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 namespace Mono.CSharp {
  14         using System;
  15         using System.Collections;
  16         using System.Diagnostics;
  17         using System.Reflection;
  18         using System.Reflection.Emit;
  19         using System.Text;
  20
  21         /// <remarks>
  22         ///   The ExprClass class contains the is used to pass the
  23         ///   classification of an expression (value, variable, namespace,
  24         ///   type, method group, property access, event access, indexer access,
  25         ///   nothing).
  26         /// </remarks>
  27         public enum ExprClass : byte {
  28                 Invalid,
  29
  30                 Value,
  31                 Variable,
  32                 Namespace,
  33                 Type,
  34                 TypeParameter,
  35                 MethodGroup,
  36                 PropertyAccess,
  37                 EventAccess,
  38                 IndexerAccess,
  39                 Nothing,
  40         }
  41
  42         /// <remarks>
  43         ///   This is used to tell Resolve in which types of expressions we're
  44         ///   interested.
  45         /// </remarks>
  46         [Flags]
  47         public enum ResolveFlags {
  48                 // Returns Value, Variable, PropertyAccess, EventAccess or IndexerAccess.
  49                 VariableOrValue         = 1,
  50
  51                 // Returns a type expression.
  52                 Type                    = 1 << 1,
  53
  54                 // Returns a method group.
  55                 MethodGroup             = 1 << 2,
  56
  57                 TypeParameter   = 1 << 3,
  58
  59                 // Mask of all the expression class flags.
  60                 MaskExprClass = VariableOrValue | Type | MethodGroup | TypeParameter,
  61
  62                 // Disable control flow analysis while resolving the expression.
  63                 // This is used when resolving the instance expression of a field expression.
  64                 DisableFlowAnalysis     = 1 << 10,
  65
  66                 // Set if this is resolving the first part of a MemberAccess.
  67                 Intermediate            = 1 << 11,
  68
  69                 // Disable control flow analysis _of struct_ while resolving the expression.
  70                 // This is used when resolving the instance expression of a field expression.
  71                 DisableStructFlowAnalysis       = 1 << 12,
  72
  73         }
  74
  75         //
  76         // This is just as a hint to AddressOf of what will be done with the
  77         // address.
  78         [Flags]
  79         public enum AddressOp {
  80                 Store = 1,
  81                 Load  = 2,
  82                 LoadStore = 3
  83         };
  84
  85         /// <summary>
  86         ///   This interface is implemented by variables
  87         /// </summary>
  88         public interface IMemoryLocation {
  89                 /// <summary>
  90                 ///   The AddressOf method should generate code that loads
  91                 ///   the address of the object and leaves it on the stack.
  92                 ///
  93                 ///   The `mode' argument is used to notify the expression
  94                 ///   of whether this will be used to read from the address or
  95                 ///   write to the address.
  96                 ///
  97                 ///   This is just a hint that can be used to provide good error
  98                 ///   reporting, and should have no other side effects.
  99                 /// </summary>
 100                 void AddressOf (EmitContext ec, AddressOp mode);
 101         }
 102
 103         //
 104         // An expressions resolved as a direct variable reference
 105         //
 106         public interface IVariableReference {
 107                 bool IsFixedVariable { get; }
 108                 bool IsHoisted { get; }
 109                 string Name { get; }
 110                 VariableInfo VariableInfo { get; }
 111
 112                 void SetHasAddressTaken ();
 113         }
 114
 115         /// <remarks>
 116         ///   Base class for expressions
 117         /// </remarks>
 118         public abstract class Expression {
 119                 public ExprClass eclass;
 120                 protected Type type;
 121                 protected Location loc;
 122
 123                 public Type Type {
 124                         get { return type; }
 125                         set { type = value; }
 126                 }
 127
 128                 public virtual Location Location {
 129                         get { return loc; }
 130                 }
 131
 132                 /// <summary>
 133                 ///   Utility wrapper routine for Error, just to beautify the code
 134                 /// </summary>
 135                 public void Error (int error, string s)
 136                 {
 137                         Report.Error (error, loc, s);
 138                 }
 139
 140                 // Not nice but we have broken hierarchy.
 141                 public virtual void CheckMarshalByRefAccess (EmitContext ec)
 142                 {
 143                 }
 144
 145                 public virtual bool GetAttributableValue (EmitContext ec, Type value_type, out object value)
 146                 {
 147                         Attribute.Error_AttributeArgumentNotValid (loc);
 148                         value = null;
 149                         return false;
 150                 }
 151
 152                 public virtual string GetSignatureForError ()
 153                 {
 154                         return TypeManager.CSharpName (type);
 155                 }
 156
 157                 public static bool IsAccessorAccessible (Type invocation_type, MethodInfo mi, out bool must_do_cs1540_check)
 158                 {
 159                         MethodAttributes ma = mi.Attributes & MethodAttributes.MemberAccessMask;
 160
 161                         must_do_cs1540_check = false; // by default we do not check for this
 162
 163                         if (ma == MethodAttributes.Public)
 164                                 return true;
 165
 166                         //
 167                         // If only accessible to the current class or children
 168                         //
 169                         if (ma == MethodAttributes.Private)
 170                                 return TypeManager.IsPrivateAccessible (invocation_type, mi.DeclaringType) ||
 171                                         TypeManager.IsNestedChildOf (invocation_type, mi.DeclaringType);
 172
 173                         if (TypeManager.IsThisOrFriendAssembly (mi.DeclaringType.Assembly)) {
 174                                 if (ma == MethodAttributes.Assembly || ma == MethodAttributes.FamORAssem)
 175                                         return true;
 176                         } else {
 177                                 if (ma == MethodAttributes.Assembly || ma == MethodAttributes.FamANDAssem)
 178                                         return false;
 179                         }
 180
 181                         // Family and FamANDAssem require that we derive.
 182                         // FamORAssem requires that we derive if in different assemblies.
 183                         if (!TypeManager.IsNestedFamilyAccessible (invocation_type, mi.DeclaringType))
 184                                 return false;
 185
 186                         if (!TypeManager.IsNestedChildOf (invocation_type, mi.DeclaringType))
 187                                 must_do_cs1540_check = true;
 188
 189                         return true;
 190                 }
 191
 192                 public virtual bool IsNull {
 193                         get {
 194                                 return false;
 195                         }
 196                 }
 197
 198                 /// <summary>
 199                 ///   Performs semantic analysis on the Expression
 200                 /// </summary>
 201                 ///
 202                 /// <remarks>
 203                 ///   The Resolve method is invoked to perform the semantic analysis
 204                 ///   on the node.
 205                 ///
 206                 ///   The return value is an expression (it can be the
 207                 ///   same expression in some cases) or a new
 208                 ///   expression that better represents this node.
 209                 ///
 210                 ///   For example, optimizations of Unary (LiteralInt)
 211                 ///   would return a new LiteralInt with a negated
 212                 ///   value.
 213                 ///
 214                 ///   If there is an error during semantic analysis,
 215                 ///   then an error should be reported (using Report)
 216                 ///   and a null value should be returned.
 217                 ///
 218                 ///   There are two side effects expected from calling
 219                 ///   Resolve(): the the field variable "eclass" should
 220                 ///   be set to any value of the enumeration
 221                 ///   `ExprClass' and the type variable should be set
 222                 ///   to a valid type (this is the type of the
 223                 ///   expression).
 224                 /// </remarks>
 225                 public abstract Expression DoResolve (EmitContext ec);
 226
 227                 public virtual Expression DoResolveLValue (EmitContext ec, Expression right_side)
 228                 {
 229                         return null;
 230                 }
 231
 232                 //
 233                 // This is used if the expression should be resolved as a type or namespace name.
 234                 // the default implementation fails.
 235                 //
 236                 public virtual FullNamedExpression ResolveAsTypeStep (IResolveContext rc,  bool silent)
 237                 {
 238                         if (!silent) {
 239                                 Expression e = this;
 240                                 EmitContext ec = rc as EmitContext;
 241                                 if (ec != null)
 242                                         e = e.Resolve (ec);
 243                                 if (e != null)
 244                                         e.Error_UnexpectedKind (ResolveFlags.Type, loc);
 245                         }
 246                         return null;
 247                 }
 248
 249                 //
 250                 // C# 3.0 introduced contextual keywords (var) which behaves like a type if type with
 251                 // same name exists or as a keyword when no type was found
 252                 //
 253                 public virtual TypeExpr ResolveAsContextualType (IResolveContext rc, bool silent)
 254                 {
 255                         return ResolveAsTypeTerminal (rc, silent);
 256                 }
 257
 258                 //
 259                 // This is used to resolve the expression as a type, a null
 260                 // value will be returned if the expression is not a type
 261                 // reference
 262                 //
 263                 public virtual TypeExpr ResolveAsTypeTerminal (IResolveContext ec, bool silent)
 264                 {
 265                         TypeExpr te = ResolveAsBaseTerminal (ec, silent);
 266                         if (te == null)
 267                                 return null;
 268
 269                         if (!silent) { // && !(te is TypeParameterExpr)) {
 270                                 ObsoleteAttribute obsolete_attr = AttributeTester.GetObsoleteAttribute (te.Type);
 271                                 if (obsolete_attr != null && !ec.IsInObsoleteScope) {
 272                                         AttributeTester.Report_ObsoleteMessage (obsolete_attr, te.GetSignatureForError (), Location);
 273                                 }
 274                         }
 275
 276                         ConstructedType ct = te as ConstructedType;
 277                         if (ct != null) {
 278                                 // Skip constrains check for overrides and explicit implementations
 279                                 // TODO: they should use different overload
 280                                 GenericMethod gm = ec.GenericDeclContainer as GenericMethod;
 281                                 if (gm != null && ((gm.ModFlags & Modifiers.OVERRIDE) != 0 || gm.MemberName.Left != null)) {
 282                                         te.loc = loc;
 283                                         return te;
 284                                 }
 285
 286                                 // TODO: silent flag is ignored
 287                                 ct.CheckConstraints (ec);
 288                         }
 289
 290                         return te;
 291                 }
 292
 293                 public TypeExpr ResolveAsBaseTerminal (IResolveContext ec, bool silent)
 294                 {
 295                         int errors = Report.Errors;
 296
 297                         FullNamedExpression fne = ResolveAsTypeStep (ec, silent);
 298
 299                         if (fne == null)
 300                                 return null;
 301
 302                         TypeExpr te = fne as TypeExpr;
 303                         if (te == null) {
 304                                 if (!silent && errors == Report.Errors)
 305                                         fne.Error_UnexpectedKind (null, "type", loc);
 306                                 return null;
 307                         }
 308
 309                         if (!te.CheckAccessLevel (ec.GenericDeclContainer)) {
 310                                 Report.SymbolRelatedToPreviousError (te.Type);
 311                                 ErrorIsInaccesible (loc, TypeManager.CSharpName (te.Type));
 312                                 return null;
 313                         }
 314
 315                         te.loc = loc;
 316                         return te;
 317                 }
 318
 319                 public static void ErrorIsInaccesible (Location loc, string name)
 320                 {
 321                         Report.Error (122, loc, "`{0}' is inaccessible due to its protection level", name);
 322                 }
 323
 324                 protected static void Error_CannotAccessProtected (Location loc, MemberInfo m, Type qualifier, Type container)
 325                 {
 326                         Report.Error (1540, loc, "Cannot access protected member `{0}' via a qualifier of type `{1}'."
 327                                 + " The qualifier must be of type `{2}' or derived from it",
 328                                 TypeManager.GetFullNameSignature (m),
 329                                 TypeManager.CSharpName (qualifier),
 330                                 TypeManager.CSharpName (container));
 331
 332                 }
 333
 334                 public static void Error_InvalidExpressionStatement (Location loc)
 335                 {
 336                         Report.Error (201, loc, "Only assignment, call, increment, decrement, and new object " +
 337                                        "expressions can be used as a statement");
 338                 }
 339
 340                 public void Error_InvalidExpressionStatement ()
 341                 {
 342                         Error_InvalidExpressionStatement (loc);
 343                 }
 344
 345                 protected void Error_CannotAssign (string to, string roContext)
 346                 {
 347                         Report.Error (1656, loc, "Cannot assign to `{0}' because it is a `{1}'",
 348                                 to, roContext);
 349                 }
 350
 351                 public static void Error_VoidInvalidInTheContext (Location loc)
 352                 {
 353                         Report.Error (1547, loc, "Keyword `void' cannot be used in this context");
 354                 }
 355
 356                 public virtual void Error_ValueCannotBeConverted (EmitContext ec, Location loc, Type target, bool expl)
 357                 {
 358                         // The error was already reported as CS1660
 359                         if (type == TypeManager.anonymous_method_type)
 360                                 return;
 361
 362                         if (TypeManager.IsGenericParameter (Type) && TypeManager.IsGenericParameter (target) && type.Name == target.Name) {
 363 #if GMCS_SOURCE
 364                                 string sig1 = type.DeclaringMethod == null ?
 365                                         TypeManager.CSharpName (type.DeclaringType) :
 366                                         TypeManager.CSharpSignature (type.DeclaringMethod);
 367                                 string sig2 = target.DeclaringMethod == null ?
 368                                         TypeManager.CSharpName (target.DeclaringType) :
 369                                         TypeManager.CSharpSignature (target.DeclaringMethod);
 370                                 Report.ExtraInformation (loc,
 371                                         String.Format (
 372                                                 "The generic parameter `{0}' of `{1}' cannot be converted to the generic parameter `{0}' of `{2}' (in the previous ",
 373                                                 Type.Name, sig1, sig2));
 374 #endif
 375                         } else if (Type.FullName == target.FullName){
 376                                 Report.ExtraInformation (loc,
 377                                         String.Format (
 378                                         "The type `{0}' has two conflicting definitions, one comes from `{1}' and the other from `{2}' (in the previous ",
 379                                         Type.FullName, Type.Assembly.FullName, target.Assembly.FullName));
 380                         }
 381
 382                         if (expl) {
 383                                 Report.Error (30, loc, "Cannot convert type `{0}' to `{1}'",
 384                                         TypeManager.CSharpName (type), TypeManager.CSharpName (target));
 385                                 return;
 386                         }
 387
 388                         Report.DisableReporting ();
 389                         bool expl_exists = Convert.ExplicitConversion (ec, this, target, Location.Null) != null;
 390                         Report.EnableReporting ();
 391
 392                         if (expl_exists) {
 393                                 Report.Error (266, loc, "Cannot implicitly convert type `{0}' to `{1}'. " +
 394                                               "An explicit conversion exists (are you missing a cast?)",
 395                                         TypeManager.CSharpName (Type), TypeManager.CSharpName (target));
 396                                 return;
 397                         }
 398
 399                         Report.Error (29, loc, "Cannot implicitly convert type `{0}' to `{1}'",
 400                                 TypeManager.CSharpName (type),
 401                                 TypeManager.CSharpName (target));
 402                 }
 403
 404                 public virtual void Error_VariableIsUsedBeforeItIsDeclared (string name)
 405                 {
 406                         Report.Error (841, loc, "A local variable `{0}' cannot be used before it is declared", name);
 407                 }
 408
 409                 protected virtual void Error_TypeDoesNotContainDefinition (Type type, string name)
 410                 {
 411                         Error_TypeDoesNotContainDefinition (loc, type, name);
 412                 }
 413
 414                 public static void Error_TypeDoesNotContainDefinition (Location loc, Type type, string name)
 415                 {
 416                         Report.SymbolRelatedToPreviousError (type);
 417                         Report.Error (117, loc, "`{0}' does not contain a definition for `{1}'",
 418                                 TypeManager.CSharpName (type), name);
 419                 }
 420
 421                 protected static void Error_ValueAssignment (Location loc)
 422                 {
 423                         Report.Error (131, loc, "The left-hand side of an assignment must be a variable, a property or an indexer");
 424                 }
 425
 426                 ResolveFlags ExprClassToResolveFlags
 427                 {
 428                         get {
 429                                 switch (eclass) {
 430                                         case ExprClass.Type:
 431                                         case ExprClass.Namespace:
 432                                                 return ResolveFlags.Type;
 433
 434                                         case ExprClass.MethodGroup:
 435                                                 return ResolveFlags.MethodGroup;
 436
 437                                         case ExprClass.TypeParameter:
 438                                                 return ResolveFlags.TypeParameter;
 439
 440                                         case ExprClass.Value:
 441                                         case ExprClass.Variable:
 442                                         case ExprClass.PropertyAccess:
 443                                         case ExprClass.EventAccess:
 444                                         case ExprClass.IndexerAccess:
 445                                                 return ResolveFlags.VariableOrValue;
 446
 447                                         default:
 448                                                 throw new InternalErrorException (loc.ToString () + " " +  GetType () + " ExprClass is Invalid after resolve");
 449                                 }
 450                         }
 451                 }
 452
 453                 /// <summary>
 454                 ///   Resolves an expression and performs semantic analysis on it.
 455                 /// </summary>
 456                 ///
 457                 /// <remarks>
 458                 ///   Currently Resolve wraps DoResolve to perform sanity
 459                 ///   checking and assertion checking on what we expect from Resolve.
 460                 /// </remarks>
 461                 public Expression Resolve (EmitContext ec, ResolveFlags flags)
 462                 {
 463                         if ((flags & ResolveFlags.MaskExprClass) == ResolveFlags.Type)
 464                                 return ResolveAsTypeStep (ec, false);
 465
 466                         bool do_flow_analysis = ec.DoFlowAnalysis;
 467                         bool omit_struct_analysis = ec.OmitStructFlowAnalysis;
 468                         if ((flags & ResolveFlags.DisableFlowAnalysis) != 0)
 469                                 do_flow_analysis = false;
 470                         if ((flags & ResolveFlags.DisableStructFlowAnalysis) != 0)
 471                                 omit_struct_analysis = true;
 472
 473                         Expression e;
 474                         using (ec.WithFlowAnalysis (do_flow_analysis, omit_struct_analysis)) {
 475                                 if (this is SimpleName) {
 476                                         bool intermediate = (flags & ResolveFlags.Intermediate) == ResolveFlags.Intermediate;
 477                                         e = ((SimpleName) this).DoResolve (ec, intermediate);
 478                                 } else {
 479                                         e = DoResolve (ec);
 480                                 }
 481                         }
 482
 483                         if (e == null)
 484                                 return null;
 485
 486                         if ((flags & e.ExprClassToResolveFlags) == 0) {
 487                                 e.Error_UnexpectedKind (flags, loc);
 488                                 return null;
 489                         }
 490
 491                         if (e.type == null && !(e is Namespace)) {
 492                                 throw new Exception (
 493                                         "Expression " + e.GetType () +
 494                                         " did not set its type after Resolve\n" +
 495                                         "called from: " + this.GetType ());
 496                         }
 497
 498                         return e;
 499                 }
 500
 501                 /// <summary>
 502                 ///   Resolves an expression and performs semantic analysis on it.
 503                 /// </summary>
 504                 public Expression Resolve (EmitContext ec)
 505                 {
 506                         Expression e = Resolve (ec, ResolveFlags.VariableOrValue | ResolveFlags.MethodGroup);
 507
 508                         if (e != null && e.eclass == ExprClass.MethodGroup && RootContext.Version == LanguageVersion.ISO_1) {
 509                                 ((MethodGroupExpr) e).ReportUsageError ();
 510                                 return null;
 511                         }
 512                         return e;
 513                 }
 514
 515                 public Constant ResolveAsConstant (EmitContext ec, MemberCore mc)
 516                 {
 517                         Expression e = Resolve (ec);
 518                         if (e == null)
 519                                 return null;
 520
 521                         Constant c = e as Constant;
 522                         if (c != null)
 523                                 return c;
 524
 525                         Const.Error_ExpressionMustBeConstant (loc, mc.GetSignatureForError ());
 526                         return null;
 527                 }
 528
 529                 /// <summary>
 530                 ///   Resolves an expression for LValue assignment
 531                 /// </summary>
 532                 ///
 533                 /// <remarks>
 534                 ///   Currently ResolveLValue wraps DoResolveLValue to perform sanity
 535                 ///   checking and assertion checking on what we expect from Resolve
 536                 /// </remarks>
 537                 public Expression ResolveLValue (EmitContext ec, Expression right_side, Location loc)
 538                 {
 539                         int errors = Report.Errors;
 540                         bool out_access = right_side == EmptyExpression.OutAccess;
 541
 542                         Expression e = DoResolveLValue (ec, right_side);
 543
 544                         if (e != null && out_access && !(e is IMemoryLocation)) {
 545                                 // FIXME: There's no problem with correctness, the 'Expr = null' handles that.
 546                                 //        Enabling this 'throw' will "only" result in deleting useless code elsewhere,
 547
 548                                 //throw new InternalErrorException ("ResolveLValue didn't return an IMemoryLocation: " +
 549                                 //                                e.GetType () + " " + e.GetSignatureForError ());
 550                                 e = null;
 551                         }
 552
 553                         if (e == null) {
 554                                 if (errors == Report.Errors) {
 555                                         if (out_access)
 556                                                 Report.Error (1510, loc, "A ref or out argument must be an assignable variable");
 557                                         else
 558                                                 Error_ValueAssignment (loc);
 559                                 }
 560                                 return null;
 561                         }
 562
 563                         if (e.eclass == ExprClass.Invalid)
 564                                 throw new Exception ("Expression " + e + " ExprClass is Invalid after resolve");
 565
 566                         if ((e.type == null) && !(e is ConstructedType))
 567                                 throw new Exception ("Expression " + e + " did not set its type after Resolve");
 568
 569                         return e;
 570                 }
 571
 572                 /// <summary>
 573                 ///   Emits the code for the expression
 574                 /// </summary>
 575                 ///
 576                 /// <remarks>
 577                 ///   The Emit method is invoked to generate the code
 578                 ///   for the expression.
 579                 /// </remarks>
 580                 public abstract void Emit (EmitContext ec);
 581
 582                 // Emit code to branch to @target if this expression is equivalent to @on_true.
 583                 // The default implementation is to emit the value, and then emit a brtrue or brfalse.
 584                 // Subclasses can provide more efficient implementations, but those MUST be equivalent,
 585                 // including the use of conditional branches.  Note also that a branch MUST be emitted
 586                 public virtual void EmitBranchable (EmitContext ec, Label target, bool on_true)
 587                 {
 588                         Emit (ec);
 589                         ec.ig.Emit (on_true ? OpCodes.Brtrue : OpCodes.Brfalse, target);
 590                 }
 591
 592                 // Emit this expression for its side effects, not for its value.
 593                 // The default implementation is to emit the value, and then throw it away.
 594                 // Subclasses can provide more efficient implementations, but those MUST be equivalent
 595                 public virtual void EmitSideEffect (EmitContext ec)
 596                 {
 597                         Emit (ec);
 598                         ec.ig.Emit (OpCodes.Pop);
 599                 }
 600
 601                 /// <summary>
 602                 ///   Protected constructor.  Only derivate types should
 603                 ///   be able to be created
 604                 /// </summary>
 605
 606                 protected Expression ()
 607                 {
 608                         eclass = ExprClass.Invalid;
 609                         type = null;
 610                 }
 611
 612                 /// <summary>
 613                 ///   Returns a fully formed expression after a MemberLookup
 614                 /// </summary>
 615                 ///
 616                 public static Expression ExprClassFromMemberInfo (Type container_type, MemberInfo mi, Location loc)
 617                 {
 618                         if (mi is EventInfo)
 619                                 return new EventExpr ((EventInfo) mi, loc);
 620                         else if (mi is FieldInfo) {
 621                                 FieldInfo fi = (FieldInfo) mi;
 622                                 if (fi.IsLiteral || (fi.IsInitOnly && fi.FieldType == TypeManager.decimal_type))
 623                                         return new ConstantExpr (fi, loc);
 624                                 return new FieldExpr (fi, loc);
 625                         } else if (mi is PropertyInfo)
 626                                 return new PropertyExpr (container_type, (PropertyInfo) mi, loc);
 627                         else if (mi is Type) {
 628                                 return new TypeExpression ((System.Type) mi, loc);
 629                         }
 630
 631                         return null;
 632                 }
 633
 634                 protected static ArrayList almost_matched_members = new ArrayList (4);
 635
 636                 //
 637                 // FIXME: Probably implement a cache for (t,name,current_access_set)?
 638                 //
 639                 // This code could use some optimizations, but we need to do some
 640                 // measurements.  For example, we could use a delegate to `flag' when
 641                 // something can not any longer be a method-group (because it is something
 642                 // else).
 643                 //
 644                 // Return values:
 645                 //     If the return value is an Array, then it is an array of
 646                 //     MethodBases
 647                 //
 648                 //     If the return value is an MemberInfo, it is anything, but a Method
 649                 //
 650                 //     null on error.
 651                 //
 652                 // FIXME: When calling MemberLookup inside an `Invocation', we should pass
 653                 // the arguments here and have MemberLookup return only the methods that
 654                 // match the argument count/type, unlike we are doing now (we delay this
 655                 // decision).
 656                 //
 657                 // This is so we can catch correctly attempts to invoke instance methods
 658                 // from a static body (scan for error 120 in ResolveSimpleName).
 659                 //
 660                 //
 661                 // FIXME: Potential optimization, have a static ArrayList
 662                 //
 663
 664                 public static Expression MemberLookup (Type container_type, Type queried_type, string name,
 665                                                        MemberTypes mt, BindingFlags bf, Location loc)
 666                 {
 667                         return MemberLookup (container_type, null, queried_type, name, mt, bf, loc);
 668                 }
 669
 670                 //
 671                 // Lookup type `queried_type' for code in class `container_type' with a qualifier of
 672                 // `qualifier_type' or null to lookup members in the current class.
 673                 //
 674
 675                 public static Expression MemberLookup (Type container_type,
 676                                                        Type qualifier_type, Type queried_type,
 677                                                        string name, MemberTypes mt,
 678                                                        BindingFlags bf, Location loc)
 679                 {
 680                         almost_matched_members.Clear ();
 681
 682                         MemberInfo [] mi = TypeManager.MemberLookup (container_type, qualifier_type,
 683                                                                      queried_type, mt, bf, name, almost_matched_members);
 684
 685                         if (mi == null)
 686                                 return null;
 687
 688                         if (mi.Length > 1) {
 689                                 bool is_interface = qualifier_type != null && qualifier_type.IsInterface;
 690                                 ArrayList methods = new ArrayList (2);
 691                                 ArrayList non_methods = null;
 692
 693                                 foreach (MemberInfo m in mi) {
 694                                         if (m is MethodBase) {
 695                                                 methods.Add (m);
 696                                                 continue;
 697                                         }
 698
 699                                         if (non_methods == null) {
 700                                                 non_methods = new ArrayList (2);
 701                                                 non_methods.Add (m);
 702                                                 continue;
 703                                         }
 704
 705                                         foreach (MemberInfo n_m in non_methods) {
 706                                                 if (m.DeclaringType.IsInterface && TypeManager.ImplementsInterface (m.DeclaringType, n_m.DeclaringType))
 707                                                         continue;
 708
 709                                                 Report.SymbolRelatedToPreviousError (m);
 710                                                 Report.Error (229, loc, "Ambiguity between `{0}' and `{1}'",
 711                                                         TypeManager.GetFullNameSignature (m), TypeManager.GetFullNameSignature (n_m));
 712                                                 return null;
 713                                         }
 714                                 }
 715
 716                                 if (methods.Count == 0)
 717                                         return ExprClassFromMemberInfo (container_type, (MemberInfo)non_methods [0], loc);
 718
 719                                 if (non_methods != null) {
 720                                         MethodBase method = (MethodBase) methods [0];
 721                                         MemberInfo non_method = (MemberInfo) non_methods [0];
 722                                         if (method.DeclaringType == non_method.DeclaringType) {
 723                                                 // Cannot happen with C# code, but is valid in IL
 724                                                 Report.SymbolRelatedToPreviousError (method);
 725                                                 Report.SymbolRelatedToPreviousError (non_method);
 726                                                 Report.Error (229, loc, "Ambiguity between `{0}' and `{1}'",
 727                                                               TypeManager.GetFullNameSignature (non_method),
 728                                                               TypeManager.CSharpSignature (method));
 729                                                 return null;
 730                                         }
 731
 732                                         if (is_interface) {
 733                                                 Report.SymbolRelatedToPreviousError (method);
 734                                                 Report.SymbolRelatedToPreviousError (non_method);
 735                                                 Report.Warning (467, 2, loc, "Ambiguity between method `{0}' and non-method `{1}'. Using method `{0}'",
 736                                                                 TypeManager.CSharpSignature (method), TypeManager.GetFullNameSignature (non_method));
 737                                         }
 738                                 }
 739
 740                                 return new MethodGroupExpr (methods, queried_type, loc);
 741                         }
 742
 743                         if (mi [0] is MethodBase)
 744                                 return new MethodGroupExpr (mi, queried_type, loc);
 745
 746                         return ExprClassFromMemberInfo (container_type, mi [0], loc);
 747                 }
 748
 749                 public const MemberTypes AllMemberTypes =
 750                         MemberTypes.Constructor |
 751                         MemberTypes.Event       |
 752                         MemberTypes.Field       |
 753                         MemberTypes.Method      |
 754                         MemberTypes.NestedType  |
 755                         MemberTypes.Property;
 756
 757                 public const BindingFlags AllBindingFlags =
 758                         BindingFlags.Public |
 759                         BindingFlags.Static |
 760                         BindingFlags.Instance;
 761
 762                 public static Expression MemberLookup (Type container_type, Type queried_type,
 763                                                        string name, Location loc)
 764                 {
 765                         return MemberLookup (container_type, null, queried_type, name,
 766                                              AllMemberTypes, AllBindingFlags, loc);
 767                 }
 768
 769                 public static Expression MemberLookup (Type container_type, Type qualifier_type,
 770                                                        Type queried_type, string name, Location loc)
 771                 {
 772                         return MemberLookup (container_type, qualifier_type, queried_type,
 773                                              name, AllMemberTypes, AllBindingFlags, loc);
 774                 }
 775
 776                 public static MethodGroupExpr MethodLookup (Type container_type, Type queried_type,
 777                                                        string name, Location loc)
 778                 {
 779                         return (MethodGroupExpr)MemberLookup (container_type, null, queried_type, name,
 780                                              MemberTypes.Method, AllBindingFlags, loc);
 781                 }
 782
 783                 /// <summary>
 784                 ///   This is a wrapper for MemberLookup that is not used to "probe", but
 785                 ///   to find a final definition.  If the final definition is not found, we
 786                 ///   look for private members and display a useful debugging message if we
 787                 ///   find it.
