mcs/mcs/ecore.cs

   1 //
   2 // ecore.cs: Core of the Expression representation for the intermediate tree.
   3 //
   4 // Author:
   5 //   Miguel de Icaza (miguel@ximian.com)
   6 //   Marek Safar (marek.safar@seznam.cz)
   7 //
   8 // Copyright 2001, 2002, 2003 Ximian, Inc.
   9 // Copyright 2003-2008 Novell, Inc.
  10 // Copyright 2011 Xamarin Inc.
  11 //
  12 //
  13
  14 using System;
  15 using System.Collections.Generic;
  16 using System.Text;
  17 using SLE = System.Linq.Expressions;
  18 using System.Linq;
  19
  20 #if STATIC
  21 using IKVM.Reflection;
  22 using IKVM.Reflection.Emit;
  23 #else
  24 using System.Reflection;
  25 using System.Reflection.Emit;
  26 #endif
  27
  28 namespace Mono.CSharp {
  29
  30         /// <remarks>
  31         ///   The ExprClass class contains the is used to pass the
  32         ///   classification of an expression (value, variable, namespace,
  33         ///   type, method group, property access, event access, indexer access,
  34         ///   nothing).
  35         /// </remarks>
  36         public enum ExprClass : byte {
  37                 Unresolved      = 0,
  38
  39                 Value,
  40                 Variable,
  41                 Namespace,
  42                 Type,
  43                 TypeParameter,
  44                 MethodGroup,
  45                 PropertyAccess,
  46                 EventAccess,
  47                 IndexerAccess,
  48                 Nothing,
  49         }
  50
  51         /// <remarks>
  52         ///   This is used to tell Resolve in which types of expressions we're
  53         ///   interested.
  54         /// </remarks>
  55         [Flags]
  56         public enum ResolveFlags {
  57                 // Returns Value, Variable, PropertyAccess, EventAccess or IndexerAccess.
  58                 VariableOrValue         = 1,
  59
  60                 // Returns a type expression.
  61                 Type                    = 1 << 1,
  62
  63                 // Returns a method group.
  64                 MethodGroup             = 1 << 2,
  65
  66                 TypeParameter   = 1 << 3,
  67
  68                 // Mask of all the expression class flags.
  69                 MaskExprClass = VariableOrValue | Type | MethodGroup | TypeParameter,
  70         }
  71
  72         //
  73         // This is just as a hint to AddressOf of what will be done with the
  74         // address.
  75         [Flags]
  76         public enum AddressOp {
  77                 Store = 1,
  78                 Load  = 2,
  79                 LoadStore = 3
  80         };
  81
  82         /// <summary>
  83         ///   This interface is implemented by variables
  84         /// </summary>
  85         public interface IMemoryLocation {
  86                 /// <summary>
  87                 ///   The AddressOf method should generate code that loads
  88                 ///   the address of the object and leaves it on the stack.
  89                 ///
  90                 ///   The `mode' argument is used to notify the expression
  91                 ///   of whether this will be used to read from the address or
  92                 ///   write to the address.
  93                 ///
  94                 ///   This is just a hint that can be used to provide good error
  95                 ///   reporting, and should have no other side effects.
  96                 /// </summary>
  97                 void AddressOf (EmitContext ec, AddressOp mode);
  98         }
  99
 100         //
 101         // An expressions resolved as a direct variable reference
 102         //
 103         public interface IVariableReference : IFixedExpression
 104         {
 105                 bool IsHoisted { get; }
 106                 string Name { get; }
 107                 VariableInfo VariableInfo { get; }
 108
 109                 void SetHasAddressTaken ();
 110         }
 111
 112         //
 113         // Implemented by an expression which could be or is always
 114         // fixed
 115         //
 116         public interface IFixedExpression
 117         {
 118                 bool IsFixed { get; }
 119         }
 120
 121         public interface IExpressionCleanup
 122         {
 123                 void EmitCleanup (EmitContext ec);
 124         }
 125
 126         /// <remarks>
 127         ///   Base class for expressions
 128         /// </remarks>
 129         public abstract class Expression {
 130                 public ExprClass eclass;
 131                 protected TypeSpec type;
 132                 protected Location loc;
 133
 134                 public TypeSpec Type {
 135                         get { return type; }
 136                         set { type = value; }
 137                 }
 138
 139                 public virtual bool IsSideEffectFree {
 140                         get {
 141                                 return false;
 142                         }
 143                 }
 144
 145                 public Location Location {
 146                         get { return loc; }
 147                 }
 148
 149                 public virtual bool IsNull {
 150                         get {
 151                                 return false;
 152                         }
 153                 }
 154
 155                 //
 156                 // Returns true when the expression during Emit phase breaks stack
 157                 // by using await expression
 158                 //
 159                 public virtual bool ContainsEmitWithAwait ()
 160                 {
 161                         return false;
 162                 }
 163
 164                 /// <summary>
 165                 ///   Performs semantic analysis on the Expression
 166                 /// </summary>
 167                 ///
 168                 /// <remarks>
 169                 ///   The Resolve method is invoked to perform the semantic analysis
 170                 ///   on the node.
 171                 ///
 172                 ///   The return value is an expression (it can be the
 173                 ///   same expression in some cases) or a new
 174                 ///   expression that better represents this node.
 175                 ///
 176                 ///   For example, optimizations of Unary (LiteralInt)
 177                 ///   would return a new LiteralInt with a negated
 178                 ///   value.
 179                 ///
 180                 ///   If there is an error during semantic analysis,
 181                 ///   then an error should be reported (using Report)
 182                 ///   and a null value should be returned.
 183                 ///
 184                 ///   There are two side effects expected from calling
 185                 ///   Resolve(): the the field variable "eclass" should
 186                 ///   be set to any value of the enumeration
 187                 ///   `ExprClass' and the type variable should be set
 188                 ///   to a valid type (this is the type of the
 189                 ///   expression).
 190                 /// </remarks>
 191                 protected abstract Expression DoResolve (ResolveContext rc);
 192
 193                 public virtual Expression DoResolveLValue (ResolveContext rc, Expression right_side)
 194                 {
 195                         return null;
 196                 }
 197
 198                 //
 199                 // This is used if the expression should be resolved as a type or namespace name.
 200                 // the default implementation fails.
 201                 //
 202                 public virtual TypeSpec ResolveAsType (IMemberContext mc)
 203                 {
 204                         ResolveContext ec = new ResolveContext (mc);
 205                         Expression e = Resolve (ec);
 206                         if (e != null)
 207                                 e.Error_UnexpectedKind (ec, ResolveFlags.Type, loc);
 208
 209                         return null;
 210                 }
 211
 212                 public static void ErrorIsInaccesible (IMemberContext rc, string member, Location loc)
 213                 {
 214                         rc.Module.Compiler.Report.Error (122, loc, "`{0}' is inaccessible due to its protection level", member);
 215                 }
 216
 217                 public void Error_ExpressionMustBeConstant (ResolveContext rc, Location loc, string e_name)
 218                 {
 219                         rc.Report.Error (133, loc, "The expression being assigned to `{0}' must be constant", e_name);
 220                 }
 221
 222                 public void Error_ConstantCanBeInitializedWithNullOnly (ResolveContext rc, TypeSpec type, Location loc, string name)
 223                 {
 224                         rc.Report.Error (134, loc, "A constant `{0}' of reference type `{1}' can only be initialized with null",
 225                                 name, TypeManager.CSharpName (type));
 226                 }
 227
 228                 public static void Error_InvalidExpressionStatement (Report Report, Location loc)
 229                 {
 230                         Report.Error (201, loc, "Only assignment, call, increment, decrement, await, and new object expressions can be used as a statement");
 231                 }
 232
 233                 public void Error_InvalidExpressionStatement (BlockContext ec)
 234                 {
 235                         Error_InvalidExpressionStatement (ec.Report, loc);
 236                 }
 237
 238                 public static void Error_VoidInvalidInTheContext (Location loc, Report Report)
 239                 {
 240                         Report.Error (1547, loc, "Keyword `void' cannot be used in this context");
 241                 }
 242
 243                 public virtual void Error_ValueCannotBeConverted (ResolveContext ec, Location loc, TypeSpec target, bool expl)
 244                 {
 245                         Error_ValueCannotBeConvertedCore (ec, loc, target, expl);
 246                 }
 247
 248                 protected void Error_ValueCannotBeConvertedCore (ResolveContext ec, Location loc, TypeSpec target, bool expl)
 249                 {
 250                         // The error was already reported as CS1660
 251                         if (type == InternalType.AnonymousMethod || type == InternalType.ErrorType)
 252                                 return;
 253
 254                         string from_type = type.GetSignatureForError ();
 255                         string to_type = target.GetSignatureForError ();
 256                         if (from_type == to_type) {
 257                                 from_type = type.GetSignatureForErrorIncludingAssemblyName ();
 258                                 to_type = target.GetSignatureForErrorIncludingAssemblyName ();
 259                         }
 260
 261                         if (expl) {
 262                                 ec.Report.Error (30, loc, "Cannot convert type `{0}' to `{1}'",
 263                                         from_type, to_type);
 264                                 return;
 265                         }
 266
 267                         ec.Report.DisableReporting ();
 268                         bool expl_exists = Convert.ExplicitConversion (ec, this, target, Location.Null) != null;
 269                         ec.Report.EnableReporting ();
 270
 271                         if (expl_exists) {
 272                                 ec.Report.Error (266, loc,
 273                                         "Cannot implicitly convert type `{0}' to `{1}'. An explicit conversion exists (are you missing a cast?)",
 274                                         from_type, to_type);
 275                         } else {
 276                                 ec.Report.Error (29, loc, "Cannot implicitly convert type `{0}' to `{1}'",
 277                                         from_type, to_type);
 278                         }
 279                 }
 280
 281                 public void Error_TypeArgumentsCannotBeUsed (IMemberContext context, MemberSpec member, int arity, Location loc)
 282                 {
 283                         // Better message for possible generic expressions
 284                         if (member != null && (member.Kind & MemberKind.GenericMask) != 0) {
 285                                 var report = context.Module.Compiler.Report;
 286                                 report.SymbolRelatedToPreviousError (member);
 287                                 if (member is TypeSpec)
 288                                         member = ((TypeSpec) member).GetDefinition ();
 289                                 else
 290                                         member = ((MethodSpec) member).GetGenericMethodDefinition ();
 291
 292                                 string name = member.Kind == MemberKind.Method ? "method" : "type";
 293                                 if (member.IsGeneric) {
 294                                         report.Error (305, loc, "Using the generic {0} `{1}' requires `{2}' type argument(s)",
 295                                                 name, member.GetSignatureForError (), member.Arity.ToString ());
 296                                 } else {
 297                                         report.Error (308, loc, "The non-generic {0} `{1}' cannot be used with the type arguments",
 298                                                 name, member.GetSignatureForError ());
 299                                 }
 300                         } else {
 301                                 Error_TypeArgumentsCannotBeUsed (context, ExprClassName, GetSignatureForError (), loc);
 302                         }
 303                 }
 304
 305                 public void Error_TypeArgumentsCannotBeUsed (IMemberContext context, string exprType, string name, Location loc)
 306                 {
 307                         context.Module.Compiler.Report.Error (307, loc, "The {0} `{1}' cannot be used with type arguments",
 308                                 exprType, name);
 309                 }
 310
 311                 protected virtual void Error_TypeDoesNotContainDefinition (ResolveContext ec, TypeSpec type, string name)
 312                 {
 313                         Error_TypeDoesNotContainDefinition (ec, loc, type, name);
 314                 }
 315
 316                 public static void Error_TypeDoesNotContainDefinition (ResolveContext ec, Location loc, TypeSpec type, string name)
 317                 {
 318                         ec.Report.SymbolRelatedToPreviousError (type);
 319                         ec.Report.Error (117, loc, "`{0}' does not contain a definition for `{1}'",
 320                                 TypeManager.CSharpName (type), name);
 321                 }
 322
 323                 public void Error_ValueAssignment (ResolveContext rc, Expression rhs)
 324                 {
 325                         if (rhs == EmptyExpression.LValueMemberAccess || rhs == EmptyExpression.LValueMemberOutAccess) {
 326                                 rc.Report.SymbolRelatedToPreviousError (type);
 327                                 if (rc.CurrentInitializerVariable != null) {
 328                                         rc.Report.Error (1918, loc, "Members of value type `{0}' cannot be assigned using a property `{1}' object initializer",
 329                                                 type.GetSignatureForError (), GetSignatureForError ());
 330                                 } else {
 331                                         rc.Report.Error (1612, loc, "Cannot modify a value type return value of `{0}'. Consider storing the value in a temporary variable",
 332                                                 GetSignatureForError ());
 333                                 }
 334                         } else {
 335                                 rc.Report.Error (131, loc, "The left-hand side of an assignment must be a variable, a property or an indexer");
 336                         }
 337                 }
 338
 339                 protected void Error_VoidPointerOperation (ResolveContext rc)
 340                 {
 341                         rc.Report.Error (242, loc, "The operation in question is undefined on void pointers");
 342                 }
 343
 344                 public ResolveFlags ExprClassToResolveFlags {
 345                         get {
 346                                 switch (eclass) {
 347                                 case ExprClass.Type:
 348                                 case ExprClass.Namespace:
 349                                         return ResolveFlags.Type;
 350
 351                                 case ExprClass.MethodGroup:
 352                                         return ResolveFlags.MethodGroup;
 353
 354                                 case ExprClass.TypeParameter:
 355                                         return ResolveFlags.TypeParameter;
 356
 357                                 case ExprClass.Value:
 358                                 case ExprClass.Variable:
 359                                 case ExprClass.PropertyAccess:
 360                                 case ExprClass.EventAccess:
 361                                 case ExprClass.IndexerAccess:
 362                                         return ResolveFlags.VariableOrValue;
 363
 364                                 default:
 365                                         throw new InternalErrorException (loc.ToString () + " " +  GetType () + " ExprClass is Invalid after resolve");
 366                                 }
 367                         }
 368                 }
 369
 370                 public virtual string GetSignatureForError ()
 371                 {
 372                         return type.GetDefinition ().GetSignatureForError ();
 373                 }
 374
 375                 /// <summary>
 376                 ///   Resolves an expression and performs semantic analysis on it.
 377                 /// </summary>
 378                 ///
 379                 /// <remarks>
 380                 ///   Currently Resolve wraps DoResolve to perform sanity
 381                 ///   checking and assertion checking on what we expect from Resolve.
 382                 /// </remarks>
 383                 public Expression Resolve (ResolveContext ec, ResolveFlags flags)
 384                 {
 385                         if (eclass != ExprClass.Unresolved)
 386                                 return this;
 387
 388                         Expression e;
 389                         try {
 390                                 e = DoResolve (ec);
 391
 392                                 if (e == null)
 393                                         return null;
 394
 395                                 if ((flags & e.ExprClassToResolveFlags) == 0) {
 396                                         e.Error_UnexpectedKind (ec, flags, loc);
 397                                         return null;
 398                                 }
 399
 400                                 if (e.type == null)
 401                                         throw new InternalErrorException ("Expression `{0}' didn't set its type in DoResolve", e.GetType ());
 402
 403                                 return e;
 404                         } catch (Exception ex) {
 405                                 if (loc.IsNull || ec.Module.Compiler.Settings.DebugFlags > 0 || ex is CompletionResult || ec.Report.IsDisabled || ex is FatalException)
 406                                         throw;
 407
 408                                 ec.Report.Error (584, loc, "Internal compiler error: {0}", ex.Message);
 409                                 return ErrorExpression.Instance;        // TODO: Add location
 410                         }
 411                 }
 412
 413                 /// <summary>
 414                 ///   Resolves an expression and performs semantic analysis on it.
 415                 /// </summary>
 416                 public Expression Resolve (ResolveContext rc)
 417                 {
 418                         return Resolve (rc, ResolveFlags.VariableOrValue | ResolveFlags.MethodGroup);
 419                 }
 420
 421                 /// <summary>
 422                 ///   Resolves an expression for LValue assignment
 423                 /// </summary>
 424                 ///
 425                 /// <remarks>
 426                 ///   Currently ResolveLValue wraps DoResolveLValue to perform sanity
 427                 ///   checking and assertion checking on what we expect from Resolve
 428                 /// </remarks>
 429                 public Expression ResolveLValue (ResolveContext ec, Expression right_side)
 430                 {
 431                         int errors = ec.Report.Errors;
 432                         bool out_access = right_side == EmptyExpression.OutAccess;
 433
 434                         Expression e = DoResolveLValue (ec, right_side);
 435
 436                         if (e != null && out_access && !(e is IMemoryLocation)) {
 437                                 // FIXME: There's no problem with correctness, the 'Expr = null' handles that.
 438                                 //        Enabling this 'throw' will "only" result in deleting useless code elsewhere,
 439
 440                                 //throw new InternalErrorException ("ResolveLValue didn't return an IMemoryLocation: " +
 441                                 //                                e.GetType () + " " + e.GetSignatureForError ());
 442                                 e = null;
 443                         }
 444
 445                         if (e == null) {
 446                                 if (errors == ec.Report.Errors) {
 447                                         if (out_access)
 448                                                 ec.Report.Error (1510, loc, "A ref or out argument must be an assignable variable");
 449                                         else
 450                                                 Error_ValueAssignment (ec, right_side);
 451                                 }
 452                                 return null;
 453                         }
 454
 455                         if (e.eclass == ExprClass.Unresolved)
 456                                 throw new Exception ("Expression " + e + " ExprClass is Invalid after resolve");
 457
 458                         if ((e.type == null) && !(e is GenericTypeExpr))
 459                                 throw new Exception ("Expression " + e + " did not set its type after Resolve");
 460
 461                         return e;
 462                 }
 463
 464                 public virtual void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
 465                 {
 466                         rc.Module.Compiler.Report.Error (182, loc,
 467                                 "An attribute argument must be a constant expression, typeof expression or array creation expression");
 468                 }
 469
 470                 /// <summary>
 471                 ///   Emits the code for the expression
 472                 /// </summary>
 473                 ///
 474                 /// <remarks>
 475                 ///   The Emit method is invoked to generate the code
 476                 ///   for the expression.
 477                 /// </remarks>
 478                 public abstract void Emit (EmitContext ec);
 479
 480
 481                 // Emit code to branch to @target if this expression is equivalent to @on_true.
 482                 // The default implementation is to emit the value, and then emit a brtrue or brfalse.
 483                 // Subclasses can provide more efficient implementations, but those MUST be equivalent,
 484                 // including the use of conditional branches.  Note also that a branch MUST be emitted
 485                 public virtual void EmitBranchable (EmitContext ec, Label target, bool on_true)
 486                 {
 487                         Emit (ec);
 488                         ec.Emit (on_true ? OpCodes.Brtrue : OpCodes.Brfalse, target);
 489                 }
 490
 491                 // Emit this expression for its side effects, not for its value.
 492                 // The default implementation is to emit the value, and then throw it away.
 493                 // Subclasses can provide more efficient implementations, but those MUST be equivalent
 494                 public virtual void EmitSideEffect (EmitContext ec)
 495                 {
 496                         Emit (ec);
 497                         ec.Emit (OpCodes.Pop);
 498                 }
 499
 500                 //
 501                 // Emits the expression into temporary field variable. The method
 502                 // should be used for await expressions only
 503                 //
 504                 public virtual Expression EmitToField (EmitContext ec)
 505                 {
 506                         //
 507                         // This is the await prepare Emit method. When emitting code like
 508                         // a + b we emit code like
 509                         //
 510                         // a.Emit ()
 511                         // b.Emit ()
 512                         // Opcodes.Add
 513                         //
 514                         // For await a + await b we have to interfere the flow to keep the
 515                         // stack clean because await yields from the expression. The emit
 516                         // then changes to
 517                         //
 518                         // a = a.EmitToField () // a is changed to temporary field access
 519                         // b = b.EmitToField ()
 520                         // a.Emit ()
 521                         // b.Emit ()
 522                         // Opcodes.Add
 523                         //
 524                         //
 525                         // The idea is to emit expression and leave the stack empty with
 526                         // result value still available.
 527                         //
 528                         // Expressions should override this default implementation when
 529                         // optimized version can be provided (e.g. FieldExpr)
 530                         //
 531                         //
 532                         // We can optimize for side-effect free expressions, they can be
 533                         // emitted out of order
 534                         //
 535                         if (IsSideEffectFree)
 536                                 return this;
 537
 538                         bool needs_temporary = ContainsEmitWithAwait ();
 539                         if (!needs_temporary)
 540                                 ec.EmitThis ();
 541
 542                         // Emit original code
 543                         var field = EmitToFieldSource (ec);
 544                         if (field == null) {
 545                                 //
 546                                 // Store the result to temporary field when we
 547                                 // cannot load `this' directly
 548                                 //
 549                                 field = ec.GetTemporaryField (type);
 550                                 if (needs_temporary) {
 551                                         //
 552                                         // Create temporary local (we cannot load `this' before Emit)
 553                                         //
 554                                         var temp = ec.GetTemporaryLocal (type);
 555                                         ec.Emit (OpCodes.Stloc, temp);
 556
 557                                         ec.EmitThis ();
 558                                         ec.Emit (OpCodes.Ldloc, temp);
 559                                         field.EmitAssignFromStack (ec);
 560
 561                                         ec.FreeTemporaryLocal (temp, type);
 562                                 } else {
 563                                         field.EmitAssignFromStack (ec);
 564                                 }
 565                         }
 566
 567                         return field;
 568                 }
 569
 570                 protected virtual FieldExpr EmitToFieldSource (EmitContext ec)
 571                 {
 572                         //
 573                         // Default implementation calls Emit method
 574                         //
 575                         Emit (ec);
 576                         return null;
 577                 }
 578
 579                 protected static void EmitExpressionsList (EmitContext ec, List<Expression> expressions)
 580                 {
 581                         if (ec.HasSet (BuilderContext.Options.AsyncBody)) {
 582                                 bool contains_await = false;
 583
 584                                 for (int i = 1; i < expressions.Count; ++i) {
 585                                         if (expressions[i].ContainsEmitWithAwait ()) {
 586                                                 contains_await = true;
 587                                                 break;
 588                                         }
 589                                 }
 590
 591                                 if (contains_await) {
 592                                         for (int i = 0; i < expressions.Count; ++i) {
 593                                                 expressions[i] = expressions[i].EmitToField (ec);
 594                                         }
 595                                 }
 596                         }
 597
 598                         for (int i = 0; i < expressions.Count; ++i) {
 599                                 expressions[i].Emit (ec);
 600                         }
 601                 }
 602
 603                 /// <summary>
 604                 ///   Protected constructor.  Only derivate types should
 605                 ///   be able to be created
 606                 /// </summary>
 607
 608                 protected Expression ()
 609                 {
 610                 }
 611
 612                 /// <summary>
 613                 ///   Returns a fully formed expression after a MemberLookup
 614                 /// </summary>
 615                 ///
 616                 static Expression ExprClassFromMemberInfo (MemberSpec spec, Location loc)
 617                 {
 618                         if (spec is EventSpec)
 619                                 return new EventExpr ((EventSpec) spec, loc);
 620                         if (spec is ConstSpec)
 621                                 return new ConstantExpr ((ConstSpec) spec, loc);
 622                         if (spec is FieldSpec)
 623                                 return new FieldExpr ((FieldSpec) spec, loc);
 624                         if (spec is PropertySpec)
 625                                 return new PropertyExpr ((PropertySpec) spec, loc);
 626                         if (spec is TypeSpec)
 627                                 return new TypeExpression (((TypeSpec) spec), loc);
 628
 629                         return null;
 630                 }
 631
 632                 public static MethodSpec ConstructorLookup (ResolveContext rc, TypeSpec type, ref Arguments args, Location loc)
 633                 {
 634                         var ctors = MemberCache.FindMembers (type, Constructor.ConstructorName, true);
 635                         if (ctors == null) {
 636                                 rc.Report.SymbolRelatedToPreviousError (type);
 637                                 if (type.IsStruct) {
 638                                         // Report meaningful error for struct as they always have default ctor in C# context
 639                                         OverloadResolver.Error_ConstructorMismatch (rc, type, args == null ? 0 : args.Count, loc);
 640                                 } else {
 641                                         rc.Report.Error (143, loc, "The class `{0}' has no constructors defined",
 642                                                 type.GetSignatureForError ());
 643                                 }
 644
 645                                 return null;
 646                         }
 647
 648                         var r = new OverloadResolver (ctors, OverloadResolver.Restrictions.NoBaseMembers, loc);
 649                         if (!rc.HasSet (ResolveContext.Options.BaseInitializer)) {
 650                                 r.InstanceQualifier = new ConstructorInstanceQualifier (type);
 651                         }
 652
 653                         return r.ResolveMember<MethodSpec> (rc, ref args);
 654                 }
 655
 656                 [Flags]
 657                 public enum MemberLookupRestrictions
 658                 {
 659                         None = 0,
 660                         InvocableOnly = 1,
 661                         ExactArity = 1 << 2,
 662                         ReadAccess = 1 << 3
 663                 }
 664
 665                 //
 666                 // Lookup type `queried_type' for code in class `container_type' with a qualifier of
 667                 // `qualifier_type' or null to lookup members in the current class.
 668                 //
 669                 public static Expression MemberLookup (IMemberContext rc, bool errorMode, TypeSpec queried_type, string name, int arity, MemberLookupRestrictions restrictions, Location loc)
 670                 {
 671                         var members = MemberCache.FindMembers (queried_type, name, false);
 672                         if (members == null)
 673                                 return null;
 674
 675                         MemberSpec non_method = null;
 676                         MemberSpec ambig_non_method = null;
 677                         do {
 678                                 for (int i = 0; i < members.Count; ++i) {
 679                                         var member = members[i];
 680
 681                                         // HACK: for events because +=/-= can appear at same class only, should use OverrideToBase there
 682                                         if ((member.Modifiers & Modifiers.OVERRIDE) != 0 && member.Kind != MemberKind.Event)
 683                                                 continue;
 684
 685                                         if ((member.Modifiers & Modifiers.BACKING_FIELD) != 0)
 686                                                 continue;
 687
 688                                         if ((arity > 0 || (restrictions & MemberLookupRestrictions.ExactArity) != 0) && member.Arity != arity)
 689                                                 continue;
 690
 691                                         if (!errorMode) {
 692                                                 if (!member.IsAccessible (rc))
 693                                                         continue;
 694
 695                                                 //
 696                                                 // With runtime binder we can have a situation where queried type is inaccessible
 697                                                 // because it came via dynamic object, the check about inconsisted accessibility
 698                                                 // had no effect as the type was unknown during compilation
 699                                                 //
 700                                                 // class A {
 701                                                 //              private class N { }
 702                                                 //
 703                                                 //              public dynamic Foo ()
 704                                                 //              {
 705                                                 //                      return new N ();
 706                                                 //              }
 707                                                 //      }
 708                                                 //
 709                                                 if (rc.Module.Compiler.IsRuntimeBinder && !member.DeclaringType.IsAccessible (rc))
 710                                                         continue;
 711                                         }
 712
 713                                         if ((restrictions & MemberLookupRestrictions.InvocableOnly) != 0) {
 714                                                 if (member is MethodSpec)
 715                                                         return new MethodGroupExpr (members, queried_type, loc);
 716
 717                                                 if (!Invocation.IsMemberInvocable (member))
 718                                                         continue;
 719                                         }
 720
 721                                         if (non_method == null || member is MethodSpec || non_method.IsNotCSharpCompatible) {
 722                                                 non_method = member;
 723                                         } else if (!errorMode && !member.IsNotCSharpCompatible) {
 724                                                 ambig_non_method = member;
 725                                         }
 726                                 }
 727
 728                                 if (non_method != null) {
 729                                         if (ambig_non_method != null && rc != null) {
 730                                                 var report = rc.Module.Compiler.Report;
 731                                                 report.SymbolRelatedToPreviousError (non_method);
 732                                                 report.SymbolRelatedToPreviousError (ambig_non_method);
 733                                                 report.Error (229, loc, "Ambiguity between `{0}' and `{1}'",
 734                                                         non_method.GetSignatureForError (), ambig_non_method.GetSignatureForError ());
 735                                         }
 736
 737                                         if (non_method is MethodSpec)
 738                                                 return new MethodGroupExpr (members, queried_type, loc);
 739
 740                                         return ExprClassFromMemberInfo (non_method, loc);
 741                                 }
 742
 743                                 if (members[0].DeclaringType.BaseType == null)
 744                                         members = null;
 745                                 else
 746                                         members = MemberCache.FindMembers (members[0].DeclaringType.BaseType, name, false);
 747
 748                         } while (members != null);
 749
 750                         return null;
 751                 }
 752
 753                 protected virtual void Error_NegativeArrayIndex (ResolveContext ec, Location loc)
 754                 {
 755                         throw new NotImplementedException ();
 756                 }
 757
 758                 public virtual void Error_OperatorCannotBeApplied (ResolveContext rc, Location loc, string oper, TypeSpec t)
 759                 {
 760                         if (t == InternalType.ErrorType)
 761                                 return;
 762
 763                         rc.Report.Error (23, loc, "The `{0}' operator cannot be applied to operand of type `{1}'",
 764                                 oper, t.GetSignatureForError ());
 765                 }
 766
 767                 protected void Error_PointerInsideExpressionTree (ResolveContext ec)
 768                 {
 769                         ec.Report.Error (1944, loc, "An expression tree cannot contain an unsafe pointer operation");
 770                 }
 771
 772                 /// <summary>
 773                 ///   Returns an expression that can be used to invoke operator true
 774                 ///   on the expression if it exists.
 775                 /// </summary>
 776                 protected static Expression GetOperatorTrue (ResolveContext ec, Expression e, Location loc)
 777                 {
 778                         return GetOperatorTrueOrFalse (ec, e, true, loc);
 779                 }
 780
 781                 /// <summary>
 782                 ///   Returns an expression that can be used to invoke operator false
 783                 ///   on the expression if it exists.
