWithAwait ();
10626                 }
10627
10628                 public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
10629                 {
10630                         if (HasConditionalAccess ())
10631                                 Error_NullPropagatingLValue (ec);
10632
10633                         return DoResolve (ec);
10634                 }
10635
10636                 protected override Expression DoResolve (ResolveContext ec)
10637                 {
10638                         // dynamic is used per argument in ConvertExpressionToArrayIndex case
10639                         bool dynamic;
10640                         ea.Arguments.Resolve (ec, out dynamic);
10641
10642                         var ac = ea.Expr.Type as ArrayContainer;
10643                         int rank = ea.Arguments.Count;
10644                         if (ac.Rank != rank) {
10645                                 ec.Report.Error (22, ea.Location, "Wrong number of indexes `{0}' inside [], expected `{1}'",
10646                                           rank.ToString (), ac.Rank.ToString ());
10647                                 return null;
10648                         }
10649
10650                         type = ac.Element;
10651                         if (type.IsPointer) {
10652                                 if (ec.CurrentIterator != null) {
10653                                         UnsafeInsideIteratorError (ec, ea.Location);
10654                                 } else if (!ec.IsUnsafe) {
10655                                         UnsafeError (ec, ea.Location);
10656                                 }
10657                         }
10658
10659                         if (conditional_access_receiver)
10660                                 type = LiftMemberType (ec, type);
10661
10662                         foreach (Argument a in ea.Arguments) {
10663                                 var na = a as NamedArgument;
10664                                 if (na != null)
10665                                         ElementAccess.Error_NamedArgument (na, ec.Report);
10666
10667                                 a.Expr = ConvertExpressionToArrayIndex (ec, a.Expr);
10668                         }
10669
10670                         eclass = ExprClass.Variable;
10671
10672                         return this;
10673                 }
10674
10675                 protected override void Error_NegativeArrayIndex (ResolveContext ec, Location loc)
10676                 {
10677                         ec.Report.Warning (251, 2, loc, "Indexing an array with a negative index (array indices always start at zero)");
10678                 }
10679
10680                 public override void FlowAnalysis (FlowAnalysisContext fc)
10681                 {
10682                         var da = conditional_access_receiver ? fc.BranchDefiniteAssignment () : null;
10683
10684                         ea.FlowAnalysis (fc);
10685
10686                         if (conditional_access_receiver)
10687                                 fc.DefiniteAssignment = da;
10688                 }
10689
10690                 public override bool HasConditionalAccess ()
10691                 {
10692                         return ConditionalAccess || ea.Expr.HasConditionalAccess ();
10693                 }
10694
10695                 //
10696                 // Load the array arguments into the stack.
10697                 //
10698                 void LoadInstanceAndArguments (EmitContext ec, bool duplicateArguments, bool prepareAwait)
10699                 {
10700                         if (prepareAwait) {
10701                                 ea.Expr = ea.Expr.EmitToField (ec);
10702                         } else {
10703                                 var ie = new InstanceEmitter (ea.Expr, false);
10704                                 ie.Emit (ec, ConditionalAccess);
10705
10706                                 if (duplicateArguments) {
10707                                         ec.Emit (OpCodes.Dup);
10708
10709                                         var copy = new LocalTemporary (ea.Expr.Type);
10710                                         copy.Store (ec);
10711                                         ea.Expr = copy;
10712                                 }
10713                         }
10714
10715                         var dup_args = ea.Arguments.Emit (ec, duplicateArguments, prepareAwait);
10716                         if (dup_args != null)
10717                                 ea.Arguments = dup_args;
10718                 }
10719
10720                 public void Emit (EmitContext ec, bool leave_copy)
10721                 {
10722                         if (prepared) {
10723                                 ec.EmitLoadFromPtr (type);
10724                         } else {
10725                                 if (!has_await_args.HasValue && ec.HasSet (BuilderContext.Options.AsyncBody) && ea.Arguments.ContainsEmitWithAwait ()) {
10726                                         LoadInstanceAndArguments (ec, false, true);
10727                                 }
10728
10729                                 if (conditional_access_receiver)
10730                                         ec.ConditionalAccess = new ConditionalAccessContext (type, ec.DefineLabel ());
10731
10732                                 var ac = (ArrayContainer) ea.Expr.Type;
10733                                 LoadInstanceAndArguments (ec, false, false);
10734                                 ec.EmitArrayLoad (ac);
10735
10736                                 if (conditional_access_receiver)
10737                                         ec.CloseConditionalAccess (type.IsNullableType && type != ac.Element ? type : null);
10738                         }
10739
10740                         if (leave_copy) {
10741                                 ec.Emit (OpCodes.Dup);
10742                                 temp = new LocalTemporary (this.type);
10743                                 temp.Store (ec);
10744                         }
10745                 }
10746
10747                 public override void Emit (EmitContext ec)
10748                 {
10749                         Emit (ec, false);
10750                 }
10751
10752                 public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool isCompound)
10753                 {
10754                         var ac = (ArrayContainer) ea.Expr.Type;
10755                         TypeSpec t = source.Type;
10756
10757                         has_await_args = ec.HasSet (BuilderContext.Options.AsyncBody) && (ea.Arguments.ContainsEmitWithAwait () || source.ContainsEmitWithAwait ());
10758
10759                         //
10760                         // When we are dealing with a struct, get the address of it to avoid value copy
10761                         // Same cannot be done for reference type because array covariance and the
10762                         // check in ldelema requires to specify the type of array element stored at the index
10763                         //
10764                         if (t.IsStruct && ((isCompound && !(source is DynamicExpressionStatement)) || !BuiltinTypeSpec.IsPrimitiveType (t))) {
10765                                 LoadInstanceAndArguments (ec, false, has_await_args.Value);
10766
10767                                 if (has_await_args.Value) {
10768                                         if (source.ContainsEmitWithAwait ()) {
10769                                                 source = source.EmitToField (ec);
10770                                                 isCompound = false;
10771                                                 prepared = true;
10772                                         }
10773
10774                                         LoadInstanceAndArguments (ec, isCompound, false);
10775                                 } else {
10776                                         prepared = true;
10777                                 }
10778
10779                                 ec.EmitArrayAddress (ac);
10780
10781                                 if (isCompound) {
10782                                         ec.Emit (OpCodes.Dup);
10783                                         prepared = true;
10784                                 }
10785                         } else {
10786                                 LoadInstanceAndArguments (ec, isCompound, has_await_args.Value);
10787
10788                                 if (has_await_args.Value) {
10789                                         if (source.ContainsEmitWithAwait ())
10790                                                 source = source.EmitToField (ec);
10791
10792                                         LoadInstanceAndArguments (ec, false, false);
10793                                 }
10794                         }
10795
10796                         source.Emit (ec);
10797
10798                         if (isCompound) {
10799                                 var lt = ea.Expr as LocalTemporary;
10800                                 if (lt != null)
10801                                         lt.Release (ec);
10802                         }
10803
10804                         if (leave_copy) {
10805                                 ec.Emit (OpCodes.Dup);
10806                                 temp = new LocalTemporary (this.type);
10807                                 temp.Store (ec);
10808                         }
10809
10810                         if (prepared) {
10811                                 ec.EmitStoreFromPtr (t);
10812                         } else {
10813                                 ec.EmitArrayStore (ac);
10814                         }
10815
10816                         if (temp != null) {
10817                                 temp.Emit (ec);
10818                                 temp.Release (ec);
10819                         }
10820                 }
10821
10822                 public override Expression EmitToField (EmitContext ec)
10823                 {
10824                         //
10825                         // Have to be specialized for arrays to get access to
10826                         // underlying element. Instead of another result copy we
10827                         // need direct access to element
10828                         //
10829                         // Consider:
10830                         //
10831                         // CallRef (ref a[await Task.Factory.StartNew (() => 1)]);
10832                         //
10833                         ea.Expr = ea.Expr.EmitToField (ec);
10834                         ea.Arguments = ea.Arguments.Emit (ec, false, true);
10835                         return this;
10836                 }
10837
10838                 public SLE.Expression MakeAssignExpression (BuilderContext ctx, Expression source)
10839                 {
10840                         return SLE.Expression.ArrayAccess (ea.Expr.MakeExpression (ctx), MakeExpressionArguments (ctx));
10841                 }
10842
10843                 public override SLE.Expression MakeExpression (BuilderContext ctx)
10844                 {
10845                         return SLE.Expression.ArrayIndex (ea.Expr.MakeExpression (ctx), MakeExpressionArguments (ctx));
10846                 }
10847
10848                 SLE.Expression[] MakeExpressionArguments (BuilderContext ctx)
10849                 {
10850                         using (ctx.With (BuilderContext.Options.CheckedScope, true)) {
10851                                 return Arguments.MakeExpression (ea.Arguments, ctx);
10852                         }
10853                 }
10854
10855                 public void SetConditionalAccessReceiver ()
10856                 {
10857                         conditional_access_receiver = true;
10858                 }
10859         }
10860
10861         //
10862         // Indexer access expression
10863         //
10864         class IndexerExpr : PropertyOrIndexerExpr<IndexerSpec>, OverloadResolver.IBaseMembersProvider
10865         {
10866                 IList<MemberSpec> indexers;
10867                 Arguments arguments;
10868                 TypeSpec queried_type;
10869
10870                 public IndexerExpr (IList<MemberSpec> indexers, TypeSpec queriedType, ElementAccess ea)
10871                         : this (indexers, queriedType, ea.Expr, ea.Arguments, ea.Location)
10872                 {
10873                 }
10874
10875                 public IndexerExpr (IList<MemberSpec> indexers, TypeSpec queriedType, Expression instance, Arguments args, Location loc)
10876                         : base (loc)
10877                 {
10878                         this.indexers = indexers;
10879                         this.queried_type = queriedType;
10880                         this.InstanceExpression = instance;
10881                         this.arguments = args;
10882                 }
10883
10884                 #region Properties
10885
10886                 protected override Arguments Arguments {
10887                         get {
10888                                 return arguments;
10889                         }
10890                         set {
10891                                 arguments = value;
10892                         }
10893                 }
10894
10895                 protected override TypeSpec DeclaringType {
10896                         get {
10897                                 return best_candidate.DeclaringType;
10898                         }
10899                 }
10900
10901                 public override bool IsInstance {
10902                         get {
10903                                 return true;
10904                         }
10905                 }
10906
10907                 public override bool IsStatic {
10908                         get {
10909                                 return false;
10910                         }
10911                 }
10912
10913                 public override string KindName {
10914                         get { return "indexer"; }
10915                 }
10916
10917                 public override string Name {
10918                         get {
10919                                 return "this";
10920                         }
10921                 }
10922
10923                 #endregion
10924
10925                 public override bool ContainsEmitWithAwait ()
10926                 {
10927                         return base.ContainsEmitWithAwait () || arguments.ContainsEmitWithAwait ();
10928                 }
10929
10930                 public override Expression CreateExpressionTree (ResolveContext ec)
10931                 {
10932                         if (ConditionalAccess) {
