mcs/mcs/expression.cs

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