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.Diagnostics;
  16 using System.Reflection;
  17 using System.Reflection.Emit;
  18 using System.Text;
  19 using SLE = System.Linq.Expressions;
  20 using System.Linq;
  21
  22 namespace Mono.CSharp {
  23
  24         /// <remarks>
  25         ///   The ExprClass class contains the is used to pass the
  26         ///   classification of an expression (value, variable, namespace,
  27         ///   type, method group, property access, event access, indexer access,
  28         ///   nothing).
  29         /// </remarks>
  30         public enum ExprClass : byte {
  31                 Unresolved      = 0,
  32
  33                 Value,
  34                 Variable,
  35                 Namespace,
  36                 Type,
  37                 TypeParameter,
  38                 MethodGroup,
  39                 PropertyAccess,
  40                 EventAccess,
  41                 IndexerAccess,
  42                 Nothing,
  43         }
  44
  45         /// <remarks>
  46         ///   This is used to tell Resolve in which types of expressions we're
  47         ///   interested.
  48         /// </remarks>
  49         [Flags]
  50         public enum ResolveFlags {
  51                 // Returns Value, Variable, PropertyAccess, EventAccess or IndexerAccess.
  52                 VariableOrValue         = 1,
  53
  54                 // Returns a type expression.
  55                 Type                    = 1 << 1,
  56
  57                 // Returns a method group.
  58                 MethodGroup             = 1 << 2,
  59
  60                 TypeParameter   = 1 << 3,
  61
  62                 // Mask of all the expression class flags.
  63                 MaskExprClass = VariableOrValue | Type | MethodGroup | TypeParameter,
  64         }
  65
  66         //
  67         // This is just as a hint to AddressOf of what will be done with the
  68         // address.
  69         [Flags]
  70         public enum AddressOp {
  71                 Store = 1,
  72                 Load  = 2,
  73                 LoadStore = 3
  74         };
  75
  76         /// <summary>
  77         ///   This interface is implemented by variables
  78         /// </summary>
  79         public interface IMemoryLocation {
  80                 /// <summary>
  81                 ///   The AddressOf method should generate code that loads
  82                 ///   the address of the object and leaves it on the stack.
  83                 ///
  84                 ///   The `mode' argument is used to notify the expression
  85                 ///   of whether this will be used to read from the address or
  86                 ///   write to the address.
  87                 ///
  88                 ///   This is just a hint that can be used to provide good error
  89                 ///   reporting, and should have no other side effects.
  90                 /// </summary>
  91                 void AddressOf (EmitContext ec, AddressOp mode);
  92         }
  93
  94         //
  95         // An expressions resolved as a direct variable reference
  96         //
  97         public interface IVariableReference : IFixedExpression
  98         {
  99                 bool IsHoisted { get; }
 100                 string Name { get; }
 101                 VariableInfo VariableInfo { get; }
 102
 103                 void SetHasAddressTaken ();
 104         }
 105
 106         //
 107         // Implemented by an expression which could be or is always
 108         // fixed
 109         //
 110         public interface IFixedExpression
 111         {
 112                 bool IsFixed { get; }
 113         }
 114
 115         /// <remarks>
 116         ///   Base class for expressions
 117         /// </remarks>
 118         public abstract class Expression {
 119                 public ExprClass eclass;
 120                 protected TypeSpec type;
 121                 protected Location loc;
 122
 123                 public TypeSpec Type {
 124                         get { return type; }
 125                         set { type = value; }
 126                 }
 127
 128                 public Location Location {
 129                         get { return loc; }
 130                 }
 131
 132                 // Not nice but we have broken hierarchy.
 133                 public virtual void CheckMarshalByRefAccess (ResolveContext ec)
 134                 {
 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                 // C# 3.0 introduced contextual keywords (var) which behaves like a type if type with
 200                 // same name exists or as a keyword when no type was found
 201                 //
 202                 public virtual TypeExpr ResolveAsContextualType (IMemberContext rc, bool silent)
 203                 {
 204                         return ResolveAsTypeTerminal (rc, silent);
 205                 }
 206
 207                 //
 208                 // This is used to resolve the expression as a type, a null
 209                 // value will be returned if the expression is not a type
 210                 // reference
 211                 //
 212                 public virtual TypeExpr ResolveAsTypeTerminal (IMemberContext ec , bool silent)
 213                 {
 214                         int errors = ec.Compiler.Report.Errors;
 215
 216                         FullNamedExpression fne = ResolveAsTypeStep (ec, silent);
 217
 218                         if (fne == null)
 219                                 return null;
 220
 221                         TypeExpr te = fne as TypeExpr;
 222                         if (te == null) {
 223                                 if (!silent && errors == ec.Compiler.Report.Errors)
 224                                         fne.Error_UnexpectedKind (ec.Compiler.Report, null, "type", loc);
 225                                 return null;
 226                         }
 227
 228                         if (!te.CheckAccessLevel (ec)) {
 229                                 ec.Compiler.Report.SymbolRelatedToPreviousError (te.Type);
 230                                 ErrorIsInaccesible (ec, te.Type.GetSignatureForError (), loc);
 231                         }
 232
 233                         te.loc = loc;
 234
 235                         //
 236                         // Obsolete checks cannot be done when resolving base context as they
 237                         // require type dependecies to be set but we are just resolving them
 238                         //
 239                         if (!silent && !(ec is TypeContainer.BaseContext)) {
 240                                 ObsoleteAttribute obsolete_attr = te.Type.GetAttributeObsolete ();
 241                                 if (obsolete_attr != null && !ec.IsObsolete) {
 242                                         AttributeTester.Report_ObsoleteMessage (obsolete_attr, te.GetSignatureForError (), Location, ec.Compiler.Report);
 243                                 }
 244                         }
 245
 246                         return te;
 247                 }
 248
 249                 public static void ErrorIsInaccesible (IMemberContext rc, string member, Location loc)
 250                 {
 251                         rc.Compiler.Report.Error (122, loc, "`{0}' is inaccessible due to its protection level", member);
 252                 }
 253
 254                 public void Error_ExpressionMustBeConstant (ResolveContext rc, Location loc, string e_name)
 255                 {
 256                         rc.Report.Error (133, loc, "The expression being assigned to `{0}' must be constant", e_name);
 257                 }
 258
 259                 public void Error_ConstantCanBeInitializedWithNullOnly (ResolveContext rc, TypeSpec type, Location loc, string name)
 260                 {
 261                         rc.Report.Error (134, loc, "A constant `{0}' of reference type `{1}' can only be initialized with null",
 262                                 name, TypeManager.CSharpName (type));
 263                 }
 264
 265                 public static void Error_InvalidExpressionStatement (Report Report, Location loc)
 266                 {
 267                         Report.Error (201, loc, "Only assignment, call, increment, decrement, and new object " +
 268                                        "expressions can be used as a statement");
 269                 }
 270
 271                 public void Error_InvalidExpressionStatement (BlockContext ec)
 272                 {
 273                         Error_InvalidExpressionStatement (ec.Report, loc);
 274                 }
 275
 276                 public static void Error_VoidInvalidInTheContext (Location loc, Report Report)
 277                 {
 278                         Report.Error (1547, loc, "Keyword `void' cannot be used in this context");
 279                 }
 280
 281                 public virtual void Error_ValueCannotBeConverted (ResolveContext ec, Location loc, TypeSpec target, bool expl)
 282                 {
 283                         Error_ValueCannotBeConvertedCore (ec, loc, target, expl);
 284                 }
 285
 286                 protected void Error_ValueCannotBeConvertedCore (ResolveContext ec, Location loc, TypeSpec target, bool expl)
 287                 {
 288                         // The error was already reported as CS1660
 289                         if (type == InternalType.AnonymousMethod)
 290                                 return;
 291
 292 /*
 293                         if (TypeManager.IsGenericParameter (Type) && TypeManager.IsGenericParameter (target) && type.Name == target.Name) {
 294                                 string sig1 = type.DeclaringMethod == null ?
 295                                         TypeManager.CSharpName (type.DeclaringType) :
 296                                         TypeManager.CSharpSignature (type.DeclaringMethod);
 297                                 string sig2 = target.DeclaringMethod == null ?
 298                                         TypeManager.CSharpName (target.DeclaringType) :
 299                                         TypeManager.CSharpSignature (target.DeclaringMethod);
 300                                 ec.Report.ExtraInformation (loc,
 301                                         String.Format (
 302                                                 "The generic parameter `{0}' of `{1}' cannot be converted to the generic parameter `{0}' of `{2}' (in the previous ",
 303                                                 Type.Name, sig1, sig2));
 304                         } else if (Type.MetaInfo.FullName == target.MetaInfo.FullName) {
 305                                 ec.Report.ExtraInformation (loc,
 306                                         String.Format (
 307                                         "The type `{0}' has two conflicting definitions, one comes from `{1}' and the other from `{2}' (in the previous ",
 308                                         Type.MetaInfo.FullName, Type.Assembly.FullName, target.Assembly.FullName));
 309                         }
 310 */
 311                         if (expl) {
 312                                 ec.Report.Error (30, loc, "Cannot convert type `{0}' to `{1}'",
 313                                         TypeManager.CSharpName (type), TypeManager.CSharpName (target));
 314                                 return;
 315                         }
 316
 317                         ec.Report.DisableReporting ();
 318                         bool expl_exists = Convert.ExplicitConversion (ec, this, target, Location.Null) != null;
 319                         ec.Report.EnableReporting ();
 320
 321                         if (expl_exists) {
 322                                 ec.Report.Error (266, loc, "Cannot implicitly convert type `{0}' to `{1}'. " +
 323                                               "An explicit conversion exists (are you missing a cast?)",
 324                                         TypeManager.CSharpName (Type), TypeManager.CSharpName (target));
 325                                 return;
 326                         }
 327
 328                         ec.Report.Error (29, loc, "Cannot implicitly convert type `{0}' to `{1}'",
 329                                 type.GetSignatureForError (), target.GetSignatureForError ());
 330                 }
 331
 332                 public virtual void Error_VariableIsUsedBeforeItIsDeclared (Report Report, string name)
 333                 {
 334                         Report.Error (841, loc, "A local variable `{0}' cannot be used before it is declared", name);
 335                 }
 336
 337                 public void Error_TypeArgumentsCannotBeUsed (Report report, Location loc, MemberSpec member, int arity)
 338                 {
 339                         // Better message for possible generic expressions
 340                         if (member != null && (member.Kind & MemberKind.GenericMask) != 0) {
 341                                 report.SymbolRelatedToPreviousError (member);
 342                                 if (member is TypeSpec)
 343                                         member = ((TypeSpec) member).GetDefinition ();
 344                                 else
 345                                         member = ((MethodSpec) member).GetGenericMethodDefinition ();
 346
 347                                 string name = member.Kind == MemberKind.Method ? "method" : "type";
 348                                 if (member.IsGeneric) {
 349                                         report.Error (305, loc, "Using the generic {0} `{1}' requires `{2}' type argument(s)",
 350                                                 name, member.GetSignatureForError (), member.Arity.ToString ());
 351                                 } else {
 352                                         report.Error (308, loc, "The non-generic {0} `{1}' cannot be used with the type arguments",
 353                                                 name, member.GetSignatureForError ());
 354                                 }
 355                         } else {
 356                                 Error_TypeArgumentsCannotBeUsed (report, ExprClassName, GetSignatureForError (), loc);
 357                         }
 358                 }
 359
 360                 public void Error_TypeArgumentsCannotBeUsed (Report report, string exprType, string name, Location loc)
 361                 {
 362                         report.Error (307, loc, "The {0} `{1}' cannot be used with type arguments",
 363                                 exprType, name);
 364                 }
 365
 366                 protected virtual void Error_TypeDoesNotContainDefinition (ResolveContext ec, TypeSpec type, string name)
 367                 {
 368                         Error_TypeDoesNotContainDefinition (ec, loc, type, name);
 369                 }
 370
 371                 public static void Error_TypeDoesNotContainDefinition (ResolveContext ec, Location loc, TypeSpec type, string name)
 372                 {
 373                         ec.Report.SymbolRelatedToPreviousError (type);
 374                         ec.Report.Error (117, loc, "`{0}' does not contain a definition for `{1}'",
 375                                 TypeManager.CSharpName (type), name);
 376                 }
 377
 378                 protected static void Error_ValueAssignment (ResolveContext ec, Location loc)
 379                 {
 380                         ec.Report.Error (131, loc, "The left-hand side of an assignment must be a variable, a property or an indexer");
 381                 }
 382
 383                 public ResolveFlags ExprClassToResolveFlags {
 384                         get {
 385                                 switch (eclass) {
 386                                 case ExprClass.Type:
 387                                 case ExprClass.Namespace:
 388                                         return ResolveFlags.Type;
 389
 390                                 case ExprClass.MethodGroup:
 391                                         return ResolveFlags.MethodGroup;
 392
 393                                 case ExprClass.TypeParameter:
 394                                         return ResolveFlags.TypeParameter;
 395
 396                                 case ExprClass.Value:
 397                                 case ExprClass.Variable:
 398                                 case ExprClass.PropertyAccess:
 399                                 case ExprClass.EventAccess:
 400                                 case ExprClass.IndexerAccess:
 401                                         return ResolveFlags.VariableOrValue;
 402
 403                                 default:
 404                                         throw new InternalErrorException (loc.ToString () + " " +  GetType () + " ExprClass is Invalid after resolve");
 405                                 }
 406                         }
 407                 }
 408
 409                 /// <summary>
 410                 ///   Resolves an expression and performs semantic analysis on it.
 411                 /// </summary>
 412                 ///
 413                 /// <remarks>
 414                 ///   Currently Resolve wraps DoResolve to perform sanity
 415                 ///   checking and assertion checking on what we expect from Resolve.
 416                 /// </remarks>
 417                 public Expression Resolve (ResolveContext ec, ResolveFlags flags)
 418                 {
 419                         if (eclass != ExprClass.Unresolved)
 420                                 return this;
 421
 422                         Expression e;
 423                         try {
 424                                 e = DoResolve (ec);
 425
 426                                 if (e == null)
 427                                         return null;
 428
 429                                 if ((flags & e.ExprClassToResolveFlags) == 0) {
 430                                         e.Error_UnexpectedKind (ec, flags, loc);
 431                                         return null;
 432                                 }
 433
 434                                 if (e.type == null)
 435                                         throw new InternalErrorException ("Expression `{0}' didn't set its type in DoResolve", e.GetType ());
 436
 437                                 return e;
 438                         } catch (Exception ex) {
 439                                 if (loc.IsNull || Report.DebugFlags > 0 || ex is CompletionResult || ec.Report.IsDisabled)
 440                                         throw;
 441
 442                                 ec.Report.Error (584, loc, "Internal compiler error: {0}", ex.Message);
 443                                 return EmptyExpression.Null;
 444                         }
 445                 }
 446
 447                 /// <summary>
 448                 ///   Resolves an expression and performs semantic analysis on it.
 449                 /// </summary>
 450                 public Expression Resolve (ResolveContext rc)
 451                 {
 452                         return Resolve (rc, ResolveFlags.VariableOrValue | ResolveFlags.MethodGroup);
 453                 }
 454
 455                 /// <summary>
 456                 ///   Resolves an expression for LValue assignment
 457                 /// </summary>
 458                 ///
 459                 /// <remarks>
 460                 ///   Currently ResolveLValue wraps DoResolveLValue to perform sanity
 461                 ///   checking and assertion checking on what we expect from Resolve
 462                 /// </remarks>
 463                 public Expression ResolveLValue (ResolveContext ec, Expression right_side)
 464                 {
 465                         int errors = ec.Report.Errors;
 466                         bool out_access = right_side == EmptyExpression.OutAccess.Instance;
 467
 468                         Expression e = DoResolveLValue (ec, right_side);
 469
 470                         if (e != null && out_access && !(e is IMemoryLocation)) {
 471                                 // FIXME: There's no problem with correctness, the 'Expr = null' handles that.
 472                                 //        Enabling this 'throw' will "only" result in deleting useless code elsewhere,
 473
 474                                 //throw new InternalErrorException ("ResolveLValue didn't return an IMemoryLocation: " +
 475                                 //                                e.GetType () + " " + e.GetSignatureForError ());
 476                                 e = null;
 477                         }
 478
 479                         if (e == null) {
 480                                 if (errors == ec.Report.Errors) {
 481                                         if (out_access)
 482                                                 ec.Report.Error (1510, loc, "A ref or out argument must be an assignable variable");
 483                                         else
 484                                                 Error_ValueAssignment (ec, loc);
 485                                 }
 486                                 return null;
 487                         }
 488
 489                         if (e.eclass == ExprClass.Unresolved)
 490                                 throw new Exception ("Expression " + e + " ExprClass is Invalid after resolve");
 491
 492                         if ((e.type == null) && !(e is GenericTypeExpr))
 493                                 throw new Exception ("Expression " + e + " did not set its type after Resolve");
 494
 495                         return e;
 496                 }
 497
 498                 public virtual void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
 499                 {
 500                         Attribute.Error_AttributeArgumentNotValid (rc, loc);
 501                 }
 502
 503                 /// <summary>
 504                 ///   Emits the code for the expression
 505                 /// </summary>
 506                 ///
 507                 /// <remarks>
 508                 ///   The Emit method is invoked to generate the code
 509                 ///   for the expression.
 510                 /// </remarks>
 511                 public abstract void Emit (EmitContext ec);
 512
 513
 514                 // Emit code to branch to @target if this expression is equivalent to @on_true.
 515                 // The default implementation is to emit the value, and then emit a brtrue or brfalse.
 516                 // Subclasses can provide more efficient implementations, but those MUST be equivalent,
 517                 // including the use of conditional branches.  Note also that a branch MUST be emitted
 518                 public virtual void EmitBranchable (EmitContext ec, Label target, bool on_true)
 519                 {
 520                         Emit (ec);
 521                         ec.Emit (on_true ? OpCodes.Brtrue : OpCodes.Brfalse, target);
 522                 }
 523
 524                 // Emit this expression for its side effects, not for its value.
 525                 // The default implementation is to emit the value, and then throw it away.
 526                 // Subclasses can provide more efficient implementations, but those MUST be equivalent
 527                 public virtual void EmitSideEffect (EmitContext ec)
 528                 {
 529                         Emit (ec);
 530                         ec.Emit (OpCodes.Pop);
 531                 }
 532
 533                 /// <summary>
 534                 ///   Protected constructor.  Only derivate types should
 535                 ///   be able to be created
 536                 /// </summary>
 537
 538                 protected Expression ()
 539                 {
 540                 }
 541
 542                 /// <summary>
 543                 ///   Returns a fully formed expression after a MemberLookup
 544                 /// </summary>
 545                 ///
 546                 static Expression ExprClassFromMemberInfo (MemberSpec spec, Location loc)
 547                 {
 548                         if (spec is EventSpec)
 549                                 return new EventExpr ((EventSpec) spec, loc);
 550                         if (spec is ConstSpec)
 551                                 return new ConstantExpr ((ConstSpec) spec, loc);
 552                         if (spec is FieldSpec)
 553                                 return new FieldExpr ((FieldSpec) spec, loc);
 554                         if (spec is PropertySpec)
 555                                 return new PropertyExpr ((PropertySpec) spec, loc);
 556                         if (spec is TypeSpec)
 557                                 return new TypeExpression (((TypeSpec) spec), loc);
 558
 559                         return null;
 560                 }
 561
 562                 protected static MethodSpec ConstructorLookup (ResolveContext rc, TypeSpec type, ref Arguments args, Location loc)
 563                 {
 564                         var ctors = MemberCache.FindMembers (type, ConstructorInfo.ConstructorName, true);
 565                         if (ctors == null) {
 566                                 rc.Report.SymbolRelatedToPreviousError (type);
 567                                 if (type.IsStruct) {
 568                                         // Report meaningful error for struct as they always have default ctor in C# context
 569                                         OverloadResolver.Error_ConstructorMismatch (rc, type, args == null ? 0 : args.Count, loc);
 570                                 } else {
 571                                         rc.Report.Error (143, loc, "The class `{0}' has no constructors defined",
 572                                                 type.GetSignatureForError ());
 573                                 }
 574
 575                                 return null;
 576                         }
 577
 578                         var r = new OverloadResolver (ctors, OverloadResolver.Restrictions.NoBaseMembers, loc);
 579                         return r.ResolveMember<MethodSpec> (rc, ref args);
 580                 }
 581
 582                 //
 583                 // Lookup type `queried_type' for code in class `container_type' with a qualifier of
 584                 // `qualifier_type' or null to lookup members in the current class.
 585                 //
 586                 public static Expression MemberLookup (ResolveContext rc, TypeSpec currentType, TypeSpec queried_type, string name, int arity, bool invocableOnly, Location loc)
 587                 {
 588                         var members = MemberCache.FindMembers (queried_type, name, false);
 589                         if (members == null)
 590                                 return null;
 591
 592                         MemberSpec non_method = null;
 593                         MemberSpec ambig_non_method = null;
 594                         currentType = currentType ?? InternalType.FakeInternalType;
 595                         do {
 596                                 for (int i = 0; i < members.Count; ++i) {
 597                                         var member = members[i];
 598
 599                                         // HACK: for events because +=/-= can appear at same class only, should use OverrideToBase there
 600                                         if ((member.Modifiers & Modifiers.OVERRIDE) != 0 && member.Kind != MemberKind.Event)
 601                                                 continue;
 602
 603                                         if (arity > 0 && member.Arity != arity)
 604                                                 continue;
 605
 606                                         if (rc != null && !member.IsAccessible (currentType))
 607                                                 continue;
 608
 609                                         if (invocableOnly) {
 610                                                 if (member is MethodSpec)
 611                                                         return new MethodGroupExpr (members, queried_type, loc);
 612
 613                                                 if (!Invocation.IsMemberInvocable (member))
 614                                                         continue;
 615                                         }
 616
 617                                         if (non_method == null || member is MethodSpec) {
 618                                                 non_method = member;
 619                                         } else if (currentType != null) {
 620                                                 ambig_non_method = member;
 621                                         }
 622                                 }
 623
 624                                 if (non_method != null) {
 625                                         if (ambig_non_method != null && rc != null) {
 626                                                 rc.Report.SymbolRelatedToPreviousError (non_method);
 627                                                 rc.Report.SymbolRelatedToPreviousError (ambig_non_method);
 628                                                 rc.Report.Error (229, loc, "Ambiguity between `{0}' and `{1}'",
 629                                                         non_method.GetSignatureForError (), ambig_non_method.GetSignatureForError ());
 630                                         }
 631
 632                                         if (non_method is MethodSpec)
 633                                                 return new MethodGroupExpr (members, queried_type, loc);
 634
 635                                         return ExprClassFromMemberInfo (non_method, loc);
 636                                 }
 637
 638                                 if (members[0].DeclaringType.BaseType == null)
 639                                         members = null;
 640                                 else
 641                                         members = MemberCache.FindMembers (members[0].DeclaringType.BaseType, name, false);
 642
 643                         } while (members != null);
 644
 645                         return null;
 646                 }
 647
 648                 protected virtual void Error_NegativeArrayIndex (ResolveContext ec, Location loc)
 649                 {
 650                         throw new NotImplementedException ();
 651                 }
 652
 653                 protected void Error_PointerInsideExpressionTree (ResolveContext ec)
 654                 {
 655                         ec.Report.Error (1944, loc, "An expression tree cannot contain an unsafe pointer operation");
 656                 }
 657
 658                 /// <summary>
 659                 ///   Returns an expression that can be used to invoke operator true
 660                 ///   on the expression if it exists.
 661                 /// </summary>
 662                 protected static Expression GetOperatorTrue (ResolveContext ec, Expression e, Location loc)
 663                 {
 664                         return GetOperatorTrueOrFalse (ec, e, true, loc);
 665                 }
 666
 667                 /// <summary>
 668                 ///   Returns an expression that can be used to invoke operator false
 669                 ///   on the expression if it exists.
