mcs/mcs/ecore.cs

   1 //
   2 // ecore.cs: Core of the Expression representation for the intermediate tree.
   3 //
   4 // Author:
   5 //   Miguel de Icaza (miguel@ximian.com)
   6 //   Marek Safar (marek.safar@seznam.cz)
   7 //
   8 // Copyright 2001, 2002, 2003 Ximian, Inc.
   9 // Copyright 2003-2008 Novell, Inc.
  10 // Copyright 2011 Xamarin Inc.
  11 //
  12 //
  13
  14 using System;
  15 using System.Collections.Generic;
  16 using System.Text;
  17 using SLE = System.Linq.Expressions;
  18 using System.Linq;
  19
  20 #if STATIC
  21 using IKVM.Reflection;
  22 using IKVM.Reflection.Emit;
  23 #else
  24 using System.Reflection;
  25 using System.Reflection.Emit;
  26 #endif
  27
  28 namespace Mono.CSharp {
  29
  30         /// <remarks>
  31         ///   The ExprClass class contains the is used to pass the
  32         ///   classification of an expression (value, variable, namespace,
  33         ///   type, method group, property access, event access, indexer access,
  34         ///   nothing).
  35         /// </remarks>
  36         public enum ExprClass : byte {
  37                 Unresolved      = 0,
  38
  39                 Value,
  40                 Variable,
  41                 Namespace,
  42                 Type,
  43                 TypeParameter,
  44                 MethodGroup,
  45                 PropertyAccess,
  46                 EventAccess,
  47                 IndexerAccess,
  48                 Nothing,
  49         }
  50
  51         /// <remarks>
  52         ///   This is used to tell Resolve in which types of expressions we're
  53         ///   interested.
  54         /// </remarks>
  55         [Flags]
  56         public enum ResolveFlags {
  57                 // Returns Value, Variable, PropertyAccess, EventAccess or IndexerAccess.
  58                 VariableOrValue         = 1,
  59
  60                 // Returns a type expression.
  61                 Type                    = 1 << 1,
  62
  63                 // Returns a method group.
  64                 MethodGroup             = 1 << 2,
  65
  66                 TypeParameter   = 1 << 3,
  67
  68                 // Mask of all the expression class flags.
  69                 MaskExprClass = VariableOrValue | Type | MethodGroup | TypeParameter,
  70         }
  71
  72         //
  73         // This is just as a hint to AddressOf of what will be done with the
  74         // address.
  75         [Flags]
  76         public enum AddressOp {
  77                 Store = 1,
  78                 Load  = 2,
  79                 LoadStore = 3
  80         };
  81
  82         /// <summary>
  83         ///   This interface is implemented by variables
  84         /// </summary>
  85         public interface IMemoryLocation {
  86                 /// <summary>
  87                 ///   The AddressOf method should generate code that loads
  88                 ///   the address of the object and leaves it on the stack.
  89                 ///
  90                 ///   The `mode' argument is used to notify the expression
  91                 ///   of whether this will be used to read from the address or
  92                 ///   write to the address.
  93                 ///
  94                 ///   This is just a hint that can be used to provide good error
  95                 ///   reporting, and should have no other side effects.
  96                 /// </summary>
  97                 void AddressOf (EmitContext ec, AddressOp mode);
  98         }
  99
 100         //
 101         // An expressions resolved as a direct variable reference
 102         //
 103         public interface IVariableReference : IFixedExpression
 104         {
 105                 bool IsHoisted { get; }
 106                 string Name { get; }
 107                 VariableInfo VariableInfo { get; }
 108
 109                 void SetHasAddressTaken ();
 110         }
 111
 112         //
 113         // Implemented by an expression which could be or is always
 114         // fixed
 115         //
 116         public interface IFixedExpression
 117         {
 118                 bool IsFixed { get; }
 119         }
 120
 121         /// <remarks>
 122         ///   Base class for expressions
 123         /// </remarks>
 124         public abstract class Expression {
 125                 public ExprClass eclass;
 126                 protected TypeSpec type;
 127                 protected Location loc;
 128
 129                 public TypeSpec Type {
 130                         get { return type; }
 131                         set { type = value; }
 132                 }
 133
 134                 public virtual bool IsSideEffectFree {
 135                         get {
 136                                 return false;
 137                         }
 138                 }
 139
 140                 public Location Location {
 141                         get { return loc; }
 142                 }
 143
 144                 public virtual bool IsNull {
 145                         get {
 146                                 return false;
 147                         }
 148                 }
 149
 150                 //
 151                 // Returns true when the expression during Emit phase breaks stack
 152                 // by using await expression
 153                 //
 154                 public virtual bool ContainsEmitWithAwait ()
 155                 {
 156                         return false;
 157                 }
 158
 159                 /// <summary>
 160                 ///   Performs semantic analysis on the Expression
 161                 /// </summary>
 162                 ///
 163                 /// <remarks>
 164                 ///   The Resolve method is invoked to perform the semantic analysis
 165                 ///   on the node.
 166                 ///
 167                 ///   The return value is an expression (it can be the
 168                 ///   same expression in some cases) or a new
 169                 ///   expression that better represents this node.
 170                 ///
 171                 ///   For example, optimizations of Unary (LiteralInt)
 172                 ///   would return a new LiteralInt with a negated
 173                 ///   value.
 174                 ///
 175                 ///   If there is an error during semantic analysis,
 176                 ///   then an error should be reported (using Report)
 177                 ///   and a null value should be returned.
 178                 ///
 179                 ///   There are two side effects expected from calling
 180                 ///   Resolve(): the the field variable "eclass" should
 181                 ///   be set to any value of the enumeration
 182                 ///   `ExprClass' and the type variable should be set
 183                 ///   to a valid type (this is the type of the
 184                 ///   expression).
 185                 /// </remarks>
 186                 protected abstract Expression DoResolve (ResolveContext rc);
 187
 188                 public virtual Expression DoResolveLValue (ResolveContext rc, Expression right_side)
 189                 {
 190                         return null;
 191                 }
 192
 193                 //
 194                 // This is used if the expression should be resolved as a type or namespace name.
 195                 // the default implementation fails.
 196                 //
 197                 public virtual TypeSpec ResolveAsType (IMemberContext mc)
 198                 {
 199                         ResolveContext ec = new ResolveContext (mc);
 200                         Expression e = Resolve (ec);
 201                         if (e != null)
 202                                 e.Error_UnexpectedKind (ec, ResolveFlags.Type, loc);
 203
 204                         return null;
 205                 }
 206
 207                 public static void ErrorIsInaccesible (IMemberContext rc, string member, Location loc)
 208                 {
 209                         rc.Module.Compiler.Report.Error (122, loc, "`{0}' is inaccessible due to its protection level", member);
 210                 }
 211
 212                 public void Error_ExpressionMustBeConstant (ResolveContext rc, Location loc, string e_name)
 213                 {
 214                         rc.Report.Error (133, loc, "The expression being assigned to `{0}' must be constant", e_name);
 215                 }
 216
 217                 public void Error_ConstantCanBeInitializedWithNullOnly (ResolveContext rc, TypeSpec type, Location loc, string name)
 218                 {
 219                         rc.Report.Error (134, loc, "A constant `{0}' of reference type `{1}' can only be initialized with null",
 220                                 name, TypeManager.CSharpName (type));
 221                 }
 222
 223                 public static void Error_InvalidExpressionStatement (Report Report, Location loc)
 224                 {
 225                         Report.Error (201, loc, "Only assignment, call, increment, decrement, and new object " +
 226                                        "expressions can be used as a statement");
 227                 }
 228
 229                 public void Error_InvalidExpressionStatement (BlockContext ec)
 230                 {
 231                         Error_InvalidExpressionStatement (ec.Report, loc);
 232                 }
 233
 234                 public static void Error_VoidInvalidInTheContext (Location loc, Report Report)
 235                 {
 236                         Report.Error (1547, loc, "Keyword `void' cannot be used in this context");
 237                 }
 238
 239                 public virtual void Error_ValueCannotBeConverted (ResolveContext ec, Location loc, TypeSpec target, bool expl)
 240                 {
 241                         Error_ValueCannotBeConvertedCore (ec, loc, target, expl);
 242                 }
 243
 244                 protected void Error_ValueCannotBeConvertedCore (ResolveContext ec, Location loc, TypeSpec target, bool expl)
 245                 {
 246                         // The error was already reported as CS1660
 247                         if (type == InternalType.AnonymousMethod)
 248                                 return;
 249
 250                         string from_type = type.GetSignatureForError ();
 251                         string to_type = target.GetSignatureForError ();
 252                         if (from_type == to_type) {
 253                                 from_type = type.GetSignatureForErrorIncludingAssemblyName ();
 254                                 to_type = target.GetSignatureForErrorIncludingAssemblyName ();
 255                         }
 256
 257                         if (expl) {
 258                                 ec.Report.Error (30, loc, "Cannot convert type `{0}' to `{1}'",
 259                                         from_type, to_type);
 260                                 return;
 261                         }
 262
 263                         ec.Report.DisableReporting ();
 264                         bool expl_exists = Convert.ExplicitConversion (ec, this, target, Location.Null) != null;
 265                         ec.Report.EnableReporting ();
 266
 267                         if (expl_exists) {
 268                                 ec.Report.Error (266, loc,
 269                                         "Cannot implicitly convert type `{0}' to `{1}'. An explicit conversion exists (are you missing a cast?)",
 270                                         from_type, to_type);
 271                         } else {
 272                                 ec.Report.Error (29, loc, "Cannot implicitly convert type `{0}' to `{1}'",
 273                                         from_type, to_type);
 274                         }
 275                 }
 276
 277                 public void Error_TypeArgumentsCannotBeUsed (IMemberContext context, MemberSpec member, int arity, Location loc)
 278                 {
 279                         // Better message for possible generic expressions
 280                         if (member != null && (member.Kind & MemberKind.GenericMask) != 0) {
 281                                 var report = context.Module.Compiler.Report;
 282                                 report.SymbolRelatedToPreviousError (member);
 283                                 if (member is TypeSpec)
 284                                         member = ((TypeSpec) member).GetDefinition ();
 285                                 else
 286                                         member = ((MethodSpec) member).GetGenericMethodDefinition ();
 287
 288                                 string name = member.Kind == MemberKind.Method ? "method" : "type";
 289                                 if (member.IsGeneric) {
 290                                         report.Error (305, loc, "Using the generic {0} `{1}' requires `{2}' type argument(s)",
 291                                                 name, member.GetSignatureForError (), member.Arity.ToString ());
 292                                 } else {
 293                                         report.Error (308, loc, "The non-generic {0} `{1}' cannot be used with the type arguments",
 294                                                 name, member.GetSignatureForError ());
 295                                 }
 296                         } else {
 297                                 Error_TypeArgumentsCannotBeUsed (context, ExprClassName, GetSignatureForError (), loc);
 298                         }
 299                 }
 300
 301                 public void Error_TypeArgumentsCannotBeUsed (IMemberContext context, string exprType, string name, Location loc)
 302                 {
 303                         context.Module.Compiler.Report.Error (307, loc, "The {0} `{1}' cannot be used with type arguments",
 304                                 exprType, name);
 305                 }
 306
 307                 protected virtual void Error_TypeDoesNotContainDefinition (ResolveContext ec, TypeSpec type, string name)
 308                 {
 309                         Error_TypeDoesNotContainDefinition (ec, loc, type, name);
 310                 }
 311
 312                 public static void Error_TypeDoesNotContainDefinition (ResolveContext ec, Location loc, TypeSpec type, string name)
 313                 {
 314                         ec.Report.SymbolRelatedToPreviousError (type);
 315                         ec.Report.Error (117, loc, "`{0}' does not contain a definition for `{1}'",
 316                                 TypeManager.CSharpName (type), name);
 317                 }
 318
 319                 public void Error_ValueAssignment (ResolveContext rc, Expression rhs)
 320                 {
 321                         if (rhs == EmptyExpression.LValueMemberAccess || rhs == EmptyExpression.LValueMemberOutAccess) {
 322                                 rc.Report.SymbolRelatedToPreviousError (type);
 323                                 if (rc.CurrentInitializerVariable != null) {
 324                                         rc.Report.Error (1918, loc, "Members of value type `{0}' cannot be assigned using a property `{1}' object initializer",
 325                                                 type.GetSignatureForError (), GetSignatureForError ());
 326                                 } else {
 327                                         rc.Report.Error (1612, loc, "Cannot modify a value type return value of `{0}'. Consider storing the value in a temporary variable",
 328                                                 GetSignatureForError ());
 329                                 }
 330                         } else {
 331                                 rc.Report.Error (131, loc, "The left-hand side of an assignment must be a variable, a property or an indexer");
 332                         }
 333                 }
 334
 335                 protected void Error_VoidPointerOperation (ResolveContext rc)
 336                 {
 337                         rc.Report.Error (242, loc, "The operation in question is undefined on void pointers");
 338                 }
 339
 340                 public ResolveFlags ExprClassToResolveFlags {
 341                         get {
 342                                 switch (eclass) {
 343                                 case ExprClass.Type:
 344                                 case ExprClass.Namespace:
 345                                         return ResolveFlags.Type;
 346
 347                                 case ExprClass.MethodGroup:
 348                                         return ResolveFlags.MethodGroup;
 349
 350                                 case ExprClass.TypeParameter:
 351                                         return ResolveFlags.TypeParameter;
 352
 353                                 case ExprClass.Value:
 354                                 case ExprClass.Variable:
 355                                 case ExprClass.PropertyAccess:
 356                                 case ExprClass.EventAccess:
 357                                 case ExprClass.IndexerAccess:
 358                                         return ResolveFlags.VariableOrValue;
 359
 360                                 default:
 361                                         throw new InternalErrorException (loc.ToString () + " " +  GetType () + " ExprClass is Invalid after resolve");
 362                                 }
 363                         }
 364                 }
 365
 366                 public virtual string GetSignatureForError ()
 367                 {
 368                         return type.GetDefinition ().GetSignatureForError ();
 369                 }
 370
 371                 /// <summary>
 372                 ///   Resolves an expression and performs semantic analysis on it.
 373                 /// </summary>
 374                 ///
 375                 /// <remarks>
 376                 ///   Currently Resolve wraps DoResolve to perform sanity
 377                 ///   checking and assertion checking on what we expect from Resolve.
 378                 /// </remarks>
 379                 public Expression Resolve (ResolveContext ec, ResolveFlags flags)
 380                 {
 381                         if (eclass != ExprClass.Unresolved)
 382                                 return this;
 383
 384                         Expression e;
 385                         try {
 386                                 e = DoResolve (ec);
 387
 388                                 if (e == null)
 389                                         return null;
 390
 391                                 if ((flags & e.ExprClassToResolveFlags) == 0) {
 392                                         e.Error_UnexpectedKind (ec, flags, loc);
 393                                         return null;
 394                                 }
 395
 396                                 if (e.type == null)
 397                                         throw new InternalErrorException ("Expression `{0}' didn't set its type in DoResolve", e.GetType ());
 398
 399                                 return e;
 400                         } catch (Exception ex) {
 401                                 if (loc.IsNull || ec.Module.Compiler.Settings.DebugFlags > 0 || ex is CompletionResult || ec.Report.IsDisabled)
 402                                         throw;
 403
 404                                 ec.Report.Error (584, loc, "Internal compiler error: {0}", ex.Message);
 405                                 return ErrorExpression.Instance;        // TODO: Add location
 406                         }
 407                 }
 408
 409                 /// <summary>
 410                 ///   Resolves an expression and performs semantic analysis on it.
 411                 /// </summary>
 412                 public Expression Resolve (ResolveContext rc)
 413                 {
 414                         return Resolve (rc, ResolveFlags.VariableOrValue | ResolveFlags.MethodGroup);
 415                 }
 416
 417                 /// <summary>
 418                 ///   Resolves an expression for LValue assignment
 419                 /// </summary>
 420                 ///
 421                 /// <remarks>
 422                 ///   Currently ResolveLValue wraps DoResolveLValue to perform sanity
 423                 ///   checking and assertion checking on what we expect from Resolve
 424                 /// </remarks>
 425                 public Expression ResolveLValue (ResolveContext ec, Expression right_side)
 426                 {
 427                         int errors = ec.Report.Errors;
 428                         bool out_access = right_side == EmptyExpression.OutAccess;
 429
 430                         Expression e = DoResolveLValue (ec, right_side);
 431
 432                         if (e != null && out_access && !(e is IMemoryLocation)) {
 433                                 // FIXME: There's no problem with correctness, the 'Expr = null' handles that.
 434                                 //        Enabling this 'throw' will "only" result in deleting useless code elsewhere,
 435
 436                                 //throw new InternalErrorException ("ResolveLValue didn't return an IMemoryLocation: " +
 437                                 //                                e.GetType () + " " + e.GetSignatureForError ());
 438                                 e = null;
 439                         }
 440
 441                         if (e == null) {
 442                                 if (errors == ec.Report.Errors) {
 443                                         if (out_access)
 444                                                 ec.Report.Error (1510, loc, "A ref or out argument must be an assignable variable");
 445                                         else
 446                                                 Error_ValueAssignment (ec, right_side);
 447                                 }
 448                                 return null;
 449                         }
 450
 451                         if (e.eclass == ExprClass.Unresolved)
 452                                 throw new Exception ("Expression " + e + " ExprClass is Invalid after resolve");
 453
 454                         if ((e.type == null) && !(e is GenericTypeExpr))
 455                                 throw new Exception ("Expression " + e + " did not set its type after Resolve");
 456
 457                         return e;
 458                 }
 459
 460                 public virtual void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
 461                 {
 462                         rc.Module.Compiler.Report.Error (182, loc,
 463                                 "An attribute argument must be a constant expression, typeof expression or array creation expression");
 464                 }
 465
 466                 /// <summary>
 467                 ///   Emits the code for the expression
 468                 /// </summary>
 469                 ///
 470                 /// <remarks>
 471                 ///   The Emit method is invoked to generate the code
 472                 ///   for the expression.
 473                 /// </remarks>
 474                 public abstract void Emit (EmitContext ec);
 475
 476
 477                 // Emit code to branch to @target if this expression is equivalent to @on_true.
 478                 // The default implementation is to emit the value, and then emit a brtrue or brfalse.
 479                 // Subclasses can provide more efficient implementations, but those MUST be equivalent,
 480                 // including the use of conditional branches.  Note also that a branch MUST be emitted
 481                 public virtual void EmitBranchable (EmitContext ec, Label target, bool on_true)
 482                 {
 483                         Emit (ec);
 484                         ec.Emit (on_true ? OpCodes.Brtrue : OpCodes.Brfalse, target);
 485                 }
 486
 487                 // Emit this expression for its side effects, not for its value.
 488                 // The default implementation is to emit the value, and then throw it away.
 489                 // Subclasses can provide more efficient implementations, but those MUST be equivalent
 490                 public virtual void EmitSideEffect (EmitContext ec)
 491                 {
 492                         Emit (ec);
 493                         ec.Emit (OpCodes.Pop);
 494                 }
 495
 496                 //
 497                 // Emits the expression into temporary field variable. The method
 498                 // should be used for await expressions only
 499                 //
 500                 public virtual Expression EmitToField (EmitContext ec)
 501                 {
 502                         //
 503                         // This is the await prepare Emit method. When emitting code like
 504                         // a + b we emit code like
 505                         //
 506                         // a.Emit ()
 507                         // b.Emit ()
 508                         // Opcodes.Add
 509                         //
 510                         // For await a + await b we have to interfere the flow to keep the
 511                         // stack clean because await yields from the expression. The emit
 512                         // then changes to
 513                         //
 514                         // a = a.EmitToField () // a is changed to temporary field access
 515                         // b = b.EmitToField ()
 516                         // a.Emit ()
 517                         // b.Emit ()
 518                         // Opcodes.Add
 519                         //
 520                         //
 521                         // The idea is to emit expression and leave the stack empty with
 522                         // result value still available.
 523                         //
 524                         // Expressions should override this default implementation when
 525                         // optimized version can be provided (e.g. FieldExpr)
 526                         //
 527                         //
 528                         // We can optimize for side-effect free expressions, they can be
 529                         // emitted out of order
 530                         //
 531                         if (IsSideEffectFree)
 532                                 return this;
 533
 534                         bool needs_temporary = ContainsEmitWithAwait ();
 535                         if (!needs_temporary)
 536                                 ec.EmitThis ();
 537
 538                         // Emit original code
 539                         EmitToFieldSource (ec);
 540
 541                         //
 542                         // Store the result to temporary field when we
 543                         // cannot load `this' directly
 544                         //
 545                         var field = ec.GetTemporaryField (type);
 546                         if (needs_temporary) {
 547                                 //
 548                                 // Create temporary local (we cannot load `this' before Emit)
 549                                 //
 550                                 var temp = ec.GetTemporaryLocal (type);
 551                                 ec.Emit (OpCodes.Stloc, temp);
 552
 553                                 ec.EmitThis ();
 554                                 ec.Emit (OpCodes.Ldloc, temp);
 555                                 field.EmitAssignFromStack (ec);
 556
 557                                 ec.FreeTemporaryLocal (temp, type);
 558                         } else {
 559                                 field.EmitAssignFromStack (ec);
 560                         }
 561
 562                         return field;
 563                 }
 564
 565                 protected virtual void EmitToFieldSource (EmitContext ec)
 566                 {
 567                         //
 568                         // Default implementation calls Emit method
 569                         //
 570                         Emit (ec);
 571                 }
 572
 573                 protected static void EmitExpressionsList (EmitContext ec, List<Expression> expressions)
 574                 {
 575                         if (ec.HasSet (BuilderContext.Options.AsyncBody)) {
 576                                 bool contains_await = false;
 577
 578                                 for (int i = 1; i < expressions.Count; ++i) {
 579                                         if (expressions[i].ContainsEmitWithAwait ()) {
 580                                                 contains_await = true;
 581                                                 break;
 582                                         }
 583                                 }
 584
 585                                 if (contains_await) {
 586                                         for (int i = 0; i < expressions.Count; ++i) {
 587                                                 expressions[i] = expressions[i].EmitToField (ec);
 588                                         }
 589                                 }
 590                         }
 591
 592                         for (int i = 0; i < expressions.Count; ++i) {
 593                                 expressions[i].Emit (ec);
 594                         }
 595                 }
 596
 597                 /// <summary>
 598                 ///   Protected constructor.  Only derivate types should
 599                 ///   be able to be created
 600                 /// </summary>
 601
 602                 protected Expression ()
 603                 {
 604                 }
 605
 606                 /// <summary>
 607                 ///   Returns a fully formed expression after a MemberLookup
 608                 /// </summary>
 609                 ///
 610                 static Expression ExprClassFromMemberInfo (MemberSpec spec, Location loc)
 611                 {
 612                         if (spec is EventSpec)
 613                                 return new EventExpr ((EventSpec) spec, loc);
 614                         if (spec is ConstSpec)
 615                                 return new ConstantExpr ((ConstSpec) spec, loc);
 616                         if (spec is FieldSpec)
 617                                 return new FieldExpr ((FieldSpec) spec, loc);
 618                         if (spec is PropertySpec)
 619                                 return new PropertyExpr ((PropertySpec) spec, loc);
 620                         if (spec is TypeSpec)
 621                                 return new TypeExpression (((TypeSpec) spec), loc);
 622
 623                         return null;
 624                 }
 625
 626                 public static MethodSpec ConstructorLookup (ResolveContext rc, TypeSpec type, ref Arguments args, Location loc)
 627                 {
 628                         var ctors = MemberCache.FindMembers (type, Constructor.ConstructorName, true);
 629                         if (ctors == null) {
 630                                 rc.Report.SymbolRelatedToPreviousError (type);
 631                                 if (type.IsStruct) {
 632                                         // Report meaningful error for struct as they always have default ctor in C# context
 633                                         OverloadResolver.Error_ConstructorMismatch (rc, type, args == null ? 0 : args.Count, loc);
 634                                 } else {
 635                                         rc.Report.Error (143, loc, "The class `{0}' has no constructors defined",
 636                                                 type.GetSignatureForError ());
 637                                 }
 638
 639                                 return null;
 640                         }
 641
 642                         var r = new OverloadResolver (ctors, OverloadResolver.Restrictions.NoBaseMembers, loc);
 643                         if (!rc.HasSet (ResolveContext.Options.BaseInitializer)) {
 644                                 r.InstanceQualifier = new ConstructorInstanceQualifier (type);
 645                         }
 646
 647                         return r.ResolveMember<MethodSpec> (rc, ref args);
 648                 }
 649
 650                 [Flags]
 651                 public enum MemberLookupRestrictions
 652                 {
 653                         None = 0,
 654                         InvocableOnly = 1,
 655                         ExactArity = 1 << 2,
 656                         ReadAccess = 1 << 3
 657                 }
 658
 659                 //
 660                 // Lookup type `queried_type' for code in class `container_type' with a qualifier of
 661                 // `qualifier_type' or null to lookup members in the current class.
 662                 //
 663                 public static Expression MemberLookup (IMemberContext rc, bool errorMode, TypeSpec queried_type, string name, int arity, MemberLookupRestrictions restrictions, Location loc)
 664                 {
 665                         var members = MemberCache.FindMembers (queried_type, name, false);
 666                         if (members == null)
 667                                 return null;
 668
 669                         MemberSpec non_method = null;
 670                         MemberSpec ambig_non_method = null;
 671                         do {
 672                                 for (int i = 0; i < members.Count; ++i) {
 673                                         var member = members[i];
 674
 675                                         // HACK: for events because +=/-= can appear at same class only, should use OverrideToBase there
 676                                         if ((member.Modifiers & Modifiers.OVERRIDE) != 0 && member.Kind != MemberKind.Event)
 677                                                 continue;
 678
 679                                         if ((member.Modifiers & Modifiers.BACKING_FIELD) != 0)
 680                                                 continue;
 681
 682                                         if ((arity > 0 || (restrictions & MemberLookupRestrictions.ExactArity) != 0) && member.Arity != arity)
 683                                                 continue;
 684
 685                                         if (!errorMode) {
 686                                                 if (!member.IsAccessible (rc))
 687                                                         continue;
 688
 689                                                 //
 690                                                 // With runtime binder we can have a situation where queried type is inaccessible
 691                                                 // because it came via dynamic object, the check about inconsisted accessibility
 692                                                 // had no effect as the type was unknown during compilation
 693                                                 //
 694                                                 // class A {
 695                                                 //              private class N { }
 696                                                 //
 697                                                 //              public dynamic Foo ()
 698                                                 //              {
 699                                                 //                      return new N ();
 700                                                 //              }
 701                                                 //      }
 702                                                 //
 703                                                 if (rc.Module.Compiler.IsRuntimeBinder && !member.DeclaringType.IsAccessible (rc))
 704                                                         continue;
 705                                         }
 706
 707                                         if ((restrictions & MemberLookupRestrictions.InvocableOnly) != 0) {
 708                                                 if (member is MethodSpec)
 709                                                         return new MethodGroupExpr (members, queried_type, loc);
 710
 711                                                 if (!Invocation.IsMemberInvocable (member))
 712                                                         continue;
 713                                         }
 714
 715                                         if (non_method == null || member is MethodSpec || non_method.IsNotCSharpCompatible) {
 716                                                 non_method = member;
 717                                         } else if (!errorMode && !member.IsNotCSharpCompatible) {
 718                                                 ambig_non_method = member;
 719                                         }
 720                                 }
 721
 722                                 if (non_method != null) {
 723                                         if (ambig_non_method != null && rc != null) {
 724                                                 var report = rc.Module.Compiler.Report;
 725                                                 report.SymbolRelatedToPreviousError (non_method);
 726                                                 report.SymbolRelatedToPreviousError (ambig_non_method);
 727                                                 report.Error (229, loc, "Ambiguity between `{0}' and `{1}'",
 728                                                         non_method.GetSignatureForError (), ambig_non_method.GetSignatureForError ());
 729                                         }
 730
 731                                         if (non_method is MethodSpec)
 732                                                 return new MethodGroupExpr (members, queried_type, loc);
 733
 734                                         return ExprClassFromMemberInfo (non_method, loc);
 735                                 }
 736
 737                                 if (members[0].DeclaringType.BaseType == null)
 738                                         members = null;
 739                                 else
 740                                         members = MemberCache.FindMembers (members[0].DeclaringType.BaseType, name, false);
 741
 742                         } while (members != null);
 743
 744                         return null;
 745                 }
 746
 747                 protected virtual void Error_NegativeArrayIndex (ResolveContext ec, Location loc)
 748                 {
 749                         throw new NotImplementedException ();
 750                 }
 751
 752                 public virtual void Error_OperatorCannotBeApplied (ResolveContext rc, Location loc, string oper, TypeSpec t)
 753                 {
 754                         rc.Report.Error (23, loc, "The `{0}' operator cannot be applied to operand of type `{1}'",
 755                                 oper, t.GetSignatureForError ());
 756                 }
 757
 758                 protected void Error_PointerInsideExpressionTree (ResolveContext ec)
 759                 {
 760                         ec.Report.Error (1944, loc, "An expression tree cannot contain an unsafe pointer operation");
 761                 }
 762
 763                 /// <summary>
 764                 ///   Returns an expression that can be used to invoke operator true
 765                 ///   on the expression if it exists.
 766                 /// </summary>
 767                 protected static Expression GetOperatorTrue (ResolveContext ec, Expression e, Location loc)
 768                 {
 769                         return GetOperatorTrueOrFalse (ec, e, true, loc);
 770                 }
 771
 772                 /// <summary>
 773                 ///   Returns an expression that can be used to invoke operator false
 774                 ///   on the expression if it exists.
