mcs/mcs/ecore.cs

   1 //
   2 // ecore.cs: Core of the Expression representation for the intermediate tree.
   3 //
   4 // Author:
   5 //   Miguel de Icaza (miguel@ximian.com)
   6 //   Marek Safar (marek.safar@seznam.cz)
   7 //
   8 // Copyright 2001, 2002, 2003 Ximian, Inc.
   9 // Copyright 2003-2008 Novell, Inc.
  10 //
  11 //
  12
  13 using System;
  14 using System.Collections.Generic;
  15 using System.Diagnostics;
  16 using System.Reflection;
  17 using System.Reflection.Emit;
  18 using System.Text;
  19 using SLE = System.Linq.Expressions;
  20 using System.Linq;
  21
  22 namespace Mono.CSharp {
  23
  24         /// <remarks>
  25         ///   The ExprClass class contains the is used to pass the
  26         ///   classification of an expression (value, variable, namespace,
  27         ///   type, method group, property access, event access, indexer access,
  28         ///   nothing).
  29         /// </remarks>
  30         public enum ExprClass : byte {
  31                 Unresolved      = 0,
  32
  33                 Value,
  34                 Variable,
  35                 Namespace,
  36                 Type,
  37                 TypeParameter,
  38                 MethodGroup,
  39                 PropertyAccess,
  40                 EventAccess,
  41                 IndexerAccess,
  42                 Nothing,
  43         }
  44
  45         /// <remarks>
  46         ///   This is used to tell Resolve in which types of expressions we're
  47         ///   interested.
  48         /// </remarks>
  49         [Flags]
  50         public enum ResolveFlags {
  51                 // Returns Value, Variable, PropertyAccess, EventAccess or IndexerAccess.
  52                 VariableOrValue         = 1,
  53
  54                 // Returns a type expression.
  55                 Type                    = 1 << 1,
  56
  57                 // Returns a method group.
  58                 MethodGroup             = 1 << 2,
  59
  60                 TypeParameter   = 1 << 3,
  61
  62                 // Mask of all the expression class flags.
  63                 MaskExprClass = VariableOrValue | Type | MethodGroup | TypeParameter,
  64         }
  65
  66         //
  67         // This is just as a hint to AddressOf of what will be done with the
  68         // address.
  69         [Flags]
  70         public enum AddressOp {
  71                 Store = 1,
  72                 Load  = 2,
  73                 LoadStore = 3
  74         };
  75
  76         /// <summary>
  77         ///   This interface is implemented by variables
  78         /// </summary>
  79         public interface IMemoryLocation {
  80                 /// <summary>
  81                 ///   The AddressOf method should generate code that loads
  82                 ///   the address of the object and leaves it on the stack.
  83                 ///
  84                 ///   The `mode' argument is used to notify the expression
  85                 ///   of whether this will be used to read from the address or
  86                 ///   write to the address.
  87                 ///
  88                 ///   This is just a hint that can be used to provide good error
  89                 ///   reporting, and should have no other side effects.
  90                 /// </summary>
  91                 void AddressOf (EmitContext ec, AddressOp mode);
  92         }
  93
  94         //
  95         // An expressions resolved as a direct variable reference
  96         //
  97         public interface IVariableReference : IFixedExpression
  98         {
  99                 bool IsHoisted { get; }
 100                 string Name { get; }
 101                 VariableInfo VariableInfo { get; }
 102
 103                 void SetHasAddressTaken ();
 104         }
 105
 106         //
 107         // Implemented by an expression which could be or is always
 108         // fixed
 109         //
 110         public interface IFixedExpression
 111         {
 112                 bool IsFixed { get; }
 113         }
 114
 115         /// <remarks>
 116         ///   Base class for expressions
 117         /// </remarks>
 118         public abstract class Expression {
 119                 public ExprClass eclass;
 120                 protected TypeSpec type;
 121                 protected Location loc;
 122
 123                 public TypeSpec Type {
 124                         get { return type; }
 125                         set { type = value; }
 126                 }
 127
 128                 public Location Location {
 129                         get { return loc; }
 130                 }
 131
 132                 // Not nice but we have broken hierarchy.
 133                 public virtual void CheckMarshalByRefAccess (ResolveContext ec)
 134                 {
 135                 }
 136
 137                 public virtual string GetSignatureForError ()
 138                 {
 139                         return type.GetDefinition ().GetSignatureForError ();
 140                 }
 141
 142                 public virtual bool IsNull {
 143                         get {
 144                                 return false;
 145                         }
 146                 }
 147
 148                 /// <summary>
 149                 ///   Performs semantic analysis on the Expression
 150                 /// </summary>
 151                 ///
 152                 /// <remarks>
 153                 ///   The Resolve method is invoked to perform the semantic analysis
 154                 ///   on the node.
 155                 ///
 156                 ///   The return value is an expression (it can be the
 157                 ///   same expression in some cases) or a new
 158                 ///   expression that better represents this node.
 159                 ///
 160                 ///   For example, optimizations of Unary (LiteralInt)
 161                 ///   would return a new LiteralInt with a negated
 162                 ///   value.
 163                 ///
 164                 ///   If there is an error during semantic analysis,
 165                 ///   then an error should be reported (using Report)
 166                 ///   and a null value should be returned.
 167                 ///
 168                 ///   There are two side effects expected from calling
 169                 ///   Resolve(): the the field variable "eclass" should
 170                 ///   be set to any value of the enumeration
 171                 ///   `ExprClass' and the type variable should be set
 172                 ///   to a valid type (this is the type of the
 173                 ///   expression).
 174                 /// </remarks>
 175                 protected abstract Expression DoResolve (ResolveContext rc);
 176
 177                 public virtual Expression DoResolveLValue (ResolveContext rc, Expression right_side)
 178                 {
 179                         return null;
 180                 }
 181
 182                 //
 183                 // This is used if the expression should be resolved as a type or namespace name.
 184                 // the default implementation fails.
 185                 //
 186                 public virtual FullNamedExpression ResolveAsTypeStep (IMemberContext rc,  bool silent)
 187                 {
 188                         if (!silent) {
 189                                 ResolveContext ec = new ResolveContext (rc);
 190                                 Expression e = Resolve (ec);
 191                                 if (e != null)
 192                                         e.Error_UnexpectedKind (ec, ResolveFlags.Type, loc);
 193                         }
 194
 195                         return null;
 196                 }
 197
 198                 //
 199                 // This is used to resolve the expression as a type, a null
 200                 // value will be returned if the expression is not a type
 201                 // reference
 202                 //
 203                 public virtual TypeExpr ResolveAsTypeTerminal (IMemberContext ec , bool silent)
 204                 {
 205                         int errors = ec.Compiler.Report.Errors;
 206
 207                         FullNamedExpression fne = ResolveAsTypeStep (ec, silent);
 208
 209                         if (fne == null)
 210                                 return null;
 211
 212                         TypeExpr te = fne as TypeExpr;
 213                         if (te == null) {
 214                                 if (!silent && errors == ec.Compiler.Report.Errors)
 215                                         fne.Error_UnexpectedKind (ec.Compiler.Report, null, "type", loc);
 216                                 return null;
 217                         }
 218
 219                         if (!te.CheckAccessLevel (ec)) {
 220                                 ec.Compiler.Report.SymbolRelatedToPreviousError (te.Type);
 221                                 ErrorIsInaccesible (ec, te.Type.GetSignatureForError (), loc);
 222                         }
 223
 224                         te.loc = loc;
 225
 226                         //
 227                         // Obsolete checks cannot be done when resolving base context as they
 228                         // require type dependecies to be set but we are just resolving them
 229                         //
 230                         if (!silent && !(ec is TypeContainer.BaseContext)) {
 231                                 ObsoleteAttribute obsolete_attr = te.Type.GetAttributeObsolete ();
 232                                 if (obsolete_attr != null && !ec.IsObsolete) {
 233                                         AttributeTester.Report_ObsoleteMessage (obsolete_attr, te.GetSignatureForError (), Location, ec.Compiler.Report);
 234                                 }
 235                         }
 236
 237                         return te;
 238                 }
 239
 240                 public static void ErrorIsInaccesible (IMemberContext rc, string member, Location loc)
 241                 {
 242                         rc.Compiler.Report.Error (122, loc, "`{0}' is inaccessible due to its protection level", member);
 243                 }
 244
 245                 public void Error_ExpressionMustBeConstant (ResolveContext rc, Location loc, string e_name)
 246                 {
 247                         rc.Report.Error (133, loc, "The expression being assigned to `{0}' must be constant", e_name);
 248                 }
 249
 250                 public void Error_ConstantCanBeInitializedWithNullOnly (ResolveContext rc, TypeSpec type, Location loc, string name)
 251                 {
 252                         rc.Report.Error (134, loc, "A constant `{0}' of reference type `{1}' can only be initialized with null",
 253                                 name, TypeManager.CSharpName (type));
 254                 }
 255
 256                 public static void Error_InvalidExpressionStatement (Report Report, Location loc)
 257                 {
 258                         Report.Error (201, loc, "Only assignment, call, increment, decrement, and new object " +
 259                                        "expressions can be used as a statement");
 260                 }
 261
 262                 public void Error_InvalidExpressionStatement (BlockContext ec)
 263                 {
 264                         Error_InvalidExpressionStatement (ec.Report, loc);
 265                 }
 266
 267                 public static void Error_VoidInvalidInTheContext (Location loc, Report Report)
 268                 {
 269                         Report.Error (1547, loc, "Keyword `void' cannot be used in this context");
 270                 }
 271
 272                 public virtual void Error_ValueCannotBeConverted (ResolveContext ec, Location loc, TypeSpec target, bool expl)
 273                 {
 274                         Error_ValueCannotBeConvertedCore (ec, loc, target, expl);
 275                 }
 276
 277                 protected void Error_ValueCannotBeConvertedCore (ResolveContext ec, Location loc, TypeSpec target, bool expl)
 278                 {
 279                         // The error was already reported as CS1660
 280                         if (type == InternalType.AnonymousMethod)
 281                                 return;
 282
 283 /*
 284                         if (TypeManager.IsGenericParameter (Type) && TypeManager.IsGenericParameter (target) && type.Name == target.Name) {
 285                                 string sig1 = type.DeclaringMethod == null ?
 286                                         TypeManager.CSharpName (type.DeclaringType) :
 287                                         TypeManager.CSharpSignature (type.DeclaringMethod);
 288                                 string sig2 = target.DeclaringMethod == null ?
 289                                         TypeManager.CSharpName (target.DeclaringType) :
 290                                         TypeManager.CSharpSignature (target.DeclaringMethod);
 291                                 ec.Report.ExtraInformation (loc,
 292                                         String.Format (
 293                                                 "The generic parameter `{0}' of `{1}' cannot be converted to the generic parameter `{0}' of `{2}' (in the previous ",
 294                                                 Type.Name, sig1, sig2));
 295                         } else if (Type.MetaInfo.FullName == target.MetaInfo.FullName) {
 296                                 ec.Report.ExtraInformation (loc,
 297                                         String.Format (
 298                                         "The type `{0}' has two conflicting definitions, one comes from `{1}' and the other from `{2}' (in the previous ",
 299                                         Type.MetaInfo.FullName, Type.Assembly.FullName, target.Assembly.FullName));
 300                         }
 301 */
 302                         if (expl) {
 303                                 ec.Report.Error (30, loc, "Cannot convert type `{0}' to `{1}'",
 304                                         TypeManager.CSharpName (type), TypeManager.CSharpName (target));
 305                                 return;
 306                         }
 307
 308                         ec.Report.DisableReporting ();
 309                         bool expl_exists = Convert.ExplicitConversion (ec, this, target, Location.Null) != null;
 310                         ec.Report.EnableReporting ();
 311
 312                         if (expl_exists) {
 313                                 ec.Report.Error (266, loc, "Cannot implicitly convert type `{0}' to `{1}'. " +
 314                                               "An explicit conversion exists (are you missing a cast?)",
 315                                         TypeManager.CSharpName (Type), TypeManager.CSharpName (target));
 316                                 return;
 317                         }
 318
 319                         ec.Report.Error (29, loc, "Cannot implicitly convert type `{0}' to `{1}'",
 320                                 type.GetSignatureForError (), target.GetSignatureForError ());
 321                 }
 322
 323                 public void Error_TypeArgumentsCannotBeUsed (Report report, Location loc, MemberSpec member, int arity)
 324                 {
 325                         // Better message for possible generic expressions
 326                         if (member != null && (member.Kind & MemberKind.GenericMask) != 0) {
 327                                 report.SymbolRelatedToPreviousError (member);
 328                                 if (member is TypeSpec)
 329                                         member = ((TypeSpec) member).GetDefinition ();
 330                                 else
 331                                         member = ((MethodSpec) member).GetGenericMethodDefinition ();
 332
 333                                 string name = member.Kind == MemberKind.Method ? "method" : "type";
 334                                 if (member.IsGeneric) {
 335                                         report.Error (305, loc, "Using the generic {0} `{1}' requires `{2}' type argument(s)",
 336                                                 name, member.GetSignatureForError (), member.Arity.ToString ());
 337                                 } else {
 338                                         report.Error (308, loc, "The non-generic {0} `{1}' cannot be used with the type arguments",
 339                                                 name, member.GetSignatureForError ());
 340                                 }
 341                         } else {
 342                                 Error_TypeArgumentsCannotBeUsed (report, ExprClassName, GetSignatureForError (), loc);
 343                         }
 344                 }
 345
 346                 public void Error_TypeArgumentsCannotBeUsed (Report report, string exprType, string name, Location loc)
 347                 {
 348                         report.Error (307, loc, "The {0} `{1}' cannot be used with type arguments",
 349                                 exprType, name);
 350                 }
 351
 352                 protected virtual void Error_TypeDoesNotContainDefinition (ResolveContext ec, TypeSpec type, string name)
 353                 {
 354                         Error_TypeDoesNotContainDefinition (ec, loc, type, name);
 355                 }
 356
 357                 public static void Error_TypeDoesNotContainDefinition (ResolveContext ec, Location loc, TypeSpec type, string name)
 358                 {
 359                         ec.Report.SymbolRelatedToPreviousError (type);
 360                         ec.Report.Error (117, loc, "`{0}' does not contain a definition for `{1}'",
 361                                 TypeManager.CSharpName (type), name);
 362                 }
 363
 364                 protected static void Error_ValueAssignment (ResolveContext ec, Location loc)
 365                 {
 366                         ec.Report.Error (131, loc, "The left-hand side of an assignment must be a variable, a property or an indexer");
 367                 }
 368
 369                 protected void Error_VoidPointerOperation (ResolveContext rc)
 370                 {
 371                         rc.Report.Error (242, loc, "The operation in question is undefined on void pointers");
 372                 }
 373
 374                 public ResolveFlags ExprClassToResolveFlags {
 375                         get {
 376                                 switch (eclass) {
 377                                 case ExprClass.Type:
 378                                 case ExprClass.Namespace:
 379                                         return ResolveFlags.Type;
 380
 381                                 case ExprClass.MethodGroup:
 382                                         return ResolveFlags.MethodGroup;
 383
 384                                 case ExprClass.TypeParameter:
 385                                         return ResolveFlags.TypeParameter;
 386
 387                                 case ExprClass.Value:
 388                                 case ExprClass.Variable:
 389                                 case ExprClass.PropertyAccess:
 390                                 case ExprClass.EventAccess:
 391                                 case ExprClass.IndexerAccess:
 392                                         return ResolveFlags.VariableOrValue;
 393
 394                                 default:
 395                                         throw new InternalErrorException (loc.ToString () + " " +  GetType () + " ExprClass is Invalid after resolve");
 396                                 }
 397                         }
 398                 }
 399
 400                 /// <summary>
 401                 ///   Resolves an expression and performs semantic analysis on it.
 402                 /// </summary>
 403                 ///
 404                 /// <remarks>
 405                 ///   Currently Resolve wraps DoResolve to perform sanity
 406                 ///   checking and assertion checking on what we expect from Resolve.
 407                 /// </remarks>
 408                 public Expression Resolve (ResolveContext ec, ResolveFlags flags)
 409                 {
 410                         if (eclass != ExprClass.Unresolved)
 411                                 return this;
 412
 413                         Expression e;
 414                         try {
 415                                 e = DoResolve (ec);
 416
 417                                 if (e == null)
 418                                         return null;
 419
 420                                 if ((flags & e.ExprClassToResolveFlags) == 0) {
 421                                         e.Error_UnexpectedKind (ec, flags, loc);
 422                                         return null;
 423                                 }
 424
 425                                 if (e.type == null)
 426                                         throw new InternalErrorException ("Expression `{0}' didn't set its type in DoResolve", e.GetType ());
 427
 428                                 return e;
 429                         } catch (Exception ex) {
 430                                 if (loc.IsNull || Report.DebugFlags > 0 || ex is CompletionResult || ec.Report.IsDisabled)
 431                                         throw;
 432
 433                                 ec.Report.Error (584, loc, "Internal compiler error: {0}", ex.Message);
 434                                 return EmptyExpression.Null;    // TODO: Add location
 435                         }
 436                 }
 437
 438                 /// <summary>
 439                 ///   Resolves an expression and performs semantic analysis on it.
 440                 /// </summary>
 441                 public Expression Resolve (ResolveContext rc)
 442                 {
 443                         return Resolve (rc, ResolveFlags.VariableOrValue | ResolveFlags.MethodGroup);
 444                 }
 445
 446                 /// <summary>
 447                 ///   Resolves an expression for LValue assignment
 448                 /// </summary>
 449                 ///
 450                 /// <remarks>
 451                 ///   Currently ResolveLValue wraps DoResolveLValue to perform sanity
 452                 ///   checking and assertion checking on what we expect from Resolve
 453                 /// </remarks>
 454                 public Expression ResolveLValue (ResolveContext ec, Expression right_side)
 455                 {
 456                         int errors = ec.Report.Errors;
 457                         bool out_access = right_side == EmptyExpression.OutAccess.Instance;
 458
 459                         Expression e = DoResolveLValue (ec, right_side);
 460
 461                         if (e != null && out_access && !(e is IMemoryLocation)) {
 462                                 // FIXME: There's no problem with correctness, the 'Expr = null' handles that.
 463                                 //        Enabling this 'throw' will "only" result in deleting useless code elsewhere,
 464
 465                                 //throw new InternalErrorException ("ResolveLValue didn't return an IMemoryLocation: " +
 466                                 //                                e.GetType () + " " + e.GetSignatureForError ());
 467                                 e = null;
 468                         }
 469
 470                         if (e == null) {
 471                                 if (errors == ec.Report.Errors) {
 472                                         if (out_access)
 473                                                 ec.Report.Error (1510, loc, "A ref or out argument must be an assignable variable");
 474                                         else
 475                                                 Error_ValueAssignment (ec, loc);
 476                                 }
 477                                 return null;
 478                         }
 479
 480                         if (e.eclass == ExprClass.Unresolved)
 481                                 throw new Exception ("Expression " + e + " ExprClass is Invalid after resolve");
 482
 483                         if ((e.type == null) && !(e is GenericTypeExpr))
 484                                 throw new Exception ("Expression " + e + " did not set its type after Resolve");
 485
 486                         return e;
 487                 }
 488
 489                 public virtual void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
 490                 {
 491                         rc.Compiler.Report.Error (182, loc,
 492                                 "An attribute argument must be a constant expression, typeof expression or array creation expression");
 493                 }
 494
 495                 /// <summary>
 496                 ///   Emits the code for the expression
 497                 /// </summary>
 498                 ///
 499                 /// <remarks>
 500                 ///   The Emit method is invoked to generate the code
 501                 ///   for the expression.
 502                 /// </remarks>
 503                 public abstract void Emit (EmitContext ec);
 504
 505
 506                 // Emit code to branch to @target if this expression is equivalent to @on_true.
 507                 // The default implementation is to emit the value, and then emit a brtrue or brfalse.
 508                 // Subclasses can provide more efficient implementations, but those MUST be equivalent,
 509                 // including the use of conditional branches.  Note also that a branch MUST be emitted
 510                 public virtual void EmitBranchable (EmitContext ec, Label target, bool on_true)
 511                 {
 512                         Emit (ec);
 513                         ec.Emit (on_true ? OpCodes.Brtrue : OpCodes.Brfalse, target);
 514                 }
 515
 516                 // Emit this expression for its side effects, not for its value.
 517                 // The default implementation is to emit the value, and then throw it away.
 518                 // Subclasses can provide more efficient implementations, but those MUST be equivalent
 519                 public virtual void EmitSideEffect (EmitContext ec)
 520                 {
 521                         Emit (ec);
 522                         ec.Emit (OpCodes.Pop);
 523                 }
 524
 525                 /// <summary>
 526                 ///   Protected constructor.  Only derivate types should
 527                 ///   be able to be created
 528                 /// </summary>
 529
 530                 protected Expression ()
 531                 {
 532                 }
 533
 534                 /// <summary>
 535                 ///   Returns a fully formed expression after a MemberLookup
 536                 /// </summary>
 537                 ///
 538                 static Expression ExprClassFromMemberInfo (MemberSpec spec, Location loc)
 539                 {
 540                         if (spec is EventSpec)
 541                                 return new EventExpr ((EventSpec) spec, loc);
 542                         if (spec is ConstSpec)
 543                                 return new ConstantExpr ((ConstSpec) spec, loc);
 544                         if (spec is FieldSpec)
 545                                 return new FieldExpr ((FieldSpec) spec, loc);
 546                         if (spec is PropertySpec)
 547                                 return new PropertyExpr ((PropertySpec) spec, loc);
 548                         if (spec is TypeSpec)
 549                                 return new TypeExpression (((TypeSpec) spec), loc);
 550
 551                         return null;
 552                 }
 553
 554                 protected static MethodSpec ConstructorLookup (ResolveContext rc, TypeSpec type, ref Arguments args, Location loc)
 555                 {
 556                         var ctors = MemberCache.FindMembers (type, ConstructorInfo.ConstructorName, true);
 557                         if (ctors == null) {
 558                                 rc.Report.SymbolRelatedToPreviousError (type);
 559                                 if (type.IsStruct) {
 560                                         // Report meaningful error for struct as they always have default ctor in C# context
 561                                         OverloadResolver.Error_ConstructorMismatch (rc, type, args == null ? 0 : args.Count, loc);
 562                                 } else {
 563                                         rc.Report.Error (143, loc, "The class `{0}' has no constructors defined",
 564                                                 type.GetSignatureForError ());
 565                                 }
 566
 567                                 return null;
 568                         }
 569
 570                         var r = new OverloadResolver (ctors, OverloadResolver.Restrictions.NoBaseMembers, loc);
 571                         return r.ResolveMember<MethodSpec> (rc, ref args);
 572                 }
 573
 574                 [Flags]
 575                 public enum MemberLookupRestrictions
 576                 {
 577                         None = 0,
 578                         InvocableOnly = 1,
 579                         ExactArity = 1 << 2,
 580                         ReadAccess = 1 << 3
 581                 }
 582
 583                 //
 584                 // Lookup type `queried_type' for code in class `container_type' with a qualifier of
 585                 // `qualifier_type' or null to lookup members in the current class.
 586                 //
 587                 public static Expression MemberLookup (ResolveContext rc, TypeSpec currentType, TypeSpec queried_type, string name, int arity, MemberLookupRestrictions restrictions, Location loc)
 588                 {
 589                         var members = MemberCache.FindMembers (queried_type, name, false);
 590                         if (members == null)
 591                                 return null;
 592
 593                         MemberSpec non_method = null;
 594                         MemberSpec ambig_non_method = null;
 595                         currentType = currentType ?? InternalType.FakeInternalType;
 596                         do {
 597                                 for (int i = 0; i < members.Count; ++i) {
 598                                         var member = members[i];
 599
 600                                         // HACK: for events because +=/-= can appear at same class only, should use OverrideToBase there
 601                                         if ((member.Modifiers & Modifiers.OVERRIDE) != 0 && member.Kind != MemberKind.Event)
 602                                                 continue;
 603
 604                                         if ((arity > 0 || (restrictions & MemberLookupRestrictions.ExactArity) != 0) && member.Arity != arity)
 605                                                 continue;
 606
 607                                         if (rc != null && !member.IsAccessible (currentType))
 608                                                 continue;
 609
 610                                         if ((restrictions & MemberLookupRestrictions.InvocableOnly) != 0) {
 611                                                 if (member is MethodSpec)
 612                                                         return new MethodGroupExpr (members, queried_type, loc);
 613
 614                                                 if (!Invocation.IsMemberInvocable (member))
 615                                                         continue;
 616                                         }
 617
 618                                         if (non_method == null || member is MethodSpec) {
 619                                                 non_method = member;
 620                                         } else if (currentType != null) {
 621                                                 ambig_non_method = member;
 622                                         }
 623                                 }
 624
 625                                 if (non_method != null) {
 626                                         if (ambig_non_method != null && rc != null) {
 627                                                 rc.Report.SymbolRelatedToPreviousError (non_method);
 628                                                 rc.Report.SymbolRelatedToPreviousError (ambig_non_method);
 629                                                 rc.Report.Error (229, loc, "Ambiguity between `{0}' and `{1}'",
 630                                                         non_method.GetSignatureForError (), ambig_non_method.GetSignatureForError ());
 631                                         }
 632
 633                                         if (non_method is MethodSpec)
 634                                                 return new MethodGroupExpr (members, queried_type, loc);
 635
 636                                         return ExprClassFromMemberInfo (non_method, loc);
 637                                 }
 638
 639                                 if (members[0].DeclaringType.BaseType == null)
 640                                         members = null;
 641                                 else
 642                                         members = MemberCache.FindMembers (members[0].DeclaringType.BaseType, name, false);
 643
 644                         } while (members != null);
 645
 646                         return null;
 647                 }
 648
 649                 protected virtual void Error_NegativeArrayIndex (ResolveContext ec, Location loc)
 650                 {
 651                         throw new NotImplementedException ();
 652                 }
 653
 654                 protected void Error_PointerInsideExpressionTree (ResolveContext ec)
 655                 {
 656                         ec.Report.Error (1944, loc, "An expression tree cannot contain an unsafe pointer operation");
 657                 }
 658
 659                 /// <summary>
 660                 ///   Returns an expression that can be used to invoke operator true
 661                 ///   on the expression if it exists.
 662                 /// </summary>
 663                 protected static Expression GetOperatorTrue (ResolveContext ec, Expression e, Location loc)
 664                 {
 665                         return GetOperatorTrueOrFalse (ec, e, true, loc);
 666                 }
 667
 668                 /// <summary>
 669                 ///   Returns an expression that can be used to invoke operator false
 670                 ///   on the expression if it exists.