 670                 /// </summary>
 671                 static public Expression GetOperatorFalse (ResolveContext ec, Expression e, Location loc)
 672                 {
 673                         return GetOperatorTrueOrFalse (ec, e, false, loc);
 674                 }
 675
 676                 static Expression GetOperatorTrueOrFalse (ResolveContext ec, Expression e, bool is_true, Location loc)
 677                 {
 678                         var op = is_true ? Operator.OpType.True : Operator.OpType.False;
 679                         var methods = MemberCache.GetUserOperator (e.type, op, false);
 680                         if (methods == null)
 681                                 return null;
 682
 683                         Arguments arguments = new Arguments (1);
 684                         arguments.Add (new Argument (e));
 685
 686                         var res = new OverloadResolver (methods, OverloadResolver.Restrictions.NoBaseMembers, loc);
 687                         var oper = res.ResolveOperator (ec, ref arguments);
 688
 689                         if (oper == null)
 690                                 return null;
 691
 692                         return new UserOperatorCall (oper, arguments, null, loc);
 693                 }
 694
 695                 public virtual string ExprClassName
 696                 {
 697                         get {
 698                                 switch (eclass){
 699                                 case ExprClass.Unresolved:
 700                                         return "Unresolved";
 701                                 case ExprClass.Value:
 702                                         return "value";
 703                                 case ExprClass.Variable:
 704                                         return "variable";
 705                                 case ExprClass.Namespace:
 706                                         return "namespace";
 707                                 case ExprClass.Type:
 708                                         return "type";
 709                                 case ExprClass.MethodGroup:
 710                                         return "method group";
 711                                 case ExprClass.PropertyAccess:
 712                                         return "property access";
 713                                 case ExprClass.EventAccess:
 714                                         return "event access";
 715                                 case ExprClass.IndexerAccess:
 716                                         return "indexer access";
 717                                 case ExprClass.Nothing:
 718                                         return "null";
 719                                 case ExprClass.TypeParameter:
 720                                         return "type parameter";
 721                                 }
 722                                 throw new Exception ("Should not happen");
 723                         }
 724                 }
 725
 726                 /// <summary>
 727                 ///   Reports that we were expecting `expr' to be of class `expected'
 728                 /// </summary>
 729                 public void Error_UnexpectedKind (Report r, MemberCore mc, string expected, Location loc)
 730                 {
 731                         Error_UnexpectedKind (r, mc, expected, ExprClassName, loc);
 732                 }
 733
 734                 public void Error_UnexpectedKind (Report r, MemberCore mc, string expected, string was, Location loc)
 735                 {
 736                         string name;
 737                         if (mc != null)
 738                                 name = mc.GetSignatureForError ();
 739                         else
 740                                 name = GetSignatureForError ();
 741
 742                         r.Error (118, loc, "`{0}' is a `{1}' but a `{2}' was expected",
 743                               name, was, expected);
 744                 }
 745
 746                 public void Error_UnexpectedKind (ResolveContext ec, ResolveFlags flags, Location loc)
 747                 {
 748                         string [] valid = new string [4];
 749                         int count = 0;
 750
 751                         if ((flags & ResolveFlags.VariableOrValue) != 0) {
 752                                 valid [count++] = "variable";
 753                                 valid [count++] = "value";
 754                         }
 755
 756                         if ((flags & ResolveFlags.Type) != 0)
 757                                 valid [count++] = "type";
 758
 759                         if ((flags & ResolveFlags.MethodGroup) != 0)
 760                                 valid [count++] = "method group";
 761
 762                         if (count == 0)
 763                                 valid [count++] = "unknown";
 764
 765                         StringBuilder sb = new StringBuilder (valid [0]);
 766                         for (int i = 1; i < count - 1; i++) {
 767                                 sb.Append ("', `");
 768                                 sb.Append (valid [i]);
 769                         }
 770                         if (count > 1) {
 771                                 sb.Append ("' or `");
 772                                 sb.Append (valid [count - 1]);
 773                         }
 774
 775                         ec.Report.Error (119, loc,
 776                                 "Expression denotes a `{0}', where a `{1}' was expected", ExprClassName, sb.ToString ());
 777                 }
 778
 779                 public static void UnsafeError (ResolveContext ec, Location loc)
 780                 {
 781                         UnsafeError (ec.Report, loc);
 782                 }
 783
 784                 public static void UnsafeError (Report Report, Location loc)
 785                 {
 786                         Report.Error (214, loc, "Pointers and fixed size buffers may only be used in an unsafe context");
 787                 }
 788
 789
 790                 //
 791                 // Returns the size of type `t' if known, otherwise, 0
 792                 //
 793                 public static int GetTypeSize (TypeSpec t)
 794                 {
 795                         if (t == TypeManager.int32_type ||
 796                             t == TypeManager.uint32_type ||
 797                             t == TypeManager.float_type)
 798                                 return 4;
 799                         else if (t == TypeManager.int64_type ||
 800                                  t == TypeManager.uint64_type ||
 801                                  t == TypeManager.double_type)
 802                                 return 8;
 803                         else if (t == TypeManager.byte_type ||
 804                                  t == TypeManager.sbyte_type ||
 805                                  t == TypeManager.bool_type)
 806                                 return 1;
 807                         else if (t == TypeManager.short_type ||
 808                                  t == TypeManager.char_type ||
 809                                  t == TypeManager.ushort_type)
 810                                 return 2;
 811                         else if (t == TypeManager.decimal_type)
 812                                 return 16;
 813                         else
 814                                 return 0;
 815                 }
 816
 817                 protected void Error_CannotCallAbstractBase (ResolveContext ec, string name)
 818                 {
 819                         ec.Report.Error (205, loc, "Cannot call an abstract base member `{0}'", name);
 820                 }
 821
 822                 protected void Error_CannotModifyIntermediateExpressionValue (ResolveContext ec)
 823                 {
 824                         ec.Report.SymbolRelatedToPreviousError (type);
 825                         if (ec.CurrentInitializerVariable != null) {
 826                                 ec.Report.Error (1918, loc, "Members of value type `{0}' cannot be assigned using a property `{1}' object initializer",
 827                                         TypeManager.CSharpName (type), GetSignatureForError ());
 828                         } else {
 829                                 ec.Report.Error (1612, loc, "Cannot modify a value type return value of `{0}'. Consider storing the value in a temporary variable",
 830                                         GetSignatureForError ());
 831                         }
 832                 }
 833
 834                 //
 835                 // Converts `source' to an int, uint, long or ulong.
 836                 //
 837                 protected Expression ConvertExpressionToArrayIndex (ResolveContext ec, Expression source)
 838                 {
 839                         if (source.type == InternalType.Dynamic) {
 840                                 Arguments args = new Arguments (1);
 841                                 args.Add (new Argument (source));
 842                                 return new DynamicConversion (TypeManager.int32_type, CSharpBinderFlags.ConvertArrayIndex, args, loc).Resolve (ec);
 843                         }
 844
 845                         Expression converted;
 846
 847                         using (ec.Set (ResolveContext.Options.CheckedScope)) {
 848                                 converted = Convert.ImplicitConversion (ec, source, TypeManager.int32_type, source.loc);
 849                                 if (converted == null)
 850                                         converted = Convert.ImplicitConversion (ec, source, TypeManager.uint32_type, source.loc);
 851                                 if (converted == null)
 852                                         converted = Convert.ImplicitConversion (ec, source, TypeManager.int64_type, source.loc);
 853                                 if (converted == null)
 854                                         converted = Convert.ImplicitConversion (ec, source, TypeManager.uint64_type, source.loc);
 855
 856                                 if (converted == null) {
 857                                         source.Error_ValueCannotBeConverted (ec, source.loc, TypeManager.int32_type, false);
 858                                         return null;
 859                                 }
 860                         }
 861
 862                         //
 863                         // Only positive constants are allowed at compile time
 864                         //
 865                         Constant c = converted as Constant;
 866                         if (c != null && c.IsNegative)
 867                                 Error_NegativeArrayIndex (ec, source.loc);
 868
 869                         // No conversion needed to array index
 870                         if (converted.Type == TypeManager.int32_type)
 871                                 return converted;
 872
 873                         return new ArrayIndexCast (converted).Resolve (ec);
 874                 }
 875
 876                 //
 877                 // Derived classes implement this method by cloning the fields that
 878                 // could become altered during the Resolve stage
 879                 //
 880                 // Only expressions that are created for the parser need to implement
 881                 // this.
 882                 //
 883                 protected virtual void CloneTo (CloneContext clonectx, Expression target)
 884                 {
 885                         throw new NotImplementedException (
 886                                 String.Format (
 887                                         "CloneTo not implemented for expression {0}", this.GetType ()));
 888                 }
 889
 890                 //
 891                 // Clones an expression created by the parser.
 892                 //
 893                 // We only support expressions created by the parser so far, not
 894                 // expressions that have been resolved (many more classes would need
 895                 // to implement CloneTo).
 896                 //
 897                 // This infrastructure is here merely for Lambda expressions which
 898                 // compile the same code using different type values for the same
 899                 // arguments to find the correct overload
 900                 //
 901                 public Expression Clone (CloneContext clonectx)
 902                 {
 903                         Expression cloned = (Expression) MemberwiseClone ();
 904                         CloneTo (clonectx, cloned);
 905
 906                         return cloned;
 907                 }
 908
 909                 //
 910                 // Implementation of expression to expression tree conversion
 911                 //
 912                 public abstract Expression CreateExpressionTree (ResolveContext ec);
 913
 914                 protected Expression CreateExpressionFactoryCall (ResolveContext ec, string name, Arguments args)
 915                 {
 916                         return CreateExpressionFactoryCall (ec, name, null, args, loc);
 917                 }
 918
 919                 protected Expression CreateExpressionFactoryCall (ResolveContext ec, string name, TypeArguments typeArguments, Arguments args)
 920                 {
 921                         return CreateExpressionFactoryCall (ec, name, typeArguments, args, loc);
 922                 }
 923
 924                 public static Expression CreateExpressionFactoryCall (ResolveContext ec, string name, TypeArguments typeArguments, Arguments args, Location loc)
 925                 {
 926                         return new Invocation (new MemberAccess (CreateExpressionTypeExpression (ec, loc), name, typeArguments, loc), args);
 927                 }
 928
 929                 protected static TypeExpr CreateExpressionTypeExpression (ResolveContext ec, Location loc)
 930                 {
 931                         TypeExpr texpr = TypeManager.expression_type_expr;
 932                         if (texpr == null) {
 933                                 TypeSpec t = TypeManager.CoreLookupType (ec.Compiler, "System.Linq.Expressions", "Expression", MemberKind.Class, true);
 934                                 if (t == null)
 935                                         return null;
 936
 937                                 TypeManager.expression_type_expr = texpr = new TypeExpression (t, Location.Null);
 938                         }
 939
 940                         return texpr;
 941                 }
 942
 943                 //
 944                 // Implemented by all expressions which support conversion from
 945                 // compiler expression to invokable runtime expression. Used by
 946                 // dynamic C# binder.
 947                 //
 948                 public virtual SLE.Expression MakeExpression (BuilderContext ctx)
 949                 {
 950                         throw new NotImplementedException ("MakeExpression for " + GetType ());
 951                 }
 952         }
 953
 954         /// <summary>
 955         ///   This is just a base class for expressions that can
 956         ///   appear on statements (invocations, object creation,
 957         ///   assignments, post/pre increment and decrement).  The idea
 958         ///   being that they would support an extra Emition interface that
 959         ///   does not leave a result on the stack.
 960         /// </summary>
 961         public abstract class ExpressionStatement : Expression {
 962
 963                 public ExpressionStatement ResolveStatement (BlockContext ec)
 964                 {
 965                         Expression e = Resolve (ec);
 966                         if (e == null)
 967                                 return null;
 968
 969                         ExpressionStatement es = e as ExpressionStatement;
 970                         if (es == null)
 971                                 Error_InvalidExpressionStatement (ec);
 972
 973                         return es;
 974                 }
 975
 976                 /// <summary>
 977                 ///   Requests the expression to be emitted in a `statement'
 978                 ///   context.  This means that no new value is left on the
 979                 ///   stack after invoking this method (constrasted with
 980                 ///   Emit that will always leave a value on the stack).
 981                 /// </summary>
 982                 public abstract void EmitStatement (EmitContext ec);
 983
 984                 public override void EmitSideEffect (EmitContext ec)
 985                 {
 986                         EmitStatement (ec);
 987                 }
 988         }
 989
 990         /// <summary>
 991         ///   This kind of cast is used to encapsulate the child
 992         ///   whose type is child.Type into an expression that is
 993         ///   reported to return "return_type".  This is used to encapsulate
 994         ///   expressions which have compatible types, but need to be dealt
 995         ///   at higher levels with.
 996         ///
 997         ///   For example, a "byte" expression could be encapsulated in one
 998         ///   of these as an "unsigned int".  The type for the expression
 999         ///   would be "unsigned int".
1000         ///
1001         /// </summary>
1002         public abstract class TypeCast : Expression
1003         {
1004                 protected readonly Expression child;
1005
1006                 protected TypeCast (Expression child, TypeSpec return_type)
1007                 {
1008                         eclass = child.eclass;
1009                         loc = child.Location;
1010                         type = return_type;
1011                         this.child = child;
1012                 }
1013
1014                 public Expression Child {
1015                         get {
1016                                 return child;
1017                         }
1018                 }
1019
1020                 public override Expression CreateExpressionTree (ResolveContext ec)
1021                 {
1022                         Arguments args = new Arguments (2);
1023                         args.Add (new Argument (child.CreateExpressionTree (ec)));
1024                         args.Add (new Argument (new TypeOf (new TypeExpression (type, loc), loc)));
1025
1026                         if (type.IsPointer || child.Type.IsPointer)
1027                                 Error_PointerInsideExpressionTree (ec);
1028
1029                         return CreateExpressionFactoryCall (ec, ec.HasSet (ResolveContext.Options.CheckedScope) ? "ConvertChecked" : "Convert", args);
1030                 }
1031
1032                 protected override Expression DoResolve (ResolveContext ec)
1033                 {
1034                         // This should never be invoked, we are born in fully
1035                         // initialized state.
1036
1037                         return this;
1038                 }
1039
1040                 public override void Emit (EmitContext ec)
1041                 {
1042                         child.Emit (ec);
1043                 }
1044
1045                 public override SLE.Expression MakeExpression (BuilderContext ctx)
1046                 {
1047                         return ctx.HasSet (BuilderContext.Options.CheckedScope) ?
1048                                 SLE.Expression.ConvertChecked (child.MakeExpression (ctx), type.GetMetaInfo ()) :
1049                                 SLE.Expression.Convert (child.MakeExpression (ctx), type.GetMetaInfo ());
1050                 }
1051
1052                 protected override void CloneTo (CloneContext clonectx, Expression t)
1053                 {
1054                         // Nothing to clone
1055                 }
1056
1057                 public override bool IsNull {
1058                         get { return child.IsNull; }
1059                 }
1060         }
1061
1062         public class EmptyCast : TypeCast {
1063                 EmptyCast (Expression child, TypeSpec target_type)
1064                         : base (child, target_type)
1065                 {
1066                 }
1067
1068                 public static Expression Create (Expression child, TypeSpec type)
1069                 {
1070                         Constant c = child as Constant;
1071                         if (c != null)
1072                                 return new EmptyConstantCast (c, type);
1073
1074                         EmptyCast e = child as EmptyCast;
1075                         if (e != null)
1076                                 return new EmptyCast (e.child, type);
1077
1078                         return new EmptyCast (child, type);
1079                 }
1080
1081                 public override void EmitBranchable (EmitContext ec, Label label, bool on_true)
1082                 {
1083                         child.EmitBranchable (ec, label, on_true);
1084                 }
1085
1086                 public override void EmitSideEffect (EmitContext ec)
1087                 {
1088                         child.EmitSideEffect (ec);
1089                 }
1090         }
1091
1092         //
1093         // Used for predefined class library user casts (no obsolete check, etc.)
1094         //
1095         public class OperatorCast : TypeCast {
1096                 MethodSpec conversion_operator;
1097
1098                 public OperatorCast (Expression child, TypeSpec target_type)
1099                         : this (child, target_type, false)
1100                 {
1101                 }
1102
1103                 public OperatorCast (Expression child, TypeSpec target_type, bool find_explicit)
1104                         : base (child, target_type)
1105                 {
1106                         conversion_operator = GetConversionOperator (find_explicit);
1107                         if (conversion_operator == null)
1108                                 throw new InternalErrorException ("Outer conversion routine is out of sync");
1109                 }
1110
1111                 // Returns the implicit operator that converts from
1112                 // 'child.Type' to our target type (type)
1113                 MethodSpec GetConversionOperator (bool find_explicit)
1114                 {
1115                         var op = find_explicit ? Operator.OpType.Explicit : Operator.OpType.Implicit;
1116
1117                         var mi = MemberCache.GetUserOperator (child.Type, op, true);
1118                         if (mi == null){
1119                                 mi = MemberCache.GetUserOperator (type, op, true);
1120                         }
1121
1122                         foreach (MethodSpec oper in mi) {
1123                                 if (oper.ReturnType != type)
1124                                         continue;
1125
1126                                 if (oper.Parameters.Types [0] == child.Type)
1127                                         return oper;
1128                         }
1129
1130                         return null;
1131                 }
1132
1133                 public override void Emit (EmitContext ec)
1134                 {
1135                         child.Emit (ec);
1136                         ec.Emit (OpCodes.Call, conversion_operator);
1137                 }
1138         }
1139
1140         /// <summary>
1141         ///     This is a numeric cast to a Decimal
1142         /// </summary>
1143         public class CastToDecimal : OperatorCast {
1144                 public CastToDecimal (Expression child)
1145                         : this (child, false)
1146                 {
1147                 }
1148
1149                 public CastToDecimal (Expression child, bool find_explicit)
1150                         : base (child, TypeManager.decimal_type, find_explicit)
1151                 {
1152                 }
1153         }
1154
1155         /// <summary>
1156         ///     This is an explicit numeric cast from a Decimal
1157         /// </summary>
1158         public class CastFromDecimal : TypeCast
1159         {
1160                 static Dictionary<TypeSpec, MethodSpec> operators;
1161
1162                 public CastFromDecimal (Expression child, TypeSpec return_type)
1163                         : base (child, return_type)
1164                 {
1165                         if (child.Type != TypeManager.decimal_type)
1166                                 throw new ArgumentException ("Expected decimal child " + child.Type.GetSignatureForError ());
1167                 }
1168
1169                 // Returns the explicit operator that converts from an
1170                 // express of type System.Decimal to 'type'.
1171                 public Expression Resolve ()
1172                 {
1173                         if (operators == null) {
1174                                 var all_oper = MemberCache.GetUserOperator (TypeManager.decimal_type, Operator.OpType.Explicit, true);
1175
1176                                 operators = new Dictionary<TypeSpec, MethodSpec> ();
1177                                 foreach (MethodSpec oper in all_oper) {
1178                                         AParametersCollection pd = oper.Parameters;
1179                                         if (pd.Types [0] == TypeManager.decimal_type)
1180                                                 operators.Add (oper.ReturnType, oper);
1181                                 }
1182                         }
1183
1184                         return operators.ContainsKey (type) ? this : null;
1185                 }
1186
1187                 public override void Emit (EmitContext ec)
1188                 {
1189                         child.Emit (ec);
1190
1191                         ec.Emit (OpCodes.Call, operators [type]);
1192                 }
1193
1194                 public static void Reset ()
1195                 {
1196                         operators = null;
1197                 }
1198         }
1199
1200
1201         //
1202         // Constant specialization of EmptyCast.
1203         // We need to special case this since an empty cast of
1204         // a constant is still a constant.
1205         //
1206         public class EmptyConstantCast : Constant
1207         {
1208                 public Constant child;
1209
1210                 public EmptyConstantCast (Constant child, TypeSpec type)
1211                         : base (child.Location)
1212                 {
1213                         if (child == null)
1214                                 throw new ArgumentNullException ("child");
1215
1216                         this.child = child;
1217                         this.eclass = child.eclass;
1218                         this.type = type;
1219                 }
1220
1221                 public override string AsString ()
1222                 {
1223                         return child.AsString ();
1224                 }
1225
1226                 public override object GetValue ()
1227                 {
1228                         return child.GetValue ();
1229                 }
1230
1231                 public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
1232                 {
1233                         if (child.Type == target_type)
1234                                 return child;
1235
1236                         // FIXME: check that 'type' can be converted to 'target_type' first
1237                         return child.ConvertExplicitly (in_checked_context, target_type);
1238                 }
1239
1240                 public override Expression CreateExpressionTree (ResolveContext ec)
1241                 {
1242                         Arguments args = Arguments.CreateForExpressionTree (ec, null,
1243                                 child.CreateExpressionTree (ec),
1244                                 new TypeOf (new TypeExpression (type, loc), loc));
1245
1246                         if (type.IsPointer)
1247                                 Error_PointerInsideExpressionTree (ec);
1248
1249                         return CreateExpressionFactoryCall (ec, "Convert", args);
1250                 }
1251
1252                 public override bool IsDefaultValue {
1253                         get { return child.IsDefaultValue; }
1254                 }
1255
1256                 public override bool IsNegative {
1257                         get { return child.IsNegative; }
1258                 }
1259
1260                 public override bool IsNull {
1261                         get { return child.IsNull; }
1262                 }
1263
1264                 public override bool IsOneInteger {
1265                         get { return child.IsOneInteger; }
1266                 }
1267
1268                 public override bool IsZeroInteger {
1269                         get { return child.IsZeroInteger; }
1270                 }
1271
1272                 protected override Expression DoResolve (ResolveContext rc)
1273                 {
1274                         return this;
1275                 }
1276
1277                 public override void Emit (EmitContext ec)
1278                 {
1279                         child.Emit (ec);
1280                 }
1281
1282                 public override void EmitBranchable (EmitContext ec, Label label, bool on_true)
1283                 {
1284                         child.EmitBranchable (ec, label, on_true);
1285
1286                         // Only to make verifier happy
1287                         if (TypeManager.IsGenericParameter (type) && child.IsNull)
1288                                 ec.Emit (OpCodes.Unbox_Any, type);
1289                 }
1290
1291                 public override void EmitSideEffect (EmitContext ec)
1292                 {
1293                         child.EmitSideEffect (ec);
1294                 }
1295
1296                 public override Constant ConvertImplicitly (ResolveContext rc, TypeSpec target_type)
1297                 {
1298                         // FIXME: Do we need to check user conversions?
1299                         if (!Convert.ImplicitStandardConversionExists (this, target_type))
1300                                 return null;
1301                         return child.ConvertImplicitly (rc, target_type);
1302                 }
1303         }
1304
1305         /// <summary>
1306         ///  This class is used to wrap literals which belong inside Enums
1307         /// </summary>
1308         public class EnumConstant : Constant
1309         {
1310                 public Constant Child;
1311
1312                 public EnumConstant (Constant child, TypeSpec enum_type)
1313                         : base (child.Location)
1314                 {
1315                         this.Child = child;
1316                         this.type = enum_type;
1317                 }
1318
1319                 protected EnumConstant (Location loc)
1320                         : base (loc)
1321                 {
1322                 }
1323
1324                 protected override Expression DoResolve (ResolveContext rc)
1325                 {
1326                         Child = Child.Resolve (rc);
1327                         this.eclass = ExprClass.Value;
1328                         return this;
1329                 }
1330
1331                 public override void Emit (EmitContext ec)
1332                 {
1333                         Child.Emit (ec);
1334                 }
1335
1336                 public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
1337                 {
1338                         Child.EncodeAttributeValue (rc, enc, Child.Type);
1339                 }
1340
1341                 public override void EmitBranchable (EmitContext ec, Label label, bool on_true)
1342                 {
1343                         Child.EmitBranchable (ec, label, on_true);
1344                 }
1345
1346                 public override void EmitSideEffect (EmitContext ec)
1347                 {
1348                         Child.EmitSideEffect (ec);
1349                 }
1350
1351                 public override string GetSignatureForError()
1352                 {
1353                         return TypeManager.CSharpName (Type);
1354                 }
1355
1356                 public override object GetValue ()
1357                 {
1358                         return Child.GetValue ();
1359                 }
1360
1361                 public override object GetTypedValue ()
1362                 {
1363                         // FIXME: runtime is not ready to work with just emited enums
1364                         if (!RootContext.StdLib) {
1365                                 return Child.GetValue ();
1366                         }
1367
1368 #if MS_COMPATIBLE
1369                         // Small workaround for big problem
1370                         // System.Enum.ToObject cannot be called on dynamic types
1371                         // EnumBuilder has to be used, but we cannot use EnumBuilder
1372                         // because it does not properly support generics
1373                         //
1374                         // This works only sometimes
1375                         //
1376                         if (type.MemberDefinition is TypeContainer)
1377                                 return Child.GetValue ();
1378 #endif
1379
1380                         return System.Enum.ToObject (type.GetMetaInfo (), Child.GetValue ());
1381                 }
1382
1383                 public override string AsString ()
1384                 {
1385                         return Child.AsString ();
1386                 }
1387
1388                 public EnumConstant Increment()
1389                 {
1390                         return new EnumConstant (((IntegralConstant) Child).Increment (), type);
1391                 }
1392
1393                 public override bool IsDefaultValue {
1394                         get {
1395                                 return Child.IsDefaultValue;
1396                         }
1397                 }
1398
1399                 public override bool IsZeroInteger {
1400                         get { return Child.IsZeroInteger; }
1401                 }
1402
1403                 public override bool IsNegative {
1404                         get {
1405                                 return Child.IsNegative;
1406                         }
1407                 }
1408
1409                 public override Constant ConvertExplicitly(bool in_checked_context, TypeSpec target_type)
1410                 {
1411                         if (Child.Type == target_type)
1412                                 return Child;
1413
1414                         return Child.ConvertExplicitly (in_checked_context, target_type);
1415                 }
1416
1417                 public override Constant ConvertImplicitly (ResolveContext rc, TypeSpec type)
1418                 {
1419                         if (this.type == type) {
1420                                 return this;
1421                         }
1422
1423                         if (!Convert.ImplicitStandardConversionExists (this, type)){
1424                                 return null;
1425                         }
1426
1427                         return Child.ConvertImplicitly (rc, type);
1428                 }
1429         }
1430
1431         /// <summary>
1432         ///   This kind of cast is used to encapsulate Value Types in objects.
1433         ///
1434         ///   The effect of it is to box the value type emitted by the previous
1435         ///   operation.
1436         /// </summary>
1437         public class BoxedCast : TypeCast {
1438
1439                 public BoxedCast (Expression expr, TypeSpec target_type)
1440                         : base (expr, target_type)
1441                 {
1442                         eclass = ExprClass.Value;
1443                 }
1444
1445                 protected override Expression DoResolve (ResolveContext ec)
1446                 {
1447                         // This should never be invoked, we are born in fully
1448                         // initialized state.