 775                 /// </summary>
 776                 protected static Expression GetOperatorFalse (ResolveContext ec, Expression e, Location loc)
 777                 {
 778                         return GetOperatorTrueOrFalse (ec, e, false, loc);
 779                 }
 780
 781                 static Expression GetOperatorTrueOrFalse (ResolveContext ec, Expression e, bool is_true, Location loc)
 782                 {
 783                         var op = is_true ? Operator.OpType.True : Operator.OpType.False;
 784                         var methods = MemberCache.GetUserOperator (e.type, op, false);
 785                         if (methods == null)
 786                                 return null;
 787
 788                         Arguments arguments = new Arguments (1);
 789                         arguments.Add (new Argument (e));
 790
 791                         var res = new OverloadResolver (methods, OverloadResolver.Restrictions.BaseMembersIncluded | OverloadResolver.Restrictions.NoBaseMembers, loc);
 792                         var oper = res.ResolveOperator (ec, ref arguments);
 793
 794                         if (oper == null)
 795                                 return null;
 796
 797                         return new UserOperatorCall (oper, arguments, null, loc);
 798                 }
 799
 800                 public virtual string ExprClassName
 801                 {
 802                         get {
 803                                 switch (eclass){
 804                                 case ExprClass.Unresolved:
 805                                         return "Unresolved";
 806                                 case ExprClass.Value:
 807                                         return "value";
 808                                 case ExprClass.Variable:
 809                                         return "variable";
 810                                 case ExprClass.Namespace:
 811                                         return "namespace";
 812                                 case ExprClass.Type:
 813                                         return "type";
 814                                 case ExprClass.MethodGroup:
 815                                         return "method group";
 816                                 case ExprClass.PropertyAccess:
 817                                         return "property access";
 818                                 case ExprClass.EventAccess:
 819                                         return "event access";
 820                                 case ExprClass.IndexerAccess:
 821                                         return "indexer access";
 822                                 case ExprClass.Nothing:
 823                                         return "null";
 824                                 case ExprClass.TypeParameter:
 825                                         return "type parameter";
 826                                 }
 827                                 throw new Exception ("Should not happen");
 828                         }
 829                 }
 830
 831                 /// <summary>
 832                 ///   Reports that we were expecting `expr' to be of class `expected'
 833                 /// </summary>
 834                 public void Error_UnexpectedKind (Report r, MemberCore mc, string expected, Location loc)
 835                 {
 836                         Error_UnexpectedKind (r, mc, expected, ExprClassName, loc);
 837                 }
 838
 839                 public void Error_UnexpectedKind (Report r, MemberCore mc, string expected, string was, Location loc)
 840                 {
 841                         string name;
 842                         if (mc != null)
 843                                 name = mc.GetSignatureForError ();
 844                         else
 845                                 name = GetSignatureForError ();
 846
 847                         r.Error (118, loc, "`{0}' is a `{1}' but a `{2}' was expected",
 848                               name, was, expected);
 849                 }
 850
 851                 public virtual void Error_UnexpectedKind (ResolveContext ec, ResolveFlags flags, Location loc)
 852                 {
 853                         string [] valid = new string [4];
 854                         int count = 0;
 855
 856                         if ((flags & ResolveFlags.VariableOrValue) != 0) {
 857                                 valid [count++] = "variable";
 858                                 valid [count++] = "value";
 859                         }
 860
 861                         if ((flags & ResolveFlags.Type) != 0)
 862                                 valid [count++] = "type";
 863
 864                         if ((flags & ResolveFlags.MethodGroup) != 0)
 865                                 valid [count++] = "method group";
 866
 867                         if (count == 0)
 868                                 valid [count++] = "unknown";
 869
 870                         StringBuilder sb = new StringBuilder (valid [0]);
 871                         for (int i = 1; i < count - 1; i++) {
 872                                 sb.Append ("', `");
 873                                 sb.Append (valid [i]);
 874                         }
 875                         if (count > 1) {
 876                                 sb.Append ("' or `");
 877                                 sb.Append (valid [count - 1]);
 878                         }
 879
 880                         ec.Report.Error (119, loc,
 881                                 "Expression denotes a `{0}', where a `{1}' was expected", ExprClassName, sb.ToString ());
 882                 }
 883
 884                 public static void UnsafeError (ResolveContext ec, Location loc)
 885                 {
 886                         UnsafeError (ec.Report, loc);
 887                 }
 888
 889                 public static void UnsafeError (Report Report, Location loc)
 890                 {
 891                         Report.Error (214, loc, "Pointers and fixed size buffers may only be used in an unsafe context");
 892                 }
 893
 894                 //
 895                 // Converts `source' to an int, uint, long or ulong.
 896                 //
 897                 protected Expression ConvertExpressionToArrayIndex (ResolveContext ec, Expression source)
 898                 {
 899                         var btypes = ec.BuiltinTypes;
 900
 901                         if (source.type.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
 902                                 Arguments args = new Arguments (1);
 903                                 args.Add (new Argument (source));
 904                                 return new DynamicConversion (btypes.Int, CSharpBinderFlags.ConvertArrayIndex, args, loc).Resolve (ec);
 905                         }
 906
 907                         Expression converted;
 908
 909                         using (ec.Set (ResolveContext.Options.CheckedScope)) {
 910                                 converted = Convert.ImplicitConversion (ec, source, btypes.Int, source.loc);
 911                                 if (converted == null)
 912                                         converted = Convert.ImplicitConversion (ec, source, btypes.UInt, source.loc);
 913                                 if (converted == null)
 914                                         converted = Convert.ImplicitConversion (ec, source, btypes.Long, source.loc);
 915                                 if (converted == null)
 916                                         converted = Convert.ImplicitConversion (ec, source, btypes.ULong, source.loc);
 917
 918                                 if (converted == null) {
 919                                         source.Error_ValueCannotBeConverted (ec, source.loc, btypes.Int, false);
 920                                         return null;
 921                                 }
 922                         }
 923
 924                         //
 925                         // Only positive constants are allowed at compile time
 926                         //
 927                         Constant c = converted as Constant;
 928                         if (c != null && c.IsNegative)
 929                                 Error_NegativeArrayIndex (ec, source.loc);
 930
 931                         // No conversion needed to array index
 932                         if (converted.Type.BuiltinType == BuiltinTypeSpec.Type.Int)
 933                                 return converted;
 934
 935                         return new ArrayIndexCast (converted, btypes.Int).Resolve (ec);
 936                 }
 937
 938                 //
 939                 // Derived classes implement this method by cloning the fields that
 940                 // could become altered during the Resolve stage
 941                 //
 942                 // Only expressions that are created for the parser need to implement
 943                 // this.
 944                 //
 945                 protected virtual void CloneTo (CloneContext clonectx, Expression target)
 946                 {
 947                         throw new NotImplementedException (
 948                                 String.Format (
 949                                         "CloneTo not implemented for expression {0}", this.GetType ()));
 950                 }
 951
 952                 //
 953                 // Clones an expression created by the parser.
 954                 //
 955                 // We only support expressions created by the parser so far, not
 956                 // expressions that have been resolved (many more classes would need
 957                 // to implement CloneTo).
 958                 //
 959                 // This infrastructure is here merely for Lambda expressions which
 960                 // compile the same code using different type values for the same
 961                 // arguments to find the correct overload
 962                 //
 963                 public virtual Expression Clone (CloneContext clonectx)
 964                 {
 965                         Expression cloned = (Expression) MemberwiseClone ();
 966                         CloneTo (clonectx, cloned);
 967
 968                         return cloned;
 969                 }
 970
 971                 //
 972                 // Implementation of expression to expression tree conversion
 973                 //
 974                 public abstract Expression CreateExpressionTree (ResolveContext ec);
 975
 976                 protected Expression CreateExpressionFactoryCall (ResolveContext ec, string name, Arguments args)
 977                 {
 978                         return CreateExpressionFactoryCall (ec, name, null, args, loc);
 979                 }
 980
 981                 protected Expression CreateExpressionFactoryCall (ResolveContext ec, string name, TypeArguments typeArguments, Arguments args)
 982                 {
 983                         return CreateExpressionFactoryCall (ec, name, typeArguments, args, loc);
 984                 }
 985
 986                 public static Expression CreateExpressionFactoryCall (ResolveContext ec, string name, TypeArguments typeArguments, Arguments args, Location loc)
 987                 {
 988                         return new Invocation (new MemberAccess (CreateExpressionTypeExpression (ec, loc), name, typeArguments, loc), args);
 989                 }
 990
 991                 protected static TypeExpr CreateExpressionTypeExpression (ResolveContext ec, Location loc)
 992                 {
 993                         var t = ec.Module.PredefinedTypes.Expression.Resolve ();
 994                         if (t == null)
 995                                 return null;
 996
 997                         return new TypeExpression (t, loc);
 998                 }
 999
1000                 //
1001                 // Implemented by all expressions which support conversion from
1002                 // compiler expression to invokable runtime expression. Used by
1003                 // dynamic C# binder.
1004                 //
1005                 public virtual SLE.Expression MakeExpression (BuilderContext ctx)
1006                 {
1007                         throw new NotImplementedException ("MakeExpression for " + GetType ());
1008                 }
1009
1010                 public virtual object Accept (StructuralVisitor visitor)
1011                 {
1012                         return visitor.Visit (this);
1013                 }
1014         }
1015
1016         /// <summary>
1017         ///   This is just a base class for expressions that can
1018         ///   appear on statements (invocations, object creation,
1019         ///   assignments, post/pre increment and decrement).  The idea
1020         ///   being that they would support an extra Emition interface that
1021         ///   does not leave a result on the stack.
1022         /// </summary>
1023         public abstract class ExpressionStatement : Expression {
1024
1025                 public ExpressionStatement ResolveStatement (BlockContext ec)
1026                 {
1027                         Expression e = Resolve (ec);
1028                         if (e == null)
1029                                 return null;
1030
1031                         ExpressionStatement es = e as ExpressionStatement;
1032                         if (es == null)
1033                                 Error_InvalidExpressionStatement (ec);
1034
1035                         return es;
1036                 }
1037
1038                 /// <summary>
1039                 ///   Requests the expression to be emitted in a `statement'
1040                 ///   context.  This means that no new value is left on the
1041                 ///   stack after invoking this method (constrasted with
1042                 ///   Emit that will always leave a value on the stack).
1043                 /// </summary>
1044                 public abstract void EmitStatement (EmitContext ec);
1045
1046                 public override void EmitSideEffect (EmitContext ec)
1047                 {
1048                         EmitStatement (ec);
1049                 }
1050         }
1051
1052         /// <summary>
1053         ///   This kind of cast is used to encapsulate the child
1054         ///   whose type is child.Type into an expression that is
1055         ///   reported to return "return_type".  This is used to encapsulate
1056         ///   expressions which have compatible types, but need to be dealt
1057         ///   at higher levels with.
1058         ///
1059         ///   For example, a "byte" expression could be encapsulated in one
1060         ///   of these as an "unsigned int".  The type for the expression
1061         ///   would be "unsigned int".
1062         ///
1063         /// </summary>
1064         public abstract class TypeCast : Expression
1065         {
1066                 protected readonly Expression child;
1067
1068                 protected TypeCast (Expression child, TypeSpec return_type)
1069                 {
1070                         eclass = child.eclass;
1071                         loc = child.Location;
1072                         type = return_type;
1073                         this.child = child;
1074                 }
1075
1076                 public Expression Child {
1077                         get {
1078                                 return child;
1079                         }
1080                 }
1081
1082                 public override bool ContainsEmitWithAwait ()
1083                 {
1084                         return child.ContainsEmitWithAwait ();
1085                 }
1086
1087                 public override Expression CreateExpressionTree (ResolveContext ec)
1088                 {
1089                         Arguments args = new Arguments (2);
1090                         args.Add (new Argument (child.CreateExpressionTree (ec)));
1091                         args.Add (new Argument (new TypeOf (type, loc)));
1092
1093                         if (type.IsPointer || child.Type.IsPointer)
1094                                 Error_PointerInsideExpressionTree (ec);
1095
1096                         return CreateExpressionFactoryCall (ec, ec.HasSet (ResolveContext.Options.CheckedScope) ? "ConvertChecked" : "Convert", args);
1097                 }
1098
1099                 protected override Expression DoResolve (ResolveContext ec)
1100                 {
1101                         // This should never be invoked, we are born in fully
1102                         // initialized state.
1103
1104                         return this;
1105                 }
1106
1107                 public override void Emit (EmitContext ec)
1108                 {
1109                         child.Emit (ec);
1110                 }
1111
1112                 public override SLE.Expression MakeExpression (BuilderContext ctx)
1113                 {
1114 #if STATIC
1115                         return base.MakeExpression (ctx);
1116 #else
1117                         return ctx.HasSet (BuilderContext.Options.CheckedScope) ?
1118                                 SLE.Expression.ConvertChecked (child.MakeExpression (ctx), type.GetMetaInfo ()) :
1119                                 SLE.Expression.Convert (child.MakeExpression (ctx), type.GetMetaInfo ());
1120 #endif
1121                 }
1122
1123                 protected override void CloneTo (CloneContext clonectx, Expression t)
1124                 {
1125                         // Nothing to clone
1126                 }
1127
1128                 public override bool IsNull {
1129                         get { return child.IsNull; }
1130                 }
1131         }
1132
1133         public class EmptyCast : TypeCast {
1134                 EmptyCast (Expression child, TypeSpec target_type)
1135                         : base (child, target_type)
1136                 {
1137                 }
1138
1139                 public static Expression Create (Expression child, TypeSpec type)
1140                 {
1141                         Constant c = child as Constant;
1142                         if (c != null)
1143                                 return new EmptyConstantCast (c, type);
1144
1145                         EmptyCast e = child as EmptyCast;
1146                         if (e != null)
1147                                 return new EmptyCast (e.child, type);
1148
1149                         return new EmptyCast (child, type);
1150                 }
1151
1152                 public override void EmitBranchable (EmitContext ec, Label label, bool on_true)
1153                 {
1154                         child.EmitBranchable (ec, label, on_true);
1155                 }
1156
1157                 public override void EmitSideEffect (EmitContext ec)
1158                 {
1159                         child.EmitSideEffect (ec);
1160                 }
1161         }
1162
1163         //
1164         // Used for predefined type user operator (no obsolete check, etc.)
1165         //
1166         public class OperatorCast : TypeCast
1167         {
1168                 readonly MethodSpec conversion_operator;
1169
1170                 public OperatorCast (Expression expr, TypeSpec target_type)
1171                         : this (expr, target_type, target_type, false)
1172                 {
1173                 }
1174
1175                 public OperatorCast (Expression expr, TypeSpec target_type, bool find_explicit)
1176                         : this (expr, target_type, target_type, find_explicit)
1177                 {
1178                 }
1179
1180                 public OperatorCast (Expression expr, TypeSpec declaringType, TypeSpec returnType, bool isExplicit)
1181                         : base (expr, returnType)
1182                 {
1183                         var op = isExplicit ? Operator.OpType.Explicit : Operator.OpType.Implicit;
1184                         var mi = MemberCache.GetUserOperator (declaringType, op, true);
1185
1186                         if (mi != null) {
1187                                 foreach (MethodSpec oper in mi) {
1188                                         if (oper.ReturnType != returnType)
1189                                                 continue;
1190
1191                                         if (oper.Parameters.Types[0] == expr.Type) {
1192                                                 conversion_operator = oper;
1193                                                 return;
1194                                         }
1195                                 }
1196                         }
1197
1198                         throw new InternalErrorException ("Missing predefined user operator between `{0}' and `{1}'",
1199                                 returnType.GetSignatureForError (), expr.Type.GetSignatureForError ());
1200                 }
1201
1202                 public override void Emit (EmitContext ec)
1203                 {
1204                         child.Emit (ec);
1205                         ec.Emit (OpCodes.Call, conversion_operator);
1206                 }
1207         }
1208
1209         //
1210         // Constant specialization of EmptyCast.
1211         // We need to special case this since an empty cast of
1212         // a constant is still a constant.
1213         //
1214         public class EmptyConstantCast : Constant
1215         {
1216                 public readonly Constant child;
1217
1218                 public EmptyConstantCast (Constant child, TypeSpec type)
1219                         : base (child.Location)
1220                 {
1221                         if (child == null)
1222                                 throw new ArgumentNullException ("child");
1223
1224                         this.child = child;
1225                         this.eclass = child.eclass;
1226                         this.type = type;
1227                 }
1228
1229                 public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
1230                 {
1231                         if (child.Type == target_type)
1232                                 return child;
1233
1234                         // FIXME: check that 'type' can be converted to 'target_type' first
1235                         return child.ConvertExplicitly (in_checked_context, target_type);
1236                 }
1237
1238                 public override Expression CreateExpressionTree (ResolveContext ec)
1239                 {
1240                         Arguments args = Arguments.CreateForExpressionTree (ec, null,
1241                                 child.CreateExpressionTree (ec),
1242                                 new TypeOf (type, loc));
1243
1244                         if (type.IsPointer)
1245                                 Error_PointerInsideExpressionTree (ec);
1246
1247                         return CreateExpressionFactoryCall (ec, "Convert", args);
1248                 }
1249
1250                 public override bool IsDefaultValue {
1251                         get { return child.IsDefaultValue; }
1252                 }
1253
1254                 public override bool IsNegative {
1255                         get { return child.IsNegative; }
1256                 }
1257
1258                 public override bool IsNull {
1259                         get { return child.IsNull; }
1260                 }
1261
1262                 public override bool IsOneInteger {
1263                         get { return child.IsOneInteger; }
1264                 }
1265
1266                 public override bool IsSideEffectFree {
1267                         get {
1268                                 return child.IsSideEffectFree;
1269                         }
1270                 }
1271
1272                 public override bool IsZeroInteger {
1273                         get { return child.IsZeroInteger; }
1274                 }
1275
1276                 public override void Emit (EmitContext ec)
1277                 {
1278                         child.Emit (ec);
1279                 }
1280
1281                 public override void EmitBranchable (EmitContext ec, Label label, bool on_true)
1282                 {
1283                         child.EmitBranchable (ec, label, on_true);
1284
1285                         // Only to make verifier happy
1286                         if (TypeManager.IsGenericParameter (type) && child.IsNull)
1287                                 ec.Emit (OpCodes.Unbox_Any, type);
1288                 }
1289
1290                 public override void EmitSideEffect (EmitContext ec)
1291                 {
1292                         child.EmitSideEffect (ec);
1293                 }
1294
1295                 public override object GetValue ()
1296                 {
1297                         return child.GetValue ();
1298                 }
1299
1300                 public override string GetValueAsLiteral ()
1301                 {
1302                         return child.GetValueAsLiteral ();
1303                 }
1304
1305                 public override long GetValueAsLong ()
1306                 {
1307                         return child.GetValueAsLong ();
1308                 }
1309
1310                 public override Constant ConvertImplicitly (TypeSpec target_type)
1311                 {
1312                         if (type == target_type)
1313                                 return this;
1314
1315                         // FIXME: Do we need to check user conversions?
1316                         if (!Convert.ImplicitStandardConversionExists (this, target_type))
1317                                 return null;
1318
1319                         return child.ConvertImplicitly (target_type);
1320                 }
1321         }
1322
1323         /// <summary>
1324         ///  This class is used to wrap literals which belong inside Enums
1325         /// </summary>
1326         public class EnumConstant : Constant
1327         {
1328                 public Constant Child;
1329
1330                 public EnumConstant (Constant child, TypeSpec enum_type)
1331                         : base (child.Location)
1332                 {
1333                         this.Child = child;
1334
1335                         this.eclass = ExprClass.Value;
1336                         this.type = enum_type;
1337                 }
1338
1339                 protected EnumConstant (Location loc)
1340                         : base (loc)
1341                 {
1342                 }
1343
1344                 public override void Emit (EmitContext ec)
1345                 {
1346                         Child.Emit (ec);
1347                 }
1348
1349                 public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
1350                 {
1351                         Child.EncodeAttributeValue (rc, enc, Child.Type);
1352                 }
1353
1354                 public override void EmitBranchable (EmitContext ec, Label label, bool on_true)
1355                 {
1356                         Child.EmitBranchable (ec, label, on_true);
1357                 }
1358
1359                 public override void EmitSideEffect (EmitContext ec)
1360                 {
1361                         Child.EmitSideEffect (ec);
1362                 }
1363
1364                 public override string GetSignatureForError()
1365                 {
1366                         return TypeManager.CSharpName (Type);
1367                 }
1368
1369                 public override object GetValue ()
1370                 {
1371                         return Child.GetValue ();
1372                 }
1373
1374 #if !STATIC
1375                 public override object GetTypedValue ()
1376                 {
1377                         //
1378                         // The method can be used in dynamic context only (on closed types)
1379                         //
1380                         // System.Enum.ToObject cannot be called on dynamic types
1381                         // EnumBuilder has to be used, but we cannot use EnumBuilder
1382                         // because it does not properly support generics
1383                         //
1384                         return System.Enum.ToObject (type.GetMetaInfo (), Child.GetValue ());
1385                 }
1386 #endif
1387
1388                 public override string GetValueAsLiteral ()
1389                 {
1390                         return Child.GetValueAsLiteral ();
1391                 }
1392
1393                 public override long GetValueAsLong ()
1394                 {
1395                         return Child.GetValueAsLong ();
1396                 }
1397
1398                 public EnumConstant Increment()
1399                 {
1400                         return new EnumConstant (((IntegralConstant) Child).Increment (), type);
1401                 }
1402
1403                 public override bool IsDefaultValue {
1404                         get {
1405                                 return Child.IsDefaultValue;
1406                         }
1407                 }
1408
1409                 public override bool IsSideEffectFree {
1410                         get {
1411                                 return Child.IsSideEffectFree;
1412                         }
1413                 }
1414
1415                 public override bool IsZeroInteger {
1416                         get { return Child.IsZeroInteger; }
1417                 }
1418
1419                 public override bool IsNegative {
1420                         get {
1421                                 return Child.IsNegative;
1422                         }
1423                 }
1424
1425                 public override Constant ConvertExplicitly(bool in_checked_context, TypeSpec target_type)
1426                 {
1427                         if (Child.Type == target_type)
1428                                 return Child;
1429
1430                         return Child.ConvertExplicitly (in_checked_context, target_type);
1431                 }
1432
1433                 public override Constant ConvertImplicitly (TypeSpec type)
1434                 {
1435                         if (this.type == type) {
1436                                 return this;
1437                         }
1438
1439                         if (!Convert.ImplicitStandardConversionExists (this, type)){
1440                                 return null;
1441                         }
1442
1443                         return Child.ConvertImplicitly (type);
1444                 }
1445         }
1446
1447         /// <summary>
1448         ///   This kind of cast is used to encapsulate Value Types in objects.
1449         ///
1450         ///   The effect of it is to box the value type emitted by the previous
1451         ///   operation.
1452         /// </summary>
1453         public class BoxedCast : TypeCast {
1454
1455                 public BoxedCast (Expression expr, TypeSpec target_type)
1456                         : base (expr, target_type)
1457                 {
1458                         eclass = ExprClass.Value;
1459                 }
1460
1461                 protected override Expression DoResolve (ResolveContext ec)
1462                 {
1463                         // This should never be invoked, we are born in fully
1464                         // initialized state.
1465
1466                         return this;
1467                 }
1468
1469                 public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
1470                 {
1471                         // Only boxing to object type is supported
1472                         if (targetType.BuiltinType != BuiltinTypeSpec.Type.Object) {
1473                                 base.EncodeAttributeValue (rc, enc, targetType);
1474                                 return;
1475                         }
1476
1477                         enc.Encode (child.Type);
1478                         child.EncodeAttributeValue (rc, enc, child.Type);
1479                 }
1480
1481                 public override void Emit (EmitContext ec)
1482                 {
1483                         base.Emit (ec);
1484
1485                         ec.Emit (OpCodes.Box, child.Type);
1486                 }
1487
1488                 public override void EmitSideEffect (EmitContext ec)
1489                 {
1490                         // boxing is side-effectful, since it involves runtime checks, except when boxing to Object or ValueType
1491                         // so, we need to emit the box+pop instructions in most cases
1492                         if (child.Type.IsStruct &&
1493                             (type.BuiltinType == BuiltinTypeSpec.Type.Object || type.BuiltinType == BuiltinTypeSpec.Type.ValueType))
1494                                 child.EmitSideEffect (ec);
1495                         else
1496                                 base.EmitSideEffect (ec);
1497                 }
1498         }
1499
1500         public class UnboxCast : TypeCast {
1501                 public UnboxCast (Expression expr, TypeSpec return_type)
1502                         : base (expr, return_type)
1503                 {
1504                 }
1505
1506                 protected override Expression DoResolve (ResolveContext ec)
1507                 {
1508                         // This should never be invoked, we are born in fully
1509                         // initialized state.
1510
1511                         return this;
1512                 }
1513
1514                 public override void Emit (EmitContext ec)
1515                 {
1516                         base.Emit (ec);
1517
1518                         ec.Emit (OpCodes.Unbox_Any, type);
1519                 }
1520         }
1521
1522         /// <summary>
1523         ///   This is used to perform explicit numeric conversions.
1524         ///
1525         ///   Explicit numeric conversions might trigger exceptions in a checked
1526         ///   context, so they should generate the conv.ovf opcodes instead of
1527         ///   conv opcodes.
1528         /// </summary>
1529         public class ConvCast : TypeCast {
1530                 public enum Mode : byte {
1531                         I1_U1, I1_U2, I1_U4, I1_U8, I1_CH,
1532                         U1_I1, U1_CH,
1533                         I2_I1, I2_U1, I2_U2, I2_U4, I2_U8, I2_CH,
1534                         U2_I1, U2_U1, U2_I2, U2_CH,
1535                         I4_I1, I4_U1, I4_I2, I4_U2, I4_U4, I4_U8, I4_CH,
1536                         U4_I1, U4_U1, U4_I2, U4_U2, U4_I4, U4_CH,
1537                         I8_I1, I8_U1, I8_I2, I8_U2, I8_I4, I8_U4, I8_U8, I8_CH, I8_I,
1538                         U8_I1, U8_U1, U8_I2, U8_U2, U8_I4, U8_U4, U8_I8, U8_CH, U8_I,
1539                         CH_I1, CH_U1, CH_I2,
1540                         R4_I1, R4_U1, R4_I2, R4_U2, R4_I4, R4_U4, R4_I8, R4_U8, R4_CH,
1541                         R8_I1, R8_U1, R8_I2, R8_U2, R8_I4, R8_U4, R8_I8, R8_U8, R8_CH, R8_R4,
1542                         I_I8,
1543                 }
1544
1545                 Mode mode;
1546
1547                 public ConvCast (Expression child, TypeSpec return_type, Mode m)
1548                         : base (child, return_type)
1549                 {
1550                         mode = m;
1551                 }
1552
1553                 protected override Expression DoResolve (ResolveContext ec)
1554                 {
1555                         // This should never be invoked, we are born in fully
1556                         // initialized state.