 671                 /// </summary>
 672                 static public Expression GetOperatorFalse (ResolveContext ec, Expression e, Location loc)
 673                 {
 674                         return GetOperatorTrueOrFalse (ec, e, false, loc);
 675                 }
 676
 677                 static Expression GetOperatorTrueOrFalse (ResolveContext ec, Expression e, bool is_true, Location loc)
 678                 {
 679                         var op = is_true ? Operator.OpType.True : Operator.OpType.False;
 680                         var methods = MemberCache.GetUserOperator (e.type, op, false);
 681                         if (methods == null)
 682                                 return null;
 683
 684                         Arguments arguments = new Arguments (1);
 685                         arguments.Add (new Argument (e));
 686
 687                         var res = new OverloadResolver (methods, OverloadResolver.Restrictions.BaseMembersIncluded | OverloadResolver.Restrictions.NoBaseMembers, loc);
 688                         var oper = res.ResolveOperator (ec, ref arguments);
 689
 690                         if (oper == null)
 691                                 return null;
 692
 693                         return new UserOperatorCall (oper, arguments, null, loc);
 694                 }
 695
 696                 public virtual string ExprClassName
 697                 {
 698                         get {
 699                                 switch (eclass){
 700                                 case ExprClass.Unresolved:
 701                                         return "Unresolved";
 702                                 case ExprClass.Value:
 703                                         return "value";
 704                                 case ExprClass.Variable:
 705                                         return "variable";
 706                                 case ExprClass.Namespace:
 707                                         return "namespace";
 708                                 case ExprClass.Type:
 709                                         return "type";
 710                                 case ExprClass.MethodGroup:
 711                                         return "method group";
 712                                 case ExprClass.PropertyAccess:
 713                                         return "property access";
 714                                 case ExprClass.EventAccess:
 715                                         return "event access";
 716                                 case ExprClass.IndexerAccess:
 717                                         return "indexer access";
 718                                 case ExprClass.Nothing:
 719                                         return "null";
 720                                 case ExprClass.TypeParameter:
 721                                         return "type parameter";
 722                                 }
 723                                 throw new Exception ("Should not happen");
 724                         }
 725                 }
 726
 727                 /// <summary>
 728                 ///   Reports that we were expecting `expr' to be of class `expected'
 729                 /// </summary>
 730                 public void Error_UnexpectedKind (Report r, MemberCore mc, string expected, Location loc)
 731                 {
 732                         Error_UnexpectedKind (r, mc, expected, ExprClassName, loc);
 733                 }
 734
 735                 public void Error_UnexpectedKind (Report r, MemberCore mc, string expected, string was, Location loc)
 736                 {
 737                         string name;
 738                         if (mc != null)
 739                                 name = mc.GetSignatureForError ();
 740                         else
 741                                 name = GetSignatureForError ();
 742
 743                         r.Error (118, loc, "`{0}' is a `{1}' but a `{2}' was expected",
 744                               name, was, expected);
 745                 }
 746
 747                 public void Error_UnexpectedKind (ResolveContext ec, ResolveFlags flags, Location loc)
 748                 {
 749                         string [] valid = new string [4];
 750                         int count = 0;
 751
 752                         if ((flags & ResolveFlags.VariableOrValue) != 0) {
 753                                 valid [count++] = "variable";
 754                                 valid [count++] = "value";
 755                         }
 756
 757                         if ((flags & ResolveFlags.Type) != 0)
 758                                 valid [count++] = "type";
 759
 760                         if ((flags & ResolveFlags.MethodGroup) != 0)
 761                                 valid [count++] = "method group";
 762
 763                         if (count == 0)
 764                                 valid [count++] = "unknown";
 765
 766                         StringBuilder sb = new StringBuilder (valid [0]);
 767                         for (int i = 1; i < count - 1; i++) {
 768                                 sb.Append ("', `");
 769                                 sb.Append (valid [i]);
 770                         }
 771                         if (count > 1) {
 772                                 sb.Append ("' or `");
 773                                 sb.Append (valid [count - 1]);
 774                         }
 775
 776                         ec.Report.Error (119, loc,
 777                                 "Expression denotes a `{0}', where a `{1}' was expected", ExprClassName, sb.ToString ());
 778                 }
 779
 780                 public static void UnsafeError (ResolveContext ec, Location loc)
 781                 {
 782                         UnsafeError (ec.Report, loc);
 783                 }
 784
 785                 public static void UnsafeError (Report Report, Location loc)
 786                 {
 787                         Report.Error (214, loc, "Pointers and fixed size buffers may only be used in an unsafe context");
 788                 }
 789
 790
 791                 //
 792                 // Returns the size of type `t' if known, otherwise, 0
 793                 //
 794                 public static int GetTypeSize (TypeSpec t)
 795                 {
 796                         if (t == TypeManager.int32_type ||
 797                             t == TypeManager.uint32_type ||
 798                             t == TypeManager.float_type)
 799                                 return 4;
 800                         else if (t == TypeManager.int64_type ||
 801                                  t == TypeManager.uint64_type ||
 802                                  t == TypeManager.double_type)
 803                                 return 8;
 804                         else if (t == TypeManager.byte_type ||
 805                                  t == TypeManager.sbyte_type ||
 806                                  t == TypeManager.bool_type)
 807                                 return 1;
 808                         else if (t == TypeManager.short_type ||
 809                                  t == TypeManager.char_type ||
 810                                  t == TypeManager.ushort_type)
 811                                 return 2;
 812                         else if (t == TypeManager.decimal_type)
 813                                 return 16;
 814                         else
 815                                 return 0;
 816                 }
 817
 818                 protected void Error_CannotModifyIntermediateExpressionValue (ResolveContext ec)
 819                 {
 820                         ec.Report.SymbolRelatedToPreviousError (type);
 821                         if (ec.CurrentInitializerVariable != null) {
 822                                 ec.Report.Error (1918, loc, "Members of value type `{0}' cannot be assigned using a property `{1}' object initializer",
 823                                         TypeManager.CSharpName (type), GetSignatureForError ());
 824                         } else {
 825                                 ec.Report.Error (1612, loc, "Cannot modify a value type return value of `{0}'. Consider storing the value in a temporary variable",
 826                                         GetSignatureForError ());
 827                         }
 828                 }
 829
 830                 //
 831                 // Converts `source' to an int, uint, long or ulong.
 832                 //
 833                 protected Expression ConvertExpressionToArrayIndex (ResolveContext ec, Expression source)
 834                 {
 835                         if (source.type == InternalType.Dynamic) {
 836                                 Arguments args = new Arguments (1);
 837                                 args.Add (new Argument (source));
 838                                 return new DynamicConversion (TypeManager.int32_type, CSharpBinderFlags.ConvertArrayIndex, args, loc).Resolve (ec);
 839                         }
 840
 841                         Expression converted;
 842
 843                         using (ec.Set (ResolveContext.Options.CheckedScope)) {
 844                                 converted = Convert.ImplicitConversion (ec, source, TypeManager.int32_type, source.loc);
 845                                 if (converted == null)
 846                                         converted = Convert.ImplicitConversion (ec, source, TypeManager.uint32_type, source.loc);
 847                                 if (converted == null)
 848                                         converted = Convert.ImplicitConversion (ec, source, TypeManager.int64_type, source.loc);
 849                                 if (converted == null)
 850                                         converted = Convert.ImplicitConversion (ec, source, TypeManager.uint64_type, source.loc);
 851
 852                                 if (converted == null) {
 853                                         source.Error_ValueCannotBeConverted (ec, source.loc, TypeManager.int32_type, false);
 854                                         return null;
 855                                 }
 856                         }
 857
 858                         //
 859                         // Only positive constants are allowed at compile time
 860                         //
 861                         Constant c = converted as Constant;
 862                         if (c != null && c.IsNegative)
 863                                 Error_NegativeArrayIndex (ec, source.loc);
 864
 865                         // No conversion needed to array index
 866                         if (converted.Type == TypeManager.int32_type)
 867                                 return converted;
 868
 869                         return new ArrayIndexCast (converted).Resolve (ec);
 870                 }
 871
 872                 //
 873                 // Derived classes implement this method by cloning the fields that
 874                 // could become altered during the Resolve stage
 875                 //
 876                 // Only expressions that are created for the parser need to implement
 877                 // this.
 878                 //
 879                 protected virtual void CloneTo (CloneContext clonectx, Expression target)
 880                 {
 881                         throw new NotImplementedException (
 882                                 String.Format (
 883                                         "CloneTo not implemented for expression {0}", this.GetType ()));
 884                 }
 885
 886                 //
 887                 // Clones an expression created by the parser.
 888                 //
 889                 // We only support expressions created by the parser so far, not
 890                 // expressions that have been resolved (many more classes would need
 891                 // to implement CloneTo).
 892                 //
 893                 // This infrastructure is here merely for Lambda expressions which
 894                 // compile the same code using different type values for the same
 895                 // arguments to find the correct overload
 896                 //
 897                 public virtual Expression Clone (CloneContext clonectx)
 898                 {
 899                         Expression cloned = (Expression) MemberwiseClone ();
 900                         CloneTo (clonectx, cloned);
 901
 902                         return cloned;
 903                 }
 904
 905                 //
 906                 // Implementation of expression to expression tree conversion
 907                 //
 908                 public abstract Expression CreateExpressionTree (ResolveContext ec);
 909
 910                 protected Expression CreateExpressionFactoryCall (ResolveContext ec, string name, Arguments args)
 911                 {
 912                         return CreateExpressionFactoryCall (ec, name, null, args, loc);
 913                 }
 914
 915                 protected Expression CreateExpressionFactoryCall (ResolveContext ec, string name, TypeArguments typeArguments, Arguments args)
 916                 {
 917                         return CreateExpressionFactoryCall (ec, name, typeArguments, args, loc);
 918                 }
 919
 920                 public static Expression CreateExpressionFactoryCall (ResolveContext ec, string name, TypeArguments typeArguments, Arguments args, Location loc)
 921                 {
 922                         return new Invocation (new MemberAccess (CreateExpressionTypeExpression (ec, loc), name, typeArguments, loc), args);
 923                 }
 924
 925                 protected static TypeExpr CreateExpressionTypeExpression (ResolveContext ec, Location loc)
 926                 {
 927                         TypeExpr texpr = TypeManager.expression_type_expr;
 928                         if (texpr == null) {
 929                                 TypeSpec t = TypeManager.CoreLookupType (ec.Compiler, "System.Linq.Expressions", "Expression", MemberKind.Class, true);
 930                                 if (t == null)
 931                                         return null;
 932
 933                                 TypeManager.expression_type_expr = texpr = new TypeExpression (t, Location.Null);
 934                         }
 935
 936                         return texpr;
 937                 }
 938
 939                 //
 940                 // Implemented by all expressions which support conversion from
 941                 // compiler expression to invokable runtime expression. Used by
 942                 // dynamic C# binder.
 943                 //
 944                 public virtual SLE.Expression MakeExpression (BuilderContext ctx)
 945                 {
 946                         throw new NotImplementedException ("MakeExpression for " + GetType ());
 947                 }
 948         }
 949
 950         /// <summary>
 951         ///   This is just a base class for expressions that can
 952         ///   appear on statements (invocations, object creation,
 953         ///   assignments, post/pre increment and decrement).  The idea
 954         ///   being that they would support an extra Emition interface that
 955         ///   does not leave a result on the stack.
 956         /// </summary>
 957         public abstract class ExpressionStatement : Expression {
 958
 959                 public ExpressionStatement ResolveStatement (BlockContext ec)
 960                 {
 961                         Expression e = Resolve (ec);
 962                         if (e == null)
 963                                 return null;
 964
 965                         ExpressionStatement es = e as ExpressionStatement;
 966                         if (es == null)
 967                                 Error_InvalidExpressionStatement (ec);
 968
 969                         return es;
 970                 }
 971
 972                 /// <summary>
 973                 ///   Requests the expression to be emitted in a `statement'
 974                 ///   context.  This means that no new value is left on the
 975                 ///   stack after invoking this method (constrasted with
 976                 ///   Emit that will always leave a value on the stack).
 977                 /// </summary>
 978                 public abstract void EmitStatement (EmitContext ec);
 979
 980                 public override void EmitSideEffect (EmitContext ec)
 981                 {
 982                         EmitStatement (ec);
 983                 }
 984         }
 985
 986         /// <summary>
 987         ///   This kind of cast is used to encapsulate the child
 988         ///   whose type is child.Type into an expression that is
 989         ///   reported to return "return_type".  This is used to encapsulate
 990         ///   expressions which have compatible types, but need to be dealt
 991         ///   at higher levels with.
 992         ///
 993         ///   For example, a "byte" expression could be encapsulated in one
 994         ///   of these as an "unsigned int".  The type for the expression
 995         ///   would be "unsigned int".
 996         ///
 997         /// </summary>
 998         public abstract class TypeCast : Expression
 999         {
1000                 protected readonly Expression child;
1001
1002                 protected TypeCast (Expression child, TypeSpec return_type)
1003                 {
1004                         eclass = child.eclass;
1005                         loc = child.Location;
1006                         type = return_type;
1007                         this.child = child;
1008                 }
1009
1010                 public Expression Child {
1011                         get {
1012                                 return child;
1013                         }
1014                 }
1015
1016                 public override Expression CreateExpressionTree (ResolveContext ec)
1017                 {
1018                         Arguments args = new Arguments (2);
1019                         args.Add (new Argument (child.CreateExpressionTree (ec)));
1020                         args.Add (new Argument (new TypeOf (new TypeExpression (type, loc), loc)));
1021
1022                         if (type.IsPointer || child.Type.IsPointer)
1023                                 Error_PointerInsideExpressionTree (ec);
1024
1025                         return CreateExpressionFactoryCall (ec, ec.HasSet (ResolveContext.Options.CheckedScope) ? "ConvertChecked" : "Convert", args);
1026                 }
1027
1028                 protected override Expression DoResolve (ResolveContext ec)
1029                 {
1030                         // This should never be invoked, we are born in fully
1031                         // initialized state.
1032
1033                         return this;
1034                 }
1035
1036                 public override void Emit (EmitContext ec)
1037                 {
1038                         child.Emit (ec);
1039                 }
1040
1041                 public override SLE.Expression MakeExpression (BuilderContext ctx)
1042                 {
1043                         return ctx.HasSet (BuilderContext.Options.CheckedScope) ?
1044                                 SLE.Expression.ConvertChecked (child.MakeExpression (ctx), type.GetMetaInfo ()) :
1045                                 SLE.Expression.Convert (child.MakeExpression (ctx), type.GetMetaInfo ());
1046                 }
1047
1048                 protected override void CloneTo (CloneContext clonectx, Expression t)
1049                 {
1050                         // Nothing to clone
1051                 }
1052
1053                 public override bool IsNull {
1054                         get { return child.IsNull; }
1055                 }
1056         }
1057
1058         public class EmptyCast : TypeCast {
1059                 EmptyCast (Expression child, TypeSpec target_type)
1060                         : base (child, target_type)
1061                 {
1062                 }
1063
1064                 public static Expression Create (Expression child, TypeSpec type)
1065                 {
1066                         Constant c = child as Constant;
1067                         if (c != null)
1068                                 return new EmptyConstantCast (c, type);
1069
1070                         EmptyCast e = child as EmptyCast;
1071                         if (e != null)
1072                                 return new EmptyCast (e.child, type);
1073
1074                         return new EmptyCast (child, type);
1075                 }
1076
1077                 public override void EmitBranchable (EmitContext ec, Label label, bool on_true)
1078                 {
1079                         child.EmitBranchable (ec, label, on_true);
1080                 }
1081
1082                 public override void EmitSideEffect (EmitContext ec)
1083                 {
1084                         child.EmitSideEffect (ec);
1085                 }
1086         }
1087
1088         //
1089         // Used for predefined class library user casts (no obsolete check, etc.)
1090         //
1091         public class OperatorCast : TypeCast {
1092                 MethodSpec conversion_operator;
1093
1094                 public OperatorCast (Expression child, TypeSpec target_type)
1095                         : this (child, target_type, false)
1096                 {
1097                 }
1098
1099                 public OperatorCast (Expression child, TypeSpec target_type, bool find_explicit)
1100                         : base (child, target_type)
1101                 {
1102                         conversion_operator = GetConversionOperator (find_explicit);
1103                         if (conversion_operator == null)
1104                                 throw new InternalErrorException ("Outer conversion routine is out of sync");
1105                 }
1106
1107                 // Returns the implicit operator that converts from
1108                 // 'child.Type' to our target type (type)
1109                 MethodSpec GetConversionOperator (bool find_explicit)
1110                 {
1111                         var op = find_explicit ? Operator.OpType.Explicit : Operator.OpType.Implicit;
1112
1113                         var mi = MemberCache.GetUserOperator (child.Type, op, true);
1114                         if (mi == null){
1115                                 mi = MemberCache.GetUserOperator (type, op, true);
1116                         }
1117
1118                         foreach (MethodSpec oper in mi) {
1119                                 if (oper.ReturnType != type)
1120                                         continue;
1121
1122                                 if (oper.Parameters.Types [0] == child.Type)
1123                                         return oper;
1124                         }
1125
1126                         return null;
1127                 }
1128
1129                 public override void Emit (EmitContext ec)
1130                 {
1131                         child.Emit (ec);
1132                         ec.Emit (OpCodes.Call, conversion_operator);
1133                 }
1134         }
1135
1136         /// <summary>
1137         ///     This is a numeric cast to a Decimal
1138         /// </summary>
1139         public class CastToDecimal : OperatorCast {
1140                 public CastToDecimal (Expression child)
1141                         : this (child, false)
1142                 {
1143                 }
1144
1145                 public CastToDecimal (Expression child, bool find_explicit)
1146                         : base (child, TypeManager.decimal_type, find_explicit)
1147                 {
1148                 }
1149         }
1150
1151         /// <summary>
1152         ///     This is an explicit numeric cast from a Decimal
1153         /// </summary>
1154         public class CastFromDecimal : TypeCast
1155         {
1156                 static Dictionary<TypeSpec, MethodSpec> operators;
1157
1158                 public CastFromDecimal (Expression child, TypeSpec return_type)
1159                         : base (child, return_type)
1160                 {
1161                         if (child.Type != TypeManager.decimal_type)
1162                                 throw new ArgumentException ("Expected decimal child " + child.Type.GetSignatureForError ());
1163                 }
1164
1165                 // Returns the explicit operator that converts from an
1166                 // express of type System.Decimal to 'type'.
1167                 public Expression Resolve ()
1168                 {
1169                         if (operators == null) {
1170                                 var all_oper = MemberCache.GetUserOperator (TypeManager.decimal_type, Operator.OpType.Explicit, true);
1171
1172                                 operators = new Dictionary<TypeSpec, MethodSpec> ();
1173                                 foreach (MethodSpec oper in all_oper) {
1174                                         AParametersCollection pd = oper.Parameters;
1175                                         if (pd.Types [0] == TypeManager.decimal_type)
1176                                                 operators.Add (oper.ReturnType, oper);
1177                                 }
1178                         }
1179
1180                         return operators.ContainsKey (type) ? this : null;
1181                 }
1182
1183                 public override void Emit (EmitContext ec)
1184                 {
1185                         child.Emit (ec);
1186
1187                         ec.Emit (OpCodes.Call, operators [type]);
1188                 }
1189
1190                 public static void Reset ()
1191                 {
1192                         operators = null;
1193                 }
1194         }
1195
1196
1197         //
1198         // Constant specialization of EmptyCast.
1199         // We need to special case this since an empty cast of
1200         // a constant is still a constant.
1201         //
1202         public class EmptyConstantCast : Constant
1203         {
1204                 public Constant child;
1205
1206                 public EmptyConstantCast (Constant child, TypeSpec type)
1207                         : base (child.Location)
1208                 {
1209                         if (child == null)
1210                                 throw new ArgumentNullException ("child");
1211
1212                         this.child = child;
1213                         this.eclass = child.eclass;
1214                         this.type = type;
1215                 }
1216
1217                 public override string AsString ()
1218                 {
1219                         return child.AsString ();
1220                 }
1221
1222                 public override object GetValue ()
1223                 {
1224                         return child.GetValue ();
1225                 }
1226
1227                 public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
1228                 {
1229                         if (child.Type == target_type)
1230                                 return child;
1231
1232                         // FIXME: check that 'type' can be converted to 'target_type' first
1233                         return child.ConvertExplicitly (in_checked_context, target_type);
1234                 }
1235
1236                 public override Expression CreateExpressionTree (ResolveContext ec)
1237                 {
1238                         Arguments args = Arguments.CreateForExpressionTree (ec, null,
1239                                 child.CreateExpressionTree (ec),
1240                                 new TypeOf (new TypeExpression (type, loc), loc));
1241
1242                         if (type.IsPointer)
1243                                 Error_PointerInsideExpressionTree (ec);
1244
1245                         return CreateExpressionFactoryCall (ec, "Convert", args);
1246                 }
1247
1248                 public override bool IsDefaultValue {
1249                         get { return child.IsDefaultValue; }
1250                 }
1251
1252                 public override bool IsNegative {
1253                         get { return child.IsNegative; }
1254                 }
1255
1256                 public override bool IsNull {
1257                         get { return child.IsNull; }
1258                 }
1259
1260                 public override bool IsOneInteger {
1261                         get { return child.IsOneInteger; }
1262                 }
1263
1264                 public override bool IsZeroInteger {
1265                         get { return child.IsZeroInteger; }
1266                 }
1267
1268                 protected override Expression DoResolve (ResolveContext rc)
1269                 {
1270                         return this;
1271                 }
1272
1273                 public override void Emit (EmitContext ec)
1274                 {
1275                         child.Emit (ec);
1276                 }
1277
1278                 public override void EmitBranchable (EmitContext ec, Label label, bool on_true)
1279                 {
1280                         child.EmitBranchable (ec, label, on_true);
1281
1282                         // Only to make verifier happy
1283                         if (TypeManager.IsGenericParameter (type) && child.IsNull)
1284                                 ec.Emit (OpCodes.Unbox_Any, type);
1285                 }
1286
1287                 public override void EmitSideEffect (EmitContext ec)
1288                 {
1289                         child.EmitSideEffect (ec);
1290                 }
1291
1292                 public override Constant ConvertImplicitly (ResolveContext rc, TypeSpec target_type)
1293                 {
1294                         // FIXME: Do we need to check user conversions?
1295                         if (!Convert.ImplicitStandardConversionExists (this, target_type))
1296                                 return null;
1297                         return child.ConvertImplicitly (rc, target_type);
1298                 }
1299         }
1300
1301         /// <summary>
1302         ///  This class is used to wrap literals which belong inside Enums
1303         /// </summary>
1304         public class EnumConstant : Constant
1305         {
1306                 public Constant Child;
1307
1308                 public EnumConstant (Constant child, TypeSpec enum_type)
1309                         : base (child.Location)
1310                 {
1311                         this.Child = child;
1312                         this.type = enum_type;
1313                 }
1314
1315                 protected EnumConstant (Location loc)
1316                         : base (loc)
1317                 {
1318                 }
1319
1320                 protected override Expression DoResolve (ResolveContext rc)
1321                 {
1322                         Child = Child.Resolve (rc);
1323                         this.eclass = ExprClass.Value;
1324                         return this;
1325                 }
1326
1327                 public override void Emit (EmitContext ec)
1328                 {
1329                         Child.Emit (ec);
1330                 }
1331
1332                 public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
1333                 {
1334                         Child.EncodeAttributeValue (rc, enc, Child.Type);
1335                 }
1336
1337                 public override void EmitBranchable (EmitContext ec, Label label, bool on_true)
1338                 {
1339                         Child.EmitBranchable (ec, label, on_true);
1340                 }
1341
1342                 public override void EmitSideEffect (EmitContext ec)
1343                 {
1344                         Child.EmitSideEffect (ec);
1345                 }
1346
1347                 public override string GetSignatureForError()
1348                 {
1349                         return TypeManager.CSharpName (Type);
1350                 }
1351
1352                 public override object GetValue ()
1353                 {
1354                         return Child.GetValue ();
1355                 }
1356
1357                 public override object GetTypedValue ()
1358                 {
1359                         // FIXME: runtime is not ready to work with just emited enums
1360                         if (!RootContext.StdLib) {
1361                                 return Child.GetValue ();
1362                         }
1363
1364 #if MS_COMPATIBLE
1365                         // Small workaround for big problem
1366                         // System.Enum.ToObject cannot be called on dynamic types
1367                         // EnumBuilder has to be used, but we cannot use EnumBuilder
1368                         // because it does not properly support generics
1369                         //
1370                         // This works only sometimes
1371                         //
1372                         if (type.MemberDefinition is TypeContainer)
1373                                 return Child.GetValue ();
1374 #endif
1375
1376                         return System.Enum.ToObject (type.GetMetaInfo (), Child.GetValue ());
1377                 }
1378
1379                 public override string AsString ()
1380                 {
1381                         return Child.AsString ();
1382                 }
1383
1384                 public EnumConstant Increment()
1385                 {
1386                         return new EnumConstant (((IntegralConstant) Child).Increment (), type);
1387                 }
1388
1389                 public override bool IsDefaultValue {
1390                         get {
1391                                 return Child.IsDefaultValue;
1392                         }
1393                 }
1394
1395                 public override bool IsZeroInteger {
1396                         get { return Child.IsZeroInteger; }
1397                 }
1398
1399                 public override bool IsNegative {
1400                         get {
1401                                 return Child.IsNegative;
1402                         }
1403                 }
1404
1405                 public override Constant ConvertExplicitly(bool in_checked_context, TypeSpec target_type)
1406                 {
1407                         if (Child.Type == target_type)
1408                                 return Child;
1409
1410                         return Child.ConvertExplicitly (in_checked_context, target_type);
1411                 }
1412
1413                 public override Constant ConvertImplicitly (ResolveContext rc, TypeSpec type)
1414                 {
1415                         if (this.type == type) {
1416                                 return this;
1417                         }
1418
1419                         if (!Convert.ImplicitStandardConversionExists (this, type)){
1420                                 return null;
1421                         }
1422
1423                         return Child.ConvertImplicitly (rc, type);
1424                 }
1425         }
1426
1427         /// <summary>
1428         ///   This kind of cast is used to encapsulate Value Types in objects.
1429         ///
1430         ///   The effect of it is to box the value type emitted by the previous
1431         ///   operation.
