mcs/mcs/ecore.cs

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