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 //
  11 //
  12
  13 using System;
  14 using System.Collections.Generic;
  15 using System.Text;
  16 using SLE = System.Linq.Expressions;
  17 using System.Linq;
  18
  19 #if STATIC
  20 using IKVM.Reflection;
  21 using IKVM.Reflection.Emit;
  22 #else
  23 using System.Reflection;
  24 using System.Reflection.Emit;
  25 #endif
  26
  27 namespace Mono.CSharp {
  28
  29         /// <remarks>
  30         ///   The ExprClass class contains the is used to pass the
  31         ///   classification of an expression (value, variable, namespace,
  32         ///   type, method group, property access, event access, indexer access,
  33         ///   nothing).
  34         /// </remarks>
  35         public enum ExprClass : byte {
  36                 Unresolved      = 0,
  37
  38                 Value,
  39                 Variable,
  40                 Namespace,
  41                 Type,
  42                 TypeParameter,
  43                 MethodGroup,
  44                 PropertyAccess,
  45                 EventAccess,
  46                 IndexerAccess,
  47                 Nothing,
  48         }
  49
  50         /// <remarks>
  51         ///   This is used to tell Resolve in which types of expressions we're
  52         ///   interested.
  53         /// </remarks>
  54         [Flags]
  55         public enum ResolveFlags {
  56                 // Returns Value, Variable, PropertyAccess, EventAccess or IndexerAccess.
  57                 VariableOrValue         = 1,
  58
  59                 // Returns a type expression.
  60                 Type                    = 1 << 1,
  61
  62                 // Returns a method group.
  63                 MethodGroup             = 1 << 2,
  64
  65                 TypeParameter   = 1 << 3,
  66
  67                 // Mask of all the expression class flags.
  68                 MaskExprClass = VariableOrValue | Type | MethodGroup | TypeParameter,
  69         }
  70
  71         //
  72         // This is just as a hint to AddressOf of what will be done with the
  73         // address.
  74         [Flags]
  75         public enum AddressOp {
  76                 Store = 1,
  77                 Load  = 2,
  78                 LoadStore = 3
  79         };
  80
  81         /// <summary>
  82         ///   This interface is implemented by variables
  83         /// </summary>
  84         public interface IMemoryLocation {
  85                 /// <summary>
  86                 ///   The AddressOf method should generate code that loads
  87                 ///   the address of the object and leaves it on the stack.
  88                 ///
  89                 ///   The `mode' argument is used to notify the expression
  90                 ///   of whether this will be used to read from the address or
  91                 ///   write to the address.
  92                 ///
  93                 ///   This is just a hint that can be used to provide good error
  94                 ///   reporting, and should have no other side effects.
  95                 /// </summary>
  96                 void AddressOf (EmitContext ec, AddressOp mode);
  97         }
  98
  99         //
 100         // An expressions resolved as a direct variable reference
 101         //
 102         public interface IVariableReference : IFixedExpression
 103         {
 104                 bool IsHoisted { get; }
 105                 string Name { get; }
 106                 VariableInfo VariableInfo { get; }
 107
 108                 void SetHasAddressTaken ();
 109         }
 110
 111         //
 112         // Implemented by an expression which could be or is always
 113         // fixed
 114         //
 115         public interface IFixedExpression
 116         {
 117                 bool IsFixed { get; }
 118         }
 119
 120         /// <remarks>
 121         ///   Base class for expressions
 122         /// </remarks>
 123         public abstract class Expression {
 124                 public ExprClass eclass;
 125                 protected TypeSpec type;
 126                 protected Location loc;
 127
 128                 public TypeSpec Type {
 129                         get { return type; }
 130                         set { type = value; }
 131                 }
 132
 133                 public Location Location {
 134                         get { return loc; }
 135                 }
 136
 137                 public virtual string GetSignatureForError ()
 138                 {
 139                         return type.GetDefinition ().GetSignatureForError ();
 140                 }
 141
 142                 public virtual bool IsNull {
 143                         get {
 144                                 return false;
 145                         }
 146                 }
 147
 148                 /// <summary>
 149                 ///   Performs semantic analysis on the Expression
 150                 /// </summary>
 151                 ///
 152                 /// <remarks>
 153                 ///   The Resolve method is invoked to perform the semantic analysis
 154                 ///   on the node.
 155                 ///
 156                 ///   The return value is an expression (it can be the
 157                 ///   same expression in some cases) or a new
 158                 ///   expression that better represents this node.
 159                 ///
 160                 ///   For example, optimizations of Unary (LiteralInt)
 161                 ///   would return a new LiteralInt with a negated
 162                 ///   value.
 163                 ///
 164                 ///   If there is an error during semantic analysis,
 165                 ///   then an error should be reported (using Report)
 166                 ///   and a null value should be returned.
 167                 ///
 168                 ///   There are two side effects expected from calling
 169                 ///   Resolve(): the the field variable "eclass" should
 170                 ///   be set to any value of the enumeration
 171                 ///   `ExprClass' and the type variable should be set
 172                 ///   to a valid type (this is the type of the
 173                 ///   expression).
 174                 /// </remarks>
 175                 protected abstract Expression DoResolve (ResolveContext rc);
 176
 177                 public virtual Expression DoResolveLValue (ResolveContext rc, Expression right_side)
 178                 {
 179                         return null;
 180                 }
 181
 182                 //
 183                 // This is used if the expression should be resolved as a type or namespace name.
 184                 // the default implementation fails.
 185                 //
 186                 public virtual FullNamedExpression ResolveAsTypeStep (IMemberContext rc,  bool silent)
 187                 {
 188                         if (!silent) {
 189                                 ResolveContext ec = new ResolveContext (rc);
 190                                 Expression e = Resolve (ec);
 191                                 if (e != null)
 192                                         e.Error_UnexpectedKind (ec, ResolveFlags.Type, loc);
 193                         }
 194
 195                         return null;
 196                 }
 197
 198                 //
 199                 // This is used to resolve the expression as a type, a null
 200                 // value will be returned if the expression is not a type
 201                 // reference
 202                 //
 203                 public virtual TypeExpr ResolveAsTypeTerminal (IMemberContext ec , bool silent)
 204                 {
 205                         // FIXME: THIS IS TOO SLOW and it should not be needed either
 206                         int errors = ec.Module.Compiler.Report.Errors;
 207
 208                         FullNamedExpression fne = ResolveAsTypeStep (ec, silent);
 209
 210                         if (fne == null)
 211                                 return null;
 212
 213                         TypeExpr te = fne as TypeExpr;
 214                         if (te == null) {
 215                                 if (!silent && errors == ec.Module.Compiler.Report.Errors)
 216                                         fne.Error_UnexpectedKind (ec.Module.Compiler.Report, null, "type", loc);
 217                                 return null;
 218                         }
 219
 220                         if (!te.type.IsAccessible (ec.CurrentType)) {
 221                                 ec.Module.Compiler.Report.SymbolRelatedToPreviousError (te.Type);
 222                                 ErrorIsInaccesible (ec, te.Type.GetSignatureForError (), loc);
 223                         }
 224
 225                         te.loc = loc;
 226
 227                         var dep = te.type.GetMissingDependencies ();
 228                         if (dep != null) {
 229                                 ImportedTypeDefinition.Error_MissingDependency (ec, dep, loc);
 230                         }
 231
 232                         //
 233                         // Obsolete checks cannot be done when resolving base context as they
 234                         // require type dependecies to be set but we are just resolving them
 235                         //
 236                         if (!silent && !(ec is TypeContainer.BaseContext)) {
 237                                 ObsoleteAttribute obsolete_attr = te.Type.GetAttributeObsolete ();
 238                                 if (obsolete_attr != null && !ec.IsObsolete) {
 239                                         AttributeTester.Report_ObsoleteMessage (obsolete_attr, te.GetSignatureForError (), Location, ec.Module.Compiler.Report);
 240                                 }
 241                         }
 242
 243                         return te;
 244                 }
 245
 246                 public static void ErrorIsInaccesible (IMemberContext rc, string member, Location loc)
 247                 {
 248                         rc.Module.Compiler.Report.Error (122, loc, "`{0}' is inaccessible due to its protection level", member);
 249                 }
 250
 251                 public void Error_ExpressionMustBeConstant (ResolveContext rc, Location loc, string e_name)
 252                 {
 253                         rc.Report.Error (133, loc, "The expression being assigned to `{0}' must be constant", e_name);
 254                 }
 255
 256                 public void Error_ConstantCanBeInitializedWithNullOnly (ResolveContext rc, TypeSpec type, Location loc, string name)
 257                 {
 258                         rc.Report.Error (134, loc, "A constant `{0}' of reference type `{1}' can only be initialized with null",
 259                                 name, TypeManager.CSharpName (type));
 260                 }
 261
 262                 public static void Error_InvalidExpressionStatement (Report Report, Location loc)
 263                 {
 264                         Report.Error (201, loc, "Only assignment, call, increment, decrement, and new object " +
 265                                        "expressions can be used as a statement");
 266                 }
 267
 268                 public void Error_InvalidExpressionStatement (BlockContext ec)
 269                 {
 270                         Error_InvalidExpressionStatement (ec.Report, loc);
 271                 }
 272
 273                 public static void Error_VoidInvalidInTheContext (Location loc, Report Report)
 274                 {
 275                         Report.Error (1547, loc, "Keyword `void' cannot be used in this context");
 276                 }
 277
 278                 public virtual void Error_ValueCannotBeConverted (ResolveContext ec, Location loc, TypeSpec target, bool expl)
 279                 {
 280                         Error_ValueCannotBeConvertedCore (ec, loc, target, expl);
 281                 }
 282
 283                 protected void Error_ValueCannotBeConvertedCore (ResolveContext ec, Location loc, TypeSpec target, bool expl)
 284                 {
 285                         // The error was already reported as CS1660
 286                         if (type == InternalType.AnonymousMethod)
 287                                 return;
 288
 289                         string from_type = type.GetSignatureForError ();
 290                         string to_type = target.GetSignatureForError ();
 291                         if (from_type == to_type) {
 292                                 from_type = string.Format ("{0} [{1}]", from_type, type.MemberDefinition.DeclaringAssembly.FullName);
 293                                 to_type = string.Format ("{0} [{1}]", to_type, target.MemberDefinition.DeclaringAssembly.FullName);
 294                         }
 295
 296                         if (expl) {
 297                                 ec.Report.Error (30, loc, "Cannot convert type `{0}' to `{1}'",
 298                                         from_type, to_type);
 299                                 return;
 300                         }
 301
 302                         ec.Report.DisableReporting ();
 303                         bool expl_exists = Convert.ExplicitConversion (ec, this, target, Location.Null) != null;
 304                         ec.Report.EnableReporting ();
 305
 306                         if (expl_exists) {
 307                                 ec.Report.Error (266, loc,
 308                                         "Cannot implicitly convert type `{0}' to `{1}'. An explicit conversion exists (are you missing a cast?)",
 309                                         from_type, to_type);
 310                         } else {
 311                                 ec.Report.Error (29, loc, "Cannot implicitly convert type `{0}' to `{1}'",
 312                                         from_type, to_type);
 313                         }
 314                 }
 315
 316                 public void Error_TypeArgumentsCannotBeUsed (Report report, Location loc, MemberSpec member, int arity)
 317                 {
 318                         // Better message for possible generic expressions
 319                         if (member != null && (member.Kind & MemberKind.GenericMask) != 0) {
 320                                 report.SymbolRelatedToPreviousError (member);
 321                                 if (member is TypeSpec)
 322                                         member = ((TypeSpec) member).GetDefinition ();
 323                                 else
 324                                         member = ((MethodSpec) member).GetGenericMethodDefinition ();
 325
 326                                 string name = member.Kind == MemberKind.Method ? "method" : "type";
 327                                 if (member.IsGeneric) {
 328                                         report.Error (305, loc, "Using the generic {0} `{1}' requires `{2}' type argument(s)",
 329                                                 name, member.GetSignatureForError (), member.Arity.ToString ());
 330                                 } else {
 331                                         report.Error (308, loc, "The non-generic {0} `{1}' cannot be used with the type arguments",
 332                                                 name, member.GetSignatureForError ());
 333                                 }
 334                         } else {
 335                                 Error_TypeArgumentsCannotBeUsed (report, ExprClassName, GetSignatureForError (), loc);
 336                         }
 337                 }
 338
 339                 public void Error_TypeArgumentsCannotBeUsed (Report report, string exprType, string name, Location loc)
 340                 {
 341                         report.Error (307, loc, "The {0} `{1}' cannot be used with type arguments",
 342                                 exprType, name);
 343                 }
 344
 345                 protected virtual void Error_TypeDoesNotContainDefinition (ResolveContext ec, TypeSpec type, string name)
 346                 {
 347                         Error_TypeDoesNotContainDefinition (ec, loc, type, name);
 348                 }
 349
 350                 public static void Error_TypeDoesNotContainDefinition (ResolveContext ec, Location loc, TypeSpec type, string name)
 351                 {
 352                         ec.Report.SymbolRelatedToPreviousError (type);
 353                         ec.Report.Error (117, loc, "`{0}' does not contain a definition for `{1}'",
 354                                 TypeManager.CSharpName (type), name);
 355                 }
 356
 357                 protected static void Error_ValueAssignment (ResolveContext ec, Location loc)
 358                 {
 359                         ec.Report.Error (131, loc, "The left-hand side of an assignment must be a variable, a property or an indexer");
 360                 }
 361
 362                 protected void Error_VoidPointerOperation (ResolveContext rc)
 363                 {
 364                         rc.Report.Error (242, loc, "The operation in question is undefined on void pointers");
 365                 }
 366
 367                 public ResolveFlags ExprClassToResolveFlags {
 368                         get {
 369                                 switch (eclass) {
 370                                 case ExprClass.Type:
 371                                 case ExprClass.Namespace:
 372                                         return ResolveFlags.Type;
 373
 374                                 case ExprClass.MethodGroup:
 375                                         return ResolveFlags.MethodGroup;
 376
 377                                 case ExprClass.TypeParameter:
 378                                         return ResolveFlags.TypeParameter;
 379
 380                                 case ExprClass.Value:
 381                                 case ExprClass.Variable:
 382                                 case ExprClass.PropertyAccess:
 383                                 case ExprClass.EventAccess:
 384                                 case ExprClass.IndexerAccess:
 385                                         return ResolveFlags.VariableOrValue;
 386
 387                                 default:
 388                                         throw new InternalErrorException (loc.ToString () + " " +  GetType () + " ExprClass is Invalid after resolve");
 389                                 }
 390                         }
 391                 }
 392
 393                 /// <summary>
 394                 ///   Resolves an expression and performs semantic analysis on it.
 395                 /// </summary>
 396                 ///
 397                 /// <remarks>
 398                 ///   Currently Resolve wraps DoResolve to perform sanity
 399                 ///   checking and assertion checking on what we expect from Resolve.
 400                 /// </remarks>
 401                 public Expression Resolve (ResolveContext ec, ResolveFlags flags)
 402                 {
 403                         if (eclass != ExprClass.Unresolved)
 404                                 return this;
 405
 406                         Expression e;
 407                         try {
 408                                 e = DoResolve (ec);
 409
 410                                 if (e == null)
 411                                         return null;
 412
 413                                 if ((flags & e.ExprClassToResolveFlags) == 0) {
 414                                         e.Error_UnexpectedKind (ec, flags, loc);
 415                                         return null;
 416                                 }
 417
 418                                 if (e.type == null)
 419                                         throw new InternalErrorException ("Expression `{0}' didn't set its type in DoResolve", e.GetType ());
 420
 421                                 return e;
 422                         } catch (Exception ex) {
 423                                 if (loc.IsNull || Report.DebugFlags > 0 || ex is CompletionResult || ec.Report.IsDisabled)
 424                                         throw;
 425
 426                                 ec.Report.Error (584, loc, "Internal compiler error: {0}", ex.Message);
 427                                 return EmptyExpression.Null;    // TODO: Add location
 428                         }
 429                 }
 430
 431                 /// <summary>
 432                 ///   Resolves an expression and performs semantic analysis on it.
 433                 /// </summary>
 434                 public Expression Resolve (ResolveContext rc)
 435                 {
 436                         return Resolve (rc, ResolveFlags.VariableOrValue | ResolveFlags.MethodGroup);
 437                 }
 438
 439                 /// <summary>
 440                 ///   Resolves an expression for LValue assignment
 441                 /// </summary>
 442                 ///
 443                 /// <remarks>
 444                 ///   Currently ResolveLValue wraps DoResolveLValue to perform sanity
 445                 ///   checking and assertion checking on what we expect from Resolve
 446                 /// </remarks>
 447                 public Expression ResolveLValue (ResolveContext ec, Expression right_side)
 448                 {
 449                         int errors = ec.Report.Errors;
 450                         bool out_access = right_side == EmptyExpression.OutAccess.Instance;
 451
 452                         Expression e = DoResolveLValue (ec, right_side);
 453
 454                         if (e != null && out_access && !(e is IMemoryLocation)) {
 455                                 // FIXME: There's no problem with correctness, the 'Expr = null' handles that.
 456                                 //        Enabling this 'throw' will "only" result in deleting useless code elsewhere,
 457
 458                                 //throw new InternalErrorException ("ResolveLValue didn't return an IMemoryLocation: " +
 459                                 //                                e.GetType () + " " + e.GetSignatureForError ());
 460                                 e = null;
 461                         }
 462
 463                         if (e == null) {
 464                                 if (errors == ec.Report.Errors) {
 465                                         if (out_access)
 466                                                 ec.Report.Error (1510, loc, "A ref or out argument must be an assignable variable");
 467                                         else
 468                                                 Error_ValueAssignment (ec, loc);
 469                                 }
 470                                 return null;
 471                         }
 472
 473                         if (e.eclass == ExprClass.Unresolved)
 474                                 throw new Exception ("Expression " + e + " ExprClass is Invalid after resolve");
 475
 476                         if ((e.type == null) && !(e is GenericTypeExpr))
 477                                 throw new Exception ("Expression " + e + " did not set its type after Resolve");
 478
 479                         return e;
 480                 }
 481
 482                 public virtual void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
 483                 {
 484                         rc.Module.Compiler.Report.Error (182, loc,
 485                                 "An attribute argument must be a constant expression, typeof expression or array creation expression");
 486                 }
 487
 488                 /// <summary>
 489                 ///   Emits the code for the expression
 490                 /// </summary>
 491                 ///
 492                 /// <remarks>
 493                 ///   The Emit method is invoked to generate the code
 494                 ///   for the expression.
 495                 /// </remarks>
 496                 public abstract void Emit (EmitContext ec);
 497
 498
 499                 // Emit code to branch to @target if this expression is equivalent to @on_true.
 500                 // The default implementation is to emit the value, and then emit a brtrue or brfalse.
 501                 // Subclasses can provide more efficient implementations, but those MUST be equivalent,
 502                 // including the use of conditional branches.  Note also that a branch MUST be emitted
 503                 public virtual void EmitBranchable (EmitContext ec, Label target, bool on_true)
 504                 {
 505                         Emit (ec);
 506                         ec.Emit (on_true ? OpCodes.Brtrue : OpCodes.Brfalse, target);
 507                 }
 508
 509                 // Emit this expression for its side effects, not for its value.
 510                 // The default implementation is to emit the value, and then throw it away.
 511                 // Subclasses can provide more efficient implementations, but those MUST be equivalent
 512                 public virtual void EmitSideEffect (EmitContext ec)
 513                 {
 514                         Emit (ec);
 515                         ec.Emit (OpCodes.Pop);
 516                 }
 517
 518                 /// <summary>
 519                 ///   Protected constructor.  Only derivate types should
 520                 ///   be able to be created
 521                 /// </summary>
 522
 523                 protected Expression ()
 524                 {
 525                 }
 526
 527                 /// <summary>
 528                 ///   Returns a fully formed expression after a MemberLookup
 529                 /// </summary>
 530                 ///
 531                 static Expression ExprClassFromMemberInfo (MemberSpec spec, Location loc)
 532                 {
 533                         if (spec is EventSpec)
 534                                 return new EventExpr ((EventSpec) spec, loc);
 535                         if (spec is ConstSpec)
 536                                 return new ConstantExpr ((ConstSpec) spec, loc);
 537                         if (spec is FieldSpec)
 538                                 return new FieldExpr ((FieldSpec) spec, loc);
 539                         if (spec is PropertySpec)
 540                                 return new PropertyExpr ((PropertySpec) spec, loc);
 541                         if (spec is TypeSpec)
 542                                 return new TypeExpression (((TypeSpec) spec), loc);
 543
 544                         return null;
 545                 }
 546
 547                 protected static MethodSpec ConstructorLookup (ResolveContext rc, TypeSpec type, ref Arguments args, Location loc)
 548                 {
 549                         var ctors = MemberCache.FindMembers (type, Constructor.ConstructorName, true);
 550                         if (ctors == null) {
 551                                 rc.Report.SymbolRelatedToPreviousError (type);
 552                                 if (type.IsStruct) {
 553                                         // Report meaningful error for struct as they always have default ctor in C# context
 554                                         OverloadResolver.Error_ConstructorMismatch (rc, type, args == null ? 0 : args.Count, loc);
 555                                 } else {
 556                                         rc.Report.Error (143, loc, "The class `{0}' has no constructors defined",
 557                                                 type.GetSignatureForError ());
 558                                 }
 559
 560                                 return null;
 561                         }
 562
 563                         var r = new OverloadResolver (ctors, OverloadResolver.Restrictions.NoBaseMembers, loc);
 564                         return r.ResolveMember<MethodSpec> (rc, ref args);
 565                 }
 566
 567                 [Flags]
 568                 public enum MemberLookupRestrictions
 569                 {
 570                         None = 0,
 571                         InvocableOnly = 1,
 572                         ExactArity = 1 << 2,
 573                         ReadAccess = 1 << 3
 574                 }
 575
 576                 //
 577                 // Lookup type `queried_type' for code in class `container_type' with a qualifier of
 578                 // `qualifier_type' or null to lookup members in the current class.
 579                 //
 580                 public static Expression MemberLookup (ResolveContext rc, TypeSpec currentType, TypeSpec queried_type, string name, int arity, MemberLookupRestrictions restrictions, Location loc)
 581                 {
 582                         var members = MemberCache.FindMembers (queried_type, name, false);
 583                         if (members == null)
 584                                 return null;
 585
 586                         MemberSpec non_method = null;
 587                         MemberSpec ambig_non_method = null;
 588                         currentType = currentType ?? InternalType.FakeInternalType;
 589                         do {
 590                                 for (int i = 0; i < members.Count; ++i) {
 591                                         var member = members[i];
 592
 593                                         // HACK: for events because +=/-= can appear at same class only, should use OverrideToBase there
 594                                         if ((member.Modifiers & Modifiers.OVERRIDE) != 0 && member.Kind != MemberKind.Event)
 595                                                 continue;
 596
 597                                         if ((arity > 0 || (restrictions & MemberLookupRestrictions.ExactArity) != 0) && member.Arity != arity)
 598                                                 continue;
 599
 600                                         if (rc != null) {
 601                                                 if (!member.IsAccessible (currentType))
 602                                                         continue;
 603
 604                                                 //
 605                                                 // With runtime binder we can have a situation where queried type is inaccessible
 606                                                 // because it came via dynamic object, the check about inconsisted accessibility
 607                                                 // had no effect as the type was unknown during compilation
 608                                                 //
 609                                                 // class A {
 610                                                 //              private class N { }
 611                                                 //
 612                                                 //              public dynamic Foo ()
 613                                                 //              {
 614                                                 //                      return new N ();
 615                                                 //              }
 616                                                 //      }
 617                                                 //
 618                                                 if (rc.IsRuntimeBinder && !member.DeclaringType.IsAccessible (currentType))
 619                                                         continue;
 620                                         }
 621
 622                                         if ((restrictions & MemberLookupRestrictions.InvocableOnly) != 0) {
 623                                                 if (member is MethodSpec)
 624                                                         return new MethodGroupExpr (members, queried_type, loc);
 625
 626                                                 if (!Invocation.IsMemberInvocable (member))
 627                                                         continue;
 628                                         }
 629
 630                                         if (non_method == null || member is MethodSpec) {
 631                                                 non_method = member;
 632                                         } else if (currentType != null) {
 633                                                 ambig_non_method = member;
 634                                         }
 635                                 }
 636
 637                                 if (non_method != null) {
 638                                         if (ambig_non_method != null && rc != null) {
 639                                                 rc.Report.SymbolRelatedToPreviousError (non_method);
 640                                                 rc.Report.SymbolRelatedToPreviousError (ambig_non_method);
 641                                                 rc.Report.Error (229, loc, "Ambiguity between `{0}' and `{1}'",
 642                                                         non_method.GetSignatureForError (), ambig_non_method.GetSignatureForError ());
 643                                         }
 644
 645                                         if (non_method is MethodSpec)
 646                                                 return new MethodGroupExpr (members, queried_type, loc);
 647
 648                                         return ExprClassFromMemberInfo (non_method, loc);
 649                                 }
 650
 651                                 if (members[0].DeclaringType.BaseType == null)
 652                                         members = null;
 653                                 else
 654                                         members = MemberCache.FindMembers (members[0].DeclaringType.BaseType, name, false);
 655
 656                         } while (members != null);
 657
 658                         return null;
 659                 }
 660
 661                 protected virtual void Error_NegativeArrayIndex (ResolveContext ec, Location loc)
 662                 {
 663                         throw new NotImplementedException ();
 664                 }
 665
 666                 protected void Error_PointerInsideExpressionTree (ResolveContext ec)
 667                 {
 668                         ec.Report.Error (1944, loc, "An expression tree cannot contain an unsafe pointer operation");
 669                 }
 670
 671                 /// <summary>
 672                 ///   Returns an expression that can be used to invoke operator true
 673                 ///   on the expression if it exists.
 674                 /// </summary>
 675                 protected static Expression GetOperatorTrue (ResolveContext ec, Expression e, Location loc)
 676                 {
 677                         return GetOperatorTrueOrFalse (ec, e, true, loc);
 678                 }
 679
 680                 /// <summary>
 681                 ///   Returns an expression that can be used to invoke operator false
 682                 ///   on the expression if it exists.