10933                                 Error_NullShortCircuitInsideExpressionTree (ec);
10934                         }
10935
10936                         Arguments args = Arguments.CreateForExpressionTree (ec, arguments,
10937                                 InstanceExpression.CreateExpressionTree (ec),
10938                                 new TypeOfMethod (Getter, loc));
10939
10940                         return CreateExpressionFactoryCall (ec, "Call", args);
10941                 }
10942
10943                 public override void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool isCompound)
10944                 {
10945                         LocalTemporary await_source_arg = null;
10946
10947                         if (isCompound) {
10948                                 emitting_compound_assignment = true;
10949                                 if (source is DynamicExpressionStatement) {
10950                                         Emit (ec, false);
10951                                 } else {
10952                                         source.Emit (ec);
10953                                 }
10954                                 emitting_compound_assignment = false;
10955
10956                                 if (has_await_arguments) {
10957                                         await_source_arg = new LocalTemporary (Type);
10958                                         await_source_arg.Store (ec);
10959
10960                                         arguments.Add (new Argument (await_source_arg));
10961
10962                                         if (leave_copy) {
10963                                                 temp = await_source_arg;
10964                                         }
10965
10966                                         has_await_arguments = false;
10967                                 } else {
10968                                         arguments = null;
10969
10970                                         if (leave_copy) {
10971                                                 ec.Emit (OpCodes.Dup);
10972                                                 temp = new LocalTemporary (Type);
10973                                                 temp.Store (ec);
10974                                         }
10975                                 }
10976                         } else {
10977                                 if (leave_copy) {
10978                                         if (ec.HasSet (BuilderContext.Options.AsyncBody) && (arguments.ContainsEmitWithAwait () || source.ContainsEmitWithAwait ())) {
10979                                                 source = source.EmitToField (ec);
10980                                         } else {
10981                                                 temp = new LocalTemporary (Type);
10982                                                 source.Emit (ec);
10983                                                 temp.Store (ec);
10984                                                 source = temp;
10985                                         }
10986                                 }
10987
10988                                 arguments.Add (new Argument (source));
10989                         }
10990
10991                         var call = new CallEmitter ();
10992                         call.InstanceExpression = InstanceExpression;
10993                         if (arguments == null)
10994                                 call.InstanceExpressionOnStack = true;
10995
10996                         call.Emit (ec, Setter, arguments, loc);
10997
10998                         if (temp != null) {
10999                                 temp.Emit (ec);
11000                                 temp.Release (ec);
11001                         } else if (leave_copy) {
11002                                 source.Emit (ec);
11003                         }
11004
11005                         if (await_source_arg != null) {
11006                                 await_source_arg.Release (ec);
11007                         }
11008                 }
11009
11010                 public override void FlowAnalysis (FlowAnalysisContext fc)
11011                 {
11012                         var da = conditional_access_receiver ? fc.BranchDefiniteAssignment () : null;
11013
11014                         base.FlowAnalysis (fc);
11015                         arguments.FlowAnalysis (fc);
11016
11017                         if (conditional_access_receiver)
11018                                 fc.DefiniteAssignment = da;
11019                 }
11020
11021                 public override string GetSignatureForError ()
11022                 {
11023                         return best_candidate.GetSignatureForError ();
11024                 }
11025
11026                 public override SLE.Expression MakeAssignExpression (BuilderContext ctx, Expression source)
11027                 {
11028 #if STATIC
11029                         throw new NotSupportedException ();
11030 #else
11031                         var value = new[] { source.MakeExpression (ctx) };
11032                         var args = Arguments.MakeExpression (arguments, ctx).Concat (value);
11033                         return SLE.Expression.Block (
11034                                         SLE.Expression.Call (InstanceExpression.MakeExpression (ctx), (MethodInfo) Setter.GetMetaInfo (), args),
11035                                         value [0]);
11036 #endif
11037                 }
11038
11039                 public override SLE.Expression MakeExpression (BuilderContext ctx)
11040                 {
11041 #if STATIC
11042                         return base.MakeExpression (ctx);
11043 #else
11044                         var args = Arguments.MakeExpression (arguments, ctx);
11045                         return SLE.Expression.Call (InstanceExpression.MakeExpression (ctx), (MethodInfo) Getter.GetMetaInfo (), args);
11046 #endif
11047                 }
11048
11049                 protected override Expression OverloadResolve (ResolveContext rc, Expression right_side)
11050                 {
11051                         if (best_candidate != null)
11052                                 return this;
11053
11054                         eclass = ExprClass.IndexerAccess;
11055
11056                         bool dynamic;
11057                         using (rc.With (ResolveContext.Options.DontSetConditionalAccessReceiver, false)) {
11058                                 arguments.Resolve (rc, out dynamic);
11059                         }
11060
11061                         if (indexers == null && InstanceExpression.Type.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
11062                                 dynamic = true;
11063                         } else {
11064                                 var res = new OverloadResolver (indexers, OverloadResolver.Restrictions.None, loc);
11065                                 res.BaseMembersProvider = this;
11066                                 res.InstanceQualifier = this;
11067
11068                                 // TODO: Do I need 2 argument sets?
11069                                 best_candidate = res.ResolveMember<IndexerSpec> (rc, ref arguments);
11070                                 if (best_candidate != null)
11071                                         type = res.BestCandidateReturnType;
11072                                 else if (!res.BestCandidateIsDynamic)
11073                                         return null;
11074                         }
11075
11076                         //
11077                         // It has dynamic arguments
11078                         //
11079                         if (dynamic) {
11080                                 Arguments args = new Arguments (arguments.Count + 1);
11081                                 if (IsBase) {
11082                                         rc.Report.Error (1972, loc,
11083                                                 "The indexer base access cannot be dynamically dispatched. Consider casting the dynamic arguments or eliminating the base access");
11084                                 } else {
11085                                         args.Add (new Argument (InstanceExpression));
11086                                 }
11087                                 args.AddRange (arguments);
11088
11089                                 best_candidate = null;
11090                                 return new DynamicIndexBinder (args, conditional_access_receiver, ConditionalAccess, loc);
11091                         }
11092
11093                         //
11094                         // Try to avoid resolving left expression again
11095                         //
11096                         if (right_side != null)
11097                                 ResolveInstanceExpression (rc, right_side);
11098
11099                         return this;
11100                 }
11101
11102                 protected override void CloneTo (CloneContext clonectx, Expression t)
11103                 {
11104                         IndexerExpr target = (IndexerExpr) t;
11105
11106                         if (arguments != null)
11107                                 target.arguments = arguments.Clone (clonectx);
11108                 }
11109
11110                 public void SetConditionalAccessReceiver ()
11111                 {
11112                         conditional_access_receiver = true;
11113                 }
11114
11115                 public override void SetTypeArguments (ResolveContext ec, TypeArguments ta)
11116                 {
11117                         Error_TypeArgumentsCannotBeUsed (ec, "indexer", GetSignatureForError (), loc);
11118                 }
11119
11120                 #region IBaseMembersProvider Members
11121
11122                 IList<MemberSpec> OverloadResolver.IBaseMembersProvider.GetBaseMembers (TypeSpec type)
11123                 {
11124                         var baseType = type.BaseType;
11125                         var members = baseType == null ? null : MemberCache.FindMembers (baseType, MemberCache.IndexerNameAlias, false);
11126
11127                         if (members == null && !type.IsInterface) {
11128                                 var tps = queried_type as TypeParameterSpec;
11129                                 if (tps != null)
11130                                         members = MemberCache.FindInterfaceMembers (tps, MemberCache.IndexerNameAlias);
11131                         }
11132
11133                         return members;
11134                 }
11135
11136                 IParametersMember OverloadResolver.IBaseMembersProvider.GetOverrideMemberParameters (MemberSpec member)
11137                 {
11138                         if (queried_type == member.DeclaringType)
11139                                 return null;
11140
11141                         var filter = new MemberFilter (MemberCache.IndexerNameAlias, 0, MemberKind.Indexer, ((IndexerSpec) member).Parameters, null);
11142                         return MemberCache.FindMember (queried_type, filter, BindingRestriction.InstanceOnly | BindingRestriction.OverrideOnly) as IParametersMember;
11143                 }
11144
11145                 MethodGroupExpr OverloadResolver.IBaseMembersProvider.LookupExtensionMethod (ResolveContext rc)
11146                 {
11147                         return null;
11148                 }
11149
11150                 #endregion
11151         }
11152
11153         //
11154         // A base access expression
11155         //
11156         public class BaseThis : This
11157         {
11158                 public BaseThis (Location loc)
11159                         : base (loc)
11160                 {
11161                 }
11162
11163                 public BaseThis (TypeSpec type, Location loc)
11164                         : base (loc)
11165                 {
11166                         this.type = type;
11167                         eclass = ExprClass.Variable;
11168                 }
11169
11170                 #region Properties
11171
11172                 public override string Name {
11173                         get {
11174                                 return "base";
11175                         }
11176                 }
11177
11178                 #endregion
11179
11180                 public override Expression CreateExpressionTree (ResolveContext ec)
11181                 {
11182                         ec.Report.Error (831, loc, "An expression tree may not contain a base access");
11183                         return base.CreateExpressionTree (ec);
11184                 }
11185
11186                 public override void Emit (EmitContext ec)
11187                 {
11188                         base.Emit (ec);
11189
11190                         if (type == ec.Module.Compiler.BuiltinTypes.ValueType) {
11191                                 var context_type = ec.CurrentType;
11192                                 ec.Emit (OpCodes.Ldobj, context_type);
11193                                 ec.Emit (OpCodes.Box, context_type);
11194                         }
11195                 }
11196
11197                 protected override void Error_ThisNotAvailable (ResolveContext ec)
11198                 {
11199                         if (ec.IsStatic) {
11200                                 ec.Report.Error (1511, loc, "Keyword `base' is not available in a static method");
11201                         } else {
11202                                 ec.Report.Error (1512, loc, "Keyword `base' is not available in the current context");
11203                         }
11204                 }
11205
11206                 public override void ResolveBase (ResolveContext ec)
11207                 {
11208                         base.ResolveBase (ec);
11209                         type = ec.CurrentType.BaseType;
11210                 }
11211
11212                 public override object Accept (StructuralVisitor visitor)
11213                 {
11214                         return visitor.Visit (this);
11215                 }
11216         }
11217
11218         /// <summary>
11219         ///   This class exists solely to pass the Type around and to be a dummy
11220         ///   that can be passed to the conversion functions (this is used by
11221         ///   foreach implementation to typecast the object return value from
11222         ///   get_Current into the proper type.  All code has been generated and
11223         ///   we only care about the side effect conversions to be performed
11224         ///
11225         ///   This is also now used as a placeholder where a no-action expression
11226         ///   is needed (the `New' class).
