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                 MethodGroup,
  35                 PropertyAccess,
  36                 EventAccess,
  37                 IndexerAccess,
  38                 Nothing,
  39         }
  40
  41         /// <remarks>
  42         ///   This is used to tell Resolve in which types of expressions we're
  43         ///   interested.
  44         /// </remarks>
  45         [Flags]
  46         public enum ResolveFlags {
  47                 // Returns Value, Variable, PropertyAccess, EventAccess or IndexerAccess.
  48                 VariableOrValue         = 1,
  49
  50                 // Returns a type expression.
  51                 Type                    = 2,
  52
  53                 // Returns a method group.
  54                 MethodGroup             = 4,
  55
  56                 // Mask of all the expression class flags.
  57                 MaskExprClass           = 7,
  58
  59                 // Disable control flow analysis while resolving the expression.
  60                 // This is used when resolving the instance expression of a field expression.
  61                 DisableFlowAnalysis     = 8,
  62
  63                 // Set if this is resolving the first part of a MemberAccess.
  64                 Intermediate            = 16,
  65
  66                 // Disable control flow analysis _of struct_ while resolving the expression.
  67                 // This is used when resolving the instance expression of a field expression.
  68                 DisableStructFlowAnalysis       = 32,
  69
  70         }
  71
  72         //
  73         // This is just as a hint to AddressOf of what will be done with the
  74         // address.
  75         [Flags]
  76         public enum AddressOp {
  77                 Store = 1,
  78                 Load  = 2,
  79                 LoadStore = 3
  80         };
  81
  82         /// <summary>
  83         ///   This interface is implemented by variables
  84         /// </summary>
  85         public interface IMemoryLocation {
  86                 /// <summary>
  87                 ///   The AddressOf method should generate code that loads
  88                 ///   the address of the object and leaves it on the stack.
  89                 ///
  90                 ///   The `mode' argument is used to notify the expression
  91                 ///   of whether this will be used to read from the address or
  92                 ///   write to the address.
  93                 ///
  94                 ///   This is just a hint that can be used to provide good error
  95                 ///   reporting, and should have no other side effects.
  96                 /// </summary>
  97                 void AddressOf (EmitContext ec, AddressOp mode);
  98         }
  99
 100         // TODO: Rename to something meaningful, this is flow-analysis interface only
 101         public interface IVariable {
 102                 VariableInfo VariableInfo { get; }
 103                 bool IsFixed { get; }
 104         }
 105
 106         /// <remarks>
 107         ///   Base class for expressions
 108         /// </remarks>
 109         public abstract class Expression {
 110                 public ExprClass eclass;
 111                 protected Type type;
 112                 protected Location loc;
 113
 114                 public Type Type {
 115                         get { return type; }
 116                         set { type = value; }
 117                 }
 118
 119                 public virtual Location Location {
 120                         get { return loc; }
 121                 }
 122
 123                 /// <summary>
 124                 ///   Utility wrapper routine for Error, just to beautify the code
 125                 /// </summary>
 126                 public void Error (int error, string s)
 127                 {
 128                         Report.Error (error, loc, s);
 129                 }
 130
 131                 // Not nice but we have broken hierarchy.
 132                 public virtual void CheckMarshalByRefAccess (EmitContext ec)
 133                 {
 134                 }
 135
 136                 public virtual bool GetAttributableValue (Type value_type, out object value)
 137                 {
 138                         Attribute.Error_AttributeArgumentNotValid (loc);
 139                         value = null;
 140                         return false;
 141                 }
 142
 143                 public virtual string GetSignatureForError ()
 144                 {
 145                         return TypeManager.CSharpName (type);
 146                 }
 147
 148                 public static bool IsAccessorAccessible (Type invocation_type, MethodInfo mi, out bool must_do_cs1540_check)
 149                 {
 150                         MethodAttributes ma = mi.Attributes & MethodAttributes.MemberAccessMask;
 151
 152                         must_do_cs1540_check = false; // by default we do not check for this
 153
 154                         if (ma == MethodAttributes.Public)
 155                                 return true;
 156
 157                         //
 158                         // If only accessible to the current class or children
 159                         //
 160                         if (ma == MethodAttributes.Private)
 161                                 return TypeManager.IsPrivateAccessible (invocation_type, mi.DeclaringType) ||
 162                                         TypeManager.IsNestedChildOf (invocation_type, mi.DeclaringType);
 163
 164                         if (TypeManager.IsThisOrFriendAssembly (mi.DeclaringType.Assembly)) {
 165                                 if (ma == MethodAttributes.Assembly || ma == MethodAttributes.FamORAssem)
 166                                         return true;
 167                         } else {
 168                                 if (ma == MethodAttributes.Assembly || ma == MethodAttributes.FamANDAssem)
 169                                         return false;
 170                         }
 171
 172                         // Family and FamANDAssem require that we derive.
 173                         // FamORAssem requires that we derive if in different assemblies.