 788                 /// </summary>
 789                 protected Expression MemberLookupFinal (EmitContext ec, Type qualifier_type,
 790                                                             Type queried_type, string name,
 791                                                             MemberTypes mt, BindingFlags bf,
 792                                                             Location loc)
 793                 {
 794                         Expression e;
 795
 796                         int errors = Report.Errors;
 797                         e = MemberLookup (ec.ContainerType, qualifier_type, queried_type, name, mt, bf, loc);
 798
 799                         if (e != null || errors != Report.Errors)
 800                                 return e;
 801
 802                         // No errors were reported by MemberLookup, but there was an error.
 803                         return Error_MemberLookupFailed (ec.ContainerType, qualifier_type, queried_type,
 804                                         name, null, mt, bf);
 805                 }
 806
 807                 protected virtual Expression Error_MemberLookupFailed (Type container_type, Type qualifier_type,
 808                                                        Type queried_type, string name, string class_name,
 809                                                            MemberTypes mt, BindingFlags bf)
 810                 {
 811                         if (almost_matched_members.Count != 0) {
 812                                 for (int i = 0; i < almost_matched_members.Count; ++i) {
 813                                         MemberInfo m = (MemberInfo) almost_matched_members [i];
 814                                         for (int j = 0; j < i; ++j) {
 815                                                 if (m == almost_matched_members [j]) {
 816                                                         m = null;
 817                                                         break;
 818                                                 }
 819                                         }
 820                                         if (m == null)
 821                                                 continue;
 822
 823                                         Type declaring_type = m.DeclaringType;
 824
 825                                         Report.SymbolRelatedToPreviousError (m);
 826                                         if (qualifier_type == null) {
 827                                                 Report.Error (38, loc, "Cannot access a nonstatic member of outer type `{0}' via nested type `{1}'",
 828                                                               TypeManager.CSharpName (m.DeclaringType),
 829                                                               TypeManager.CSharpName (container_type));
 830
 831                                         } else if (qualifier_type != container_type &&
 832                                                    TypeManager.IsNestedFamilyAccessible (container_type, declaring_type)) {
 833                                                 // Although a derived class can access protected members of
 834                                                 // its base class it cannot do so through an instance of the
 835                                                 // base class (CS1540).  If the qualifier_type is a base of the
 836                                                 // ec.ContainerType and the lookup succeeds with the latter one,
 837                                                 // then we are in this situation.
 838                                                 Error_CannotAccessProtected (loc, m, qualifier_type, container_type);
 839                                         } else {
 840                                                 ErrorIsInaccesible (loc, TypeManager.GetFullNameSignature (m));
 841                                         }
 842                                 }
 843                                 almost_matched_members.Clear ();
 844                                 return null;
 845                         }
 846
 847                         MemberInfo[] lookup = null;
 848                         if (queried_type == null) {
 849                                 class_name = "global::";
 850                         } else {
 851                                 lookup = TypeManager.MemberLookup (queried_type, null, queried_type,
 852                                         mt, (bf & ~BindingFlags.Public) | BindingFlags.NonPublic,
 853                                         name, null);
 854
 855                                 if (lookup != null) {
 856                                         Report.SymbolRelatedToPreviousError (lookup [0]);
 857                                         ErrorIsInaccesible (loc, TypeManager.GetFullNameSignature (lookup [0]));
 858                                         return Error_MemberLookupFailed (lookup);
 859                                 }
 860
 861                                 lookup = TypeManager.MemberLookup (queried_type, null, queried_type,
 862                                         AllMemberTypes, AllBindingFlags | BindingFlags.NonPublic,
 863                                         name, null);
 864                         }
 865
 866                         if (lookup == null) {
 867                                 if (class_name != null) {
 868                                         Report.Error (103, loc, "The name `{0}' does not exist in the current context",
 869                                                 name);
 870                                 } else {
 871                                         Error_TypeDoesNotContainDefinition (queried_type, name);
 872                                 }
 873                                 return null;
 874                         }
 875
 876                         if (TypeManager.MemberLookup (queried_type, null, queried_type,
 877                                                       AllMemberTypes, AllBindingFlags |
 878                                                       BindingFlags.NonPublic, name, null) == null) {
 879                                 if ((lookup.Length == 1) && (lookup [0] is Type)) {
 880                                         Type t = (Type) lookup [0];
 881
 882                                         Report.Error (305, loc,
 883                                                       "Using the generic type `{0}' " +
 884                                                       "requires {1} type arguments",
 885                                                       TypeManager.CSharpName (t),
 886                                                       TypeManager.GetNumberOfTypeArguments (t).ToString ());
 887                                         return null;
 888                                 }
 889                         }
 890
 891                         return Error_MemberLookupFailed (lookup);
 892                 }
 893
 894                 protected virtual Expression Error_MemberLookupFailed (MemberInfo[] members)
 895                 {
 896                         for (int i = 0; i < members.Length; ++i) {
 897                                 if (!(members [i] is MethodBase))
 898                                         return null;
 899                         }
 900
 901                         // By default propagate the closest candidates upwards
 902                         return new MethodGroupExpr (members, type, loc);
 903                 }
 904
 905                 protected virtual void Error_NegativeArrayIndex (Location loc)
 906                 {
 907                         throw new NotImplementedException ();
 908                 }
 909
 910                 protected void Error_PointerInsideExpressionTree ()
 911                 {
 912                         Report.Error (1944, loc, "An expression tree cannot contain an unsafe pointer operation");
 913                 }
 914
 915                 /// <summary>
 916                 ///   Returns an expression that can be used to invoke operator true
 917                 ///   on the expression if it exists.
 918                 /// </summary>
 919                 static public Expression GetOperatorTrue (EmitContext ec, Expression e, Location loc)
 920                 {
 921                         return GetOperatorTrueOrFalse (ec, e, true, loc);
 922                 }
 923
 924                 /// <summary>
 925                 ///   Returns an expression that can be used to invoke operator false
 926                 ///   on the expression if it exists.
 927                 /// </summary>
 928                 static public Expression GetOperatorFalse (EmitContext ec, Expression e, Location loc)
 929                 {
 930                         return GetOperatorTrueOrFalse (ec, e, false, loc);
 931                 }
 932
 933                 static Expression GetOperatorTrueOrFalse (EmitContext ec, Expression e, bool is_true, Location loc)
 934                 {
 935                         MethodGroupExpr operator_group;
 936                         string mname = Operator.GetMetadataName (is_true ? Operator.OpType.True : Operator.OpType.False);
 937                         operator_group = MethodLookup (ec.ContainerType, e.Type, mname, loc) as MethodGroupExpr;
 938                         if (operator_group == null)
 939                                 return null;
 940
 941                         ArrayList arguments = new ArrayList (1);
 942                         arguments.Add (new Argument (e, Argument.AType.Expression));
 943                         operator_group = operator_group.OverloadResolve (
 944                                 ec, ref arguments, false, loc);
 945
 946                         if (operator_group == null)
 947                                 return null;
 948
 949                         return new UserOperatorCall (operator_group, arguments, null, loc);
 950                 }
 951
 952                 /// <summary>
 953                 ///   Resolves the expression `e' into a boolean expression: either through
 954                 ///   an implicit conversion, or through an `operator true' invocation
 955                 /// </summary>
 956                 public static Expression ResolveBoolean (EmitContext ec, Expression e, Location loc)
 957                 {
 958                         e = e.Resolve (ec);
 959                         if (e == null)
 960                                 return null;
 961
 962                         if (e.Type == TypeManager.bool_type)
 963                                 return e;
 964
 965                         Expression converted = Convert.ImplicitConversion (ec, e, TypeManager.bool_type, Location.Null);
 966
 967                         if (converted != null)
 968                                 return converted;
 969
 970                         //
 971                         // If no implicit conversion to bool exists, try using `operator true'
 972                         //
 973                         converted = Expression.GetOperatorTrue (ec, e, loc);
 974                         if (converted == null){
 975                                 e.Error_ValueCannotBeConverted (ec, loc, TypeManager.bool_type, false);
 976                                 return null;
 977                         }
 978                         return converted;
 979                 }
 980
 981                 public virtual string ExprClassName
 982                 {
 983                         get {
 984                                 switch (eclass){
 985                                         case ExprClass.Invalid:
 986                                                 return "Invalid";
 987                                         case ExprClass.Value:
 988                                                 return "value";
 989                                         case ExprClass.Variable:
 990                                                 return "variable";
 991                                         case ExprClass.Namespace:
 992                                                 return "namespace";
 993                                         case ExprClass.Type:
 994                                                 return "type";
 995                                         case ExprClass.MethodGroup:
 996                                                 return "method group";
 997                                         case ExprClass.PropertyAccess:
 998                                                 return "property access";
 999                                         case ExprClass.EventAccess:
1000                                                 return "event access";
1001                                         case ExprClass.IndexerAccess:
1002                                                 return "indexer access";
1003                                         case ExprClass.Nothing:
1004                                                 return "null";
1005                                         case ExprClass.TypeParameter:
1006                                                 return "type parameter";
1007                                 }
1008                                 throw new Exception ("Should not happen");
1009                         }
1010                 }
1011
1012                 /// <summary>
1013                 ///   Reports that we were expecting `expr' to be of class `expected'
1014                 /// </summary>
1015                 public void Error_UnexpectedKind (DeclSpace ds, string expected, Location loc)
1016                 {
1017                         Error_UnexpectedKind (ds, expected, ExprClassName, loc);
1018                 }
1019
1020                 public void Error_UnexpectedKind (DeclSpace ds, string expected, string was, Location loc)
1021                 {
1022                         string name = GetSignatureForError ();
1023                         if (ds != null)
1024                                 name = ds.GetSignatureForError () + '.' + name;
1025
1026                         Report.Error (118, loc, "`{0}' is a `{1}' but a `{2}' was expected",
1027                               name, was, expected);
1028                 }
1029
1030                 public void Error_UnexpectedKind (ResolveFlags flags, Location loc)
1031                 {
1032                         string [] valid = new string [4];
1033                         int count = 0;
1034
1035                         if ((flags & ResolveFlags.VariableOrValue) != 0) {
1036                                 valid [count++] = "variable";
1037                                 valid [count++] = "value";
1038                         }
1039
1040                         if ((flags & ResolveFlags.Type) != 0)
1041                                 valid [count++] = "type";
1042
1043                         if ((flags & ResolveFlags.MethodGroup) != 0)
1044                                 valid [count++] = "method group";
1045
1046                         if (count == 0)
1047                                 valid [count++] = "unknown";
1048
1049                         StringBuilder sb = new StringBuilder (valid [0]);
1050                         for (int i = 1; i < count - 1; i++) {
1051                                 sb.Append ("', `");
1052                                 sb.Append (valid [i]);
1053                         }
1054                         if (count > 1) {
1055                                 sb.Append ("' or `");
1056                                 sb.Append (valid [count - 1]);
1057                         }
1058
1059                         Report.Error (119, loc,
1060                                 "Expression denotes a `{0}', where a `{1}' was expected", ExprClassName, sb.ToString ());
1061                 }
1062
1063                 public static void UnsafeError (Location loc)
1064                 {
1065                         Report.Error (214, loc, "Pointers and fixed size buffers may only be used in an unsafe context");
1066                 }
1067
1068                 //
1069                 // Load the object from the pointer.
1070                 //
1071                 public static void LoadFromPtr (ILGenerator ig, Type t)
1072                 {
1073                         if (t == TypeManager.int32_type)
1074                                 ig.Emit (OpCodes.Ldind_I4);
1075                         else if (t == TypeManager.uint32_type)
1076                                 ig.Emit (OpCodes.Ldind_U4);
1077                         else if (t == TypeManager.short_type)
1078                                 ig.Emit (OpCodes.Ldind_I2);
1079                         else if (t == TypeManager.ushort_type)
1080                                 ig.Emit (OpCodes.Ldind_U2);
1081                         else if (t == TypeManager.char_type)
1082                                 ig.Emit (OpCodes.Ldind_U2);
1083                         else if (t == TypeManager.byte_type)
1084                                 ig.Emit (OpCodes.Ldind_U1);
1085                         else if (t == TypeManager.sbyte_type)
1086                                 ig.Emit (OpCodes.Ldind_I1);
1087                         else if (t == TypeManager.uint64_type)
1088                                 ig.Emit (OpCodes.Ldind_I8);
1089                         else if (t == TypeManager.int64_type)
1090                                 ig.Emit (OpCodes.Ldind_I8);
1091                         else if (t == TypeManager.float_type)
1092                                 ig.Emit (OpCodes.Ldind_R4);
1093                         else if (t == TypeManager.double_type)
1094                                 ig.Emit (OpCodes.Ldind_R8);
1095                         else if (t == TypeManager.bool_type)
1096                                 ig.Emit (OpCodes.Ldind_I1);
1097                         else if (t == TypeManager.intptr_type)
1098                                 ig.Emit (OpCodes.Ldind_I);
1099                         else if (TypeManager.IsEnumType (t)) {
1100                                 if (t == TypeManager.enum_type)
1101                                         ig.Emit (OpCodes.Ldind_Ref);
1102                                 else
1103                                         LoadFromPtr (ig, TypeManager.GetEnumUnderlyingType (t));
1104                         } else if (t.IsValueType || TypeManager.IsGenericParameter (t))
1105                                 ig.Emit (OpCodes.Ldobj, t);
1106                         else if (t.IsPointer)
1107                                 ig.Emit (OpCodes.Ldind_I);
1108                         else
1109                                 ig.Emit (OpCodes.Ldind_Ref);
1110                 }
1111
1112                 //
1113                 // The stack contains the pointer and the value of type `type'
1114                 //
1115                 public static void StoreFromPtr (ILGenerator ig, Type type)
1116                 {
1117                         if (TypeManager.IsEnumType (type))
1118                                 type = TypeManager.GetEnumUnderlyingType (type);
1119                         if (type == TypeManager.int32_type || type == TypeManager.uint32_type)
1120                                 ig.Emit (OpCodes.Stind_I4);
1121                         else if (type == TypeManager.int64_type || type == TypeManager.uint64_type)
1122                                 ig.Emit (OpCodes.Stind_I8);
1123                         else if (type == TypeManager.char_type || type == TypeManager.short_type ||
1124                                  type == TypeManager.ushort_type)
1125                                 ig.Emit (OpCodes.Stind_I2);
1126                         else if (type == TypeManager.float_type)
1127                                 ig.Emit (OpCodes.Stind_R4);
1128                         else if (type == TypeManager.double_type)
1129                                 ig.Emit (OpCodes.Stind_R8);
1130                         else if (type == TypeManager.byte_type || type == TypeManager.sbyte_type ||
1131                                  type == TypeManager.bool_type)
1132                                 ig.Emit (OpCodes.Stind_I1);
1133                         else if (type == TypeManager.intptr_type)
1134                                 ig.Emit (OpCodes.Stind_I);
1135                         else if (type.IsValueType || TypeManager.IsGenericParameter (type))
1136                                 ig.Emit (OpCodes.Stobj, type);
1137                         else
1138                                 ig.Emit (OpCodes.Stind_Ref);
1139                 }
1140
1141                 //
1142                 // Returns the size of type `t' if known, otherwise, 0
1143                 //
1144                 public static int GetTypeSize (Type t)
1145                 {
1146                         t = TypeManager.TypeToCoreType (t);
1147                         if (t == TypeManager.int32_type ||
1148                             t == TypeManager.uint32_type ||
1149                             t == TypeManager.float_type)
1150                                 return 4;
1151                         else if (t == TypeManager.int64_type ||
1152                                  t == TypeManager.uint64_type ||
1153                                  t == TypeManager.double_type)
1154                                 return 8;
1155                         else if (t == TypeManager.byte_type ||
1156                                  t == TypeManager.sbyte_type ||
1157                                  t == TypeManager.bool_type)
1158                                 return 1;
1159                         else if (t == TypeManager.short_type ||
1160                                  t == TypeManager.char_type ||
1161                                  t == TypeManager.ushort_type)
1162                                 return 2;
1163                         else if (t == TypeManager.decimal_type)
1164                                 return 16;
1165                         else
1166                                 return 0;
1167                 }
1168
1169                 protected void Error_CannotCallAbstractBase (string name)
1170                 {
1171                         Report.Error (205, loc, "Cannot call an abstract base member `{0}'", name);
1172                 }
1173
1174                 protected void Error_CannotModifyIntermediateExpressionValue (EmitContext ec)
1175                 {
1176                         Report.SymbolRelatedToPreviousError (type);
1177                         if (ec.CurrentInitializerVariable != null) {
1178                                 Report.Error (1918, loc, "Members of value type `{0}' cannot be assigned using a property `{1}' object initializer",
1179                                         TypeManager.CSharpName (type), GetSignatureForError ());
1180                         } else {
1181                                 Report.Error (1612, loc, "Cannot modify a value type return value of `{0}'. Consider storing the value in a temporary variable",
1182                                         GetSignatureForError ());
1183                         }
1184                 }
1185
1186                 //
1187                 // Converts `source' to an int, uint, long or ulong.
1188                 //
1189                 public Expression ConvertExpressionToArrayIndex (EmitContext ec, Expression source)
1190                 {
1191                         Expression converted;
1192
1193                         using (ec.With (EmitContext.Flags.CheckState, true)) {
1194                                 converted = Convert.ImplicitConversion (ec, source, TypeManager.int32_type, source.loc);
1195                                 if (converted == null)
1196                                         converted = Convert.ImplicitConversion (ec, source, TypeManager.uint32_type, source.loc);
1197                                 if (converted == null)
1198                                         converted = Convert.ImplicitConversion (ec, source, TypeManager.int64_type, source.loc);
1199                                 if (converted == null)
1200                                         converted = Convert.ImplicitConversion (ec, source, TypeManager.uint64_type, source.loc);
1201
1202                                 if (converted == null) {
1203                                         source.Error_ValueCannotBeConverted (ec, source.loc, TypeManager.int32_type, false);
1204                                         return null;
1205                                 }
1206                         }
1207
1208                         //
1209                         // Only positive constants are allowed at compile time
1210                         //
1211                         Constant c = converted as Constant;
1212                         if (c != null) {
1213                                 if (c.IsNegative) {
1214                                         Error_NegativeArrayIndex (source.loc);
1215                                 }
1216                                 return c;
1217                         }
1218
1219                         return new ArrayIndexCast (converted).Resolve (ec);
1220                 }
1221
1222                 //
1223                 // Derived classes implement this method by cloning the fields that
1224                 // could become altered during the Resolve stage
1225                 //
1226                 // Only expressions that are created for the parser need to implement
1227                 // this.
1228                 //
1229                 protected virtual void CloneTo (CloneContext clonectx, Expression target)
1230                 {
1231                         throw new NotImplementedException (
1232                                 String.Format (
1233                                         "CloneTo not implemented for expression {0}", this.GetType ()));
1234                 }
1235
1236                 //
1237                 // Clones an expression created by the parser.
1238                 //
1239                 // We only support expressions created by the parser so far, not
1240                 // expressions that have been resolved (many more classes would need
1241                 // to implement CloneTo).
1242                 //
1243                 // This infrastructure is here merely for Lambda expressions which
1244                 // compile the same code using different type values for the same
1245                 // arguments to find the correct overload
1246                 //
1247                 public Expression Clone (CloneContext clonectx)
1248                 {
1249                         Expression cloned = (Expression) MemberwiseClone ();
1250                         CloneTo (clonectx, cloned);
1251
1252                         return cloned;
1253                 }
1254
1255                 //
1256                 // Implementation of expression to expression tree conversion
1257                 //
1258                 public abstract Expression CreateExpressionTree (EmitContext ec);
1259
1260                 protected Expression CreateExpressionFactoryCall (string name, ArrayList args)
1261                 {
1262                         return CreateExpressionFactoryCall (name, null, args, loc);
1263                 }
1264
1265                 protected Expression CreateExpressionFactoryCall (string name, TypeArguments typeArguments, ArrayList args)
1266                 {
1267                         return CreateExpressionFactoryCall (name, typeArguments, args, loc);
1268                 }
1269
1270                 public static Expression CreateExpressionFactoryCall (string name, TypeArguments typeArguments, ArrayList args, Location loc)
1271                 {
1272                         return new Invocation (new MemberAccess (CreateExpressionTypeExpression (loc), name, typeArguments, loc), args);
1273                 }
1274
1275                 protected static TypeExpr CreateExpressionTypeExpression (Location loc)
1276                 {
1277                         TypeExpr texpr = TypeManager.expression_type_expr;
1278                         if (texpr == null) {
1279                                 Type t = TypeManager.CoreLookupType ("System.Linq.Expressions", "Expression", Kind.Class, true);
1280                                 if (t == null)
1281                                         return null;
1282
1283                                 TypeManager.expression_type_expr = texpr = new TypeExpression (t, Location.Null);
1284                         }
1285
1286                         return texpr;
1287                 }
1288
1289                 public virtual void MutateHoistedGenericType (AnonymousMethodStorey storey)
1290                 {
1291                         // TODO: It should probably be type = storey.MutateType (type);
1292                 }
1293         }
1294
1295         /// <summary>
1296         ///   This is just a base class for expressions that can
1297         ///   appear on statements (invocations, object creation,
1298         ///   assignments, post/pre increment and decrement).  The idea
1299         ///   being that they would support an extra Emition interface that
1300         ///   does not leave a result on the stack.
1301         /// </summary>
1302         public abstract class ExpressionStatement : Expression {
1303
1304                 public virtual ExpressionStatement ResolveStatement (EmitContext ec)
1305                 {
1306                         Expression e = Resolve (ec);
1307                         if (e == null)
1308                                 return null;
1309
1310                         ExpressionStatement es = e as ExpressionStatement;
1311                         if (es == null)
1312                                 Error_InvalidExpressionStatement ();
1313
1314                         return es;
1315                 }
1316
1317                 /// <summary>
1318                 ///   Requests the expression to be emitted in a `statement'
1319                 ///   context.  This means that no new value is left on the
1320                 ///   stack after invoking this method (constrasted with
1321                 ///   Emit that will always leave a value on the stack).
1322                 /// </summary>
1323                 public abstract void EmitStatement (EmitContext ec);
1324
1325                 public override void EmitSideEffect (EmitContext ec)
1326                 {
1327                         EmitStatement (ec);
1328                 }
1329         }
1330
1331         /// <summary>
1332         ///   This kind of cast is used to encapsulate the child
1333         ///   whose type is child.Type into an expression that is
1334         ///   reported to return "return_type".  This is used to encapsulate
1335         ///   expressions which have compatible types, but need to be dealt
1336         ///   at higher levels with.
1337         ///
1338         ///   For example, a "byte" expression could be encapsulated in one
1339         ///   of these as an "unsigned int".  The type for the expression
1340         ///   would be "unsigned int".
1341         ///
1342         /// </summary>
1343         public abstract class TypeCast : Expression
1344         {
1345                 protected readonly Expression child;
1346
1347                 protected TypeCast (Expression child, Type return_type)
1348                 {
1349                         eclass = child.eclass;
1350                         loc = child.Location;
1351                         type = return_type;
1352                         this.child = child;
1353                 }
1354
1355                 public override Expression CreateExpressionTree (EmitContext ec)
1356                 {
1357                         ArrayList args = new ArrayList (2);
1358                         args.Add (new Argument (child.CreateExpressionTree (ec)));
1359                         args.Add (new Argument (new TypeOf (new TypeExpression (type, loc), loc)));
1360
1361                         if (type.IsPointer || child.Type.IsPointer)
1362                                 Error_PointerInsideExpressionTree ();
1363
1364                         return CreateExpressionFactoryCall (ec.CheckState ? "ConvertChecked" : "Convert", args);
1365                 }
1366
1367                 public override Expression DoResolve (EmitContext ec)
1368                 {
1369                         // This should never be invoked, we are born in fully
1370                         // initialized state.