1449
1450                         return this;
1451                 }
1452
1453                 public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
1454                 {
1455                         enc.Encode (child.Type);
1456                         child.EncodeAttributeValue (rc, enc, child.Type);
1457                 }
1458
1459                 public override void Emit (EmitContext ec)
1460                 {
1461                         base.Emit (ec);
1462
1463                         ec.Emit (OpCodes.Box, child.Type);
1464                 }
1465
1466                 public override void EmitSideEffect (EmitContext ec)
1467                 {
1468                         // boxing is side-effectful, since it involves runtime checks, except when boxing to Object or ValueType
1469                         // so, we need to emit the box+pop instructions in most cases
1470                         if (TypeManager.IsStruct (child.Type) &&
1471                             (type == TypeManager.object_type || type == TypeManager.value_type))
1472                                 child.EmitSideEffect (ec);
1473                         else
1474                                 base.EmitSideEffect (ec);
1475                 }
1476         }
1477
1478         public class UnboxCast : TypeCast {
1479                 public UnboxCast (Expression expr, TypeSpec return_type)
1480                         : base (expr, return_type)
1481                 {
1482                 }
1483
1484                 protected override Expression DoResolve (ResolveContext ec)
1485                 {
1486                         // This should never be invoked, we are born in fully
1487                         // initialized state.
1488
1489                         return this;
1490                 }
1491
1492                 public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
1493                 {
1494                         if (right_side == EmptyExpression.LValueMemberAccess || right_side == EmptyExpression.LValueMemberOutAccess)
1495                                 ec.Report.Error (445, loc, "Cannot modify the result of an unboxing conversion");
1496                         return base.DoResolveLValue (ec, right_side);
1497                 }
1498
1499                 public override void Emit (EmitContext ec)
1500                 {
1501                         base.Emit (ec);
1502
1503                         ec.Emit (OpCodes.Unbox_Any, type);
1504                 }
1505         }
1506
1507         /// <summary>
1508         ///   This is used to perform explicit numeric conversions.
1509         ///
1510         ///   Explicit numeric conversions might trigger exceptions in a checked
1511         ///   context, so they should generate the conv.ovf opcodes instead of
1512         ///   conv opcodes.
1513         /// </summary>
1514         public class ConvCast : TypeCast {
1515                 public enum Mode : byte {
1516                         I1_U1, I1_U2, I1_U4, I1_U8, I1_CH,
1517                         U1_I1, U1_CH,
1518                         I2_I1, I2_U1, I2_U2, I2_U4, I2_U8, I2_CH,
1519                         U2_I1, U2_U1, U2_I2, U2_CH,
1520                         I4_I1, I4_U1, I4_I2, I4_U2, I4_U4, I4_U8, I4_CH,
1521                         U4_I1, U4_U1, U4_I2, U4_U2, U4_I4, U4_CH,
1522                         I8_I1, I8_U1, I8_I2, I8_U2, I8_I4, I8_U4, I8_U8, I8_CH, I8_I,
1523                         U8_I1, U8_U1, U8_I2, U8_U2, U8_I4, U8_U4, U8_I8, U8_CH, U8_I,
1524                         CH_I1, CH_U1, CH_I2,
1525                         R4_I1, R4_U1, R4_I2, R4_U2, R4_I4, R4_U4, R4_I8, R4_U8, R4_CH,
1526                         R8_I1, R8_U1, R8_I2, R8_U2, R8_I4, R8_U4, R8_I8, R8_U8, R8_CH, R8_R4,
1527                         I_I8,
1528                 }
1529
1530                 Mode mode;
1531
1532                 public ConvCast (Expression child, TypeSpec return_type, Mode m)
1533                         : base (child, return_type)
1534                 {
1535                         mode = m;
1536                 }
1537
1538                 protected override Expression DoResolve (ResolveContext ec)
1539                 {
1540                         // This should never be invoked, we are born in fully
1541                         // initialized state.
1542
1543                         return this;
1544                 }
1545
1546                 public override string ToString ()
1547                 {
1548                         return String.Format ("ConvCast ({0}, {1})", mode, child);
1549                 }
1550
1551                 public override void Emit (EmitContext ec)
1552                 {
1553                         base.Emit (ec);
1554
1555                         if (ec.HasSet (EmitContext.Options.CheckedScope)) {
1556                                 switch (mode){
1557                                 case Mode.I1_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1558                                 case Mode.I1_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1559                                 case Mode.I1_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1560                                 case Mode.I1_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1561                                 case Mode.I1_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1562
1563                                 case Mode.U1_I1: ec.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1564                                 case Mode.U1_CH: /* nothing */ break;
1565
1566                                 case Mode.I2_I1: ec.Emit (OpCodes.Conv_Ovf_I1); break;
1567                                 case Mode.I2_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1568                                 case Mode.I2_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1569                                 case Mode.I2_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1570                                 case Mode.I2_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1571                                 case Mode.I2_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1572
1573                                 case Mode.U2_I1: ec.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1574                                 case Mode.U2_U1: ec.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1575                                 case Mode.U2_I2: ec.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1576                                 case Mode.U2_CH: /* nothing */ break;
1577
1578                                 case Mode.I4_I1: ec.Emit (OpCodes.Conv_Ovf_I1); break;
1579                                 case Mode.I4_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1580                                 case Mode.I4_I2: ec.Emit (OpCodes.Conv_Ovf_I2); break;
1581                                 case Mode.I4_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1582                                 case Mode.I4_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1583                                 case Mode.I4_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1584                                 case Mode.I4_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1585
1586                                 case Mode.U4_I1: ec.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1587                                 case Mode.U4_U1: ec.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1588                                 case Mode.U4_I2: ec.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1589                                 case Mode.U4_U2: ec.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1590                                 case Mode.U4_I4: ec.Emit (OpCodes.Conv_Ovf_I4_Un); break;
1591                                 case Mode.U4_CH: ec.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1592
1593                                 case Mode.I8_I1: ec.Emit (OpCodes.Conv_Ovf_I1); break;
1594                                 case Mode.I8_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1595                                 case Mode.I8_I2: ec.Emit (OpCodes.Conv_Ovf_I2); break;
1596                                 case Mode.I8_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1597                                 case Mode.I8_I4: ec.Emit (OpCodes.Conv_Ovf_I4); break;
1598                                 case Mode.I8_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1599                                 case Mode.I8_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1600                                 case Mode.I8_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1601                                 case Mode.I8_I: ec.Emit (OpCodes.Conv_Ovf_U); break;
1602
1603                                 case Mode.U8_I1: ec.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1604                                 case Mode.U8_U1: ec.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1605                                 case Mode.U8_I2: ec.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1606                                 case Mode.U8_U2: ec.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1607                                 case Mode.U8_I4: ec.Emit (OpCodes.Conv_Ovf_I4_Un); break;
1608                                 case Mode.U8_U4: ec.Emit (OpCodes.Conv_Ovf_U4_Un); break;
1609                                 case Mode.U8_I8: ec.Emit (OpCodes.Conv_Ovf_I8_Un); break;
1610                                 case Mode.U8_CH: ec.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1611                                 case Mode.U8_I: ec.Emit (OpCodes.Conv_Ovf_U_Un); break;
1612
1613                                 case Mode.CH_I1: ec.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1614                                 case Mode.CH_U1: ec.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1615                                 case Mode.CH_I2: ec.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1616
1617                                 case Mode.R4_I1: ec.Emit (OpCodes.Conv_Ovf_I1); break;
1618                                 case Mode.R4_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1619                                 case Mode.R4_I2: ec.Emit (OpCodes.Conv_Ovf_I2); break;
1620                                 case Mode.R4_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1621                                 case Mode.R4_I4: ec.Emit (OpCodes.Conv_Ovf_I4); break;
1622                                 case Mode.R4_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1623                                 case Mode.R4_I8: ec.Emit (OpCodes.Conv_Ovf_I8); break;
1624                                 case Mode.R4_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1625                                 case Mode.R4_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1626
1627                                 case Mode.R8_I1: ec.Emit (OpCodes.Conv_Ovf_I1); break;
1628                                 case Mode.R8_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1629                                 case Mode.R8_I2: ec.Emit (OpCodes.Conv_Ovf_I2); break;
1630                                 case Mode.R8_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1631                                 case Mode.R8_I4: ec.Emit (OpCodes.Conv_Ovf_I4); break;
1632                                 case Mode.R8_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1633                                 case Mode.R8_I8: ec.Emit (OpCodes.Conv_Ovf_I8); break;
1634                                 case Mode.R8_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1635                                 case Mode.R8_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1636                                 case Mode.R8_R4: ec.Emit (OpCodes.Conv_R4); break;
1637
1638                                 case Mode.I_I8: ec.Emit (OpCodes.Conv_Ovf_I8_Un); break;
1639                                 }
1640                         } else {
1641                                 switch (mode){
1642                                 case Mode.I1_U1: ec.Emit (OpCodes.Conv_U1); break;
1643                                 case Mode.I1_U2: ec.Emit (OpCodes.Conv_U2); break;
1644                                 case Mode.I1_U4: ec.Emit (OpCodes.Conv_U4); break;
1645                                 case Mode.I1_U8: ec.Emit (OpCodes.Conv_I8); break;
1646                                 case Mode.I1_CH: ec.Emit (OpCodes.Conv_U2); break;
1647
1648                                 case Mode.U1_I1: ec.Emit (OpCodes.Conv_I1); break;
1649                                 case Mode.U1_CH: ec.Emit (OpCodes.Conv_U2); break;
1650
1651                                 case Mode.I2_I1: ec.Emit (OpCodes.Conv_I1); break;
1652                                 case Mode.I2_U1: ec.Emit (OpCodes.Conv_U1); break;
1653                                 case Mode.I2_U2: ec.Emit (OpCodes.Conv_U2); break;
1654                                 case Mode.I2_U4: ec.Emit (OpCodes.Conv_U4); break;
1655                                 case Mode.I2_U8: ec.Emit (OpCodes.Conv_I8); break;
1656                                 case Mode.I2_CH: ec.Emit (OpCodes.Conv_U2); break;
1657
1658                                 case Mode.U2_I1: ec.Emit (OpCodes.Conv_I1); break;
1659                                 case Mode.U2_U1: ec.Emit (OpCodes.Conv_U1); break;
1660                                 case Mode.U2_I2: ec.Emit (OpCodes.Conv_I2); break;
1661                                 case Mode.U2_CH: /* nothing */ break;
1662
1663                                 case Mode.I4_I1: ec.Emit (OpCodes.Conv_I1); break;
1664                                 case Mode.I4_U1: ec.Emit (OpCodes.Conv_U1); break;
1665                                 case Mode.I4_I2: ec.Emit (OpCodes.Conv_I2); break;
1666                                 case Mode.I4_U4: /* nothing */ break;
1667                                 case Mode.I4_U2: ec.Emit (OpCodes.Conv_U2); break;
1668                                 case Mode.I4_U8: ec.Emit (OpCodes.Conv_I8); break;
1669                                 case Mode.I4_CH: ec.Emit (OpCodes.Conv_U2); break;
1670
1671                                 case Mode.U4_I1: ec.Emit (OpCodes.Conv_I1); break;
1672                                 case Mode.U4_U1: ec.Emit (OpCodes.Conv_U1); break;
1673                                 case Mode.U4_I2: ec.Emit (OpCodes.Conv_I2); break;
1674                                 case Mode.U4_U2: ec.Emit (OpCodes.Conv_U2); break;
1675                                 case Mode.U4_I4: /* nothing */ break;
1676                                 case Mode.U4_CH: ec.Emit (OpCodes.Conv_U2); break;
1677
1678                                 case Mode.I8_I1: ec.Emit (OpCodes.Conv_I1); break;
1679                                 case Mode.I8_U1: ec.Emit (OpCodes.Conv_U1); break;
1680                                 case Mode.I8_I2: ec.Emit (OpCodes.Conv_I2); break;
1681                                 case Mode.I8_U2: ec.Emit (OpCodes.Conv_U2); break;
1682                                 case Mode.I8_I4: ec.Emit (OpCodes.Conv_I4); break;
1683                                 case Mode.I8_U4: ec.Emit (OpCodes.Conv_U4); break;
1684                                 case Mode.I8_U8: /* nothing */ break;
1685                                 case Mode.I8_CH: ec.Emit (OpCodes.Conv_U2); break;
1686                                 case Mode.I8_I: ec.Emit (OpCodes.Conv_U); break;
1687
1688                                 case Mode.U8_I1: ec.Emit (OpCodes.Conv_I1); break;
1689                                 case Mode.U8_U1: ec.Emit (OpCodes.Conv_U1); break;
1690                                 case Mode.U8_I2: ec.Emit (OpCodes.Conv_I2); break;
1691                                 case Mode.U8_U2: ec.Emit (OpCodes.Conv_U2); break;
1692                                 case Mode.U8_I4: ec.Emit (OpCodes.Conv_I4); break;
1693                                 case Mode.U8_U4: ec.Emit (OpCodes.Conv_U4); break;
1694                                 case Mode.U8_I8: /* nothing */ break;
1695                                 case Mode.U8_CH: ec.Emit (OpCodes.Conv_U2); break;
1696                                 case Mode.U8_I: ec.Emit (OpCodes.Conv_U); break;
1697
1698                                 case Mode.CH_I1: ec.Emit (OpCodes.Conv_I1); break;
1699                                 case Mode.CH_U1: ec.Emit (OpCodes.Conv_U1); break;
1700                                 case Mode.CH_I2: ec.Emit (OpCodes.Conv_I2); break;
1701
1702                                 case Mode.R4_I1: ec.Emit (OpCodes.Conv_I1); break;
1703                                 case Mode.R4_U1: ec.Emit (OpCodes.Conv_U1); break;
1704                                 case Mode.R4_I2: ec.Emit (OpCodes.Conv_I2); break;
1705                                 case Mode.R4_U2: ec.Emit (OpCodes.Conv_U2); break;
1706                                 case Mode.R4_I4: ec.Emit (OpCodes.Conv_I4); break;
1707                                 case Mode.R4_U4: ec.Emit (OpCodes.Conv_U4); break;
1708                                 case Mode.R4_I8: ec.Emit (OpCodes.Conv_I8); break;
1709                                 case Mode.R4_U8: ec.Emit (OpCodes.Conv_U8); break;
1710                                 case Mode.R4_CH: ec.Emit (OpCodes.Conv_U2); break;
1711
1712                                 case Mode.R8_I1: ec.Emit (OpCodes.Conv_I1); break;
1713                                 case Mode.R8_U1: ec.Emit (OpCodes.Conv_U1); break;
1714                                 case Mode.R8_I2: ec.Emit (OpCodes.Conv_I2); break;
1715                                 case Mode.R8_U2: ec.Emit (OpCodes.Conv_U2); break;
1716                                 case Mode.R8_I4: ec.Emit (OpCodes.Conv_I4); break;
1717                                 case Mode.R8_U4: ec.Emit (OpCodes.Conv_U4); break;
1718                                 case Mode.R8_I8: ec.Emit (OpCodes.Conv_I8); break;
1719                                 case Mode.R8_U8: ec.Emit (OpCodes.Conv_U8); break;
1720                                 case Mode.R8_CH: ec.Emit (OpCodes.Conv_U2); break;
1721                                 case Mode.R8_R4: ec.Emit (OpCodes.Conv_R4); break;
1722
1723                                 case Mode.I_I8: ec.Emit (OpCodes.Conv_U8); break;
1724                                 }
1725                         }
1726                 }
1727         }
1728
1729         public class OpcodeCast : TypeCast {
1730                 readonly OpCode op;
1731
1732                 public OpcodeCast (Expression child, TypeSpec return_type, OpCode op)
1733                         : base (child, return_type)
1734                 {
1735                         this.op = op;
1736                 }
1737
1738                 protected override Expression DoResolve (ResolveContext ec)
1739                 {
1740                         // This should never be invoked, we are born in fully
1741                         // initialized state.
1742
1743                         return this;
1744                 }
1745
1746                 public override void Emit (EmitContext ec)
1747                 {
1748                         base.Emit (ec);
1749                         ec.Emit (op);
1750                 }
1751
1752                 public TypeSpec UnderlyingType {
1753                         get { return child.Type; }
1754                 }
1755         }
1756
1757         /// <summary>
1758         ///   This kind of cast is used to encapsulate a child and cast it
1759         ///   to the class requested
1760         /// </summary>
1761         public sealed class ClassCast : TypeCast {
1762                 readonly bool forced;
1763
1764                 public ClassCast (Expression child, TypeSpec return_type)
1765                         : base (child, return_type)
1766                 {
1767                 }
1768
1769                 public ClassCast (Expression child, TypeSpec return_type, bool forced)
1770                         : base (child, return_type)
1771                 {
1772                         this.forced = forced;
1773                 }
1774
1775                 public override void Emit (EmitContext ec)
1776                 {
1777                         base.Emit (ec);
1778
1779                         bool gen = TypeManager.IsGenericParameter (child.Type);
1780                         if (gen)
1781                                 ec.Emit (OpCodes.Box, child.Type);
1782
1783                         if (type.IsGenericParameter) {
1784                                 ec.Emit (OpCodes.Unbox_Any, type);
1785                                 return;
1786                         }
1787
1788                         if (gen && !forced)
1789                                 return;
1790
1791                         ec.Emit (OpCodes.Castclass, type);
1792                 }
1793         }
1794
1795         //
1796         // Created during resolving pahse when an expression is wrapped or constantified
1797         // and original expression can be used later (e.g. for expression trees)
1798         //
1799         public class ReducedExpression : Expression
1800         {
1801                 sealed class ReducedConstantExpression : EmptyConstantCast
1802                 {
1803                         readonly Expression orig_expr;
1804
1805                         public ReducedConstantExpression (Constant expr, Expression orig_expr)
1806                                 : base (expr, expr.Type)
1807                         {
1808                                 this.orig_expr = orig_expr;
1809                         }
1810
1811                         public override Constant ConvertImplicitly (ResolveContext rc, TypeSpec target_type)
1812                         {
1813                                 Constant c = base.ConvertImplicitly (rc, target_type);
1814                                 if (c != null)
1815                                         c = new ReducedConstantExpression (c, orig_expr);
1816
1817                                 return c;
1818                         }
1819
1820                         public override Expression CreateExpressionTree (ResolveContext ec)
1821                         {
1822                                 return orig_expr.CreateExpressionTree (ec);
1823                         }
1824
1825                         public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
1826                         {
1827                                 Constant c = base.ConvertExplicitly (in_checked_context, target_type);
1828                                 if (c != null)
1829                                         c = new ReducedConstantExpression (c, orig_expr);
1830                                 return c;
1831                         }
1832                 }
1833
1834                 sealed class ReducedExpressionStatement : ExpressionStatement
1835                 {
1836                         readonly Expression orig_expr;
1837                         readonly ExpressionStatement stm;
1838
1839                         public ReducedExpressionStatement (ExpressionStatement stm, Expression orig)
1840                         {
1841                                 this.orig_expr = orig;
1842                                 this.stm = stm;
1843                                 this.loc = orig.Location;
1844                         }
1845
1846                         public override Expression CreateExpressionTree (ResolveContext ec)
1847                         {
1848                                 return orig_expr.CreateExpressionTree (ec);
1849                         }
1850
1851                         protected override Expression DoResolve (ResolveContext ec)
1852                         {
1853                                 eclass = stm.eclass;
1854                                 type = stm.Type;
1855                                 return this;
1856                         }
1857
1858                         public override void Emit (EmitContext ec)
1859                         {
1860                                 stm.Emit (ec);
1861                         }
1862
1863                         public override void EmitStatement (EmitContext ec)
1864                         {
1865                                 stm.EmitStatement (ec);
1866                         }
1867                 }
1868
1869                 readonly Expression expr, orig_expr;
1870
1871                 private ReducedExpression (Expression expr, Expression orig_expr)
1872                 {
1873                         this.expr = expr;
1874                         this.eclass = expr.eclass;
1875                         this.type = expr.Type;
1876                         this.orig_expr = orig_expr;
1877                         this.loc = orig_expr.Location;
1878                 }
1879
1880                 //
1881                 // Creates fully resolved expression switcher
1882                 //
1883                 public static Constant Create (Constant expr, Expression original_expr)
1884                 {
1885                         if (expr.eclass == ExprClass.Unresolved)
1886                                 throw new ArgumentException ("Unresolved expression");
1887
1888                         return new ReducedConstantExpression (expr, original_expr);
1889                 }
1890
1891                 public static ExpressionStatement Create (ExpressionStatement s, Expression orig)
1892                 {
1893                         return new ReducedExpressionStatement (s, orig);
1894                 }
1895
1896                 //
1897                 // Creates unresolved reduce expression. The original expression has to be
1898                 // already resolved
1899                 //
1900                 public static Expression Create (Expression expr, Expression original_expr)
1901                 {
1902                         Constant c = expr as Constant;
1903                         if (c != null)
1904                                 return Create (c, original_expr);
1905
1906                         ExpressionStatement s = expr as ExpressionStatement;
1907                         if (s != null)
1908                                 return Create (s, original_expr);
1909
1910                         if (expr.eclass == ExprClass.Unresolved)
1911                                 throw new ArgumentException ("Unresolved expression");
1912
1913                         return new ReducedExpression (expr, original_expr);
1914                 }
1915
1916                 public override Expression CreateExpressionTree (ResolveContext ec)
1917                 {
1918                         return orig_expr.CreateExpressionTree (ec);
1919                 }
1920
1921                 protected override Expression DoResolve (ResolveContext ec)
1922                 {
1923                         return this;
1924                 }
1925
1926                 public override void Emit (EmitContext ec)
1927                 {
1928                         expr.Emit (ec);
1929                 }
1930
1931                 public override void EmitBranchable (EmitContext ec, Label target, bool on_true)
1932                 {
1933                         expr.EmitBranchable (ec, target, on_true);
1934                 }
1935
1936                 public override SLE.Expression MakeExpression (BuilderContext ctx)
1937                 {
1938                         return orig_expr.MakeExpression (ctx);
1939                 }
1940         }
1941
1942         //
1943         // Standard composite pattern
1944         //
1945         public abstract class CompositeExpression : Expression
1946         {
1947                 Expression expr;
1948
1949                 protected CompositeExpression (Expression expr)
1950                 {
1951                         this.expr = expr;
1952                         this.loc = expr.Location;
1953                 }
1954
1955                 public override Expression CreateExpressionTree (ResolveContext ec)
1956                 {
1957                         return expr.CreateExpressionTree (ec);
1958                 }
1959
1960                 public Expression Child {
1961                         get { return expr; }
1962                 }
1963
1964                 protected override Expression DoResolve (ResolveContext ec)
1965                 {
1966                         expr = expr.Resolve (ec);
1967                         if (expr != null) {
1968                                 type = expr.Type;
1969                                 eclass = expr.eclass;
1970                         }
1971
1972                         return this;
1973                 }
1974
1975                 public override void Emit (EmitContext ec)
1976                 {
1977                         expr.Emit (ec);
1978                 }
1979
1980                 public override bool IsNull {
1981                         get { return expr.IsNull; }
1982                 }
1983         }
1984
1985         //
1986         // Base of expressions used only to narrow resolve flow
1987         //
1988         public abstract class ShimExpression : Expression
1989         {
1990                 protected Expression expr;
1991
1992                 protected ShimExpression (Expression expr)
1993                 {
1994                         this.expr = expr;
1995                 }
1996
1997                 protected override void CloneTo (CloneContext clonectx, Expression t)
1998                 {
1999                         if (expr == null)
2000                                 return;
2001
2002                         ShimExpression target = (ShimExpression) t;
2003                         target.expr = expr.Clone (clonectx);
2004                 }
2005
2006                 public override Expression CreateExpressionTree (ResolveContext ec)
2007                 {
2008                         throw new NotSupportedException ("ET");
2009                 }
2010
2011                 public override void Emit (EmitContext ec)
2012                 {
2013                         throw new InternalErrorException ("Missing Resolve call");
2014                 }
2015
2016                 public Expression Expr {
2017                         get { return expr; }
2018                 }
2019         }
2020
2021         //
2022         // Unresolved type name expressions
2023         //
2024         public abstract class ATypeNameExpression : FullNamedExpression
2025         {
2026                 string name;
2027                 protected TypeArguments targs;
2028
2029                 protected ATypeNameExpression (string name, Location l)
2030                 {
2031                         this.name = name;
2032                         loc = l;
2033                 }
2034
2035                 protected ATypeNameExpression (string name, TypeArguments targs, Location l)
2036                 {
2037                         this.name = name;
2038                         this.targs = targs;
2039                         loc = l;
2040                 }
2041
2042                 protected ATypeNameExpression (string name, int arity, Location l)
2043                         : this (name, new UnboundTypeArguments (arity), l)
2044                 {
2045                 }
2046
2047                 #region Properties
2048
2049                 protected int Arity {
2050                         get {
2051                                 return targs == null ? 0 : targs.Count;
2052                         }
2053                 }
2054
2055                 public bool HasTypeArguments {
2056                         get {
2057                                 return targs != null && !targs.IsEmpty;
2058                         }
2059                 }
2060
2061                 public string Name {
2062                         get {
2063                                 return name;
2064                         }
2065                         set {
2066                                 name = value;
2067                         }
2068                 }
2069
2070                 public TypeArguments TypeArguments {
2071                         get {
2072                                 return targs;
2073                         }
2074                 }
2075
2076                 #endregion
2077
2078                 public override bool Equals (object obj)
2079                 {
2080                         ATypeNameExpression atne = obj as ATypeNameExpression;
2081                         return atne != null && atne.Name == Name &&
2082                                 (targs == null || targs.Equals (atne.targs));
2083                 }
2084
2085                 public override int GetHashCode ()
2086                 {
2087                         return Name.GetHashCode ();
2088                 }
2089
2090                 // TODO: Move it to MemberCore
2091                 public static string GetMemberType (MemberCore mc)
2092                 {
2093                         if (mc is Property)
2094                                 return "property";
2095                         if (mc is Indexer)
2096                                 return "indexer";
2097                         if (mc is FieldBase)
2098                                 return "field";
2099                         if (mc is MethodCore)
2100                                 return "method";
2101                         if (mc is EnumMember)
2102                                 return "enum";
2103                         if (mc is Event)
2104                                 return "event";
2105
2106                         return "type";
2107                 }
2108
2109                 public override string GetSignatureForError ()
2110                 {
2111                         if (targs != null) {
2112                                 return Name + "<" + targs.GetSignatureForError () + ">";
2113                         }
2114
2115                         return Name;
2116                 }
2117
2118                 public abstract Expression LookupNameExpression (ResolveContext rc, bool readMode, bool invocableOnly);
2119         }
2120
2121         /// <summary>
2122         ///   SimpleName expressions are formed of a single word and only happen at the beginning
2123         ///   of a dotted-name.