 174                         if (!TypeManager.IsNestedFamilyAccessible (invocation_type, mi.DeclaringType))
 175                                 return false;
 176
 177                         if (!TypeManager.IsNestedChildOf (invocation_type, mi.DeclaringType))
 178                                 must_do_cs1540_check = true;
 179
 180                         return true;
 181                 }
 182
 183                 public virtual bool IsNull {
 184                         get {
 185                                 return false;
 186                         }
 187                 }
 188
 189                 /// <summary>
 190                 ///   Performs semantic analysis on the Expression
 191                 /// </summary>
 192                 ///
 193                 /// <remarks>
 194                 ///   The Resolve method is invoked to perform the semantic analysis
 195                 ///   on the node.
 196                 ///
 197                 ///   The return value is an expression (it can be the
 198                 ///   same expression in some cases) or a new
 199                 ///   expression that better represents this node.
 200                 ///
 201                 ///   For example, optimizations of Unary (LiteralInt)
 202                 ///   would return a new LiteralInt with a negated
 203                 ///   value.
 204                 ///
 205                 ///   If there is an error during semantic analysis,
 206                 ///   then an error should be reported (using Report)
 207                 ///   and a null value should be returned.
 208                 ///
 209                 ///   There are two side effects expected from calling
 210                 ///   Resolve(): the the field variable "eclass" should
 211                 ///   be set to any value of the enumeration
 212                 ///   `ExprClass' and the type variable should be set
 213                 ///   to a valid type (this is the type of the
 214                 ///   expression).
 215                 /// </remarks>
 216                 public abstract Expression DoResolve (EmitContext ec);
 217
 218                 public virtual Expression DoResolveLValue (EmitContext ec, Expression right_side)
 219                 {
 220                         return null;
 221                 }
 222
 223                 //
 224                 // This is used if the expression should be resolved as a type or namespace name.
 225                 // the default implementation fails.
 226                 //
 227                 public virtual FullNamedExpression ResolveAsTypeStep (IResolveContext rc,  bool silent)
 228                 {
 229                         if (!silent) {
 230                                 Expression e = this;
 231                                 EmitContext ec = rc as EmitContext;
 232                                 if (ec != null)
 233                                         e = e.Resolve (ec);
 234                                 if (e != null)
 235                                         e.Error_UnexpectedKind (ResolveFlags.Type, loc);
 236                         }
 237                         return null;
 238                 }
 239
 240                 //
 241                 // C# 3.0 introduced contextual keywords (var) which behaves like a type if type with
 242                 // same name exists or as a keyword when no type was found
 243                 //
 244                 public virtual TypeExpr ResolveAsContextualType (IResolveContext rc, bool silent)
 245                 {
 246                         return ResolveAsTypeTerminal (rc, silent);
 247                 }
 248
 249                 //
 250                 // This is used to resolve the expression as a type, a null
 251                 // value will be returned if the expression is not a type
 252                 // reference
 253                 //
 254                 public virtual TypeExpr ResolveAsTypeTerminal (IResolveContext ec, bool silent)
 255                 {
 256                         TypeExpr te = ResolveAsBaseTerminal (ec, silent);
 257                         if (te == null)
 258                                 return null;
 259
 260                         if (!silent) { // && !(te is TypeParameterExpr)) {
 261                                 ObsoleteAttribute obsolete_attr = AttributeTester.GetObsoleteAttribute (te.Type);
 262                                 if (obsolete_attr != null && !ec.IsInObsoleteScope) {
 263                                         AttributeTester.Report_ObsoleteMessage (obsolete_attr, te.GetSignatureForError (), Location);
 264                                 }
 265                         }
 266
 267                         // Constrains don't need to be checked for overrides
 268                         GenericMethod gm = ec.GenericDeclContainer as GenericMethod;
 269                         if (gm != null && (gm.ModFlags & Modifiers.OVERRIDE) != 0) {
 270                                 te.loc = loc;
 271                                 return te;
 272                         }
 273
 274                         ConstructedType ct = te as ConstructedType;
 275                         if ((ct != null) && !ct.CheckConstraints (ec))
 276                                 return null;
 277
 278                         return te;
 279                 }
 280
 281                 public TypeExpr ResolveAsBaseTerminal (IResolveContext ec, bool silent)
 282                 {
 283                         int errors = Report.Errors;
 284
 285                         FullNamedExpression fne = ResolveAsTypeStep (ec, silent);
 286
 287                         if (fne == null)
 288                                 return null;
 289
 290                         if (fne.eclass != ExprClass.Type) {
 291                                 if (!silent && errors == Report.Errors)
 292                                         fne.Error_UnexpectedKind (null, "type", loc);
 293                                 return null;
 294                         }
 295
 296                         TypeExpr te = fne as TypeExpr;
 297
 298                         if (!te.CheckAccessLevel (ec.DeclContainer)) {
 299                                 Report.SymbolRelatedToPreviousError (te.Type);
 300                                 ErrorIsInaccesible (loc, TypeManager.CSharpName (te.Type));
 301                                 return null;
 302                         }
 303
 304                         te.loc = loc;
 305                         return te;
 306                 }
 307
 308                 public static void ErrorIsInaccesible (Location loc, string name)
 309                 {
 310                         Report.Error (122, loc, "`{0}' is inaccessible due to its protection level", name);
 311                 }
 312
 313                 protected static void Error_CannotAccessProtected (Location loc, MemberInfo m, Type qualifier, Type container)
 314                 {
 315                         Report.Error (1540, loc, "Cannot access protected member `{0}' via a qualifier of type `{1}'."