1557
1558                         return this;
1559                 }
1560
1561                 public override string ToString ()
1562                 {
1563                         return String.Format ("ConvCast ({0}, {1})", mode, child);
1564                 }
1565
1566                 public override void Emit (EmitContext ec)
1567                 {
1568                         base.Emit (ec);
1569
1570                         if (ec.HasSet (EmitContext.Options.CheckedScope)) {
1571                                 switch (mode){
1572                                 case Mode.I1_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1573                                 case Mode.I1_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1574                                 case Mode.I1_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1575                                 case Mode.I1_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1576                                 case Mode.I1_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1577
1578                                 case Mode.U1_I1: ec.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1579                                 case Mode.U1_CH: /* nothing */ break;
1580
1581                                 case Mode.I2_I1: ec.Emit (OpCodes.Conv_Ovf_I1); break;
1582                                 case Mode.I2_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1583                                 case Mode.I2_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1584                                 case Mode.I2_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1585                                 case Mode.I2_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1586                                 case Mode.I2_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1587
1588                                 case Mode.U2_I1: ec.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1589                                 case Mode.U2_U1: ec.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1590                                 case Mode.U2_I2: ec.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1591                                 case Mode.U2_CH: /* nothing */ break;
1592
1593                                 case Mode.I4_I1: ec.Emit (OpCodes.Conv_Ovf_I1); break;
1594                                 case Mode.I4_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1595                                 case Mode.I4_I2: ec.Emit (OpCodes.Conv_Ovf_I2); break;
1596                                 case Mode.I4_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1597                                 case Mode.I4_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1598                                 case Mode.I4_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1599                                 case Mode.I4_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1600
1601                                 case Mode.U4_I1: ec.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1602                                 case Mode.U4_U1: ec.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1603                                 case Mode.U4_I2: ec.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1604                                 case Mode.U4_U2: ec.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1605                                 case Mode.U4_I4: ec.Emit (OpCodes.Conv_Ovf_I4_Un); break;
1606                                 case Mode.U4_CH: ec.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1607
1608                                 case Mode.I8_I1: ec.Emit (OpCodes.Conv_Ovf_I1); break;
1609                                 case Mode.I8_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1610                                 case Mode.I8_I2: ec.Emit (OpCodes.Conv_Ovf_I2); break;
1611                                 case Mode.I8_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1612                                 case Mode.I8_I4: ec.Emit (OpCodes.Conv_Ovf_I4); break;
1613                                 case Mode.I8_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1614                                 case Mode.I8_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1615                                 case Mode.I8_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1616                                 case Mode.I8_I: ec.Emit (OpCodes.Conv_Ovf_U); break;
1617
1618                                 case Mode.U8_I1: ec.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1619                                 case Mode.U8_U1: ec.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1620                                 case Mode.U8_I2: ec.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1621                                 case Mode.U8_U2: ec.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1622                                 case Mode.U8_I4: ec.Emit (OpCodes.Conv_Ovf_I4_Un); break;
1623                                 case Mode.U8_U4: ec.Emit (OpCodes.Conv_Ovf_U4_Un); break;
1624                                 case Mode.U8_I8: ec.Emit (OpCodes.Conv_Ovf_I8_Un); break;
1625                                 case Mode.U8_CH: ec.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1626                                 case Mode.U8_I: ec.Emit (OpCodes.Conv_Ovf_U_Un); break;
1627
1628                                 case Mode.CH_I1: ec.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1629                                 case Mode.CH_U1: ec.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1630                                 case Mode.CH_I2: ec.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1631
1632                                 case Mode.R4_I1: ec.Emit (OpCodes.Conv_Ovf_I1); break;
1633                                 case Mode.R4_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1634                                 case Mode.R4_I2: ec.Emit (OpCodes.Conv_Ovf_I2); break;
1635                                 case Mode.R4_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1636                                 case Mode.R4_I4: ec.Emit (OpCodes.Conv_Ovf_I4); break;
1637                                 case Mode.R4_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1638                                 case Mode.R4_I8: ec.Emit (OpCodes.Conv_Ovf_I8); break;
1639                                 case Mode.R4_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1640                                 case Mode.R4_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1641
1642                                 case Mode.R8_I1: ec.Emit (OpCodes.Conv_Ovf_I1); break;
1643                                 case Mode.R8_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1644                                 case Mode.R8_I2: ec.Emit (OpCodes.Conv_Ovf_I2); break;
1645                                 case Mode.R8_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1646                                 case Mode.R8_I4: ec.Emit (OpCodes.Conv_Ovf_I4); break;
1647                                 case Mode.R8_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1648                                 case Mode.R8_I8: ec.Emit (OpCodes.Conv_Ovf_I8); break;
1649                                 case Mode.R8_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1650                                 case Mode.R8_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1651                                 case Mode.R8_R4: ec.Emit (OpCodes.Conv_R4); break;
1652
1653                                 case Mode.I_I8: ec.Emit (OpCodes.Conv_Ovf_I8_Un); break;
1654                                 }
1655                         } else {
1656                                 switch (mode){
1657                                 case Mode.I1_U1: ec.Emit (OpCodes.Conv_U1); break;
1658                                 case Mode.I1_U2: ec.Emit (OpCodes.Conv_U2); break;
1659                                 case Mode.I1_U4: ec.Emit (OpCodes.Conv_U4); break;
1660                                 case Mode.I1_U8: ec.Emit (OpCodes.Conv_I8); break;
1661                                 case Mode.I1_CH: ec.Emit (OpCodes.Conv_U2); break;
1662
1663                                 case Mode.U1_I1: ec.Emit (OpCodes.Conv_I1); break;
1664                                 case Mode.U1_CH: ec.Emit (OpCodes.Conv_U2); break;
1665
1666                                 case Mode.I2_I1: ec.Emit (OpCodes.Conv_I1); break;
1667                                 case Mode.I2_U1: ec.Emit (OpCodes.Conv_U1); break;
1668                                 case Mode.I2_U2: ec.Emit (OpCodes.Conv_U2); break;
1669                                 case Mode.I2_U4: ec.Emit (OpCodes.Conv_U4); break;
1670                                 case Mode.I2_U8: ec.Emit (OpCodes.Conv_I8); break;
1671                                 case Mode.I2_CH: ec.Emit (OpCodes.Conv_U2); break;
1672
1673                                 case Mode.U2_I1: ec.Emit (OpCodes.Conv_I1); break;
1674                                 case Mode.U2_U1: ec.Emit (OpCodes.Conv_U1); break;
1675                                 case Mode.U2_I2: ec.Emit (OpCodes.Conv_I2); break;
1676                                 case Mode.U2_CH: /* nothing */ break;
1677
1678                                 case Mode.I4_I1: ec.Emit (OpCodes.Conv_I1); break;
1679                                 case Mode.I4_U1: ec.Emit (OpCodes.Conv_U1); break;
1680                                 case Mode.I4_I2: ec.Emit (OpCodes.Conv_I2); break;
1681                                 case Mode.I4_U4: /* nothing */ break;
1682                                 case Mode.I4_U2: ec.Emit (OpCodes.Conv_U2); break;
1683                                 case Mode.I4_U8: ec.Emit (OpCodes.Conv_I8); break;
1684                                 case Mode.I4_CH: ec.Emit (OpCodes.Conv_U2); break;
1685
1686                                 case Mode.U4_I1: ec.Emit (OpCodes.Conv_I1); break;
1687                                 case Mode.U4_U1: ec.Emit (OpCodes.Conv_U1); break;
1688                                 case Mode.U4_I2: ec.Emit (OpCodes.Conv_I2); break;
1689                                 case Mode.U4_U2: ec.Emit (OpCodes.Conv_U2); break;
1690                                 case Mode.U4_I4: /* nothing */ break;
1691                                 case Mode.U4_CH: ec.Emit (OpCodes.Conv_U2); break;
1692
1693                                 case Mode.I8_I1: ec.Emit (OpCodes.Conv_I1); break;
1694                                 case Mode.I8_U1: ec.Emit (OpCodes.Conv_U1); break;
1695                                 case Mode.I8_I2: ec.Emit (OpCodes.Conv_I2); break;
1696                                 case Mode.I8_U2: ec.Emit (OpCodes.Conv_U2); break;
1697                                 case Mode.I8_I4: ec.Emit (OpCodes.Conv_I4); break;
1698                                 case Mode.I8_U4: ec.Emit (OpCodes.Conv_U4); break;
1699                                 case Mode.I8_U8: /* nothing */ break;
1700                                 case Mode.I8_CH: ec.Emit (OpCodes.Conv_U2); break;
1701                                 case Mode.I8_I: ec.Emit (OpCodes.Conv_U); break;
1702
1703                                 case Mode.U8_I1: ec.Emit (OpCodes.Conv_I1); break;
1704                                 case Mode.U8_U1: ec.Emit (OpCodes.Conv_U1); break;
1705                                 case Mode.U8_I2: ec.Emit (OpCodes.Conv_I2); break;
1706                                 case Mode.U8_U2: ec.Emit (OpCodes.Conv_U2); break;
1707                                 case Mode.U8_I4: ec.Emit (OpCodes.Conv_I4); break;
1708                                 case Mode.U8_U4: ec.Emit (OpCodes.Conv_U4); break;
1709                                 case Mode.U8_I8: /* nothing */ break;
1710                                 case Mode.U8_CH: ec.Emit (OpCodes.Conv_U2); break;
1711                                 case Mode.U8_I: ec.Emit (OpCodes.Conv_U); break;
1712
1713                                 case Mode.CH_I1: ec.Emit (OpCodes.Conv_I1); break;
1714                                 case Mode.CH_U1: ec.Emit (OpCodes.Conv_U1); break;
1715                                 case Mode.CH_I2: ec.Emit (OpCodes.Conv_I2); break;
1716
1717                                 case Mode.R4_I1: ec.Emit (OpCodes.Conv_I1); break;
1718                                 case Mode.R4_U1: ec.Emit (OpCodes.Conv_U1); break;
1719                                 case Mode.R4_I2: ec.Emit (OpCodes.Conv_I2); break;
1720                                 case Mode.R4_U2: ec.Emit (OpCodes.Conv_U2); break;
1721                                 case Mode.R4_I4: ec.Emit (OpCodes.Conv_I4); break;
1722                                 case Mode.R4_U4: ec.Emit (OpCodes.Conv_U4); break;
1723                                 case Mode.R4_I8: ec.Emit (OpCodes.Conv_I8); break;
1724                                 case Mode.R4_U8: ec.Emit (OpCodes.Conv_U8); break;
1725                                 case Mode.R4_CH: ec.Emit (OpCodes.Conv_U2); break;
1726
1727                                 case Mode.R8_I1: ec.Emit (OpCodes.Conv_I1); break;
1728                                 case Mode.R8_U1: ec.Emit (OpCodes.Conv_U1); break;
1729                                 case Mode.R8_I2: ec.Emit (OpCodes.Conv_I2); break;
1730                                 case Mode.R8_U2: ec.Emit (OpCodes.Conv_U2); break;
1731                                 case Mode.R8_I4: ec.Emit (OpCodes.Conv_I4); break;
1732                                 case Mode.R8_U4: ec.Emit (OpCodes.Conv_U4); break;
1733                                 case Mode.R8_I8: ec.Emit (OpCodes.Conv_I8); break;
1734                                 case Mode.R8_U8: ec.Emit (OpCodes.Conv_U8); break;
1735                                 case Mode.R8_CH: ec.Emit (OpCodes.Conv_U2); break;
1736                                 case Mode.R8_R4: ec.Emit (OpCodes.Conv_R4); break;
1737
1738                                 case Mode.I_I8: ec.Emit (OpCodes.Conv_U8); break;
1739                                 }
1740                         }
1741                 }
1742         }
1743
1744         class OpcodeCast : TypeCast
1745         {
1746                 readonly OpCode op;
1747
1748                 public OpcodeCast (Expression child, TypeSpec return_type, OpCode op)
1749                         : base (child, return_type)
1750                 {
1751                         this.op = op;
1752                 }
1753
1754                 protected override Expression DoResolve (ResolveContext ec)
1755                 {
1756                         // This should never be invoked, we are born in fully
1757                         // initialized state.
1758
1759                         return this;
1760                 }
1761
1762                 public override void Emit (EmitContext ec)
1763                 {
1764                         base.Emit (ec);
1765                         ec.Emit (op);
1766                 }
1767
1768                 public TypeSpec UnderlyingType {
1769                         get { return child.Type; }
1770                 }
1771         }
1772
1773         //
1774         // Opcode casts expression with 2 opcodes but only
1775         // single expression tree node
1776         //
1777         class OpcodeCastDuplex : OpcodeCast
1778         {
1779                 readonly OpCode second;
1780
1781                 public OpcodeCastDuplex (Expression child, TypeSpec returnType, OpCode first, OpCode second)
1782                         : base (child, returnType, first)
1783                 {
1784                         this.second = second;
1785                 }
1786
1787                 public override void Emit (EmitContext ec)
1788                 {
1789                         base.Emit (ec);
1790                         ec.Emit (second);
1791                 }
1792         }
1793
1794         /// <summary>
1795         ///   This kind of cast is used to encapsulate a child and cast it
1796         ///   to the class requested
1797         /// </summary>
1798         public sealed class ClassCast : TypeCast {
1799                 readonly bool forced;
1800
1801                 public ClassCast (Expression child, TypeSpec return_type)
1802                         : base (child, return_type)
1803                 {
1804                 }
1805
1806                 public ClassCast (Expression child, TypeSpec return_type, bool forced)
1807                         : base (child, return_type)
1808                 {
1809                         this.forced = forced;
1810                 }
1811
1812                 public override void Emit (EmitContext ec)
1813                 {
1814                         base.Emit (ec);
1815
1816                         bool gen = TypeManager.IsGenericParameter (child.Type);
1817                         if (gen)
1818                                 ec.Emit (OpCodes.Box, child.Type);
1819
1820                         if (type.IsGenericParameter) {
1821                                 ec.Emit (OpCodes.Unbox_Any, type);
1822                                 return;
1823                         }
1824
1825                         if (gen && !forced)
1826                                 return;
1827
1828                         ec.Emit (OpCodes.Castclass, type);
1829                 }
1830         }
1831
1832         //
1833         // Created during resolving pahse when an expression is wrapped or constantified
1834         // and original expression can be used later (e.g. for expression trees)
1835         //
1836         public class ReducedExpression : Expression
1837         {
1838                 sealed class ReducedConstantExpression : EmptyConstantCast
1839                 {
1840                         readonly Expression orig_expr;
1841
1842                         public ReducedConstantExpression (Constant expr, Expression orig_expr)
1843                                 : base (expr, expr.Type)
1844                         {
1845                                 this.orig_expr = orig_expr;
1846                         }
1847
1848                         public override Constant ConvertImplicitly (TypeSpec target_type)
1849                         {
1850                                 Constant c = base.ConvertImplicitly (target_type);
1851                                 if (c != null)
1852                                         c = new ReducedConstantExpression (c, orig_expr);
1853
1854                                 return c;
1855                         }
1856
1857                         public override Expression CreateExpressionTree (ResolveContext ec)
1858                         {
1859                                 return orig_expr.CreateExpressionTree (ec);
1860                         }
1861
1862                         public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
1863                         {
1864                                 Constant c = base.ConvertExplicitly (in_checked_context, target_type);
1865                                 if (c != null)
1866                                         c = new ReducedConstantExpression (c, orig_expr);
1867                                 return c;
1868                         }
1869
1870                         public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
1871                         {
1872                                 //
1873                                 // LAMESPEC: Reduced conditional expression is allowed as an attribute argument
1874                                 //
1875                                 if (orig_expr is Conditional)
1876                                         child.EncodeAttributeValue (rc, enc, targetType);
1877                                 else
1878                                         base.EncodeAttributeValue (rc, enc, targetType);
1879                         }
1880                 }
1881
1882                 sealed class ReducedExpressionStatement : ExpressionStatement
1883                 {
1884                         readonly Expression orig_expr;
1885                         readonly ExpressionStatement stm;
1886
1887                         public ReducedExpressionStatement (ExpressionStatement stm, Expression orig)
1888                         {
1889                                 this.orig_expr = orig;
1890                                 this.stm = stm;
1891                                 this.eclass = stm.eclass;
1892                                 this.type = stm.Type;
1893
1894                                 this.loc = orig.Location;
1895                         }
1896
1897                         public override bool ContainsEmitWithAwait ()
1898                         {
1899                                 return stm.ContainsEmitWithAwait ();
1900                         }
1901
1902                         public override Expression CreateExpressionTree (ResolveContext ec)
1903                         {
1904                                 return orig_expr.CreateExpressionTree (ec);
1905                         }
1906
1907                         protected override Expression DoResolve (ResolveContext ec)
1908                         {
1909                                 return this;
1910                         }
1911
1912                         public override void Emit (EmitContext ec)
1913                         {
1914                                 stm.Emit (ec);
1915                         }
1916
1917                         public override void EmitStatement (EmitContext ec)
1918                         {
1919                                 stm.EmitStatement (ec);
1920                         }
1921                 }
1922
1923                 readonly Expression expr, orig_expr;
1924
1925                 private ReducedExpression (Expression expr, Expression orig_expr)
1926                 {
1927                         this.expr = expr;
1928                         this.eclass = expr.eclass;
1929                         this.type = expr.Type;
1930                         this.orig_expr = orig_expr;
1931                         this.loc = orig_expr.Location;
1932                 }
1933
1934                 #region Properties
1935
1936                 public Expression OriginalExpression {
1937                         get {
1938                                 return orig_expr;
1939                         }
1940                 }
1941
1942                 #endregion
1943
1944                 public override bool ContainsEmitWithAwait ()
1945                 {
1946                         return expr.ContainsEmitWithAwait ();
1947                 }
1948
1949                 //
1950                 // Creates fully resolved expression switcher
1951                 //
1952                 public static Constant Create (Constant expr, Expression original_expr)
1953                 {
1954                         if (expr.eclass == ExprClass.Unresolved)
1955                                 throw new ArgumentException ("Unresolved expression");
1956
1957                         return new ReducedConstantExpression (expr, original_expr);
1958                 }
1959
1960                 public static ExpressionStatement Create (ExpressionStatement s, Expression orig)
1961                 {
1962                         return new ReducedExpressionStatement (s, orig);
1963                 }
1964
1965                 public static Expression Create (Expression expr, Expression original_expr)
1966                 {
1967                         return Create (expr, original_expr, true);
1968                 }
1969
1970                 //
1971                 // Creates unresolved reduce expression. The original expression has to be
1972                 // already resolved. Created expression is constant based based on `expr'
1973                 // value unless canBeConstant is used
1974                 //
1975                 public static Expression Create (Expression expr, Expression original_expr, bool canBeConstant)
1976                 {
1977                         if (canBeConstant) {
1978                                 Constant c = expr as Constant;
1979                                 if (c != null)
1980                                         return Create (c, original_expr);
1981                         }
1982
1983                         ExpressionStatement s = expr as ExpressionStatement;
1984                         if (s != null)
1985                                 return Create (s, original_expr);
1986
1987                         if (expr.eclass == ExprClass.Unresolved)
1988                                 throw new ArgumentException ("Unresolved expression");
1989
1990                         return new ReducedExpression (expr, original_expr);
1991                 }
1992
1993                 public override Expression CreateExpressionTree (ResolveContext ec)
1994                 {
1995                         return orig_expr.CreateExpressionTree (ec);
1996                 }
1997
1998                 protected override Expression DoResolve (ResolveContext ec)
1999                 {
2000                         return this;
2001                 }
2002
2003                 public override void Emit (EmitContext ec)
2004                 {
2005                         expr.Emit (ec);
2006                 }
2007
2008                 public override void EmitBranchable (EmitContext ec, Label target, bool on_true)
2009                 {
2010                         expr.EmitBranchable (ec, target, on_true);
2011                 }
2012
2013                 public override SLE.Expression MakeExpression (BuilderContext ctx)
2014                 {
2015                         return orig_expr.MakeExpression (ctx);
2016                 }
2017         }
2018
2019         //
2020         // Standard composite pattern
2021         //
2022         public abstract class CompositeExpression : Expression
2023         {
2024                 protected Expression expr;
2025
2026                 protected CompositeExpression (Expression expr)
2027                 {
2028                         this.expr = expr;
2029                         this.loc = expr.Location;
2030                 }
2031
2032                 public override bool ContainsEmitWithAwait ()
2033                 {
2034                         return expr.ContainsEmitWithAwait ();
2035                 }
2036
2037                 public override Expression CreateExpressionTree (ResolveContext rc)
2038                 {
2039                         return expr.CreateExpressionTree (rc);
2040                 }
2041
2042                 public Expression Child {
2043                         get { return expr; }
2044                 }
2045
2046                 protected override Expression DoResolve (ResolveContext rc)
2047                 {
2048                         expr = expr.Resolve (rc);
2049                         if (expr != null) {
2050                                 type = expr.Type;
2051                                 eclass = expr.eclass;
2052                         }
2053
2054                         return this;
2055                 }
2056
2057                 public override void Emit (EmitContext ec)
2058                 {
2059                         expr.Emit (ec);
2060                 }
2061
2062                 public override bool IsNull {
2063                         get { return expr.IsNull; }
2064                 }
2065         }
2066
2067         //
2068         // Base of expressions used only to narrow resolve flow
2069         //
2070         public abstract class ShimExpression : Expression
2071         {
2072                 protected Expression expr;
2073
2074                 protected ShimExpression (Expression expr)
2075                 {
2076                         this.expr = expr;
2077                 }
2078
2079                 public Expression Expr {
2080                         get {
2081                                 return expr;
2082                         }
2083                 }
2084
2085                 protected override void CloneTo (CloneContext clonectx, Expression t)
2086                 {
2087                         if (expr == null)
2088                                 return;
2089
2090                         ShimExpression target = (ShimExpression) t;
2091                         target.expr = expr.Clone (clonectx);
2092                 }
2093
2094                 public override bool ContainsEmitWithAwait ()
2095                 {
2096                         return expr.ContainsEmitWithAwait ();
2097                 }
2098
2099                 public override Expression CreateExpressionTree (ResolveContext ec)
2100                 {
2101                         throw new NotSupportedException ("ET");
2102                 }
2103
2104                 public override void Emit (EmitContext ec)
2105                 {
2106                         throw new InternalErrorException ("Missing Resolve call");
2107                 }
2108
2109         }
2110
2111         //
2112         // Unresolved type name expressions
2113         //
2114         public abstract class ATypeNameExpression : FullNamedExpression
2115         {
2116                 string name;
2117                 protected TypeArguments targs;
2118
2119                 protected ATypeNameExpression (string name, Location l)
2120                 {
2121                         this.name = name;
2122                         loc = l;
2123                 }
2124
2125                 protected ATypeNameExpression (string name, TypeArguments targs, Location l)
2126                 {
2127                         this.name = name;
2128                         this.targs = targs;
2129                         loc = l;
2130                 }
2131
2132                 protected ATypeNameExpression (string name, int arity, Location l)
2133                         : this (name, new UnboundTypeArguments (arity), l)
2134                 {
2135                 }
2136
2137                 #region Properties
2138
2139                 protected int Arity {
2140                         get {
2141                                 return targs == null ? 0 : targs.Count;
2142                         }
2143                 }
2144
2145                 public bool HasTypeArguments {
2146                         get {
2147                                 return targs != null && !targs.IsEmpty;
2148                         }
2149                 }
2150
2151                 public string Name {
2152                         get {
2153                                 return name;
2154                         }
2155                         set {
2156                                 name = value;
2157                         }
2158                 }
2159
2160                 public TypeArguments TypeArguments {
2161                         get {
2162                                 return targs;
2163                         }
2164                 }
2165
2166                 #endregion
2167
2168                 public override bool Equals (object obj)
2169                 {
2170                         ATypeNameExpression atne = obj as ATypeNameExpression;
2171                         return atne != null && atne.Name == Name &&
2172                                 (targs == null || targs.Equals (atne.targs));
2173                 }
2174
2175                 public override int GetHashCode ()
2176                 {
2177                         return Name.GetHashCode ();
2178                 }
2179
2180                 // TODO: Move it to MemberCore
2181                 public static string GetMemberType (MemberCore mc)
2182                 {
2183                         if (mc is Property)
2184                                 return "property";
2185                         if (mc is Indexer)
2186                                 return "indexer";
2187                         if (mc is FieldBase)
2188                                 return "field";
2189                         if (mc is MethodCore)
2190                                 return "method";
2191                         if (mc is EnumMember)
2192                                 return "enum";
2193                         if (mc is Event)
2194                                 return "event";
2195
2196                         return "type";
2197                 }
2198
2199                 public override string GetSignatureForError ()
2200                 {
2201                         if (targs != null) {
2202                                 return Name + "<" + targs.GetSignatureForError () + ">";
2203                         }
2204
2205                         return Name;
2206                 }
2207
2208                 public abstract Expression LookupNameExpression (ResolveContext rc, MemberLookupRestrictions restriction);
2209         }
2210
2211         /// <summary>
2212         ///   SimpleName expressions are formed of a single word and only happen at the beginning
2213         ///   of a dotted-name.
2214         /// </summary>
2215         public class SimpleName : ATypeNameExpression
2216         {
2217                 public SimpleName (string name, Location l)
2218                         : base (name, l)
2219                 {
2220                 }
2221
2222                 public SimpleName (string name, TypeArguments args, Location l)
2223                         : base (name, args, l)
2224                 {
2225                 }
2226
2227                 public SimpleName (string name, int arity, Location l)
2228                         : base (name, arity, l)
2229                 {
2230                 }
2231
2232                 public SimpleName GetMethodGroup ()
2233                 {
2234                         return new SimpleName (Name, targs, loc);
2235                 }
2236
2237                 protected override Expression DoResolve (ResolveContext rc)
2238                 {
2239                         var e = SimpleNameResolve (rc, null, false);
2240
2241                         var fe = e as FieldExpr;
2242                         if (fe != null) {
2243                                 fe.VerifyAssignedStructField (rc, null);
2244                         }
2245
2246                         return e;
2247                 }
2248
2249                 public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
2250                 {
2251                         return SimpleNameResolve (ec, right_side, false);
2252                 }
2253
2254                 protected virtual void Error_TypeOrNamespaceNotFound (IMemberContext ctx)
2255                 {
2256                         if (ctx.CurrentType != null) {
2257                                 if (ctx.CurrentMemberDefinition != null) {
2258                                         MemberCore mc = ctx.CurrentMemberDefinition.Parent.GetDefinition (Name);
2259                                         if (mc != null) {
2260                                                 Error_UnexpectedKind (ctx.Module.Compiler.Report, mc, "type", GetMemberType (mc), loc);
2261                                                 return;
2262                                         }
2263                                 }
2264                         }
2265
2266                         var retval = ctx.LookupNamespaceOrType (Name, Arity, LookupMode.IgnoreAccessibility, loc);
2267                         if (retval != null) {
2268                                 ctx.Module.Compiler.Report.SymbolRelatedToPreviousError (retval.Type);
2269                                 ErrorIsInaccesible (ctx, retval.GetSignatureForError (), loc);
2270                                 return;
2271                         }
2272
2273                         retval = ctx.LookupNamespaceOrType (Name, -System.Math.Max (1, Arity), LookupMode.Probing, loc);
2274                         if (retval != null) {
2275                                 Error_TypeArgumentsCannotBeUsed (ctx, retval.Type, Arity, loc);
2276                                 return;
2277                         }
2278
2279                         NamespaceContainer.Error_NamespaceNotFound (loc, Name, ctx.Module.Compiler.Report);
2280                 }
2281
2282                 public override FullNamedExpression ResolveAsTypeOrNamespace (IMemberContext ec)
2283                 {
2284                         FullNamedExpression fne = ec.LookupNamespaceOrType (Name, Arity, LookupMode.Normal, loc);
2285
2286                         if (fne != null) {
2287                                 if (fne.Type != null && Arity > 0) {
2288                                         if (HasTypeArguments) {
2289                                                 GenericTypeExpr ct = new GenericTypeExpr (fne.Type, targs, loc);
2290                                                 if (ct.ResolveAsType (ec) == null)
2291                                                         return null;
2292
2293                                                 return ct;
2294                                         }
2295
2296                                         return new GenericOpenTypeExpr (fne.Type, loc);
2297                                 }
2298
2299                                 //
2300                                 // dynamic namespace is ignored when dynamic is allowed (does not apply to types)
2301                                 //
2302                                 if (!(fne is Namespace))
2303                                         return fne;
2304                         }
2305
2306                         if (Arity == 0 && Name == "dynamic" && ec.Module.Compiler.Settings.Version > LanguageVersion.V_3) {
2307                                 if (!ec.Module.PredefinedAttributes.Dynamic.IsDefined) {
2308                                         ec.Module.Compiler.Report.Error (1980, Location,
2309                                                 "Dynamic keyword requires `{0}' to be defined. Are you missing System.Core.dll assembly reference?",
2310                                                 ec.Module.PredefinedAttributes.Dynamic.GetSignatureForError ());
2311                                 }
2312
2313                                 fne = new DynamicTypeExpr (loc);
2314                                 fne.ResolveAsType (ec);
2315                         }
2316
2317                         if (fne != null)
2318                                 return fne;
2319
2320                         Error_TypeOrNamespaceNotFound (ec);
2321                         return null;
2322                 }
2323
2324                 public bool IsPossibleTypeOrNamespace (IMemberContext mc)
2325                 {
2326                         return mc.LookupNamespaceOrType (Name, Arity, LookupMode.Probing, loc) != null;
2327                 }
2328
2329                 public override Expression LookupNameExpression (ResolveContext rc, MemberLookupRestrictions restrictions)
2330                 {
2331                         int lookup_arity = Arity;
2332                         bool errorMode = false;
2333                         Expression e;
2334                         Block current_block = rc.CurrentBlock;
2335                         INamedBlockVariable variable = null;
2336                         bool variable_found = false;
2337
2338                         while (true) {
2339                                 //
2340                                 // Stage 1: binding to local variables or parameters
2341                                 //
2342                                 // LAMESPEC: It should take invocableOnly into account but that would break csc compatibility
2343                                 //
2344                                 if (current_block != null && lookup_arity == 0) {
2345                                         if (current_block.ParametersBlock.TopBlock.GetLocalName (Name, current_block.Original, ref variable)) {
2346                                                 if (!variable.IsDeclared) {
2347                                                         // We found local name in accessible block but it's not
2348                                                         // initialized yet, maybe the user wanted to bind to something else
2349                                                         errorMode = true;
2350                                                         variable_found = true;
2351                                                 } else {
2352                                                         e = variable.CreateReferenceExpression (rc, loc);
2353                                                         if (e != null) {
2354                                                                 if (Arity > 0)
2355                                                                         Error_TypeArgumentsCannotBeUsed (rc, "variable", Name, loc);
2356
2357                                                                 return e;
2358                                                         }
2359                                                 }
2360                                         }
2361                                 }
2362
2363                                 //
2364                                 // Stage 2: Lookup members if we are inside a type up to top level type for nested types
2365                                 //
2366                                 TypeSpec member_type = rc.CurrentType;
2367                                 for (; member_type != null; member_type = member_type.DeclaringType) {
2368                                         e = MemberLookup (rc, errorMode, member_type, Name, lookup_arity, restrictions, loc);
2369                                         if (e == null)
2370                                                 continue;
2371
2372                                         var me = e as MemberExpr;
2373                                         if (me == null) {
2374                                                 // The name matches a type, defer to ResolveAsTypeStep
2375                                                 if (e is TypeExpr)
2376                                                         break;
2377
2378                                                 continue;
2379                                         }
2380
2381                                         if (errorMode) {
2382                                                 if (variable != null) {
2383                                                         if (me is FieldExpr || me is ConstantExpr || me is EventExpr || me is PropertyExpr) {
2384                                                                 rc.Report.Error (844, loc,
2385                                                                         "A local variable `{0}' cannot be used before it is declared. Consider renaming the local variable when it hides the member `{1}'",
2386                                                                         Name, me.GetSignatureForError ());
2387                                                         } else {
2388                                                                 break;
2389                                                         }
2390                                                 } else if (me is MethodGroupExpr) {
2391                                                         // Leave it to overload resolution to report correct error
2392                                                 } else {
2393                                                         // TODO: rc.Report.SymbolRelatedToPreviousError ()
2394                                                         ErrorIsInaccesible (rc, me.GetSignatureForError (), loc);
2395                                                 }
2396                                         } else {
2397                                                 // LAMESPEC: again, ignores InvocableOnly
2398                                                 if (variable != null) {
2399                                                         rc.Report.SymbolRelatedToPreviousError (variable.Location, Name);
2400                                                         rc.Report.Error (135, loc, "`{0}' conflicts with a declaration in a child block", Name);
2401                                                 }
2402
2403                                                 //
2404                                                 // MemberLookup does not check accessors availability, this is actually needed for properties only
2405                                                 //
2406                                                 var pe = me as PropertyExpr;
2407                                                 if (pe != null) {
2408
2409                                                         // Break as there is no other overload available anyway
2410                                                         if ((restrictions & MemberLookupRestrictions.ReadAccess) != 0) {
2411                                                                 if (!pe.PropertyInfo.HasGet || !pe.PropertyInfo.Get.IsAccessible (rc))
2412                                                                         break;
2413
2414                                                                 pe.Getter = pe.PropertyInfo.Get;
2415                                                         } else {
2416                                                                 if (!pe.PropertyInfo.HasSet || !pe.PropertyInfo.Set.IsAccessible (rc))
2417                                                                         break;
2418
2419                                                                 pe.Setter = pe.PropertyInfo.Set;
2420                                                         }
2421                                                 }
2422                                         }
2423
2424                                         // TODO: It's used by EventExpr -> FieldExpr transformation only
2425                                         // TODO: Should go to MemberAccess
2426                                         me = me.ResolveMemberAccess (rc, null, null);
2427
2428                                         if (Arity > 0) {
2429                                                 targs.Resolve (rc);
2430                                                 me.SetTypeArguments (rc, targs);
2431                                         }
2432
2433                                         return me;
2434                                 }
2435
2436                                 //
2437                                 // Stage 3: Lookup nested types, namespaces and type parameters in the context
2438                                 //
2439                                 if ((restrictions & MemberLookupRestrictions.InvocableOnly) == 0 && !variable_found) {
2440                                         if (IsPossibleTypeOrNamespace (rc)) {
2441                                                 if (variable != null) {
2442                                                         rc.Report.SymbolRelatedToPreviousError (variable.Location, Name);
2443                                                         rc.Report.Error (135, loc, "`{0}' conflicts with a declaration in a child block", Name);
2444                                                 }
2445
2446                                                 return ResolveAsTypeOrNamespace (rc);
2447                                         }
2448                                 }
2449
2450                                 if (errorMode) {
2451                                         if (variable_found) {
2452                                                 rc.Report.Error (841, loc, "A local variable `{0}' cannot be used before it is declared", Name);
2453                                         } else {
2454                                                 if (Arity > 0) {
2455                                                         TypeParameter[] tparams = rc.CurrentTypeParameters;
2456                                                         if (tparams != null) {
2457                                                                 foreach (var ctp in tparams) {
2458                                                                         if (ctp.Name == Name) {
2459                                                                                 Error_TypeArgumentsCannotBeUsed (rc, "type parameter", Name, loc);
2460                                                                                 return null;
2461                                                                         }
2462                                                                 }
2463                                                         }
2464
2465                                                         var ct = rc.CurrentType;
2466                                                         do {
2467                                                                 if (ct.MemberDefinition.TypeParametersCount > 0) {
2468                                                                         foreach (var ctp in ct.MemberDefinition.TypeParameters) {
2469                                                                                 if (ctp.Name == Name) {
2470                                                                                         Error_TypeArgumentsCannotBeUsed (rc, "type parameter", Name, loc);
2471                                                                                         return null;
2472                                                                                 }
2473                                                                         }
2474                                                                 }
2475
2476                                                                 ct = ct.DeclaringType;
2477                                                         } while (ct != null);
2478                                                 }
2479
2480                                                 if ((restrictions & MemberLookupRestrictions.InvocableOnly) == 0) {
2481                                                         e = rc.LookupNamespaceOrType (Name, Arity, LookupMode.IgnoreAccessibility, loc);
2482                                                         if (e != null) {
2483                                                                 rc.Report.SymbolRelatedToPreviousError (e.Type);
2484                                                                 ErrorIsInaccesible (rc, e.GetSignatureForError (), loc);
2485                                                                 return e;
2486                                                         }
2487                                                 }
2488
2489                                                 e = rc.LookupNamespaceOrType (Name, -System.Math.Max (1, Arity), LookupMode.Probing, loc);
2490                                                 if (e != null) {
2491                                                         if (!(e is TypeExpr) || (restrictions & MemberLookupRestrictions.InvocableOnly) == 0 || !e.Type.IsDelegate) {
2492                                                                 Error_TypeArgumentsCannotBeUsed (rc, e.Type, Arity, loc);
2493                                                                 return e;
2494                                                         }
2495                                                 }
2496
2497                                                 rc.Report.Error (103, loc, "The name `{0}' does not exist in the current context", Name);
2498                                         }
2499
2500                                         return ErrorExpression.Instance;
2501                                 }
2502
2503                                 if (rc.Module.Evaluator != null) {
2504                                         var fi = rc.Module.Evaluator.LookupField (Name);
2505                                         if (fi != null)
2506                                                 return new FieldExpr (fi.Item1, loc);
2507                                 }
2508
2509                                 lookup_arity = 0;
2510                                 errorMode = true;
2511                         }
2512                 }
2513
2514                 Expression SimpleNameResolve (ResolveContext ec, Expression right_side, bool intermediate)
2515                 {
2516                         Expression e = LookupNameExpression (ec, right_side == null ? MemberLookupRestrictions.ReadAccess : MemberLookupRestrictions.None);
2517
2518                         if (e == null)
2519                                 return null;
2520
2521                         if (right_side != null) {
2522                                 if (e is TypeExpr) {
2523                                     e.Error_UnexpectedKind (ec, ResolveFlags.VariableOrValue, loc);
2524                                     return null;
2525                                 }
2526
2527                                 e = e.ResolveLValue (ec, right_side);
2528                         } else {
2529                                 e = e.Resolve (ec);
2530                         }
2531
2532                         //if (ec.CurrentBlock == null || ec.CurrentBlock.CheckInvariantMeaningInBlock (Name, e, Location))
2533                         return e;
2534                 }
2535
2536                 public override object Accept (StructuralVisitor visitor)
2537                 {
2538                         return visitor.Visit (this);
2539                 }
2540         }
2541
2542         /// <summary>
2543         ///   Represents a namespace or a type.  The name of the class was inspired by
2544         ///   section 10.8.1 (Fully Qualified Names).