 784                 /// </summary>
 785                 protected static Expression GetOperatorFalse (ResolveContext ec, Expression e, Location loc)
 786                 {
 787                         return GetOperatorTrueOrFalse (ec, e, false, loc);
 788                 }
 789
 790                 static Expression GetOperatorTrueOrFalse (ResolveContext ec, Expression e, bool is_true, Location loc)
 791                 {
 792                         var op = is_true ? Operator.OpType.True : Operator.OpType.False;
 793                         var methods = MemberCache.GetUserOperator (e.type, op, false);
 794                         if (methods == null)
 795                                 return null;
 796
 797                         Arguments arguments = new Arguments (1);
 798                         arguments.Add (new Argument (e));
 799
 800                         var res = new OverloadResolver (methods, OverloadResolver.Restrictions.BaseMembersIncluded | OverloadResolver.Restrictions.NoBaseMembers, loc);
 801                         var oper = res.ResolveOperator (ec, ref arguments);
 802
 803                         if (oper == null)
 804                                 return null;
 805
 806                         return new UserOperatorCall (oper, arguments, null, loc);
 807                 }
 808
 809                 public virtual string ExprClassName
 810                 {
 811                         get {
 812                                 switch (eclass){
 813                                 case ExprClass.Unresolved:
 814                                         return "Unresolved";
 815                                 case ExprClass.Value:
 816                                         return "value";
 817                                 case ExprClass.Variable:
 818                                         return "variable";
 819                                 case ExprClass.Namespace:
 820                                         return "namespace";
 821                                 case ExprClass.Type:
 822                                         return "type";
 823                                 case ExprClass.MethodGroup:
 824                                         return "method group";
 825                                 case ExprClass.PropertyAccess:
 826                                         return "property access";
 827                                 case ExprClass.EventAccess:
 828                                         return "event access";
 829                                 case ExprClass.IndexerAccess:
 830                                         return "indexer access";
 831                                 case ExprClass.Nothing:
 832                                         return "null";
 833                                 case ExprClass.TypeParameter:
 834                                         return "type parameter";
 835                                 }
 836                                 throw new Exception ("Should not happen");
 837                         }
 838                 }
 839
 840                 /// <summary>
 841                 ///   Reports that we were expecting `expr' to be of class `expected'
 842                 /// </summary>
 843                 public void Error_UnexpectedKind (IMemberContext ctx, Expression memberExpr, string expected, string was, Location loc)
 844                 {
 845                         var name = memberExpr.GetSignatureForError ();
 846
 847                         ctx.Module.Compiler.Report.Error (118, loc, "`{0}' is a `{1}' but a `{2}' was expected", name, was, expected);
 848                 }
 849
 850                 public virtual void Error_UnexpectedKind (ResolveContext ec, ResolveFlags flags, Location loc)
 851                 {
 852                         string [] valid = new string [4];
 853                         int count = 0;
 854
 855                         if ((flags & ResolveFlags.VariableOrValue) != 0) {
 856                                 valid [count++] = "variable";
 857                                 valid [count++] = "value";
 858                         }
 859
 860                         if ((flags & ResolveFlags.Type) != 0)
 861                                 valid [count++] = "type";
 862
 863                         if ((flags & ResolveFlags.MethodGroup) != 0)
 864                                 valid [count++] = "method group";
 865
 866                         if (count == 0)
 867                                 valid [count++] = "unknown";
 868
 869                         StringBuilder sb = new StringBuilder (valid [0]);
 870                         for (int i = 1; i < count - 1; i++) {
 871                                 sb.Append ("', `");
 872                                 sb.Append (valid [i]);
 873                         }
 874                         if (count > 1) {
 875                                 sb.Append ("' or `");
 876                                 sb.Append (valid [count - 1]);
 877                         }
 878
 879                         ec.Report.Error (119, loc,
 880                                 "Expression denotes a `{0}', where a `{1}' was expected", ExprClassName, sb.ToString ());
 881                 }
 882
 883                 public static void UnsafeError (ResolveContext ec, Location loc)
 884                 {
 885                         UnsafeError (ec.Report, loc);
 886                 }
 887
 888                 public static void UnsafeError (Report Report, Location loc)
 889                 {
 890                         Report.Error (214, loc, "Pointers and fixed size buffers may only be used in an unsafe context");
 891                 }
 892
 893                 //
 894                 // Converts `source' to an int, uint, long or ulong.
 895                 //
 896                 protected Expression ConvertExpressionToArrayIndex (ResolveContext ec, Expression source)
 897                 {
 898                         var btypes = ec.BuiltinTypes;
 899
 900                         if (source.type.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
 901                                 Arguments args = new Arguments (1);
 902                                 args.Add (new Argument (source));
 903                                 return new DynamicConversion (btypes.Int, CSharpBinderFlags.ConvertArrayIndex, args, loc).Resolve (ec);
 904                         }
 905
 906                         Expression converted;
 907
 908                         using (ec.Set (ResolveContext.Options.CheckedScope)) {
 909                                 converted = Convert.ImplicitConversion (ec, source, btypes.Int, source.loc);
 910                                 if (converted == null)
 911                                         converted = Convert.ImplicitConversion (ec, source, btypes.UInt, source.loc);
 912                                 if (converted == null)
 913                                         converted = Convert.ImplicitConversion (ec, source, btypes.Long, source.loc);
 914                                 if (converted == null)
 915                                         converted = Convert.ImplicitConversion (ec, source, btypes.ULong, source.loc);
 916
 917                                 if (converted == null) {
 918                                         source.Error_ValueCannotBeConverted (ec, source.loc, btypes.Int, false);
 919                                         return null;
 920                                 }
 921                         }
 922
 923                         //
 924                         // Only positive constants are allowed at compile time
 925                         //
 926                         Constant c = converted as Constant;
 927                         if (c != null && c.IsNegative)
 928                                 Error_NegativeArrayIndex (ec, source.loc);
 929
 930                         // No conversion needed to array index
 931                         if (converted.Type.BuiltinType == BuiltinTypeSpec.Type.Int)
 932                                 return converted;
 933
 934                         return new ArrayIndexCast (converted, btypes.Int).Resolve (ec);
 935                 }
 936
 937                 //
 938                 // Derived classes implement this method by cloning the fields that
 939                 // could become altered during the Resolve stage
 940                 //
 941                 // Only expressions that are created for the parser need to implement
 942                 // this.
 943                 //
 944                 protected virtual void CloneTo (CloneContext clonectx, Expression target)
 945                 {
 946                         throw new NotImplementedException (
 947                                 String.Format (
 948                                         "CloneTo not implemented for expression {0}", this.GetType ()));
 949                 }
 950
 951                 //
 952                 // Clones an expression created by the parser.
 953                 //
 954                 // We only support expressions created by the parser so far, not
 955                 // expressions that have been resolved (many more classes would need
 956                 // to implement CloneTo).
 957                 //
 958                 // This infrastructure is here merely for Lambda expressions which
 959                 // compile the same code using different type values for the same
 960                 // arguments to find the correct overload
 961                 //
 962                 public virtual Expression Clone (CloneContext clonectx)
 963                 {
 964                         Expression cloned = (Expression) MemberwiseClone ();
 965                         CloneTo (clonectx, cloned);
 966
 967                         return cloned;
 968                 }
 969
 970                 //
 971                 // Implementation of expression to expression tree conversion
 972                 //
 973                 public abstract Expression CreateExpressionTree (ResolveContext ec);
 974
 975                 protected Expression CreateExpressionFactoryCall (ResolveContext ec, string name, Arguments args)
 976                 {
 977                         return CreateExpressionFactoryCall (ec, name, null, args, loc);
 978                 }
 979
 980                 protected Expression CreateExpressionFactoryCall (ResolveContext ec, string name, TypeArguments typeArguments, Arguments args)
 981                 {
 982                         return CreateExpressionFactoryCall (ec, name, typeArguments, args, loc);
 983                 }
 984
 985                 public static Expression CreateExpressionFactoryCall (ResolveContext ec, string name, TypeArguments typeArguments, Arguments args, Location loc)
 986                 {
 987                         return new Invocation (new MemberAccess (CreateExpressionTypeExpression (ec, loc), name, typeArguments, loc), args);
 988                 }
 989
 990                 protected static TypeExpr CreateExpressionTypeExpression (ResolveContext ec, Location loc)
 991                 {
 992                         var t = ec.Module.PredefinedTypes.Expression.Resolve ();
 993                         if (t == null)
 994                                 return null;
 995
 996                         return new TypeExpression (t, loc);
 997                 }
 998
 999                 //
1000                 // Implemented by all expressions which support conversion from
1001                 // compiler expression to invokable runtime expression. Used by
1002                 // dynamic C# binder.
1003                 //
1004                 public virtual SLE.Expression MakeExpression (BuilderContext ctx)
1005                 {
1006                         throw new NotImplementedException ("MakeExpression for " + GetType ());
1007                 }
1008
1009                 public virtual object Accept (StructuralVisitor visitor)
1010                 {
1011                         return visitor.Visit (this);
1012                 }
1013         }
1014
1015         /// <summary>
1016         ///   This is just a base class for expressions that can
1017         ///   appear on statements (invocations, object creation,
1018         ///   assignments, post/pre increment and decrement).  The idea
1019         ///   being that they would support an extra Emition interface that
1020         ///   does not leave a result on the stack.
1021         /// </summary>
1022         public abstract class ExpressionStatement : Expression {
1023
1024                 public ExpressionStatement ResolveStatement (BlockContext ec)
1025                 {
1026                         Expression e = Resolve (ec);
1027                         if (e == null)
1028                                 return null;
1029
1030                         ExpressionStatement es = e as ExpressionStatement;
1031                         if (es == null)
1032                                 Error_InvalidExpressionStatement (ec);
1033
1034                         if (ec.CurrentAnonymousMethod is AsyncInitializer && !(e is Assign) &&
1035                                 (e.Type.IsGenericTask || e.Type == ec.Module.PredefinedTypes.Task.TypeSpec)) {
1036                                 ec.Report.Warning (4014, 1, e.Location,
1037                                         "The statement is not awaited and execution of current method continues before the call is completed. Consider using `await' operator");
1038                         }
1039
1040                         return es;
1041                 }
1042
1043                 /// <summary>
1044                 ///   Requests the expression to be emitted in a `statement'
1045                 ///   context.  This means that no new value is left on the
1046                 ///   stack after invoking this method (constrasted with
1047                 ///   Emit that will always leave a value on the stack).
1048                 /// </summary>
1049                 public abstract void EmitStatement (EmitContext ec);
1050
1051                 public override void EmitSideEffect (EmitContext ec)
1052                 {
1053                         EmitStatement (ec);
1054                 }
1055         }
1056
1057         /// <summary>
1058         ///   This kind of cast is used to encapsulate the child
1059         ///   whose type is child.Type into an expression that is
1060         ///   reported to return "return_type".  This is used to encapsulate
1061         ///   expressions which have compatible types, but need to be dealt
1062         ///   at higher levels with.
1063         ///
1064         ///   For example, a "byte" expression could be encapsulated in one
1065         ///   of these as an "unsigned int".  The type for the expression
1066         ///   would be "unsigned int".
1067         ///
1068         /// </summary>
1069         public abstract class TypeCast : Expression
1070         {
1071                 protected readonly Expression child;
1072
1073                 protected TypeCast (Expression child, TypeSpec return_type)
1074                 {
1075                         eclass = child.eclass;
1076                         loc = child.Location;
1077                         type = return_type;
1078                         this.child = child;
1079                 }
1080
1081                 public Expression Child {
1082                         get {
1083                                 return child;
1084                         }
1085                 }
1086
1087                 public override bool ContainsEmitWithAwait ()
1088                 {
1089                         return child.ContainsEmitWithAwait ();
1090                 }
1091
1092                 public override Expression CreateExpressionTree (ResolveContext ec)
1093                 {
1094                         Arguments args = new Arguments (2);
1095                         args.Add (new Argument (child.CreateExpressionTree (ec)));
1096                         args.Add (new Argument (new TypeOf (type, loc)));
1097
1098                         if (type.IsPointer || child.Type.IsPointer)
1099                                 Error_PointerInsideExpressionTree (ec);
1100
1101                         return CreateExpressionFactoryCall (ec, ec.HasSet (ResolveContext.Options.CheckedScope) ? "ConvertChecked" : "Convert", args);
1102                 }
1103
1104                 protected override Expression DoResolve (ResolveContext ec)
1105                 {
1106                         // This should never be invoked, we are born in fully
1107                         // initialized state.
1108
1109                         return this;
1110                 }
1111
1112                 public override void Emit (EmitContext ec)
1113                 {
1114                         child.Emit (ec);
1115                 }
1116
1117                 public override SLE.Expression MakeExpression (BuilderContext ctx)
1118                 {
1119 #if STATIC
1120                         return base.MakeExpression (ctx);
1121 #else
1122                         return ctx.HasSet (BuilderContext.Options.CheckedScope) ?
1123                                 SLE.Expression.ConvertChecked (child.MakeExpression (ctx), type.GetMetaInfo ()) :
1124                                 SLE.Expression.Convert (child.MakeExpression (ctx), type.GetMetaInfo ());
1125 #endif
1126                 }
1127
1128                 protected override void CloneTo (CloneContext clonectx, Expression t)
1129                 {
1130                         // Nothing to clone
1131                 }
1132
1133                 public override bool IsNull {
1134                         get { return child.IsNull; }
1135                 }
1136         }
1137
1138         public class EmptyCast : TypeCast {
1139                 EmptyCast (Expression child, TypeSpec target_type)
1140                         : base (child, target_type)
1141                 {
1142                 }
1143
1144                 public static Expression Create (Expression child, TypeSpec type)
1145                 {
1146                         Constant c = child as Constant;
1147                         if (c != null)
1148                                 return new EmptyConstantCast (c, type);
1149
1150                         EmptyCast e = child as EmptyCast;
1151                         if (e != null)
1152                                 return new EmptyCast (e.child, type);
1153
1154                         return new EmptyCast (child, type);
1155                 }
1156
1157                 public override void EmitBranchable (EmitContext ec, Label label, bool on_true)
1158                 {
1159                         child.EmitBranchable (ec, label, on_true);
1160                 }
1161
1162                 public override void EmitSideEffect (EmitContext ec)
1163                 {
1164                         child.EmitSideEffect (ec);
1165                 }
1166         }
1167
1168         //
1169         // Used for predefined type user operator (no obsolete check, etc.)
1170         //
1171         public class OperatorCast : TypeCast
1172         {
1173                 readonly MethodSpec conversion_operator;
1174
1175                 public OperatorCast (Expression expr, TypeSpec target_type)
1176                         : this (expr, target_type, target_type, false)
1177                 {
1178                 }
1179
1180                 public OperatorCast (Expression expr, TypeSpec target_type, bool find_explicit)
1181                         : this (expr, target_type, target_type, find_explicit)
1182                 {
1183                 }
1184
1185                 public OperatorCast (Expression expr, TypeSpec declaringType, TypeSpec returnType, bool isExplicit)
1186                         : base (expr, returnType)
1187                 {
1188                         var op = isExplicit ? Operator.OpType.Explicit : Operator.OpType.Implicit;
1189                         var mi = MemberCache.GetUserOperator (declaringType, op, true);
1190
1191                         if (mi != null) {
1192                                 foreach (MethodSpec oper in mi) {
1193                                         if (oper.ReturnType != returnType)
1194                                                 continue;
1195
1196                                         if (oper.Parameters.Types[0] == expr.Type) {
1197                                                 conversion_operator = oper;
1198                                                 return;
1199                                         }
1200                                 }
1201                         }
1202
1203                         throw new InternalErrorException ("Missing predefined user operator between `{0}' and `{1}'",
1204                                 returnType.GetSignatureForError (), expr.Type.GetSignatureForError ());
1205                 }
1206
1207                 public override void Emit (EmitContext ec)
1208                 {
1209                         child.Emit (ec);
1210                         ec.Emit (OpCodes.Call, conversion_operator);
1211                 }
1212         }
1213
1214         //
1215         // Constant specialization of EmptyCast.
1216         // We need to special case this since an empty cast of
1217         // a constant is still a constant.
1218         //
1219         public class EmptyConstantCast : Constant
1220         {
1221                 public readonly Constant child;
1222
1223                 public EmptyConstantCast (Constant child, TypeSpec type)
1224                         : base (child.Location)
1225                 {
1226                         if (child == null)
1227                                 throw new ArgumentNullException ("child");
1228
1229                         this.child = child;
1230                         this.eclass = child.eclass;
1231                         this.type = type;
1232                 }
1233
1234                 public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
1235                 {
1236                         if (child.Type == target_type)
1237                                 return child;
1238
1239                         // FIXME: check that 'type' can be converted to 'target_type' first
1240                         return child.ConvertExplicitly (in_checked_context, target_type);
1241                 }
1242
1243                 public override Expression CreateExpressionTree (ResolveContext ec)
1244                 {
1245                         Arguments args = Arguments.CreateForExpressionTree (ec, null,
1246                                 child.CreateExpressionTree (ec),
1247                                 new TypeOf (type, loc));
1248
1249                         if (type.IsPointer)
1250                                 Error_PointerInsideExpressionTree (ec);
1251
1252                         return CreateExpressionFactoryCall (ec, "Convert", args);
1253                 }
1254
1255                 public override bool IsDefaultValue {
1256                         get { return child.IsDefaultValue; }
1257                 }
1258
1259                 public override bool IsNegative {
1260                         get { return child.IsNegative; }
1261                 }
1262
1263                 public override bool IsNull {
1264                         get { return child.IsNull; }
1265                 }
1266
1267                 public override bool IsOneInteger {
1268                         get { return child.IsOneInteger; }
1269                 }
1270
1271                 public override bool IsSideEffectFree {
1272                         get {
1273                                 return child.IsSideEffectFree;
1274                         }
1275                 }
1276
1277                 public override bool IsZeroInteger {
1278                         get { return child.IsZeroInteger; }
1279                 }
1280
1281                 public override void Emit (EmitContext ec)
1282                 {
1283                         child.Emit (ec);
1284                 }
1285
1286                 public override void EmitBranchable (EmitContext ec, Label label, bool on_true)
1287                 {
1288                         child.EmitBranchable (ec, label, on_true);
1289
1290                         // Only to make verifier happy
1291                         if (TypeManager.IsGenericParameter (type) && child.IsNull)
1292                                 ec.Emit (OpCodes.Unbox_Any, type);
1293                 }
1294
1295                 public override void EmitSideEffect (EmitContext ec)
1296                 {
1297                         child.EmitSideEffect (ec);
1298                 }
1299
1300                 public override object GetValue ()
1301                 {
1302                         return child.GetValue ();
1303                 }
1304
1305                 public override string GetValueAsLiteral ()
1306                 {
1307                         return child.GetValueAsLiteral ();
1308                 }
1309
1310                 public override long GetValueAsLong ()
1311                 {
1312                         return child.GetValueAsLong ();
1313                 }
1314
1315                 public override Constant ConvertImplicitly (TypeSpec target_type)
1316                 {
1317                         if (type == target_type)
1318                                 return this;
1319
1320                         // FIXME: Do we need to check user conversions?
1321                         if (!Convert.ImplicitStandardConversionExists (this, target_type))
1322                                 return null;
1323
1324                         return child.ConvertImplicitly (target_type);
1325                 }
1326         }
1327
1328         /// <summary>
1329         ///  This class is used to wrap literals which belong inside Enums
1330         /// </summary>
1331         public class EnumConstant : Constant
1332         {
1333                 public Constant Child;
1334
1335                 public EnumConstant (Constant child, TypeSpec enum_type)
1336                         : base (child.Location)
1337                 {
1338                         this.Child = child;
1339
1340                         this.eclass = ExprClass.Value;
1341                         this.type = enum_type;
1342                 }
1343
1344                 protected EnumConstant (Location loc)
1345                         : base (loc)
1346                 {
1347                 }
1348
1349                 public override void Emit (EmitContext ec)
1350                 {
1351                         Child.Emit (ec);
1352                 }
1353
1354                 public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
1355                 {
1356                         Child.EncodeAttributeValue (rc, enc, Child.Type);
1357                 }
1358
1359                 public override void EmitBranchable (EmitContext ec, Label label, bool on_true)
1360                 {
1361                         Child.EmitBranchable (ec, label, on_true);
1362                 }
1363
1364                 public override void EmitSideEffect (EmitContext ec)
1365                 {
1366                         Child.EmitSideEffect (ec);
1367                 }
1368
1369                 public override string GetSignatureForError()
1370                 {
1371                         return TypeManager.CSharpName (Type);
1372                 }
1373
1374                 public override object GetValue ()
1375                 {
1376                         return Child.GetValue ();
1377                 }
1378
1379 #if !STATIC
1380                 public override object GetTypedValue ()
1381                 {
1382                         //
1383                         // The method can be used in dynamic context only (on closed types)
1384                         //
1385                         // System.Enum.ToObject cannot be called on dynamic types
1386                         // EnumBuilder has to be used, but we cannot use EnumBuilder
1387                         // because it does not properly support generics
1388                         //
1389                         return System.Enum.ToObject (type.GetMetaInfo (), Child.GetValue ());
1390                 }
1391 #endif
1392
1393                 public override string GetValueAsLiteral ()
1394                 {
1395                         return Child.GetValueAsLiteral ();
1396                 }
1397
1398                 public override long GetValueAsLong ()
1399                 {
1400                         return Child.GetValueAsLong ();
1401                 }
1402
1403                 public EnumConstant Increment()
1404                 {
1405                         return new EnumConstant (((IntegralConstant) Child).Increment (), type);
1406                 }
1407
1408                 public override bool IsDefaultValue {
1409                         get {
1410                                 return Child.IsDefaultValue;
1411                         }
1412                 }
1413
1414                 public override bool IsSideEffectFree {
1415                         get {
1416                                 return Child.IsSideEffectFree;
1417                         }
1418                 }
1419
1420                 public override bool IsZeroInteger {
1421                         get { return Child.IsZeroInteger; }
1422                 }
1423
1424                 public override bool IsNegative {
1425                         get {
1426                                 return Child.IsNegative;
1427                         }
1428                 }
1429
1430                 public override Constant ConvertExplicitly(bool in_checked_context, TypeSpec target_type)
1431                 {
1432                         if (Child.Type == target_type)
1433                                 return Child;
1434
1435                         return Child.ConvertExplicitly (in_checked_context, target_type);
1436                 }
1437
1438                 public override Constant ConvertImplicitly (TypeSpec type)
1439                 {
1440                         if (this.type == type) {
1441                                 return this;
1442                         }
1443
1444                         if (!Convert.ImplicitStandardConversionExists (this, type)){
1445                                 return null;
1446                         }
1447
1448                         return Child.ConvertImplicitly (type);
1449                 }
1450         }
1451
1452         /// <summary>
1453         ///   This kind of cast is used to encapsulate Value Types in objects.
1454         ///
1455         ///   The effect of it is to box the value type emitted by the previous
1456         ///   operation.
1457         /// </summary>
1458         public class BoxedCast : TypeCast {
1459
1460                 public BoxedCast (Expression expr, TypeSpec target_type)
1461                         : base (expr, target_type)
1462                 {
1463                         eclass = ExprClass.Value;
1464                 }
1465
1466                 protected override Expression DoResolve (ResolveContext ec)
1467                 {
1468                         // This should never be invoked, we are born in fully
1469                         // initialized state.
1470
1471                         return this;
1472                 }
1473
1474                 public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
1475                 {
1476                         // Only boxing to object type is supported
1477                         if (targetType.BuiltinType != BuiltinTypeSpec.Type.Object) {
1478                                 base.EncodeAttributeValue (rc, enc, targetType);
1479                                 return;
1480                         }
1481
1482                         enc.Encode (child.Type);
1483                         child.EncodeAttributeValue (rc, enc, child.Type);
1484                 }
1485
1486                 public override void Emit (EmitContext ec)
1487                 {
1488                         base.Emit (ec);
1489
1490                         ec.Emit (OpCodes.Box, child.Type);
1491                 }
1492
1493                 public override void EmitSideEffect (EmitContext ec)
1494                 {
1495                         // boxing is side-effectful, since it involves runtime checks, except when boxing to Object or ValueType
1496                         // so, we need to emit the box+pop instructions in most cases
1497                         if (child.Type.IsStruct &&
1498                             (type.BuiltinType == BuiltinTypeSpec.Type.Object || type.BuiltinType == BuiltinTypeSpec.Type.ValueType))
1499                                 child.EmitSideEffect (ec);
1500                         else
1501                                 base.EmitSideEffect (ec);
1502                 }
1503         }
1504
1505         public class UnboxCast : TypeCast {
1506                 public UnboxCast (Expression expr, TypeSpec return_type)
1507                         : base (expr, return_type)
1508                 {
1509                 }
1510
1511                 protected override Expression DoResolve (ResolveContext ec)
1512                 {
1513                         // This should never be invoked, we are born in fully
1514                         // initialized state.
1515
1516                         return this;
1517                 }
1518
1519                 public override void Emit (EmitContext ec)
1520                 {
1521                         base.Emit (ec);
1522
1523                         ec.Emit (OpCodes.Unbox_Any, type);
1524                 }
1525         }
1526
1527         /// <summary>
1528         ///   This is used to perform explicit numeric conversions.
1529         ///
1530         ///   Explicit numeric conversions might trigger exceptions in a checked
1531         ///   context, so they should generate the conv.ovf opcodes instead of
1532         ///   conv opcodes.
1533         /// </summary>
1534         public class ConvCast : TypeCast {
1535                 public enum Mode : byte {
1536                         I1_U1, I1_U2, I1_U4, I1_U8, I1_CH,
1537                         U1_I1, U1_CH,
1538                         I2_I1, I2_U1, I2_U2, I2_U4, I2_U8, I2_CH,
1539                         U2_I1, U2_U1, U2_I2, U2_CH,
1540                         I4_I1, I4_U1, I4_I2, I4_U2, I4_U4, I4_U8, I4_CH,
1541                         U4_I1, U4_U1, U4_I2, U4_U2, U4_I4, U4_CH,
1542                         I8_I1, I8_U1, I8_I2, I8_U2, I8_I4, I8_U4, I8_U8, I8_CH, I8_I,
1543                         U8_I1, U8_U1, U8_I2, U8_U2, U8_I4, U8_U4, U8_I8, U8_CH, U8_I,
1544                         CH_I1, CH_U1, CH_I2,
1545                         R4_I1, R4_U1, R4_I2, R4_U2, R4_I4, R4_U4, R4_I8, R4_U8, R4_CH,
1546                         R8_I1, R8_U1, R8_I2, R8_U2, R8_I4, R8_U4, R8_I8, R8_U8, R8_CH, R8_R4,
1547                         I_I8,
1548                 }
1549
1550                 Mode mode;
1551
1552                 public ConvCast (Expression child, TypeSpec return_type, Mode m)
1553                         : base (child, return_type)
1554                 {
1555                         mode = m;
1556                 }
1557
1558                 protected override Expression DoResolve (ResolveContext ec)
1559                 {
1560                         // This should never be invoked, we are born in fully
1561                         // initialized state.