1432         /// </summary>
1433         public class BoxedCast : TypeCast {
1434
1435                 public BoxedCast (Expression expr, TypeSpec target_type)
1436                         : base (expr, target_type)
1437                 {
1438                         eclass = ExprClass.Value;
1439                 }
1440
1441                 protected override Expression DoResolve (ResolveContext ec)
1442                 {
1443                         // This should never be invoked, we are born in fully
1444                         // initialized state.
1445
1446                         return this;
1447                 }
1448
1449                 public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
1450                 {
1451                         enc.Encode (child.Type);
1452                         child.EncodeAttributeValue (rc, enc, child.Type);
1453                 }
1454
1455                 public override void Emit (EmitContext ec)
1456                 {
1457                         base.Emit (ec);
1458
1459                         ec.Emit (OpCodes.Box, child.Type);
1460                 }
1461
1462                 public override void EmitSideEffect (EmitContext ec)
1463                 {
1464                         // boxing is side-effectful, since it involves runtime checks, except when boxing to Object or ValueType
1465                         // so, we need to emit the box+pop instructions in most cases
1466                         if (TypeManager.IsStruct (child.Type) &&
1467                             (type == TypeManager.object_type || type == TypeManager.value_type))
1468                                 child.EmitSideEffect (ec);
1469                         else
1470                                 base.EmitSideEffect (ec);
1471                 }
1472         }
1473
1474         public class UnboxCast : TypeCast {
1475                 public UnboxCast (Expression expr, TypeSpec return_type)
1476                         : base (expr, return_type)
1477                 {
1478                 }
1479
1480                 protected override Expression DoResolve (ResolveContext ec)
1481                 {
1482                         // This should never be invoked, we are born in fully
1483                         // initialized state.
1484
1485                         return this;
1486                 }
1487
1488                 public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
1489                 {
1490                         if (right_side == EmptyExpression.LValueMemberAccess || right_side == EmptyExpression.LValueMemberOutAccess)
1491                                 ec.Report.Error (445, loc, "Cannot modify the result of an unboxing conversion");
1492                         return base.DoResolveLValue (ec, right_side);
1493                 }
1494
1495                 public override void Emit (EmitContext ec)
1496                 {
1497                         base.Emit (ec);
1498
1499                         ec.Emit (OpCodes.Unbox_Any, type);
1500                 }
1501         }
1502
1503         /// <summary>
1504         ///   This is used to perform explicit numeric conversions.
1505         ///
1506         ///   Explicit numeric conversions might trigger exceptions in a checked
1507         ///   context, so they should generate the conv.ovf opcodes instead of
1508         ///   conv opcodes.
1509         /// </summary>
1510         public class ConvCast : TypeCast {
1511                 public enum Mode : byte {
1512                         I1_U1, I1_U2, I1_U4, I1_U8, I1_CH,
1513                         U1_I1, U1_CH,
1514                         I2_I1, I2_U1, I2_U2, I2_U4, I2_U8, I2_CH,
1515                         U2_I1, U2_U1, U2_I2, U2_CH,
1516                         I4_I1, I4_U1, I4_I2, I4_U2, I4_U4, I4_U8, I4_CH,
1517                         U4_I1, U4_U1, U4_I2, U4_U2, U4_I4, U4_CH,
1518                         I8_I1, I8_U1, I8_I2, I8_U2, I8_I4, I8_U4, I8_U8, I8_CH, I8_I,
1519                         U8_I1, U8_U1, U8_I2, U8_U2, U8_I4, U8_U4, U8_I8, U8_CH, U8_I,
1520                         CH_I1, CH_U1, CH_I2,
1521                         R4_I1, R4_U1, R4_I2, R4_U2, R4_I4, R4_U4, R4_I8, R4_U8, R4_CH,
1522                         R8_I1, R8_U1, R8_I2, R8_U2, R8_I4, R8_U4, R8_I8, R8_U8, R8_CH, R8_R4,
1523                         I_I8,
1524                 }
1525
1526                 Mode mode;
1527
1528                 public ConvCast (Expression child, TypeSpec return_type, Mode m)
1529                         : base (child, return_type)
1530                 {
1531                         mode = m;
1532                 }
1533
1534                 protected override Expression DoResolve (ResolveContext ec)
1535                 {
1536                         // This should never be invoked, we are born in fully
1537                         // initialized state.
1538
1539                         return this;
1540                 }
1541
1542                 public override string ToString ()
1543                 {
1544                         return String.Format ("ConvCast ({0}, {1})", mode, child);
1545                 }
1546
1547                 public override void Emit (EmitContext ec)
1548                 {
1549                         base.Emit (ec);
1550
1551                         if (ec.HasSet (EmitContext.Options.CheckedScope)) {
1552                                 switch (mode){
1553                                 case Mode.I1_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1554                                 case Mode.I1_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1555                                 case Mode.I1_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1556                                 case Mode.I1_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1557                                 case Mode.I1_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1558
1559                                 case Mode.U1_I1: ec.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1560                                 case Mode.U1_CH: /* nothing */ break;
1561
1562                                 case Mode.I2_I1: ec.Emit (OpCodes.Conv_Ovf_I1); break;
1563                                 case Mode.I2_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1564                                 case Mode.I2_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1565                                 case Mode.I2_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1566                                 case Mode.I2_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1567                                 case Mode.I2_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1568
1569                                 case Mode.U2_I1: ec.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1570                                 case Mode.U2_U1: ec.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1571                                 case Mode.U2_I2: ec.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1572                                 case Mode.U2_CH: /* nothing */ break;
1573
1574                                 case Mode.I4_I1: ec.Emit (OpCodes.Conv_Ovf_I1); break;
1575                                 case Mode.I4_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1576                                 case Mode.I4_I2: ec.Emit (OpCodes.Conv_Ovf_I2); break;
1577                                 case Mode.I4_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1578                                 case Mode.I4_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1579                                 case Mode.I4_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1580                                 case Mode.I4_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1581
1582                                 case Mode.U4_I1: ec.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1583                                 case Mode.U4_U1: ec.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1584                                 case Mode.U4_I2: ec.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1585                                 case Mode.U4_U2: ec.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1586                                 case Mode.U4_I4: ec.Emit (OpCodes.Conv_Ovf_I4_Un); break;
1587                                 case Mode.U4_CH: ec.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1588
1589                                 case Mode.I8_I1: ec.Emit (OpCodes.Conv_Ovf_I1); break;
1590                                 case Mode.I8_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1591                                 case Mode.I8_I2: ec.Emit (OpCodes.Conv_Ovf_I2); break;
1592                                 case Mode.I8_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1593                                 case Mode.I8_I4: ec.Emit (OpCodes.Conv_Ovf_I4); break;
1594                                 case Mode.I8_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1595                                 case Mode.I8_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1596                                 case Mode.I8_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1597                                 case Mode.I8_I: ec.Emit (OpCodes.Conv_Ovf_U); break;
1598
1599                                 case Mode.U8_I1: ec.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1600                                 case Mode.U8_U1: ec.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1601                                 case Mode.U8_I2: ec.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1602                                 case Mode.U8_U2: ec.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1603                                 case Mode.U8_I4: ec.Emit (OpCodes.Conv_Ovf_I4_Un); break;
1604                                 case Mode.U8_U4: ec.Emit (OpCodes.Conv_Ovf_U4_Un); break;
1605                                 case Mode.U8_I8: ec.Emit (OpCodes.Conv_Ovf_I8_Un); break;
1606                                 case Mode.U8_CH: ec.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1607                                 case Mode.U8_I: ec.Emit (OpCodes.Conv_Ovf_U_Un); break;
1608
1609                                 case Mode.CH_I1: ec.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1610                                 case Mode.CH_U1: ec.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1611                                 case Mode.CH_I2: ec.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1612
1613                                 case Mode.R4_I1: ec.Emit (OpCodes.Conv_Ovf_I1); break;
1614                                 case Mode.R4_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1615                                 case Mode.R4_I2: ec.Emit (OpCodes.Conv_Ovf_I2); break;
1616                                 case Mode.R4_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1617                                 case Mode.R4_I4: ec.Emit (OpCodes.Conv_Ovf_I4); break;
1618                                 case Mode.R4_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1619                                 case Mode.R4_I8: ec.Emit (OpCodes.Conv_Ovf_I8); break;
1620                                 case Mode.R4_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1621                                 case Mode.R4_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1622
1623                                 case Mode.R8_I1: ec.Emit (OpCodes.Conv_Ovf_I1); break;
1624                                 case Mode.R8_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1625                                 case Mode.R8_I2: ec.Emit (OpCodes.Conv_Ovf_I2); break;
1626                                 case Mode.R8_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1627                                 case Mode.R8_I4: ec.Emit (OpCodes.Conv_Ovf_I4); break;
1628                                 case Mode.R8_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1629                                 case Mode.R8_I8: ec.Emit (OpCodes.Conv_Ovf_I8); break;
1630                                 case Mode.R8_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1631                                 case Mode.R8_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1632                                 case Mode.R8_R4: ec.Emit (OpCodes.Conv_R4); break;
1633
1634                                 case Mode.I_I8: ec.Emit (OpCodes.Conv_Ovf_I8_Un); break;
1635                                 }
1636                         } else {
1637                                 switch (mode){
1638                                 case Mode.I1_U1: ec.Emit (OpCodes.Conv_U1); break;
1639                                 case Mode.I1_U2: ec.Emit (OpCodes.Conv_U2); break;
1640                                 case Mode.I1_U4: ec.Emit (OpCodes.Conv_U4); break;
1641                                 case Mode.I1_U8: ec.Emit (OpCodes.Conv_I8); break;
1642                                 case Mode.I1_CH: ec.Emit (OpCodes.Conv_U2); break;
1643
1644                                 case Mode.U1_I1: ec.Emit (OpCodes.Conv_I1); break;
1645                                 case Mode.U1_CH: ec.Emit (OpCodes.Conv_U2); break;
1646
1647                                 case Mode.I2_I1: ec.Emit (OpCodes.Conv_I1); break;
1648                                 case Mode.I2_U1: ec.Emit (OpCodes.Conv_U1); break;
1649                                 case Mode.I2_U2: ec.Emit (OpCodes.Conv_U2); break;
1650                                 case Mode.I2_U4: ec.Emit (OpCodes.Conv_U4); break;
1651                                 case Mode.I2_U8: ec.Emit (OpCodes.Conv_I8); break;
1652                                 case Mode.I2_CH: ec.Emit (OpCodes.Conv_U2); break;
1653
1654                                 case Mode.U2_I1: ec.Emit (OpCodes.Conv_I1); break;
1655                                 case Mode.U2_U1: ec.Emit (OpCodes.Conv_U1); break;
1656                                 case Mode.U2_I2: ec.Emit (OpCodes.Conv_I2); break;
1657                                 case Mode.U2_CH: /* nothing */ break;
1658
1659                                 case Mode.I4_I1: ec.Emit (OpCodes.Conv_I1); break;
1660                                 case Mode.I4_U1: ec.Emit (OpCodes.Conv_U1); break;
1661                                 case Mode.I4_I2: ec.Emit (OpCodes.Conv_I2); break;
1662                                 case Mode.I4_U4: /* nothing */ break;
1663                                 case Mode.I4_U2: ec.Emit (OpCodes.Conv_U2); break;
1664                                 case Mode.I4_U8: ec.Emit (OpCodes.Conv_I8); break;
1665                                 case Mode.I4_CH: ec.Emit (OpCodes.Conv_U2); break;
1666
1667                                 case Mode.U4_I1: ec.Emit (OpCodes.Conv_I1); break;
1668                                 case Mode.U4_U1: ec.Emit (OpCodes.Conv_U1); break;
1669                                 case Mode.U4_I2: ec.Emit (OpCodes.Conv_I2); break;
1670                                 case Mode.U4_U2: ec.Emit (OpCodes.Conv_U2); break;
1671                                 case Mode.U4_I4: /* nothing */ break;
1672                                 case Mode.U4_CH: ec.Emit (OpCodes.Conv_U2); break;
1673
1674                                 case Mode.I8_I1: ec.Emit (OpCodes.Conv_I1); break;
1675                                 case Mode.I8_U1: ec.Emit (OpCodes.Conv_U1); break;
1676                                 case Mode.I8_I2: ec.Emit (OpCodes.Conv_I2); break;
1677                                 case Mode.I8_U2: ec.Emit (OpCodes.Conv_U2); break;
1678                                 case Mode.I8_I4: ec.Emit (OpCodes.Conv_I4); break;
1679                                 case Mode.I8_U4: ec.Emit (OpCodes.Conv_U4); break;
1680                                 case Mode.I8_U8: /* nothing */ break;
1681                                 case Mode.I8_CH: ec.Emit (OpCodes.Conv_U2); break;
1682                                 case Mode.I8_I: ec.Emit (OpCodes.Conv_U); break;
1683
1684                                 case Mode.U8_I1: ec.Emit (OpCodes.Conv_I1); break;
1685                                 case Mode.U8_U1: ec.Emit (OpCodes.Conv_U1); break;
1686                                 case Mode.U8_I2: ec.Emit (OpCodes.Conv_I2); break;
1687                                 case Mode.U8_U2: ec.Emit (OpCodes.Conv_U2); break;
1688                                 case Mode.U8_I4: ec.Emit (OpCodes.Conv_I4); break;
1689                                 case Mode.U8_U4: ec.Emit (OpCodes.Conv_U4); break;
1690                                 case Mode.U8_I8: /* nothing */ break;
1691                                 case Mode.U8_CH: ec.Emit (OpCodes.Conv_U2); break;
1692                                 case Mode.U8_I: ec.Emit (OpCodes.Conv_U); break;
1693
1694                                 case Mode.CH_I1: ec.Emit (OpCodes.Conv_I1); break;
1695                                 case Mode.CH_U1: ec.Emit (OpCodes.Conv_U1); break;
1696                                 case Mode.CH_I2: ec.Emit (OpCodes.Conv_I2); break;
1697
1698                                 case Mode.R4_I1: ec.Emit (OpCodes.Conv_I1); break;
1699                                 case Mode.R4_U1: ec.Emit (OpCodes.Conv_U1); break;
1700                                 case Mode.R4_I2: ec.Emit (OpCodes.Conv_I2); break;
1701                                 case Mode.R4_U2: ec.Emit (OpCodes.Conv_U2); break;
1702                                 case Mode.R4_I4: ec.Emit (OpCodes.Conv_I4); break;
1703                                 case Mode.R4_U4: ec.Emit (OpCodes.Conv_U4); break;
1704                                 case Mode.R4_I8: ec.Emit (OpCodes.Conv_I8); break;
1705                                 case Mode.R4_U8: ec.Emit (OpCodes.Conv_U8); break;
1706                                 case Mode.R4_CH: ec.Emit (OpCodes.Conv_U2); break;
1707
1708                                 case Mode.R8_I1: ec.Emit (OpCodes.Conv_I1); break;
1709                                 case Mode.R8_U1: ec.Emit (OpCodes.Conv_U1); break;
1710                                 case Mode.R8_I2: ec.Emit (OpCodes.Conv_I2); break;
1711                                 case Mode.R8_U2: ec.Emit (OpCodes.Conv_U2); break;
1712                                 case Mode.R8_I4: ec.Emit (OpCodes.Conv_I4); break;
1713                                 case Mode.R8_U4: ec.Emit (OpCodes.Conv_U4); break;
1714                                 case Mode.R8_I8: ec.Emit (OpCodes.Conv_I8); break;
1715                                 case Mode.R8_U8: ec.Emit (OpCodes.Conv_U8); break;
1716                                 case Mode.R8_CH: ec.Emit (OpCodes.Conv_U2); break;
1717                                 case Mode.R8_R4: ec.Emit (OpCodes.Conv_R4); break;
1718
1719                                 case Mode.I_I8: ec.Emit (OpCodes.Conv_U8); break;
1720                                 }
1721                         }
1722                 }
1723         }
1724
1725         public class OpcodeCast : TypeCast {
1726                 readonly OpCode op;
1727
1728                 public OpcodeCast (Expression child, TypeSpec return_type, OpCode op)
1729                         : base (child, return_type)
1730                 {
1731                         this.op = op;
1732                 }
1733
1734                 protected override Expression DoResolve (ResolveContext ec)
1735                 {
1736                         // This should never be invoked, we are born in fully
1737                         // initialized state.
1738
1739                         return this;
1740                 }
1741
1742                 public override void Emit (EmitContext ec)
1743                 {
1744                         base.Emit (ec);
1745                         ec.Emit (op);
1746                 }
1747
1748                 public TypeSpec UnderlyingType {
1749                         get { return child.Type; }
1750                 }
1751         }
1752
1753         /// <summary>
1754         ///   This kind of cast is used to encapsulate a child and cast it
1755         ///   to the class requested
1756         /// </summary>
1757         public sealed class ClassCast : TypeCast {
1758                 readonly bool forced;
1759
1760                 public ClassCast (Expression child, TypeSpec return_type)
1761                         : base (child, return_type)
1762                 {
1763                 }
1764
1765                 public ClassCast (Expression child, TypeSpec return_type, bool forced)
1766                         : base (child, return_type)
1767                 {
1768                         this.forced = forced;
1769                 }
1770
1771                 public override void Emit (EmitContext ec)
1772                 {
1773                         base.Emit (ec);
1774
1775                         bool gen = TypeManager.IsGenericParameter (child.Type);
1776                         if (gen)
1777                                 ec.Emit (OpCodes.Box, child.Type);
1778
1779                         if (type.IsGenericParameter) {
1780                                 ec.Emit (OpCodes.Unbox_Any, type);
1781                                 return;
1782                         }
1783
1784                         if (gen && !forced)
1785                                 return;
1786
1787                         ec.Emit (OpCodes.Castclass, type);
1788                 }
1789         }
1790
1791         //
1792         // Created during resolving pahse when an expression is wrapped or constantified
1793         // and original expression can be used later (e.g. for expression trees)
1794         //
1795         public class ReducedExpression : Expression
1796         {
1797                 sealed class ReducedConstantExpression : EmptyConstantCast
1798                 {
1799                         readonly Expression orig_expr;
1800
1801                         public ReducedConstantExpression (Constant expr, Expression orig_expr)
1802                                 : base (expr, expr.Type)
1803                         {
1804                                 this.orig_expr = orig_expr;
1805                         }
1806
1807                         public override Constant ConvertImplicitly (ResolveContext rc, TypeSpec target_type)
1808                         {
1809                                 Constant c = base.ConvertImplicitly (rc, target_type);
1810                                 if (c != null)
1811                                         c = new ReducedConstantExpression (c, orig_expr);
1812
1813                                 return c;
1814                         }
1815
1816                         public override Expression CreateExpressionTree (ResolveContext ec)
1817                         {
1818                                 return orig_expr.CreateExpressionTree (ec);
1819                         }
1820
1821                         public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
1822                         {
1823                                 Constant c = base.ConvertExplicitly (in_checked_context, target_type);
1824                                 if (c != null)
1825                                         c = new ReducedConstantExpression (c, orig_expr);
1826                                 return c;
1827                         }
1828                 }
1829
1830                 sealed class ReducedExpressionStatement : ExpressionStatement
1831                 {
1832                         readonly Expression orig_expr;
1833                         readonly ExpressionStatement stm;
1834
1835                         public ReducedExpressionStatement (ExpressionStatement stm, Expression orig)
1836                         {
1837                                 this.orig_expr = orig;
1838                                 this.stm = stm;
1839                                 this.loc = orig.Location;
1840                         }
1841
1842                         public override Expression CreateExpressionTree (ResolveContext ec)
1843                         {
1844                                 return orig_expr.CreateExpressionTree (ec);
1845                         }
1846
1847                         protected override Expression DoResolve (ResolveContext ec)
1848                         {
1849                                 eclass = stm.eclass;
1850                                 type = stm.Type;
1851                                 return this;
1852                         }
1853
1854                         public override void Emit (EmitContext ec)
1855                         {
1856                                 stm.Emit (ec);
1857                         }
1858
1859                         public override void EmitStatement (EmitContext ec)
1860                         {
1861                                 stm.EmitStatement (ec);
1862                         }
1863                 }
1864
1865                 readonly Expression expr, orig_expr;
1866
1867                 private ReducedExpression (Expression expr, Expression orig_expr)
1868                 {
1869                         this.expr = expr;
1870                         this.eclass = expr.eclass;
1871                         this.type = expr.Type;
1872                         this.orig_expr = orig_expr;
1873                         this.loc = orig_expr.Location;
1874                 }
1875
1876                 #region Properties
1877
1878                 public Expression OriginalExpression {
1879                         get {
1880                                 return orig_expr;
1881                         }
1882                 }
1883
1884                 #endregion
1885
1886                 //
1887                 // Creates fully resolved expression switcher
1888                 //
1889                 public static Constant Create (Constant expr, Expression original_expr)
1890                 {
1891                         if (expr.eclass == ExprClass.Unresolved)
1892                                 throw new ArgumentException ("Unresolved expression");
1893
1894                         return new ReducedConstantExpression (expr, original_expr);
1895                 }
1896
1897                 public static ExpressionStatement Create (ExpressionStatement s, Expression orig)
1898                 {
1899                         return new ReducedExpressionStatement (s, orig);
1900                 }
1901
1902                 //
1903                 // Creates unresolved reduce expression. The original expression has to be
1904                 // already resolved
1905                 //
1906                 public static Expression Create (Expression expr, Expression original_expr)
1907                 {
1908                         Constant c = expr as Constant;
1909                         if (c != null)
1910                                 return Create (c, original_expr);
1911
1912                         ExpressionStatement s = expr as ExpressionStatement;
1913                         if (s != null)
1914                                 return Create (s, original_expr);
1915
1916                         if (expr.eclass == ExprClass.Unresolved)
1917                                 throw new ArgumentException ("Unresolved expression");
1918
1919                         return new ReducedExpression (expr, original_expr);
1920                 }
1921
1922                 public override Expression CreateExpressionTree (ResolveContext ec)
1923                 {
1924                         return orig_expr.CreateExpressionTree (ec);
1925                 }
1926
1927                 protected override Expression DoResolve (ResolveContext ec)
1928                 {
1929                         return this;
1930                 }
1931
1932                 public override void Emit (EmitContext ec)
1933                 {
1934                         expr.Emit (ec);
1935                 }
1936
1937                 public override void EmitBranchable (EmitContext ec, Label target, bool on_true)
1938                 {
1939                         expr.EmitBranchable (ec, target, on_true);
1940                 }
1941
1942                 public override SLE.Expression MakeExpression (BuilderContext ctx)
1943                 {
1944                         return orig_expr.MakeExpression (ctx);
1945                 }
1946         }
1947
1948         //
1949         // Standard composite pattern
1950         //
1951         public abstract class CompositeExpression : Expression
1952         {
1953                 Expression expr;
1954
1955                 protected CompositeExpression (Expression expr)
1956                 {
1957                         this.expr = expr;
1958                         this.loc = expr.Location;
1959                 }
1960
1961                 public override Expression CreateExpressionTree (ResolveContext ec)
1962                 {
1963                         return expr.CreateExpressionTree (ec);
1964                 }
1965
1966                 public Expression Child {
1967                         get { return expr; }
1968                 }
1969
1970                 protected override Expression DoResolve (ResolveContext ec)
1971                 {
1972                         expr = expr.Resolve (ec);
1973                         if (expr != null) {
1974                                 type = expr.Type;
1975                                 eclass = expr.eclass;
1976                         }
1977
1978                         return this;
1979                 }
1980
1981                 public override void Emit (EmitContext ec)
1982                 {
1983                         expr.Emit (ec);
1984                 }
1985
1986                 public override bool IsNull {
1987                         get { return expr.IsNull; }
1988                 }
1989         }
1990
1991         //
1992         // Base of expressions used only to narrow resolve flow
1993         //
1994         public abstract class ShimExpression : Expression
1995         {
1996                 protected Expression expr;
1997
1998                 protected ShimExpression (Expression expr)
1999                 {
2000                         this.expr = expr;
2001                 }
2002
2003                 protected override void CloneTo (CloneContext clonectx, Expression t)
2004                 {
2005                         if (expr == null)
2006                                 return;
2007
2008                         ShimExpression target = (ShimExpression) t;
2009                         target.expr = expr.Clone (clonectx);
2010                 }
2011
2012                 public override Expression CreateExpressionTree (ResolveContext ec)
2013                 {
2014                         throw new NotSupportedException ("ET");
2015                 }
2016
2017                 public override void Emit (EmitContext ec)
2018                 {
2019                         throw new InternalErrorException ("Missing Resolve call");
2020                 }
2021
2022                 public Expression Expr {
2023                         get { return expr; }
2024                 }
2025         }
2026
2027         //
2028         // Unresolved type name expressions
2029         //
2030         public abstract class ATypeNameExpression : FullNamedExpression
2031         {
2032                 string name;
2033                 protected TypeArguments targs;
2034
2035                 protected ATypeNameExpression (string name, Location l)
2036                 {
2037                         this.name = name;
2038                         loc = l;
2039                 }
2040
2041                 protected ATypeNameExpression (string name, TypeArguments targs, Location l)
2042                 {
2043                         this.name = name;
2044                         this.targs = targs;
2045                         loc = l;
2046                 }
2047
2048                 protected ATypeNameExpression (string name, int arity, Location l)
2049                         : this (name, new UnboundTypeArguments (arity), l)
2050                 {
2051                 }
2052
2053                 #region Properties
2054
2055                 protected int Arity {
2056                         get {
2057                                 return targs == null ? 0 : targs.Count;
2058                         }
2059                 }
2060
2061                 public bool HasTypeArguments {
2062                         get {
2063                                 return targs != null && !targs.IsEmpty;
2064                         }
2065                 }
2066
2067                 public string Name {
2068                         get {
2069                                 return name;
2070                         }
2071                         set {
2072                                 name = value;
2073                         }
2074                 }
2075
2076                 public TypeArguments TypeArguments {
2077                         get {
2078                                 return targs;
2079                         }
2080                 }
2081
2082                 #endregion
2083
2084                 public override bool Equals (object obj)
2085                 {
2086                         ATypeNameExpression atne = obj as ATypeNameExpression;
2087                         return atne != null && atne.Name == Name &&
2088                                 (targs == null || targs.Equals (atne.targs));
2089                 }
2090
2091                 public override int GetHashCode ()
2092                 {
2093                         return Name.GetHashCode ();
2094                 }
2095
2096                 // TODO: Move it to MemberCore
2097                 public static string GetMemberType (MemberCore mc)
2098                 {
2099                         if (mc is Property)
2100                                 return "property";
2101                         if (mc is Indexer)
2102                                 return "indexer";
2103                         if (mc is FieldBase)
2104                                 return "field";
2105                         if (mc is MethodCore)
2106                                 return "method";
2107                         if (mc is EnumMember)
2108                                 return "enum";
2109                         if (mc is Event)
2110                                 return "event";
2111
2112                         return "type";
2113                 }
2114
2115                 public override string GetSignatureForError ()
2116                 {
2117                         if (targs != null) {
2118                                 return Name + "<" + targs.GetSignatureForError () + ">";
2119                         }
2120
2121                         return Name;
2122                 }
2123
2124                 public abstract Expression LookupNameExpression (ResolveContext rc, MemberLookupRestrictions restriction);
2125         }
2126
2127         /// <summary>
2128         ///   SimpleName expressions are formed of a single word and only happen at the beginning
2129         ///   of a dotted-name.