2124         /// </summary>
2125         public class SimpleName : ATypeNameExpression
2126         {
2127                 public SimpleName (string name, Location l)
2128                         : base (name, l)
2129                 {
2130                 }
2131
2132                 public SimpleName (string name, TypeArguments args, Location l)
2133                         : base (name, args, l)
2134                 {
2135                 }
2136
2137                 public SimpleName (string name, int arity, Location l)
2138                         : base (name, arity, l)
2139                 {
2140                 }
2141
2142                 public SimpleName GetMethodGroup ()
2143                 {
2144                         return new SimpleName (Name, targs, loc);
2145                 }
2146
2147                 protected virtual void Error_TypeOrNamespaceNotFound (IMemberContext ec)
2148                 {
2149                         if (ec.CurrentType != null) {
2150                                 if (ec.CurrentMemberDefinition != null) {
2151                                         MemberCore mc = ec.CurrentMemberDefinition.Parent.GetDefinition (Name);
2152                                         if (mc != null) {
2153                                                 Error_UnexpectedKind (ec.Compiler.Report, mc, "type", GetMemberType (mc), loc);
2154                                                 return;
2155                                         }
2156                                 }
2157
2158                                 /*
2159                                                                 // TODO MemberCache: Implement
2160
2161                                                                 string ns = ec.CurrentType.Namespace;
2162                                                                 string fullname = (ns.Length > 0) ? ns + "." + Name : Name;
2163                                                                 foreach (Assembly a in GlobalRootNamespace.Instance.Assemblies) {
2164                                                                         var type = a.GetType (fullname);
2165                                                                         if (type != null) {
2166                                                                                 ec.Compiler.Report.SymbolRelatedToPreviousError (type);
2167                                                                                 Expression.ErrorIsInaccesible (loc, TypeManager.CSharpName (type), ec.Compiler.Report);
2168                                                                                 return;
2169                                                                         }
2170                                                                 }
2171
2172                                                                 if (ec.CurrentTypeDefinition != null) {
2173                                                                         TypeSpec t = ec.CurrentTypeDefinition.LookupAnyGeneric (Name);
2174                                                                         if (t != null) {
2175                                                                                 Namespace.Error_InvalidNumberOfTypeArguments (ec.Compiler.Report, t, loc);
2176                                                                                 return;
2177                                                                         }
2178                                                                 }
2179                                 */
2180                         }
2181
2182                         FullNamedExpression retval = ec.LookupNamespaceOrType (Name, -System.Math.Max (1, Arity), loc, true);
2183                         if (retval != null) {
2184                                 Error_TypeArgumentsCannotBeUsed (ec.Compiler.Report, loc, retval.Type, Arity);
2185 /*
2186                                 var te = retval as TypeExpr;
2187                                 if (HasTypeArguments && te != null && !te.Type.IsGeneric)
2188                                         retval.Error_TypeArgumentsCannotBeUsed (ec.Compiler.Report, loc);
2189                                 else
2190                                         Namespace.Error_InvalidNumberOfTypeArguments (ec.Compiler.Report, retval.Type, loc);
2191 */
2192                                 return;
2193                         }
2194
2195                         NamespaceEntry.Error_NamespaceNotFound (loc, Name, ec.Compiler.Report);
2196                 }
2197
2198                 protected override Expression DoResolve (ResolveContext ec)
2199                 {
2200                         return SimpleNameResolve (ec, null, false);
2201                 }
2202
2203                 public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
2204                 {
2205                         return SimpleNameResolve (ec, right_side, false);
2206                 }
2207
2208                 public override FullNamedExpression ResolveAsTypeStep (IMemberContext ec, bool silent)
2209                 {
2210                         int errors = ec.Compiler.Report.Errors;
2211                         FullNamedExpression fne = ec.LookupNamespaceOrType (Name, Arity, loc, /*ignore_cs0104=*/ false);
2212
2213                         if (fne != null) {
2214                                 if (fne.Type != null && Arity > 0) {
2215                                         if (HasTypeArguments) {
2216                                                 GenericTypeExpr ct = new GenericTypeExpr (fne.Type, targs, loc);
2217                                                 return ct.ResolveAsTypeStep (ec, false);
2218                                         }
2219
2220                                         return new GenericOpenTypeExpr (fne.Type, loc);
2221                                 }
2222
2223                                 //
2224                                 // dynamic namespace is ignored when dynamic is allowed (does not apply to types)
2225                                 //
2226                                 if (!(fne is Namespace))
2227                                         return fne;
2228                         }
2229
2230                         if (Arity == 0 && Name == "dynamic" && RootContext.Version > LanguageVersion.V_3) {
2231                                 if (!PredefinedAttributes.Get.Dynamic.IsDefined) {
2232                                         ec.Compiler.Report.Error (1980, Location,
2233                                                 "Dynamic keyword requires `{0}' to be defined. Are you missing System.Core.dll assembly reference?",
2234                                                 PredefinedAttributes.Get.Dynamic.GetSignatureForError ());
2235                                 }
2236
2237                                 return new DynamicTypeExpr (loc);
2238                         }
2239
2240                         if (fne != null)
2241                                 return fne;
2242
2243                         if (silent || errors != ec.Compiler.Report.Errors)
2244                                 return null;
2245
2246                         Error_TypeOrNamespaceNotFound (ec);
2247                         return null;
2248                 }
2249
2250                 public override Expression LookupNameExpression (ResolveContext rc, bool readMode, bool invocableOnly)
2251                 {
2252                         int lookup_arity = Arity;
2253                         bool errorMode = false;
2254                         Expression e;
2255                         Block current_block = rc.CurrentBlock;
2256
2257                         while (true) {
2258                                 //
2259                                 // Stage 1: binding to local variables or parameters
2260                                 //
2261                                 if (current_block != null && lookup_arity == 0) {
2262                                         LocalInfo vi = current_block.GetLocalInfo (Name);
2263                                         if (vi != null) {
2264                                                 // TODO: pass vi in to speed things up
2265                                                 e = new LocalVariableReference (rc.CurrentBlock, Name, loc);
2266                                         } else {
2267                                                 e = current_block.Toplevel.GetParameterReference (Name, loc);
2268                                         }
2269
2270                                         if (e != null) {
2271                                                 if (Arity > 0)
2272                                                         Error_TypeArgumentsCannotBeUsed (rc.Report, "variable", Name, loc);
2273
2274                                                 return e;
2275                                         }
2276
2277                                         if (!errorMode)
2278                                                 current_block.CheckInvariantMeaningInBlock (Name, this, loc);
2279
2280 /*
2281                                         //if (errorMode) {
2282                                                 IKnownVariable ikv = current_block.Explicit.GetKnownVariable (Name);
2283                                                 if (ikv != null) {
2284                                                         LocalInfo li = ikv as LocalInfo;
2285                                                         // Supress CS0219 warning
2286                                                         if (li != null)
2287                                                                 li.Used = true;
2288
2289                                                         Error_VariableIsUsedBeforeItIsDeclared (rc.Report, Name);
2290                                                         return null;
2291                                                 }
2292                                         //}
2293 */
2294                                 }
2295
2296                                 //
2297                                 // Stage 2: Lookup members if we are inside a type up to top level type for nested types
2298                                 //
2299                                 TypeSpec member_type = rc.CurrentType;
2300                                 TypeSpec current_type = member_type;
2301                                 for (; member_type != null; member_type = member_type.DeclaringType) {
2302                                         var me = MemberLookup (errorMode ? null : rc, current_type, member_type, Name, lookup_arity, invocableOnly, loc) as MemberExpr;
2303                                         if (me == null)
2304                                                 continue;
2305
2306                                         if (errorMode) {
2307                                                 if (me is MethodGroupExpr) {
2308                                                         // Leave it to overload resolution to report correct error
2309                                                 } else {
2310                                                         // TODO: rc.Report.SymbolRelatedToPreviousError ()
2311                                                         ErrorIsInaccesible (rc, me.GetSignatureForError (), loc);
2312                                                 }
2313                                         } else {
2314                                                 //
2315                                                 // MemberLookup does not check accessors availability, this is actually needed for properties only
2316                                                 //
2317                                                 var pe = me as PropertyExpr;
2318                                                 if (pe != null) {
2319
2320                                                         // Break as there is no other overload available anyway
2321                                                         if (readMode) {
2322                                                                 if (!pe.PropertyInfo.HasGet || !pe.PropertyInfo.Get.IsAccessible (current_type))
2323                                                                         break;
2324
2325                                                                 pe.Getter = pe.PropertyInfo.Get;
2326                                                         } else {
2327                                                                 if (!pe.PropertyInfo.HasSet || !pe.PropertyInfo.Set.IsAccessible (current_type))
2328                                                                         break;
2329
2330                                                                 pe.Setter = pe.PropertyInfo.Set;
2331                                                         }
2332                                                 }
2333                                         }
2334
2335                                         // TODO: It's used by EventExpr -> FieldExpr transformation only
2336                                         // TODO: Should go to MemberAccess
2337                                         me = me.ResolveMemberAccess (rc, null, null);
2338
2339                                         if (Arity > 0) {
2340                                                 targs.Resolve (rc);
2341                                                 me.SetTypeArguments (rc, targs);
2342                                         }
2343
2344                                         return me;
2345                                 }
2346
2347                                 //
2348                                 // Stage 3: Lookup nested types, namespaces and type parameters in the context
2349                                 //
2350                                 if (!invocableOnly) {
2351                                         e = ResolveAsTypeStep (rc, lookup_arity == 0 || !errorMode);
2352                                         if (e != null)
2353                                                 return e;
2354                                 }
2355
2356                                 if (errorMode) {
2357                                         rc.Report.Error (103, loc, "The name `{0}' does not exist in the current context", Name);
2358                                         return null;
2359                                 }
2360
2361                                 if (RootContext.EvalMode) {
2362                                         var fi = Evaluator.LookupField (Name);
2363                                         if (fi != null)
2364                                                 return new FieldExpr (fi.Item1, loc);
2365                                 }
2366
2367                                 lookup_arity = 0;
2368                                 invocableOnly = false;
2369                                 errorMode = true;
2370                         }
2371                 }
2372
2373                 Expression SimpleNameResolve (ResolveContext ec, Expression right_side, bool intermediate)
2374                 {
2375                         Expression e = LookupNameExpression (ec, right_side == null, false);
2376
2377                         if (e == null)
2378                                 return null;
2379
2380                         if (right_side != null)
2381                                 e = e.ResolveLValue (ec, right_side);
2382                         else
2383                                 e = e.Resolve (ec);
2384
2385                         //if (ec.CurrentBlock == null || ec.CurrentBlock.CheckInvariantMeaningInBlock (Name, e, Location))
2386                         return e;
2387                 }
2388         }
2389
2390         /// <summary>
2391         ///   Represents a namespace or a type.  The name of the class was inspired by
2392         ///   section 10.8.1 (Fully Qualified Names).
2393         /// </summary>
2394         public abstract class FullNamedExpression : Expression
2395         {
2396                 protected override void CloneTo (CloneContext clonectx, Expression target)
2397                 {
2398                         // Do nothing, most unresolved type expressions cannot be
2399                         // resolved to different type
2400                 }
2401
2402                 public override Expression CreateExpressionTree (ResolveContext ec)
2403                 {
2404                         throw new NotSupportedException ("ET");
2405                 }
2406
2407                 public override FullNamedExpression ResolveAsTypeStep (IMemberContext ec, bool silent)
2408                 {
2409                         return this;
2410                 }
2411
2412                 public override void Emit (EmitContext ec)
2413                 {
2414                         throw new InternalErrorException ("FullNamedExpression `{0}' found in resolved tree",
2415                                 GetSignatureForError ());
2416                 }
2417         }
2418
2419         /// <summary>
2420         ///   Expression that evaluates to a type
2421         /// </summary>
2422         public abstract class TypeExpr : FullNamedExpression {
2423                 public override FullNamedExpression ResolveAsTypeStep (IMemberContext ec, bool silent)
2424                 {
2425                         TypeExpr t = DoResolveAsTypeStep (ec);
2426                         if (t == null)
2427                                 return null;
2428
2429                         eclass = ExprClass.Type;
2430                         return t;
2431                 }
2432
2433                 protected override Expression DoResolve (ResolveContext ec)
2434                 {
2435                         return ResolveAsTypeTerminal (ec, false);
2436                 }
2437
2438                 public virtual bool CheckAccessLevel (IMemberContext mc)
2439                 {
2440                         DeclSpace c = mc.CurrentMemberDefinition as DeclSpace;
2441                         if (c == null)
2442                                 c = mc.CurrentMemberDefinition.Parent;
2443
2444                         return c.CheckAccessLevel (Type);
2445                 }
2446
2447                 protected abstract TypeExpr DoResolveAsTypeStep (IMemberContext ec);
2448
2449                 public override bool Equals (object obj)
2450                 {
2451                         TypeExpr tobj = obj as TypeExpr;
2452                         if (tobj == null)
2453                                 return false;
2454
2455                         return Type == tobj.Type;
2456                 }
2457
2458                 public override int GetHashCode ()
2459                 {
2460                         return Type.GetHashCode ();
2461                 }
2462         }
2463
2464         /// <summary>
2465         ///   Fully resolved Expression that already evaluated to a type
2466         /// </summary>
2467         public class TypeExpression : TypeExpr {
2468                 public TypeExpression (TypeSpec t, Location l)
2469                 {
2470                         Type = t;
2471                         eclass = ExprClass.Type;
2472                         loc = l;
2473                 }
2474
2475                 protected override TypeExpr DoResolveAsTypeStep (IMemberContext ec)
2476                 {
2477                         return this;
2478                 }
2479
2480                 public override TypeExpr ResolveAsTypeTerminal (IMemberContext ec, bool silent)
2481                 {
2482                         return this;
2483                 }
2484         }
2485
2486         /// <summary>
2487         ///   This class denotes an expression which evaluates to a member
2488         ///   of a struct or a class.
2489         /// </summary>
2490         public abstract class MemberExpr : Expression
2491         {
2492                 //
2493                 // An instance expression associated with this member, if it's a
2494                 // non-static member
2495                 //
2496                 public Expression InstanceExpression;
2497
2498                 /// <summary>
2499                 ///   The name of this member.
2500                 /// </summary>
2501                 public abstract string Name {
2502                         get;
2503                 }
2504
2505                 //
2506                 // When base.member is used
2507                 //
2508                 public bool IsBase {
2509                         get { return InstanceExpression is BaseThis; }
2510                 }
2511
2512                 /// <summary>
2513                 ///   Whether this is an instance member.
2514                 /// </summary>
2515                 public abstract bool IsInstance {
2516                         get;
2517                 }
2518
2519                 /// <summary>
2520                 ///   Whether this is a static member.
2521                 /// </summary>
2522                 public abstract bool IsStatic {
2523                         get;
2524                 }
2525
2526                 // TODO: Not needed
2527                 protected abstract TypeSpec DeclaringType {
2528                         get;
2529                 }
2530
2531                 //
2532                 // Converts best base candidate for virtual method starting from QueriedBaseType
2533                 //
2534                 protected MethodSpec CandidateToBaseOverride (ResolveContext rc, MethodSpec method)
2535                 {
2536                         //
2537                         // Only when base.member is used and method is virtual
2538                         //
2539                         if (!IsBase)
2540                                 return method;
2541
2542                         //
2543                         // Overload resulution works on virtual or non-virtual members only (no overrides). That
2544                         // means for base.member access we have to find the closest match after we found best candidate
2545                         //
2546                         if ((method.Modifiers & (Modifiers.ABSTRACT | Modifiers.VIRTUAL | Modifiers.STATIC)) != Modifiers.STATIC) {
2547                                 //
2548                                 // The method could already be what we are looking for
2549                                 //
2550                                 TypeSpec[] targs = null;
2551                                 if (method.DeclaringType != InstanceExpression.Type) {
2552                                         var base_override = MemberCache.FindMember (InstanceExpression.Type, new MemberFilter (method), BindingRestriction.InstanceOnly) as MethodSpec;
2553                                         if (base_override != null && base_override.DeclaringType != method.DeclaringType) {
2554                                                 if (base_override.IsGeneric)
2555                                                         targs = method.TypeArguments;
2556
2557                                                 method = base_override;
2558                                         }
2559                                 }
2560
2561                                 // TODO: For now we do it for any hoisted call even if it's needed for
2562                                 // hoisted stories only but that requires a new expression wrapper
2563                                 if (rc.CurrentAnonymousMethod != null) {
2564                                         if (targs == null && method.IsGeneric) {
2565                                                 targs = method.TypeArguments;
2566                                                 method = method.GetGenericMethodDefinition ();
2567                                         }
2568
2569                                         if (method.Parameters.HasArglist)
2570                                                 throw new NotImplementedException ("__arglist base call proxy");
2571
2572                                         method = rc.CurrentMemberDefinition.Parent.PartialContainer.CreateHoistedBaseCallProxy (rc, method);\r
2573 \r
2574                                         // Ideally this should apply to any proxy rewrite but in the case of unary mutators on\r
2575                                         // get/set member expressions second call would fail to proxy because left expression\r
2576                                         // would be of 'this' and not 'base'\r
2577                                         if (rc.CurrentType.IsStruct)\r
2578                                                 InstanceExpression = rc.GetThis (loc);\r
2579                                 }
2580
2581                                 if (targs != null)
2582                                         method = method.MakeGenericMethod (targs);
2583                         }
2584
2585                         //
2586                         // Only base will allow this invocation to happen.