 316                                 + " The qualifier must be of type `{2}' or derived from it",
 317                                 TypeManager.GetFullNameSignature (m),
 318                                 TypeManager.CSharpName (qualifier),
 319                                 TypeManager.CSharpName (container));
 320
 321                 }
 322
 323                 public static void Error_InvalidExpressionStatement (Location loc)
 324                 {
 325                         Report.Error (201, loc, "Only assignment, call, increment, decrement, and new object " +
 326                                        "expressions can be used as a statement");
 327                 }
 328
 329                 public void Error_InvalidExpressionStatement ()
 330                 {
 331                         Error_InvalidExpressionStatement (loc);
 332                 }
 333
 334                 protected void Error_CannotAssign (string to, string roContext)
 335                 {
 336                         Report.Error (1656, loc, "Cannot assign to `{0}' because it is a `{1}'",
 337                                 to, roContext);
 338                 }
 339
 340                 public static void Error_VoidInvalidInTheContext (Location loc)
 341                 {
 342                         Report.Error (1547, loc, "Keyword `void' cannot be used in this context");
 343                 }
 344
 345                 public virtual void Error_ValueCannotBeConverted (EmitContext ec, Location loc, Type target, bool expl)
 346                 {
 347                         // The error was already reported as CS1660
 348                         if (type == TypeManager.anonymous_method_type)
 349                                 return;
 350
 351                         if (TypeManager.IsGenericParameter (Type) && TypeManager.IsGenericParameter (target) && type.Name == target.Name) {
 352 #if GMCS_SOURCE
 353                                 string sig1 = type.DeclaringMethod == null ?
 354                                         TypeManager.CSharpName (type.DeclaringType) :
 355                                         TypeManager.CSharpSignature (type.DeclaringMethod);
 356                                 string sig2 = target.DeclaringMethod == null ?
 357                                         TypeManager.CSharpName (target.DeclaringType) :
 358                                         TypeManager.CSharpSignature (target.DeclaringMethod);
 359                                 Report.ExtraInformation (loc,
 360                                         String.Format (
 361                                                 "The generic parameter `{0}' of `{1}' cannot be converted to the generic parameter `{0}' of `{2}' (in the previous ",
 362                                                 Type.Name, sig1, sig2));
 363 #endif
 364                         } else if (Type.FullName == target.FullName){
 365                                 Report.ExtraInformation (loc,
 366                                         String.Format (
 367                                         "The type `{0}' has two conflicting definitions, one comes from `{1}' and the other from `{2}' (in the previous ",
 368                                         Type.FullName, Type.Assembly.FullName, target.Assembly.FullName));
 369                         }
 370
 371                         if (expl) {
 372                                 Report.Error (30, loc, "Cannot convert type `{0}' to `{1}'",
 373                                         TypeManager.CSharpName (type), TypeManager.CSharpName (target));
 374                                 return;
 375                         }
 376
 377                         Expression e = (this is EnumConstant) ? ((EnumConstant)this).Child : this;
 378                         bool b = Convert.ExplicitNumericConversion (e, target) != null;
 379
 380                         if (b ||
 381                             Convert.ExplicitReferenceConversionExists (Type, target) ||
 382                             Convert.ExplicitUnsafe (e, target) != null ||
 383                             (ec != null && Convert.ExplicitUserConversion (ec, this, target, Location.Null) != null))
 384                         {
 385                                 Report.Error (266, loc, "Cannot implicitly convert type `{0}' to `{1}'. " +
 386                                               "An explicit conversion exists (are you missing a cast?)",
 387                                         TypeManager.CSharpName (Type), TypeManager.CSharpName (target));
 388                                 return;
 389                         }
 390
 391                         Report.Error (29, loc, "Cannot implicitly convert type `{0}' to `{1}'",
 392                                 TypeManager.CSharpName (type),
 393                                 TypeManager.CSharpName (target));
 394                 }
 395
 396                 protected void Error_VariableIsUsedBeforeItIsDeclared (string name)
 397                 {
 398                         Report.Error (841, loc, "The variable `{0}' cannot be used before it is declared",
 399                                 name);
 400                 }
 401
 402                 protected virtual void Error_TypeDoesNotContainDefinition (Type type, string name)
 403                 {
 404                         Error_TypeDoesNotContainDefinition (loc, type, name);
 405                 }
 406
 407                 public static void Error_TypeDoesNotContainDefinition (Location loc, Type type, string name)
 408                 {
 409                         Report.SymbolRelatedToPreviousError (type);
 410                         Report.Error (117, loc, "`{0}' does not contain a definition for `{1}'",
 411                                 TypeManager.CSharpName (type), name);
 412                 }
 413
 414                 protected static void Error_ValueAssignment (Location loc)
 415                 {
 416                         Report.Error (131, loc, "The left-hand side of an assignment must be a variable, a property or an indexer");
 417                 }
 418
 419                 ResolveFlags ExprClassToResolveFlags
 420                 {
 421                         get {
 422                                 switch (eclass) {
 423                                         case ExprClass.Type:
 424                                         case ExprClass.Namespace:
 425                                                 return ResolveFlags.Type;
 426
 427                                         case ExprClass.MethodGroup:
 428                                                 return ResolveFlags.MethodGroup;
 429
 430                                         case ExprClass.Value:
 431                                         case ExprClass.Variable:
 432                                         case ExprClass.PropertyAccess:
 433                                         case ExprClass.EventAccess:
 434                                         case ExprClass.IndexerAccess:
 435                                                 return ResolveFlags.VariableOrValue;
 436
 437                                         default:
 438                                                 throw new InternalErrorException (loc.ToString () + " " +  GetType () + " ExprClass is Invalid after resolve");
 439                                 }
 440                         }
 441                 }
 442
 443                 /// <summary>
 444                 ///   Resolves an expression and performs semantic analysis on it.