2130         /// </summary>
2131         public class SimpleName : ATypeNameExpression
2132         {
2133                 public SimpleName (string name, Location l)
2134                         : base (name, l)
2135                 {
2136                 }
2137
2138                 public SimpleName (string name, TypeArguments args, Location l)
2139                         : base (name, args, l)
2140                 {
2141                 }
2142
2143                 public SimpleName (string name, int arity, Location l)
2144                         : base (name, arity, l)
2145                 {
2146                 }
2147
2148                 public SimpleName GetMethodGroup ()
2149                 {
2150                         return new SimpleName (Name, targs, loc);
2151                 }
2152
2153                 protected virtual void Error_TypeOrNamespaceNotFound (IMemberContext ec)
2154                 {
2155                         if (ec.CurrentType != null) {
2156                                 if (ec.CurrentMemberDefinition != null) {
2157                                         MemberCore mc = ec.CurrentMemberDefinition.Parent.GetDefinition (Name);
2158                                         if (mc != null) {
2159                                                 Error_UnexpectedKind (ec.Compiler.Report, mc, "type", GetMemberType (mc), loc);
2160                                                 return;
2161                                         }
2162                                 }
2163
2164                                 /*
2165                                                                 // TODO MemberCache: Implement
2166
2167                                                                 string ns = ec.CurrentType.Namespace;
2168                                                                 string fullname = (ns.Length > 0) ? ns + "." + Name : Name;
2169                                                                 foreach (Assembly a in GlobalRootNamespace.Instance.Assemblies) {
2170                                                                         var type = a.GetType (fullname);
2171                                                                         if (type != null) {
2172                                                                                 ec.Compiler.Report.SymbolRelatedToPreviousError (type);
2173                                                                                 Expression.ErrorIsInaccesible (loc, TypeManager.CSharpName (type), ec.Compiler.Report);
2174                                                                                 return;
2175                                                                         }
2176                                                                 }
2177
2178                                                                 if (ec.CurrentTypeDefinition != null) {
2179                                                                         TypeSpec t = ec.CurrentTypeDefinition.LookupAnyGeneric (Name);
2180                                                                         if (t != null) {
2181                                                                                 Namespace.Error_InvalidNumberOfTypeArguments (ec.Compiler.Report, t, loc);
2182                                                                                 return;
2183                                                                         }
2184                                                                 }
2185                                 */
2186                         }
2187
2188                         FullNamedExpression retval = ec.LookupNamespaceOrType (Name, -System.Math.Max (1, Arity), loc, true);
2189                         if (retval != null) {
2190                                 Error_TypeArgumentsCannotBeUsed (ec.Compiler.Report, loc, retval.Type, Arity);
2191 /*
2192                                 var te = retval as TypeExpr;
2193                                 if (HasTypeArguments && te != null && !te.Type.IsGeneric)
2194                                         retval.Error_TypeArgumentsCannotBeUsed (ec.Compiler.Report, loc);
2195                                 else
2196                                         Namespace.Error_InvalidNumberOfTypeArguments (ec.Compiler.Report, retval.Type, loc);
2197 */
2198                                 return;
2199                         }
2200
2201                         NamespaceEntry.Error_NamespaceNotFound (loc, Name, ec.Compiler.Report);
2202                 }
2203
2204                 protected override Expression DoResolve (ResolveContext ec)
2205                 {
2206                         return SimpleNameResolve (ec, null, false);
2207                 }
2208
2209                 public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
2210                 {
2211                         return SimpleNameResolve (ec, right_side, false);
2212                 }
2213
2214                 public override FullNamedExpression ResolveAsTypeStep (IMemberContext ec, bool silent)
2215                 {
2216                         int errors = ec.Compiler.Report.Errors;
2217                         FullNamedExpression fne = ec.LookupNamespaceOrType (Name, Arity, loc, /*ignore_cs0104=*/ false);
2218
2219                         if (fne != null) {
2220                                 if (fne.Type != null && Arity > 0) {
2221                                         if (HasTypeArguments) {
2222                                                 GenericTypeExpr ct = new GenericTypeExpr (fne.Type, targs, loc);
2223                                                 return ct.ResolveAsTypeStep (ec, false);
2224                                         }
2225
2226                                         return new GenericOpenTypeExpr (fne.Type, loc);
2227                                 }
2228
2229                                 //
2230                                 // dynamic namespace is ignored when dynamic is allowed (does not apply to types)
2231                                 //
2232                                 if (!(fne is Namespace))
2233                                         return fne;
2234                         }
2235
2236                         if (Arity == 0 && Name == "dynamic" && RootContext.Version > LanguageVersion.V_3) {
2237                                 if (!ec.Compiler.PredefinedAttributes.Dynamic.IsDefined) {
2238                                         ec.Compiler.Report.Error (1980, Location,
2239                                                 "Dynamic keyword requires `{0}' to be defined. Are you missing System.Core.dll assembly reference?",
2240                                                 ec.Compiler.PredefinedAttributes.Dynamic.GetSignatureForError ());
2241                                 }
2242
2243                                 return new DynamicTypeExpr (loc);
2244                         }
2245
2246                         if (fne != null)
2247                                 return fne;
2248
2249                         if (silent || errors != ec.Compiler.Report.Errors)
2250                                 return null;
2251
2252                         Error_TypeOrNamespaceNotFound (ec);
2253                         return null;
2254                 }
2255
2256                 public override Expression LookupNameExpression (ResolveContext rc, MemberLookupRestrictions restrictions)
2257                 {
2258                         int lookup_arity = Arity;
2259                         bool errorMode = false;
2260                         Expression e;
2261                         Block current_block = rc.CurrentBlock;
2262                         INamedBlockVariable variable = null;
2263                         bool variable_found = false;
2264
2265                         while (true) {
2266                                 //
2267                                 // Stage 1: binding to local variables or parameters
2268                                 //
2269                                 // LAMESPEC: It should take invocableOnly into account but that would break csc compatibility
2270                                 //
2271                                 if (current_block != null && lookup_arity == 0) {
2272                                         if (current_block.ParametersBlock.TopBlock.GetLocalName (Name, current_block.Original, ref variable)) {
2273                                                 if (!variable.IsDeclared) {
2274                                                         // We found local name in accessible block but it's not
2275                                                         // initialized yet, maybe the user wanted to bind to something else
2276                                                         errorMode = true;
2277                                                         variable_found = true;
2278                                                 } else {
2279                                                         e = variable.CreateReferenceExpression (rc, loc);
2280                                                         if (e != null) {
2281                                                                 if (Arity > 0)
2282                                                                         Error_TypeArgumentsCannotBeUsed (rc.Report, "variable", Name, loc);
2283
2284                                                                 return e;
2285                                                         }
2286                                                 }
2287                                         }
2288                                 }
2289
2290                                 //
2291                                 // Stage 2: Lookup members if we are inside a type up to top level type for nested types
2292                                 //
2293                                 TypeSpec member_type = rc.CurrentType;
2294                                 TypeSpec current_type = member_type;
2295                                 for (; member_type != null; member_type = member_type.DeclaringType) {
2296                                         var me = MemberLookup (errorMode ? null : rc, current_type, member_type, Name, lookup_arity, restrictions, loc) as MemberExpr;
2297                                         if (me == null)
2298                                                 continue;
2299
2300                                         if (errorMode) {
2301                                                 if (variable != null) {
2302                                                         if (me is FieldExpr || me is ConstantExpr || me is EventExpr || me is PropertyExpr) {
2303                                                                 rc.Report.Error (844, loc,
2304                                                                         "A local variable `{0}' cannot be used before it is declared. Consider renaming the local variable when it hides the member `{1}'",
2305                                                                         Name, me.GetSignatureForError ());
2306                                                         } else {
2307                                                                 break;
2308                                                         }
2309                                                 } else if (me is MethodGroupExpr) {
2310                                                         // Leave it to overload resolution to report correct error
2311                                                 } else {
2312                                                         // TODO: rc.Report.SymbolRelatedToPreviousError ()
2313                                                         ErrorIsInaccesible (rc, me.GetSignatureForError (), loc);
2314                                                 }
2315                                         } else {
2316                                                 if (variable != null && (restrictions & MemberLookupRestrictions.InvocableOnly) == 0) {
2317                                                         rc.Report.SymbolRelatedToPreviousError (variable.Location, Name);
2318                                                         rc.Report.Error (135, loc, "`{0}' conflicts with a declaration in a child block", Name);
2319                                                 }
2320
2321                                                 //
2322                                                 // MemberLookup does not check accessors availability, this is actually needed for properties only
2323                                                 //
2324                                                 var pe = me as PropertyExpr;
2325                                                 if (pe != null) {
2326
2327                                                         // Break as there is no other overload available anyway
2328                                                         if ((restrictions & MemberLookupRestrictions.ReadAccess) != 0) {
2329                                                                 if (!pe.PropertyInfo.HasGet || !pe.PropertyInfo.Get.IsAccessible (current_type))
2330                                                                         break;
2331
2332                                                                 pe.Getter = pe.PropertyInfo.Get;
2333                                                         } else {
2334                                                                 if (!pe.PropertyInfo.HasSet || !pe.PropertyInfo.Set.IsAccessible (current_type))
2335                                                                         break;
2336
2337                                                                 pe.Setter = pe.PropertyInfo.Set;
2338                                                         }
2339                                                 }
2340                                         }
2341
2342                                         // TODO: It's used by EventExpr -> FieldExpr transformation only
2343                                         // TODO: Should go to MemberAccess
2344                                         me = me.ResolveMemberAccess (rc, null, null);
2345
2346                                         if (Arity > 0) {
2347                                                 targs.Resolve (rc);
2348                                                 me.SetTypeArguments (rc, targs);
2349                                         }
2350
2351                                         return me;
2352                                 }
2353
2354                                 //
2355                                 // Stage 3: Lookup nested types, namespaces and type parameters in the context
2356                                 //
2357                                 if ((restrictions & MemberLookupRestrictions.InvocableOnly) == 0 && !variable_found) {
2358                                         e = ResolveAsTypeStep (rc, lookup_arity == 0 || !errorMode);
2359                                         if (e != null)
2360                                                 return e;
2361                                 }
2362
2363                                 if (errorMode) {
2364                                         if (variable_found) {
2365                                                 rc.Report.Error (841, loc, "A local variable `{0}' cannot be used before it is declared", Name);
2366                                         } else {
2367                                                 rc.Report.Error (103, loc, "The name `{0}' does not exist in the current context", Name);
2368                                         }
2369
2370                                         return null;
2371                                 }
2372
2373                                 if (RootContext.EvalMode) {
2374                                         var fi = Evaluator.LookupField (Name);
2375                                         if (fi != null)
2376                                                 return new FieldExpr (fi.Item1, loc);
2377                                 }
2378
2379                                 lookup_arity = 0;
2380                                 restrictions &= ~MemberLookupRestrictions.InvocableOnly;
2381                                 errorMode = true;
2382                         }
2383                 }
2384
2385                 Expression SimpleNameResolve (ResolveContext ec, Expression right_side, bool intermediate)
2386                 {
2387                         Expression e = LookupNameExpression (ec, right_side == null ? MemberLookupRestrictions.ReadAccess : MemberLookupRestrictions.None);
2388
2389                         if (e == null)
2390                                 return null;
2391
2392                         if (right_side != null) {
2393                                 if (e is TypeExpr) {
2394                                     e.Error_UnexpectedKind (ec, ResolveFlags.VariableOrValue, loc);
2395                                     return null;
2396                                 }
2397
2398                                 e = e.ResolveLValue (ec, right_side);
2399                         } else {
2400                                 e = e.Resolve (ec);
2401                         }
2402
2403                         //if (ec.CurrentBlock == null || ec.CurrentBlock.CheckInvariantMeaningInBlock (Name, e, Location))
2404                         return e;
2405                 }
2406         }
2407
2408         /// <summary>
2409         ///   Represents a namespace or a type.  The name of the class was inspired by
2410         ///   section 10.8.1 (Fully Qualified Names).
2411         /// </summary>
2412         public abstract class FullNamedExpression : Expression
2413         {
2414                 protected override void CloneTo (CloneContext clonectx, Expression target)
2415                 {
2416                         // Do nothing, most unresolved type expressions cannot be
2417                         // resolved to different type
2418                 }
2419
2420                 public override Expression CreateExpressionTree (ResolveContext ec)
2421                 {
2422                         throw new NotSupportedException ("ET");
2423                 }
2424
2425                 public override FullNamedExpression ResolveAsTypeStep (IMemberContext ec, bool silent)
2426                 {
2427                         return this;
2428                 }
2429
2430                 public override void Emit (EmitContext ec)
2431                 {
2432                         throw new InternalErrorException ("FullNamedExpression `{0}' found in resolved tree",
2433                                 GetSignatureForError ());
2434                 }
2435         }
2436
2437         /// <summary>
2438         ///   Expression that evaluates to a type
2439         /// </summary>
2440         public abstract class TypeExpr : FullNamedExpression {
2441                 public override FullNamedExpression ResolveAsTypeStep (IMemberContext ec, bool silent)
2442                 {
2443                         TypeExpr t = DoResolveAsTypeStep (ec);
2444                         if (t == null)
2445                                 return null;
2446
2447                         eclass = ExprClass.Type;
2448                         return t;
2449                 }
2450
2451                 protected override Expression DoResolve (ResolveContext ec)
2452                 {
2453                         return ResolveAsTypeTerminal (ec, false);
2454                 }
2455
2456                 public virtual bool CheckAccessLevel (IMemberContext mc)
2457                 {
2458                         DeclSpace c = mc.CurrentMemberDefinition as DeclSpace;
2459                         if (c == null)
2460                                 c = mc.CurrentMemberDefinition.Parent;
2461
2462                         return c.CheckAccessLevel (Type);
2463                 }
2464
2465                 protected abstract TypeExpr DoResolveAsTypeStep (IMemberContext ec);
2466
2467                 public override bool Equals (object obj)
2468                 {
2469                         TypeExpr tobj = obj as TypeExpr;
2470                         if (tobj == null)
2471                                 return false;
2472
2473                         return Type == tobj.Type;
2474                 }
2475
2476                 public override int GetHashCode ()
2477                 {
2478                         return Type.GetHashCode ();
2479                 }
2480         }
2481
2482         /// <summary>
2483         ///   Fully resolved Expression that already evaluated to a type
2484         /// </summary>
2485         public class TypeExpression : TypeExpr {
2486                 public TypeExpression (TypeSpec t, Location l)
2487                 {
2488                         Type = t;
2489                         eclass = ExprClass.Type;
2490                         loc = l;
2491                 }
2492
2493                 protected override TypeExpr DoResolveAsTypeStep (IMemberContext ec)
2494                 {
2495                         return this;
2496                 }
2497
2498                 public override TypeExpr ResolveAsTypeTerminal (IMemberContext ec, bool silent)
2499                 {
2500                         return this;
2501                 }
2502         }
2503
2504         /// <summary>
2505         ///   This class denotes an expression which evaluates to a member
2506         ///   of a struct or a class.
2507         /// </summary>
2508         public abstract class MemberExpr : Expression
2509         {
2510                 //
2511                 // An instance expression associated with this member, if it's a
2512                 // non-static member
2513                 //
2514                 public Expression InstanceExpression;
2515
2516                 /// <summary>
2517                 ///   The name of this member.
2518                 /// </summary>
2519                 public abstract string Name {
2520                         get;
2521                 }
2522
2523                 //
2524                 // When base.member is used
2525                 //
2526                 public bool IsBase {
2527                         get { return InstanceExpression is BaseThis; }
2528                 }
2529
2530                 /// <summary>
2531                 ///   Whether this is an instance member.
2532                 /// </summary>
2533                 public abstract bool IsInstance {
2534                         get;
2535                 }
2536
2537                 /// <summary>
2538                 ///   Whether this is a static member.
2539                 /// </summary>
2540                 public abstract bool IsStatic {
2541                         get;
2542                 }
2543
2544                 // TODO: Not needed
2545                 protected abstract TypeSpec DeclaringType {
2546                         get;
2547                 }
2548
2549                 //
2550                 // Converts best base candidate for virtual method starting from QueriedBaseType
2551                 //
2552                 protected MethodSpec CandidateToBaseOverride (ResolveContext rc, MethodSpec method)
2553                 {
2554                         //
2555                         // Only when base.member is used and method is virtual
2556                         //
2557                         if (!IsBase)
2558                                 return method;
2559
2560                         //
2561                         // Overload resulution works on virtual or non-virtual members only (no overrides). That
2562                         // means for base.member access we have to find the closest match after we found best candidate
2563                         //
2564                         if ((method.Modifiers & (Modifiers.ABSTRACT | Modifiers.VIRTUAL | Modifiers.STATIC)) != Modifiers.STATIC) {
2565                                 //
2566                                 // The method could already be what we are looking for
2567                                 //
2568                                 TypeSpec[] targs = null;
2569                                 if (method.DeclaringType != InstanceExpression.Type) {
2570                                         var base_override = MemberCache.FindMember (InstanceExpression.Type, new MemberFilter (method), BindingRestriction.InstanceOnly) as MethodSpec;
2571                                         if (base_override != null && base_override.DeclaringType != method.DeclaringType) {
2572                                                 if (base_override.IsGeneric)
2573                                                         targs = method.TypeArguments;
2574
2575                                                 method = base_override;
2576                                         }
2577                                 }
2578
2579                                 // TODO: For now we do it for any hoisted call even if it's needed for
2580                                 // hoisted stories only but that requires a new expression wrapper
2581                                 if (rc.CurrentAnonymousMethod != null) {
2582                                         if (targs == null && method.IsGeneric) {
2583                                                 targs = method.TypeArguments;
2584                                                 method = method.GetGenericMethodDefinition ();
2585                                         }
2586
2587                                         if (method.Parameters.HasArglist)
2588                                                 throw new NotImplementedException ("__arglist base call proxy");
2589
2590                                         method = rc.CurrentMemberDefinition.Parent.PartialContainer.CreateHoistedBaseCallProxy (rc, method);
2591
2592                                         // Ideally this should apply to any proxy rewrite but in the case of unary mutators on
2593                                         // get/set member expressions second call would fail to proxy because left expression
2594                                         // would be of 'this' and not 'base'
2595                                         if (rc.CurrentType.IsStruct)
2596                                                 InstanceExpression = rc.GetThis (loc);
2597                                 }
2598
2599                                 if (targs != null)
2600                                         method = method.MakeGenericMethod (targs);
2601                         }
2602
2603                         //
2604                         // Only base will allow this invocation to happen.
2605                         //
2606                         if (method.IsAbstract) {
2607                                 Error_CannotCallAbstractBase (rc, method.GetSignatureForError ());
2608                         }
2609
2610                         return method;
2611                 }
2612
2613                 protected void CheckProtectedMemberAccess<T> (ResolveContext rc, T member) where T : MemberSpec
2614                 {
2615                         if (InstanceExpression == null)
2616                                 return;
2617
2618                         if ((member.Modifiers & Modifiers.AccessibilityMask) == Modifiers.PROTECTED && !(InstanceExpression is This)) {
2619                                 var ct = rc.CurrentType;
2620                                 var expr_type = InstanceExpression.Type;
2621                                 if (ct != expr_type) {
2622                                         expr_type = expr_type.GetDefinition ();
2623                                         if (ct != expr_type && !IsSameOrBaseQualifier (ct, expr_type)) {
2624                                                 rc.Report.SymbolRelatedToPreviousError (member);
2625                                                 rc.Report.Error (1540, loc,
2626                                                         "Cannot access protected member `{0}' via a qualifier of type `{1}'. The qualifier must be of type `{2}' or derived from it",
2627                                                         member.GetSignatureForError (), expr_type.GetSignatureForError (), ct.GetSignatureForError ());
2628                                         }
2629                                 }
2630                         }
2631                 }
2632
2633                 static bool IsSameOrBaseQualifier (TypeSpec type, TypeSpec qtype)
2634                 {
2635                         do {
2636                                 type = type.GetDefinition ();
2637
2638                                 if (type == qtype || TypeManager.IsFamilyAccessible (qtype, type))
2639                                         return true;
2640
2641                                 type = type.DeclaringType;
2642                         } while (type != null);
2643
2644                         return false;
2645                 }
2646
2647                 protected void DoBestMemberChecks<T> (ResolveContext rc, T member) where T : MemberSpec, IInterfaceMemberSpec
2648                 {
2649                         if (InstanceExpression != null) {
2650                                 InstanceExpression = InstanceExpression.Resolve (rc);
2651                                 CheckProtectedMemberAccess (rc, member);
2652                         }
2653
2654                         if (member.MemberType.IsPointer && !rc.IsUnsafe) {
2655                                 UnsafeError (rc, loc);
2656                         }
2657
2658                         if (!rc.IsObsolete) {
2659                                 ObsoleteAttribute oa = member.GetAttributeObsolete ();
2660                                 if (oa != null)
2661                                         AttributeTester.Report_ObsoleteMessage (oa, member.GetSignatureForError (), loc, rc.Report);
2662                         }
2663
2664                         if (!(member is FieldSpec))
2665                                 member.MemberDefinition.SetIsUsed ();
2666                 }
2667
2668                 protected virtual void Error_CannotCallAbstractBase (ResolveContext rc, string name)
2669                 {
2670                         rc.Report.Error (205, loc, "Cannot call an abstract base member `{0}'", name);
2671                 }
2672
2673                 //
2674                 // Implements identicial simple name and type-name
2675                 //
2676                 public Expression ProbeIdenticalTypeName (ResolveContext rc, Expression left, SimpleName name)
2677                 {
2678                         var t = left.Type;
2679                         if (t.Kind == MemberKind.InternalCompilerType || t is ElementTypeSpec || t.Arity > 0)
2680                                 return left;
2681
2682                         // 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
2683                         // a constant, field, property, local variable, or parameter with the same type as the meaning of E as a type-name
2684
2685                         if (left is MemberExpr || left is VariableReference) {
2686                                 rc.Report.DisableReporting ();
2687                                 Expression identical_type = rc.LookupNamespaceOrType (name.Name, 0, loc, true) as TypeExpr;
2688                                 rc.Report.EnableReporting ();
2689                                 if (identical_type != null && identical_type.Type == left.Type)
2690                                         return identical_type;
2691                         }
2692
2693                         return left;
2694                 }
2695
2696                 public bool ResolveInstanceExpression (ResolveContext rc)
2697                 {
2698                         if (IsStatic) {
2699                                 if (InstanceExpression != null) {
2700                                         if (InstanceExpression is TypeExpr) {
2701                                                 ObsoleteAttribute oa = InstanceExpression.Type.GetAttributeObsolete ();
2702                                                 if (oa != null && !rc.IsObsolete) {
2703                                                         AttributeTester.Report_ObsoleteMessage (oa, InstanceExpression.GetSignatureForError (), loc, rc.Report);
2704                                                 }
2705                                         } else {
2706                                                 var runtime_expr = InstanceExpression as RuntimeValueExpression;
2707                                                 if (runtime_expr == null || !runtime_expr.IsSuggestionOnly) {
2708                                                         rc.Report.Error (176, loc,
2709                                                                 "Static member `{0}' cannot be accessed with an instance reference, qualify it with a type name instead",
2710                                                                 GetSignatureForError ());
2711                                                 }
2712                                         }
2713
2714                                         InstanceExpression = null;
2715                                 }
2716
2717                                 return false;
2718                         }
2719
2720                         if (InstanceExpression == null || InstanceExpression is TypeExpr) {
2721                                 if (InstanceExpression != null || !This.IsThisAvailable (rc, true)) {
2722                                         if (rc.HasSet (ResolveContext.Options.FieldInitializerScope))
2723                                                 rc.Report.Error (236, loc,
2724                                                         "A field initializer cannot reference the nonstatic field, method, or property `{0}'",
2725                                                         GetSignatureForError ());
2726                                         else
2727                                                 rc.Report.Error (120, loc,
2728                                                         "An object reference is required to access non-static member `{0}'",
2729                                                         GetSignatureForError ());
2730
2731                                         return false;
2732                                 }
2733
2734                                 if (!TypeManager.IsFamilyAccessible (rc.CurrentType, DeclaringType)) {
2735                                         rc.Report.Error (38, loc,
2736                                                 "Cannot access a nonstatic member of outer type `{0}' via nested type `{1}'",
2737                                                 DeclaringType.GetSignatureForError (), rc.CurrentType.GetSignatureForError ());
2738                                 }
2739
2740                                 InstanceExpression = rc.GetThis (loc);
2741                                 return false;
2742                         }
2743
2744                         var me = InstanceExpression as MemberExpr;
2745                         if (me != null) {
2746                                 me.ResolveInstanceExpression (rc);
2747
2748                                 var fe = me as FieldExpr;
2749                                 if (fe != null && fe.IsMarshalByRefAccess ()) {
2750                                         rc.Report.SymbolRelatedToPreviousError (me.DeclaringType);
2751                                         rc.Report.Warning (1690, 1, loc,
2752                                                 "Cannot call methods, properties, or indexers on `{0}' because it is a value type member of a marshal-by-reference class",
2753                                                 me.GetSignatureForError ());
2754                                 }
2755                         }
2756
2757                         return true;
2758                 }
2759
2760                 public virtual MemberExpr ResolveMemberAccess (ResolveContext ec, Expression left, SimpleName original)
2761                 {
2762                         if (left != null && left.IsNull && TypeManager.IsReferenceType (left.Type)) {
2763                                 ec.Report.Warning (1720, 1, left.Location,
2764                                         "Expression will always cause a `{0}'", "System.NullReferenceException");
2765                         }
2766
2767                         InstanceExpression = left;
2768                         return this;
2769                 }
2770
2771                 protected void EmitInstance (EmitContext ec, bool prepare_for_load)
2772                 {
2773                         TypeSpec instance_type = InstanceExpression.Type;
2774                         if (TypeManager.IsValueType (instance_type)) {
2775                                 if (InstanceExpression is IMemoryLocation) {
2776                                         ((IMemoryLocation) InstanceExpression).AddressOf (ec, AddressOp.LoadStore);
2777                                 } else {
2778                                         LocalTemporary t = new LocalTemporary (instance_type);
2779                                         InstanceExpression.Emit (ec);
2780                                         t.Store (ec);
2781                                         t.AddressOf (ec, AddressOp.Store);
2782                                 }
2783                         } else {
2784                                 InstanceExpression.Emit (ec);
2785
2786                                 // Only to make verifier happy
2787                                 if (instance_type.IsGenericParameter && !(InstanceExpression is This) && TypeManager.IsReferenceType (instance_type))
2788                                         ec.Emit (OpCodes.Box, instance_type);
2789                         }
2790
2791                         if (prepare_for_load)
2792                                 ec.Emit (OpCodes.Dup);
2793                 }
2794
2795                 public abstract void SetTypeArguments (ResolveContext ec, TypeArguments ta);
2796         }
2797
2798         //
2799         // Represents a group of extension method candidates for whole namespace
2800         //
2801         class ExtensionMethodGroupExpr : MethodGroupExpr, OverloadResolver.IErrorHandler
2802         {
2803                 NamespaceEntry namespace_entry;
2804                 public readonly Expression ExtensionExpression;
2805
2806                 public ExtensionMethodGroupExpr (IList<MethodSpec> list, NamespaceEntry n, Expression extensionExpr, Location l)
2807                         : base (list.Cast<MemberSpec>().ToList (), extensionExpr.Type, l)
2808                 {
2809                         this.namespace_entry = n;
2810                         this.ExtensionExpression = extensionExpr;
2811                 }
2812
2813                 public override bool IsStatic {
2814                         get { return true; }
2815                 }
2816
2817                 public override IList<MemberSpec> GetBaseMembers (TypeSpec baseType)
2818                 {
2819                         if (namespace_entry == null)
2820                                 return null;
2821
2822                         //
2823                         // For extension methodgroup we are not looking for base members but parent
2824                         // namespace extension methods
2825                         //
2826                         int arity = type_arguments == null ? 0 : type_arguments.Count;
2827                         var found = namespace_entry.LookupExtensionMethod (DeclaringType, Name, arity, ref namespace_entry);
2828                         if (found == null)
2829                                 return null;
2830
2831                         return found.Cast<MemberSpec> ().ToList ();
2832                 }
2833
2834                 public override MethodGroupExpr LookupExtensionMethod (ResolveContext rc)
2835                 {
2836                         // We are already here
2837                         return null;
2838                 }
2839
2840                 public override MethodGroupExpr OverloadResolve (ResolveContext ec, ref Arguments arguments, OverloadResolver.IErrorHandler ehandler, OverloadResolver.Restrictions restr)
2841                 {
2842                         if (arguments == null)
2843                                 arguments = new Arguments (1);
2844
2845                         arguments.Insert (0, new Argument (ExtensionExpression, Argument.AType.ExtensionType));
2846                         var res = base.OverloadResolve (ec, ref arguments, ehandler ?? this, restr);
2847
2848                         // Store resolved argument and restore original arguments
2849                         if (res == null) {
2850                                 // Clean-up modified arguments for error reporting
2851                                 arguments.RemoveAt (0);
2852                                 return null;
2853                         }
2854
2855                         var me = ExtensionExpression as MemberExpr;
2856                         if (me != null)
2857                                 me.ResolveInstanceExpression (ec);
2858
2859                         InstanceExpression = null;
2860                         return this;
2861                 }
2862
2863                 #region IErrorHandler Members
2864
2865                 bool OverloadResolver.IErrorHandler.AmbiguousCandidates (ResolveContext rc, MemberSpec best, MemberSpec ambiguous)
2866                 {
2867                         return false;
2868                 }
2869
2870                 bool OverloadResolver.IErrorHandler.ArgumentMismatch (ResolveContext rc, MemberSpec best, Argument arg, int index)
2871                 {
2872                         rc.Report.SymbolRelatedToPreviousError (best);
2873                         rc.Report.Error (1928, loc,
2874                                 "Type `{0}' does not contain a member `{1}' and the best extension method overload `{2}' has some invalid arguments",
2875                                 queried_type.GetSignatureForError (), Name, best.GetSignatureForError ());
2876
2877                         if (index == 0) {
2878                                 rc.Report.Error (1929, loc,
2879                                         "Extension method instance type `{0}' cannot be converted to `{1}'",
2880                                         arg.Type.GetSignatureForError (), ((MethodSpec)best).Parameters.ExtensionMethodType.GetSignatureForError ());
2881                         }
2882
2883                         return true;
2884                 }
2885
2886                 bool OverloadResolver.IErrorHandler.NoArgumentMatch (ResolveContext rc, MemberSpec best)
2887                 {
2888                         return false;
2889                 }
2890
2891                 bool OverloadResolver.IErrorHandler.TypeInferenceFailed (ResolveContext rc, MemberSpec best)
2892                 {
2893                         return false;
2894                 }
2895
2896                 #endregion
2897         }
2898
2899         /// <summary>
2900         ///   MethodGroupExpr represents a group of method candidates which
2901         ///   can be resolved to the best method overload
2902         /// </summary>
2903         public class MethodGroupExpr : MemberExpr, OverloadResolver.IBaseMembersProvider
2904         {
2905                 protected IList<MemberSpec> Methods;
2906                 MethodSpec best_candidate;
2907                 protected TypeArguments type_arguments;
2908
2909                 SimpleName simple_name;
2910                 protected TypeSpec queried_type;
2911
2912                 public MethodGroupExpr (IList<MemberSpec> mi, TypeSpec type, Location loc)
2913                 {
2914                         Methods = mi;
2915                         this.loc = loc;
2916                         this.type = InternalType.MethodGroup;
2917
2918                         eclass = ExprClass.MethodGroup;
2919                         queried_type = type;
2920                 }
2921
2922                 public MethodGroupExpr (MethodSpec m, TypeSpec type, Location loc)
2923                         : this (new MemberSpec[] { m }, type, loc)
2924                 {
2925                 }
2926
2927                 #region Properties
2928
2929                 public MethodSpec BestCandidate {
2930                         get {
2931                                 return best_candidate;
2932                         }
2933                 }
2934
2935                 protected override TypeSpec DeclaringType {
2936                         get {
2937                                 return queried_type;
2938                         }
2939                 }
2940
2941                 public override bool IsInstance {
2942                         get {
2943                                 if (best_candidate != null)
2944                                         return !best_candidate.IsStatic;
2945
2946                                 return false;
2947                         }
2948                 }
2949
2950                 public override bool IsStatic {
2951                         get {
2952                                 if (best_candidate != null)
2953                                         return best_candidate.IsStatic;
2954
2955                                 return false;
2956                         }
2957                 }
2958
2959                 public override string Name {
2960                         get {
2961                                 if (best_candidate != null)
2962                                         return best_candidate.Name;
2963
2964                                 // TODO: throw ?
