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