 683                 /// </summary>
 684                 protected static Expression GetOperatorFalse (ResolveContext ec, Expression e, Location loc)
 685                 {
 686                         return GetOperatorTrueOrFalse (ec, e, false, loc);
 687                 }
 688
 689                 static Expression GetOperatorTrueOrFalse (ResolveContext ec, Expression e, bool is_true, Location loc)
 690                 {
 691                         var op = is_true ? Operator.OpType.True : Operator.OpType.False;
 692                         var methods = MemberCache.GetUserOperator (e.type, op, false);
 693                         if (methods == null)
 694                                 return null;
 695
 696                         Arguments arguments = new Arguments (1);
 697                         arguments.Add (new Argument (e));
 698
 699                         var res = new OverloadResolver (methods, OverloadResolver.Restrictions.BaseMembersIncluded | OverloadResolver.Restrictions.NoBaseMembers, loc);
 700                         var oper = res.ResolveOperator (ec, ref arguments);
 701
 702                         if (oper == null)
 703                                 return null;
 704
 705                         return new UserOperatorCall (oper, arguments, null, loc);
 706                 }
 707
 708                 public virtual string ExprClassName
 709                 {
 710                         get {
 711                                 switch (eclass){
 712                                 case ExprClass.Unresolved:
 713                                         return "Unresolved";
 714                                 case ExprClass.Value:
 715                                         return "value";
 716                                 case ExprClass.Variable:
 717                                         return "variable";
 718                                 case ExprClass.Namespace:
 719                                         return "namespace";
 720                                 case ExprClass.Type:
 721                                         return "type";
 722                                 case ExprClass.MethodGroup:
 723                                         return "method group";
 724                                 case ExprClass.PropertyAccess:
 725                                         return "property access";
 726                                 case ExprClass.EventAccess:
 727                                         return "event access";
 728                                 case ExprClass.IndexerAccess:
 729                                         return "indexer access";
 730                                 case ExprClass.Nothing:
 731                                         return "null";
 732                                 case ExprClass.TypeParameter:
 733                                         return "type parameter";
 734                                 }
 735                                 throw new Exception ("Should not happen");
 736                         }
 737                 }
 738
 739                 /// <summary>
 740                 ///   Reports that we were expecting `expr' to be of class `expected'
 741                 /// </summary>
 742                 public void Error_UnexpectedKind (Report r, MemberCore mc, string expected, Location loc)
 743                 {
 744                         Error_UnexpectedKind (r, mc, expected, ExprClassName, loc);
 745                 }
 746
 747                 public void Error_UnexpectedKind (Report r, MemberCore mc, string expected, string was, Location loc)
 748                 {
 749                         string name;
 750                         if (mc != null)
 751                                 name = mc.GetSignatureForError ();
 752                         else
 753                                 name = GetSignatureForError ();
 754
 755                         r.Error (118, loc, "`{0}' is a `{1}' but a `{2}' was expected",
 756                               name, was, expected);
 757                 }
 758
 759                 public void Error_UnexpectedKind (ResolveContext ec, ResolveFlags flags, Location loc)
 760                 {
 761                         string [] valid = new string [4];
 762                         int count = 0;
 763
 764                         if ((flags & ResolveFlags.VariableOrValue) != 0) {
 765                                 valid [count++] = "variable";
 766                                 valid [count++] = "value";
 767                         }
 768
 769                         if ((flags & ResolveFlags.Type) != 0)
 770                                 valid [count++] = "type";
 771
 772                         if ((flags & ResolveFlags.MethodGroup) != 0)
 773                                 valid [count++] = "method group";
 774
 775                         if (count == 0)
 776                                 valid [count++] = "unknown";
 777
 778                         StringBuilder sb = new StringBuilder (valid [0]);
 779                         for (int i = 1; i < count - 1; i++) {
 780                                 sb.Append ("', `");
 781                                 sb.Append (valid [i]);
 782                         }
 783                         if (count > 1) {
 784                                 sb.Append ("' or `");
 785                                 sb.Append (valid [count - 1]);
 786                         }
 787
 788                         ec.Report.Error (119, loc,
 789                                 "Expression denotes a `{0}', where a `{1}' was expected", ExprClassName, sb.ToString ());
 790                 }
 791
 792                 public static void UnsafeError (ResolveContext ec, Location loc)
 793                 {
 794                         UnsafeError (ec.Report, loc);
 795                 }
 796
 797                 public static void UnsafeError (Report Report, Location loc)
 798                 {
 799                         Report.Error (214, loc, "Pointers and fixed size buffers may only be used in an unsafe context");
 800                 }
 801
 802                 protected void Error_CannotModifyIntermediateExpressionValue (ResolveContext ec)
 803                 {
 804                         ec.Report.SymbolRelatedToPreviousError (type);
 805                         if (ec.CurrentInitializerVariable != null) {
 806                                 ec.Report.Error (1918, loc, "Members of value type `{0}' cannot be assigned using a property `{1}' object initializer",
 807                                         TypeManager.CSharpName (type), GetSignatureForError ());
 808                         } else {
 809                                 ec.Report.Error (1612, loc, "Cannot modify a value type return value of `{0}'. Consider storing the value in a temporary variable",
 810                                         GetSignatureForError ());
 811                         }
 812                 }
 813
 814                 //
 815                 // Converts `source' to an int, uint, long or ulong.
 816                 //
 817                 protected Expression ConvertExpressionToArrayIndex (ResolveContext ec, Expression source)
 818                 {
 819                         var btypes = ec.BuildinTypes;
 820
 821                         if (source.type == InternalType.Dynamic) {
 822                                 Arguments args = new Arguments (1);
 823                                 args.Add (new Argument (source));
 824                                 return new DynamicConversion (btypes.Int, CSharpBinderFlags.ConvertArrayIndex, args, loc).Resolve (ec);
 825                         }
 826
 827                         Expression converted;
 828
 829                         using (ec.Set (ResolveContext.Options.CheckedScope)) {
 830                                 converted = Convert.ImplicitConversion (ec, source, btypes.Int, source.loc);
 831                                 if (converted == null)
 832                                         converted = Convert.ImplicitConversion (ec, source, btypes.UInt, source.loc);
 833                                 if (converted == null)
 834                                         converted = Convert.ImplicitConversion (ec, source, btypes.Long, source.loc);
 835                                 if (converted == null)
 836                                         converted = Convert.ImplicitConversion (ec, source, btypes.ULong, source.loc);
 837
 838                                 if (converted == null) {
 839                                         source.Error_ValueCannotBeConverted (ec, source.loc, btypes.Int, false);
 840                                         return null;
 841                                 }
 842                         }
 843
 844                         //
 845                         // Only positive constants are allowed at compile time
 846                         //
 847                         Constant c = converted as Constant;
 848                         if (c != null && c.IsNegative)
 849                                 Error_NegativeArrayIndex (ec, source.loc);
 850
 851                         // No conversion needed to array index
 852                         if (converted.Type.BuildinType == BuildinTypeSpec.Type.Int)
 853                                 return converted;
 854
 855                         return new ArrayIndexCast (converted, btypes.Int).Resolve (ec);
 856                 }
 857
 858                 //
 859                 // Derived classes implement this method by cloning the fields that
 860                 // could become altered during the Resolve stage
 861                 //
 862                 // Only expressions that are created for the parser need to implement
 863                 // this.
 864                 //
 865                 protected virtual void CloneTo (CloneContext clonectx, Expression target)
 866                 {
 867                         throw new NotImplementedException (
 868                                 String.Format (
 869                                         "CloneTo not implemented for expression {0}", this.GetType ()));
 870                 }
 871
 872                 //
 873                 // Clones an expression created by the parser.
 874                 //
 875                 // We only support expressions created by the parser so far, not
 876                 // expressions that have been resolved (many more classes would need
 877                 // to implement CloneTo).
 878                 //
 879                 // This infrastructure is here merely for Lambda expressions which
 880                 // compile the same code using different type values for the same
 881                 // arguments to find the correct overload
 882                 //
 883                 public virtual Expression Clone (CloneContext clonectx)
 884                 {
 885                         Expression cloned = (Expression) MemberwiseClone ();
 886                         CloneTo (clonectx, cloned);
 887
 888                         return cloned;
 889                 }
 890
 891                 //
 892                 // Implementation of expression to expression tree conversion
 893                 //
 894                 public abstract Expression CreateExpressionTree (ResolveContext ec);
 895
 896                 protected Expression CreateExpressionFactoryCall (ResolveContext ec, string name, Arguments args)
 897                 {
 898                         return CreateExpressionFactoryCall (ec, name, null, args, loc);
 899                 }
 900
 901                 protected Expression CreateExpressionFactoryCall (ResolveContext ec, string name, TypeArguments typeArguments, Arguments args)
 902                 {
 903                         return CreateExpressionFactoryCall (ec, name, typeArguments, args, loc);
 904                 }
 905
 906                 public static Expression CreateExpressionFactoryCall (ResolveContext ec, string name, TypeArguments typeArguments, Arguments args, Location loc)
 907                 {
 908                         return new Invocation (new MemberAccess (CreateExpressionTypeExpression (ec, loc), name, typeArguments, loc), args);
 909                 }
 910
 911                 protected static TypeExpr CreateExpressionTypeExpression (ResolveContext ec, Location loc)
 912                 {
 913                         var t = ec.Module.PredefinedTypes.Expression.Resolve (loc);
 914                         if (t == null)
 915                                 return null;
 916
 917                         return new TypeExpression (t, loc);
 918                 }
 919
 920                 //
 921                 // Implemented by all expressions which support conversion from
 922                 // compiler expression to invokable runtime expression. Used by
 923                 // dynamic C# binder.
 924                 //
 925                 public virtual SLE.Expression MakeExpression (BuilderContext ctx)
 926                 {
 927                         throw new NotImplementedException ("MakeExpression for " + GetType ());
 928                 }
 929         }
 930
 931         /// <summary>
 932         ///   This is just a base class for expressions that can
 933         ///   appear on statements (invocations, object creation,
 934         ///   assignments, post/pre increment and decrement).  The idea
 935         ///   being that they would support an extra Emition interface that
 936         ///   does not leave a result on the stack.
 937         /// </summary>
 938         public abstract class ExpressionStatement : Expression {
 939
 940                 public ExpressionStatement ResolveStatement (BlockContext ec)
 941                 {
 942                         Expression e = Resolve (ec);
 943                         if (e == null)
 944                                 return null;
 945
 946                         ExpressionStatement es = e as ExpressionStatement;
 947                         if (es == null)
 948                                 Error_InvalidExpressionStatement (ec);
 949
 950                         return es;
 951                 }
 952
 953                 /// <summary>
 954                 ///   Requests the expression to be emitted in a `statement'
 955                 ///   context.  This means that no new value is left on the
 956                 ///   stack after invoking this method (constrasted with
 957                 ///   Emit that will always leave a value on the stack).
 958                 /// </summary>
 959                 public abstract void EmitStatement (EmitContext ec);
 960
 961                 public override void EmitSideEffect (EmitContext ec)
 962                 {
 963                         EmitStatement (ec);
 964                 }
 965         }
 966
 967         /// <summary>
 968         ///   This kind of cast is used to encapsulate the child
 969         ///   whose type is child.Type into an expression that is
 970         ///   reported to return "return_type".  This is used to encapsulate
 971         ///   expressions which have compatible types, but need to be dealt
 972         ///   at higher levels with.
 973         ///
 974         ///   For example, a "byte" expression could be encapsulated in one
 975         ///   of these as an "unsigned int".  The type for the expression
 976         ///   would be "unsigned int".
 977         ///
 978         /// </summary>
 979         public abstract class TypeCast : Expression
 980         {
 981                 protected readonly Expression child;
 982
 983                 protected TypeCast (Expression child, TypeSpec return_type)
 984                 {
 985                         eclass = child.eclass;
 986                         loc = child.Location;
 987                         type = return_type;
 988                         this.child = child;
 989                 }
 990
 991                 public Expression Child {
 992                         get {
 993                                 return child;
 994                         }
 995                 }
 996
 997                 public override Expression CreateExpressionTree (ResolveContext ec)
 998                 {
 999                         Arguments args = new Arguments (2);
1000                         args.Add (new Argument (child.CreateExpressionTree (ec)));
1001                         args.Add (new Argument (new TypeOf (new TypeExpression (type, loc), loc)));
1002
1003                         if (type.IsPointer || child.Type.IsPointer)
1004                                 Error_PointerInsideExpressionTree (ec);
1005
1006                         return CreateExpressionFactoryCall (ec, ec.HasSet (ResolveContext.Options.CheckedScope) ? "ConvertChecked" : "Convert", args);
1007                 }
1008
1009                 protected override Expression DoResolve (ResolveContext ec)
1010                 {
1011                         // This should never be invoked, we are born in fully
1012                         // initialized state.
1013
1014                         return this;
1015                 }
1016
1017                 public override void Emit (EmitContext ec)
1018                 {
1019                         child.Emit (ec);
1020                 }
1021
1022                 public override SLE.Expression MakeExpression (BuilderContext ctx)
1023                 {
1024 #if STATIC
1025                         return base.MakeExpression (ctx);
1026 #else
1027                         return ctx.HasSet (BuilderContext.Options.CheckedScope) ?
1028                                 SLE.Expression.ConvertChecked (child.MakeExpression (ctx), type.GetMetaInfo ()) :
1029                                 SLE.Expression.Convert (child.MakeExpression (ctx), type.GetMetaInfo ());
1030 #endif
1031                 }
1032
1033                 protected override void CloneTo (CloneContext clonectx, Expression t)
1034                 {
1035                         // Nothing to clone
1036                 }
1037
1038                 public override bool IsNull {
1039                         get { return child.IsNull; }
1040                 }
1041         }
1042
1043         public class EmptyCast : TypeCast {
1044                 EmptyCast (Expression child, TypeSpec target_type)
1045                         : base (child, target_type)
1046                 {
1047                 }
1048
1049                 public static Expression Create (Expression child, TypeSpec type)
1050                 {
1051                         Constant c = child as Constant;
1052                         if (c != null)
1053                                 return new EmptyConstantCast (c, type);
1054
1055                         EmptyCast e = child as EmptyCast;
1056                         if (e != null)
1057                                 return new EmptyCast (e.child, type);
1058
1059                         return new EmptyCast (child, type);
1060                 }
1061
1062                 public override void EmitBranchable (EmitContext ec, Label label, bool on_true)
1063                 {
1064                         child.EmitBranchable (ec, label, on_true);
1065                 }
1066
1067                 public override void EmitSideEffect (EmitContext ec)
1068                 {
1069                         child.EmitSideEffect (ec);
1070                 }
1071         }
1072
1073         //
1074         // Used for predefined class library user casts (no obsolete check, etc.)
1075         //
1076         public class OperatorCast : TypeCast {
1077                 MethodSpec conversion_operator;
1078
1079                 public OperatorCast (Expression child, TypeSpec target_type)
1080                         : this (child, target_type, false)
1081                 {
1082                 }
1083
1084                 public OperatorCast (Expression child, TypeSpec target_type, bool find_explicit)
1085                         : base (child, target_type)
1086                 {
1087                         conversion_operator = GetConversionOperator (find_explicit);
1088                         if (conversion_operator == null)
1089                                 throw new InternalErrorException ("Outer conversion routine is out of sync");
1090                 }
1091
1092                 // Returns the implicit operator that converts from
1093                 // 'child.Type' to our target type (type)
1094                 MethodSpec GetConversionOperator (bool find_explicit)
1095                 {
1096                         var op = find_explicit ? Operator.OpType.Explicit : Operator.OpType.Implicit;
1097
1098                         var mi = MemberCache.GetUserOperator (child.Type, op, true);
1099                         if (mi == null){
1100                                 mi = MemberCache.GetUserOperator (type, op, true);
1101                         }
1102
1103                         foreach (MethodSpec oper in mi) {
1104                                 if (oper.ReturnType != type)
1105                                         continue;
1106
1107                                 if (oper.Parameters.Types [0] == child.Type)
1108                                         return oper;
1109                         }
1110
1111                         return null;
1112                 }
1113
1114                 public override void Emit (EmitContext ec)
1115                 {
1116                         child.Emit (ec);
1117                         ec.Emit (OpCodes.Call, conversion_operator);
1118                 }
1119         }
1120
1121         /// <summary>
1122         ///     This is a numeric cast to a Decimal
1123         /// </summary>
1124         public class CastToDecimal : OperatorCast {
1125                 public CastToDecimal (Expression child)
1126                         : this (child, false)
1127                 {
1128                 }
1129
1130                 public CastToDecimal (Expression child, bool find_explicit)
1131                         : base (child, TypeManager.decimal_type, find_explicit)
1132                 {
1133                 }
1134         }
1135
1136         /// <summary>
1137         ///     This is an explicit numeric cast from a Decimal
1138         /// </summary>
1139         public class CastFromDecimal : TypeCast
1140         {
1141                 static Dictionary<TypeSpec, MethodSpec> operators;
1142
1143                 public CastFromDecimal (Expression child, TypeSpec return_type)
1144                         : base (child, return_type)
1145                 {
1146                         if (child.Type.BuildinType != BuildinTypeSpec.Type.Decimal)
1147                                 throw new ArgumentException ("Expected decimal child " + child.Type.GetSignatureForError ());
1148                 }
1149
1150                 // Returns the explicit operator that converts from an
1151                 // express of type System.Decimal to 'type'.
1152                 public Expression Resolve ()
1153                 {
1154                         if (operators == null) {
1155                                 var all_oper = MemberCache.GetUserOperator (TypeManager.decimal_type, Operator.OpType.Explicit, true);
1156
1157                                 operators = new Dictionary<TypeSpec, MethodSpec> ();
1158                                 foreach (MethodSpec oper in all_oper) {
1159                                         AParametersCollection pd = oper.Parameters;
1160                                         if (pd.Types [0].BuildinType == BuildinTypeSpec.Type.Decimal)
1161                                                 operators.Add (oper.ReturnType, oper);
1162                                 }
1163                         }
1164
1165                         return operators.ContainsKey (type) ? this : null;
1166                 }
1167
1168                 public override void Emit (EmitContext ec)
1169                 {
1170                         child.Emit (ec);
1171
1172                         ec.Emit (OpCodes.Call, operators [type]);
1173                 }
1174
1175                 public static void Reset ()
1176                 {
1177                         operators = null;
1178                 }
1179         }
1180
1181
1182         //
1183         // Constant specialization of EmptyCast.
1184         // We need to special case this since an empty cast of
1185         // a constant is still a constant.
1186         //
1187         public class EmptyConstantCast : Constant
1188         {
1189                 public readonly Constant child;
1190
1191                 public EmptyConstantCast (Constant child, TypeSpec type)
1192                         : base (child.Location)
1193                 {
1194                         if (child == null)
1195                                 throw new ArgumentNullException ("child");
1196
1197                         this.child = child;
1198                         this.eclass = child.eclass;
1199                         this.type = type;
1200                 }
1201
1202                 public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
1203                 {
1204                         if (child.Type == target_type)
1205                                 return child;
1206
1207                         // FIXME: check that 'type' can be converted to 'target_type' first
1208                         return child.ConvertExplicitly (in_checked_context, target_type);
1209                 }
1210
1211                 public override Expression CreateExpressionTree (ResolveContext ec)
1212                 {
1213                         Arguments args = Arguments.CreateForExpressionTree (ec, null,
1214                                 child.CreateExpressionTree (ec),
1215                                 new TypeOf (new TypeExpression (type, loc), loc));
1216
1217                         if (type.IsPointer)
1218                                 Error_PointerInsideExpressionTree (ec);
1219
1220                         return CreateExpressionFactoryCall (ec, "Convert", args);
1221                 }
1222
1223                 public override bool IsDefaultValue {
1224                         get { return child.IsDefaultValue; }
1225                 }
1226
1227                 public override bool IsNegative {
1228                         get { return child.IsNegative; }
1229                 }
1230
1231                 public override bool IsNull {
1232                         get { return child.IsNull; }
1233                 }
1234
1235                 public override bool IsOneInteger {
1236                         get { return child.IsOneInteger; }
1237                 }
1238
1239                 public override bool IsZeroInteger {
1240                         get { return child.IsZeroInteger; }
1241                 }
1242
1243                 public override void Emit (EmitContext ec)
1244                 {
1245                         child.Emit (ec);
1246                 }
1247
1248                 public override void EmitBranchable (EmitContext ec, Label label, bool on_true)
1249                 {
1250                         child.EmitBranchable (ec, label, on_true);
1251
1252                         // Only to make verifier happy
1253                         if (TypeManager.IsGenericParameter (type) && child.IsNull)
1254                                 ec.Emit (OpCodes.Unbox_Any, type);
1255                 }
1256
1257                 public override void EmitSideEffect (EmitContext ec)
1258                 {
1259                         child.EmitSideEffect (ec);
1260                 }
1261
1262                 public override object GetValue ()
1263                 {
1264                         return child.GetValue ();
1265                 }
1266
1267                 public override string GetValueAsLiteral ()
1268                 {
1269                         return child.GetValueAsLiteral ();
1270                 }
1271
1272                 public override long GetValueAsLong ()
1273                 {
1274                         return child.GetValueAsLong ();
1275                 }
1276
1277                 public override Constant ConvertImplicitly (TypeSpec target_type)
1278                 {
1279                         if (type == target_type)
1280                                 return this;
1281
1282                         // FIXME: Do we need to check user conversions?
1283                         if (!Convert.ImplicitStandardConversionExists (this, target_type))
1284                                 return null;
1285
1286                         return child.ConvertImplicitly (target_type);
1287                 }
1288         }
1289
1290         /// <summary>
1291         ///  This class is used to wrap literals which belong inside Enums
1292         /// </summary>
1293         public class EnumConstant : Constant
1294         {
1295                 public Constant Child;
1296
1297                 public EnumConstant (Constant child, TypeSpec enum_type)
1298                         : base (child.Location)
1299                 {
1300                         this.Child = child;
1301
1302                         this.eclass = ExprClass.Value;
1303                         this.type = enum_type;
1304                 }
1305
1306                 protected EnumConstant (Location loc)
1307                         : base (loc)
1308                 {
1309                 }
1310
1311                 public override void Emit (EmitContext ec)
1312                 {
1313                         Child.Emit (ec);
1314                 }
1315
1316                 public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
1317                 {
1318                         Child.EncodeAttributeValue (rc, enc, Child.Type);
1319                 }
1320
1321                 public override void EmitBranchable (EmitContext ec, Label label, bool on_true)
1322                 {
1323                         Child.EmitBranchable (ec, label, on_true);
1324                 }
1325
1326                 public override void EmitSideEffect (EmitContext ec)
1327                 {
1328                         Child.EmitSideEffect (ec);
1329                 }
1330
1331                 public override string GetSignatureForError()
1332                 {
1333                         return TypeManager.CSharpName (Type);
1334                 }
1335
1336                 public override object GetValue ()
1337                 {
1338                         return Child.GetValue ();
1339                 }
1340
1341 #if !STATIC
1342                 public override object GetTypedValue ()
1343                 {
1344                         //
1345                         // The method can be used in dynamic context only (on closed types)
1346                         //
1347                         // System.Enum.ToObject cannot be called on dynamic types
1348                         // EnumBuilder has to be used, but we cannot use EnumBuilder
1349                         // because it does not properly support generics
1350                         //
1351                         return System.Enum.ToObject (type.GetMetaInfo (), Child.GetValue ());
1352                 }
1353 #endif
1354
1355                 public override string GetValueAsLiteral ()
1356                 {
1357                         return Child.GetValueAsLiteral ();
1358                 }
1359
1360                 public override long GetValueAsLong ()
1361                 {
1362                         return Child.GetValueAsLong ();
1363                 }
1364
1365                 public EnumConstant Increment()
1366                 {
1367                         return new EnumConstant (((IntegralConstant) Child).Increment (), type);
1368                 }
1369
1370                 public override bool IsDefaultValue {
1371                         get {
1372                                 return Child.IsDefaultValue;
1373                         }
1374                 }
1375
1376                 public override bool IsZeroInteger {
1377                         get { return Child.IsZeroInteger; }
1378                 }
1379
1380                 public override bool IsNegative {
1381                         get {
1382                                 return Child.IsNegative;
1383                         }
1384                 }
1385
1386                 public override Constant ConvertExplicitly(bool in_checked_context, TypeSpec target_type)
1387                 {
1388                         if (Child.Type == target_type)
1389                                 return Child;
1390
1391                         return Child.ConvertExplicitly (in_checked_context, target_type);
1392                 }
1393
1394                 public override Constant ConvertImplicitly (TypeSpec type)
1395                 {
1396                         if (this.type == type) {
1397                                 return this;
1398                         }
1399
1400                         if (!Convert.ImplicitStandardConversionExists (this, type)){
1401                                 return null;
1402                         }
1403
1404                         return Child.ConvertImplicitly (type);
1405                 }
1406         }
1407
1408         /// <summary>
1409         ///   This kind of cast is used to encapsulate Value Types in objects.
1410         ///
1411         ///   The effect of it is to box the value type emitted by the previous
1412         ///   operation.
1413         /// </summary>
1414         public class BoxedCast : TypeCast {
1415
1416                 public BoxedCast (Expression expr, TypeSpec target_type)
1417                         : base (expr, target_type)
1418                 {
1419                         eclass = ExprClass.Value;
1420                 }
1421
1422                 protected override Expression DoResolve (ResolveContext ec)
1423                 {
1424                         // This should never be invoked, we are born in fully
1425                         // initialized state.
1426
1427                         return this;
1428                 }
1429
1430                 public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
1431                 {
1432                         // Only boxing to object type is supported
1433                         if (targetType.BuildinType != BuildinTypeSpec.Type.Object) {
1434                                 base.EncodeAttributeValue (rc, enc, targetType);
1435                                 return;
1436                         }
1437
1438                         enc.Encode (child.Type);
1439                         child.EncodeAttributeValue (rc, enc, child.Type);
1440                 }
1441
1442                 public override void Emit (EmitContext ec)
1443                 {
1444                         base.Emit (ec);
1445
1446                         ec.Emit (OpCodes.Box, child.Type);
1447                 }
1448
1449                 public override void EmitSideEffect (EmitContext ec)
1450                 {
1451                         // boxing is side-effectful, since it involves runtime checks, except when boxing to Object or ValueType
1452                         // so, we need to emit the box+pop instructions in most cases
1453                         if (TypeManager.IsStruct (child.Type) &&
1454                             (type.BuildinType == BuildinTypeSpec.Type.Object || type.BuildinType == BuildinTypeSpec.Type.ValueType))
1455                                 child.EmitSideEffect (ec);
1456                         else
1457                                 base.EmitSideEffect (ec);
1458                 }
1459         }
1460
1461         public class UnboxCast : TypeCast {
1462                 public UnboxCast (Expression expr, TypeSpec return_type)
1463                         : base (expr, return_type)
1464                 {
1465                 }
1466
1467                 protected override Expression DoResolve (ResolveContext ec)
1468                 {
1469                         // This should never be invoked, we are born in fully
1470                         // initialized state.
1471
1472                         return this;
1473                 }
1474
1475                 public override void Emit (EmitContext ec)
1476                 {
1477                         base.Emit (ec);
1478
1479                         ec.Emit (OpCodes.Unbox_Any, type);
1480                 }
1481         }
1482
1483         /// <summary>
1484         ///   This is used to perform explicit numeric conversions.
1485         ///
1486         ///   Explicit numeric conversions might trigger exceptions in a checked
1487         ///   context, so they should generate the conv.ovf opcodes instead of
1488         ///   conv opcodes.
1489         /// </summary>
1490         public class ConvCast : TypeCast {
1491                 public enum Mode : byte {
1492                         I1_U1, I1_U2, I1_U4, I1_U8, I1_CH,
1493                         U1_I1, U1_CH,
1494                         I2_I1, I2_U1, I2_U2, I2_U4, I2_U8, I2_CH,
1495                         U2_I1, U2_U1, U2_I2, U2_CH,
1496                         I4_I1, I4_U1, I4_I2, I4_U2, I4_U4, I4_U8, I4_CH,
1497                         U4_I1, U4_U1, U4_I2, U4_U2, U4_I4, U4_CH,
1498                         I8_I1, I8_U1, I8_I2, I8_U2, I8_I4, I8_U4, I8_U8, I8_CH, I8_I,
1499                         U8_I1, U8_U1, U8_I2, U8_U2, U8_I4, U8_U4, U8_I8, U8_CH, U8_I,
1500                         CH_I1, CH_U1, CH_I2,
1501                         R4_I1, R4_U1, R4_I2, R4_U2, R4_I4, R4_U4, R4_I8, R4_U8, R4_CH,
1502                         R8_I1, R8_U1, R8_I2, R8_U2, R8_I4, R8_U4, R8_I8, R8_U8, R8_CH, R8_R4,
1503                         I_I8,
1504                 }
1505
1506                 Mode mode;
1507
1508                 public ConvCast (Expression child, TypeSpec return_type, Mode m)
1509                         : base (child, return_type)
1510                 {
1511                         mode = m;
1512                 }
1513
1514                 protected override Expression DoResolve (ResolveContext ec)
1515                 {
1516                         // This should never be invoked, we are born in fully
1517                         // initialized state.