2545         /// </summary>
2546         public abstract class FullNamedExpression : Expression
2547         {
2548                 protected override void CloneTo (CloneContext clonectx, Expression target)
2549                 {
2550                         // Do nothing, most unresolved type expressions cannot be
2551                         // resolved to different type
2552                 }
2553
2554                 public override bool ContainsEmitWithAwait ()
2555                 {
2556                         return false;
2557                 }
2558
2559                 public override Expression CreateExpressionTree (ResolveContext ec)
2560                 {
2561                         throw new NotSupportedException ("ET");
2562                 }
2563
2564                 public abstract FullNamedExpression ResolveAsTypeOrNamespace (IMemberContext mc);
2565
2566                 //
2567                 // This is used to resolve the expression as a type, a null
2568                 // value will be returned if the expression is not a type
2569                 // reference
2570                 //
2571                 public override TypeSpec ResolveAsType (IMemberContext mc)
2572                 {
2573                         FullNamedExpression fne = ResolveAsTypeOrNamespace (mc);
2574
2575                         if (fne == null)
2576                                 return null;
2577
2578                         TypeExpr te = fne as TypeExpr;
2579                         if (te == null) {
2580                                 fne.Error_UnexpectedKind (mc.Module.Compiler.Report, null, "type", loc);
2581                                 return null;
2582                         }
2583
2584                         te.loc = loc;
2585
2586                         type = te.Type;
2587
2588                         var dep = type.GetMissingDependencies ();
2589                         if (dep != null) {
2590                                 ImportedTypeDefinition.Error_MissingDependency (mc, dep, loc);
2591                         }
2592
2593                         //
2594                         // Obsolete checks cannot be done when resolving base context as they
2595                         // require type dependencies to be set but we are in process of resolving them
2596                         //
2597                         if (!(mc is TypeContainer.BaseContext)) {
2598                                 ObsoleteAttribute obsolete_attr = type.GetAttributeObsolete ();
2599                                 if (obsolete_attr != null && !mc.IsObsolete) {
2600                                         AttributeTester.Report_ObsoleteMessage (obsolete_attr, te.GetSignatureForError (), Location, mc.Module.Compiler.Report);
2601                                 }
2602                         }
2603
2604                         return type;
2605                 }
2606
2607
2608                 public override void Emit (EmitContext ec)
2609                 {
2610                         throw new InternalErrorException ("FullNamedExpression `{0}' found in resolved tree",
2611                                 GetSignatureForError ());
2612                 }
2613         }
2614
2615         /// <summary>
2616         ///   Expression that evaluates to a type
2617         /// </summary>
2618         public abstract class TypeExpr : FullNamedExpression
2619         {
2620                 public sealed override FullNamedExpression ResolveAsTypeOrNamespace (IMemberContext mc)
2621                 {
2622                         ResolveAsType (mc);
2623                         return this;
2624                 }
2625
2626                 protected sealed override Expression DoResolve (ResolveContext ec)
2627                 {
2628                         ResolveAsType (ec);
2629                         return this;
2630                 }
2631
2632                 public override bool Equals (object obj)
2633                 {
2634                         TypeExpr tobj = obj as TypeExpr;
2635                         if (tobj == null)
2636                                 return false;
2637
2638                         return Type == tobj.Type;
2639                 }
2640
2641                 public override int GetHashCode ()
2642                 {
2643                         return Type.GetHashCode ();
2644                 }
2645         }
2646
2647         /// <summary>
2648         ///   Fully resolved Expression that already evaluated to a type
2649         /// </summary>
2650         public class TypeExpression : TypeExpr
2651         {
2652                 public TypeExpression (TypeSpec t, Location l)
2653                 {
2654                         Type = t;
2655                         eclass = ExprClass.Type;
2656                         loc = l;
2657                 }
2658
2659                 public sealed override TypeSpec ResolveAsType (IMemberContext ec)
2660                 {
2661                         return type;
2662                 }
2663         }
2664
2665         /// <summary>
2666         ///   This class denotes an expression which evaluates to a member
2667         ///   of a struct or a class.
2668         /// </summary>
2669         public abstract class MemberExpr : Expression, OverloadResolver.IInstanceQualifier
2670         {
2671                 //
2672                 // An instance expression associated with this member, if it's a
2673                 // non-static member
2674                 //
2675                 public Expression InstanceExpression;
2676
2677                 /// <summary>
2678                 ///   The name of this member.
2679                 /// </summary>
2680                 public abstract string Name {
2681                         get;
2682                 }
2683
2684                 //
2685                 // When base.member is used
2686                 //
2687                 public bool IsBase {
2688                         get { return InstanceExpression is BaseThis; }
2689                 }
2690
2691                 /// <summary>
2692                 ///   Whether this is an instance member.
2693                 /// </summary>
2694                 public abstract bool IsInstance {
2695                         get;
2696                 }
2697
2698                 /// <summary>
2699                 ///   Whether this is a static member.
2700                 /// </summary>
2701                 public abstract bool IsStatic {
2702                         get;
2703                 }
2704
2705                 protected abstract TypeSpec DeclaringType {
2706                         get;
2707                 }
2708
2709                 TypeSpec OverloadResolver.IInstanceQualifier.InstanceType {
2710                         get {
2711                                 return InstanceExpression.Type;
2712                         }
2713                 }
2714
2715                 //
2716                 // Converts best base candidate for virtual method starting from QueriedBaseType
2717                 //
2718                 protected MethodSpec CandidateToBaseOverride (ResolveContext rc, MethodSpec method)
2719                 {
2720                         //
2721                         // Only when base.member is used and method is virtual
2722                         //
2723                         if (!IsBase)
2724                                 return method;
2725
2726                         //
2727                         // Overload resulution works on virtual or non-virtual members only (no overrides). That
2728                         // means for base.member access we have to find the closest match after we found best candidate
2729                         //
2730                         if ((method.Modifiers & (Modifiers.ABSTRACT | Modifiers.VIRTUAL | Modifiers.OVERRIDE)) != 0) {
2731                                 //
2732                                 // The method could already be what we are looking for
2733                                 //
2734                                 TypeSpec[] targs = null;
2735                                 if (method.DeclaringType != InstanceExpression.Type) {
2736                                         var base_override = MemberCache.FindMember (InstanceExpression.Type, new MemberFilter (method), BindingRestriction.InstanceOnly) as MethodSpec;
2737                                         if (base_override != null && base_override.DeclaringType != method.DeclaringType) {
2738                                                 if (base_override.IsGeneric)
2739                                                         targs = method.TypeArguments;
2740
2741                                                 method = base_override;
2742                                         }
2743                                 }
2744
2745                                 // TODO: For now we do it for any hoisted call even if it's needed for
2746                                 // hoisted stories only but that requires a new expression wrapper
2747                                 if (rc.CurrentAnonymousMethod != null) {
2748                                         if (targs == null && method.IsGeneric) {
2749                                                 targs = method.TypeArguments;
2750                                                 method = method.GetGenericMethodDefinition ();
2751                                         }
2752
2753                                         if (method.Parameters.HasArglist)
2754                                                 throw new NotImplementedException ("__arglist base call proxy");
2755
2756                                         method = rc.CurrentMemberDefinition.Parent.PartialContainer.CreateHoistedBaseCallProxy (rc, method);
2757
2758                                         // Ideally this should apply to any proxy rewrite but in the case of unary mutators on
2759                                         // get/set member expressions second call would fail to proxy because left expression
2760                                         // would be of 'this' and not 'base'
2761                                         if (rc.CurrentType.IsStruct)
2762                                                 InstanceExpression = new This (loc).Resolve (rc);
2763                                 }
2764
2765                                 if (targs != null)
2766                                         method = method.MakeGenericMethod (rc, targs);
2767                         }
2768
2769                         //
2770                         // Only base will allow this invocation to happen.
2771                         //
2772                         if (method.IsAbstract) {
2773                                 Error_CannotCallAbstractBase (rc, method.GetSignatureForError ());
2774                         }
2775
2776                         return method;
2777                 }
2778
2779                 protected void CheckProtectedMemberAccess (ResolveContext rc, MemberSpec member)
2780                 {
2781                         if (InstanceExpression == null)
2782                                 return;
2783
2784                         if ((member.Modifiers & Modifiers.PROTECTED) != 0 && !(InstanceExpression is This)) {
2785                                 if (!CheckProtectedMemberAccess (rc, member, InstanceExpression.Type)) {
2786                                         Error_ProtectedMemberAccess (rc, member, InstanceExpression.Type, loc);
2787                                 }
2788                         }
2789                 }
2790
2791                 bool OverloadResolver.IInstanceQualifier.CheckProtectedMemberAccess (ResolveContext rc, MemberSpec member)
2792                 {
2793                         if (InstanceExpression == null)
2794                                 return true;
2795
2796                         return InstanceExpression is This || CheckProtectedMemberAccess (rc, member, InstanceExpression.Type);
2797                 }
2798
2799                 public static bool CheckProtectedMemberAccess<T> (ResolveContext rc, T member, TypeSpec qualifier) where T : MemberSpec
2800                 {
2801                         var ct = rc.CurrentType;
2802                         if (ct == qualifier)
2803                                 return true;
2804
2805                         if ((member.Modifiers & Modifiers.INTERNAL) != 0 && member.DeclaringType.MemberDefinition.IsInternalAsPublic (ct.MemberDefinition.DeclaringAssembly))
2806                                 return true;
2807
2808                         qualifier = qualifier.GetDefinition ();
2809                         if (ct != qualifier && !IsSameOrBaseQualifier (ct, qualifier)) {
2810                                 return false;
2811                         }
2812
2813                         return true;
2814                 }
2815
2816                 public override bool ContainsEmitWithAwait ()
2817                 {
2818                         return InstanceExpression != null && InstanceExpression.ContainsEmitWithAwait ();
2819                 }
2820
2821                 static bool IsSameOrBaseQualifier (TypeSpec type, TypeSpec qtype)
2822                 {
2823                         do {
2824                                 type = type.GetDefinition ();
2825
2826                                 if (type == qtype || TypeManager.IsFamilyAccessible (qtype, type))
2827                                         return true;
2828
2829                                 type = type.DeclaringType;
2830                         } while (type != null);
2831
2832                         return false;
2833                 }
2834
2835                 protected void DoBestMemberChecks<T> (ResolveContext rc, T member) where T : MemberSpec, IInterfaceMemberSpec
2836                 {
2837                         if (InstanceExpression != null) {
2838                                 InstanceExpression = InstanceExpression.Resolve (rc);
2839                                 CheckProtectedMemberAccess (rc, member);
2840                         }
2841
2842                         if (member.MemberType.IsPointer && !rc.IsUnsafe) {
2843                                 UnsafeError (rc, loc);
2844                         }
2845
2846                         var dep = member.GetMissingDependencies ();
2847                         if (dep != null) {
2848                                 ImportedTypeDefinition.Error_MissingDependency (rc, dep, loc);
2849                         }
2850
2851                         if (!rc.IsObsolete) {
2852                                 ObsoleteAttribute oa = member.GetAttributeObsolete ();
2853                                 if (oa != null)
2854                                         AttributeTester.Report_ObsoleteMessage (oa, member.GetSignatureForError (), loc, rc.Report);
2855                         }
2856
2857                         if (!(member is FieldSpec))
2858                                 member.MemberDefinition.SetIsUsed ();
2859                 }
2860
2861                 protected virtual void Error_CannotCallAbstractBase (ResolveContext rc, string name)
2862                 {
2863                         rc.Report.Error (205, loc, "Cannot call an abstract base member `{0}'", name);
2864                 }
2865
2866                 public static void Error_ProtectedMemberAccess (ResolveContext rc, MemberSpec member, TypeSpec qualifier, Location loc)
2867                 {
2868                         rc.Report.SymbolRelatedToPreviousError (member);
2869                         rc.Report.Error (1540, loc,
2870                                 "Cannot access protected member `{0}' via a qualifier of type `{1}'. The qualifier must be of type `{2}' or derived from it",
2871                                 member.GetSignatureForError (), qualifier.GetSignatureForError (), rc.CurrentType.GetSignatureForError ());
2872                 }
2873
2874                 //
2875                 // Implements identicial simple name and type-name
2876                 //
2877                 public Expression ProbeIdenticalTypeName (ResolveContext rc, Expression left, SimpleName name)
2878                 {
2879                         var t = left.Type;
2880                         if (t.Kind == MemberKind.InternalCompilerType || t is ElementTypeSpec || t.Arity > 0)
2881                                 return left;
2882
2883                         // 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
2884                         // a constant, field, property, local variable, or parameter with the same type as the meaning of E as a type-name
2885
2886                         if (left is MemberExpr || left is VariableReference) {
2887                                 var identical_type = rc.LookupNamespaceOrType (name.Name, 0, LookupMode.Probing, loc) as TypeExpr;
2888                                 if (identical_type != null && identical_type.Type == left.Type)
2889                                         return identical_type;
2890                         }
2891
2892                         return left;
2893                 }
2894
2895                 public bool ResolveInstanceExpression (ResolveContext rc, Expression rhs)
2896                 {
2897                         if (IsStatic) {
2898                                 if (InstanceExpression != null) {
2899                                         if (InstanceExpression is TypeExpr) {
2900                                                 var t = InstanceExpression.Type;
2901                                                 do {
2902                                                         ObsoleteAttribute oa = t.GetAttributeObsolete ();
2903                                                         if (oa != null && !rc.IsObsolete) {
2904                                                                 AttributeTester.Report_ObsoleteMessage (oa, t.GetSignatureForError (), loc, rc.Report);
2905                                                         }
2906
2907                                                         t = t.DeclaringType;
2908                                                 } while (t != null);
2909                                         } else {
2910                                                 var runtime_expr = InstanceExpression as RuntimeValueExpression;
2911                                                 if (runtime_expr == null || !runtime_expr.IsSuggestionOnly) {
2912                                                         rc.Report.Error (176, loc,
2913                                                                 "Static member `{0}' cannot be accessed with an instance reference, qualify it with a type name instead",
2914                                                                 GetSignatureForError ());
2915                                                 }
2916                                         }
2917
2918                                         InstanceExpression = null;
2919                                 }
2920
2921                                 return false;
2922                         }
2923
2924                         if (InstanceExpression == null || InstanceExpression is TypeExpr) {
2925                                 if (InstanceExpression != null || !This.IsThisAvailable (rc, true)) {
2926                                         if (rc.HasSet (ResolveContext.Options.FieldInitializerScope))
2927                                                 rc.Report.Error (236, loc,
2928                                                         "A field initializer cannot reference the nonstatic field, method, or property `{0}'",
2929                                                         GetSignatureForError ());
2930                                         else
2931                                                 rc.Report.Error (120, loc,
2932                                                         "An object reference is required to access non-static member `{0}'",
2933                                                         GetSignatureForError ());
2934
2935                                         InstanceExpression = new CompilerGeneratedThis (type, loc).Resolve (rc);
2936                                         return false;
2937                                 }
2938
2939                                 if (!TypeManager.IsFamilyAccessible (rc.CurrentType, DeclaringType)) {
2940                                         rc.Report.Error (38, loc,
2941                                                 "Cannot access a nonstatic member of outer type `{0}' via nested type `{1}'",
2942                                                 DeclaringType.GetSignatureForError (), rc.CurrentType.GetSignatureForError ());
2943                                 }
2944
2945                                 InstanceExpression = new This (loc);
2946                                 if (this is FieldExpr && rc.CurrentBlock.ParametersBlock.TopBlock.ThisVariable != null) {
2947                                         using (rc.Set (ResolveContext.Options.OmitStructFlowAnalysis)) {
2948                                                 InstanceExpression = InstanceExpression.Resolve (rc);
2949                                         }
2950                                 } else {
2951                                         InstanceExpression = InstanceExpression.Resolve (rc);
2952                                 }
2953
2954                                 return false;
2955                         }
2956
2957                         var me = InstanceExpression as MemberExpr;
2958                         if (me != null) {
2959                                 me.ResolveInstanceExpression (rc, rhs);
2960
2961                                 var fe = me as FieldExpr;
2962                                 if (fe != null && fe.IsMarshalByRefAccess (rc)) {
2963                                         rc.Report.SymbolRelatedToPreviousError (me.DeclaringType);
2964                                         rc.Report.Warning (1690, 1, loc,
2965                                                 "Cannot call methods, properties, or indexers on `{0}' because it is a value type member of a marshal-by-reference class",
2966                                                 me.GetSignatureForError ());
2967                                 }
2968
2969                                 return true;
2970                         }
2971
2972                         //
2973                         // Run member-access postponed check once we know that
2974                         // the expression is not field expression which is the only
2975                         // expression which can use uninitialized this
2976                         //
2977                         if (InstanceExpression is This && !(this is FieldExpr) && rc.CurrentBlock.ParametersBlock.TopBlock.ThisVariable != null) {
2978                                 ((This)InstanceExpression).CheckStructThisDefiniteAssignment (rc);
2979                         }
2980
2981                         //
2982                         // Additional checks for l-value member access
2983                         //
2984                         if (rhs != null) {
2985                                 if (InstanceExpression is UnboxCast) {
2986                                         rc.Report.Error (445, InstanceExpression.Location, "Cannot modify the result of an unboxing conversion");
2987                                 }
2988                         }
2989
2990                         return true;
2991                 }
2992
2993                 public virtual MemberExpr ResolveMemberAccess (ResolveContext ec, Expression left, SimpleName original)
2994                 {
2995                         if (left != null && left.IsNull && TypeSpec.IsReferenceType (left.Type)) {
2996                                 ec.Report.Warning (1720, 1, left.Location,
2997                                         "Expression will always cause a `{0}'", "System.NullReferenceException");
2998                         }
2999
3000                         InstanceExpression = left;
3001                         return this;
3002                 }
3003
3004                 protected void EmitInstance (EmitContext ec, bool prepare_for_load)
3005                 {
3006                         TypeSpec instance_type = InstanceExpression.Type;
3007                         if (TypeSpec.IsValueType (instance_type)) {
3008                                 if (InstanceExpression is IMemoryLocation) {
3009                                         ((IMemoryLocation) InstanceExpression).AddressOf (ec, AddressOp.Load);
3010                                 } else {
3011                                         // Cannot release the temporary variable when its address
3012                                         // is required to be on stack for any parent
3013                                         LocalTemporary t = new LocalTemporary (instance_type);
3014                                         InstanceExpression.Emit (ec);
3015                                         t.Store (ec);
3016                                         t.AddressOf (ec, AddressOp.Store);
3017                                 }
3018                         } else {
3019                                 InstanceExpression.Emit (ec);
3020
3021                                 // Only to make verifier happy
3022                                 if (instance_type.IsGenericParameter && !(InstanceExpression is This) && TypeSpec.IsReferenceType (instance_type))
3023                                         ec.Emit (OpCodes.Box, instance_type);
3024                         }
3025
3026                         if (prepare_for_load)
3027                                 ec.Emit (OpCodes.Dup);
3028                 }
3029
3030                 public abstract void SetTypeArguments (ResolveContext ec, TypeArguments ta);
3031         }
3032
3033         public class ExtensionMethodCandidates
3034         {
3035                 NamespaceContainer container;
3036                 Namespace ns;
3037                 IList<MethodSpec> methods;
3038
3039                 public ExtensionMethodCandidates (IList<MethodSpec> methods, NamespaceContainer nsContainer)
3040                         : this (methods, nsContainer, null)
3041                 {
3042                 }
3043
3044                 public ExtensionMethodCandidates (IList<MethodSpec> methods, NamespaceContainer nsContainer, Namespace ns)
3045                 {
3046                         this.methods = methods;
3047                         this.container = nsContainer;
3048                         this.ns = ns;
3049                 }
3050
3051                 public NamespaceContainer Container {
3052                         get {
3053                                 return container;
3054                         }
3055                 }
3056
3057                 public bool HasUninspectedMembers { get; set; }
3058
3059                 public Namespace Namespace {
3060                         get {
3061                                 return ns;
3062                         }
3063                 }
3064
3065                 public IList<MethodSpec> Methods {
3066                         get {
3067                                 return methods;
3068                         }
3069                 }
3070         }
3071
3072         //
3073         // Represents a group of extension method candidates for whole namespace
3074         //
3075         class ExtensionMethodGroupExpr : MethodGroupExpr, OverloadResolver.IErrorHandler
3076         {
3077                 ExtensionMethodCandidates candidates;
3078                 public readonly Expression ExtensionExpression;
3079
3080                 public ExtensionMethodGroupExpr (ExtensionMethodCandidates candidates, Expression extensionExpr, Location loc)
3081                         : base (candidates.Methods.Cast<MemberSpec>().ToList (), extensionExpr.Type, loc)
3082                 {
3083                         this.candidates = candidates;
3084                         this.ExtensionExpression = extensionExpr;
3085                 }
3086
3087                 public override bool IsStatic {
3088                         get { return true; }
3089                 }
3090
3091                 //
3092                 // For extension methodgroup we are not looking for base members but parent
3093                 // namespace extension methods
3094                 //
3095                 public override IList<MemberSpec> GetBaseMembers (TypeSpec baseType)
3096                 {
3097                         // TODO: candidates are null only when doing error reporting, that's
3098                         // incorrect. We have to discover same extension methods in error mode
3099                         if (candidates == null)
3100                                 return null;
3101
3102                         int arity = type_arguments == null ? 0 : type_arguments.Count;
3103
3104                         //
3105                         // Here we try to resume the search for extension method at the point
3106                         // where the last bunch of candidates was found. It's more tricky than
3107                         // it seems as we have to check both namespace containers and namespace
3108                         // in correct order.
3109                         //
3110                         // Consider:
3111                         //
3112                         // namespace A {
3113                         //      using N1;
3114                         //  namespace B.C.D {
3115                         //              <our first search found candidates in A.B.C.D
3116                         //  }
3117                         // }
3118                         //
3119                         // In the example above namespace A.B.C.D, A.B.C and A.B have to be
3120                         // checked before we hit A.N1 using
3121                         //
3122                         if (candidates.Namespace == null) {
3123                                 Namespace scope;
3124                                 var methods = candidates.Container.NS.LookupExtensionMethod (candidates.Container, ExtensionExpression.Type, Name, arity, out scope);
3125                                 if (methods != null) {
3126                                         candidates = new ExtensionMethodCandidates (null, candidates.Container, scope);
3127                                         return methods.Cast<MemberSpec> ().ToList ();
3128                                 }
3129                         }
3130
3131                         var ns_container = candidates.HasUninspectedMembers ? candidates.Container : candidates.Container.Parent;
3132                         if (ns_container == null)
3133                                 return null;
3134
3135                         candidates = ns_container.LookupExtensionMethod (ExtensionExpression.Type, Name, arity);
3136                         if (candidates == null)
3137                                 return null;
3138
3139                         return candidates.Methods.Cast<MemberSpec> ().ToList ();
3140                 }
3141
3142                 public override MethodGroupExpr LookupExtensionMethod (ResolveContext rc)
3143                 {
3144                         // We are already here
3145                         return null;
3146                 }
3147
3148                 public override MethodGroupExpr OverloadResolve (ResolveContext ec, ref Arguments arguments, OverloadResolver.IErrorHandler ehandler, OverloadResolver.Restrictions restr)
3149                 {
3150                         if (arguments == null)
3151                                 arguments = new Arguments (1);
3152
3153                         arguments.Insert (0, new Argument (ExtensionExpression, Argument.AType.ExtensionType));
3154                         var res = base.OverloadResolve (ec, ref arguments, ehandler ?? this, restr);
3155
3156                         // Store resolved argument and restore original arguments
3157                         if (res == null) {
3158                                 // Clean-up modified arguments for error reporting
3159                                 arguments.RemoveAt (0);
3160                                 return null;
3161                         }
3162
3163                         var me = ExtensionExpression as MemberExpr;
3164                         if (me != null)
3165                                 me.ResolveInstanceExpression (ec, null);
3166
3167                         InstanceExpression = null;
3168                         return this;
3169                 }
3170
3171                 #region IErrorHandler Members
3172
3173                 bool OverloadResolver.IErrorHandler.AmbiguousCandidates (ResolveContext rc, MemberSpec best, MemberSpec ambiguous)
3174                 {
3175                         return false;
3176                 }
3177
3178                 bool OverloadResolver.IErrorHandler.ArgumentMismatch (ResolveContext rc, MemberSpec best, Argument arg, int index)
3179                 {
3180                         rc.Report.SymbolRelatedToPreviousError (best);
3181                         rc.Report.Error (1928, loc,
3182                                 "Type `{0}' does not contain a member `{1}' and the best extension method overload `{2}' has some invalid arguments",
3183                                 queried_type.GetSignatureForError (), Name, best.GetSignatureForError ());
3184
3185                         if (index == 0) {
3186                                 rc.Report.Error (1929, loc,
3187                                         "Extension method instance type `{0}' cannot be converted to `{1}'",
3188                                         arg.Type.GetSignatureForError (), ((MethodSpec)best).Parameters.ExtensionMethodType.GetSignatureForError ());
3189                         }
3190
3191                         return true;
3192                 }
3193
3194                 bool OverloadResolver.IErrorHandler.NoArgumentMatch (ResolveContext rc, MemberSpec best)
3195                 {
3196                         return false;
3197                 }
3198
3199                 bool OverloadResolver.IErrorHandler.TypeInferenceFailed (ResolveContext rc, MemberSpec best)
3200                 {
3201                         return false;
3202                 }
3203
3204                 #endregion
3205         }
3206
3207         /// <summary>
3208         ///   MethodGroupExpr represents a group of method candidates which
3209         ///   can be resolved to the best method overload
3210         /// </summary>
3211         public class MethodGroupExpr : MemberExpr, OverloadResolver.IBaseMembersProvider
3212         {
3213                 protected IList<MemberSpec> Methods;
3214                 MethodSpec best_candidate;
3215                 TypeSpec best_candidate_return;
3216                 protected TypeArguments type_arguments;
3217
3218                 SimpleName simple_name;
3219                 protected TypeSpec queried_type;
3220
3221                 public MethodGroupExpr (IList<MemberSpec> mi, TypeSpec type, Location loc)
3222                 {
3223                         Methods = mi;
3224                         this.loc = loc;
3225                         this.type = InternalType.MethodGroup;
3226
3227                         eclass = ExprClass.MethodGroup;
3228                         queried_type = type;
3229                 }
3230
3231                 public MethodGroupExpr (MethodSpec m, TypeSpec type, Location loc)
3232                         : this (new MemberSpec[] { m }, type, loc)
3233                 {
3234                 }
3235
3236                 #region Properties
3237
3238                 public MethodSpec BestCandidate {
3239                         get {
3240                                 return best_candidate;
3241                         }
3242                 }
3243
3244                 public TypeSpec BestCandidateReturnType {
3245                         get {
3246                                 return best_candidate_return;
3247                         }
3248                 }
3249
3250                 public IList<MemberSpec> Candidates {
3251                         get {
3252                                 return Methods;
3253                         }
3254                 }
3255
3256                 protected override TypeSpec DeclaringType {
3257                         get {
3258                                 return queried_type;
3259                         }
3260                 }
3261
3262                 public override bool IsInstance {
3263                         get {
3264                                 if (best_candidate != null)
3265                                         return !best_candidate.IsStatic;
3266
3267                                 return false;
3268                         }
3269                 }
3270
3271                 public override bool IsStatic {
3272                         get {
3273                                 if (best_candidate != null)
3274                                         return best_candidate.IsStatic;
3275
3276                                 return false;
3277                         }
3278                 }
3279
3280                 public override string Name {
3281                         get {
3282                                 if (best_candidate != null)
3283                                         return best_candidate.Name;
3284
3285                                 // TODO: throw ?