 445                 /// </summary>
 446                 ///
 447                 /// <remarks>
 448                 ///   Currently Resolve wraps DoResolve to perform sanity
 449                 ///   checking and assertion checking on what we expect from Resolve.
 450                 /// </remarks>
 451                 public Expression Resolve (EmitContext ec, ResolveFlags flags)
 452                 {
 453                         if ((flags & ResolveFlags.MaskExprClass) == ResolveFlags.Type)
 454                                 return ResolveAsTypeStep (ec, false);
 455
 456                         bool do_flow_analysis = ec.DoFlowAnalysis;
 457                         bool omit_struct_analysis = ec.OmitStructFlowAnalysis;
 458                         if ((flags & ResolveFlags.DisableFlowAnalysis) != 0)
 459                                 do_flow_analysis = false;
 460                         if ((flags & ResolveFlags.DisableStructFlowAnalysis) != 0)
 461                                 omit_struct_analysis = true;
 462
 463                         Expression e;
 464                         using (ec.WithFlowAnalysis (do_flow_analysis, omit_struct_analysis)) {
 465                                 if (this is SimpleName) {
 466                                         bool intermediate = (flags & ResolveFlags.Intermediate) == ResolveFlags.Intermediate;
 467                                         e = ((SimpleName) this).DoResolve (ec, intermediate);
 468                                 } else {
 469                                         e = DoResolve (ec);
 470                                 }
 471                         }
 472
 473                         if (e == null)
 474                                 return null;
 475
 476                         if ((flags & e.ExprClassToResolveFlags) == 0) {
 477                                 e.Error_UnexpectedKind (flags, loc);
 478                                 return null;
 479                         }
 480
 481                         if (e.type == null && !(e is Namespace)) {
 482                                 throw new Exception (
 483                                         "Expression " + e.GetType () +
 484                                         " did not set its type after Resolve\n" +
 485                                         "called from: " + this.GetType ());
 486                         }
 487
 488                         return e;
 489                 }
 490
 491                 /// <summary>
 492                 ///   Resolves an expression and performs semantic analysis on it.
 493                 /// </summary>
 494                 public Expression Resolve (EmitContext ec)
 495                 {
 496                         Expression e = Resolve (ec, ResolveFlags.VariableOrValue | ResolveFlags.MethodGroup);
 497
 498                         if (e != null && e.eclass == ExprClass.MethodGroup && RootContext.Version == LanguageVersion.ISO_1) {
 499                                 ((MethodGroupExpr) e).ReportUsageError ();
 500                                 return null;
 501                         }
 502                         return e;
 503                 }
 504
 505                 public Constant ResolveAsConstant (EmitContext ec, MemberCore mc)
 506                 {
 507                         Expression e = Resolve (ec);
 508                         if (e == null)
 509                                 return null;
 510
 511                         Constant c = e as Constant;
 512                         if (c != null)
 513                                 return c;
 514
 515                         Const.Error_ExpressionMustBeConstant (loc, mc.GetSignatureForError ());
 516                         return null;
 517                 }
 518
 519                 /// <summary>
 520                 ///   Resolves an expression for LValue assignment
 521                 /// </summary>
 522                 ///
 523                 /// <remarks>
 524                 ///   Currently ResolveLValue wraps DoResolveLValue to perform sanity
 525                 ///   checking and assertion checking on what we expect from Resolve
 526                 /// </remarks>
 527                 public Expression ResolveLValue (EmitContext ec, Expression right_side, Location loc)
 528                 {
 529                         int errors = Report.Errors;
 530                         bool out_access = right_side == EmptyExpression.OutAccess;
 531
 532                         Expression e = DoResolveLValue (ec, right_side);
 533
 534                         if (e != null && out_access && !(e is IMemoryLocation)) {
 535                                 // FIXME: There's no problem with correctness, the 'Expr = null' handles that.