2965                                 return Methods.First ().Name;
2966                         }
2967                 }
2968
2969                 #endregion
2970
2971                 //
2972                 // When best candidate is already know this factory can be used
2973                 // to avoid expensive overload resolution to be called
2974                 //
2975                 // NOTE: InstanceExpression has to be set manually
2976                 //
2977                 public static MethodGroupExpr CreatePredefined (MethodSpec best, TypeSpec queriedType, Location loc)
2978                 {
2979                         return new MethodGroupExpr (best, queriedType, loc) {
2980                                 best_candidate = best
2981                         };
2982                 }
2983
2984                 public override string GetSignatureForError ()
2985                 {
2986                         if (best_candidate != null)
2987                                 return best_candidate.GetSignatureForError ();
2988
2989                         return Methods.First ().GetSignatureForError ();
2990                 }
2991
2992                 public override Expression CreateExpressionTree (ResolveContext ec)
2993                 {
2994                         if (best_candidate == null) {
2995                                 ec.Report.Error (1953, loc, "An expression tree cannot contain an expression with method group");
2996                                 return null;
2997                         }
2998
2999                         if (best_candidate.IsConditionallyExcluded (loc))
3000                                 ec.Report.Error (765, loc,
3001                                         "Partial methods with only a defining declaration or removed conditional methods cannot be used in an expression tree");
3002
3003                         return new TypeOfMethod (best_candidate, loc);
3004                 }
3005
3006                 protected override Expression DoResolve (ResolveContext ec)
3007                 {
3008                         this.eclass = ExprClass.MethodGroup;
3009
3010                         if (InstanceExpression != null) {
3011                                 InstanceExpression = InstanceExpression.Resolve (ec);
3012                                 if (InstanceExpression == null)
3013                                         return null;
3014                         }
3015
3016                         return this;
3017                 }
3018
3019                 public override void Emit (EmitContext ec)
3020                 {
3021                         throw new NotSupportedException ();
3022                 }
3023
3024                 public void EmitCall (EmitContext ec, Arguments arguments)
3025                 {
3026                         Invocation.EmitCall (ec, InstanceExpression, best_candidate, arguments, loc);
3027                 }
3028
3029                 public override void Error_ValueCannotBeConverted (ResolveContext ec, Location loc, TypeSpec target, bool expl)
3030                 {
3031                         ec.Report.Error (428, loc, "Cannot convert method group `{0}' to non-delegate type `{1}'. Consider using parentheses to invoke the method",
3032                                 Name, TypeManager.CSharpName (target));
3033                 }
3034
3035                 public static bool IsExtensionMethodArgument (Expression expr)
3036                 {
3037                         //
3038                         // LAMESPEC: No details about which expressions are not allowed
3039                         //
3040                         return !(expr is TypeExpr) && !(expr is BaseThis);
3041                 }
3042
3043                 /// <summary>
3044                 ///   Find the Applicable Function Members (7.4.2.1)
3045                 ///
3046                 ///   me: Method Group expression with the members to select.
3047                 ///       it might contain constructors or methods (or anything
3048                 ///       that maps to a method).
3049                 ///
3050                 ///   Arguments: ArrayList containing resolved Argument objects.
3051                 ///
3052                 ///   loc: The location if we want an error to be reported, or a Null
3053                 ///        location for "probing" purposes.
3054                 ///
3055                 ///   Returns: The MethodBase (either a ConstructorInfo or a MethodInfo)
3056                 ///            that is the best match of me on Arguments.
3057                 ///
3058                 /// </summary>
3059                 public virtual MethodGroupExpr OverloadResolve (ResolveContext ec, ref Arguments args, OverloadResolver.IErrorHandler cerrors, OverloadResolver.Restrictions restr)
3060                 {
3061                         // TODO: causes issues with probing mode, remove explicit Kind check
3062                         if (best_candidate != null && best_candidate.Kind == MemberKind.Destructor)
3063                                 return this;
3064
3065                         var r = new OverloadResolver (Methods, type_arguments, restr, loc);
3066                         if ((restr & OverloadResolver.Restrictions.NoBaseMembers) == 0) {
3067                                 r.BaseMembersProvider = this;
3068                         }
3069
3070                         if (cerrors != null)
3071                                 r.CustomErrors = cerrors;
3072
3073                         // TODO: When in probing mode do IsApplicable only and when called again do VerifyArguments for full error reporting
3074                         best_candidate = r.ResolveMember<MethodSpec> (ec, ref args);
3075                         if (best_candidate == null)
3076                                 return r.BestCandidateIsDynamic ? this : null;
3077
3078                         // Overload resolver had to create a new method group, all checks bellow have already been executed
3079                         if (r.BestCandidateNewMethodGroup != null)
3080                                 return r.BestCandidateNewMethodGroup;
3081
3082                         if (best_candidate.Kind == MemberKind.Method) {
3083                                 if (InstanceExpression != null) {
3084                                         if (best_candidate.IsExtensionMethod && args[0].Expr == InstanceExpression) {
3085                                                 InstanceExpression = null;
3086                                         } else {
3087                                                 if (best_candidate.IsStatic && simple_name != null) {
3088                                                         InstanceExpression = ProbeIdenticalTypeName (ec, InstanceExpression, simple_name);
3089                                                 }
3090
3091                                                 InstanceExpression.Resolve (ec);
3092                                         }
3093                                 }
3094
3095                                 ResolveInstanceExpression (ec);
3096                                 if (InstanceExpression != null)
3097                                         CheckProtectedMemberAccess (ec, best_candidate);
3098                         }
3099
3100                         best_candidate = CandidateToBaseOverride (ec, best_candidate);
3101                         return this;
3102                 }
3103
3104                 public override MemberExpr ResolveMemberAccess (ResolveContext ec, Expression left, SimpleName original)
3105                 {
3106                         simple_name = original;
3107                         return base.ResolveMemberAccess (ec, left, original);
3108                 }
3109
3110                 public override void SetTypeArguments (ResolveContext ec, TypeArguments ta)
3111                 {
3112                         type_arguments = ta;
3113                 }
3114
3115                 #region IBaseMembersProvider Members
3116
3117                 public virtual IList<MemberSpec> GetBaseMembers (TypeSpec baseType)
3118                 {
3119                         return baseType == null ? null : MemberCache.FindMembers (baseType, Methods [0].Name, false);
3120                 }
3121
3122                 //
3123                 // Extension methods lookup after ordinary methods candidates failed to apply
3124                 //
3125                 public virtual MethodGroupExpr LookupExtensionMethod (ResolveContext rc)
3126                 {
3127                         if (InstanceExpression == null)
3128                                 return null;
3129
3130                         InstanceExpression = InstanceExpression.Resolve (rc);
3131                         if (!IsExtensionMethodArgument (InstanceExpression))
3132                                 return null;
3133
3134                         int arity = type_arguments == null ? 0 : type_arguments.Count;
3135                         NamespaceEntry methods_scope = null;
3136                         var methods = rc.LookupExtensionMethod (InstanceExpression.Type, Methods[0].Name, arity, ref methods_scope);
3137                         if (methods == null)
3138                                 return null;
3139
3140                         var emg = new ExtensionMethodGroupExpr (methods, methods_scope, InstanceExpression, loc);
3141                         emg.SetTypeArguments (rc, type_arguments);
3142                         return emg;
3143                 }
3144
3145                 #endregion
3146         }
3147
3148         public struct OverloadResolver
3149         {
3150                 [Flags]
3151                 public enum Restrictions
3152                 {
3153                         None = 0,
3154                         DelegateInvoke = 1,
3155                         ProbingOnly     = 1 << 1,
3156                         CovariantDelegate = 1 << 2,
3157                         NoBaseMembers = 1 << 3,
3158                         BaseMembersIncluded = 1 << 4
3159                 }
3160
3161                 public interface IBaseMembersProvider
3162                 {
3163                         IList<MemberSpec> GetBaseMembers (TypeSpec baseType);
3164                         MethodGroupExpr LookupExtensionMethod (ResolveContext rc);
3165                 }
3166
3167                 public interface IErrorHandler
3168                 {
3169                         bool AmbiguousCandidates (ResolveContext rc, MemberSpec best, MemberSpec ambiguous);
3170                         bool ArgumentMismatch (ResolveContext rc, MemberSpec best, Argument a, int index);
3171                         bool NoArgumentMatch (ResolveContext rc, MemberSpec best);
3172                         bool TypeInferenceFailed (ResolveContext rc, MemberSpec best);
3173                 }
3174
3175                 sealed class NoBaseMembers : IBaseMembersProvider
3176                 {
3177                         public static readonly IBaseMembersProvider Instance = new NoBaseMembers ();
3178
3179                         public IList<MemberSpec> GetBaseMembers (TypeSpec baseType)
3180                         {
3181                                 return null;
3182                         }
3183
3184                         public MethodGroupExpr LookupExtensionMethod (ResolveContext rc)
3185                         {
3186                                 return null;
3187                         }
3188                 }
3189
3190                 struct AmbiguousCandidate
3191                 {
3192                         public readonly MemberSpec Member;
3193                         public readonly bool Expanded;
3194
3195                         public AmbiguousCandidate (MemberSpec member, bool expanded)
3196                         {
3197                                 Member = member;
3198                                 Expanded = expanded;
3199                         }
3200                 }
3201
3202                 Location loc;
3203                 IList<MemberSpec> members;
3204                 TypeArguments type_arguments;
3205                 IBaseMembersProvider base_provider;
3206                 IErrorHandler custom_errors;
3207                 Restrictions restrictions;
3208                 MethodGroupExpr best_candidate_extension_group;
3209
3210                 SessionReportPrinter lambda_conv_msgs;
3211                 ReportPrinter prev_recorder;
3212
3213                 public OverloadResolver (IList<MemberSpec> members, Restrictions restrictions, Location loc)
3214                         : this (members, null, restrictions, loc)
3215                 {
3216                 }
3217
3218                 public OverloadResolver (IList<MemberSpec> members, TypeArguments targs, Restrictions restrictions, Location loc)
3219                         : this ()
3220                 {
3221                         if (members == null || members.Count == 0)
3222                                 throw new ArgumentException ("empty members set");
3223
3224                         this.members = members;
3225                         this.loc = loc;
3226                         type_arguments = targs;
3227                         this.restrictions = restrictions;
3228                         if (IsDelegateInvoke)
3229                                 this.restrictions |= Restrictions.NoBaseMembers;
3230
3231                         base_provider = NoBaseMembers.Instance;
3232                 }
3233
3234                 #region Properties
3235
3236                 public IBaseMembersProvider BaseMembersProvider {
3237                         get {
3238                                 return base_provider;
3239                         }
3240                         set {
3241                                 base_provider = value;
3242                         }
3243                 }
3244
3245                 public bool BestCandidateIsDynamic { get; set; }
3246
3247                 //
3248                 // Best candidate was found in newly created MethodGroupExpr, used by extension methods
3249                 //
3250                 public MethodGroupExpr BestCandidateNewMethodGroup {
3251                         get {
3252                                 return best_candidate_extension_group;
3253                         }
3254                 }
3255
3256                 public IErrorHandler CustomErrors {
3257                         get {
3258                                 return custom_errors;
3259                         }
3260                         set {
3261                                 custom_errors = value;
3262                         }
3263                 }
3264
3265                 TypeSpec DelegateType {
3266                         get {
3267                                 if ((restrictions & Restrictions.DelegateInvoke) == 0)
3268                                         throw new InternalErrorException ("Not running in delegate mode", loc);
3269
3270                                 return members [0].DeclaringType;
3271                         }
3272                 }
3273
3274                 bool IsProbingOnly {
3275                         get {
3276                                 return (restrictions & Restrictions.ProbingOnly) != 0;
3277                         }
3278                 }
3279
3280                 bool IsDelegateInvoke {
3281                         get {
3282                                 return (restrictions & Restrictions.DelegateInvoke) != 0;
3283                         }
3284                 }
3285
3286                 #endregion
3287
3288                 //
3289                 //  7.4.3.3  Better conversion from expression
3290                 //  Returns :   1    if a->p is better,
3291                 //              2    if a->q is better,
3292                 //              0 if neither is better
3293                 //
3294                 static int BetterExpressionConversion (ResolveContext ec, Argument a, TypeSpec p, TypeSpec q)
3295                 {
3296                         TypeSpec argument_type = a.Type;
3297                         if (argument_type == InternalType.AnonymousMethod && RootContext.Version > LanguageVersion.ISO_2) {
3298                                 //
3299                                 // Uwrap delegate from Expression<T>
3300                                 //
3301                                 if (p.GetDefinition () == TypeManager.expression_type) {
3302                                         p = TypeManager.GetTypeArguments (p)[0];
3303                                 }
3304                                 if (q.GetDefinition () == TypeManager.expression_type) {
3305                                         q = TypeManager.GetTypeArguments (q)[0];
3306                                 }
3307
3308                                 p = Delegate.GetInvokeMethod (ec.Compiler, p).ReturnType;
3309                                 q = Delegate.GetInvokeMethod (ec.Compiler, q).ReturnType;
3310                                 if (p == TypeManager.void_type && q != TypeManager.void_type)
3311                                         return 2;
3312                                 if (q == TypeManager.void_type && p != TypeManager.void_type)
3313                                         return 1;
3314                         } else {
3315                                 if (argument_type == p)
3316                                         return 1;
3317
3318                                 if (argument_type == q)
3319                                         return 2;
3320                         }
3321
3322                         return BetterTypeConversion (ec, p, q);
3323                 }
3324
3325                 //
3326                 // 7.4.3.4  Better conversion from type
3327                 //
3328                 public static int BetterTypeConversion (ResolveContext ec, TypeSpec p, TypeSpec q)
3329                 {
3330                         if (p == null || q == null)
3331                                 throw new InternalErrorException ("BetterTypeConversion got a null conversion");
3332
3333                         if (p == TypeManager.int32_type) {
3334                                 if (q == TypeManager.uint32_type || q == TypeManager.uint64_type)
3335                                         return 1;
3336                         } else if (p == TypeManager.int64_type) {
3337                                 if (q == TypeManager.uint64_type)
3338                                         return 1;
3339                         } else if (p == TypeManager.sbyte_type) {
3340                                 if (q == TypeManager.byte_type || q == TypeManager.ushort_type ||
3341                                         q == TypeManager.uint32_type || q == TypeManager.uint64_type)
3342                                         return 1;
3343                         } else if (p == TypeManager.short_type) {
3344                                 if (q == TypeManager.ushort_type || q == TypeManager.uint32_type ||
3345                                         q == TypeManager.uint64_type)
3346                                         return 1;
3347                         } else if (p == InternalType.Dynamic) {
3348                                 if (q == TypeManager.object_type)
3349                                         return 2;
3350                         }
3351
3352                         if (q == TypeManager.int32_type) {
3353                                 if (p == TypeManager.uint32_type || p == TypeManager.uint64_type)
3354                                         return 2;
3355                         } if (q == TypeManager.int64_type) {
3356                                 if (p == TypeManager.uint64_type)
3357                                         return 2;
3358                         } else if (q == TypeManager.sbyte_type) {
3359                                 if (p == TypeManager.byte_type || p == TypeManager.ushort_type ||
3360                                         p == TypeManager.uint32_type || p == TypeManager.uint64_type)
3361                                         return 2;
3362                         } if (q == TypeManager.short_type) {
3363                                 if (p == TypeManager.ushort_type || p == TypeManager.uint32_type ||
3364                                         p == TypeManager.uint64_type)
3365                                         return 2;
3366                         } else if (q == InternalType.Dynamic) {
3367                                 if (p == TypeManager.object_type)
3368                                         return 1;
3369                         }
3370
3371                         // TODO: this is expensive
3372                         Expression p_tmp = new EmptyExpression (p);
3373                         Expression q_tmp = new EmptyExpression (q);
3374
3375                         bool p_to_q = Convert.ImplicitConversionExists (ec, p_tmp, q);
3376                         bool q_to_p = Convert.ImplicitConversionExists (ec, q_tmp, p);
3377
3378                         if (p_to_q && !q_to_p)
3379                                 return 1;
3380
3381                         if (q_to_p && !p_to_q)
3382                                 return 2;
3383
3384                         return 0;
3385                 }
3386
3387                 /// <summary>
3388                 ///   Determines "Better function" between candidate
3389                 ///   and the current best match
3390                 /// </summary>
3391                 /// <remarks>
3392                 ///    Returns a boolean indicating :
3393                 ///     false if candidate ain't better
3394                 ///     true  if candidate is better than the current best match
3395                 /// </remarks>
3396                 static bool BetterFunction (ResolveContext ec, Arguments args, MemberSpec candidate, bool candidate_params,
3397                         MemberSpec best, bool best_params)
3398                 {
3399                         AParametersCollection candidate_pd = ((IParametersMember) candidate).Parameters;
3400                         AParametersCollection best_pd = ((IParametersMember) best).Parameters;
3401
3402                         bool better_at_least_one = false;
3403                         bool same = true;
3404                         int args_count = args == null ? 0 : args.Count;
3405                         int j = 0;
3406                         for (int c_idx = 0, b_idx = 0; j < args_count; ++j, ++c_idx, ++b_idx) {
3407                                 Argument a = args[j];
3408
3409                                 // Default arguments are ignored for better decision
3410                                 if (a.IsDefaultArgument)
3411                                         break;
3412
3413                                 TypeSpec ct = candidate_pd.Types[c_idx];
3414                                 TypeSpec bt = best_pd.Types[b_idx];
3415
3416                                 if (candidate_params && candidate_pd.FixedParameters[c_idx].ModFlags == Parameter.Modifier.PARAMS) {
3417                                         ct = TypeManager.GetElementType (ct);
3418                                         --c_idx;
3419                                 }
3420
3421                                 if (best_params && best_pd.FixedParameters[b_idx].ModFlags == Parameter.Modifier.PARAMS) {
3422                                         bt = TypeManager.GetElementType (bt);
3423                                         --b_idx;
3424                                 }
3425
3426                                 if (ct == bt)
3427                                         continue;
3428
3429                                 same = false;
3430                                 int result = BetterExpressionConversion (ec, a, ct, bt);
3431
3432                                 // for each argument, the conversion to 'ct' should be no worse than
3433                                 // the conversion to 'bt'.
3434                                 if (result == 2)
3435                                         return false;
3436
3437                                 // for at least one argument, the conversion to 'ct' should be better than
3438                                 // the conversion to 'bt'.
3439                                 if (result != 0)
3440                                         better_at_least_one = true;
3441                         }
3442
3443                         if (better_at_least_one)
3444                                 return true;
3445
3446                         //
3447                         // This handles the case
3448                         //
3449                         //   Add (float f1, float f2, float f3);
3450                         //   Add (params decimal [] foo);
3451                         //
3452                         // The call Add (3, 4, 5) should be ambiguous.  Without this check, the
3453                         // first candidate would've chosen as better.