1562
1563                         return this;
1564                 }
1565
1566                 public override string ToString ()
1567                 {
1568                         return String.Format ("ConvCast ({0}, {1})", mode, child);
1569                 }
1570
1571                 public override void Emit (EmitContext ec)
1572                 {
1573                         base.Emit (ec);
1574
1575                         if (ec.HasSet (EmitContext.Options.CheckedScope)) {
1576                                 switch (mode){
1577                                 case Mode.I1_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1578                                 case Mode.I1_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1579                                 case Mode.I1_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1580                                 case Mode.I1_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1581                                 case Mode.I1_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1582
1583                                 case Mode.U1_I1: ec.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1584                                 case Mode.U1_CH: /* nothing */ break;
1585
1586                                 case Mode.I2_I1: ec.Emit (OpCodes.Conv_Ovf_I1); break;
1587                                 case Mode.I2_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1588                                 case Mode.I2_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1589                                 case Mode.I2_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1590                                 case Mode.I2_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1591                                 case Mode.I2_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1592
1593                                 case Mode.U2_I1: ec.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1594                                 case Mode.U2_U1: ec.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1595                                 case Mode.U2_I2: ec.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1596                                 case Mode.U2_CH: /* nothing */ break;
1597
1598                                 case Mode.I4_I1: ec.Emit (OpCodes.Conv_Ovf_I1); break;
1599                                 case Mode.I4_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1600                                 case Mode.I4_I2: ec.Emit (OpCodes.Conv_Ovf_I2); break;
1601                                 case Mode.I4_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1602                                 case Mode.I4_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1603                                 case Mode.I4_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1604                                 case Mode.I4_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1605
1606                                 case Mode.U4_I1: ec.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1607                                 case Mode.U4_U1: ec.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1608                                 case Mode.U4_I2: ec.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1609                                 case Mode.U4_U2: ec.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1610                                 case Mode.U4_I4: ec.Emit (OpCodes.Conv_Ovf_I4_Un); break;
1611                                 case Mode.U4_CH: ec.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1612
1613                                 case Mode.I8_I1: ec.Emit (OpCodes.Conv_Ovf_I1); break;
1614                                 case Mode.I8_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1615                                 case Mode.I8_I2: ec.Emit (OpCodes.Conv_Ovf_I2); break;
1616                                 case Mode.I8_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1617                                 case Mode.I8_I4: ec.Emit (OpCodes.Conv_Ovf_I4); break;
1618                                 case Mode.I8_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1619                                 case Mode.I8_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1620                                 case Mode.I8_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1621                                 case Mode.I8_I: ec.Emit (OpCodes.Conv_Ovf_U); break;
1622
1623                                 case Mode.U8_I1: ec.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1624                                 case Mode.U8_U1: ec.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1625                                 case Mode.U8_I2: ec.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1626                                 case Mode.U8_U2: ec.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1627                                 case Mode.U8_I4: ec.Emit (OpCodes.Conv_Ovf_I4_Un); break;
1628                                 case Mode.U8_U4: ec.Emit (OpCodes.Conv_Ovf_U4_Un); break;
1629                                 case Mode.U8_I8: ec.Emit (OpCodes.Conv_Ovf_I8_Un); break;
1630                                 case Mode.U8_CH: ec.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1631                                 case Mode.U8_I: ec.Emit (OpCodes.Conv_Ovf_U_Un); break;
1632
1633                                 case Mode.CH_I1: ec.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1634                                 case Mode.CH_U1: ec.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1635                                 case Mode.CH_I2: ec.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1636
1637                                 case Mode.R4_I1: ec.Emit (OpCodes.Conv_Ovf_I1); break;
1638                                 case Mode.R4_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1639                                 case Mode.R4_I2: ec.Emit (OpCodes.Conv_Ovf_I2); break;
1640                                 case Mode.R4_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1641                                 case Mode.R4_I4: ec.Emit (OpCodes.Conv_Ovf_I4); break;
1642                                 case Mode.R4_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1643                                 case Mode.R4_I8: ec.Emit (OpCodes.Conv_Ovf_I8); break;
1644                                 case Mode.R4_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1645                                 case Mode.R4_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1646
1647                                 case Mode.R8_I1: ec.Emit (OpCodes.Conv_Ovf_I1); break;
1648                                 case Mode.R8_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1649                                 case Mode.R8_I2: ec.Emit (OpCodes.Conv_Ovf_I2); break;
1650                                 case Mode.R8_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1651                                 case Mode.R8_I4: ec.Emit (OpCodes.Conv_Ovf_I4); break;
1652                                 case Mode.R8_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1653                                 case Mode.R8_I8: ec.Emit (OpCodes.Conv_Ovf_I8); break;
1654                                 case Mode.R8_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1655                                 case Mode.R8_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1656                                 case Mode.R8_R4: ec.Emit (OpCodes.Conv_R4); break;
1657
1658                                 case Mode.I_I8: ec.Emit (OpCodes.Conv_Ovf_I8_Un); break;
1659                                 }
1660                         } else {
1661                                 switch (mode){
1662                                 case Mode.I1_U1: ec.Emit (OpCodes.Conv_U1); break;
1663                                 case Mode.I1_U2: ec.Emit (OpCodes.Conv_U2); break;
1664                                 case Mode.I1_U4: ec.Emit (OpCodes.Conv_U4); break;
1665                                 case Mode.I1_U8: ec.Emit (OpCodes.Conv_I8); break;
1666                                 case Mode.I1_CH: ec.Emit (OpCodes.Conv_U2); break;
1667
1668                                 case Mode.U1_I1: ec.Emit (OpCodes.Conv_I1); break;
1669                                 case Mode.U1_CH: ec.Emit (OpCodes.Conv_U2); break;
1670
1671                                 case Mode.I2_I1: ec.Emit (OpCodes.Conv_I1); break;
1672                                 case Mode.I2_U1: ec.Emit (OpCodes.Conv_U1); break;
1673                                 case Mode.I2_U2: ec.Emit (OpCodes.Conv_U2); break;
1674                                 case Mode.I2_U4: ec.Emit (OpCodes.Conv_U4); break;
1675                                 case Mode.I2_U8: ec.Emit (OpCodes.Conv_I8); break;
1676                                 case Mode.I2_CH: ec.Emit (OpCodes.Conv_U2); break;
1677
1678                                 case Mode.U2_I1: ec.Emit (OpCodes.Conv_I1); break;
1679                                 case Mode.U2_U1: ec.Emit (OpCodes.Conv_U1); break;
1680                                 case Mode.U2_I2: ec.Emit (OpCodes.Conv_I2); break;
1681                                 case Mode.U2_CH: /* nothing */ break;
1682
1683                                 case Mode.I4_I1: ec.Emit (OpCodes.Conv_I1); break;
1684                                 case Mode.I4_U1: ec.Emit (OpCodes.Conv_U1); break;
1685                                 case Mode.I4_I2: ec.Emit (OpCodes.Conv_I2); break;
1686                                 case Mode.I4_U4: /* nothing */ break;
1687                                 case Mode.I4_U2: ec.Emit (OpCodes.Conv_U2); break;
1688                                 case Mode.I4_U8: ec.Emit (OpCodes.Conv_I8); break;
1689                                 case Mode.I4_CH: ec.Emit (OpCodes.Conv_U2); break;
1690
1691                                 case Mode.U4_I1: ec.Emit (OpCodes.Conv_I1); break;
1692                                 case Mode.U4_U1: ec.Emit (OpCodes.Conv_U1); break;
1693                                 case Mode.U4_I2: ec.Emit (OpCodes.Conv_I2); break;
1694                                 case Mode.U4_U2: ec.Emit (OpCodes.Conv_U2); break;
1695                                 case Mode.U4_I4: /* nothing */ break;
1696                                 case Mode.U4_CH: ec.Emit (OpCodes.Conv_U2); break;
1697
1698                                 case Mode.I8_I1: ec.Emit (OpCodes.Conv_I1); break;
1699                                 case Mode.I8_U1: ec.Emit (OpCodes.Conv_U1); break;
1700                                 case Mode.I8_I2: ec.Emit (OpCodes.Conv_I2); break;
1701                                 case Mode.I8_U2: ec.Emit (OpCodes.Conv_U2); break;
1702                                 case Mode.I8_I4: ec.Emit (OpCodes.Conv_I4); break;
1703                                 case Mode.I8_U4: ec.Emit (OpCodes.Conv_U4); break;
1704                                 case Mode.I8_U8: /* nothing */ break;
1705                                 case Mode.I8_CH: ec.Emit (OpCodes.Conv_U2); break;
1706                                 case Mode.I8_I: ec.Emit (OpCodes.Conv_U); break;
1707
1708                                 case Mode.U8_I1: ec.Emit (OpCodes.Conv_I1); break;
1709                                 case Mode.U8_U1: ec.Emit (OpCodes.Conv_U1); break;
1710                                 case Mode.U8_I2: ec.Emit (OpCodes.Conv_I2); break;
1711                                 case Mode.U8_U2: ec.Emit (OpCodes.Conv_U2); break;
1712                                 case Mode.U8_I4: ec.Emit (OpCodes.Conv_I4); break;
1713                                 case Mode.U8_U4: ec.Emit (OpCodes.Conv_U4); break;
1714                                 case Mode.U8_I8: /* nothing */ break;
1715                                 case Mode.U8_CH: ec.Emit (OpCodes.Conv_U2); break;
1716                                 case Mode.U8_I: ec.Emit (OpCodes.Conv_U); break;
1717
1718                                 case Mode.CH_I1: ec.Emit (OpCodes.Conv_I1); break;
1719                                 case Mode.CH_U1: ec.Emit (OpCodes.Conv_U1); break;
1720                                 case Mode.CH_I2: ec.Emit (OpCodes.Conv_I2); break;
1721
1722                                 case Mode.R4_I1: ec.Emit (OpCodes.Conv_I1); break;
1723                                 case Mode.R4_U1: ec.Emit (OpCodes.Conv_U1); break;
1724                                 case Mode.R4_I2: ec.Emit (OpCodes.Conv_I2); break;
1725                                 case Mode.R4_U2: ec.Emit (OpCodes.Conv_U2); break;
1726                                 case Mode.R4_I4: ec.Emit (OpCodes.Conv_I4); break;
1727                                 case Mode.R4_U4: ec.Emit (OpCodes.Conv_U4); break;
1728                                 case Mode.R4_I8: ec.Emit (OpCodes.Conv_I8); break;
1729                                 case Mode.R4_U8: ec.Emit (OpCodes.Conv_U8); break;
1730                                 case Mode.R4_CH: ec.Emit (OpCodes.Conv_U2); break;
1731
1732                                 case Mode.R8_I1: ec.Emit (OpCodes.Conv_I1); break;
1733                                 case Mode.R8_U1: ec.Emit (OpCodes.Conv_U1); break;
1734                                 case Mode.R8_I2: ec.Emit (OpCodes.Conv_I2); break;
1735                                 case Mode.R8_U2: ec.Emit (OpCodes.Conv_U2); break;
1736                                 case Mode.R8_I4: ec.Emit (OpCodes.Conv_I4); break;
1737                                 case Mode.R8_U4: ec.Emit (OpCodes.Conv_U4); break;
1738                                 case Mode.R8_I8: ec.Emit (OpCodes.Conv_I8); break;
1739                                 case Mode.R8_U8: ec.Emit (OpCodes.Conv_U8); break;
1740                                 case Mode.R8_CH: ec.Emit (OpCodes.Conv_U2); break;
1741                                 case Mode.R8_R4: ec.Emit (OpCodes.Conv_R4); break;
1742
1743                                 case Mode.I_I8: ec.Emit (OpCodes.Conv_U8); break;
1744                                 }
1745                         }
1746                 }
1747         }
1748
1749         class OpcodeCast : TypeCast
1750         {
1751                 readonly OpCode op;
1752
1753                 public OpcodeCast (Expression child, TypeSpec return_type, OpCode op)
1754                         : base (child, return_type)
1755                 {
1756                         this.op = op;
1757                 }
1758
1759                 protected override Expression DoResolve (ResolveContext ec)
1760                 {
1761                         // This should never be invoked, we are born in fully
1762                         // initialized state.
1763
1764                         return this;
1765                 }
1766
1767                 public override void Emit (EmitContext ec)
1768                 {
1769                         base.Emit (ec);
1770                         ec.Emit (op);
1771                 }
1772
1773                 public TypeSpec UnderlyingType {
1774                         get { return child.Type; }
1775                 }
1776         }
1777
1778         //
1779         // Opcode casts expression with 2 opcodes but only
1780         // single expression tree node
1781         //
1782         class OpcodeCastDuplex : OpcodeCast
1783         {
1784                 readonly OpCode second;
1785
1786                 public OpcodeCastDuplex (Expression child, TypeSpec returnType, OpCode first, OpCode second)
1787                         : base (child, returnType, first)
1788                 {
1789                         this.second = second;
1790                 }
1791
1792                 public override void Emit (EmitContext ec)
1793                 {
1794                         base.Emit (ec);
1795                         ec.Emit (second);
1796                 }
1797         }
1798
1799         /// <summary>
1800         ///   This kind of cast is used to encapsulate a child and cast it
1801         ///   to the class requested
1802         /// </summary>
1803         public sealed class ClassCast : TypeCast {
1804                 readonly bool forced;
1805
1806                 public ClassCast (Expression child, TypeSpec return_type)
1807                         : base (child, return_type)
1808                 {
1809                 }
1810
1811                 public ClassCast (Expression child, TypeSpec return_type, bool forced)
1812                         : base (child, return_type)
1813                 {
1814                         this.forced = forced;
1815                 }
1816
1817                 public override void Emit (EmitContext ec)
1818                 {
1819                         base.Emit (ec);
1820
1821                         bool gen = TypeManager.IsGenericParameter (child.Type);
1822                         if (gen)
1823                                 ec.Emit (OpCodes.Box, child.Type);
1824
1825                         if (type.IsGenericParameter) {
1826                                 ec.Emit (OpCodes.Unbox_Any, type);
1827                                 return;
1828                         }
1829
1830                         if (gen && !forced)
1831                                 return;
1832
1833                         ec.Emit (OpCodes.Castclass, type);
1834                 }
1835         }
1836
1837         //
1838         // Created during resolving pahse when an expression is wrapped or constantified
1839         // and original expression can be used later (e.g. for expression trees)
1840         //
1841         public class ReducedExpression : Expression
1842         {
1843                 sealed class ReducedConstantExpression : EmptyConstantCast
1844                 {
1845                         readonly Expression orig_expr;
1846
1847                         public ReducedConstantExpression (Constant expr, Expression orig_expr)
1848                                 : base (expr, expr.Type)
1849                         {
1850                                 this.orig_expr = orig_expr;
1851                         }
1852
1853                         public override Constant ConvertImplicitly (TypeSpec target_type)
1854                         {
1855                                 Constant c = base.ConvertImplicitly (target_type);
1856                                 if (c != null)
1857                                         c = new ReducedConstantExpression (c, orig_expr);
1858
1859                                 return c;
1860                         }
1861
1862                         public override Expression CreateExpressionTree (ResolveContext ec)
1863                         {
1864                                 return orig_expr.CreateExpressionTree (ec);
1865                         }
1866
1867                         public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
1868                         {
1869                                 Constant c = base.ConvertExplicitly (in_checked_context, target_type);
1870                                 if (c != null)
1871                                         c = new ReducedConstantExpression (c, orig_expr);
1872                                 return c;
1873                         }
1874
1875                         public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
1876                         {
1877                                 //
1878                                 // LAMESPEC: Reduced conditional expression is allowed as an attribute argument
1879                                 //
1880                                 if (orig_expr is Conditional)
1881                                         child.EncodeAttributeValue (rc, enc, targetType);
1882                                 else
1883                                         base.EncodeAttributeValue (rc, enc, targetType);
1884                         }
1885                 }
1886
1887                 sealed class ReducedExpressionStatement : ExpressionStatement
1888                 {
1889                         readonly Expression orig_expr;
1890                         readonly ExpressionStatement stm;
1891
1892                         public ReducedExpressionStatement (ExpressionStatement stm, Expression orig)
1893                         {
1894                                 this.orig_expr = orig;
1895                                 this.stm = stm;
1896                                 this.eclass = stm.eclass;
1897                                 this.type = stm.Type;
1898
1899                                 this.loc = orig.Location;
1900                         }
1901
1902                         public override bool ContainsEmitWithAwait ()
1903                         {
1904                                 return stm.ContainsEmitWithAwait ();
1905                         }
1906
1907                         public override Expression CreateExpressionTree (ResolveContext ec)
1908                         {
1909                                 return orig_expr.CreateExpressionTree (ec);
1910                         }
1911
1912                         protected override Expression DoResolve (ResolveContext ec)
1913                         {
1914                                 return this;
1915                         }
1916
1917                         public override void Emit (EmitContext ec)
1918                         {
1919                                 stm.Emit (ec);
1920                         }
1921
1922                         public override void EmitStatement (EmitContext ec)
1923                         {
1924                                 stm.EmitStatement (ec);
1925                         }
1926                 }
1927
1928                 readonly Expression expr, orig_expr;
1929
1930                 private ReducedExpression (Expression expr, Expression orig_expr)
1931                 {
1932                         this.expr = expr;
1933                         this.eclass = expr.eclass;
1934                         this.type = expr.Type;
1935                         this.orig_expr = orig_expr;
1936                         this.loc = orig_expr.Location;
1937                 }
1938
1939                 #region Properties
1940
1941                 public override bool IsSideEffectFree {
1942                         get {
1943                                 return expr.IsSideEffectFree;
1944                         }
1945                 }
1946
1947                 public Expression OriginalExpression {
1948                         get {
1949                                 return orig_expr;
1950                         }
1951                 }
1952
1953                 #endregion
1954
1955                 public override bool ContainsEmitWithAwait ()
1956                 {
1957                         return expr.ContainsEmitWithAwait ();
1958                 }
1959
1960                 //
1961                 // Creates fully resolved expression switcher
1962                 //
1963                 public static Constant Create (Constant expr, Expression original_expr)
1964                 {
1965                         if (expr.eclass == ExprClass.Unresolved)
1966                                 throw new ArgumentException ("Unresolved expression");
1967
1968                         return new ReducedConstantExpression (expr, original_expr);
1969                 }
1970
1971                 public static ExpressionStatement Create (ExpressionStatement s, Expression orig)
1972                 {
1973                         return new ReducedExpressionStatement (s, orig);
1974                 }
1975
1976                 public static Expression Create (Expression expr, Expression original_expr)
1977                 {
1978                         return Create (expr, original_expr, true);
1979                 }
1980
1981                 //
1982                 // Creates unresolved reduce expression. The original expression has to be
1983                 // already resolved. Created expression is constant based based on `expr'
1984                 // value unless canBeConstant is used
1985                 //
1986                 public static Expression Create (Expression expr, Expression original_expr, bool canBeConstant)
1987                 {
1988                         if (canBeConstant) {
1989                                 Constant c = expr as Constant;
1990                                 if (c != null)
1991                                         return Create (c, original_expr);
1992                         }
1993
1994                         ExpressionStatement s = expr as ExpressionStatement;
1995                         if (s != null)
1996                                 return Create (s, original_expr);
1997
1998                         if (expr.eclass == ExprClass.Unresolved)
1999                                 throw new ArgumentException ("Unresolved expression");
2000
2001                         return new ReducedExpression (expr, original_expr);
2002                 }
2003
2004                 public override Expression CreateExpressionTree (ResolveContext ec)
2005                 {
2006                         return orig_expr.CreateExpressionTree (ec);
2007                 }
2008
2009                 protected override Expression DoResolve (ResolveContext ec)
2010                 {
2011                         return this;
2012                 }
2013
2014                 public override void Emit (EmitContext ec)
2015                 {
2016                         expr.Emit (ec);
2017                 }
2018
2019                 public override Expression EmitToField (EmitContext ec)
2020                 {
2021                         return expr.EmitToField(ec);
2022                 }
2023
2024                 public override void EmitBranchable (EmitContext ec, Label target, bool on_true)
2025                 {
2026                         expr.EmitBranchable (ec, target, on_true);
2027                 }
2028
2029                 public override SLE.Expression MakeExpression (BuilderContext ctx)
2030                 {
2031                         return orig_expr.MakeExpression (ctx);
2032                 }
2033         }
2034
2035         //
2036         // Standard composite pattern
2037         //
2038         public abstract class CompositeExpression : Expression
2039         {
2040                 protected Expression expr;
2041
2042                 protected CompositeExpression (Expression expr)
2043                 {
2044                         this.expr = expr;
2045                         this.loc = expr.Location;
2046                 }
2047
2048                 public override bool ContainsEmitWithAwait ()
2049                 {
2050                         return expr.ContainsEmitWithAwait ();
2051                 }
2052
2053                 public override Expression CreateExpressionTree (ResolveContext rc)
2054                 {
2055                         return expr.CreateExpressionTree (rc);
2056                 }
2057
2058                 public Expression Child {
2059                         get { return expr; }
2060                 }
2061
2062                 protected override Expression DoResolve (ResolveContext rc)
2063                 {
2064                         expr = expr.Resolve (rc);
2065                         if (expr != null) {
2066                                 type = expr.Type;
2067                                 eclass = expr.eclass;
2068                         }
2069
2070                         return this;
2071                 }
2072
2073                 public override void Emit (EmitContext ec)
2074                 {
2075                         expr.Emit (ec);
2076                 }
2077
2078                 public override bool IsNull {
2079                         get { return expr.IsNull; }
2080                 }
2081         }
2082
2083         //
2084         // Base of expressions used only to narrow resolve flow
2085         //
2086         public abstract class ShimExpression : Expression
2087         {
2088                 protected Expression expr;
2089
2090                 protected ShimExpression (Expression expr)
2091                 {
2092                         this.expr = expr;
2093                 }
2094
2095                 public Expression Expr {
2096                         get {
2097                                 return expr;
2098                         }
2099                 }
2100
2101                 protected override void CloneTo (CloneContext clonectx, Expression t)
2102                 {
2103                         if (expr == null)
2104                                 return;
2105
2106                         ShimExpression target = (ShimExpression) t;
2107                         target.expr = expr.Clone (clonectx);
2108                 }
2109
2110                 public override bool ContainsEmitWithAwait ()
2111                 {
2112                         return expr.ContainsEmitWithAwait ();
2113                 }
2114
2115                 public override Expression CreateExpressionTree (ResolveContext ec)
2116                 {
2117                         throw new NotSupportedException ("ET");
2118                 }
2119
2120                 public override void Emit (EmitContext ec)
2121                 {
2122                         throw new InternalErrorException ("Missing Resolve call");
2123                 }
2124
2125         }
2126
2127         //
2128         // Unresolved type name expressions
2129         //
2130         public abstract class ATypeNameExpression : FullNamedExpression
2131         {
2132                 string name;
2133                 protected TypeArguments targs;
2134
2135                 protected ATypeNameExpression (string name, Location l)
2136                 {
2137                         this.name = name;
2138                         loc = l;
2139                 }
2140
2141                 protected ATypeNameExpression (string name, TypeArguments targs, Location l)
2142                 {
2143                         this.name = name;
2144                         this.targs = targs;
2145                         loc = l;
2146                 }
2147
2148                 protected ATypeNameExpression (string name, int arity, Location l)
2149                         : this (name, new UnboundTypeArguments (arity), l)
2150                 {
2151                 }
2152
2153                 #region Properties
2154
2155                 protected int Arity {
2156                         get {
2157                                 return targs == null ? 0 : targs.Count;
2158                         }
2159                 }
2160
2161                 public bool HasTypeArguments {
2162                         get {
2163                                 return targs != null && !targs.IsEmpty;
2164                         }
2165                 }
2166
2167                 public string Name {
2168                         get {
2169                                 return name;
2170                         }
2171                         set {
2172                                 name = value;
2173                         }
2174                 }
2175
2176                 public TypeArguments TypeArguments {
2177                         get {
2178                                 return targs;
2179                         }
2180                 }
2181
2182                 #endregion
2183
2184                 public override bool Equals (object obj)
2185                 {
2186                         ATypeNameExpression atne = obj as ATypeNameExpression;
2187                         return atne != null && atne.Name == Name &&
2188                                 (targs == null || targs.Equals (atne.targs));
2189                 }
2190
2191                 public override int GetHashCode ()
2192                 {
2193                         return Name.GetHashCode ();
2194                 }
2195
2196                 // TODO: Move it to MemberCore
2197                 public static string GetMemberType (MemberCore mc)
2198                 {
2199                         if (mc is Property)
2200                                 return "property";
2201                         if (mc is Indexer)
2202                                 return "indexer";
2203                         if (mc is FieldBase)
2204                                 return "field";
2205                         if (mc is MethodCore)
2206                                 return "method";
2207                         if (mc is EnumMember)
2208                                 return "enum";
2209                         if (mc is Event)
2210                                 return "event";
2211
2212                         return "type";
2213                 }
2214
2215                 public override string GetSignatureForError ()
2216                 {
2217                         if (targs != null) {
2218                                 return Name + "<" + targs.GetSignatureForError () + ">";
2219                         }
2220
2221                         return Name;
2222                 }
2223
2224                 public abstract Expression LookupNameExpression (ResolveContext rc, MemberLookupRestrictions restriction);
2225         }
2226
2227         /// <summary>
2228         ///   SimpleName expressions are formed of a single word and only happen at the beginning
2229         ///   of a dotted-name.
2230         /// </summary>
2231         public class SimpleName : ATypeNameExpression
2232         {
2233                 public SimpleName (string name, Location l)
2234                         : base (name, l)
2235                 {
2236                 }
2237
2238                 public SimpleName (string name, TypeArguments args, Location l)
2239                         : base (name, args, l)
2240                 {
2241                 }
2242
2243                 public SimpleName (string name, int arity, Location l)
2244                         : base (name, arity, l)
2245                 {
2246                 }
2247
2248                 public SimpleName GetMethodGroup ()
2249                 {
2250                         return new SimpleName (Name, targs, loc);
2251                 }
2252
2253                 protected override Expression DoResolve (ResolveContext rc)
2254                 {
2255                         var e = SimpleNameResolve (rc, null, false);
2256
2257                         var fe = e as FieldExpr;
2258                         if (fe != null) {
2259                                 fe.VerifyAssignedStructField (rc, null);
2260                         }
2261
2262                         return e;
2263                 }
2264
2265                 public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
2266                 {
2267                         return SimpleNameResolve (ec, right_side, false);
2268                 }
2269
2270                 protected virtual void Error_TypeOrNamespaceNotFound (IMemberContext ctx)
2271                 {
2272                         if (ctx.CurrentType != null) {
2273                                 var member = MemberLookup (ctx, false, ctx.CurrentType, Name, 0, MemberLookupRestrictions.ExactArity, loc) as MemberExpr;
2274                                 if (member != null) {
2275                                         member.Error_UnexpectedKind (ctx, member, "type", member.KindName, loc);
2276                                         return;
2277                                 }
2278                         }
2279
2280                         var retval = ctx.LookupNamespaceOrType (Name, Arity, LookupMode.IgnoreAccessibility, loc);
2281                         if (retval != null) {
2282                                 ctx.Module.Compiler.Report.SymbolRelatedToPreviousError (retval.Type);
2283                                 ErrorIsInaccesible (ctx, retval.GetSignatureForError (), loc);
2284                                 return;
2285                         }
2286
2287                         retval = ctx.LookupNamespaceOrType (Name, -System.Math.Max (1, Arity), LookupMode.Probing, loc);
2288                         if (retval != null) {
2289                                 Error_TypeArgumentsCannotBeUsed (ctx, retval.Type, Arity, loc);
2290                                 return;
2291                         }
2292
2293                         NamespaceContainer.Error_NamespaceNotFound (loc, Name, ctx.Module.Compiler.Report);
2294                 }
2295
2296                 public override FullNamedExpression ResolveAsTypeOrNamespace (IMemberContext ec)
2297                 {
2298                         FullNamedExpression fne = ec.LookupNamespaceOrType (Name, Arity, LookupMode.Normal, loc);
2299
2300                         if (fne != null) {
2301                                 if (fne.Type != null && Arity > 0) {
2302                                         if (HasTypeArguments) {
2303                                                 GenericTypeExpr ct = new GenericTypeExpr (fne.Type, targs, loc);
2304                                                 if (ct.ResolveAsType (ec) == null)
2305                                                         return null;
2306
2307                                                 return ct;
2308                                         }
2309
2310                                         return new GenericOpenTypeExpr (fne.Type, loc);
2311                                 }
2312
2313                                 //
2314                                 // dynamic namespace is ignored when dynamic is allowed (does not apply to types)
2315                                 //
2316                                 if (!(fne is Namespace))
2317                                         return fne;
2318                         }
2319
2320                         if (Arity == 0 && Name == "dynamic" && ec.Module.Compiler.Settings.Version > LanguageVersion.V_3) {
2321                                 if (!ec.Module.PredefinedAttributes.Dynamic.IsDefined) {
2322                                         ec.Module.Compiler.Report.Error (1980, Location,
2323                                                 "Dynamic keyword requires `{0}' to be defined. Are you missing System.Core.dll assembly reference?",
2324                                                 ec.Module.PredefinedAttributes.Dynamic.GetSignatureForError ());
2325                                 }
2326
2327                                 fne = new DynamicTypeExpr (loc);
2328                                 fne.ResolveAsType (ec);
2329                         }
2330
2331                         if (fne != null)
2332                                 return fne;
2333
2334                         Error_TypeOrNamespaceNotFound (ec);
2335                         return null;
2336                 }
2337
2338                 public bool IsPossibleTypeOrNamespace (IMemberContext mc)
2339                 {
2340                         return mc.LookupNamespaceOrType (Name, Arity, LookupMode.Probing, loc) != null;
2341                 }
2342
2343                 public override Expression LookupNameExpression (ResolveContext rc, MemberLookupRestrictions restrictions)
2344                 {
2345                         int lookup_arity = Arity;
2346                         bool errorMode = false;
2347                         Expression e;
2348                         Block current_block = rc.CurrentBlock;
2349                         INamedBlockVariable variable = null;
2350                         bool variable_found = false;
2351
2352                         while (true) {
2353                                 //
2354                                 // Stage 1: binding to local variables or parameters
2355                                 //
2356                                 // LAMESPEC: It should take invocableOnly into account but that would break csc compatibility
2357                                 //
2358                                 if (current_block != null && lookup_arity == 0) {
2359                                         if (current_block.ParametersBlock.TopBlock.GetLocalName (Name, current_block.Original, ref variable)) {
2360                                                 if (!variable.IsDeclared) {
2361                                                         // We found local name in accessible block but it's not
2362                                                         // initialized yet, maybe the user wanted to bind to something else
2363                                                         errorMode = true;
2364                                                         variable_found = true;
2365                                                 } else {
2366                                                         e = variable.CreateReferenceExpression (rc, loc);
2367                                                         if (e != null) {
2368                                                                 if (Arity > 0)
2369                                                                         Error_TypeArgumentsCannotBeUsed (rc, "variable", Name, loc);
2370
2371                                                                 return e;
2372                                                         }
2373                                                 }
2374                                         }
2375                                 }
2376
2377                                 //
2378                                 // Stage 2: Lookup members if we are inside a type up to top level type for nested types
2379                                 //
2380                                 TypeSpec member_type = rc.CurrentType;
2381                                 for (; member_type != null; member_type = member_type.DeclaringType) {
2382                                         e = MemberLookup (rc, errorMode, member_type, Name, lookup_arity, restrictions, loc);
2383                                         if (e == null)
2384                                                 continue;
2385
2386                                         var me = e as MemberExpr;
2387                                         if (me == null) {
2388                                                 // The name matches a type, defer to ResolveAsTypeStep
2389                                                 if (e is TypeExpr)
2390                                                         break;
2391
2392                                                 continue;
2393                                         }
2394
2395                                         if (errorMode) {
2396                                                 if (variable != null) {
2397                                                         if (me is FieldExpr || me is ConstantExpr || me is EventExpr || me is PropertyExpr) {
2398                                                                 rc.Report.Error (844, loc,
2399                                                                         "A local variable `{0}' cannot be used before it is declared. Consider renaming the local variable when it hides the member `{1}'",
2400                                                                         Name, me.GetSignatureForError ());
2401                                                         } else {
2402                                                                 break;
2403                                                         }
2404                                                 } else if (me is MethodGroupExpr) {
2405                                                         // Leave it to overload resolution to report correct error
2406                                                 } else {
2407                                                         // TODO: rc.Report.SymbolRelatedToPreviousError ()
2408                                                         ErrorIsInaccesible (rc, me.GetSignatureForError (), loc);
2409                                                 }
2410                                         } else {
2411                                                 // LAMESPEC: again, ignores InvocableOnly
2412                                                 if (variable != null) {
2413                                                         rc.Report.SymbolRelatedToPreviousError (variable.Location, Name);
2414                                                         rc.Report.Error (135, loc, "`{0}' conflicts with a declaration in a child block", Name);
2415                                                 }
2416
2417                                                 //
2418                                                 // MemberLookup does not check accessors availability, this is actually needed for properties only
2419                                                 //
2420                                                 var pe = me as PropertyExpr;
2421                                                 if (pe != null) {
2422
2423                                                         // Break as there is no other overload available anyway
2424                                                         if ((restrictions & MemberLookupRestrictions.ReadAccess) != 0) {
2425                                                                 if (!pe.PropertyInfo.HasGet || !pe.PropertyInfo.Get.IsAccessible (rc))
2426                                                                         break;
2427
2428                                                                 pe.Getter = pe.PropertyInfo.Get;
2429                                                         } else {
2430                                                                 if (!pe.PropertyInfo.HasSet || !pe.PropertyInfo.Set.IsAccessible (rc))
2431                                                                         break;
2432
2433                                                                 pe.Setter = pe.PropertyInfo.Set;
2434                                                         }
2435                                                 }
2436                                         }
2437
2438                                         // TODO: It's used by EventExpr -> FieldExpr transformation only
2439                                         // TODO: Should go to MemberAccess
2440                                         me = me.ResolveMemberAccess (rc, null, null);
2441
2442                                         if (Arity > 0) {
2443                                                 targs.Resolve (rc);
2444                                                 me.SetTypeArguments (rc, targs);
2445                                         }
2446
2447                                         return me;
2448                                 }
2449
2450                                 //
2451                                 // Stage 3: Lookup nested types, namespaces and type parameters in the context
2452                                 //
2453                                 if ((restrictions & MemberLookupRestrictions.InvocableOnly) == 0 && !variable_found) {
2454                                         if (IsPossibleTypeOrNamespace (rc)) {
2455                                                 if (variable != null) {
2456                                                         rc.Report.SymbolRelatedToPreviousError (variable.Location, Name);
2457                                                         rc.Report.Error (135, loc, "`{0}' conflicts with a declaration in a child block", Name);
2458                                                 }
2459
2460                                                 return ResolveAsTypeOrNamespace (rc);
2461                                         }
2462                                 }
2463
2464                                 if (errorMode) {
2465                                         if (variable_found) {
2466                                                 rc.Report.Error (841, loc, "A local variable `{0}' cannot be used before it is declared", Name);
2467                                         } else {
2468                                                 if (Arity > 0) {
2469                                                         var tparams = rc.CurrentTypeParameters;
2470                                                         if (tparams != null) {
2471                                                                 if (tparams.Find (Name) != null) {
2472                                                                         Error_TypeArgumentsCannotBeUsed (rc, "type parameter", Name, loc);
2473                                                                         return null;
2474                                                                 }
2475                                                         }
2476
2477                                                         var ct = rc.CurrentType;
2478                                                         do {
2479                                                                 if (ct.MemberDefinition.TypeParametersCount > 0) {
2480                                                                         foreach (var ctp in ct.MemberDefinition.TypeParameters) {
2481                                                                                 if (ctp.Name == Name) {
2482                                                                                         Error_TypeArgumentsCannotBeUsed (rc, "type parameter", Name, loc);
2483                                                                                         return null;
2484                                                                                 }
2485                                                                         }
2486                                                                 }
2487
2488                                                                 ct = ct.DeclaringType;
2489                                                         } while (ct != null);
2490                                                 }
2491
2492                                                 if ((restrictions & MemberLookupRestrictions.InvocableOnly) == 0) {
2493                                                         e = rc.LookupNamespaceOrType (Name, Arity, LookupMode.IgnoreAccessibility, loc);
2494                                                         if (e != null) {
2495                                                                 rc.Report.SymbolRelatedToPreviousError (e.Type);
2496                                                                 ErrorIsInaccesible (rc, e.GetSignatureForError (), loc);
2497                                                                 return e;
2498                                                         }
2499                                                 }
2500
2501                                                 e = rc.LookupNamespaceOrType (Name, -System.Math.Max (1, Arity), LookupMode.Probing, loc);
2502                                                 if (e != null) {
2503                                                         if (e.Type.Arity != Arity) {
2504                                                                 Error_TypeArgumentsCannotBeUsed (rc, e.Type, Arity, loc);
2505                                                                 return e;
2506                                                         }
2507
2508                                                         if (e is TypeExpr) {
2509                                                                 e.Error_UnexpectedKind (rc, e, "variable", e.ExprClassName, loc);
2510                                                                 return e;
2511                                                         }
2512                                                 }
2513
2514                                                 rc.Report.Error (103, loc, "The name `{0}' does not exist in the current context", Name);
2515                                         }
2516
2517                                         return ErrorExpression.Instance;
2518                                 }
2519
2520                                 if (rc.Module.Evaluator != null) {
2521                                         var fi = rc.Module.Evaluator.LookupField (Name);
2522                                         if (fi != null)
2523                                                 return new FieldExpr (fi.Item1, loc);
2524                                 }
2525
2526                                 lookup_arity = 0;
2527                                 errorMode = true;
2528                         }
2529                 }
2530
2531                 Expression SimpleNameResolve (ResolveContext ec, Expression right_side, bool intermediate)
2532                 {
2533                         Expression e = LookupNameExpression (ec, right_side == null ? MemberLookupRestrictions.ReadAccess : MemberLookupRestrictions.None);
2534
2535                         if (e == null)
2536                                 return null;
2537
2538                         if (right_side != null) {
2539                                 if (e is FullNamedExpression && e.eclass != ExprClass.Unresolved) {
2540                                         e.Error_UnexpectedKind (ec, e, "variable", e.ExprClassName, loc);
2541                                     return null;
2542                                 }
2543
2544                                 e = e.ResolveLValue (ec, right_side);
2545                         } else {
2546                                 e = e.Resolve (ec);
2547                         }
2548
2549                         return e;
2550                 }
2551
2552                 public override object Accept (StructuralVisitor visitor)
2553                 {
2554                         return visitor.Visit (this);
2555                 }
2556         }
2557
2558         /// <summary>
2559         ///   Represents a namespace or a type.  The name of the class was inspired by
2560         ///   section 10.8.1 (Fully Qualified Names).
