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