3454                         //
3455                         if (!same)
3456                                 return false;
3457
3458                         //
3459                         // The two methods have equal non-optional parameter types, apply tie-breaking rules
3460                         //
3461
3462                         //
3463                         // This handles the following cases:
3464                         //
3465                         //  Foo (int i) is better than Foo (int i, long l = 0)
3466                         //  Foo (params int[] args) is better than Foo (int i = 0, params int[] args)
3467                         //
3468                         // Prefer non-optional version
3469                         //
3470                         // LAMESPEC: Specification claims this should be done at last but the opposite is true
3471                         if (candidate_params == best_params && candidate_pd.Count != best_pd.Count) {
3472                                 if (candidate_pd.Count >= best_pd.Count)
3473                                         return false;
3474
3475                                 if (j < candidate_pd.Count && candidate_pd.FixedParameters[j].HasDefaultValue)
3476                                         return false;
3477
3478                                 return true;
3479                         }
3480
3481                         //
3482                         // One is a non-generic method and second is a generic method, then non-generic is better
3483                         //
3484                         if (best.IsGeneric != candidate.IsGeneric)
3485                                 return best.IsGeneric;
3486
3487                         //
3488                         // This handles the following cases:
3489                         //
3490                         //   Trim () is better than Trim (params char[] chars)
3491                         //   Concat (string s1, string s2, string s3) is better than
3492                         //     Concat (string s1, params string [] srest)
3493                         //   Foo (int, params int [] rest) is better than Foo (params int [] rest)
3494                         //
3495                         // Prefer non-expanded version
3496                         //
3497                         if (candidate_params != best_params)
3498                                 return best_params;
3499
3500                         int candidate_param_count = candidate_pd.Count;
3501                         int best_param_count = best_pd.Count;
3502
3503                         if (candidate_param_count != best_param_count)
3504                                 // can only happen if (candidate_params && best_params)
3505                                 return candidate_param_count > best_param_count && best_pd.HasParams;
3506
3507                         //
3508                         // Both methods have the same number of parameters, and the parameters have equal types
3509                         // Pick the "more specific" signature using rules over original (non-inflated) types
3510                         //
3511                         var candidate_def_pd = ((IParametersMember) candidate.MemberDefinition).Parameters;
3512                         var best_def_pd = ((IParametersMember) best.MemberDefinition).Parameters;
3513
3514                         bool specific_at_least_once = false;
3515                         for (j = 0; j < candidate_param_count; ++j) {
3516                                 var ct = candidate_def_pd.Types[j];
3517                                 var bt = best_def_pd.Types[j];
3518                                 if (ct == bt)
3519                                         continue;
3520                                 TypeSpec specific = MoreSpecific (ct, bt);
3521                                 if (specific == bt)
3522                                         return false;
3523                                 if (specific == ct)
3524                                         specific_at_least_once = true;
3525                         }
3526
3527                         if (specific_at_least_once)
3528                                 return true;
3529
3530                         // FIXME: handle lifted operators
3531                         // ...
3532
3533                         return false;
3534                 }
3535
3536                 public static void Error_ConstructorMismatch (ResolveContext rc, TypeSpec type, int argCount, Location loc)
3537                 {
3538                         rc.Report.Error (1729, loc,
3539                                 "The type `{0}' does not contain a constructor that takes `{1}' arguments",
3540                                 type.GetSignatureForError (), argCount.ToString ());
3541                 }
3542
3543                 ///
3544                 /// Determines if the candidate method is applicable (section 14.4.2.1)
3545                 /// to the given set of arguments
3546                 /// A return value rates candidate method compatibility,
3547                 /// 0 = the best, int.MaxValue = the worst
3548                 ///
3549                 int IsApplicable (ResolveContext ec, ref Arguments arguments, int arg_count, ref MemberSpec candidate, ref bool params_expanded_form)
3550                 {
3551                         AParametersCollection pd = ((IParametersMember) candidate).Parameters;
3552                         int param_count = pd.Count;
3553                         int optional_count = 0;
3554                         int score;
3555
3556                         if (arg_count != param_count) {
3557                                 for (int i = 0; i < pd.Count; ++i) {
3558                                         if (pd.FixedParameters[i].HasDefaultValue) {
3559                                                 optional_count = pd.Count - i;
3560                                                 break;
3561                                         }
3562                                 }
3563
3564                                 int args_gap = System.Math.Abs (arg_count - param_count);
3565                                 if (optional_count != 0) {
3566                                         if (args_gap > optional_count)
3567                                                 return int.MaxValue - 10000 + args_gap - optional_count;
3568
3569                                         // Readjust expected number when params used
3570                                         if (pd.HasParams) {
3571                                                 optional_count--;
3572                                                 if (arg_count < param_count)
3573                                                         param_count--;
3574                                         } else if (arg_count > param_count) {
3575                                                 return int.MaxValue - 10000 + args_gap;
3576                                         }
3577                                 } else if (arg_count != param_count) {
3578                                         if (!pd.HasParams)
3579                                                 return int.MaxValue - 10000 + args_gap;
3580                                         if (arg_count < param_count - 1)
3581                                                 return int.MaxValue - 10000 + args_gap;
3582                                 }
3583
3584                                 // Resize to fit optional arguments
3585                                 if (optional_count != 0) {
3586                                         if (arguments == null) {
3587                                                 arguments = new Arguments (optional_count);
3588                                         } else {
3589                                                 // Have to create a new container, so the next run can do same
3590                                                 var resized = new Arguments (param_count);
3591                                                 resized.AddRange (arguments);
3592                                                 arguments = resized;
3593                                         }
3594
3595                                         for (int i = arg_count; i < param_count; ++i)
3596                                                 arguments.Add (null);
3597                                 }
3598                         }
3599
3600                         if (arg_count > 0) {
3601                                 //
3602                                 // Shuffle named arguments to the right positions if there are any
3603                                 //
3604                                 if (arguments[arg_count - 1] is NamedArgument) {
3605                                         arg_count = arguments.Count;
3606
3607                                         for (int i = 0; i < arg_count; ++i) {
3608                                                 bool arg_moved = false;
3609                                                 while (true) {
3610                                                         NamedArgument na = arguments[i] as NamedArgument;
3611                                                         if (na == null)
3612                                                                 break;
3613
3614                                                         int index = pd.GetParameterIndexByName (na.Name);
3615
3616                                                         // Named parameter not found or already reordered
3617                                                         if (index == i || index < 0)
3618                                                                 break;
3619
3620                                                         Argument temp;
3621                                                         if (index >= param_count) {
3622                                                                 // When using parameters which should not be available to the user
3623                                                                 if ((pd.FixedParameters[index].ModFlags & Parameter.Modifier.PARAMS) == 0)
3624                                                                         break;
3625
3626                                                                 arguments.Add (null);
3627                                                                 ++arg_count;
3628                                                                 temp = null;
3629                                                         } else {
3630                                                                 temp = arguments[index];
3631
3632                                                                 // The slot has been taken by positional argument
3633                                                                 if (temp != null && !(temp is NamedArgument))
3634                                                                         break;
3635                                                         }
3636
3637                                                         if (!arg_moved) {
3638                                                                 arguments.MarkReorderedArgument (na);
3639                                                                 arg_moved = true;
3640                                                         }
3641
3642                                                         arguments[index] = arguments[i];
3643                                                         arguments[i] = temp;
3644
3645                                                         if (temp == null)
3646                                                                 break;
3647                                                 }
3648                                         }
3649                                 } else {
3650                                         arg_count = arguments.Count;
3651                                 }
3652                         } else if (arguments != null) {
3653                                 arg_count = arguments.Count;
3654                         }
3655
3656                         //
3657                         // 1. Handle generic method using type arguments when specified or type inference
3658                         //
3659                         var ms = candidate as MethodSpec;
3660                         if (ms != null && ms.IsGeneric) {
3661                                 // Setup constraint checker for probing only
3662                                 ConstraintChecker cc = new ConstraintChecker (null);
3663
3664                                 if (type_arguments != null) {
3665                                         var g_args_count = ms.Arity;
3666                                         if (g_args_count != type_arguments.Count)
3667                                                 return int.MaxValue - 20000 + System.Math.Abs (type_arguments.Count - g_args_count);
3668
3669                                         candidate = ms = ms.MakeGenericMethod (type_arguments.Arguments);
3670                                         pd = ms.Parameters;
3671                                 } else {
3672                                         // TODO: It should not be here (we don't know yet whether any argument is lambda) but
3673                                         // for now it simplifies things. I should probably add a callback to ResolveContext
3674                                         if (lambda_conv_msgs == null) {
3675                                                 lambda_conv_msgs = new SessionReportPrinter ();
3676                                                 prev_recorder = ec.Report.SetPrinter (lambda_conv_msgs);
3677                                         }
3678
3679                                         var ti = new TypeInference (arguments);
3680                                         TypeSpec[] i_args = ti.InferMethodArguments (ec, ms);
3681                                         lambda_conv_msgs.EndSession ();
3682
3683                                         if (i_args == null)
3684                                                 return ti.InferenceScore - 20000;
3685
3686                                         if (i_args.Length != 0) {
3687                                                 candidate = ms = ms.MakeGenericMethod (i_args);
3688                                                 pd = ms.Parameters;
3689                                         }
3690
3691                                         cc.IgnoreInferredDynamic = true;
3692                                 }
3693
3694                                 //
3695                                 // Type arguments constraints have to match for the method to be applicable
3696                                 //
3697                                 if (!cc.CheckAll (ms.GetGenericMethodDefinition (), ms.TypeArguments, ms.Constraints, loc))
3698                                         return int.MaxValue - 25000;
3699
3700                         } else {
3701                                 if (type_arguments != null)
3702                                         return int.MaxValue - 15000;
3703                         }
3704
3705                         //
3706                         // 2. Each argument has to be implicitly convertible to method parameter
3707                         //
3708                         Parameter.Modifier p_mod = 0;
3709                         TypeSpec pt = null;
3710                         for (int i = 0; i < arg_count; i++) {
3711                                 Argument a = arguments[i];
3712                                 if (a == null) {
3713                                         if (!pd.FixedParameters[i].HasDefaultValue)
3714                                                 throw new InternalErrorException ();
3715
3716                                         //
3717                                         // Get the default value expression, we can use the same expression
3718                                         // if the type matches
3719                                         //
3720                                         Expression e = pd.FixedParameters[i].DefaultValue;
3721                                         if (!(e is Constant) || e.Type.IsGenericOrParentIsGeneric) {
3722                                                 //
3723                                                 // LAMESPEC: No idea what the exact rules are for System.Reflection.Missing.Value instead of null
3724                                                 //
3725                                                 if (e == EmptyExpression.MissingValue && pd.Types[i] == TypeManager.object_type) {
3726                                                         e = new MemberAccess (new MemberAccess (new MemberAccess (
3727                                                                 new QualifiedAliasMember (QualifiedAliasMember.GlobalAlias, "System", loc), "Reflection", loc), "Missing", loc), "Value", loc);
3728                                                 } else {
3729                                                         e = new DefaultValueExpression (new TypeExpression (pd.Types[i], loc), loc);
3730                                                 }
3731
3732                                                 e = e.Resolve (ec);
3733                                         }
3734
3735                                         arguments[i] = new Argument (e, Argument.AType.Default);
3736                                         continue;
3737                                 }
3738
3739                                 if (p_mod != Parameter.Modifier.PARAMS) {
3740                                         p_mod = pd.FixedParameters[i].ModFlags;
3741                                         pt = pd.Types[i];
3742                                 } else if (!params_expanded_form) {
3743                                         params_expanded_form = true;
3744                                         pt = ((ElementTypeSpec) pt).Element;
3745                                         i -= 2;
3746                                         continue;
3747                                 }
3748
3749                                 score = 1;
3750                                 if (!params_expanded_form)
3751                                         score = IsArgumentCompatible (ec, a, p_mod & ~Parameter.Modifier.PARAMS, pt);
3752
3753                                 //
3754                                 // It can be applicable in expanded form (when not doing exact match like for delegates)
3755                                 //
3756                                 if (score != 0 && (p_mod & Parameter.Modifier.PARAMS) != 0 && (restrictions & Restrictions.CovariantDelegate) == 0) {
3757                                         if (!params_expanded_form)
3758                                                 pt = ((ElementTypeSpec) pt).Element;
3759
3760                                         score = IsArgumentCompatible (ec, a, Parameter.Modifier.NONE, pt);
3761                                         if (score == 0)
3762                                                 params_expanded_form = true;
3763                                 }
3764
3765                                 if (score != 0) {
3766                                         if (params_expanded_form)
3767                                                 ++score;
3768                                         return (arg_count - i) * 2 + score;
3769                                 }
3770                         }
3771
3772                         //
3773                         // When params parameter has notargument, will be provided later if the method is the best candidate
3774                         //
3775                         if (arg_count + 1 == pd.Count && (pd.FixedParameters [arg_count].ModFlags & Parameter.Modifier.PARAMS) != 0)
3776                                 params_expanded_form = true;
3777
3778                         return 0;
3779                 }
3780
3781                 int IsArgumentCompatible (ResolveContext ec, Argument argument, Parameter.Modifier param_mod, TypeSpec parameter)
3782                 {
3783                         //
3784                         // Types have to be identical when ref or out modifer
3785                         // is used and argument is not of dynamic type
3786                         //
3787                         if ((argument.Modifier | param_mod) != 0) {
3788                                 //
3789                                 // Defer to dynamic binder
3790                                 //
3791                                 if (argument.Type == InternalType.Dynamic)
3792                                         return 0;
3793
3794                                 if (argument.Type != parameter) {
3795                                         //
3796                                         // Do full equality check after quick path
3797                                         //
3798                                         if (!TypeSpecComparer.IsEqual (argument.Type, parameter))
3799                                                 return 2;
3800                                 }
3801                         } else {
3802                                 //
3803                                 // Deploy custom error reporting for lambda methods. When probing lambda methods
3804                                 // keep all errors reported in separate set and once we are done and no best
3805                                 // candidate found, this set is used to report more details about what was wrong
3806                                 // with lambda body
3807                                 //
3808                                 if (argument.Expr.Type == InternalType.AnonymousMethod) {
3809                                         if (lambda_conv_msgs == null) {
3810                                                 lambda_conv_msgs = new SessionReportPrinter ();
3811                                                 prev_recorder = ec.Report.SetPrinter (lambda_conv_msgs);
3812                                         }
3813                                 }
3814
3815                                 if (!Convert.ImplicitConversionExists (ec, argument.Expr, parameter)) {
3816                                         if (lambda_conv_msgs != null) {
3817                                                 lambda_conv_msgs.EndSession ();
3818                                         }
3819
3820                                         return 2;
3821                                 }
3822                         }
3823
3824                         if (argument.Modifier != param_mod)
3825                                 return 1;
3826
3827                         return 0;
3828                 }
3829
3830                 static TypeSpec MoreSpecific (TypeSpec p, TypeSpec q)
3831                 {
3832                         if (TypeManager.IsGenericParameter (p) && !TypeManager.IsGenericParameter (q))
3833                                 return q;
3834                         if (!TypeManager.IsGenericParameter (p) && TypeManager.IsGenericParameter (q))
3835                                 return p;
3836
3837                         var ac_p = p as ArrayContainer;
3838                         if (ac_p != null) {
3839                                 var ac_q = ((ArrayContainer) q);
3840                                 TypeSpec specific = MoreSpecific (ac_p.Element, ac_q.Element);
3841                                 if (specific == ac_p.Element)
3842                                         return p;
3843                                 if (specific == ac_q.Element)
3844                                         return q;
3845                         } else if (TypeManager.IsGenericType (p)) {
3846                                 var pargs = TypeManager.GetTypeArguments (p);
3847                                 var qargs = TypeManager.GetTypeArguments (q);
3848
3849                                 bool p_specific_at_least_once = false;
3850                                 bool q_specific_at_least_once = false;
3851
3852                                 for (int i = 0; i < pargs.Length; i++) {
3853                                         TypeSpec specific = MoreSpecific (pargs[i], qargs[i]);
3854                                         if (specific == pargs[i])
3855                                                 p_specific_at_least_once = true;
3856                                         if (specific == qargs[i])
3857                                                 q_specific_at_least_once = true;
3858                                 }
3859
3860                                 if (p_specific_at_least_once && !q_specific_at_least_once)
3861                                         return p;
3862                                 if (!p_specific_at_least_once && q_specific_at_least_once)
3863                                         return q;
3864                         }
3865
3866                         return null;
3867                 }
3868
3869                 //
3870                 // Find the best method from candidate list
3871                 //
3872                 public T ResolveMember<T> (ResolveContext rc, ref Arguments args) where T : MemberSpec, IParametersMember
3873                 {
3874                         List<AmbiguousCandidate> ambiguous_candidates = null;
3875
3876                         MemberSpec best_candidate;
3877                         Arguments best_candidate_args = null;
3878                         bool best_candidate_params = false;
3879                         int best_candidate_rate;
3880
3881                         int args_count = args != null ? args.Count : 0;
3882                         Arguments candidate_args = args;
3883                         bool error_mode = false;
3884                         var current_type = rc.CurrentType;
3885                         MemberSpec invocable_member = null;
3886
3887                         // Be careful, cannot return until error reporter is restored
3888                         while (true) {
3889                                 best_candidate = null;
3890                                 best_candidate_rate = int.MaxValue;
3891
3892                                 var type_members = members;
3893                                 try {
3894
3895                                         do {
3896                                                 for (int i = 0; i < type_members.Count; ++i) {
3897                                                         var member = type_members[i];
3898
3899                                                         //
3900                                                         // Methods in a base class are not candidates if any method in a derived
3901                                                         // class is applicable
3902                                                         //
3903                                                         if ((member.Modifiers & Modifiers.OVERRIDE) != 0)
3904                                                                 continue;
3905
3906                                                         if (!member.IsAccessible (current_type) && !error_mode)
3907                                                                 continue;
3908
3909                                                         if (!(member is IParametersMember)) {
3910                                                                 //
3911                                                                 // Will use it later to report ambiguity between best method and invocable member
3912                                                                 //
3913                                                                 if (Invocation.IsMemberInvocable (member))
3914                                                                         invocable_member = member;
3915
3916                                                                 continue;
3917                                                         }
3918
3919                                                         //
3920                                                         // Check if candidate is applicable
3921                                                         //
3922                                                         bool params_expanded_form = false;
3923                                                         int candidate_rate = IsApplicable (rc, ref candidate_args, args_count, ref member, ref params_expanded_form);
3924
3925                                                         //
3926                                                         // How does it score compare to others
3927                                                         //
3928                                                         if (candidate_rate < best_candidate_rate) {
3929                                                                 best_candidate_rate = candidate_rate;
3930                                                                 best_candidate = member;
3931                                                                 best_candidate_args = candidate_args;
3932                                                                 best_candidate_params = params_expanded_form;
3933                                                         } else if (candidate_rate == 0) {
3934                                                                 //
3935                                                                 // The member look is done per type for most operations but sometimes
3936                                                                 // it's not possible like for binary operators overload because they
3937                                                                 // are unioned between 2 sides
3938                                                                 //
3939                                                                 if ((restrictions & Restrictions.BaseMembersIncluded) != 0) {
3940                                                                         if (TypeSpec.IsBaseClass (best_candidate.DeclaringType, member.DeclaringType, true))
3941                                                                                 continue;
3942                                                                 }
3943
3944                                                                 // Is new candidate better
3945                                                                 if (BetterFunction (rc, candidate_args, member, params_expanded_form, best_candidate, best_candidate_params)) {
3946                                                                         best_candidate = member;
3947                                                                         best_candidate_args = candidate_args;
3948                                                                         best_candidate_params = params_expanded_form;
3949                                                                 } else {
3950                                                                         // It's not better but any other found later could be but we are not sure yet
3951                                                                         if (ambiguous_candidates == null)
3952                                                                                 ambiguous_candidates = new List<AmbiguousCandidate> ();
3953
3954                                                                         ambiguous_candidates.Add (new AmbiguousCandidate (member, params_expanded_form));
3955                                                                 }
3956                                                         }
3957
3958                                                         // Restore expanded arguments
3959                                                         if (candidate_args != args)
3960                                                                 candidate_args = args;
3961                                                 }
3962                                         } while (best_candidate_rate != 0 && (type_members = base_provider.GetBaseMembers (type_members[0].DeclaringType.BaseType)) != null);
3963                                 } finally {
3964                                         if (prev_recorder != null)
3965                                                 rc.Report.SetPrinter (prev_recorder);
3966                                 }
3967
3968                                 //
3969                                 // We've found exact match
3970                                 //
3971                                 if (best_candidate_rate == 0)
3972                                         break;
3973
3974                                 //
3975                                 // Try extension methods lookup when no ordinary method match was found and provider enables it
3976                                 //
3977                                 if (!error_mode) {
3978                                         var emg = base_provider.LookupExtensionMethod (rc);
3979                                         if (emg != null) {
3980                                                 emg = emg.OverloadResolve (rc, ref args, null, restrictions);
3981                                                 if (emg != null) {
3982                                                         best_candidate_extension_group = emg;
3983                                                         return (T) (MemberSpec) emg.BestCandidate;
3984                                                 }
3985                                         }
3986                                 }
3987
3988                                 // Don't run expensive error reporting mode for probing
3989                                 if (IsProbingOnly)
3990                                         return null;
3991
3992                                 if (error_mode)
3993                                         break;
3994
3995                                 lambda_conv_msgs = null;
3996                                 error_mode = true;
3997                         }
3998
3999                         //
4000                         // No best member match found, report an error
4001                         //
4002                         if (best_candidate_rate != 0 || error_mode) {
4003                                 ReportOverloadError (rc, best_candidate, best_candidate_args, best_candidate_params);
4004                                 return null;
4005                         }
4006
4007                         // TODO: HasDynamic is quite slow
4008                         if (args_count != 0 && (restrictions & Restrictions.CovariantDelegate) == 0 && args.HasDynamic) {
4009                                 if (args [0].ArgType == Argument.AType.ExtensionType) {
4010                                         rc.Report.Error (1973, loc,
4011                                                 "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",
4012                                                 args [0].Type.GetSignatureForError (), best_candidate.Name, best_candidate.GetSignatureForError());
4013                                 }
4014
4015                                 BestCandidateIsDynamic = true;
4016                                 return null;
4017                         }
4018
4019                         if (ambiguous_candidates != null) {
4020                                 //
4021                                 // Now check that there are no ambiguities i.e the selected method
4022                                 // should be better than all the others
4023                                 //
4024                                 for (int ix = 0; ix < ambiguous_candidates.Count; ix++) {
4025                                         var candidate = ambiguous_candidates [ix];
4026
4027                                         if (!BetterFunction (rc, candidate_args, best_candidate, best_candidate_params, candidate.Member, candidate.Expanded)) {
4028                                                 var ambiguous = candidate.Member;
4029                                                 if (custom_errors == null || !custom_errors.AmbiguousCandidates (rc, best_candidate, ambiguous)) {
4030                                                         rc.Report.SymbolRelatedToPreviousError (best_candidate);
4031                                                         rc.Report.SymbolRelatedToPreviousError (ambiguous);
4032                                                         rc.Report.Error (121, loc, "The call is ambiguous between the following methods or properties: `{0}' and `{1}'",
4033                                                                 best_candidate.GetSignatureForError (), ambiguous.GetSignatureForError ());
4034                                                 }
4035
4036                                                 return (T) best_candidate;
4037                                         }
4038                                 }
4039                         }
4040
4041                         if (invocable_member != null) {
4042                                 rc.Report.SymbolRelatedToPreviousError (best_candidate);
4043                                 rc.Report.SymbolRelatedToPreviousError (invocable_member);
4044                                 rc.Report.Warning (467, 2, loc, "Ambiguity between method `{0}' and invocable non-method `{1}'. Using method group",
4045                                         best_candidate.GetSignatureForError (), invocable_member.GetSignatureForError ());
4046                         }
4047
4048                         //
4049                         // And now check if the arguments are all
4050                         // compatible, perform conversions if
4051                         // necessary etc. and return if everything is
4052                         // all right
4053                         //
4054                         if (!VerifyArguments (rc, ref best_candidate_args, best_candidate, best_candidate_params))
4055                                 return null;
4056
4057                         if (best_candidate == null)
4058                                 return null;
4059
4060                         //
4061                         // Check ObsoleteAttribute on the best method
4062                         //
4063                         ObsoleteAttribute oa = best_candidate.GetAttributeObsolete ();
4064                         if (oa != null && !rc.IsObsolete)
4065                                 AttributeTester.Report_ObsoleteMessage (oa, best_candidate.GetSignatureForError (), loc, rc.Report);
4066
4067                         best_candidate.MemberDefinition.SetIsUsed ();
4068
4069                         args = best_candidate_args;
4070                         return (T) best_candidate;
4071                 }
4072
4073                 public MethodSpec ResolveOperator (ResolveContext rc, ref Arguments args)
4074                 {
4075                         return ResolveMember<MethodSpec> (rc, ref args);
4076                 }
4077
4078                 void ReportArgumentMismatch (ResolveContext ec, int idx, MemberSpec method,
4079                                                                                                         Argument a, AParametersCollection expected_par, TypeSpec paramType)
4080                 {
4081                         if (custom_errors != null && custom_errors.ArgumentMismatch (ec, method, a, idx))
4082                                 return;
4083
4084                         if (a is CollectionElementInitializer.ElementInitializerArgument) {
4085                                 ec.Report.SymbolRelatedToPreviousError (method);
4086                                 if ((expected_par.FixedParameters[idx].ModFlags & Parameter.Modifier.ISBYREF) != 0) {
4087                                         ec.Report.Error (1954, loc, "The best overloaded collection initalizer method `{0}' cannot have 'ref', or `out' modifier",
4088                                                 TypeManager.CSharpSignature (method));
4089                                         return;
4090                                 }
4091                                 ec.Report.Error (1950, loc, "The best overloaded collection initalizer method `{0}' has some invalid arguments",
4092                                           TypeManager.CSharpSignature (method));