2587                         //
2588                         if (method.IsAbstract) {
2589                                 Error_CannotCallAbstractBase (rc, method.GetSignatureForError ());
2590                         }
2591
2592                         return method;
2593                 }
2594
2595                 protected void CheckProtectedMemberAccess<T> (ResolveContext rc, T member) where T : MemberSpec
2596                 {
2597                         if (InstanceExpression == null)
2598                                 return;
2599
2600                         if ((member.Modifiers & Modifiers.AccessibilityMask) == Modifiers.PROTECTED && !(InstanceExpression is This)) {
2601                                 var ct = rc.CurrentType;
2602                                 var expr_type = InstanceExpression.Type;
2603                                 if (ct != expr_type && !TypeManager.IsSubclassOf (expr_type, ct)) {
2604                                         expr_type = expr_type.GetDefinition ();
2605                                         if (ct != expr_type && !IsSameOrBaseQualifier (ct, expr_type)) {
2606                                                 rc.Report.SymbolRelatedToPreviousError (member);
2607                                                 rc.Report.Error (1540, loc,
2608                                                         "Cannot access protected member `{0}' via a qualifier of type `{1}'. The qualifier must be of type `{2}' or derived from it",
2609                                                         member.GetSignatureForError (), expr_type.GetSignatureForError (), ct.GetSignatureForError ());
2610                                         }
2611                                 }
2612                         }
2613                 }
2614
2615                 static bool IsSameOrBaseQualifier (TypeSpec type, TypeSpec qtype)
2616                 {
2617                         do {
2618                                 type = type.GetDefinition ();
2619
2620                                 if (type == qtype || TypeManager.IsFamilyAccessible (qtype, type))
2621                                         return true;
2622
2623                                 type = type.DeclaringType;
2624                         } while (type != null);
2625
2626                         return false;
2627                 }
2628
2629                 protected void DoBestMemberChecks<T> (ResolveContext rc, T member) where T : MemberSpec, IInterfaceMemberSpec
2630                 {
2631                         if (InstanceExpression != null) {
2632                                 InstanceExpression = InstanceExpression.Resolve (rc);
2633                                 CheckProtectedMemberAccess (rc, member);
2634                         }
2635
2636                         if (member.MemberType.IsPointer && !rc.IsUnsafe) {
2637                                 UnsafeError (rc, loc);
2638                         }
2639
2640                         if (!rc.IsObsolete) {
2641                                 ObsoleteAttribute oa = member.GetAttributeObsolete ();
2642                                 if (oa != null)
2643                                         AttributeTester.Report_ObsoleteMessage (oa, member.GetSignatureForError (), loc, rc.Report);
2644                         }
2645
2646                         if (!(member is FieldSpec))
2647                                 member.MemberDefinition.SetIsUsed ();
2648                 }
2649
2650                 //
2651                 // Implements identicial simple name and type-name
2652                 //
2653                 public Expression ProbeIdenticalTypeName (ResolveContext rc, Expression left, SimpleName name)
2654                 {
2655                         var t = left.Type;
2656                         if (t.Kind == MemberKind.InternalCompilerType || t is ElementTypeSpec || t.Arity > 0)
2657                                 return left;
2658
2659                         // 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
2660                         // a constant, field, property, local variable, or parameter with the same type as the meaning of E as a type-name
2661
2662                         if (left is MemberExpr || left is VariableReference) {
2663                                 rc.Report.DisableReporting ();
2664                                 Expression identical_type = rc.LookupNamespaceOrType (name.Name, 0, loc, true) as TypeExpr;
2665                                 rc.Report.EnableReporting ();
2666                                 if (identical_type != null && identical_type.Type == left.Type)
2667                                         return identical_type;
2668                         }
2669
2670                         return left;
2671                 }
2672
2673                 public bool ResolveInstanceExpression (ResolveContext rc)
2674                 {
2675                         if (IsStatic) {
2676                                 if (InstanceExpression != null) {
2677                                         if (InstanceExpression is TypeExpr) {
2678                                                 ObsoleteAttribute oa = InstanceExpression.Type.GetAttributeObsolete ();
2679                                                 if (oa != null && !rc.IsObsolete) {
2680                                                         AttributeTester.Report_ObsoleteMessage (oa, InstanceExpression.GetSignatureForError (), loc, rc.Report);
2681                                                 }
2682                                         } else {
2683                                                 var runtime_expr = InstanceExpression as RuntimeValueExpression;
2684                                                 if (runtime_expr == null || !runtime_expr.IsSuggestionOnly) {
2685                                                         rc.Report.Error (176, loc,
2686                                                                 "Static member `{0}' cannot be accessed with an instance reference, qualify it with a type name instead",
2687                                                                 GetSignatureForError ());
2688                                                 }
2689                                         }
2690
2691                                         InstanceExpression = null;
2692                                 }
2693
2694                                 return false;
2695                         }
2696
2697                         if (InstanceExpression == null || InstanceExpression is TypeExpr) {
2698                                 if (InstanceExpression != null || !This.IsThisAvailable (rc, true)) {
2699                                         if (rc.HasSet (ResolveContext.Options.FieldInitializerScope))
2700                                                 rc.Report.Error (236, loc,
2701                                                         "A field initializer cannot reference the nonstatic field, method, or property `{0}'",
2702                                                         GetSignatureForError ());
2703                                         else
2704                                                 rc.Report.Error (120, loc,
2705                                                         "An object reference is required to access non-static member `{0}'",
2706                                                         GetSignatureForError ());
2707
2708                                         return false;
2709                                 }
2710
2711                                 if (!TypeManager.IsFamilyAccessible (rc.CurrentType, DeclaringType)) {
2712                                         rc.Report.Error (38, loc,
2713                                                 "Cannot access a nonstatic member of outer type `{0}' via nested type `{1}'",
2714                                                 DeclaringType.GetSignatureForError (), rc.CurrentType.GetSignatureForError ());
2715                                 }
2716
2717                                 InstanceExpression = rc.GetThis (loc);
2718                                 return false;
2719                         }
2720
2721                         var me = InstanceExpression as MemberExpr;
2722                         if (me != null) {
2723                                 me.ResolveInstanceExpression (rc);
2724
2725                                 var fe = me as FieldExpr;
2726                                 if (fe != null && fe.IsMarshalByRefAccess ()) {
2727                                         rc.Report.SymbolRelatedToPreviousError (me.DeclaringType);
2728                                         rc.Report.Warning (1690, 1, loc,
2729                                                 "Cannot call methods, properties, or indexers on `{0}' because it is a value type member of a marshal-by-reference class",
2730                                                 me.GetSignatureForError ());
2731                                 }
2732                         }
2733
2734                         return true;
2735                 }
2736
2737                 public virtual MemberExpr ResolveMemberAccess (ResolveContext ec, Expression left, SimpleName original)
2738                 {
2739                         if (left != null && left.IsNull && TypeManager.IsReferenceType (left.Type)) {
2740                                 ec.Report.Warning (1720, 1, left.Location,
2741                                         "Expression will always cause a `{0}'", "System.NullReferenceException");
2742                         }
2743
2744                         InstanceExpression = left;
2745                         return this;
2746                 }
2747
2748                 protected void EmitInstance (EmitContext ec, bool prepare_for_load)
2749                 {
2750                         if (TypeManager.IsValueType (InstanceExpression.Type)) {
2751                                 if (InstanceExpression is IMemoryLocation) {
2752                                         ((IMemoryLocation) InstanceExpression).AddressOf (ec, AddressOp.LoadStore);
2753                                 } else {
2754                                         LocalTemporary t = new LocalTemporary (InstanceExpression.Type);
2755                                         InstanceExpression.Emit (ec);
2756                                         t.Store (ec);
2757                                         t.AddressOf (ec, AddressOp.Store);
2758                                 }
2759                         } else
2760                                 InstanceExpression.Emit (ec);
2761
2762                         if (prepare_for_load)
2763                                 ec.Emit (OpCodes.Dup);
2764                 }
2765
2766                 public abstract void SetTypeArguments (ResolveContext ec, TypeArguments ta);
2767         }
2768
2769         ///
2770         /// Represents group of extension method candidates
2771         ///
2772         public class ExtensionMethodGroupExpr : MethodGroupExpr, OverloadResolver.IErrorHandler
2773         {
2774                 readonly NamespaceEntry namespace_entry;
2775                 public Expression ExtensionExpression;
2776
2777                 public ExtensionMethodGroupExpr (List<MethodSpec> list, NamespaceEntry n, TypeSpec extensionType, Location l)
2778                         : base (list.Cast<MemberSpec>().ToList (), extensionType, l)
2779                 {
2780                         this.namespace_entry = n;
2781                 }
2782
2783                 public override bool IsStatic {
2784                         get { return true; }
2785                 }
2786
2787                 public bool IsTopLevel {
2788                         get { return namespace_entry == null; }
2789                 }
2790
2791                 public override MethodGroupExpr OverloadResolve (ResolveContext ec, ref Arguments arguments, OverloadResolver.IErrorHandler ehandler, OverloadResolver.Restrictions restr)
2792                 {
2793                         if (arguments == null)
2794                                 arguments = new Arguments (1);
2795
2796                         arguments.Insert (0, new Argument (ExtensionExpression));
2797                         MethodGroupExpr mg = ResolveOverloadExtensions (ec, ref arguments, ehandler ?? this, namespace_entry, loc);
2798
2799                         // Store resolved argument and restore original arguments
2800                         if (mg == null) {
2801                                 arguments.RemoveAt (0); // Clean-up modified arguments for error reporting
2802                         } else {
2803                                 var me = ExtensionExpression as MemberExpr;
2804                                 if (me != null)
2805                                         me.ResolveInstanceExpression (ec);
2806                         }
2807
2808                         return mg;
2809                 }
2810
2811                 MethodGroupExpr ResolveOverloadExtensions (ResolveContext ec, ref Arguments arguments, OverloadResolver.IErrorHandler ehandler, NamespaceEntry ns, Location loc)
2812                 {
2813                         // Use normal resolve rules
2814                         MethodGroupExpr mg = base.OverloadResolve (ec, ref arguments, ehandler, ns != null ? OverloadResolver.Restrictions.ProbingOnly : OverloadResolver.Restrictions.None);
2815                         if (mg != null)
2816                                 return mg;
2817
2818                         if (ns == null)
2819                                 return null;
2820
2821                         // Search continues
2822                         int arity = type_arguments == null ? 0 : type_arguments.Count;
2823                         ExtensionMethodGroupExpr e = ns.LookupExtensionMethod (type, Name, arity, loc);
2824                         if (e == null)
2825                                 return base.OverloadResolve (ec, ref arguments, ehandler, OverloadResolver.Restrictions.None);
2826
2827                         e.ExtensionExpression = ExtensionExpression;
2828                         e.SetTypeArguments (ec, type_arguments);
2829                         return e.ResolveOverloadExtensions (ec, ref arguments, ehandler, e.namespace_entry, loc);
2830                 }
2831
2832                 #region IErrorHandler Members
2833
2834                 bool OverloadResolver.IErrorHandler.AmbiguousCandidates (ResolveContext rc, MemberSpec best, MemberSpec ambiguous)
2835                 {
2836                         return false;
2837                 }
2838
2839                 bool OverloadResolver.IErrorHandler.ArgumentMismatch (ResolveContext rc, MemberSpec best, Argument arg, int index)
2840                 {
2841                         rc.Report.SymbolRelatedToPreviousError (best);
2842                         rc.Report.Error (1928, loc,
2843                                 "Type `{0}' does not contain a member `{1}' and the best extension method overload `{2}' has some invalid arguments",
2844                                 queried_type.GetSignatureForError (), Name, best.GetSignatureForError ());
2845
2846                         if (index == 0) {
2847                                 rc.Report.Error (1929, loc,
2848                                         "Extension method instance type `{0}' cannot be converted to `{1}'",
2849                                         arg.Type.GetSignatureForError (), ((MethodSpec)best).Parameters.ExtensionMethodType.GetSignatureForError ());
2850                         }
2851
2852                         return true;
2853                 }
2854
2855                 bool OverloadResolver.IErrorHandler.NoArgumentMatch (ResolveContext rc, MemberSpec best)
2856                 {
2857                         return false;
2858                 }
2859
2860                 bool OverloadResolver.IErrorHandler.TypeInferenceFailed (ResolveContext rc, MemberSpec best)
2861                 {
2862                         return false;
2863                 }
2864
2865                 #endregion
2866         }
2867
2868         /// <summary>
2869         ///   MethodGroupExpr represents a group of method candidates which
2870         ///   can be resolved to the best method overload
2871         /// </summary>
2872         public class MethodGroupExpr : MemberExpr, OverloadResolver.IBaseMembersProvider
2873         {
2874                 protected IList<MemberSpec> Methods;
2875                 MethodSpec best_candidate;
2876                 protected TypeArguments type_arguments;
2877
2878                 SimpleName simple_name;
2879                 protected TypeSpec queried_type;
2880
2881                 public MethodGroupExpr (IList<MemberSpec> mi, TypeSpec type, Location loc)
2882                 {
2883                         Methods = mi;
2884                         this.loc = loc;
2885                         this.type = InternalType.MethodGroup;
2886
2887                         eclass = ExprClass.MethodGroup;
2888                         queried_type = type;
2889                 }
2890
2891                 public MethodGroupExpr (MethodSpec m, TypeSpec type, Location loc)
2892                         : this (new MemberSpec[] { m }, type, loc)
2893                 {
2894                 }
2895
2896                 #region Properties
2897
2898                 public MethodSpec BestCandidate {
2899                         get {
2900                                 return best_candidate;
2901                         }
2902                 }
2903
2904                 protected override TypeSpec DeclaringType {
2905                         get {
2906                                 return queried_type;
2907                         }
2908                 }
2909
2910                 public override bool IsInstance {
2911                         get {
2912                                 if (best_candidate != null)
2913                                         return !best_candidate.IsStatic;
2914
2915                                 return false;
2916                         }
2917                 }
2918
2919                 public override bool IsStatic {
2920                         get {
2921                                 if (best_candidate != null)
2922                                         return best_candidate.IsStatic;
2923
2924                                 return false;
2925                         }
2926                 }
2927
2928                 public override string Name {
2929                         get {
2930                                 if (best_candidate != null)
2931                                         return best_candidate.Name;
2932
2933                                 // TODO: throw ?
2934                                 return Methods.First ().Name;
2935                         }
2936                 }
2937
2938                 #endregion
2939
2940                 //
2941                 // When best candidate is already know this factory can be used
2942                 // to avoid expensive overload resolution to be called
2943                 //
2944                 // NOTE: InstanceExpression has to be set manually
2945                 //
2946                 public static MethodGroupExpr CreatePredefined (MethodSpec best, TypeSpec queriedType, Location loc)
2947                 {
2948                         return new MethodGroupExpr (best, queriedType, loc) {
2949                                 best_candidate = best
2950                         };
2951                 }
2952
2953                 public override string GetSignatureForError ()
2954                 {
2955                         if (best_candidate != null)
2956                                 return best_candidate.GetSignatureForError ();
2957
2958                         return Methods.First ().GetSignatureForError ();
2959                 }
2960
2961                 public override MemberExpr ResolveMemberAccess (ResolveContext ec, Expression left, SimpleName original)
2962                 {
2963                         simple_name = original;
2964
2965                         return base.ResolveMemberAccess (ec, left, original);
2966                 }
2967
2968                 public override Expression CreateExpressionTree (ResolveContext ec)
2969                 {
2970                         if (best_candidate == null) {
2971                                 ec.Report.Error (1953, loc, "An expression tree cannot contain an expression with method group");
2972                                 return null;
2973                         }
2974
2975                         if (best_candidate.IsConditionallyExcluded (loc))
2976                                 ec.Report.Error (765, loc,
2977                                         "Partial methods with only a defining declaration or removed conditional methods cannot be used in an expression tree");
2978
2979                         return new TypeOfMethod (best_candidate, loc);
2980                 }
2981
2982                 protected override Expression DoResolve (ResolveContext ec)
2983                 {
2984                         this.eclass = ExprClass.MethodGroup;
2985
2986                         if (InstanceExpression != null) {
2987                                 InstanceExpression = InstanceExpression.Resolve (ec);
2988                                 if (InstanceExpression == null)
2989                                         return null;
2990                         }
2991
2992                         return this;
2993                 }
2994
2995                 public override void Emit (EmitContext ec)
2996                 {
2997                         throw new NotSupportedException ();
2998                 }
2999
3000                 public void EmitCall (EmitContext ec, Arguments arguments)
3001                 {
3002                         Invocation.EmitCall (ec, InstanceExpression, best_candidate, arguments, loc);
3003                 }
3004
3005                 public override void Error_ValueCannotBeConverted (ResolveContext ec, Location loc, TypeSpec target, bool expl)
3006                 {
3007                         ec.Report.Error (428, loc, "Cannot convert method group `{0}' to non-delegate type `{1}'. Consider using parentheses to invoke the method",
3008                                 Name, TypeManager.CSharpName (target));
3009                 }
3010
3011                 public static bool IsExtensionMethodArgument (Expression expr)
3012                 {
3013                         //
3014                         // LAMESPEC: No details about which expressions are not allowed
3015                         //
3016                         return !(expr is BaseThis);
3017                 }
3018
3019                 /// <summary>
3020                 ///   Find the Applicable Function Members (7.4.2.1)
3021                 ///
3022                 ///   me: Method Group expression with the members to select.
3023                 ///       it might contain constructors or methods (or anything
3024                 ///       that maps to a method).
3025                 ///
3026                 ///   Arguments: ArrayList containing resolved Argument objects.
3027                 ///
3028                 ///   loc: The location if we want an error to be reported, or a Null
3029                 ///        location for "probing" purposes.
3030                 ///
3031                 ///   Returns: The MethodBase (either a ConstructorInfo or a MethodInfo)
3032                 ///            that is the best match of me on Arguments.
3033                 ///
3034                 /// </summary>
3035                 public virtual MethodGroupExpr OverloadResolve (ResolveContext ec, ref Arguments args, OverloadResolver.IErrorHandler cerrors, OverloadResolver.Restrictions restr)
3036                 {
3037                         // TODO: causes issues with probing mode, remove explicit Kind check
3038                         if (best_candidate != null && best_candidate.Kind == MemberKind.Destructor)
3039                                 return this;
3040
3041                         var r = new OverloadResolver (Methods, type_arguments, restr, loc);
3042                         if ((restr & OverloadResolver.Restrictions.NoBaseMembers) == 0) {
3043                                 r.BaseMembersProvider = this;
3044                         }
3045
3046                         if (cerrors != null)
3047                                 r.CustomErrors = cerrors;
3048
3049                         // TODO: When in probing mode do IsApplicable only and when called again do VerifyArguments for full error reporting
3050                         best_candidate = r.ResolveMember<MethodSpec> (ec, ref args);
3051                         if (best_candidate == null)
3052                                 return r.BestCandidateIsDynamic ? this : null;
3053
3054                         if (best_candidate.Kind == MemberKind.Method) {
3055                                 if (InstanceExpression != null) {
3056                                         if (best_candidate.IsExtensionMethod && args[0].Expr == InstanceExpression) {
3057                                                 InstanceExpression = null;
3058                                         } else {
3059                                                 if (best_candidate.IsStatic && simple_name != null) {
3060                                                         InstanceExpression = ProbeIdenticalTypeName (ec, InstanceExpression, simple_name);
3061                                                 }
3062
3063                                                 InstanceExpression.Resolve (ec);
3064                                         }
3065                                 }
3066
3067                                 ResolveInstanceExpression (ec);
3068                                 if (InstanceExpression != null)
3069                                         CheckProtectedMemberAccess (ec, best_candidate);
3070
3071                                 if (best_candidate.IsGeneric) {
3072                                         ConstraintChecker.CheckAll (ec.MemberContext, best_candidate.GetGenericMethodDefinition (), best_candidate.TypeArguments,
3073                                                 best_candidate.Constraints, loc);
3074                                 }
3075                         }
3076
3077                         best_candidate = CandidateToBaseOverride (ec, best_candidate);
3078                         return this;
3079                 }
3080
3081                 public override void SetTypeArguments (ResolveContext ec, TypeArguments ta)
3082                 {
3083                         type_arguments = ta;
3084                 }
3085
3086                 #region IBaseMembersProvider Members
3087
3088                 IList<MemberSpec> OverloadResolver.IBaseMembersProvider.GetBaseMembers (TypeSpec baseType)
3089                 {
3090                         return baseType == null ? null : MemberCache.FindMembers (baseType, Methods [0].Name, false);
3091                 }
3092
3093                 MethodGroupExpr OverloadResolver.IBaseMembersProvider.LookupExtensionMethod (ResolveContext rc, int arity)
3094                 {
3095                         if (InstanceExpression == null)
3096                                 return null;
3097
3098                         InstanceExpression = InstanceExpression.Resolve (rc);
3099                         if (!IsExtensionMethodArgument (InstanceExpression))
3100                                 return null;
3101
3102                         var emg = rc.LookupExtensionMethod (InstanceExpression.Type, Methods [0].Name, arity, loc);
3103                         if (emg != null) {
3104                                 emg.ExtensionExpression = InstanceExpression;
3105                                 emg.SetTypeArguments (rc, type_arguments);
3106                         }
3107
3108                         return emg;
3109                 }
3110
3111                 #endregion
3112         }
3113
3114         public struct OverloadResolver
3115         {
3116                 [Flags]
3117                 public enum Restrictions
3118                 {
3119                         None = 0,
3120                         DelegateInvoke = 1,
3121                         ProbingOnly     = 1 << 1,
3122                         Covariant = 1 << 2,
3123                         NoBaseMembers = 1 << 3
3124                 }
3125
3126                 public interface IBaseMembersProvider
3127                 {
3128                         IList<MemberSpec> GetBaseMembers (TypeSpec baseType);
3129                         MethodGroupExpr LookupExtensionMethod (ResolveContext rc, int arity);
3130                 }
3131
3132                 public interface IErrorHandler
3133                 {
3134                         bool AmbiguousCandidates (ResolveContext rc, MemberSpec best, MemberSpec ambiguous);
3135                         bool ArgumentMismatch (ResolveContext rc, MemberSpec best, Argument a, int index);
3136                         bool NoArgumentMatch (ResolveContext rc, MemberSpec best);
3137                         bool TypeInferenceFailed (ResolveContext rc, MemberSpec best);
3138                 }
3139
3140                 sealed class NoBaseMembers : IBaseMembersProvider
3141                 {
3142                         public static readonly IBaseMembersProvider Instance = new NoBaseMembers ();
3143
3144                         public IList<MemberSpec> GetBaseMembers (TypeSpec baseType)
3145                         {
3146                                 return null;
3147                         }
3148
3149                         public MethodGroupExpr LookupExtensionMethod (ResolveContext rc, int arity)
3150                         {
3151                                 return null;
3152                         }
3153                 }
3154
3155                 struct AmbiguousCandidate
3156                 {
3157                         public readonly MemberSpec Member;
3158                         public readonly bool Expanded;
3159
3160                         public AmbiguousCandidate (MemberSpec member, bool expanded)
3161                         {
3162                                 Member = member;
3163                                 Expanded = expanded;
3164                         }
3165                 }
3166
3167                 Location loc;
3168                 IList<MemberSpec> members;
3169                 TypeArguments type_arguments;
3170                 IBaseMembersProvider base_provider;
3171                 IErrorHandler custom_errors;
3172                 Restrictions restrictions;
3173
3174                 SessionReportPrinter lambda_conv_msgs;
3175                 ReportPrinter prev_recorder;
3176
3177                 public OverloadResolver (IList<MemberSpec> members, Restrictions restrictions, Location loc)
3178                         : this (members, null, restrictions, loc)
3179                 {
3180                 }
3181
3182                 public OverloadResolver (IList<MemberSpec> members, TypeArguments targs, Restrictions restrictions, Location loc)
3183                         : this ()
3184                 {
3185                         if (members == null || members.Count == 0)
3186                                 throw new ArgumentException ("empty members set");
3187
3188                         this.members = members;
3189                         this.loc = loc;
3190                         type_arguments = targs;
3191                         this.restrictions = restrictions;
3192                         if (IsDelegateInvoke)
3193                                 this.restrictions |= Restrictions.NoBaseMembers;
3194
3195                         base_provider = NoBaseMembers.Instance;
3196                 }
3197
3198                 #region Properties
3199
3200                 public IBaseMembersProvider BaseMembersProvider {
3201                         get {
3202                                 return base_provider;
3203                         }
3204                         set {
3205                                 base_provider = value;
3206                         }
3207                 }
3208
3209                 public bool BestCandidateIsDynamic { get; set; }
3210
3211                 public IErrorHandler CustomErrors {
3212                         get {
3213                                 return custom_errors;
3214                         }
3215                         set {
3216                                 custom_errors = value;
3217                         }
3218                 }
3219
3220                 TypeSpec DelegateType {
3221                         get {
3222                                 if ((restrictions & Restrictions.DelegateInvoke) == 0)
3223                                         throw new InternalErrorException ("Not running in delegate mode", loc);
3224
3225                                 return members [0].DeclaringType;
3226                         }
3227                 }
3228
3229                 bool IsProbingOnly {
3230                         get {
3231                                 return (restrictions & Restrictions.ProbingOnly) != 0;
3232                         }
3233                 }
3234
3235                 bool IsDelegateInvoke {
3236                         get {
3237                                 return (restrictions & Restrictions.DelegateInvoke) != 0;
3238                         }
3239                 }
3240
3241                 #endregion
3242
3243                 //
3244                 //  7.4.3.3  Better conversion from expression
3245                 //  Returns :   1    if a->p is better,
3246                 //              2    if a->q is better,
3247                 //              0 if neither is better
3248                 //
3249                 static int BetterExpressionConversion (ResolveContext ec, Argument a, TypeSpec p, TypeSpec q)
3250                 {
3251                         TypeSpec argument_type = a.Type;
3252                         if (argument_type == InternalType.AnonymousMethod && RootContext.Version > LanguageVersion.ISO_2) {
3253                                 //
3254                                 // Uwrap delegate from Expression<T>
3255                                 //
3256                                 if (p.GetDefinition () == TypeManager.expression_type) {
3257                                         p = TypeManager.GetTypeArguments (p)[0];
3258                                 }
3259                                 if (q.GetDefinition () == TypeManager.expression_type) {
3260                                         q = TypeManager.GetTypeArguments (q)[0];
3261                                 }
3262
3263                                 p = Delegate.GetInvokeMethod (ec.Compiler, p).ReturnType;
3264                                 q = Delegate.GetInvokeMethod (ec.Compiler, q).ReturnType;
3265                                 if (p == TypeManager.void_type && q != TypeManager.void_type)
3266                                         return 2;
3267                                 if (q == TypeManager.void_type && p != TypeManager.void_type)
3268                                         return 1;
3269                         } else {
3270                                 if (argument_type == p)
3271                                         return 1;
3272
3273                                 if (argument_type == q)
3274                                         return 2;
3275                         }
3276
3277                         return BetterTypeConversion (ec, p, q);
3278                 }
3279
3280                 //
3281                 // 7.4.3.4  Better conversion from type
3282                 //
3283                 public static int BetterTypeConversion (ResolveContext ec, TypeSpec p, TypeSpec q)
3284                 {
3285                         if (p == null || q == null)
3286                                 throw new InternalErrorException ("BetterTypeConversion got a null conversion");
3287
3288                         if (p == TypeManager.int32_type) {
3289                                 if (q == TypeManager.uint32_type || q == TypeManager.uint64_type)
3290                                         return 1;
3291                         } else if (p == TypeManager.int64_type) {
3292                                 if (q == TypeManager.uint64_type)
3293                                         return 1;
3294                         } else if (p == TypeManager.sbyte_type) {
3295                                 if (q == TypeManager.byte_type || q == TypeManager.ushort_type ||
3296                                         q == TypeManager.uint32_type || q == TypeManager.uint64_type)
3297                                         return 1;
3298                         } else if (p == TypeManager.short_type) {
3299                                 if (q == TypeManager.ushort_type || q == TypeManager.uint32_type ||
3300                                         q == TypeManager.uint64_type)
3301                                         return 1;
3302                         } else if (p == InternalType.Dynamic) {
3303                                 if (q == TypeManager.object_type)
3304                                         return 2;
3305                         }
3306
3307                         if (q == TypeManager.int32_type) {
3308                                 if (p == TypeManager.uint32_type || p == TypeManager.uint64_type)
3309                                         return 2;
3310                         } if (q == TypeManager.int64_type) {
3311                                 if (p == TypeManager.uint64_type)
3312                                         return 2;
3313                         } else if (q == TypeManager.sbyte_type) {
3314                                 if (p == TypeManager.byte_type || p == TypeManager.ushort_type ||
3315                                         p == TypeManager.uint32_type || p == TypeManager.uint64_type)
3316                                         return 2;
3317                         } if (q == TypeManager.short_type) {
3318                                 if (p == TypeManager.ushort_type || p == TypeManager.uint32_type ||
3319                                         p == TypeManager.uint64_type)
3320                                         return 2;
3321                         } else if (q == InternalType.Dynamic) {
3322                                 if (p == TypeManager.object_type)
3323                                         return 1;
3324                         }
3325
3326                         // TODO: this is expensive
3327                         Expression p_tmp = new EmptyExpression (p);
3328                         Expression q_tmp = new EmptyExpression (q);
3329
3330                         bool p_to_q = Convert.ImplicitConversionExists (ec, p_tmp, q);
3331                         bool q_to_p = Convert.ImplicitConversionExists (ec, q_tmp, p);
3332
3333                         if (p_to_q && !q_to_p)
3334                                 return 1;
3335
3336                         if (q_to_p && !p_to_q)
3337                                 return 2;
3338
3339                         return 0;
3340                 }
3341
3342                 /// <summary>
3343                 ///   Determines "Better function" between candidate
3344                 ///   and the current best match
3345                 /// </summary>
3346                 /// <remarks>
3347                 ///    Returns a boolean indicating :
3348                 ///     false if candidate ain't better
3349                 ///     true  if candidate is better than the current best match
3350                 /// </remarks>
3351                 static bool BetterFunction (ResolveContext ec, Arguments args, MemberSpec candidate, bool candidate_params,
3352                         MemberSpec best, bool best_params)
3353                 {
3354                         AParametersCollection candidate_pd = ((IParametersMember) candidate).Parameters;
3355                         AParametersCollection best_pd = ((IParametersMember) best).Parameters;
3356
3357                         bool better_at_least_one = false;
3358                         bool same = true;
3359                         int args_count = args == null ? 0 : args.Count;
3360                         for (int j = 0, c_idx = 0, b_idx = 0; j < args_count; ++j, ++c_idx, ++b_idx) {
3361                                 Argument a = args[j];
3362
3363                                 // Provided default argument value is never better
3364                                 if (a.IsDefaultArgument && candidate_params == best_params)
3365                                         return false;
3366
3367                                 TypeSpec ct = candidate_pd.Types[c_idx];
3368                                 TypeSpec bt = best_pd.Types[b_idx];
3369
3370                                 if (candidate_params && candidate_pd.FixedParameters[c_idx].ModFlags == Parameter.Modifier.PARAMS) {
3371                                         ct = TypeManager.GetElementType (ct);
3372                                         --c_idx;
3373                                 }
3374
3375                                 if (best_params && best_pd.FixedParameters[b_idx].ModFlags == Parameter.Modifier.PARAMS) {
3376                                         bt = TypeManager.GetElementType (bt);
3377                                         --b_idx;
3378                                 }
3379
3380                                 if (TypeManager.IsEqual (ct, bt))
3381                                         continue;
3382
3383                                 same = false;
3384                                 int result = BetterExpressionConversion (ec, a, ct, bt);
3385
3386                                 // for each argument, the conversion to 'ct' should be no worse than
3387                                 // the conversion to 'bt'.
3388                                 if (result == 2)
3389                                         return false;
3390
3391                                 // for at least one argument, the conversion to 'ct' should be better than
3392                                 // the conversion to 'bt'.
3393                                 if (result != 0)
3394                                         better_at_least_one = true;
3395                         }
3396
3397                         if (better_at_least_one)
3398                                 return true;
3399
3400                         //
3401                         // This handles the case
3402                         //
3403                         //   Add (float f1, float f2, float f3);
3404                         //   Add (params decimal [] foo);
3405                         //
3406                         // The call Add (3, 4, 5) should be ambiguous.  Without this check, the
3407                         // first candidate would've chosen as better.