2561         /// </summary>
2562         public abstract class FullNamedExpression : Expression
2563         {
2564                 protected override void CloneTo (CloneContext clonectx, Expression target)
2565                 {
2566                         // Do nothing, most unresolved type expressions cannot be
2567                         // resolved to different type
2568                 }
2569
2570                 public override bool ContainsEmitWithAwait ()
2571                 {
2572                         return false;
2573                 }
2574
2575                 public override Expression CreateExpressionTree (ResolveContext ec)
2576                 {
2577                         throw new NotSupportedException ("ET");
2578                 }
2579
2580                 public abstract FullNamedExpression ResolveAsTypeOrNamespace (IMemberContext mc);
2581
2582                 //
2583                 // This is used to resolve the expression as a type, a null
2584                 // value will be returned if the expression is not a type
2585                 // reference
2586                 //
2587                 public override TypeSpec ResolveAsType (IMemberContext mc)
2588                 {
2589                         FullNamedExpression fne = ResolveAsTypeOrNamespace (mc);
2590
2591                         if (fne == null)
2592                                 return null;
2593
2594                         TypeExpr te = fne as TypeExpr;
2595                         if (te == null) {
2596                                 fne.Error_UnexpectedKind (mc, fne, "type", fne.ExprClassName, loc);
2597                                 return null;
2598                         }
2599
2600                         te.loc = loc;
2601
2602                         type = te.Type;
2603
2604                         var dep = type.GetMissingDependencies ();
2605                         if (dep != null) {
2606                                 ImportedTypeDefinition.Error_MissingDependency (mc, dep, loc);
2607                         }
2608
2609                         if (type.Kind == MemberKind.Void) {
2610                                 mc.Module.Compiler.Report.Error (673, loc, "System.Void cannot be used from C#. Consider using `void'");
2611                         }
2612
2613                         //
2614                         // Obsolete checks cannot be done when resolving base context as they
2615                         // require type dependencies to be set but we are in process of resolving them
2616                         //
2617                         if (!(mc is TypeDefinition.BaseContext) && !(mc is UsingAliasNamespace.AliasContext)) {
2618                                 ObsoleteAttribute obsolete_attr = type.GetAttributeObsolete ();
2619                                 if (obsolete_attr != null && !mc.IsObsolete) {
2620                                         AttributeTester.Report_ObsoleteMessage (obsolete_attr, te.GetSignatureForError (), Location, mc.Module.Compiler.Report);
2621                                 }
2622                         }
2623
2624                         return type;
2625                 }
2626
2627
2628                 public override void Emit (EmitContext ec)
2629                 {
2630                         throw new InternalErrorException ("FullNamedExpression `{0}' found in resolved tree",
2631                                 GetSignatureForError ());
2632                 }
2633         }
2634
2635         /// <summary>
2636         ///   Expression that evaluates to a type
2637         /// </summary>
2638         public abstract class TypeExpr : FullNamedExpression
2639         {
2640                 public sealed override FullNamedExpression ResolveAsTypeOrNamespace (IMemberContext mc)
2641                 {
2642                         ResolveAsType (mc);
2643                         return this;
2644                 }
2645
2646                 protected sealed override Expression DoResolve (ResolveContext ec)
2647                 {
2648                         ResolveAsType (ec);
2649                         return this;
2650                 }
2651
2652                 public override bool Equals (object obj)
2653                 {
2654                         TypeExpr tobj = obj as TypeExpr;
2655                         if (tobj == null)
2656                                 return false;
2657
2658                         return Type == tobj.Type;
2659                 }
2660
2661                 public override int GetHashCode ()
2662                 {
2663                         return Type.GetHashCode ();
2664                 }
2665         }
2666
2667         /// <summary>
2668         ///   Fully resolved Expression that already evaluated to a type
2669         /// </summary>
2670         public class TypeExpression : TypeExpr
2671         {
2672                 public TypeExpression (TypeSpec t, Location l)
2673                 {
2674                         Type = t;
2675                         eclass = ExprClass.Type;
2676                         loc = l;
2677                 }
2678
2679                 public sealed override TypeSpec ResolveAsType (IMemberContext ec)
2680                 {
2681                         return type;
2682                 }
2683         }
2684
2685         /// <summary>
2686         ///   This class denotes an expression which evaluates to a member
2687         ///   of a struct or a class.
2688         /// </summary>
2689         public abstract class MemberExpr : Expression, OverloadResolver.IInstanceQualifier
2690         {
2691                 //
2692                 // An instance expression associated with this member, if it's a
2693                 // non-static member
2694                 //
2695                 public Expression InstanceExpression;
2696
2697                 /// <summary>
2698                 ///   The name of this member.
2699                 /// </summary>
2700                 public abstract string Name {
2701                         get;
2702                 }
2703
2704                 //
2705                 // When base.member is used
2706                 //
2707                 public bool IsBase {
2708                         get { return InstanceExpression is BaseThis; }
2709                 }
2710
2711                 /// <summary>
2712                 ///   Whether this is an instance member.
2713                 /// </summary>
2714                 public abstract bool IsInstance {
2715                         get;
2716                 }
2717
2718                 /// <summary>
2719                 ///   Whether this is a static member.
2720                 /// </summary>
2721                 public abstract bool IsStatic {
2722                         get;
2723                 }
2724
2725                 public abstract string KindName {
2726                         get;
2727                 }
2728
2729                 protected abstract TypeSpec DeclaringType {
2730                         get;
2731                 }
2732
2733                 TypeSpec OverloadResolver.IInstanceQualifier.InstanceType {
2734                         get {
2735                                 return InstanceExpression.Type;
2736                         }
2737                 }
2738
2739                 //
2740                 // Converts best base candidate for virtual method starting from QueriedBaseType
2741                 //
2742                 protected MethodSpec CandidateToBaseOverride (ResolveContext rc, MethodSpec method)
2743                 {
2744                         //
2745                         // Only when base.member is used and method is virtual
2746                         //
2747                         if (!IsBase)
2748                                 return method;
2749
2750                         //
2751                         // Overload resulution works on virtual or non-virtual members only (no overrides). That
2752                         // means for base.member access we have to find the closest match after we found best candidate
2753                         //
2754                         if ((method.Modifiers & (Modifiers.ABSTRACT | Modifiers.VIRTUAL | Modifiers.OVERRIDE)) != 0) {
2755                                 //
2756                                 // The method could already be what we are looking for
2757                                 //
2758                                 TypeSpec[] targs = null;
2759                                 if (method.DeclaringType != InstanceExpression.Type) {
2760                                         var base_override = MemberCache.FindMember (InstanceExpression.Type, new MemberFilter (method), BindingRestriction.InstanceOnly) as MethodSpec;
2761                                         if (base_override != null && base_override.DeclaringType != method.DeclaringType) {
2762                                                 if (base_override.IsGeneric)
2763                                                         targs = method.TypeArguments;
2764
2765                                                 method = base_override;
2766                                         }
2767                                 }
2768
2769                                 // TODO: For now we do it for any hoisted call even if it's needed for
2770                                 // hoisted stories only but that requires a new expression wrapper
2771                                 if (rc.CurrentAnonymousMethod != null) {
2772                                         if (targs == null && method.IsGeneric) {
2773                                                 targs = method.TypeArguments;
2774                                                 method = method.GetGenericMethodDefinition ();
2775                                         }
2776
2777                                         if (method.Parameters.HasArglist)
2778                                                 throw new NotImplementedException ("__arglist base call proxy");
2779
2780                                         method = rc.CurrentMemberDefinition.Parent.PartialContainer.CreateHoistedBaseCallProxy (rc, method);
2781
2782                                         // Ideally this should apply to any proxy rewrite but in the case of unary mutators on
2783                                         // get/set member expressions second call would fail to proxy because left expression
2784                                         // would be of 'this' and not 'base'
2785                                         if (rc.CurrentType.IsStruct)
2786                                                 InstanceExpression = new This (loc).Resolve (rc);
2787                                 }
2788
2789                                 if (targs != null)
2790                                         method = method.MakeGenericMethod (rc, targs);
2791                         }
2792
2793                         //
2794                         // Only base will allow this invocation to happen.
2795                         //
2796                         if (method.IsAbstract) {
2797                                 Error_CannotCallAbstractBase (rc, method.GetSignatureForError ());
2798                         }
2799
2800                         return method;
2801                 }
2802
2803                 protected void CheckProtectedMemberAccess (ResolveContext rc, MemberSpec member)
2804                 {
2805                         if (InstanceExpression == null)
2806                                 return;
2807
2808                         if ((member.Modifiers & Modifiers.PROTECTED) != 0 && !(InstanceExpression is This)) {
2809                                 if (!CheckProtectedMemberAccess (rc, member, InstanceExpression.Type)) {
2810                                         Error_ProtectedMemberAccess (rc, member, InstanceExpression.Type, loc);
2811                                 }
2812                         }
2813                 }
2814
2815                 bool OverloadResolver.IInstanceQualifier.CheckProtectedMemberAccess (ResolveContext rc, MemberSpec member)
2816                 {
2817                         if (InstanceExpression == null)
2818                                 return true;
2819
2820                         return InstanceExpression is This || CheckProtectedMemberAccess (rc, member, InstanceExpression.Type);
2821                 }
2822
2823                 public static bool CheckProtectedMemberAccess<T> (ResolveContext rc, T member, TypeSpec qualifier) where T : MemberSpec
2824                 {
2825                         var ct = rc.CurrentType;
2826                         if (ct == qualifier)
2827                                 return true;
2828
2829                         if ((member.Modifiers & Modifiers.INTERNAL) != 0 && member.DeclaringType.MemberDefinition.IsInternalAsPublic (ct.MemberDefinition.DeclaringAssembly))
2830                                 return true;
2831
2832                         qualifier = qualifier.GetDefinition ();
2833                         if (ct != qualifier && !IsSameOrBaseQualifier (ct, qualifier)) {
2834                                 return false;
2835                         }
2836
2837                         return true;
2838                 }
2839
2840                 public override bool ContainsEmitWithAwait ()
2841                 {
2842                         return InstanceExpression != null && InstanceExpression.ContainsEmitWithAwait ();
2843                 }
2844
2845                 static bool IsSameOrBaseQualifier (TypeSpec type, TypeSpec qtype)
2846                 {
2847                         do {
2848                                 type = type.GetDefinition ();
2849
2850                                 if (type == qtype || TypeManager.IsFamilyAccessible (qtype, type))
2851                                         return true;
2852
2853                                 type = type.DeclaringType;
2854                         } while (type != null);
2855
2856                         return false;
2857                 }
2858
2859                 protected void DoBestMemberChecks<T> (ResolveContext rc, T member) where T : MemberSpec, IInterfaceMemberSpec
2860                 {
2861                         if (InstanceExpression != null) {
2862                                 InstanceExpression = InstanceExpression.Resolve (rc);
2863                                 CheckProtectedMemberAccess (rc, member);
2864                         }
2865
2866                         if (member.MemberType.IsPointer && !rc.IsUnsafe) {
2867                                 UnsafeError (rc, loc);
2868                         }
2869
2870                         var dep = member.GetMissingDependencies ();
2871                         if (dep != null) {
2872                                 ImportedTypeDefinition.Error_MissingDependency (rc, dep, loc);
2873                         }
2874
2875                         if (!rc.IsObsolete) {
2876                                 ObsoleteAttribute oa = member.GetAttributeObsolete ();
2877                                 if (oa != null)
2878                                         AttributeTester.Report_ObsoleteMessage (oa, member.GetSignatureForError (), loc, rc.Report);
2879                         }
2880
2881                         if (!(member is FieldSpec))
2882                                 member.MemberDefinition.SetIsUsed ();
2883                 }
2884
2885                 protected virtual void Error_CannotCallAbstractBase (ResolveContext rc, string name)
2886                 {
2887                         rc.Report.Error (205, loc, "Cannot call an abstract base member `{0}'", name);
2888                 }
2889
2890                 public static void Error_ProtectedMemberAccess (ResolveContext rc, MemberSpec member, TypeSpec qualifier, Location loc)
2891                 {
2892                         rc.Report.SymbolRelatedToPreviousError (member);
2893                         rc.Report.Error (1540, loc,
2894                                 "Cannot access protected member `{0}' via a qualifier of type `{1}'. The qualifier must be of type `{2}' or derived from it",
2895                                 member.GetSignatureForError (), qualifier.GetSignatureForError (), rc.CurrentType.GetSignatureForError ());
2896                 }
2897
2898                 //
2899                 // Implements identicial simple name and type-name
2900                 //
2901                 public Expression ProbeIdenticalTypeName (ResolveContext rc, Expression left, SimpleName name)
2902                 {
2903                         var t = left.Type;
2904                         if (t.Kind == MemberKind.InternalCompilerType || t is ElementTypeSpec || t.Arity > 0)
2905                                 return left;
2906
2907                         // In a member access of the form E.I, if E is a single identifier, and if the meaning of E as a simple-name is
2908                         // a constant, field, property, local variable, or parameter with the same type as the meaning of E as a type-name
2909
2910                         if (left is MemberExpr || left is VariableReference) {
2911                                 var identical_type = rc.LookupNamespaceOrType (name.Name, 0, LookupMode.Probing, loc) as TypeExpr;
2912                                 if (identical_type != null && identical_type.Type == left.Type)
2913                                         return identical_type;
2914                         }
2915
2916                         return left;
2917                 }
2918
2919                 public bool ResolveInstanceExpression (ResolveContext rc, Expression rhs)
2920                 {
2921                         if (IsStatic) {
2922                                 if (InstanceExpression != null) {
2923                                         if (InstanceExpression is TypeExpr) {
2924                                                 var t = InstanceExpression.Type;
2925                                                 do {
2926                                                         ObsoleteAttribute oa = t.GetAttributeObsolete ();
2927                                                         if (oa != null && !rc.IsObsolete) {
2928                                                                 AttributeTester.Report_ObsoleteMessage (oa, t.GetSignatureForError (), loc, rc.Report);
2929                                                         }
2930
2931                                                         t = t.DeclaringType;
2932                                                 } while (t != null);
2933                                         } else {
2934                                                 var runtime_expr = InstanceExpression as RuntimeValueExpression;
2935                                                 if (runtime_expr == null || !runtime_expr.IsSuggestionOnly) {
2936                                                         rc.Report.Error (176, loc,
2937                                                                 "Static member `{0}' cannot be accessed with an instance reference, qualify it with a type name instead",
2938                                                                 GetSignatureForError ());
2939                                                 }
2940                                         }
2941
2942                                         InstanceExpression = null;
2943                                 }
2944
2945                                 return false;
2946                         }
2947
2948                         if (InstanceExpression == null || InstanceExpression is TypeExpr) {
2949                                 if (InstanceExpression != null || !This.IsThisAvailable (rc, true)) {
2950                                         if (rc.HasSet (ResolveContext.Options.FieldInitializerScope))
2951                                                 rc.Report.Error (236, loc,
2952                                                         "A field initializer cannot reference the nonstatic field, method, or property `{0}'",
2953                                                         GetSignatureForError ());
2954                                         else
2955                                                 rc.Report.Error (120, loc,
2956                                                         "An object reference is required to access non-static member `{0}'",
2957                                                         GetSignatureForError ());
2958
2959                                         InstanceExpression = new CompilerGeneratedThis (type, loc).Resolve (rc);
2960                                         return false;
2961                                 }
2962
2963                                 if (!TypeManager.IsFamilyAccessible (rc.CurrentType, DeclaringType)) {
2964                                         rc.Report.Error (38, loc,
2965                                                 "Cannot access a nonstatic member of outer type `{0}' via nested type `{1}'",
2966                                                 DeclaringType.GetSignatureForError (), rc.CurrentType.GetSignatureForError ());
2967                                 }
2968
2969                                 InstanceExpression = new This (loc);
2970                                 if (this is FieldExpr && rc.CurrentBlock.ParametersBlock.TopBlock.ThisVariable != null) {
2971                                         using (rc.Set (ResolveContext.Options.OmitStructFlowAnalysis)) {
2972                                                 InstanceExpression = InstanceExpression.Resolve (rc);
2973                                         }
2974                                 } else {
2975                                         InstanceExpression = InstanceExpression.Resolve (rc);
2976                                 }
2977
2978                                 return false;
2979                         }
2980
2981                         var me = InstanceExpression as MemberExpr;
2982                         if (me != null) {
2983                                 me.ResolveInstanceExpression (rc, rhs);
2984
2985                                 var fe = me as FieldExpr;
2986                                 if (fe != null && fe.IsMarshalByRefAccess (rc)) {
2987                                         rc.Report.SymbolRelatedToPreviousError (me.DeclaringType);
2988                                         rc.Report.Warning (1690, 1, loc,
2989                                                 "Cannot call methods, properties, or indexers on `{0}' because it is a value type member of a marshal-by-reference class",
2990                                                 me.GetSignatureForError ());
2991                                 }
2992
2993                                 return true;
2994                         }
2995
2996                         //
2997                         // Run member-access postponed check once we know that
2998                         // the expression is not field expression which is the only
2999                         // expression which can use uninitialized this
3000                         //
3001                         if (InstanceExpression is This && !(this is FieldExpr) && rc.CurrentBlock.ParametersBlock.TopBlock.ThisVariable != null) {
3002                                 ((This)InstanceExpression).CheckStructThisDefiniteAssignment (rc);
3003                         }
3004
3005                         //
3006                         // Additional checks for l-value member access
3007                         //
3008                         if (rhs != null) {
3009                                 if (InstanceExpression is UnboxCast) {
3010                                         rc.Report.Error (445, InstanceExpression.Location, "Cannot modify the result of an unboxing conversion");
3011                                 }
3012                         }
3013
3014                         return true;
3015                 }
3016
3017                 public virtual MemberExpr ResolveMemberAccess (ResolveContext ec, Expression left, SimpleName original)
3018                 {
3019                         if (left != null && left.IsNull && TypeSpec.IsReferenceType (left.Type)) {
3020                                 ec.Report.Warning (1720, 1, left.Location,
3021                                         "Expression will always cause a `{0}'", "System.NullReferenceException");
3022                         }
3023
3024                         InstanceExpression = left;
3025                         return this;
3026                 }
3027
3028                 protected void EmitInstance (EmitContext ec, bool prepare_for_load)
3029                 {
3030                         TypeSpec instance_type = InstanceExpression.Type;
3031                         if (TypeSpec.IsValueType (instance_type)) {
3032                                 if (InstanceExpression is IMemoryLocation) {
3033                                         ((IMemoryLocation) InstanceExpression).AddressOf (ec, AddressOp.Load);
3034                                 } else {
3035                                         // Cannot release the temporary variable when its address
3036                                         // is required to be on stack for any parent
3037                                         LocalTemporary t = new LocalTemporary (instance_type);
3038                                         InstanceExpression.Emit (ec);
3039                                         t.Store (ec);
3040                                         t.AddressOf (ec, AddressOp.Store);
3041                                 }
3042                         } else {
3043                                 InstanceExpression.Emit (ec);
3044
3045                                 // Only to make verifier happy
3046                                 if (instance_type.IsGenericParameter && !(InstanceExpression is This) && TypeSpec.IsReferenceType (instance_type))
3047                                         ec.Emit (OpCodes.Box, instance_type);
3048                         }
3049
3050                         if (prepare_for_load)
3051                                 ec.Emit (OpCodes.Dup);
3052                 }
3053
3054                 public abstract void SetTypeArguments (ResolveContext ec, TypeArguments ta);
3055         }
3056
3057         public class ExtensionMethodCandidates
3058         {
3059                 readonly NamespaceContainer container;
3060                 readonly IList<MethodSpec> methods;
3061                 readonly int index;
3062                 readonly IMemberContext context;
3063
3064                 public ExtensionMethodCandidates (IMemberContext context, IList<MethodSpec> methods, NamespaceContainer nsContainer, int lookupIndex)
3065                 {
3066                         this.context = context;
3067                         this.methods = methods;
3068                         this.container = nsContainer;
3069                         this.index = lookupIndex;
3070                 }
3071
3072                 public NamespaceContainer Container {
3073                         get {
3074                                 return container;
3075                         }
3076                 }
3077
3078                 public IMemberContext Context {
3079                         get {
3080                                 return context;
3081                         }
3082                 }
3083
3084                 public int LookupIndex {
3085                         get {
3086                                 return index;
3087                         }
3088                 }
3089
3090                 public IList<MethodSpec> Methods {
3091                         get {
3092                                 return methods;
3093                         }
3094                 }
3095         }
3096
3097         //
3098         // Represents a group of extension method candidates for whole namespace
3099         //
3100         class ExtensionMethodGroupExpr : MethodGroupExpr, OverloadResolver.IErrorHandler
3101         {
3102                 ExtensionMethodCandidates candidates;
3103                 public readonly Expression ExtensionExpression;
3104
3105                 public ExtensionMethodGroupExpr (ExtensionMethodCandidates candidates, Expression extensionExpr, Location loc)
3106                         : base (candidates.Methods.Cast<MemberSpec>().ToList (), extensionExpr.Type, loc)
3107                 {
3108                         this.candidates = candidates;
3109                         this.ExtensionExpression = extensionExpr;
3110                 }
3111
3112                 public override bool IsStatic {
3113                         get { return true; }
3114                 }
3115
3116                 //
3117                 // For extension methodgroup we are not looking for base members but parent
3118                 // namespace extension methods
3119                 //
3120                 public override IList<MemberSpec> GetBaseMembers (TypeSpec baseType)
3121                 {
3122                         // TODO: candidates are null only when doing error reporting, that's
3123                         // incorrect. We have to discover same extension methods in error mode
3124                         if (candidates == null)
3125                                 return null;
3126
3127                         int arity = type_arguments == null ? 0 : type_arguments.Count;
3128
3129                         candidates = candidates.Container.LookupExtensionMethod (candidates.Context, ExtensionExpression.Type, Name, arity, candidates.LookupIndex);
3130                         if (candidates == null)
3131                                 return null;
3132
3133                         return candidates.Methods.Cast<MemberSpec> ().ToList ();
3134                 }
3135
3136                 public override MethodGroupExpr LookupExtensionMethod (ResolveContext rc)
3137                 {
3138                         // We are already here
3139                         return null;
3140                 }
3141
3142                 public override MethodGroupExpr OverloadResolve (ResolveContext ec, ref Arguments arguments, OverloadResolver.IErrorHandler ehandler, OverloadResolver.Restrictions restr)
3143                 {
3144                         if (arguments == null)
3145                                 arguments = new Arguments (1);
3146
3147                         arguments.Insert (0, new Argument (ExtensionExpression, Argument.AType.ExtensionType));
3148                         var res = base.OverloadResolve (ec, ref arguments, ehandler ?? this, restr);
3149
3150                         // Store resolved argument and restore original arguments
3151                         if (res == null) {
3152                                 // Clean-up modified arguments for error reporting
3153                                 arguments.RemoveAt (0);
3154                                 return null;
3155                         }
3156
3157                         var me = ExtensionExpression as MemberExpr;
3158                         if (me != null)
3159                                 me.ResolveInstanceExpression (ec, null);
3160
3161                         InstanceExpression = null;
3162                         return this;
3163                 }
3164
3165                 #region IErrorHandler Members
3166
3167                 bool OverloadResolver.IErrorHandler.AmbiguousCandidates (ResolveContext rc, MemberSpec best, MemberSpec ambiguous)
3168                 {
3169                         return false;
3170                 }
3171
3172                 bool OverloadResolver.IErrorHandler.ArgumentMismatch (ResolveContext rc, MemberSpec best, Argument arg, int index)
3173                 {
3174                         rc.Report.SymbolRelatedToPreviousError (best);
3175                         rc.Report.Error (1928, loc,
3176                                 "Type `{0}' does not contain a member `{1}' and the best extension method overload `{2}' has some invalid arguments",
3177                                 queried_type.GetSignatureForError (), Name, best.GetSignatureForError ());
3178
3179                         if (index == 0) {
3180                                 rc.Report.Error (1929, loc,
3181                                         "Extension method instance type `{0}' cannot be converted to `{1}'",
3182                                         arg.Type.GetSignatureForError (), ((MethodSpec)best).Parameters.ExtensionMethodType.GetSignatureForError ());
3183                         }
3184
3185                         return true;
3186                 }
3187
3188                 bool OverloadResolver.IErrorHandler.NoArgumentMatch (ResolveContext rc, MemberSpec best)
3189                 {
3190                         return false;
3191                 }
3192
3193                 bool OverloadResolver.IErrorHandler.TypeInferenceFailed (ResolveContext rc, MemberSpec best)
3194                 {
3195                         return false;
3196                 }
3197
3198                 #endregion
3199         }
3200
3201         /// <summary>
3202         ///   MethodGroupExpr represents a group of method candidates which
3203         ///   can be resolved to the best method overload
3204         /// </summary>
3205         public class MethodGroupExpr : MemberExpr, OverloadResolver.IBaseMembersProvider
3206         {
3207                 protected IList<MemberSpec> Methods;
3208                 MethodSpec best_candidate;
3209                 TypeSpec best_candidate_return;
3210                 protected TypeArguments type_arguments;
3211
3212                 SimpleName simple_name;
3213                 protected TypeSpec queried_type;
3214
3215                 public MethodGroupExpr (IList<MemberSpec> mi, TypeSpec type, Location loc)
3216                 {
3217                         Methods = mi;
3218                         this.loc = loc;
3219                         this.type = InternalType.MethodGroup;
3220
3221                         eclass = ExprClass.MethodGroup;
3222                         queried_type = type;
3223                 }
3224
3225                 public MethodGroupExpr (MethodSpec m, TypeSpec type, Location loc)
3226                         : this (new MemberSpec[] { m }, type, loc)
3227                 {
3228                 }
3229
3230                 #region Properties
3231
3232                 public MethodSpec BestCandidate {
3233                         get {
3234                                 return best_candidate;
3235                         }
3236                 }
3237
3238                 public TypeSpec BestCandidateReturnType {
3239                         get {
3240                                 return best_candidate_return;
3241                         }
3242                 }
3243
3244                 public IList<MemberSpec> Candidates {
3245                         get {
3246                                 return Methods;
3247                         }
3248                 }
3249
3250                 protected override TypeSpec DeclaringType {
3251                         get {
3252                                 return queried_type;
3253                         }
3254                 }
3255
3256                 public override bool IsInstance {
3257                         get {
3258                                 if (best_candidate != null)
3259                                         return !best_candidate.IsStatic;
3260
3261                                 return false;
3262                         }
3263                 }
3264
3265                 public override bool IsStatic {
3266                         get {
3267                                 if (best_candidate != null)
3268                                         return best_candidate.IsStatic;
3269
3270                                 return false;
3271                         }
3272                 }
3273
3274                 public override string KindName {
3275                         get { return "method"; }
3276                 }
3277
3278                 public override string Name {
3279                         get {
3280                                 if (best_candidate != null)
3281                                         return best_candidate.Name;
3282
3283                                 // TODO: throw ?