 536                                 //        Enabling this 'throw' will "only" result in deleting useless code elsewhere,
 537
 538                                 //throw new InternalErrorException ("ResolveLValue didn't return an IMemoryLocation: " +
 539                                 //                                e.GetType () + " " + e.GetSignatureForError ());
 540                                 e = null;
 541                         }
 542
 543                         if (e == null) {
 544                                 if (errors == Report.Errors) {
 545                                         if (out_access)
 546                                                 Report.Error (1510, loc, "A ref or out argument must be an assignable variable");
 547                                         else
 548                                                 Error_ValueAssignment (loc);
 549                                 }
 550                                 return null;
 551                         }
 552
 553                         if (e.eclass == ExprClass.Invalid)
 554                                 throw new Exception ("Expression " + e + " ExprClass is Invalid after resolve");
 555
 556                         if (e.eclass == ExprClass.MethodGroup) {
 557                                 ((MethodGroupExpr) e).ReportUsageError ();
 558                                 return null;
 559                         }
 560
 561                         if ((e.type == null) && !(e is ConstructedType))
 562                                 throw new Exception ("Expression " + e + " did not set its type after Resolve");
 563
 564                         return e;
 565                 }
 566
 567                 /// <summary>
 568                 ///   Emits the code for the expression
 569                 /// </summary>
 570                 ///
 571                 /// <remarks>
 572                 ///   The Emit method is invoked to generate the code
 573                 ///   for the expression.
 574                 /// </remarks>
 575                 public abstract void Emit (EmitContext ec);
 576
 577                 // Emit code to branch to @target if this expression is equivalent to @on_true.
 578                 // The default implementation is to emit the value, and then emit a brtrue or brfalse.
 579                 // Subclasses can provide more efficient implementations, but those MUST be equivalent,
 580                 // including the use of conditional branches.  Note also that a branch MUST be emitted
 581                 public virtual void EmitBranchable (EmitContext ec, Label target, bool on_true)
 582                 {
 583                         Emit (ec);
 584                         ec.ig.Emit (on_true ? OpCodes.Brtrue : OpCodes.Brfalse, target);
 585                 }
 586
 587                 // Emit this expression for its side effects, not for its value.
 588                 // The default implementation is to emit the value, and then throw it away.
 589                 // Subclasses can provide more efficient implementations, but those MUST be equivalent
 590                 public virtual void EmitSideEffect (EmitContext ec)
 591                 {
 592                         Emit (ec);
 593                         ec.ig.Emit (OpCodes.Pop);
 594                 }
 595
 596                 /// <summary>
 597                 ///   Protected constructor.  Only derivate types should
 598                 ///   be able to be created
 599                 /// </summary>
 600
 601                 protected Expression ()
 602                 {
 603                         eclass = ExprClass.Invalid;
 604                         type = null;
 605                 }
 606
 607                 /// <summary>
 608                 ///   Returns a fully formed expression after a MemberLookup
 609                 /// </summary>
 610                 ///
 611                 public static Expression ExprClassFromMemberInfo (Type container_type, MemberInfo mi, Location loc)
 612                 {
 613                         if (mi is EventInfo)
 614                                 return new EventExpr ((EventInfo) mi, loc);
 615                         else if (mi is FieldInfo) {
 616                                 FieldInfo fi = (FieldInfo) mi;
 617                                 if (fi.IsLiteral || (fi.IsInitOnly && fi.FieldType == TypeManager.decimal_type))
 618                                         return new ConstantExpr (fi, loc);
 619                                 return new FieldExpr (fi, loc);
 620                         } else if (mi is PropertyInfo)
 621                                 return new PropertyExpr (container_type, (PropertyInfo) mi, loc);
 622                         else if (mi is Type) {
 623                                 return new TypeExpression ((System.Type) mi, loc);
 624                         }
 625
 626                         return null;
 627                 }
 628
 629                 protected static ArrayList almost_matched_members = new ArrayList (4);
 630
 631                 //
 632                 // FIXME: Probably implement a cache for (t,name,current_access_set)?
 633                 //
 634                 // This code could use some optimizations, but we need to do some
 635                 // measurements.  For example, we could use a delegate to `flag' when
 636                 // something can not any longer be a method-group (because it is something
 637                 // else).
 638                 //
 639                 // Return values:
 640                 //     If the return value is an Array, then it is an array of
 641                 //     MethodBases
 642                 //
 643                 //     If the return value is an MemberInfo, it is anything, but a Method
 644                 //
 645                 //     null on error.
 646                 //
 647                 // FIXME: When calling MemberLookup inside an `Invocation', we should pass
 648                 // the arguments here and have MemberLookup return only the methods that
 649                 // match the argument count/type, unlike we are doing now (we delay this
 650                 // decision).
 651                 //
 652                 // This is so we can catch correctly attempts to invoke instance methods
 653                 // from a static body (scan for error 120 in ResolveSimpleName).