11227         /// </summary>
11228         public class EmptyExpression : Expression
11229         {
11230                 sealed class OutAccessExpression : EmptyExpression
11231                 {
11232                         public OutAccessExpression (TypeSpec t)
11233                                 : base (t)
11234                         {
11235                         }
11236
11237                         public override Expression DoResolveLValue (ResolveContext rc, Expression right_side)
11238                         {
11239                                 rc.Report.Error (206, right_side.Location,
11240                                         "A property, indexer or dynamic member access may not be passed as `ref' or `out' parameter");
11241
11242                                 return null;
11243                         }
11244                 }
11245
11246                 public static readonly EmptyExpression LValueMemberAccess = new EmptyExpression (InternalType.FakeInternalType);
11247                 public static readonly EmptyExpression LValueMemberOutAccess = new EmptyExpression (InternalType.FakeInternalType);
11248                 public static readonly EmptyExpression UnaryAddress = new EmptyExpression (InternalType.FakeInternalType);
11249                 public static readonly EmptyExpression EventAddition = new EmptyExpression (InternalType.FakeInternalType);
11250                 public static readonly EmptyExpression EventSubtraction = new EmptyExpression (InternalType.FakeInternalType);
11251                 public static readonly EmptyExpression MissingValue = new EmptyExpression (InternalType.FakeInternalType);
11252                 public static readonly Expression Null = new EmptyExpression (InternalType.FakeInternalType);
11253                 public static readonly EmptyExpression OutAccess = new OutAccessExpression (InternalType.FakeInternalType);
11254
11255                 public EmptyExpression (TypeSpec t)
11256                 {
11257                         type = t;
11258                         eclass = ExprClass.Value;
11259                         loc = Location.Null;
11260                 }
11261
11262                 protected override void CloneTo (CloneContext clonectx, Expression target)
11263                 {
11264                 }
11265
11266                 public override bool ContainsEmitWithAwait ()
11267                 {
11268                         return false;
11269                 }
11270
11271                 public override Expression CreateExpressionTree (ResolveContext ec)
11272                 {
11273                         throw new NotSupportedException ("ET");
11274                 }
11275
11276                 protected override Expression DoResolve (ResolveContext ec)
11277                 {
11278                         return this;
11279                 }
11280
11281                 public override void Emit (EmitContext ec)
11282                 {
11283                         // nothing, as we only exist to not do anything.
11284                 }
11285
11286                 public override void EmitBranchable (EmitContext ec, Label target, bool on_true)
11287                 {
11288                 }
11289
11290                 public override void EmitSideEffect (EmitContext ec)
11291                 {
11292                 }
11293
11294                 public override object Accept (StructuralVisitor visitor)
11295                 {
11296                         return visitor.Visit (this);
11297                 }
11298         }
11299
11300         sealed class EmptyAwaitExpression : EmptyExpression
11301         {
11302                 public EmptyAwaitExpression (TypeSpec type)
11303                         : base (type)
11304                 {
11305                 }
11306
11307                 public override bool ContainsEmitWithAwait ()
11308                 {
11309                         return true;
11310                 }
11311         }
11312
11313         //
11314         // Empty statement expression
11315         //
11316         public sealed class EmptyExpressionStatement : ExpressionStatement
11317         {
11318                 public static readonly EmptyExpressionStatement Instance = new EmptyExpressionStatement ();
11319
11320                 private EmptyExpressionStatement ()
11321                 {
11322                         loc = Location.Null;
11323                 }
11324
11325                 public override bool ContainsEmitWithAwait ()
11326                 {
11327                         return false;
11328                 }
11329
11330                 public override Expression CreateExpressionTree (ResolveContext ec)
11331                 {
11332                         return null;
11333                 }
11334
11335                 public override void EmitStatement (EmitContext ec)
11336                 {
11337                         // Do nothing
11338                 }
11339
11340                 protected override Expression DoResolve (ResolveContext ec)
11341                 {
11342                         eclass = ExprClass.Value;
11343                         type = ec.BuiltinTypes.Object;
11344                         return this;
11345                 }
11346
11347                 public override void Emit (EmitContext ec)
11348                 {
11349                         // Do nothing
11350                 }
11351
11352                 public override object Accept (StructuralVisitor visitor)
11353                 {
11354                         return visitor.Visit (this);
11355                 }
11356         }
11357
11358         public class ErrorExpression : EmptyExpression
11359         {
11360                 public static readonly ErrorExpression Instance = new ErrorExpression ();
11361
11362                 private ErrorExpression ()
11363                         : base (InternalType.ErrorType)
11364                 {
11365                 }
11366
11367                 public override Expression CreateExpressionTree (ResolveContext ec)
11368                 {
11369                         return this;
11370                 }
11371
11372                 public override Expression DoResolveLValue (ResolveContext rc, Expression right_side)
11373                 {
11374                         return this;
11375                 }
11376
11377                 public override void Error_ValueAssignment (ResolveContext rc, Expression rhs)
11378                 {
11379                 }
11380
11381                 public override void Error_UnexpectedKind (ResolveContext ec, ResolveFlags flags, Location loc)
11382                 {
11383                 }
11384
11385                 public override void Error_ValueCannotBeConverted (ResolveContext ec, TypeSpec target, bool expl)
11386                 {
11387                 }
11388
11389                 public override void Error_OperatorCannotBeApplied (ResolveContext rc, Location loc, string oper, TypeSpec t)
11390                 {
11391                 }
11392
11393                 public override object Accept (StructuralVisitor visitor)
11394                 {
11395                         return visitor.Visit (this);
11396                 }
11397         }
11398
11399         public class UserCast : Expression {
11400                 MethodSpec method;
11401                 Expression source;
11402
11403                 public UserCast (MethodSpec method, Expression source, Location l)
11404                 {
11405                         if (source == null)
11406                                 throw new ArgumentNullException ("source");
11407
11408                         this.method = method;
11409                         this.source = source;
11410                         type = method.ReturnType;
11411                         loc = l;
11412                 }
11413
11414                 public Expression Source {
11415                         get {
11416                                 return source;
11417                         }
11418                         set {
11419                                 source = value;
11420                         }
11421                 }
11422
11423                 public override bool ContainsEmitWithAwait ()
11424                 {
11425                         return source.ContainsEmitWithAwait ();
11426                 }
11427
11428                 public override Expression CreateExpressionTree (ResolveContext ec)
11429                 {
11430                         Arguments args = new Arguments (3);
11431                         args.Add (new Argument (source.CreateExpressionTree (ec)));
11432                         args.Add (new Argument (new TypeOf (type, loc)));
11433                         args.Add (new Argument (new TypeOfMethod (method, loc)));
11434                         return CreateExpressionFactoryCall (ec, "Convert", args);
11435                 }
11436
11437                 protected override Expression DoResolve (ResolveContext ec)
11438                 {
11439                         method.CheckObsoleteness (ec, source.Location);
11440
11441                         eclass = ExprClass.Value;
11442                         return this;
11443                 }
11444
11445                 public override void Emit (EmitContext ec)
11446                 {
11447                         source.Emit (ec);
11448                         ec.MarkCallEntry (loc);
11449                         ec.Emit (OpCodes.Call, method);
11450                 }
11451
11452                 public override void FlowAnalysis (FlowAnalysisContext fc)
11453                 {
11454                         source.FlowAnalysis (fc);
11455                 }
11456
11457                 public override string GetSignatureForError ()
11458                 {
11459                         return TypeManager.CSharpSignature (method);
11460                 }
11461
11462                 public override SLE.Expression MakeExpression (BuilderContext ctx)
11463                 {
11464 #if STATIC
11465                         return base.MakeExpression (ctx);
11466 #else
11467                         return SLE.Expression.Convert (source.MakeExpression (ctx), type.GetMetaInfo (), (MethodInfo) method.GetMetaInfo ());
11468 #endif
11469                 }
11470         }
11471
11472         //
11473         // Holds additional type specifiers like ?, *, []
11474         //
11475         public class ComposedTypeSpecifier
11476         {
11477                 public static readonly ComposedTypeSpecifier SingleDimension = new ComposedTypeSpecifier (1, Location.Null);
11478
11479                 public readonly int Dimension;
11480                 public readonly Location Location;
11481
11482                 public ComposedTypeSpecifier (int specifier, Location loc)
11483                 {
11484                         this.Dimension = specifier;
11485                         this.Location = loc;
11486                 }
11487
11488                 #region Properties
11489                 public bool IsNullable {
11490                         get {
11491                                 return Dimension == -1;
11492                         }
11493                 }
11494
11495                 public bool IsPointer {
11496                         get {
11497                                 return Dimension == -2;
11498                         }
11499                 }
11500
11501                 public ComposedTypeSpecifier Next { get; set; }
11502
11503                 #endregion
11504
11505                 public static ComposedTypeSpecifier CreateArrayDimension (int dimension, Location loc)
11506                 {
11507                         return new ComposedTypeSpecifier (dimension, loc);
11508                 }
11509
11510                 public static ComposedTypeSpecifier CreateNullable (Location loc)
11511                 {
11512                         return new ComposedTypeSpecifier (-1, loc);
11513                 }
11514
11515                 public static ComposedTypeSpecifier CreatePointer (Location loc)
11516                 {
11517                         return new ComposedTypeSpecifier (-2, loc);
11518                 }
11519
11520                 public string GetSignatureForError ()
11521                 {
11522                         string s =
11523                                 IsPointer ? "*" :
11524                                 IsNullable ? "?" :
11525                                 ArrayContainer.GetPostfixSignature (Dimension);
11526
11527                         return Next != null ? s + Next.GetSignatureForError () : s;
11528                 }
11529         }
11530
11531         // <summary>
11532         //   This class is used to "construct" the type during a typecast
11533         //   operation.  Since the Type.GetType class in .NET can parse
11534         //   the type specification, we just use this to construct the type
11535         //   one bit at a time.