3284                                 return Methods.First ().Name;
3285                         }
3286                 }
3287
3288                 #endregion
3289
3290                 //
3291                 // When best candidate is already know this factory can be used
3292                 // to avoid expensive overload resolution to be called
3293                 //
3294                 // NOTE: InstanceExpression has to be set manually
3295                 //
3296                 public static MethodGroupExpr CreatePredefined (MethodSpec best, TypeSpec queriedType, Location loc)
3297                 {
3298                         return new MethodGroupExpr (best, queriedType, loc) {
3299                                 best_candidate = best,
3300                                 best_candidate_return = best.ReturnType
3301                         };
3302                 }
3303
3304                 public override string GetSignatureForError ()
3305                 {
3306                         if (best_candidate != null)
3307                                 return best_candidate.GetSignatureForError ();
3308
3309                         return Methods.First ().GetSignatureForError ();
3310                 }
3311
3312                 public override Expression CreateExpressionTree (ResolveContext ec)
3313                 {
3314                         if (best_candidate == null) {
3315                                 ec.Report.Error (1953, loc, "An expression tree cannot contain an expression with method group");
3316                                 return null;
3317                         }
3318
3319                         if (best_candidate.IsConditionallyExcluded (ec, loc))
3320                                 ec.Report.Error (765, loc,
3321                                         "Partial methods with only a defining declaration or removed conditional methods cannot be used in an expression tree");
3322
3323                         return new TypeOfMethod (best_candidate, loc);
3324                 }
3325
3326                 protected override Expression DoResolve (ResolveContext ec)
3327                 {
3328                         this.eclass = ExprClass.MethodGroup;
3329
3330                         if (InstanceExpression != null) {
3331                                 InstanceExpression = InstanceExpression.Resolve (ec);
3332                                 if (InstanceExpression == null)
3333                                         return null;
3334                         }
3335
3336                         return this;
3337                 }
3338
3339                 public override void Emit (EmitContext ec)
3340                 {
3341                         throw new NotSupportedException ();
3342                 }
3343
3344                 public void EmitCall (EmitContext ec, Arguments arguments)
3345                 {
3346                         var call = new CallEmitter ();
3347                         call.InstanceExpression = InstanceExpression;
3348                         call.Emit (ec, best_candidate, arguments, loc);
3349                 }
3350
3351                 public override void Error_ValueCannotBeConverted (ResolveContext ec, Location loc, TypeSpec target, bool expl)
3352                 {
3353                         ec.Report.Error (428, loc, "Cannot convert method group `{0}' to non-delegate type `{1}'. Consider using parentheses to invoke the method",
3354                                 Name, TypeManager.CSharpName (target));
3355                 }
3356
3357                 public static bool IsExtensionMethodArgument (Expression expr)
3358                 {
3359                         //
3360                         // LAMESPEC: No details about which expressions are not allowed
3361                         //
3362                         return !(expr is TypeExpr) && !(expr is BaseThis);
3363                 }
3364
3365                 /// <summary>
3366                 ///   Find the Applicable Function Members (7.4.2.1)
3367                 ///
3368                 ///   me: Method Group expression with the members to select.
3369                 ///       it might contain constructors or methods (or anything
3370                 ///       that maps to a method).
3371                 ///
3372                 ///   Arguments: ArrayList containing resolved Argument objects.
3373                 ///
3374                 ///   loc: The location if we want an error to be reported, or a Null
3375                 ///        location for "probing" purposes.
3376                 ///
3377                 ///   Returns: The MethodBase (either a ConstructorInfo or a MethodInfo)
3378                 ///            that is the best match of me on Arguments.
3379                 ///
3380                 /// </summary>
3381                 public virtual MethodGroupExpr OverloadResolve (ResolveContext ec, ref Arguments args, OverloadResolver.IErrorHandler cerrors, OverloadResolver.Restrictions restr)
3382                 {
3383                         // TODO: causes issues with probing mode, remove explicit Kind check
3384                         if (best_candidate != null && best_candidate.Kind == MemberKind.Destructor)
3385                                 return this;
3386
3387                         var r = new OverloadResolver (Methods, type_arguments, restr, loc);
3388                         if ((restr & OverloadResolver.Restrictions.NoBaseMembers) == 0) {
3389                                 r.BaseMembersProvider = this;
3390                                 r.InstanceQualifier = this;
3391                         }
3392
3393                         if (cerrors != null)
3394                                 r.CustomErrors = cerrors;
3395
3396                         // TODO: When in probing mode do IsApplicable only and when called again do VerifyArguments for full error reporting
3397                         best_candidate = r.ResolveMember<MethodSpec> (ec, ref args);
3398                         if (best_candidate == null)
3399                                 return r.BestCandidateIsDynamic ? this : null;
3400
3401                         // Overload resolver had to create a new method group, all checks bellow have already been executed
3402                         if (r.BestCandidateNewMethodGroup != null)
3403                                 return r.BestCandidateNewMethodGroup;
3404
3405                         if (best_candidate.Kind == MemberKind.Method && (restr & OverloadResolver.Restrictions.ProbingOnly) == 0) {
3406                                 if (InstanceExpression != null) {
3407                                         if (best_candidate.IsExtensionMethod && args[0].Expr == InstanceExpression) {
3408                                                 InstanceExpression = null;
3409                                         } else {
3410                                                 if (best_candidate.IsStatic && simple_name != null) {
3411                                                         InstanceExpression = ProbeIdenticalTypeName (ec, InstanceExpression, simple_name);
3412                                                 }
3413
3414                                                 InstanceExpression.Resolve (ec);
3415                                         }
3416                                 }
3417
3418                                 ResolveInstanceExpression (ec, null);
3419                         }
3420
3421                         var base_override = CandidateToBaseOverride (ec, best_candidate);
3422                         if (base_override == best_candidate) {
3423                                 best_candidate_return = r.BestCandidateReturnType;
3424                         } else {
3425                                 best_candidate = base_override;
3426                                 best_candidate_return = best_candidate.ReturnType;
3427                         }
3428
3429                         return this;
3430                 }
3431
3432                 public override MemberExpr ResolveMemberAccess (ResolveContext ec, Expression left, SimpleName original)
3433                 {
3434                         simple_name = original;
3435                         return base.ResolveMemberAccess (ec, left, original);
3436                 }
3437
3438                 public override void SetTypeArguments (ResolveContext ec, TypeArguments ta)
3439                 {
3440                         type_arguments = ta;
3441                 }
3442
3443                 #region IBaseMembersProvider Members
3444
3445                 public virtual IList<MemberSpec> GetBaseMembers (TypeSpec baseType)
3446                 {
3447                         return baseType == null ? null : MemberCache.FindMembers (baseType, Methods [0].Name, false);
3448                 }
3449
3450                 public IParametersMember GetOverrideMemberParameters (MemberSpec member)
3451                 {
3452                         if (queried_type == member.DeclaringType)
3453                                 return null;
3454
3455                         return MemberCache.FindMember (queried_type, new MemberFilter ((MethodSpec) member),
3456                                 BindingRestriction.InstanceOnly | BindingRestriction.OverrideOnly) as IParametersMember;
3457                 }
3458
3459                 //
3460                 // Extension methods lookup after ordinary methods candidates failed to apply
3461                 //
3462                 public virtual MethodGroupExpr LookupExtensionMethod (ResolveContext rc)
3463                 {
3464                         if (InstanceExpression == null)
3465                                 return null;
3466
3467                         InstanceExpression = InstanceExpression.Resolve (rc);
3468                         if (!IsExtensionMethodArgument (InstanceExpression))
3469                                 return null;
3470
3471                         int arity = type_arguments == null ? 0 : type_arguments.Count;
3472                         var methods = rc.LookupExtensionMethod (InstanceExpression.Type, Methods[0].Name, arity);
3473                         if (methods == null)
3474                                 return null;
3475
3476                         var emg = new ExtensionMethodGroupExpr (methods, InstanceExpression, loc);
3477                         emg.SetTypeArguments (rc, type_arguments);
3478                         return emg;
3479                 }
3480
3481                 #endregion
3482         }
3483
3484         struct ConstructorInstanceQualifier : OverloadResolver.IInstanceQualifier
3485         {
3486                 public ConstructorInstanceQualifier (TypeSpec type)
3487                         : this ()
3488                 {
3489                         InstanceType = type;
3490                 }
3491
3492                 public TypeSpec InstanceType { get; private set; }
3493
3494                 public bool CheckProtectedMemberAccess (ResolveContext rc, MemberSpec member)
3495                 {
3496                         return MemberExpr.CheckProtectedMemberAccess (rc, member, InstanceType);
3497                 }
3498         }
3499
3500         public struct OverloadResolver
3501         {
3502                 [Flags]
3503                 public enum Restrictions
3504                 {
3505                         None = 0,
3506                         DelegateInvoke = 1,
3507                         ProbingOnly     = 1 << 1,
3508                         CovariantDelegate = 1 << 2,
3509                         NoBaseMembers = 1 << 3,
3510                         BaseMembersIncluded = 1 << 4
3511                 }
3512
3513                 public interface IBaseMembersProvider
3514                 {
3515                         IList<MemberSpec> GetBaseMembers (TypeSpec baseType);
3516                         IParametersMember GetOverrideMemberParameters (MemberSpec member);
3517                         MethodGroupExpr LookupExtensionMethod (ResolveContext rc);
3518                 }
3519
3520                 public interface IErrorHandler
3521                 {
3522                         bool AmbiguousCandidates (ResolveContext rc, MemberSpec best, MemberSpec ambiguous);
3523                         bool ArgumentMismatch (ResolveContext rc, MemberSpec best, Argument a, int index);
3524                         bool NoArgumentMatch (ResolveContext rc, MemberSpec best);
3525                         bool TypeInferenceFailed (ResolveContext rc, MemberSpec best);
3526                 }
3527
3528                 public interface IInstanceQualifier
3529                 {
3530                         TypeSpec InstanceType { get; }
3531                         bool CheckProtectedMemberAccess (ResolveContext rc, MemberSpec member);
3532                 }
3533
3534                 sealed class NoBaseMembers : IBaseMembersProvider
3535                 {
3536                         public static readonly IBaseMembersProvider Instance = new NoBaseMembers ();
3537
3538                         public IList<MemberSpec> GetBaseMembers (TypeSpec baseType)
3539                         {
3540                                 return null;
3541                         }
3542
3543                         public IParametersMember GetOverrideMemberParameters (MemberSpec member)
3544                         {
3545                                 return null;
3546                         }
3547
3548                         public MethodGroupExpr LookupExtensionMethod (ResolveContext rc)
3549                         {
3550                                 return null;
3551                         }
3552                 }
3553
3554                 struct AmbiguousCandidate
3555                 {
3556                         public readonly MemberSpec Member;
3557                         public readonly bool Expanded;
3558                         public readonly AParametersCollection Parameters;
3559
3560                         public AmbiguousCandidate (MemberSpec member, AParametersCollection parameters, bool expanded)
3561                         {
3562                                 Member = member;
3563                                 Parameters = parameters;
3564                                 Expanded = expanded;
3565                         }
3566                 }
3567
3568                 Location loc;
3569                 IList<MemberSpec> members;
3570                 TypeArguments type_arguments;
3571                 IBaseMembersProvider base_provider;
3572                 IErrorHandler custom_errors;
3573                 IInstanceQualifier instance_qualifier;
3574                 Restrictions restrictions;
3575                 MethodGroupExpr best_candidate_extension_group;
3576                 TypeSpec best_candidate_return_type;
3577
3578                 SessionReportPrinter lambda_conv_msgs;
3579                 ReportPrinter prev_recorder;
3580
3581                 public OverloadResolver (IList<MemberSpec> members, Restrictions restrictions, Location loc)
3582                         : this (members, null, restrictions, loc)
3583                 {
3584                 }
3585
3586                 public OverloadResolver (IList<MemberSpec> members, TypeArguments targs, Restrictions restrictions, Location loc)
3587                         : this ()
3588                 {
3589                         if (members == null || members.Count == 0)
3590                                 throw new ArgumentException ("empty members set");
3591
3592                         this.members = members;
3593                         this.loc = loc;
3594                         type_arguments = targs;
3595                         this.restrictions = restrictions;
3596                         if (IsDelegateInvoke)
3597                                 this.restrictions |= Restrictions.NoBaseMembers;
3598
3599                         base_provider = NoBaseMembers.Instance;
3600                 }
3601
3602                 #region Properties
3603
3604                 public IBaseMembersProvider BaseMembersProvider {
3605                         get {
3606                                 return base_provider;
3607                         }
3608                         set {
3609                                 base_provider = value;
3610                         }
3611                 }
3612
3613                 public bool BestCandidateIsDynamic { get; set; }
3614
3615                 //
3616                 // Best candidate was found in newly created MethodGroupExpr, used by extension methods
3617                 //
3618                 public MethodGroupExpr BestCandidateNewMethodGroup {
3619                         get {
3620                                 return best_candidate_extension_group;
3621                         }
3622                 }
3623
3624                 //
3625                 // Return type can be different between best candidate and closest override
3626                 //
3627                 public TypeSpec BestCandidateReturnType {
3628                         get {
3629                                 return best_candidate_return_type;
3630                         }
3631                 }
3632
3633                 public IErrorHandler CustomErrors {
3634                         get {
3635                                 return custom_errors;
3636                         }
3637                         set {
3638                                 custom_errors = value;
3639                         }
3640                 }
3641
3642                 TypeSpec DelegateType {
3643                         get {
3644                                 if ((restrictions & Restrictions.DelegateInvoke) == 0)
3645                                         throw new InternalErrorException ("Not running in delegate mode", loc);
3646
3647                                 return members [0].DeclaringType;
3648                         }
3649                 }
3650
3651                 public IInstanceQualifier InstanceQualifier {
3652                         get {
3653                                 return instance_qualifier;
3654                         }
3655                         set {
3656                                 instance_qualifier = value;
3657                         }
3658                 }
3659
3660                 bool IsProbingOnly {
3661                         get {
3662                                 return (restrictions & Restrictions.ProbingOnly) != 0;
3663                         }
3664                 }
3665
3666                 bool IsDelegateInvoke {
3667                         get {
3668                                 return (restrictions & Restrictions.DelegateInvoke) != 0;
3669                         }
3670                 }
3671
3672                 #endregion
3673
3674                 //
3675                 //  7.4.3.3  Better conversion from expression
3676                 //  Returns :   1    if a->p is better,
3677                 //              2    if a->q is better,
3678                 //              0 if neither is better
3679                 //
3680                 static int BetterExpressionConversion (ResolveContext ec, Argument a, TypeSpec p, TypeSpec q)
3681                 {
3682                         TypeSpec argument_type = a.Type;
3683
3684                         //
3685                         // If argument is an anonymous function
3686                         //
3687                         if (argument_type == InternalType.AnonymousMethod && ec.Module.Compiler.Settings.Version > LanguageVersion.ISO_2) {
3688                                 //
3689                                 // p and q are delegate types or expression tree types
3690                                 //
3691                                 if (p.IsExpressionTreeType || q.IsExpressionTreeType) {
3692                                         if (q.MemberDefinition != p.MemberDefinition) {
3693                                                 return 0;
3694                                         }
3695
3696                                         //
3697                                         // Uwrap delegate from Expression<T>
3698                                         //
3699                                         q = TypeManager.GetTypeArguments (q)[0];
3700                                         p = TypeManager.GetTypeArguments (p)[0];
3701                                 }
3702
3703                                 var p_m = Delegate.GetInvokeMethod (p);
3704                                 var q_m = Delegate.GetInvokeMethod (q);
3705
3706                                 //
3707                                 // With identical parameter lists
3708                                 //
3709                                 if (!TypeSpecComparer.Equals (p_m.Parameters.Types, q_m.Parameters.Types))
3710                                         return 0;
3711
3712                                 p = p_m.ReturnType;
3713                                 q = q_m.ReturnType;
3714
3715                                 //
3716                                 // if p is void returning, and q has a return type Y, then C2 is the better conversion.
3717                                 //
3718                                 if (p.Kind == MemberKind.Void) {
3719                                         return q.Kind != MemberKind.Void ? 2 : 0;
3720                                 }
3721
3722                                 //
3723                                 // if p has a return type Y, and q is void returning, then C1 is the better conversion.
3724                                 //
3725                                 if (q.Kind == MemberKind.Void) {
3726                                         return p.Kind != MemberKind.Void ? 1: 0;
3727                                 }
3728
3729                                 //
3730                                 // When anonymous method is an asynchronous, and P has a return type Task<Y1>, and Q has a return type Task<Y2>
3731                                 // better conversion is performed between underlying types Y1 and Y2
3732                                 //
3733                                 if (p.IsGenericTask || q.IsGenericTask) {
3734                                         var async_am = a.Expr as AnonymousMethodExpression;
3735                                         if (async_am != null && async_am.Block.IsAsync) {
3736
3737                                                 if (p.IsGenericTask != q.IsGenericTask) {
3738                                                         return 0;
3739                                                 }
3740
3741                                                 q = q.TypeArguments[0];
3742                                                 p = p.TypeArguments[0];
3743                                         }
3744                                 }
3745
3746                                 //
3747                                 // The parameters are identicial and return type is not void, use better type conversion
3748                                 // on return type to determine better one
3749                                 //
3750                         } else {
3751                                 if (argument_type == p)
3752                                         return 1;
3753
3754                                 if (argument_type == q)
3755                                         return 2;
3756                         }
3757
3758                         return BetterTypeConversion (ec, p, q);
3759                 }
3760
3761                 //
3762                 // 7.4.3.4  Better conversion from type
3763                 //
3764                 public static int BetterTypeConversion (ResolveContext ec, TypeSpec p, TypeSpec q)
3765                 {
3766                         if (p == null || q == null)
3767                                 throw new InternalErrorException ("BetterTypeConversion got a null conversion");
3768
3769                         switch (p.BuiltinType) {
3770                         case BuiltinTypeSpec.Type.Int:
3771                                 if (q.BuiltinType == BuiltinTypeSpec.Type.UInt || q.BuiltinType == BuiltinTypeSpec.Type.ULong)
3772                                         return 1;
3773                                 break;
3774                         case BuiltinTypeSpec.Type.Long:
3775                                 if (q.BuiltinType == BuiltinTypeSpec.Type.ULong)
3776                                         return 1;
3777                                 break;
3778                         case BuiltinTypeSpec.Type.SByte:
3779                                 switch (q.BuiltinType) {
3780                                 case BuiltinTypeSpec.Type.Byte:
3781                                 case BuiltinTypeSpec.Type.UShort:
3782                                 case BuiltinTypeSpec.Type.UInt:
3783                                 case BuiltinTypeSpec.Type.ULong:
3784                                         return 1;
3785                                 }
3786                                 break;
3787                         case BuiltinTypeSpec.Type.Short:
3788                                 switch (q.BuiltinType) {
3789                                 case BuiltinTypeSpec.Type.UShort:
3790                                 case BuiltinTypeSpec.Type.UInt:
3791                                 case BuiltinTypeSpec.Type.ULong:
3792                                         return 1;
3793                                 }
3794                                 break;
3795                         case BuiltinTypeSpec.Type.Dynamic:
3796                                 // Dynamic is never better
3797                                 return 2;
3798                         }
3799
3800                         switch (q.BuiltinType) {
3801                         case BuiltinTypeSpec.Type.Int:
3802                                 if (p.BuiltinType == BuiltinTypeSpec.Type.UInt || p.BuiltinType == BuiltinTypeSpec.Type.ULong)
3803                                         return 2;
3804                                 break;
3805                         case BuiltinTypeSpec.Type.Long:
3806                                 if (p.BuiltinType == BuiltinTypeSpec.Type.ULong)
3807                                         return 2;
3808                                 break;
3809                         case BuiltinTypeSpec.Type.SByte:
3810                                 switch (p.BuiltinType) {
3811                                 case BuiltinTypeSpec.Type.Byte:
3812                                 case BuiltinTypeSpec.Type.UShort:
3813                                 case BuiltinTypeSpec.Type.UInt:
3814                                 case BuiltinTypeSpec.Type.ULong:
3815                                         return 2;
3816                                 }
3817                                 break;
3818                         case BuiltinTypeSpec.Type.Short:
3819                                 switch (p.BuiltinType) {
3820                                 case BuiltinTypeSpec.Type.UShort:
3821                                 case BuiltinTypeSpec.Type.UInt:
3822                                 case BuiltinTypeSpec.Type.ULong:
3823                                         return 2;
3824                                 }
3825                                 break;
3826                         case BuiltinTypeSpec.Type.Dynamic:
3827                                 // Dynamic is never better
3828                                 return 1;
3829                         }
3830
3831                         // FIXME: handle lifted operators
3832
3833                         // TODO: this is expensive
3834                         Expression p_tmp = new EmptyExpression (p);
3835                         Expression q_tmp = new EmptyExpression (q);
3836
3837                         bool p_to_q = Convert.ImplicitConversionExists (ec, p_tmp, q);
3838                         bool q_to_p = Convert.ImplicitConversionExists (ec, q_tmp, p);
3839
3840                         if (p_to_q && !q_to_p)
3841                                 return 1;
3842
3843                         if (q_to_p && !p_to_q)
3844                                 return 2;
3845
3846                         return 0;
3847                 }
3848
3849                 /// <summary>
3850                 ///   Determines "Better function" between candidate
3851                 ///   and the current best match
3852                 /// </summary>
3853                 /// <remarks>
3854                 ///    Returns a boolean indicating :
3855                 ///     false if candidate ain't better
3856                 ///     true  if candidate is better than the current best match
3857                 /// </remarks>
3858                 static bool BetterFunction (ResolveContext ec, Arguments args, MemberSpec candidate, AParametersCollection cparam, bool candidate_params,
3859                         MemberSpec best, AParametersCollection bparam, bool best_params)
3860                 {
3861                         AParametersCollection candidate_pd = ((IParametersMember) candidate).Parameters;
3862                         AParametersCollection best_pd = ((IParametersMember) best).Parameters;
3863
3864                         bool better_at_least_one = false;
3865                         bool same = true;
3866                         int args_count = args == null ? 0 : args.Count;
3867                         int j = 0;
3868                         Argument a = null;
3869                         TypeSpec ct, bt;
3870                         for (int c_idx = 0, b_idx = 0; j < args_count; ++j, ++c_idx, ++b_idx) {
3871                                 a = args[j];
3872
3873                                 // Default arguments are ignored for better decision
3874                                 if (a.IsDefaultArgument)
3875                                         break;
3876
3877                                 //
3878                                 // When comparing named argument the parameter type index has to be looked up
3879                                 // in original parameter set (override version for virtual members)
3880                                 //
3881                                 NamedArgument na = a as NamedArgument;
3882                                 if (na != null) {
3883                                         int idx = cparam.GetParameterIndexByName (na.Name);
3884                                         ct = candidate_pd.Types[idx];
3885                                         if (candidate_params && candidate_pd.FixedParameters[idx].ModFlags == Parameter.Modifier.PARAMS)
3886                                                 ct = TypeManager.GetElementType (ct);
3887
3888                                         idx = bparam.GetParameterIndexByName (na.Name);
3889                                         bt = best_pd.Types[idx];
3890                                         if (best_params && best_pd.FixedParameters[idx].ModFlags == Parameter.Modifier.PARAMS)
3891                                                 bt = TypeManager.GetElementType (bt);
3892                                 } else {
3893                                         ct = candidate_pd.Types[c_idx];
3894                                         bt = best_pd.Types[b_idx];
3895
3896                                         if (candidate_params && candidate_pd.FixedParameters[c_idx].ModFlags == Parameter.Modifier.PARAMS) {
3897                                                 ct = TypeManager.GetElementType (ct);
3898                                                 --c_idx;
3899                                         }
3900
3901                                         if (best_params && best_pd.FixedParameters[b_idx].ModFlags == Parameter.Modifier.PARAMS) {
3902                                                 bt = TypeManager.GetElementType (bt);
3903                                                 --b_idx;
3904                                         }
3905                                 }
3906
3907                                 if (TypeSpecComparer.IsEqual (ct, bt))
3908                                         continue;
3909
3910                                 same = false;
3911                                 int result = BetterExpressionConversion (ec, a, ct, bt);
3912
3913                                 // for each argument, the conversion to 'ct' should be no worse than
3914                                 // the conversion to 'bt'.
3915                                 if (result == 2)
3916                                         return false;
3917
3918                                 // for at least one argument, the conversion to 'ct' should be better than
3919                                 // the conversion to 'bt'.
3920                                 if (result != 0)
3921                                         better_at_least_one = true;
3922                         }
3923
3924                         if (better_at_least_one)
3925                                 return true;
3926
3927                         //
3928                         // This handles the case
3929                         //
3930                         //   Add (float f1, float f2, float f3);
3931                         //   Add (params decimal [] foo);
3932                         //
3933                         // The call Add (3, 4, 5) should be ambiguous.  Without this check, the
3934                         // first candidate would've chosen as better.
3935                         //
3936                         if (!same && !a.IsDefaultArgument)
3937                                 return false;
3938
3939                         //
3940                         // The two methods have equal non-optional parameter types, apply tie-breaking rules
3941                         //
3942
3943                         //
3944                         // This handles the following cases:
3945                         //
3946                         //  Foo (int i) is better than Foo (int i, long l = 0)
3947                         //  Foo (params int[] args) is better than Foo (int i = 0, params int[] args)
3948                         //
3949                         // Prefer non-optional version
3950                         //
3951                         // LAMESPEC: Specification claims this should be done at last but the opposite is true
3952                         //
3953                         if (candidate_params == best_params && candidate_pd.Count != best_pd.Count) {
3954                                 if (candidate_pd.Count >= best_pd.Count)
3955                                         return false;
3956
3957                                 if (j < candidate_pd.Count && candidate_pd.FixedParameters[j].HasDefaultValue)
3958                                         return false;
3959
3960                                 return true;
3961                         }
3962
3963                         //
3964                         // One is a non-generic method and second is a generic method, then non-generic is better
3965                         //
3966                         if (best.IsGeneric != candidate.IsGeneric)
3967                                 return best.IsGeneric;
3968
3969                         //
3970                         // This handles the following cases:
3971                         //
3972                         //   Trim () is better than Trim (params char[] chars)
3973                         //   Concat (string s1, string s2, string s3) is better than
3974                         //     Concat (string s1, params string [] srest)
3975                         //   Foo (int, params int [] rest) is better than Foo (params int [] rest)
3976                         //
3977                         // Prefer non-expanded version
3978                         //
3979                         if (candidate_params != best_params)
3980                                 return best_params;
3981
3982                         int candidate_param_count = candidate_pd.Count;
3983                         int best_param_count = best_pd.Count;
3984
3985                         if (candidate_param_count != best_param_count)
3986                                 // can only happen if (candidate_params && best_params)
3987                                 return candidate_param_count > best_param_count && best_pd.HasParams;
3988
3989                         //
3990                         // Both methods have the same number of parameters, and the parameters have equal types
3991                         // Pick the "more specific" signature using rules over original (non-inflated) types
3992                         //
3993                         var candidate_def_pd = ((IParametersMember) candidate.MemberDefinition).Parameters;
3994                         var best_def_pd = ((IParametersMember) best.MemberDefinition).Parameters;
3995
3996                         bool specific_at_least_once = false;
3997                         for (j = 0; j < args_count; ++j) {
3998                                 NamedArgument na = args_count == 0 ? null : args [j] as NamedArgument;
3999                                 if (na != null) {
4000                                         ct = candidate_def_pd.Types[cparam.GetParameterIndexByName (na.Name)];
4001                                         bt = best_def_pd.Types[bparam.GetParameterIndexByName (na.Name)];
4002                                 } else {
4003                                         ct = candidate_def_pd.Types[j];
4004                                         bt = best_def_pd.Types[j];
4005                                 }
4006
4007                                 if (ct == bt)
4008                                         continue;
4009                                 TypeSpec specific = MoreSpecific (ct, bt);
4010                                 if (specific == bt)
4011                                         return false;
4012                                 if (specific == ct)
4013                                         specific_at_least_once = true;
4014                         }
4015
4016                         if (specific_at_least_once)
4017                                 return true;
4018
4019                         return false;
4020                 }
4021
4022                 public static void Error_ConstructorMismatch (ResolveContext rc, TypeSpec type, int argCount, Location loc)
4023                 {
4024                         rc.Report.Error (1729, loc,
4025                                 "The type `{0}' does not contain a constructor that takes `{1}' arguments",
4026                                 type.GetSignatureForError (), argCount.ToString ());
4027                 }
4028
4029                 //
4030                 // Determines if the candidate method is applicable to the given set of arguments
4031                 // There could be two different set of parameters for same candidate where one
4032                 // is the closest override for default values and named arguments checks and second
4033                 // one being the virtual base for the parameter types and modifiers.