 654                 //
 655                 //
 656                 // FIXME: Potential optimization, have a static ArrayList
 657                 //
 658
 659                 public static Expression MemberLookup (Type container_type, Type queried_type, string name,
 660                                                        MemberTypes mt, BindingFlags bf, Location loc)
 661                 {
 662                         return MemberLookup (container_type, null, queried_type, name, mt, bf, loc);
 663                 }
 664
 665                 //
 666                 // Lookup type `queried_type' for code in class `container_type' with a qualifier of
 667                 // `qualifier_type' or null to lookup members in the current class.
 668                 //
 669
 670                 public static Expression MemberLookup (Type container_type,
 671                                                        Type qualifier_type, Type queried_type,
 672                                                        string name, MemberTypes mt,
 673                                                        BindingFlags bf, Location loc)
 674                 {
 675                         almost_matched_members.Clear ();
 676
 677                         MemberInfo [] mi = TypeManager.MemberLookup (container_type, qualifier_type,
 678                                                                      queried_type, mt, bf, name, almost_matched_members);
 679
 680                         if (mi == null)
 681                                 return null;
 682
 683                         if (mi.Length > 1) {
 684                                 bool is_interface = qualifier_type != null && qualifier_type.IsInterface;
 685                                 ArrayList methods = new ArrayList (2);
 686                                 ArrayList non_methods = null;
 687
 688                                 foreach (MemberInfo m in mi) {
 689                                         if (m is MethodBase) {
 690                                                 methods.Add (m);
 691                                                 continue;
 692                                         }
 693
 694                                         if (non_methods == null) {
 695                                                 non_methods = new ArrayList (2);
 696                                                 non_methods.Add (m);
 697                                                 continue;
 698                                         }
 699
 700                                         foreach (MemberInfo n_m in non_methods) {
 701                                                 if (m.DeclaringType.IsInterface && TypeManager.ImplementsInterface (m.DeclaringType, n_m.DeclaringType))
 702                                                         continue;
 703
 704                                                 Report.SymbolRelatedToPreviousError (m);
 705                                                 Report.Error (229, loc, "Ambiguity between `{0}' and `{1}'",
 706                                                         TypeManager.GetFullNameSignature (m), TypeManager.GetFullNameSignature (n_m));
 707                                                 return null;
 708                                         }
 709                                 }
 710
 711                                 if (methods.Count == 0)
 712                                         return ExprClassFromMemberInfo (container_type, (MemberInfo)non_methods [0], loc);
 713
 714                                 if (non_methods != null) {
 715                                         MethodBase method = (MethodBase) methods [0];
 716                                         MemberInfo non_method = (MemberInfo) non_methods [0];
 717                                         if (method.DeclaringType == non_method.DeclaringType) {
 718                                                 // Cannot happen with C# code, but is valid in IL
 719                                                 Report.SymbolRelatedToPreviousError (method);
 720                                                 Report.SymbolRelatedToPreviousError (non_method);
 721                                                 Report.Error (229, loc, "Ambiguity between `{0}' and `{1}'",
 722                                                               TypeManager.GetFullNameSignature (non_method),
 723                                                               TypeManager.CSharpSignature (method));
 724                                                 return null;
 725                                         }
 726
 727                                         if (is_interface) {
 728                                                 Report.SymbolRelatedToPreviousError (method);
 729                                                 Report.SymbolRelatedToPreviousError (non_method);
 730                                                 Report.Warning (467, 2, loc, "Ambiguity between method `{0}' and non-method `{1}'. Using method `{0}'",
 731                                                                 TypeManager.CSharpSignature (method), TypeManager.GetFullNameSignature (non_method));
 732                                         }
 733                                 }
 734
 735                                 return new MethodGroupExpr (methods, queried_type, loc);
 736                         }
 737
 738                         if (mi [0] is MethodBase)
 739                                 return new MethodGroupExpr (mi, queried_type, loc);
 740
 741                         return ExprClassFromMemberInfo (container_type, mi [0], loc);
 742                 }
 743
 744                 public const MemberTypes AllMemberTypes =
 745                         MemberTypes.Constructor |
 746                         MemberTypes.Event       |
 747                         MemberTypes.Field       |
 748                         MemberTypes.Method      |
 749                         MemberTypes.NestedType  |
 750                         MemberTypes.Property;
 751
 752                 public const BindingFlags AllBindingFlags =
 753                         BindingFlags.Public |
 754                         BindingFlags.Static |
 755                         BindingFlags.Instance;
 756
 757                 public static Expression MemberLookup (Type container_type, Type queried_type,
 758                                                        string name, Location loc)
 759                 {
 760                         return MemberLookup (container_type, null, queried_type, name,
 761                                              AllMemberTypes, AllBindingFlags, loc);
 762                 }
 763
 764                 public static Expression MemberLookup (Type container_type, Type qualifier_type,
 765                                                        Type queried_type, string name, Location loc)
 766                 {
 767                         return MemberLookup (container_type, qualifier_type, queried_type,
 768                                              name, AllMemberTypes, AllBindingFlags, loc);
 769                 }
 770
 771                 public static MethodGroupExpr MethodLookup (Type container_type, Type queried_type,
 772                                                        string name, Location loc)
 773                 {
 774                         return (MethodGroupExpr)MemberLookup (container_type, null, queried_type, name,
 775                                              MemberTypes.Method, AllBindingFlags, loc);
 776                 }
 777
 778                 /// <summary>
 779                 ///   This is a wrapper for MemberLookup that is not used to "probe", but
 780                 ///   to find a final definition.  If the final definition is not found, we
 781                 ///   look for private members and display a useful debugging message if we
 782                 ///   find it.
