mcs/mcs/ecore.cs

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