3408                         //
3409                         if (!same)
3410                                 return false;
3411
3412                         //
3413                         // The two methods have equal parameter types.  Now apply tie-breaking rules
3414                         //
3415                         if (best.IsGeneric) {
3416                                 if (!candidate.IsGeneric)
3417                                         return true;
3418                         } else if (candidate.IsGeneric) {
3419                                 return false;
3420                         }
3421
3422                         //
3423                         // This handles the following cases:
3424                         //
3425                         //   Trim () is better than Trim (params char[] chars)
3426                         //   Concat (string s1, string s2, string s3) is better than
3427                         //     Concat (string s1, params string [] srest)
3428                         //   Foo (int, params int [] rest) is better than Foo (params int [] rest)
3429                         //
3430                         if (!candidate_params && best_params)
3431                                 return true;
3432                         if (candidate_params && !best_params)
3433                                 return false;
3434
3435                         int candidate_param_count = candidate_pd.Count;
3436                         int best_param_count = best_pd.Count;
3437
3438                         if (candidate_param_count != best_param_count)
3439                                 // can only happen if (candidate_params && best_params)
3440                                 return candidate_param_count > best_param_count && best_pd.HasParams;
3441
3442                         //
3443                         // Both methods have the same number of parameters, and the parameters have equal types
3444                         // Pick the "more specific" signature using rules over original (non-inflated) types
3445                         //
3446                         var candidate_def_pd = ((IParametersMember) candidate.MemberDefinition).Parameters;
3447                         var best_def_pd = ((IParametersMember) best.MemberDefinition).Parameters;
3448
3449                         bool specific_at_least_once = false;
3450                         for (int j = 0; j < candidate_param_count; ++j) {
3451                                 var ct = candidate_def_pd.Types[j];
3452                                 var bt = best_def_pd.Types[j];
3453                                 if (ct == bt)
3454                                         continue;
3455                                 TypeSpec specific = MoreSpecific (ct, bt);
3456                                 if (specific == bt)
3457                                         return false;
3458                                 if (specific == ct)
3459                                         specific_at_least_once = true;
3460                         }
3461
3462                         if (specific_at_least_once)
3463                                 return true;
3464
3465                         // FIXME: handle lifted operators
3466                         // ...
3467
3468                         return false;
3469                 }
3470
3471                 public static void Error_ConstructorMismatch (ResolveContext rc, TypeSpec type, int argCount, Location loc)
3472                 {
3473                         rc.Report.Error (1729, loc,
3474                                 "The type `{0}' does not contain a constructor that takes `{1}' arguments",
3475                                 type.GetSignatureForError (), argCount.ToString ());
3476                 }
3477
3478                 ///
3479                 /// Determines if the candidate method is applicable (section 14.4.2.1)
3480                 /// to the given set of arguments
3481                 /// A return value rates candidate method compatibility,
3482                 /// 0 = the best, int.MaxValue = the worst
3483                 ///
3484                 int IsApplicable (ResolveContext ec, ref Arguments arguments, int arg_count, ref MemberSpec candidate, ref bool params_expanded_form)
3485                 {
3486                         AParametersCollection pd = ((IParametersMember) candidate).Parameters;
3487                         int param_count = pd.Count;
3488                         int optional_count = 0;
3489
3490                         if (arg_count != param_count) {
3491                                 for (int i = 0; i < pd.Count; ++i) {
3492                                         if (pd.FixedParameters[i].HasDefaultValue) {
3493                                                 optional_count = pd.Count - i;
3494                                                 break;
3495                                         }
3496                                 }
3497
3498                                 int args_gap = System.Math.Abs (arg_count - param_count);
3499                                 if (optional_count != 0) {
3500                                         if (args_gap > optional_count)
3501                                                 return int.MaxValue - 10000 + args_gap - optional_count;
3502
3503                                         // Readjust expected number when params used
3504                                         if (pd.HasParams) {
3505                                                 optional_count--;
3506                                                 if (arg_count < param_count)
3507                                                         param_count--;
3508                                         } else if (arg_count > param_count) {
3509                                                 return int.MaxValue - 10000 + args_gap;
3510                                         }
3511                                 } else if (arg_count != param_count) {
3512                                         if (!pd.HasParams)
3513                                                 return int.MaxValue - 10000 + args_gap;
3514                                         if (arg_count < param_count - 1)
3515                                                 return int.MaxValue - 10000 + args_gap;
3516                                 }
3517
3518                                 // Initialize expanded form of a method with 1 params parameter
3519                                 params_expanded_form = param_count == 1 && pd.HasParams;
3520
3521                                 // Resize to fit optional arguments
3522                                 if (optional_count != 0) {
3523                                         Arguments resized;
3524                                         if (arguments == null) {
3525                                                 resized = new Arguments (optional_count);
3526                                         } else {
3527                                                 resized = new Arguments (param_count);
3528                                                 resized.AddRange (arguments);
3529                                         }
3530
3531                                         for (int i = arg_count; i < param_count; ++i)
3532                                                 resized.Add (null);
3533                                         arguments = resized;
3534                                 }
3535                         }
3536
3537                         if (arg_count > 0) {
3538                                 //
3539                                 // Shuffle named arguments to the right positions if there are any
3540                                 //
3541                                 if (arguments[arg_count - 1] is NamedArgument) {
3542                                         arg_count = arguments.Count;
3543
3544                                         for (int i = 0; i < arg_count; ++i) {
3545                                                 bool arg_moved = false;
3546                                                 while (true) {
3547                                                         NamedArgument na = arguments[i] as NamedArgument;
3548                                                         if (na == null)
3549                                                                 break;
3550
3551                                                         int index = pd.GetParameterIndexByName (na.Name);
3552
3553                                                         // Named parameter not found or already reordered
3554                                                         if (index <= i)
3555                                                                 break;
3556
3557                                                         // When using parameters which should not be available to the user
3558                                                         if (index >= param_count)
3559                                                                 break;
3560
3561                                                         if (!arg_moved) {
3562                                                                 arguments.MarkReorderedArgument (na);
3563                                                                 arg_moved = true;
3564                                                         }
3565
3566                                                         Argument temp = arguments[index];
3567                                                         arguments[index] = arguments[i];
3568                                                         arguments[i] = temp;
3569
3570                                                         if (temp == null)
3571                                                                 break;
3572                                                 }
3573                                         }
3574                                 } else {
3575                                         arg_count = arguments.Count;
3576                                 }
3577                         } else if (arguments != null) {
3578                                 arg_count = arguments.Count;
3579                         }
3580
3581                         //
3582                         // 1. Handle generic method using type arguments when specified or type inference
3583                         //
3584                         var ms = candidate as MethodSpec;
3585                         if (ms != null && ms.IsGeneric) {
3586                                 if (type_arguments != null) {
3587                                         var g_args_count = ms.Arity;
3588                                         if (g_args_count != type_arguments.Count)
3589                                                 return int.MaxValue - 20000 + System.Math.Abs (type_arguments.Count - g_args_count);
3590
3591                                         candidate = ms = ms.MakeGenericMethod (type_arguments.Arguments);
3592                                         pd = ms.Parameters;
3593                                 } else {
3594                                         // TODO: It should not be here (we don't know yet whether any argument is lambda) but
3595                                         // for now it simplifies things. I should probably add a callback to ResolveContext
3596                                         if (lambda_conv_msgs == null) {
3597                                                 lambda_conv_msgs = new SessionReportPrinter ();
3598                                                 prev_recorder = ec.Report.SetPrinter (lambda_conv_msgs);
3599                                         }
3600
3601                                         int score = TypeManager.InferTypeArguments (ec, arguments, ref ms);
3602                                         lambda_conv_msgs.EndSession ();
3603
3604                                         if (score != 0)
3605                                                 return score - 20000;
3606
3607                                         candidate = ms;
3608                                         pd = ms.Parameters;
3609                                 }
3610                         } else {
3611                                 if (type_arguments != null)
3612                                         return int.MaxValue - 15000;
3613                         }
3614
3615                         //
3616                         // 2. Each argument has to be implicitly convertible to method parameter
3617                         //
3618                         Parameter.Modifier p_mod = 0;
3619                         TypeSpec pt = null;
3620                         for (int i = 0; i < arg_count; i++) {
3621                                 Argument a = arguments[i];
3622                                 if (a == null) {
3623                                         if (!pd.FixedParameters[i].HasDefaultValue)
3624                                                 throw new InternalErrorException ();
3625
3626                                         Expression e = pd.FixedParameters[i].DefaultValue as Constant;
3627                                         if (e == null)
3628                                                 e = new DefaultValueExpression (new TypeExpression (pd.Types[i], loc), loc).Resolve (ec);
3629
3630                                         arguments[i] = new Argument (e, Argument.AType.Default);
3631                                         continue;
3632                                 }
3633
3634                                 if (p_mod != Parameter.Modifier.PARAMS) {
3635                                         p_mod = pd.FixedParameters[i].ModFlags & ~(Parameter.Modifier.OUTMASK | Parameter.Modifier.REFMASK);
3636                                         pt = pd.Types[i];
3637                                 } else {
3638                                         params_expanded_form = true;
3639                                 }
3640
3641                                 Parameter.Modifier a_mod = a.Modifier & ~(Parameter.Modifier.OUTMASK | Parameter.Modifier.REFMASK);
3642                                 int score = 1;
3643                                 if (!params_expanded_form)
3644                                         score = IsArgumentCompatible (ec, a_mod, a, p_mod & ~Parameter.Modifier.PARAMS, pt);
3645
3646                                 //
3647                                 // It can be applicable in expanded form (when not doing exact match like for delegates)
3648                                 //
3649                                 if (score != 0 && (p_mod & Parameter.Modifier.PARAMS) != 0 && (restrictions & Restrictions.Covariant) == 0) {
3650                                         score = IsArgumentCompatible (ec, a_mod, a, 0, TypeManager.GetElementType (pt));
3651                                         if (score == 0)
3652                                                 params_expanded_form = true;
3653                                 }
3654
3655                                 if (score != 0) {
3656                                         if (params_expanded_form)
3657                                                 ++score;
3658                                         return (arg_count - i) * 2 + score;
3659                                 }
3660                         }
3661
3662                         if (arg_count != param_count)
3663                                 params_expanded_form = true;
3664
3665                         return 0;
3666                 }
3667
3668                 int IsArgumentCompatible (ResolveContext ec, Parameter.Modifier arg_mod, Argument argument, Parameter.Modifier param_mod, TypeSpec parameter)
3669                 {
3670                         //
3671                         // Types have to be identical when ref or out modifer is used
3672                         //
3673                         if ((arg_mod | param_mod) != 0) {
3674                                 if (argument.Type != parameter) {
3675                                         if (argument.Type == InternalType.Dynamic)
3676                                                 return 0;
3677
3678                                         return 2;
3679                                 }
3680                         } else {
3681                                 //
3682                                 // Deploy custom error reporting for lambda methods. When probing lambda methods
3683                                 // keep all errors reported in separate set and once we are done and no best
3684                                 // candidate found, this set is used to report more details about what was wrong
3685                                 // with lambda body
3686                                 //
3687                                 if (argument.Expr.Type == InternalType.AnonymousMethod) {
3688                                         if (lambda_conv_msgs == null) {
3689                                                 lambda_conv_msgs = new SessionReportPrinter ();
3690                                                 prev_recorder = ec.Report.SetPrinter (lambda_conv_msgs);
3691                                         }
3692                                 }
3693
3694                                 if (!Convert.ImplicitConversionExists (ec, argument.Expr, parameter)) {
3695                                         if (lambda_conv_msgs != null) {
3696                                                 lambda_conv_msgs.EndSession ();
3697                                         }
3698
3699                                         if (argument.Type == InternalType.Dynamic)
3700                                                 return 0;
3701
3702                                         return 2;
3703                                 }
3704                         }
3705
3706                         if (arg_mod != param_mod)
3707                                 return 1;
3708
3709                         return 0;
3710                 }
3711
3712                 static TypeSpec MoreSpecific (TypeSpec p, TypeSpec q)
3713                 {
3714                         if (TypeManager.IsGenericParameter (p) && !TypeManager.IsGenericParameter (q))
3715                                 return q;
3716                         if (!TypeManager.IsGenericParameter (p) && TypeManager.IsGenericParameter (q))
3717                                 return p;
3718
3719                         var ac_p = p as ArrayContainer;
3720                         if (ac_p != null) {
3721                                 var ac_q = ((ArrayContainer) q);
3722                                 TypeSpec specific = MoreSpecific (ac_p.Element, ac_q.Element);
3723                                 if (specific == ac_p.Element)
3724                                         return p;
3725                                 if (specific == ac_q.Element)
3726                                         return q;
3727                         } else if (TypeManager.IsGenericType (p)) {
3728                                 var pargs = TypeManager.GetTypeArguments (p);
3729                                 var qargs = TypeManager.GetTypeArguments (q);
3730
3731                                 bool p_specific_at_least_once = false;
3732                                 bool q_specific_at_least_once = false;
3733
3734                                 for (int i = 0; i < pargs.Length; i++) {
3735                                         TypeSpec specific = MoreSpecific (pargs[i], qargs[i]);
3736                                         if (specific == pargs[i])
3737                                                 p_specific_at_least_once = true;
3738                                         if (specific == qargs[i])
3739                                                 q_specific_at_least_once = true;
3740                                 }
3741
3742                                 if (p_specific_at_least_once && !q_specific_at_least_once)
3743                                         return p;
3744                                 if (!p_specific_at_least_once && q_specific_at_least_once)
3745                                         return q;
3746                         }
3747
3748                         return null;
3749                 }
3750
3751                 //
3752                 // Find the best method from candidate list
3753                 //
3754                 public T ResolveMember<T> (ResolveContext rc, ref Arguments args) where T : MemberSpec, IParametersMember
3755                 {
3756                         List<AmbiguousCandidate> ambiguous_candidates = null;
3757
3758                         MemberSpec best_candidate;
3759                         Arguments best_candidate_args = null;
3760                         bool best_candidate_params = false;
3761                         int best_candidate_rate;
3762
3763                         int args_count = args != null ? args.Count : 0;
3764                         Arguments candidate_args = args;
3765                         bool error_mode = false;
3766                         var current_type = rc.CurrentType;
3767                         MemberSpec invocable_member = null;
3768
3769                         // Cannot return until error reporter is restored
3770                         while (true) {
3771                                 best_candidate = null;
3772                                 best_candidate_rate = int.MaxValue;
3773
3774                                 var type_members = members;
3775
3776                                 do {
3777                                         for (int i = 0; i < type_members.Count; ++i) {
3778                                                 var member = type_members [i];
3779
3780                                                 //
3781                                                 // Methods in a base class are not candidates if any method in a derived
3782                                                 // class is applicable
3783                                                 //
3784                                                 if ((member.Modifiers & Modifiers.OVERRIDE) != 0)
3785                                                         continue;
3786
3787                                                 if (!member.IsAccessible (current_type) && !error_mode)
3788                                                         continue;
3789
3790                                                 if (!(member is IParametersMember)) {
3791                                                         //
3792                                                         // Will use it later to report ambiguity between best method and invocable member
3793                                                         //
3794                                                         if (Invocation.IsMemberInvocable (member))
3795                                                                 invocable_member = member;
3796
3797                                                         continue;
3798                                                 }
3799
3800                                                 //
3801                                                 // Check if candidate is applicable
3802                                                 //
3803                                                 bool params_expanded_form = false;
3804                                                 int candidate_rate = IsApplicable (rc, ref candidate_args, args_count, ref member, ref params_expanded_form);
3805
3806                                                 //
3807                                                 // How does it score compare to others
3808                                                 //
3809                                                 if (candidate_rate < best_candidate_rate) {
3810                                                         best_candidate_rate = candidate_rate;
3811                                                         best_candidate = member;
3812                                                         best_candidate_args = candidate_args;
3813                                                         best_candidate_params = params_expanded_form;
3814                                                 } else if (candidate_rate == 0) {
3815                                                         // Is new candidate better
3816                                                         if (BetterFunction (rc, candidate_args, member, params_expanded_form, best_candidate, best_candidate_params)) {
3817                                                                 best_candidate = member;
3818                                                                 best_candidate_args = candidate_args;
3819                                                                 best_candidate_params = params_expanded_form;
3820                                                         } else {
3821                                                                 // It's not better but any other found later could be but we are not sure yet
3822                                                                 if (ambiguous_candidates == null)
3823                                                                         ambiguous_candidates = new List<AmbiguousCandidate> ();
3824
3825                                                                 ambiguous_candidates.Add (new AmbiguousCandidate (member, params_expanded_form));
3826                                                         }
3827                                                 }
3828
3829                                                 // Restore expanded arguments
3830                                                 if (candidate_args != args)
3831                                                         candidate_args = args;
3832                                         }
3833                                 } while (best_candidate_rate != 0 && (type_members = base_provider.GetBaseMembers (type_members[0].DeclaringType.BaseType)) != null);
3834
3835                                 if (prev_recorder != null)
3836                                         rc.Report.SetPrinter (prev_recorder);
3837
3838                                 //
3839                                 // We've found exact match
3840                                 //
3841                                 if (best_candidate_rate == 0)
3842                                         break;
3843
3844                                 //
3845                                 // Extension methods lookup when no ordinary method match was found
3846                                 //
3847                                 if (!error_mode) {
3848                                         var emg = base_provider.LookupExtensionMethod (rc, type_arguments == null ? 0 : type_arguments.Count);
3849                                         if (emg != null) {
3850                                                 emg = emg.OverloadResolve (rc, ref args, custom_errors, error_mode ? Restrictions.ProbingOnly : Restrictions.None);
3851                                                 if (emg != null)
3852                                                         return (T) (MemberSpec) emg.BestCandidate;
3853                                         }
3854                                 }
3855
3856                                 // Don't run expensive error reporting mode for probing
3857                                 if (IsProbingOnly)
3858                                         return null;
3859
3860                                 if (error_mode)
3861                                         break;
3862
3863                                 lambda_conv_msgs = null;
3864                                 error_mode = true;
3865                         }
3866
3867                         //
3868                         // No best member match found, report an error
3869                         //
3870                         if (best_candidate_rate != 0 || error_mode) {
3871                                 ReportOverloadError (rc, best_candidate, best_candidate_args, best_candidate_params);
3872                                 return null;
3873                         }
3874
3875                         // TODO: quite slow
3876                         if (args_count != 0 && args.HasDynamic) {
3877                                 BestCandidateIsDynamic = true;
3878                                 return null;
3879                         }
3880
3881                         if (ambiguous_candidates != null) {
3882                                 //
3883                                 // Now check that there are no ambiguities i.e the selected method
3884                                 // should be better than all the others
3885                                 //
3886                                 for (int ix = 0; ix < ambiguous_candidates.Count; ix++) {
3887                                         var candidate = ambiguous_candidates [ix];
3888
3889                                         if (!BetterFunction (rc, candidate_args, best_candidate, best_candidate_params, candidate.Member, candidate.Expanded)) {
3890                                                 var ambiguous = candidate.Member;
3891                                                 if (custom_errors == null || !custom_errors.AmbiguousCandidates (rc, best_candidate, ambiguous)) {
3892                                                         rc.Report.SymbolRelatedToPreviousError (best_candidate);
3893                                                         rc.Report.SymbolRelatedToPreviousError (ambiguous);
3894                                                         rc.Report.Error (121, loc, "The call is ambiguous between the following methods or properties: `{0}' and `{1}'",
3895                                                                 best_candidate.GetSignatureForError (), ambiguous.GetSignatureForError ());
3896                                                 }
3897
3898                                                 return (T) best_candidate;
3899                                         }
3900                                 }
3901                         }
3902
3903                         if (invocable_member != null) {
3904                                 rc.Report.SymbolRelatedToPreviousError (best_candidate);
3905                                 rc.Report.SymbolRelatedToPreviousError (invocable_member);
3906                                 rc.Report.Warning (467, 2, loc, "Ambiguity between method `{0}' and invocable non-method `{1}'. Using method group",
3907                                         best_candidate.GetSignatureForError (), invocable_member.GetSignatureForError ());
3908                         }
3909
3910                         //
3911                         // And now check if the arguments are all
3912                         // compatible, perform conversions if
3913                         // necessary etc. and return if everything is
3914                         // all right
3915                         //
3916                         if (!VerifyArguments (rc, ref best_candidate_args, best_candidate, best_candidate_params))
3917                                 return null;
3918
3919                         if (best_candidate == null)
3920                                 return null;
3921
3922                         //
3923                         // Check ObsoleteAttribute on the best method
3924                         //
3925                         ObsoleteAttribute oa = best_candidate.GetAttributeObsolete ();
3926                         if (oa != null && !rc.IsObsolete)
3927                                 AttributeTester.Report_ObsoleteMessage (oa, best_candidate.GetSignatureForError (), loc, rc.Report);
3928
3929                         best_candidate.MemberDefinition.SetIsUsed ();
3930
3931                         args = best_candidate_args;
3932                         return (T) best_candidate;
3933                 }
3934
3935                 public MethodSpec ResolveOperator (ResolveContext rc, ref Arguments args)
3936                 {
3937                         return ResolveMember<MethodSpec> (rc, ref args);
3938                 }
3939
3940                 void ReportArgumentMismatch (ResolveContext ec, int idx, MemberSpec method,
3941                                                                                                         Argument a, AParametersCollection expected_par, TypeSpec paramType)
3942                 {
3943                         if (custom_errors != null && custom_errors.ArgumentMismatch (ec, method, a, idx))
3944                                 return;
3945
3946                         if (a is CollectionElementInitializer.ElementInitializerArgument) {
3947                                 ec.Report.SymbolRelatedToPreviousError (method);
3948                                 if ((expected_par.FixedParameters[idx].ModFlags & Parameter.Modifier.ISBYREF) != 0) {
3949                                         ec.Report.Error (1954, loc, "The best overloaded collection initalizer method `{0}' cannot have 'ref', or `out' modifier",
3950                                                 TypeManager.CSharpSignature (method));
3951                                         return;
3952                                 }
3953                                 ec.Report.Error (1950, loc, "The best overloaded collection initalizer method `{0}' has some invalid arguments",
3954                                           TypeManager.CSharpSignature (method));
3955                         } else if (IsDelegateInvoke) {
3956                                 ec.Report.Error (1594, loc, "Delegate `{0}' has some invalid arguments",
3957                                         DelegateType.GetSignatureForError ());
3958                         } else {
3959                                 ec.Report.SymbolRelatedToPreviousError (method);
3960                                 ec.Report.Error (1502, loc, "The best overloaded method match for `{0}' has some invalid arguments",
3961                                         method.GetSignatureForError ());
3962                         }
3963
3964                         Parameter.Modifier mod = idx >= expected_par.Count ? 0 : expected_par.FixedParameters[idx].ModFlags;
3965
3966                         string index = (idx + 1).ToString ();
3967                         if (((mod & (Parameter.Modifier.REF | Parameter.Modifier.OUT)) ^
3968                                 (a.Modifier & (Parameter.Modifier.REF | Parameter.Modifier.OUT))) != 0) {
3969                                 if ((mod & Parameter.Modifier.ISBYREF) == 0)
3970                                         ec.Report.Error (1615, loc, "Argument `#{0}' does not require `{1}' modifier. Consider removing `{1}' modifier",
3971                                                 index, Parameter.GetModifierSignature (a.Modifier));
3972                                 else
3973                                         ec.Report.Error (1620, loc, "Argument `#{0}' is missing `{1}' modifier",
3974                                                 index, Parameter.GetModifierSignature (mod));
3975                         } else {
3976                                 string p1 = a.GetSignatureForError ();
3977                                 string p2 = TypeManager.CSharpName (paramType);
3978
3979                                 if (p1 == p2) {
3980                                         ec.Report.ExtraInformation (loc, "(equally named types possibly from different assemblies in previous ");
3981                                         ec.Report.SymbolRelatedToPreviousError (a.Expr.Type);
3982                                         ec.Report.SymbolRelatedToPreviousError (paramType);
3983                                 }
3984
3985                                 ec.Report.Error (1503, loc,
3986                                         "Argument `#{0}' cannot convert `{1}' expression to type `{2}'", index, p1, p2);
3987                         }
3988                 }
3989
3990                 //
3991                 // We have failed to find exact match so we return error info about the closest match
3992                 //
3993                 void ReportOverloadError (ResolveContext rc, MemberSpec best_candidate, Arguments args, bool params_expanded)
3994                 {
3995                         int ta_count = type_arguments == null ? 0 : type_arguments.Count;