4093                         } else if (IsDelegateInvoke) {
4094                                 ec.Report.Error (1594, loc, "Delegate `{0}' has some invalid arguments",
4095                                         DelegateType.GetSignatureForError ());
4096                         } else {
4097                                 ec.Report.SymbolRelatedToPreviousError (method);
4098                                 ec.Report.Error (1502, loc, "The best overloaded method match for `{0}' has some invalid arguments",
4099                                         method.GetSignatureForError ());
4100                         }
4101
4102                         Parameter.Modifier mod = idx >= expected_par.Count ? 0 : expected_par.FixedParameters[idx].ModFlags;
4103
4104                         string index = (idx + 1).ToString ();
4105                         if (((mod & (Parameter.Modifier.REF | Parameter.Modifier.OUT)) ^
4106                                 (a.Modifier & (Parameter.Modifier.REF | Parameter.Modifier.OUT))) != 0) {
4107                                 if ((mod & Parameter.Modifier.ISBYREF) == 0)
4108                                         ec.Report.Error (1615, loc, "Argument `#{0}' does not require `{1}' modifier. Consider removing `{1}' modifier",
4109                                                 index, Parameter.GetModifierSignature (a.Modifier));
4110                                 else
4111                                         ec.Report.Error (1620, loc, "Argument `#{0}' is missing `{1}' modifier",
4112                                                 index, Parameter.GetModifierSignature (mod));
4113                         } else {
4114                                 string p1 = a.GetSignatureForError ();
4115                                 string p2 = TypeManager.CSharpName (paramType);
4116
4117                                 if (p1 == p2) {
4118                                         ec.Report.ExtraInformation (loc, "(equally named types possibly from different assemblies in previous ");
4119                                         ec.Report.SymbolRelatedToPreviousError (a.Expr.Type);
4120                                         ec.Report.SymbolRelatedToPreviousError (paramType);
4121                                 }
4122
4123                                 ec.Report.Error (1503, loc,
4124                                         "Argument `#{0}' cannot convert `{1}' expression to type `{2}'", index, p1, p2);
4125                         }
4126                 }
4127
4128                 //
4129                 // We have failed to find exact match so we return error info about the closest match
4130                 //
4131                 void ReportOverloadError (ResolveContext rc, MemberSpec best_candidate, Arguments args, bool params_expanded)
4132                 {
4133                         int ta_count = type_arguments == null ? 0 : type_arguments.Count;
4134                         int arg_count = args == null ? 0 : args.Count;
4135
4136                         if (ta_count != best_candidate.Arity && (ta_count > 0 || ((IParametersMember) best_candidate).Parameters.IsEmpty)) {
4137                                 var mg = new MethodGroupExpr (new [] { best_candidate }, best_candidate.DeclaringType, loc);
4138                                 mg.Error_TypeArgumentsCannotBeUsed (rc.Report, loc, best_candidate, ta_count);
4139                                 return;
4140                         }
4141
4142                         if (lambda_conv_msgs != null) {
4143                                 if (lambda_conv_msgs.Merge (rc.Report.Printer))
4144                                         return;
4145                         }
4146
4147                         //
4148                         // For candidates which match on parameters count report more details about incorrect arguments
4149                         //
4150                         var pm = best_candidate as IParametersMember;
4151                         if (pm != null) {
4152                                 int unexpanded_count = pm.Parameters.HasParams ? pm.Parameters.Count - 1 : pm.Parameters.Count;
4153                                 if (pm.Parameters.Count == arg_count || params_expanded || unexpanded_count == arg_count) {
4154                                         // Reject any inaccessible member
4155                                         if (!best_candidate.IsAccessible (rc.CurrentType)) {
4156                                                 rc.Report.SymbolRelatedToPreviousError (best_candidate);
4157                                                 Expression.ErrorIsInaccesible (rc, best_candidate.GetSignatureForError (), loc);
4158                                                 return;
4159                                         }
4160
4161                                         var ms = best_candidate as MethodSpec;
4162                                         if (ms != null && ms.IsGeneric) {
4163                                                 bool constr_ok = true;
4164                                                 if (ms.TypeArguments != null)
4165                                                         constr_ok = new ConstraintChecker (rc.MemberContext).CheckAll (ms.GetGenericMethodDefinition (), ms.TypeArguments, ms.Constraints, loc);
4166
4167                                                 if (ta_count == 0) {
4168                                                         if (custom_errors != null && custom_errors.TypeInferenceFailed (rc, best_candidate))
4169                                                                 return;
4170
4171                                                         if (constr_ok) {
4172                                                                 rc.Report.Error (411, loc,
4173                                                                         "The type arguments for method `{0}' cannot be inferred from the usage. Try specifying the type arguments explicitly",
4174                                                                         ms.GetGenericMethodDefinition ().GetSignatureForError ());
4175                                                         }
4176
4177                                                         return;
4178                                                 }
4179                                         }
4180
4181                                         VerifyArguments (rc, ref args, best_candidate, params_expanded);
4182                                         return;
4183                                 }
4184                         }
4185
4186                         //
4187                         // We failed to find any method with correct argument count, report best candidate
4188                         //
4189                         if (custom_errors != null && custom_errors.NoArgumentMatch (rc, best_candidate))
4190                                 return;
4191
4192                         if (best_candidate.Kind == MemberKind.Constructor) {
4193                                 rc.Report.SymbolRelatedToPreviousError (best_candidate);
4194                                 Error_ConstructorMismatch (rc, best_candidate.DeclaringType, arg_count, loc);
4195                         } else if (IsDelegateInvoke) {
4196                                 rc.Report.SymbolRelatedToPreviousError (DelegateType);
4197                                 rc.Report.Error (1593, loc, "Delegate `{0}' does not take `{1}' arguments",
4198                                         DelegateType.GetSignatureForError (), arg_count.ToString ());
4199                         } else {
4200                                 string name = best_candidate.Kind == MemberKind.Indexer ? "this" : best_candidate.Name;
4201                                 rc.Report.SymbolRelatedToPreviousError (best_candidate);
4202                                 rc.Report.Error (1501, loc, "No overload for method `{0}' takes `{1}' arguments",
4203                                         name, arg_count.ToString ());
4204                         }
4205                 }
4206
4207                 bool VerifyArguments (ResolveContext ec, ref Arguments args, MemberSpec member, bool chose_params_expanded)
4208                 {
4209                         var pm = member as IParametersMember;
4210                         var pd = pm.Parameters;
4211
4212                         Parameter.Modifier p_mod = 0;
4213                         TypeSpec pt = null;
4214                         int a_idx = 0, a_pos = 0;
4215                         Argument a = null;
4216                         ArrayInitializer params_initializers = null;
4217                         bool has_unsafe_arg = pm.MemberType.IsPointer;
4218                         int arg_count = args == null ? 0 : args.Count;
4219
4220                         for (; a_idx < arg_count; a_idx++, ++a_pos) {
4221                                 a = args[a_idx];
4222                                 if (p_mod != Parameter.Modifier.PARAMS) {
4223                                         p_mod = pd.FixedParameters[a_idx].ModFlags;
4224                                         pt = pd.Types[a_idx];
4225                                         has_unsafe_arg |= pt.IsPointer;
4226
4227                                         if (p_mod == Parameter.Modifier.PARAMS) {
4228                                                 if (chose_params_expanded) {
4229                                                         params_initializers = new ArrayInitializer (arg_count - a_idx, a.Expr.Location);
4230                                                         pt = TypeManager.GetElementType (pt);
4231                                                 }
4232                                         }
4233                                 }
4234
4235                                 //
4236                                 // Types have to be identical when ref or out modifer is used
4237                                 //
4238                                 if (a.Modifier != 0 || (p_mod & ~Parameter.Modifier.PARAMS) != 0) {
4239                                         if ((p_mod & ~Parameter.Modifier.PARAMS) != a.Modifier)
4240                                                 break;
4241
4242                                         if (a.Expr.Type == pt || TypeSpecComparer.IsEqual (a.Expr.Type, pt))
4243                                                 continue;
4244
4245                                         break;
4246                                 }
4247
4248                                 NamedArgument na = a as NamedArgument;
4249                                 if (na != null) {
4250                                         int name_index = pd.GetParameterIndexByName (na.Name);
4251                                         if (name_index < 0 || name_index >= pd.Count) {
4252                                                 if (IsDelegateInvoke) {
4253                                                         ec.Report.SymbolRelatedToPreviousError (DelegateType);
4254                                                         ec.Report.Error (1746, na.Location,
4255                                                                 "The delegate `{0}' does not contain a parameter named `{1}'",
4256                                                                 DelegateType.GetSignatureForError (), na.Name);
4257                                                 } else {
4258                                                         ec.Report.SymbolRelatedToPreviousError (member);
4259                                                         ec.Report.Error (1739, na.Location,
4260                                                                 "The best overloaded method match for `{0}' does not contain a parameter named `{1}'",
4261                                                                 TypeManager.CSharpSignature (member), na.Name);
4262                                                 }
4263                                         } else if (args[name_index] != a) {
4264                                                 if (IsDelegateInvoke)
4265                                                         ec.Report.SymbolRelatedToPreviousError (DelegateType);
4266                                                 else
4267                                                         ec.Report.SymbolRelatedToPreviousError (member);
4268
4269                                                 ec.Report.Error (1744, na.Location,
4270                                                         "Named argument `{0}' cannot be used for a parameter which has positional argument specified",
4271                                                         na.Name);
4272                                         }
4273                                 }
4274
4275                                 if (a.Expr.Type == InternalType.Dynamic)
4276                                         continue;
4277
4278                                 if ((restrictions & Restrictions.CovariantDelegate) != 0 && !Delegate.IsTypeCovariant (a.Expr, pt)) {
4279                                         custom_errors.NoArgumentMatch (ec, member);
4280                                         return false;
4281                                 }
4282
4283                                 Expression conv = Convert.ImplicitConversion (ec, a.Expr, pt, loc);
4284                                 if (conv == null)
4285                                         break;
4286
4287                                 //
4288                                 // Convert params arguments to an array initializer
4289                                 //
4290                                 if (params_initializers != null) {
4291                                         // we choose to use 'a.Expr' rather than 'conv' so that
4292                                         // we don't hide the kind of expression we have (esp. CompoundAssign.Helper)
4293                                         params_initializers.Add (a.Expr);
4294                                         args.RemoveAt (a_idx--);
4295                                         --arg_count;
4296                                         continue;
4297                                 }
4298
4299                                 // Update the argument with the implicit conversion
4300                                 a.Expr = conv;
4301                         }
4302
4303                         if (a_idx != arg_count) {
4304                                 ReportArgumentMismatch (ec, a_pos, member, a, pd, pt);
4305                                 return false;
4306                         }
4307
4308                         //
4309                         // Fill not provided arguments required by params modifier
4310                         //
4311                         if (params_initializers == null && pd.HasParams && arg_count + 1 == pd.Count) {
4312                                 if (args == null)
4313                                         args = new Arguments (1);
4314
4315                                 pt = pd.Types[pd.Count - 1];
4316                                 pt = TypeManager.GetElementType (pt);
4317                                 has_unsafe_arg |= pt.IsPointer;
4318                                 params_initializers = new ArrayInitializer (0, loc);
4319                         }
4320
4321                         //
4322                         // Append an array argument with all params arguments
4323                         //
4324                         if (params_initializers != null) {
4325                                 args.Add (new Argument (
4326                                         new ArrayCreation (new TypeExpression (pt, loc), params_initializers, loc).Resolve (ec)));
4327                                 arg_count++;
4328                         }
4329
4330                         if (has_unsafe_arg && !ec.IsUnsafe) {
4331                                 Expression.UnsafeError (ec, loc);
4332                         }
4333
4334                         //
4335                         // We could infer inaccesible type arguments
4336                         //
4337                         if (type_arguments == null && member.IsGeneric) {
4338                                 var ms = (MethodSpec) member;
4339                                 foreach (var ta in ms.TypeArguments) {
4340                                         if (!ta.IsAccessible (ec.CurrentType)) {
4341                                                 ec.Report.SymbolRelatedToPreviousError (ta);
4342                                                 Expression.ErrorIsInaccesible (ec, member.GetSignatureForError (), loc);
4343                                                 break;
4344                                         }
4345                                 }
4346                         }
4347
4348                         return true;
4349                 }
4350         }
4351
4352         public class ConstantExpr : MemberExpr
4353         {
4354                 ConstSpec constant;
4355
4356                 public ConstantExpr (ConstSpec constant, Location loc)
4357                 {
4358                         this.constant = constant;
4359                         this.loc = loc;
4360                 }
4361
4362                 public override string Name {
4363                         get { throw new NotImplementedException (); }
4364                 }
4365
4366                 public override bool IsInstance {
4367                         get { return !IsStatic; }
4368                 }
4369
4370                 public override bool IsStatic {
4371                         get { return true; }
4372                 }
4373
4374                 protected override TypeSpec DeclaringType {
4375                         get { return constant.DeclaringType; }
4376                 }
4377
4378                 public override Expression CreateExpressionTree (ResolveContext ec)
4379                 {
4380                         throw new NotSupportedException ("ET");
4381                 }
4382
4383                 protected override Expression DoResolve (ResolveContext rc)
4384                 {
4385                         ResolveInstanceExpression (rc);
4386                         DoBestMemberChecks (rc, constant);
4387
4388                         var c = constant.GetConstant (rc);
4389
4390                         // Creates reference expression to the constant value
4391                         return Constant.CreateConstant (rc, constant.MemberType, c.GetValue (), loc);
4392                 }
4393
4394                 public override void Emit (EmitContext ec)
4395                 {
4396                         throw new NotSupportedException ();
4397                 }
4398
4399                 public override string GetSignatureForError ()
4400                 {
4401                         return constant.GetSignatureForError ();
4402                 }
4403
4404                 public override void SetTypeArguments (ResolveContext ec, TypeArguments ta)
4405                 {
4406                         Error_TypeArgumentsCannotBeUsed (ec.Report, "constant", GetSignatureForError (), loc);
4407                 }
4408         }
4409
4410         /// <summary>
4411         ///   Fully resolved expression that evaluates to a Field
4412         /// </summary>
4413         public class FieldExpr : MemberExpr, IDynamicAssign, IMemoryLocation, IVariableReference {
4414                 protected FieldSpec spec;
4415                 VariableInfo variable_info;
4416
4417                 LocalTemporary temp;
4418                 bool prepared;
4419
4420                 protected FieldExpr (Location l)
4421                 {
4422                         loc = l;
4423                 }
4424
4425                 public FieldExpr (FieldSpec spec, Location loc)
4426                 {
4427                         this.spec = spec;
4428                         this.loc = loc;
4429
4430                         type = spec.MemberType;
4431                 }
4432
4433                 public FieldExpr (FieldBase fi, Location l)
4434                         : this (fi.Spec, l)
4435                 {
4436                 }
4437
4438 #region Properties
4439
4440                 public override string Name {
4441                         get {
4442                                 return spec.Name;
4443                         }
4444                 }
4445
4446                 public bool IsHoisted {
4447                         get {
4448                                 IVariableReference hv = InstanceExpression as IVariableReference;
4449                                 return hv != null && hv.IsHoisted;
4450                         }
4451                 }
4452
4453                 public override bool IsInstance {
4454                         get {
4455                                 return !spec.IsStatic;
4456                         }
4457                 }
4458
4459                 public override bool IsStatic {
4460                         get {
4461                                 return spec.IsStatic;
4462                         }
4463                 }
4464
4465                 public FieldSpec Spec {
4466                         get {
4467                                 return spec;
4468                         }
4469                 }
4470
4471                 protected override TypeSpec DeclaringType {
4472                         get {
4473                                 return spec.DeclaringType;
4474                         }
4475                 }
4476
4477                 public VariableInfo VariableInfo {
4478                         get {
4479                                 return variable_info;
4480                         }
4481                 }
4482
4483 #endregion
4484
4485                 public override string GetSignatureForError ()
4486                 {
4487                         return TypeManager.GetFullNameSignature (spec);
4488                 }
4489
4490                 public bool IsMarshalByRefAccess ()
4491                 {
4492                         // Checks possible ldflda of field access expression
4493                         return !spec.IsStatic && TypeManager.IsValueType (spec.MemberType) &&
4494                                 TypeSpec.IsBaseClass (spec.DeclaringType, TypeManager.mbr_type, false) &&
4495                                 !(InstanceExpression is This);
4496                 }
4497
4498                 public void SetHasAddressTaken ()
4499                 {
4500                         IVariableReference vr = InstanceExpression as IVariableReference;
4501                         if (vr != null)
4502                                 vr.SetHasAddressTaken ();
4503                 }
4504
4505                 public override Expression CreateExpressionTree (ResolveContext ec)
4506                 {
4507                         Expression instance;
4508                         if (InstanceExpression == null) {
4509                                 instance = new NullLiteral (loc);
4510                         } else {
4511                                 instance = InstanceExpression.CreateExpressionTree (ec);
4512                         }
4513
4514                         Arguments args = Arguments.CreateForExpressionTree (ec, null,
4515                                 instance,
4516                                 CreateTypeOfExpression ());
4517
4518                         return CreateExpressionFactoryCall (ec, "Field", args);
4519                 }
4520
4521                 public Expression CreateTypeOfExpression ()
4522                 {
4523                         return new TypeOfField (spec, loc);
4524                 }
4525
4526                 protected override Expression DoResolve (ResolveContext ec)
4527                 {
4528                         return DoResolve (ec, false, false);
4529                 }
4530
4531                 Expression DoResolve (ResolveContext ec, bool lvalue_instance, bool out_access)
4532                 {
4533                         if (ResolveInstanceExpression (ec)) {
4534                                 // Resolve the field's instance expression while flow analysis is turned
4535                                 // off: when accessing a field "a.b", we must check whether the field
4536                                 // "a.b" is initialized, not whether the whole struct "a" is initialized.
4537
4538                                 if (lvalue_instance) {
4539                                         using (ec.With (ResolveContext.Options.DoFlowAnalysis, false)) {
4540                                                 Expression right_side =
4541                                                         out_access ? EmptyExpression.LValueMemberOutAccess : EmptyExpression.LValueMemberAccess;
4542
4543                                                 InstanceExpression = InstanceExpression.ResolveLValue (ec, right_side);
4544                                         }
4545                                 } else {
4546                                         using (ec.With (ResolveContext.Options.DoFlowAnalysis, false)) {
4547                                                 InstanceExpression = InstanceExpression.Resolve (ec, ResolveFlags.VariableOrValue);
4548                                         }
4549                                 }
4550
4551                                 if (InstanceExpression == null)
4552                                         return null;
4553
4554                                 using (ec.Set (ResolveContext.Options.OmitStructFlowAnalysis)) {
4555                                         InstanceExpression.CheckMarshalByRefAccess (ec);
4556                                 }
4557                         }
4558
4559                         DoBestMemberChecks (ec, spec);
4560
4561                         var fb = spec as FixedFieldSpec;
4562                         IVariableReference var = InstanceExpression as IVariableReference;
4563
4564                         if (lvalue_instance && var != null && var.VariableInfo != null) {
4565                                 var.VariableInfo.SetFieldAssigned (ec, Name);
4566                         }
4567
4568                         if (fb != null) {
4569                                 IFixedExpression fe = InstanceExpression as IFixedExpression;
4570                                 if (!ec.HasSet (ResolveContext.Options.FixedInitializerScope) && (fe == null || !fe.IsFixed)) {
4571                                         ec.Report.Error (1666, loc, "You cannot use fixed size buffers contained in unfixed expressions. Try using the fixed statement");
4572                                 }
4573
4574                                 if (InstanceExpression.eclass != ExprClass.Variable) {
4575                                         ec.Report.SymbolRelatedToPreviousError (spec);
4576                                         ec.Report.Error (1708, loc, "`{0}': Fixed size buffers can only be accessed through locals or fields",
4577                                                 TypeManager.GetFullNameSignature (spec));
4578                                 } else if (var != null && var.IsHoisted) {
4579                                         AnonymousMethodExpression.Error_AddressOfCapturedVar (ec, var, loc);
4580                                 }
4581
4582                                 return new FixedBufferPtr (this, fb.ElementType, loc).Resolve (ec);
4583                         }
4584
4585                         eclass = ExprClass.Variable;
4586
4587                         // If the instance expression is a local variable or parameter.
4588                         if (var == null || var.VariableInfo == null)
4589                                 return this;
4590
4591                         VariableInfo vi = var.VariableInfo;
4592                         if (!vi.IsFieldAssigned (ec, Name, loc))
4593                                 return null;
4594
4595                         variable_info = vi.GetSubStruct (Name);
4596                         return this;
4597                 }
4598
4599                 static readonly int [] codes = {
4600                         191,    // instance, write access
4601                         192,    // instance, out access
4602                         198,    // static, write access
4603                         199,    // static, out access
4604                         1648,   // member of value instance, write access
4605                         1649,   // member of value instance, out access
4606                         1650,   // member of value static, write access
4607                         1651    // member of value static, out access
4608                 };
4609
4610                 static readonly string [] msgs = {
4611                         /*0191*/ "A readonly field `{0}' cannot be assigned to (except in a constructor or a variable initializer)",
4612                         /*0192*/ "A readonly field `{0}' cannot be passed ref or out (except in a constructor)",
4613                         /*0198*/ "A static readonly field `{0}' cannot be assigned to (except in a static constructor or a variable initializer)",
4614                         /*0199*/ "A static readonly field `{0}' cannot be passed ref or out (except in a static constructor)",
4615                         /*1648*/ "Members of readonly field `{0}' cannot be modified (except in a constructor or a variable initializer)",
4616                         /*1649*/ "Members of readonly field `{0}' cannot be passed ref or out (except in a constructor)",
4617                         /*1650*/ "Fields of static readonly field `{0}' cannot be assigned to (except in a static constructor or a variable initializer)",
4618                         /*1651*/ "Fields of static readonly field `{0}' cannot be passed ref or out (except in a static constructor)"
4619                 };
4620
4621                 // The return value is always null.  Returning a value simplifies calling code.
4622                 Expression Report_AssignToReadonly (ResolveContext ec, Expression right_side)
4623                 {
4624                         int i = 0;
4625                         if (right_side == EmptyExpression.OutAccess.Instance || right_side == EmptyExpression.LValueMemberOutAccess)
4626                                 i += 1;
4627                         if (IsStatic)
4628                                 i += 2;
4629                         if (right_side == EmptyExpression.LValueMemberAccess || right_side == EmptyExpression.LValueMemberOutAccess)
4630                                 i += 4;
4631                         ec.Report.Error (codes [i], loc, msgs [i], GetSignatureForError ());
4632
4633                         return null;
4634                 }
4635
4636                 override public Expression DoResolveLValue (ResolveContext ec, Expression right_side)
4637                 {
4638                         bool lvalue_instance = IsInstance && spec.DeclaringType.IsStruct;
4639                         bool out_access = right_side == EmptyExpression.OutAccess.Instance || right_side == EmptyExpression.LValueMemberOutAccess;
4640
4641                         Expression e = DoResolve (ec, lvalue_instance, out_access);
4642
4643                         if (e == null)
4644                                 return null;
4645
4646                         spec.MemberDefinition.SetIsAssigned ();
4647
4648                         if ((right_side == EmptyExpression.UnaryAddress || right_side == EmptyExpression.OutAccess.Instance) &&
4649                                         (spec.Modifiers & Modifiers.VOLATILE) != 0) {
4650                                 ec.Report.Warning (420, 1, loc,
4651                                         "`{0}': A volatile field references will not be treated as volatile",
4652                                         spec.GetSignatureForError ());
4653                         }
4654
4655                         if (spec.IsReadOnly) {
4656                                 // InitOnly fields can only be assigned in constructors or initializers
4657                                 if (!ec.HasAny (ResolveContext.Options.FieldInitializerScope | ResolveContext.Options.ConstructorScope))
4658                                         return Report_AssignToReadonly (ec, right_side);
4659
4660                                 if (ec.HasSet (ResolveContext.Options.ConstructorScope)) {
4661
4662                                         // InitOnly fields cannot be assigned-to in a different constructor from their declaring type
4663                                         if (ec.CurrentMemberDefinition.Parent.Definition != spec.DeclaringType.GetDefinition ())
4664                                                 return Report_AssignToReadonly (ec, right_side);
4665                                         // static InitOnly fields cannot be assigned-to in an instance constructor
4666                                         if (IsStatic && !ec.IsStatic)
4667                                                 return Report_AssignToReadonly (ec, right_side);
4668                                         // instance constructors can't modify InitOnly fields of other instances of the same type
4669                                         if (!IsStatic && !(InstanceExpression is This))
4670                                                 return Report_AssignToReadonly (ec, right_side);
4671                                 }
4672                         }
4673
4674                         if (right_side == EmptyExpression.OutAccess.Instance &&
4675                                 !IsStatic && !(InstanceExpression is This) && TypeManager.mbr_type != null && TypeSpec.IsBaseClass (spec.DeclaringType, TypeManager.mbr_type, false)) {
4676                                 ec.Report.SymbolRelatedToPreviousError (spec.DeclaringType);
4677                                 ec.Report.Warning (197, 1, loc,
4678                                                 "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",
4679                                                 GetSignatureForError ());
4680                         }
4681
4682                         eclass = ExprClass.Variable;
4683                         return this;
4684                 }
4685
4686                 public override int GetHashCode ()
4687                 {
4688                         return spec.GetHashCode ();
4689                 }
4690
4691                 public bool IsFixed {
4692                         get {
4693                                 //
4694                                 // A variable of the form V.I is fixed when V is a fixed variable of a struct type
4695                                 //
4696                                 IVariableReference variable = InstanceExpression as IVariableReference;
4697                                 if (variable != null)
4698                                         return InstanceExpression.Type.IsStruct && variable.IsFixed;
4699
4700                                 IFixedExpression fe = InstanceExpression as IFixedExpression;
4701                                 return fe != null && fe.IsFixed;
4702                         }
4703                 }
4704
4705                 public override bool Equals (object obj)
4706                 {
4707                         FieldExpr fe = obj as FieldExpr;
4708                         if (fe == null)
4709                                 return false;
4710
4711                         if (spec != fe.spec)
4712                                 return false;
4713
4714                         if (InstanceExpression == null || fe.InstanceExpression == null)
4715                                 return true;
4716
4717                         return InstanceExpression.Equals (fe.InstanceExpression);
4718                 }
4719
4720                 public void Emit (EmitContext ec, bool leave_copy)
4721                 {
4722                         bool is_volatile = false;
4723
4724                         if ((spec.Modifiers & Modifiers.VOLATILE) != 0)
4725                                 is_volatile = true;
4726
4727                         spec.MemberDefinition.SetIsUsed ();
4728
4729                         if (IsStatic){
4730                                 if (is_volatile)
4731                                         ec.Emit (OpCodes.Volatile);
4732
4733                                 ec.Emit (OpCodes.Ldsfld, spec);
4734                         } else {
4735                                 if (!prepared)
4736                                         EmitInstance (ec, false);
4737
4738                                 // Optimization for build-in types
4739                                 if (TypeManager.IsStruct (type) && type == ec.MemberContext.CurrentType && InstanceExpression.Type == type) {
4740                                         ec.EmitLoadFromPtr (type);
4741                                 } else {
4742                                         var ff = spec as FixedFieldSpec;
4743                                         if (ff != null) {
4744                                                 ec.Emit (OpCodes.Ldflda, spec);
4745                                                 ec.Emit (OpCodes.Ldflda, ff.Element);
4746                                         } else {
4747                                                 if (is_volatile)
4748                                                         ec.Emit (OpCodes.Volatile);
4749
4750                                                 ec.Emit (OpCodes.Ldfld, spec);
4751                                         }
4752                                 }
4753                         }
4754
4755                         if (leave_copy) {
4756                                 ec.Emit (OpCodes.Dup);
4757                                 if (!IsStatic) {
4758                                         temp = new LocalTemporary (this.Type);
4759                                         temp.Store (ec);
4760                                 }
4761                         }
4762                 }
4763
4764                 public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool prepare_for_load)
4765                 {
4766                         prepared = prepare_for_load;
4767                         if (IsInstance)
4768                                 EmitInstance (ec, prepared);
4769
4770                         source.Emit (ec);
4771                         if (leave_copy) {
4772                                 ec.Emit (OpCodes.Dup);
4773                                 if (!IsStatic) {
4774                                         temp = new LocalTemporary (this.Type);
4775                                         temp.Store (ec);
4776                                 }
4777                         }
4778
4779                         if ((spec.Modifiers & Modifiers.VOLATILE) != 0)
4780                                 ec.Emit (OpCodes.Volatile);
4781
4782                         spec.MemberDefinition.SetIsAssigned ();
4783
4784                         if (IsStatic)
4785                                 ec.Emit (OpCodes.Stsfld, spec);
4786                         else
4787                                 ec.Emit (OpCodes.Stfld, spec);
4788
4789                         if (temp != null) {
4790                                 temp.Emit (ec);
4791                                 temp.Release (ec);
4792                                 temp = null;
4793                         }
4794                 }
4795
4796                 public override void Emit (EmitContext ec)
4797                 {
4798                         Emit (ec, false);
4799                 }
4800
4801                 public override void EmitSideEffect (EmitContext ec)
4802                 {
4803                         bool is_volatile = (spec.Modifiers & Modifiers.VOLATILE) != 0;
4804
4805                         if (is_volatile) // || is_marshal_by_ref ())
4806                                 base.EmitSideEffect (ec);
4807                 }
4808
4809                 public void AddressOf (EmitContext ec, AddressOp mode)
4810                 {
4811                         if ((mode & AddressOp.Store) != 0)
4812                                 spec.MemberDefinition.SetIsAssigned ();
4813                         if ((mode & AddressOp.Load) != 0)
4814                                 spec.MemberDefinition.SetIsUsed ();
4815
4816                         //
4817                         // Handle initonly fields specially: make a copy and then
4818                         // get the address of the copy.