1371
1372                         return this;
1373                 }
1374
1375                 public override void Emit (EmitContext ec)
1376                 {
1377                         child.Emit (ec);
1378                 }
1379
1380                 public override bool GetAttributableValue (EmitContext ec, Type value_type, out object value)
1381                 {
1382                         return child.GetAttributableValue (ec, value_type, out value);
1383                 }
1384
1385                 public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
1386                 {
1387                         child.MutateHoistedGenericType (storey);
1388                 }
1389
1390                 protected override void CloneTo (CloneContext clonectx, Expression t)
1391                 {
1392                         // Nothing to clone
1393                 }
1394
1395                 public override bool IsNull {
1396                         get { return child.IsNull; }
1397                 }
1398         }
1399
1400         public class EmptyCast : TypeCast {
1401                 EmptyCast (Expression child, Type target_type)
1402                         : base (child, target_type)
1403                 {
1404                 }
1405
1406                 public static Expression Create (Expression child, Type type)
1407                 {
1408                         Constant c = child as Constant;
1409                         if (c != null)
1410                                 return new EmptyConstantCast (c, type);
1411
1412                         EmptyCast e = child as EmptyCast;
1413                         if (e != null)
1414                                 return new EmptyCast (e.child, type);
1415
1416                         return new EmptyCast (child, type);
1417                 }
1418
1419                 public override void EmitBranchable (EmitContext ec, Label label, bool on_true)
1420                 {
1421                         child.EmitBranchable (ec, label, on_true);
1422                 }
1423
1424                 public override void EmitSideEffect (EmitContext ec)
1425                 {
1426                         child.EmitSideEffect (ec);
1427                 }
1428         }
1429
1430         /// <summary>
1431         ///    Performs a cast using an operator (op_Explicit or op_Implicit)
1432         /// </summary>
1433         public class OperatorCast : TypeCast {
1434                 MethodInfo conversion_operator;
1435                 bool find_explicit;
1436
1437                 public OperatorCast (Expression child, Type target_type) : this (child, target_type, false) {}
1438
1439                 public OperatorCast (Expression child, Type target_type, bool find_explicit)
1440                         : base (child, target_type)
1441                 {
1442                         this.find_explicit = find_explicit;
1443                 }
1444
1445                 // Returns the implicit operator that converts from
1446                 // 'child.Type' to our target type (type)
1447                 MethodInfo GetConversionOperator (bool find_explicit)
1448                 {
1449                         string operator_name = find_explicit ? "op_Explicit" : "op_Implicit";
1450
1451                         MemberInfo [] mi;
1452
1453                         mi = TypeManager.MemberLookup (child.Type, child.Type, child.Type, MemberTypes.Method,
1454                                 BindingFlags.Static | BindingFlags.Public, operator_name, null);
1455
1456                         if (mi == null){
1457                                 mi = TypeManager.MemberLookup (type, type, type, MemberTypes.Method,
1458                                                                BindingFlags.Static | BindingFlags.Public, operator_name, null);
1459                         }
1460
1461                         foreach (MethodInfo oper in mi) {
1462                                 AParametersCollection pd = TypeManager.GetParameterData (oper);
1463
1464                                 if (pd.Types [0] == child.Type && TypeManager.TypeToCoreType (oper.ReturnType) == type)
1465                                         return oper;
1466                         }
1467
1468                         return null;
1469
1470
1471                 }
1472                 public override void Emit (EmitContext ec)
1473                 {
1474                         ILGenerator ig = ec.ig;
1475
1476                         child.Emit (ec);
1477                         conversion_operator = GetConversionOperator (find_explicit);
1478
1479                         if (conversion_operator == null)
1480                                 throw new InternalErrorException ("Outer conversion routine is out of sync");
1481
1482                         ig.Emit (OpCodes.Call, conversion_operator);
1483                 }
1484
1485         }
1486
1487         /// <summary>
1488         ///     This is a numeric cast to a Decimal
1489         /// </summary>
1490         public class CastToDecimal : TypeCast {
1491                 MethodInfo conversion_operator;
1492
1493                 public CastToDecimal (Expression child)
1494                         : this (child, false)
1495                 {
1496                 }
1497
1498                 public CastToDecimal (Expression child, bool find_explicit)
1499                         : base (child, TypeManager.decimal_type)
1500                 {
1501                         conversion_operator = GetConversionOperator (find_explicit);
1502
1503                         if (conversion_operator == null)
1504                                 throw new InternalErrorException ("Outer conversion routine is out of sync");
1505                 }
1506
1507                 // Returns the implicit operator that converts from
1508                 // 'child.Type' to System.Decimal.
1509                 MethodInfo GetConversionOperator (bool find_explicit)
1510                 {
1511                         string operator_name = find_explicit ? "op_Explicit" : "op_Implicit";
1512
1513                         MemberInfo [] mi = TypeManager.MemberLookup (type, type, type, MemberTypes.Method,
1514                                 BindingFlags.Static | BindingFlags.Public, operator_name, null);
1515
1516                         foreach (MethodInfo oper in mi) {
1517                                 AParametersCollection pd = TypeManager.GetParameterData (oper);
1518
1519                                 if (pd.Types [0] == child.Type && TypeManager.TypeToCoreType (oper.ReturnType) == type)
1520                                         return oper;
1521                         }
1522
1523                         return null;
1524                 }
1525                 public override void Emit (EmitContext ec)
1526                 {
1527                         ILGenerator ig = ec.ig;
1528                         child.Emit (ec);
1529
1530                         ig.Emit (OpCodes.Call, conversion_operator);
1531                 }
1532         }
1533
1534         /// <summary>
1535         ///     This is an explicit numeric cast from a Decimal
1536         /// </summary>
1537         public class CastFromDecimal : TypeCast
1538         {
1539                 static IDictionary operators;
1540
1541                 public CastFromDecimal (Expression child, Type return_type)
1542                         : base (child, return_type)
1543                 {
1544                         if (child.Type != TypeManager.decimal_type)
1545                                 throw new InternalErrorException (
1546                                         "The expected type is Decimal, instead it is " + child.Type.FullName);
1547                 }
1548
1549                 // Returns the explicit operator that converts from an
1550                 // express of type System.Decimal to 'type'.
1551                 public Expression Resolve ()
1552                 {
1553                         if (operators == null) {
1554                                  MemberInfo[] all_oper = TypeManager.MemberLookup (TypeManager.decimal_type,
1555                                         TypeManager.decimal_type, TypeManager.decimal_type, MemberTypes.Method,
1556                                         BindingFlags.Static | BindingFlags.Public, "op_Explicit", null);
1557
1558                                 operators = new System.Collections.Specialized.HybridDictionary ();
1559                                 foreach (MethodInfo oper in all_oper) {
1560                                         AParametersCollection pd = TypeManager.GetParameterData (oper);
1561                                         if (pd.Types [0] == TypeManager.decimal_type)
1562                                                 operators.Add (TypeManager.TypeToCoreType (oper.ReturnType), oper);
1563                                 }
1564                         }
1565
1566                         return operators.Contains (type) ? this : null;
1567                 }
1568
1569                 public override void Emit (EmitContext ec)
1570                 {
1571                         ILGenerator ig = ec.ig;
1572                         child.Emit (ec);
1573
1574                         ig.Emit (OpCodes.Call, (MethodInfo)operators [type]);
1575                 }
1576         }
1577
1578
1579         //
1580         // Constant specialization of EmptyCast.
1581         // We need to special case this since an empty cast of
1582         // a constant is still a constant.
1583         //
1584         public class EmptyConstantCast : Constant
1585         {
1586                 public readonly Constant child;
1587
1588                 public EmptyConstantCast(Constant child, Type type)
1589                         : base (child.Location)
1590                 {
1591                         eclass = child.eclass;
1592                         this.child = child;
1593                         this.type = type;
1594                 }
1595
1596                 public override string AsString ()
1597                 {
1598                         return child.AsString ();
1599                 }
1600
1601                 public override object GetValue ()
1602                 {
1603                         return child.GetValue ();
1604                 }
1605
1606                 public override Constant ConvertExplicitly (bool in_checked_context, Type target_type)
1607                 {
1608                         // FIXME: check that 'type' can be converted to 'target_type' first
1609                         return child.ConvertExplicitly (in_checked_context, target_type);
1610                 }
1611
1612                 public override Expression CreateExpressionTree (EmitContext ec)
1613                 {
1614                         ArrayList args = new ArrayList (2);
1615                         args.Add (new Argument (child.CreateExpressionTree (ec)));
1616                         args.Add (new Argument (new TypeOf (new TypeExpression (type, loc), loc)));
1617                         if (type.IsPointer)
1618                                 Error_PointerInsideExpressionTree ();
1619
1620                         return CreateExpressionFactoryCall ("Convert", args);
1621                 }
1622
1623                 public override Constant Increment ()
1624                 {
1625                         return child.Increment ();
1626                 }
1627
1628                 public override bool IsDefaultValue {
1629                         get { return child.IsDefaultValue; }
1630                 }
1631
1632                 public override bool IsNegative {
1633                         get { return child.IsNegative; }
1634                 }
1635
1636                 public override bool IsNull {
1637                         get { return child.IsNull; }
1638                 }
1639
1640                 public override bool IsZeroInteger {
1641                         get { return child.IsZeroInteger; }
1642                 }
1643
1644                 public override void Emit (EmitContext ec)
1645                 {
1646                         child.Emit (ec);
1647                 }
1648
1649                 public override void EmitBranchable (EmitContext ec, Label label, bool on_true)
1650                 {
1651                         child.EmitBranchable (ec, label, on_true);
1652                 }
1653
1654                 public override void EmitSideEffect (EmitContext ec)
1655                 {
1656                         child.EmitSideEffect (ec);
1657                 }
1658
1659                 public override Constant ConvertImplicitly (Type target_type)
1660                 {
1661                         // FIXME: Do we need to check user conversions?
1662                         if (!Convert.ImplicitStandardConversionExists (this, target_type))
1663                                 return null;
1664                         return child.ConvertImplicitly (target_type);
1665                 }
1666
1667                 public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
1668                 {
1669                         child.MutateHoistedGenericType (storey);
1670                 }
1671         }
1672
1673
1674         /// <summary>
1675         ///  This class is used to wrap literals which belong inside Enums
1676         /// </summary>
1677         public class EnumConstant : Constant {
1678                 public Constant Child;
1679
1680                 public EnumConstant (Constant child, Type enum_type):
1681                         base (child.Location)
1682                 {
1683                         eclass = child.eclass;
1684                         this.Child = child;
1685                         type = enum_type;
1686                 }
1687
1688                 public override Expression DoResolve (EmitContext ec)
1689                 {
1690                         // This should never be invoked, we are born in fully
1691                         // initialized state.
1692
1693                         return this;
1694                 }
1695
1696                 public override void Emit (EmitContext ec)
1697                 {
1698                         Child.Emit (ec);
1699                 }
1700
1701                 public override void EmitBranchable (EmitContext ec, Label label, bool on_true)
1702                 {
1703                         Child.EmitBranchable (ec, label, on_true);
1704                 }
1705
1706                 public override void EmitSideEffect (EmitContext ec)
1707                 {
1708                         Child.EmitSideEffect (ec);
1709                 }
1710
1711                 public override bool GetAttributableValue (EmitContext ec, Type value_type, out object value)
1712                 {
1713                         value = GetTypedValue ();
1714                         return true;
1715                 }
1716
1717                 public override string GetSignatureForError()
1718                 {
1719                         return TypeManager.CSharpName (Type);
1720                 }
1721
1722                 public override object GetValue ()
1723                 {
1724                         return Child.GetValue ();
1725                 }
1726
1727                 public override object GetTypedValue ()
1728                 {
1729                         // FIXME: runtime is not ready to work with just emited enums
1730                         if (!RootContext.StdLib) {
1731                                 return Child.GetValue ();
1732                         }
1733
1734                         return System.Enum.ToObject (type, Child.GetValue ());
1735                 }
1736
1737                 public override string AsString ()
1738                 {
1739                         return Child.AsString ();
1740                 }
1741
1742                 public override Constant Increment()
1743                 {
1744                         return new EnumConstant (Child.Increment (), type);
1745                 }
1746
1747                 public override bool IsDefaultValue {
1748                         get {
1749                                 return Child.IsDefaultValue;
1750                         }
1751                 }
1752
1753                 public override bool IsZeroInteger {
1754                         get { return Child.IsZeroInteger; }
1755                 }
1756
1757                 public override bool IsNegative {
1758                         get {
1759                                 return Child.IsNegative;
1760                         }
1761                 }
1762
1763                 public override Constant ConvertExplicitly(bool in_checked_context, Type target_type)
1764                 {
1765                         if (Child.Type == target_type)
1766                                 return Child;
1767
1768                         return Child.ConvertExplicitly (in_checked_context, target_type);
1769                 }
1770
1771                 public override Constant ConvertImplicitly (Type type)
1772                 {
1773                         Type this_type = TypeManager.DropGenericTypeArguments (Type);
1774                         type = TypeManager.DropGenericTypeArguments (type);
1775
1776                         if (this_type == type) {
1777                                 // This is workaround of mono bug. It can be removed when the latest corlib spreads enough
1778                                 if (TypeManager.IsEnumType (type.UnderlyingSystemType))
1779                                         return this;
1780
1781                                 Type child_type = TypeManager.DropGenericTypeArguments (Child.Type);
1782                                 if (type.UnderlyingSystemType != child_type)
1783                                         Child = Child.ConvertImplicitly (type.UnderlyingSystemType);
1784                                 return this;
1785                         }
1786
1787                         if (!Convert.ImplicitStandardConversionExists (this, type)){
1788                                 return null;
1789                         }
1790
1791                         return Child.ConvertImplicitly(type);
1792                 }
1793
1794         }
1795
1796         /// <summary>
1797         ///   This kind of cast is used to encapsulate Value Types in objects.
1798         ///
1799         ///   The effect of it is to box the value type emitted by the previous
1800         ///   operation.
1801         /// </summary>
1802         public class BoxedCast : TypeCast {
1803
1804                 public BoxedCast (Expression expr, Type target_type)
1805                         : base (expr, target_type)
1806                 {
1807                         eclass = ExprClass.Value;
1808                 }
1809
1810                 public override Expression DoResolve (EmitContext ec)
1811                 {
1812                         // This should never be invoked, we are born in fully
1813                         // initialized state.
1814
1815                         return this;
1816                 }
1817
1818                 public override void Emit (EmitContext ec)
1819                 {
1820                         base.Emit (ec);
1821
1822                         ec.ig.Emit (OpCodes.Box, child.Type);
1823                 }
1824
1825                 public override void EmitSideEffect (EmitContext ec)
1826                 {
1827                         // boxing is side-effectful, since it involves runtime checks, except when boxing to Object or ValueType
1828                         // so, we need to emit the box+pop instructions in most cases
1829                         if (child.Type.IsValueType &&
1830                             (type == TypeManager.object_type || type == TypeManager.value_type))
1831                                 child.EmitSideEffect (ec);
1832                         else
1833                                 base.EmitSideEffect (ec);
1834                 }
1835         }
1836
1837         public class UnboxCast : TypeCast {
1838                 public UnboxCast (Expression expr, Type return_type)
1839                         : base (expr, return_type)
1840                 {
1841                 }
1842
1843                 public override Expression DoResolve (EmitContext ec)
1844                 {
1845                         // This should never be invoked, we are born in fully
1846                         // initialized state.
1847
1848                         return this;
1849                 }
1850
1851                 public override Expression DoResolveLValue (EmitContext ec, Expression right_side)
1852                 {
1853                         if (right_side == EmptyExpression.LValueMemberAccess || right_side == EmptyExpression.LValueMemberOutAccess)
1854                                 Report.Error (445, loc, "Cannot modify the result of an unboxing conversion");
1855                         return base.DoResolveLValue (ec, right_side);
1856                 }
1857
1858                 public override void Emit (EmitContext ec)
1859                 {
1860                         ILGenerator ig = ec.ig;
1861
1862                         base.Emit (ec);
1863 #if GMCS_SOURCE
1864                         if (type.IsGenericParameter || type.IsGenericType && type.IsValueType)
1865                                 ig.Emit (OpCodes.Unbox_Any, type);
1866                         else
1867 #endif
1868                         {
1869                                 ig.Emit (OpCodes.Unbox, type);
1870
1871                                 LoadFromPtr (ig, type);
1872                         }
1873                 }
1874
1875                 public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
1876                 {
1877                         type = storey.MutateType (type);
1878                         base.MutateHoistedGenericType (storey);
1879                 }
1880         }
1881
1882         /// <summary>
1883         ///   This is used to perform explicit numeric conversions.
1884         ///
1885         ///   Explicit numeric conversions might trigger exceptions in a checked
1886         ///   context, so they should generate the conv.ovf opcodes instead of
1887         ///   conv opcodes.
1888         /// </summary>
1889         public class ConvCast : TypeCast {
1890                 public enum Mode : byte {
1891                         I1_U1, I1_U2, I1_U4, I1_U8, I1_CH,
1892                         U1_I1, U1_CH,
1893                         I2_I1, I2_U1, I2_U2, I2_U4, I2_U8, I2_CH,
1894                         U2_I1, U2_U1, U2_I2, U2_CH,
1895                         I4_I1, I4_U1, I4_I2, I4_U2, I4_U4, I4_U8, I4_CH,
1896                         U4_I1, U4_U1, U4_I2, U4_U2, U4_I4, U4_CH,
1897                         I8_I1, I8_U1, I8_I2, I8_U2, I8_I4, I8_U4, I8_U8, I8_CH,
1898                         U8_I1, U8_U1, U8_I2, U8_U2, U8_I4, U8_U4, U8_I8, U8_CH,
1899                         CH_I1, CH_U1, CH_I2,
1900                         R4_I1, R4_U1, R4_I2, R4_U2, R4_I4, R4_U4, R4_I8, R4_U8, R4_CH,
1901                         R8_I1, R8_U1, R8_I2, R8_U2, R8_I4, R8_U4, R8_I8, R8_U8, R8_CH, R8_R4
1902                 }
1903
1904                 Mode mode;
1905
1906                 public ConvCast (Expression child, Type return_type, Mode m)
1907                         : base (child, return_type)
1908                 {
1909                         mode = m;
1910                 }
1911
1912                 public override Expression DoResolve (EmitContext ec)
1913                 {
1914                         // This should never be invoked, we are born in fully
1915                         // initialized state.
1916
1917                         return this;
1918                 }
1919
1920                 public override string ToString ()
1921                 {
1922                         return String.Format ("ConvCast ({0}, {1})", mode, child);
1923                 }
1924
1925                 public override void Emit (EmitContext ec)
1926                 {
1927                         ILGenerator ig = ec.ig;
1928
1929                         base.Emit (ec);
1930
1931                         if (ec.CheckState){
1932                                 switch (mode){
1933                                 case Mode.I1_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
1934                                 case Mode.I1_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
1935                                 case Mode.I1_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
1936                                 case Mode.I1_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
1937                                 case Mode.I1_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
1938
1939                                 case Mode.U1_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1940                                 case Mode.U1_CH: /* nothing */ break;
1941
1942                                 case Mode.I2_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
1943                                 case Mode.I2_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
1944                                 case Mode.I2_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
1945                                 case Mode.I2_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
1946                                 case Mode.I2_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
1947                                 case Mode.I2_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
1948
1949                                 case Mode.U2_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1950                                 case Mode.U2_U1: ig.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1951                                 case Mode.U2_I2: ig.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1952                                 case Mode.U2_CH: /* nothing */ break;
1953
1954                                 case Mode.I4_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
1955                                 case Mode.I4_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
1956                                 case Mode.I4_I2: ig.Emit (OpCodes.Conv_Ovf_I2); break;
1957                                 case Mode.I4_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
1958                                 case Mode.I4_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
1959                                 case Mode.I4_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
1960                                 case Mode.I4_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
1961
1962                                 case Mode.U4_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1963                                 case Mode.U4_U1: ig.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1964                                 case Mode.U4_I2: ig.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1965                                 case Mode.U4_U2: ig.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1966                                 case Mode.U4_I4: ig.Emit (OpCodes.Conv_Ovf_I4_Un); break;
1967                                 case Mode.U4_CH: ig.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1968
1969                                 case Mode.I8_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
1970                                 case Mode.I8_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
1971                                 case Mode.I8_I2: ig.Emit (OpCodes.Conv_Ovf_I2); break;
1972                                 case Mode.I8_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
1973                                 case Mode.I8_I4: ig.Emit (OpCodes.Conv_Ovf_I4); break;
1974                                 case Mode.I8_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
1975                                 case Mode.I8_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
1976                                 case Mode.I8_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
1977
1978                                 case Mode.U8_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1979                                 case Mode.U8_U1: ig.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1980                                 case Mode.U8_I2: ig.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1981                                 case Mode.U8_U2: ig.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1982                                 case Mode.U8_I4: ig.Emit (OpCodes.Conv_Ovf_I4_Un); break;
1983                                 case Mode.U8_U4: ig.Emit (OpCodes.Conv_Ovf_U4_Un); break;
1984                                 case Mode.U8_I8: ig.Emit (OpCodes.Conv_Ovf_I8_Un); break;
1985                                 case Mode.U8_CH: ig.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1986
1987                                 case Mode.CH_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1988                                 case Mode.CH_U1: ig.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1989                                 case Mode.CH_I2: ig.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1990
1991                                 case Mode.R4_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
1992                                 case Mode.R4_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
1993                                 case Mode.R4_I2: ig.Emit (OpCodes.Conv_Ovf_I2); break;
1994                                 case Mode.R4_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
1995                                 case Mode.R4_I4: ig.Emit (OpCodes.Conv_Ovf_I4); break;
1996                                 case Mode.R4_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
1997                                 case Mode.R4_I8: ig.Emit (OpCodes.Conv_Ovf_I8); break;
1998                                 case Mode.R4_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
1999                                 case Mode.R4_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
2000
2001                                 case Mode.R8_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
2002                                 case Mode.R8_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
2003                                 case Mode.R8_I2: ig.Emit (OpCodes.Conv_Ovf_I2); break;
2004                                 case Mode.R8_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
2005                                 case Mode.R8_I4: ig.Emit (OpCodes.Conv_Ovf_I4); break;
2006                                 case Mode.R8_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
2007                                 case Mode.R8_I8: ig.Emit (OpCodes.Conv_Ovf_I8); break;
2008                                 case Mode.R8_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
2009                                 case Mode.R8_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
2010                                 case Mode.R8_R4: ig.Emit (OpCodes.Conv_R4); break;
2011                                 }
2012                         } else {
2013                                 switch (mode){
2014                                 case Mode.I1_U1: ig.Emit (OpCodes.Conv_U1); break;
2015                                 case Mode.I1_U2: ig.Emit (OpCodes.Conv_U2); break;
2016                                 case Mode.I1_U4: ig.Emit (OpCodes.Conv_U4); break;
2017                                 case Mode.I1_U8: ig.Emit (OpCodes.Conv_I8); break;
2018                                 case Mode.I1_CH: ig.Emit (OpCodes.Conv_U2); break;
2019
2020                                 case Mode.U1_I1: ig.Emit (OpCodes.Conv_I1); break;
2021                                 case Mode.U1_CH: ig.Emit (OpCodes.Conv_U2); break;
2022
2023                                 case Mode.I2_I1: ig.Emit (OpCodes.Conv_I1); break;
2024                                 case Mode.I2_U1: ig.Emit (OpCodes.Conv_U1); break;
2025                                 case Mode.I2_U2: ig.Emit (OpCodes.Conv_U2); break;
2026                                 case Mode.I2_U4: ig.Emit (OpCodes.Conv_U4); break;
2027                                 case Mode.I2_U8: ig.Emit (OpCodes.Conv_I8); break;
2028                                 case Mode.I2_CH: ig.Emit (OpCodes.Conv_U2); break;
2029
2030                                 case Mode.U2_I1: ig.Emit (OpCodes.Conv_I1); break;
2031                                 case Mode.U2_U1: ig.Emit (OpCodes.Conv_U1); break;
2032                                 case Mode.U2_I2: ig.Emit (OpCodes.Conv_I2); break;
2033                                 case Mode.U2_CH: /* nothing */ break;
2034
2035                                 case Mode.I4_I1: ig.Emit (OpCodes.Conv_I1); break;
2036                                 case Mode.I4_U1: ig.Emit (OpCodes.Conv_U1); break;
2037                                 case Mode.I4_I2: ig.Emit (OpCodes.Conv_I2); break;
2038                                 case Mode.I4_U4: /* nothing */ break;
2039                                 case Mode.I4_U2: ig.Emit (OpCodes.Conv_U2); break;
2040                                 case Mode.I4_U8: ig.Emit (OpCodes.Conv_I8); break;
2041                                 case Mode.I4_CH: ig.Emit (OpCodes.Conv_U2); break;
2042
2043                                 case Mode.U4_I1: ig.Emit (OpCodes.Conv_I1); break;
2044                                 case Mode.U4_U1: ig.Emit (OpCodes.Conv_U1); break;
2045                                 case Mode.U4_I2: ig.Emit (OpCodes.Conv_I2); break;
2046                                 case Mode.U4_U2: ig.Emit (OpCodes.Conv_U2); break;
2047                                 case Mode.U4_I4: /* nothing */ break;
2048                                 case Mode.U4_CH: ig.Emit (OpCodes.Conv_U2); break;
2049
2050                                 case Mode.I8_I1: ig.Emit (OpCodes.Conv_I1); break;
2051                                 case Mode.I8_U1: ig.Emit (OpCodes.Conv_U1); break;
2052                                 case Mode.I8_I2: ig.Emit (OpCodes.Conv_I2); break;
2053                                 case Mode.I8_U2: ig.Emit (OpCodes.Conv_U2); break;
2054                                 case Mode.I8_I4: ig.Emit (OpCodes.Conv_I4); break;
2055                                 case Mode.I8_U4: ig.Emit (OpCodes.Conv_U4); break;
2056                                 case Mode.I8_U8: /* nothing */ break;
2057                                 case Mode.I8_CH: ig.Emit (OpCodes.Conv_U2); break;
2058
2059                                 case Mode.U8_I1: ig.Emit (OpCodes.Conv_I1); break;
2060                                 case Mode.U8_U1: ig.Emit (OpCodes.Conv_U1); break;
2061                                 case Mode.U8_I2: ig.Emit (OpCodes.Conv_I2); break;
2062                                 case Mode.U8_U2: ig.Emit (OpCodes.Conv_U2); break;
2063                                 case Mode.U8_I4: ig.Emit (OpCodes.Conv_I4); break;
2064                                 case Mode.U8_U4: ig.Emit (OpCodes.Conv_U4); break;
2065                                 case Mode.U8_I8: /* nothing */ break;
2066                                 case Mode.U8_CH: ig.Emit (OpCodes.Conv_U2); break;
2067
2068                                 case Mode.CH_I1: ig.Emit (OpCodes.Conv_I1); break;
2069                                 case Mode.CH_U1: ig.Emit (OpCodes.Conv_U1); break;
2070                                 case Mode.CH_I2: ig.Emit (OpCodes.Conv_I2); break;
2071
2072                                 case Mode.R4_I1: ig.Emit (OpCodes.Conv_I1); break;
2073                                 case Mode.R4_U1: ig.Emit (OpCodes.Conv_U1); break;
2074                                 case Mode.R4_I2: ig.Emit (OpCodes.Conv_I2); break;
2075                                 case Mode.R4_U2: ig.Emit (OpCodes.Conv_U2); break;
2076                                 case Mode.R4_I4: ig.Emit (OpCodes.Conv_I4); break;
2077                                 case Mode.R4_U4: ig.Emit (OpCodes.Conv_U4); break;
2078                                 case Mode.R4_I8: ig.Emit (OpCodes.Conv_I8); break;
2079                                 case Mode.R4_U8: ig.Emit (OpCodes.Conv_U8); break;
2080                                 case Mode.R4_CH: ig.Emit (OpCodes.Conv_U2); break;
2081
2082                                 case Mode.R8_I1: ig.Emit (OpCodes.Conv_I1); break;
2083                                 case Mode.R8_U1: ig.Emit (OpCodes.Conv_U1); break;
2084                                 case Mode.R8_I2: ig.Emit (OpCodes.Conv_I2); break;
2085                                 case Mode.R8_U2: ig.Emit (OpCodes.Conv_U2); break;
2086                                 case Mode.R8_I4: ig.Emit (OpCodes.Conv_I4); break;
2087                                 case Mode.R8_U4: ig.Emit (OpCodes.Conv_U4); break;
2088                                 case Mode.R8_I8: ig.Emit (OpCodes.Conv_I8); break;
2089                                 case Mode.R8_U8: ig.Emit (OpCodes.Conv_U8); break;
2090                                 case Mode.R8_CH: ig.Emit (OpCodes.Conv_U2); break;
2091                                 case Mode.R8_R4: ig.Emit (OpCodes.Conv_R4); break;
2092                                 }
2093                         }
2094                 }
2095         }
2096
2097         public class OpcodeCast : TypeCast {
2098                 readonly OpCode op;
2099
2100                 public OpcodeCast (Expression child, Type return_type, OpCode op)
2101                         : base (child, return_type)
2102                 {
2103                         this.op = op;
2104                 }
2105
2106                 public override Expression DoResolve (EmitContext ec)
2107                 {
2108                         // This should never be invoked, we are born in fully
2109                         // initialized state.
2110
2111                         return this;
2112                 }
2113
2114                 public override void Emit (EmitContext ec)
2115                 {
2116                         base.Emit (ec);
2117                         ec.ig.Emit (op);
2118                 }
2119
2120                 public Type UnderlyingType {
2121                         get { return child.Type; }
2122                 }
2123         }
2124
2125         /// <summary>
2126         ///   This kind of cast is used to encapsulate a child and cast it
2127         ///   to the class requested
2128         /// </summary>
2129         public sealed class ClassCast : TypeCast {
2130                 Type child_generic_parameter;
2131
2132                 public ClassCast (Expression child, Type return_type)
2133                         : base (child, return_type)
2134
2135                 {
2136                         if (TypeManager.IsGenericParameter (child.Type))
2137                                 child_generic_parameter = child.Type;
2138                 }
2139
2140                 public override Expression DoResolve (EmitContext ec)
2141                 {
2142                         // This should never be invoked, we are born in fully
2143                         // initialized state.