3286                                 return Methods.First ().Name;
3287                         }
3288                 }
3289
3290                 #endregion
3291
3292                 //
3293                 // When best candidate is already know this factory can be used
3294                 // to avoid expensive overload resolution to be called
3295                 //
3296                 // NOTE: InstanceExpression has to be set manually
3297                 //
3298                 public static MethodGroupExpr CreatePredefined (MethodSpec best, TypeSpec queriedType, Location loc)
3299                 {
3300                         return new MethodGroupExpr (best, queriedType, loc) {
3301                                 best_candidate = best,
3302                                 best_candidate_return = best.ReturnType
3303                         };
3304                 }
3305
3306                 public override string GetSignatureForError ()
3307                 {
3308                         if (best_candidate != null)
3309                                 return best_candidate.GetSignatureForError ();
3310
3311                         return Methods.First ().GetSignatureForError ();
3312                 }
3313
3314                 public override Expression CreateExpressionTree (ResolveContext ec)
3315                 {
3316                         if (best_candidate == null) {
3317                                 ec.Report.Error (1953, loc, "An expression tree cannot contain an expression with method group");
3318                                 return null;
3319                         }
3320
3321                         if (best_candidate.IsConditionallyExcluded (ec.Module.Compiler, loc))
3322                                 ec.Report.Error (765, loc,
3323                                         "Partial methods with only a defining declaration or removed conditional methods cannot be used in an expression tree");
3324
3325                         return new TypeOfMethod (best_candidate, loc);
3326                 }
3327
3328                 protected override Expression DoResolve (ResolveContext ec)
3329                 {
3330                         this.eclass = ExprClass.MethodGroup;
3331
3332                         if (InstanceExpression != null) {
3333                                 InstanceExpression = InstanceExpression.Resolve (ec);
3334                                 if (InstanceExpression == null)
3335                                         return null;
3336                         }
3337
3338                         return this;
3339                 }
3340
3341                 public override void Emit (EmitContext ec)
3342                 {
3343                         throw new NotSupportedException ();
3344                 }
3345
3346                 public void EmitCall (EmitContext ec, Arguments arguments)
3347                 {
3348                         var call = new CallEmitter ();
3349                         call.InstanceExpression = InstanceExpression;
3350                         call.Emit (ec, best_candidate, arguments, loc);
3351                 }
3352
3353                 public override void Error_ValueCannotBeConverted (ResolveContext ec, Location loc, TypeSpec target, bool expl)
3354                 {
3355                         ec.Report.Error (428, loc, "Cannot convert method group `{0}' to non-delegate type `{1}'. Consider using parentheses to invoke the method",
3356                                 Name, TypeManager.CSharpName (target));
3357                 }
3358
3359                 public static bool IsExtensionMethodArgument (Expression expr)
3360                 {
3361                         //
3362                         // LAMESPEC: No details about which expressions are not allowed
3363                         //
3364                         return !(expr is TypeExpr) && !(expr is BaseThis);
3365                 }
3366
3367                 /// <summary>
3368                 ///   Find the Applicable Function Members (7.4.2.1)
3369                 ///
3370                 ///   me: Method Group expression with the members to select.
3371                 ///       it might contain constructors or methods (or anything
3372                 ///       that maps to a method).
3373                 ///
3374                 ///   Arguments: ArrayList containing resolved Argument objects.
3375                 ///
3376                 ///   loc: The location if we want an error to be reported, or a Null
3377                 ///        location for "probing" purposes.
3378                 ///
3379                 ///   Returns: The MethodBase (either a ConstructorInfo or a MethodInfo)
3380                 ///            that is the best match of me on Arguments.
3381                 ///
3382                 /// </summary>
3383                 public virtual MethodGroupExpr OverloadResolve (ResolveContext ec, ref Arguments args, OverloadResolver.IErrorHandler cerrors, OverloadResolver.Restrictions restr)
3384                 {
3385                         // TODO: causes issues with probing mode, remove explicit Kind check
3386                         if (best_candidate != null && best_candidate.Kind == MemberKind.Destructor)
3387                                 return this;
3388
3389                         var r = new OverloadResolver (Methods, type_arguments, restr, loc);
3390                         if ((restr & OverloadResolver.Restrictions.NoBaseMembers) == 0) {
3391                                 r.BaseMembersProvider = this;
3392                                 r.InstanceQualifier = this;
3393                         }
3394
3395                         if (cerrors != null)
3396                                 r.CustomErrors = cerrors;
3397
3398                         // TODO: When in probing mode do IsApplicable only and when called again do VerifyArguments for full error reporting
3399                         best_candidate = r.ResolveMember<MethodSpec> (ec, ref args);
3400                         if (best_candidate == null)
3401                                 return r.BestCandidateIsDynamic ? this : null;
3402
3403                         // Overload resolver had to create a new method group, all checks bellow have already been executed
3404                         if (r.BestCandidateNewMethodGroup != null)
3405                                 return r.BestCandidateNewMethodGroup;
3406
3407                         if (best_candidate.Kind == MemberKind.Method && (restr & OverloadResolver.Restrictions.ProbingOnly) == 0) {
3408                                 if (InstanceExpression != null) {
3409                                         if (best_candidate.IsExtensionMethod && args[0].Expr == InstanceExpression) {
3410                                                 InstanceExpression = null;
3411                                         } else {
3412                                                 if (best_candidate.IsStatic && simple_name != null) {
3413                                                         InstanceExpression = ProbeIdenticalTypeName (ec, InstanceExpression, simple_name);
3414                                                 }
3415
3416                                                 InstanceExpression.Resolve (ec);
3417                                         }
3418                                 }
3419
3420                                 ResolveInstanceExpression (ec, null);
3421                         }
3422
3423                         var base_override = CandidateToBaseOverride (ec, best_candidate);
3424                         if (base_override == best_candidate) {
3425                                 best_candidate_return = r.BestCandidateReturnType;
3426                         } else {
3427                                 best_candidate = base_override;
3428                                 best_candidate_return = best_candidate.ReturnType;
3429                         }
3430
3431                         return this;
3432                 }
3433
3434                 public override MemberExpr ResolveMemberAccess (ResolveContext ec, Expression left, SimpleName original)
3435                 {
3436                         simple_name = original;
3437                         return base.ResolveMemberAccess (ec, left, original);
3438                 }
3439
3440                 public override void SetTypeArguments (ResolveContext ec, TypeArguments ta)
3441                 {
3442                         type_arguments = ta;
3443                 }
3444
3445                 #region IBaseMembersProvider Members
3446
3447                 public virtual IList<MemberSpec> GetBaseMembers (TypeSpec baseType)
3448                 {
3449                         return baseType == null ? null : MemberCache.FindMembers (baseType, Methods [0].Name, false);
3450                 }
3451
3452                 public IParametersMember GetOverrideMemberParameters (MemberSpec member)
3453                 {
3454                         if (queried_type == member.DeclaringType)
3455                                 return null;
3456
3457                         return MemberCache.FindMember (queried_type, new MemberFilter ((MethodSpec) member),
3458                                 BindingRestriction.InstanceOnly | BindingRestriction.OverrideOnly) as IParametersMember;
3459                 }
3460
3461                 //
3462                 // Extension methods lookup after ordinary methods candidates failed to apply
3463                 //
3464                 public virtual MethodGroupExpr LookupExtensionMethod (ResolveContext rc)
3465                 {
3466                         if (InstanceExpression == null)
3467                                 return null;
3468
3469                         InstanceExpression = InstanceExpression.Resolve (rc);
3470                         if (!IsExtensionMethodArgument (InstanceExpression))
3471                                 return null;
3472
3473                         int arity = type_arguments == null ? 0 : type_arguments.Count;
3474                         var methods = rc.LookupExtensionMethod (InstanceExpression.Type, Methods[0].Name, arity);
3475                         if (methods == null)
3476                                 return null;
3477
3478                         var emg = new ExtensionMethodGroupExpr (methods, InstanceExpression, loc);
3479                         emg.SetTypeArguments (rc, type_arguments);
3480                         return emg;
3481                 }
3482
3483                 #endregion
3484         }
3485
3486         struct ConstructorInstanceQualifier : OverloadResolver.IInstanceQualifier
3487         {
3488                 public ConstructorInstanceQualifier (TypeSpec type)
3489                         : this ()
3490                 {
3491                         InstanceType = type;
3492                 }
3493
3494                 public TypeSpec InstanceType { get; private set; }
3495
3496                 public bool CheckProtectedMemberAccess (ResolveContext rc, MemberSpec member)
3497                 {
3498                         return MemberExpr.CheckProtectedMemberAccess (rc, member, InstanceType);
3499                 }
3500         }
3501
3502         public struct OverloadResolver
3503         {
3504                 [Flags]
3505                 public enum Restrictions
3506                 {
3507                         None = 0,
3508                         DelegateInvoke = 1,
3509                         ProbingOnly     = 1 << 1,
3510                         CovariantDelegate = 1 << 2,
3511                         NoBaseMembers = 1 << 3,
3512                         BaseMembersIncluded = 1 << 4
3513                 }
3514
3515                 public interface IBaseMembersProvider
3516                 {
3517                         IList<MemberSpec> GetBaseMembers (TypeSpec baseType);
3518                         IParametersMember GetOverrideMemberParameters (MemberSpec member);
3519                         MethodGroupExpr LookupExtensionMethod (ResolveContext rc);
3520                 }
3521
3522                 public interface IErrorHandler
3523                 {
3524                         bool AmbiguousCandidates (ResolveContext rc, MemberSpec best, MemberSpec ambiguous);
3525                         bool ArgumentMismatch (ResolveContext rc, MemberSpec best, Argument a, int index);
3526                         bool NoArgumentMatch (ResolveContext rc, MemberSpec best);
3527                         bool TypeInferenceFailed (ResolveContext rc, MemberSpec best);
3528                 }
3529
3530                 public interface IInstanceQualifier
3531                 {
3532                         TypeSpec InstanceType { get; }
3533                         bool CheckProtectedMemberAccess (ResolveContext rc, MemberSpec member);
3534                 }
3535
3536                 sealed class NoBaseMembers : IBaseMembersProvider
3537                 {
3538                         public static readonly IBaseMembersProvider Instance = new NoBaseMembers ();
3539
3540                         public IList<MemberSpec> GetBaseMembers (TypeSpec baseType)
3541                         {
3542                                 return null;
3543                         }
3544
3545                         public IParametersMember GetOverrideMemberParameters (MemberSpec member)
3546                         {
3547                                 return null;
3548                         }
3549
3550                         public MethodGroupExpr LookupExtensionMethod (ResolveContext rc)
3551                         {
3552                                 return null;
3553                         }
3554                 }
3555
3556                 struct AmbiguousCandidate
3557                 {
3558                         public readonly MemberSpec Member;
3559                         public readonly bool Expanded;
3560                         public readonly AParametersCollection Parameters;
3561
3562                         public AmbiguousCandidate (MemberSpec member, AParametersCollection parameters, bool expanded)
3563                         {
3564                                 Member = member;
3565                                 Parameters = parameters;
3566                                 Expanded = expanded;
3567                         }
3568                 }
3569
3570                 Location loc;
3571                 IList<MemberSpec> members;
3572                 TypeArguments type_arguments;
3573                 IBaseMembersProvider base_provider;
3574                 IErrorHandler custom_errors;
3575                 IInstanceQualifier instance_qualifier;
3576                 Restrictions restrictions;
3577                 MethodGroupExpr best_candidate_extension_group;
3578                 TypeSpec best_candidate_return_type;
3579
3580                 SessionReportPrinter lambda_conv_msgs;
3581                 ReportPrinter prev_recorder;
3582
3583                 public OverloadResolver (IList<MemberSpec> members, Restrictions restrictions, Location loc)
3584                         : this (members, null, restrictions, loc)
3585                 {
3586                 }
3587
3588                 public OverloadResolver (IList<MemberSpec> members, TypeArguments targs, Restrictions restrictions, Location loc)
3589                         : this ()
3590                 {
3591                         if (members == null || members.Count == 0)
3592                                 throw new ArgumentException ("empty members set");
3593
3594                         this.members = members;
3595                         this.loc = loc;
3596                         type_arguments = targs;
3597                         this.restrictions = restrictions;
3598                         if (IsDelegateInvoke)
3599                                 this.restrictions |= Restrictions.NoBaseMembers;
3600
3601                         base_provider = NoBaseMembers.Instance;
3602                 }
3603
3604                 #region Properties
3605
3606                 public IBaseMembersProvider BaseMembersProvider {
3607                         get {
3608                                 return base_provider;
3609                         }
3610                         set {
3611                                 base_provider = value;
3612                         }
3613                 }
3614
3615                 public bool BestCandidateIsDynamic { get; set; }
3616
3617                 //
3618                 // Best candidate was found in newly created MethodGroupExpr, used by extension methods
3619                 //
3620                 public MethodGroupExpr BestCandidateNewMethodGroup {
3621                         get {
3622                                 return best_candidate_extension_group;
3623                         }
3624                 }
3625
3626                 //
3627                 // Return type can be different between best candidate and closest override
3628                 //
3629                 public TypeSpec BestCandidateReturnType {
3630                         get {
3631                                 return best_candidate_return_type;
3632                         }
3633                 }
3634
3635                 public IErrorHandler CustomErrors {
3636                         get {
3637                                 return custom_errors;
3638                         }
3639                         set {
3640                                 custom_errors = value;
3641                         }
3642                 }
3643
3644                 TypeSpec DelegateType {
3645                         get {
3646                                 if ((restrictions & Restrictions.DelegateInvoke) == 0)
3647                                         throw new InternalErrorException ("Not running in delegate mode", loc);
3648
3649                                 return members [0].DeclaringType;
3650                         }
3651                 }
3652
3653                 public IInstanceQualifier InstanceQualifier {
3654                         get {
3655                                 return instance_qualifier;
3656                         }
3657                         set {
3658                                 instance_qualifier = value;
3659                         }
3660                 }
3661
3662                 bool IsProbingOnly {
3663                         get {
3664                                 return (restrictions & Restrictions.ProbingOnly) != 0;
3665                         }
3666                 }
3667
3668                 bool IsDelegateInvoke {
3669                         get {
3670                                 return (restrictions & Restrictions.DelegateInvoke) != 0;
3671                         }
3672                 }
3673
3674                 #endregion
3675
3676                 //
3677                 //  7.4.3.3  Better conversion from expression
3678                 //  Returns :   1    if a->p is better,
3679                 //              2    if a->q is better,
3680                 //              0 if neither is better
3681                 //
3682                 static int BetterExpressionConversion (ResolveContext ec, Argument a, TypeSpec p, TypeSpec q)
3683                 {
3684                         TypeSpec argument_type = a.Type;
3685
3686                         //
3687                         // If argument is an anonymous function
3688                         //
3689                         if (argument_type == InternalType.AnonymousMethod && ec.Module.Compiler.Settings.Version > LanguageVersion.ISO_2) {
3690                                 //
3691                                 // p and q are delegate types or expression tree types
3692                                 //
3693                                 if (p.IsExpressionTreeType || q.IsExpressionTreeType) {
3694                                         if (q.MemberDefinition != p.MemberDefinition) {
3695                                                 return 0;
3696                                         }
3697
3698                                         //
3699                                         // Uwrap delegate from Expression<T>
3700                                         //
3701                                         q = TypeManager.GetTypeArguments (q)[0];
3702                                         p = TypeManager.GetTypeArguments (p)[0];
3703                                 }
3704
3705                                 var p_m = Delegate.GetInvokeMethod (p);
3706                                 var q_m = Delegate.GetInvokeMethod (q);
3707
3708                                 //
3709                                 // With identical parameter lists
3710                                 //
3711                                 if (!TypeSpecComparer.Equals (p_m.Parameters.Types, q_m.Parameters.Types))
3712                                         return 0;
3713
3714                                 p = p_m.ReturnType;
3715                                 q = q_m.ReturnType;
3716
3717                                 //
3718                                 // if p is void returning, and q has a return type Y, then C2 is the better conversion.
3719                                 //
3720                                 if (p.Kind == MemberKind.Void) {
3721                                         return q.Kind != MemberKind.Void ? 2 : 0;
3722                                 }
3723
3724                                 //
3725                                 // if p has a return type Y, and q is void returning, then C1 is the better conversion.
3726                                 //
3727                                 if (q.Kind == MemberKind.Void) {
3728                                         return p.Kind != MemberKind.Void ? 1: 0;
3729                                 }
3730
3731                                 //
3732                                 // When anonymous method is an asynchronous, and P has a return type Task<Y1>, and Q has a return type Task<Y2>
3733                                 // better conversion is performed between underlying types Y1 and Y2
3734                                 //
3735                                 if (p.IsGenericTask || q.IsGenericTask) {
3736                                         var async_am = a.Expr as AnonymousMethodExpression;
3737                                         if (async_am != null && async_am.Block.IsAsync) {
3738
3739                                                 if (p.IsGenericTask != q.IsGenericTask) {
3740                                                         return 0;
3741                                                 }
3742
3743                                                 q = q.TypeArguments[0];
3744                                                 p = p.TypeArguments[0];
3745                                         }
3746                                 }
3747
3748                                 //
3749                                 // The parameters are identicial and return type is not void, use better type conversion
3750                                 // on return type to determine better one
3751                                 //
3752                         } else {
3753                                 if (argument_type == p)
3754                                         return 1;
3755
3756                                 if (argument_type == q)
3757                                         return 2;
3758                         }
3759
3760                         return BetterTypeConversion (ec, p, q);
3761                 }
3762
3763                 //
3764                 // 7.4.3.4  Better conversion from type
3765                 //
3766                 public static int BetterTypeConversion (ResolveContext ec, TypeSpec p, TypeSpec q)
3767                 {
3768                         if (p == null || q == null)
3769                                 throw new InternalErrorException ("BetterTypeConversion got a null conversion");
3770
3771                         switch (p.BuiltinType) {
3772                         case BuiltinTypeSpec.Type.Int:
3773                                 if (q.BuiltinType == BuiltinTypeSpec.Type.UInt || q.BuiltinType == BuiltinTypeSpec.Type.ULong)
3774                                         return 1;
3775                                 break;
3776                         case BuiltinTypeSpec.Type.Long:
3777                                 if (q.BuiltinType == BuiltinTypeSpec.Type.ULong)
3778                                         return 1;
3779                                 break;
3780                         case BuiltinTypeSpec.Type.SByte:
3781                                 switch (q.BuiltinType) {
3782                                 case BuiltinTypeSpec.Type.Byte:
3783                                 case BuiltinTypeSpec.Type.UShort:
3784                                 case BuiltinTypeSpec.Type.UInt:
3785                                 case BuiltinTypeSpec.Type.ULong:
3786                                         return 1;
3787                                 }
3788                                 break;
3789                         case BuiltinTypeSpec.Type.Short:
3790                                 switch (q.BuiltinType) {
3791                                 case BuiltinTypeSpec.Type.UShort:
3792                                 case BuiltinTypeSpec.Type.UInt:
3793                                 case BuiltinTypeSpec.Type.ULong:
3794                                         return 1;
3795                                 }
3796                                 break;
3797                         case BuiltinTypeSpec.Type.Dynamic:
3798                                 // Dynamic is never better
3799                                 return 2;
3800                         }
3801
3802                         switch (q.BuiltinType) {
3803                         case BuiltinTypeSpec.Type.Int:
3804                                 if (p.BuiltinType == BuiltinTypeSpec.Type.UInt || p.BuiltinType == BuiltinTypeSpec.Type.ULong)
3805                                         return 2;
3806                                 break;
3807                         case BuiltinTypeSpec.Type.Long:
3808                                 if (p.BuiltinType == BuiltinTypeSpec.Type.ULong)
3809                                         return 2;
3810                                 break;
3811                         case BuiltinTypeSpec.Type.SByte:
3812                                 switch (p.BuiltinType) {
3813                                 case BuiltinTypeSpec.Type.Byte:
3814                                 case BuiltinTypeSpec.Type.UShort:
3815                                 case BuiltinTypeSpec.Type.UInt:
3816                                 case BuiltinTypeSpec.Type.ULong:
3817                                         return 2;
3818                                 }
3819                                 break;
3820                         case BuiltinTypeSpec.Type.Short:
3821                                 switch (p.BuiltinType) {
3822                                 case BuiltinTypeSpec.Type.UShort:
3823                                 case BuiltinTypeSpec.Type.UInt:
3824                                 case BuiltinTypeSpec.Type.ULong:
3825                                         return 2;
3826                                 }
3827                                 break;
3828                         case BuiltinTypeSpec.Type.Dynamic:
3829                                 // Dynamic is never better
3830                                 return 1;
3831                         }
3832
3833                         // FIXME: handle lifted operators
3834
3835                         // TODO: this is expensive
3836                         Expression p_tmp = new EmptyExpression (p);
3837                         Expression q_tmp = new EmptyExpression (q);
3838
3839                         bool p_to_q = Convert.ImplicitConversionExists (ec, p_tmp, q);
3840                         bool q_to_p = Convert.ImplicitConversionExists (ec, q_tmp, p);
3841
3842                         if (p_to_q && !q_to_p)
3843                                 return 1;
3844
3845                         if (q_to_p && !p_to_q)
3846                                 return 2;
3847
3848                         return 0;
3849                 }
3850
3851                 /// <summary>
3852                 ///   Determines "Better function" between candidate
3853                 ///   and the current best match
3854                 /// </summary>
3855                 /// <remarks>
3856                 ///    Returns a boolean indicating :
3857                 ///     false if candidate ain't better
3858                 ///     true  if candidate is better than the current best match
3859                 /// </remarks>
3860                 static bool BetterFunction (ResolveContext ec, Arguments args, MemberSpec candidate, AParametersCollection cparam, bool candidate_params,
3861                         MemberSpec best, AParametersCollection bparam, bool best_params)
3862                 {
3863                         AParametersCollection candidate_pd = ((IParametersMember) candidate).Parameters;
3864                         AParametersCollection best_pd = ((IParametersMember) best).Parameters;
3865
3866                         bool better_at_least_one = false;
3867                         bool same = true;
3868                         int args_count = args == null ? 0 : args.Count;
3869                         int j = 0;
3870                         Argument a = null;
3871                         TypeSpec ct, bt;
3872                         for (int c_idx = 0, b_idx = 0; j < args_count; ++j, ++c_idx, ++b_idx) {
3873                                 a = args[j];
3874
3875                                 // Default arguments are ignored for better decision
3876                                 if (a.IsDefaultArgument)
3877                                         break;
3878
3879                                 //
3880                                 // When comparing named argument the parameter type index has to be looked up
3881                                 // in original parameter set (override version for virtual members)
3882                                 //
3883                                 NamedArgument na = a as NamedArgument;
3884                                 if (na != null) {
3885                                         int idx = cparam.GetParameterIndexByName (na.Name);
3886                                         ct = candidate_pd.Types[idx];
3887                                         if (candidate_params && candidate_pd.FixedParameters[idx].ModFlags == Parameter.Modifier.PARAMS)
3888                                                 ct = TypeManager.GetElementType (ct);
3889
3890                                         idx = bparam.GetParameterIndexByName (na.Name);
3891                                         bt = best_pd.Types[idx];
3892                                         if (best_params && best_pd.FixedParameters[idx].ModFlags == Parameter.Modifier.PARAMS)
3893                                                 bt = TypeManager.GetElementType (bt);
3894                                 } else {
3895                                         ct = candidate_pd.Types[c_idx];
3896                                         bt = best_pd.Types[b_idx];
3897
3898                                         if (candidate_params && candidate_pd.FixedParameters[c_idx].ModFlags == Parameter.Modifier.PARAMS) {
3899                                                 ct = TypeManager.GetElementType (ct);
3900                                                 --c_idx;
3901                                         }
3902
3903                                         if (best_params && best_pd.FixedParameters[b_idx].ModFlags == Parameter.Modifier.PARAMS) {
3904                                                 bt = TypeManager.GetElementType (bt);
3905                                                 --b_idx;
3906                                         }
3907                                 }
3908
3909                                 if (TypeSpecComparer.IsEqual (ct, bt))
3910                                         continue;
3911
3912                                 same = false;
3913                                 int result = BetterExpressionConversion (ec, a, ct, bt);
3914
3915                                 // for each argument, the conversion to 'ct' should be no worse than
3916                                 // the conversion to 'bt'.
3917                                 if (result == 2)
3918                                         return false;
3919
3920                                 // for at least one argument, the conversion to 'ct' should be better than
3921                                 // the conversion to 'bt'.
3922                                 if (result != 0)
3923                                         better_at_least_one = true;
3924                         }
3925
3926                         if (better_at_least_one)
3927                                 return true;
3928
3929                         //
3930                         // This handles the case
3931                         //
3932                         //   Add (float f1, float f2, float f3);
3933                         //   Add (params decimal [] foo);
3934                         //
3935                         // The call Add (3, 4, 5) should be ambiguous.  Without this check, the
3936                         // first candidate would've chosen as better.
3937                         //
3938                         if (!same && !a.IsDefaultArgument)
3939                                 return false;
3940
3941                         //
3942                         // The two methods have equal non-optional parameter types, apply tie-breaking rules
3943                         //
3944
3945                         //
3946                         // This handles the following cases:
3947                         //
3948                         //  Foo (int i) is better than Foo (int i, long l = 0)
3949                         //  Foo (params int[] args) is better than Foo (int i = 0, params int[] args)
3950                         //
3951                         // Prefer non-optional version
3952                         //
3953                         // LAMESPEC: Specification claims this should be done at last but the opposite is true
3954                         //
3955                         if (candidate_params == best_params && candidate_pd.Count != best_pd.Count) {
3956                                 if (candidate_pd.Count >= best_pd.Count)
3957                                         return false;
3958
3959                                 if (j < candidate_pd.Count && candidate_pd.FixedParameters[j].HasDefaultValue)
3960                                         return false;
3961
3962                                 return true;
3963                         }
3964
3965                         //
3966                         // One is a non-generic method and second is a generic method, then non-generic is better
3967                         //
3968                         if (best.IsGeneric != candidate.IsGeneric)
3969                                 return best.IsGeneric;
3970
3971                         //
3972                         // This handles the following cases:
3973                         //
3974                         //   Trim () is better than Trim (params char[] chars)
3975                         //   Concat (string s1, string s2, string s3) is better than
3976                         //     Concat (string s1, params string [] srest)
3977                         //   Foo (int, params int [] rest) is better than Foo (params int [] rest)
3978                         //
3979                         // Prefer non-expanded version
3980                         //
3981                         if (candidate_params != best_params)
3982                                 return best_params;
3983
3984                         int candidate_param_count = candidate_pd.Count;
3985                         int best_param_count = best_pd.Count;
3986
3987                         if (candidate_param_count != best_param_count)
3988                                 // can only happen if (candidate_params && best_params)
3989                                 return candidate_param_count > best_param_count && best_pd.HasParams;
3990
3991                         //
3992                         // Both methods have the same number of parameters, and the parameters have equal types
3993                         // Pick the "more specific" signature using rules over original (non-inflated) types
3994                         //
3995                         var candidate_def_pd = ((IParametersMember) candidate.MemberDefinition).Parameters;
3996                         var best_def_pd = ((IParametersMember) best.MemberDefinition).Parameters;
3997
3998                         bool specific_at_least_once = false;
3999                         for (j = 0; j < args_count; ++j) {
4000                                 NamedArgument na = args_count == 0 ? null : args [j] as NamedArgument;
4001                                 if (na != null) {
4002                                         ct = candidate_def_pd.Types[cparam.GetParameterIndexByName (na.Name)];
4003                                         bt = best_def_pd.Types[bparam.GetParameterIndexByName (na.Name)];
4004                                 } else {
4005                                         ct = candidate_def_pd.Types[j];
4006                                         bt = best_def_pd.Types[j];
4007                                 }
4008
4009                                 if (ct == bt)
4010                                         continue;
4011                                 TypeSpec specific = MoreSpecific (ct, bt);
4012                                 if (specific == bt)
4013                                         return false;
4014                                 if (specific == ct)
4015                                         specific_at_least_once = true;
4016                         }
4017
4018                         if (specific_at_least_once)
4019                                 return true;
4020
4021                         return false;
4022                 }
4023
4024                 public static void Error_ConstructorMismatch (ResolveContext rc, TypeSpec type, int argCount, Location loc)
4025                 {
4026                         rc.Report.Error (1729, loc,
4027                                 "The type `{0}' does not contain a constructor that takes `{1}' arguments",
4028                                 type.GetSignatureForError (), argCount.ToString ());
4029                 }
4030
4031                 //
4032                 // Determines if the candidate method is applicable to the given set of arguments
4033                 // There could be two different set of parameters for same candidate where one
4034                 // is the closest override for default values and named arguments checks and second
4035                 // one being the virtual base for the parameter types and modifiers.