4034                 //
4035                 // A return value rates candidate method compatibility,
4036                 // 0 = the best, int.MaxValue = the worst
4037                 //
4038                 int IsApplicable (ResolveContext ec, ref Arguments arguments, int arg_count, ref MemberSpec candidate, IParametersMember pm, ref bool params_expanded_form, ref bool dynamicArgument, ref TypeSpec returnType)
4039                 {
4040                         // Parameters of most-derived type used mainly for named and optional parameters
4041                         var pd = pm.Parameters;
4042
4043                         // Used for params modifier only, that's legacy of C# 1.0 which uses base type for
4044                         // params modifier instead of most-derived type
4045                         var cpd = ((IParametersMember) candidate).Parameters;
4046                         int param_count = pd.Count;
4047                         int optional_count = 0;
4048                         int score;
4049                         Arguments orig_args = arguments;
4050
4051                         if (arg_count != param_count) {
4052                                 //
4053                                 // No arguments expansion when doing exact match for delegates
4054                                 //
4055                                 if ((restrictions & Restrictions.CovariantDelegate) == 0) {
4056                                         for (int i = 0; i < pd.Count; ++i) {
4057                                                 if (pd.FixedParameters[i].HasDefaultValue) {
4058                                                         optional_count = pd.Count - i;
4059                                                         break;
4060                                                 }
4061                                         }
4062                                 }
4063
4064                                 if (optional_count != 0) {
4065                                         // Readjust expected number when params used
4066                                         if (cpd.HasParams) {
4067                                                 optional_count--;
4068                                                 if (arg_count < param_count)
4069                                                         param_count--;
4070                                         } else if (arg_count > param_count) {
4071                                                 int args_gap = System.Math.Abs (arg_count - param_count);
4072                                                 return int.MaxValue - 10000 + args_gap;
4073                                         }
4074                                 } else if (arg_count != param_count) {
4075                                         int args_gap = System.Math.Abs (arg_count - param_count);
4076                                         if (!cpd.HasParams)
4077                                                 return int.MaxValue - 10000 + args_gap;
4078                                         if (arg_count < param_count - 1)
4079                                                 return int.MaxValue - 10000 + args_gap;
4080                                 }
4081
4082                                 // Resize to fit optional arguments
4083                                 if (optional_count != 0) {
4084                                         if (arguments == null) {
4085                                                 arguments = new Arguments (optional_count);
4086                                         } else {
4087                                                 // Have to create a new container, so the next run can do same
4088                                                 var resized = new Arguments (param_count);
4089                                                 resized.AddRange (arguments);
4090                                                 arguments = resized;
4091                                         }
4092
4093                                         for (int i = arg_count; i < param_count; ++i)
4094                                                 arguments.Add (null);
4095                                 }
4096                         }
4097
4098                         if (arg_count > 0) {
4099                                 //
4100                                 // Shuffle named arguments to the right positions if there are any
4101                                 //
4102                                 if (arguments[arg_count - 1] is NamedArgument) {
4103                                         arg_count = arguments.Count;
4104
4105                                         for (int i = 0; i < arg_count; ++i) {
4106                                                 bool arg_moved = false;
4107                                                 while (true) {
4108                                                         NamedArgument na = arguments[i] as NamedArgument;
4109                                                         if (na == null)
4110                                                                 break;
4111
4112                                                         int index = pd.GetParameterIndexByName (na.Name);
4113
4114                                                         // Named parameter not found
4115                                                         if (index < 0)
4116                                                                 return (i + 1) * 3;
4117
4118                                                         // already reordered
4119                                                         if (index == i)
4120                                                                 break;
4121
4122                                                         Argument temp;
4123                                                         if (index >= param_count) {
4124                                                                 // When using parameters which should not be available to the user
4125                                                                 if ((cpd.FixedParameters[index].ModFlags & Parameter.Modifier.PARAMS) == 0)
4126                                                                         break;
4127
4128                                                                 arguments.Add (null);
4129                                                                 ++arg_count;
4130                                                                 temp = null;
4131                                                         } else {
4132                                                                 temp = arguments[index];
4133
4134                                                                 // The slot has been taken by positional argument
4135                                                                 if (temp != null && !(temp is NamedArgument))
4136                                                                         break;
4137                                                         }
4138
4139                                                         if (!arg_moved) {
4140                                                                 arguments = arguments.MarkOrderedArgument (na);
4141                                                                 arg_moved = true;
4142                                                         }
4143
4144                                                         arguments[index] = arguments[i];
4145                                                         arguments[i] = temp;
4146
4147                                                         if (temp == null)
4148                                                                 break;
4149                                                 }
4150                                         }
4151                                 } else {
4152                                         arg_count = arguments.Count;
4153                                 }
4154                         } else if (arguments != null) {
4155                                 arg_count = arguments.Count;
4156                         }
4157
4158                         //
4159                         // 1. Handle generic method using type arguments when specified or type inference
4160                         //
4161                         TypeSpec[] ptypes;
4162                         var ms = candidate as MethodSpec;
4163                         if (ms != null && ms.IsGeneric) {
4164                                 // Setup constraint checker for probing only
4165                                 ConstraintChecker cc = new ConstraintChecker (null);
4166
4167                                 if (type_arguments != null) {
4168                                         var g_args_count = ms.Arity;
4169                                         if (g_args_count != type_arguments.Count)
4170                                                 return int.MaxValue - 20000 + System.Math.Abs (type_arguments.Count - g_args_count);
4171
4172                                         ms = ms.MakeGenericMethod (ec, type_arguments.Arguments);
4173                                 } else {
4174                                         // TODO: It should not be here (we don't know yet whether any argument is lambda) but
4175                                         // for now it simplifies things. I should probably add a callback to ResolveContext
4176                                         if (lambda_conv_msgs == null) {
4177                                                 lambda_conv_msgs = new SessionReportPrinter ();
4178                                                 prev_recorder = ec.Report.SetPrinter (lambda_conv_msgs);
4179                                         }
4180
4181                                         var ti = new TypeInference (arguments);
4182                                         TypeSpec[] i_args = ti.InferMethodArguments (ec, ms);
4183                                         lambda_conv_msgs.EndSession ();
4184
4185                                         if (i_args == null)
4186                                                 return ti.InferenceScore - 20000;
4187
4188                                         if (i_args.Length != 0) {
4189                                                 ms = ms.MakeGenericMethod (ec, i_args);
4190                                         }
4191
4192                                         cc.IgnoreInferredDynamic = true;
4193                                 }
4194
4195                                 //
4196                                 // Type arguments constraints have to match for the method to be applicable
4197                                 //
4198                                 if (!cc.CheckAll (ms.GetGenericMethodDefinition (), ms.TypeArguments, ms.Constraints, loc)) {
4199                                         candidate = ms;
4200                                         return int.MaxValue - 25000;
4201                                 }
4202
4203                                 //
4204                                 // We have a generic return type and at same time the method is override which
4205                                 // means we have to also inflate override return type in case the candidate is
4206                                 // best candidate and override return type is different to base return type.
4207                                 //
4208                                 // virtual Foo<T, object> with override Foo<T, dynamic>
4209                                 //
4210                                 if (candidate != pm) {
4211                                         MethodSpec override_ms = (MethodSpec) pm;
4212                                         var inflator = new TypeParameterInflator (ec, ms.DeclaringType, override_ms.GenericDefinition.TypeParameters, ms.TypeArguments);
4213                                         returnType = inflator.Inflate (returnType);
4214                                 } else {
4215                                         returnType = ms.ReturnType;
4216                                 }
4217
4218                                 candidate = ms;
4219                                 ptypes = ms.Parameters.Types;
4220                         } else {
4221                                 if (type_arguments != null)
4222                                         return int.MaxValue - 15000;
4223
4224                                 ptypes = cpd.Types;
4225                         }
4226
4227                         //
4228                         // 2. Each argument has to be implicitly convertible to method parameter
4229                         //
4230                         Parameter.Modifier p_mod = 0;
4231                         TypeSpec pt = null;
4232
4233                         for (int i = 0; i < arg_count; i++) {
4234                                 Argument a = arguments[i];
4235                                 if (a == null) {
4236                                         var fp = pd.FixedParameters[i];
4237                                         if (!fp.HasDefaultValue) {
4238                                                 arguments = orig_args;
4239                                                 return arg_count * 2 + 2;
4240                                         }
4241
4242                                         //
4243                                         // Get the default value expression, we can use the same expression
4244                                         // if the type matches
4245                                         //
4246                                         Expression e = fp.DefaultValue;
4247                                         if (!(e is Constant) || e.Type.IsGenericOrParentIsGeneric || e.Type.IsGenericParameter) {
4248                                                 //
4249                                                 // LAMESPEC: No idea what the exact rules are for System.Reflection.Missing.Value instead of null
4250                                                 //
4251                                                 if (e == EmptyExpression.MissingValue && ptypes[i].BuiltinType == BuiltinTypeSpec.Type.Object || ptypes[i].BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
4252                                                         e = new MemberAccess (new MemberAccess (new MemberAccess (
4253                                                                 new QualifiedAliasMember (QualifiedAliasMember.GlobalAlias, "System", loc), "Reflection", loc), "Missing", loc), "Value", loc);
4254                                                 } else {
4255                                                         e = new DefaultValueExpression (new TypeExpression (ptypes [i], loc), loc);
4256                                                 }
4257
4258                                                 e = e.Resolve (ec);
4259                                         }
4260
4261                                         if ((fp.ModFlags & Parameter.Modifier.CallerMask) != 0) {
4262                                                 //
4263                                                 // LAMESPEC: Attributes can be mixed together with build-in priority
4264                                                 //
4265                                                 if ((fp.ModFlags & Parameter.Modifier.CallerLineNumber) != 0) {
4266                                                         e = new IntLiteral (ec.BuiltinTypes, loc.Row, loc);
4267                                                 } else if ((fp.ModFlags & Parameter.Modifier.CallerFilePath) != 0) {
4268                                                         e = new StringLiteral (ec.BuiltinTypes, loc.NameFullPath, loc);
4269                                                 } else if (ec.MemberContext.CurrentMemberDefinition != null) {
4270                                                         e = new StringLiteral (ec.BuiltinTypes, ec.MemberContext.CurrentMemberDefinition.GetCallerMemberName (), loc);
4271                                                 }
4272                                         }
4273
4274                                         arguments[i] = new Argument (e, Argument.AType.Default);
4275                                         continue;
4276                                 }
4277
4278                                 if (p_mod != Parameter.Modifier.PARAMS) {
4279                                         p_mod = (pd.FixedParameters[i].ModFlags & ~Parameter.Modifier.PARAMS) | (cpd.FixedParameters[i].ModFlags & Parameter.Modifier.PARAMS);
4280                                         pt = ptypes [i];
4281                                 } else if (!params_expanded_form) {
4282                                         params_expanded_form = true;
4283                                         pt = ((ElementTypeSpec) pt).Element;
4284                                         i -= 2;
4285                                         continue;
4286                                 }
4287
4288                                 score = 1;
4289                                 if (!params_expanded_form) {
4290                                         if (a.ArgType == Argument.AType.ExtensionType) {
4291                                                 //
4292                                                 // Indentity, implicit reference or boxing conversion must exist for the extension parameter
4293                                                 //
4294                                                 // LAMESPEC: or implicit type parameter conversion
4295                                                 //
4296                                                 var at = a.Type;
4297                                                 if (at == pt || TypeSpecComparer.IsEqual (at, pt) ||
4298                                                         Convert.ImplicitReferenceConversionExists (at, pt, false) ||
4299                                                         Convert.ImplicitBoxingConversion (null, at, pt) != null) {
4300                                                         score = 0;
4301                                                         continue;
4302                                                 }
4303                                         } else {
4304                                                 score = IsArgumentCompatible (ec, a, p_mod, pt);
4305
4306                                                 if (score < 0)
4307                                                         dynamicArgument = true;
4308                                         }
4309                                 }
4310
4311                                 //
4312                                 // It can be applicable in expanded form (when not doing exact match like for delegates)
4313                                 //
4314                                 if (score != 0 && (p_mod & Parameter.Modifier.PARAMS) != 0 && (restrictions & Restrictions.CovariantDelegate) == 0) {
4315                                         if (!params_expanded_form)
4316                                                 pt = ((ElementTypeSpec) pt).Element;
4317
4318                                         if (score > 0)
4319                                                 score = IsArgumentCompatible (ec, a, Parameter.Modifier.NONE, pt);
4320
4321                                         if (score == 0) {
4322                                                 params_expanded_form = true;
4323                                         } else if (score < 0) {
4324                                                 params_expanded_form = true;
4325                                                 dynamicArgument = true;
4326                                         }
4327                                 }
4328
4329                                 if (score > 0) {
4330                                         if (params_expanded_form)
4331                                                 ++score;
4332                                         return (arg_count - i) * 2 + score;
4333                                 }
4334                         }
4335
4336                         //
4337                         // When params parameter has no argument it will be provided later if the method is the best candidate
4338                         //
4339                         if (arg_count + 1 == pd.Count && (cpd.FixedParameters [arg_count].ModFlags & Parameter.Modifier.PARAMS) != 0)
4340                                 params_expanded_form = true;
4341
4342                         //
4343                         // Restore original arguments for dynamic binder to keep the intention of original source code
4344                         //
4345                         if (dynamicArgument)
4346                                 arguments = orig_args;
4347
4348                         return 0;
4349                 }
4350
4351                 //
4352                 // Tests argument compatibility with the parameter
4353                 // The possible return values are
4354                 // 0 - success
4355                 // 1 - modifier mismatch
4356                 // 2 - type mismatch
4357                 // -1 - dynamic binding required
4358                 //
4359                 int IsArgumentCompatible (ResolveContext ec, Argument argument, Parameter.Modifier param_mod, TypeSpec parameter)
4360                 {
4361                         //
4362                         // Types have to be identical when ref or out modifer
4363                         // is used and argument is not of dynamic type
4364                         //
4365                         if (((argument.Modifier | param_mod) & Parameter.Modifier.RefOutMask) != 0) {
4366                                 if (argument.Type != parameter) {
4367                                         //
4368                                         // Do full equality check after quick path
4369                                         //
4370                                         if (!TypeSpecComparer.IsEqual (argument.Type, parameter)) {
4371                                                 //
4372                                                 // Using dynamic for ref/out parameter can still succeed at runtime
4373                                                 //
4374                                                 if (argument.Type.BuiltinType == BuiltinTypeSpec.Type.Dynamic && (argument.Modifier & Parameter.Modifier.RefOutMask) == 0 && (restrictions & Restrictions.CovariantDelegate) == 0)
4375                                                         return -1;
4376
4377                                                 return 2;
4378                                         }
4379                                 }
4380
4381                                 if ((argument.Modifier & Parameter.Modifier.RefOutMask) != (param_mod & Parameter.Modifier.RefOutMask)) {
4382                                         //
4383                                         // Using dynamic for ref/out parameter can still succeed at runtime
4384                                         //
4385                                         if (argument.Type.BuiltinType == BuiltinTypeSpec.Type.Dynamic && (argument.Modifier & Parameter.Modifier.RefOutMask) == 0 && (restrictions & Restrictions.CovariantDelegate) == 0)
4386                                                 return -1;
4387
4388                                         return 1;
4389                                 }
4390
4391                         } else {
4392                                 if (argument.Type.BuiltinType == BuiltinTypeSpec.Type.Dynamic && (restrictions & Restrictions.CovariantDelegate) == 0)
4393                                         return -1;
4394
4395                                 //
4396                                 // Deploy custom error reporting for lambda methods. When probing lambda methods
4397                                 // keep all errors reported in separate set and once we are done and no best
4398                                 // candidate was found, this set is used to report more details about what was wrong
4399                                 // with lambda body
4400                                 //
4401                                 if (argument.Expr.Type == InternalType.AnonymousMethod) {
4402                                         if (lambda_conv_msgs == null) {
4403                                                 lambda_conv_msgs = new SessionReportPrinter ();
4404                                                 prev_recorder = ec.Report.SetPrinter (lambda_conv_msgs);
4405                                         }
4406                                 }
4407
4408                                 //
4409                                 // Use implicit conversion in all modes to return same candidates when the expression
4410                                 // is used as argument or delegate conversion
4411                                 //
4412                                 if (!Convert.ImplicitConversionExists (ec, argument.Expr, parameter)) {
4413                                         if (lambda_conv_msgs != null) {
4414                                                 lambda_conv_msgs.EndSession ();
4415                                         }
4416
4417                                         return 2;
4418                                 }
4419                         }
4420
4421                         return 0;
4422                 }
4423
4424                 static TypeSpec MoreSpecific (TypeSpec p, TypeSpec q)
4425                 {
4426                         if (TypeManager.IsGenericParameter (p) && !TypeManager.IsGenericParameter (q))
4427                                 return q;
4428                         if (!TypeManager.IsGenericParameter (p) && TypeManager.IsGenericParameter (q))
4429                                 return p;
4430
4431                         var ac_p = p as ArrayContainer;
4432                         if (ac_p != null) {
4433                                 var ac_q = q as ArrayContainer;
4434                                 if (ac_q == null)
4435                                         return null;
4436
4437                                 TypeSpec specific = MoreSpecific (ac_p.Element, ac_q.Element);
4438                                 if (specific == ac_p.Element)
4439                                         return p;
4440                                 if (specific == ac_q.Element)
4441                                         return q;
4442                         } else if (TypeManager.IsGenericType (p)) {
4443                                 var pargs = TypeManager.GetTypeArguments (p);
4444                                 var qargs = TypeManager.GetTypeArguments (q);
4445
4446                                 bool p_specific_at_least_once = false;
4447                                 bool q_specific_at_least_once = false;
4448
4449                                 for (int i = 0; i < pargs.Length; i++) {
4450                                         TypeSpec specific = MoreSpecific (pargs[i], qargs[i]);
4451                                         if (specific == pargs[i])
4452                                                 p_specific_at_least_once = true;
4453                                         if (specific == qargs[i])
4454                                                 q_specific_at_least_once = true;
4455                                 }
4456
4457                                 if (p_specific_at_least_once && !q_specific_at_least_once)
4458                                         return p;
4459                                 if (!p_specific_at_least_once && q_specific_at_least_once)
4460                                         return q;
4461                         }
4462
4463                         return null;
4464                 }
4465
4466                 //
4467                 // Find the best method from candidate list
4468                 //
4469                 public T ResolveMember<T> (ResolveContext rc, ref Arguments args) where T : MemberSpec, IParametersMember
4470                 {
4471                         List<AmbiguousCandidate> ambiguous_candidates = null;
4472
4473                         MemberSpec best_candidate;
4474                         Arguments best_candidate_args = null;
4475                         bool best_candidate_params = false;
4476                         bool best_candidate_dynamic = false;
4477                         int best_candidate_rate;
4478                         IParametersMember best_parameter_member = null;
4479
4480                         int args_count = args != null ? args.Count : 0;
4481
4482                         Arguments candidate_args = args;
4483                         bool error_mode = false;
4484                         MemberSpec invocable_member = null;
4485
4486                         // Be careful, cannot return until error reporter is restored
4487                         while (true) {
4488                                 best_candidate = null;
4489                                 best_candidate_rate = int.MaxValue;
4490
4491                                 var type_members = members;
4492                                 try {
4493
4494                                         do {
4495                                                 for (int i = 0; i < type_members.Count; ++i) {
4496                                                         var member = type_members[i];
4497
4498                                                         //
4499                                                         // Methods in a base class are not candidates if any method in a derived
4500                                                         // class is applicable
4501                                                         //
4502                                                         if ((member.Modifiers & Modifiers.OVERRIDE) != 0)
4503                                                                 continue;
4504
4505                                                         if (!error_mode) {
4506                                                                 if (!member.IsAccessible (rc))
4507                                                                         continue;
4508
4509                                                                 if (rc.IsRuntimeBinder && !member.DeclaringType.IsAccessible (rc))
4510                                                                         continue;
4511
4512                                                                 if ((member.Modifiers & (Modifiers.PROTECTED | Modifiers.STATIC)) == Modifiers.PROTECTED &&
4513                                                                         instance_qualifier != null && !instance_qualifier.CheckProtectedMemberAccess (rc, member)) {
4514                                                                         continue;
4515                                                                 }
4516                                                         }
4517
4518                                                         IParametersMember pm = member as IParametersMember;
4519                                                         if (pm == null) {
4520                                                                 //
4521                                                                 // Will use it later to report ambiguity between best method and invocable member
4522                                                                 //
4523                                                                 if (Invocation.IsMemberInvocable (member))
4524                                                                         invocable_member = member;
4525
4526                                                                 continue;
4527                                                         }
4528
4529                                                         //
4530                                                         // Overload resolution is looking for base member but using parameter names
4531                                                         // and default values from the closest member. That means to do expensive lookup
4532                                                         // for the closest override for virtual or abstract members
4533                                                         //
4534                                                         if ((member.Modifiers & (Modifiers.VIRTUAL | Modifiers.ABSTRACT)) != 0) {
4535                                                                 var override_params = base_provider.GetOverrideMemberParameters (member);
4536                                                                 if (override_params != null)
4537                                                                         pm = override_params;
4538                                                         }
4539
4540                                                         //
4541                                                         // Check if the member candidate is applicable
4542                                                         //
4543                                                         bool params_expanded_form = false;
4544                                                         bool dynamic_argument = false;
4545                                                         TypeSpec rt = pm.MemberType;
4546                                                         int candidate_rate = IsApplicable (rc, ref candidate_args, args_count, ref member, pm, ref params_expanded_form, ref dynamic_argument, ref rt);
4547
4548                                                         //
4549                                                         // How does it score compare to others
4550                                                         //
4551                                                         if (candidate_rate < best_candidate_rate) {
4552                                                                 best_candidate_rate = candidate_rate;
4553                                                                 best_candidate = member;
4554                                                                 best_candidate_args = candidate_args;
4555                                                                 best_candidate_params = params_expanded_form;
4556                                                                 best_candidate_dynamic = dynamic_argument;
4557                                                                 best_parameter_member = pm;
4558                                                                 best_candidate_return_type = rt;
4559                                                         } else if (candidate_rate == 0) {
4560                                                                 //
4561                                                                 // The member look is done per type for most operations but sometimes
4562                                                                 // it's not possible like for binary operators overload because they
4563                                                                 // are unioned between 2 sides
4564                                                                 //
4565                                                                 if ((restrictions & Restrictions.BaseMembersIncluded) != 0) {
4566                                                                         if (TypeSpec.IsBaseClass (best_candidate.DeclaringType, member.DeclaringType, true))
4567                                                                                 continue;
4568                                                                 }
4569
4570                                                                 bool is_better;
4571                                                                 if (best_candidate.DeclaringType.IsInterface && member.DeclaringType.ImplementsInterface (best_candidate.DeclaringType, false)) {
4572                                                                         //
4573                                                                         // We pack all interface members into top level type which makes the overload resolution
4574                                                                         // more complicated for interfaces. We compensate it by removing methods with same
4575                                                                         // signature when building the cache hence this path should not really be hit often
4576                                                                         //
4577                                                                         // Example:
4578                                                                         // interface IA { void Foo (int arg); }
4579                                                                         // interface IB : IA { void Foo (params int[] args); }
4580                                                                         //
4581                                                                         // IB::Foo is the best overload when calling IB.Foo (1)
4582                                                                         //
4583                                                                         is_better = true;
4584                                                                         if (ambiguous_candidates != null) {
4585                                                                                 foreach (var amb_cand in ambiguous_candidates) {
4586                                                                                         if (member.DeclaringType.ImplementsInterface (best_candidate.DeclaringType, false)) {
4587                                                                                                 continue;
4588                                                                                         }
4589
4590                                                                                         is_better = false;
4591                                                                                         break;
4592                                                                                 }
4593
4594                                                                                 if (is_better)
4595                                                                                         ambiguous_candidates = null;
4596                                                                         }
4597                                                                 } else {
4598                                                                         // Is the new candidate better
4599                                                                         is_better = BetterFunction (rc, candidate_args, member, pm.Parameters, params_expanded_form, best_candidate, best_parameter_member.Parameters, best_candidate_params);
4600                                                                 }
4601
4602                                                                 if (is_better) {
4603                                                                         best_candidate = member;
4604                                                                         best_candidate_args = candidate_args;
4605                                                                         best_candidate_params = params_expanded_form;
4606                                                                         best_candidate_dynamic = dynamic_argument;
4607                                                                         best_parameter_member = pm;
4608                                                                         best_candidate_return_type = rt;
4609                                                                 } else {
4610                                                                         // It's not better but any other found later could be but we are not sure yet
4611                                                                         if (ambiguous_candidates == null)
4612                                                                                 ambiguous_candidates = new List<AmbiguousCandidate> ();
4613
4614                                                                         ambiguous_candidates.Add (new AmbiguousCandidate (member, pm.Parameters, params_expanded_form));
4615                                                                 }
4616                                                         }
4617
4618                                                         // Restore expanded arguments
4619                                                         if (candidate_args != args)
4620                                                                 candidate_args = args;
4621                                                 }
4622                                         } while (best_candidate_rate != 0 && (type_members = base_provider.GetBaseMembers (type_members[0].DeclaringType.BaseType)) != null);
4623                                 } finally {
4624                                         if (prev_recorder != null)
4625                                                 rc.Report.SetPrinter (prev_recorder);
4626                                 }
4627
4628                                 //
4629                                 // We've found exact match
4630                                 //
4631                                 if (best_candidate_rate == 0)
4632                                         break;
4633
4634                                 //
4635                                 // Try extension methods lookup when no ordinary method match was found and provider enables it
4636                                 //
4637                                 if (!error_mode) {
4638                                         var emg = base_provider.LookupExtensionMethod (rc);
4639                                         if (emg != null) {
4640                                                 emg = emg.OverloadResolve (rc, ref args, null, restrictions);
4641                                                 if (emg != null) {
4642                                                         best_candidate_extension_group = emg;
4643                                                         return (T) (MemberSpec) emg.BestCandidate;
4644                                                 }
4645                                         }
4646                                 }
4647
4648                                 // Don't run expensive error reporting mode for probing
4649                                 if (IsProbingOnly)
4650                                         return null;
4651
4652                                 if (error_mode)
4653                                         break;
4654
4655                                 if (lambda_conv_msgs != null && !lambda_conv_msgs.IsEmpty)
4656                                         break;
4657
4658                                 lambda_conv_msgs = null;
4659                                 error_mode = true;
4660                         }
4661
4662                         //
4663                         // No best member match found, report an error
4664                         //
4665                         if (best_candidate_rate != 0 || error_mode) {
4666                                 ReportOverloadError (rc, best_candidate, best_parameter_member, best_candidate_args, best_candidate_params);
4667                                 return null;
4668                         }
4669
4670                         if (best_candidate_dynamic) {
4671                                 if (args[0].ArgType == Argument.AType.ExtensionType) {
4672                                         rc.Report.Error (1973, loc,
4673                                                 "Type `{0}' does not contain a member `{1}' and the best extension method overload `{2}' cannot be dynamically dispatched. Consider calling the method without the extension method syntax",
4674                                                 args [0].Type.GetSignatureForError (), best_candidate.Name, best_candidate.GetSignatureForError ());
4675                                 }
4676
4677                                 BestCandidateIsDynamic = true;
4678                                 return null;
4679                         }
4680
4681                         //
4682                         // These flags indicates we are running delegate probing conversion. No need to
4683                         // do more expensive checks
4684                         //
4685                         if ((restrictions & (Restrictions.ProbingOnly | Restrictions.CovariantDelegate)) == (Restrictions.CovariantDelegate | Restrictions.ProbingOnly))
4686                                 return (T) best_candidate;
4687
4688                         if (ambiguous_candidates != null) {
4689                                 //
4690                                 // Now check that there are no ambiguities i.e the selected method
4691                                 // should be better than all the others
4692                                 //
4693                                 for (int ix = 0; ix < ambiguous_candidates.Count; ix++) {
4694                                         var candidate = ambiguous_candidates [ix];
4695
4696                                         if (!BetterFunction (rc, best_candidate_args, best_candidate, best_parameter_member.Parameters, best_candidate_params, candidate.Member, candidate.Parameters, candidate.Expanded)) {
4697                                                 var ambiguous = candidate.Member;
4698                                                 if (custom_errors == null || !custom_errors.AmbiguousCandidates (rc, best_candidate, ambiguous)) {
4699                                                         rc.Report.SymbolRelatedToPreviousError (best_candidate);
4700                                                         rc.Report.SymbolRelatedToPreviousError (ambiguous);
4701                                                         rc.Report.Error (121, loc, "The call is ambiguous between the following methods or properties: `{0}' and `{1}'",
4702                                                                 best_candidate.GetSignatureForError (), ambiguous.GetSignatureForError ());
4703                                                 }
4704
4705                                                 return (T) best_candidate;
4706                                         }
4707                                 }
4708                         }
4709
4710                         if (invocable_member != null) {
4711                                 rc.Report.SymbolRelatedToPreviousError (best_candidate);
4712                                 rc.Report.SymbolRelatedToPreviousError (invocable_member);
4713                                 rc.Report.Warning (467, 2, loc, "Ambiguity between method `{0}' and invocable non-method `{1}'. Using method group",
4714                                         best_candidate.GetSignatureForError (), invocable_member.GetSignatureForError ());
4715                         }
4716
4717                         //
4718                         // And now check if the arguments are all
4719                         // compatible, perform conversions if