2144
2145                         return this;
2146                 }
2147
2148                 public override void Emit (EmitContext ec)
2149                 {
2150                         base.Emit (ec);
2151
2152                         if (child_generic_parameter != null)
2153                                 ec.ig.Emit (OpCodes.Box, child_generic_parameter);
2154
2155 #if GMCS_SOURCE
2156                         if (type.IsGenericParameter)
2157                                 ec.ig.Emit (OpCodes.Unbox_Any, type);
2158                         else
2159 #endif
2160                                 ec.ig.Emit (OpCodes.Castclass, type);
2161                 }
2162
2163                 public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
2164                 {
2165                         type = storey.MutateType (type);
2166                         if (child_generic_parameter != null)
2167                                 child_generic_parameter = storey.MutateGenericArgument (child_generic_parameter);
2168
2169                         base.MutateHoistedGenericType (storey);
2170                 }
2171         }
2172
2173         //
2174         // Created during resolving pahse when an expression is wrapped or constantified
2175         // and original expression can be used later (e.g. for expression trees)
2176         //
2177         public class ReducedExpression : Expression
2178         {
2179                 sealed class ReducedConstantExpression : EmptyConstantCast
2180                 {
2181                         readonly Expression orig_expr;
2182
2183                         public ReducedConstantExpression (Constant expr, Expression orig_expr)
2184                                 : base (expr, expr.Type)
2185                         {
2186                                 this.orig_expr = orig_expr;
2187                         }
2188
2189                         public override Constant ConvertImplicitly (Type target_type)
2190                         {
2191                                 Constant c = base.ConvertImplicitly (target_type);
2192                                 if (c != null)
2193                                         c = new ReducedConstantExpression (c, orig_expr);
2194                                 return c;
2195                         }
2196
2197                         public override Expression CreateExpressionTree (EmitContext ec)
2198                         {
2199                                 return orig_expr.CreateExpressionTree (ec);
2200                         }
2201
2202                         public override bool GetAttributableValue (EmitContext ec, Type value_type, out object value)
2203                         {
2204                                 //
2205                                 // Even if resolved result is a constant original expression was not
2206                                 // and attribute accepts constants only
2207                                 //
2208                                 Attribute.Error_AttributeArgumentNotValid (loc);
2209                                 value = null;
2210                                 return false;
2211                         }
2212
2213                         public override Constant ConvertExplicitly (bool in_checked_context, Type target_type)
2214                         {
2215                                 Constant c = base.ConvertExplicitly (in_checked_context, target_type);
2216                                 if (c != null)
2217                                         c = new ReducedConstantExpression (c, orig_expr);
2218                                 return c;
2219                         }
2220                 }
2221
2222                 readonly Expression expr, orig_expr;
2223
2224                 private ReducedExpression (Expression expr, Expression orig_expr)
2225                 {
2226                         this.expr = expr;
2227                         this.orig_expr = orig_expr;
2228                         this.loc = orig_expr.Location;
2229                 }
2230
2231                 public static Constant Create (Constant expr, Expression original_expr)
2232                 {
2233                         return new ReducedConstantExpression (expr, original_expr);
2234                 }
2235
2236                 public static Expression Create (Expression expr, Expression original_expr)
2237                 {
2238                         Constant c = expr as Constant;
2239                         if (c != null)
2240                                 return Create (c, original_expr);
2241
2242                         return new ReducedExpression (expr, original_expr);
2243                 }
2244
2245                 public override Expression CreateExpressionTree (EmitContext ec)
2246                 {
2247                         return orig_expr.CreateExpressionTree (ec);
2248                 }
2249
2250                 public override Expression DoResolve (EmitContext ec)
2251                 {
2252                         eclass = expr.eclass;
2253                         type = expr.Type;
2254                         return this;
2255                 }
2256
2257                 public override void Emit (EmitContext ec)
2258                 {
2259                         expr.Emit (ec);
2260                 }
2261
2262                 public override void EmitBranchable (EmitContext ec, Label target, bool on_true)
2263                 {
2264                         expr.EmitBranchable (ec, target, on_true);
2265                 }
2266
2267                 public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
2268                 {
2269                         expr.MutateHoistedGenericType (storey);
2270                 }
2271         }
2272
2273         //
2274         // Unresolved type name expressions
2275         //
2276         public abstract class ATypeNameExpression : FullNamedExpression
2277         {
2278                 public readonly string Name;
2279                 protected TypeArguments targs;
2280
2281                 protected ATypeNameExpression (string name, Location l)
2282                 {
2283                         Name = name;
2284                         loc = l;
2285                 }
2286
2287                 protected ATypeNameExpression (string name, TypeArguments targs, Location l)
2288                 {
2289                         Name = name;
2290                         this.targs = targs;
2291                         loc = l;
2292                 }
2293
2294                 public bool HasTypeArguments {
2295                         get {
2296                                 return targs != null;
2297                         }
2298                 }
2299
2300                 public override string GetSignatureForError ()
2301                 {
2302                         if (targs != null) {
2303                                 return TypeManager.RemoveGenericArity (Name) + "<" +
2304                                         targs.GetSignatureForError () + ">";
2305                         }
2306
2307                         return Name;
2308                 }
2309         }
2310
2311         /// <summary>
2312         ///   SimpleName expressions are formed of a single word and only happen at the beginning
2313         ///   of a dotted-name.
2314         /// </summary>
2315         public class SimpleName : ATypeNameExpression {
2316                 bool in_transit;
2317
2318                 public SimpleName (string name, Location l)
2319                         : base (name, l)
2320                 {
2321                 }
2322
2323                 public SimpleName (string name, TypeArguments args, Location l)
2324                         : base (name, args, l)
2325                 {
2326                 }
2327
2328                 public SimpleName (string name, TypeParameter[] type_params, Location l)
2329                         : base (name, l)
2330                 {
2331                         targs = new TypeArguments (l);
2332                         foreach (TypeParameter type_param in type_params)
2333                                 targs.Add (new TypeParameterExpr (type_param, l));
2334                 }
2335
2336                 public static string RemoveGenericArity (string name)
2337                 {
2338                         int start = 0;
2339                         StringBuilder sb = null;
2340                         do {
2341                                 int pos = name.IndexOf ('`', start);
2342                                 if (pos < 0) {
2343                                         if (start == 0)
2344                                                 return name;
2345
2346                                         sb.Append (name.Substring (start));
2347                                         break;
2348                                 }
2349
2350                                 if (sb == null)
2351                                         sb = new StringBuilder ();
2352                                 sb.Append (name.Substring (start, pos-start));
2353
2354                                 pos++;
2355                                 while ((pos < name.Length) && Char.IsNumber (name [pos]))
2356                                         pos++;
2357
2358                                 start = pos;
2359                         } while (start < name.Length);
2360
2361                         return sb.ToString ();
2362                 }
2363
2364                 public SimpleName GetMethodGroup ()
2365                 {
2366                         return new SimpleName (RemoveGenericArity (Name), targs, loc);
2367                 }
2368
2369                 public static void Error_ObjectRefRequired (EmitContext ec, Location l, string name)
2370                 {
2371                         if (ec.IsInFieldInitializer)
2372                                 Report.Error (236, l,
2373                                         "A field initializer cannot reference the nonstatic field, method, or property `{0}'",
2374                                         name);
2375                         else
2376                                 Report.Error (
2377                                         120, l, "`{0}': An object reference is required for the nonstatic field, method or property",
2378                                         name);
2379                 }
2380
2381                 public bool IdenticalNameAndTypeName (EmitContext ec, Expression resolved_to, Location loc)
2382                 {
2383                         return resolved_to != null && resolved_to.Type != null &&
2384                                 resolved_to.Type.Name == Name &&
2385                                 (ec.DeclContainer.LookupNamespaceOrType (Name, loc, /* ignore_cs0104 = */ true) != null);
2386                 }
2387
2388                 public override Expression DoResolve (EmitContext ec)
2389                 {
2390                         return SimpleNameResolve (ec, null, false);
2391                 }
2392
2393                 public override Expression DoResolveLValue (EmitContext ec, Expression right_side)
2394                 {
2395                         return SimpleNameResolve (ec, right_side, false);
2396                 }
2397
2398
2399                 public Expression DoResolve (EmitContext ec, bool intermediate)
2400                 {
2401                         return SimpleNameResolve (ec, null, intermediate);
2402                 }
2403
2404                 static bool IsNestedChild (Type t, Type parent)
2405                 {
2406                         while (parent != null) {
2407                                 if (TypeManager.IsNestedChildOf (t, TypeManager.DropGenericTypeArguments (parent)))
2408                                         return true;
2409
2410                                 parent = parent.BaseType;
2411                         }
2412
2413                         return false;
2414                 }
2415
2416                 FullNamedExpression ResolveNested (IResolveContext ec, Type t)
2417                 {
2418                         if (!TypeManager.IsGenericTypeDefinition (t) && !TypeManager.IsGenericType (t))
2419                                 return null;
2420
2421                         DeclSpace ds = ec.DeclContainer;
2422                         while (ds != null && !IsNestedChild (t, ds.TypeBuilder))
2423                                 ds = ds.Parent;
2424
2425                         if (ds == null)
2426                                 return null;
2427
2428                         Type[] gen_params = TypeManager.GetTypeArguments (t);
2429
2430                         int arg_count = targs != null ? targs.Count : 0;
2431
2432                         for (; (ds != null) && ds.IsGeneric; ds = ds.Parent) {
2433                                 if (arg_count + ds.CountTypeParameters == gen_params.Length) {
2434                                         TypeArguments new_args = new TypeArguments (loc);
2435                                         foreach (TypeParameter param in ds.TypeParameters)
2436                                                 new_args.Add (new TypeParameterExpr (param, loc));
2437
2438                                         if (targs != null)
2439                                                 new_args.Add (targs);
2440
2441                                         return new ConstructedType (t, new_args, loc);
2442                                 }
2443                         }
2444
2445                         return null;
2446                 }
2447
2448                 public override FullNamedExpression ResolveAsTypeStep (IResolveContext ec, bool silent)
2449                 {
2450                         FullNamedExpression fne = ec.GenericDeclContainer.LookupGeneric (Name, loc);
2451                         if (fne != null)
2452                                 return fne.ResolveAsTypeStep (ec, silent);
2453
2454                         int errors = Report.Errors;
2455                         fne = ec.DeclContainer.LookupNamespaceOrType (Name, loc, /*ignore_cs0104=*/ false);
2456
2457                         if (fne != null) {
2458                                 if (fne.Type == null)
2459                                         return fne;
2460
2461                                 FullNamedExpression nested = ResolveNested (ec, fne.Type);
2462                                 if (nested != null)
2463                                         return nested.ResolveAsTypeStep (ec, false);
2464
2465                                 if (targs != null) {
2466                                         ConstructedType ct = new ConstructedType (fne, targs, loc);
2467                                         return ct.ResolveAsTypeStep (ec, false);
2468                                 }
2469
2470                                 return fne;
2471                         }
2472
2473                         if (silent || errors != Report.Errors)
2474                                 return null;
2475
2476                         Error_TypeOrNamespaceNotFound (ec);
2477                         return null;
2478                 }
2479
2480                 protected virtual void Error_TypeOrNamespaceNotFound (IResolveContext ec)
2481                 {
2482                         MemberCore mc = ec.DeclContainer.GetDefinition (Name);
2483                         if (mc != null) {
2484                                 Error_UnexpectedKind (ec.DeclContainer, "type", GetMemberType (mc), loc);
2485                                 return;
2486                         }
2487
2488                         string ns = ec.DeclContainer.NamespaceEntry.NS.Name;
2489                         string fullname = (ns.Length > 0) ? ns + "." + Name : Name;
2490                         foreach (Assembly a in RootNamespace.Global.Assemblies) {
2491                                 Type type = a.GetType (fullname);
2492                                 if (type != null) {
2493                                         Report.SymbolRelatedToPreviousError (type);
2494                                         Expression.ErrorIsInaccesible (loc, TypeManager.CSharpName (type));
2495                                         return;
2496                                 }
2497                         }
2498
2499                         Type t = ec.DeclContainer.LookupAnyGeneric (Name);
2500                         if (t != null) {
2501                                 Namespace.Error_InvalidNumberOfTypeArguments (t, loc);
2502                                 return;
2503                         }
2504
2505                         if (targs != null) {
2506                                 FullNamedExpression retval = ec.DeclContainer.LookupNamespaceOrType (SimpleName.RemoveGenericArity (Name), loc, true);
2507                                 if (retval != null) {
2508                                         Namespace.Error_TypeArgumentsCannotBeUsed (retval.Type, loc);
2509                                         return;
2510                                 }
2511                         }
2512
2513                         NamespaceEntry.Error_NamespaceNotFound (loc, Name);
2514                 }
2515
2516                 // TODO: I am still not convinced about this. If someone else will need it
2517                 // implement this as virtual property in MemberCore hierarchy
2518                 public static string GetMemberType (MemberCore mc)
2519                 {
2520                         if (mc is Property)
2521                                 return "property";
2522                         if (mc is Indexer)
2523                                 return "indexer";
2524                         if (mc is FieldBase)
2525                                 return "field";
2526                         if (mc is MethodCore)
2527                                 return "method";
2528                         if (mc is EnumMember)
2529                                 return "enum";
2530                         if (mc is Event)
2531                                 return "event";
2532
2533                         return "type";
2534                 }
2535
2536                 Expression SimpleNameResolve (EmitContext ec, Expression right_side, bool intermediate)
2537                 {
2538                         if (in_transit)
2539                                 return null;
2540
2541                         in_transit = true;
2542                         Expression e = DoSimpleNameResolve (ec, right_side, intermediate);
2543                         in_transit = false;
2544
2545                         if (e == null)
2546                                 return null;
2547
2548                         if (ec.CurrentBlock == null || ec.CurrentBlock.CheckInvariantMeaningInBlock (Name, e, Location))
2549                                 return e;
2550
2551                         return null;
2552                 }
2553
2554                 /// <remarks>
2555                 ///   7.5.2: Simple Names.
2556                 ///
2557                 ///   Local Variables and Parameters are handled at
2558                 ///   parse time, so they never occur as SimpleNames.
2559                 ///
2560                 ///   The `intermediate' flag is used by MemberAccess only
2561                 ///   and it is used to inform us that it is ok for us to
2562                 ///   avoid the static check, because MemberAccess might end
2563                 ///   up resolving the Name as a Type name and the access as
2564                 ///   a static type access.
2565                 ///
2566                 ///   ie: Type Type; .... { Type.GetType (""); }
2567                 ///
2568                 ///   Type is both an instance variable and a Type;  Type.GetType
2569                 ///   is the static method not an instance method of type.
2570                 /// </remarks>
2571                 Expression DoSimpleNameResolve (EmitContext ec, Expression right_side, bool intermediate)
2572                 {
2573                         Expression e = null;
2574
2575                         //
2576                         // Stage 1: Performed by the parser (binding to locals or parameters).
2577                         //
2578                         Block current_block = ec.CurrentBlock;
2579                         if (current_block != null){
2580                                 LocalInfo vi = current_block.GetLocalInfo (Name);
2581                                 if (vi != null){
2582                                         if (targs != null) {
2583                                                 Report.Error (307, loc,
2584                                                               "The variable `{0}' cannot be used with type arguments",
2585                                                               Name);
2586                                                 return null;
2587                                         }
2588
2589                                         LocalVariableReference var = new LocalVariableReference (ec.CurrentBlock, Name, loc);
2590                                         if (right_side != null) {
2591                                                 return var.ResolveLValue (ec, right_side, loc);
2592                                         } else {
2593                                                 ResolveFlags rf = ResolveFlags.VariableOrValue;
2594                                                 if (intermediate)
2595                                                         rf |= ResolveFlags.DisableFlowAnalysis;
2596                                                 return var.Resolve (ec, rf);
2597                                         }
2598                                 }
2599
2600                                 ParameterReference pref = current_block.Toplevel.GetParameterReference (Name, loc);
2601                                 if (pref != null) {
2602                                         if (targs != null) {
2603                                                 Report.Error (307, loc,
2604                                                               "The variable `{0}' cannot be used with type arguments",
2605                                                               Name);
2606                                                 return null;
2607                                         }
2608
2609                                         if (right_side != null)
2610                                                 return pref.ResolveLValue (ec, right_side, loc);
2611                                         else
2612                                                 return pref.Resolve (ec);
2613                                 }
2614
2615                                 Expression expr = current_block.Toplevel.GetTransparentIdentifier (Name);
2616                                 if (expr != null) {
2617                                         if (right_side != null)
2618                                                 return expr.ResolveLValue (ec, right_side, loc);
2619                                         return expr.Resolve (ec);
2620                                 }
2621                         }
2622
2623                         //
2624                         // Stage 2: Lookup members
2625                         //
2626
2627                         Type almost_matched_type = null;
2628                         ArrayList almost_matched = null;
2629                         for (DeclSpace lookup_ds = ec.DeclContainer; lookup_ds != null; lookup_ds = lookup_ds.Parent) {
2630                                 // either RootDeclSpace or GenericMethod
2631                                 if (lookup_ds.TypeBuilder == null)
2632                                         continue;
2633
2634                                 e = MemberLookup (ec.ContainerType, lookup_ds.TypeBuilder, Name, loc);
2635                                 if (e != null) {
2636                                         PropertyExpr pe = e as PropertyExpr;
2637                                         if (pe != null) {
2638                                                 AParametersCollection param = TypeManager.GetParameterData (pe.PropertyInfo);
2639
2640                                                 // since TypeManager.MemberLookup doesn't know if we're doing a lvalue access or not,
2641                                                 // it doesn't know which accessor to check permissions against
2642                                                 if (param.IsEmpty && pe.IsAccessibleFrom (ec.ContainerType, right_side != null))
2643                                                         break;
2644                                         } else if (e is EventExpr) {
2645                                                 if (((EventExpr) e).IsAccessibleFrom (ec.ContainerType))
2646                                                         break;
2647                                         } else {
2648                                                 break;
2649                                         }
2650                                         e = null;
2651                                 }
2652
2653                                 if (almost_matched == null && almost_matched_members.Count > 0) {
2654                                         almost_matched_type = lookup_ds.TypeBuilder;
2655                                         almost_matched = (ArrayList) almost_matched_members.Clone ();
2656                                 }
2657                         }
2658
2659                         if (e == null) {
2660                                 if (almost_matched == null && almost_matched_members.Count > 0) {
2661                                         almost_matched_type = ec.ContainerType;
2662                                         almost_matched = (ArrayList) almost_matched_members.Clone ();
2663                                 }
2664                                 e = ResolveAsTypeStep (ec, true);
2665                         }
2666
2667                         if (e == null) {
2668                                 if (current_block != null) {
2669                                         IKnownVariable ikv = current_block.Explicit.GetKnownVariable (Name);
2670                                         if (ikv != null) {
2671                                                 LocalInfo li = ikv as LocalInfo;
2672                                                 // Supress CS0219 warning
2673                                                 if (li != null)
2674                                                         li.Used = true;
2675
2676                                                 Error_VariableIsUsedBeforeItIsDeclared (Name);
2677                                                 return null;
2678                                         }
2679                                 }
2680
2681                                 if (RootContext.EvalMode){
2682                                         FieldInfo fi = Evaluator.LookupField (Name);
2683                                         if (fi != null)
2684                                                 return new FieldExpr (fi, loc);
2685                                 }
2686
2687                                 if (almost_matched != null)
2688                                         almost_matched_members = almost_matched;
2689                                 if (almost_matched_type == null)
2690                                         almost_matched_type = ec.ContainerType;
2691                                 Error_MemberLookupFailed (ec.ContainerType, null, almost_matched_type, Name,
2692                                         ec.DeclContainer.Name, AllMemberTypes, AllBindingFlags);
2693                                 return null;
2694                         }
2695
2696                         if (e is TypeExpr) {
2697                                 if (targs == null)
2698                                         return e;
2699
2700                                 ConstructedType ct = new ConstructedType (
2701                                         e.Type, targs, loc);
2702                                 return ct.ResolveAsTypeStep (ec, false);
2703                         }
2704
2705                         if (e is MemberExpr) {
2706                                 MemberExpr me = (MemberExpr) e;
2707
2708                                 Expression left;
2709                                 if (me.IsInstance) {
2710                                         if (ec.IsStatic || ec.IsInFieldInitializer) {
2711                                                 //
2712                                                 // Note that an MemberExpr can be both IsInstance and IsStatic.
2713                                                 // An unresolved MethodGroupExpr can contain both kinds of methods
2714                                                 // and each predicate is true if the MethodGroupExpr contains
2715                                                 // at least one of that kind of method.
2716                                                 //
2717
2718                                                 if (!me.IsStatic &&
2719                                                     (!intermediate || !IdenticalNameAndTypeName (ec, me, loc))) {
2720                                                         Error_ObjectRefRequired (ec, loc, me.GetSignatureForError ());
2721                                                         return null;
2722                                                 }
2723
2724                                                 //
2725                                                 // Pass the buck to MemberAccess and Invocation.
2726                                                 //
2727                                                 left = EmptyExpression.Null;
2728                                         } else {
2729                                                 left = ec.GetThis (loc);
2730                                         }
2731                                 } else {
2732                                         left = new TypeExpression (ec.ContainerType, loc);
2733                                 }
2734
2735                                 me = me.ResolveMemberAccess (ec, left, loc, null);
2736                                 if (me == null)
2737                                         return null;
2738
2739                                 if (targs != null) {
2740                                         targs.Resolve (ec);
2741                                         me.SetTypeArguments (targs);
2742                                 }
2743
2744                                 if (!me.IsStatic && (me.InstanceExpression != null) &&
2745                                     TypeManager.IsNestedFamilyAccessible (me.InstanceExpression.Type, me.DeclaringType) &&
2746                                     me.InstanceExpression.Type != me.DeclaringType &&
2747                                     !TypeManager.IsFamilyAccessible (me.InstanceExpression.Type, me.DeclaringType) &&
2748                                     (!intermediate || !IdenticalNameAndTypeName (ec, e, loc))) {
2749                                         Report.Error (38, loc, "Cannot access a nonstatic member of outer type `{0}' via nested type `{1}'",
2750                                                 TypeManager.CSharpName (me.DeclaringType), TypeManager.CSharpName (me.InstanceExpression.Type));
2751                                         return null;
2752                                 }
2753
2754                                 return (right_side != null)
2755                                         ? me.DoResolveLValue (ec, right_side)
2756                                         : me.DoResolve (ec);
2757                         }
2758
2759                         return e;
2760                 }
2761
2762                 protected override void CloneTo (CloneContext clonectx, Expression target)
2763                 {
2764                         // CloneTo: Nothing, we do not keep any state on this expression
2765                 }
2766         }
2767
2768         /// <summary>
2769         ///   Represents a namespace or a type.  The name of the class was inspired by
2770         ///   section 10.8.1 (Fully Qualified Names).
2771         /// </summary>
2772         public abstract class FullNamedExpression : Expression {
2773
2774                 public override Expression CreateExpressionTree (EmitContext ec)
2775                 {
2776                         throw new NotSupportedException ("ET");
2777                 }
2778
2779                 public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
2780                 {
2781                         throw new NotSupportedException ();
2782                 }
2783
2784                 public override FullNamedExpression ResolveAsTypeStep (IResolveContext ec, bool silent)
2785                 {
2786                         return this;
2787                 }
2788
2789                 public override void Emit (EmitContext ec)
2790                 {
2791                         throw new InternalErrorException ("FullNamedExpression `{0}' found in resolved tree",
2792                                 GetSignatureForError ());
2793                 }
2794         }
2795
2796         /// <summary>
2797         ///   Expression that evaluates to a type
2798         /// </summary>
2799         public abstract class TypeExpr : FullNamedExpression {
2800                 public override FullNamedExpression ResolveAsTypeStep (IResolveContext ec, bool silent)
2801                 {
2802                         TypeExpr t = DoResolveAsTypeStep (ec);
2803                         if (t == null)
2804                                 return null;
2805
2806                         eclass = ExprClass.Type;
2807                         return t;
2808                 }
2809
2810                 override public Expression DoResolve (EmitContext ec)
2811                 {
2812                         return ResolveAsTypeTerminal (ec, false);
2813                 }
2814
2815                 public virtual bool CheckAccessLevel (DeclSpace ds)
2816                 {
2817                         return ds.CheckAccessLevel (Type);
2818                 }
2819
2820                 public virtual bool AsAccessible (DeclSpace ds)
2821                 {
2822                         return ds.IsAccessibleAs (Type);
2823                 }
2824
2825                 public virtual bool IsClass {
2826                         get { return Type.IsClass; }
2827                 }
2828
2829                 public virtual bool IsValueType {
2830                         get { return Type.IsValueType; }
2831                 }
2832
2833                 public virtual bool IsInterface {
2834                         get { return Type.IsInterface; }
2835                 }
2836
2837                 public virtual bool IsSealed {
2838                         get { return Type.IsSealed; }
2839                 }
2840
2841                 public virtual bool CanInheritFrom ()
2842                 {
2843                         if (Type == TypeManager.enum_type ||
2844                             (Type == TypeManager.value_type && RootContext.StdLib) ||
2845                             Type == TypeManager.multicast_delegate_type ||
2846                             Type == TypeManager.delegate_type ||
2847                             Type == TypeManager.array_type)
2848                                 return false;
2849
2850                         return true;
2851                 }
2852
2853                 protected abstract TypeExpr DoResolveAsTypeStep (IResolveContext ec);
2854
2855                 public override bool Equals (object obj)
2856                 {
2857                         TypeExpr tobj = obj as TypeExpr;
2858                         if (tobj == null)
2859                                 return false;
2860
2861                         return Type == tobj.Type;
2862                 }
2863
2864                 public override int GetHashCode ()
2865                 {
2866                         return Type.GetHashCode ();
2867                 }
2868
2869                 public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
2870                 {
2871                         type = storey.MutateType (type);
2872                 }
2873         }
2874
2875         /// <summary>
2876         ///   Fully resolved Expression that already evaluated to a type
2877         /// </summary>
2878         public class TypeExpression : TypeExpr {
2879                 public TypeExpression (Type t, Location l)
2880                 {
2881                         Type = t;
2882                         eclass = ExprClass.Type;
2883                         loc = l;
2884                 }
2885
2886                 protected override TypeExpr DoResolveAsTypeStep (IResolveContext ec)
2887                 {
2888                         return this;
2889                 }
2890
2891                 public override TypeExpr ResolveAsTypeTerminal (IResolveContext ec, bool silent)
2892                 {
2893                         return this;
2894                 }
2895         }
2896
2897         /// <summary>
2898         ///   Used to create types from a fully qualified name.  These are just used
2899         ///   by the parser to setup the core types.  A TypeLookupExpression is always
2900         ///   classified as a type.
2901         /// </summary>
2902         public sealed class TypeLookupExpression : TypeExpr {
2903                 readonly string name;
2904
2905                 public TypeLookupExpression (string name)
2906                 {
2907                         this.name = name;
2908                         eclass = ExprClass.Type;
2909                 }
2910
2911                 public override TypeExpr ResolveAsTypeTerminal (IResolveContext ec, bool silent)
2912                 {
2913                         // It's null for corlib compilation only
2914                         if (type == null)
2915                                 return DoResolveAsTypeStep (ec);
2916
2917                         return this;
2918                 }
2919
2920                 private class UnexpectedType
2921                 {
2922                 }
2923
2924                 // This performes recursive type lookup, providing support for generic types.