11536         // </summary>
11537         public class ComposedCast : TypeExpr {
11538                 FullNamedExpression left;
11539                 ComposedTypeSpecifier spec;
11540
11541                 public ComposedCast (FullNamedExpression left, ComposedTypeSpecifier spec)
11542                 {
11543                         if (spec == null)
11544                                 throw new ArgumentNullException ("spec");
11545
11546                         this.left = left;
11547                         this.spec = spec;
11548                         this.loc = left.Location;
11549                 }
11550
11551                 public override TypeSpec ResolveAsType (IMemberContext ec, bool allowUnboundTypeArguments)
11552                 {
11553                         type = left.ResolveAsType (ec);
11554                         if (type == null)
11555                                 return null;
11556
11557                         eclass = ExprClass.Type;
11558
11559                         var single_spec = spec;
11560
11561                         if (single_spec.IsNullable) {
11562                                 type = new Nullable.NullableType (type, loc).ResolveAsType (ec);
11563                                 if (type == null)
11564                                         return null;
11565
11566                                 single_spec = single_spec.Next;
11567                         } else if (single_spec.IsPointer) {
11568                                 //
11569                                 // Declared fields cannot have unmanaged check done before all types are defined
11570                                 //
11571                                 if (!(ec.CurrentMemberDefinition is Field) && !TypeManager.VerifyUnmanaged (ec.Module, type, loc))
11572                                         return null;
11573
11574                                 var rc = ec as ResolveContext;
11575                                 if (rc?.CurrentIterator != null) {
11576                                         UnsafeInsideIteratorError (ec.Module.Compiler.Report, loc);
11577                                 } else if (!ec.IsUnsafe) {
11578                                         UnsafeError (ec.Module.Compiler.Report, loc);
11579                                 }
11580
11581                                 do {
11582                                         type = PointerContainer.MakeType (ec.Module, type);
11583                                         single_spec = single_spec.Next;
11584                                 } while (single_spec != null && single_spec.IsPointer);
11585                         }
11586
11587                         if (single_spec != null && single_spec.Dimension > 0) {
11588                                 if (type.IsSpecialRuntimeType) {
11589                                         ec.Module.Compiler.Report.Error (611, loc, "Array elements cannot be of type `{0}'", type.GetSignatureForError ());
11590                                 } else if (type.IsStatic) {
11591                                         ec.Module.Compiler.Report.SymbolRelatedToPreviousError (type);
11592                                         ec.Module.Compiler.Report.Error (719, loc, "Array elements cannot be of static type `{0}'",
11593                                                 type.GetSignatureForError ());
11594                                 } else {
11595                                         MakeArray (ec.Module, single_spec);
11596                                 }
11597                         }
11598
11599                         return type;
11600                 }
11601
11602                 void MakeArray (ModuleContainer module, ComposedTypeSpecifier spec)
11603                 {
11604                         if (spec.Next != null)
11605                                 MakeArray (module, spec.Next);
11606
11607                         type = ArrayContainer.MakeType (module, type, spec.Dimension);
11608                 }
11609
11610                 public override string GetSignatureForError ()
11611                 {
11612                         return left.GetSignatureForError () + spec.GetSignatureForError ();
11613                 }
11614
11615                 public override object Accept (StructuralVisitor visitor)
11616                 {
11617                         return visitor.Visit (this);
11618                 }
11619         }
11620
11621         class ReferenceTypeExpr : TypeExpr
11622         {
11623                 FullNamedExpression element;
11624
11625                 public ReferenceTypeExpr (FullNamedExpression element, Location loc)
11626                 {
11627                         this.element = element;
11628                         this.loc = loc;
11629                 }
11630
11631                 public override TypeSpec ResolveAsType (IMemberContext mc, bool allowUnboundTypeArguments = false)
11632                 {
11633                         type = element.ResolveAsType (mc);
11634                         if (type == null)
11635                                 return null;
11636
11637                         eclass = ExprClass.Type;
11638                         type = ReferenceContainer.MakeType (mc.Module, type);
11639
11640                         return type;
11641                 }
11642
11643                 public override string GetSignatureForError ()
11644                 {
11645                         return "ref " + element.GetSignatureForError ();
11646                 }
11647
11648                 public override object Accept (StructuralVisitor visitor)
11649                 {
11650                         return visitor.Visit (this);
11651                 }
11652         }
11653
11654         class FixedBufferPtr : Expression
11655         {
11656                 readonly Expression array;
11657
11658                 public FixedBufferPtr (Expression array, TypeSpec array_type, Location l)
11659                 {
11660                         this.type = array_type;
11661                         this.array = array;
11662                         this.loc = l;
11663                 }
11664
11665                 public override bool ContainsEmitWithAwait ()
11666                 {
11667                         throw new NotImplementedException ();
11668                 }
11669
11670                 public override Expression CreateExpressionTree (ResolveContext ec)
11671                 {
11672                         Error_PointerInsideExpressionTree (ec);
11673                         return null;
11674                 }
11675
11676                 public override void Emit(EmitContext ec)
11677                 {
11678                         array.Emit (ec);
11679                 }
11680
11681                 protected override Expression DoResolve (ResolveContext ec)
11682                 {
11683                         type = PointerContainer.MakeType (ec.Module, type);
11684                         eclass = ExprClass.Value;
11685                         return this;
11686                 }
11687         }
11688
11689
11690         //
11691         // This class is used to represent the address of an array, used
11692         // only by the Fixed statement, this generates "&a [0]" construct
11693         // for fixed (char *pa = a)
11694         //
11695         class ArrayPtr : FixedBufferPtr
11696         {
11697                 public ArrayPtr (Expression array, TypeSpec array_type, Location l):
11698                         base (array, array_type, l)
11699                 {
11700                 }
11701
11702                 public override void Emit (EmitContext ec)
11703                 {
11704                         base.Emit (ec);
11705
11706                         ec.EmitInt (0);
11707                         ec.Emit (OpCodes.Ldelema, ((PointerContainer) type).Element);
11708                 }
11709         }
11710
11711         //
11712         // Encapsulates a conversion rules required for array indexes
11713         //
11714         public class ArrayIndexCast : TypeCast
11715         {
11716                 public ArrayIndexCast (Expression expr, TypeSpec returnType)
11717                         : base (expr, returnType)
11718                 {
11719                         if (expr.Type == returnType) // int -> int
11720                                 throw new ArgumentException ("unnecessary array index conversion");
11721                 }
11722
11723                 public override Expression CreateExpressionTree (ResolveContext ec)
11724                 {
11725                         using (ec.Set (ResolveContext.Options.CheckedScope)) {
11726                                 return base.CreateExpressionTree (ec);
11727                         }
11728                 }
11729
11730                 public override void Emit (EmitContext ec)
11731                 {
11732                         child.Emit (ec);
11733
11734                         switch (child.Type.BuiltinType) {
11735                         case BuiltinTypeSpec.Type.UInt:
11736                                 ec.Emit (OpCodes.Conv_U);
11737                                 break;
11738                         case BuiltinTypeSpec.Type.Long:
11739                                 ec.Emit (OpCodes.Conv_Ovf_I);
11740                                 break;
11741                         case BuiltinTypeSpec.Type.ULong:
11742                                 ec.Emit (OpCodes.Conv_Ovf_I_Un);
11743                                 break;
11744                         default:
11745                                 throw new InternalErrorException ("Cannot emit cast to unknown array element type", type);
11746                         }
11747                 }
11748         }
11749
11750         //
11751         // Implements the `stackalloc' keyword
11752         //
11753         public class StackAlloc : Expression {
11754                 TypeSpec otype;
11755                 Expression texpr;
11756                 Expression count;
11757
11758                 public StackAlloc (Expression type, Expression count, Location l)
11759                 {
11760                         texpr = type;
11761                         this.count = count;
11762                         loc = l;
11763                 }
11764
11765                 public Expression TypeExpression {
11766                         get {
11767                                 return texpr;
11768                         }
11769                 }
11770
11771                 public Expression CountExpression {
11772                         get {
11773                                 return this.count;
11774                         }
11775                 }
11776
11777                 public override bool ContainsEmitWithAwait ()
11778                 {
11779                         return false;
11780                 }
11781
11782                 public override Expression CreateExpressionTree (ResolveContext ec)
11783                 {
11784                         throw new NotSupportedException ("ET");
11785                 }
11786
11787                 protected override Expression DoResolve (ResolveContext ec)
11788                 {
11789                         count = count.Resolve (ec);
11790                         if (count == null)
11791                                 return null;
11792
11793                         if (count.Type.BuiltinType != BuiltinTypeSpec.Type.UInt){
11794                                 count = Convert.ImplicitConversionRequired (ec, count, ec.BuiltinTypes.Int, loc);
11795                                 if (count == null)
11796                                         return null;
11797                         }
11798
11799                         Constant c = count as Constant;
11800                         if (c != null && c.IsNegative) {
11801                                 ec.Report.Error (247, loc, "Cannot use a negative size with stackalloc");
11802                         }
11803
11804                         if (ec.HasAny (ResolveContext.Options.CatchScope | ResolveContext.Options.FinallyScope)) {
11805                                 ec.Report.Error (255, loc, "Cannot use stackalloc in finally or catch");
11806                         }
11807
11808                         otype = texpr.ResolveAsType (ec);
11809                         if (otype == null)
11810                                 return null;
11811
11812                         if (!TypeManager.VerifyUnmanaged (ec.Module, otype, loc))
11813                                 return null;
11814
11815                         type = PointerContainer.MakeType (ec.Module, otype);
11816                         eclass = ExprClass.Value;
11817
11818                         return this;
11819                 }
11820
11821                 public override void Emit (EmitContext ec)
11822                 {
11823                         int size = BuiltinTypeSpec.GetSize (otype);
11824
11825                         count.Emit (ec);
11826
11827                         if (size == 0)
11828                                 ec.Emit (OpCodes.Sizeof, otype);
11829                         else
11830                                 ec.EmitInt (size);
11831
11832                         ec.Emit (OpCodes.Mul_Ovf_Un);
11833                         ec.Emit (OpCodes.Localloc);
11834                 }
11835
11836                 protected override void CloneTo (CloneContext clonectx, Expression t)
11837                 {
11838                         StackAlloc target = (StackAlloc) t;
11839                         target.count = count.Clone (clonectx);
11840                         target.texpr = texpr.Clone (clonectx);
11841                 }
11842
11843                 public override object Accept (StructuralVisitor visitor)
11844                 {
11845                         return visitor.Visit (this);
11846                 }
11847         }
11848
11849         //
11850         // An object initializer expression
11851         //
11852         public class ElementInitializer : Assign
11853         {
11854                 public readonly string Name;
11855
11856                 public ElementInitializer (string name, Expression initializer, Location loc)
11857                         : base (null, initializer, loc)
11858                 {
11859                         this.Name = name;
11860                 }
11861
11862                 public bool IsDictionaryInitializer {
11863                         get {
11864                                 return Name == null;
11865                         }
11866                 }
11867
11868                 protected override void CloneTo (CloneContext clonectx, Expression t)
11869                 {
11870                         ElementInitializer target = (ElementInitializer) t;
11871                         target.source = source.Clone (clonectx);
11872                 }
11873
11874                 public override Expression CreateExpressionTree (ResolveContext ec)
11875                 {
11876                         Arguments args = new Arguments (2);
11877                         FieldExpr fe = target as FieldExpr;
11878                         if (fe != null)
11879                                 args.Add (new Argument (fe.CreateTypeOfExpression ()));
11880                         else