4720                         // necessary etc. and return if everything is
4721                         // all right
4722                         //
4723                         if (!VerifyArguments (rc, ref best_candidate_args, best_candidate, best_parameter_member, best_candidate_params))
4724                                 return null;
4725
4726                         if (best_candidate == null)
4727                                 return null;
4728
4729                         //
4730                         // Check ObsoleteAttribute on the best method
4731                         //
4732                         ObsoleteAttribute oa = best_candidate.GetAttributeObsolete ();
4733                         if (oa != null && !rc.IsObsolete)
4734                                 AttributeTester.Report_ObsoleteMessage (oa, best_candidate.GetSignatureForError (), loc, rc.Report);
4735
4736                         var dep = best_candidate.GetMissingDependencies ();
4737                         if (dep != null) {
4738                                 ImportedTypeDefinition.Error_MissingDependency (rc, dep, loc);
4739                         }
4740
4741                         best_candidate.MemberDefinition.SetIsUsed ();
4742
4743                         args = best_candidate_args;
4744                         return (T) best_candidate;
4745                 }
4746
4747                 public MethodSpec ResolveOperator (ResolveContext rc, ref Arguments args)
4748                 {
4749                         return ResolveMember<MethodSpec> (rc, ref args);
4750                 }
4751
4752                 void ReportArgumentMismatch (ResolveContext ec, int idx, MemberSpec method,
4753                                                                                                         Argument a, AParametersCollection expected_par, TypeSpec paramType)
4754                 {
4755                         if (custom_errors != null && custom_errors.ArgumentMismatch (ec, method, a, idx))
4756                                 return;
4757
4758                         if (a.Type == InternalType.ErrorType)
4759                                 return;
4760
4761                         if (a is CollectionElementInitializer.ElementInitializerArgument) {
4762                                 ec.Report.SymbolRelatedToPreviousError (method);
4763                                 if ((expected_par.FixedParameters[idx].ModFlags & Parameter.Modifier.RefOutMask) != 0) {
4764                                         ec.Report.Error (1954, loc, "The best overloaded collection initalizer method `{0}' cannot have 'ref', or `out' modifier",
4765                                                 TypeManager.CSharpSignature (method));
4766                                         return;
4767                                 }
4768                                 ec.Report.Error (1950, loc, "The best overloaded collection initalizer method `{0}' has some invalid arguments",
4769                                           TypeManager.CSharpSignature (method));
4770                         } else if (IsDelegateInvoke) {
4771                                 ec.Report.Error (1594, loc, "Delegate `{0}' has some invalid arguments",
4772                                         DelegateType.GetSignatureForError ());
4773                         } else {
4774                                 ec.Report.SymbolRelatedToPreviousError (method);
4775                                 ec.Report.Error (1502, loc, "The best overloaded method match for `{0}' has some invalid arguments",
4776                                         method.GetSignatureForError ());
4777                         }
4778
4779                         Parameter.Modifier mod = idx >= expected_par.Count ? 0 : expected_par.FixedParameters[idx].ModFlags;
4780
4781                         string index = (idx + 1).ToString ();
4782                         if (((mod & Parameter.Modifier.RefOutMask) ^ (a.Modifier & Parameter.Modifier.RefOutMask)) != 0) {
4783                                 if ((mod & Parameter.Modifier.RefOutMask) == 0)
4784                                         ec.Report.Error (1615, loc, "Argument `#{0}' does not require `{1}' modifier. Consider removing `{1}' modifier",
4785                                                 index, Parameter.GetModifierSignature (a.Modifier));
4786                                 else
4787                                         ec.Report.Error (1620, loc, "Argument `#{0}' is missing `{1}' modifier",
4788                                                 index, Parameter.GetModifierSignature (mod));
4789                         } else {
4790                                 string p1 = a.GetSignatureForError ();
4791                                 string p2 = TypeManager.CSharpName (paramType);
4792
4793                                 if (p1 == p2) {
4794                                         p1 = a.Type.GetSignatureForErrorIncludingAssemblyName ();
4795                                         p2 = paramType.GetSignatureForErrorIncludingAssemblyName ();
4796                                 }
4797
4798                                 ec.Report.Error (1503, loc,
4799                                         "Argument `#{0}' cannot convert `{1}' expression to type `{2}'", index, p1, p2);
4800                         }
4801                 }
4802
4803                 //
4804                 // We have failed to find exact match so we return error info about the closest match
4805                 //
4806                 void ReportOverloadError (ResolveContext rc, MemberSpec best_candidate, IParametersMember pm, Arguments args, bool params_expanded)
4807                 {
4808                         int ta_count = type_arguments == null ? 0 : type_arguments.Count;
4809                         int arg_count = args == null ? 0 : args.Count;
4810
4811                         if (ta_count != best_candidate.Arity && (ta_count > 0 || ((IParametersMember) best_candidate).Parameters.IsEmpty)) {
4812                                 var mg = new MethodGroupExpr (new [] { best_candidate }, best_candidate.DeclaringType, loc);
4813                                 mg.Error_TypeArgumentsCannotBeUsed (rc, best_candidate, ta_count, loc);
4814                                 return;
4815                         }
4816
4817                         if (lambda_conv_msgs != null) {
4818                                 if (lambda_conv_msgs.Merge (rc.Report.Printer))
4819                                         return;
4820                         }
4821
4822
4823                         if ((best_candidate.Modifiers & (Modifiers.PROTECTED | Modifiers.STATIC)) == Modifiers.PROTECTED &&
4824                                 InstanceQualifier != null && !InstanceQualifier.CheckProtectedMemberAccess (rc, best_candidate)) {
4825                                 MemberExpr.Error_ProtectedMemberAccess (rc, best_candidate, InstanceQualifier.InstanceType, loc);
4826                         }
4827
4828                         //
4829                         // For candidates which match on parameters count report more details about incorrect arguments
4830                         //
4831                         if (pm != null) {
4832                                 int unexpanded_count = ((IParametersMember) best_candidate).Parameters.HasParams ? pm.Parameters.Count - 1 : pm.Parameters.Count;
4833                                 if (pm.Parameters.Count == arg_count || params_expanded || unexpanded_count == arg_count) {
4834                                         // Reject any inaccessible member
4835                                         if (!best_candidate.IsAccessible (rc) || !best_candidate.DeclaringType.IsAccessible (rc)) {
4836                                                 rc.Report.SymbolRelatedToPreviousError (best_candidate);
4837                                                 Expression.ErrorIsInaccesible (rc, best_candidate.GetSignatureForError (), loc);
4838                                                 return;
4839                                         }
4840
4841                                         var ms = best_candidate as MethodSpec;
4842                                         if (ms != null && ms.IsGeneric) {
4843                                                 bool constr_ok = true;
4844                                                 if (ms.TypeArguments != null)
4845                                                         constr_ok = new ConstraintChecker (rc.MemberContext).CheckAll (ms.GetGenericMethodDefinition (), ms.TypeArguments, ms.Constraints, loc);
4846
4847                                                 if (ta_count == 0) {
4848                                                         if (custom_errors != null && custom_errors.TypeInferenceFailed (rc, best_candidate))
4849                                                                 return;
4850
4851                                                         if (constr_ok) {
4852                                                                 rc.Report.Error (411, loc,
4853                                                                         "The type arguments for method `{0}' cannot be inferred from the usage. Try specifying the type arguments explicitly",
4854                                                                         ms.GetGenericMethodDefinition ().GetSignatureForError ());
4855                                                         }
4856
4857                                                         return;
4858                                                 }
4859                                         }
4860
4861                                         VerifyArguments (rc, ref args, best_candidate, pm, params_expanded);
4862                                         return;
4863                                 }
4864                         }
4865
4866                         //
4867                         // We failed to find any method with correct argument count, report best candidate
4868                         //
4869                         if (custom_errors != null && custom_errors.NoArgumentMatch (rc, best_candidate))
4870                                 return;
4871
4872                         if (best_candidate.Kind == MemberKind.Constructor) {
4873                                 rc.Report.SymbolRelatedToPreviousError (best_candidate);
4874                                 Error_ConstructorMismatch (rc, best_candidate.DeclaringType, arg_count, loc);
4875                         } else if (IsDelegateInvoke) {
4876                                 rc.Report.SymbolRelatedToPreviousError (DelegateType);
4877                                 rc.Report.Error (1593, loc, "Delegate `{0}' does not take `{1}' arguments",
4878                                         DelegateType.GetSignatureForError (), arg_count.ToString ());
4879                         } else {
4880                                 string name = best_candidate.Kind == MemberKind.Indexer ? "this" : best_candidate.Name;
4881                                 rc.Report.SymbolRelatedToPreviousError (best_candidate);
4882                                 rc.Report.Error (1501, loc, "No overload for method `{0}' takes `{1}' arguments",
4883                                         name, arg_count.ToString ());
4884                         }
4885                 }
4886
4887                 bool VerifyArguments (ResolveContext ec, ref Arguments args, MemberSpec member, IParametersMember pm, bool chose_params_expanded)
4888                 {
4889                         var pd = pm.Parameters;
4890                         TypeSpec[] ptypes = ((IParametersMember) member).Parameters.Types;
4891
4892                         Parameter.Modifier p_mod = 0;
4893                         TypeSpec pt = null;
4894                         int a_idx = 0, a_pos = 0;
4895                         Argument a = null;
4896                         ArrayInitializer params_initializers = null;
4897                         bool has_unsafe_arg = pm.MemberType.IsPointer;
4898                         int arg_count = args == null ? 0 : args.Count;
4899
4900                         for (; a_idx < arg_count; a_idx++, ++a_pos) {
4901                                 a = args[a_idx];
4902                                 if (p_mod != Parameter.Modifier.PARAMS) {
4903                                         p_mod = pd.FixedParameters[a_idx].ModFlags;
4904                                         pt = ptypes[a_idx];
4905                                         has_unsafe_arg |= pt.IsPointer;
4906
4907                                         if (p_mod == Parameter.Modifier.PARAMS) {
4908                                                 if (chose_params_expanded) {
4909                                                         params_initializers = new ArrayInitializer (arg_count - a_idx, a.Expr.Location);
4910                                                         pt = TypeManager.GetElementType (pt);
4911                                                 }
4912                                         }
4913                                 }
4914
4915                                 //
4916                                 // Types have to be identical when ref or out modifer is used
4917                                 //
4918                                 if (((a.Modifier | p_mod) & Parameter.Modifier.RefOutMask) != 0) {
4919                                         if ((a.Modifier & Parameter.Modifier.RefOutMask) != (p_mod & Parameter.Modifier.RefOutMask))
4920                                                 break;
4921
4922                                         if (a.Expr.Type == pt || TypeSpecComparer.IsEqual (a.Expr.Type, pt))
4923                                                 continue;
4924
4925                                         break;
4926                                 }
4927
4928                                 NamedArgument na = a as NamedArgument;
4929                                 if (na != null) {
4930                                         int name_index = pd.GetParameterIndexByName (na.Name);
4931                                         if (name_index < 0 || name_index >= pd.Count) {
4932                                                 if (IsDelegateInvoke) {
4933                                                         ec.Report.SymbolRelatedToPreviousError (DelegateType);
4934                                                         ec.Report.Error (1746, na.Location,
4935                                                                 "The delegate `{0}' does not contain a parameter named `{1}'",
4936                                                                 DelegateType.GetSignatureForError (), na.Name);
4937                                                 } else {
4938                                                         ec.Report.SymbolRelatedToPreviousError (member);
4939                                                         ec.Report.Error (1739, na.Location,
4940                                                                 "The best overloaded method match for `{0}' does not contain a parameter named `{1}'",
4941                                                                 TypeManager.CSharpSignature (member), na.Name);
4942                                                 }
4943                                         } else if (args[name_index] != a) {
4944                                                 if (IsDelegateInvoke)
4945                                                         ec.Report.SymbolRelatedToPreviousError (DelegateType);
4946                                                 else
4947                                                         ec.Report.SymbolRelatedToPreviousError (member);
4948
4949                                                 ec.Report.Error (1744, na.Location,
4950                                                         "Named argument `{0}' cannot be used for a parameter which has positional argument specified",
4951                                                         na.Name);
4952                                         }
4953                                 }
4954
4955                                 if (a.Expr.Type.BuiltinType == BuiltinTypeSpec.Type.Dynamic)
4956                                         continue;
4957
4958                                 if ((restrictions & Restrictions.CovariantDelegate) != 0 && !Delegate.IsTypeCovariant (ec, a.Expr.Type, pt)) {
4959                                         custom_errors.NoArgumentMatch (ec, member);
4960                                         return false;
4961                                 }
4962
4963                                 Expression conv = null;
4964                                 if (a.ArgType == Argument.AType.ExtensionType) {
4965                                         if (a.Expr.Type == pt || TypeSpecComparer.IsEqual (a.Expr.Type, pt)) {
4966                                                 conv = a.Expr;
4967                                         } else {
4968                                                 conv = Convert.ImplicitReferenceConversion (a.Expr, pt, false);
4969                                                 if (conv == null)
4970                                                         conv = Convert.ImplicitBoxingConversion (a.Expr, a.Expr.Type, pt);
4971                                         }
4972                                 } else {
4973                                         conv = Convert.ImplicitConversion (ec, a.Expr, pt, loc);
4974                                 }
4975
4976                                 if (conv == null)
4977                                         break;
4978
4979                                 //
4980                                 // Convert params arguments to an array initializer
4981                                 //
4982                                 if (params_initializers != null) {
4983                                         // we choose to use 'a.Expr' rather than 'conv' so that
4984                                         // we don't hide the kind of expression we have (esp. CompoundAssign.Helper)
4985                                         params_initializers.Add (a.Expr);
4986                                         args.RemoveAt (a_idx--);
4987                                         --arg_count;
4988                                         continue;
4989                                 }
4990
4991                                 // Update the argument with the implicit conversion
4992                                 a.Expr = conv;
4993                         }
4994
4995                         if (a_idx != arg_count) {
4996                                 ReportArgumentMismatch (ec, a_pos, member, a, pd, pt);
4997                                 return false;
4998                         }
4999
5000                         //
5001                         // Fill not provided arguments required by params modifier
5002                         //
5003                         if (params_initializers == null && pd.HasParams && arg_count + 1 == pd.Count) {
5004                                 if (args == null)
5005                                         args = new Arguments (1);
5006
5007                                 pt = ptypes[pd.Count - 1];
5008                                 pt = TypeManager.GetElementType (pt);
5009                                 has_unsafe_arg |= pt.IsPointer;
5010                                 params_initializers = new ArrayInitializer (0, loc);
5011                         }
5012
5013                         //
5014                         // Append an array argument with all params arguments
5015                         //
5016                         if (params_initializers != null) {
5017                                 args.Add (new Argument (
5018                                         new ArrayCreation (new TypeExpression (pt, loc), params_initializers, loc).Resolve (ec)));
5019                                 arg_count++;
5020                         }
5021
5022                         if (has_unsafe_arg && !ec.IsUnsafe) {
5023                                 Expression.UnsafeError (ec, loc);
5024                         }
5025
5026                         //
5027                         // We could infer inaccesible type arguments
5028                         //
5029                         if (type_arguments == null && member.IsGeneric) {
5030                                 var ms = (MethodSpec) member;
5031                                 foreach (var ta in ms.TypeArguments) {
5032                                         if (!ta.IsAccessible (ec)) {
5033                                                 ec.Report.SymbolRelatedToPreviousError (ta);
5034                                                 Expression.ErrorIsInaccesible (ec, member.GetSignatureForError (), loc);
5035                                                 break;
5036                                         }
5037                                 }
5038                         }
5039
5040                         return true;
5041                 }
5042         }
5043
5044         public class ConstantExpr : MemberExpr
5045         {
5046                 readonly ConstSpec constant;
5047
5048                 public ConstantExpr (ConstSpec constant, Location loc)
5049                 {
5050                         this.constant = constant;
5051                         this.loc = loc;
5052                 }
5053
5054                 public override string Name {
5055                         get { throw new NotImplementedException (); }
5056                 }
5057
5058                 public override string KindName {
5059                         get { return "constant"; }
5060                 }
5061
5062                 public override bool IsInstance {
5063                         get { return !IsStatic; }
5064                 }
5065
5066                 public override bool IsStatic {
5067                         get { return true; }
5068                 }
5069
5070                 protected override TypeSpec DeclaringType {
5071                         get { return constant.DeclaringType; }
5072                 }
5073
5074                 public override Expression CreateExpressionTree (ResolveContext ec)
5075                 {
5076                         throw new NotSupportedException ("ET");
5077                 }
5078
5079                 protected override Expression DoResolve (ResolveContext rc)
5080                 {
5081                         ResolveInstanceExpression (rc, null);
5082                         DoBestMemberChecks (rc, constant);
5083
5084                         var c = constant.GetConstant (rc);
5085
5086                         // Creates reference expression to the constant value
5087                         return Constant.CreateConstant (constant.MemberType, c.GetValue (), loc);
5088                 }
5089
5090                 public override void Emit (EmitContext ec)
5091                 {
5092                         throw new NotSupportedException ();
5093                 }
5094
5095                 public override string GetSignatureForError ()
5096                 {
5097                         return constant.GetSignatureForError ();
5098                 }
5099
5100                 public override void SetTypeArguments (ResolveContext ec, TypeArguments ta)
5101                 {
5102                         Error_TypeArgumentsCannotBeUsed (ec, "constant", GetSignatureForError (), loc);
5103                 }
5104         }
5105
5106         //
5107         // Fully resolved expression that references a Field
5108         //
5109         public class FieldExpr : MemberExpr, IDynamicAssign, IMemoryLocation, IVariableReference
5110         {
5111                 protected FieldSpec spec;
5112                 VariableInfo variable_info;
5113
5114                 LocalTemporary temp;
5115                 bool prepared;
5116
5117                 protected FieldExpr (Location l)
5118                 {
5119                         loc = l;
5120                 }
5121
5122                 public FieldExpr (FieldSpec spec, Location loc)
5123                 {
5124                         this.spec = spec;
5125                         this.loc = loc;
5126
5127                         type = spec.MemberType;
5128                 }
5129
5130                 public FieldExpr (FieldBase fi, Location l)
5131                         : this (fi.Spec, l)
5132                 {
5133                 }
5134
5135                 #region Properties
5136
5137                 public override string Name {
5138                         get {
5139                                 return spec.Name;
5140                         }
5141                 }
5142
5143                 public bool IsHoisted {
5144                         get {
5145                                 IVariableReference hv = InstanceExpression as IVariableReference;
5146                                 return hv != null && hv.IsHoisted;
5147                         }
5148                 }
5149
5150                 public override bool IsInstance {
5151                         get {
5152                                 return !spec.IsStatic;
5153                         }
5154                 }
5155
5156                 public override bool IsStatic {
5157                         get {
5158                                 return spec.IsStatic;
5159                         }
5160                 }
5161
5162                 public override string KindName {
5163                         get { return "field"; }
5164                 }
5165
5166                 public FieldSpec Spec {
5167                         get {
5168                                 return spec;
5169                         }
5170                 }
5171
5172                 protected override TypeSpec DeclaringType {
5173                         get {
5174                                 return spec.DeclaringType;
5175                         }
5176                 }
5177
5178                 public VariableInfo VariableInfo {
5179                         get {
5180                                 return variable_info;
5181                         }
5182                 }
5183
5184 #endregion
5185
5186                 public override string GetSignatureForError ()
5187                 {
5188                         return spec.GetSignatureForError ();
5189                 }
5190
5191                 public bool IsMarshalByRefAccess (ResolveContext rc)
5192                 {
5193                         // Checks possible ldflda of field access expression
5194                         return !spec.IsStatic && TypeSpec.IsValueType (spec.MemberType) && !(InstanceExpression is This) &&
5195                                 rc.Module.PredefinedTypes.MarshalByRefObject.Define () &&
5196                                 TypeSpec.IsBaseClass (spec.DeclaringType, rc.Module.PredefinedTypes.MarshalByRefObject.TypeSpec, false);
5197                 }
5198
5199                 public void SetHasAddressTaken ()
5200                 {
5201                         IVariableReference vr = InstanceExpression as IVariableReference;
5202                         if (vr != null) {
5203                                 vr.SetHasAddressTaken ();
5204                         }
5205                 }
5206
5207                 public override Expression CreateExpressionTree (ResolveContext ec)
5208                 {
5209                         Expression instance;
5210                         if (InstanceExpression == null) {
5211                                 instance = new NullLiteral (loc);
5212                         } else {
5213                                 instance = InstanceExpression.CreateExpressionTree (ec);
5214                         }
5215
5216                         Arguments args = Arguments.CreateForExpressionTree (ec, null,
5217                                 instance,
5218                                 CreateTypeOfExpression ());
5219
5220                         return CreateExpressionFactoryCall (ec, "Field", args);
5221                 }
5222
5223                 public Expression CreateTypeOfExpression ()
5224                 {
5225                         return new TypeOfField (spec, loc);
5226                 }
5227
5228                 protected override Expression DoResolve (ResolveContext ec)
5229                 {
5230                         return DoResolve (ec, null);
5231                 }
5232
5233                 Expression DoResolve (ResolveContext ec, Expression rhs)
5234                 {
5235                         bool lvalue_instance = rhs != null && IsInstance && spec.DeclaringType.IsStruct;
5236
5237                         if (rhs != this) {
5238                                 if (ResolveInstanceExpression (ec, rhs)) {
5239                                         // Resolve the field's instance expression while flow analysis is turned
5240                                         // off: when accessing a field "a.b", we must check whether the field
5241                                         // "a.b" is initialized, not whether the whole struct "a" is initialized.
5242
5243                                         if (lvalue_instance) {
5244                                                 using (ec.With (ResolveContext.Options.DoFlowAnalysis, false)) {
5245                                                         bool out_access = rhs == EmptyExpression.OutAccess || rhs == EmptyExpression.LValueMemberOutAccess;
5246
5247                                                         Expression right_side =
5248                                                                 out_access ? EmptyExpression.LValueMemberOutAccess : EmptyExpression.LValueMemberAccess;
5249
5250                                                         InstanceExpression = InstanceExpression.ResolveLValue (ec, right_side);
5251                                                 }
5252                                         } else {
5253                                                 using (ec.With (ResolveContext.Options.DoFlowAnalysis, false)) {
5254                                                         InstanceExpression = InstanceExpression.Resolve (ec, ResolveFlags.VariableOrValue);
5255                                                 }
5256                                         }
5257
5258                                         if (InstanceExpression == null)
5259                                                 return null;
5260                                 }
5261
5262                                 DoBestMemberChecks (ec, spec);
5263                         }
5264
5265                         var fb = spec as FixedFieldSpec;
5266                         IVariableReference var = InstanceExpression as IVariableReference;
5267
5268                         if (lvalue_instance && var != null && var.VariableInfo != null) {
5269                                 var.VariableInfo.SetStructFieldAssigned (ec, Name);
5270                         }
5271
5272                         if (fb != null) {
5273                                 IFixedExpression fe = InstanceExpression as IFixedExpression;
5274                                 if (!ec.HasSet (ResolveContext.Options.FixedInitializerScope) && (fe == null || !fe.IsFixed)) {
5275                                         ec.Report.Error (1666, loc, "You cannot use fixed size buffers contained in unfixed expressions. Try using the fixed statement");
5276                                 }
5277
5278                                 if (InstanceExpression.eclass != ExprClass.Variable) {
5279                                         ec.Report.SymbolRelatedToPreviousError (spec);
5280                                         ec.Report.Error (1708, loc, "`{0}': Fixed size buffers can only be accessed through locals or fields",
5281                                                 TypeManager.GetFullNameSignature (spec));
5282                                 } else if (var != null && var.IsHoisted) {
5283                                         AnonymousMethodExpression.Error_AddressOfCapturedVar (ec, var, loc);
5284                                 }
5285
5286                                 return new FixedBufferPtr (this, fb.ElementType, loc).Resolve (ec);
5287                         }
5288
5289                         //
5290                         // Set flow-analysis variable info for struct member access. It will be check later
5291                         // for precise error reporting
5292                         //
5293                         if (var != null && var.VariableInfo != null && InstanceExpression.Type.IsStruct) {
5294                                 variable_info = var.VariableInfo.GetStructFieldInfo (Name);
5295                                 if (rhs != null && variable_info != null)
5296                                         variable_info.SetStructFieldAssigned (ec, Name);
5297                         }
5298
5299                         eclass = ExprClass.Variable;
5300                         return this;
5301                 }
5302
5303                 public void VerifyAssignedStructField (ResolveContext rc, Expression rhs)
5304                 {
5305                         var fe = this;
5306
5307                         do {
5308                                 var var = fe.InstanceExpression as IVariableReference;
5309                                 if (var != null) {
5310                                         var vi = var.VariableInfo;
5311
5312                                         if (vi != null && !vi.IsStructFieldAssigned (rc, fe.Name) && (rhs == null || !fe.type.IsStruct)) {
5313                                                 if (rhs != null) {
5314                                                         rc.Report.Warning (1060, 1, fe.loc, "Use of possibly unassigned field `{0}'", fe.Name);
5315                                                 } else {
5316                                                         rc.Report.Error (170, fe.loc, "Use of possibly unassigned field `{0}'", fe.Name);
5317                                                 }
5318
5319                                                 return;
5320                                         }
5321                                 }
5322
5323                                 fe = fe.InstanceExpression as FieldExpr;
5324
5325                         } while (fe != null);
5326                 }
5327
5328                 static readonly int [] codes = {
5329                         191,    // instance, write access
5330                         192,    // instance, out access
5331                         198,    // static, write access
5332                         199,    // static, out access
5333                         1648,   // member of value instance, write access
5334                         1649,   // member of value instance, out access
5335                         1650,   // member of value static, write access
5336                         1651    // member of value static, out access
5337                 };
5338
5339                 static readonly string [] msgs = {
5340                         /*0191*/ "A readonly field `{0}' cannot be assigned to (except in a constructor or a variable initializer)",
5341                         /*0192*/ "A readonly field `{0}' cannot be passed ref or out (except in a constructor)",
5342                         /*0198*/ "A static readonly field `{0}' cannot be assigned to (except in a static constructor or a variable initializer)",
5343                         /*0199*/ "A static readonly field `{0}' cannot be passed ref or out (except in a static constructor)",
5344                         /*1648*/ "Members of readonly field `{0}' cannot be modified (except in a constructor or a variable initializer)",
5345                         /*1649*/ "Members of readonly field `{0}' cannot be passed ref or out (except in a constructor)",
5346                         /*1650*/ "Fields of static readonly field `{0}' cannot be assigned to (except in a static constructor or a variable initializer)",
5347                         /*1651*/ "Fields of static readonly field `{0}' cannot be passed ref or out (except in a static constructor)"
5348                 };
5349
5350                 // The return value is always null.  Returning a value simplifies calling code.
5351                 Expression Report_AssignToReadonly (ResolveContext ec, Expression right_side)
5352                 {
5353                         int i = 0;
5354                         if (right_side == EmptyExpression.OutAccess || right_side == EmptyExpression.LValueMemberOutAccess)
5355                                 i += 1;
5356                         if (IsStatic)
5357                                 i += 2;
5358                         if (right_side == EmptyExpression.LValueMemberAccess || right_side == EmptyExpression.LValueMemberOutAccess)
5359                                 i += 4;
5360                         ec.Report.Error (codes [i], loc, msgs [i], GetSignatureForError ());
5361
5362                         return null;
5363                 }
5364
5365                 override public Expression DoResolveLValue (ResolveContext ec, Expression right_side)
5366                 {
5367                         Expression e = DoResolve (ec, right_side);
5368
5369                         if (e == null)
5370                                 return null;
5371
5372                         spec.MemberDefinition.SetIsAssigned ();
5373
5374                         if ((right_side == EmptyExpression.UnaryAddress || right_side == EmptyExpression.OutAccess) &&
5375                                         (spec.Modifiers & Modifiers.VOLATILE) != 0) {
5376                                 ec.Report.Warning (420, 1, loc,
5377                                         "`{0}': A volatile field references will not be treated as volatile",
5378                                         spec.GetSignatureForError ());
5379                         }
5380
5381                         if (spec.IsReadOnly) {
5382                                 // InitOnly fields can only be assigned in constructors or initializers
5383                                 if (!ec.HasAny (ResolveContext.Options.FieldInitializerScope | ResolveContext.Options.ConstructorScope))
5384                                         return Report_AssignToReadonly (ec, right_side);
5385
5386                                 if (ec.HasSet (ResolveContext.Options.ConstructorScope)) {
5387
5388                                         // InitOnly fields cannot be assigned-to in a different constructor from their declaring type
5389                                         if (ec.CurrentMemberDefinition.Parent.PartialContainer.Definition != spec.DeclaringType.GetDefinition ())
5390                                                 return Report_AssignToReadonly (ec, right_side);
5391                                         // static InitOnly fields cannot be assigned-to in an instance constructor
5392                                         if (IsStatic && !ec.IsStatic)
5393                                                 return Report_AssignToReadonly (ec, right_side);
5394                                         // instance constructors can't modify InitOnly fields of other instances of the same type
5395                                         if (!IsStatic && !(InstanceExpression is This))
5396                                                 return Report_AssignToReadonly (ec, right_side);
5397                                 }
5398                         }
5399
5400                         if (right_side == EmptyExpression.OutAccess && IsMarshalByRefAccess (ec)) {
5401                                 ec.Report.SymbolRelatedToPreviousError (spec.DeclaringType);
5402                                 ec.Report.Warning (197, 1, loc,
5403                                                 "Passing `{0}' as ref or out or taking its address may cause a runtime exception because it is a field of a marshal-by-reference class",
5404                                                 GetSignatureForError ());
5405                         }
5406
5407                         eclass = ExprClass.Variable;
5408                         return this;
5409                 }
5410
5411                 public override int GetHashCode ()
5412                 {
5413                         return spec.GetHashCode ();
5414                 }
5415
5416                 public bool IsFixed {
5417                         get {
5418                                 //
5419                                 // A variable of the form V.I is fixed when V is a fixed variable of a struct type
5420                                 //
5421                                 IVariableReference variable = InstanceExpression as IVariableReference;
5422                                 if (variable != null)
5423                                         return InstanceExpression.Type.IsStruct && variable.IsFixed;
5424
5425                                 IFixedExpression fe = InstanceExpression as IFixedExpression;
5426                                 return fe != null && fe.IsFixed;
5427                         }
5428                 }
5429
5430                 public override bool Equals (object obj)
5431                 {
5432                         FieldExpr fe = obj as FieldExpr;
5433                         if (fe == null)
5434                                 return false;
5435
5436                         if (spec != fe.spec)
5437                                 return false;
5438
5439                         if (InstanceExpression == null || fe.InstanceExpression == null)
5440                                 return true;
5441
5442                         return InstanceExpression.Equals (fe.InstanceExpression);
5443                 }
5444
5445                 public void Emit (EmitContext ec, bool leave_copy)
5446                 {
5447                         bool is_volatile = (spec.Modifiers & Modifiers.VOLATILE) != 0;
5448
5449                         spec.MemberDefinition.SetIsUsed ();
5450
5451                         if (IsStatic){
5452                                 if (is_volatile)
5453                                         ec.Emit (OpCodes.Volatile);
5454
5455                                 ec.Emit (OpCodes.Ldsfld, spec);
5456                         } else {
5457                                 if (!prepared)
5458                                         EmitInstance (ec, false);
5459
5460                                 // Optimization for build-in types
5461                                 if (type.IsStruct && type == ec.CurrentType && InstanceExpression.Type == type) {
5462                                         ec.EmitLoadFromPtr (type);
5463                                 } else {
5464                                         var ff = spec as FixedFieldSpec;
5465                                         if (ff != null) {
5466                                                 ec.Emit (OpCodes.Ldflda, spec);
5467                                                 ec.Emit (OpCodes.Ldflda, ff.Element);
5468                                         } else {
5469                                                 if (is_volatile)
5470                                                         ec.Emit (OpCodes.Volatile);
5471
5472                                                 ec.Emit (OpCodes.Ldfld, spec);
5473                                         }
5474                                 }
5475                         }
5476
5477                         if (leave_copy) {
5478                                 ec.Emit (OpCodes.Dup);
5479                                 if (!IsStatic) {
5480                                         temp = new LocalTemporary (this.Type);
5481                                         temp.Store (ec);
5482                                 }
5483                         }
5484                 }
5485
5486                 public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool isCompound)
5487                 {
5488                         bool has_await_source = ec.HasSet (BuilderContext.Options.AsyncBody) && source.ContainsEmitWithAwait ();
5489                         if (isCompound && !(source is DynamicExpressionStatement)) {
5490                                 if (has_await_source) {
5491                                         if (IsInstance)
5492                                                 InstanceExpression = InstanceExpression.EmitToField (ec);
5493                                 } else {
5494                                         prepared = true;
5495                                 }
5496                         }
5497
5498                         if (IsInstance) {
5499                                 if (has_await_source)
5500                                         source = source.EmitToField (ec);
5501
5502                                 EmitInstance (ec, prepared);
5503                         }
5504
5505                         source.Emit (ec);
5506
5507                         if (leave_copy) {
5508                                 ec.Emit (OpCodes.Dup);
5509                                 if (!IsStatic) {
5510                                         temp = new LocalTemporary (this.Type);
5511                                         temp.Store (ec);
5512                                 }
5513                         }
5514
5515                         if ((spec.Modifiers & Modifiers.VOLATILE) != 0)
5516                                 ec.Emit (OpCodes.Volatile);
5517
5518                         spec.MemberDefinition.SetIsAssigned ();
5519
5520                         if (IsStatic)
5521                                 ec.Emit (OpCodes.Stsfld, spec);
5522                         else
5523                                 ec.Emit (OpCodes.Stfld, spec);
5524
5525                         if (temp != null) {
5526                                 temp.Emit (ec);
5527                                 temp.Release (ec);
5528                                 temp = null;
5529                         }
5530                 }
5531
5532                 //
5533                 // Emits store to field with prepared values on stack
5534                 //
5535                 public void EmitAssignFromStack (EmitContext ec)
5536                 {
5537                         if (IsStatic) {
5538                                 ec.Emit (OpCodes.Stsfld, spec);
5539                         } else {
5540                                 ec.Emit (OpCodes.Stfld, spec);
5541                         }
5542                 }
5543
5544                 public override void Emit (EmitContext ec)
5545                 {
5546                         Emit (ec, false);
5547                 }
5548
5549                 public override void EmitSideEffect (EmitContext ec)
5550                 {
5551                         bool is_volatile = (spec.Modifiers & Modifiers.VOLATILE) != 0;
5552
5553                         if (is_volatile) // || is_marshal_by_ref ())
5554                                 base.EmitSideEffect (ec);
5555                 }
5556
5557                 public virtual void AddressOf (EmitContext ec, AddressOp mode)
5558                 {
5559                         if ((mode & AddressOp.Store) != 0)
5560                                 spec.MemberDefinition.SetIsAssigned ();
5561                         if ((mode & AddressOp.Load) != 0)
5562                                 spec.MemberDefinition.SetIsUsed ();
5563
5564                         //
5565                         // Handle initonly fields specially: make a copy and then
5566                         // get the address of the copy.