2925                 // For example, given the type:
2926                 //
2927                 // System.Collections.Generic.KeyValuePair`2[[System.Int32],[System.String]]
2928                 //
2929                 // The types will be checked in the following order:
2930                 //                                                                             _
2931                 // System                                                                       |
2932                 // System.Collections                                                           |
2933                 // System.Collections.Generic                                                   |
2934                 //                        _                                                     |
2935                 //     System              | recursive call 1                                   |
2936                 //     System.Int32       _|                                                    | main method call
2937                 //                        _                                                     |
2938                 //     System              | recursive call 2                                   |
2939                 //     System.String      _|                                                    |
2940                 //                                                                              |
2941                 // System.Collections.Generic.KeyValuePair`2[[System.Int32],[System.String]]   _|
2942                 //
2943                 private Type TypeLookup (IResolveContext ec, string name)
2944                 {
2945                         int index = 0;
2946                         int dot = 0;
2947                         bool done = false;
2948                         FullNamedExpression resolved = null;
2949                         Type type = null;
2950                         Type recursive_type = null;
2951                         while (index < name.Length) {
2952                                 if (name[index] == '[') {
2953                                         int open = index;
2954                                         int braces = 1;
2955                                         do {
2956                                                 index++;
2957                                                 if (name[index] == '[')
2958                                                         braces++;
2959                                                 else if (name[index] == ']')
2960                                                         braces--;
2961                                         } while (braces > 0);
2962                                         recursive_type = TypeLookup (ec, name.Substring (open + 1, index - open - 1));
2963                                         if (recursive_type == null || (recursive_type == typeof(UnexpectedType)))
2964                                                 return recursive_type;
2965                                 }
2966                                 else {
2967                                         if (name[index] == ',')
2968                                                 done = true;
2969                                         else if ((name[index] == '.' && !done) || (index == name.Length && name[0] != '[')) {
2970                                                 string substring = name.Substring(dot, index - dot);
2971
2972                                                 if (resolved == null)
2973                                                         resolved = RootNamespace.Global.Lookup (ec.DeclContainer, substring, Location.Null);
2974                                                 else if (resolved is Namespace)
2975                                                     resolved = (resolved as Namespace).Lookup (ec.DeclContainer, substring, Location.Null);
2976                                                 else if (type != null)
2977                                                         type = TypeManager.GetNestedType (type, substring);
2978                                                 else
2979                                                         return null;
2980
2981                                                 if (resolved == null)
2982                                                         return null;
2983                                                 else if (type == null && resolved is TypeExpr)
2984                                                         type = resolved.Type;
2985
2986                                                 dot = index + 1;
2987                                         }
2988                                 }
2989                                 index++;
2990                         }
2991                         if (name[0] != '[') {
2992                                 string substring = name.Substring(dot, index - dot);
2993
2994                                 if (type != null)
2995                                         return TypeManager.GetNestedType (type, substring);
2996
2997                                 if (resolved != null) {
2998                                         resolved = (resolved as Namespace).Lookup (ec.DeclContainer, substring, Location.Null);
2999                                         if (resolved is TypeExpr)
3000                                                 return resolved.Type;
3001
3002                                         if (resolved == null)
3003                                                 return null;
3004
3005                                         resolved.Error_UnexpectedKind (ec.DeclContainer, "type", loc);
3006                                         return typeof (UnexpectedType);
3007                                 }
3008                                 else
3009                                         return null;
3010                         }
3011                         else
3012                                 return recursive_type;
3013                         }
3014
3015                 protected override TypeExpr DoResolveAsTypeStep (IResolveContext ec)
3016                 {
3017                         Type t = TypeLookup (ec, name);
3018                         if (t == null) {
3019                                 NamespaceEntry.Error_NamespaceNotFound (loc, name);
3020                                 return null;
3021                         }
3022                         if (t == typeof(UnexpectedType))
3023                                 return null;
3024                         type = t;
3025                         return this;
3026                 }
3027
3028                 protected override void CloneTo (CloneContext clonectx, Expression target)
3029                 {
3030                         // CloneTo: Nothing, we do not keep any state on this expression
3031                 }
3032
3033                 public override string GetSignatureForError ()
3034                 {
3035                         if (type == null)
3036                                 return TypeManager.CSharpName (name);
3037
3038                         return base.GetSignatureForError ();
3039                 }
3040         }
3041
3042         /// <summary>
3043         ///   Represents an "unbound generic type", ie. typeof (Foo<>).
3044         ///   See 14.5.11.
3045         /// </summary>
3046         public class UnboundTypeExpression : TypeExpr
3047         {
3048                 MemberName name;
3049
3050                 public UnboundTypeExpression (MemberName name, Location l)
3051                 {
3052                         this.name = name;
3053                         loc = l;
3054                 }
3055
3056                 protected override void CloneTo (CloneContext clonectx, Expression target)
3057                 {
3058                         // Nothing to clone
3059                 }
3060
3061                 protected override TypeExpr DoResolveAsTypeStep (IResolveContext ec)
3062                 {
3063                         Expression expr;
3064                         if (name.Left != null) {
3065                                 Expression lexpr = name.Left.GetTypeExpression ();
3066                                 expr = new MemberAccess (lexpr, name.Basename);
3067                         } else {
3068                                 expr = new SimpleName (name.Basename, loc);
3069                         }
3070
3071                         FullNamedExpression fne = expr.ResolveAsTypeStep (ec, false);
3072                         if (fne == null)
3073                                 return null;
3074
3075                         type = fne.Type;
3076                         return new TypeExpression (type, loc);
3077                 }
3078         }
3079
3080         /// <summary>
3081         ///   This class denotes an expression which evaluates to a member
3082         ///   of a struct or a class.
3083         /// </summary>
3084         public abstract class MemberExpr : Expression
3085         {
3086                 protected bool is_base;
3087
3088                 /// <summary>
3089                 ///   The name of this member.
3090                 /// </summary>
3091                 public abstract string Name {
3092                         get;
3093                 }
3094
3095                 //
3096                 // When base.member is used
3097                 //
3098                 public bool IsBase {
3099                         get { return is_base; }
3100                         set { is_base = value; }
3101                 }
3102
3103                 /// <summary>
3104                 ///   Whether this is an instance member.
3105                 /// </summary>
3106                 public abstract bool IsInstance {
3107                         get;
3108                 }
3109
3110                 /// <summary>
3111                 ///   Whether this is a static member.
3112                 /// </summary>
3113                 public abstract bool IsStatic {
3114                         get;
3115                 }
3116
3117                 /// <summary>
3118                 ///   The type which declares this member.
3119                 /// </summary>
3120                 public abstract Type DeclaringType {
3121                         get;
3122                 }
3123
3124                 /// <summary>
3125                 ///   The instance expression associated with this member, if it's a
3126                 ///   non-static member.
3127                 /// </summary>
3128                 public Expression InstanceExpression;
3129
3130                 public static void error176 (Location loc, string name)
3131                 {
3132                         Report.Error (176, loc, "Static member `{0}' cannot be accessed " +
3133                                       "with an instance reference, qualify it with a type name instead", name);
3134                 }
3135
3136                 public static void Error_BaseAccessInExpressionTree (Location loc)
3137                 {
3138                         Report.Error (831, loc, "An expression tree may not contain a base access");
3139                 }
3140
3141                 public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
3142                 {
3143                         if (InstanceExpression != null)
3144                                 InstanceExpression.MutateHoistedGenericType (storey);
3145                 }
3146
3147                 // TODO: possible optimalization
3148                 // Cache resolved constant result in FieldBuilder <-> expression map
3149                 public virtual MemberExpr ResolveMemberAccess (EmitContext ec, Expression left, Location loc,
3150                                                                SimpleName original)
3151                 {
3152                         //
3153                         // Precondition:
3154                         //   original == null || original.Resolve (...) ==> left
3155                         //
3156
3157                         if (left is TypeExpr) {
3158                                 left = left.ResolveAsTypeTerminal (ec, true);
3159                                 if (left == null)
3160                                         return null;
3161
3162                                 if (!IsStatic) {
3163                                         SimpleName.Error_ObjectRefRequired (ec, loc, GetSignatureForError ());
3164                                         return null;
3165                                 }
3166
3167                                 return this;
3168                         }
3169
3170                         if (!IsInstance) {
3171                                 if (original != null && original.IdenticalNameAndTypeName (ec, left, loc))
3172                                         return this;
3173
3174                                 return ResolveExtensionMemberAccess (left);
3175                         }
3176
3177                         InstanceExpression = left;
3178                         return this;
3179                 }
3180
3181                 protected virtual MemberExpr ResolveExtensionMemberAccess (Expression left)
3182                 {
3183                         error176 (loc, GetSignatureForError ());
3184                         return this;
3185                 }
3186
3187                 protected void EmitInstance (EmitContext ec, bool prepare_for_load)
3188                 {
3189                         if (IsStatic)
3190                                 return;
3191
3192                         if (InstanceExpression == EmptyExpression.Null) {
3193                                 SimpleName.Error_ObjectRefRequired (ec, loc, GetSignatureForError ());
3194                                 return;
3195                         }
3196
3197                         if (InstanceExpression.Type.IsValueType) {
3198                                 if (InstanceExpression is IMemoryLocation) {
3199                                         ((IMemoryLocation) InstanceExpression).AddressOf (ec, AddressOp.LoadStore);
3200                                 } else {
3201                                         LocalTemporary t = new LocalTemporary (InstanceExpression.Type);
3202                                         InstanceExpression.Emit (ec);
3203                                         t.Store (ec);
3204                                         t.AddressOf (ec, AddressOp.Store);
3205                                 }
3206                         } else
3207                                 InstanceExpression.Emit (ec);
3208
3209                         if (prepare_for_load)
3210                                 ec.ig.Emit (OpCodes.Dup);
3211                 }
3212
3213                 public virtual void SetTypeArguments (TypeArguments ta)
3214                 {
3215                         // TODO: need to get correct member type
3216                         Report.Error (307, loc, "The property `{0}' cannot be used with type arguments",
3217                                 GetSignatureForError ());
3218                 }
3219         }
3220
3221         ///
3222         /// Represents group of extension methods
3223         ///
3224         public class ExtensionMethodGroupExpr : MethodGroupExpr
3225         {
3226                 readonly NamespaceEntry namespace_entry;
3227                 public Expression ExtensionExpression;
3228                 Argument extension_argument;
3229
3230                 public ExtensionMethodGroupExpr (ArrayList list, NamespaceEntry n, Type extensionType, Location l)
3231                         : base (list, extensionType, l)
3232                 {
3233                         this.namespace_entry = n;
3234                 }
3235
3236                 public override bool IsStatic {
3237                         get { return true; }
3238                 }
3239
3240                 public bool IsTopLevel {
3241                         get { return namespace_entry == null; }
3242                 }
3243
3244                 public override void EmitArguments (EmitContext ec, ArrayList arguments)
3245                 {
3246                         if (arguments == null)
3247                                 arguments = new ArrayList (1);
3248                         arguments.Insert (0, extension_argument);
3249                         base.EmitArguments (ec, arguments);
3250                 }
3251
3252                 public override void EmitCall (EmitContext ec, ArrayList arguments)
3253                 {
3254                         if (arguments == null)
3255                                 arguments = new ArrayList (1);
3256                         arguments.Insert (0, extension_argument);
3257                         base.EmitCall (ec, arguments);
3258                 }
3259
3260                 public override MethodGroupExpr OverloadResolve (EmitContext ec, ref ArrayList arguments, bool may_fail, Location loc)
3261                 {
3262                         if (arguments == null)
3263                                 arguments = new ArrayList (1);
3264
3265                         arguments.Insert (0, new Argument (ExtensionExpression));
3266                         MethodGroupExpr mg = ResolveOverloadExtensions (ec, arguments, namespace_entry, loc);
3267
3268                         // Store resolved argument and restore original arguments
3269                         if (mg != null)
3270                                 ((ExtensionMethodGroupExpr)mg).extension_argument = (Argument)arguments [0];
3271                         arguments.RemoveAt (0);
3272
3273                         return mg;
3274                 }
3275
3276                 MethodGroupExpr ResolveOverloadExtensions (EmitContext ec, ArrayList arguments, NamespaceEntry ns, Location loc)
3277                 {
3278                         // Use normal resolve rules
3279                         MethodGroupExpr mg = base.OverloadResolve (ec, ref arguments, ns != null, loc);
3280                         if (mg != null)
3281                                 return mg;
3282
3283                         if (ns == null)
3284                                 return null;
3285
3286                         // Search continues
3287                         ExtensionMethodGroupExpr e = ns.LookupExtensionMethod (type, null, Name, loc);
3288                         if (e == null)
3289                                 return base.OverloadResolve (ec, ref arguments, false, loc);
3290
3291                         e.ExtensionExpression = ExtensionExpression;
3292                         e.SetTypeArguments (type_arguments);
3293                         return e.ResolveOverloadExtensions (ec, arguments, e.namespace_entry, loc);
3294                 }
3295         }
3296
3297         /// <summary>
3298         ///   MethodGroupExpr represents a group of method candidates which
3299         ///   can be resolved to the best method overload
3300         /// </summary>
3301         public class MethodGroupExpr : MemberExpr
3302         {
3303                 public interface IErrorHandler
3304                 {
3305                         bool NoExactMatch (EmitContext ec, MethodBase method);
3306                 }
3307
3308                 public IErrorHandler CustomErrorHandler;
3309                 public MethodBase [] Methods;
3310                 MethodBase best_candidate;
3311                 // TODO: make private
3312                 public TypeArguments type_arguments;
3313                 bool identical_type_name;
3314                 Type delegate_type;
3315
3316                 public MethodGroupExpr (MemberInfo [] mi, Type type, Location l)
3317                         : this (type, l)
3318                 {
3319                         Methods = new MethodBase [mi.Length];
3320                         mi.CopyTo (Methods, 0);
3321                 }
3322
3323                 public MethodGroupExpr (ArrayList list, Type type, Location l)
3324                         : this (type, l)
3325                 {
3326                         try {
3327                                 Methods = (MethodBase[])list.ToArray (typeof (MethodBase));
3328                         } catch {
3329                                 foreach (MemberInfo m in list){
3330                                         if (!(m is MethodBase)){
3331                                                 Console.WriteLine ("Name " + m.Name);
3332                                                 Console.WriteLine ("Found a: " + m.GetType ().FullName);
3333                                         }
3334                                 }
3335                                 throw;
3336                         }
3337
3338
3339                 }
3340
3341                 protected MethodGroupExpr (Type type, Location loc)
3342                 {
3343                         this.loc = loc;
3344                         eclass = ExprClass.MethodGroup;
3345                         this.type = type;
3346                 }
3347
3348                 public override Type DeclaringType {
3349                         get {
3350                                 //
3351                                 // We assume that the top-level type is in the end
3352                                 //
3353                                 return Methods [Methods.Length - 1].DeclaringType;
3354                                 //return Methods [0].DeclaringType;
3355                         }
3356                 }
3357
3358                 public Type DelegateType {
3359                         set {
3360                                 delegate_type = value;
3361                         }
3362                 }
3363
3364                 public bool IdenticalTypeName {
3365                         get {
3366                                 return identical_type_name;
3367                         }
3368
3369                         set {
3370                                 identical_type_name = value;
3371                         }
3372                 }
3373
3374                 public override string GetSignatureForError ()
3375                 {
3376                         if (best_candidate != null)
3377                                 return TypeManager.CSharpSignature (best_candidate);
3378
3379                         return TypeManager.CSharpSignature (Methods [0]);
3380                 }
3381
3382                 public override string Name {
3383                         get {
3384                                 return Methods [0].Name;
3385                         }
3386                 }
3387
3388                 public override bool IsInstance {
3389                         get {
3390                                 if (best_candidate != null)
3391                                         return !best_candidate.IsStatic;
3392
3393                                 foreach (MethodBase mb in Methods)
3394                                         if (!mb.IsStatic)
3395                                                 return true;
3396
3397                                 return false;
3398                         }
3399                 }
3400
3401                 public override bool IsStatic {
3402                         get {
3403                                 if (best_candidate != null)
3404                                         return best_candidate.IsStatic;
3405
3406                                 foreach (MethodBase mb in Methods)
3407                                         if (mb.IsStatic)
3408                                                 return true;
3409
3410                                 return false;
3411                         }
3412                 }
3413
3414                 public static explicit operator ConstructorInfo (MethodGroupExpr mg)
3415                 {
3416                         return (ConstructorInfo)mg.best_candidate;
3417                 }
3418
3419                 public static explicit operator MethodInfo (MethodGroupExpr mg)
3420                 {
3421                         return (MethodInfo)mg.best_candidate;
3422                 }
3423
3424                 //
3425                 //  7.4.3.3  Better conversion from expression
3426                 //  Returns :   1    if a->p is better,
3427                 //              2    if a->q is better,
3428                 //              0 if neither is better
3429                 //
3430                 static int BetterExpressionConversion (EmitContext ec, Argument a, Type p, Type q)
3431                 {
3432                         Type argument_type = TypeManager.TypeToCoreType (a.Type);
3433                         if (argument_type == TypeManager.anonymous_method_type && RootContext.Version > LanguageVersion.ISO_2) {
3434                                 //
3435                                 // Uwrap delegate from Expression<T>
3436                                 //
3437                                 if (TypeManager.DropGenericTypeArguments (p) == TypeManager.expression_type) {
3438                                         p = TypeManager.GetTypeArguments (p) [0];
3439                                 }
3440                                 if (TypeManager.DropGenericTypeArguments (q) == TypeManager.expression_type) {
3441                                         q = TypeManager.GetTypeArguments (q) [0];
3442                                 }
3443
3444                                 p = Delegate.GetInvokeMethod (null, p).ReturnType;
3445                                 q = Delegate.GetInvokeMethod (null, q).ReturnType;
3446                                 if (p == TypeManager.void_type && q != TypeManager.void_type)
3447                                         return 2;
3448                                 if (q == TypeManager.void_type && p != TypeManager.void_type)
3449                                         return 1;
3450                         } else {
3451                                 if (argument_type == p)
3452                                         return 1;
3453
3454                                 if (argument_type == q)
3455                                         return 2;
3456                         }
3457
3458                         return BetterTypeConversion (ec, p, q);
3459                 }
3460
3461                 //
3462                 // 7.4.3.4  Better conversion from type
3463                 //
3464                 public static int BetterTypeConversion (EmitContext ec, Type p, Type q)
3465                 {
3466                         if (p == null || q == null)
3467                                 throw new InternalErrorException ("BetterTypeConversion got a null conversion");
3468
3469                         if (p == TypeManager.int32_type) {
3470                                 if (q == TypeManager.uint32_type || q == TypeManager.uint64_type)
3471                                         return 1;
3472                         } else if (p == TypeManager.int64_type) {
3473                                 if (q == TypeManager.uint64_type)
3474                                         return 1;
3475                         } else if (p == TypeManager.sbyte_type) {
3476                                 if (q == TypeManager.byte_type || q == TypeManager.ushort_type ||
3477                                         q == TypeManager.uint32_type || q == TypeManager.uint64_type)
3478                                         return 1;
3479                         } else if (p == TypeManager.short_type) {
3480                                 if (q == TypeManager.ushort_type || q == TypeManager.uint32_type ||
3481                                         q == TypeManager.uint64_type)
3482                                         return 1;
3483                         }
3484
3485                         if (q == TypeManager.int32_type) {
3486                                 if (p == TypeManager.uint32_type || p == TypeManager.uint64_type)
3487                                         return 2;
3488                         } if (q == TypeManager.int64_type) {
3489                                 if (p == TypeManager.uint64_type)
3490                                         return 2;
3491                         } else if (q == TypeManager.sbyte_type) {
3492                                 if (p == TypeManager.byte_type || p == TypeManager.ushort_type ||
3493                                         p == TypeManager.uint32_type || p == TypeManager.uint64_type)
3494                                         return 2;
3495                         } if (q == TypeManager.short_type) {
3496                                 if (p == TypeManager.ushort_type || p == TypeManager.uint32_type ||
3497                                         p == TypeManager.uint64_type)
3498                                         return 2;
3499                         }
3500
3501                         // TODO: this is expensive
3502                         Expression p_tmp = new EmptyExpression (p);
3503                         Expression q_tmp = new EmptyExpression (q);
3504
3505                         bool p_to_q = Convert.ImplicitConversionExists (ec, p_tmp, q);
3506                         bool q_to_p = Convert.ImplicitConversionExists (ec, q_tmp, p);
3507
3508                         if (p_to_q && !q_to_p)
3509                                 return 1;
3510
3511                         if (q_to_p && !p_to_q)
3512                                 return 2;
3513
3514                         return 0;
3515                 }
3516
3517                 /// <summary>
3518                 ///   Determines "Better function" between candidate
3519                 ///   and the current best match
3520                 /// </summary>
3521                 /// <remarks>
3522                 ///    Returns a boolean indicating :
3523                 ///     false if candidate ain't better
3524                 ///     true  if candidate is better than the current best match
3525                 /// </remarks>
3526                 static bool BetterFunction (EmitContext ec, ArrayList args, int argument_count,
3527                         MethodBase candidate, bool candidate_params,
3528                         MethodBase best, bool best_params)
3529                 {
3530                         AParametersCollection candidate_pd = TypeManager.GetParameterData (candidate);
3531                         AParametersCollection best_pd = TypeManager.GetParameterData (best);
3532
3533                         bool better_at_least_one = false;
3534                         bool same = true;
3535                         for (int j = 0, c_idx = 0, b_idx = 0; j < argument_count; ++j, ++c_idx, ++b_idx)
3536                         {
3537                                 Argument a = (Argument) args [j];
3538
3539                                 Type ct = candidate_pd.Types [c_idx];
3540                                 Type bt = best_pd.Types [b_idx];
3541
3542                                 if (candidate_params && candidate_pd.FixedParameters [c_idx].ModFlags == Parameter.Modifier.PARAMS)
3543                                 {
3544                                         ct = TypeManager.GetElementType (ct);
3545                                         --c_idx;
3546                                 }
3547
3548                                 if (best_params && best_pd.FixedParameters [b_idx].ModFlags == Parameter.Modifier.PARAMS)
3549                                 {
3550                                         bt = TypeManager.GetElementType (bt);
3551                                         --b_idx;
3552                                 }
3553
3554                                 if (ct.Equals (bt))
3555                                         continue;
3556
3557                                 same = false;
3558                                 int result = BetterExpressionConversion (ec, a, ct, bt);
3559
3560                                 // for each argument, the conversion to 'ct' should be no worse than
3561                                 // the conversion to 'bt'.
3562                                 if (result == 2)
3563                                         return false;
3564
3565                                 // for at least one argument, the conversion to 'ct' should be better than
3566                                 // the conversion to 'bt'.
3567                                 if (result != 0)
3568                                         better_at_least_one = true;
3569                         }
3570
3571                         if (better_at_least_one)
3572                                 return true;
3573
3574                         //
3575                         // This handles the case
3576                         //
3577                         //   Add (float f1, float f2, float f3);
3578                         //   Add (params decimal [] foo);
3579                         //
3580                         // The call Add (3, 4, 5) should be ambiguous.  Without this check, the
3581                         // first candidate would've chosen as better.
3582                         //
3583                         if (!same)
3584                                 return false;
3585
3586                         //
3587                         // The two methods have equal parameter types.  Now apply tie-breaking rules
3588                         //
3589                         if (TypeManager.IsGenericMethod (best) && !TypeManager.IsGenericMethod (candidate))
3590                                 return true;
3591                         if (!TypeManager.IsGenericMethod (best) && TypeManager.IsGenericMethod (candidate))
3592                                 return false;
3593
3594                         //
3595                         // This handles the following cases:
3596                         //
3597                         //   Trim () is better than Trim (params char[] chars)
3598                         //   Concat (string s1, string s2, string s3) is better than
3599                         //     Concat (string s1, params string [] srest)
3600                         //   Foo (int, params int [] rest) is better than Foo (params int [] rest)
3601                         //
3602                         if (!candidate_params && best_params)
3603                                 return true;
3604                         if (candidate_params && !best_params)
3605                                 return false;
3606
3607                         int candidate_param_count = candidate_pd.Count;
3608                         int best_param_count = best_pd.Count;
3609
3610                         if (candidate_param_count != best_param_count)
3611                                 // can only happen if (candidate_params && best_params)
3612                                 return candidate_param_count > best_param_count;
3613
3614                         //
3615                         // now, both methods have the same number of parameters, and the parameters have the same types
3616                         // Pick the "more specific" signature
3617                         //
3618
3619                         MethodBase orig_candidate = TypeManager.DropGenericMethodArguments (candidate);
3620                         MethodBase orig_best = TypeManager.DropGenericMethodArguments (best);
3621
3622                         AParametersCollection orig_candidate_pd = TypeManager.GetParameterData (orig_candidate);
3623                         AParametersCollection orig_best_pd = TypeManager.GetParameterData (orig_best);
3624
3625                         bool specific_at_least_once = false;
3626                         for (int j = 0; j < candidate_param_count; ++j)
3627                         {
3628                                 Type ct = orig_candidate_pd.Types [j];
3629                                 Type bt = orig_best_pd.Types [j];
3630                                 if (ct.Equals (bt))
3631                                         continue;
3632                                 Type specific = MoreSpecific (ct, bt);
3633                                 if (specific == bt)
3634                                         return false;
3635                                 if (specific == ct)
3636                                         specific_at_least_once = true;
3637                         }
3638
3639                         if (specific_at_least_once)
3640                                 return true;
3641
3642                         // FIXME: handle lifted operators
3643                         // ...