4036                 //
4037                 // A return value rates candidate method compatibility,
4038                 // 0 = the best, int.MaxValue = the worst
4039                 //
4040                 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)
4041                 {
4042                         // Parameters of most-derived type used mainly for named and optional parameters
4043                         var pd = pm.Parameters;
4044
4045                         // Used for params modifier only, that's legacy of C# 1.0 which uses base type for
4046                         // params modifier instead of most-derived type
4047                         var cpd = ((IParametersMember) candidate).Parameters;
4048                         int param_count = pd.Count;
4049                         int optional_count = 0;
4050                         int score;
4051                         Arguments orig_args = arguments;
4052
4053                         if (arg_count != param_count) {
4054                                 for (int i = 0; i < pd.Count; ++i) {
4055                                         if (pd.FixedParameters[i].HasDefaultValue) {
4056                                                 optional_count = pd.Count - i;
4057                                                 break;
4058                                         }
4059                                 }
4060
4061                                 if (optional_count != 0) {
4062                                         // Readjust expected number when params used
4063                                         if (cpd.HasParams) {
4064                                                 optional_count--;
4065                                                 if (arg_count < param_count)
4066                                                         param_count--;
4067                                         } else if (arg_count > param_count) {
4068                                                 int args_gap = System.Math.Abs (arg_count - param_count);
4069                                                 return int.MaxValue - 10000 + args_gap;
4070                                         }
4071                                 } else if (arg_count != param_count) {
4072                                         int args_gap = System.Math.Abs (arg_count - param_count);
4073                                         if (!cpd.HasParams)
4074                                                 return int.MaxValue - 10000 + args_gap;
4075                                         if (arg_count < param_count - 1)
4076                                                 return int.MaxValue - 10000 + args_gap;
4077                                 }
4078
4079                                 // Resize to fit optional arguments
4080                                 if (optional_count != 0) {
4081                                         if (arguments == null) {
4082                                                 arguments = new Arguments (optional_count);
4083                                         } else {
4084                                                 // Have to create a new container, so the next run can do same
4085                                                 var resized = new Arguments (param_count);
4086                                                 resized.AddRange (arguments);
4087                                                 arguments = resized;
4088                                         }
4089
4090                                         for (int i = arg_count; i < param_count; ++i)
4091                                                 arguments.Add (null);
4092                                 }
4093                         }
4094
4095                         if (arg_count > 0) {
4096                                 //
4097                                 // Shuffle named arguments to the right positions if there are any
4098                                 //
4099                                 if (arguments[arg_count - 1] is NamedArgument) {
4100                                         arg_count = arguments.Count;
4101
4102                                         for (int i = 0; i < arg_count; ++i) {
4103                                                 bool arg_moved = false;
4104                                                 while (true) {
4105                                                         NamedArgument na = arguments[i] as NamedArgument;
4106                                                         if (na == null)
4107                                                                 break;
4108
4109                                                         int index = pd.GetParameterIndexByName (na.Name);
4110
4111                                                         // Named parameter not found
4112                                                         if (index < 0)
4113                                                                 return (i + 1) * 3;
4114
4115                                                         // already reordered
4116                                                         if (index == i)
4117                                                                 break;
4118
4119                                                         Argument temp;
4120                                                         if (index >= param_count) {
4121                                                                 // When using parameters which should not be available to the user
4122                                                                 if ((cpd.FixedParameters[index].ModFlags & Parameter.Modifier.PARAMS) == 0)
4123                                                                         break;
4124
4125                                                                 arguments.Add (null);
4126                                                                 ++arg_count;
4127                                                                 temp = null;
4128                                                         } else {
4129                                                                 temp = arguments[index];
4130
4131                                                                 // The slot has been taken by positional argument
4132                                                                 if (temp != null && !(temp is NamedArgument))
4133                                                                         break;
4134                                                         }
4135
4136                                                         if (!arg_moved) {
4137                                                                 arguments = arguments.MarkOrderedArgument (na);
4138                                                                 arg_moved = true;
4139                                                         }
4140
4141                                                         arguments[index] = arguments[i];
4142                                                         arguments[i] = temp;
4143
4144                                                         if (temp == null)
4145                                                                 break;
4146                                                 }
4147                                         }
4148                                 } else {
4149                                         arg_count = arguments.Count;
4150                                 }
4151                         } else if (arguments != null) {
4152                                 arg_count = arguments.Count;
4153                         }
4154
4155                         //
4156                         // 1. Handle generic method using type arguments when specified or type inference
4157                         //
4158                         TypeSpec[] ptypes;
4159                         var ms = candidate as MethodSpec;
4160                         if (ms != null && ms.IsGeneric) {
4161                                 // Setup constraint checker for probing only
4162                                 ConstraintChecker cc = new ConstraintChecker (null);
4163
4164                                 if (type_arguments != null) {
4165                                         var g_args_count = ms.Arity;
4166                                         if (g_args_count != type_arguments.Count)
4167                                                 return int.MaxValue - 20000 + System.Math.Abs (type_arguments.Count - g_args_count);
4168
4169                                         ms = ms.MakeGenericMethod (ec, type_arguments.Arguments);
4170                                 } else {
4171                                         // TODO: It should not be here (we don't know yet whether any argument is lambda) but
4172                                         // for now it simplifies things. I should probably add a callback to ResolveContext
4173                                         if (lambda_conv_msgs == null) {
4174                                                 lambda_conv_msgs = new SessionReportPrinter ();
4175                                                 prev_recorder = ec.Report.SetPrinter (lambda_conv_msgs);
4176                                         }
4177
4178                                         var ti = new TypeInference (arguments);
4179                                         TypeSpec[] i_args = ti.InferMethodArguments (ec, ms);
4180                                         lambda_conv_msgs.EndSession ();
4181
4182                                         if (i_args == null)
4183                                                 return ti.InferenceScore - 20000;
4184
4185                                         if (i_args.Length != 0) {
4186                                                 ms = ms.MakeGenericMethod (ec, i_args);
4187                                         }
4188
4189                                         cc.IgnoreInferredDynamic = true;
4190                                 }
4191
4192                                 //
4193                                 // Type arguments constraints have to match for the method to be applicable
4194                                 //
4195                                 if (!cc.CheckAll (ms.GetGenericMethodDefinition (), ms.TypeArguments, ms.Constraints, loc)) {
4196                                         candidate = ms;
4197                                         return int.MaxValue - 25000;
4198                                 }
4199
4200                                 //
4201                                 // We have a generic return type and at same time the method is override which
4202                                 // means we have to also inflate override return type in case the candidate is
4203                                 // best candidate and override return type is different to base return type.
4204                                 //
4205                                 // virtual Foo<T, object> with override Foo<T, dynamic>
4206                                 //
4207                                 if (candidate != pm) {
4208                                         MethodSpec override_ms = (MethodSpec) pm;
4209                                         var inflator = new TypeParameterInflator (ec, ms.DeclaringType, override_ms.GenericDefinition.TypeParameters, ms.TypeArguments);
4210                                         returnType = inflator.Inflate (returnType);
4211                                 } else {
4212                                         returnType = ms.ReturnType;
4213                                 }
4214
4215                                 candidate = ms;
4216                                 ptypes = ms.Parameters.Types;
4217                         } else {
4218                                 if (type_arguments != null)
4219                                         return int.MaxValue - 15000;
4220
4221                                 ptypes = cpd.Types;
4222                         }
4223
4224                         //
4225                         // 2. Each argument has to be implicitly convertible to method parameter
4226                         //
4227                         Parameter.Modifier p_mod = 0;
4228                         TypeSpec pt = null;
4229
4230                         for (int i = 0; i < arg_count; i++) {
4231                                 Argument a = arguments[i];
4232                                 if (a == null) {
4233                                         if (!pd.FixedParameters[i].HasDefaultValue) {
4234                                                 arguments = orig_args;
4235                                                 return arg_count * 2 + 2;
4236                                         }
4237
4238                                         //
4239                                         // Get the default value expression, we can use the same expression
4240                                         // if the type matches
4241                                         //
4242                                         Expression e = pd.FixedParameters[i].DefaultValue;
4243                                         if (!(e is Constant) || e.Type.IsGenericOrParentIsGeneric || e.Type.IsGenericParameter) {
4244                                                 //
4245                                                 // LAMESPEC: No idea what the exact rules are for System.Reflection.Missing.Value instead of null
4246                                                 //
4247                                                 if (e == EmptyExpression.MissingValue && ptypes[i].BuiltinType == BuiltinTypeSpec.Type.Object || ptypes[i].BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
4248                                                         e = new MemberAccess (new MemberAccess (new MemberAccess (
4249                                                                 new QualifiedAliasMember (QualifiedAliasMember.GlobalAlias, "System", loc), "Reflection", loc), "Missing", loc), "Value", loc);
4250                                                 } else {
4251                                                         e = new DefaultValueExpression (new TypeExpression (ptypes [i], loc), loc);
4252                                                 }
4253
4254                                                 e = e.Resolve (ec);
4255                                         }
4256
4257                                         arguments[i] = new Argument (e, Argument.AType.Default);
4258                                         continue;
4259                                 }
4260
4261                                 if (p_mod != Parameter.Modifier.PARAMS) {
4262                                         p_mod = (pd.FixedParameters[i].ModFlags & ~Parameter.Modifier.PARAMS) | (cpd.FixedParameters[i].ModFlags & Parameter.Modifier.PARAMS);
4263                                         pt = ptypes [i];
4264                                 } else if (!params_expanded_form) {
4265                                         params_expanded_form = true;
4266                                         pt = ((ElementTypeSpec) pt).Element;
4267                                         i -= 2;
4268                                         continue;
4269                                 }
4270
4271                                 score = 1;
4272                                 if (!params_expanded_form) {
4273                                         if (a.ArgType == Argument.AType.ExtensionType) {
4274                                                 //
4275                                                 // Indentity, implicit reference or boxing conversion must exist for the extension parameter
4276                                                 //
4277                                                 // LAMESPEC: or implicit type parameter conversion
4278                                                 //
4279                                                 var at = a.Type;
4280                                                 if (at == pt || TypeSpecComparer.IsEqual (at, pt) ||
4281                                                         Convert.ImplicitReferenceConversionExists (at, pt, false) ||
4282                                                         Convert.ImplicitBoxingConversion (null, at, pt) != null) {
4283                                                         score = 0;
4284                                                         continue;
4285                                                 }
4286                                         } else {
4287                                                 score = IsArgumentCompatible (ec, a, p_mod & ~Parameter.Modifier.PARAMS, pt);
4288
4289                                                 if (score < 0)
4290                                                         dynamicArgument = true;
4291                                         }
4292                                 }
4293
4294                                 //
4295                                 // It can be applicable in expanded form (when not doing exact match like for delegates)
4296                                 //
4297                                 if (score != 0 && (p_mod & Parameter.Modifier.PARAMS) != 0 && (restrictions & Restrictions.CovariantDelegate) == 0) {
4298                                         if (!params_expanded_form)
4299                                                 pt = ((ElementTypeSpec) pt).Element;
4300
4301                                         if (score > 0)
4302                                                 score = IsArgumentCompatible (ec, a, Parameter.Modifier.NONE, pt);
4303
4304                                         if (score == 0) {
4305                                                 params_expanded_form = true;
4306                                         } else if (score < 0) {
4307                                                 params_expanded_form = true;
4308                                                 dynamicArgument = true;
4309                                         }
4310                                 }
4311
4312                                 if (score > 0) {
4313                                         if (params_expanded_form)
4314                                                 ++score;
4315                                         return (arg_count - i) * 2 + score;
4316                                 }
4317                         }
4318
4319                         //
4320                         // When params parameter has no argument it will be provided later if the method is the best candidate
4321                         //
4322                         if (arg_count + 1 == pd.Count && (cpd.FixedParameters [arg_count].ModFlags & Parameter.Modifier.PARAMS) != 0)
4323                                 params_expanded_form = true;
4324
4325                         //
4326                         // Restore original arguments for dynamic binder to keep the intention of original source code
4327                         //
4328                         if (dynamicArgument)
4329                                 arguments = orig_args;
4330
4331                         return 0;
4332                 }
4333
4334                 //
4335                 // Tests argument compatibility with the parameter
4336                 // The possible return values are
4337                 // 0 - success
4338                 // 1 - modifier mismatch
4339                 // 2 - type mismatch
4340                 // -1 - dynamic binding required
4341                 //
4342                 int IsArgumentCompatible (ResolveContext ec, Argument argument, Parameter.Modifier param_mod, TypeSpec parameter)
4343                 {
4344                         //
4345                         // Types have to be identical when ref or out modifer
4346                         // is used and argument is not of dynamic type
4347                         //
4348                         if ((argument.Modifier | param_mod) != 0) {
4349                                 if (argument.Type != parameter) {
4350                                         //
4351                                         // Do full equality check after quick path
4352                                         //
4353                                         if (!TypeSpecComparer.IsEqual (argument.Type, parameter)) {
4354                                                 //
4355                                                 // Using dynamic for ref/out parameter can still succeed at runtime
4356                                                 //
4357                                                 if (argument.Type.BuiltinType == BuiltinTypeSpec.Type.Dynamic && argument.Modifier == 0 && (restrictions & Restrictions.CovariantDelegate) == 0)
4358                                                         return -1;
4359
4360                                                 return 2;
4361                                         }
4362                                 }
4363
4364                                 if (argument.Modifier != param_mod) {
4365                                         //
4366                                         // Using dynamic for ref/out parameter can still succeed at runtime
4367                                         //
4368                                         if (argument.Type.BuiltinType == BuiltinTypeSpec.Type.Dynamic && argument.Modifier == 0 && (restrictions & Restrictions.CovariantDelegate) == 0)
4369                                                 return -1;
4370
4371                                         return 1;
4372                                 }
4373
4374                         } else {
4375                                 if (argument.Type.BuiltinType == BuiltinTypeSpec.Type.Dynamic && (restrictions & Restrictions.CovariantDelegate) == 0)
4376                                         return -1;
4377
4378                                 //
4379                                 // Deploy custom error reporting for lambda methods. When probing lambda methods
4380                                 // keep all errors reported in separate set and once we are done and no best
4381                                 // candidate was found, this set is used to report more details about what was wrong
4382                                 // with lambda body
4383                                 //
4384                                 if (argument.Expr.Type == InternalType.AnonymousMethod) {
4385                                         if (lambda_conv_msgs == null) {
4386                                                 lambda_conv_msgs = new SessionReportPrinter ();
4387                                                 prev_recorder = ec.Report.SetPrinter (lambda_conv_msgs);
4388                                         }
4389                                 }
4390
4391                                 //
4392                                 // Use implicit conversion in all modes to return same candidates when the expression
4393                                 // is used as argument or delegate conversion
4394                                 //
4395                                 if (!Convert.ImplicitConversionExists (ec, argument.Expr, parameter)) {
4396                                         if (lambda_conv_msgs != null) {
4397                                                 lambda_conv_msgs.EndSession ();
4398                                         }
4399
4400                                         return 2;
4401                                 }
4402                         }
4403
4404                         return 0;
4405                 }
4406
4407                 static TypeSpec MoreSpecific (TypeSpec p, TypeSpec q)
4408                 {
4409                         if (TypeManager.IsGenericParameter (p) && !TypeManager.IsGenericParameter (q))
4410                                 return q;
4411                         if (!TypeManager.IsGenericParameter (p) && TypeManager.IsGenericParameter (q))
4412                                 return p;
4413
4414                         var ac_p = p as ArrayContainer;
4415                         if (ac_p != null) {
4416                                 var ac_q = q as ArrayContainer;
4417                                 if (ac_q == null)
4418                                         return null;
4419
4420                                 TypeSpec specific = MoreSpecific (ac_p.Element, ac_q.Element);
4421                                 if (specific == ac_p.Element)
4422                                         return p;
4423                                 if (specific == ac_q.Element)
4424                                         return q;
4425                         } else if (TypeManager.IsGenericType (p)) {
4426                                 var pargs = TypeManager.GetTypeArguments (p);
4427                                 var qargs = TypeManager.GetTypeArguments (q);
4428
4429                                 bool p_specific_at_least_once = false;
4430                                 bool q_specific_at_least_once = false;
4431
4432                                 for (int i = 0; i < pargs.Length; i++) {
4433                                         TypeSpec specific = MoreSpecific (pargs[i], qargs[i]);
4434                                         if (specific == pargs[i])
4435                                                 p_specific_at_least_once = true;
4436                                         if (specific == qargs[i])
4437                                                 q_specific_at_least_once = true;
4438                                 }
4439
4440                                 if (p_specific_at_least_once && !q_specific_at_least_once)
4441                                         return p;
4442                                 if (!p_specific_at_least_once && q_specific_at_least_once)
4443                                         return q;
4444                         }
4445
4446                         return null;
4447                 }
4448
4449                 //
4450                 // Find the best method from candidate list
4451                 //
4452                 public T ResolveMember<T> (ResolveContext rc, ref Arguments args) where T : MemberSpec, IParametersMember
4453                 {
4454                         List<AmbiguousCandidate> ambiguous_candidates = null;
4455
4456                         MemberSpec best_candidate;
4457                         Arguments best_candidate_args = null;
4458                         bool best_candidate_params = false;
4459                         bool best_candidate_dynamic = false;
4460                         int best_candidate_rate;
4461                         IParametersMember best_parameter_member = null;
4462
4463                         int args_count = args != null ? args.Count : 0;
4464
4465                         Arguments candidate_args = args;
4466                         bool error_mode = false;
4467                         MemberSpec invocable_member = null;
4468
4469                         // Be careful, cannot return until error reporter is restored
4470                         while (true) {
4471                                 best_candidate = null;
4472                                 best_candidate_rate = int.MaxValue;
4473
4474                                 var type_members = members;
4475                                 try {
4476
4477                                         do {
4478                                                 for (int i = 0; i < type_members.Count; ++i) {
4479                                                         var member = type_members[i];
4480
4481                                                         //
4482                                                         // Methods in a base class are not candidates if any method in a derived
4483                                                         // class is applicable
4484                                                         //
4485                                                         if ((member.Modifiers & Modifiers.OVERRIDE) != 0)
4486                                                                 continue;
4487
4488                                                         if (!error_mode) {
4489                                                                 if (!member.IsAccessible (rc))
4490                                                                         continue;
4491
4492                                                                 if (rc.IsRuntimeBinder && !member.DeclaringType.IsAccessible (rc))
4493                                                                         continue;
4494
4495                                                                 if ((member.Modifiers & (Modifiers.PROTECTED | Modifiers.STATIC)) == Modifiers.PROTECTED &&
4496                                                                         instance_qualifier != null && !instance_qualifier.CheckProtectedMemberAccess (rc, member)) {
4497                                                                         continue;
4498                                                                 }
4499                                                         }
4500
4501                                                         IParametersMember pm = member as IParametersMember;
4502                                                         if (pm == null) {
4503                                                                 //
4504                                                                 // Will use it later to report ambiguity between best method and invocable member
4505                                                                 //
4506                                                                 if (Invocation.IsMemberInvocable (member))
4507                                                                         invocable_member = member;
4508
4509                                                                 continue;
4510                                                         }
4511
4512                                                         //
4513                                                         // Overload resolution is looking for base member but using parameter names
4514                                                         // and default values from the closest member. That means to do expensive lookup
4515                                                         // for the closest override for virtual or abstract members
4516                                                         //
4517                                                         if ((member.Modifiers & (Modifiers.VIRTUAL | Modifiers.ABSTRACT)) != 0) {
4518                                                                 var override_params = base_provider.GetOverrideMemberParameters (member);
4519                                                                 if (override_params != null)
4520                                                                         pm = override_params;
4521                                                         }
4522
4523                                                         //
4524                                                         // Check if the member candidate is applicable
4525                                                         //
4526                                                         bool params_expanded_form = false;
4527                                                         bool dynamic_argument = false;
4528                                                         TypeSpec rt = pm.MemberType;
4529                                                         int candidate_rate = IsApplicable (rc, ref candidate_args, args_count, ref member, pm, ref params_expanded_form, ref dynamic_argument, ref rt);
4530
4531                                                         //
4532                                                         // How does it score compare to others
4533                                                         //
4534                                                         if (candidate_rate < best_candidate_rate) {
4535                                                                 best_candidate_rate = candidate_rate;
4536                                                                 best_candidate = member;
4537                                                                 best_candidate_args = candidate_args;
4538                                                                 best_candidate_params = params_expanded_form;
4539                                                                 best_candidate_dynamic = dynamic_argument;
4540                                                                 best_parameter_member = pm;
4541                                                                 best_candidate_return_type = rt;
4542                                                         } else if (candidate_rate == 0) {
4543                                                                 //
4544                                                                 // The member look is done per type for most operations but sometimes
4545                                                                 // it's not possible like for binary operators overload because they
4546                                                                 // are unioned between 2 sides
4547                                                                 //
4548                                                                 if ((restrictions & Restrictions.BaseMembersIncluded) != 0) {
4549                                                                         if (TypeSpec.IsBaseClass (best_candidate.DeclaringType, member.DeclaringType, true))
4550                                                                                 continue;
4551                                                                 }
4552
4553                                                                 bool is_better;
4554                                                                 if (best_candidate.DeclaringType.IsInterface && member.DeclaringType.ImplementsInterface (best_candidate.DeclaringType, false)) {
4555                                                                         //
4556                                                                         // We pack all interface members into top level type which makes the overload resolution
4557                                                                         // more complicated for interfaces. We compensate it by removing methods with same
4558                                                                         // signature when building the cache hence this path should not really be hit often
4559                                                                         //
4560                                                                         // Example:
4561                                                                         // interface IA { void Foo (int arg); }
4562                                                                         // interface IB : IA { void Foo (params int[] args); }
4563                                                                         //
4564                                                                         // IB::Foo is the best overload when calling IB.Foo (1)
4565                                                                         //
4566                                                                         is_better = true;
4567                                                                         if (ambiguous_candidates != null) {
4568                                                                                 foreach (var amb_cand in ambiguous_candidates) {
4569                                                                                         if (member.DeclaringType.ImplementsInterface (best_candidate.DeclaringType, false)) {
4570                                                                                                 continue;
4571                                                                                         }
4572
4573                                                                                         is_better = false;
4574                                                                                         break;
4575                                                                                 }
4576
4577                                                                                 if (is_better)
4578                                                                                         ambiguous_candidates = null;
4579                                                                         }
4580                                                                 } else {
4581                                                                         // Is the new candidate better
4582                                                                         is_better = BetterFunction (rc, candidate_args, member, pm.Parameters, params_expanded_form, best_candidate, best_parameter_member.Parameters, best_candidate_params);
4583                                                                 }
4584
4585                                                                 if (is_better) {
4586                                                                         best_candidate = member;
4587                                                                         best_candidate_args = candidate_args;
4588                                                                         best_candidate_params = params_expanded_form;
4589                                                                         best_candidate_dynamic = dynamic_argument;
4590                                                                         best_parameter_member = pm;
4591                                                                         best_candidate_return_type = rt;
4592                                                                 } else {
4593                                                                         // It's not better but any other found later could be but we are not sure yet
4594                                                                         if (ambiguous_candidates == null)
4595                                                                                 ambiguous_candidates = new List<AmbiguousCandidate> ();
4596
4597                                                                         ambiguous_candidates.Add (new AmbiguousCandidate (member, pm.Parameters, params_expanded_form));
4598                                                                 }
4599                                                         }
4600
4601                                                         // Restore expanded arguments
4602                                                         if (candidate_args != args)
4603                                                                 candidate_args = args;
4604                                                 }
4605                                         } while (best_candidate_rate != 0 && (type_members = base_provider.GetBaseMembers (type_members[0].DeclaringType.BaseType)) != null);
4606                                 } finally {
4607                                         if (prev_recorder != null)
4608                                                 rc.Report.SetPrinter (prev_recorder);
4609                                 }
4610
4611                                 //
4612                                 // We've found exact match
4613                                 //
4614                                 if (best_candidate_rate == 0)
4615                                         break;
4616
4617                                 //
4618                                 // Try extension methods lookup when no ordinary method match was found and provider enables it
4619                                 //
4620                                 if (!error_mode) {
4621                                         var emg = base_provider.LookupExtensionMethod (rc);
4622                                         if (emg != null) {
4623                                                 emg = emg.OverloadResolve (rc, ref args, null, restrictions);
4624                                                 if (emg != null) {
4625                                                         best_candidate_extension_group = emg;
4626                                                         return (T) (MemberSpec) emg.BestCandidate;
4627                                                 }
4628                                         }
4629                                 }
4630
4631                                 // Don't run expensive error reporting mode for probing
4632                                 if (IsProbingOnly)
4633                                         return null;
4634
4635                                 if (error_mode)
4636                                         break;
4637
4638                                 if (lambda_conv_msgs != null && !lambda_conv_msgs.IsEmpty)
4639                                         break;
4640
4641                                 lambda_conv_msgs = null;
4642                                 error_mode = true;
4643                         }
4644
4645                         //
4646                         // No best member match found, report an error
4647                         //
4648                         if (best_candidate_rate != 0 || error_mode) {
4649                                 ReportOverloadError (rc, best_candidate, best_parameter_member, best_candidate_args, best_candidate_params);
4650                                 return null;
4651                         }
4652
4653                         if (best_candidate_dynamic) {
4654                                 if (args[0].ArgType == Argument.AType.ExtensionType) {
4655                                         rc.Report.Error (1973, loc,
4656                                                 "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",
4657                                                 args [0].Type.GetSignatureForError (), best_candidate.Name, best_candidate.GetSignatureForError ());
4658                                 }
4659
4660                                 BestCandidateIsDynamic = true;
4661                                 return null;
4662                         }
4663
4664                         //
4665                         // These flags indicates we are running delegate probing conversion. No need to
4666                         // do more expensive checks
4667                         //
4668                         if ((restrictions & (Restrictions.ProbingOnly | Restrictions.CovariantDelegate)) == (Restrictions.CovariantDelegate | Restrictions.ProbingOnly))
4669                                 return (T) best_candidate;
4670
4671                         if (ambiguous_candidates != null) {
4672                                 //
4673                                 // Now check that there are no ambiguities i.e the selected method
4674                                 // should be better than all the others
4675                                 //
4676                                 for (int ix = 0; ix < ambiguous_candidates.Count; ix++) {
4677                                         var candidate = ambiguous_candidates [ix];
4678
4679                                         if (!BetterFunction (rc, best_candidate_args, best_candidate, best_parameter_member.Parameters, best_candidate_params, candidate.Member, candidate.Parameters, candidate.Expanded)) {
4680                                                 var ambiguous = candidate.Member;
4681                                                 if (custom_errors == null || !custom_errors.AmbiguousCandidates (rc, best_candidate, ambiguous)) {
4682                                                         rc.Report.SymbolRelatedToPreviousError (best_candidate);
4683                                                         rc.Report.SymbolRelatedToPreviousError (ambiguous);
4684                                                         rc.Report.Error (121, loc, "The call is ambiguous between the following methods or properties: `{0}' and `{1}'",
4685                                                                 best_candidate.GetSignatureForError (), ambiguous.GetSignatureForError ());
4686                                                 }
4687
4688                                                 return (T) best_candidate;
4689                                         }
4690                                 }
4691                         }
4692
4693                         if (invocable_member != null) {
4694                                 rc.Report.SymbolRelatedToPreviousError (best_candidate);
4695                                 rc.Report.SymbolRelatedToPreviousError (invocable_member);
4696                                 rc.Report.Warning (467, 2, loc, "Ambiguity between method `{0}' and invocable non-method `{1}'. Using method group",
4697                                         best_candidate.GetSignatureForError (), invocable_member.GetSignatureForError ());
4698                         }
4699
4700                         //
4701                         // And now check if the arguments are all
4702                         // compatible, perform conversions if
4703                         // necessary etc. and return if everything is
4704                         // all right
4705                         //
4706                         if (!VerifyArguments (rc, ref best_candidate_args, best_candidate, best_parameter_member, best_candidate_params))
4707                                 return null;
4708
4709                         if (best_candidate == null)
4710                                 return null;
4711
4712                         //
4713                         // Check ObsoleteAttribute on the best method
4714                         //
4715                         ObsoleteAttribute oa = best_candidate.GetAttributeObsolete ();
4716                         if (oa != null && !rc.IsObsolete)
4717                                 AttributeTester.Report_ObsoleteMessage (oa, best_candidate.GetSignatureForError (), loc, rc.Report);