1518
1519                         return this;
1520                 }
1521
1522                 public override string ToString ()
1523                 {
1524                         return String.Format ("ConvCast ({0}, {1})", mode, child);
1525                 }
1526
1527                 public override void Emit (EmitContext ec)
1528                 {
1529                         base.Emit (ec);
1530
1531                         if (ec.HasSet (EmitContext.Options.CheckedScope)) {
1532                                 switch (mode){
1533                                 case Mode.I1_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1534                                 case Mode.I1_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1535                                 case Mode.I1_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1536                                 case Mode.I1_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1537                                 case Mode.I1_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1538
1539                                 case Mode.U1_I1: ec.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1540                                 case Mode.U1_CH: /* nothing */ break;
1541
1542                                 case Mode.I2_I1: ec.Emit (OpCodes.Conv_Ovf_I1); break;
1543                                 case Mode.I2_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1544                                 case Mode.I2_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1545                                 case Mode.I2_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1546                                 case Mode.I2_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1547                                 case Mode.I2_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1548
1549                                 case Mode.U2_I1: ec.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1550                                 case Mode.U2_U1: ec.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1551                                 case Mode.U2_I2: ec.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1552                                 case Mode.U2_CH: /* nothing */ break;
1553
1554                                 case Mode.I4_I1: ec.Emit (OpCodes.Conv_Ovf_I1); break;
1555                                 case Mode.I4_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1556                                 case Mode.I4_I2: ec.Emit (OpCodes.Conv_Ovf_I2); break;
1557                                 case Mode.I4_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1558                                 case Mode.I4_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1559                                 case Mode.I4_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1560                                 case Mode.I4_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1561
1562                                 case Mode.U4_I1: ec.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1563                                 case Mode.U4_U1: ec.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1564                                 case Mode.U4_I2: ec.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1565                                 case Mode.U4_U2: ec.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1566                                 case Mode.U4_I4: ec.Emit (OpCodes.Conv_Ovf_I4_Un); break;
1567                                 case Mode.U4_CH: ec.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1568
1569                                 case Mode.I8_I1: ec.Emit (OpCodes.Conv_Ovf_I1); break;
1570                                 case Mode.I8_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1571                                 case Mode.I8_I2: ec.Emit (OpCodes.Conv_Ovf_I2); break;
1572                                 case Mode.I8_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1573                                 case Mode.I8_I4: ec.Emit (OpCodes.Conv_Ovf_I4); break;
1574                                 case Mode.I8_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1575                                 case Mode.I8_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1576                                 case Mode.I8_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1577                                 case Mode.I8_I: ec.Emit (OpCodes.Conv_Ovf_U); break;
1578
1579                                 case Mode.U8_I1: ec.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1580                                 case Mode.U8_U1: ec.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1581                                 case Mode.U8_I2: ec.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1582                                 case Mode.U8_U2: ec.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1583                                 case Mode.U8_I4: ec.Emit (OpCodes.Conv_Ovf_I4_Un); break;
1584                                 case Mode.U8_U4: ec.Emit (OpCodes.Conv_Ovf_U4_Un); break;
1585                                 case Mode.U8_I8: ec.Emit (OpCodes.Conv_Ovf_I8_Un); break;
1586                                 case Mode.U8_CH: ec.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1587                                 case Mode.U8_I: ec.Emit (OpCodes.Conv_Ovf_U_Un); break;
1588
1589                                 case Mode.CH_I1: ec.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1590                                 case Mode.CH_U1: ec.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1591                                 case Mode.CH_I2: ec.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1592
1593                                 case Mode.R4_I1: ec.Emit (OpCodes.Conv_Ovf_I1); break;
1594                                 case Mode.R4_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1595                                 case Mode.R4_I2: ec.Emit (OpCodes.Conv_Ovf_I2); break;
1596                                 case Mode.R4_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1597                                 case Mode.R4_I4: ec.Emit (OpCodes.Conv_Ovf_I4); break;
1598                                 case Mode.R4_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1599                                 case Mode.R4_I8: ec.Emit (OpCodes.Conv_Ovf_I8); break;
1600                                 case Mode.R4_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1601                                 case Mode.R4_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1602
1603                                 case Mode.R8_I1: ec.Emit (OpCodes.Conv_Ovf_I1); break;
1604                                 case Mode.R8_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1605                                 case Mode.R8_I2: ec.Emit (OpCodes.Conv_Ovf_I2); break;
1606                                 case Mode.R8_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1607                                 case Mode.R8_I4: ec.Emit (OpCodes.Conv_Ovf_I4); break;
1608                                 case Mode.R8_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1609                                 case Mode.R8_I8: ec.Emit (OpCodes.Conv_Ovf_I8); break;
1610                                 case Mode.R8_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1611                                 case Mode.R8_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1612                                 case Mode.R8_R4: ec.Emit (OpCodes.Conv_R4); break;
1613
1614                                 case Mode.I_I8: ec.Emit (OpCodes.Conv_Ovf_I8_Un); break;
1615                                 }
1616                         } else {
1617                                 switch (mode){
1618                                 case Mode.I1_U1: ec.Emit (OpCodes.Conv_U1); break;
1619                                 case Mode.I1_U2: ec.Emit (OpCodes.Conv_U2); break;
1620                                 case Mode.I1_U4: ec.Emit (OpCodes.Conv_U4); break;
1621                                 case Mode.I1_U8: ec.Emit (OpCodes.Conv_I8); break;
1622                                 case Mode.I1_CH: ec.Emit (OpCodes.Conv_U2); break;
1623
1624                                 case Mode.U1_I1: ec.Emit (OpCodes.Conv_I1); break;
1625                                 case Mode.U1_CH: ec.Emit (OpCodes.Conv_U2); break;
1626
1627                                 case Mode.I2_I1: ec.Emit (OpCodes.Conv_I1); break;
1628                                 case Mode.I2_U1: ec.Emit (OpCodes.Conv_U1); break;
1629                                 case Mode.I2_U2: ec.Emit (OpCodes.Conv_U2); break;
1630                                 case Mode.I2_U4: ec.Emit (OpCodes.Conv_U4); break;
1631                                 case Mode.I2_U8: ec.Emit (OpCodes.Conv_I8); break;
1632                                 case Mode.I2_CH: ec.Emit (OpCodes.Conv_U2); break;
1633
1634                                 case Mode.U2_I1: ec.Emit (OpCodes.Conv_I1); break;
1635                                 case Mode.U2_U1: ec.Emit (OpCodes.Conv_U1); break;
1636                                 case Mode.U2_I2: ec.Emit (OpCodes.Conv_I2); break;
1637                                 case Mode.U2_CH: /* nothing */ break;
1638
1639                                 case Mode.I4_I1: ec.Emit (OpCodes.Conv_I1); break;
1640                                 case Mode.I4_U1: ec.Emit (OpCodes.Conv_U1); break;
1641                                 case Mode.I4_I2: ec.Emit (OpCodes.Conv_I2); break;
1642                                 case Mode.I4_U4: /* nothing */ break;
1643                                 case Mode.I4_U2: ec.Emit (OpCodes.Conv_U2); break;
1644                                 case Mode.I4_U8: ec.Emit (OpCodes.Conv_I8); break;
1645                                 case Mode.I4_CH: ec.Emit (OpCodes.Conv_U2); break;
1646
1647                                 case Mode.U4_I1: ec.Emit (OpCodes.Conv_I1); break;
1648                                 case Mode.U4_U1: ec.Emit (OpCodes.Conv_U1); break;
1649                                 case Mode.U4_I2: ec.Emit (OpCodes.Conv_I2); break;
1650                                 case Mode.U4_U2: ec.Emit (OpCodes.Conv_U2); break;
1651                                 case Mode.U4_I4: /* nothing */ break;
1652                                 case Mode.U4_CH: ec.Emit (OpCodes.Conv_U2); break;
1653
1654                                 case Mode.I8_I1: ec.Emit (OpCodes.Conv_I1); break;
1655                                 case Mode.I8_U1: ec.Emit (OpCodes.Conv_U1); break;
1656                                 case Mode.I8_I2: ec.Emit (OpCodes.Conv_I2); break;
1657                                 case Mode.I8_U2: ec.Emit (OpCodes.Conv_U2); break;
1658                                 case Mode.I8_I4: ec.Emit (OpCodes.Conv_I4); break;
1659                                 case Mode.I8_U4: ec.Emit (OpCodes.Conv_U4); break;
1660                                 case Mode.I8_U8: /* nothing */ break;
1661                                 case Mode.I8_CH: ec.Emit (OpCodes.Conv_U2); break;
1662                                 case Mode.I8_I: ec.Emit (OpCodes.Conv_U); break;
1663
1664                                 case Mode.U8_I1: ec.Emit (OpCodes.Conv_I1); break;
1665                                 case Mode.U8_U1: ec.Emit (OpCodes.Conv_U1); break;
1666                                 case Mode.U8_I2: ec.Emit (OpCodes.Conv_I2); break;
1667                                 case Mode.U8_U2: ec.Emit (OpCodes.Conv_U2); break;
1668                                 case Mode.U8_I4: ec.Emit (OpCodes.Conv_I4); break;
1669                                 case Mode.U8_U4: ec.Emit (OpCodes.Conv_U4); break;
1670                                 case Mode.U8_I8: /* nothing */ break;
1671                                 case Mode.U8_CH: ec.Emit (OpCodes.Conv_U2); break;
1672                                 case Mode.U8_I: ec.Emit (OpCodes.Conv_U); break;
1673
1674                                 case Mode.CH_I1: ec.Emit (OpCodes.Conv_I1); break;
1675                                 case Mode.CH_U1: ec.Emit (OpCodes.Conv_U1); break;
1676                                 case Mode.CH_I2: ec.Emit (OpCodes.Conv_I2); break;
1677
1678                                 case Mode.R4_I1: ec.Emit (OpCodes.Conv_I1); break;
1679                                 case Mode.R4_U1: ec.Emit (OpCodes.Conv_U1); break;
1680                                 case Mode.R4_I2: ec.Emit (OpCodes.Conv_I2); break;
1681                                 case Mode.R4_U2: ec.Emit (OpCodes.Conv_U2); break;
1682                                 case Mode.R4_I4: ec.Emit (OpCodes.Conv_I4); break;
1683                                 case Mode.R4_U4: ec.Emit (OpCodes.Conv_U4); break;
1684                                 case Mode.R4_I8: ec.Emit (OpCodes.Conv_I8); break;
1685                                 case Mode.R4_U8: ec.Emit (OpCodes.Conv_U8); break;
1686                                 case Mode.R4_CH: ec.Emit (OpCodes.Conv_U2); break;
1687
1688                                 case Mode.R8_I1: ec.Emit (OpCodes.Conv_I1); break;
1689                                 case Mode.R8_U1: ec.Emit (OpCodes.Conv_U1); break;
1690                                 case Mode.R8_I2: ec.Emit (OpCodes.Conv_I2); break;
1691                                 case Mode.R8_U2: ec.Emit (OpCodes.Conv_U2); break;
1692                                 case Mode.R8_I4: ec.Emit (OpCodes.Conv_I4); break;
1693                                 case Mode.R8_U4: ec.Emit (OpCodes.Conv_U4); break;
1694                                 case Mode.R8_I8: ec.Emit (OpCodes.Conv_I8); break;
1695                                 case Mode.R8_U8: ec.Emit (OpCodes.Conv_U8); break;
1696                                 case Mode.R8_CH: ec.Emit (OpCodes.Conv_U2); break;
1697                                 case Mode.R8_R4: ec.Emit (OpCodes.Conv_R4); break;
1698
1699                                 case Mode.I_I8: ec.Emit (OpCodes.Conv_U8); break;
1700                                 }
1701                         }
1702                 }
1703         }
1704
1705         class OpcodeCast : TypeCast
1706         {
1707                 readonly OpCode op;
1708
1709                 public OpcodeCast (Expression child, TypeSpec return_type, OpCode op)
1710                         : base (child, return_type)
1711                 {
1712                         this.op = op;
1713                 }
1714
1715                 protected override Expression DoResolve (ResolveContext ec)
1716                 {
1717                         // This should never be invoked, we are born in fully
1718                         // initialized state.
1719
1720                         return this;
1721                 }
1722
1723                 public override void Emit (EmitContext ec)
1724                 {
1725                         base.Emit (ec);
1726                         ec.Emit (op);
1727                 }
1728
1729                 public TypeSpec UnderlyingType {
1730                         get { return child.Type; }
1731                 }
1732         }
1733
1734         //
1735         // Opcode casts expression with 2 opcodes but only
1736         // single expression tree node
1737         //
1738         class OpcodeCastDuplex : OpcodeCast
1739         {
1740                 readonly OpCode second;
1741
1742                 public OpcodeCastDuplex (Expression child, TypeSpec returnType, OpCode first, OpCode second)
1743                         : base (child, returnType, first)
1744                 {
1745                         this.second = second;
1746                 }
1747
1748                 public override void Emit (EmitContext ec)
1749                 {
1750                         base.Emit (ec);
1751                         ec.Emit (second);
1752                 }
1753         }
1754
1755         /// <summary>
1756         ///   This kind of cast is used to encapsulate a child and cast it
1757         ///   to the class requested
1758         /// </summary>
1759         public sealed class ClassCast : TypeCast {
1760                 readonly bool forced;
1761
1762                 public ClassCast (Expression child, TypeSpec return_type)
1763                         : base (child, return_type)
1764                 {
1765                 }
1766
1767                 public ClassCast (Expression child, TypeSpec return_type, bool forced)
1768                         : base (child, return_type)
1769                 {
1770                         this.forced = forced;
1771                 }
1772
1773                 public override void Emit (EmitContext ec)
1774                 {
1775                         base.Emit (ec);
1776
1777                         bool gen = TypeManager.IsGenericParameter (child.Type);
1778                         if (gen)
1779                                 ec.Emit (OpCodes.Box, child.Type);
1780
1781                         if (type.IsGenericParameter) {
1782                                 ec.Emit (OpCodes.Unbox_Any, type);
1783                                 return;
1784                         }
1785
1786                         if (gen && !forced)
1787                                 return;
1788
1789                         ec.Emit (OpCodes.Castclass, type);
1790                 }
1791         }
1792
1793         //
1794         // Created during resolving pahse when an expression is wrapped or constantified
1795         // and original expression can be used later (e.g. for expression trees)
1796         //
1797         public class ReducedExpression : Expression
1798         {
1799                 sealed class ReducedConstantExpression : EmptyConstantCast
1800                 {
1801                         readonly Expression orig_expr;
1802
1803                         public ReducedConstantExpression (Constant expr, Expression orig_expr)
1804                                 : base (expr, expr.Type)
1805                         {
1806                                 this.orig_expr = orig_expr;
1807                         }
1808
1809                         public override Constant ConvertImplicitly (TypeSpec target_type)
1810                         {
1811                                 Constant c = base.ConvertImplicitly (target_type);
1812                                 if (c != null)
1813                                         c = new ReducedConstantExpression (c, orig_expr);
1814
1815                                 return c;
1816                         }
1817
1818                         public override Expression CreateExpressionTree (ResolveContext ec)
1819                         {
1820                                 return orig_expr.CreateExpressionTree (ec);
1821                         }
1822
1823                         public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
1824                         {
1825                                 Constant c = base.ConvertExplicitly (in_checked_context, target_type);
1826                                 if (c != null)
1827                                         c = new ReducedConstantExpression (c, orig_expr);
1828                                 return c;
1829                         }
1830                 }
1831
1832                 sealed class ReducedExpressionStatement : ExpressionStatement
1833                 {
1834                         readonly Expression orig_expr;
1835                         readonly ExpressionStatement stm;
1836
1837                         public ReducedExpressionStatement (ExpressionStatement stm, Expression orig)
1838                         {
1839                                 this.orig_expr = orig;
1840                                 this.stm = stm;
1841                                 this.eclass = stm.eclass;
1842                                 this.type = stm.Type;
1843
1844                                 this.loc = orig.Location;
1845                         }
1846
1847                         public override Expression CreateExpressionTree (ResolveContext ec)
1848                         {
1849                                 return orig_expr.CreateExpressionTree (ec);
1850                         }
1851
1852                         protected override Expression DoResolve (ResolveContext ec)
1853                         {
1854                                 return this;
1855                         }
1856
1857                         public override void Emit (EmitContext ec)
1858                         {
1859                                 stm.Emit (ec);
1860                         }
1861
1862                         public override void EmitStatement (EmitContext ec)
1863                         {
1864                                 stm.EmitStatement (ec);
1865                         }
1866                 }
1867
1868                 readonly Expression expr, orig_expr;
1869
1870                 private ReducedExpression (Expression expr, Expression orig_expr)
1871                 {
1872                         this.expr = expr;
1873                         this.eclass = expr.eclass;
1874                         this.type = expr.Type;
1875                         this.orig_expr = orig_expr;
1876                         this.loc = orig_expr.Location;
1877                 }
1878
1879                 #region Properties
1880
1881                 public Expression OriginalExpression {
1882                         get {
1883                                 return orig_expr;
1884                         }
1885                 }
1886
1887                 #endregion
1888
1889                 //
1890                 // Creates fully resolved expression switcher
1891                 //
1892                 public static Constant Create (Constant expr, Expression original_expr)
1893                 {
1894                         if (expr.eclass == ExprClass.Unresolved)
1895                                 throw new ArgumentException ("Unresolved expression");
1896
1897                         return new ReducedConstantExpression (expr, original_expr);
1898                 }
1899
1900                 public static ExpressionStatement Create (ExpressionStatement s, Expression orig)
1901                 {
1902                         return new ReducedExpressionStatement (s, orig);
1903                 }
1904
1905                 public static Expression Create (Expression expr, Expression original_expr)
1906                 {
1907                         return Create (expr, original_expr, true);
1908                 }
1909
1910                 //
1911                 // Creates unresolved reduce expression. The original expression has to be
1912                 // already resolved. Created expression is constant based based on `expr'
1913                 // value unless canBeConstant is used
1914                 //
1915                 public static Expression Create (Expression expr, Expression original_expr, bool canBeConstant)
1916                 {
1917                         if (canBeConstant) {
1918                                 Constant c = expr as Constant;
1919                                 if (c != null)
1920                                         return Create (c, original_expr);
1921                         }
1922
1923                         ExpressionStatement s = expr as ExpressionStatement;
1924                         if (s != null)
1925                                 return Create (s, original_expr);
1926
1927                         if (expr.eclass == ExprClass.Unresolved)
1928                                 throw new ArgumentException ("Unresolved expression");
1929
1930                         return new ReducedExpression (expr, original_expr);
1931                 }
1932
1933                 public override Expression CreateExpressionTree (ResolveContext ec)
1934                 {
1935                         return orig_expr.CreateExpressionTree (ec);
1936                 }
1937
1938                 protected override Expression DoResolve (ResolveContext ec)
1939                 {
1940                         return this;
1941                 }
1942
1943                 public override void Emit (EmitContext ec)
1944                 {
1945                         expr.Emit (ec);
1946                 }
1947
1948                 public override void EmitBranchable (EmitContext ec, Label target, bool on_true)
1949                 {
1950                         expr.EmitBranchable (ec, target, on_true);
1951                 }
1952
1953                 public override SLE.Expression MakeExpression (BuilderContext ctx)
1954                 {
1955                         return orig_expr.MakeExpression (ctx);
1956                 }
1957         }
1958
1959         //
1960         // Standard composite pattern
1961         //
1962         public abstract class CompositeExpression : Expression
1963         {
1964                 protected Expression expr;
1965
1966                 protected CompositeExpression (Expression expr)
1967                 {
1968                         this.expr = expr;
1969                         this.loc = expr.Location;
1970                 }
1971
1972                 public override Expression CreateExpressionTree (ResolveContext ec)
1973                 {
1974                         return expr.CreateExpressionTree (ec);
1975                 }
1976
1977                 public Expression Child {
1978                         get { return expr; }
1979                 }
1980
1981                 protected override Expression DoResolve (ResolveContext ec)
1982                 {
1983                         expr = expr.Resolve (ec);
1984                         if (expr != null) {
1985                                 type = expr.Type;
1986                                 eclass = expr.eclass;
1987                         }
1988
1989                         return this;
1990                 }
1991
1992                 public override void Emit (EmitContext ec)
1993                 {
1994                         expr.Emit (ec);
1995                 }
1996
1997                 public override bool IsNull {
1998                         get { return expr.IsNull; }
1999                 }
2000         }
2001
2002         //
2003         // Base of expressions used only to narrow resolve flow
2004         //
2005         public abstract class ShimExpression : Expression
2006         {
2007                 protected Expression expr;
2008
2009                 protected ShimExpression (Expression expr)
2010                 {
2011                         this.expr = expr;
2012                 }
2013
2014                 protected override void CloneTo (CloneContext clonectx, Expression t)
2015                 {
2016                         if (expr == null)
2017                                 return;
2018
2019                         ShimExpression target = (ShimExpression) t;
2020                         target.expr = expr.Clone (clonectx);
2021                 }
2022
2023                 public override Expression CreateExpressionTree (ResolveContext ec)
2024                 {
2025                         throw new NotSupportedException ("ET");
2026                 }
2027
2028                 public override void Emit (EmitContext ec)
2029                 {
2030                         throw new InternalErrorException ("Missing Resolve call");
2031                 }
2032
2033                 public Expression Expr {
2034                         get { return expr; }
2035                 }
2036         }
2037
2038         //
2039         // Unresolved type name expressions
2040         //
2041         public abstract class ATypeNameExpression : FullNamedExpression
2042         {
2043                 string name;
2044                 protected TypeArguments targs;
2045
2046                 protected ATypeNameExpression (string name, Location l)
2047                 {
2048                         this.name = name;
2049                         loc = l;
2050                 }
2051
2052                 protected ATypeNameExpression (string name, TypeArguments targs, Location l)
2053                 {
2054                         this.name = name;
2055                         this.targs = targs;
2056                         loc = l;
2057                 }
2058
2059                 protected ATypeNameExpression (string name, int arity, Location l)
2060                         : this (name, new UnboundTypeArguments (arity), l)
2061                 {
2062                 }
2063
2064                 #region Properties
2065
2066                 protected int Arity {
2067                         get {
2068                                 return targs == null ? 0 : targs.Count;
2069                         }
2070                 }
2071
2072                 public bool HasTypeArguments {
2073                         get {
2074                                 return targs != null && !targs.IsEmpty;
2075                         }
2076                 }
2077
2078                 public string Name {
2079                         get {
2080                                 return name;
2081                         }
2082                         set {
2083                                 name = value;
2084                         }
2085                 }
2086
2087                 public TypeArguments TypeArguments {
2088                         get {
2089                                 return targs;
2090                         }
2091                 }
2092
2093                 #endregion
2094
2095                 public override bool Equals (object obj)
2096                 {
2097                         ATypeNameExpression atne = obj as ATypeNameExpression;
2098                         return atne != null && atne.Name == Name &&
2099                                 (targs == null || targs.Equals (atne.targs));
2100                 }
2101
2102                 public override int GetHashCode ()
2103                 {
2104                         return Name.GetHashCode ();
2105                 }
2106
2107                 // TODO: Move it to MemberCore
2108                 public static string GetMemberType (MemberCore mc)
2109                 {
2110                         if (mc is Property)
2111                                 return "property";
2112                         if (mc is Indexer)
2113                                 return "indexer";
2114                         if (mc is FieldBase)
2115                                 return "field";
2116                         if (mc is MethodCore)
2117                                 return "method";
2118                         if (mc is EnumMember)
2119                                 return "enum";
2120                         if (mc is Event)
2121                                 return "event";
2122
2123                         return "type";
2124                 }
2125
2126                 public override string GetSignatureForError ()
2127                 {
2128                         if (targs != null) {
2129                                 return Name + "<" + targs.GetSignatureForError () + ">";
2130                         }
2131
2132                         return Name;
2133                 }
2134
2135                 public abstract Expression LookupNameExpression (ResolveContext rc, MemberLookupRestrictions restriction);
2136         }
2137
2138         /// <summary>
2139         ///   SimpleName expressions are formed of a single word and only happen at the beginning
2140         ///   of a dotted-name.