3644
3645                         return false;
3646                 }
3647
3648                 protected override MemberExpr ResolveExtensionMemberAccess (Expression left)
3649                 {
3650                         if (!IsStatic)
3651                                 return base.ResolveExtensionMemberAccess (left);
3652
3653                         //
3654                         // When left side is an expression and at least one candidate method is
3655                         // static, it can be extension method
3656                         //
3657                         InstanceExpression = left;
3658                         return this;
3659                 }
3660
3661                 public override MemberExpr ResolveMemberAccess (EmitContext ec, Expression left, Location loc,
3662                                                                 SimpleName original)
3663                 {
3664                         if (!(left is TypeExpr) &&
3665                             original != null && original.IdenticalNameAndTypeName (ec, left, loc))
3666                                 IdenticalTypeName = true;
3667
3668                         return base.ResolveMemberAccess (ec, left, loc, original);
3669                 }
3670
3671                 public override Expression CreateExpressionTree (EmitContext ec)
3672                 {
3673                         if (best_candidate == null) {
3674                                 Report.Error (1953, loc, "An expression tree cannot contain an expression with method group");
3675                                 return null;
3676                         }
3677
3678                         if (best_candidate.IsConstructor)
3679                                 return new TypeOfConstructorInfo (best_candidate, loc);
3680
3681                         IMethodData md = TypeManager.GetMethod (best_candidate);
3682                         if (md != null && md.IsExcluded ())
3683                                 Report.Error (765, loc,
3684                                         "Partial methods with only a defining declaration or removed conditional methods cannot be used in an expression tree");
3685
3686                         return new TypeOfMethodInfo (best_candidate, loc);
3687                 }
3688
3689                 override public Expression DoResolve (EmitContext ec)
3690                 {
3691                         if (InstanceExpression != null) {
3692                                 InstanceExpression = InstanceExpression.DoResolve (ec);
3693                                 if (InstanceExpression == null)
3694                                         return null;
3695                         }
3696
3697                         return this;
3698                 }
3699
3700                 public void ReportUsageError ()
3701                 {
3702                         Report.Error (654, loc, "Method `" + DeclaringType + "." +
3703                                       Name + "()' is referenced without parentheses");
3704                 }
3705
3706                 override public void Emit (EmitContext ec)
3707                 {
3708                         ReportUsageError ();
3709                 }
3710
3711                 public virtual void EmitArguments (EmitContext ec, ArrayList arguments)
3712                 {
3713                         Invocation.EmitArguments (ec, arguments, false, null);
3714                 }
3715
3716                 public virtual void EmitCall (EmitContext ec, ArrayList arguments)
3717                 {
3718                         Invocation.EmitCall (ec, IsBase, InstanceExpression, best_candidate, arguments, loc);
3719                 }
3720
3721                 protected virtual void Error_InvalidArguments (EmitContext ec, Location loc, int idx, MethodBase method,
3722                                                                                                         Argument a, AParametersCollection expected_par, Type paramType)
3723                 {
3724                         ExtensionMethodGroupExpr emg = this as ExtensionMethodGroupExpr;
3725
3726                         if (a is CollectionElementInitializer.ElementInitializerArgument) {
3727                                 Report.SymbolRelatedToPreviousError (method);
3728                                 if ((expected_par.FixedParameters [idx].ModFlags & Parameter.Modifier.ISBYREF) != 0) {
3729                                         Report.Error (1954, loc, "The best overloaded collection initalizer method `{0}' cannot have 'ref', or `out' modifier",
3730                                                 TypeManager.CSharpSignature (method));
3731                                         return;
3732                                 }
3733                                 Report.Error (1950, loc, "The best overloaded collection initalizer method `{0}' has some invalid arguments",
3734                                           TypeManager.CSharpSignature (method));
3735                         } else if (delegate_type == null) {
3736                                 Report.SymbolRelatedToPreviousError (method);
3737                                 if (emg != null) {
3738                                         Report.Error (1928, loc,
3739                                                 "Type `{0}' does not contain a member `{1}' and the best extension method overload `{2}' has some invalid arguments",
3740                                                 emg.ExtensionExpression.GetSignatureForError (),
3741                                                 emg.Name, TypeManager.CSharpSignature (method));
3742                                 } else {
3743                                         Report.Error (1502, loc, "The best overloaded method match for `{0}' has some invalid arguments",
3744                                                 TypeManager.CSharpSignature (method));
3745                                 }
3746                         } else
3747                                 Report.Error (1594, loc, "Delegate `{0}' has some invalid arguments",
3748                                         TypeManager.CSharpName (delegate_type));
3749
3750                         Parameter.Modifier mod = idx >= expected_par.Count ? 0 : expected_par.FixedParameters [idx].ModFlags;
3751
3752                         string index = (idx + 1).ToString ();
3753                         if (((mod & (Parameter.Modifier.REF | Parameter.Modifier.OUT)) ^
3754                                 (a.Modifier & (Parameter.Modifier.REF | Parameter.Modifier.OUT))) != 0) {
3755                                 if ((mod & Parameter.Modifier.ISBYREF) == 0)
3756                                         Report.Error (1615, loc, "Argument `#{0}' does not require `{1}' modifier. Consider removing `{1}' modifier",
3757                                                 index, Parameter.GetModifierSignature (a.Modifier));
3758                                 else
3759                                         Report.Error (1620, loc, "Argument `#{0}' is missing `{1}' modifier",
3760                                                 index, Parameter.GetModifierSignature (mod));
3761                         } else {
3762                                 string p1 = a.GetSignatureForError ();
3763                                 string p2 = TypeManager.CSharpName (paramType);
3764
3765                                 if (p1 == p2) {
3766                                         Report.ExtraInformation (loc, "(equally named types possibly from different assemblies in previous ");
3767                                         Report.SymbolRelatedToPreviousError (a.Expr.Type);
3768                                         Report.SymbolRelatedToPreviousError (paramType);
3769                                 }
3770
3771                                 if (idx == 0 && emg != null) {
3772                                         Report.Error (1929, loc,
3773                                                 "Extension method instance type `{0}' cannot be converted to `{1}'", p1, p2);
3774                                 } else {
3775                                         Report.Error (1503, loc,
3776                                                 "Argument `#{0}' cannot convert `{1}' expression to type `{2}'", index, p1, p2);
3777                                 }
3778                         }
3779                 }
3780
3781                 public override void Error_ValueCannotBeConverted (EmitContext ec, Location loc, Type target, bool expl)
3782                 {
3783                         Report.Error (428, loc, "Cannot convert method group `{0}' to non-delegate type `{1}'. Consider using parentheses to invoke the method",
3784                                 Name, TypeManager.CSharpName (target));
3785                 }
3786
3787                 protected virtual int GetApplicableParametersCount (MethodBase method, AParametersCollection parameters)
3788                 {
3789                         return parameters.Count;
3790                 }
3791
3792                 public static bool IsAncestralType (Type first_type, Type second_type)
3793                 {
3794                         return first_type != second_type &&
3795                                 (TypeManager.IsSubclassOf (second_type, first_type) ||
3796                                 TypeManager.ImplementsInterface (second_type, first_type));
3797                 }
3798
3799                 ///
3800                 /// Determines if the candidate method is applicable (section 14.4.2.1)
3801                 /// to the given set of arguments
3802                 /// A return value rates candidate method compatibility,
3803                 /// 0 = the best, int.MaxValue = the worst
3804                 ///
3805                 public int IsApplicable (EmitContext ec,
3806                                                  ArrayList arguments, int arg_count, ref MethodBase method, ref bool params_expanded_form)
3807                 {
3808                         MethodBase candidate = method;
3809
3810                         AParametersCollection pd = TypeManager.GetParameterData (candidate);
3811                         int param_count = GetApplicableParametersCount (candidate, pd);
3812
3813                         if (arg_count != param_count) {
3814                                 if (!pd.HasParams)
3815                                         return int.MaxValue - 10000 + Math.Abs (arg_count - param_count);
3816                                 if (arg_count < param_count - 1)
3817                                         return int.MaxValue - 10000 + Math.Abs (arg_count - param_count);
3818                         }
3819
3820 #if GMCS_SOURCE
3821                         //
3822                         // 1. Handle generic method using type arguments when specified or type inference
3823                         //
3824                         if (TypeManager.IsGenericMethod (candidate)) {
3825                                 if (type_arguments != null) {
3826                                         Type [] g_args = candidate.GetGenericArguments ();
3827                                         if (g_args.Length != type_arguments.Count)
3828                                                 return int.MaxValue - 20000 + Math.Abs (type_arguments.Count - g_args.Length);
3829
3830                                         // TODO: Don't create new method, create Parameters only
3831                                         method = ((MethodInfo) candidate).MakeGenericMethod (type_arguments.Arguments);
3832                                         candidate = method;
3833                                         pd = TypeManager.GetParameterData (candidate);
3834                                 } else {
3835                                         int score = TypeManager.InferTypeArguments (ec, arguments, ref candidate);
3836                                         if (score != 0)
3837                                                 return score - 20000;
3838
3839                                         if (TypeManager.IsGenericMethodDefinition (candidate))
3840                                                 throw new InternalErrorException ("A generic method `{0}' definition took part in overload resolution",
3841                                                         TypeManager.CSharpSignature (candidate));
3842
3843                                         pd = TypeManager.GetParameterData (candidate);
3844                                 }
3845                         } else {
3846                                 if (type_arguments != null)
3847                                         return int.MaxValue - 15000;
3848                         }
3849 #endif
3850
3851                         //
3852                         // 2. Each argument has to be implicitly convertible to method parameter
3853                         //
3854                         method = candidate;
3855                         Parameter.Modifier p_mod = 0;
3856                         Type pt = null;
3857                         for (int i = 0; i < arg_count; i++) {
3858                                 Argument a = (Argument) arguments [i];
3859                                 Parameter.Modifier a_mod = a.Modifier &
3860                                         ~(Parameter.Modifier.OUTMASK | Parameter.Modifier.REFMASK);
3861
3862                                 if (p_mod != Parameter.Modifier.PARAMS) {
3863                                         p_mod = pd.FixedParameters [i].ModFlags & ~(Parameter.Modifier.OUTMASK | Parameter.Modifier.REFMASK);
3864
3865                                         if (p_mod == Parameter.Modifier.ARGLIST) {
3866                                                 if (a.Type == TypeManager.runtime_argument_handle_type)
3867                                                         continue;
3868
3869                                                 p_mod = 0;
3870                                         }
3871
3872                                         pt = pd.Types [i];
3873                                 } else {
3874                                         params_expanded_form = true;
3875                                 }
3876
3877                                 int score = 1;
3878                                 if (!params_expanded_form)
3879                                         score = IsArgumentCompatible (ec, a_mod, a, p_mod & ~Parameter.Modifier.PARAMS, pt);
3880
3881                                 if (score != 0 && (p_mod & Parameter.Modifier.PARAMS) != 0) {
3882                                         // It can be applicable in expanded form
3883                                         score = IsArgumentCompatible (ec, a_mod, a, 0, pt.GetElementType ());
3884                                         if (score == 0)
3885                                                 params_expanded_form = true;
3886                                 }
3887
3888                                 if (score != 0) {
3889                                         if (params_expanded_form)
3890                                                 ++score;
3891                                         return (arg_count - i) * 2 + score;
3892                                 }
3893                         }
3894
3895                         if (arg_count != param_count)
3896                                 params_expanded_form = true;
3897
3898                         return 0;
3899                 }
3900
3901                 int IsArgumentCompatible (EmitContext ec, Parameter.Modifier arg_mod, Argument argument, Parameter.Modifier param_mod, Type parameter)
3902                 {
3903                         //
3904                         // Types have to be identical when ref or out modifer is used
3905                         //
3906                         if (arg_mod != 0 || param_mod != 0) {
3907                                 if (TypeManager.HasElementType (parameter))
3908                                         parameter = parameter.GetElementType ();
3909
3910                                 Type a_type = argument.Type;
3911                                 if (TypeManager.HasElementType (a_type))
3912                                         a_type = a_type.GetElementType ();
3913
3914                                 if (a_type != parameter)
3915                                         return 2;
3916                         } else {
3917                                 if (delegate_type != null ?
3918                                         !Delegate.IsTypeCovariant (argument.Expr, parameter) :
3919                                         !Convert.ImplicitConversionExists (ec, argument.Expr, parameter))
3920                                         return 2;
3921                         }
3922
3923                         if (arg_mod != param_mod)
3924                                 return 1;
3925
3926                         return 0;
3927                 }
3928
3929                 public static bool IsOverride (MethodBase cand_method, MethodBase base_method)
3930                 {
3931                         if (!IsAncestralType (base_method.DeclaringType, cand_method.DeclaringType))
3932                                 return false;
3933
3934                         AParametersCollection cand_pd = TypeManager.GetParameterData (cand_method);
3935                         AParametersCollection base_pd = TypeManager.GetParameterData (base_method);
3936
3937                         if (cand_pd.Count != base_pd.Count)
3938                                 return false;
3939
3940                         for (int j = 0; j < cand_pd.Count; ++j)
3941                         {
3942                                 Parameter.Modifier cm = cand_pd.FixedParameters [j].ModFlags;
3943                                 Parameter.Modifier bm = base_pd.FixedParameters [j].ModFlags;
3944                                 Type ct = cand_pd.Types [j];
3945                                 Type bt = base_pd.Types [j];
3946
3947                                 if (cm != bm || ct != bt)
3948                                         return false;
3949                         }
3950
3951                         return true;
3952                 }
3953
3954                 public static MethodGroupExpr MakeUnionSet (MethodGroupExpr mg1, MethodGroupExpr mg2, Location loc)
3955                 {
3956                         if (mg1 == null) {
3957                                 if (mg2 == null)
3958                                         return null;
3959                                 return mg2;
3960                         }
3961
3962                         if (mg2 == null)
3963                                 return mg1;
3964
3965                         ArrayList all = new ArrayList (mg1.Methods);
3966                         foreach (MethodBase m in mg2.Methods){
3967                                 if (!TypeManager.ArrayContainsMethod (mg1.Methods, m, false))
3968                                         all.Add (m);
3969                         }
3970
3971                         return new MethodGroupExpr (all, null, loc);
3972                 }
3973
3974                 static Type MoreSpecific (Type p, Type q)
3975                 {
3976                         if (TypeManager.IsGenericParameter (p) && !TypeManager.IsGenericParameter (q))
3977                                 return q;
3978                         if (!TypeManager.IsGenericParameter (p) && TypeManager.IsGenericParameter (q))
3979                                 return p;
3980
3981                         if (TypeManager.HasElementType (p))
3982                         {
3983                                 Type pe = TypeManager.GetElementType (p);
3984                                 Type qe = TypeManager.GetElementType (q);
3985                                 Type specific = MoreSpecific (pe, qe);
3986                                 if (specific == pe)
3987                                         return p;
3988                                 if (specific == qe)
3989                                         return q;
3990                         }
3991                         else if (TypeManager.IsGenericType (p))
3992                         {
3993                                 Type[] pargs = TypeManager.GetTypeArguments (p);
3994                                 Type[] qargs = TypeManager.GetTypeArguments (q);
3995
3996                                 bool p_specific_at_least_once = false;
3997                                 bool q_specific_at_least_once = false;
3998
3999                                 for (int i = 0; i < pargs.Length; i++)
4000                                 {
4001                                         Type specific = MoreSpecific (pargs [i], qargs [i]);
4002                                         if (specific == pargs [i])
4003                                                 p_specific_at_least_once = true;
4004                                         if (specific == qargs [i])
4005                                                 q_specific_at_least_once = true;
4006                                 }
4007
4008                                 if (p_specific_at_least_once && !q_specific_at_least_once)
4009                                         return p;
4010                                 if (!p_specific_at_least_once && q_specific_at_least_once)
4011                                         return q;
4012                         }
4013
4014                         return null;
4015                 }
4016
4017                 public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
4018                 {
4019                         base.MutateHoistedGenericType (storey);
4020
4021                         MethodInfo mi = best_candidate as MethodInfo;
4022                         if (mi != null) {
4023                                 best_candidate = storey.MutateGenericMethod (mi);
4024                                 return;
4025                         }
4026
4027                         best_candidate = storey.MutateConstructor ((ConstructorInfo) this);
4028                 }
4029
4030                 /// <summary>
4031                 ///   Find the Applicable Function Members (7.4.2.1)
4032                 ///
4033                 ///   me: Method Group expression with the members to select.
4034                 ///       it might contain constructors or methods (or anything
4035                 ///       that maps to a method).
4036                 ///
4037                 ///   Arguments: ArrayList containing resolved Argument objects.
4038                 ///
4039                 ///   loc: The location if we want an error to be reported, or a Null
4040                 ///        location for "probing" purposes.
4041                 ///
4042                 ///   Returns: The MethodBase (either a ConstructorInfo or a MethodInfo)
4043                 ///            that is the best match of me on Arguments.
4044                 ///
4045                 /// </summary>
4046                 public virtual MethodGroupExpr OverloadResolve (EmitContext ec, ref ArrayList Arguments,
4047                         bool may_fail, Location loc)
4048                 {
4049                         bool method_params = false;
4050                         Type applicable_type = null;
4051                         int arg_count = 0;
4052                         ArrayList candidates = new ArrayList (2);
4053                         ArrayList candidate_overrides = null;
4054
4055                         //
4056                         // Used to keep a map between the candidate
4057                         // and whether it is being considered in its
4058                         // normal or expanded form
4059                         //
4060                         // false is normal form, true is expanded form
4061                         //
4062                         Hashtable candidate_to_form = null;
4063
4064                         if (Arguments != null)
4065                                 arg_count = Arguments.Count;
4066
4067                         if (RootContext.Version == LanguageVersion.ISO_1 && Name == "Invoke" && TypeManager.IsDelegateType (DeclaringType)) {
4068                                 if (!may_fail)
4069                                         Report.Error (1533, loc, "Invoke cannot be called directly on a delegate");
4070                                 return null;
4071                         }
4072
4073                         int nmethods = Methods.Length;
4074
4075                         if (!IsBase) {
4076                                 //
4077                                 // Methods marked 'override' don't take part in 'applicable_type'
4078                                 // computation, nor in the actual overload resolution.
4079                                 // However, they still need to be emitted instead of a base virtual method.
4080                                 // So, we salt them away into the 'candidate_overrides' array.
4081                                 //
4082                                 // In case of reflected methods, we replace each overriding method with
4083                                 // its corresponding base virtual method.  This is to improve compatibility
4084                                 // with non-C# libraries which change the visibility of overrides (#75636)
4085                                 //
4086                                 int j = 0;
4087                                 for (int i = 0; i < Methods.Length; ++i) {
4088                                         MethodBase m = Methods [i];
4089                                         if (TypeManager.IsOverride (m)) {
4090                                                 if (candidate_overrides == null)
4091                                                         candidate_overrides = new ArrayList ();
4092                                                 candidate_overrides.Add (m);
4093                                                 m = TypeManager.TryGetBaseDefinition (m);
4094                                         }
4095                                         if (m != null)
4096                                                 Methods [j++] = m;
4097                                 }
4098                                 nmethods = j;
4099                         }
4100
4101                         //
4102                         // Enable message recording, it's used mainly by lambda expressions
4103                         //
4104                         Report.IMessageRecorder msg_recorder = new Report.MessageRecorder ();
4105                         Report.IMessageRecorder prev_recorder = Report.SetMessageRecorder (msg_recorder);
4106
4107                         //
4108                         // First we construct the set of applicable methods
4109                         //
4110                         bool is_sorted = true;
4111                         int best_candidate_rate = int.MaxValue;
4112                         for (int i = 0; i < nmethods; i++) {
4113                                 Type decl_type = Methods [i].DeclaringType;
4114
4115                                 //
4116                                 // If we have already found an applicable method
4117                                 // we eliminate all base types (Section 14.5.5.1)
4118                                 //
4119                                 if (applicable_type != null && IsAncestralType (decl_type, applicable_type))
4120                                         continue;
4121
4122                                 //
4123                                 // Check if candidate is applicable (section 14.4.2.1)
4124                                 //
4125                                 bool params_expanded_form = false;
4126                                 int candidate_rate = IsApplicable (ec, Arguments, arg_count, ref Methods [i], ref params_expanded_form);
4127
4128                                 if (candidate_rate < best_candidate_rate) {
4129                                         best_candidate_rate = candidate_rate;
4130                                         best_candidate = Methods [i];
4131                                 }
4132
4133                                 if (params_expanded_form) {
4134                                         if (candidate_to_form == null)
4135                                                 candidate_to_form = new PtrHashtable ();
4136                                         MethodBase candidate = Methods [i];
4137                                         candidate_to_form [candidate] = candidate;
4138                                 }
4139
4140                                 if (candidate_rate != 0) {
4141                                         if (msg_recorder != null)
4142                                                 msg_recorder.EndSession ();
4143                                         continue;
4144                                 }
4145
4146                                 msg_recorder = null;
4147                                 candidates.Add (Methods [i]);
4148
4149                                 if (applicable_type == null)
4150                                         applicable_type = decl_type;
4151                                 else if (applicable_type != decl_type) {
4152                                         is_sorted = false;
4153                                         if (IsAncestralType (applicable_type, decl_type))
4154                                                 applicable_type = decl_type;
4155                                 }
4156                         }
4157
4158                         Report.SetMessageRecorder (prev_recorder);
4159                         if (msg_recorder != null && !msg_recorder.IsEmpty) {
4160                                 if (!may_fail)
4161                                         msg_recorder.PrintMessages ();
4162
4163                                 return null;
4164                         }
4165
4166                         int candidate_top = candidates.Count;
4167
4168                         if (applicable_type == null) {
4169                                 //
4170                                 // When we found a top level method which does not match and it's
4171                                 // not an extension method. We start extension methods lookup from here
4172                                 //
4173                                 if (InstanceExpression != null) {
4174                                         ExtensionMethodGroupExpr ex_method_lookup = ec.TypeContainer.LookupExtensionMethod (type, Name, loc);
4175                                         if (ex_method_lookup != null) {
4176                                                 ex_method_lookup.ExtensionExpression = InstanceExpression;
4177                                                 ex_method_lookup.SetTypeArguments (type_arguments);
4178                                                 return ex_method_lookup.OverloadResolve (ec, ref Arguments, may_fail, loc);
4179                                         }
4180                                 }
4181
4182                                 if (may_fail)
4183                                         return null;
4184
4185                                 //
4186                                 // Okay so we have failed to find exact match so we
4187                                 // return error info about the closest match
4188                                 //
4189                                 if (best_candidate != null) {
4190                                         if (CustomErrorHandler != null) {
4191                                                 if (CustomErrorHandler.NoExactMatch (ec, best_candidate))
4192                                                         return null;
4193                                         }
4194
4195                                         AParametersCollection pd = TypeManager.GetParameterData (best_candidate);
4196                                         bool cand_params = candidate_to_form != null && candidate_to_form.Contains (best_candidate);
4197                                         if (arg_count == pd.Count || pd.HasParams) {
4198                                                 if (TypeManager.IsGenericMethodDefinition (best_candidate)) {
4199                                                         if (type_arguments == null) {
4200                                                                 Report.Error (411, loc,
4201                                                                         "The type arguments for method `{0}' cannot be inferred from " +
4202                                                                         "the usage. Try specifying the type arguments explicitly",
4203                                                                         TypeManager.CSharpSignature (best_candidate));
4204                                                                 return null;
4205                                                         }
4206
4207                                                         Type [] g_args = TypeManager.GetGenericArguments (best_candidate);
4208                                                         if (type_arguments.Count != g_args.Length) {
4209                                                                 Report.SymbolRelatedToPreviousError (best_candidate);
4210                                                                 Report.Error (305, loc, "Using the generic method `{0}' requires `{1}' type argument(s)",
4211                                                                         TypeManager.CSharpSignature (best_candidate),
4212                                                                         g_args.Length.ToString ());
4213                                                                 return null;
4214                                                         }
4215                                                 } else {
4216                                                         if (type_arguments != null && !TypeManager.IsGenericMethod (best_candidate)) {
4217                                                                 Namespace.Error_TypeArgumentsCannotBeUsed (best_candidate, loc);
4218                                                                 return null;
4219                                                         }
4220                                                 }
4221
4222                                                 if (!VerifyArgumentsCompat (ec, ref Arguments, arg_count, best_candidate, cand_params, may_fail, loc))
4223                                                         return null;
4224                                         }
4225                                 }
4226
4227                                 if (almost_matched_members.Count != 0) {
4228                                         Error_MemberLookupFailed (ec.ContainerType, type, type, ".ctor",
4229                                         null, MemberTypes.Constructor, AllBindingFlags);
4230                                         return null;
4231                                 }
4232
4233                                 //
4234                                 // We failed to find any method with correct argument count
4235                                 //
4236                                 if (Name == ConstructorInfo.ConstructorName) {
4237                                         Report.SymbolRelatedToPreviousError (type);
4238                                         Report.Error (1729, loc,
4239                                                 "The type `{0}' does not contain a constructor that takes `{1}' arguments",
4240                                                 TypeManager.CSharpName (type), arg_count);
4241                                 } else {
4242                                         Report.Error (1501, loc, "No overload for method `{0}' takes `{1}' arguments",
4243                                                 Name, arg_count.ToString ());
4244                                 }
4245
4246                                 return null;
4247                         }
4248
4249                         if (!is_sorted) {
4250                                 //
4251                                 // At this point, applicable_type is _one_ of the most derived types
4252                                 // in the set of types containing the methods in this MethodGroup.
4253                                 // Filter the candidates so that they only contain methods from the
4254                                 // most derived types.
4255                                 //
4256
4257                                 int finalized = 0; // Number of finalized candidates
4258
4259                                 do {
4260                                         // Invariant: applicable_type is a most derived type
4261
4262                                         // We'll try to complete Section 14.5.5.1 for 'applicable_type' by
4263                                         // eliminating all it's base types.  At the same time, we'll also move
4264                                         // every unrelated type to the end of the array, and pick the next
4265                                         // 'applicable_type'.
4266
4267                                         Type next_applicable_type = null;
4268                                         int j = finalized; // where to put the next finalized candidate
4269                                         int k = finalized; // where to put the next undiscarded candidate
4270                                         for (int i = finalized; i < candidate_top; ++i) {
4271                                                 MethodBase candidate = (MethodBase) candidates [i];
4272                                                 Type decl_type = candidate.DeclaringType;
4273
4274                                                 if (decl_type == applicable_type) {
4275                                                         candidates [k++] = candidates [j];
4276                                                         candidates [j++] = candidates [i];
4277                                                         continue;
4278                                                 }
4279
4280                                                 if (IsAncestralType (decl_type, applicable_type))
4281                                                         continue;
4282
4283                                                 if (next_applicable_type != null &&
4284                                                         IsAncestralType (decl_type, next_applicable_type))
4285                                                         continue;
4286
4287                                                 candidates [k++] = candidates [i];
4288
4289                                                 if (next_applicable_type == null ||
4290                                                         IsAncestralType (next_applicable_type, decl_type))
4291                                                         next_applicable_type = decl_type;
4292                                         }
4293
4294                                         applicable_type = next_applicable_type;
4295                                         finalized = j;
4296                                         candidate_top = k;
4297                                 } while (applicable_type != null);
4298                         }
4299
4300                         //
4301                         // Now we actually find the best method
4302                         //
4303
4304                         best_candidate = (MethodBase) candidates [0];
4305                         if (delegate_type == null)
4306                                 method_params = candidate_to_form != null && candidate_to_form.Contains (best_candidate);
4307
4308                         for (int ix = 1; ix < candidate_top; ix++) {
4309                                 MethodBase candidate = (MethodBase) candidates [ix];
4310
4311                                 if (candidate == best_candidate)
4312                                         continue;
4313
4314                                 bool cand_params = candidate_to_form != null && candidate_to_form.Contains (candidate);
4315
4316                                 if (BetterFunction (ec, Arguments, arg_count,
4317                                         candidate, cand_params,
4318                                         best_candidate, method_params)) {
4319                                         best_candidate = candidate;
4320                                         method_params = cand_params;
4321                                 }
4322                         }
4323                         //
4324                         // Now check that there are no ambiguities i.e the selected method
4325                         // should be better than all the others
4326                         //
4327                         MethodBase ambiguous = null;
4328                         for (int ix = 1; ix < candidate_top; ix++) {
4329                                 MethodBase candidate = (MethodBase) candidates [ix];
4330
4331                                 if (candidate == best_candidate)
4332                                         continue;
4333
4334                                 bool cand_params = candidate_to_form != null && candidate_to_form.Contains (candidate);
4335                                 if (!BetterFunction (ec, Arguments, arg_count,
4336                                         best_candidate, method_params,
4337                                         candidate, cand_params))
4338                                 {
4339                                         if (!may_fail)
4340                                                 Report.SymbolRelatedToPreviousError (candidate);
4341                                         ambiguous = candidate;
4342                                 }
4343                         }
4344
4345                         if (ambiguous != null) {
4346                                 Report.SymbolRelatedToPreviousError (best_candidate);
4347                                 Report.Error (121, loc, "The call is ambiguous between the following methods or properties: `{0}' and `{1}'",
4348                                         TypeManager.CSharpSignature (ambiguous), TypeManager.CSharpSignature (best_candidate));
4349                                 return this;
4350                         }
4351
4352                         //
4353                         // If the method is a virtual function, pick an override closer to the LHS type.