3996                         int arg_count = args == null ? 0 : args.Count;
3997
3998                         if (ta_count != best_candidate.Arity && (ta_count > 0 || ((IParametersMember) best_candidate).Parameters.IsEmpty)) {
3999                                 var mg = new MethodGroupExpr (new [] { best_candidate }, best_candidate.DeclaringType, loc);
4000                                 mg.Error_TypeArgumentsCannotBeUsed (rc.Report, loc, best_candidate, ta_count);
4001                                 return;
4002                         }
4003
4004                         if (lambda_conv_msgs != null) {
4005                                 if (lambda_conv_msgs.Merge (rc.Report.Printer))
4006                                         return;
4007                         }
4008
4009                         //
4010                         // For candidates which match on parameters count report more details about incorrect arguments
4011                         //
4012                         var pm = best_candidate as IParametersMember;
4013                         if (pm != null) {
4014                                 int unexpanded_count = pm.Parameters.HasParams ? pm.Parameters.Count - 1 : pm.Parameters.Count;
4015                                 if (pm.Parameters.Count == arg_count || params_expanded || unexpanded_count == arg_count) {
4016                                         // Reject any inaccessible member
4017                                         if (!best_candidate.IsAccessible (rc.CurrentType)) {
4018                                                 rc.Report.SymbolRelatedToPreviousError (best_candidate);
4019                                                 Expression.ErrorIsInaccesible (rc, best_candidate.GetSignatureForError (), loc);
4020                                                 return;
4021                                         }
4022
4023                                         var ms = best_candidate as MethodSpec;
4024                                         if (ms != null && ms.IsGeneric && ta_count == 0) {
4025                                                 if (custom_errors != null && custom_errors.TypeInferenceFailed (rc, best_candidate))
4026                                                         return;
4027
4028                                                 rc.Report.Error (411, loc,
4029                                                         "The type arguments for method `{0}' cannot be inferred from the usage. Try specifying the type arguments explicitly",
4030                                                         ms.GetGenericMethodDefinition ().GetSignatureForError ());
4031                                                 return;
4032                                         }
4033
4034                                         VerifyArguments (rc, ref args, best_candidate, params_expanded);
4035                                         return;
4036                                 }
4037                         }
4038
4039                         //
4040                         // We failed to find any method with correct argument count, report best candidate
4041                         //
4042                         if (custom_errors != null && custom_errors.NoArgumentMatch (rc, best_candidate))
4043                                 return;
4044
4045                         if (best_candidate.Kind == MemberKind.Constructor) {
4046                                 rc.Report.SymbolRelatedToPreviousError (best_candidate);
4047                                 Error_ConstructorMismatch (rc, best_candidate.DeclaringType, arg_count, loc);
4048                         } else if (IsDelegateInvoke) {
4049                                 rc.Report.SymbolRelatedToPreviousError (DelegateType);
4050                                 rc.Report.Error (1593, loc, "Delegate `{0}' does not take `{1}' arguments",
4051                                         DelegateType.GetSignatureForError (), arg_count.ToString ());
4052                         } else {
4053                                 string name = best_candidate.Kind == MemberKind.Indexer ? "this" : best_candidate.Name;
4054                                 rc.Report.SymbolRelatedToPreviousError (best_candidate);
4055                                 rc.Report.Error (1501, loc, "No overload for method `{0}' takes `{1}' arguments",
4056                                         name, arg_count.ToString ());
4057                         }
4058                 }
4059
4060                 bool VerifyArguments (ResolveContext ec, ref Arguments args, MemberSpec member, bool chose_params_expanded)
4061                 {
4062                         var pm = member as IParametersMember;
4063                         var pd = pm.Parameters;
4064
4065                         Parameter.Modifier p_mod = 0;
4066                         TypeSpec pt = null;
4067                         int a_idx = 0, a_pos = 0;
4068                         Argument a = null;
4069                         ArrayInitializer params_initializers = null;
4070                         bool has_unsafe_arg = pm.MemberType.IsPointer;
4071                         int arg_count = args == null ? 0 : args.Count;
4072
4073                         for (; a_idx < arg_count; a_idx++, ++a_pos) {
4074                                 a = args[a_idx];
4075                                 if (p_mod != Parameter.Modifier.PARAMS) {
4076                                         p_mod = pd.FixedParameters[a_idx].ModFlags;
4077                                         pt = pd.Types[a_idx];
4078                                         has_unsafe_arg |= pt.IsPointer;
4079
4080                                         if (p_mod == Parameter.Modifier.PARAMS) {
4081                                                 if (chose_params_expanded) {
4082                                                         params_initializers = new ArrayInitializer (arg_count - a_idx, a.Expr.Location);
4083                                                         pt = TypeManager.GetElementType (pt);
4084                                                 }
4085                                         }
4086                                 }
4087
4088                                 //
4089                                 // Types have to be identical when ref or out modifer is used
4090                                 //
4091                                 if (a.Modifier != 0 || (p_mod & ~Parameter.Modifier.PARAMS) != 0) {
4092                                         if ((p_mod & ~Parameter.Modifier.PARAMS) != a.Modifier)
4093                                                 break;
4094
4095                                         if (!TypeManager.IsEqual (a.Expr.Type, pt))
4096                                                 break;
4097
4098                                         continue;
4099                                 }
4100
4101                                 NamedArgument na = a as NamedArgument;
4102                                 if (na != null) {
4103                                         int name_index = pd.GetParameterIndexByName (na.Name);
4104                                         if (name_index < 0 || name_index >= pd.Count) {
4105                                                 if (IsDelegateInvoke) {
4106                                                         ec.Report.SymbolRelatedToPreviousError (DelegateType);
4107                                                         ec.Report.Error (1746, na.Location,
4108                                                                 "The delegate `{0}' does not contain a parameter named `{1}'",
4109                                                                 DelegateType.GetSignatureForError (), na.Name);
4110                                                 } else {
4111                                                         ec.Report.SymbolRelatedToPreviousError (member);
4112                                                         ec.Report.Error (1739, na.Location,
4113                                                                 "The best overloaded method match for `{0}' does not contain a parameter named `{1}'",
4114                                                                 TypeManager.CSharpSignature (member), na.Name);
4115                                                 }
4116                                         } else if (args[name_index] != a) {
4117                                                 if (IsDelegateInvoke)
4118                                                         ec.Report.SymbolRelatedToPreviousError (DelegateType);
4119                                                 else
4120                                                         ec.Report.SymbolRelatedToPreviousError (member);
4121
4122                                                 ec.Report.Error (1744, na.Location,
4123                                                         "Named argument `{0}' cannot be used for a parameter which has positional argument specified",
4124                                                         na.Name);
4125                                         }
4126                                 }
4127
4128                                 if (a.Expr.Type == InternalType.Dynamic)
4129                                         continue;
4130
4131                                 if ((restrictions & Restrictions.Covariant) != 0 && !Delegate.IsTypeCovariant (a.Expr, pt)) {
4132                                         custom_errors.NoArgumentMatch (ec, member);
4133                                         return false;
4134                                 }
4135
4136                                 Expression conv = Convert.ImplicitConversion (ec, a.Expr, pt, loc);
4137                                 if (conv == null)
4138                                         break;
4139
4140                                 //
4141                                 // Convert params arguments to an array initializer
4142                                 //
4143                                 if (params_initializers != null) {
4144                                         // we choose to use 'a.Expr' rather than 'conv' so that
4145                                         // we don't hide the kind of expression we have (esp. CompoundAssign.Helper)
4146                                         params_initializers.Add (a.Expr);
4147                                         args.RemoveAt (a_idx--);
4148                                         --arg_count;
4149                                         continue;
4150                                 }
4151
4152                                 // Update the argument with the implicit conversion
4153                                 a.Expr = conv;
4154                         }
4155
4156                         if (a_idx != arg_count) {
4157                                 ReportArgumentMismatch (ec, a_pos, member, a, pd, pt);
4158                                 return false;
4159                         }
4160
4161                         //
4162                         // Fill not provided arguments required by params modifier
4163                         //
4164                         if (params_initializers == null && pd.HasParams && arg_count + 1 == pd.Count) {
4165                                 if (args == null)
4166                                         args = new Arguments (1);
4167
4168                                 pt = pd.Types[pd.Count - 1];
4169                                 pt = TypeManager.GetElementType (pt);
4170                                 has_unsafe_arg |= pt.IsPointer;
4171                                 params_initializers = new ArrayInitializer (0, loc);
4172                         }
4173
4174                         //
4175                         // Append an array argument with all params arguments
4176                         //
4177                         if (params_initializers != null) {
4178                                 args.Add (new Argument (
4179                                         new ArrayCreation (new TypeExpression (pt, loc), params_initializers, loc).Resolve (ec)));
4180                                 arg_count++;
4181                         }
4182
4183                         if (has_unsafe_arg && !ec.IsUnsafe) {
4184                                 Expression.UnsafeError (ec, loc);
4185                         }
4186
4187                         return true;
4188                 }
4189         }
4190
4191         public class ConstantExpr : MemberExpr
4192         {
4193                 ConstSpec constant;
4194
4195                 public ConstantExpr (ConstSpec constant, Location loc)
4196                 {
4197                         this.constant = constant;
4198                         this.loc = loc;
4199                 }
4200
4201                 public override string Name {
4202                         get { throw new NotImplementedException (); }
4203                 }
4204
4205                 public override bool IsInstance {
4206                         get { return !IsStatic; }
4207                 }
4208
4209                 public override bool IsStatic {
4210                         get { return true; }
4211                 }
4212
4213                 protected override TypeSpec DeclaringType {
4214                         get { return constant.DeclaringType; }
4215                 }
4216
4217                 public override Expression CreateExpressionTree (ResolveContext ec)
4218                 {
4219                         throw new NotSupportedException ("ET");
4220                 }
4221
4222                 protected override Expression DoResolve (ResolveContext rc)
4223                 {
4224                         ResolveInstanceExpression (rc);
4225                         DoBestMemberChecks (rc, constant);
4226
4227                         var c = constant.GetConstant (rc);
4228
4229                         // Creates reference expression to the constant value
4230                         return Constant.CreateConstant (rc, constant.MemberType, c.GetValue (), loc);
4231                 }
4232
4233                 public override void Emit (EmitContext ec)
4234                 {
4235                         throw new NotSupportedException ();
4236                 }
4237
4238                 public override string GetSignatureForError ()
4239                 {
4240                         return constant.GetSignatureForError ();
4241                 }
4242
4243                 public override void SetTypeArguments (ResolveContext ec, TypeArguments ta)
4244                 {
4245                         Error_TypeArgumentsCannotBeUsed (ec.Report, "constant", GetSignatureForError (), loc);
4246                 }
4247         }
4248
4249         /// <summary>
4250         ///   Fully resolved expression that evaluates to a Field
4251         /// </summary>
4252         public class FieldExpr : MemberExpr, IDynamicAssign, IMemoryLocation, IVariableReference {
4253                 protected FieldSpec spec;
4254                 VariableInfo variable_info;
4255
4256                 LocalTemporary temp;
4257                 bool prepared;
4258
4259                 protected FieldExpr (Location l)
4260                 {
4261                         loc = l;
4262                 }
4263
4264                 public FieldExpr (FieldSpec spec, Location loc)
4265                 {
4266                         this.spec = spec;
4267                         this.loc = loc;
4268
4269                         type = spec.MemberType;
4270                 }
4271
4272                 public FieldExpr (FieldBase fi, Location l)
4273                         : this (fi.Spec, l)
4274                 {
4275                 }
4276
4277 #region Properties
4278
4279                 public override string Name {
4280                         get {
4281                                 return spec.Name;
4282                         }
4283                 }
4284
4285                 public bool IsHoisted {
4286                         get {
4287                                 IVariableReference hv = InstanceExpression as IVariableReference;
4288                                 return hv != null && hv.IsHoisted;
4289                         }
4290                 }
4291
4292                 public override bool IsInstance {
4293                         get {
4294                                 return !spec.IsStatic;
4295                         }
4296                 }
4297
4298                 public override bool IsStatic {
4299                         get {
4300                                 return spec.IsStatic;
4301                         }
4302                 }
4303
4304                 public FieldSpec Spec {
4305                         get {
4306                                 return spec;
4307                         }
4308                 }
4309
4310                 protected override TypeSpec DeclaringType {
4311                         get {
4312                                 return spec.DeclaringType;
4313                         }
4314                 }
4315
4316                 public VariableInfo VariableInfo {
4317                         get {
4318                                 return variable_info;
4319                         }
4320                 }
4321
4322 #endregion
4323
4324                 public override string GetSignatureForError ()
4325                 {
4326                         return TypeManager.GetFullNameSignature (spec);
4327                 }
4328
4329                 public bool IsMarshalByRefAccess ()
4330                 {
4331                         // Checks possible ldflda of field access expression
4332                         return !spec.IsStatic && TypeManager.IsValueType (spec.MemberType) &&
4333                                 TypeManager.IsSubclassOf (spec.DeclaringType, TypeManager.mbr_type) &&
4334                                 !(InstanceExpression is This);
4335                 }
4336
4337                 public void SetHasAddressTaken ()
4338                 {
4339                         IVariableReference vr = InstanceExpression as IVariableReference;
4340                         if (vr != null)
4341                                 vr.SetHasAddressTaken ();
4342                 }
4343
4344                 public override Expression CreateExpressionTree (ResolveContext ec)
4345                 {
4346                         Expression instance;
4347                         if (InstanceExpression == null) {
4348                                 instance = new NullLiteral (loc);
4349                         } else {
4350                                 instance = InstanceExpression.CreateExpressionTree (ec);
4351                         }
4352
4353                         Arguments args = Arguments.CreateForExpressionTree (ec, null,
4354                                 instance,
4355                                 CreateTypeOfExpression ());
4356
4357                         return CreateExpressionFactoryCall (ec, "Field", args);
4358                 }
4359
4360                 public Expression CreateTypeOfExpression ()
4361                 {
4362                         return new TypeOfField (spec, loc);
4363                 }
4364
4365                 protected override Expression DoResolve (ResolveContext ec)
4366                 {
4367                         return DoResolve (ec, false, false);
4368                 }
4369
4370                 Expression DoResolve (ResolveContext ec, bool lvalue_instance, bool out_access)
4371                 {
4372                         if (ResolveInstanceExpression (ec)) {
4373                                 // Resolve the field's instance expression while flow analysis is turned
4374                                 // off: when accessing a field "a.b", we must check whether the field
4375                                 // "a.b" is initialized, not whether the whole struct "a" is initialized.
4376
4377                                 if (lvalue_instance) {
4378                                         using (ec.With (ResolveContext.Options.DoFlowAnalysis, false)) {
4379                                                 Expression right_side =
4380                                                         out_access ? EmptyExpression.LValueMemberOutAccess : EmptyExpression.LValueMemberAccess;
4381
4382                                                 InstanceExpression = InstanceExpression.ResolveLValue (ec, right_side);
4383                                         }
4384                                 } else {
4385                                         using (ec.With (ResolveContext.Options.DoFlowAnalysis, false)) {
4386                                                 InstanceExpression = InstanceExpression.Resolve (ec, ResolveFlags.VariableOrValue);
4387                                         }
4388                                 }
4389
4390                                 if (InstanceExpression == null)
4391                                         return null;
4392
4393                                 using (ec.Set (ResolveContext.Options.OmitStructFlowAnalysis)) {
4394                                         InstanceExpression.CheckMarshalByRefAccess (ec);
4395                                 }
4396                         }
4397
4398                         DoBestMemberChecks (ec, spec);
4399
4400                         var fb = spec as FixedFieldSpec;
4401                         IVariableReference var = InstanceExpression as IVariableReference;
4402
4403                         if (lvalue_instance && var != null && var.VariableInfo != null) {
4404                                 var.VariableInfo.SetFieldAssigned (ec, Name);
4405                         }
4406
4407                         if (fb != null) {
4408                                 IFixedExpression fe = InstanceExpression as IFixedExpression;
4409                                 if (!ec.HasSet (ResolveContext.Options.FixedInitializerScope) && (fe == null || !fe.IsFixed)) {
4410                                         ec.Report.Error (1666, loc, "You cannot use fixed size buffers contained in unfixed expressions. Try using the fixed statement");
4411                                 }
4412
4413                                 if (InstanceExpression.eclass != ExprClass.Variable) {
4414                                         ec.Report.SymbolRelatedToPreviousError (spec);
4415                                         ec.Report.Error (1708, loc, "`{0}': Fixed size buffers can only be accessed through locals or fields",
4416                                                 TypeManager.GetFullNameSignature (spec));
4417                                 } else if (var != null && var.IsHoisted) {
4418                                         AnonymousMethodExpression.Error_AddressOfCapturedVar (ec, var, loc);
4419                                 }
4420
4421                                 return new FixedBufferPtr (this, fb.ElementType, loc).Resolve (ec);
4422                         }
4423
4424                         eclass = ExprClass.Variable;
4425
4426                         // If the instance expression is a local variable or parameter.
4427                         if (var == null || var.VariableInfo == null)
4428                                 return this;
4429
4430                         VariableInfo vi = var.VariableInfo;
4431                         if (!vi.IsFieldAssigned (ec, Name, loc))
4432                                 return null;
4433
4434                         variable_info = vi.GetSubStruct (Name);
4435                         return this;
4436                 }
4437
4438                 static readonly int [] codes = {
4439                         191,    // instance, write access
4440                         192,    // instance, out access
4441                         198,    // static, write access
4442                         199,    // static, out access
4443                         1648,   // member of value instance, write access
4444                         1649,   // member of value instance, out access
4445                         1650,   // member of value static, write access
4446                         1651    // member of value static, out access
4447                 };
4448
4449                 static readonly string [] msgs = {
4450                         /*0191*/ "A readonly field `{0}' cannot be assigned to (except in a constructor or a variable initializer)",
4451                         /*0192*/ "A readonly field `{0}' cannot be passed ref or out (except in a constructor)",
4452                         /*0198*/ "A static readonly field `{0}' cannot be assigned to (except in a static constructor or a variable initializer)",
4453                         /*0199*/ "A static readonly field `{0}' cannot be passed ref or out (except in a static constructor)",
4454                         /*1648*/ "Members of readonly field `{0}' cannot be modified (except in a constructor or a variable initializer)",
4455                         /*1649*/ "Members of readonly field `{0}' cannot be passed ref or out (except in a constructor)",
4456                         /*1650*/ "Fields of static readonly field `{0}' cannot be assigned to (except in a static constructor or a variable initializer)",
4457                         /*1651*/ "Fields of static readonly field `{0}' cannot be passed ref or out (except in a static constructor)"
4458                 };
4459
4460                 // The return value is always null.  Returning a value simplifies calling code.
4461                 Expression Report_AssignToReadonly (ResolveContext ec, Expression right_side)
4462                 {
4463                         int i = 0;
4464                         if (right_side == EmptyExpression.OutAccess.Instance || right_side == EmptyExpression.LValueMemberOutAccess)
4465                                 i += 1;
4466                         if (IsStatic)
4467                                 i += 2;
4468                         if (right_side == EmptyExpression.LValueMemberAccess || right_side == EmptyExpression.LValueMemberOutAccess)
4469                                 i += 4;
4470                         ec.Report.Error (codes [i], loc, msgs [i], GetSignatureForError ());
4471
4472                         return null;
4473                 }
4474
4475                 override public Expression DoResolveLValue (ResolveContext ec, Expression right_side)
4476                 {
4477                         bool lvalue_instance = IsInstance && spec.DeclaringType.IsStruct;
4478                         bool out_access = right_side == EmptyExpression.OutAccess.Instance || right_side == EmptyExpression.LValueMemberOutAccess;
4479
4480                         Expression e = DoResolve (ec, lvalue_instance, out_access);
4481
4482                         if (e == null)
4483                                 return null;
4484
4485                         spec.MemberDefinition.SetIsAssigned ();
4486
4487                         if ((right_side == EmptyExpression.UnaryAddress || right_side == EmptyExpression.OutAccess.Instance) &&
4488                                         (spec.Modifiers & Modifiers.VOLATILE) != 0) {
4489                                 ec.Report.Warning (420, 1, loc,
4490                                         "`{0}': A volatile field references will not be treated as volatile",
4491                                         spec.GetSignatureForError ());
4492                         }
4493
4494                         if (spec.IsReadOnly) {
4495                                 // InitOnly fields can only be assigned in constructors or initializers
4496                                 if (!ec.HasAny (ResolveContext.Options.FieldInitializerScope | ResolveContext.Options.ConstructorScope))
4497                                         return Report_AssignToReadonly (ec, right_side);
4498
4499                                 if (ec.HasSet (ResolveContext.Options.ConstructorScope)) {
4500
4501                                         // InitOnly fields cannot be assigned-to in a different constructor from their declaring type
4502                                         if (!TypeManager.IsEqual (ec.CurrentMemberDefinition.Parent.Definition, spec.DeclaringType.GetDefinition ()))
4503                                                 return Report_AssignToReadonly (ec, right_side);
4504                                         // static InitOnly fields cannot be assigned-to in an instance constructor
4505                                         if (IsStatic && !ec.IsStatic)
4506                                                 return Report_AssignToReadonly (ec, right_side);
4507                                         // instance constructors can't modify InitOnly fields of other instances of the same type
4508                                         if (!IsStatic && !(InstanceExpression is This))
4509                                                 return Report_AssignToReadonly (ec, right_side);
4510                                 }
4511                         }
4512
4513                         if (right_side == EmptyExpression.OutAccess.Instance &&
4514                             !IsStatic && !(InstanceExpression is This) && TypeManager.mbr_type != null && TypeManager.IsSubclassOf (spec.DeclaringType, TypeManager.mbr_type)) {
4515                                 ec.Report.SymbolRelatedToPreviousError (spec.DeclaringType);
4516                                 ec.Report.Warning (197, 1, loc,
4517                                                 "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",
4518                                                 GetSignatureForError ());
4519                         }
4520
4521                         eclass = ExprClass.Variable;
4522                         return this;
4523                 }
4524
4525                 public override int GetHashCode ()
4526                 {
4527                         return spec.GetHashCode ();
4528                 }
4529
4530                 public bool IsFixed {
4531                         get {
4532                                 //
4533                                 // A variable of the form V.I is fixed when V is a fixed variable of a struct type
4534                                 //
4535                                 IVariableReference variable = InstanceExpression as IVariableReference;
4536                                 if (variable != null)
4537                                         return InstanceExpression.Type.IsStruct && variable.IsFixed;
4538
4539                                 IFixedExpression fe = InstanceExpression as IFixedExpression;
4540                                 return fe != null && fe.IsFixed;
4541                         }
4542                 }
4543
4544                 public override bool Equals (object obj)
4545                 {
4546                         FieldExpr fe = obj as FieldExpr;
4547                         if (fe == null)
4548                                 return false;
4549
4550                         if (spec != fe.spec)
4551                                 return false;
4552
4553                         if (InstanceExpression == null || fe.InstanceExpression == null)
4554                                 return true;
4555
4556                         return InstanceExpression.Equals (fe.InstanceExpression);
4557                 }
4558
4559                 public void Emit (EmitContext ec, bool leave_copy)
4560                 {
4561                         bool is_volatile = false;
4562
4563                         if ((spec.Modifiers & Modifiers.VOLATILE) != 0)
4564                                 is_volatile = true;
4565
4566                         spec.MemberDefinition.SetIsUsed ();
4567
4568                         if (IsStatic){
4569                                 if (is_volatile)
4570                                         ec.Emit (OpCodes.Volatile);
4571
4572                                 ec.Emit (OpCodes.Ldsfld, spec);
4573                         } else {
4574                                 if (!prepared)
4575                                         EmitInstance (ec, false);
4576
4577                                 // Optimization for build-in types
4578                                 if (TypeManager.IsStruct (type) && TypeManager.IsEqual (type, ec.MemberContext.CurrentType) && TypeManager.IsEqual (InstanceExpression.Type, type)) {
4579                                         ec.EmitLoadFromPtr (type);
4580                                 } else {
4581                                         var ff = spec as FixedFieldSpec;
4582                                         if (ff != null) {
4583                                                 ec.Emit (OpCodes.Ldflda, spec);
4584                                                 ec.Emit (OpCodes.Ldflda, ff.Element);
4585                                         } else {
4586                                                 if (is_volatile)
4587                                                         ec.Emit (OpCodes.Volatile);
4588
4589                                                 ec.Emit (OpCodes.Ldfld, spec);
4590                                         }
4591                                 }
4592                         }
4593
4594                         if (leave_copy) {
4595                                 ec.Emit (OpCodes.Dup);
4596                                 if (!IsStatic) {
4597                                         temp = new LocalTemporary (this.Type);
4598                                         temp.Store (ec);
4599                                 }
4600                         }
4601                 }
4602
4603                 public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool prepare_for_load)
4604                 {
4605                         prepared = prepare_for_load;
4606                         if (IsInstance)
4607                                 EmitInstance (ec, prepared);
4608
4609                         source.Emit (ec);
4610                         if (leave_copy) {
4611                                 ec.Emit (OpCodes.Dup);
4612                                 if (!IsStatic) {
4613                                         temp = new LocalTemporary (this.Type);
4614                                         temp.Store (ec);
4615                                 }
4616                         }
4617
4618                         if ((spec.Modifiers & Modifiers.VOLATILE) != 0)
4619                                 ec.Emit (OpCodes.Volatile);
4620
4621                         spec.MemberDefinition.SetIsAssigned ();
4622
4623                         if (IsStatic)
4624                                 ec.Emit (OpCodes.Stsfld, spec);
4625                         else
4626                                 ec.Emit (OpCodes.Stfld, spec);
4627
4628                         if (temp != null) {
4629                                 temp.Emit (ec);
4630                                 temp.Release (ec);
4631                                 temp = null;
4632                         }
4633                 }
4634
4635                 public override void Emit (EmitContext ec)
4636                 {
4637                         Emit (ec, false);
4638                 }
4639
4640                 public override void EmitSideEffect (EmitContext ec)
4641                 {
4642                         bool is_volatile = (spec.Modifiers & Modifiers.VOLATILE) != 0;
4643
4644                         if (is_volatile) // || is_marshal_by_ref ())
4645                                 base.EmitSideEffect (ec);
4646                 }
4647
4648                 public override void Error_VariableIsUsedBeforeItIsDeclared (Report r, string name)
4649                 {
4650                         r.Error (844, loc,
4651                                 "A local variable `{0}' cannot be used before it is declared. Consider renaming the local variable when it hides the field `{1}'",
4652                                 name, GetSignatureForError ());
4653                 }
4654
4655                 public void AddressOf (EmitContext ec, AddressOp mode)
4656                 {
4657                         if ((mode & AddressOp.Store) != 0)
4658                                 spec.MemberDefinition.SetIsAssigned ();
4659                         if ((mode & AddressOp.Load) != 0)
4660                                 spec.MemberDefinition.SetIsUsed ();
4661
4662                         //
4663                         // Handle initonly fields specially: make a copy and then
4664                         // get the address of the copy.