2141         /// </summary>
2142         public class SimpleName : ATypeNameExpression
2143         {
2144                 public SimpleName (string name, Location l)
2145                         : base (name, l)
2146                 {
2147                 }
2148
2149                 public SimpleName (string name, TypeArguments args, Location l)
2150                         : base (name, args, l)
2151                 {
2152                 }
2153
2154                 public SimpleName (string name, int arity, Location l)
2155                         : base (name, arity, l)
2156                 {
2157                 }
2158
2159                 public SimpleName GetMethodGroup ()
2160                 {
2161                         return new SimpleName (Name, targs, loc);
2162                 }
2163
2164                 protected virtual void Error_TypeOrNamespaceNotFound (IMemberContext ec)
2165                 {
2166                         if (ec.CurrentType != null) {
2167                                 if (ec.CurrentMemberDefinition != null) {
2168                                         MemberCore mc = ec.CurrentMemberDefinition.Parent.GetDefinition (Name);
2169                                         if (mc != null) {
2170                                                 Error_UnexpectedKind (ec.Module.Compiler.Report, mc, "type", GetMemberType (mc), loc);
2171                                                 return;
2172                                         }
2173                                 }
2174
2175                                 /*
2176                                                                 // TODO MemberCache: Implement
2177
2178                                                                 string ns = ec.CurrentType.Namespace;
2179                                                                 string fullname = (ns.Length > 0) ? ns + "." + Name : Name;
2180                                                                 foreach (Assembly a in GlobalRootNamespace.Instance.Assemblies) {
2181                                                                         var type = a.GetType (fullname);
2182                                                                         if (type != null) {
2183                                                                                 ec.Compiler.Report.SymbolRelatedToPreviousError (type);
2184                                                                                 Expression.ErrorIsInaccesible (loc, TypeManager.CSharpName (type), ec.Compiler.Report);
2185                                                                                 return;
2186                                                                         }
2187                                                                 }
2188
2189                                                                 if (ec.CurrentTypeDefinition != null) {
2190                                                                         TypeSpec t = ec.CurrentTypeDefinition.LookupAnyGeneric (Name);
2191                                                                         if (t != null) {
2192                                                                                 Namespace.Error_InvalidNumberOfTypeArguments (ec.Compiler.Report, t, loc);
2193                                                                                 return;
2194                                                                         }
2195                                                                 }
2196                                 */
2197                         }
2198
2199                         FullNamedExpression retval = ec.LookupNamespaceOrType (Name, -System.Math.Max (1, Arity), loc, true);
2200                         if (retval != null) {
2201                                 Error_TypeArgumentsCannotBeUsed (ec.Module.Compiler.Report, loc, retval.Type, Arity);
2202 /*
2203                                 var te = retval as TypeExpr;
2204                                 if (HasTypeArguments && te != null && !te.Type.IsGeneric)
2205                                         retval.Error_TypeArgumentsCannotBeUsed (ec.Compiler.Report, loc);
2206                                 else
2207                                         Namespace.Error_InvalidNumberOfTypeArguments (ec.Compiler.Report, retval.Type, loc);
2208 */
2209                                 return;
2210                         }
2211
2212                         NamespaceEntry.Error_NamespaceNotFound (loc, Name, ec.Module.Compiler.Report);
2213                 }
2214
2215                 protected override Expression DoResolve (ResolveContext ec)
2216                 {
2217                         return SimpleNameResolve (ec, null, false);
2218                 }
2219
2220                 public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
2221                 {
2222                         return SimpleNameResolve (ec, right_side, false);
2223                 }
2224
2225                 public override FullNamedExpression ResolveAsTypeStep (IMemberContext ec, bool silent)
2226                 {
2227                         int errors = ec.Module.Compiler.Report.Errors;
2228                         FullNamedExpression fne = ec.LookupNamespaceOrType (Name, Arity, loc, /*ignore_cs0104=*/ false);
2229
2230                         if (fne != null) {
2231                                 if (fne.Type != null && Arity > 0) {
2232                                         if (HasTypeArguments) {
2233                                                 GenericTypeExpr ct = new GenericTypeExpr (fne.Type, targs, loc);
2234                                                 return ct.ResolveAsTypeStep (ec, false);
2235                                         }
2236
2237                                         return new GenericOpenTypeExpr (fne.Type, loc);
2238                                 }
2239
2240                                 //
2241                                 // dynamic namespace is ignored when dynamic is allowed (does not apply to types)
2242                                 //
2243                                 if (!(fne is Namespace))
2244                                         return fne;
2245                         }
2246
2247                         if (Arity == 0 && Name == "dynamic" && ec.Module.Compiler.Settings.Version > LanguageVersion.V_3) {
2248                                 if (!ec.Module.PredefinedAttributes.Dynamic.IsDefined) {
2249                                         ec.Module.Compiler.Report.Error (1980, Location,
2250                                                 "Dynamic keyword requires `{0}' to be defined. Are you missing System.Core.dll assembly reference?",
2251                                                 ec.Module.PredefinedAttributes.Dynamic.GetSignatureForError ());
2252                                 }
2253
2254                                 return new DynamicTypeExpr (loc);
2255                         }
2256
2257                         if (fne != null)
2258                                 return fne;
2259
2260                         if (silent || errors != ec.Module.Compiler.Report.Errors)
2261                                 return null;
2262
2263                         Error_TypeOrNamespaceNotFound (ec);
2264                         return null;
2265                 }
2266
2267                 public override Expression LookupNameExpression (ResolveContext rc, MemberLookupRestrictions restrictions)
2268                 {
2269                         int lookup_arity = Arity;
2270                         bool errorMode = false;
2271                         Expression e;
2272                         Block current_block = rc.CurrentBlock;
2273                         INamedBlockVariable variable = null;
2274                         bool variable_found = false;
2275
2276                         while (true) {
2277                                 //
2278                                 // Stage 1: binding to local variables or parameters
2279                                 //
2280                                 // LAMESPEC: It should take invocableOnly into account but that would break csc compatibility
2281                                 //
2282                                 if (current_block != null && lookup_arity == 0) {
2283                                         if (current_block.ParametersBlock.TopBlock.GetLocalName (Name, current_block.Original, ref variable)) {
2284                                                 if (!variable.IsDeclared) {
2285                                                         // We found local name in accessible block but it's not
2286                                                         // initialized yet, maybe the user wanted to bind to something else
2287                                                         errorMode = true;
2288                                                         variable_found = true;
2289                                                 } else {
2290                                                         e = variable.CreateReferenceExpression (rc, loc);
2291                                                         if (e != null) {
2292                                                                 if (Arity > 0)
2293                                                                         Error_TypeArgumentsCannotBeUsed (rc.Report, "variable", Name, loc);
2294
2295                                                                 return e;
2296                                                         }
2297                                                 }
2298                                         }
2299                                 }
2300
2301                                 //
2302                                 // Stage 2: Lookup members if we are inside a type up to top level type for nested types
2303                                 //
2304                                 TypeSpec member_type = rc.CurrentType;
2305                                 TypeSpec current_type = member_type;
2306                                 for (; member_type != null; member_type = member_type.DeclaringType) {
2307                                         e = MemberLookup (errorMode ? null : rc, current_type, member_type, Name, lookup_arity, restrictions, loc);
2308                                         if (e == null)
2309                                                 continue;
2310
2311                                         var me = e as MemberExpr;
2312                                         if (me == null) {
2313                                                 // The name matches a type, defer to ResolveAsTypeStep
2314                                                 if (e is TypeExpr)
2315                                                         break;
2316
2317                                                 continue;
2318                                         }
2319
2320                                         if (errorMode) {
2321                                                 if (variable != null) {
2322                                                         if (me is FieldExpr || me is ConstantExpr || me is EventExpr || me is PropertyExpr) {
2323                                                                 rc.Report.Error (844, loc,
2324                                                                         "A local variable `{0}' cannot be used before it is declared. Consider renaming the local variable when it hides the member `{1}'",
2325                                                                         Name, me.GetSignatureForError ());
2326                                                         } else {
2327                                                                 break;
2328                                                         }
2329                                                 } else if (me is MethodGroupExpr) {
2330                                                         // Leave it to overload resolution to report correct error
2331                                                 } else {
2332                                                         // TODO: rc.Report.SymbolRelatedToPreviousError ()
2333                                                         ErrorIsInaccesible (rc, me.GetSignatureForError (), loc);
2334                                                 }
2335                                         } else {
2336                                                 // LAMESPEC: again, ignores InvocableOnly
2337                                                 if (variable != null) {
2338                                                         rc.Report.SymbolRelatedToPreviousError (variable.Location, Name);
2339                                                         rc.Report.Error (135, loc, "`{0}' conflicts with a declaration in a child block", Name);
2340                                                 }
2341
2342                                                 //
2343                                                 // MemberLookup does not check accessors availability, this is actually needed for properties only
2344                                                 //
2345                                                 var pe = me as PropertyExpr;
2346                                                 if (pe != null) {
2347
2348                                                         // Break as there is no other overload available anyway
2349                                                         if ((restrictions & MemberLookupRestrictions.ReadAccess) != 0) {
2350                                                                 if (!pe.PropertyInfo.HasGet || !pe.PropertyInfo.Get.IsAccessible (current_type))
2351                                                                         break;
2352
2353                                                                 pe.Getter = pe.PropertyInfo.Get;
2354                                                         } else {
2355                                                                 if (!pe.PropertyInfo.HasSet || !pe.PropertyInfo.Set.IsAccessible (current_type))
2356                                                                         break;
2357
2358                                                                 pe.Setter = pe.PropertyInfo.Set;
2359                                                         }
2360                                                 }
2361                                         }
2362
2363                                         // TODO: It's used by EventExpr -> FieldExpr transformation only
2364                                         // TODO: Should go to MemberAccess
2365                                         me = me.ResolveMemberAccess (rc, null, null);
2366
2367                                         if (Arity > 0) {
2368                                                 targs.Resolve (rc);
2369                                                 me.SetTypeArguments (rc, targs);
2370                                         }
2371
2372                                         return me;
2373                                 }
2374
2375                                 //
2376                                 // Stage 3: Lookup nested types, namespaces and type parameters in the context
2377                                 //
2378                                 if ((restrictions & MemberLookupRestrictions.InvocableOnly) == 0 && !variable_found) {
2379                                         e = ResolveAsTypeStep (rc, lookup_arity == 0 || !errorMode);
2380                                         if (e != null) {
2381                                                 if (variable != null) {
2382                                                         rc.Report.SymbolRelatedToPreviousError (variable.Location, Name);
2383                                                         rc.Report.Error (135, loc, "`{0}' conflicts with a declaration in a child block", Name);
2384                                                 }
2385
2386                                                 return e;
2387                                         }
2388                                 }
2389
2390                                 if (errorMode) {
2391                                         if (variable_found) {
2392                                                 rc.Report.Error (841, loc, "A local variable `{0}' cannot be used before it is declared", Name);
2393                                         } else {
2394                                                 rc.Report.Error (103, loc, "The name `{0}' does not exist in the current context", Name);
2395                                         }
2396
2397                                         return null;
2398                                 }
2399
2400                                 if (rc.Module.Evaluator != null) {
2401                                         var fi = rc.Module.Evaluator.LookupField (Name);
2402                                         if (fi != null)
2403                                                 return new FieldExpr (fi.Item1, loc);
2404                                 }
2405
2406                                 lookup_arity = 0;
2407                                 restrictions &= ~MemberLookupRestrictions.InvocableOnly;
2408                                 errorMode = true;
2409                         }
2410                 }
2411
2412                 Expression SimpleNameResolve (ResolveContext ec, Expression right_side, bool intermediate)
2413                 {
2414                         Expression e = LookupNameExpression (ec, right_side == null ? MemberLookupRestrictions.ReadAccess : MemberLookupRestrictions.None);
2415
2416                         if (e == null)
2417                                 return null;
2418
2419                         if (right_side != null) {
2420                                 if (e is TypeExpr) {
2421                                     e.Error_UnexpectedKind (ec, ResolveFlags.VariableOrValue, loc);
2422                                     return null;
2423                                 }
2424
2425                                 e = e.ResolveLValue (ec, right_side);
2426                         } else {
2427                                 e = e.Resolve (ec);
2428                         }
2429
2430                         //if (ec.CurrentBlock == null || ec.CurrentBlock.CheckInvariantMeaningInBlock (Name, e, Location))
2431                         return e;
2432                 }
2433         }
2434
2435         /// <summary>
2436         ///   Represents a namespace or a type.  The name of the class was inspired by
2437         ///   section 10.8.1 (Fully Qualified Names).
2438         /// </summary>
2439         public abstract class FullNamedExpression : Expression
2440         {
2441                 protected override void CloneTo (CloneContext clonectx, Expression target)
2442                 {
2443                         // Do nothing, most unresolved type expressions cannot be
2444                         // resolved to different type
2445                 }
2446
2447                 public override Expression CreateExpressionTree (ResolveContext ec)
2448                 {
2449                         throw new NotSupportedException ("ET");
2450                 }
2451
2452                 public override FullNamedExpression ResolveAsTypeStep (IMemberContext ec, bool silent)
2453                 {
2454                         return this;
2455                 }
2456
2457                 public override void Emit (EmitContext ec)
2458                 {
2459                         throw new InternalErrorException ("FullNamedExpression `{0}' found in resolved tree",
2460                                 GetSignatureForError ());
2461                 }
2462         }
2463
2464         /// <summary>
2465         ///   Expression that evaluates to a type
2466         /// </summary>
2467         public abstract class TypeExpr : FullNamedExpression {
2468                 public override FullNamedExpression ResolveAsTypeStep (IMemberContext ec, bool silent)
2469                 {
2470                         TypeExpr t = DoResolveAsTypeStep (ec);
2471                         if (t == null)
2472                                 return null;
2473
2474                         eclass = ExprClass.Type;
2475                         return t;
2476                 }
2477
2478                 protected override Expression DoResolve (ResolveContext ec)
2479                 {
2480                         return ResolveAsTypeTerminal (ec, false);
2481                 }
2482
2483                 protected abstract TypeExpr DoResolveAsTypeStep (IMemberContext ec);
2484
2485                 public override bool Equals (object obj)
2486                 {
2487                         TypeExpr tobj = obj as TypeExpr;
2488                         if (tobj == null)
2489                                 return false;
2490
2491                         return Type == tobj.Type;
2492                 }
2493
2494                 public override int GetHashCode ()
2495                 {
2496                         return Type.GetHashCode ();
2497                 }
2498         }
2499
2500         /// <summary>
2501         ///   Fully resolved Expression that already evaluated to a type
2502         /// </summary>
2503         public class TypeExpression : TypeExpr {
2504                 public TypeExpression (TypeSpec t, Location l)
2505                 {
2506                         Type = t;
2507                         eclass = ExprClass.Type;
2508                         loc = l;
2509                 }
2510
2511                 protected override TypeExpr DoResolveAsTypeStep (IMemberContext ec)
2512                 {
2513                         return this;
2514                 }
2515
2516                 public override TypeExpr ResolveAsTypeTerminal (IMemberContext ec, bool silent)
2517                 {
2518                         return this;
2519                 }
2520         }
2521
2522         /// <summary>
2523         ///   This class denotes an expression which evaluates to a member
2524         ///   of a struct or a class.
2525         /// </summary>
2526         public abstract class MemberExpr : Expression
2527         {
2528                 //
2529                 // An instance expression associated with this member, if it's a
2530                 // non-static member
2531                 //
2532                 public Expression InstanceExpression;
2533
2534                 /// <summary>
2535                 ///   The name of this member.
2536                 /// </summary>
2537                 public abstract string Name {
2538                         get;
2539                 }
2540
2541                 //
2542                 // When base.member is used
2543                 //
2544                 public bool IsBase {
2545                         get { return InstanceExpression is BaseThis; }
2546                 }
2547
2548                 /// <summary>
2549                 ///   Whether this is an instance member.
2550                 /// </summary>
2551                 public abstract bool IsInstance {
2552                         get;
2553                 }
2554
2555                 /// <summary>
2556                 ///   Whether this is a static member.
2557                 /// </summary>
2558                 public abstract bool IsStatic {
2559                         get;
2560                 }
2561
2562                 // TODO: Not needed
2563                 protected abstract TypeSpec DeclaringType {
2564                         get;
2565                 }
2566
2567                 //
2568                 // Converts best base candidate for virtual method starting from QueriedBaseType
2569                 //
2570                 protected MethodSpec CandidateToBaseOverride (ResolveContext rc, MethodSpec method)
2571                 {
2572                         //
2573                         // Only when base.member is used and method is virtual
2574                         //
2575                         if (!IsBase)
2576                                 return method;
2577
2578                         //
2579                         // Overload resulution works on virtual or non-virtual members only (no overrides). That
2580                         // means for base.member access we have to find the closest match after we found best candidate
2581                         //
2582                         if ((method.Modifiers & (Modifiers.ABSTRACT | Modifiers.VIRTUAL | Modifiers.STATIC)) != Modifiers.STATIC) {
2583                                 //
2584                                 // The method could already be what we are looking for
2585                                 //
2586                                 TypeSpec[] targs = null;
2587                                 if (method.DeclaringType != InstanceExpression.Type) {
2588                                         var base_override = MemberCache.FindMember (InstanceExpression.Type, new MemberFilter (method), BindingRestriction.InstanceOnly) as MethodSpec;
2589                                         if (base_override != null && base_override.DeclaringType != method.DeclaringType) {
2590                                                 if (base_override.IsGeneric)
2591                                                         targs = method.TypeArguments;
2592
2593                                                 method = base_override;
2594                                         }
2595                                 }
2596
2597                                 // TODO: For now we do it for any hoisted call even if it's needed for
2598                                 // hoisted stories only but that requires a new expression wrapper
2599                                 if (rc.CurrentAnonymousMethod != null) {
2600                                         if (targs == null && method.IsGeneric) {
2601                                                 targs = method.TypeArguments;
2602                                                 method = method.GetGenericMethodDefinition ();
2603                                         }
2604
2605                                         if (method.Parameters.HasArglist)
2606                                                 throw new NotImplementedException ("__arglist base call proxy");
2607
2608                                         method = rc.CurrentMemberDefinition.Parent.PartialContainer.CreateHoistedBaseCallProxy (rc, method);
2609
2610                                         // Ideally this should apply to any proxy rewrite but in the case of unary mutators on
2611                                         // get/set member expressions second call would fail to proxy because left expression
2612                                         // would be of 'this' and not 'base'
2613                                         if (rc.CurrentType.IsStruct)
2614                                                 InstanceExpression = new This (loc).Resolve (rc);
2615                                 }
2616
2617                                 if (targs != null)
2618                                         method = method.MakeGenericMethod (rc, targs);
2619                         }
2620
2621                         //
2622                         // Only base will allow this invocation to happen.
2623                         //
2624                         if (method.IsAbstract) {
2625                                 Error_CannotCallAbstractBase (rc, method.GetSignatureForError ());
2626                         }
2627
2628                         return method;
2629                 }
2630
2631                 protected void CheckProtectedMemberAccess<T> (ResolveContext rc, T member) where T : MemberSpec
2632                 {
2633                         if (InstanceExpression == null)
2634                                 return;
2635
2636                         if ((member.Modifiers & Modifiers.PROTECTED) != 0 && !(InstanceExpression is This)) {
2637                                 var ct = rc.CurrentType;
2638                                 var expr_type = InstanceExpression.Type;
2639                                 if (ct == expr_type)
2640                                         return;
2641
2642                                 if ((member.Modifiers & Modifiers.INTERNAL) != 0 && expr_type.MemberDefinition.IsInternalAsPublic (ct.MemberDefinition.DeclaringAssembly))
2643                                         return;
2644
2645                                 expr_type = expr_type.GetDefinition ();
2646                                 if (ct != expr_type && !IsSameOrBaseQualifier (ct, expr_type)) {
2647                                         rc.Report.SymbolRelatedToPreviousError (member);
2648                                         rc.Report.Error (1540, loc,
2649                                                 "Cannot access protected member `{0}' via a qualifier of type `{1}'. The qualifier must be of type `{2}' or derived from it",
2650                                                 member.GetSignatureForError (), expr_type.GetSignatureForError (), ct.GetSignatureForError ());
2651                                 }
2652                         }
2653                 }
2654
2655                 static bool IsSameOrBaseQualifier (TypeSpec type, TypeSpec qtype)
2656                 {
2657                         do {
2658                                 type = type.GetDefinition ();
2659
2660                                 if (type == qtype || TypeManager.IsFamilyAccessible (qtype, type))
2661                                         return true;
2662
2663                                 type = type.DeclaringType;
2664                         } while (type != null);
2665
2666                         return false;
2667                 }
2668
2669                 protected void DoBestMemberChecks<T> (ResolveContext rc, T member) where T : MemberSpec, IInterfaceMemberSpec
2670                 {
2671                         if (InstanceExpression != null) {
2672                                 InstanceExpression = InstanceExpression.Resolve (rc);
2673                                 CheckProtectedMemberAccess (rc, member);
2674                         }
2675
2676                         if (member.MemberType.IsPointer && !rc.IsUnsafe) {
2677                                 UnsafeError (rc, loc);
2678                         }
2679
2680                         var dep = member.GetMissingDependencies ();
2681                         if (dep != null) {
2682                                 ImportedTypeDefinition.Error_MissingDependency (rc, dep, loc);
2683                         }
2684
2685                         if (!rc.IsObsolete) {
2686                                 ObsoleteAttribute oa = member.GetAttributeObsolete ();
2687                                 if (oa != null)
2688                                         AttributeTester.Report_ObsoleteMessage (oa, member.GetSignatureForError (), loc, rc.Report);
2689                         }
2690
2691                         if (!(member is FieldSpec))
2692                                 member.MemberDefinition.SetIsUsed ();
2693                 }
2694
2695                 protected virtual void Error_CannotCallAbstractBase (ResolveContext rc, string name)
2696                 {
2697                         rc.Report.Error (205, loc, "Cannot call an abstract base member `{0}'", name);
2698                 }
2699
2700                 //
2701                 // Implements identicial simple name and type-name
2702                 //
2703                 public Expression ProbeIdenticalTypeName (ResolveContext rc, Expression left, SimpleName name)
2704                 {
2705                         var t = left.Type;
2706                         if (t.Kind == MemberKind.InternalCompilerType || t is ElementTypeSpec || t.Arity > 0)
2707                                 return left;
2708
2709                         // 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
2710                         // a constant, field, property, local variable, or parameter with the same type as the meaning of E as a type-name
2711
2712                         if (left is MemberExpr || left is VariableReference) {
2713                                 rc.Report.DisableReporting ();
2714                                 Expression identical_type = rc.LookupNamespaceOrType (name.Name, 0, loc, true) as TypeExpr;
2715                                 rc.Report.EnableReporting ();
2716                                 if (identical_type != null && identical_type.Type == left.Type)
2717                                         return identical_type;
2718                         }
2719
2720                         return left;
2721                 }
2722
2723                 public bool ResolveInstanceExpression (ResolveContext rc, Expression rhs)
2724                 {
2725                         if (IsStatic) {
2726                                 if (InstanceExpression != null) {
2727                                         if (InstanceExpression is TypeExpr) {
2728                                                 var t = InstanceExpression.Type;
2729                                                 do {
2730                                                         ObsoleteAttribute oa = t.GetAttributeObsolete ();
2731                                                         if (oa != null && !rc.IsObsolete) {
2732                                                                 AttributeTester.Report_ObsoleteMessage (oa, t.GetSignatureForError (), loc, rc.Report);
2733                                                         }
2734
2735                                                         t = t.DeclaringType;
2736                                                 } while (t != null);
2737                                         } else {
2738                                                 var runtime_expr = InstanceExpression as RuntimeValueExpression;
2739                                                 if (runtime_expr == null || !runtime_expr.IsSuggestionOnly) {
2740                                                         rc.Report.Error (176, loc,
2741                                                                 "Static member `{0}' cannot be accessed with an instance reference, qualify it with a type name instead",
2742                                                                 GetSignatureForError ());
2743                                                 }
2744                                         }
2745
2746                                         InstanceExpression = null;
2747                                 }
2748
2749                                 return false;
2750                         }
2751
2752                         if (InstanceExpression == null || InstanceExpression is TypeExpr) {
2753                                 if (InstanceExpression != null || !This.IsThisAvailable (rc, true)) {
2754                                         if (rc.HasSet (ResolveContext.Options.FieldInitializerScope))
2755                                                 rc.Report.Error (236, loc,
2756                                                         "A field initializer cannot reference the nonstatic field, method, or property `{0}'",
2757                                                         GetSignatureForError ());
2758                                         else
2759                                                 rc.Report.Error (120, loc,
2760                                                         "An object reference is required to access non-static member `{0}'",
2761                                                         GetSignatureForError ());
2762
2763                                         return false;
2764                                 }
2765
2766                                 if (!TypeManager.IsFamilyAccessible (rc.CurrentType, DeclaringType)) {
2767                                         rc.Report.Error (38, loc,
2768                                                 "Cannot access a nonstatic member of outer type `{0}' via nested type `{1}'",
2769                                                 DeclaringType.GetSignatureForError (), rc.CurrentType.GetSignatureForError ());
2770                                 }
2771
2772                                 InstanceExpression = new This (loc);
2773                                 if (this is FieldExpr && rc.CurrentType.IsStruct) {
2774                                         using (rc.Set (ResolveContext.Options.OmitStructFlowAnalysis)) {
2775                                                 InstanceExpression = InstanceExpression.Resolve (rc);
2776                                         }
2777                                 } else {
2778                                         InstanceExpression = InstanceExpression.Resolve (rc);
2779                                 }
2780
2781                                 return false;
2782                         }
2783
2784                         var me = InstanceExpression as MemberExpr;
2785                         if (me != null) {
2786                                 me.ResolveInstanceExpression (rc, rhs);
2787
2788                                 var fe = me as FieldExpr;
2789                                 if (fe != null && fe.IsMarshalByRefAccess ()) {
2790                                         rc.Report.SymbolRelatedToPreviousError (me.DeclaringType);
2791                                         rc.Report.Warning (1690, 1, loc,
2792                                                 "Cannot call methods, properties, or indexers on `{0}' because it is a value type member of a marshal-by-reference class",
2793                                                 me.GetSignatureForError ());
2794                                 }
2795
2796                                 return true;
2797                         }
2798
2799                         //
2800                         // Run member-access postponed check once we know that
2801                         // the expression is not field expression which is the only
2802                         // expression which can use uninitialized this
2803                         //
2804                         if (InstanceExpression is This && !(this is FieldExpr) && rc.CurrentType.IsStruct) {
2805                                 ((This)InstanceExpression).CheckStructThisDefiniteAssignment (rc);
2806                         }
2807
2808                         //
2809                         // Additional checks for l-value member access
2810                         //
2811                         if (rhs != null) {
2812                                 //
2813                                 // TODO: It should be recursive but that would break csc compatibility
2814                                 //
2815                                 if (InstanceExpression is UnboxCast) {
2816                                         rc.Report.Error (445, InstanceExpression.Location, "Cannot modify the result of an unboxing conversion");
2817                                 }
2818                         }
2819
2820                         return true;
2821                 }
2822
2823                 public virtual MemberExpr ResolveMemberAccess (ResolveContext ec, Expression left, SimpleName original)
2824                 {
2825                         if (left != null && left.IsNull && TypeManager.IsReferenceType (left.Type)) {
2826                                 ec.Report.Warning (1720, 1, left.Location,
2827                                         "Expression will always cause a `{0}'", "System.NullReferenceException");
2828                         }
2829
2830                         InstanceExpression = left;
2831                         return this;
2832                 }
2833
2834                 protected void EmitInstance (EmitContext ec, bool prepare_for_load)
2835                 {
2836                         TypeSpec instance_type = InstanceExpression.Type;
2837                         if (TypeManager.IsValueType (instance_type)) {
2838                                 if (InstanceExpression is IMemoryLocation) {
2839                                         ((IMemoryLocation) InstanceExpression).AddressOf (ec, AddressOp.LoadStore);
2840                                 } else {
2841                                         LocalTemporary t = new LocalTemporary (instance_type);
2842                                         InstanceExpression.Emit (ec);
2843                                         t.Store (ec);
2844                                         t.AddressOf (ec, AddressOp.Store);
2845                                 }
2846                         } else {
2847                                 InstanceExpression.Emit (ec);
2848
2849                                 // Only to make verifier happy
2850                                 if (instance_type.IsGenericParameter && !(InstanceExpression is This) && TypeManager.IsReferenceType (instance_type))
2851                                         ec.Emit (OpCodes.Box, instance_type);
2852                         }
2853
2854                         if (prepare_for_load)
2855                                 ec.Emit (OpCodes.Dup);
2856                 }
2857
2858                 public abstract void SetTypeArguments (ResolveContext ec, TypeArguments ta);
2859         }
2860
2861         //
2862         // Represents a group of extension method candidates for whole namespace
2863         //
2864         class ExtensionMethodGroupExpr : MethodGroupExpr, OverloadResolver.IErrorHandler
2865         {
2866                 NamespaceEntry namespace_entry;
2867                 public readonly Expression ExtensionExpression;
2868
2869                 public ExtensionMethodGroupExpr (IList<MethodSpec> list, NamespaceEntry n, Expression extensionExpr, Location l)
2870                         : base (list.Cast<MemberSpec>().ToList (), extensionExpr.Type, l)
2871                 {
2872                         this.namespace_entry = n;
2873                         this.ExtensionExpression = extensionExpr;
2874                 }
2875
2876                 public override bool IsStatic {
2877                         get { return true; }
2878                 }
2879
2880                 public override IList<MemberSpec> GetBaseMembers (TypeSpec baseType)
2881                 {
2882                         if (namespace_entry == null)
2883                                 return null;
2884
2885                         //
2886                         // For extension methodgroup we are not looking for base members but parent
2887                         // namespace extension methods
2888                         //
2889                         int arity = type_arguments == null ? 0 : type_arguments.Count;
2890                         var found = namespace_entry.LookupExtensionMethod (DeclaringType, Name, arity, ref namespace_entry);
2891                         if (found == null)
2892                                 return null;
2893
2894                         return found.Cast<MemberSpec> ().ToList ();
2895                 }
2896
2897                 public override MethodGroupExpr LookupExtensionMethod (ResolveContext rc)
2898                 {
2899                         // We are already here
2900                         return null;
2901                 }
2902
2903                 public override MethodGroupExpr OverloadResolve (ResolveContext ec, ref Arguments arguments, OverloadResolver.IErrorHandler ehandler, OverloadResolver.Restrictions restr)
2904                 {
2905                         if (arguments == null)
2906                                 arguments = new Arguments (1);
2907
2908                         arguments.Insert (0, new Argument (ExtensionExpression, Argument.AType.ExtensionType));
2909                         var res = base.OverloadResolve (ec, ref arguments, ehandler ?? this, restr);
2910
2911                         // Store resolved argument and restore original arguments
2912                         if (res == null) {
2913                                 // Clean-up modified arguments for error reporting
2914                                 arguments.RemoveAt (0);
2915                                 return null;
2916                         }
2917
2918                         var me = ExtensionExpression as MemberExpr;
2919                         if (me != null)
2920                                 me.ResolveInstanceExpression (ec, null);
2921
2922                         InstanceExpression = null;
2923                         return this;
2924                 }
2925
2926                 #region IErrorHandler Members
2927
2928                 bool OverloadResolver.IErrorHandler.AmbiguousCandidates (ResolveContext rc, MemberSpec best, MemberSpec ambiguous)
2929                 {
2930                         return false;
2931                 }
2932
2933                 bool OverloadResolver.IErrorHandler.ArgumentMismatch (ResolveContext rc, MemberSpec best, Argument arg, int index)
2934                 {
2935                         rc.Report.SymbolRelatedToPreviousError (best);
2936                         rc.Report.Error (1928, loc,
2937                                 "Type `{0}' does not contain a member `{1}' and the best extension method overload `{2}' has some invalid arguments",
2938                                 queried_type.GetSignatureForError (), Name, best.GetSignatureForError ());
2939
2940                         if (index == 0) {
2941                                 rc.Report.Error (1929, loc,
2942                                         "Extension method instance type `{0}' cannot be converted to `{1}'",
2943                                         arg.Type.GetSignatureForError (), ((MethodSpec)best).Parameters.ExtensionMethodType.GetSignatureForError ());
2944                         }
2945
2946                         return true;
2947                 }
2948
2949                 bool OverloadResolver.IErrorHandler.NoArgumentMatch (ResolveContext rc, MemberSpec best)
2950                 {
2951                         return false;
2952                 }
2953
2954                 bool OverloadResolver.IErrorHandler.TypeInferenceFailed (ResolveContext rc, MemberSpec best)
2955                 {
2956                         return false;
2957                 }
2958
2959                 #endregion
2960         }
2961
2962         /// <summary>
2963         ///   MethodGroupExpr represents a group of method candidates which
2964         ///   can be resolved to the best method overload
2965         /// </summary>
2966         public class MethodGroupExpr : MemberExpr, OverloadResolver.IBaseMembersProvider
2967         {
2968                 protected IList<MemberSpec> Methods;
2969                 MethodSpec best_candidate;
2970                 TypeSpec best_candidate_return;
2971                 protected TypeArguments type_arguments;
2972
2973                 SimpleName simple_name;
2974                 protected TypeSpec queried_type;
2975
2976                 public MethodGroupExpr (IList<MemberSpec> mi, TypeSpec type, Location loc)
2977                 {
2978                         Methods = mi;
2979                         this.loc = loc;
2980                         this.type = InternalType.MethodGroup;
2981
2982                         eclass = ExprClass.MethodGroup;
2983                         queried_type = type;
2984                 }
2985
2986                 public MethodGroupExpr (MethodSpec m, TypeSpec type, Location loc)
2987                         : this (new MemberSpec[] { m }, type, loc)
2988                 {
2989                 }
2990
2991                 #region Properties
2992
2993                 public MethodSpec BestCandidate {
2994                         get {
2995                                 return best_candidate;
2996                         }
2997                 }
2998
2999                 public TypeSpec BestCandidateReturnType {
3000                         get {
3001                                 return best_candidate_return;
3002                         }
3003                 }
3004
3005                 protected override TypeSpec DeclaringType {
3006                         get {
3007                                 return queried_type;
3008                         }
3009                 }
3010
3011                 public override bool IsInstance {
3012                         get {
3013                                 if (best_candidate != null)
3014                                         return !best_candidate.IsStatic;
3015
3016                                 return false;
3017                         }
3018                 }
3019
3020                 public override bool IsStatic {
3021                         get {
3022                                 if (best_candidate != null)
3023                                         return best_candidate.IsStatic;
3024
3025                                 return false;
3026                         }
3027                 }
3028
3029                 public override string Name {
3030                         get {
3031                                 if (best_candidate != null)
3032                                         return best_candidate.Name;
3033
3034                                 // TODO: throw ?