4354                         //
4355                         if (!IsBase && best_candidate.IsVirtual) {
4356                                 if (TypeManager.IsOverride (best_candidate))
4357                                         throw new InternalErrorException (
4358                                                 "Should not happen.  An 'override' method took part in overload resolution: " + best_candidate);
4359
4360                                 if (candidate_overrides != null) {
4361                                         Type[] gen_args = null;
4362                                         bool gen_override = false;
4363                                         if (TypeManager.IsGenericMethod (best_candidate))
4364                                                 gen_args = TypeManager.GetGenericArguments (best_candidate);
4365
4366                                         foreach (MethodBase candidate in candidate_overrides) {
4367                                                 if (TypeManager.IsGenericMethod (candidate)) {
4368                                                         if (gen_args == null)
4369                                                                 continue;
4370
4371                                                         if (gen_args.Length != TypeManager.GetGenericArguments (candidate).Length)
4372                                                                 continue;
4373                                                 } else {
4374                                                         if (gen_args != null)
4375                                                                 continue;
4376                                                 }
4377
4378                                                 if (IsOverride (candidate, best_candidate)) {
4379                                                         gen_override = true;
4380                                                         best_candidate = candidate;
4381                                                 }
4382                                         }
4383
4384                                         if (gen_override && gen_args != null) {
4385 #if GMCS_SOURCE
4386                                                 best_candidate = ((MethodInfo) best_candidate).MakeGenericMethod (gen_args);
4387 #endif
4388                                         }
4389                                 }
4390                         }
4391
4392                         //
4393                         // And now check if the arguments are all
4394                         // compatible, perform conversions if
4395                         // necessary etc. and return if everything is
4396                         // all right
4397                         //
4398                         if (!VerifyArgumentsCompat (ec, ref Arguments, arg_count, best_candidate,
4399                                 method_params, may_fail, loc))
4400                                 return null;
4401
4402                         if (best_candidate == null)
4403                                 return null;
4404
4405                         MethodBase the_method = TypeManager.DropGenericMethodArguments (best_candidate);
4406 #if GMCS_SOURCE
4407                         if (the_method.IsGenericMethodDefinition &&
4408                             !ConstraintChecker.CheckConstraints (ec, the_method, best_candidate, loc))
4409                                 return null;
4410 #endif
4411
4412                         IMethodData data = TypeManager.GetMethod (the_method);
4413                         if (data != null)
4414                                 data.SetMemberIsUsed ();
4415
4416                         return this;
4417                 }
4418
4419                 public override void SetTypeArguments (TypeArguments ta)
4420                 {
4421                         type_arguments = ta;
4422                 }
4423
4424                 public bool VerifyArgumentsCompat (EmitContext ec, ref ArrayList arguments,
4425                                                           int arg_count, MethodBase method,
4426                                                           bool chose_params_expanded,
4427                                                           bool may_fail, Location loc)
4428                 {
4429                         AParametersCollection pd = TypeManager.GetParameterData (method);
4430
4431                         int errors = Report.Errors;
4432                         Parameter.Modifier p_mod = 0;
4433                         Type pt = null;
4434                         int a_idx = 0, a_pos = 0;
4435                         Argument a = null;
4436                         ArrayList params_initializers = null;
4437                         bool has_unsafe_arg = false;
4438
4439                         for (; a_idx < arg_count; a_idx++, ++a_pos) {
4440                                 a = (Argument) arguments [a_idx];
4441                                 if (p_mod != Parameter.Modifier.PARAMS) {
4442                                         p_mod = pd.FixedParameters [a_idx].ModFlags;
4443                                         pt = pd.Types [a_idx];
4444                                         has_unsafe_arg |= pt.IsPointer;
4445
4446                                         if (p_mod == Parameter.Modifier.ARGLIST) {
4447                                                 if (a.Type != TypeManager.runtime_argument_handle_type)
4448                                                         break;
4449                                                 continue;
4450                                         }
4451
4452                                         if (p_mod == Parameter.Modifier.PARAMS) {
4453                                                 if (chose_params_expanded) {
4454                                                         params_initializers = new ArrayList (arg_count - a_idx);
4455                                                         pt = TypeManager.GetElementType (pt);
4456                                                 }
4457                                         }
4458                                 }
4459
4460                                 //
4461                                 // Types have to be identical when ref or out modifer is used
4462                                 //
4463                                 if (a.Modifier != 0 || (p_mod & ~Parameter.Modifier.PARAMS) != 0) {
4464                                         if ((p_mod & ~Parameter.Modifier.PARAMS) != a.Modifier)
4465                                                 break;
4466
4467                                         if (!TypeManager.IsEqual (a.Expr.Type, pt))
4468                                                 break;
4469
4470                                         continue;
4471                                 }
4472
4473                                 Expression conv = Convert.ImplicitConversion (ec, a.Expr, pt, loc);
4474                                 if (conv == null)
4475                                         break;
4476
4477                                 //
4478                                 // Convert params arguments to an array initializer
4479                                 //
4480                                 if (params_initializers != null) {
4481                                         // we choose to use 'a.Expr' rather than 'conv' so that
4482                                         // we don't hide the kind of expression we have (esp. CompoundAssign.Helper)
4483                                         params_initializers.Add (a.Expr);
4484                                         arguments.RemoveAt (a_idx--);
4485                                         --arg_count;
4486                                         continue;
4487                                 }
4488
4489                                 // Update the argument with the implicit conversion
4490                                 a.Expr = conv;
4491                         }
4492
4493                         //
4494                         // Fill not provided arguments required by params modifier
4495                         //
4496                         if (params_initializers == null && pd.HasParams && arg_count < pd.Count && a_idx + 1 == pd.Count) {
4497                                 if (arguments == null)
4498                                         arguments = new ArrayList (1);
4499
4500                                 pt = pd.Types [GetApplicableParametersCount (method, pd) - 1];
4501                                 pt = TypeManager.GetElementType (pt);
4502                                 has_unsafe_arg |= pt.IsPointer;
4503                                 params_initializers = new ArrayList (0);
4504                         }
4505
4506                         if (a_idx == arg_count) {
4507                                 //
4508                                 // Append an array argument with all params arguments
4509                                 //
4510                                 if (params_initializers != null) {
4511                                         arguments.Add (new Argument (
4512                                                 new ArrayCreation (new TypeExpression (pt, loc), "[]",
4513                                                 params_initializers, loc).Resolve (ec)));
4514                                 }
4515
4516                                 if (has_unsafe_arg && !ec.InUnsafe) {
4517                                         if (!may_fail)
4518                                                 UnsafeError (loc);
4519                                         return false;
4520                                 }
4521
4522                                 return true;
4523                         }
4524
4525                         if (!may_fail && Report.Errors == errors) {
4526                                 if (CustomErrorHandler != null)
4527                                         CustomErrorHandler.NoExactMatch (ec, best_candidate);
4528                                 else
4529                                         Error_InvalidArguments (ec, loc, a_pos, method, a, pd, pt);
4530                         }
4531                         return false;
4532                 }
4533         }
4534
4535         public class ConstantExpr : MemberExpr
4536         {
4537                 FieldInfo constant;
4538
4539                 public ConstantExpr (FieldInfo constant, Location loc)
4540                 {
4541                         this.constant = constant;
4542                         this.loc = loc;
4543                 }
4544
4545                 public override string Name {
4546                         get { throw new NotImplementedException (); }
4547                 }
4548
4549                 public override bool IsInstance {
4550                         get { return !IsStatic; }
4551                 }
4552
4553                 public override bool IsStatic {
4554                         get { return constant.IsStatic; }
4555                 }
4556
4557                 public override Type DeclaringType {
4558                         get { return constant.DeclaringType; }
4559                 }
4560
4561                 public override MemberExpr ResolveMemberAccess (EmitContext ec, Expression left, Location loc, SimpleName original)
4562                 {
4563                         constant = TypeManager.GetGenericFieldDefinition (constant);
4564
4565                         IConstant ic = TypeManager.GetConstant (constant);
4566                         if (ic == null) {
4567                                 if (constant.IsLiteral) {
4568                                         ic = new ExternalConstant (constant);
4569                                 } else {
4570                                         ic = ExternalConstant.CreateDecimal (constant);
4571                                         // HACK: decimal field was not resolved as constant
4572                                         if (ic == null)
4573                                                 return new FieldExpr (constant, loc).ResolveMemberAccess (ec, left, loc, original);
4574                                 }
4575                                 TypeManager.RegisterConstant (constant, ic);
4576                         }
4577
4578                         return base.ResolveMemberAccess (ec, left, loc, original);
4579                 }
4580
4581                 public override Expression CreateExpressionTree (EmitContext ec)
4582                 {
4583                         throw new NotSupportedException ("ET");
4584                 }
4585
4586                 public override Expression DoResolve (EmitContext ec)
4587                 {
4588                         IConstant ic = TypeManager.GetConstant (constant);
4589                         if (ic.ResolveValue ()) {
4590                                 if (!ec.IsInObsoleteScope)
4591                                         ic.CheckObsoleteness (loc);
4592                         }
4593
4594                         return ic.CreateConstantReference (loc);
4595                 }
4596
4597                 public override void Emit (EmitContext ec)
4598                 {
4599                         throw new NotSupportedException ();
4600                 }
4601
4602                 public override string GetSignatureForError ()
4603                 {
4604                         return TypeManager.GetFullNameSignature (constant);
4605                 }
4606         }
4607
4608         /// <summary>
4609         ///   Fully resolved expression that evaluates to a Field
4610         /// </summary>
4611         public class FieldExpr : MemberExpr, IAssignMethod, IMemoryLocation, IVariableReference {
4612                 public FieldInfo FieldInfo;
4613                 readonly Type constructed_generic_type;
4614                 VariableInfo variable_info;
4615
4616                 LocalTemporary temp;
4617                 bool prepared;
4618                 bool in_initializer;
4619
4620                 public FieldExpr (FieldInfo fi, Location l, bool in_initializer):
4621                         this (fi, l)
4622                 {
4623                         this.in_initializer = in_initializer;
4624                 }
4625
4626                 public FieldExpr (FieldInfo fi, Location l)
4627                 {
4628                         FieldInfo = fi;
4629                         eclass = ExprClass.Variable;
4630                         type = TypeManager.TypeToCoreType (fi.FieldType);
4631                         loc = l;
4632                 }
4633
4634                 public FieldExpr (FieldInfo fi, Type genericType, Location l)
4635                         : this (fi, l)
4636                 {
4637                         this.constructed_generic_type = genericType;
4638                 }
4639
4640                 public override string Name {
4641                         get {
4642                                 return FieldInfo.Name;
4643                         }
4644                 }
4645
4646                 public override bool IsInstance {
4647                         get {
4648                                 return !FieldInfo.IsStatic;
4649                         }
4650                 }
4651
4652                 public override bool IsStatic {
4653                         get {
4654                                 return FieldInfo.IsStatic;
4655                         }
4656                 }
4657
4658                 public override Type DeclaringType {
4659                         get {
4660                                 return FieldInfo.DeclaringType;
4661                         }
4662                 }
4663
4664                 public override string GetSignatureForError ()
4665                 {
4666                         return TypeManager.GetFullNameSignature (FieldInfo);
4667                 }
4668
4669                 public VariableInfo VariableInfo {
4670                         get {
4671                                 return variable_info;
4672                         }
4673                 }
4674
4675                 public override MemberExpr ResolveMemberAccess (EmitContext ec, Expression left, Location loc,
4676                                                                 SimpleName original)
4677                 {
4678                         FieldInfo fi = TypeManager.GetGenericFieldDefinition (FieldInfo);
4679                         Type t = fi.FieldType;
4680
4681                         if (t.IsPointer && !ec.InUnsafe) {
4682                                 UnsafeError (loc);
4683                         }
4684
4685                         return base.ResolveMemberAccess (ec, left, loc, original);
4686                 }
4687
4688                 public void SetHasAddressTaken ()
4689                 {
4690                         IVariableReference vr = InstanceExpression as IVariableReference;
4691                         if (vr != null)
4692                                 vr.SetHasAddressTaken ();
4693                 }
4694
4695                 public override Expression CreateExpressionTree (EmitContext ec)
4696                 {
4697                         Expression instance;
4698                         if (InstanceExpression == null) {
4699                                 instance = new NullLiteral (loc);
4700                         } else {
4701                                 instance = InstanceExpression.CreateExpressionTree (ec);
4702                         }
4703
4704                         ArrayList args = new ArrayList (2);
4705                         args.Add (new Argument (instance));
4706                         args.Add (new Argument (CreateTypeOfExpression ()));
4707                         return CreateExpressionFactoryCall ("Field", args);
4708                 }
4709
4710                 public Expression CreateTypeOfExpression ()
4711                 {
4712                         return new TypeOfField (FieldInfo, loc);
4713                 }
4714
4715                 override public Expression DoResolve (EmitContext ec)
4716                 {
4717                         return DoResolve (ec, false, false);
4718                 }
4719
4720                 Expression DoResolve (EmitContext ec, bool lvalue_instance, bool out_access)
4721                 {
4722                         if (!FieldInfo.IsStatic){
4723                                 if (InstanceExpression == null){
4724                                         //
4725                                         // This can happen when referencing an instance field using
4726                                         // a fully qualified type expression: TypeName.InstanceField = xxx
4727                                         //
4728                                         SimpleName.Error_ObjectRefRequired (ec, loc, GetSignatureForError ());
4729                                         return null;
4730                                 }
4731
4732                                 // Resolve the field's instance expression while flow analysis is turned
4733                                 // off: when accessing a field "a.b", we must check whether the field
4734                                 // "a.b" is initialized, not whether the whole struct "a" is initialized.
4735
4736                                 if (lvalue_instance) {
4737                                         using (ec.With (EmitContext.Flags.DoFlowAnalysis, false)) {
4738                                                 Expression right_side =
4739                                                         out_access ? EmptyExpression.LValueMemberOutAccess : EmptyExpression.LValueMemberAccess;
4740                                                 InstanceExpression = InstanceExpression.ResolveLValue (ec, right_side, loc);
4741                                         }
4742                                 } else {
4743                                         ResolveFlags rf = ResolveFlags.VariableOrValue | ResolveFlags.DisableFlowAnalysis;
4744                                         InstanceExpression = InstanceExpression.Resolve (ec, rf);
4745                                 }
4746
4747                                 if (InstanceExpression == null)
4748                                         return null;
4749
4750                                 using (ec.Set (EmitContext.Flags.OmitStructFlowAnalysis)) {
4751                                         InstanceExpression.CheckMarshalByRefAccess (ec);
4752                                 }
4753                         }
4754
4755                         if (!in_initializer && !ec.IsInFieldInitializer) {
4756                                 ObsoleteAttribute oa;
4757                                 FieldBase f = TypeManager.GetField (FieldInfo);
4758                                 if (f != null) {
4759                                         if (!ec.IsInObsoleteScope)
4760                                                 f.CheckObsoleteness (loc);
4761
4762                                         // To be sure that type is external because we do not register generated fields
4763                                 } else if (!(FieldInfo.DeclaringType is TypeBuilder)) {
4764                                         oa = AttributeTester.GetMemberObsoleteAttribute (FieldInfo);
4765                                         if (oa != null)
4766                                                 AttributeTester.Report_ObsoleteMessage (oa, TypeManager.GetFullNameSignature (FieldInfo), loc);
4767                                 }
4768                         }
4769
4770                         IFixedBuffer fb = AttributeTester.GetFixedBuffer (FieldInfo);
4771                         IVariableReference var = InstanceExpression as IVariableReference;
4772
4773                         if (fb != null) {
4774                                 if (!ec.InFixedInitializer && ec.ContainerType.IsValueType) {
4775                                         Report.Error (1666, loc, "You cannot use fixed size buffers contained in unfixed expressions. Try using the fixed statement");
4776                                 }
4777
4778                                 if (InstanceExpression.eclass != ExprClass.Variable) {
4779                                         Report.SymbolRelatedToPreviousError (FieldInfo);
4780                                         Report.Error (1708, loc, "`{0}': Fixed size buffers can only be accessed through locals or fields",
4781                                                 TypeManager.GetFullNameSignature (FieldInfo));
4782                                 } else if (var != null && var.IsHoisted) {
4783                                         AnonymousMethodExpression.Error_AddressOfCapturedVar (var, loc);
4784                                 }
4785
4786                                 return new FixedBufferPtr (this, fb.ElementType, loc).Resolve (ec);
4787                         }
4788
4789                         // If the instance expression is a local variable or parameter.
4790                         if (var == null || var.VariableInfo == null)
4791                                 return this;
4792
4793                         VariableInfo vi = var.VariableInfo;
4794                         if (!vi.IsFieldAssigned (ec, FieldInfo.Name, loc))
4795                                 return null;
4796
4797                         variable_info = vi.GetSubStruct (FieldInfo.Name);
4798                         return this;
4799                 }
4800
4801                 static readonly int [] codes = {
4802                         191,    // instance, write access
4803                         192,    // instance, out access
4804                         198,    // static, write access
4805                         199,    // static, out access
4806                         1648,   // member of value instance, write access
4807                         1649,   // member of value instance, out access
4808                         1650,   // member of value static, write access
4809                         1651    // member of value static, out access
4810                 };
4811
4812                 static readonly string [] msgs = {
4813                         /*0191*/ "A readonly field `{0}' cannot be assigned to (except in a constructor or a variable initializer)",
4814                         /*0192*/ "A readonly field `{0}' cannot be passed ref or out (except in a constructor)",
4815                         /*0198*/ "A static readonly field `{0}' cannot be assigned to (except in a static constructor or a variable initializer)",
4816                         /*0199*/ "A static readonly field `{0}' cannot be passed ref or out (except in a static constructor)",
4817                         /*1648*/ "Members of readonly field `{0}' cannot be modified (except in a constructor or a variable initializer)",
4818                         /*1649*/ "Members of readonly field `{0}' cannot be passed ref or out (except in a constructor)",
4819                         /*1650*/ "Fields of static readonly field `{0}' cannot be assigned to (except in a static constructor or a variable initializer)",
4820                         /*1651*/ "Fields of static readonly field `{0}' cannot be passed ref or out (except in a static constructor)"
4821                 };
4822
4823                 // The return value is always null.  Returning a value simplifies calling code.
4824                 Expression Report_AssignToReadonly (Expression right_side)
4825                 {
4826                         int i = 0;
4827                         if (right_side == EmptyExpression.OutAccess || right_side == EmptyExpression.LValueMemberOutAccess)
4828                                 i += 1;
4829                         if (IsStatic)
4830                                 i += 2;
4831                         if (right_side == EmptyExpression.LValueMemberAccess || right_side == EmptyExpression.LValueMemberOutAccess)
4832                                 i += 4;
4833                         Report.Error (codes [i], loc, msgs [i], GetSignatureForError ());
4834
4835                         return null;
4836                 }
4837
4838                 override public Expression DoResolveLValue (EmitContext ec, Expression right_side)
4839                 {
4840                         IVariableReference var = InstanceExpression as IVariableReference;
4841                         if (var != null && var.VariableInfo != null)
4842                                 var.VariableInfo.SetFieldAssigned (ec, FieldInfo.Name);
4843
4844                         bool lvalue_instance = !FieldInfo.IsStatic && FieldInfo.DeclaringType.IsValueType;
4845                         bool out_access = right_side == EmptyExpression.OutAccess || right_side == EmptyExpression.LValueMemberOutAccess;
4846
4847                         Expression e = DoResolve (ec, lvalue_instance, out_access);
4848
4849                         if (e == null)
4850                                 return null;
4851
4852                         FieldBase fb = TypeManager.GetField (FieldInfo);
4853                         if (fb != null)
4854                                 fb.SetAssigned ();
4855
4856                         if (FieldInfo.IsInitOnly) {
4857                                 // InitOnly fields can only be assigned in constructors or initializers
4858                                 if (!ec.IsInFieldInitializer && !ec.IsConstructor)
4859                                         return Report_AssignToReadonly (right_side);
4860
4861                                 if (ec.IsConstructor) {
4862                                         Type ctype = ec.TypeContainer.CurrentType;
4863                                         if (ctype == null)
4864                                                 ctype = ec.ContainerType;
4865
4866                                         // InitOnly fields cannot be assigned-to in a different constructor from their declaring type
4867                                         if (!TypeManager.IsEqual (ctype, FieldInfo.DeclaringType))
4868                                                 return Report_AssignToReadonly (right_side);
4869                                         // static InitOnly fields cannot be assigned-to in an instance constructor
4870                                         if (IsStatic && !ec.IsStatic)
4871                                                 return Report_AssignToReadonly (right_side);
4872                                         // instance constructors can't modify InitOnly fields of other instances of the same type
4873                                         if (!IsStatic && !(InstanceExpression is This))
4874                                                 return Report_AssignToReadonly (right_side);
4875                                 }
4876                         }
4877
4878                         if (right_side == EmptyExpression.OutAccess &&
4879                             !IsStatic && !(InstanceExpression is This) && TypeManager.mbr_type != null && TypeManager.IsSubclassOf (DeclaringType, TypeManager.mbr_type)) {
4880                                 Report.SymbolRelatedToPreviousError (DeclaringType);
4881                                 Report.Warning (197, 1, loc,
4882                                                 "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",
4883                                                 GetSignatureForError ());
4884                         }
4885
4886                         return this;
4887                 }
4888
4889                 bool is_marshal_by_ref ()
4890                 {
4891                         return !IsStatic && Type.IsValueType && TypeManager.mbr_type != null && TypeManager.IsSubclassOf (DeclaringType, TypeManager.mbr_type);
4892                 }
4893
4894                 public override void CheckMarshalByRefAccess (EmitContext ec)
4895                 {
4896                         if (is_marshal_by_ref () && !(InstanceExpression is This)) {
4897                                 Report.SymbolRelatedToPreviousError (DeclaringType);
4898                                 Report.Warning (1690, 1, loc, "Cannot call methods, properties, or indexers on `{0}' because it is a value type member of a marshal-by-reference class",
4899                                                 GetSignatureForError ());
4900                         }
4901                 }
4902
4903                 public override int GetHashCode ()
4904                 {
4905                         return FieldInfo.GetHashCode ();
4906                 }
4907
4908                 public bool IsFixedVariable {
4909                         get {
4910                                 //
4911                                 // A variable of the form V.I is fixed when V is a fixed variable of a struct type
4912                                 //
4913                                 IVariableReference variable = InstanceExpression as IVariableReference;
4914                                 return variable != null && InstanceExpression.Type.IsValueType && variable.IsFixedVariable;
4915                         }
4916                 }
4917
4918                 public bool IsHoisted {
4919                         get {
4920                                 IVariableReference hv = InstanceExpression as IVariableReference;
4921                                 return hv != null && hv.IsHoisted;
4922                         }
4923                 }
4924
4925                 public override bool Equals (object obj)
4926                 {
4927                         FieldExpr fe = obj as FieldExpr;
4928                         if (fe == null)
4929                                 return false;
4930
4931                         if (FieldInfo != fe.FieldInfo)
4932                                 return false;
4933
4934                         if (InstanceExpression == null || fe.InstanceExpression == null)
4935                                 return true;
4936
4937                         return InstanceExpression.Equals (fe.InstanceExpression);
4938                 }
4939
4940                 public void Emit (EmitContext ec, bool leave_copy)
4941                 {
4942                         ILGenerator ig = ec.ig;
4943                         bool is_volatile = false;
4944
4945                         FieldBase f = TypeManager.GetField (FieldInfo);
4946                         if (f != null){
4947                                 if ((f.ModFlags & Modifiers.VOLATILE) != 0)
4948                                         is_volatile = true;
4949
4950                                 f.SetMemberIsUsed ();
4951                         }
4952
4953                         if (FieldInfo.IsStatic){
4954                                 if (is_volatile)
4955                                         ig.Emit (OpCodes.Volatile);
4956
4957                                 ig.Emit (OpCodes.Ldsfld, GetConstructedFieldInfo ());
4958                         } else {
4959                                 if (!prepared)
4960                                         EmitInstance (ec, false);
4961
4962                                 IFixedBuffer ff = AttributeTester.GetFixedBuffer (FieldInfo);
4963                                 if (ff != null) {
4964                                         ig.Emit (OpCodes.Ldflda, GetConstructedFieldInfo ());
4965                                         ig.Emit (OpCodes.Ldflda, ff.Element);
4966                                 } else {
4967                                         if (is_volatile)
4968                                                 ig.Emit (OpCodes.Volatile);
4969
4970                                         ig.Emit (OpCodes.Ldfld, GetConstructedFieldInfo ());
4971                                 }
4972                         }
4973
4974                         if (leave_copy) {
4975                                 ec.ig.Emit (OpCodes.Dup);
4976                                 if (!FieldInfo.IsStatic) {
4977                                         temp = new LocalTemporary (this.Type);
4978                                         temp.Store (ec);
4979                                 }
4980                         }
4981                 }
4982
4983                 public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool prepare_for_load)
4984                 {
4985                         FieldAttributes fa = FieldInfo.Attributes;
4986                         bool is_static = (fa & FieldAttributes.Static) != 0;
4987                         bool is_readonly = (fa & FieldAttributes.InitOnly) != 0;
4988                         ILGenerator ig = ec.ig;
4989
4990                         if (is_readonly && !ec.IsConstructor){
4991                                 Report_AssignToReadonly (source);
4992                                 return;
4993                         }
4994
4995                         prepared = prepare_for_load;
4996                         EmitInstance (ec, prepared);
4997
4998                         source.Emit (ec);
4999                         if (leave_copy) {
5000                                 ec.ig.Emit (OpCodes.Dup);
5001                                 if (!FieldInfo.IsStatic) {
5002                                         temp = new LocalTemporary (this.Type);
5003                                         temp.Store (ec);
5004                                 }
5005                         }
5006
5007                         FieldBase f = TypeManager.GetField (FieldInfo);
5008                         if (f != null){
5009                                 if ((f.ModFlags & Modifiers.VOLATILE) != 0)
5010                                         ig.Emit (OpCodes.Volatile);
5011
5012                                 f.SetAssigned ();
5013                         }
5014
5015                         if (is_static)
5016                                 ig.Emit (OpCodes.Stsfld, GetConstructedFieldInfo ());
5017                         else
5018                                 ig.Emit (OpCodes.Stfld, GetConstructedFieldInfo ());
5019
5020                         if (temp != null) {
5021                                 temp.Emit (ec);
5022                                 temp.Release (ec);
5023                                 temp = null;
5024                         }
5025                 }
5026
5027                 public override void Emit (EmitContext ec)
5028                 {
5029                         Emit (ec, false);
5030                 }
5031
5032                 public override void EmitSideEffect (EmitContext ec)
5033                 {
5034                         FieldBase f = TypeManager.GetField (FieldInfo);
5035                         bool is_volatile = f != null && (f.ModFlags & Modifiers.VOLATILE) != 0;
5036
5037                         if (is_volatile || is_marshal_by_ref ())
5038                                 base.EmitSideEffect (ec);
5039                 }
5040
5041                 public override void Error_VariableIsUsedBeforeItIsDeclared (string name)
5042                 {
5043                         Report.Error (844, loc,
5044                                 "A local variable `{0}' cannot be used before it is declared. Consider renaming the local variable when it hides the field `{1}'",
5045                                 name, GetSignatureForError ());
5046                 }
5047
5048                 public void AddressOf (EmitContext ec, AddressOp mode)
5049                 {
5050                         ILGenerator ig = ec.ig;
5051
5052                         FieldBase f = TypeManager.GetField (FieldInfo);
5053                         if (f != null){
5054                                 if ((f.ModFlags & Modifiers.VOLATILE) != 0){
5055                                         Report.Warning (420, 1, loc, "`{0}': A volatile field references will not be treated as volatile",
5056                                                         f.GetSignatureForError ());
5057                                 }
5058
5059                                 if ((mode & AddressOp.Store) != 0)
5060                                         f.SetAssigned ();
5061                                 if ((mode & AddressOp.Load) != 0)
5062                                         f.SetMemberIsUsed ();
5063                         }
5064
5065                         //
5066                         // Handle initonly fields specially: make a copy and then
5067                         // get the address of the copy.
5068                         //
5069                         bool need_copy;
5070                         if (FieldInfo.IsInitOnly){
5071                                 need_copy = true;
5072                                 if (ec.IsConstructor){
5073                                         if (FieldInfo.IsStatic){
5074                                                 if (ec.IsStatic)
5075                                                         need_copy = false;
5076                                         } else
5077                                                 need_copy = false;
5078                                 }
5079                         } else
5080                                 need_copy = false;
5081
5082                         if (need_copy){
5083                                 LocalBuilder local;
5084                                 Emit (ec);
5085                                 local = ig.DeclareLocal (type);
5086                                 ig.Emit (OpCodes.Stloc, local);
5087                                 ig.Emit (OpCodes.Ldloca, local);
5088                                 return;
5089                         }
5090
5091
5092                         if (FieldInfo.IsStatic){
5093                                 ig.Emit (OpCodes.Ldsflda, GetConstructedFieldInfo ());
5094                         } else {
5095                                 if (!prepared)
5096                                         EmitInstance (ec, false);
5097                                 ig.Emit (OpCodes.Ldflda, GetConstructedFieldInfo ());
5098                         }
5099                 }
5100
5101                 FieldInfo GetConstructedFieldInfo ()
5102                 {
5103                         if (constructed_generic_type == null)
5104                                 return FieldInfo;
5105 #if GMCS_SOURCE
5106                         return TypeBuilder.GetField (constructed_generic_type, FieldInfo);
5107 #else
5108                         throw new NotSupportedException ();
5109 #endif
5110                 }
5111
5112                 public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
5113                 {
5114                         FieldInfo = storey.MutateField (FieldInfo);
5115                         base.MutateHoistedGenericType (storey);
5116                 }
5117         }
5118
5119
5120         /// <summary>
5121         ///   Expression that evaluates to a Property.  The Assign class
5122         ///   might set the `Value' expression if we are in an assignment.
5123         ///
5124         ///   This is not an LValue because we need to re-write the expression, we
5125         ///   can not take data from the stack and store it.
