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