3035                                 return Methods.First ().Name;
3036                         }
3037                 }
3038
3039                 #endregion
3040
3041                 //
3042                 // When best candidate is already know this factory can be used
3043                 // to avoid expensive overload resolution to be called
3044                 //
3045                 // NOTE: InstanceExpression has to be set manually
3046                 //
3047                 public static MethodGroupExpr CreatePredefined (MethodSpec best, TypeSpec queriedType, Location loc)
3048                 {
3049                         return new MethodGroupExpr (best, queriedType, loc) {
3050                                 best_candidate = best,
3051                                 best_candidate_return = best.ReturnType
3052                         };
3053                 }
3054
3055                 public override string GetSignatureForError ()
3056                 {
3057                         if (best_candidate != null)
3058                                 return best_candidate.GetSignatureForError ();
3059
3060                         return Methods.First ().GetSignatureForError ();
3061                 }
3062
3063                 public override Expression CreateExpressionTree (ResolveContext ec)
3064                 {
3065                         if (best_candidate == null) {
3066                                 ec.Report.Error (1953, loc, "An expression tree cannot contain an expression with method group");
3067                                 return null;
3068                         }
3069
3070                         if (best_candidate.IsConditionallyExcluded (loc))
3071                                 ec.Report.Error (765, loc,
3072                                         "Partial methods with only a defining declaration or removed conditional methods cannot be used in an expression tree");
3073
3074                         return new TypeOfMethod (best_candidate, loc);
3075                 }
3076
3077                 protected override Expression DoResolve (ResolveContext ec)
3078                 {
3079                         this.eclass = ExprClass.MethodGroup;
3080
3081                         if (InstanceExpression != null) {
3082                                 InstanceExpression = InstanceExpression.Resolve (ec);
3083                                 if (InstanceExpression == null)
3084                                         return null;
3085                         }
3086
3087                         return this;
3088                 }
3089
3090                 public override void Emit (EmitContext ec)
3091                 {
3092                         throw new NotSupportedException ();
3093                 }
3094
3095                 public void EmitCall (EmitContext ec, Arguments arguments)
3096                 {
3097                         Invocation.EmitCall (ec, InstanceExpression, best_candidate, arguments, loc);
3098                 }
3099
3100                 public override void Error_ValueCannotBeConverted (ResolveContext ec, Location loc, TypeSpec target, bool expl)
3101                 {
3102                         ec.Report.Error (428, loc, "Cannot convert method group `{0}' to non-delegate type `{1}'. Consider using parentheses to invoke the method",
3103                                 Name, TypeManager.CSharpName (target));
3104                 }
3105
3106                 public static bool IsExtensionMethodArgument (Expression expr)
3107                 {
3108                         //
3109                         // LAMESPEC: No details about which expressions are not allowed
3110                         //
3111                         return !(expr is TypeExpr) && !(expr is BaseThis);
3112                 }
3113
3114                 /// <summary>
3115                 ///   Find the Applicable Function Members (7.4.2.1)
3116                 ///
3117                 ///   me: Method Group expression with the members to select.
3118                 ///       it might contain constructors or methods (or anything
3119                 ///       that maps to a method).
3120                 ///
3121                 ///   Arguments: ArrayList containing resolved Argument objects.
3122                 ///
3123                 ///   loc: The location if we want an error to be reported, or a Null
3124                 ///        location for "probing" purposes.
3125                 ///
3126                 ///   Returns: The MethodBase (either a ConstructorInfo or a MethodInfo)
3127                 ///            that is the best match of me on Arguments.
3128                 ///
3129                 /// </summary>
3130                 public virtual MethodGroupExpr OverloadResolve (ResolveContext ec, ref Arguments args, OverloadResolver.IErrorHandler cerrors, OverloadResolver.Restrictions restr)
3131                 {
3132                         // TODO: causes issues with probing mode, remove explicit Kind check
3133                         if (best_candidate != null && best_candidate.Kind == MemberKind.Destructor)
3134                                 return this;
3135
3136                         var r = new OverloadResolver (Methods, type_arguments, restr, loc);
3137                         if ((restr & OverloadResolver.Restrictions.NoBaseMembers) == 0) {
3138                                 r.BaseMembersProvider = this;
3139                         }
3140
3141                         if (cerrors != null)
3142                                 r.CustomErrors = cerrors;
3143
3144                         // TODO: When in probing mode do IsApplicable only and when called again do VerifyArguments for full error reporting
3145                         best_candidate = r.ResolveMember<MethodSpec> (ec, ref args);
3146                         if (best_candidate == null)
3147                                 return r.BestCandidateIsDynamic ? this : null;
3148
3149                         // Overload resolver had to create a new method group, all checks bellow have already been executed
3150                         if (r.BestCandidateNewMethodGroup != null)
3151                                 return r.BestCandidateNewMethodGroup;
3152
3153                         if (best_candidate.Kind == MemberKind.Method && (restr & OverloadResolver.Restrictions.ProbingOnly) == 0) {
3154                                 if (InstanceExpression != null) {
3155                                         if (best_candidate.IsExtensionMethod && args[0].Expr == InstanceExpression) {
3156                                                 InstanceExpression = null;
3157                                         } else {
3158                                                 if (best_candidate.IsStatic && simple_name != null) {
3159                                                         InstanceExpression = ProbeIdenticalTypeName (ec, InstanceExpression, simple_name);
3160                                                 }
3161
3162                                                 InstanceExpression.Resolve (ec);
3163                                         }
3164                                 }
3165
3166                                 ResolveInstanceExpression (ec, null);
3167                                 if (InstanceExpression != null)
3168                                         CheckProtectedMemberAccess (ec, best_candidate);
3169                         }
3170
3171                         var base_override = CandidateToBaseOverride (ec, best_candidate);
3172                         if (base_override == best_candidate) {
3173                                 best_candidate_return = r.BestCandidateReturnType;
3174                         } else {
3175                                 best_candidate = base_override;
3176                                 best_candidate_return = best_candidate.ReturnType;
3177                         }
3178
3179                         return this;
3180                 }
3181
3182                 public override MemberExpr ResolveMemberAccess (ResolveContext ec, Expression left, SimpleName original)
3183                 {
3184                         simple_name = original;
3185                         return base.ResolveMemberAccess (ec, left, original);
3186                 }
3187
3188                 public override void SetTypeArguments (ResolveContext ec, TypeArguments ta)
3189                 {
3190                         type_arguments = ta;
3191                 }
3192
3193                 #region IBaseMembersProvider Members
3194
3195                 public virtual IList<MemberSpec> GetBaseMembers (TypeSpec baseType)
3196                 {
3197                         return baseType == null ? null : MemberCache.FindMembers (baseType, Methods [0].Name, false);
3198                 }
3199
3200                 public IParametersMember GetOverrideMemberParameters (MemberSpec member)
3201                 {
3202                         if (queried_type == member.DeclaringType)
3203                                 return null;
3204
3205                         return MemberCache.FindMember (queried_type, new MemberFilter ((MethodSpec) member),
3206                                 BindingRestriction.InstanceOnly | BindingRestriction.OverrideOnly) as IParametersMember;
3207                 }
3208
3209                 //
3210                 // Extension methods lookup after ordinary methods candidates failed to apply
3211                 //
3212                 public virtual MethodGroupExpr LookupExtensionMethod (ResolveContext rc)
3213                 {
3214                         if (InstanceExpression == null)
3215                                 return null;
3216
3217                         InstanceExpression = InstanceExpression.Resolve (rc);
3218                         if (!IsExtensionMethodArgument (InstanceExpression))
3219                                 return null;
3220
3221                         int arity = type_arguments == null ? 0 : type_arguments.Count;
3222                         NamespaceEntry methods_scope = null;
3223                         var methods = rc.LookupExtensionMethod (InstanceExpression.Type, Methods[0].Name, arity, ref methods_scope);
3224                         if (methods == null)
3225                                 return null;
3226
3227                         var emg = new ExtensionMethodGroupExpr (methods, methods_scope, InstanceExpression, loc);
3228                         emg.SetTypeArguments (rc, type_arguments);
3229                         return emg;
3230                 }
3231
3232                 #endregion
3233         }
3234
3235         public struct OverloadResolver
3236         {
3237                 [Flags]
3238                 public enum Restrictions
3239                 {
3240                         None = 0,
3241                         DelegateInvoke = 1,
3242                         ProbingOnly     = 1 << 1,
3243                         CovariantDelegate = 1 << 2,
3244                         NoBaseMembers = 1 << 3,
3245                         BaseMembersIncluded = 1 << 4
3246                 }
3247
3248                 public interface IBaseMembersProvider
3249                 {
3250                         IList<MemberSpec> GetBaseMembers (TypeSpec baseType);
3251                         IParametersMember GetOverrideMemberParameters (MemberSpec member);
3252                         MethodGroupExpr LookupExtensionMethod (ResolveContext rc);
3253                 }
3254
3255                 public interface IErrorHandler
3256                 {
3257                         bool AmbiguousCandidates (ResolveContext rc, MemberSpec best, MemberSpec ambiguous);
3258                         bool ArgumentMismatch (ResolveContext rc, MemberSpec best, Argument a, int index);
3259                         bool NoArgumentMatch (ResolveContext rc, MemberSpec best);
3260                         bool TypeInferenceFailed (ResolveContext rc, MemberSpec best);
3261                 }
3262
3263                 sealed class NoBaseMembers : IBaseMembersProvider
3264                 {
3265                         public static readonly IBaseMembersProvider Instance = new NoBaseMembers ();
3266
3267                         public IList<MemberSpec> GetBaseMembers (TypeSpec baseType)
3268                         {
3269                                 return null;
3270                         }
3271
3272                         public IParametersMember GetOverrideMemberParameters (MemberSpec member)
3273                         {
3274                                 return null;
3275                         }
3276
3277                         public MethodGroupExpr LookupExtensionMethod (ResolveContext rc)
3278                         {
3279                                 return null;
3280                         }
3281                 }
3282
3283                 struct AmbiguousCandidate
3284                 {
3285                         public readonly MemberSpec Member;
3286                         public readonly bool Expanded;
3287                         public readonly AParametersCollection Parameters;
3288
3289                         public AmbiguousCandidate (MemberSpec member, AParametersCollection parameters, bool expanded)
3290                         {
3291                                 Member = member;
3292                                 Parameters = parameters;
3293                                 Expanded = expanded;
3294                         }
3295                 }
3296
3297                 Location loc;
3298                 IList<MemberSpec> members;
3299                 TypeArguments type_arguments;
3300                 IBaseMembersProvider base_provider;
3301                 IErrorHandler custom_errors;
3302                 Restrictions restrictions;
3303                 MethodGroupExpr best_candidate_extension_group;
3304                 TypeSpec best_candidate_return_type;
3305
3306                 SessionReportPrinter lambda_conv_msgs;
3307                 ReportPrinter prev_recorder;
3308
3309                 public OverloadResolver (IList<MemberSpec> members, Restrictions restrictions, Location loc)
3310                         : this (members, null, restrictions, loc)
3311                 {
3312                 }
3313
3314                 public OverloadResolver (IList<MemberSpec> members, TypeArguments targs, Restrictions restrictions, Location loc)
3315                         : this ()
3316                 {
3317                         if (members == null || members.Count == 0)
3318                                 throw new ArgumentException ("empty members set");
3319
3320                         this.members = members;
3321                         this.loc = loc;
3322                         type_arguments = targs;
3323                         this.restrictions = restrictions;
3324                         if (IsDelegateInvoke)
3325                                 this.restrictions |= Restrictions.NoBaseMembers;
3326
3327                         base_provider = NoBaseMembers.Instance;
3328                 }
3329
3330                 #region Properties
3331
3332                 public IBaseMembersProvider BaseMembersProvider {
3333                         get {
3334                                 return base_provider;
3335                         }
3336                         set {
3337                                 base_provider = value;
3338                         }
3339                 }
3340
3341                 public bool BestCandidateIsDynamic { get; set; }
3342
3343                 //
3344                 // Best candidate was found in newly created MethodGroupExpr, used by extension methods
3345                 //
3346                 public MethodGroupExpr BestCandidateNewMethodGroup {
3347                         get {
3348                                 return best_candidate_extension_group;
3349                         }
3350                 }
3351
3352                 //
3353                 // Return type can be different between best candidate and closest override
3354                 //
3355                 public TypeSpec BestCandidateReturnType {
3356                         get {
3357                                 return best_candidate_return_type;
3358                         }
3359                 }
3360
3361                 public IErrorHandler CustomErrors {
3362                         get {
3363                                 return custom_errors;
3364                         }
3365                         set {
3366                                 custom_errors = value;
3367                         }
3368                 }
3369
3370                 TypeSpec DelegateType {
3371                         get {
3372                                 if ((restrictions & Restrictions.DelegateInvoke) == 0)
3373                                         throw new InternalErrorException ("Not running in delegate mode", loc);
3374
3375                                 return members [0].DeclaringType;
3376                         }
3377                 }
3378
3379                 bool IsProbingOnly {
3380                         get {
3381                                 return (restrictions & Restrictions.ProbingOnly) != 0;
3382                         }
3383                 }
3384
3385                 bool IsDelegateInvoke {
3386                         get {
3387                                 return (restrictions & Restrictions.DelegateInvoke) != 0;
3388                         }
3389                 }
3390
3391                 #endregion
3392
3393                 //
3394                 //  7.4.3.3  Better conversion from expression
3395                 //  Returns :   1    if a->p is better,
3396                 //              2    if a->q is better,
3397                 //              0 if neither is better
3398                 //
3399                 static int BetterExpressionConversion (ResolveContext ec, Argument a, TypeSpec p, TypeSpec q)
3400                 {
3401                         TypeSpec argument_type = a.Type;
3402
3403                         //
3404                         // If argument is an anonymous function
3405                         //
3406                         if (argument_type == InternalType.AnonymousMethod && ec.Module.Compiler.Settings.Version > LanguageVersion.ISO_2) {
3407                                 //
3408                                 // p and q are delegate types or expression tree types
3409                                 //
3410                                 if (p.GetDefinition () == TypeManager.expression_type || q.GetDefinition () == TypeManager.expression_type) {
3411                                         if (q.MemberDefinition != p.MemberDefinition) {
3412                                                 return 0;
3413                                         }
3414
3415                                         //
3416                                         // Uwrap delegate from Expression<T>
3417                                         //
3418                                         q = TypeManager.GetTypeArguments (q)[0];
3419                                         p = TypeManager.GetTypeArguments (p)[0];
3420                                 }
3421
3422                                 var p_m = Delegate.GetInvokeMethod (p);
3423                                 var q_m = Delegate.GetInvokeMethod (q);
3424
3425                                 //
3426                                 // With identical parameter lists
3427                                 //
3428                                 if (!TypeSpecComparer.Equals (p_m.Parameters.Types,q_m.Parameters.Types))
3429                                         return 0;
3430
3431                                 p = p_m.ReturnType;
3432                                 q = q_m.ReturnType;
3433
3434                                 //
3435                                 // if p is void returning, and q has a return type Y, then C2 is the better conversion.
3436                                 //
3437                                 if (p.Kind == MemberKind.Void) {
3438                                         return q.Kind != MemberKind.Void ? 2 : 0;
3439                                 }
3440
3441                                 //
3442                                 // if p has a return type Y, and q is void returning, then C1 is the better conversion.
3443                                 //
3444                                 if (q.Kind == MemberKind.Void) {
3445                                         return p.Kind != MemberKind.Void ? 1: 0;
3446                                 }
3447                         } else {
3448                                 if (argument_type == p)
3449                                         return 1;
3450
3451                                 if (argument_type == q)
3452                                         return 2;
3453                         }
3454
3455                         return BetterTypeConversion (ec, p, q);
3456                 }
3457
3458                 //
3459                 // 7.4.3.4  Better conversion from type
3460                 //
3461                 public static int BetterTypeConversion (ResolveContext ec, TypeSpec p, TypeSpec q)
3462                 {
3463                         if (p == null || q == null)
3464                                 throw new InternalErrorException ("BetterTypeConversion got a null conversion");
3465
3466                         switch (p.BuildinType) {
3467                         case BuildinTypeSpec.Type.Int:
3468                                 if (q.BuildinType == BuildinTypeSpec.Type.UInt || q.BuildinType == BuildinTypeSpec.Type.ULong)
3469                                         return 1;
3470                                 break;
3471                         case BuildinTypeSpec.Type.Long:
3472                                 if (q.BuildinType == BuildinTypeSpec.Type.ULong)
3473                                         return 1;
3474                                 break;
3475                         case BuildinTypeSpec.Type.SByte:
3476                                 switch (q.BuildinType) {
3477                                 case BuildinTypeSpec.Type.Byte:
3478                                 case BuildinTypeSpec.Type.UShort:
3479                                 case BuildinTypeSpec.Type.UInt:
3480                                 case BuildinTypeSpec.Type.ULong:
3481                                         return 1;
3482                                 }
3483                                 break;
3484                         case BuildinTypeSpec.Type.Short:
3485                                 switch (q.BuildinType) {
3486                                 case BuildinTypeSpec.Type.UShort:
3487                                 case BuildinTypeSpec.Type.UInt:
3488                                 case BuildinTypeSpec.Type.ULong:
3489                                         return 1;
3490                                 }
3491                                 break;
3492                         case BuildinTypeSpec.Type.Dynamic:
3493                                 // Dynamic is never better
3494                                 return 2;
3495                         }
3496
3497                         switch (q.BuildinType) {
3498                         case BuildinTypeSpec.Type.Int:
3499                                 if (p.BuildinType == BuildinTypeSpec.Type.UInt || p.BuildinType == BuildinTypeSpec.Type.ULong)
3500                                         return 2;
3501                                 break;
3502                         case BuildinTypeSpec.Type.Long:
3503                                 if (p.BuildinType == BuildinTypeSpec.Type.ULong)
3504                                         return 2;
3505                                 break;
3506                         case BuildinTypeSpec.Type.SByte:
3507                                 switch (p.BuildinType) {
3508                                 case BuildinTypeSpec.Type.Byte:
3509                                 case BuildinTypeSpec.Type.UShort:
3510                                 case BuildinTypeSpec.Type.UInt:
3511                                 case BuildinTypeSpec.Type.ULong:
3512                                         return 2;
3513                                 }
3514                                 break;
3515                         case BuildinTypeSpec.Type.Short:
3516                                 switch (p.BuildinType) {
3517                                 case BuildinTypeSpec.Type.UShort:
3518                                 case BuildinTypeSpec.Type.UInt:
3519                                 case BuildinTypeSpec.Type.ULong:
3520                                         return 2;
3521                                 }
3522                                 break;
3523                         case BuildinTypeSpec.Type.Dynamic:
3524                                 // Dynamic is never better
3525                                 return 1;
3526                         }
3527
3528                         // FIXME: handle lifted operators
3529
3530                         // TODO: this is expensive
3531                         Expression p_tmp = new EmptyExpression (p);
3532                         Expression q_tmp = new EmptyExpression (q);
3533
3534                         bool p_to_q = Convert.ImplicitConversionExists (ec, p_tmp, q);
3535                         bool q_to_p = Convert.ImplicitConversionExists (ec, q_tmp, p);
3536
3537                         if (p_to_q && !q_to_p)
3538                                 return 1;
3539
3540                         if (q_to_p && !p_to_q)
3541                                 return 2;
3542
3543                         return 0;
3544                 }
3545
3546                 /// <summary>
3547                 ///   Determines "Better function" between candidate
3548                 ///   and the current best match
3549                 /// </summary>
3550                 /// <remarks>
3551                 ///    Returns a boolean indicating :
3552                 ///     false if candidate ain't better
3553                 ///     true  if candidate is better than the current best match
3554                 /// </remarks>
3555                 static bool BetterFunction (ResolveContext ec, Arguments args, MemberSpec candidate, AParametersCollection cparam, bool candidate_params,
3556                         MemberSpec best, AParametersCollection bparam, bool best_params)
3557                 {
3558                         AParametersCollection candidate_pd = ((IParametersMember) candidate).Parameters;
3559                         AParametersCollection best_pd = ((IParametersMember) best).Parameters;
3560
3561                         bool better_at_least_one = false;
3562                         bool same = true;
3563                         int args_count = args == null ? 0 : args.Count;
3564                         int j = 0;
3565                         Argument a = null;
3566                         TypeSpec ct, bt;
3567                         for (int c_idx = 0, b_idx = 0; j < args_count; ++j, ++c_idx, ++b_idx) {
3568                                 a = args[j];
3569
3570                                 // Default arguments are ignored for better decision
3571                                 if (a.IsDefaultArgument)
3572                                         break;
3573
3574                                 //
3575                                 // When comparing named argument the parameter type index has to be looked up
3576                                 // in original parameter set (override version for virtual members)
3577                                 //
3578                                 NamedArgument na = a as NamedArgument;
3579                                 if (na != null) {
3580                                         int idx = cparam.GetParameterIndexByName (na.Name);
3581                                         ct = candidate_pd.Types[idx];
3582                                         if (candidate_params && candidate_pd.FixedParameters[idx].ModFlags == Parameter.Modifier.PARAMS)
3583                                                 ct = TypeManager.GetElementType (ct);
3584
3585                                         idx = bparam.GetParameterIndexByName (na.Name);
3586                                         bt = best_pd.Types[idx];
3587                                         if (best_params && best_pd.FixedParameters[idx].ModFlags == Parameter.Modifier.PARAMS)
3588                                                 bt = TypeManager.GetElementType (bt);
3589                                 } else {
3590                                         ct = candidate_pd.Types[c_idx];
3591                                         bt = best_pd.Types[b_idx];
3592
3593                                         if (candidate_params && candidate_pd.FixedParameters[c_idx].ModFlags == Parameter.Modifier.PARAMS) {
3594                                                 ct = TypeManager.GetElementType (ct);
3595                                                 --c_idx;
3596                                         }
3597
3598                                         if (best_params && best_pd.FixedParameters[b_idx].ModFlags == Parameter.Modifier.PARAMS) {
3599                                                 bt = TypeManager.GetElementType (bt);
3600                                                 --b_idx;
3601                                         }
3602                                 }
3603
3604                                 if (TypeSpecComparer.IsEqual (ct, bt))
3605                                         continue;
3606
3607                                 same = false;
3608                                 int result = BetterExpressionConversion (ec, a, ct, bt);
3609
3610                                 // for each argument, the conversion to 'ct' should be no worse than
3611                                 // the conversion to 'bt'.
3612                                 if (result == 2)
3613                                         return false;
3614
3615                                 // for at least one argument, the conversion to 'ct' should be better than
3616                                 // the conversion to 'bt'.
3617                                 if (result != 0)
3618                                         better_at_least_one = true;
3619                         }
3620
3621                         if (better_at_least_one)
3622                                 return true;
3623
3624                         //
3625                         // This handles the case
3626                         //
3627                         //   Add (float f1, float f2, float f3);
3628                         //   Add (params decimal [] foo);
3629                         //
3630                         // The call Add (3, 4, 5) should be ambiguous.  Without this check, the
3631                         // first candidate would've chosen as better.
3632                         //
3633                         if (!same && !a.IsDefaultArgument)
3634                                 return false;
3635
3636                         //
3637                         // The two methods have equal non-optional parameter types, apply tie-breaking rules
3638                         //
3639
3640                         //
3641                         // This handles the following cases:
3642                         //
3643                         //  Foo (int i) is better than Foo (int i, long l = 0)
3644                         //  Foo (params int[] args) is better than Foo (int i = 0, params int[] args)
3645                         //
3646                         // Prefer non-optional version
3647                         //
3648                         // LAMESPEC: Specification claims this should be done at last but the opposite is true
3649                         //
3650                         if (candidate_params == best_params && candidate_pd.Count != best_pd.Count) {
3651                                 if (candidate_pd.Count >= best_pd.Count)
3652                                         return false;
3653
3654                                 if (j < candidate_pd.Count && candidate_pd.FixedParameters[j].HasDefaultValue)
3655                                         return false;
3656
3657                                 return true;
3658                         }
3659
3660                         //
3661                         // One is a non-generic method and second is a generic method, then non-generic is better
3662                         //
3663                         if (best.IsGeneric != candidate.IsGeneric)
3664                                 return best.IsGeneric;
3665
3666                         //
3667                         // This handles the following cases:
3668                         //
3669                         //   Trim () is better than Trim (params char[] chars)
3670                         //   Concat (string s1, string s2, string s3) is better than
3671                         //     Concat (string s1, params string [] srest)
3672                         //   Foo (int, params int [] rest) is better than Foo (params int [] rest)
3673                         //
3674                         // Prefer non-expanded version
3675                         //
3676                         if (candidate_params != best_params)
3677                                 return best_params;
3678
3679                         int candidate_param_count = candidate_pd.Count;
3680                         int best_param_count = best_pd.Count;
3681
3682                         if (candidate_param_count != best_param_count)
3683                                 // can only happen if (candidate_params && best_params)
3684                                 return candidate_param_count > best_param_count && best_pd.HasParams;
3685
3686                         //
3687                         // Both methods have the same number of parameters, and the parameters have equal types
3688                         // Pick the "more specific" signature using rules over original (non-inflated) types
3689                         //
3690                         var candidate_def_pd = ((IParametersMember) candidate.MemberDefinition).Parameters;
3691                         var best_def_pd = ((IParametersMember) best.MemberDefinition).Parameters;
3692
3693                         bool specific_at_least_once = false;
3694                         for (j = 0; j < args_count; ++j) {
3695                                 NamedArgument na = args_count == 0 ? null : args [j] as NamedArgument;
3696                                 if (na != null) {
3697                                         ct = candidate_def_pd.Types[cparam.GetParameterIndexByName (na.Name)];
3698                                         bt = best_def_pd.Types[bparam.GetParameterIndexByName (na.Name)];
3699                                 } else {
3700                                         ct = candidate_def_pd.Types[j];
3701                                         bt = best_def_pd.Types[j];
3702                                 }
3703
3704                                 if (ct == bt)
3705                                         continue;
3706                                 TypeSpec specific = MoreSpecific (ct, bt);
3707                                 if (specific == bt)
3708                                         return false;
3709                                 if (specific == ct)
3710                                         specific_at_least_once = true;
3711                         }
3712
3713                         if (specific_at_least_once)
3714                                 return true;
3715
3716                         return false;
3717                 }
3718
3719                 public static void Error_ConstructorMismatch (ResolveContext rc, TypeSpec type, int argCount, Location loc)
3720                 {
3721                         rc.Report.Error (1729, loc,
3722                                 "The type `{0}' does not contain a constructor that takes `{1}' arguments",
3723                                 type.GetSignatureForError (), argCount.ToString ());
3724                 }
3725
3726                 //
3727                 // Determines if the candidate method is applicable to the given set of arguments
3728                 // There could be two different set of parameters for same candidate where one
3729                 // is the closest override for default values and named arguments checks and second
3730                 // one being the virtual base for the parameter types and modifiers.