4665                         //
4666                         bool need_copy;
4667                         if (spec.IsReadOnly){
4668                                 need_copy = true;
4669                                 if (ec.HasSet (EmitContext.Options.ConstructorScope)){
4670                                         if (IsStatic){
4671                                                 if (ec.IsStatic)
4672                                                         need_copy = false;
4673                                         } else
4674                                                 need_copy = false;
4675                                 }
4676                         } else
4677                                 need_copy = false;
4678
4679                         if (need_copy){
4680                                 LocalBuilder local;
4681                                 Emit (ec);
4682                                 local = ec.DeclareLocal (type, false);
4683                                 ec.Emit (OpCodes.Stloc, local);
4684                                 ec.Emit (OpCodes.Ldloca, local);
4685                                 return;
4686                         }
4687
4688
4689                         if (IsStatic){
4690                                 ec.Emit (OpCodes.Ldsflda, spec);
4691                         } else {
4692                                 if (!prepared)
4693                                         EmitInstance (ec, false);
4694                                 ec.Emit (OpCodes.Ldflda, spec);
4695                         }
4696                 }
4697
4698                 public SLE.Expression MakeAssignExpression (BuilderContext ctx, Expression source)
4699                 {
4700                         return MakeExpression (ctx);
4701                 }
4702
4703                 public override SLE.Expression MakeExpression (BuilderContext ctx)
4704                 {
4705                         return SLE.Expression.Field (InstanceExpression.MakeExpression (ctx), spec.GetMetaInfo ());
4706                 }
4707
4708                 public override void SetTypeArguments (ResolveContext ec, TypeArguments ta)
4709                 {
4710                         Error_TypeArgumentsCannotBeUsed (ec.Report, "field", GetSignatureForError (), loc);
4711                 }
4712         }
4713
4714
4715         /// <summary>
4716         ///   Expression that evaluates to a Property.  The Assign class
4717         ///   might set the `Value' expression if we are in an assignment.
4718         ///
4719         ///   This is not an LValue because we need to re-write the expression, we
4720         ///   can not take data from the stack and store it.
4721         /// </summary>
4722         class PropertyExpr : PropertyOrIndexerExpr<PropertySpec>
4723         {
4724                 public PropertyExpr (PropertySpec spec, Location l)
4725                         : base (l)
4726                 {
4727                         best_candidate = spec;
4728                         type = spec.MemberType;
4729                 }
4730
4731                 #region Properties
4732
4733                 protected override TypeSpec DeclaringType {
4734                         get {
4735                                 return best_candidate.DeclaringType;
4736                         }
4737                 }
4738
4739                 public override string Name {
4740                         get {
4741                                 return best_candidate.Name;
4742                         }
4743                 }
4744
4745                 public override bool IsInstance {
4746                         get {
4747                                 return !IsStatic;
4748                         }
4749                 }
4750
4751                 public override bool IsStatic {
4752                         get {
4753                                 return best_candidate.IsStatic;
4754                         }
4755                 }
4756
4757                 public PropertySpec PropertyInfo {
4758                         get {
4759                                 return best_candidate;
4760                         }
4761                 }
4762
4763                 #endregion
4764
4765                 public override Expression CreateExpressionTree (ResolveContext ec)
4766                 {
4767                         Arguments args;
4768                         if (IsSingleDimensionalArrayLength ()) {
4769                                 args = new Arguments (1);
4770                                 args.Add (new Argument (InstanceExpression.CreateExpressionTree (ec)));
4771                                 return CreateExpressionFactoryCall (ec, "ArrayLength", args);
4772                         }
4773
4774                         args = new Arguments (2);
4775                         if (InstanceExpression == null)
4776                                 args.Add (new Argument (new NullLiteral (loc)));
4777                         else
4778                                 args.Add (new Argument (InstanceExpression.CreateExpressionTree (ec)));
4779                         args.Add (new Argument (new TypeOfMethod (Getter, loc)));
4780                         return CreateExpressionFactoryCall (ec, "Property", args);
4781                 }
4782
4783                 public Expression CreateSetterTypeOfExpression ()
4784                 {
4785                         return new TypeOfMethod (Setter, loc);
4786                 }
4787
4788                 public override string GetSignatureForError ()
4789                 {
4790                         return best_candidate.GetSignatureForError ();
4791                 }
4792
4793                 public override SLE.Expression MakeAssignExpression (BuilderContext ctx, Expression source)
4794                 {
4795                         return SLE.Expression.Property (InstanceExpression.MakeExpression (ctx), (MethodInfo) Setter.GetMetaInfo ());
4796                 }
4797
4798                 public override SLE.Expression MakeExpression (BuilderContext ctx)
4799                 {
4800                         return SLE.Expression.Property (InstanceExpression.MakeExpression (ctx), (MethodInfo) Getter.GetMetaInfo ());
4801                 }
4802
4803                 void Error_PropertyNotValid (ResolveContext ec)
4804                 {
4805                         ec.Report.SymbolRelatedToPreviousError (best_candidate);
4806                         ec.Report.Error (1546, loc, "Property or event `{0}' is not supported by the C# language",
4807                                 GetSignatureForError ());
4808                 }
4809
4810                 bool IsSingleDimensionalArrayLength ()
4811                 {
4812                         if (best_candidate.DeclaringType != TypeManager.array_type || !best_candidate.HasGet || Name != "Length")
4813                                 return false;
4814
4815                         ArrayContainer ac = InstanceExpression.Type as ArrayContainer;
4816                         return ac != null && ac.Rank == 1;
4817                 }
4818
4819                 public override void Emit (EmitContext ec, bool leave_copy)
4820                 {
4821                         //
4822                         // Special case: length of single dimension array property is turned into ldlen
4823                         //
4824                         if (IsSingleDimensionalArrayLength ()) {
4825                                 if (!prepared)
4826                                         EmitInstance (ec, false);
4827                                 ec.Emit (OpCodes.Ldlen);
4828                                 ec.Emit (OpCodes.Conv_I4);
4829                                 return;
4830                         }
4831
4832                         Invocation.EmitCall (ec, InstanceExpression, Getter, null, loc, prepared, false);
4833
4834                         if (leave_copy) {
4835                                 ec.Emit (OpCodes.Dup);
4836                                 if (!IsStatic) {
4837                                         temp = new LocalTemporary (this.Type);
4838                                         temp.Store (ec);
4839                                 }
4840                         }
4841                 }
4842
4843                 public override void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool prepare_for_load)
4844                 {
4845                         Expression my_source = source;
4846
4847                         if (prepare_for_load) {
4848                                 prepared = true;
4849                                 source.Emit (ec);
4850
4851                                 if (leave_copy) {
4852                                         ec.Emit (OpCodes.Dup);
4853                                         if (!IsStatic) {
4854                                                 temp = new LocalTemporary (this.Type);
4855                                                 temp.Store (ec);
4856                                         }
4857                                 }
4858                         } else if (leave_copy) {
4859                                 source.Emit (ec);
4860                                 temp = new LocalTemporary (this.Type);
4861                                 temp.Store (ec);
4862                                 my_source = temp;
4863                         }
4864
4865                         Arguments args = new Arguments (1);
4866                         args.Add (new Argument (my_source));
4867
4868                         Invocation.EmitCall (ec, InstanceExpression, Setter, args, loc, false, prepared);
4869
4870                         if (temp != null) {
4871                                 temp.Emit (ec);
4872                                 temp.Release (ec);
4873                         }
4874                 }
4875
4876                 protected override Expression OverloadResolve (ResolveContext rc, Expression right_side)
4877                 {
4878                         eclass = ExprClass.PropertyAccess;
4879
4880                         if (best_candidate.IsNotRealProperty) {
4881                                 Error_PropertyNotValid (rc);
4882                         }
4883
4884                         if (ResolveInstanceExpression (rc)) {
4885                                 if (right_side != null && best_candidate.DeclaringType.IsStruct)
4886                                         InstanceExpression.DoResolveLValue (rc, EmptyExpression.LValueMemberAccess);
4887                         }
4888
4889                         DoBestMemberChecks (rc, best_candidate);
4890                         return this;
4891                 }
4892
4893                 public override void SetTypeArguments (ResolveContext ec, TypeArguments ta)
4894                 {
4895                         Error_TypeArgumentsCannotBeUsed (ec.Report, "property", GetSignatureForError (), loc);
4896                 }
4897         }
4898
4899         abstract class PropertyOrIndexerExpr<T> : MemberExpr, IDynamicAssign where T : PropertySpec
4900         {
4901                 // getter and setter can be different for base calls
4902                 MethodSpec getter, setter;
4903                 protected T best_candidate;
4904
4905                 protected LocalTemporary temp;
4906                 protected bool prepared;
4907
4908                 protected PropertyOrIndexerExpr (Location l)
4909                 {
4910                         loc = l;
4911                 }
4912
4913                 #region Properties
4914
4915                 public MethodSpec Getter {
4916                         get {
4917                                 return getter;
4918                         }
4919                         set {
4920                                 getter = value;
4921                         }
4922                 }
4923
4924                 public MethodSpec Setter {
4925                         get {
4926                                 return setter;
4927                         }
4928                         set {
4929                                 setter = value;
4930                         }
4931                 }
4932
4933                 #endregion
4934
4935                 protected override Expression DoResolve (ResolveContext ec)
4936                 {
4937                         if (eclass == ExprClass.Unresolved) {
4938                                 var expr = OverloadResolve (ec, null);
4939                                 if (expr == null)
4940                                         return null;
4941
4942                                 if (InstanceExpression != null)
4943                                         InstanceExpression.CheckMarshalByRefAccess (ec);
4944
4945                                 if (expr != this)
4946                                         return expr.Resolve (ec);
4947                         }
4948
4949                         if (!ResolveGetter (ec))
4950                                 return null;
4951
4952                         return this;
4953                 }
4954
4955                 public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
4956                 {
4957                         if (right_side == EmptyExpression.OutAccess.Instance) {
4958                                 // TODO: best_candidate can be null at this point
4959                                 if (best_candidate != null && ec.CurrentBlock.Toplevel.GetParameterReference (best_candidate.Name, loc) is MemberAccess) {
4960                                         ec.Report.Error (1939, loc, "A range variable `{0}' may not be passes as `ref' or `out' parameter",
4961                                                 best_candidate.Name);
4962                                 } else {
4963                                         right_side.DoResolveLValue (ec, this);
4964                                 }
4965                                 return null;
4966                         }
4967
4968                         // if the property/indexer returns a value type, and we try to set a field in it
4969                         if (right_side == EmptyExpression.LValueMemberAccess || right_side == EmptyExpression.LValueMemberOutAccess) {
4970                                 Error_CannotModifyIntermediateExpressionValue (ec);
4971                         }
4972
4973                         if (eclass == ExprClass.Unresolved) {
4974                                 var expr = OverloadResolve (ec, right_side);
4975                                 if (expr == null)
4976                                         return null;
4977
4978                                 if (expr != this)
4979                                         return expr.ResolveLValue (ec, right_side);
4980                         }
4981
4982                         if (!ResolveSetter (ec))
4983                                 return null;
4984
4985                         return this;
4986                 }
4987
4988                 //
4989                 // Implements the IAssignMethod interface for assignments
4990                 //
4991                 public abstract void Emit (EmitContext ec, bool leave_copy);
4992                 public abstract void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool prepare_for_load);
4993
4994                 public override void Emit (EmitContext ec)
4995                 {
4996                         Emit (ec, false);
4997                 }
4998
4999                 public abstract SLE.Expression MakeAssignExpression (BuilderContext ctx, Expression source);
5000
5001                 protected abstract Expression OverloadResolve (ResolveContext rc, Expression right_side);
5002
5003                 bool ResolveGetter (ResolveContext rc)
5004                 {
5005                         if (!best_candidate.HasGet) {
5006                                 if (InstanceExpression != EmptyExpression.Null) {
5007                                         rc.Report.SymbolRelatedToPreviousError (best_candidate);
5008                                         rc.Report.Error (154, loc, "The property or indexer `{0}' cannot be used in this context because it lacks the `get' accessor",
5009                                                 best_candidate.GetSignatureForError ());
5010                                         return false;
5011                                 }
5012                         } else if (!best_candidate.Get.IsAccessible (rc.CurrentType)) {
5013                                 if (best_candidate.HasDifferentAccessibility) {
5014                                         rc.Report.SymbolRelatedToPreviousError (best_candidate.Get);
5015                                         rc.Report.Error (271, loc, "The property or indexer `{0}' cannot be used in this context because the get accessor is inaccessible",
5016                                                 TypeManager.CSharpSignature (best_candidate));
5017                                 } else {
5018                                         rc.Report.SymbolRelatedToPreviousError (best_candidate.Get);
5019                                         ErrorIsInaccesible (rc, best_candidate.Get.GetSignatureForError (), loc);
5020                                 }
5021                         }
5022
5023                         if (best_candidate.HasDifferentAccessibility) {
5024                                 CheckProtectedMemberAccess (rc, best_candidate.Get);
5025                         }
5026
5027                         getter = CandidateToBaseOverride (rc, best_candidate.Get);
5028                         return true;
5029                 }
5030
5031                 bool ResolveSetter (ResolveContext rc)
5032                 {
5033                         if (!best_candidate.HasSet) {
5034                                 if (rc.CurrentBlock.Toplevel.GetParameterReference (best_candidate.Name, loc) is MemberAccess) {
5035                                         rc.Report.Error (1947, loc, "A range variable `{0}' cannot be assigned to. Consider using `let' clause to store the value",
5036                                                 best_candidate.Name);
5037                                 } else {
5038                                         rc.Report.Error (200, loc, "Property or indexer `{0}' cannot be assigned to (it is read-only)",
5039                                                 GetSignatureForError ());
5040                                 }
5041                                 return false;
5042                         }
5043
5044                         if (!best_candidate.Set.IsAccessible (rc.CurrentType)) {
5045                                 if (best_candidate.HasDifferentAccessibility) {
5046                                         rc.Report.SymbolRelatedToPreviousError (best_candidate.Set);
5047                                         rc.Report.Error (272, loc, "The property or indexer `{0}' cannot be used in this context because the set accessor is inaccessible",
5048                                                 GetSignatureForError ());
5049                                 } else {
5050                                         rc.Report.SymbolRelatedToPreviousError (best_candidate.Set);
5051                                         ErrorIsInaccesible (rc, best_candidate.Set.GetSignatureForError (), loc);
5052                                 }
5053                         }
5054
5055                         if (best_candidate.HasDifferentAccessibility)
5056                                 CheckProtectedMemberAccess (rc, best_candidate.Set);
5057
5058                         setter = CandidateToBaseOverride (rc, best_candidate.Set);
5059                         return true;
5060                 }
5061         }
5062
5063         /// <summary>
5064         ///   Fully resolved expression that evaluates to an Event
5065         /// </summary>
5066         public class EventExpr : MemberExpr
5067         {
5068                 readonly EventSpec spec;
5069
5070                 public EventExpr (EventSpec spec, Location loc)
5071                 {
5072                         this.spec = spec;
5073                         this.loc = loc;
5074                 }
5075
5076                 public override string Name {
5077                         get {
5078                                 return spec.Name;
5079                         }
5080                 }
5081
5082                 public override bool IsInstance {
5083                         get {
5084                                 return !spec.IsStatic;
5085                         }
5086                 }
5087
5088                 public override bool IsStatic {
5089                         get {
5090                                 return spec.IsStatic;
5091                         }
5092                 }
5093
5094                 protected override TypeSpec DeclaringType {
5095                         get {
5096                                 return spec.DeclaringType;
5097                         }
5098                 }
5099
5100                 public void Error_AssignmentEventOnly (ResolveContext ec)
5101                 {
5102                         ec.Report.Error (79, loc, "The event `{0}' can only appear on the left hand side of `+=' or `-=' operator",
5103                                 GetSignatureForError ());
5104                 }
5105
5106                 public override MemberExpr ResolveMemberAccess (ResolveContext ec, Expression left, SimpleName original)
5107                 {
5108                         //
5109                         // If the event is local to this class, we transform ourselves into a FieldExpr
5110                         //
5111
5112                         if (spec.DeclaringType == ec.CurrentType ||
5113                             TypeManager.IsNestedChildOf(ec.CurrentType, spec.DeclaringType)) {
5114
5115                                 // TODO: Breaks dynamic binder as currect context fields are imported and not compiled
5116                                 // EventField mi = spec.MemberDefinition as EventField;
5117
5118                                 if (spec.BackingField != null) {
5119                                         spec.MemberDefinition.SetIsUsed ();
5120
5121                                         if (!ec.IsObsolete) {
5122                                                 ObsoleteAttribute oa = spec.GetAttributeObsolete ();
5123                                                 if (oa != null)
5124                                                         AttributeTester.Report_ObsoleteMessage (oa, spec.GetSignatureForError (), loc, ec.Report);
5125                                         }
5126
5127                                         if ((spec.Modifiers & (Modifiers.ABSTRACT | Modifiers.EXTERN)) != 0 && !ec.HasSet (ResolveContext.Options.CompoundAssignmentScope))
5128                                                 Error_AssignmentEventOnly (ec);
5129
5130                                         FieldExpr ml = new FieldExpr (spec.BackingField, loc);
5131
5132                                         InstanceExpression = null;
5133
5134                                         return ml.ResolveMemberAccess (ec, left, original);
5135                                 }
5136                         }
5137
5138                         if (!ec.HasSet (ResolveContext.Options.CompoundAssignmentScope))
5139                                 Error_AssignmentEventOnly (ec);
5140
5141                         return base.ResolveMemberAccess (ec, left, original);
5142                 }
5143
5144                 public override Expression CreateExpressionTree (ResolveContext ec)
5145                 {
5146                         throw new NotSupportedException ("ET");
5147                 }
5148
5149                 public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
5150                 {
5151                         // contexts where an LValue is valid have already devolved to FieldExprs
5152                         Error_CannotAssign (ec);
5153                         return null;
5154                 }
5155
5156                 protected override Expression DoResolve (ResolveContext ec)
5157                 {
5158                         eclass = ExprClass.EventAccess;
5159                         type = spec.MemberType;
5160 /*
5161                         if (!spec.IsAccessible (ec.CurrentType)) {
5162                                 ec.Report.SymbolRelatedToPreviousError (spec);
5163                                 ErrorIsInaccesible (loc, TypeManager.CSharpSignature (spec), ec.Report);
5164                         }
5165 */
5166                         if (IsBase && spec.IsAbstract) {
5167                                 Error_CannotCallAbstractBase (ec, GetSignatureForError ());
5168                         }
5169
5170                         ResolveInstanceExpression (ec);
5171
5172                         if (!ec.HasSet (ResolveContext.Options.CompoundAssignmentScope)) {
5173                                 Error_CannotAssign (ec);
5174                         }
5175
5176                         DoBestMemberChecks (ec, spec);
5177                         return this;
5178                 }
5179
5180                 public override void Emit (EmitContext ec)
5181                 {
5182                         throw new NotSupportedException ();
5183                         //Error_CannotAssign ();
5184                 }
5185
5186                 public void Error_CannotAssign (ResolveContext ec)
5187                 {
5188                         ec.Report.Error (70, loc,
5189                                 "The event `{0}' can only appear on the left hand side of += or -= when used outside of the type `{1}'",
5190                                 GetSignatureForError (), TypeManager.CSharpName (spec.DeclaringType));
5191                 }
5192
5193                 public override string GetSignatureForError ()
5194                 {
5195                         return TypeManager.CSharpSignature (spec);
5196                 }
5197
5198                 public void EmitAddOrRemove (EmitContext ec, bool is_add, Expression source)
5199                 {
5200                         Arguments args = new Arguments (1);
5201                         args.Add (new Argument (source));
5202                         Invocation.EmitCall (ec, InstanceExpression, is_add ? spec.AccessorAdd : spec.AccessorRemove, args, loc);
5203                 }
5204
5205                 public override void SetTypeArguments (ResolveContext ec, TypeArguments ta)
5206                 {
5207                         Error_TypeArgumentsCannotBeUsed (ec.Report, "event", GetSignatureForError (), loc);
5208                 }
5209         }
5210
5211         public class TemporaryVariable : VariableReference
5212         {
5213                 LocalInfo li;
5214
5215                 public TemporaryVariable (TypeSpec type, Location loc)
5216                 {
5217                         this.type = type;
5218                         this.loc = loc;
5219                 }
5220
5221                 public override Expression CreateExpressionTree (ResolveContext ec)
5222                 {
5223                         throw new NotSupportedException ("ET");
5224                 }
5225
5226                 protected override Expression DoResolve (ResolveContext ec)
5227                 {
5228                         eclass = ExprClass.Variable;
5229
5230                         TypeExpr te = new TypeExpression (type, loc);
5231                         li = ec.CurrentBlock.AddTemporaryVariable (te, loc);
5232                         if (!li.Resolve (ec))
5233                                 return null;
5234
5235                         //
5236                         // Don't capture temporary variables except when using
5237                         // iterator redirection
5238                         //
5239                         if (ec.CurrentAnonymousMethod != null && ec.CurrentAnonymousMethod.IsIterator && ec.IsVariableCapturingRequired) {
5240                                 AnonymousMethodStorey storey = li.Block.Explicit.CreateAnonymousMethodStorey (ec);
5241                                 storey.CaptureLocalVariable (ec, li);
5242                         }
5243
5244                         return this;
5245                 }
5246
5247                 public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
5248                 {
5249                         return Resolve (ec);
5250                 }
5251
5252                 public override void Emit (EmitContext ec)
5253                 {
5254                         Emit (ec, false);
5255                 }
5256
5257                 public void EmitAssign (EmitContext ec, Expression source)
5258                 {
5259                         EmitAssign (ec, source, false, false);
5260                 }
5261
5262                 public override HoistedVariable GetHoistedVariable (AnonymousExpression ae)
5263                 {
5264                         return li.HoistedVariant;
5265                 }
5266
5267                 public override bool IsFixed {
5268                         get { return true; }
5269                 }
5270
5271                 public override bool IsRef {
5272                         get { return false; }
5273                 }
5274
5275                 public override string Name {
5276                         get { throw new NotImplementedException (); }
5277                 }
5278
5279                 public override void SetHasAddressTaken ()
5280                 {
5281                         throw new NotImplementedException ();
5282                 }
5283
5284                 protected override ILocalVariable Variable {
5285                         get { return li; }
5286                 }
5287
5288                 public override VariableInfo VariableInfo {
5289                         get { throw new NotImplementedException (); }
5290                 }
5291         }
5292
5293         ///
5294         /// Handles `var' contextual keyword; var becomes a keyword only
5295         /// if no type called var exists in a variable scope
5296         ///
5297         class VarExpr : SimpleName
5298         {
5299                 // Used for error reporting only
5300                 int initializers_count;
5301
5302                 public VarExpr (Location loc)
5303                         : base ("var", loc)
5304                 {
5305                         initializers_count = 1;
5306                 }
5307
5308                 public int VariableInitializersCount {
5309                         set {
5310                                 this.initializers_count = value;
5311                         }
5312                 }
5313
5314                 public bool InferType (ResolveContext ec, Expression right_side)
5315                 {
5316                         if (type != null)
5317                                 throw new InternalErrorException ("An implicitly typed local variable could not be redefined");
5318
5319                         type = right_side.Type;
5320                         if (type == TypeManager.null_type || type == TypeManager.void_type || type == InternalType.AnonymousMethod || type == InternalType.MethodGroup) {
5321                                 ec.Report.Error (815, loc,
5322                                         "An implicitly typed local variable declaration cannot be initialized with `{0}'",
5323                                         type.GetSignatureForError ());
5324                                 return false;
5325                         }
5326
5327                         eclass = ExprClass.Variable;
5328                         return true;
5329                 }
5330
5331                 protected override void Error_TypeOrNamespaceNotFound (IMemberContext ec)
5332                 {
5333                         if (RootContext.Version < LanguageVersion.V_3)
5334                                 base.Error_TypeOrNamespaceNotFound (ec);
5335                         else
5336                                 ec.Compiler.Report.Error (825, loc, "The contextual keyword `var' may only appear within a local variable declaration");
5337                 }
5338
5339                 public override TypeExpr ResolveAsContextualType (IMemberContext rc, bool silent)
5340                 {
5341                         TypeExpr te = base.ResolveAsContextualType (rc, true);
5342                         if (te != null)
5343                                 return te;
5344
5345                         if (RootContext.Version < LanguageVersion.V_3)
5346                                 rc.Compiler.Report.FeatureIsNotAvailable (loc, "implicitly typed local variable");
5347
5348                         if (initializers_count == 1)
5349                                 return null;
5350
5351                         if (initializers_count > 1) {
5352                                 rc.Compiler.Report.Error (819, loc, "An implicitly typed local variable declaration cannot include multiple declarators");
5353                                 initializers_count = 1;
5354                                 return null;
5355                         }
5356
5357                         if (initializers_count == 0) {
5358                                 initializers_count = 1;
5359                                 rc.Compiler.Report.Error (818, loc, "An implicitly typed local variable declarator must include an initializer");
5360                                 return null;
5361                         }
5362
5363                         return null;
5364                 }
5365         }
5366 }