4819                         //
4820                         bool need_copy;
4821                         if (spec.IsReadOnly){
4822                                 need_copy = true;
4823                                 if (ec.HasSet (EmitContext.Options.ConstructorScope)){
4824                                         if (IsStatic){
4825                                                 if (ec.IsStatic)
4826                                                         need_copy = false;
4827                                         } else
4828                                                 need_copy = false;
4829                                 }
4830                         } else
4831                                 need_copy = false;
4832
4833                         if (need_copy){
4834                                 LocalBuilder local;
4835                                 Emit (ec);
4836                                 local = ec.DeclareLocal (type, false);
4837                                 ec.Emit (OpCodes.Stloc, local);
4838                                 ec.Emit (OpCodes.Ldloca, local);
4839                                 return;
4840                         }
4841
4842
4843                         if (IsStatic){
4844                                 ec.Emit (OpCodes.Ldsflda, spec);
4845                         } else {
4846                                 if (!prepared)
4847                                         EmitInstance (ec, false);
4848                                 ec.Emit (OpCodes.Ldflda, spec);
4849                         }
4850                 }
4851
4852                 public SLE.Expression MakeAssignExpression (BuilderContext ctx, Expression source)
4853                 {
4854                         return MakeExpression (ctx);
4855                 }
4856
4857                 public override SLE.Expression MakeExpression (BuilderContext ctx)
4858                 {
4859                         return SLE.Expression.Field (InstanceExpression.MakeExpression (ctx), spec.GetMetaInfo ());
4860                 }
4861
4862                 public override void SetTypeArguments (ResolveContext ec, TypeArguments ta)
4863                 {
4864                         Error_TypeArgumentsCannotBeUsed (ec.Report, "field", GetSignatureForError (), loc);
4865                 }
4866         }
4867
4868
4869         /// <summary>
4870         ///   Expression that evaluates to a Property.  The Assign class
4871         ///   might set the `Value' expression if we are in an assignment.
4872         ///
4873         ///   This is not an LValue because we need to re-write the expression, we
4874         ///   can not take data from the stack and store it.
4875         /// </summary>
4876         class PropertyExpr : PropertyOrIndexerExpr<PropertySpec>
4877         {
4878                 public PropertyExpr (PropertySpec spec, Location l)
4879                         : base (l)
4880                 {
4881                         best_candidate = spec;
4882                         type = spec.MemberType;
4883                 }
4884
4885                 #region Properties
4886
4887                 protected override TypeSpec DeclaringType {
4888                         get {
4889                                 return best_candidate.DeclaringType;
4890                         }
4891                 }
4892
4893                 public override string Name {
4894                         get {
4895                                 return best_candidate.Name;
4896                         }
4897                 }
4898
4899                 public override bool IsInstance {
4900                         get {
4901                                 return !IsStatic;
4902                         }
4903                 }
4904
4905                 public override bool IsStatic {
4906                         get {
4907                                 return best_candidate.IsStatic;
4908                         }
4909                 }
4910
4911                 public PropertySpec PropertyInfo {
4912                         get {
4913                                 return best_candidate;
4914                         }
4915                 }
4916
4917                 #endregion
4918
4919                 public override Expression CreateExpressionTree (ResolveContext ec)
4920                 {
4921                         Arguments args;
4922                         if (IsSingleDimensionalArrayLength ()) {
4923                                 args = new Arguments (1);
4924                                 args.Add (new Argument (InstanceExpression.CreateExpressionTree (ec)));
4925                                 return CreateExpressionFactoryCall (ec, "ArrayLength", args);
4926                         }
4927
4928                         args = new Arguments (2);
4929                         if (InstanceExpression == null)
4930                                 args.Add (new Argument (new NullLiteral (loc)));
4931                         else
4932                                 args.Add (new Argument (InstanceExpression.CreateExpressionTree (ec)));
4933                         args.Add (new Argument (new TypeOfMethod (Getter, loc)));
4934                         return CreateExpressionFactoryCall (ec, "Property", args);
4935                 }
4936
4937                 public Expression CreateSetterTypeOfExpression ()
4938                 {
4939                         return new TypeOfMethod (Setter, loc);
4940                 }
4941
4942                 public override string GetSignatureForError ()
4943                 {
4944                         return best_candidate.GetSignatureForError ();
4945                 }
4946
4947                 public override SLE.Expression MakeAssignExpression (BuilderContext ctx, Expression source)
4948                 {
4949                         return SLE.Expression.Property (InstanceExpression.MakeExpression (ctx), (MethodInfo) Setter.GetMetaInfo ());
4950                 }
4951
4952                 public override SLE.Expression MakeExpression (BuilderContext ctx)
4953                 {
4954                         return SLE.Expression.Property (InstanceExpression.MakeExpression (ctx), (MethodInfo) Getter.GetMetaInfo ());
4955                 }
4956
4957                 void Error_PropertyNotValid (ResolveContext ec)
4958                 {
4959                         ec.Report.SymbolRelatedToPreviousError (best_candidate);
4960                         ec.Report.Error (1546, loc, "Property or event `{0}' is not supported by the C# language",
4961                                 GetSignatureForError ());
4962                 }
4963
4964                 bool IsSingleDimensionalArrayLength ()
4965                 {
4966                         if (best_candidate.DeclaringType != TypeManager.array_type || !best_candidate.HasGet || Name != "Length")
4967                                 return false;
4968
4969                         ArrayContainer ac = InstanceExpression.Type as ArrayContainer;
4970                         return ac != null && ac.Rank == 1;
4971                 }
4972
4973                 public override void Emit (EmitContext ec, bool leave_copy)
4974                 {
4975                         //
4976                         // Special case: length of single dimension array property is turned into ldlen
4977                         //
4978                         if (IsSingleDimensionalArrayLength ()) {
4979                                 if (!prepared)
4980                                         EmitInstance (ec, false);
4981                                 ec.Emit (OpCodes.Ldlen);
4982                                 ec.Emit (OpCodes.Conv_I4);
4983                                 return;
4984                         }
4985
4986                         Invocation.EmitCall (ec, InstanceExpression, Getter, null, loc, prepared, false);
4987
4988                         if (leave_copy) {
4989                                 ec.Emit (OpCodes.Dup);
4990                                 if (!IsStatic) {
4991                                         temp = new LocalTemporary (this.Type);
4992                                         temp.Store (ec);
4993                                 }
4994                         }
4995                 }
4996
4997                 public override void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool prepare_for_load)
4998                 {
4999                         Expression my_source = source;
5000
5001                         if (prepare_for_load) {
5002                                 prepared = true;
5003                                 source.Emit (ec);
5004
5005                                 if (leave_copy) {
5006                                         ec.Emit (OpCodes.Dup);
5007                                         if (!IsStatic) {
5008                                                 temp = new LocalTemporary (this.Type);
5009                                                 temp.Store (ec);
5010                                         }
5011                                 }
5012                         } else if (leave_copy) {
5013                                 source.Emit (ec);
5014                                 temp = new LocalTemporary (this.Type);
5015                                 temp.Store (ec);
5016                                 my_source = temp;
5017                         }
5018
5019                         Arguments args = new Arguments (1);
5020                         args.Add (new Argument (my_source));
5021
5022                         Invocation.EmitCall (ec, InstanceExpression, Setter, args, loc, false, prepared);
5023
5024                         if (temp != null) {
5025                                 temp.Emit (ec);
5026                                 temp.Release (ec);
5027                         }
5028                 }
5029
5030                 protected override Expression OverloadResolve (ResolveContext rc, Expression right_side)
5031                 {
5032                         eclass = ExprClass.PropertyAccess;
5033
5034                         if (best_candidate.IsNotRealProperty) {
5035                                 Error_PropertyNotValid (rc);
5036                         }
5037
5038                         if (ResolveInstanceExpression (rc)) {
5039                                 if (right_side != null && best_candidate.DeclaringType.IsStruct)
5040                                         InstanceExpression.DoResolveLValue (rc, EmptyExpression.LValueMemberAccess);
5041                         }
5042
5043                         DoBestMemberChecks (rc, best_candidate);
5044                         return this;
5045                 }
5046
5047                 public override void SetTypeArguments (ResolveContext ec, TypeArguments ta)
5048                 {
5049                         Error_TypeArgumentsCannotBeUsed (ec.Report, "property", GetSignatureForError (), loc);
5050                 }
5051         }
5052
5053         abstract class PropertyOrIndexerExpr<T> : MemberExpr, IDynamicAssign where T : PropertySpec
5054         {
5055                 // getter and setter can be different for base calls
5056                 MethodSpec getter, setter;
5057                 protected T best_candidate;
5058
5059                 protected LocalTemporary temp;
5060                 protected bool prepared;
5061
5062                 protected PropertyOrIndexerExpr (Location l)
5063                 {
5064                         loc = l;
5065                 }
5066
5067                 #region Properties
5068
5069                 public MethodSpec Getter {
5070                         get {
5071                                 return getter;
5072                         }
5073                         set {
5074                                 getter = value;
5075                         }
5076                 }
5077
5078                 public MethodSpec Setter {
5079                         get {
5080                                 return setter;
5081                         }
5082                         set {
5083                                 setter = value;
5084                         }
5085                 }
5086
5087                 #endregion
5088
5089                 protected override Expression DoResolve (ResolveContext ec)
5090                 {
5091                         if (eclass == ExprClass.Unresolved) {
5092                                 var expr = OverloadResolve (ec, null);
5093                                 if (expr == null)
5094                                         return null;
5095
5096                                 if (InstanceExpression != null)
5097                                         InstanceExpression.CheckMarshalByRefAccess (ec);
5098
5099                                 if (expr != this)
5100                                         return expr.Resolve (ec);
5101                         }
5102
5103                         if (!ResolveGetter (ec))
5104                                 return null;
5105
5106                         return this;
5107                 }
5108
5109                 public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
5110                 {
5111                         if (right_side == EmptyExpression.OutAccess.Instance) {
5112                                 // TODO: best_candidate can be null at this point
5113                                 INamedBlockVariable variable = null;
5114                                 if (best_candidate != null && ec.CurrentBlock.ParametersBlock.TopBlock.GetLocalName (best_candidate.Name, ec.CurrentBlock, ref variable) && variable is Linq.RangeVariable) {
5115                                         ec.Report.Error (1939, loc, "A range variable `{0}' may not be passes as `ref' or `out' parameter",
5116                                                 best_candidate.Name);
5117                                 } else {
5118                                         right_side.DoResolveLValue (ec, this);
5119                                 }
5120                                 return null;
5121                         }
5122
5123                         // if the property/indexer returns a value type, and we try to set a field in it
5124                         if (right_side == EmptyExpression.LValueMemberAccess || right_side == EmptyExpression.LValueMemberOutAccess) {
5125                                 Error_CannotModifyIntermediateExpressionValue (ec);
5126                         }
5127
5128                         if (eclass == ExprClass.Unresolved) {
5129                                 var expr = OverloadResolve (ec, right_side);
5130                                 if (expr == null)
5131                                         return null;
5132
5133                                 if (expr != this)
5134                                         return expr.ResolveLValue (ec, right_side);
5135                         }
5136
5137                         if (!ResolveSetter (ec))
5138                                 return null;
5139
5140                         return this;
5141                 }
5142
5143                 //
5144                 // Implements the IAssignMethod interface for assignments
5145                 //
5146                 public abstract void Emit (EmitContext ec, bool leave_copy);
5147                 public abstract void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool prepare_for_load);
5148
5149                 public override void Emit (EmitContext ec)
5150                 {
5151                         Emit (ec, false);
5152                 }
5153
5154                 public abstract SLE.Expression MakeAssignExpression (BuilderContext ctx, Expression source);
5155
5156                 protected abstract Expression OverloadResolve (ResolveContext rc, Expression right_side);
5157
5158                 bool ResolveGetter (ResolveContext rc)
5159                 {
5160                         if (!best_candidate.HasGet) {
5161                                 if (InstanceExpression != EmptyExpression.Null) {
5162                                         rc.Report.SymbolRelatedToPreviousError (best_candidate);
5163                                         rc.Report.Error (154, loc, "The property or indexer `{0}' cannot be used in this context because it lacks the `get' accessor",
5164                                                 best_candidate.GetSignatureForError ());
5165                                         return false;
5166                                 }
5167                         } else if (!best_candidate.Get.IsAccessible (rc.CurrentType)) {
5168                                 if (best_candidate.HasDifferentAccessibility) {
5169                                         rc.Report.SymbolRelatedToPreviousError (best_candidate.Get);
5170                                         rc.Report.Error (271, loc, "The property or indexer `{0}' cannot be used in this context because the get accessor is inaccessible",
5171                                                 TypeManager.CSharpSignature (best_candidate));
5172                                 } else {
5173                                         rc.Report.SymbolRelatedToPreviousError (best_candidate.Get);
5174                                         ErrorIsInaccesible (rc, best_candidate.Get.GetSignatureForError (), loc);
5175                                 }
5176                         }
5177
5178                         if (best_candidate.HasDifferentAccessibility) {
5179                                 CheckProtectedMemberAccess (rc, best_candidate.Get);
5180                         }
5181
5182                         getter = CandidateToBaseOverride (rc, best_candidate.Get);
5183                         return true;
5184                 }
5185
5186                 bool ResolveSetter (ResolveContext rc)
5187                 {
5188                         if (!best_candidate.HasSet) {
5189                                 rc.Report.Error (200, loc, "Property or indexer `{0}' cannot be assigned to (it is read-only)",
5190                                         GetSignatureForError ());
5191                                 return false;
5192                         }
5193
5194                         if (!best_candidate.Set.IsAccessible (rc.CurrentType)) {
5195                                 if (best_candidate.HasDifferentAccessibility) {
5196                                         rc.Report.SymbolRelatedToPreviousError (best_candidate.Set);
5197                                         rc.Report.Error (272, loc, "The property or indexer `{0}' cannot be used in this context because the set accessor is inaccessible",
5198                                                 GetSignatureForError ());
5199                                 } else {
5200                                         rc.Report.SymbolRelatedToPreviousError (best_candidate.Set);
5201                                         ErrorIsInaccesible (rc, best_candidate.Set.GetSignatureForError (), loc);
5202                                 }
5203                         }
5204
5205                         if (best_candidate.HasDifferentAccessibility)
5206                                 CheckProtectedMemberAccess (rc, best_candidate.Set);
5207
5208                         setter = CandidateToBaseOverride (rc, best_candidate.Set);
5209                         return true;
5210                 }
5211         }
5212
5213         /// <summary>
5214         ///   Fully resolved expression that evaluates to an Event
5215         /// </summary>
5216         public class EventExpr : MemberExpr, IAssignMethod
5217         {
5218                 readonly EventSpec spec;
5219                 MethodSpec op;
5220
5221                 public EventExpr (EventSpec spec, Location loc)
5222                 {
5223                         this.spec = spec;
5224                         this.loc = loc;
5225                 }
5226
5227                 #region Properties
5228
5229                 protected override TypeSpec DeclaringType {
5230                         get {
5231                                 return spec.DeclaringType;
5232                         }
5233                 }
5234
5235                 public override string Name {
5236                         get {
5237                                 return spec.Name;
5238                         }
5239                 }
5240
5241                 public override bool IsInstance {
5242                         get {
5243                                 return !spec.IsStatic;
5244                         }
5245                 }
5246
5247                 public override bool IsStatic {
5248                         get {
5249                                 return spec.IsStatic;
5250                         }
5251                 }
5252
5253                 public MethodSpec Operator {
5254                         get {
5255                                 return op;
5256                         }
5257                 }
5258
5259                 #endregion
5260
5261                 public override MemberExpr ResolveMemberAccess (ResolveContext ec, Expression left, SimpleName original)
5262                 {
5263                         //
5264                         // If the event is local to this class, we transform ourselves into a FieldExpr
5265                         //
5266
5267                         if (spec.DeclaringType == ec.CurrentType ||
5268                             TypeManager.IsNestedChildOf(ec.CurrentType, spec.DeclaringType)) {
5269
5270                                 if (spec.BackingField != null) {
5271                                         spec.MemberDefinition.SetIsUsed ();
5272
5273                                         if (!ec.IsObsolete) {
5274                                                 ObsoleteAttribute oa = spec.GetAttributeObsolete ();
5275                                                 if (oa != null)
5276                                                         AttributeTester.Report_ObsoleteMessage (oa, spec.GetSignatureForError (), loc, ec.Report);
5277                                         }
5278
5279                                         if ((spec.Modifiers & (Modifiers.ABSTRACT | Modifiers.EXTERN)) != 0 && !ec.HasSet (ResolveContext.Options.CompoundAssignmentScope))
5280                                                 Error_AssignmentEventOnly (ec);
5281
5282                                         FieldExpr ml = new FieldExpr (spec.BackingField, loc);
5283
5284                                         InstanceExpression = null;
5285
5286                                         return ml.ResolveMemberAccess (ec, left, original);
5287                                 }
5288                         }
5289
5290                         if (!ec.HasSet (ResolveContext.Options.CompoundAssignmentScope))
5291                                 Error_AssignmentEventOnly (ec);
5292
5293                         return base.ResolveMemberAccess (ec, left, original);
5294                 }
5295
5296                 public override Expression CreateExpressionTree (ResolveContext ec)
5297                 {
5298                         throw new NotSupportedException ("ET");
5299                 }
5300
5301                 public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
5302                 {
5303                         if (right_side == EmptyExpression.EventAddition) {
5304                                 op = spec.AccessorAdd;
5305                         } else if (right_side == EmptyExpression.EventSubtraction) {
5306                                 op = spec.AccessorRemove;
5307                         }
5308
5309                         if (op == null) {
5310                                 Error_AssignmentEventOnly (ec);
5311                                 return null;
5312                         }
5313
5314                         op = CandidateToBaseOverride (ec, op);
5315                         return this;
5316                 }
5317
5318                 protected override Expression DoResolve (ResolveContext ec)
5319                 {
5320                         eclass = ExprClass.EventAccess;
5321                         type = spec.MemberType;
5322
5323                         ResolveInstanceExpression (ec);
5324
5325                         if (!ec.HasSet (ResolveContext.Options.CompoundAssignmentScope)) {
5326                                 Error_CannotAssign (ec);
5327                         }
5328
5329                         DoBestMemberChecks (ec, spec);
5330                         return this;
5331                 }
5332
5333                 public override void Emit (EmitContext ec)
5334                 {
5335                         throw new NotSupportedException ();
5336                         //Error_CannotAssign ();
5337                 }
5338
5339                 #region IAssignMethod Members
5340
5341                 public void Emit (EmitContext ec, bool leave_copy)
5342                 {
5343                         throw new NotImplementedException ();
5344                 }
5345
5346                 public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool prepare_for_load)
5347                 {
5348                         if (leave_copy || !prepare_for_load)
5349                                 throw new NotImplementedException ("EventExpr::EmitAssign");
5350
5351                         Arguments args = new Arguments (1);
5352                         args.Add (new Argument (source));
5353                         Invocation.EmitCall (ec, InstanceExpression, op, args, loc);
5354                 }
5355
5356                 #endregion
5357
5358                 void Error_AssignmentEventOnly (ResolveContext ec)
5359                 {
5360                         ec.Report.Error (79, loc, "The event `{0}' can only appear on the left hand side of `+=' or `-=' operator",
5361                                 GetSignatureForError ());
5362                 }
5363
5364                 public void Error_CannotAssign (ResolveContext ec)
5365                 {
5366                         ec.Report.Error (70, loc,
5367                                 "The event `{0}' can only appear on the left hand side of += or -= when used outside of the type `{1}'",
5368                                 GetSignatureForError (), TypeManager.CSharpName (spec.DeclaringType));
5369                 }
5370
5371                 protected override void Error_CannotCallAbstractBase (ResolveContext rc, string name)
5372                 {
5373                         name = name.Substring (0, name.LastIndexOf ('.'));
5374                         base.Error_CannotCallAbstractBase (rc, name);
5375                 }
5376
5377                 public override string GetSignatureForError ()
5378                 {
5379                         return TypeManager.CSharpSignature (spec);
5380                 }
5381
5382                 public override void SetTypeArguments (ResolveContext ec, TypeArguments ta)
5383                 {
5384                         Error_TypeArgumentsCannotBeUsed (ec.Report, "event", GetSignatureForError (), loc);
5385                 }
5386         }
5387
5388         public class TemporaryVariableReference : VariableReference
5389         {
5390                 public class Declarator : Statement
5391                 {
5392                         TemporaryVariableReference variable;
5393
5394                         public Declarator (TemporaryVariableReference variable)
5395                         {
5396                                 this.variable = variable;
5397                                 loc = variable.loc;
5398                         }
5399
5400                         protected override void DoEmit (EmitContext ec)
5401                         {
5402                                 variable.li.CreateBuilder (ec);
5403                         }
5404
5405                         protected override void CloneTo (CloneContext clonectx, Statement target)
5406                         {
5407                                 // Nothing
5408                         }
5409                 }
5410
5411                 LocalVariable li;
5412
5413                 public TemporaryVariableReference (LocalVariable li, Location loc)
5414                 {
5415                         this.li = li;
5416                         this.type = li.Type;
5417                         this.loc = loc;
5418                 }
5419
5420                 public LocalVariable LocalInfo {
5421                     get {
5422                         return li;
5423                     }
5424                 }
5425
5426                 public static TemporaryVariableReference Create (TypeSpec type, Block block, Location loc)
5427                 {
5428                         var li = LocalVariable.CreateCompilerGenerated (type, block, loc);
5429                         return new TemporaryVariableReference (li, loc);
5430                 }
5431
5432                 public override Expression CreateExpressionTree (ResolveContext ec)
5433                 {
5434                         throw new NotSupportedException ("ET");
5435                 }
5436
5437                 protected override Expression DoResolve (ResolveContext ec)
5438                 {
5439                         eclass = ExprClass.Variable;
5440
5441                         //
5442                         // Don't capture temporary variables except when using
5443                         // iterator redirection
5444                         //
5445                         if (ec.CurrentAnonymousMethod != null && ec.CurrentAnonymousMethod.IsIterator && ec.IsVariableCapturingRequired) {
5446                                 AnonymousMethodStorey storey = li.Block.Explicit.CreateAnonymousMethodStorey (ec);
5447                                 storey.CaptureLocalVariable (ec, li);
5448                         }
5449
5450                         return this;
5451                 }
5452
5453                 public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
5454                 {
5455                         return Resolve (ec);
5456                 }
5457
5458                 public override void Emit (EmitContext ec)
5459                 {
5460                         li.CreateBuilder (ec);
5461
5462                         Emit (ec, false);
5463                 }
5464
5465                 public void EmitAssign (EmitContext ec, Expression source)
5466                 {
5467                         li.CreateBuilder (ec);
5468
5469                         EmitAssign (ec, source, false, false);
5470                 }
5471
5472                 public override HoistedVariable GetHoistedVariable (AnonymousExpression ae)
5473                 {
5474                         return li.HoistedVariant;
5475                 }
5476
5477                 public override bool IsFixed {
5478                         get { return true; }
5479                 }
5480
5481                 public override bool IsRef {
5482                         get { return false; }
5483                 }
5484
5485                 public override string Name {
5486                         get { throw new NotImplementedException (); }
5487                 }
5488
5489                 public override void SetHasAddressTaken ()
5490                 {
5491                         throw new NotImplementedException ();
5492                 }
5493
5494                 protected override ILocalVariable Variable {
5495                         get { return li; }
5496                 }
5497
5498                 public override VariableInfo VariableInfo {
5499                         get { throw new NotImplementedException (); }
5500                 }
5501         }
5502
5503         ///
5504         /// Handles `var' contextual keyword; var becomes a keyword only
5505         /// if no type called var exists in a variable scope
5506         ///
5507         class VarExpr : SimpleName
5508         {
5509                 public VarExpr (Location loc)
5510                         : base ("var", loc)
5511                 {
5512                 }
5513
5514                 public bool InferType (ResolveContext ec, Expression right_side)
5515                 {
5516                         if (type != null)
5517                                 throw new InternalErrorException ("An implicitly typed local variable could not be redefined");
5518
5519                         type = right_side.Type;
5520                         if (type == InternalType.Null || type == TypeManager.void_type || type == InternalType.AnonymousMethod || type == InternalType.MethodGroup) {
5521                                 ec.Report.Error (815, loc,
5522                                         "An implicitly typed local variable declaration cannot be initialized with `{0}'",
5523                                         type.GetSignatureForError ());
5524                                 return false;
5525                         }
5526
5527                         eclass = ExprClass.Variable;
5528                         return true;
5529                 }
5530
5531                 protected override void Error_TypeOrNamespaceNotFound (IMemberContext ec)
5532                 {
5533                         if (RootContext.Version < LanguageVersion.V_3)
5534                                 base.Error_TypeOrNamespaceNotFound (ec);
5535                         else
5536                                 ec.Compiler.Report.Error (825, loc, "The contextual keyword `var' may only appear within a local variable declaration");
5537                 }
5538         }
5539 }