3731                 //
3732                 // A return value rates candidate method compatibility,
3733                 // 0 = the best, int.MaxValue = the worst
3734                 //
3735                 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)
3736                 {
3737                         // Parameters of most-derived type used mainly for named and optional parameters
3738                         var pd = pm.Parameters;
3739
3740                         // Used for params modifier only, that's legacy of C# 1.0 which uses base type for
3741                         // params modifier instead of most-derived type
3742                         var cpd = ((IParametersMember) candidate).Parameters;
3743                         int param_count = pd.Count;
3744                         int optional_count = 0;
3745                         int score;
3746                         Arguments orig_args = arguments;
3747
3748                         if (arg_count != param_count) {
3749                                 for (int i = 0; i < pd.Count; ++i) {
3750                                         if (pd.FixedParameters[i].HasDefaultValue) {
3751                                                 optional_count = pd.Count - i;
3752                                                 break;
3753                                         }
3754                                 }
3755
3756                                 if (optional_count != 0) {
3757                                         // Readjust expected number when params used
3758                                         if (cpd.HasParams) {
3759                                                 optional_count--;
3760                                                 if (arg_count < param_count)
3761                                                         param_count--;
3762                                         } else if (arg_count > param_count) {
3763                                                 int args_gap = System.Math.Abs (arg_count - param_count);
3764                                                 return int.MaxValue - 10000 + args_gap;
3765                                         }
3766                                 } else if (arg_count != param_count) {
3767                                         int args_gap = System.Math.Abs (arg_count - param_count);
3768                                         if (!cpd.HasParams)
3769                                                 return int.MaxValue - 10000 + args_gap;
3770                                         if (arg_count < param_count - 1)
3771                                                 return int.MaxValue - 10000 + args_gap;
3772                                 }
3773
3774                                 // Resize to fit optional arguments
3775                                 if (optional_count != 0) {
3776                                         if (arguments == null) {
3777                                                 arguments = new Arguments (optional_count);
3778                                         } else {
3779                                                 // Have to create a new container, so the next run can do same
3780                                                 var resized = new Arguments (param_count);
3781                                                 resized.AddRange (arguments);
3782                                                 arguments = resized;
3783                                         }
3784
3785                                         for (int i = arg_count; i < param_count; ++i)
3786                                                 arguments.Add (null);
3787                                 }
3788                         }
3789
3790                         if (arg_count > 0) {
3791                                 //
3792                                 // Shuffle named arguments to the right positions if there are any
3793                                 //
3794                                 if (arguments[arg_count - 1] is NamedArgument) {
3795                                         arg_count = arguments.Count;
3796
3797                                         for (int i = 0; i < arg_count; ++i) {
3798                                                 bool arg_moved = false;
3799                                                 while (true) {
3800                                                         NamedArgument na = arguments[i] as NamedArgument;
3801                                                         if (na == null)
3802                                                                 break;
3803
3804                                                         int index = pd.GetParameterIndexByName (na.Name);
3805
3806                                                         // Named parameter not found
3807                                                         if (index < 0)
3808                                                                 return (i + 1) * 3;
3809
3810                                                         // already reordered
3811                                                         if (index == i)
3812                                                                 break;
3813
3814                                                         Argument temp;
3815                                                         if (index >= param_count) {
3816                                                                 // When using parameters which should not be available to the user
3817                                                                 if ((cpd.FixedParameters[index].ModFlags & Parameter.Modifier.PARAMS) == 0)
3818                                                                         break;
3819
3820                                                                 arguments.Add (null);
3821                                                                 ++arg_count;
3822                                                                 temp = null;
3823                                                         } else {
3824                                                                 temp = arguments[index];
3825
3826                                                                 // The slot has been taken by positional argument
3827                                                                 if (temp != null && !(temp is NamedArgument))
3828                                                                         break;
3829                                                         }
3830
3831                                                         if (!arg_moved) {
3832                                                                 arguments = arguments.MarkOrderedArgument (na);
3833                                                                 arg_moved = true;
3834                                                         }
3835
3836                                                         arguments[index] = arguments[i];
3837                                                         arguments[i] = temp;
3838
3839                                                         if (temp == null)
3840                                                                 break;
3841                                                 }
3842                                         }
3843                                 } else {
3844                                         arg_count = arguments.Count;
3845                                 }
3846                         } else if (arguments != null) {
3847                                 arg_count = arguments.Count;
3848                         }
3849
3850                         //
3851                         // 1. Handle generic method using type arguments when specified or type inference
3852                         //
3853                         TypeSpec[] ptypes;
3854                         var ms = candidate as MethodSpec;
3855                         if (ms != null && ms.IsGeneric) {
3856                                 // Setup constraint checker for probing only
3857                                 ConstraintChecker cc = new ConstraintChecker (null);
3858
3859                                 if (type_arguments != null) {
3860                                         var g_args_count = ms.Arity;
3861                                         if (g_args_count != type_arguments.Count)
3862                                                 return int.MaxValue - 20000 + System.Math.Abs (type_arguments.Count - g_args_count);
3863
3864                                         ms = ms.MakeGenericMethod (ec, type_arguments.Arguments);
3865                                 } else {
3866                                         // TODO: It should not be here (we don't know yet whether any argument is lambda) but
3867                                         // for now it simplifies things. I should probably add a callback to ResolveContext
3868                                         if (lambda_conv_msgs == null) {
3869                                                 lambda_conv_msgs = new SessionReportPrinter ();
3870                                                 prev_recorder = ec.Report.SetPrinter (lambda_conv_msgs);
3871                                         }
3872
3873                                         var ti = new TypeInference (arguments);
3874                                         TypeSpec[] i_args = ti.InferMethodArguments (ec, ms);
3875                                         lambda_conv_msgs.EndSession ();
3876
3877                                         if (i_args == null)
3878                                                 return ti.InferenceScore - 20000;
3879
3880                                         if (i_args.Length != 0) {
3881                                                 ms = ms.MakeGenericMethod (ec, i_args);
3882                                         }
3883
3884                                         cc.IgnoreInferredDynamic = true;
3885                                 }
3886
3887                                 //
3888                                 // Type arguments constraints have to match for the method to be applicable
3889                                 //
3890                                 if (!cc.CheckAll (ms.GetGenericMethodDefinition (), ms.TypeArguments, ms.Constraints, loc)) {
3891                                         candidate = ms;
3892                                         return int.MaxValue - 25000;
3893                                 }
3894
3895                                 //
3896                                 // We have a generic return type and at same time the method is override which
3897                                 // means we have to also inflate override return type in case the candidate is
3898                                 // best candidate and override return type is different to base return type.
3899                                 //
3900                                 // virtual Foo<T, object> with override Foo<T, dynamic>
3901                                 //
3902                                 if (candidate != pm) {
3903                                         MethodSpec override_ms = (MethodSpec) pm;
3904                                         var inflator = new TypeParameterInflator (ec, ms.DeclaringType, override_ms.GenericDefinition.TypeParameters, ms.TypeArguments);
3905                                         returnType = inflator.Inflate (returnType);
3906                                 } else {
3907                                         returnType = ms.ReturnType;
3908                                 }
3909
3910                                 candidate = ms;
3911                                 ptypes = ms.Parameters.Types;
3912                         } else {
3913                                 if (type_arguments != null)
3914                                         return int.MaxValue - 15000;
3915
3916                                 ptypes = cpd.Types;
3917                         }
3918
3919                         //
3920                         // 2. Each argument has to be implicitly convertible to method parameter
3921                         //
3922                         Parameter.Modifier p_mod = 0;
3923                         TypeSpec pt = null;
3924
3925                         for (int i = 0; i < arg_count; i++) {
3926                                 Argument a = arguments[i];
3927                                 if (a == null) {
3928                                         if (!pd.FixedParameters[i].HasDefaultValue) {
3929                                                 arguments = orig_args;
3930                                                 return arg_count * 2 + 2;
3931                                         }
3932
3933                                         //
3934                                         // Get the default value expression, we can use the same expression
3935                                         // if the type matches
3936                                         //
3937                                         Expression e = pd.FixedParameters[i].DefaultValue;
3938                                         if (!(e is Constant) || e.Type.IsGenericOrParentIsGeneric) {
3939                                                 //
3940                                                 // LAMESPEC: No idea what the exact rules are for System.Reflection.Missing.Value instead of null
3941                                                 //
3942                                                 if (e == EmptyExpression.MissingValue && ptypes[i].BuildinType == BuildinTypeSpec.Type.Object || ptypes[i] == InternalType.Dynamic) {
3943                                                         e = new MemberAccess (new MemberAccess (new MemberAccess (
3944                                                                 new QualifiedAliasMember (QualifiedAliasMember.GlobalAlias, "System", loc), "Reflection", loc), "Missing", loc), "Value", loc);
3945                                                 } else {
3946                                                         e = new DefaultValueExpression (new TypeExpression (ptypes [i], loc), loc);
3947                                                 }
3948
3949                                                 e = e.Resolve (ec);
3950                                         }
3951
3952                                         arguments[i] = new Argument (e, Argument.AType.Default);
3953                                         continue;
3954                                 }
3955
3956                                 if (p_mod != Parameter.Modifier.PARAMS) {
3957                                         p_mod = (pd.FixedParameters[i].ModFlags & ~Parameter.Modifier.PARAMS) | (cpd.FixedParameters[i].ModFlags & Parameter.Modifier.PARAMS);
3958                                         pt = ptypes [i];
3959                                 } else if (!params_expanded_form) {
3960                                         params_expanded_form = true;
3961                                         pt = ((ElementTypeSpec) pt).Element;
3962                                         i -= 2;
3963                                         continue;
3964                                 }
3965
3966                                 score = 1;
3967                                 if (!params_expanded_form) {
3968                                         if (a.ArgType == Argument.AType.ExtensionType) {
3969                                                 //
3970                                                 // Indentity, implicit reference or boxing conversion must exist for the extension parameter
3971                                                 //
3972                                                 var at = a.Type;
3973                                                 if (at == pt || TypeSpecComparer.IsEqual (at, pt) ||
3974                                                         Convert.ImplicitReferenceConversionExists (a.Expr, pt) ||
3975                                                         Convert.ImplicitBoxingConversion (EmptyExpression.Null, at, pt) != null) {
3976                                                         score = 0;
3977                                                         continue;
3978                                                 }
3979                                         } else {
3980                                                 score = IsArgumentCompatible (ec, a, p_mod & ~Parameter.Modifier.PARAMS, pt);
3981
3982                                                 if (score < 0)
3983                                                         dynamicArgument = true;
3984                                         }
3985                                 }
3986
3987                                 //
3988                                 // It can be applicable in expanded form (when not doing exact match like for delegates)
3989                                 //
3990                                 if (score != 0 && (p_mod & Parameter.Modifier.PARAMS) != 0 && (restrictions & Restrictions.CovariantDelegate) == 0) {
3991                                         if (!params_expanded_form)
3992                                                 pt = ((ElementTypeSpec) pt).Element;
3993
3994                                         if (score > 0)
3995                                                 score = IsArgumentCompatible (ec, a, Parameter.Modifier.NONE, pt);
3996
3997                                         if (score == 0) {
3998                                                 params_expanded_form = true;
3999                                         } else if (score < 0) {
4000                                                 params_expanded_form = true;
4001                                                 dynamicArgument = true;
4002                                         }
4003                                 }
4004
4005                                 if (score > 0) {
4006                                         if (params_expanded_form)
4007                                                 ++score;
4008                                         return (arg_count - i) * 2 + score;
4009                                 }
4010                         }
4011
4012                         //
4013                         // When params parameter has no argument it will be provided later if the method is the best candidate
4014                         //
4015                         if (arg_count + 1 == pd.Count && (cpd.FixedParameters [arg_count].ModFlags & Parameter.Modifier.PARAMS) != 0)
4016                                 params_expanded_form = true;
4017
4018                         //
4019                         // Restore original arguments for dynamic binder to keep the intention of original source code
4020                         //
4021                         if (dynamicArgument)
4022                                 arguments = orig_args;
4023
4024                         return 0;
4025                 }
4026
4027                 //
4028                 // Tests argument compatibility with the parameter
4029                 // The possible return values are
4030                 // 0 - success
4031                 // 1 - modifier mismatch
4032                 // 2 - type mismatch
4033                 // -1 - dynamic binding required
4034                 //
4035                 int IsArgumentCompatible (ResolveContext ec, Argument argument, Parameter.Modifier param_mod, TypeSpec parameter)
4036                 {
4037                         //
4038                         // Types have to be identical when ref or out modifer
4039                         // is used and argument is not of dynamic type
4040                         //
4041                         if ((argument.Modifier | param_mod) != 0) {
4042                                 if (argument.Type != parameter) {
4043                                         //
4044                                         // Do full equality check after quick path
4045                                         //
4046                                         if (!TypeSpecComparer.IsEqual (argument.Type, parameter)) {
4047                                                 //
4048                                                 // Using dynamic for ref/out parameter can still succeed at runtime
4049                                                 //
4050                                                 if (argument.Type == InternalType.Dynamic && argument.Modifier == 0 && (restrictions & Restrictions.CovariantDelegate) == 0)
4051                                                         return -1;
4052
4053                                                 return 2;
4054                                         }
4055                                 }
4056
4057                                 if (argument.Modifier != param_mod) {
4058                                         //
4059                                         // Using dynamic for ref/out parameter can still succeed at runtime
4060                                         //
4061                                         if (argument.Type == InternalType.Dynamic && argument.Modifier == 0 && (restrictions & Restrictions.CovariantDelegate) == 0)
4062                                                 return -1;
4063
4064                                         return 1;
4065                                 }
4066
4067                         } else {
4068                                 if (argument.Type == InternalType.Dynamic && (restrictions & Restrictions.CovariantDelegate) == 0)
4069                                         return -1;
4070
4071                                 //
4072                                 // Deploy custom error reporting for lambda methods. When probing lambda methods
4073                                 // keep all errors reported in separate set and once we are done and no best
4074                                 // candidate found, this set is used to report more details about what was wrong
4075                                 // with lambda body
4076                                 //
4077                                 if (argument.Expr.Type == InternalType.AnonymousMethod) {
4078                                         if (lambda_conv_msgs == null) {
4079                                                 lambda_conv_msgs = new SessionReportPrinter ();
4080                                                 prev_recorder = ec.Report.SetPrinter (lambda_conv_msgs);
4081                                         }
4082                                 }
4083
4084                                 if (!Convert.ImplicitConversionExists (ec, argument.Expr, parameter)) {
4085                                         if (lambda_conv_msgs != null) {
4086                                                 lambda_conv_msgs.EndSession ();
4087                                         }
4088
4089                                         return 2;
4090                                 }
4091                         }
4092
4093                         return 0;
4094                 }
4095
4096                 static TypeSpec MoreSpecific (TypeSpec p, TypeSpec q)
4097                 {
4098                         if (TypeManager.IsGenericParameter (p) && !TypeManager.IsGenericParameter (q))
4099                                 return q;
4100                         if (!TypeManager.IsGenericParameter (p) && TypeManager.IsGenericParameter (q))
4101                                 return p;
4102
4103                         var ac_p = p as ArrayContainer;
4104                         if (ac_p != null) {
4105                                 var ac_q = ((ArrayContainer) q);
4106                                 TypeSpec specific = MoreSpecific (ac_p.Element, ac_q.Element);
4107                                 if (specific == ac_p.Element)
4108                                         return p;
4109                                 if (specific == ac_q.Element)
4110                                         return q;
4111                         } else if (TypeManager.IsGenericType (p)) {
4112                                 var pargs = TypeManager.GetTypeArguments (p);
4113                                 var qargs = TypeManager.GetTypeArguments (q);
4114
4115                                 bool p_specific_at_least_once = false;
4116                                 bool q_specific_at_least_once = false;
4117
4118                                 for (int i = 0; i < pargs.Length; i++) {
4119                                         TypeSpec specific = MoreSpecific (pargs[i], qargs[i]);
4120                                         if (specific == pargs[i])
4121                                                 p_specific_at_least_once = true;
4122                                         if (specific == qargs[i])
4123                                                 q_specific_at_least_once = true;
4124                                 }
4125
4126                                 if (p_specific_at_least_once && !q_specific_at_least_once)
4127                                         return p;
4128                                 if (!p_specific_at_least_once && q_specific_at_least_once)
4129                                         return q;
4130                         }
4131
4132                         return null;
4133                 }
4134
4135                 //
4136                 // Find the best method from candidate list
4137                 //
4138                 public T ResolveMember<T> (ResolveContext rc, ref Arguments args) where T : MemberSpec, IParametersMember
4139                 {
4140                         List<AmbiguousCandidate> ambiguous_candidates = null;
4141
4142                         MemberSpec best_candidate;
4143                         Arguments best_candidate_args = null;
4144                         bool best_candidate_params = false;
4145                         bool best_candidate_dynamic = false;
4146                         int best_candidate_rate;
4147                         IParametersMember best_parameter_member = null;
4148
4149                         int args_count = args != null ? args.Count : 0;
4150
4151                         Arguments candidate_args = args;
4152                         bool error_mode = false;
4153                         var current_type = rc.CurrentType;
4154                         MemberSpec invocable_member = null;
4155
4156                         // Be careful, cannot return until error reporter is restored
4157                         while (true) {
4158                                 best_candidate = null;
4159                                 best_candidate_rate = int.MaxValue;
4160
4161                                 var type_members = members;
4162                                 try {
4163
4164                                         do {
4165                                                 for (int i = 0; i < type_members.Count; ++i) {
4166                                                         var member = type_members[i];
4167
4168                                                         //
4169                                                         // Methods in a base class are not candidates if any method in a derived
4170                                                         // class is applicable
4171                                                         //
4172                                                         if ((member.Modifiers & Modifiers.OVERRIDE) != 0)
4173                                                                 continue;
4174
4175                                                         if (!error_mode) {
4176                                                                 if (!member.IsAccessible (current_type))
4177                                                                         continue;
4178
4179                                                                 if (rc.IsRuntimeBinder && !member.DeclaringType.IsAccessible (current_type))
4180                                                                         continue;
4181                                                         }
4182
4183                                                         IParametersMember pm = member as IParametersMember;
4184                                                         if (pm == null) {
4185                                                                 //
4186                                                                 // Will use it later to report ambiguity between best method and invocable member
4187                                                                 //
4188                                                                 if (Invocation.IsMemberInvocable (member))
4189                                                                         invocable_member = member;
4190
4191                                                                 continue;
4192                                                         }
4193
4194                                                         //
4195                                                         // Overload resolution is looking for base member but using parameter names
4196                                                         // and default values from the closest member. That means to do expensive lookup
4197                                                         // for the closest override for virtual or abstract members
4198                                                         //
4199                                                         if ((member.Modifiers & (Modifiers.VIRTUAL | Modifiers.ABSTRACT)) != 0) {
4200                                                                 var override_params = base_provider.GetOverrideMemberParameters (member);
4201                                                                 if (override_params != null)
4202                                                                         pm = override_params;
4203                                                         }
4204
4205                                                         //
4206                                                         // Check if the member candidate is applicable
4207                                                         //
4208                                                         bool params_expanded_form = false;
4209                                                         bool dynamic_argument = false;
4210                                                         TypeSpec rt = pm.MemberType;
4211                                                         int candidate_rate = IsApplicable (rc, ref candidate_args, args_count, ref member, pm, ref params_expanded_form, ref dynamic_argument, ref rt);
4212
4213                                                         //
4214                                                         // How does it score compare to others
4215                                                         //
4216                                                         if (candidate_rate < best_candidate_rate) {
4217                                                                 best_candidate_rate = candidate_rate;
4218                                                                 best_candidate = member;
4219                                                                 best_candidate_args = candidate_args;
4220                                                                 best_candidate_params = params_expanded_form;
4221                                                                 best_candidate_dynamic = dynamic_argument;
4222                                                                 best_parameter_member = pm;
4223                                                                 best_candidate_return_type = rt;
4224                                                         } else if (candidate_rate == 0) {
4225                                                                 //
4226                                                                 // The member look is done per type for most operations but sometimes
4227                                                                 // it's not possible like for binary operators overload because they
4228                                                                 // are unioned between 2 sides
4229                                                                 //
4230                                                                 if ((restrictions & Restrictions.BaseMembersIncluded) != 0) {
4231                                                                         if (TypeSpec.IsBaseClass (best_candidate.DeclaringType, member.DeclaringType, true))
4232                                                                                 continue;
4233                                                                 }
4234
4235                                                                 bool is_better;
4236                                                                 if (best_candidate.DeclaringType.IsInterface && member.DeclaringType.ImplementsInterface (best_candidate.DeclaringType, false)) {
4237                                                                         //
4238                                                                         // We pack all interface members into top level type which makes the overload resolution
4239                                                                         // more complicated for interfaces. We compensate it by removing methods with same
4240                                                                         // signature when building the cache hence this path should not really be hit often
4241                                                                         //
4242                                                                         // Example:
4243                                                                         // interface IA { void Foo (int arg); }
4244                                                                         // interface IB : IA { void Foo (params int[] args); }
4245                                                                         //
4246                                                                         // IB::Foo is the best overload when calling IB.Foo (1)
4247                                                                         //
4248                                                                         is_better = true;
4249                                                                         if (ambiguous_candidates != null) {
4250                                                                                 foreach (var amb_cand in ambiguous_candidates) {
4251                                                                                         if (member.DeclaringType.ImplementsInterface (best_candidate.DeclaringType, false)) {
4252                                                                                                 continue;
4253                                                                                         }
4254
4255                                                                                         is_better = false;
4256                                                                                         break;
4257                                                                                 }
4258
4259                                                                                 if (is_better)
4260                                                                                         ambiguous_candidates = null;
4261                                                                         }
4262                                                                 } else {
4263                                                                         // Is the new candidate better
4264                                                                         is_better = BetterFunction (rc, candidate_args, member, pm.Parameters, params_expanded_form, best_candidate, best_parameter_member.Parameters, best_candidate_params);
4265                                                                 }
4266
4267                                                                 if (is_better) {
4268                                                                         best_candidate = member;
4269                                                                         best_candidate_args = candidate_args;
4270                                                                         best_candidate_params = params_expanded_form;
4271                                                                         best_candidate_dynamic = dynamic_argument;
4272                                                                         best_parameter_member = pm;
4273                                                                         best_candidate_return_type = rt;
4274                                                                 } else {
4275                                                                         // It's not better but any other found later could be but we are not sure yet
4276                                                                         if (ambiguous_candidates == null)
4277                                                                                 ambiguous_candidates = new List<AmbiguousCandidate> ();
4278
4279                                                                         ambiguous_candidates.Add (new AmbiguousCandidate (member, pm.Parameters, params_expanded_form));
4280                                                                 }
4281                                                         }
4282
4283                                                         // Restore expanded arguments
4284                                                         if (candidate_args != args)
4285                                                                 candidate_args = args;
4286                                                 }
4287                                         } while (best_candidate_rate != 0 && (type_members = base_provider.GetBaseMembers (type_members[0].DeclaringType.BaseType)) != null);
4288                                 } finally {
4289                                         if (prev_recorder != null)
4290                                                 rc.Report.SetPrinter (prev_recorder);
4291                                 }
4292
4293                                 //
4294                                 // We've found exact match
4295                                 //
4296                                 if (best_candidate_rate == 0)
4297                                         break;
4298
4299                                 //
4300                                 // Try extension methods lookup when no ordinary method match was found and provider enables it
4301                                 //
4302                                 if (!error_mode) {
4303                                         var emg = base_provider.LookupExtensionMethod (rc);
4304                                         if (emg != null) {
4305                                                 emg = emg.OverloadResolve (rc, ref args, null, restrictions);
4306                                                 if (emg != null) {
4307                                                         best_candidate_extension_group = emg;
4308                                                         return (T) (MemberSpec) emg.BestCandidate;
4309                                                 }
4310                                         }
4311                                 }
4312
4313                                 // Don't run expensive error reporting mode for probing
4314                                 if (IsProbingOnly)
4315                                         return null;
4316
4317                                 if (error_mode)
4318                                         break;
4319
4320                                 lambda_conv_msgs = null;
4321                                 error_mode = true;
4322                         }
4323
4324                         //
4325                         // No best member match found, report an error
4326                         //
4327                         if (best_candidate_rate != 0 || error_mode) {
4328                                 ReportOverloadError (rc, best_candidate, best_parameter_member, best_candidate_args, best_candidate_params);
4329                                 return null;
4330                         }
4331
4332                         if (best_candidate_dynamic) {
4333                                 if (args[0].ArgType == Argument.AType.ExtensionType) {
4334                                         rc.Report.Error (1973, loc,
4335                                                 "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",
4336                                                 args [0].Type.GetSignatureForError (), best_candidate.Name, best_candidate.GetSignatureForError ());
4337                                 }
4338
4339                                 BestCandidateIsDynamic = true;
4340                                 return null;
4341                         }
4342
4343                         if (ambiguous_candidates != null) {
4344                                 //
4345                                 // Now check that there are no ambiguities i.e the selected method
4346                                 // should be better than all the others
4347                                 //
4348                                 for (int ix = 0; ix < ambiguous_candidates.Count; ix++) {
4349                                         var candidate = ambiguous_candidates [ix];
4350
4351                                         if (!BetterFunction (rc, best_candidate_args, best_candidate, best_parameter_member.Parameters, best_candidate_params, candidate.Member, candidate.Parameters, candidate.Expanded)) {
4352                                                 var ambiguous = candidate.Member;
4353                                                 if (custom_errors == null || !custom_errors.AmbiguousCandidates (rc, best_candidate, ambiguous)) {
4354                                                         rc.Report.SymbolRelatedToPreviousError (best_candidate);
4355                                                         rc.Report.SymbolRelatedToPreviousError (ambiguous);
4356                                                         rc.Report.Error (121, loc, "The call is ambiguous between the following methods or properties: `{0}' and `{1}'",
4357                                                                 best_candidate.GetSignatureForError (), ambiguous.GetSignatureForError ());
4358                                                 }
4359
4360                                                 return (T) best_candidate;
4361                                         }
4362                                 }
4363                         }
4364
4365                         if (invocable_member != null) {
4366                                 rc.Report.SymbolRelatedToPreviousError (best_candidate);
4367                                 rc.Report.SymbolRelatedToPreviousError (invocable_member);
4368                                 rc.Report.Warning (467, 2, loc, "Ambiguity between method `{0}' and invocable non-method `{1}'. Using method group",
4369                                         best_candidate.GetSignatureForError (), invocable_member.GetSignatureForError ());
4370                         }
4371
4372                         //
4373                         // And now check if the arguments are all
4374                         // compatible, perform conversions if
4375                         // necessary etc. and return if everything is
4376                         // all right