11881                                 args.Add (new Argument (((PropertyExpr) target).CreateSetterTypeOfExpression (ec)));
11882
11883                         string mname;
11884                         Expression arg_expr;
11885                         var cinit = source as CollectionOrObjectInitializers;
11886                         if (cinit == null) {
11887                                 mname = "Bind";
11888                                 arg_expr = source.CreateExpressionTree (ec);
11889                         } else {
11890                                 mname = cinit.IsEmpty || cinit.Initializers[0] is ElementInitializer ? "MemberBind" : "ListBind";
11891                                 arg_expr = cinit.CreateExpressionTree (ec, !cinit.IsEmpty);
11892                         }
11893
11894                         args.Add (new Argument (arg_expr));
11895                         return CreateExpressionFactoryCall (ec, mname, args);
11896                 }
11897
11898                 protected override Expression DoResolve (ResolveContext ec)
11899                 {
11900                         if (source == null)
11901                                 return EmptyExpressionStatement.Instance;
11902
11903                         if (!ResolveElement (ec))
11904                                 return null;
11905
11906                         if (source is CollectionOrObjectInitializers) {
11907                                 target = target.Resolve (ec);
11908                                 if (target == null)
11909                                         return null;
11910
11911                                 Expression previous = ec.CurrentInitializerVariable;
11912                                 ec.CurrentInitializerVariable = target;
11913                                 source = source.Resolve (ec);
11914                                 ec.CurrentInitializerVariable = previous;
11915                                 if (source == null)
11916                                         return null;
11917
11918                                 eclass = source.eclass;
11919                                 type = source.Type;
11920
11921                                 return this;
11922                         }
11923
11924                         return base.DoResolve (ec);
11925                 }
11926
11927                 public override void EmitStatement (EmitContext ec)
11928                 {
11929                         if (source is CollectionOrObjectInitializers)
11930                                 source.Emit (ec);
11931                         else
11932                                 base.EmitStatement (ec);
11933                 }
11934
11935                 protected virtual bool ResolveElement (ResolveContext rc)
11936                 {
11937                         var t = rc.CurrentInitializerVariable.Type;
11938                         if (t.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
11939                                 Arguments args = new Arguments (1);
11940                                 args.Add (new Argument (rc.CurrentInitializerVariable));
11941                                 target = new DynamicMemberBinder (Name, args, loc);
11942                         } else {
11943                                 var member = MemberLookup (rc, false, t, Name, 0, MemberLookupRestrictions.ExactArity, loc);
11944                                 if (member == null) {
11945                                         member = Expression.MemberLookup (rc, true, t, Name, 0, MemberLookupRestrictions.ExactArity, loc);
11946
11947                                         if (member != null) {
11948                                                 // TODO: ec.Report.SymbolRelatedToPreviousError (member);
11949                                                 ErrorIsInaccesible (rc, member.GetSignatureForError (), loc);
11950                                                 return false;
11951                                         }
11952                                 }
11953
11954                                 if (member == null) {
11955                                         Error_TypeDoesNotContainDefinition (rc, loc, t, Name);
11956                                         return false;
11957                                 }
11958
11959                                 var me = member as MemberExpr;
11960                                 if (me is EventExpr) {
11961                                         me = me.ResolveMemberAccess (rc, null, null);
11962                                 } else if (!(member is PropertyExpr || member is FieldExpr)) {
11963                                         rc.Report.Error (1913, loc,
11964                                                 "Member `{0}' cannot be initialized. An object initializer may only be used for fields, or properties",
11965                                                 member.GetSignatureForError ());
11966
11967                                         return false;
11968                                 }
11969
11970                                 if (me.IsStatic) {
11971                                         rc.Report.Error (1914, loc,
11972                                                 "Static field or property `{0}' cannot be assigned in an object initializer",
11973                                                 me.GetSignatureForError ());
11974                                 }
11975
11976                                 target = me;
11977                                 me.InstanceExpression = rc.CurrentInitializerVariable;
11978                         }
11979
11980                         return true;
11981                 }
11982         }
11983
11984         //
11985         // A collection initializer expression
11986         //
11987         class CollectionElementInitializer : Invocation
11988         {
11989                 public class ElementInitializerArgument : Argument
11990                 {
11991                         public ElementInitializerArgument (Expression e)
11992                                 : base (e)
11993                         {
11994                         }
11995                 }
11996
11997                 sealed class AddMemberAccess : MemberAccess
11998                 {
11999                         public AddMemberAccess (Expression expr, Location loc)
12000                                 : base (expr, "Add", loc)
12001                         {
12002                         }
12003
12004                         public override void Error_TypeDoesNotContainDefinition (ResolveContext ec, TypeSpec type, string name)
12005                         {
12006                                 if (TypeManager.HasElementType (type))
12007                                         return;
12008
12009                                 base.Error_TypeDoesNotContainDefinition (ec, type, name);
12010                         }
12011                 }
12012
12013                 public CollectionElementInitializer (Expression argument)
12014                         : base (null, new Arguments (1))
12015                 {
12016                         base.arguments.Add (new ElementInitializerArgument (argument));
12017                         this.loc = argument.Location;
12018                 }
12019
12020                 public CollectionElementInitializer (List<Expression> arguments, Location loc)
12021                         : base (null, new Arguments (arguments.Count))
12022                 {
12023                         foreach (Expression e in arguments)
12024                                 base.arguments.Add (new ElementInitializerArgument (e));
12025
12026                         this.loc = loc;
12027                 }
12028
12029                 public CollectionElementInitializer (Location loc)
12030                         : base (null, null)
12031                 {
12032                         this.loc = loc;
12033                 }
12034
12035                 public override Expression CreateExpressionTree (ResolveContext ec)
12036                 {
12037                         Arguments args = new Arguments (2);
12038                         args.Add (new Argument (mg.CreateExpressionTree (ec)));
12039
12040                         var expr_initializers = new ArrayInitializer (arguments.Count, loc);
12041                         foreach (Argument a in arguments) {
12042                                 if (a.ArgType == Argument.AType.ExtensionType) {
12043                                         ec.Report.Error (8075, a.Expr.Location, "An expression tree cannot contain a collection initializer with extension method");
12044                                         continue;
12045                                 }
12046                                 expr_initializers.Add (a.CreateExpressionTree (ec));
12047                         }
12048
12049                         args.Add (new Argument (new ArrayCreation (
12050                                 CreateExpressionTypeExpression (ec, loc), expr_initializers, loc)));
12051                         return CreateExpressionFactoryCall (ec, "ElementInit", args);
12052                 }
12053
12054                 protected override void CloneTo (CloneContext clonectx, Expression t)
12055                 {
12056                         CollectionElementInitializer target = (CollectionElementInitializer) t;
12057                         if (arguments != null)
12058                                 target.arguments = arguments.Clone (clonectx);
12059                 }
12060
12061                 protected override Expression DoResolve (ResolveContext ec)
12062                 {
12063                         base.expr = new AddMemberAccess (ec.CurrentInitializerVariable, loc);
12064
12065                         return base.DoResolve (ec);
12066                 }
12067         }
12068
12069         class DictionaryElementInitializer : ElementInitializer
12070         {
12071                 readonly Arguments args;
12072
12073                 public DictionaryElementInitializer (Arguments arguments, Expression initializer, Location loc)
12074                         : base (null, initializer, loc)
12075                 {
12076                         this.args = arguments;
12077                 }
12078
12079                 public override Expression CreateExpressionTree (ResolveContext ec)
12080                 {
12081                         ec.Report.Error (8074, loc, "Expression tree cannot contain a dictionary initializer");
12082                         return null;
12083                 }
12084
12085                 protected override bool ResolveElement (ResolveContext rc)
12086                 {
12087                         var init = rc.CurrentInitializerVariable;
12088                         var type = init.Type;
12089
12090                         if (type.IsArray) {
12091                                 target = new ArrayAccess (new ElementAccess (init, args, loc), loc);
12092                                 return true;
12093                         }
12094
12095                         if (type.IsPointer) {
12096                                 target = init.MakePointerAccess (rc, type, args);
12097                                 return true;
12098                         }
12099
12100                         var indexers = MemberCache.FindMembers (type, MemberCache.IndexerNameAlias, false);
12101                         if (indexers == null && type.BuiltinType != BuiltinTypeSpec.Type.Dynamic) {
12102                                 ElementAccess.Error_CannotApplyIndexing (rc, type, loc);
12103                                 return false;
12104                         }
12105
12106                         target = new IndexerExpr (indexers, type, init, args, loc);
12107                         return true;
12108                 }
12109         }
12110
12111         //
12112         // A block of object or collection initializers
12113         //
12114         public class CollectionOrObjectInitializers : ExpressionStatement
12115         {
12116                 IList<Expression> initializers;
12117                 bool is_collection_initialization;
12118
12119                 public CollectionOrObjectInitializers (Location loc)
12120                         : this (new Expression[0], loc)
12121                 {
12122                 }
12123
12124                 public CollectionOrObjectInitializers (IList<Expression> initializers, Location loc)
12125                 {
12126                         this.initializers = initializers;
12127                         this.loc = loc;
12128                 }
12129
12130                 public IList<Expression> Initializers {
12131                         get {
12132                                 return initializers;
12133                         }
12134                 }
12135
12136                 public bool IsEmpty {
12137                         get {
12138                                 return initializers.Count == 0;
12139                         }
12140                 }
12141
12142                 public bool IsCollectionInitializer {
12143                         get {
12144                                 return is_collection_initialization;
12145                         }
12146                 }
12147
12148                 protected override void CloneTo (CloneContext clonectx, Expression target)
12149                 {
12150                         CollectionOrObjectInitializers t = (CollectionOrObjectInitializers) target;
12151
12152                         t.initializers = new List<Expression> (initializers.Count);
12153                         foreach (var e in initializers)
12154                                 t.initializers.Add (e.Clone (clonectx));
12155                 }
12156
12157                 public override bool ContainsEmitWithAwait ()
12158                 {
12159                         foreach (var e in initializers) {
12160                                 if (e.ContainsEmitWithAwait ())
12161                                         return true;
12162                         }
12163
12164                         return false;
12165                 }
12166
12167                 public override Expression CreateExpressionTree (ResolveContext ec)
12168                 {
12169                         return CreateExpressionTree (ec, false);
12170                 }
12171
12172                 public Expression CreateExpressionTree (ResolveContext ec, bool inferType)
12173                 {
12174                         var expr_initializers = new ArrayInitializer (initializers.Count, loc);
12175                         foreach (Expression e in initializers) {
12176                                 Expression expr = e.CreateExpressionTree (ec);
12177                                 if (expr != null)
12178                                         expr_initializers.Add (expr);
12179                         }
12180
12181                         if (inferType)
12182                                 return new ImplicitlyTypedArrayCreation (expr_initializers, loc);
12183
12184                         return new ArrayCreation (new TypeExpression (ec.Module.PredefinedTypes.MemberBinding.Resolve (), loc), expr_initializers, loc);
12185                 }
12186
12187                 protected override Expression DoResolve (ResolveContext ec)