4718
4719                         var dep = best_candidate.GetMissingDependencies ();
4720                         if (dep != null) {
4721                                 ImportedTypeDefinition.Error_MissingDependency (rc, dep, loc);
4722                         }
4723
4724                         best_candidate.MemberDefinition.SetIsUsed ();
4725
4726                         args = best_candidate_args;
4727                         return (T) best_candidate;
4728                 }
4729
4730                 public MethodSpec ResolveOperator (ResolveContext rc, ref Arguments args)
4731                 {
4732                         return ResolveMember<MethodSpec> (rc, ref args);
4733                 }
4734
4735                 void ReportArgumentMismatch (ResolveContext ec, int idx, MemberSpec method,
4736                                                                                                         Argument a, AParametersCollection expected_par, TypeSpec paramType)
4737                 {
4738                         if (custom_errors != null && custom_errors.ArgumentMismatch (ec, method, a, idx))
4739                                 return;
4740
4741                         if (a is CollectionElementInitializer.ElementInitializerArgument) {
4742                                 ec.Report.SymbolRelatedToPreviousError (method);
4743                                 if ((expected_par.FixedParameters[idx].ModFlags & Parameter.Modifier.ISBYREF) != 0) {
4744                                         ec.Report.Error (1954, loc, "The best overloaded collection initalizer method `{0}' cannot have 'ref', or `out' modifier",
4745                                                 TypeManager.CSharpSignature (method));
4746                                         return;
4747                                 }
4748                                 ec.Report.Error (1950, loc, "The best overloaded collection initalizer method `{0}' has some invalid arguments",
4749                                           TypeManager.CSharpSignature (method));
4750                         } else if (IsDelegateInvoke) {
4751                                 ec.Report.Error (1594, loc, "Delegate `{0}' has some invalid arguments",
4752                                         DelegateType.GetSignatureForError ());
4753                         } else {
4754                                 ec.Report.SymbolRelatedToPreviousError (method);
4755                                 ec.Report.Error (1502, loc, "The best overloaded method match for `{0}' has some invalid arguments",
4756                                         method.GetSignatureForError ());
4757                         }
4758
4759                         Parameter.Modifier mod = idx >= expected_par.Count ? 0 : expected_par.FixedParameters[idx].ModFlags;
4760
4761                         string index = (idx + 1).ToString ();
4762                         if (((mod & (Parameter.Modifier.REF | Parameter.Modifier.OUT)) ^
4763                                 (a.Modifier & (Parameter.Modifier.REF | Parameter.Modifier.OUT))) != 0) {
4764                                 if ((mod & Parameter.Modifier.ISBYREF) == 0)
4765                                         ec.Report.Error (1615, loc, "Argument `#{0}' does not require `{1}' modifier. Consider removing `{1}' modifier",
4766                                                 index, Parameter.GetModifierSignature (a.Modifier));
4767                                 else
4768                                         ec.Report.Error (1620, loc, "Argument `#{0}' is missing `{1}' modifier",
4769                                                 index, Parameter.GetModifierSignature (mod));
4770                         } else if (a.Expr != ErrorExpression.Instance) {
4771                                 string p1 = a.GetSignatureForError ();
4772                                 string p2 = TypeManager.CSharpName (paramType);
4773
4774                                 if (p1 == p2) {
4775                                         p1 = a.Type.GetSignatureForErrorIncludingAssemblyName ();
4776                                         p2 = paramType.GetSignatureForErrorIncludingAssemblyName ();
4777                                 }
4778
4779                                 ec.Report.Error (1503, loc,
4780                                         "Argument `#{0}' cannot convert `{1}' expression to type `{2}'", index, p1, p2);
4781                         }
4782                 }
4783
4784                 //
4785                 // We have failed to find exact match so we return error info about the closest match
4786                 //
4787                 void ReportOverloadError (ResolveContext rc, MemberSpec best_candidate, IParametersMember pm, Arguments args, bool params_expanded)
4788                 {
4789                         int ta_count = type_arguments == null ? 0 : type_arguments.Count;
4790                         int arg_count = args == null ? 0 : args.Count;
4791
4792                         if (ta_count != best_candidate.Arity && (ta_count > 0 || ((IParametersMember) best_candidate).Parameters.IsEmpty)) {
4793                                 var mg = new MethodGroupExpr (new [] { best_candidate }, best_candidate.DeclaringType, loc);
4794                                 mg.Error_TypeArgumentsCannotBeUsed (rc, best_candidate, ta_count, loc);
4795                                 return;
4796                         }
4797
4798                         if (lambda_conv_msgs != null) {
4799                                 if (lambda_conv_msgs.Merge (rc.Report.Printer))
4800                                         return;
4801                         }
4802
4803
4804                         if ((best_candidate.Modifiers & (Modifiers.PROTECTED | Modifiers.STATIC)) == Modifiers.PROTECTED &&
4805                                 InstanceQualifier != null && !InstanceQualifier.CheckProtectedMemberAccess (rc, best_candidate)) {
4806                                 MemberExpr.Error_ProtectedMemberAccess (rc, best_candidate, InstanceQualifier.InstanceType, loc);
4807                         }
4808
4809                         //
4810                         // For candidates which match on parameters count report more details about incorrect arguments
4811                         //
4812                         if (pm != null) {
4813                                 int unexpanded_count = ((IParametersMember) best_candidate).Parameters.HasParams ? pm.Parameters.Count - 1 : pm.Parameters.Count;
4814                                 if (pm.Parameters.Count == arg_count || params_expanded || unexpanded_count == arg_count) {
4815                                         // Reject any inaccessible member
4816                                         if (!best_candidate.IsAccessible (rc) || !best_candidate.DeclaringType.IsAccessible (rc)) {
4817                                                 rc.Report.SymbolRelatedToPreviousError (best_candidate);
4818                                                 Expression.ErrorIsInaccesible (rc, best_candidate.GetSignatureForError (), loc);
4819                                                 return;
4820                                         }
4821
4822                                         var ms = best_candidate as MethodSpec;
4823                                         if (ms != null && ms.IsGeneric) {
4824                                                 bool constr_ok = true;
4825                                                 if (ms.TypeArguments != null)
4826                                                         constr_ok = new ConstraintChecker (rc.MemberContext).CheckAll (ms.GetGenericMethodDefinition (), ms.TypeArguments, ms.Constraints, loc);
4827
4828                                                 if (ta_count == 0) {
4829                                                         if (custom_errors != null && custom_errors.TypeInferenceFailed (rc, best_candidate))
4830                                                                 return;
4831
4832                                                         if (constr_ok) {
4833                                                                 rc.Report.Error (411, loc,
4834                                                                         "The type arguments for method `{0}' cannot be inferred from the usage. Try specifying the type arguments explicitly",
4835                                                                         ms.GetGenericMethodDefinition ().GetSignatureForError ());
4836                                                         }
4837
4838                                                         return;
4839                                                 }
4840                                         }
4841
4842                                         VerifyArguments (rc, ref args, best_candidate, pm, params_expanded);
4843                                         return;
4844                                 }
4845                         }
4846
4847                         //
4848                         // We failed to find any method with correct argument count, report best candidate
4849                         //
4850                         if (custom_errors != null && custom_errors.NoArgumentMatch (rc, best_candidate))
4851                                 return;
4852
4853                         if (best_candidate.Kind == MemberKind.Constructor) {
4854                                 rc.Report.SymbolRelatedToPreviousError (best_candidate);
4855                                 Error_ConstructorMismatch (rc, best_candidate.DeclaringType, arg_count, loc);
4856                         } else if (IsDelegateInvoke) {
4857                                 rc.Report.SymbolRelatedToPreviousError (DelegateType);
4858                                 rc.Report.Error (1593, loc, "Delegate `{0}' does not take `{1}' arguments",
4859                                         DelegateType.GetSignatureForError (), arg_count.ToString ());
4860                         } else {
4861                                 string name = best_candidate.Kind == MemberKind.Indexer ? "this" : best_candidate.Name;
4862                                 rc.Report.SymbolRelatedToPreviousError (best_candidate);
4863                                 rc.Report.Error (1501, loc, "No overload for method `{0}' takes `{1}' arguments",
4864                                         name, arg_count.ToString ());
4865                         }
4866                 }
4867
4868                 bool VerifyArguments (ResolveContext ec, ref Arguments args, MemberSpec member, IParametersMember pm, bool chose_params_expanded)
4869                 {
4870                         var pd = pm.Parameters;
4871                         TypeSpec[] ptypes = ((IParametersMember) member).Parameters.Types;
4872
4873                         Parameter.Modifier p_mod = 0;
4874                         TypeSpec pt = null;
4875                         int a_idx = 0, a_pos = 0;
4876                         Argument a = null;
4877                         ArrayInitializer params_initializers = null;
4878                         bool has_unsafe_arg = pm.MemberType.IsPointer;
4879                         int arg_count = args == null ? 0 : args.Count;
4880
4881                         for (; a_idx < arg_count; a_idx++, ++a_pos) {
4882                                 a = args[a_idx];
4883                                 if (p_mod != Parameter.Modifier.PARAMS) {
4884                                         p_mod = pd.FixedParameters[a_idx].ModFlags;
4885                                         pt = ptypes[a_idx];
4886                                         has_unsafe_arg |= pt.IsPointer;
4887
4888                                         if (p_mod == Parameter.Modifier.PARAMS) {
4889                                                 if (chose_params_expanded) {
4890                                                         params_initializers = new ArrayInitializer (arg_count - a_idx, a.Expr.Location);
4891                                                         pt = TypeManager.GetElementType (pt);
4892                                                 }
4893                                         }
4894                                 }
4895
4896                                 //
4897                                 // Types have to be identical when ref or out modifer is used
4898                                 //
4899                                 if (a.Modifier != 0 || (p_mod & ~Parameter.Modifier.PARAMS) != 0) {
4900                                         if ((p_mod & ~Parameter.Modifier.PARAMS) != a.Modifier)
4901                                                 break;
4902
4903                                         if (a.Expr.Type == pt || TypeSpecComparer.IsEqual (a.Expr.Type, pt))
4904                                                 continue;
4905
4906                                         break;
4907                                 }
4908
4909                                 NamedArgument na = a as NamedArgument;
4910                                 if (na != null) {
4911                                         int name_index = pd.GetParameterIndexByName (na.Name);
4912                                         if (name_index < 0 || name_index >= pd.Count) {
4913                                                 if (IsDelegateInvoke) {
4914                                                         ec.Report.SymbolRelatedToPreviousError (DelegateType);
4915                                                         ec.Report.Error (1746, na.Location,
4916                                                                 "The delegate `{0}' does not contain a parameter named `{1}'",
4917                                                                 DelegateType.GetSignatureForError (), na.Name);
4918                                                 } else {
4919                                                         ec.Report.SymbolRelatedToPreviousError (member);
4920                                                         ec.Report.Error (1739, na.Location,
4921                                                                 "The best overloaded method match for `{0}' does not contain a parameter named `{1}'",
4922                                                                 TypeManager.CSharpSignature (member), na.Name);
4923                                                 }
4924                                         } else if (args[name_index] != a) {
4925                                                 if (IsDelegateInvoke)
4926                                                         ec.Report.SymbolRelatedToPreviousError (DelegateType);
4927                                                 else
4928                                                         ec.Report.SymbolRelatedToPreviousError (member);
4929
4930                                                 ec.Report.Error (1744, na.Location,
4931                                                         "Named argument `{0}' cannot be used for a parameter which has positional argument specified",
4932                                                         na.Name);
4933                                         }
4934                                 }
4935
4936                                 if (a.Expr.Type.BuiltinType == BuiltinTypeSpec.Type.Dynamic)
4937                                         continue;
4938
4939                                 if ((restrictions & Restrictions.CovariantDelegate) != 0 && !Delegate.IsTypeCovariant (ec, a.Expr.Type, pt)) {
4940                                         custom_errors.NoArgumentMatch (ec, member);
4941                                         return false;
4942                                 }
4943
4944                                 Expression conv = null;
4945                                 if (a.ArgType == Argument.AType.ExtensionType) {
4946                                         if (a.Expr.Type == pt || TypeSpecComparer.IsEqual (a.Expr.Type, pt)) {
4947                                                 conv = a.Expr;
4948                                         } else {
4949                                                 conv = Convert.ImplicitReferenceConversion (a.Expr, pt, false);
4950                                                 if (conv == null)
4951                                                         conv = Convert.ImplicitBoxingConversion (a.Expr, a.Expr.Type, pt);
4952                                         }
4953                                 } else {
4954                                         conv = Convert.ImplicitConversion (ec, a.Expr, pt, loc);
4955                                 }
4956
4957                                 if (conv == null)
4958                                         break;
4959
4960                                 //
4961                                 // Convert params arguments to an array initializer
4962                                 //
4963                                 if (params_initializers != null) {
4964                                         // we choose to use 'a.Expr' rather than 'conv' so that
4965                                         // we don't hide the kind of expression we have (esp. CompoundAssign.Helper)
4966                                         params_initializers.Add (a.Expr);
4967                                         args.RemoveAt (a_idx--);
4968                                         --arg_count;
4969                                         continue;
4970                                 }
4971
4972                                 // Update the argument with the implicit conversion
4973                                 a.Expr = conv;
4974                         }
4975
4976                         if (a_idx != arg_count) {
4977                                 ReportArgumentMismatch (ec, a_pos, member, a, pd, pt);
4978                                 return false;
4979                         }
4980
4981                         //
4982                         // Fill not provided arguments required by params modifier
4983                         //
4984                         if (params_initializers == null && pd.HasParams && arg_count + 1 == pd.Count) {
4985                                 if (args == null)
4986                                         args = new Arguments (1);
4987
4988                                 pt = ptypes[pd.Count - 1];
4989                                 pt = TypeManager.GetElementType (pt);
4990                                 has_unsafe_arg |= pt.IsPointer;
4991                                 params_initializers = new ArrayInitializer (0, loc);
4992                         }
4993
4994                         //
4995                         // Append an array argument with all params arguments
4996                         //
4997                         if (params_initializers != null) {
4998                                 args.Add (new Argument (
4999                                         new ArrayCreation (new TypeExpression (pt, loc), params_initializers, loc).Resolve (ec)));
5000                                 arg_count++;
5001                         }
5002
5003                         if (has_unsafe_arg && !ec.IsUnsafe) {
5004                                 Expression.UnsafeError (ec, loc);
5005                         }
5006
5007                         //
5008                         // We could infer inaccesible type arguments
5009                         //
5010                         if (type_arguments == null && member.IsGeneric) {
5011                                 var ms = (MethodSpec) member;
5012                                 foreach (var ta in ms.TypeArguments) {
5013                                         if (!ta.IsAccessible (ec)) {
5014                                                 ec.Report.SymbolRelatedToPreviousError (ta);
5015                                                 Expression.ErrorIsInaccesible (ec, member.GetSignatureForError (), loc);
5016                                                 break;
5017                                         }
5018                                 }
5019                         }
5020
5021                         return true;
5022                 }
5023         }
5024
5025         public class ConstantExpr : MemberExpr
5026         {
5027                 readonly ConstSpec constant;
5028
5029                 public ConstantExpr (ConstSpec constant, Location loc)
5030                 {
5031                         this.constant = constant;
5032                         this.loc = loc;
5033                 }
5034
5035                 public override string Name {
5036                         get { throw new NotImplementedException (); }
5037                 }
5038
5039                 public override bool IsInstance {
5040                         get { return !IsStatic; }
5041                 }
5042
5043                 public override bool IsStatic {
5044                         get { return true; }
5045                 }
5046
5047                 protected override TypeSpec DeclaringType {
5048                         get { return constant.DeclaringType; }
5049                 }
5050
5051                 public override Expression CreateExpressionTree (ResolveContext ec)
5052                 {
5053                         throw new NotSupportedException ("ET");
5054                 }
5055
5056                 protected override Expression DoResolve (ResolveContext rc)
5057                 {
5058                         ResolveInstanceExpression (rc, null);
5059                         DoBestMemberChecks (rc, constant);
5060
5061                         var c = constant.GetConstant (rc);
5062
5063                         // Creates reference expression to the constant value
5064                         return Constant.CreateConstant (constant.MemberType, c.GetValue (), loc);
5065                 }
5066
5067                 public override void Emit (EmitContext ec)
5068                 {
5069                         throw new NotSupportedException ();
5070                 }
5071
5072                 public override string GetSignatureForError ()
5073                 {
5074                         return constant.GetSignatureForError ();
5075                 }
5076
5077                 public override void SetTypeArguments (ResolveContext ec, TypeArguments ta)
5078                 {
5079                         Error_TypeArgumentsCannotBeUsed (ec, "constant", GetSignatureForError (), loc);
5080                 }
5081         }
5082
5083         //
5084         // Fully resolved expression that references a Field
5085         //
5086         public class FieldExpr : MemberExpr, IDynamicAssign, IMemoryLocation, IVariableReference
5087         {
5088                 protected FieldSpec spec;
5089                 VariableInfo variable_info;
5090
5091                 LocalTemporary temp;
5092                 bool prepared;
5093
5094                 protected FieldExpr (Location l)
5095                 {
5096                         loc = l;
5097                 }
5098
5099                 public FieldExpr (FieldSpec spec, Location loc)
5100                 {
5101                         this.spec = spec;
5102                         this.loc = loc;
5103
5104                         type = spec.MemberType;
5105                 }
5106
5107                 public FieldExpr (FieldBase fi, Location l)
5108                         : this (fi.Spec, l)
5109                 {
5110                 }
5111
5112                 #region Properties
5113
5114                 public override string Name {
5115                         get {
5116                                 return spec.Name;
5117                         }
5118                 }
5119
5120                 public bool IsHoisted {
5121                         get {
5122                                 IVariableReference hv = InstanceExpression as IVariableReference;
5123                                 return hv != null && hv.IsHoisted;
5124                         }
5125                 }
5126
5127                 public override bool IsInstance {
5128                         get {
5129                                 return !spec.IsStatic;
5130                         }
5131                 }
5132
5133                 public override bool IsStatic {
5134                         get {
5135                                 return spec.IsStatic;
5136                         }
5137                 }
5138
5139                 public FieldSpec Spec {
5140                         get {
5141                                 return spec;
5142                         }
5143                 }
5144
5145                 protected override TypeSpec DeclaringType {
5146                         get {
5147                                 return spec.DeclaringType;
5148                         }
5149                 }
5150
5151                 public VariableInfo VariableInfo {
5152                         get {
5153                                 return variable_info;
5154                         }
5155                 }
5156
5157 #endregion
5158
5159                 public override string GetSignatureForError ()
5160                 {
5161                         return spec.GetSignatureForError ();
5162                 }
5163
5164                 public bool IsMarshalByRefAccess (ResolveContext rc)
5165                 {
5166                         // Checks possible ldflda of field access expression
5167                         return !spec.IsStatic && TypeSpec.IsValueType (spec.MemberType) && !(InstanceExpression is This) &&
5168                                 rc.Module.PredefinedTypes.MarshalByRefObject.Define () &&
5169                                 TypeSpec.IsBaseClass (spec.DeclaringType, rc.Module.PredefinedTypes.MarshalByRefObject.TypeSpec, false);
5170                 }
5171
5172                 public void SetHasAddressTaken ()
5173                 {
5174                         IVariableReference vr = InstanceExpression as IVariableReference;
5175                         if (vr != null) {
5176                                 vr.SetHasAddressTaken ();
5177                         }
5178                 }
5179
5180                 public override Expression CreateExpressionTree (ResolveContext ec)
5181                 {
5182                         Expression instance;
5183                         if (InstanceExpression == null) {
5184                                 instance = new NullLiteral (loc);
5185                         } else {
5186                                 instance = InstanceExpression.CreateExpressionTree (ec);
5187                         }
5188
5189                         Arguments args = Arguments.CreateForExpressionTree (ec, null,
5190                                 instance,
5191                                 CreateTypeOfExpression ());
5192
5193                         return CreateExpressionFactoryCall (ec, "Field", args);
5194                 }
5195
5196                 public Expression CreateTypeOfExpression ()
5197                 {
5198                         return new TypeOfField (spec, loc);
5199                 }
5200
5201                 protected override Expression DoResolve (ResolveContext ec)
5202                 {
5203                         return DoResolve (ec, null);
5204                 }
5205
5206                 Expression DoResolve (ResolveContext ec, Expression rhs)
5207                 {
5208                         bool lvalue_instance = rhs != null && IsInstance && spec.DeclaringType.IsStruct;
5209
5210                         if (rhs != this) {
5211                                 if (ResolveInstanceExpression (ec, rhs)) {
5212                                         // Resolve the field's instance expression while flow analysis is turned
5213                                         // off: when accessing a field "a.b", we must check whether the field
5214                                         // "a.b" is initialized, not whether the whole struct "a" is initialized.
5215
5216                                         if (lvalue_instance) {
5217                                                 using (ec.With (ResolveContext.Options.DoFlowAnalysis, false)) {
5218                                                         bool out_access = rhs == EmptyExpression.OutAccess || rhs == EmptyExpression.LValueMemberOutAccess;
5219
5220                                                         Expression right_side =
5221                                                                 out_access ? EmptyExpression.LValueMemberOutAccess : EmptyExpression.LValueMemberAccess;
5222
5223                                                         InstanceExpression = InstanceExpression.ResolveLValue (ec, right_side);
5224                                                 }
5225                                         } else {
5226                                                 using (ec.With (ResolveContext.Options.DoFlowAnalysis, false)) {
5227                                                         InstanceExpression = InstanceExpression.Resolve (ec, ResolveFlags.VariableOrValue);
5228                                                 }
5229                                         }
5230
5231                                         if (InstanceExpression == null)
5232                                                 return null;
5233                                 }
5234
5235                                 DoBestMemberChecks (ec, spec);
5236                         }
5237
5238                         var fb = spec as FixedFieldSpec;
5239                         IVariableReference var = InstanceExpression as IVariableReference;
5240
5241                         if (lvalue_instance && var != null && var.VariableInfo != null) {
5242                                 var.VariableInfo.SetStructFieldAssigned (ec, Name);
5243                         }
5244
5245                         if (fb != null) {
5246                                 IFixedExpression fe = InstanceExpression as IFixedExpression;
5247                                 if (!ec.HasSet (ResolveContext.Options.FixedInitializerScope) && (fe == null || !fe.IsFixed)) {
5248                                         ec.Report.Error (1666, loc, "You cannot use fixed size buffers contained in unfixed expressions. Try using the fixed statement");
5249                                 }
5250
5251                                 if (InstanceExpression.eclass != ExprClass.Variable) {
5252                                         ec.Report.SymbolRelatedToPreviousError (spec);
5253                                         ec.Report.Error (1708, loc, "`{0}': Fixed size buffers can only be accessed through locals or fields",
5254                                                 TypeManager.GetFullNameSignature (spec));
5255                                 } else if (var != null && var.IsHoisted) {
5256                                         AnonymousMethodExpression.Error_AddressOfCapturedVar (ec, var, loc);
5257                                 }
5258
5259                                 return new FixedBufferPtr (this, fb.ElementType, loc).Resolve (ec);
5260                         }
5261
5262                         //
5263                         // Set flow-analysis variable info for struct member access. It will be check later
5264                         // for precise error reporting
5265                         //
5266                         if (var != null && var.VariableInfo != null && InstanceExpression.Type.IsStruct) {
5267                                 variable_info = var.VariableInfo.GetStructFieldInfo (Name);
5268                                 if (rhs != null && variable_info != null)
5269                                         variable_info.SetStructFieldAssigned (ec, Name);
5270                         }
5271
5272                         eclass = ExprClass.Variable;
5273                         return this;
5274                 }
5275
5276                 public void VerifyAssignedStructField (ResolveContext rc, Expression rhs)
5277                 {
5278                         var fe = this;
5279
5280                         do {
5281                                 var var = fe.InstanceExpression as IVariableReference;
5282                                 if (var != null) {
5283                                         var vi = var.VariableInfo;
5284
5285                                         if (vi != null && !vi.IsStructFieldAssigned (rc, fe.Name) && (rhs == null || !fe.type.IsStruct)) {
5286                                                 if (rhs != null) {
5287                                                         rc.Report.Warning (1060, 1, fe.loc, "Use of possibly unassigned field `{0}'", fe.Name);
5288                                                 } else {
5289                                                         rc.Report.Error (170, fe.loc, "Use of possibly unassigned field `{0}'", fe.Name);
5290                                                 }
5291
5292                                                 return;
5293                                         }
5294                                 }
5295
5296                                 fe = fe.InstanceExpression as FieldExpr;
5297
5298                         } while (fe != null);
5299                 }
5300
5301                 static readonly int [] codes = {
5302                         191,    // instance, write access
5303                         192,    // instance, out access
5304                         198,    // static, write access
5305                         199,    // static, out access
5306                         1648,   // member of value instance, write access
5307                         1649,   // member of value instance, out access
5308                         1650,   // member of value static, write access
5309                         1651    // member of value static, out access
5310                 };
5311
5312                 static readonly string [] msgs = {
5313                         /*0191*/ "A readonly field `{0}' cannot be assigned to (except in a constructor or a variable initializer)",
5314                         /*0192*/ "A readonly field `{0}' cannot be passed ref or out (except in a constructor)",
5315                         /*0198*/ "A static readonly field `{0}' cannot be assigned to (except in a static constructor or a variable initializer)",
5316                         /*0199*/ "A static readonly field `{0}' cannot be passed ref or out (except in a static constructor)",
5317                         /*1648*/ "Members of readonly field `{0}' cannot be modified (except in a constructor or a variable initializer)",
5318                         /*1649*/ "Members of readonly field `{0}' cannot be passed ref or out (except in a constructor)",
5319                         /*1650*/ "Fields of static readonly field `{0}' cannot be assigned to (except in a static constructor or a variable initializer)",
5320                         /*1651*/ "Fields of static readonly field `{0}' cannot be passed ref or out (except in a static constructor)"
5321                 };
5322
5323                 // The return value is always null.  Returning a value simplifies calling code.
5324                 Expression Report_AssignToReadonly (ResolveContext ec, Expression right_side)
5325                 {
5326                         int i = 0;
5327                         if (right_side == EmptyExpression.OutAccess || right_side == EmptyExpression.LValueMemberOutAccess)
5328                                 i += 1;
5329                         if (IsStatic)
5330                                 i += 2;
5331                         if (right_side == EmptyExpression.LValueMemberAccess || right_side == EmptyExpression.LValueMemberOutAccess)
5332                                 i += 4;
5333                         ec.Report.Error (codes [i], loc, msgs [i], GetSignatureForError ());
5334
5335                         return null;
5336                 }
5337
5338                 override public Expression DoResolveLValue (ResolveContext ec, Expression right_side)
5339                 {
5340                         Expression e = DoResolve (ec, right_side);
5341
5342                         if (e == null)
5343                                 return null;
5344
5345                         spec.MemberDefinition.SetIsAssigned ();
5346
5347                         if ((right_side == EmptyExpression.UnaryAddress || right_side == EmptyExpression.OutAccess) &&
5348                                         (spec.Modifiers & Modifiers.VOLATILE) != 0) {
5349                                 ec.Report.Warning (420, 1, loc,
5350                                         "`{0}': A volatile field references will not be treated as volatile",
5351                                         spec.GetSignatureForError ());
5352                         }
5353
5354                         if (spec.IsReadOnly) {
5355                                 // InitOnly fields can only be assigned in constructors or initializers
5356                                 if (!ec.HasAny (ResolveContext.Options.FieldInitializerScope | ResolveContext.Options.ConstructorScope))
5357                                         return Report_AssignToReadonly (ec, right_side);
5358
5359                                 if (ec.HasSet (ResolveContext.Options.ConstructorScope)) {
5360
5361                                         // InitOnly fields cannot be assigned-to in a different constructor from their declaring type
5362                                         if (ec.CurrentMemberDefinition.Parent.Definition != spec.DeclaringType.GetDefinition ())
5363                                                 return Report_AssignToReadonly (ec, right_side);
5364                                         // static InitOnly fields cannot be assigned-to in an instance constructor
5365                                         if (IsStatic && !ec.IsStatic)
5366                                                 return Report_AssignToReadonly (ec, right_side);
5367                                         // instance constructors can't modify InitOnly fields of other instances of the same type
5368                                         if (!IsStatic && !(InstanceExpression is This))
5369                                                 return Report_AssignToReadonly (ec, right_side);
5370                                 }
5371                         }
5372
5373                         if (right_side == EmptyExpression.OutAccess && IsMarshalByRefAccess (ec)) {
5374                                 ec.Report.SymbolRelatedToPreviousError (spec.DeclaringType);
5375                                 ec.Report.Warning (197, 1, loc,
5376                                                 "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",
5377                                                 GetSignatureForError ());
5378                         }
5379
5380                         eclass = ExprClass.Variable;
5381                         return this;
5382                 }
5383
5384                 public override int GetHashCode ()
5385                 {
5386                         return spec.GetHashCode ();
5387                 }
5388
5389                 public bool IsFixed {
5390                         get {
5391                                 //
5392                                 // A variable of the form V.I is fixed when V is a fixed variable of a struct type
5393                                 //
5394                                 IVariableReference variable = InstanceExpression as IVariableReference;
5395                                 if (variable != null)
5396                                         return InstanceExpression.Type.IsStruct && variable.IsFixed;
5397
5398                                 IFixedExpression fe = InstanceExpression as IFixedExpression;
5399                                 return fe != null && fe.IsFixed;
5400                         }
5401                 }
5402
5403                 public override bool Equals (object obj)
5404                 {
5405                         FieldExpr fe = obj as FieldExpr;
5406                         if (fe == null)
5407                                 return false;
5408
5409                         if (spec != fe.spec)
5410                                 return false;
5411
5412                         if (InstanceExpression == null || fe.InstanceExpression == null)
5413                                 return true;
5414
5415                         return InstanceExpression.Equals (fe.InstanceExpression);
5416                 }
5417
5418                 public void Emit (EmitContext ec, bool leave_copy)
5419                 {
5420                         bool is_volatile = (spec.Modifiers & Modifiers.VOLATILE) != 0;
5421
5422                         spec.MemberDefinition.SetIsUsed ();
5423
5424                         if (IsStatic){
5425                                 if (is_volatile)
5426                                         ec.Emit (OpCodes.Volatile);
5427
5428                                 ec.Emit (OpCodes.Ldsfld, spec);
5429                         } else {
5430                                 if (!prepared)
5431                                         EmitInstance (ec, false);
5432
5433                                 // Optimization for build-in types
5434                                 if (type.IsStruct && type == ec.CurrentType && InstanceExpression.Type == type) {
5435                                         ec.EmitLoadFromPtr (type);
5436                                 } else {
5437                                         var ff = spec as FixedFieldSpec;
5438                                         if (ff != null) {
5439                                                 ec.Emit (OpCodes.Ldflda, spec);
5440                                                 ec.Emit (OpCodes.Ldflda, ff.Element);
5441                                         } else {
5442                                                 if (is_volatile)
5443                                                         ec.Emit (OpCodes.Volatile);
5444
5445                                                 ec.Emit (OpCodes.Ldfld, spec);
5446                                         }
5447                                 }
5448                         }
5449
5450                         if (leave_copy) {
5451                                 ec.Emit (OpCodes.Dup);
5452                                 if (!IsStatic) {
5453                                         temp = new LocalTemporary (this.Type);
5454                                         temp.Store (ec);
5455                                 }
5456                         }
5457                 }
5458
5459                 public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool isCompound)
5460                 {
5461                         bool has_await_source = ec.HasSet (BuilderContext.Options.AsyncBody) && source.ContainsEmitWithAwait ();
5462                         if (isCompound && !(source is DynamicExpressionStatement)) {
5463                                 if (has_await_source) {
5464                                         if (IsInstance)
5465                                                 InstanceExpression = InstanceExpression.EmitToField (ec);
5466                                 } else {
5467                                         prepared = true;
5468                                 }
5469                         }
5470
5471                         if (IsInstance) {
5472                                 if (has_await_source)
5473                                         source = source.EmitToField (ec);
5474
5475                                 EmitInstance (ec, prepared);
5476                         }
5477
5478                         source.Emit (ec);
5479
5480                         if (leave_copy) {
5481                                 ec.Emit (OpCodes.Dup);
5482                                 if (!IsStatic) {
5483                                         temp = new LocalTemporary (this.Type);
5484                                         temp.Store (ec);
5485                                 }
5486                         }
5487
5488                         if ((spec.Modifiers & Modifiers.VOLATILE) != 0)
5489                                 ec.Emit (OpCodes.Volatile);
5490
5491                         spec.MemberDefinition.SetIsAssigned ();
5492
5493                         if (IsStatic)
5494                                 ec.Emit (OpCodes.Stsfld, spec);
5495                         else
5496                                 ec.Emit (OpCodes.Stfld, spec);
5497
5498                         if (temp != null) {
5499                                 temp.Emit (ec);
5500                                 temp.Release (ec);
5501                                 temp = null;
5502                         }
5503                 }
5504
5505                 //
5506                 // Emits store to field with prepared values on stack
5507                 //
5508                 public void EmitAssignFromStack (EmitContext ec)
5509                 {
5510                         if (IsStatic) {
5511                                 ec.Emit (OpCodes.Stsfld, spec);
5512                         } else {
5513                                 ec.Emit (OpCodes.Stfld, spec);
5514                         }
5515                 }
5516
5517                 public override void Emit (EmitContext ec)
5518                 {
5519                         Emit (ec, false);
5520                 }
5521
5522                 public override void EmitSideEffect (EmitContext ec)
5523                 {
5524                         bool is_volatile = (spec.Modifiers & Modifiers.VOLATILE) != 0;
5525
5526                         if (is_volatile) // || is_marshal_by_ref ())
5527                                 base.EmitSideEffect (ec);
5528                 }
5529
5530                 public void AddressOf (EmitContext ec, AddressOp mode)
5531                 {
5532                         if ((mode & AddressOp.Store) != 0)
5533                                 spec.MemberDefinition.SetIsAssigned ();
5534                         if ((mode & AddressOp.Load) != 0)
5535                                 spec.MemberDefinition.SetIsUsed ();
5536
5537                         //
5538                         // Handle initonly fields specially: make a copy and then
5539                         // get the address of the copy.