4377                         //
4378                         if (!VerifyArguments (rc, ref best_candidate_args, best_candidate, best_parameter_member, best_candidate_params))
4379                                 return null;
4380
4381                         if (best_candidate == null)
4382                                 return null;
4383
4384                         //
4385                         // Check ObsoleteAttribute on the best method
4386                         //
4387                         ObsoleteAttribute oa = best_candidate.GetAttributeObsolete ();
4388                         if (oa != null && !rc.IsObsolete)
4389                                 AttributeTester.Report_ObsoleteMessage (oa, best_candidate.GetSignatureForError (), loc, rc.Report);
4390
4391                         var dep = best_candidate.GetMissingDependencies ();
4392                         if (dep != null) {
4393                                 ImportedTypeDefinition.Error_MissingDependency (rc, dep, loc);
4394                         }
4395
4396                         best_candidate.MemberDefinition.SetIsUsed ();
4397
4398                         args = best_candidate_args;
4399                         return (T) best_candidate;
4400                 }
4401
4402                 public MethodSpec ResolveOperator (ResolveContext rc, ref Arguments args)
4403                 {
4404                         return ResolveMember<MethodSpec> (rc, ref args);
4405                 }
4406
4407                 void ReportArgumentMismatch (ResolveContext ec, int idx, MemberSpec method,
4408                                                                                                         Argument a, AParametersCollection expected_par, TypeSpec paramType)
4409                 {
4410                         if (custom_errors != null && custom_errors.ArgumentMismatch (ec, method, a, idx))
4411                                 return;
4412
4413                         if (a is CollectionElementInitializer.ElementInitializerArgument) {
4414                                 ec.Report.SymbolRelatedToPreviousError (method);
4415                                 if ((expected_par.FixedParameters[idx].ModFlags & Parameter.Modifier.ISBYREF) != 0) {
4416                                         ec.Report.Error (1954, loc, "The best overloaded collection initalizer method `{0}' cannot have 'ref', or `out' modifier",
4417                                                 TypeManager.CSharpSignature (method));
4418                                         return;
4419                                 }
4420                                 ec.Report.Error (1950, loc, "The best overloaded collection initalizer method `{0}' has some invalid arguments",
4421                                           TypeManager.CSharpSignature (method));
4422                         } else if (IsDelegateInvoke) {
4423                                 ec.Report.Error (1594, loc, "Delegate `{0}' has some invalid arguments",
4424                                         DelegateType.GetSignatureForError ());
4425                         } else {
4426                                 ec.Report.SymbolRelatedToPreviousError (method);
4427                                 ec.Report.Error (1502, loc, "The best overloaded method match for `{0}' has some invalid arguments",
4428                                         method.GetSignatureForError ());
4429                         }
4430
4431                         Parameter.Modifier mod = idx >= expected_par.Count ? 0 : expected_par.FixedParameters[idx].ModFlags;
4432
4433                         string index = (idx + 1).ToString ();
4434                         if (((mod & (Parameter.Modifier.REF | Parameter.Modifier.OUT)) ^
4435                                 (a.Modifier & (Parameter.Modifier.REF | Parameter.Modifier.OUT))) != 0) {
4436                                 if ((mod & Parameter.Modifier.ISBYREF) == 0)
4437                                         ec.Report.Error (1615, loc, "Argument `#{0}' does not require `{1}' modifier. Consider removing `{1}' modifier",
4438                                                 index, Parameter.GetModifierSignature (a.Modifier));
4439                                 else
4440                                         ec.Report.Error (1620, loc, "Argument `#{0}' is missing `{1}' modifier",
4441                                                 index, Parameter.GetModifierSignature (mod));
4442                         } else {
4443                                 string p1 = a.GetSignatureForError ();
4444                                 string p2 = TypeManager.CSharpName (paramType);
4445
4446                                 if (p1 == p2) {
4447                                         ec.Report.ExtraInformation (loc, "(equally named types possibly from different assemblies in previous ");
4448                                         ec.Report.SymbolRelatedToPreviousError (a.Expr.Type);
4449                                         ec.Report.SymbolRelatedToPreviousError (paramType);
4450                                 }
4451
4452                                 ec.Report.Error (1503, loc,
4453                                         "Argument `#{0}' cannot convert `{1}' expression to type `{2}'", index, p1, p2);
4454                         }
4455                 }
4456
4457                 //
4458                 // We have failed to find exact match so we return error info about the closest match
4459                 //
4460                 void ReportOverloadError (ResolveContext rc, MemberSpec best_candidate, IParametersMember pm, Arguments args, bool params_expanded)
4461                 {
4462                         int ta_count = type_arguments == null ? 0 : type_arguments.Count;
4463                         int arg_count = args == null ? 0 : args.Count;
4464
4465                         if (ta_count != best_candidate.Arity && (ta_count > 0 || ((IParametersMember) best_candidate).Parameters.IsEmpty)) {
4466                                 var mg = new MethodGroupExpr (new [] { best_candidate }, best_candidate.DeclaringType, loc);
4467                                 mg.Error_TypeArgumentsCannotBeUsed (rc.Report, loc, best_candidate, ta_count);
4468                                 return;
4469                         }
4470
4471                         if (lambda_conv_msgs != null) {
4472                                 if (lambda_conv_msgs.Merge (rc.Report.Printer))
4473                                         return;
4474                         }
4475
4476                         //
4477                         // For candidates which match on parameters count report more details about incorrect arguments
4478                         //
4479                         if (pm != null) {
4480                                 int unexpanded_count = ((IParametersMember) best_candidate).Parameters.HasParams ? pm.Parameters.Count - 1 : pm.Parameters.Count;
4481                                 if (pm.Parameters.Count == arg_count || params_expanded || unexpanded_count == arg_count) {
4482                                         // Reject any inaccessible member
4483                                         if (!best_candidate.IsAccessible (rc.CurrentType) || !best_candidate.DeclaringType.IsAccessible (rc.CurrentType)) {
4484                                                 rc.Report.SymbolRelatedToPreviousError (best_candidate);
4485                                                 Expression.ErrorIsInaccesible (rc, best_candidate.GetSignatureForError (), loc);
4486                                                 return;
4487                                         }
4488
4489                                         var ms = best_candidate as MethodSpec;
4490                                         if (ms != null && ms.IsGeneric) {
4491                                                 bool constr_ok = true;
4492                                                 if (ms.TypeArguments != null)
4493                                                         constr_ok = new ConstraintChecker (rc.MemberContext).CheckAll (ms.GetGenericMethodDefinition (), ms.TypeArguments, ms.Constraints, loc);
4494
4495                                                 if (ta_count == 0) {
4496                                                         if (custom_errors != null && custom_errors.TypeInferenceFailed (rc, best_candidate))
4497                                                                 return;
4498
4499                                                         if (constr_ok) {
4500                                                                 rc.Report.Error (411, loc,
4501                                                                         "The type arguments for method `{0}' cannot be inferred from the usage. Try specifying the type arguments explicitly",
4502                                                                         ms.GetGenericMethodDefinition ().GetSignatureForError ());
4503                                                         }
4504
4505                                                         return;
4506                                                 }
4507                                         }
4508
4509                                         VerifyArguments (rc, ref args, best_candidate, pm, params_expanded);
4510                                         return;
4511                                 }
4512                         }
4513
4514                         //
4515                         // We failed to find any method with correct argument count, report best candidate
4516                         //
4517                         if (custom_errors != null && custom_errors.NoArgumentMatch (rc, best_candidate))
4518                                 return;
4519
4520                         if (best_candidate.Kind == MemberKind.Constructor) {
4521                                 rc.Report.SymbolRelatedToPreviousError (best_candidate);
4522                                 Error_ConstructorMismatch (rc, best_candidate.DeclaringType, arg_count, loc);
4523                         } else if (IsDelegateInvoke) {
4524                                 rc.Report.SymbolRelatedToPreviousError (DelegateType);
4525                                 rc.Report.Error (1593, loc, "Delegate `{0}' does not take `{1}' arguments",
4526                                         DelegateType.GetSignatureForError (), arg_count.ToString ());
4527                         } else {
4528                                 string name = best_candidate.Kind == MemberKind.Indexer ? "this" : best_candidate.Name;
4529                                 rc.Report.SymbolRelatedToPreviousError (best_candidate);
4530                                 rc.Report.Error (1501, loc, "No overload for method `{0}' takes `{1}' arguments",
4531                                         name, arg_count.ToString ());
4532                         }
4533                 }
4534
4535                 bool VerifyArguments (ResolveContext ec, ref Arguments args, MemberSpec member, IParametersMember pm, bool chose_params_expanded)
4536                 {
4537                         var pd = pm.Parameters;
4538                         TypeSpec[] ptypes = ((IParametersMember) member).Parameters.Types;
4539
4540                         Parameter.Modifier p_mod = 0;
4541                         TypeSpec pt = null;
4542                         int a_idx = 0, a_pos = 0;
4543                         Argument a = null;
4544                         ArrayInitializer params_initializers = null;
4545                         bool has_unsafe_arg = pm.MemberType.IsPointer;
4546                         int arg_count = args == null ? 0 : args.Count;
4547
4548                         for (; a_idx < arg_count; a_idx++, ++a_pos) {
4549                                 a = args[a_idx];
4550                                 if (p_mod != Parameter.Modifier.PARAMS) {
4551                                         p_mod = pd.FixedParameters[a_idx].ModFlags;
4552                                         pt = ptypes[a_idx];
4553                                         has_unsafe_arg |= pt.IsPointer;
4554
4555                                         if (p_mod == Parameter.Modifier.PARAMS) {
4556                                                 if (chose_params_expanded) {
4557                                                         params_initializers = new ArrayInitializer (arg_count - a_idx, a.Expr.Location);
4558                                                         pt = TypeManager.GetElementType (pt);
4559                                                 }
4560                                         }
4561                                 }
4562
4563                                 //
4564                                 // Types have to be identical when ref or out modifer is used
4565                                 //
4566                                 if (a.Modifier != 0 || (p_mod & ~Parameter.Modifier.PARAMS) != 0) {
4567                                         if ((p_mod & ~Parameter.Modifier.PARAMS) != a.Modifier)
4568                                                 break;
4569
4570                                         if (a.Expr.Type == pt || TypeSpecComparer.IsEqual (a.Expr.Type, pt))
4571                                                 continue;
4572
4573                                         break;
4574                                 }
4575
4576                                 NamedArgument na = a as NamedArgument;
4577                                 if (na != null) {
4578                                         int name_index = pd.GetParameterIndexByName (na.Name);
4579                                         if (name_index < 0 || name_index >= pd.Count) {
4580                                                 if (IsDelegateInvoke) {
4581                                                         ec.Report.SymbolRelatedToPreviousError (DelegateType);
4582                                                         ec.Report.Error (1746, na.Location,
4583                                                                 "The delegate `{0}' does not contain a parameter named `{1}'",
4584                                                                 DelegateType.GetSignatureForError (), na.Name);
4585                                                 } else {
4586                                                         ec.Report.SymbolRelatedToPreviousError (member);
4587                                                         ec.Report.Error (1739, na.Location,
4588                                                                 "The best overloaded method match for `{0}' does not contain a parameter named `{1}'",
4589                                                                 TypeManager.CSharpSignature (member), na.Name);
4590                                                 }
4591                                         } else if (args[name_index] != a) {
4592                                                 if (IsDelegateInvoke)
4593                                                         ec.Report.SymbolRelatedToPreviousError (DelegateType);
4594                                                 else
4595                                                         ec.Report.SymbolRelatedToPreviousError (member);
4596
4597                                                 ec.Report.Error (1744, na.Location,
4598                                                         "Named argument `{0}' cannot be used for a parameter which has positional argument specified",
4599                                                         na.Name);
4600                                         }
4601                                 }
4602
4603                                 if (a.Expr.Type == InternalType.Dynamic)
4604                                         continue;
4605
4606                                 if ((restrictions & Restrictions.CovariantDelegate) != 0 && !Delegate.IsTypeCovariant (ec, a.Expr, pt)) {
4607                                         custom_errors.NoArgumentMatch (ec, member);
4608                                         return false;
4609                                 }
4610
4611                                 Expression conv = null;
4612                                 if (a.ArgType == Argument.AType.ExtensionType) {
4613                                         if (a.Expr.Type == pt || TypeSpecComparer.IsEqual (a.Expr.Type, pt)) {
4614                                                 conv = a.Expr;
4615                                         } else {
4616                                                 conv = Convert.ImplicitReferenceConversion (a.Expr, pt, false);
4617                                                 if (conv == null)
4618                                                         conv = Convert.ImplicitBoxingConversion (a.Expr, a.Expr.Type, pt);
4619                                         }
4620                                 } else {
4621                                         conv = Convert.ImplicitConversion (ec, a.Expr, pt, loc);
4622                                 }
4623
4624                                 if (conv == null)
4625                                         break;
4626
4627                                 //
4628                                 // Convert params arguments to an array initializer
4629                                 //
4630                                 if (params_initializers != null) {
4631                                         // we choose to use 'a.Expr' rather than 'conv' so that
4632                                         // we don't hide the kind of expression we have (esp. CompoundAssign.Helper)
4633                                         params_initializers.Add (a.Expr);
4634                                         args.RemoveAt (a_idx--);
4635                                         --arg_count;
4636                                         continue;
4637                                 }
4638
4639                                 // Update the argument with the implicit conversion
4640                                 a.Expr = conv;
4641                         }
4642
4643                         if (a_idx != arg_count) {
4644                                 ReportArgumentMismatch (ec, a_pos, member, a, pd, pt);
4645                                 return false;
4646                         }
4647
4648                         //
4649                         // Fill not provided arguments required by params modifier
4650                         //
4651                         if (params_initializers == null && pd.HasParams && arg_count + 1 == pd.Count) {
4652                                 if (args == null)
4653                                         args = new Arguments (1);
4654
4655                                 pt = ptypes[pd.Count - 1];
4656                                 pt = TypeManager.GetElementType (pt);
4657                                 has_unsafe_arg |= pt.IsPointer;
4658                                 params_initializers = new ArrayInitializer (0, loc);
4659                         }
4660
4661                         //
4662                         // Append an array argument with all params arguments
4663                         //
4664                         if (params_initializers != null) {
4665                                 args.Add (new Argument (
4666                                         new ArrayCreation (new TypeExpression (pt, loc), params_initializers, loc).Resolve (ec)));
4667                                 arg_count++;
4668                         }
4669
4670                         if (has_unsafe_arg && !ec.IsUnsafe) {
4671                                 Expression.UnsafeError (ec, loc);
4672                         }
4673
4674                         //
4675                         // We could infer inaccesible type arguments
4676                         //
4677                         if (type_arguments == null && member.IsGeneric) {
4678                                 var ms = (MethodSpec) member;
4679                                 foreach (var ta in ms.TypeArguments) {
4680                                         if (!ta.IsAccessible (ec.CurrentType)) {
4681                                                 ec.Report.SymbolRelatedToPreviousError (ta);
4682                                                 Expression.ErrorIsInaccesible (ec, member.GetSignatureForError (), loc);
4683                                                 break;
4684                                         }
4685                                 }
4686                         }
4687
4688                         return true;
4689                 }
4690         }
4691
4692         public class ConstantExpr : MemberExpr
4693         {
4694                 ConstSpec constant;
4695
4696                 public ConstantExpr (ConstSpec constant, Location loc)
4697                 {
4698                         this.constant = constant;
4699                         this.loc = loc;
4700                 }
4701
4702                 public override string Name {
4703                         get { throw new NotImplementedException (); }
4704                 }
4705
4706                 public override bool IsInstance {
4707                         get { return !IsStatic; }
4708                 }
4709
4710                 public override bool IsStatic {
4711                         get { return true; }
4712                 }
4713
4714                 protected override TypeSpec DeclaringType {
4715                         get { return constant.DeclaringType; }
4716                 }
4717
4718                 public override Expression CreateExpressionTree (ResolveContext ec)
4719                 {
4720                         throw new NotSupportedException ("ET");
4721                 }
4722
4723                 protected override Expression DoResolve (ResolveContext rc)
4724                 {
4725                         ResolveInstanceExpression (rc, null);
4726                         DoBestMemberChecks (rc, constant);
4727
4728                         var c = constant.GetConstant (rc);
4729
4730                         // Creates reference expression to the constant value
4731                         return Constant.CreateConstant (constant.MemberType, c.GetValue (), loc);
4732                 }
4733
4734                 public override void Emit (EmitContext ec)
4735                 {
4736                         throw new NotSupportedException ();
4737                 }
4738
4739                 public override string GetSignatureForError ()
4740                 {
4741                         return constant.GetSignatureForError ();
4742                 }
4743
4744                 public override void SetTypeArguments (ResolveContext ec, TypeArguments ta)
4745                 {
4746                         Error_TypeArgumentsCannotBeUsed (ec.Report, "constant", GetSignatureForError (), loc);
4747                 }
4748         }
4749
4750         /// <summary>
4751         ///   Fully resolved expression that evaluates to a Field
4752         /// </summary>
4753         public class FieldExpr : MemberExpr, IDynamicAssign, IMemoryLocation, IVariableReference {
4754                 protected FieldSpec spec;
4755                 VariableInfo variable_info;
4756
4757                 LocalTemporary temp;
4758                 bool prepared;
4759
4760                 protected FieldExpr (Location l)
4761                 {
4762                         loc = l;
4763                 }
4764
4765                 public FieldExpr (FieldSpec spec, Location loc)
4766                 {
4767                         this.spec = spec;
4768                         this.loc = loc;
4769
4770                         type = spec.MemberType;
4771                 }
4772
4773                 public FieldExpr (FieldBase fi, Location l)
4774                         : this (fi.Spec, l)
4775                 {
4776                 }
4777
4778                 #region Properties
4779
4780                 public override string Name {
4781                         get {
4782                                 return spec.Name;
4783                         }
4784                 }
4785
4786                 public bool IsHoisted {
4787                         get {
4788                                 IVariableReference hv = InstanceExpression as IVariableReference;
4789                                 return hv != null && hv.IsHoisted;
4790                         }
4791                 }
4792
4793                 public override bool IsInstance {
4794                         get {
4795                                 return !spec.IsStatic;
4796                         }
4797                 }
4798
4799                 public override bool IsStatic {
4800                         get {
4801                                 return spec.IsStatic;
4802                         }
4803                 }
4804
4805                 public FieldSpec Spec {
4806                         get {
4807                                 return spec;
4808                         }
4809                 }
4810
4811                 protected override TypeSpec DeclaringType {
4812                         get {
4813                                 return spec.DeclaringType;
4814                         }
4815                 }
4816
4817                 public VariableInfo VariableInfo {
4818                         get {
4819                                 return variable_info;
4820                         }
4821                 }
4822
4823 #endregion
4824
4825                 public override string GetSignatureForError ()
4826                 {
4827                         return TypeManager.GetFullNameSignature (spec);
4828                 }
4829
4830                 public bool IsMarshalByRefAccess ()
4831                 {
4832                         // Checks possible ldflda of field access expression
4833                         return !spec.IsStatic && TypeManager.IsValueType (spec.MemberType) &&
4834                                 TypeSpec.IsBaseClass (spec.DeclaringType, TypeManager.mbr_type, false) &&
4835                                 !(InstanceExpression is This);
4836                 }
4837
4838                 public void SetHasAddressTaken ()
4839                 {
4840                         IVariableReference vr = InstanceExpression as IVariableReference;
4841                         if (vr != null)
4842                                 vr.SetHasAddressTaken ();
4843                 }
4844
4845                 public override Expression CreateExpressionTree (ResolveContext ec)
4846                 {
4847                         Expression instance;
4848                         if (InstanceExpression == null) {
4849                                 instance = new NullLiteral (loc);
4850                         } else {
4851                                 instance = InstanceExpression.CreateExpressionTree (ec);
4852                         }
4853
4854                         Arguments args = Arguments.CreateForExpressionTree (ec, null,
4855                                 instance,
4856                                 CreateTypeOfExpression ());
4857
4858                         return CreateExpressionFactoryCall (ec, "Field", args);
4859                 }
4860
4861                 public Expression CreateTypeOfExpression ()
4862                 {
4863                         return new TypeOfField (spec, loc);
4864                 }
4865
4866                 protected override Expression DoResolve (ResolveContext ec)
4867                 {
4868                         return DoResolve (ec, null);
4869                 }
4870
4871                 Expression DoResolve (ResolveContext ec, Expression rhs)
4872                 {
4873                         bool lvalue_instance = rhs != null && IsInstance && spec.DeclaringType.IsStruct;
4874
4875                         if (ResolveInstanceExpression (ec, rhs)) {
4876                                 // Resolve the field's instance expression while flow analysis is turned
4877                                 // off: when accessing a field "a.b", we must check whether the field
4878                                 // "a.b" is initialized, not whether the whole struct "a" is initialized.
4879
4880                                 if (lvalue_instance) {
4881                                         using (ec.With (ResolveContext.Options.DoFlowAnalysis, false)) {
4882                                                 bool out_access = rhs == EmptyExpression.OutAccess.Instance || rhs == EmptyExpression.LValueMemberOutAccess;
4883
4884                                                 Expression right_side =
4885                                                         out_access ? EmptyExpression.LValueMemberOutAccess : EmptyExpression.LValueMemberAccess;
4886
4887                                                 InstanceExpression = InstanceExpression.ResolveLValue (ec, right_side);
4888                                         }
4889                                 } else {
4890                                         using (ec.With (ResolveContext.Options.DoFlowAnalysis, false)) {
4891                                                 InstanceExpression = InstanceExpression.Resolve (ec, ResolveFlags.VariableOrValue);
4892                                         }
4893                                 }
4894
4895                                 if (InstanceExpression == null)
4896                                         return null;
4897                         }
4898
4899                         DoBestMemberChecks (ec, spec);
4900
4901                         var fb = spec as FixedFieldSpec;
4902                         IVariableReference var = InstanceExpression as IVariableReference;
4903
4904                         if (lvalue_instance && var != null && var.VariableInfo != null) {
4905                                 var.VariableInfo.SetFieldAssigned (ec, Name);
4906                         }
4907
4908                         if (fb != null) {
4909                                 IFixedExpression fe = InstanceExpression as IFixedExpression;
4910                                 if (!ec.HasSet (ResolveContext.Options.FixedInitializerScope) && (fe == null || !fe.IsFixed)) {
4911                                         ec.Report.Error (1666, loc, "You cannot use fixed size buffers contained in unfixed expressions. Try using the fixed statement");
4912                                 }
4913
4914                                 if (InstanceExpression.eclass != ExprClass.Variable) {
4915                                         ec.Report.SymbolRelatedToPreviousError (spec);
4916                                         ec.Report.Error (1708, loc, "`{0}': Fixed size buffers can only be accessed through locals or fields",
4917                                                 TypeManager.GetFullNameSignature (spec));
4918                                 } else if (var != null && var.IsHoisted) {
4919                                         AnonymousMethodExpression.Error_AddressOfCapturedVar (ec, var, loc);
4920                                 }
4921
4922                                 return new FixedBufferPtr (this, fb.ElementType, loc).Resolve (ec);
4923                         }
4924
4925                         eclass = ExprClass.Variable;
4926
4927                         // If the instance expression is a local variable or parameter.
4928                         if (var == null || var.VariableInfo == null)
4929                                 return this;
4930
4931                         VariableInfo vi = var.VariableInfo;
4932                         if (!vi.IsFieldAssigned (ec, Name, loc))
4933                                 return null;
4934
4935                         variable_info = vi.GetSubStruct (Name);
4936                         return this;
4937                 }
4938
4939                 static readonly int [] codes = {
4940                         191,    // instance, write access
4941                         192,    // instance, out access
4942                         198,    // static, write access
4943                         199,    // static, out access
4944                         1648,   // member of value instance, write access
4945                         1649,   // member of value instance, out access
4946                         1650,   // member of value static, write access
4947                         1651    // member of value static, out access
4948                 };
4949
4950                 static readonly string [] msgs = {
4951                         /*0191*/ "A readonly field `{0}' cannot be assigned to (except in a constructor or a variable initializer)",
4952                         /*0192*/ "A readonly field `{0}' cannot be passed ref or out (except in a constructor)",
4953                         /*0198*/ "A static readonly field `{0}' cannot be assigned to (except in a static constructor or a variable initializer)",
4954                         /*0199*/ "A static readonly field `{0}' cannot be passed ref or out (except in a static constructor)",
4955                         /*1648*/ "Members of readonly field `{0}' cannot be modified (except in a constructor or a variable initializer)",
4956                         /*1649*/ "Members of readonly field `{0}' cannot be passed ref or out (except in a constructor)",
4957                         /*1650*/ "Fields of static readonly field `{0}' cannot be assigned to (except in a static constructor or a variable initializer)",
4958                         /*1651*/ "Fields of static readonly field `{0}' cannot be passed ref or out (except in a static constructor)"
4959                 };
4960
4961                 // The return value is always null.  Returning a value simplifies calling code.
4962                 Expression Report_AssignToReadonly (ResolveContext ec, Expression right_side)
4963                 {
4964                         int i = 0;
4965                         if (right_side == EmptyExpression.OutAccess.Instance || right_side == EmptyExpression.LValueMemberOutAccess)
4966                                 i += 1;
4967                         if (IsStatic)
4968                                 i += 2;
4969                         if (right_side == EmptyExpression.LValueMemberAccess || right_side == EmptyExpression.LValueMemberOutAccess)
4970                                 i += 4;
4971                         ec.Report.Error (codes [i], loc, msgs [i], GetSignatureForError ());
4972
4973                         return null;
4974                 }
4975
4976                 override public Expression DoResolveLValue (ResolveContext ec, Expression right_side)
4977                 {
4978                         Expression e = DoResolve (ec, right_side);
4979
4980                         if (e == null)
4981                                 return null;
4982
4983                         spec.MemberDefinition.SetIsAssigned ();
4984
4985                         if ((right_side == EmptyExpression.UnaryAddress || right_side == EmptyExpression.OutAccess.Instance) &&
4986                                         (spec.Modifiers & Modifiers.VOLATILE) != 0) {
4987                                 ec.Report.Warning (420, 1, loc,
4988                                         "`{0}': A volatile field references will not be treated as volatile",
4989                                         spec.GetSignatureForError ());
4990                         }
4991
4992                         if (spec.IsReadOnly) {
4993                                 // InitOnly fields can only be assigned in constructors or initializers
4994                                 if (!ec.HasAny (ResolveContext.Options.FieldInitializerScope | ResolveContext.Options.ConstructorScope))
4995                                         return Report_AssignToReadonly (ec, right_side);
4996
4997                                 if (ec.HasSet (ResolveContext.Options.ConstructorScope)) {
4998
4999                                         // InitOnly fields cannot be assigned-to in a different constructor from their declaring type
5000                                         if (ec.CurrentMemberDefinition.Parent.Definition != spec.DeclaringType.GetDefinition ())
5001                                                 return Report_AssignToReadonly (ec, right_side);
5002                                         // static InitOnly fields cannot be assigned-to in an instance constructor
5003                                         if (IsStatic && !ec.IsStatic)
5004                                                 return Report_AssignToReadonly (ec, right_side);
5005                                         // instance constructors can't modify InitOnly fields of other instances of the same type
5006                                         if (!IsStatic && !(InstanceExpression is This))
5007                                                 return Report_AssignToReadonly (ec, right_side);
5008                                 }
5009                         }
5010
5011                         if (right_side == EmptyExpression.OutAccess.Instance &&
5012                                 !IsStatic && !(InstanceExpression is This) && TypeManager.mbr_type != null && TypeSpec.IsBaseClass (spec.DeclaringType, TypeManager.mbr_type, false)) {
5013                                 ec.Report.SymbolRelatedToPreviousError (spec.DeclaringType);
5014                                 ec.Report.Warning (197, 1, loc,
5015                                                 "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",
5016                                                 GetSignatureForError ());
5017                         }
5018
5019                         eclass = ExprClass.Variable;
5020                         return this;
5021                 }
5022
5023                 public override int GetHashCode ()
5024                 {
5025                         return spec.GetHashCode ();
5026                 }
5027
5028                 public bool IsFixed {
5029                         get {
5030                                 //
5031                                 // A variable of the form V.I is fixed when V is a fixed variable of a struct type
5032                                 //
5033                                 IVariableReference variable = InstanceExpression as IVariableReference;
5034                                 if (variable != null)
5035                                         return InstanceExpression.Type.IsStruct && variable.IsFixed;
5036
5037                                 IFixedExpression fe = InstanceExpression as IFixedExpression;
5038                                 return fe != null && fe.IsFixed;
5039                         }
5040                 }
5041
5042                 public override bool Equals (object obj)
5043                 {
5044                         FieldExpr fe = obj as FieldExpr;
5045                         if (fe == null)
5046                                 return false;
5047
5048                         if (spec != fe.spec)
5049                                 return false;
5050
5051                         if (InstanceExpression == null || fe.InstanceExpression == null)
5052                                 return true;
5053
5054                         return InstanceExpression.Equals (fe.InstanceExpression);
5055                 }
5056
5057                 public void Emit (EmitContext ec, bool leave_copy)
5058                 {
5059                         bool is_volatile = false;
5060
5061                         if ((spec.Modifiers & Modifiers.VOLATILE) != 0)
5062                                 is_volatile = true;
5063
5064                         spec.MemberDefinition.SetIsUsed ();
5065
5066                         if (IsStatic){
5067                                 if (is_volatile)
5068                                         ec.Emit (OpCodes.Volatile);
5069
5070                                 ec.Emit (OpCodes.Ldsfld, spec);
5071                         } else {
5072                                 if (!prepared)
5073                                         EmitInstance (ec, false);
5074
5075                                 // Optimization for build-in types
5076                                 if (TypeManager.IsStruct (type) && type == ec.CurrentType && InstanceExpression.Type == type) {
5077                                         ec.EmitLoadFromPtr (type);
5078                                 } else {
5079                                         var ff = spec as FixedFieldSpec;
5080                                         if (ff != null) {
5081                                                 ec.Emit (OpCodes.Ldflda, spec);
5082                                                 ec.Emit (OpCodes.Ldflda, ff.Element);
5083                                         } else {
5084                                                 if (is_volatile)
5085                                                         ec.Emit (OpCodes.Volatile);
5086
5087                                                 ec.Emit (OpCodes.Ldfld, spec);
5088                                         }
5089                                 }
5090                         }
5091
5092                         if (leave_copy) {
5093                                 ec.Emit (OpCodes.Dup);
5094                                 if (!IsStatic) {
5095                                         temp = new LocalTemporary (this.Type);
5096                                         temp.Store (ec);
5097                                 }
5098                         }
5099                 }
5100
5101                 public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool prepare_for_load)
5102                 {
5103                         prepared = prepare_for_load && !(source is DynamicExpressionStatement);
5104                         if (IsInstance)
5105                                 EmitInstance (ec, prepared);
5106
5107                         source.Emit (ec);
5108                         if (leave_copy) {
5109                                 ec.Emit (OpCodes.Dup);
5110                                 if (!IsStatic) {
5111                                         temp = new LocalTemporary (this.Type);
5112                                         temp.Store (ec);
5113                                 }
5114                         }
5115
5116                         if ((spec.Modifiers & Modifiers.VOLATILE) != 0)
5117                                 ec.Emit (OpCodes.Volatile);
5118
5119                         spec.MemberDefinition.SetIsAssigned ();
5120
5121                         if (IsStatic)
5122                                 ec.Emit (OpCodes.Stsfld, spec);
5123                         else
5124                                 ec.Emit (OpCodes.Stfld, spec);
5125
5126                         if (temp != null) {
5127                                 temp.Emit (ec);
5128                                 temp.Release (ec);
5129                                 temp = null;
5130                         }
5131                 }
5132
5133                 public override void Emit (EmitContext ec)
5134                 {
5135                         Emit (ec, false);
5136                 }
5137
5138                 public override void EmitSideEffect (EmitContext ec)
5139                 {
5140                         bool is_volatile = (spec.Modifiers & Modifiers.VOLATILE) != 0;
5141
5142                         if (is_volatile) // || is_marshal_by_ref ())
5143                                 base.EmitSideEffect (ec);
5144                 }
5145
5146                 public void AddressOf (EmitContext ec, AddressOp mode)
5147                 {
5148                         if ((mode & AddressOp.Store) != 0)
5149                                 spec.MemberDefinition.SetIsAssigned ();
5150                         if ((mode & AddressOp.Load) != 0)
5151                                 spec.MemberDefinition.SetIsUsed ();
5152
5153                         //
5154                         // Handle initonly fields specially: make a copy and then
5155                         // get the address of the copy.