12188                 {
12189                         List<string> element_names = null;
12190                         for (int i = 0; i < initializers.Count; ++i) {
12191                                 Expression initializer = initializers [i];
12192                                 ElementInitializer element_initializer = initializer as ElementInitializer;
12193
12194                                 if (i == 0) {
12195                                         if (element_initializer != null) {
12196                                                 element_names = new List<string> (initializers.Count);
12197                                                 if (!element_initializer.IsDictionaryInitializer)
12198                                                         element_names.Add (element_initializer.Name);
12199                                         } else if (initializer is CompletingExpression) {
12200                                                 initializer.Resolve (ec);
12201                                                 throw new InternalErrorException ("This line should never be reached");
12202                                         } else {
12203                                                 var t = ec.CurrentInitializerVariable.Type;
12204                                                 // LAMESPEC: The collection must implement IEnumerable only, no dynamic support
12205                                                 if (!t.ImplementsInterface (ec.BuiltinTypes.IEnumerable, false) && t.BuiltinType != BuiltinTypeSpec.Type.Dynamic) {
12206                                                         ec.Report.Error (1922, loc, "A field or property `{0}' cannot be initialized with a collection " +
12207                                                                 "object initializer because type `{1}' does not implement `{2}' interface",
12208                                                                 ec.CurrentInitializerVariable.GetSignatureForError (),
12209                                                                 ec.CurrentInitializerVariable.Type.GetSignatureForError (),
12210                                                                 ec.BuiltinTypes.IEnumerable.GetSignatureForError ());
12211                                                         return null;
12212                                                 }
12213                                                 is_collection_initialization = true;
12214                                         }
12215                                 } else {
12216                                         if (is_collection_initialization != (element_initializer == null)) {
12217                                                 ec.Report.Error (747, initializer.Location, "Inconsistent `{0}' member declaration",
12218                                                         is_collection_initialization ? "collection initializer" : "object initializer");
12219                                                 continue;
12220                                         }
12221
12222                                         if (!is_collection_initialization && !element_initializer.IsDictionaryInitializer) {
12223                                                 if (element_names.Contains (element_initializer.Name)) {
12224                                                         ec.Report.Error (1912, element_initializer.Location,
12225                                                                 "An object initializer includes more than one member `{0}' initialization",
12226                                                                 element_initializer.Name);
12227                                                 } else {
12228                                                         element_names.Add (element_initializer.Name);
12229                                                 }
12230                                         }
12231                                 }
12232
12233                                 Expression e = initializer.Resolve (ec);
12234                                 if (e == EmptyExpressionStatement.Instance)
12235                                         initializers.RemoveAt (i--);
12236                                 else
12237                                         initializers [i] = e;
12238                         }
12239
12240                         type = ec.CurrentInitializerVariable.Type;
12241                         if (is_collection_initialization) {
12242                                 if (TypeManager.HasElementType (type)) {
12243                                         ec.Report.Error (1925, loc, "Cannot initialize object of type `{0}' with a collection initializer",
12244                                                 type.GetSignatureForError ());
12245                                 }
12246                         }
12247
12248                         eclass = ExprClass.Variable;
12249                         return this;
12250                 }
12251
12252                 public override void Emit (EmitContext ec)
12253                 {
12254                         EmitStatement (ec);
12255                 }
12256
12257                 public override void EmitStatement (EmitContext ec)
12258                 {
12259                         foreach (ExpressionStatement e in initializers) {
12260                                 // TODO: need location region
12261                                 ec.Mark (e.Location);
12262                                 e.EmitStatement (ec);
12263                         }
12264                 }
12265
12266                 public override void FlowAnalysis (FlowAnalysisContext fc)
12267                 {
12268                         foreach (var initializer in initializers) {
12269                                 if (initializer != null)
12270                                         initializer.FlowAnalysis (fc);
12271                         }
12272                 }
12273         }
12274
12275         //
12276         // New expression with element/object initializers
12277         //
12278         public class NewInitialize : New
12279         {
12280                 //
12281                 // This class serves as a proxy for variable initializer target instances.
12282                 // A real variable is assigned later when we resolve left side of an
12283                 // assignment
12284                 //
12285                 sealed class InitializerTargetExpression : Expression, IMemoryLocation
12286                 {
12287                         NewInitialize new_instance;
12288
12289                         public InitializerTargetExpression (NewInitialize newInstance)
12290                         {
12291                                 this.type = newInstance.type;
12292                                 this.loc = newInstance.loc;
12293                                 this.eclass = newInstance.eclass;
12294                                 this.new_instance = newInstance;
12295                         }
12296
12297                         public override bool ContainsEmitWithAwait ()
12298                         {
12299                                 return false;
12300                         }
12301
12302                         public override Expression CreateExpressionTree (ResolveContext ec)
12303                         {
12304                                 // Should not be reached
12305                                 throw new NotSupportedException ("ET");
12306                         }
12307
12308                         protected override Expression DoResolve (ResolveContext ec)
12309                         {
12310                                 return this;
12311                         }
12312
12313                         public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
12314                         {
12315                                 return this;
12316                         }
12317
12318                         public override void Emit (EmitContext ec)
12319                         {
12320                                 Expression e = (Expression) new_instance.instance;
12321                                 e.Emit (ec);
12322                         }
12323
12324                         public override Expression EmitToField (EmitContext ec)
12325                         {
12326                                 return (Expression) new_instance.instance;
12327                         }
12328
12329                         #region IMemoryLocation Members
12330
12331                         public void AddressOf (EmitContext ec, AddressOp mode)
12332                         {
12333                                 new_instance.instance.AddressOf (ec, mode);
12334                         }
12335
12336                         #endregion
12337                 }
12338
12339                 CollectionOrObjectInitializers initializers;
12340                 IMemoryLocation instance;
12341                 DynamicExpressionStatement dynamic;
12342
12343                 public NewInitialize (FullNamedExpression requested_type, Arguments arguments, CollectionOrObjectInitializers initializers, Location l)
12344                         : base (requested_type, arguments, l)
12345                 {
12346                         this.initializers = initializers;
12347                 }
12348
12349                 public CollectionOrObjectInitializers Initializers {
12350                         get {
12351                                 return initializers;
12352                         }
12353                 }
12354
12355                 protected override void CloneTo (CloneContext clonectx, Expression t)
12356                 {
12357                         base.CloneTo (clonectx, t);
12358
12359                         NewInitialize target = (NewInitialize) t;
12360                         target.initializers = (CollectionOrObjectInitializers) initializers.Clone (clonectx);
12361                 }
12362
12363                 public override bool ContainsEmitWithAwait ()
12364                 {
12365                         return base.ContainsEmitWithAwait () || initializers.ContainsEmitWithAwait ();
12366                 }
12367
12368                 public override Expression CreateExpressionTree (ResolveContext ec)
12369                 {
12370                         Arguments args = new Arguments (2);
12371                         args.Add (new Argument (base.CreateExpressionTree (ec)));
12372                         if (!initializers.IsEmpty)
12373                                 args.Add (new Argument (initializers.CreateExpressionTree (ec, initializers.IsCollectionInitializer)));
12374
12375                         return CreateExpressionFactoryCall (ec,
12376                                 initializers.IsCollectionInitializer ? "ListInit" : "MemberInit",
12377                                 args);
12378                 }
12379
12380                 protected override Expression DoResolve (ResolveContext rc)
12381                 {
12382                         Expression e = base.DoResolve (rc);
12383                         if (type == null)
12384                                 return null;
12385
12386                         if (type.IsDelegate) {
12387                                 rc.Report.Error (1958, Initializers.Location,
12388                                         "Object and collection initializers cannot be used to instantiate a delegate");
12389                         }
12390
12391                         Expression previous = rc.CurrentInitializerVariable;
12392                         rc.CurrentInitializerVariable = new InitializerTargetExpression (this);
12393                         using (rc.With (ResolveContext.Options.DontSetConditionalAccessReceiver, false)) {
12394                                 initializers.Resolve (rc);
12395                         }
12396                         rc.CurrentInitializerVariable = previous;
12397
12398                         dynamic = e as DynamicExpressionStatement;
12399                         if (dynamic != null)
12400                                 return this;
12401
12402                         return e;
12403                 }
12404
12405                 public override void Emit (EmitContext ec)
12406                 {
12407                         if (!CanEmitOptimizedLocalTarget (ec)) {
12408                                 var fe = ec.GetTemporaryField (type);
12409
12410                                 if (!Emit (ec, fe))
12411                                         fe.Emit (ec);
12412
12413                                 return;
12414                         }
12415
12416                         base.Emit (ec);
12417                 }
12418
12419                 public override bool Emit (EmitContext ec, IMemoryLocation target)
12420                 {
12421                         //
12422                         // Expression is initialized into temporary target then moved
12423                         // to real one for atomicity
12424                         //
12425                         IMemoryLocation temp_target = target;
12426
12427                         LocalTemporary temp = null;
12428                         bool by_ref = false;
12429                         if (!initializers.IsEmpty) {
12430                                 temp_target = target as LocalTemporary;
12431                                 if (temp_target == null)
12432                                         temp_target = target as StackFieldExpr;
12433
12434                                 if (temp_target == null) {
12435                                         var vr = target as VariableReference;
12436                                         if (vr != null && vr.IsRef) {
12437                                                 vr.EmitLoad (ec);
12438                                                 by_ref = true;
12439                                         }
12440                                 }
12441
12442                                 if (temp_target == null)
12443                                         temp_target = temp = new LocalTemporary (type);
12444                         }
12445
12446                         bool left_on_stack;
12447                         if (dynamic != null) {
12448                                 dynamic.Emit (ec);
12449                                 left_on_stack = true;
12450                         } else {
12451                                 left_on_stack = base.Emit (ec, temp_target);
12452                         }
12453
12454                         if (initializers.IsEmpty)
12455                                 return left_on_stack;
12456
12457                         StackFieldExpr sf = null;
12458
12459                         // Move a new instance (reference-type) to local temporary variable
12460                         if (left_on_stack) {
12461                                 if (by_ref) {
12462                                         temp_target = temp = new LocalTemporary (type);
12463                                 }
12464
12465                                 if (temp != null)
12466                                         temp.Store (ec);
12467
12468                                 if (ec.HasSet (BuilderContext.Options.AsyncBody) && initializers.ContainsEmitWithAwait ()) {