5126         /// </summary>
5127         public class PropertyExpr : MemberExpr, IAssignMethod {
5128                 public readonly PropertyInfo PropertyInfo;
5129                 MethodInfo getter, setter;
5130                 bool is_static;
5131
5132                 bool resolved;
5133
5134                 LocalTemporary temp;
5135                 bool prepared;
5136
5137                 public PropertyExpr (Type container_type, PropertyInfo pi, Location l)
5138                 {
5139                         PropertyInfo = pi;
5140                         eclass = ExprClass.PropertyAccess;
5141                         is_static = false;
5142                         loc = l;
5143
5144                         type = TypeManager.TypeToCoreType (pi.PropertyType);
5145
5146                         ResolveAccessors (container_type);
5147                 }
5148
5149                 public override string Name {
5150                         get {
5151                                 return PropertyInfo.Name;
5152                         }
5153                 }
5154
5155                 public override bool IsInstance {
5156                         get {
5157                                 return !is_static;
5158                         }
5159                 }
5160
5161                 public override bool IsStatic {
5162                         get {
5163                                 return is_static;
5164                         }
5165                 }
5166
5167                 public override Expression CreateExpressionTree (EmitContext ec)
5168                 {
5169                         ArrayList args;
5170                         if (IsSingleDimensionalArrayLength ()) {
5171                                 args = new ArrayList (1);
5172                                 args.Add (new Argument (InstanceExpression.CreateExpressionTree (ec)));
5173                                 return CreateExpressionFactoryCall ("ArrayLength", args);
5174                         }
5175
5176                         if (is_base) {
5177                                 Error_BaseAccessInExpressionTree (loc);
5178                                 return null;
5179                         }
5180
5181                         args = new ArrayList (2);
5182                         if (InstanceExpression == null)
5183                                 args.Add (new Argument (new NullLiteral (loc)));
5184                         else
5185                                 args.Add (new Argument (InstanceExpression.CreateExpressionTree (ec)));
5186                         args.Add (new Argument (new TypeOfMethodInfo (getter, loc)));
5187                         return CreateExpressionFactoryCall ("Property", args);
5188                 }
5189
5190                 public Expression CreateSetterTypeOfExpression ()
5191                 {
5192                         return new TypeOfMethodInfo (setter, loc);
5193                 }
5194
5195                 public override Type DeclaringType {
5196                         get {
5197                                 return PropertyInfo.DeclaringType;
5198                         }
5199                 }
5200
5201                 public override string GetSignatureForError ()
5202                 {
5203                         return TypeManager.GetFullNameSignature (PropertyInfo);
5204                 }
5205
5206                 void FindAccessors (Type invocation_type)
5207                 {
5208                         const BindingFlags flags = BindingFlags.Public | BindingFlags.NonPublic |
5209                                 BindingFlags.Static | BindingFlags.Instance |
5210                                 BindingFlags.DeclaredOnly;
5211
5212                         Type current = PropertyInfo.DeclaringType;
5213                         for (; current != null; current = current.BaseType) {
5214                                 MemberInfo[] group = TypeManager.MemberLookup (
5215                                         invocation_type, invocation_type, current,
5216                                         MemberTypes.Property, flags, PropertyInfo.Name, null);
5217
5218                                 if (group == null)
5219                                         continue;
5220
5221                                 if (group.Length != 1)
5222                                         // Oooops, can this ever happen ?
5223                                         return;
5224
5225                                 PropertyInfo pi = (PropertyInfo) group [0];
5226
5227                                 if (getter == null)
5228                                         getter = pi.GetGetMethod (true);
5229
5230                                 if (setter == null)
5231                                         setter = pi.GetSetMethod (true);
5232
5233                                 MethodInfo accessor = getter != null ? getter : setter;
5234
5235                                 if (!accessor.IsVirtual)
5236                                         return;
5237                         }
5238                 }
5239
5240                 //
5241                 // We also perform the permission checking here, as the PropertyInfo does not
5242                 // hold the information for the accessibility of its setter/getter
5243                 //
5244                 // TODO: Refactor to use some kind of cache together with GetPropertyFromAccessor
5245                 void ResolveAccessors (Type container_type)
5246                 {
5247                         FindAccessors (container_type);
5248
5249                         if (getter != null) {
5250                                 MethodBase the_getter = TypeManager.DropGenericMethodArguments (getter);
5251                                 IMethodData md = TypeManager.GetMethod (the_getter);
5252                                 if (md != null)
5253                                         md.SetMemberIsUsed ();
5254
5255                                 is_static = getter.IsStatic;
5256                         }
5257
5258                         if (setter != null) {
5259                                 MethodBase the_setter = TypeManager.DropGenericMethodArguments (setter);
5260                                 IMethodData md = TypeManager.GetMethod (the_setter);
5261                                 if (md != null)
5262                                         md.SetMemberIsUsed ();
5263
5264                                 is_static = setter.IsStatic;
5265                         }
5266                 }
5267
5268                 public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
5269                 {
5270                         if (InstanceExpression != null)
5271                                 InstanceExpression.MutateHoistedGenericType (storey);
5272
5273                         type = storey.MutateType (type);
5274                         getter = storey.MutateGenericMethod (getter);
5275                 }
5276
5277                 bool InstanceResolve (EmitContext ec, bool lvalue_instance, bool must_do_cs1540_check)
5278                 {
5279                         if (is_static) {
5280                                 InstanceExpression = null;
5281                                 return true;
5282                         }
5283
5284                         if (InstanceExpression == null) {
5285                                 SimpleName.Error_ObjectRefRequired (ec, loc, GetSignatureForError ());
5286                                 return false;
5287                         }
5288
5289                         InstanceExpression = InstanceExpression.DoResolve (ec);
5290                         if (lvalue_instance && InstanceExpression != null)
5291                                 InstanceExpression = InstanceExpression.ResolveLValue (ec, EmptyExpression.LValueMemberAccess, loc);
5292
5293                         if (InstanceExpression == null)
5294                                 return false;
5295
5296                         InstanceExpression.CheckMarshalByRefAccess (ec);
5297
5298                         if (must_do_cs1540_check && (InstanceExpression != EmptyExpression.Null) &&
5299                             !TypeManager.IsInstantiationOfSameGenericType (InstanceExpression.Type, ec.ContainerType) &&
5300                             !TypeManager.IsNestedChildOf (ec.ContainerType, InstanceExpression.Type) &&
5301                             !TypeManager.IsSubclassOf (InstanceExpression.Type, ec.ContainerType)) {
5302                                 Report.SymbolRelatedToPreviousError (PropertyInfo);
5303                                 Error_CannotAccessProtected (loc, PropertyInfo, InstanceExpression.Type, ec.ContainerType);
5304                                 return false;
5305                         }
5306
5307                         return true;
5308                 }
5309
5310                 void Error_PropertyNotFound (MethodInfo mi, bool getter)
5311                 {
5312                         // TODO: correctly we should compare arguments but it will lead to bigger changes
5313                         if (mi is MethodBuilder) {
5314                                 Error_TypeDoesNotContainDefinition (loc, PropertyInfo.DeclaringType, Name);
5315                                 return;
5316                         }
5317
5318                         StringBuilder sig = new StringBuilder (TypeManager.CSharpName (mi.DeclaringType));
5319                         sig.Append ('.');
5320                         AParametersCollection iparams = TypeManager.GetParameterData (mi);
5321                         sig.Append (getter ? "get_" : "set_");
5322                         sig.Append (Name);
5323                         sig.Append (iparams.GetSignatureForError ());
5324
5325                         Report.SymbolRelatedToPreviousError (mi);
5326                         Report.Error (1546, loc, "Property `{0}' is not supported by the C# language. Try to call the accessor method `{1}' directly",
5327                                 Name, sig.ToString ());
5328                 }
5329
5330                 public bool IsAccessibleFrom (Type invocation_type, bool lvalue)
5331                 {
5332                         bool dummy;
5333                         MethodInfo accessor = lvalue ? setter : getter;
5334                         if (accessor == null && lvalue)
5335                                 accessor = getter;
5336                         return accessor != null && IsAccessorAccessible (invocation_type, accessor, out dummy);
5337                 }
5338
5339                 bool IsSingleDimensionalArrayLength ()
5340                 {
5341                         if (DeclaringType != TypeManager.array_type || getter == null || Name != "Length")
5342                                 return false;
5343
5344                         string t_name = InstanceExpression.Type.Name;
5345                         int t_name_len = t_name.Length;
5346                         return t_name_len > 2 && t_name [t_name_len - 2] == '[';
5347                 }
5348
5349                 override public Expression DoResolve (EmitContext ec)
5350                 {
5351                         if (resolved)
5352                                 return this;
5353
5354                         if (getter != null){
5355                                 if (TypeManager.GetParameterData (getter).Count != 0){
5356                                         Error_PropertyNotFound (getter, true);
5357                                         return null;
5358                                 }
5359                         }
5360
5361                         if (getter == null){
5362                                 //
5363                                 // The following condition happens if the PropertyExpr was
5364                                 // created, but is invalid (ie, the property is inaccessible),
5365                                 // and we did not want to embed the knowledge about this in
5366                                 // the caller routine.  This only avoids double error reporting.
5367                                 //
5368                                 if (setter == null)
5369                                         return null;
5370
5371                                 if (InstanceExpression != EmptyExpression.Null) {
5372                                         Report.Error (154, loc, "The property or indexer `{0}' cannot be used in this context because it lacks the `get' accessor",
5373                                                 TypeManager.GetFullNameSignature (PropertyInfo));
5374                                         return null;
5375                                 }
5376                         }
5377
5378                         bool must_do_cs1540_check = false;
5379                         if (getter != null &&
5380                             !IsAccessorAccessible (ec.ContainerType, getter, out must_do_cs1540_check)) {
5381                                 PropertyBase.PropertyMethod pm = TypeManager.GetMethod (getter) as PropertyBase.PropertyMethod;
5382                                 if (pm != null && pm.HasCustomAccessModifier) {
5383                                         Report.SymbolRelatedToPreviousError (pm);
5384                                         Report.Error (271, loc, "The property or indexer `{0}' cannot be used in this context because the get accessor is inaccessible",
5385                                                 TypeManager.CSharpSignature (getter));
5386                                 }
5387                                 else {
5388                                         Report.SymbolRelatedToPreviousError (getter);
5389                                         ErrorIsInaccesible (loc, TypeManager.CSharpSignature (getter));
5390                                 }
5391                                 return null;
5392                         }
5393
5394                         if (!InstanceResolve (ec, false, must_do_cs1540_check))
5395                                 return null;
5396
5397                         //
5398                         // Only base will allow this invocation to happen.
5399                         //
5400                         if (IsBase && getter.IsAbstract) {
5401                                 Error_CannotCallAbstractBase (TypeManager.GetFullNameSignature (PropertyInfo));
5402                                 return null;
5403                         }
5404
5405                         if (PropertyInfo.PropertyType.IsPointer && !ec.InUnsafe){
5406                                 UnsafeError (loc);
5407                                 return null;
5408                         }
5409
5410                         resolved = true;
5411
5412                         return this;
5413                 }
5414
5415                 override public Expression DoResolveLValue (EmitContext ec, Expression right_side)
5416                 {
5417                         if (right_side == EmptyExpression.OutAccess) {
5418                                 if (ec.CurrentBlock.Toplevel.GetTransparentIdentifier (PropertyInfo.Name) != null) {
5419                                         Report.Error (1939, loc, "A range variable `{0}' may not be passes as `ref' or `out' parameter",
5420                                             PropertyInfo.Name);
5421                                 } else {
5422                                         Report.Error (206, loc, "A property or indexer `{0}' may not be passed as `ref' or `out' parameter",
5423                                               GetSignatureForError ());
5424                                 }
5425                                 return null;
5426                         }
5427
5428                         if (right_side == EmptyExpression.LValueMemberAccess || right_side == EmptyExpression.LValueMemberOutAccess) {
5429                                 Error_CannotModifyIntermediateExpressionValue (ec);
5430                         }
5431
5432                         if (setter == null){
5433                                 //
5434                                 // The following condition happens if the PropertyExpr was
5435                                 // created, but is invalid (ie, the property is inaccessible),
5436                                 // and we did not want to embed the knowledge about this in
5437                                 // the caller routine.  This only avoids double error reporting.
5438                                 //
5439                                 if (getter == null)
5440                                         return null;
5441
5442                                 if (ec.CurrentBlock.Toplevel.GetTransparentIdentifier (PropertyInfo.Name) != null) {
5443                                         Report.Error (1947, loc, "A range variable `{0}' cannot be assigned to. Consider using `let' clause to store the value",
5444                                                 PropertyInfo.Name);
5445                                 } else {
5446                                         Report.Error (200, loc, "Property or indexer `{0}' cannot be assigned to (it is read only)",
5447                                                 GetSignatureForError ());
5448                                 }
5449                                 return null;
5450                         }
5451
5452                         if (TypeManager.GetParameterData (setter).Count != 1){
5453                                 Error_PropertyNotFound (setter, false);
5454                                 return null;
5455                         }
5456
5457                         bool must_do_cs1540_check;
5458                         if (!IsAccessorAccessible (ec.ContainerType, setter, out must_do_cs1540_check)) {
5459                                 PropertyBase.PropertyMethod pm = TypeManager.GetMethod (setter) as PropertyBase.PropertyMethod;
5460                                 if (pm != null && pm.HasCustomAccessModifier) {
5461                                         Report.SymbolRelatedToPreviousError (pm);
5462                                         Report.Error (272, loc, "The property or indexer `{0}' cannot be used in this context because the set accessor is inaccessible",
5463                                                 TypeManager.CSharpSignature (setter));
5464                                 }
5465                                 else {
5466                                         Report.SymbolRelatedToPreviousError (setter);
5467                                         ErrorIsInaccesible (loc, TypeManager.CSharpSignature (setter));
5468                                 }
5469                                 return null;
5470                         }
5471
5472                         if (!InstanceResolve (ec, PropertyInfo.DeclaringType.IsValueType, must_do_cs1540_check))
5473                                 return null;
5474
5475                         //
5476                         // Only base will allow this invocation to happen.
5477                         //
5478                         if (IsBase && setter.IsAbstract){
5479                                 Error_CannotCallAbstractBase (TypeManager.GetFullNameSignature (PropertyInfo));
5480                                 return null;
5481                         }
5482
5483                         if (PropertyInfo.PropertyType.IsPointer && !ec.InUnsafe) {
5484                                 UnsafeError (loc);
5485                         }
5486
5487                         return this;
5488                 }
5489
5490                 public override void Emit (EmitContext ec)
5491                 {
5492                         Emit (ec, false);
5493                 }
5494
5495                 public void Emit (EmitContext ec, bool leave_copy)
5496                 {
5497                         //
5498                         // Special case: length of single dimension array property is turned into ldlen
5499                         //
5500                         if (IsSingleDimensionalArrayLength ()) {
5501                                 if (!prepared)
5502                                         EmitInstance (ec, false);
5503                                 ec.ig.Emit (OpCodes.Ldlen);
5504                                 ec.ig.Emit (OpCodes.Conv_I4);
5505                                 return;
5506                         }
5507
5508                         Invocation.EmitCall (ec, IsBase, InstanceExpression, getter, null, loc, prepared, false);
5509
5510                         if (leave_copy) {
5511                                 ec.ig.Emit (OpCodes.Dup);
5512                                 if (!is_static) {
5513                                         temp = new LocalTemporary (this.Type);
5514                                         temp.Store (ec);
5515                                 }
5516                         }
5517                 }
5518
5519                 //
5520                 // Implements the IAssignMethod interface for assignments
5521                 //
5522                 public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool prepare_for_load)
5523                 {
5524                         Expression my_source = source;
5525
5526                         if (prepare_for_load) {
5527                                 prepared = true;
5528                                 source.Emit (ec);
5529
5530                                 if (leave_copy) {
5531                                         ec.ig.Emit (OpCodes.Dup);
5532                                         if (!is_static) {
5533                                                 temp = new LocalTemporary (this.Type);
5534                                                 temp.Store (ec);
5535                                         }
5536                                 }
5537                         } else if (leave_copy) {
5538                                 source.Emit (ec);
5539                                 temp = new LocalTemporary (this.Type);
5540                                 temp.Store (ec);
5541                                 my_source = temp;
5542                         }
5543
5544                         ArrayList args = new ArrayList (1);
5545                         args.Add (new Argument (my_source, Argument.AType.Expression));
5546
5547                         Invocation.EmitCall (ec, IsBase, InstanceExpression, setter, args, loc, false, prepared);
5548
5549                         if (temp != null) {
5550                                 temp.Emit (ec);
5551                                 temp.Release (ec);
5552                         }
5553                 }
5554         }
5555
5556         /// <summary>
5557         ///   Fully resolved expression that evaluates to an Event
5558         /// </summary>
5559         public class EventExpr : MemberExpr {
5560                 public readonly EventInfo EventInfo;
5561
5562                 bool is_static;
5563                 MethodInfo add_accessor, remove_accessor;
5564
5565                 public EventExpr (EventInfo ei, Location loc)
5566                 {
5567                         EventInfo = ei;
5568                         this.loc = loc;
5569                         eclass = ExprClass.EventAccess;
5570
5571                         add_accessor = TypeManager.GetAddMethod (ei);
5572                         remove_accessor = TypeManager.GetRemoveMethod (ei);
5573                         if (add_accessor.IsStatic || remove_accessor.IsStatic)
5574                                 is_static = true;
5575
5576                         if (EventInfo is MyEventBuilder){
5577                                 MyEventBuilder eb = (MyEventBuilder) EventInfo;
5578                                 type = eb.EventType;
5579                                 eb.SetUsed ();
5580                         } else
5581                                 type = EventInfo.EventHandlerType;
5582                 }
5583
5584                 public override string Name {
5585                         get {
5586                                 return EventInfo.Name;
5587                         }
5588                 }
5589
5590                 public override bool IsInstance {
5591                         get {
5592                                 return !is_static;
5593                         }
5594                 }
5595
5596                 public override bool IsStatic {
5597                         get {
5598                                 return is_static;
5599                         }
5600                 }
5601
5602                 public override Type DeclaringType {
5603                         get {
5604                                 return EventInfo.DeclaringType;
5605                         }
5606                 }
5607
5608                 void Error_AssignmentEventOnly ()
5609                 {
5610                         Report.Error (79, loc, "The event `{0}' can only appear on the left hand side of `+=' or `-=' operator",
5611                                 GetSignatureForError ());
5612                 }
5613
5614                 public override MemberExpr ResolveMemberAccess (EmitContext ec, Expression left, Location loc,
5615                                                                 SimpleName original)
5616                 {
5617                         //
5618                         // If the event is local to this class, we transform ourselves into a FieldExpr
5619                         //
5620
5621                         if (EventInfo.DeclaringType == ec.ContainerType ||
5622                             TypeManager.IsNestedChildOf(ec.ContainerType, EventInfo.DeclaringType)) {
5623                                 EventField mi = TypeManager.GetEventField (EventInfo);
5624
5625                                 if (mi != null) {
5626                                         if (!ec.IsInObsoleteScope)
5627                                                 mi.CheckObsoleteness (loc);
5628
5629                                         if ((mi.ModFlags & (Modifiers.ABSTRACT | Modifiers.EXTERN)) != 0 && !ec.IsInCompoundAssignment)
5630                                                 Error_AssignmentEventOnly ();
5631
5632                                         FieldExpr ml = new FieldExpr (mi.FieldBuilder, loc);
5633
5634                                         InstanceExpression = null;
5635
5636                                         return ml.ResolveMemberAccess (ec, left, loc, original);
5637                                 }
5638                         }
5639
5640                         if (left is This && !ec.IsInCompoundAssignment)
5641                                 Error_AssignmentEventOnly ();
5642
5643                         return base.ResolveMemberAccess (ec, left, loc, original);
5644                 }
5645
5646                 bool InstanceResolve (EmitContext ec, bool must_do_cs1540_check)
5647                 {
5648                         if (is_static) {
5649                                 InstanceExpression = null;
5650                                 return true;
5651                         }
5652
5653                         if (InstanceExpression == null) {
5654                                 SimpleName.Error_ObjectRefRequired (ec, loc, GetSignatureForError ());
5655                                 return false;
5656                         }
5657
5658                         InstanceExpression = InstanceExpression.DoResolve (ec);
5659                         if (InstanceExpression == null)
5660                                 return false;
5661
5662                         if (IsBase && add_accessor.IsAbstract) {
5663                                 Error_CannotCallAbstractBase(TypeManager.CSharpSignature(add_accessor));
5664                                 return false;
5665                         }
5666
5667                         //
5668                         // This is using the same mechanism as the CS1540 check in PropertyExpr.
5669                         // However, in the Event case, we reported a CS0122 instead.
5670                         //
5671                         // TODO: Exact copy from PropertyExpr
5672                         //
5673                         if (must_do_cs1540_check && InstanceExpression != EmptyExpression.Null &&
5674                             !TypeManager.IsInstantiationOfSameGenericType (InstanceExpression.Type, ec.ContainerType) &&
5675                             !TypeManager.IsNestedChildOf (ec.ContainerType, InstanceExpression.Type) &&
5676                             !TypeManager.IsSubclassOf (InstanceExpression.Type, ec.ContainerType)) {
5677                                 Report.SymbolRelatedToPreviousError (EventInfo);
5678                                 ErrorIsInaccesible (loc, TypeManager.CSharpSignature (EventInfo));
5679                                 return false;
5680                         }
5681
5682                         return true;
5683                 }
5684
5685                 public bool IsAccessibleFrom (Type invocation_type)
5686                 {
5687                         bool dummy;
5688                         return IsAccessorAccessible (invocation_type, add_accessor, out dummy) &&
5689                                 IsAccessorAccessible (invocation_type, remove_accessor, out dummy);
5690                 }
5691
5692                 public override Expression CreateExpressionTree (EmitContext ec)
5693                 {
5694                         throw new NotSupportedException ("ET");
5695                 }
5696
5697                 public override Expression DoResolveLValue (EmitContext ec, Expression right_side)
5698                 {
5699                         // contexts where an LValue is valid have already devolved to FieldExprs
5700                         Error_CannotAssign ();
5701                         return null;
5702                 }
5703
5704                 public override Expression DoResolve (EmitContext ec)
5705                 {
5706                         bool must_do_cs1540_check;
5707                         if (!(IsAccessorAccessible (ec.ContainerType, add_accessor, out must_do_cs1540_check) &&
5708                               IsAccessorAccessible (ec.ContainerType, remove_accessor, out must_do_cs1540_check))) {
5709                                 Report.SymbolRelatedToPreviousError (EventInfo);
5710                                 ErrorIsInaccesible (loc, TypeManager.CSharpSignature (EventInfo));
5711                                 return null;
5712                         }
5713
5714                         if (!InstanceResolve (ec, must_do_cs1540_check))
5715                                 return null;
5716
5717                         if (!ec.IsInCompoundAssignment) {
5718                                 Error_CannotAssign ();
5719                                 return null;
5720                         }
5721
5722                         return this;
5723                 }
5724
5725                 public override void Emit (EmitContext ec)
5726                 {
5727                         Error_CannotAssign ();
5728                 }
5729
5730                 public void Error_CannotAssign ()
5731                 {
5732                         Report.Error (70, loc,
5733                                 "The event `{0}' can only appear on the left hand side of += or -= when used outside of the type `{1}'",
5734                                 GetSignatureForError (), TypeManager.CSharpName (EventInfo.DeclaringType));
5735                 }
5736
5737                 public override string GetSignatureForError ()
5738                 {
5739                         return TypeManager.CSharpSignature (EventInfo);
5740                 }
5741
5742                 public void EmitAddOrRemove (EmitContext ec, bool is_add, Expression source)
5743                 {
5744                         ArrayList args = new ArrayList (1);
5745                         args.Add (new Argument (source, Argument.AType.Expression));
5746                         Invocation.EmitCall (ec, IsBase, InstanceExpression, is_add ? add_accessor : remove_accessor, args, loc);
5747                 }
5748         }
5749
5750         public class TemporaryVariable : VariableReference
5751         {
5752                 LocalInfo li;
5753
5754                 public TemporaryVariable (Type type, Location loc)
5755                 {
5756                         this.type = type;
5757                         this.loc = loc;
5758                         eclass = ExprClass.Variable;
5759                 }
5760
5761                 public override Expression CreateExpressionTree (EmitContext ec)
5762                 {
5763                         throw new NotSupportedException ("ET");
5764                 }
5765
5766                 public override Expression DoResolve (EmitContext ec)
5767                 {
5768                         if (li != null)
5769                                 return this;
5770
5771                         TypeExpr te = new TypeExpression (type, loc);
5772                         li = ec.CurrentBlock.AddTemporaryVariable (te, loc);
5773                         if (!li.Resolve (ec))
5774                                 return null;
5775
5776                         //
5777                         // Don't capture temporary variables except when using
5778                         // iterator redirection
5779                         //
5780                         if (ec.CurrentAnonymousMethod != null && ec.CurrentAnonymousMethod.IsIterator && ec.IsVariableCapturingRequired) {
5781                                 AnonymousMethodStorey storey = li.Block.Explicit.CreateAnonymousMethodStorey (ec);
5782                                 storey.CaptureLocalVariable (ec, li);
5783                         }
5784
5785                         return this;
5786                 }
5787
5788                 public override Expression DoResolveLValue (EmitContext ec, Expression right_side)
5789                 {
5790                         return DoResolve (ec);
5791                 }
5792
5793                 public override void Emit (EmitContext ec)
5794                 {
5795                         Emit (ec, false);
5796                 }
5797
5798                 public void EmitAssign (EmitContext ec, Expression source)
5799                 {
5800                         EmitAssign (ec, source, false, false);
5801                 }
5802
5803                 public override HoistedVariable HoistedVariable {
5804                         get { return li.HoistedVariableReference; }
5805                 }
5806
5807                 public override bool IsFixedVariable {
5808                         get { return true; }
5809                 }
5810
5811                 public override bool IsRef {
5812                         get { return false; }
5813                 }
5814
5815                 public override string Name {
5816                         get { throw new NotImplementedException (); }
5817                 }
5818
5819                 public override void SetHasAddressTaken ()
5820                 {
5821                         throw new NotImplementedException ();
5822                 }
5823
5824                 protected override ILocalVariable Variable {
5825                         get { return li; }
5826                 }
5827
5828                 public override VariableInfo VariableInfo {
5829                         get { throw new NotImplementedException (); }
5830                 }
5831         }
5832
5833         ///
5834         /// Handles `var' contextual keyword; var becomes a keyword only
5835         /// if no type called var exists in a variable scope
5836         ///
5837         public class VarExpr : SimpleName
5838         {
5839                 // Used for error reporting only
5840                 ArrayList initializer;
5841
5842                 public VarExpr (Location loc)
5843                         : base ("var", loc)
5844                 {
5845                 }
5846
5847                 public ArrayList VariableInitializer {
5848                         set {
5849                                 this.initializer = value;
5850                         }
5851                 }
5852
5853                 public bool InferType (EmitContext ec, Expression right_side)
5854                 {
5855                         if (type != null)
5856                                 throw new InternalErrorException ("An implicitly typed local variable could not be redefined");
5857
5858                         type = right_side.Type;
5859                         if (type == TypeManager.null_type || type == TypeManager.void_type || type == TypeManager.anonymous_method_type) {
5860                                 Report.Error (815, loc, "An implicitly typed local variable declaration cannot be initialized with `{0}'",
5861                                               right_side.GetSignatureForError ());
5862                                 return false;
5863                         }
5864
5865                         eclass = ExprClass.Variable;
5866                         return true;
5867                 }
5868
5869                 protected override void Error_TypeOrNamespaceNotFound (IResolveContext ec)
5870                 {
5871                         Report.Error (825, loc, "The contextual keyword `var' may only appear within a local variable declaration");
5872                 }
5873
5874                 public override TypeExpr ResolveAsContextualType (IResolveContext rc, bool silent)
5875                 {
5876                         TypeExpr te = base.ResolveAsContextualType (rc, true);
5877                         if (te != null)
5878                                 return te;
5879
5880                         if (initializer == null)
5881                                 return null;
5882
5883                         if (initializer.Count > 1) {
5884                                 Location loc = ((Mono.CSharp.CSharpParser.VariableDeclaration)initializer [1]).Location;
5885                                 Report.Error (819, loc, "An implicitly typed local variable declaration cannot include multiple declarators");
5886                                 initializer = null;
5887                                 return null;
5888                         }
5889
5890                         Expression variable_initializer = ((Mono.CSharp.CSharpParser.VariableDeclaration)initializer [0]).expression_or_array_initializer;
5891                         if (variable_initializer == null) {
5892                                 Report.Error (818, loc, "An implicitly typed local variable declarator must include an initializer");
5893                                 return null;
5894                         }
5895
5896                         return null;
5897                 }
5898         }
5899 }