5156                         //
5157                         bool need_copy;
5158                         if (spec.IsReadOnly){
5159                                 need_copy = true;
5160                                 if (ec.HasSet (EmitContext.Options.ConstructorScope) && spec.DeclaringType == ec.CurrentType) {
5161                                         if (IsStatic){
5162                                                 if (ec.IsStatic)
5163                                                         need_copy = false;
5164                                         } else
5165                                                 need_copy = false;
5166                                 }
5167                         } else
5168                                 need_copy = false;
5169
5170                         if (need_copy){
5171                                 LocalBuilder local;
5172                                 Emit (ec);
5173                                 local = ec.DeclareLocal (type, false);
5174                                 ec.Emit (OpCodes.Stloc, local);
5175                                 ec.Emit (OpCodes.Ldloca, local);
5176                                 return;
5177                         }
5178
5179
5180                         if (IsStatic){
5181                                 ec.Emit (OpCodes.Ldsflda, spec);
5182                         } else {
5183                                 if (!prepared)
5184                                         EmitInstance (ec, false);
5185                                 ec.Emit (OpCodes.Ldflda, spec);
5186                         }
5187                 }
5188
5189                 public SLE.Expression MakeAssignExpression (BuilderContext ctx, Expression source)
5190                 {
5191                         return MakeExpression (ctx);
5192                 }
5193
5194                 public override SLE.Expression MakeExpression (BuilderContext ctx)
5195                 {
5196 #if STATIC
5197                         return base.MakeExpression (ctx);
5198 #else
5199                         return SLE.Expression.Field (
5200                                 IsStatic ? null : InstanceExpression.MakeExpression (ctx),
5201                                 spec.GetMetaInfo ());
5202 #endif
5203                 }
5204
5205                 public override void SetTypeArguments (ResolveContext ec, TypeArguments ta)
5206                 {
5207                         Error_TypeArgumentsCannotBeUsed (ec.Report, "field", GetSignatureForError (), loc);
5208                 }
5209         }
5210
5211
5212         /// <summary>
5213         ///   Expression that evaluates to a Property.  The Assign class
5214         ///   might set the `Value' expression if we are in an assignment.
5215         ///
5216         ///   This is not an LValue because we need to re-write the expression, we
5217         ///   can not take data from the stack and store it.
5218         /// </summary>
5219         class PropertyExpr : PropertyOrIndexerExpr<PropertySpec>
5220         {
5221                 public PropertyExpr (PropertySpec spec, Location l)
5222                         : base (l)
5223                 {
5224                         best_candidate = spec;
5225                         type = spec.MemberType;
5226                 }
5227
5228                 #region Properties
5229
5230                 protected override TypeSpec DeclaringType {
5231                         get {
5232                                 return best_candidate.DeclaringType;
5233                         }
5234                 }
5235
5236                 public override string Name {
5237                         get {
5238                                 return best_candidate.Name;
5239                         }
5240                 }
5241
5242                 public override bool IsInstance {
5243                         get {
5244                                 return !IsStatic;
5245                         }
5246                 }
5247
5248                 public override bool IsStatic {
5249                         get {
5250                                 return best_candidate.IsStatic;
5251                         }
5252                 }
5253
5254                 public PropertySpec PropertyInfo {
5255                         get {
5256                                 return best_candidate;
5257                         }
5258                 }
5259
5260                 #endregion
5261
5262                 public override Expression CreateExpressionTree (ResolveContext ec)
5263                 {
5264                         Arguments args;
5265                         if (IsSingleDimensionalArrayLength ()) {
5266                                 args = new Arguments (1);
5267                                 args.Add (new Argument (InstanceExpression.CreateExpressionTree (ec)));
5268                                 return CreateExpressionFactoryCall (ec, "ArrayLength", args);
5269                         }
5270
5271                         args = new Arguments (2);
5272                         if (InstanceExpression == null)
5273                                 args.Add (new Argument (new NullLiteral (loc)));
5274                         else
5275                                 args.Add (new Argument (InstanceExpression.CreateExpressionTree (ec)));
5276                         args.Add (new Argument (new TypeOfMethod (Getter, loc)));
5277                         return CreateExpressionFactoryCall (ec, "Property", args);
5278                 }
5279
5280                 public Expression CreateSetterTypeOfExpression ()
5281                 {
5282                         return new TypeOfMethod (Setter, loc);
5283                 }
5284
5285                 public override string GetSignatureForError ()
5286                 {
5287                         return best_candidate.GetSignatureForError ();
5288                 }
5289
5290                 public override SLE.Expression MakeAssignExpression (BuilderContext ctx, Expression source)
5291                 {
5292 #if STATIC
5293                         return base.MakeExpression (ctx);
5294 #else
5295                         return SLE.Expression.Property (InstanceExpression.MakeExpression (ctx), (MethodInfo) Setter.GetMetaInfo ());
5296 #endif
5297                 }
5298
5299                 public override SLE.Expression MakeExpression (BuilderContext ctx)
5300                 {
5301 #if STATIC
5302                         return base.MakeExpression (ctx);
5303 #else
5304                         return SLE.Expression.Property (InstanceExpression.MakeExpression (ctx), (MethodInfo) Getter.GetMetaInfo ());
5305 #endif
5306                 }
5307
5308                 void Error_PropertyNotValid (ResolveContext ec)
5309                 {
5310                         ec.Report.SymbolRelatedToPreviousError (best_candidate);
5311                         ec.Report.Error (1546, loc, "Property or event `{0}' is not supported by the C# language",
5312                                 GetSignatureForError ());
5313                 }
5314
5315                 bool IsSingleDimensionalArrayLength ()
5316                 {
5317                         if (best_candidate.DeclaringType.BuildinType != BuildinTypeSpec.Type.Array || !best_candidate.HasGet || Name != "Length")
5318                                 return false;
5319
5320                         ArrayContainer ac = InstanceExpression.Type as ArrayContainer;
5321                         return ac != null && ac.Rank == 1;
5322                 }
5323
5324                 public override void Emit (EmitContext ec, bool leave_copy)
5325                 {
5326                         //
5327                         // Special case: length of single dimension array property is turned into ldlen
5328                         //
5329                         if (IsSingleDimensionalArrayLength ()) {
5330                                 if (!prepared)
5331                                         EmitInstance (ec, false);
5332                                 ec.Emit (OpCodes.Ldlen);
5333                                 ec.Emit (OpCodes.Conv_I4);
5334                                 return;
5335                         }
5336
5337                         Invocation.EmitCall (ec, InstanceExpression, Getter, null, loc, prepared, false);
5338
5339                         if (leave_copy) {
5340                                 ec.Emit (OpCodes.Dup);
5341                                 if (!IsStatic) {
5342                                         temp = new LocalTemporary (this.Type);
5343                                         temp.Store (ec);
5344                                 }
5345                         }
5346                 }
5347
5348                 public override void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool prepare_for_load)
5349                 {
5350                         Arguments args;
5351
5352                         if (prepare_for_load && !(source is DynamicExpressionStatement)) {
5353                                 args = new Arguments (0);
5354                                 prepared = true;
5355                                 source.Emit (ec);
5356
5357                                 if (leave_copy) {
5358                                         ec.Emit (OpCodes.Dup);
5359                                         if (!IsStatic) {
5360                                                 temp = new LocalTemporary (this.Type);
5361                                                 temp.Store (ec);
5362                                         }
5363                                 }
5364                         } else {
5365                                 args = new Arguments (1);
5366
5367                                 if (leave_copy) {
5368                                         source.Emit (ec);
5369                                         temp = new LocalTemporary (this.Type);
5370                                         temp.Store (ec);
5371                                         args.Add (new Argument (temp));
5372                                 } else {
5373                                         args.Add (new Argument (source));
5374                                 }
5375                         }
5376
5377                         Invocation.EmitCall (ec, InstanceExpression, Setter, args, loc, false, prepared);
5378
5379                         if (temp != null) {
5380                                 temp.Emit (ec);
5381                                 temp.Release (ec);
5382                         }
5383                 }
5384
5385                 protected override Expression OverloadResolve (ResolveContext rc, Expression right_side)
5386                 {
5387                         eclass = ExprClass.PropertyAccess;
5388
5389                         if (best_candidate.IsNotRealProperty) {
5390                                 Error_PropertyNotValid (rc);
5391                         }
5392
5393                         ResolveInstanceExpression (rc, right_side);
5394
5395                         if ((best_candidate.Modifiers & (Modifiers.ABSTRACT | Modifiers.VIRTUAL)) != 0 && best_candidate.DeclaringType != InstanceExpression.Type) {
5396                                 var filter = new MemberFilter (best_candidate.Name, 0, MemberKind.Property, null, null);
5397                                 var p = MemberCache.FindMember (InstanceExpression.Type, filter, BindingRestriction.InstanceOnly | BindingRestriction.OverrideOnly) as PropertySpec;
5398                                 if (p != null) {
5399                                         type = p.MemberType;
5400                                 }
5401                         }
5402
5403                         DoBestMemberChecks (rc, best_candidate);
5404                         return this;
5405                 }
5406
5407                 public override void SetTypeArguments (ResolveContext ec, TypeArguments ta)
5408                 {
5409                         Error_TypeArgumentsCannotBeUsed (ec.Report, "property", GetSignatureForError (), loc);
5410                 }
5411         }
5412
5413         abstract class PropertyOrIndexerExpr<T> : MemberExpr, IDynamicAssign where T : PropertySpec
5414         {
5415                 // getter and setter can be different for base calls
5416                 MethodSpec getter, setter;
5417                 protected T best_candidate;
5418
5419                 protected LocalTemporary temp;
5420                 protected bool prepared;
5421
5422                 protected PropertyOrIndexerExpr (Location l)
5423                 {
5424                         loc = l;
5425                 }
5426
5427                 #region Properties
5428
5429                 public MethodSpec Getter {
5430                         get {
5431                                 return getter;
5432                         }
5433                         set {
5434                                 getter = value;
5435                         }
5436                 }
5437
5438                 public MethodSpec Setter {
5439                         get {
5440                                 return setter;
5441                         }
5442                         set {
5443                                 setter = value;
5444                         }
5445                 }
5446
5447                 #endregion
5448
5449                 protected override Expression DoResolve (ResolveContext ec)
5450                 {
5451                         if (eclass == ExprClass.Unresolved) {
5452                                 var expr = OverloadResolve (ec, null);
5453                                 if (expr == null)
5454                                         return null;
5455
5456                                 if (expr != this)
5457                                         return expr.Resolve (ec);
5458                         }
5459
5460                         if (!ResolveGetter (ec))
5461                                 return null;
5462
5463                         return this;
5464                 }
5465
5466                 public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
5467                 {
5468                         if (right_side == EmptyExpression.OutAccess.Instance) {
5469                                 // TODO: best_candidate can be null at this point
5470                                 INamedBlockVariable variable = null;
5471                                 if (best_candidate != null && ec.CurrentBlock.ParametersBlock.TopBlock.GetLocalName (best_candidate.Name, ec.CurrentBlock, ref variable) && variable is Linq.RangeVariable) {
5472                                         ec.Report.Error (1939, loc, "A range variable `{0}' may not be passes as `ref' or `out' parameter",
5473                                                 best_candidate.Name);
5474                                 } else {
5475                                         right_side.DoResolveLValue (ec, this);
5476                                 }
5477                                 return null;
5478                         }
5479
5480                         // if the property/indexer returns a value type, and we try to set a field in it
5481                         if (right_side == EmptyExpression.LValueMemberAccess || right_side == EmptyExpression.LValueMemberOutAccess) {
5482                                 Error_CannotModifyIntermediateExpressionValue (ec);
5483                         }
5484
5485                         if (eclass == ExprClass.Unresolved) {
5486                                 var expr = OverloadResolve (ec, right_side);
5487                                 if (expr == null)
5488                                         return null;
5489
5490                                 if (expr != this)
5491                                         return expr.ResolveLValue (ec, right_side);
5492                         }
5493
5494                         if (!ResolveSetter (ec))
5495                                 return null;
5496
5497                         return this;
5498                 }
5499
5500                 //
5501                 // Implements the IAssignMethod interface for assignments
5502                 //
5503                 public abstract void Emit (EmitContext ec, bool leave_copy);
5504                 public abstract void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool prepare_for_load);
5505
5506                 public override void Emit (EmitContext ec)
5507                 {
5508                         Emit (ec, false);
5509                 }
5510
5511                 public abstract SLE.Expression MakeAssignExpression (BuilderContext ctx, Expression source);
5512
5513                 protected abstract Expression OverloadResolve (ResolveContext rc, Expression right_side);
5514
5515                 bool ResolveGetter (ResolveContext rc)
5516                 {
5517                         if (!best_candidate.HasGet) {
5518                                 if (InstanceExpression != EmptyExpression.Null) {
5519                                         rc.Report.SymbolRelatedToPreviousError (best_candidate);
5520                                         rc.Report.Error (154, loc, "The property or indexer `{0}' cannot be used in this context because it lacks the `get' accessor",
5521                                                 best_candidate.GetSignatureForError ());
5522                                         return false;
5523                                 }
5524                         } else if (!best_candidate.Get.IsAccessible (rc.CurrentType)) {
5525                                 if (best_candidate.HasDifferentAccessibility) {
5526                                         rc.Report.SymbolRelatedToPreviousError (best_candidate.Get);
5527                                         rc.Report.Error (271, loc, "The property or indexer `{0}' cannot be used in this context because the get accessor is inaccessible",
5528                                                 TypeManager.CSharpSignature (best_candidate));
5529                                 } else {
5530                                         rc.Report.SymbolRelatedToPreviousError (best_candidate.Get);
5531                                         ErrorIsInaccesible (rc, best_candidate.Get.GetSignatureForError (), loc);
5532                                 }
5533                         }
5534
5535                         if (best_candidate.HasDifferentAccessibility) {
5536                                 CheckProtectedMemberAccess (rc, best_candidate.Get);
5537                         }
5538
5539                         getter = CandidateToBaseOverride (rc, best_candidate.Get);
5540                         return true;
5541                 }
5542
5543                 bool ResolveSetter (ResolveContext rc)
5544                 {
5545                         if (!best_candidate.HasSet) {
5546                                 rc.Report.Error (200, loc, "Property or indexer `{0}' cannot be assigned to (it is read-only)",
5547                                         GetSignatureForError ());
5548                                 return false;
5549                         }
5550
5551                         if (!best_candidate.Set.IsAccessible (rc.CurrentType)) {
5552                                 if (best_candidate.HasDifferentAccessibility) {
5553                                         rc.Report.SymbolRelatedToPreviousError (best_candidate.Set);
5554                                         rc.Report.Error (272, loc, "The property or indexer `{0}' cannot be used in this context because the set accessor is inaccessible",
5555                                                 GetSignatureForError ());
5556                                 } else {
5557                                         rc.Report.SymbolRelatedToPreviousError (best_candidate.Set);
5558                                         ErrorIsInaccesible (rc, best_candidate.Set.GetSignatureForError (), loc);
5559                                 }
5560                         }
5561
5562                         if (best_candidate.HasDifferentAccessibility)
5563                                 CheckProtectedMemberAccess (rc, best_candidate.Set);
5564
5565                         setter = CandidateToBaseOverride (rc, best_candidate.Set);
5566                         return true;
5567                 }
5568         }
5569
5570         /// <summary>
5571         ///   Fully resolved expression that evaluates to an Event
5572         /// </summary>
5573         public class EventExpr : MemberExpr, IAssignMethod
5574         {
5575                 readonly EventSpec spec;
5576                 MethodSpec op;
5577
5578                 public EventExpr (EventSpec spec, Location loc)
5579                 {
5580                         this.spec = spec;
5581                         this.loc = loc;
5582                 }
5583
5584                 #region Properties
5585
5586                 protected override TypeSpec DeclaringType {
5587                         get {
5588                                 return spec.DeclaringType;
5589                         }
5590                 }
5591
5592                 public override string Name {
5593                         get {
5594                                 return spec.Name;
5595                         }
5596                 }
5597
5598                 public override bool IsInstance {
5599                         get {
5600                                 return !spec.IsStatic;
5601                         }
5602                 }
5603
5604                 public override bool IsStatic {
5605                         get {
5606                                 return spec.IsStatic;
5607                         }
5608                 }
5609
5610                 public MethodSpec Operator {
5611                         get {
5612                                 return op;
5613                         }
5614                 }
5615
5616                 #endregion
5617
5618                 public override MemberExpr ResolveMemberAccess (ResolveContext ec, Expression left, SimpleName original)
5619                 {
5620                         //
5621                         // If the event is local to this class and we are not lhs of +=/-= we transform ourselves into a FieldExpr
5622                         //
5623                         if (!ec.HasSet (ResolveContext.Options.CompoundAssignmentScope)) {
5624                                 if (spec.BackingField != null &&
5625                                         (spec.DeclaringType == ec.CurrentType || TypeManager.IsNestedChildOf (ec.CurrentType, spec.DeclaringType.MemberDefinition))) {
5626
5627                                         spec.MemberDefinition.SetIsUsed ();
5628
5629                                         if (!ec.IsObsolete) {
5630                                                 ObsoleteAttribute oa = spec.GetAttributeObsolete ();
5631                                                 if (oa != null)
5632                                                         AttributeTester.Report_ObsoleteMessage (oa, spec.GetSignatureForError (), loc, ec.Report);
5633                                         }
5634
5635                                         if ((spec.Modifiers & (Modifiers.ABSTRACT | Modifiers.EXTERN)) != 0)
5636                                                 Error_AssignmentEventOnly (ec);
5637
5638                                         FieldExpr ml = new FieldExpr (spec.BackingField, loc);
5639
5640                                         InstanceExpression = null;
5641
5642                                         return ml.ResolveMemberAccess (ec, left, original);
5643                                 }
5644                         }
5645
5646                         return base.ResolveMemberAccess (ec, left, original);
5647                 }
5648
5649                 public override Expression CreateExpressionTree (ResolveContext ec)
5650                 {
5651                         throw new NotSupportedException ("ET");
5652                 }
5653
5654                 public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
5655                 {
5656                         if (right_side == EmptyExpression.EventAddition) {
5657                                 op = spec.AccessorAdd;
5658                         } else if (right_side == EmptyExpression.EventSubtraction) {
5659                                 op = spec.AccessorRemove;
5660                         }
5661
5662                         if (op == null) {
5663                                 Error_AssignmentEventOnly (ec);
5664                                 return null;
5665                         }
5666
5667                         op = CandidateToBaseOverride (ec, op);
5668                         return this;
5669                 }
5670
5671                 protected override Expression DoResolve (ResolveContext ec)
5672                 {
5673                         eclass = ExprClass.EventAccess;
5674                         type = spec.MemberType;
5675
5676                         ResolveInstanceExpression (ec, null);
5677
5678                         if (!ec.HasSet (ResolveContext.Options.CompoundAssignmentScope)) {
5679                                 Error_AssignmentEventOnly (ec);
5680                         }
5681
5682                         DoBestMemberChecks (ec, spec);
5683                         return this;
5684                 }
5685
5686                 public override void Emit (EmitContext ec)
5687                 {
5688                         throw new NotSupportedException ();
5689                         //Error_CannotAssign ();
5690                 }
5691
5692                 #region IAssignMethod Members
5693
5694                 public void Emit (EmitContext ec, bool leave_copy)
5695                 {
5696                         throw new NotImplementedException ();
5697                 }
5698
5699                 public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool prepare_for_load)
5700                 {
5701                         if (leave_copy || !prepare_for_load)
5702                                 throw new NotImplementedException ("EventExpr::EmitAssign");
5703
5704                         Arguments args = new Arguments (1);
5705                         args.Add (new Argument (source));
5706                         Invocation.EmitCall (ec, InstanceExpression, op, args, loc);
5707                 }
5708
5709                 #endregion
5710
5711                 void Error_AssignmentEventOnly (ResolveContext ec)
5712                 {
5713                         if (spec.DeclaringType == ec.CurrentType || TypeManager.IsNestedChildOf (ec.CurrentType, spec.DeclaringType.MemberDefinition)) {
5714                                 ec.Report.Error (79, loc,
5715                                         "The event `{0}' can only appear on the left hand side of `+=' or `-=' operator",
5716                                         GetSignatureForError ());
5717                         } else {
5718                                 ec.Report.Error (70, loc,
5719                                         "The event `{0}' can only appear on the left hand side of += or -= when used outside of the type `{1}'",
5720                                         GetSignatureForError (), spec.DeclaringType.GetSignatureForError ());
5721                         }
5722                 }
5723
5724                 protected override void Error_CannotCallAbstractBase (ResolveContext rc, string name)
5725                 {
5726                         name = name.Substring (0, name.LastIndexOf ('.'));
5727                         base.Error_CannotCallAbstractBase (rc, name);
5728                 }
5729
5730                 public override string GetSignatureForError ()
5731                 {
5732                         return TypeManager.CSharpSignature (spec);
5733                 }
5734
5735                 public override void SetTypeArguments (ResolveContext ec, TypeArguments ta)
5736                 {
5737                         Error_TypeArgumentsCannotBeUsed (ec.Report, "event", GetSignatureForError (), loc);
5738                 }
5739         }
5740
5741         public class TemporaryVariableReference : VariableReference
5742         {
5743                 public class Declarator : Statement
5744                 {
5745                         TemporaryVariableReference variable;
5746
5747                         public Declarator (TemporaryVariableReference variable)
5748                         {
5749                                 this.variable = variable;
5750                                 loc = variable.loc;
5751                         }
5752
5753                         protected override void DoEmit (EmitContext ec)
5754                         {
5755                                 variable.li.CreateBuilder (ec);
5756                         }
5757
5758                         protected override void CloneTo (CloneContext clonectx, Statement target)
5759                         {
5760                                 // Nothing
5761                         }
5762                 }
5763
5764                 LocalVariable li;
5765
5766                 public TemporaryVariableReference (LocalVariable li, Location loc)
5767                 {
5768                         this.li = li;
5769                         this.type = li.Type;
5770                         this.loc = loc;
5771                 }
5772
5773                 public override bool IsLockedByStatement {
5774                         get {
5775                                 return false;
5776                         }
5777                         set {
5778                         }
5779                 }
5780
5781                 public LocalVariable LocalInfo {
5782                     get {
5783                         return li;
5784                     }
5785                 }
5786
5787                 public static TemporaryVariableReference Create (TypeSpec type, Block block, Location loc)
5788                 {
5789                         var li = LocalVariable.CreateCompilerGenerated (type, block, loc);
5790                         return new TemporaryVariableReference (li, loc);
5791                 }
5792
5793                 public override Expression CreateExpressionTree (ResolveContext ec)
5794                 {
5795                         throw new NotSupportedException ("ET");
5796                 }
5797
5798                 protected override Expression DoResolve (ResolveContext ec)
5799                 {
5800                         eclass = ExprClass.Variable;
5801
5802                         //
5803                         // Don't capture temporary variables except when using
5804                         // iterator redirection
5805                         //
5806                         if (ec.CurrentAnonymousMethod != null && ec.CurrentAnonymousMethod.IsIterator && ec.IsVariableCapturingRequired) {
5807                                 AnonymousMethodStorey storey = li.Block.Explicit.CreateAnonymousMethodStorey (ec);
5808                                 storey.CaptureLocalVariable (ec, li);
5809                         }
5810
5811                         return this;
5812                 }
5813
5814                 public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
5815                 {
5816                         return Resolve (ec);
5817                 }
5818
5819                 public override void Emit (EmitContext ec)
5820                 {
5821                         li.CreateBuilder (ec);
5822
5823                         Emit (ec, false);
5824                 }
5825
5826                 public void EmitAssign (EmitContext ec, Expression source)
5827                 {
5828                         li.CreateBuilder (ec);
5829
5830                         EmitAssign (ec, source, false, false);
5831                 }
5832
5833                 public override HoistedVariable GetHoistedVariable (AnonymousExpression ae)
5834                 {
5835                         return li.HoistedVariant;
5836                 }
5837
5838                 public override bool IsFixed {
5839                         get { return true; }
5840                 }
5841
5842                 public override bool IsRef {
5843                         get { return false; }
5844                 }
5845
5846                 public override string Name {
5847                         get { throw new NotImplementedException (); }
5848                 }
5849
5850                 public override void SetHasAddressTaken ()
5851                 {
5852                         throw new NotImplementedException ();
5853                 }
5854
5855                 protected override ILocalVariable Variable {
5856                         get { return li; }
5857                 }
5858
5859                 public override VariableInfo VariableInfo {
5860                         get { throw new NotImplementedException (); }
5861                 }
5862         }
5863
5864         ///
5865         /// Handles `var' contextual keyword; var becomes a keyword only
5866         /// if no type called var exists in a variable scope
5867         ///
5868         class VarExpr : SimpleName
5869         {
5870                 public VarExpr (Location loc)
5871                         : base ("var", loc)
5872                 {
5873                 }
5874
5875                 public bool InferType (ResolveContext ec, Expression right_side)
5876                 {
5877                         if (type != null)
5878                                 throw new InternalErrorException ("An implicitly typed local variable could not be redefined");
5879
5880                         type = right_side.Type;
5881                         if (type == InternalType.Null || type.Kind == MemberKind.Void || type == InternalType.AnonymousMethod || type == InternalType.MethodGroup) {
5882                                 ec.Report.Error (815, loc,
5883                                         "An implicitly typed local variable declaration cannot be initialized with `{0}'",
5884                                         type.GetSignatureForError ());
5885                                 return false;
5886                         }
5887
5888                         eclass = ExprClass.Variable;
5889                         return true;
5890                 }
5891
5892                 protected override void Error_TypeOrNamespaceNotFound (IMemberContext ec)
5893                 {
5894                         if (ec.Module.Compiler.Settings.Version < LanguageVersion.V_3)
5895                                 base.Error_TypeOrNamespaceNotFound (ec);
5896                         else
5897                                 ec.Module.Compiler.Report.Error (825, loc, "The contextual keyword `var' may only appear within a local variable declaration");
5898                 }
5899         }
5900 }