12469                                         if (temp == null)
12470                                                 throw new NotImplementedException ();
12471
12472                                         sf = ec.GetTemporaryField (type);
12473                                         sf.AutomaticallyReuse = false;
12474                                         sf.EmitAssign (ec, temp, false, false);
12475                                         temp_target = sf;
12476                                         temp.Release (ec);
12477                                         left_on_stack = false;
12478                                 }
12479                         }
12480
12481                         instance = temp_target;
12482
12483                         initializers.Emit (ec);
12484
12485                         ((Expression)temp_target).Emit (ec);
12486
12487                         if (temp != null)
12488                                 temp.Release (ec);
12489
12490                         if (sf != null)
12491                                 sf.PrepareCleanup (ec);
12492
12493                         return true;
12494                 }
12495
12496                 public override bool CanEmitOptimizedLocalTarget (EmitContext ec)
12497                 {
12498                         return !(method == null && TypeSpec.IsValueType (type) &&
12499                                         initializers.Initializers.Count > 1 && ec.HasSet (BuilderContext.Options.AsyncBody) &&
12500                                         initializers.ContainsEmitWithAwait ());
12501                 }
12502
12503                 protected override IMemoryLocation EmitAddressOf (EmitContext ec, AddressOp Mode)
12504                 {
12505                         instance = base.EmitAddressOf (ec, Mode);
12506
12507                         if (!initializers.IsEmpty)
12508                                 initializers.Emit (ec);
12509
12510                         return instance;
12511                 }
12512
12513                 public override void FlowAnalysis (FlowAnalysisContext fc)
12514                 {
12515                         base.FlowAnalysis (fc);
12516                         initializers.FlowAnalysis (fc);
12517                 }
12518
12519                 public override object Accept (StructuralVisitor visitor)
12520                 {
12521                         return visitor.Visit (this);
12522                 }
12523         }
12524
12525         public class NewAnonymousType : New
12526         {
12527                 static readonly AnonymousTypeParameter[] EmptyParameters = new AnonymousTypeParameter[0];
12528
12529                 List<AnonymousTypeParameter> parameters;
12530                 readonly TypeContainer parent;
12531                 AnonymousTypeClass anonymous_type;
12532
12533                 public NewAnonymousType (List<AnonymousTypeParameter> parameters, TypeContainer parent, Location loc)
12534                          : base (null, null, loc)
12535                 {
12536                         this.parameters = parameters;
12537                         this.parent = parent;
12538                 }
12539
12540                 public List<AnonymousTypeParameter> Parameters {
12541                         get {
12542                                 return this.parameters;
12543                         }
12544                 }
12545
12546                 protected override void CloneTo (CloneContext clonectx, Expression target)
12547                 {
12548                         if (parameters == null)
12549                                 return;
12550
12551                         NewAnonymousType t = (NewAnonymousType) target;
12552                         t.parameters = new List<AnonymousTypeParameter> (parameters.Count);
12553                         foreach (AnonymousTypeParameter atp in parameters)
12554                                 t.parameters.Add ((AnonymousTypeParameter) atp.Clone (clonectx));
12555                 }
12556
12557                 AnonymousTypeClass CreateAnonymousType (ResolveContext ec, IList<AnonymousTypeParameter> parameters)
12558                 {
12559                         AnonymousTypeClass type = parent.Module.GetAnonymousType (parameters);
12560                         if (type != null)
12561                                 return type;
12562
12563                         type = AnonymousTypeClass.Create (parent, parameters, loc);
12564                         if (type == null)
12565                                 return null;
12566
12567                         int errors = ec.Report.Errors;
12568                         type.CreateContainer ();
12569                         type.DefineContainer ();
12570                         type.ExpandBaseInterfaces ();
12571                         type.Define ();
12572                         if ((ec.Report.Errors - errors) == 0) {
12573                                 parent.Module.AddAnonymousType (type);
12574                                 type.PrepareEmit ();
12575                         }
12576
12577                         return type;
12578                 }
12579
12580                 public override Expression CreateExpressionTree (ResolveContext ec)
12581                 {
12582                         if (parameters == null)
12583                                 return base.CreateExpressionTree (ec);
12584
12585                         var init = new ArrayInitializer (parameters.Count, loc);
12586                         foreach (var m in anonymous_type.Members) {
12587                                 var p = m as Property;
12588                                 if (p != null)
12589                                         init.Add (new TypeOfMethod (MemberCache.GetMember (type, p.Get.Spec), loc));
12590                         }
12591
12592                         var ctor_args = new ArrayInitializer (arguments.Count, loc);
12593                         foreach (Argument a in arguments)
12594                                 ctor_args.Add (a.CreateExpressionTree (ec));
12595
12596                         Arguments args = new Arguments (3);
12597                         args.Add (new Argument (new TypeOfMethod (method, loc)));
12598                         args.Add (new Argument (new ArrayCreation (CreateExpressionTypeExpression (ec, loc), ctor_args, loc)));
12599                         args.Add (new Argument (new ImplicitlyTypedArrayCreation (init, loc)));
12600
12601                         return CreateExpressionFactoryCall (ec, "New", args);
12602                 }
12603
12604                 protected override Expression DoResolve (ResolveContext ec)
12605                 {
12606                         if (ec.HasSet (ResolveContext.Options.ConstantScope)) {
12607                                 ec.Report.Error (836, loc, "Anonymous types cannot be used in this expression");
12608                                 return null;
12609                         }
12610
12611                         if (parameters == null) {
12612                                 anonymous_type = CreateAnonymousType (ec, EmptyParameters);
12613                                 RequestedType = new TypeExpression (anonymous_type.Definition, loc);
12614                                 return base.DoResolve (ec);
12615                         }
12616
12617                         bool error = false;
12618                         arguments = new Arguments (parameters.Count);
12619                         var t_args = new TypeSpec [parameters.Count];
12620                         for (int i = 0; i < parameters.Count; ++i) {
12621                                 Expression e = parameters [i].Resolve (ec);
12622                                 if (e == null) {
12623                                         error = true;
12624                                         continue;
12625                                 }
12626
12627                                 arguments.Add (new Argument (e));
12628                                 t_args [i] = e.Type;
12629                         }
12630
12631                         if (error)
12632                                 return null;
12633
12634                         anonymous_type = CreateAnonymousType (ec, parameters);
12635                         if (anonymous_type == null)
12636                                 return null;
12637
12638                         type = anonymous_type.Definition.MakeGenericType (ec.Module, t_args);
12639                         method = (MethodSpec) MemberCache.FindMember (type, MemberFilter.Constructor (null), BindingRestriction.DeclaredOnly);
12640                         eclass = ExprClass.Value;
12641                         return this;
12642                 }
12643
12644                 public override object Accept (StructuralVisitor visitor)
12645                 {
12646                         return visitor.Visit (this);
12647                 }
12648         }
12649
12650         public class AnonymousTypeParameter : ShimExpression
12651         {
12652                 public readonly string Name;
12653
12654                 public AnonymousTypeParameter (Expression initializer, string name, Location loc)
12655                         : base (initializer)
12656                 {
12657                         this.Name = name;
12658                         this.loc = loc;
12659                 }
12660
12661                 public AnonymousTypeParameter (Parameter parameter)
12662                         : base (new SimpleName (parameter.Name, parameter.Location))
12663                 {
12664                         this.Name = parameter.Name;
12665                         this.loc = parameter.Location;
12666                 }
12667
12668                 public override bool Equals (object o)
12669                 {
12670                         AnonymousTypeParameter other = o as AnonymousTypeParameter;
12671                         return other != null && Name == other.Name;
12672                 }
12673
12674                 public override int GetHashCode ()
12675                 {
12676                         return Name.GetHashCode ();
12677                 }
12678
12679                 protected override Expression DoResolve (ResolveContext ec)
12680                 {
12681                         Expression e = expr.Resolve (ec);
12682                         if (e == null)
12683                                 return null;
12684
12685                         if (e.eclass == ExprClass.MethodGroup) {
12686                                 Error_InvalidInitializer (ec, e.ExprClassName);
12687                                 return null;
12688                         }
12689
12690                         type = e.Type;
12691                         if (type.Kind == MemberKind.Void || InternalType.HasNoType (type) || type.IsPointer || (e is TupleLiteral && TupleLiteral.ContainsNoTypeElement (type))) {
12692                                 Error_InvalidInitializer (ec, type.GetSignatureForError ());
12693                                 return null;
12694                         }
12695
12696                         return e;
12697                 }
12698
12699                 protected virtual void Error_InvalidInitializer (ResolveContext ec, string initializer)
12700                 {
12701                         ec.Report.Error (828, loc, "An anonymous type property `{0}' cannot be initialized with `{1}'",
12702                                 Name, initializer);
12703                 }
12704         }
12705
12706         public class CatchFilterExpression : BooleanExpression
12707         {
12708                 public CatchFilterExpression (Expression expr, Location loc)
12709                         : base (expr)
12710                 {
12711                         this.loc = loc;
12712                 }
12713         }
12714
12715         public class InterpolatedString : Expression
12716         {
12717                 readonly StringLiteral start, end;
12718                 List<Expression> interpolations;
12719                 Arguments arguments;
12720
12721                 public InterpolatedString (StringLiteral start, List<Expression> interpolations, StringLiteral end)
12722                 {
12723                         this.start = start;
12724                         this.end = end;
12725                         this.interpolations = interpolations;
12726                         loc = start.Location;
12727                 }
12728
12729                 protected override void CloneTo (CloneContext clonectx, Expression t)
12730                 {
12731                         InterpolatedString target = (InterpolatedString) t;
12732
12733                         if (interpolations != null) {
12734                                 target.interpolations = new List<Expression> ();
12735                                 foreach (var interpolation in interpolations) {
12736                                         target.interpolations.Add (interpolation.Clone (clonectx));
12737                                 }
12738                         }
12739                 }
12740
12741                 public Expression ConvertTo (ResolveContext rc, TypeSpec type)
12742                 {
12743                         var factory = rc.Module.PredefinedTypes.FormattableStringFactory.Resolve ();
12744                         if (factory == null)
12745                                 return null;
12746
12747                         var ma = new MemberAccess (new TypeExpression (factory, loc), "Create", loc);
12748                         var res = new Invocation (ma, arguments).Resolve (rc);
12749                         if (res != null && res.Type != type)
12750                                 res = Convert.ExplicitConversion (rc, res, type, loc);
12751
12752                         return res;
12753                 }
12754
12755                 public override bool ContainsEmitWithAwait ()
12756                 {
12757                         if (interpolations == null)
12758                                 return false;
12759
12760                         foreach (var expr in interpolations) {
12761                                 if (expr.ContainsEmitWithAwait ())
12762                                         return true;
12763                         }
12764
12765                         return false;
12766                 }
12767
12768                 public override Expression CreateExpressionTree (ResolveContext rc)
12769                 {
12770                         var best = ResolveBestFormatOverload (rc);
12771                         if (best == null)
12772                                 return null;
12773
12774                         Expression instance = new NullLiteral (loc);
12775                         var args = Arguments.CreateForExpressionTree (rc, arguments, instance, new TypeOfMethod (best, loc));
12776                         return CreateExpressionFactoryCall (rc, "Call", args);
12777                 }
12778
12779                 protected override Expression DoResolve (ResolveContext rc)
12780                 {
12781                         string str;
12782
12783                         if (interpolations == null) {
12784                                 str = start.Value;
12785                                 arguments = new Arguments (1);