5567                         //
5568                         bool need_copy;
5569                         if (spec.IsReadOnly){
5570                                 need_copy = true;
5571                                 if (ec.HasSet (EmitContext.Options.ConstructorScope) && spec.DeclaringType == ec.CurrentType) {
5572                                         if (IsStatic){
5573                                                 if (ec.IsStatic)
5574                                                         need_copy = false;
5575                                         } else
5576                                                 need_copy = false;
5577                                 }
5578                         } else
5579                                 need_copy = false;
5580
5581                         if (need_copy) {
5582                                 Emit (ec);
5583                                 var temp = ec.GetTemporaryLocal (type);
5584                                 ec.Emit (OpCodes.Stloc, temp);
5585                                 ec.Emit (OpCodes.Ldloca, temp);
5586                                 ec.FreeTemporaryLocal (temp, type);
5587                                 return;
5588                         }
5589
5590
5591                         if (IsStatic){
5592                                 ec.Emit (OpCodes.Ldsflda, spec);
5593                         } else {
5594                                 if (!prepared)
5595                                         EmitInstance (ec, false);
5596                                 ec.Emit (OpCodes.Ldflda, spec);
5597                         }
5598                 }
5599
5600                 public SLE.Expression MakeAssignExpression (BuilderContext ctx, Expression source)
5601                 {
5602                         return MakeExpression (ctx);
5603                 }
5604
5605                 public override SLE.Expression MakeExpression (BuilderContext ctx)
5606                 {
5607 #if STATIC
5608                         return base.MakeExpression (ctx);
5609 #else
5610                         return SLE.Expression.Field (
5611                                 IsStatic ? null : InstanceExpression.MakeExpression (ctx),
5612                                 spec.GetMetaInfo ());
5613 #endif
5614                 }
5615
5616                 public override void SetTypeArguments (ResolveContext ec, TypeArguments ta)
5617                 {
5618                         Error_TypeArgumentsCannotBeUsed (ec, "field", GetSignatureForError (), loc);
5619                 }
5620         }
5621
5622
5623         //
5624         // Expression that evaluates to a Property.
5625         //
5626         // This is not an LValue because we need to re-write the expression. We
5627         // can not take data from the stack and store it.
5628         //
5629         sealed class PropertyExpr : PropertyOrIndexerExpr<PropertySpec>
5630         {
5631                 public PropertyExpr (PropertySpec spec, Location l)
5632                         : base (l)
5633                 {
5634                         best_candidate = spec;
5635                         type = spec.MemberType;
5636                 }
5637
5638                 #region Properties
5639
5640                 protected override Arguments Arguments {
5641                         get {
5642                                 return null;
5643                         }
5644                         set {
5645                         }
5646                 }
5647
5648                 protected override TypeSpec DeclaringType {
5649                         get {
5650                                 return best_candidate.DeclaringType;
5651                         }
5652                 }
5653
5654                 public override string Name {
5655                         get {
5656                                 return best_candidate.Name;
5657                         }
5658                 }
5659
5660                 public override bool IsInstance {
5661                         get {
5662                                 return !IsStatic;
5663                         }
5664                 }
5665
5666                 public override bool IsStatic {
5667                         get {
5668                                 return best_candidate.IsStatic;
5669                         }
5670                 }
5671
5672                 public override string KindName {
5673                         get { return "property"; }
5674                 }
5675
5676                 public PropertySpec PropertyInfo {
5677                         get {
5678                                 return best_candidate;
5679                         }
5680                 }
5681
5682                 #endregion
5683
5684                 public static PropertyExpr CreatePredefined (PropertySpec spec, Location loc)
5685                 {
5686                         return new PropertyExpr (spec, loc) {
5687                                 Getter = spec.Get,
5688                                 Setter = spec.Set
5689                         };
5690                 }
5691
5692                 public override Expression CreateExpressionTree (ResolveContext ec)
5693                 {
5694                         Arguments args;
5695                         if (IsSingleDimensionalArrayLength ()) {
5696                                 args = new Arguments (1);
5697                                 args.Add (new Argument (InstanceExpression.CreateExpressionTree (ec)));
5698                                 return CreateExpressionFactoryCall (ec, "ArrayLength", args);
5699                         }
5700
5701                         args = new Arguments (2);
5702                         if (InstanceExpression == null)
5703                                 args.Add (new Argument (new NullLiteral (loc)));
5704                         else
5705                                 args.Add (new Argument (InstanceExpression.CreateExpressionTree (ec)));
5706                         args.Add (new Argument (new TypeOfMethod (Getter, loc)));
5707                         return CreateExpressionFactoryCall (ec, "Property", args);
5708                 }
5709
5710                 public Expression CreateSetterTypeOfExpression (ResolveContext rc)
5711                 {
5712                         DoResolveLValue (rc, null);
5713                         return new TypeOfMethod (Setter, loc);
5714                 }
5715
5716                 public override string GetSignatureForError ()
5717                 {
5718                         return best_candidate.GetSignatureForError ();
5719                 }
5720
5721                 public override SLE.Expression MakeAssignExpression (BuilderContext ctx, Expression source)
5722                 {
5723 #if STATIC
5724                         return base.MakeExpression (ctx);
5725 #else
5726                         return SLE.Expression.Property (InstanceExpression.MakeExpression (ctx), (MethodInfo) Setter.GetMetaInfo ());
5727 #endif
5728                 }
5729
5730                 public override SLE.Expression MakeExpression (BuilderContext ctx)
5731                 {
5732 #if STATIC
5733                         return base.MakeExpression (ctx);
5734 #else
5735                         return SLE.Expression.Property (InstanceExpression.MakeExpression (ctx), (MethodInfo) Getter.GetMetaInfo ());
5736 #endif
5737                 }
5738
5739                 void Error_PropertyNotValid (ResolveContext ec)
5740                 {
5741                         ec.Report.SymbolRelatedToPreviousError (best_candidate);
5742                         ec.Report.Error (1546, loc, "Property or event `{0}' is not supported by the C# language",
5743                                 GetSignatureForError ());
5744                 }
5745
5746                 bool IsSingleDimensionalArrayLength ()
5747                 {
5748                         if (best_candidate.DeclaringType.BuiltinType != BuiltinTypeSpec.Type.Array || !best_candidate.HasGet || Name != "Length")
5749                                 return false;
5750
5751                         ArrayContainer ac = InstanceExpression.Type as ArrayContainer;
5752                         return ac != null && ac.Rank == 1;
5753                 }
5754
5755                 public override void Emit (EmitContext ec, bool leave_copy)
5756                 {
5757                         //
5758                         // Special case: length of single dimension array property is turned into ldlen
5759                         //
5760                         if (IsSingleDimensionalArrayLength ()) {
5761                                 EmitInstance (ec, false);
5762                                 ec.Emit (OpCodes.Ldlen);
5763                                 ec.Emit (OpCodes.Conv_I4);
5764                                 return;
5765                         }
5766
5767                         base.Emit (ec, leave_copy);
5768                 }
5769
5770                 public override void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool isCompound)
5771                 {
5772                         Arguments args;
5773                         LocalTemporary await_source_arg = null;
5774
5775                         if (isCompound && !(source is DynamicExpressionStatement)) {
5776                                 emitting_compound_assignment = true;
5777                                 source.Emit (ec);
5778
5779                                 if (has_await_arguments) {
5780                                         await_source_arg = new LocalTemporary (Type);
5781                                         await_source_arg.Store (ec);
5782
5783                                         args = new Arguments (1);
5784                                         args.Add (new Argument (await_source_arg));
5785
5786                                         if (leave_copy) {
5787                                                 temp = await_source_arg;
5788                                         }
5789
5790                                         has_await_arguments = false;
5791                                 } else {
5792                                         args = null;
5793
5794                                         if (leave_copy) {
5795                                                 ec.Emit (OpCodes.Dup);
5796                                                 temp = new LocalTemporary (this.Type);
5797                                                 temp.Store (ec);
5798                                         }
5799                                 }
5800                         } else {
5801                                 args = new Arguments (1);
5802
5803                                 if (leave_copy) {
5804                                         source.Emit (ec);
5805                                         temp = new LocalTemporary (this.Type);
5806                                         temp.Store (ec);
5807                                         args.Add (new Argument (temp));
5808                                 } else {
5809                                         args.Add (new Argument (source));
5810                                 }
5811                         }
5812
5813                         emitting_compound_assignment = false;
5814
5815                         var call = new CallEmitter ();
5816                         call.InstanceExpression = InstanceExpression;
5817                         if (args == null)
5818                                 call.InstanceExpressionOnStack = true;
5819
5820                         call.Emit (ec, Setter, args, loc);
5821
5822                         if (temp != null) {
5823                                 temp.Emit (ec);
5824                                 temp.Release (ec);
5825                         }
5826
5827                         if (await_source_arg != null) {
5828                                 await_source_arg.Release (ec);
5829                         }
5830                 }
5831
5832                 protected override Expression OverloadResolve (ResolveContext rc, Expression right_side)
5833                 {
5834                         eclass = ExprClass.PropertyAccess;
5835
5836                         if (best_candidate.IsNotCSharpCompatible) {
5837                                 Error_PropertyNotValid (rc);
5838                         }
5839
5840                         ResolveInstanceExpression (rc, right_side);
5841
5842                         if ((best_candidate.Modifiers & (Modifiers.ABSTRACT | Modifiers.VIRTUAL)) != 0 && best_candidate.DeclaringType != InstanceExpression.Type) {
5843                                 var filter = new MemberFilter (best_candidate.Name, 0, MemberKind.Property, null, null);
5844                                 var p = MemberCache.FindMember (InstanceExpression.Type, filter, BindingRestriction.InstanceOnly | BindingRestriction.OverrideOnly) as PropertySpec;
5845                                 if (p != null) {
5846                                         type = p.MemberType;
5847                                 }
5848                         }
5849
5850                         DoBestMemberChecks (rc, best_candidate);
5851                         return this;
5852                 }
5853
5854                 public override void SetTypeArguments (ResolveContext ec, TypeArguments ta)
5855                 {
5856                         Error_TypeArgumentsCannotBeUsed (ec, "property", GetSignatureForError (), loc);
5857                 }
5858         }
5859
5860         abstract class PropertyOrIndexerExpr<T> : MemberExpr, IDynamicAssign where T : PropertySpec
5861         {
5862                 // getter and setter can be different for base calls
5863                 MethodSpec getter, setter;
5864                 protected T best_candidate;
5865
5866                 protected LocalTemporary temp;
5867                 protected bool emitting_compound_assignment;
5868                 protected bool has_await_arguments;
5869
5870                 protected PropertyOrIndexerExpr (Location l)
5871                 {
5872                         loc = l;
5873                 }
5874
5875                 #region Properties
5876
5877                 protected abstract Arguments Arguments { get; set; }
5878
5879                 public MethodSpec Getter {
5880                         get {
5881                                 return getter;
5882                         }
5883                         set {
5884                                 getter = value;
5885                         }
5886                 }
5887
5888                 public MethodSpec Setter {
5889                         get {
5890                                 return setter;
5891                         }
5892                         set {
5893                                 setter = value;
5894                         }
5895                 }
5896
5897                 #endregion
5898
5899                 protected override Expression DoResolve (ResolveContext ec)
5900                 {
5901                         if (eclass == ExprClass.Unresolved) {
5902                                 var expr = OverloadResolve (ec, null);
5903                                 if (expr == null)
5904                                         return null;
5905
5906                                 if (expr != this)
5907                                         return expr.Resolve (ec);
5908                         }
5909
5910                         if (!ResolveGetter (ec))
5911                                 return null;
5912
5913                         return this;
5914                 }
5915
5916                 public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
5917                 {
5918                         if (right_side == EmptyExpression.OutAccess) {
5919                                 // TODO: best_candidate can be null at this point
5920                                 INamedBlockVariable variable = null;
5921                                 if (best_candidate != null && ec.CurrentBlock.ParametersBlock.TopBlock.GetLocalName (best_candidate.Name, ec.CurrentBlock, ref variable) && variable is Linq.RangeVariable) {
5922                                         ec.Report.Error (1939, loc, "A range variable `{0}' may not be passes as `ref' or `out' parameter",
5923                                                 best_candidate.Name);
5924                                 } else {
5925                                         right_side.DoResolveLValue (ec, this);
5926                                 }
5927                                 return null;
5928                         }
5929
5930                         // if the property/indexer returns a value type, and we try to set a field in it
5931                         if (right_side == EmptyExpression.LValueMemberAccess || right_side == EmptyExpression.LValueMemberOutAccess) {
5932                                 Error_ValueAssignment (ec, right_side);
5933                         }
5934
5935                         if (eclass == ExprClass.Unresolved) {
5936                                 var expr = OverloadResolve (ec, right_side);
5937                                 if (expr == null)
5938                                         return null;
5939
5940                                 if (expr != this)
5941                                         return expr.ResolveLValue (ec, right_side);
5942                         }
5943
5944                         if (!ResolveSetter (ec))
5945                                 return null;
5946
5947                         return this;
5948                 }
5949
5950                 //
5951                 // Implements the IAssignMethod interface for assignments
5952                 //
5953                 public virtual void Emit (EmitContext ec, bool leave_copy)
5954                 {
5955                         var call = new CallEmitter ();
5956                         call.InstanceExpression = InstanceExpression;
5957                         if (has_await_arguments)
5958                                 call.HasAwaitArguments = true;
5959                         else
5960                                 call.DuplicateArguments = emitting_compound_assignment;
5961
5962                         call.Emit (ec, Getter, Arguments, loc);
5963
5964                         if (call.HasAwaitArguments) {
5965                                 InstanceExpression = call.InstanceExpression;
5966                                 Arguments = call.EmittedArguments;
5967                                 has_await_arguments = true;
5968                         }
5969
5970                         if (leave_copy) {
5971                                 ec.Emit (OpCodes.Dup);
5972                                 temp = new LocalTemporary (Type);
5973                                 temp.Store (ec);
5974                         }
5975                 }
5976
5977                 public abstract void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool isCompound);
5978
5979                 public override void Emit (EmitContext ec)
5980                 {
5981                         Emit (ec, false);
5982                 }
5983
5984                 protected override FieldExpr EmitToFieldSource (EmitContext ec)
5985                 {
5986                         has_await_arguments = true;
5987                         Emit (ec, false);
5988                         return null;
5989                 }
5990
5991                 public abstract SLE.Expression MakeAssignExpression (BuilderContext ctx, Expression source);
5992
5993                 protected abstract Expression OverloadResolve (ResolveContext rc, Expression right_side);
5994
5995                 bool ResolveGetter (ResolveContext rc)
5996                 {
5997                         if (!best_candidate.HasGet) {
5998                                 if (InstanceExpression != EmptyExpression.Null) {
5999                                         rc.Report.SymbolRelatedToPreviousError (best_candidate);
6000                                         rc.Report.Error (154, loc, "The property or indexer `{0}' cannot be used in this context because it lacks the `get' accessor",
6001                                                 best_candidate.GetSignatureForError ());
6002                                         return false;
6003                                 }
6004                         } else if (!best_candidate.Get.IsAccessible (rc)) {
6005                                 if (best_candidate.HasDifferentAccessibility) {
6006                                         rc.Report.SymbolRelatedToPreviousError (best_candidate.Get);
6007                                         rc.Report.Error (271, loc, "The property or indexer `{0}' cannot be used in this context because the get accessor is inaccessible",
6008                                                 TypeManager.CSharpSignature (best_candidate));
6009                                 } else {
6010                                         rc.Report.SymbolRelatedToPreviousError (best_candidate.Get);
6011                                         ErrorIsInaccesible (rc, best_candidate.Get.GetSignatureForError (), loc);
6012                                 }
6013                         }
6014
6015                         if (best_candidate.HasDifferentAccessibility) {
6016                                 CheckProtectedMemberAccess (rc, best_candidate.Get);
6017                         }
6018
6019                         getter = CandidateToBaseOverride (rc, best_candidate.Get);
6020                         return true;
6021                 }
6022
6023                 bool ResolveSetter (ResolveContext rc)
6024                 {
6025                         if (!best_candidate.HasSet) {
6026                                 rc.Report.Error (200, loc, "Property or indexer `{0}' cannot be assigned to (it is read-only)",
6027                                         GetSignatureForError ());
6028                                 return false;
6029                         }
6030
6031                         if (!best_candidate.Set.IsAccessible (rc)) {
6032                                 if (best_candidate.HasDifferentAccessibility) {
6033                                         rc.Report.SymbolRelatedToPreviousError (best_candidate.Set);
6034                                         rc.Report.Error (272, loc, "The property or indexer `{0}' cannot be used in this context because the set accessor is inaccessible",
6035                                                 GetSignatureForError ());
6036                                 } else {
6037                                         rc.Report.SymbolRelatedToPreviousError (best_candidate.Set);
6038                                         ErrorIsInaccesible (rc, best_candidate.Set.GetSignatureForError (), loc);
6039                                 }
6040                         }
6041
6042                         if (best_candidate.HasDifferentAccessibility)
6043                                 CheckProtectedMemberAccess (rc, best_candidate.Set);
6044
6045                         setter = CandidateToBaseOverride (rc, best_candidate.Set);
6046                         return true;
6047                 }
6048         }
6049
6050         /// <summary>
6051         ///   Fully resolved expression that evaluates to an Event
6052         /// </summary>
6053         public class EventExpr : MemberExpr, IAssignMethod
6054         {
6055                 readonly EventSpec spec;
6056                 MethodSpec op;
6057
6058                 public EventExpr (EventSpec spec, Location loc)
6059                 {
6060                         this.spec = spec;
6061                         this.loc = loc;
6062                 }
6063
6064                 #region Properties
6065
6066                 protected override TypeSpec DeclaringType {
6067                         get {
6068                                 return spec.DeclaringType;
6069                         }
6070                 }
6071
6072                 public override string Name {
6073                         get {
6074                                 return spec.Name;
6075                         }
6076                 }
6077
6078                 public override bool IsInstance {
6079                         get {
6080                                 return !spec.IsStatic;
6081                         }
6082                 }
6083
6084                 public override bool IsStatic {
6085                         get {
6086                                 return spec.IsStatic;
6087                         }
6088                 }
6089
6090                 public override string KindName {
6091                         get { return "event"; }
6092                 }
6093
6094                 public MethodSpec Operator {
6095                         get {
6096                                 return op;
6097                         }
6098                 }
6099
6100                 #endregion
6101
6102                 public override MemberExpr ResolveMemberAccess (ResolveContext ec, Expression left, SimpleName original)
6103                 {
6104                         //
6105                         // If the event is local to this class and we are not lhs of +=/-= we transform ourselves into a FieldExpr
6106                         //
6107                         if (!ec.HasSet (ResolveContext.Options.CompoundAssignmentScope)) {
6108                                 if (spec.BackingField != null &&
6109                                         (spec.DeclaringType == ec.CurrentType || TypeManager.IsNestedChildOf (ec.CurrentType, spec.DeclaringType.MemberDefinition))) {
6110
6111                                         spec.MemberDefinition.SetIsUsed ();
6112
6113                                         if (!ec.IsObsolete) {
6114                                                 ObsoleteAttribute oa = spec.GetAttributeObsolete ();
6115                                                 if (oa != null)
6116                                                         AttributeTester.Report_ObsoleteMessage (oa, spec.GetSignatureForError (), loc, ec.Report);
6117                                         }
6118
6119                                         if ((spec.Modifiers & (Modifiers.ABSTRACT | Modifiers.EXTERN)) != 0)
6120                                                 Error_AssignmentEventOnly (ec);
6121
6122                                         FieldExpr ml = new FieldExpr (spec.BackingField, loc);
6123
6124                                         InstanceExpression = null;
6125
6126                                         return ml.ResolveMemberAccess (ec, left, original);
6127                                 }
6128                         }
6129
6130                         return base.ResolveMemberAccess (ec, left, original);
6131                 }
6132
6133                 public override Expression CreateExpressionTree (ResolveContext ec)
6134                 {
6135                         throw new NotSupportedException ("ET");
6136                 }
6137
6138                 public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
6139                 {
6140                         if (right_side == EmptyExpression.EventAddition) {
6141                                 op = spec.AccessorAdd;
6142                         } else if (right_side == EmptyExpression.EventSubtraction) {
6143                                 op = spec.AccessorRemove;
6144                         }
6145
6146                         if (op == null) {
6147                                 Error_AssignmentEventOnly (ec);
6148                                 return null;
6149                         }
6150
6151                         op = CandidateToBaseOverride (ec, op);
6152                         return this;
6153                 }
6154
6155                 protected override Expression DoResolve (ResolveContext ec)
6156                 {
6157                         eclass = ExprClass.EventAccess;
6158                         type = spec.MemberType;
6159
6160                         ResolveInstanceExpression (ec, null);
6161
6162                         if (!ec.HasSet (ResolveContext.Options.CompoundAssignmentScope)) {
6163                                 Error_AssignmentEventOnly (ec);
6164                         }
6165
6166                         DoBestMemberChecks (ec, spec);
6167                         return this;
6168                 }
6169
6170                 public override void Emit (EmitContext ec)
6171                 {
6172                         throw new NotSupportedException ();
6173                         //Error_CannotAssign ();
6174                 }
6175
6176                 #region IAssignMethod Members
6177
6178                 public void Emit (EmitContext ec, bool leave_copy)
6179                 {
6180                         throw new NotImplementedException ();
6181                 }
6182
6183                 public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool isCompound)
6184                 {
6185                         if (leave_copy || !isCompound)
6186                                 throw new NotImplementedException ("EventExpr::EmitAssign");
6187
6188                         Arguments args = new Arguments (1);
6189                         args.Add (new Argument (source));
6190
6191                         var call = new CallEmitter ();
6192                         call.InstanceExpression = InstanceExpression;
6193                         call.Emit (ec, op, args, loc);
6194                 }
6195
6196                 #endregion
6197
6198                 void Error_AssignmentEventOnly (ResolveContext ec)
6199                 {
6200                         if (spec.DeclaringType == ec.CurrentType || TypeManager.IsNestedChildOf (ec.CurrentType, spec.DeclaringType.MemberDefinition)) {
6201                                 ec.Report.Error (79, loc,
6202                                         "The event `{0}' can only appear on the left hand side of `+=' or `-=' operator",
6203                                         GetSignatureForError ());
6204                         } else {
6205                                 ec.Report.Error (70, loc,
6206                                         "The event `{0}' can only appear on the left hand side of += or -= when used outside of the type `{1}'",
6207                                         GetSignatureForError (), spec.DeclaringType.GetSignatureForError ());
6208                         }
6209                 }
6210
6211                 protected override void Error_CannotCallAbstractBase (ResolveContext rc, string name)
6212                 {
6213                         name = name.Substring (0, name.LastIndexOf ('.'));
6214                         base.Error_CannotCallAbstractBase (rc, name);
6215                 }
6216
6217                 public override string GetSignatureForError ()
6218                 {
6219                         return TypeManager.CSharpSignature (spec);
6220                 }
6221
6222                 public override void SetTypeArguments (ResolveContext ec, TypeArguments ta)
6223                 {
6224                         Error_TypeArgumentsCannotBeUsed (ec, "event", GetSignatureForError (), loc);
6225                 }
6226         }
6227
6228         public class TemporaryVariableReference : VariableReference
6229         {
6230                 public class Declarator : Statement
6231                 {
6232                         TemporaryVariableReference variable;
6233
6234                         public Declarator (TemporaryVariableReference variable)
6235                         {
6236                                 this.variable = variable;
6237                                 loc = variable.loc;
6238                         }
6239
6240                         protected override void DoEmit (EmitContext ec)
6241                         {
6242                                 variable.li.CreateBuilder (ec);
6243                         }
6244
6245                         public override void Emit (EmitContext ec)
6246                         {
6247                                 // Don't create sequence point
6248                                 DoEmit (ec);
6249                         }
6250
6251                         protected override void CloneTo (CloneContext clonectx, Statement target)
6252                         {
6253                                 // Nothing
6254                         }
6255                 }
6256
6257                 LocalVariable li;
6258
6259                 public TemporaryVariableReference (LocalVariable li, Location loc)
6260                 {
6261                         this.li = li;
6262                         this.type = li.Type;
6263                         this.loc = loc;
6264                 }
6265
6266                 public override bool IsLockedByStatement {
6267                         get {
6268                                 return false;
6269                         }
6270                         set {
6271                         }
6272                 }
6273
6274                 public LocalVariable LocalInfo {
6275                     get {
6276                         return li;
6277                     }
6278                 }
6279
6280                 public static TemporaryVariableReference Create (TypeSpec type, Block block, Location loc)
6281                 {
6282                         var li = LocalVariable.CreateCompilerGenerated (type, block, loc);
6283                         return new TemporaryVariableReference (li, loc);
6284                 }
6285
6286                 protected override Expression DoResolve (ResolveContext ec)
6287                 {
6288                         eclass = ExprClass.Variable;
6289
6290                         //
6291                         // Don't capture temporary variables except when using
6292                         // state machine redirection and block yields
6293                         //
6294                         if (ec.CurrentAnonymousMethod != null && ec.CurrentAnonymousMethod.IsIterator &&
6295                                 ec.CurrentBlock.Explicit.HasYield && ec.IsVariableCapturingRequired) {
6296                                 AnonymousMethodStorey storey = li.Block.Explicit.CreateAnonymousMethodStorey (ec);
6297                                 storey.CaptureLocalVariable (ec, li);
6298                         }
6299
6300                         return this;
6301                 }
6302
6303                 public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
6304                 {
6305                         return Resolve (ec);
6306                 }
6307
6308                 public override void Emit (EmitContext ec)
6309                 {
6310                         li.CreateBuilder (ec);
6311
6312                         Emit (ec, false);
6313                 }
6314
6315                 public void EmitAssign (EmitContext ec, Expression source)
6316                 {
6317                         li.CreateBuilder (ec);
6318
6319                         EmitAssign (ec, source, false, false);
6320                 }
6321
6322                 public override HoistedVariable GetHoistedVariable (AnonymousExpression ae)
6323                 {
6324                         return li.HoistedVariant;
6325                 }
6326
6327                 public override bool IsFixed {
6328                         get { return true; }
6329                 }
6330
6331                 public override bool IsRef {
6332                         get { return false; }
6333                 }
6334
6335                 public override string Name {
6336                         get { throw new NotImplementedException (); }
6337                 }
6338
6339                 public override void SetHasAddressTaken ()
6340                 {
6341                         throw new NotImplementedException ();
6342                 }
6343
6344                 protected override ILocalVariable Variable {
6345                         get { return li; }
6346                 }
6347
6348                 public override VariableInfo VariableInfo {
6349                         get { return null; }
6350                 }
6351
6352                 public override void VerifyAssigned (ResolveContext rc)
6353                 {
6354                 }
6355         }
6356
6357         ///
6358         /// Handles `var' contextual keyword; var becomes a keyword only
6359         /// if no type called var exists in a variable scope
6360         ///
6361         class VarExpr : SimpleName
6362         {
6363                 public VarExpr (Location loc)
6364                         : base ("var", loc)
6365                 {
6366                 }
6367
6368                 public bool InferType (ResolveContext ec, Expression right_side)
6369                 {
6370                         if (type != null)
6371                                 throw new InternalErrorException ("An implicitly typed local variable could not be redefined");
6372
6373                         type = right_side.Type;
6374                         if (type == InternalType.NullLiteral || type.Kind == MemberKind.Void || type == InternalType.AnonymousMethod || type == InternalType.MethodGroup) {
6375                                 ec.Report.Error (815, loc,
6376                                         "An implicitly typed local variable declaration cannot be initialized with `{0}'",
6377                                         type.GetSignatureForError ());
6378                                 return false;
6379                         }
6380
6381                         eclass = ExprClass.Variable;
6382                         return true;
6383                 }
6384
6385                 protected override void Error_TypeOrNamespaceNotFound (IMemberContext ec)
6386                 {
6387                         if (ec.Module.Compiler.Settings.Version < LanguageVersion.V_3)
6388                                 base.Error_TypeOrNamespaceNotFound (ec);
6389                         else
6390                                 ec.Module.Compiler.Report.Error (825, loc, "The contextual keyword `var' may only appear within a local variable declaration");
6391                 }
6392         }
6393 }