 783                 /// </summary>
 784                 protected Expression MemberLookupFinal (EmitContext ec, Type qualifier_type,
 785                                                             Type queried_type, string name,
 786                                                             MemberTypes mt, BindingFlags bf,
 787                                                             Location loc)
 788                 {
 789                         Expression e;
 790
 791                         int errors = Report.Errors;
 792
 793                         e = MemberLookup (ec.ContainerType, qualifier_type, queried_type, name, mt, bf, loc);
 794
 795                         if (e != null || errors != Report.Errors)
 796                                 return e;
 797
 798                         // No errors were reported by MemberLookup, but there was an error.
 799                         return Error_MemberLookupFailed (ec.ContainerType, qualifier_type, queried_type,
 800                                         name, null, mt, bf);
 801                 }
 802
 803                 protected virtual Expression Error_MemberLookupFailed (Type container_type, Type qualifier_type,
 804                                                        Type queried_type, string name, string class_name,
 805                                                            MemberTypes mt, BindingFlags bf)
 806                 {
 807                         if (almost_matched_members.Count != 0) {
 808                                 for (int i = 0; i < almost_matched_members.Count; ++i) {
 809                                         MemberInfo m = (MemberInfo) almost_matched_members [i];
 810                                         for (int j = 0; j < i; ++j) {
 811                                                 if (m == almost_matched_members [j]) {
 812                                                         m = null;
 813                                                         break;
 814                                                 }
 815                                         }
 816                                         if (m == null)
 817                                                 continue;
 818
 819                                         Type declaring_type = m.DeclaringType;
 820
 821                                         Report.SymbolRelatedToPreviousError (m);
 822                                         if (qualifier_type == null) {
 823                                                 Report.Error (38, loc, "Cannot access a nonstatic member of outer type `{0}' via nested type `{1}'",
 824                                                               TypeManager.CSharpName (m.DeclaringType),
 825                                                               TypeManager.CSharpName (container_type));
 826
 827                                         } else if (qualifier_type != container_type &&
 828                                                    TypeManager.IsNestedFamilyAccessible (container_type, declaring_type)) {
 829                                                 // Although a derived class can access protected members of
 830                                                 // its base class it cannot do so through an instance of the
 831                                                 // base class (CS1540).  If the qualifier_type is a base of the
 832                                                 // ec.ContainerType and the lookup succeeds with the latter one,
 833                                                 // then we are in this situation.
 834                                                 Error_CannotAccessProtected (loc, m, qualifier_type, container_type);
 835                                         } else {
 836                                                 ErrorIsInaccesible (loc, TypeManager.GetFullNameSignature (m));
 837                                         }
 838                                 }
 839                                 almost_matched_members.Clear ();
 840                                 return null;
 841                         }
 842
 843                         MemberInfo[] lookup = null;
 844                         if (queried_type == null) {
 845                                 class_name = "global::";
 846                         } else {
 847                                 lookup = TypeManager.MemberLookup (queried_type, null, queried_type,
 848                                         mt, (bf & ~BindingFlags.Public) | BindingFlags.NonPublic,
 849                                         name, null);
 850
 851                                 if (lookup != null) {
 852                                         Report.SymbolRelatedToPreviousError (lookup [0]);
 853                                         ErrorIsInaccesible (loc, TypeManager.GetFullNameSignature (lookup [0]));
 854                                         return Error_MemberLookupFailed (lookup);
 855                                 }
 856
 857                                 lookup = TypeManager.MemberLookup (queried_type, null, queried_type,
 858                                         AllMemberTypes, AllBindingFlags | BindingFlags.NonPublic,
 859                                         name, null);
 860                         }
 861
 862                         if (lookup == null) {
 863                                 if (class_name != null) {
 864                                         Report.Error (103, loc, "The name `{0}' does not exist in the current context",
 865                                                 name);
 866                                 } else {
 867                                         Error_TypeDoesNotContainDefinition (queried_type, name);
 868                                 }
 869                                 return null;
 870                         }
 871
 872                         if (TypeManager.MemberLookup (queried_type, null, queried_type,
 873                                                       AllMemberTypes, AllBindingFlags |
 874                                                       BindingFlags.NonPublic, name, null) == null) {
 875                                 if ((lookup.Length == 1) && (lookup [0] is Type)) {
 876                                         Type t = (Type) lookup [0];
 877
 878                                         Report.Error (305, loc,
 879                                                       "Using the generic type `{0}' " +
 880                                                       "requires {1} type arguments",
 881                                                       TypeManager.CSharpName (t),
 882                                                       TypeManager.GetNumberOfTypeArguments (t).ToString ());
 883                                         return null;
 884                                 }
 885                         }
 886
 887                         return Error_MemberLookupFailed (lookup);
 888                 }
 889
 890                 protected virtual Expression Error_MemberLookupFailed (MemberInfo[] members)
 891                 {
 892                         for (int i = 0; i < members.Length; ++i) {
 893                                 if (!(members [i] is MethodBase))
 894                                         return null;
 895                         }
 896
 897                         // By default propagate the closest candidates upwards
 898                         return new MethodGroupExpr (members, type, loc);
 899                 }
 900
 901                 protected virtual void Error_NegativeArrayIndex (Location loc)
 902                 {
 903                         throw new NotImplementedException ();
 904                 }
 905
 906                 protected void Error_PointerInsideExpressionTree ()
 907                 {
 908                         Report.Error (1944, loc, "An expression tree cannot contain an unsafe pointer operation");
 909                 }
 910
 911                 /// <summary>
 912                 ///   Returns an expression that can be used to invoke operator true
 913                 ///   on the expression if it exists.