12786                         } else {
12787                                 arguments = new Arguments (interpolations.Count);
12788
12789                                 var sb = new StringBuilder (start.Value);
12790                                 for (int i = 0; i < interpolations.Count; ++i) {
12791                                         if (i % 2 == 0) {
12792                                                 sb.Append ('{').Append (i / 2);
12793                                                 var isi = (InterpolatedStringInsert)interpolations [i];
12794                                                 if (isi.Alignment != null) {
12795                                                         sb.Append (',');
12796                                                         var value = isi.ResolveAligment (rc);
12797                                                         if (value != null)
12798                                                                 sb.Append (value.Value);
12799                                                 }
12800
12801                                                 if (isi.Format != null) {
12802                                                         sb.Append (':');
12803                                                         sb.Append (isi.Format);
12804                                                 }
12805
12806                                                 sb.Append ('}');
12807                                                 arguments.Add (new Argument (isi.Resolve (rc)));
12808                                         } else {
12809                                                 sb.Append (((StringLiteral)interpolations [i]).Value);
12810                                         }
12811                                 }
12812
12813                                 sb.Append (end.Value);
12814                                 str = sb.ToString ();
12815                         }
12816
12817                         arguments.Insert (0, new Argument (new StringLiteral (rc.BuiltinTypes, str, start.Location)));
12818
12819                         eclass = ExprClass.Value;
12820                         type = rc.BuiltinTypes.String;
12821                         return this;
12822                 }
12823
12824                 public override void Emit (EmitContext ec)
12825                 {
12826                         // No interpolation, convert to simple string result (needs to match string.Format unescaping)
12827                         if (interpolations == null) {
12828                                 var str = start.Value.Replace ("{{", "{").Replace ("}}", "}");
12829                                 if (str != start.Value)
12830                                         new StringConstant (ec.BuiltinTypes, str, loc).Emit (ec);
12831                                 else
12832                                         start.Emit (ec);
12833
12834                                 return;
12835                         }
12836
12837                         var best = ResolveBestFormatOverload (new ResolveContext (ec.MemberContext));
12838                         if (best == null)
12839                                 return;
12840
12841                         var ca = new CallEmitter ();
12842                         ca.Emit (ec, best, arguments, loc);
12843                 }
12844
12845                 public override void FlowAnalysis (FlowAnalysisContext fc)
12846                 {
12847                         if (interpolations != null) {
12848                                 foreach (var expr in interpolations) {
12849                                         expr.FlowAnalysis (fc);
12850                                 }
12851                         }
12852                 }
12853
12854                 MethodSpec ResolveBestFormatOverload (ResolveContext rc)
12855                 {
12856                         var members = MemberCache.FindMembers (rc.BuiltinTypes.String, "Format", true);
12857                         var res = new OverloadResolver (members, OverloadResolver.Restrictions.NoBaseMembers, loc);
12858                         return res.ResolveMember<MethodSpec> (rc, ref arguments);
12859                 }
12860         }
12861
12862         public class InterpolatedStringInsert : CompositeExpression
12863         {
12864                 public InterpolatedStringInsert (Expression expr)
12865                         : base (expr)
12866                 {
12867                 }
12868
12869                 public Expression Alignment { get; set; }
12870                 public string Format { get; set; }
12871
12872                 protected override void CloneTo (CloneContext clonectx, Expression t)
12873                 {
12874                         var target = (InterpolatedStringInsert)t;
12875                         target.expr = expr.Clone (clonectx);
12876                         if (Alignment != null)
12877                                 target.Alignment = Alignment.Clone (clonectx);
12878                 }
12879
12880                 protected override Expression DoResolve (ResolveContext rc)
12881                 {
12882                         var expr = base.DoResolve (rc);
12883                         if (expr == null)
12884                                 return null;
12885
12886                         //
12887                         // For better error reporting, assumes the built-in implementation uses object
12888                         // as argument(s)
12889                         //
12890                         return Convert.ImplicitConversionRequired (rc, expr, rc.BuiltinTypes.Object, expr.Location);
12891                 }
12892
12893                 public override void FlowAnalysis (FlowAnalysisContext fc)
12894                 {
12895                         Child.FlowAnalysis (fc);
12896                 }
12897
12898                 public int? ResolveAligment (ResolveContext rc)
12899                 {
12900                         var c = Alignment.ResolveLabelConstant (rc);
12901                         if (c == null)
12902                                 return null;
12903
12904                         c = c.ImplicitConversionRequired (rc, rc.BuiltinTypes.Int);
12905                         if (c == null)
12906                                 return null;
12907
12908                         var value = (int) c.GetValueAsLong ();
12909                         if (value > 32767 || value < -32767) {
12910                                 rc.Report.Warning (8094, 1, Alignment.Location,
12911                                         "Alignment value has a magnitude greater than 32767 and may result in a large formatted string");
12912                         }
12913
12914                         return value;
12915                 }
12916         }
12917
12918         class ThrowExpression : ExpressionStatement
12919         {
12920                 Expression expr;
12921
12922                 public ThrowExpression (Expression expr, Location loc)
12923                 {
12924                         this.expr = expr;
12925                         this.loc = loc;
12926                 }
12927
12928                 protected override void CloneTo (CloneContext clonectx, Expression t)
12929                 {
12930                         var target = (ThrowExpression)t;
12931                         target.expr = expr.Clone (clonectx);
12932                 }
12933
12934                 public override bool ContainsEmitWithAwait ()
12935                 {
12936                         return expr.ContainsEmitWithAwait ();
12937                 }
12938
12939                 public override Expression CreateExpressionTree (ResolveContext rc)
12940                 {
12941                         rc.Report.Error (8188, loc, "An expression tree cannot not contain a throw expression");
12942                         return expr;
12943                 }
12944
12945                 protected override Expression DoResolve (ResolveContext rc)
12946                 {
12947                         expr = expr.Resolve (rc, ResolveFlags.Type | ResolveFlags.VariableOrValue);
12948
12949                         if (expr == null)
12950                                 return null;
12951
12952                         expr = Throw.ConvertType (rc, expr);
12953
12954                         eclass = ExprClass.Value;
12955                         type = InternalType.ThrowExpr;
12956                         return this;
12957                 }
12958
12959                 public override void Emit (EmitContext ec)
12960                 {
12961                         EmitStatement (ec);
12962                 }
12963
12964                 public override void EmitStatement (EmitContext ec)
12965                 {
12966                         expr.Emit (ec);
12967
12968                         ec.Emit (OpCodes.Throw);
12969                 }
12970
12971                 public override void FlowAnalysis (FlowAnalysisContext fc)
12972                 {
12973                         expr.FlowAnalysis (fc);
12974                 }
12975
12976                 public override Reachability MarkReachable (Reachability rc)
12977                 {
12978                         return Reachability.CreateUnreachable ();
12979                 }
12980         }
12981
12982         class ReferenceExpression : CompositeExpression
12983         {
12984                 public ReferenceExpression (Expression expr, Location loc)
12985                         : base (expr)
12986                 {
12987                         this.loc = loc;
12988                 }
12989
12990                 static bool CanBeByRef (Expression expr)
12991                 {
12992                         if (expr is IAssignMethod)
12993                                 return true;
12994
12995                         var invocation = expr as Invocation;
12996                         if (invocation?.Type.Kind == MemberKind.ByRef)
12997                                 return true;
12998
12999                         return false;
13000                 }
13001
13002                 public override Expression CreateExpressionTree (ResolveContext rc)
13003                 {
13004                         throw new NotSupportedException ("ET");
13005                 }
13006
13007                 protected override Expression DoResolve (ResolveContext rc)
13008                 {
13009                         var res = expr.DoResolveLValue (rc, EmptyExpression.OutAccess);
13010                         if (res == null || !CanBeByRef (res)) {
13011                                 if (res?.Type != InternalType.ErrorType)
13012                                         rc.Report.Error (8156, expr.Location, "An expression cannot be used in this context because it may not be returned by reference");
13013                                 return ErrorExpression.Instance;
13014                         }
13015
13016                         type = res.Type;
13017                         var type_container = type as ReferenceContainer;
13018                         if (type_container != null)
13019                                 type = type_container.Element;
13020
13021                         expr = res;
13022                         eclass = ExprClass.Value;
13023                         return this;
13024                 }
13025
13026                 public override void Emit (EmitContext ec)
13027                 {
13028                         var ml = expr as IMemoryLocation;
13029                         if (ml != null)
13030                                 ml.AddressOf (ec, AddressOp.LoadStore);
13031                         else
13032                                 expr.Emit (ec);
13033                 }
13034
13035                 public override void Error_ValueCannotBeConverted (ResolveContext rc, TypeSpec target, bool expl)
13036                 {
13037                         rc.Report.Error (8173, loc, "The expression must be of type `{0}' because it is being assigned by reference", target.GetSignatureForError ());
13038                 }
13039         }
13040
13041         class ByRefDereference : CompositeExpression, IMemoryLocation, IAssignMethod
13042         {
13043                 bool prepared;
13044                 LocalTemporary temporary;
13045
13046                 private ByRefDereference (Expression expr)
13047                         : base (expr)
13048                 {
13049                 }
13050
13051                 public static Expression Create (Expression expr)
13052                 {
13053                         var rc = expr.Type as ReferenceContainer;
13054                         if (rc == null)
13055                                 return expr;
13056
13057                         return new ByRefDereference (expr) {
13058                                 type = rc.Element
13059                         };
13060                 }
13061
13062                 public void AddressOf (EmitContext ec, AddressOp mode)
13063                 {
13064                         expr.Emit (ec);
13065                 }
13066
13067                 public void Emit (EmitContext ec, bool leave_copy)
13068                 {
13069                         Emit (ec);
13070                         if (leave_copy) {
13071                                 ec.Emit (OpCodes.Dup);
13072                                 temporary = new LocalTemporary (type);
13073                                 temporary.Store (ec);
13074                         }
13075                 }
13076
13077                 public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool isCompound)
13078                 {
13079                         prepared = isCompound;
13080
13081                         expr.Emit (ec);
13082
13083                         if (isCompound)
13084                                 ec.Emit (OpCodes.Dup);
13085
13086                         source.Emit (ec);
13087                         if (leave_copy) {
13088                                 throw new NotImplementedException ("leave_copy");
13089                         }
13090
13091                         ec.EmitStoreFromPtr (type);
13092
13093                         if (temporary != null) {
13094                                 temporary.Emit (ec);
13095                                 temporary.Release (ec);
13096                         }
13097                 }
13098
13099                 protected override Expression DoResolve (ResolveContext rc)
13100                 {
13101                         eclass = ExprClass.Variable;
13102                         return this;
13103                 }
13104
13105                 public override Expression DoResolveLValue (ResolveContext rc, Expression right_side)
13106                 {
13107                         return DoResolve (rc);
13108                 }
13109
13110                 public override void Emit (EmitContext ec)
13111                 {
13112                         if (!prepared)
13113                                 base.Emit(ec);
13114
13115                         ec.EmitLoadFromPtr (type);
13116                 }
13117
13118                 public override object Accept (StructuralVisitor visitor)
13119                 {
13120                         return visitor.Visit (this);
13121                 }
13122         }
13123 }