5540                         //
5541                         bool need_copy;
5542                         if (spec.IsReadOnly){
5543                                 need_copy = true;
5544                                 if (ec.HasSet (EmitContext.Options.ConstructorScope) && spec.DeclaringType == ec.CurrentType) {
5545                                         if (IsStatic){
5546                                                 if (ec.IsStatic)
5547                                                         need_copy = false;
5548                                         } else
5549                                                 need_copy = false;
5550                                 }
5551                         } else
5552                                 need_copy = false;
5553
5554                         if (need_copy) {
5555                                 Emit (ec);
5556                                 var temp = ec.GetTemporaryLocal (type);
5557                                 ec.Emit (OpCodes.Stloc, temp);
5558                                 ec.Emit (OpCodes.Ldloca, temp);
5559                                 ec.FreeTemporaryLocal (temp, type);
5560                                 return;
5561                         }
5562
5563
5564                         if (IsStatic){
5565                                 ec.Emit (OpCodes.Ldsflda, spec);
5566                         } else {
5567                                 if (!prepared)
5568                                         EmitInstance (ec, false);
5569                                 ec.Emit (OpCodes.Ldflda, spec);
5570                         }
5571                 }
5572
5573                 public SLE.Expression MakeAssignExpression (BuilderContext ctx, Expression source)
5574                 {
5575                         return MakeExpression (ctx);
5576                 }
5577
5578                 public override SLE.Expression MakeExpression (BuilderContext ctx)
5579                 {
5580 #if STATIC
5581                         return base.MakeExpression (ctx);
5582 #else
5583                         return SLE.Expression.Field (
5584                                 IsStatic ? null : InstanceExpression.MakeExpression (ctx),
5585                                 spec.GetMetaInfo ());
5586 #endif
5587                 }
5588
5589                 public override void SetTypeArguments (ResolveContext ec, TypeArguments ta)
5590                 {
5591                         Error_TypeArgumentsCannotBeUsed (ec, "field", GetSignatureForError (), loc);
5592                 }
5593         }
5594
5595
5596         //
5597         // Expression that evaluates to a Property.
5598         //
5599         // This is not an LValue because we need to re-write the expression. We
5600         // can not take data from the stack and store it.
5601         //
5602         sealed class PropertyExpr : PropertyOrIndexerExpr<PropertySpec>
5603         {
5604                 public PropertyExpr (PropertySpec spec, Location l)
5605                         : base (l)
5606                 {
5607                         best_candidate = spec;
5608                         type = spec.MemberType;
5609                 }
5610
5611                 #region Properties
5612
5613                 protected override Arguments Arguments {
5614                         get {
5615                                 return null;
5616                         }
5617                         set {
5618                         }
5619                 }
5620
5621                 protected override TypeSpec DeclaringType {
5622                         get {
5623                                 return best_candidate.DeclaringType;
5624                         }
5625                 }
5626
5627                 public override string Name {
5628                         get {
5629                                 return best_candidate.Name;
5630                         }
5631                 }
5632
5633                 public override bool IsInstance {
5634                         get {
5635                                 return !IsStatic;
5636                         }
5637                 }
5638
5639                 public override bool IsStatic {
5640                         get {
5641                                 return best_candidate.IsStatic;
5642                         }
5643                 }
5644
5645                 public PropertySpec PropertyInfo {
5646                         get {
5647                                 return best_candidate;
5648                         }
5649                 }
5650
5651                 #endregion
5652
5653                 public static PropertyExpr CreatePredefined (PropertySpec spec, Location loc)
5654                 {
5655                         return new PropertyExpr (spec, loc) {
5656                                 Getter = spec.Get,
5657                                 Setter = spec.Set
5658                         };
5659                 }
5660
5661                 public override Expression CreateExpressionTree (ResolveContext ec)
5662                 {
5663                         Arguments args;
5664                         if (IsSingleDimensionalArrayLength ()) {
5665                                 args = new Arguments (1);
5666                                 args.Add (new Argument (InstanceExpression.CreateExpressionTree (ec)));
5667                                 return CreateExpressionFactoryCall (ec, "ArrayLength", args);
5668                         }
5669
5670                         args = new Arguments (2);
5671                         if (InstanceExpression == null)
5672                                 args.Add (new Argument (new NullLiteral (loc)));
5673                         else
5674                                 args.Add (new Argument (InstanceExpression.CreateExpressionTree (ec)));
5675                         args.Add (new Argument (new TypeOfMethod (Getter, loc)));
5676                         return CreateExpressionFactoryCall (ec, "Property", args);
5677                 }
5678
5679                 public Expression CreateSetterTypeOfExpression (ResolveContext rc)
5680                 {
5681                         DoResolveLValue (rc, null);
5682                         return new TypeOfMethod (Setter, loc);
5683                 }
5684
5685                 public override string GetSignatureForError ()
5686                 {
5687                         return best_candidate.GetSignatureForError ();
5688                 }
5689
5690                 public override SLE.Expression MakeAssignExpression (BuilderContext ctx, Expression source)
5691                 {
5692 #if STATIC
5693                         return base.MakeExpression (ctx);
5694 #else
5695                         return SLE.Expression.Property (InstanceExpression.MakeExpression (ctx), (MethodInfo) Setter.GetMetaInfo ());
5696 #endif
5697                 }
5698
5699                 public override SLE.Expression MakeExpression (BuilderContext ctx)
5700                 {
5701 #if STATIC
5702                         return base.MakeExpression (ctx);
5703 #else
5704                         return SLE.Expression.Property (InstanceExpression.MakeExpression (ctx), (MethodInfo) Getter.GetMetaInfo ());
5705 #endif
5706                 }
5707
5708                 void Error_PropertyNotValid (ResolveContext ec)
5709                 {
5710                         ec.Report.SymbolRelatedToPreviousError (best_candidate);
5711                         ec.Report.Error (1546, loc, "Property or event `{0}' is not supported by the C# language",
5712                                 GetSignatureForError ());
5713                 }
5714
5715                 bool IsSingleDimensionalArrayLength ()
5716                 {
5717                         if (best_candidate.DeclaringType.BuiltinType != BuiltinTypeSpec.Type.Array || !best_candidate.HasGet || Name != "Length")
5718                                 return false;
5719
5720                         ArrayContainer ac = InstanceExpression.Type as ArrayContainer;
5721                         return ac != null && ac.Rank == 1;
5722                 }
5723
5724                 public override void Emit (EmitContext ec, bool leave_copy)
5725                 {
5726                         //
5727                         // Special case: length of single dimension array property is turned into ldlen
5728                         //
5729                         if (IsSingleDimensionalArrayLength ()) {
5730                                 EmitInstance (ec, false);
5731                                 ec.Emit (OpCodes.Ldlen);
5732                                 ec.Emit (OpCodes.Conv_I4);
5733                                 return;
5734                         }
5735
5736                         base.Emit (ec, leave_copy);
5737                 }
5738
5739                 public override void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool isCompound)
5740                 {
5741                         Arguments args;
5742                         LocalTemporary await_source_arg = null;
5743
5744                         if (isCompound && !(source is DynamicExpressionStatement)) {
5745                                 emitting_compound_assignment = true;
5746                                 source.Emit (ec);
5747
5748                                 if (has_await_arguments) {
5749                                         await_source_arg = new LocalTemporary (Type);
5750                                         await_source_arg.Store (ec);
5751
5752                                         args = new Arguments (1);
5753                                         args.Add (new Argument (await_source_arg));
5754
5755                                         if (leave_copy) {
5756                                                 temp = await_source_arg;
5757                                         }
5758
5759                                         has_await_arguments = false;
5760                                 } else {
5761                                         args = null;
5762
5763                                         if (leave_copy) {
5764                                                 ec.Emit (OpCodes.Dup);
5765                                                 temp = new LocalTemporary (this.Type);
5766                                                 temp.Store (ec);
5767                                         }
5768                                 }
5769                         } else {
5770                                 args = new Arguments (1);
5771
5772                                 if (leave_copy) {
5773                                         source.Emit (ec);
5774                                         temp = new LocalTemporary (this.Type);
5775                                         temp.Store (ec);
5776                                         args.Add (new Argument (temp));
5777                                 } else {
5778                                         args.Add (new Argument (source));
5779                                 }
5780                         }
5781
5782                         emitting_compound_assignment = false;
5783
5784                         var call = new CallEmitter ();
5785                         call.InstanceExpression = InstanceExpression;
5786                         if (args == null)
5787                                 call.InstanceExpressionOnStack = true;
5788
5789                         call.Emit (ec, Setter, args, loc);
5790
5791                         if (temp != null) {
5792                                 temp.Emit (ec);
5793                                 temp.Release (ec);
5794                         }
5795
5796                         if (await_source_arg != null) {
5797                                 await_source_arg.Release (ec);
5798                         }
5799                 }
5800
5801                 protected override Expression OverloadResolve (ResolveContext rc, Expression right_side)
5802                 {
5803                         eclass = ExprClass.PropertyAccess;
5804
5805                         if (best_candidate.IsNotCSharpCompatible) {
5806                                 Error_PropertyNotValid (rc);
5807                         }
5808
5809                         ResolveInstanceExpression (rc, right_side);
5810
5811                         if ((best_candidate.Modifiers & (Modifiers.ABSTRACT | Modifiers.VIRTUAL)) != 0 && best_candidate.DeclaringType != InstanceExpression.Type) {
5812                                 var filter = new MemberFilter (best_candidate.Name, 0, MemberKind.Property, null, null);
5813                                 var p = MemberCache.FindMember (InstanceExpression.Type, filter, BindingRestriction.InstanceOnly | BindingRestriction.OverrideOnly) as PropertySpec;
5814                                 if (p != null) {
5815                                         type = p.MemberType;
5816                                 }
5817                         }
5818
5819                         DoBestMemberChecks (rc, best_candidate);
5820                         return this;
5821                 }
5822
5823                 public override void SetTypeArguments (ResolveContext ec, TypeArguments ta)
5824                 {
5825                         Error_TypeArgumentsCannotBeUsed (ec, "property", GetSignatureForError (), loc);
5826                 }
5827         }
5828
5829         abstract class PropertyOrIndexerExpr<T> : MemberExpr, IDynamicAssign where T : PropertySpec
5830         {
5831                 // getter and setter can be different for base calls
5832                 MethodSpec getter, setter;
5833                 protected T best_candidate;
5834
5835                 protected LocalTemporary temp;
5836                 protected bool emitting_compound_assignment;
5837                 protected bool has_await_arguments;
5838
5839                 protected PropertyOrIndexerExpr (Location l)
5840                 {
5841                         loc = l;
5842                 }
5843
5844                 #region Properties
5845
5846                 protected abstract Arguments Arguments { get; set; }
5847
5848                 public MethodSpec Getter {
5849                         get {
5850                                 return getter;
5851                         }
5852                         set {
5853                                 getter = value;
5854                         }
5855                 }
5856
5857                 public MethodSpec Setter {
5858                         get {
5859                                 return setter;
5860                         }
5861                         set {
5862                                 setter = value;
5863                         }
5864                 }
5865
5866                 #endregion
5867
5868                 protected override Expression DoResolve (ResolveContext ec)
5869                 {
5870                         if (eclass == ExprClass.Unresolved) {
5871                                 var expr = OverloadResolve (ec, null);
5872                                 if (expr == null)
5873                                         return null;
5874
5875                                 if (expr != this)
5876                                         return expr.Resolve (ec);
5877                         }
5878
5879                         if (!ResolveGetter (ec))
5880                                 return null;
5881
5882                         return this;
5883                 }
5884
5885                 public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
5886                 {
5887                         if (right_side == EmptyExpression.OutAccess) {
5888                                 // TODO: best_candidate can be null at this point
5889                                 INamedBlockVariable variable = null;
5890                                 if (best_candidate != null && ec.CurrentBlock.ParametersBlock.TopBlock.GetLocalName (best_candidate.Name, ec.CurrentBlock, ref variable) && variable is Linq.RangeVariable) {
5891                                         ec.Report.Error (1939, loc, "A range variable `{0}' may not be passes as `ref' or `out' parameter",
5892                                                 best_candidate.Name);
5893                                 } else {
5894                                         right_side.DoResolveLValue (ec, this);
5895                                 }
5896                                 return null;
5897                         }
5898
5899                         // if the property/indexer returns a value type, and we try to set a field in it
5900                         if (right_side == EmptyExpression.LValueMemberAccess || right_side == EmptyExpression.LValueMemberOutAccess) {
5901                                 Error_ValueAssignment (ec, right_side);
5902                         }
5903
5904                         if (eclass == ExprClass.Unresolved) {
5905                                 var expr = OverloadResolve (ec, right_side);
5906                                 if (expr == null)
5907                                         return null;
5908
5909                                 if (expr != this)
5910                                         return expr.ResolveLValue (ec, right_side);
5911                         }
5912
5913                         if (!ResolveSetter (ec))
5914                                 return null;
5915
5916                         return this;
5917                 }
5918
5919                 //
5920                 // Implements the IAssignMethod interface for assignments
5921                 //
5922                 public virtual void Emit (EmitContext ec, bool leave_copy)
5923                 {
5924                         var call = new CallEmitter ();
5925                         call.InstanceExpression = InstanceExpression;
5926                         if (has_await_arguments)
5927                                 call.HasAwaitArguments = true;
5928                         else
5929                                 call.DuplicateArguments = emitting_compound_assignment;
5930
5931                         call.Emit (ec, Getter, Arguments, loc);
5932
5933                         if (call.HasAwaitArguments) {
5934                                 InstanceExpression = call.InstanceExpression;
5935                                 Arguments = call.EmittedArguments;
5936                                 has_await_arguments = true;
5937                         }
5938
5939                         if (leave_copy) {
5940                                 ec.Emit (OpCodes.Dup);
5941                                 temp = new LocalTemporary (Type);
5942                                 temp.Store (ec);
5943                         }
5944                 }
5945
5946                 public abstract void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool isCompound);
5947
5948                 public override void Emit (EmitContext ec)
5949                 {
5950                         Emit (ec, false);
5951                 }
5952
5953                 protected override void EmitToFieldSource (EmitContext ec)
5954                 {
5955                         has_await_arguments = true;
5956                         Emit (ec, false);
5957                 }
5958
5959                 public abstract SLE.Expression MakeAssignExpression (BuilderContext ctx, Expression source);
5960
5961                 protected abstract Expression OverloadResolve (ResolveContext rc, Expression right_side);
5962
5963                 bool ResolveGetter (ResolveContext rc)
5964                 {
5965                         if (!best_candidate.HasGet) {
5966                                 if (InstanceExpression != EmptyExpression.Null) {
5967                                         rc.Report.SymbolRelatedToPreviousError (best_candidate);
5968                                         rc.Report.Error (154, loc, "The property or indexer `{0}' cannot be used in this context because it lacks the `get' accessor",
5969                                                 best_candidate.GetSignatureForError ());
5970                                         return false;
5971                                 }
5972                         } else if (!best_candidate.Get.IsAccessible (rc)) {
5973                                 if (best_candidate.HasDifferentAccessibility) {
5974                                         rc.Report.SymbolRelatedToPreviousError (best_candidate.Get);
5975                                         rc.Report.Error (271, loc, "The property or indexer `{0}' cannot be used in this context because the get accessor is inaccessible",
5976                                                 TypeManager.CSharpSignature (best_candidate));
5977                                 } else {
5978                                         rc.Report.SymbolRelatedToPreviousError (best_candidate.Get);
5979                                         ErrorIsInaccesible (rc, best_candidate.Get.GetSignatureForError (), loc);
5980                                 }
5981                         }
5982
5983                         if (best_candidate.HasDifferentAccessibility) {
5984                                 CheckProtectedMemberAccess (rc, best_candidate.Get);
5985                         }
5986
5987                         getter = CandidateToBaseOverride (rc, best_candidate.Get);
5988                         return true;
5989                 }
5990
5991                 bool ResolveSetter (ResolveContext rc)
5992                 {
5993                         if (!best_candidate.HasSet) {
5994                                 rc.Report.Error (200, loc, "Property or indexer `{0}' cannot be assigned to (it is read-only)",
5995                                         GetSignatureForError ());
5996                                 return false;
5997                         }
5998
5999                         if (!best_candidate.Set.IsAccessible (rc)) {
6000                                 if (best_candidate.HasDifferentAccessibility) {
6001                                         rc.Report.SymbolRelatedToPreviousError (best_candidate.Set);
6002                                         rc.Report.Error (272, loc, "The property or indexer `{0}' cannot be used in this context because the set accessor is inaccessible",
6003                                                 GetSignatureForError ());
6004                                 } else {
6005                                         rc.Report.SymbolRelatedToPreviousError (best_candidate.Set);
6006                                         ErrorIsInaccesible (rc, best_candidate.Set.GetSignatureForError (), loc);
6007                                 }
6008                         }
6009
6010                         if (best_candidate.HasDifferentAccessibility)
6011                                 CheckProtectedMemberAccess (rc, best_candidate.Set);
6012
6013                         setter = CandidateToBaseOverride (rc, best_candidate.Set);
6014                         return true;
6015                 }
6016         }
6017
6018         /// <summary>
6019         ///   Fully resolved expression that evaluates to an Event
6020         /// </summary>
6021         public class EventExpr : MemberExpr, IAssignMethod
6022         {
6023                 readonly EventSpec spec;
6024                 MethodSpec op;
6025
6026                 public EventExpr (EventSpec spec, Location loc)
6027                 {
6028                         this.spec = spec;
6029                         this.loc = loc;
6030                 }
6031
6032                 #region Properties
6033
6034                 protected override TypeSpec DeclaringType {
6035                         get {
6036                                 return spec.DeclaringType;
6037                         }
6038                 }
6039
6040                 public override string Name {
6041                         get {
6042                                 return spec.Name;
6043                         }
6044                 }
6045
6046                 public override bool IsInstance {
6047                         get {
6048                                 return !spec.IsStatic;
6049                         }
6050                 }
6051
6052                 public override bool IsStatic {
6053                         get {
6054                                 return spec.IsStatic;
6055                         }
6056                 }
6057
6058                 public MethodSpec Operator {
6059                         get {
6060                                 return op;
6061                         }
6062                 }
6063
6064                 #endregion
6065
6066                 public override MemberExpr ResolveMemberAccess (ResolveContext ec, Expression left, SimpleName original)
6067                 {
6068                         //
6069                         // If the event is local to this class and we are not lhs of +=/-= we transform ourselves into a FieldExpr
6070                         //
6071                         if (!ec.HasSet (ResolveContext.Options.CompoundAssignmentScope)) {
6072                                 if (spec.BackingField != null &&
6073                                         (spec.DeclaringType == ec.CurrentType || TypeManager.IsNestedChildOf (ec.CurrentType, spec.DeclaringType.MemberDefinition))) {
6074
6075                                         spec.MemberDefinition.SetIsUsed ();
6076
6077                                         if (!ec.IsObsolete) {
6078                                                 ObsoleteAttribute oa = spec.GetAttributeObsolete ();
6079                                                 if (oa != null)
6080                                                         AttributeTester.Report_ObsoleteMessage (oa, spec.GetSignatureForError (), loc, ec.Report);
6081                                         }
6082
6083                                         if ((spec.Modifiers & (Modifiers.ABSTRACT | Modifiers.EXTERN)) != 0)
6084                                                 Error_AssignmentEventOnly (ec);
6085
6086                                         FieldExpr ml = new FieldExpr (spec.BackingField, loc);
6087
6088                                         InstanceExpression = null;
6089
6090                                         return ml.ResolveMemberAccess (ec, left, original);
6091                                 }
6092                         }
6093
6094                         return base.ResolveMemberAccess (ec, left, original);
6095                 }
6096
6097                 public override Expression CreateExpressionTree (ResolveContext ec)
6098                 {
6099                         throw new NotSupportedException ("ET");
6100                 }
6101
6102                 public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
6103                 {
6104                         if (right_side == EmptyExpression.EventAddition) {
6105                                 op = spec.AccessorAdd;
6106                         } else if (right_side == EmptyExpression.EventSubtraction) {
6107                                 op = spec.AccessorRemove;
6108                         }
6109
6110                         if (op == null) {
6111                                 Error_AssignmentEventOnly (ec);
6112                                 return null;
6113                         }
6114
6115                         op = CandidateToBaseOverride (ec, op);
6116                         return this;
6117                 }
6118
6119                 protected override Expression DoResolve (ResolveContext ec)
6120                 {
6121                         eclass = ExprClass.EventAccess;
6122                         type = spec.MemberType;
6123
6124                         ResolveInstanceExpression (ec, null);
6125
6126                         if (!ec.HasSet (ResolveContext.Options.CompoundAssignmentScope)) {
6127                                 Error_AssignmentEventOnly (ec);
6128                         }
6129
6130                         DoBestMemberChecks (ec, spec);
6131                         return this;
6132                 }
6133
6134                 public override void Emit (EmitContext ec)
6135                 {
6136                         throw new NotSupportedException ();
6137                         //Error_CannotAssign ();
6138                 }
6139
6140                 #region IAssignMethod Members
6141
6142                 public void Emit (EmitContext ec, bool leave_copy)
6143                 {
6144                         throw new NotImplementedException ();
6145                 }
6146
6147                 public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool isCompound)
6148                 {
6149                         if (leave_copy || !isCompound)
6150                                 throw new NotImplementedException ("EventExpr::EmitAssign");
6151
6152                         Arguments args = new Arguments (1);
6153                         args.Add (new Argument (source));
6154
6155                         var call = new CallEmitter ();
6156                         call.InstanceExpression = InstanceExpression;
6157                         call.Emit (ec, op, args, loc);
6158                 }
6159
6160                 #endregion
6161
6162                 void Error_AssignmentEventOnly (ResolveContext ec)
6163                 {
6164                         if (spec.DeclaringType == ec.CurrentType || TypeManager.IsNestedChildOf (ec.CurrentType, spec.DeclaringType.MemberDefinition)) {
6165                                 ec.Report.Error (79, loc,
6166                                         "The event `{0}' can only appear on the left hand side of `+=' or `-=' operator",
6167                                         GetSignatureForError ());
6168                         } else {
6169                                 ec.Report.Error (70, loc,
6170                                         "The event `{0}' can only appear on the left hand side of += or -= when used outside of the type `{1}'",
6171                                         GetSignatureForError (), spec.DeclaringType.GetSignatureForError ());
6172                         }
6173                 }
6174
6175                 protected override void Error_CannotCallAbstractBase (ResolveContext rc, string name)
6176                 {
6177                         name = name.Substring (0, name.LastIndexOf ('.'));
6178                         base.Error_CannotCallAbstractBase (rc, name);
6179                 }
6180
6181                 public override string GetSignatureForError ()
6182                 {
6183                         return TypeManager.CSharpSignature (spec);
6184                 }
6185
6186                 public override void SetTypeArguments (ResolveContext ec, TypeArguments ta)
6187                 {
6188                         Error_TypeArgumentsCannotBeUsed (ec, "event", GetSignatureForError (), loc);
6189                 }
6190         }
6191
6192         public class TemporaryVariableReference : VariableReference
6193         {
6194                 public class Declarator : Statement
6195                 {
6196                         TemporaryVariableReference variable;
6197
6198                         public Declarator (TemporaryVariableReference variable)
6199                         {
6200                                 this.variable = variable;
6201                                 loc = variable.loc;
6202                         }
6203
6204                         protected override void DoEmit (EmitContext ec)
6205                         {
6206                                 variable.li.CreateBuilder (ec);
6207                         }
6208
6209                         protected override void CloneTo (CloneContext clonectx, Statement target)
6210                         {
6211                                 // Nothing
6212                         }
6213                 }
6214
6215                 LocalVariable li;
6216
6217                 public TemporaryVariableReference (LocalVariable li, Location loc)
6218                 {
6219                         this.li = li;
6220                         this.type = li.Type;
6221                         this.loc = loc;
6222                 }
6223
6224                 public override bool IsLockedByStatement {
6225                         get {
6226                                 return false;
6227                         }
6228                         set {
6229                         }
6230                 }
6231
6232                 public LocalVariable LocalInfo {
6233                     get {
6234                         return li;
6235                     }
6236                 }
6237
6238                 public static TemporaryVariableReference Create (TypeSpec type, Block block, Location loc)
6239                 {
6240                         var li = LocalVariable.CreateCompilerGenerated (type, block, loc);
6241                         return new TemporaryVariableReference (li, loc);
6242                 }
6243
6244                 protected override Expression DoResolve (ResolveContext ec)
6245                 {
6246                         eclass = ExprClass.Variable;
6247
6248                         //
6249                         // Don't capture temporary variables except when using
6250                         // state machine redirection
6251                         //
6252                         if (ec.CurrentAnonymousMethod != null && ec.CurrentAnonymousMethod is StateMachineInitializer && ec.IsVariableCapturingRequired) {
6253                                 AnonymousMethodStorey storey = li.Block.Explicit.CreateAnonymousMethodStorey (ec);
6254                                 storey.CaptureLocalVariable (ec, li);
6255                         }
6256
6257                         return this;
6258                 }
6259
6260                 public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
6261                 {
6262                         return Resolve (ec);
6263                 }
6264
6265                 public override void Emit (EmitContext ec)
6266                 {
6267                         li.CreateBuilder (ec);
6268
6269                         Emit (ec, false);
6270                 }
6271
6272                 public void EmitAssign (EmitContext ec, Expression source)
6273                 {
6274                         li.CreateBuilder (ec);
6275
6276                         EmitAssign (ec, source, false, false);
6277                 }
6278
6279                 public override HoistedVariable GetHoistedVariable (AnonymousExpression ae)
6280                 {
6281                         return li.HoistedVariant;
6282                 }
6283
6284                 public override bool IsFixed {
6285                         get { return true; }
6286                 }
6287
6288                 public override bool IsRef {
6289                         get { return false; }
6290                 }
6291
6292                 public override string Name {
6293                         get { throw new NotImplementedException (); }
6294                 }
6295
6296                 public override void SetHasAddressTaken ()
6297                 {
6298                         throw new NotImplementedException ();
6299                 }
6300
6301                 protected override ILocalVariable Variable {
6302                         get { return li; }
6303                 }
6304
6305                 public override VariableInfo VariableInfo {
6306                         get { return null; }
6307                 }
6308
6309                 public override void VerifyAssigned (ResolveContext rc)
6310                 {
6311                 }
6312         }
6313
6314         ///
6315         /// Handles `var' contextual keyword; var becomes a keyword only
6316         /// if no type called var exists in a variable scope
6317         ///
6318         class VarExpr : SimpleName
6319         {
6320                 public VarExpr (Location loc)
6321                         : base ("var", loc)
6322                 {
6323                 }
6324
6325                 public bool InferType (ResolveContext ec, Expression right_side)
6326                 {
6327                         if (type != null)
6328                                 throw new InternalErrorException ("An implicitly typed local variable could not be redefined");
6329
6330                         type = right_side.Type;
6331                         if (type == InternalType.NullLiteral || type.Kind == MemberKind.Void || type == InternalType.AnonymousMethod || type == InternalType.MethodGroup) {
6332                                 ec.Report.Error (815, loc,
6333                                         "An implicitly typed local variable declaration cannot be initialized with `{0}'",
6334                                         type.GetSignatureForError ());
6335                                 return false;
6336                         }
6337
6338                         eclass = ExprClass.Variable;
6339                         return true;
6340                 }
6341
6342                 protected override void Error_TypeOrNamespaceNotFound (IMemberContext ec)
6343                 {
6344                         if (ec.Module.Compiler.Settings.Version < LanguageVersion.V_3)
6345                                 base.Error_TypeOrNamespaceNotFound (ec);
6346                         else
6347                                 ec.Module.Compiler.Report.Error (825, loc, "The contextual keyword `var' may only appear within a local variable declaration");
6348                 }
6349         }
6350 }