 914                 /// </summary>
 915                 static public Expression GetOperatorTrue (EmitContext ec, Expression e, Location loc)
 916                 {
 917                         return GetOperatorTrueOrFalse (ec, e, true, loc);
 918                 }
 919
 920                 /// <summary>
 921                 ///   Returns an expression that can be used to invoke operator false
 922                 ///   on the expression if it exists.
 923                 /// </summary>
 924                 static public Expression GetOperatorFalse (EmitContext ec, Expression e, Location loc)
 925                 {
 926                         return GetOperatorTrueOrFalse (ec, e, false, loc);
 927                 }
 928
 929                 static Expression GetOperatorTrueOrFalse (EmitContext ec, Expression e, bool is_true, Location loc)
 930                 {
 931                         MethodGroupExpr operator_group;
 932                         string mname = Operator.GetMetadataName (is_true ? Operator.OpType.True : Operator.OpType.False);
 933                         operator_group = MethodLookup (ec.ContainerType, e.Type, mname, loc) as MethodGroupExpr;
 934                         if (operator_group == null)
 935                                 return null;
 936
 937                         ArrayList arguments = new ArrayList (1);
 938                         arguments.Add (new Argument (e, Argument.AType.Expression));
 939                         operator_group = operator_group.OverloadResolve (
 940                                 ec, ref arguments, false, loc);
 941
 942                         if (operator_group == null)
 943                                 return null;
 944
 945                         return new UserOperatorCall (operator_group, arguments, null, loc);
 946                 }
 947
 948                 /// <summary>
 949                 ///   Resolves the expression `e' into a boolean expression: either through
 950                 ///   an implicit conversion, or through an `operator true' invocation
 951                 /// </summary>
 952                 public static Expression ResolveBoolean (EmitContext ec, Expression e, Location loc)
 953                 {
 954                         e = e.Resolve (ec);
 955                         if (e == null)
 956                                 return null;
 957
 958                         if (e.Type == TypeManager.bool_type)
 959                                 return e;
 960
 961                         Expression converted = Convert.ImplicitConversion (ec, e, TypeManager.bool_type, Location.Null);
 962
 963                         if (converted != null)
 964                                 return converted;
 965
 966                         //
 967                         // If no implicit conversion to bool exists, try using `operator true'
 968                         //
 969                         converted = Expression.GetOperatorTrue (ec, e, loc);
 970                         if (converted == null){
 971                                 e.Error_ValueCannotBeConverted (ec, loc, TypeManager.bool_type, false);
 972                                 return null;
 973                         }
 974                         return converted;
 975                 }
 976
 977                 public virtual string ExprClassName
 978                 {
 979                         get {
 980                                 switch (eclass){
 981                                         case ExprClass.Invalid:
 982                                                 return "Invalid";
 983                                         case ExprClass.Value:
 984                                                 return "value";
 985                                         case ExprClass.Variable:
 986                                                 return "variable";
 987                                         case ExprClass.Namespace:
 988                                                 return "namespace";
 989                                         case ExprClass.Type:
 990                                                 return "type";
 991                                         case ExprClass.MethodGroup:
 992                                                 return "method group";
 993                                         case ExprClass.PropertyAccess:
 994                                                 return "property access";
 995                                         case ExprClass.EventAccess:
 996                                                 return "event access";
 997                                         case ExprClass.IndexerAccess:
 998                                                 return "indexer access";
 999                                         case ExprClass.Nothing:
1000                                                 return "null";
1001                                 }
1002                                 throw new Exception ("Should not happen");
1003                         }
1004                 }
1005
1006                 /// <summary>
1007                 ///   Reports that we were expecting `expr' to be of class `expected'
1008                 /// </summary>
1009                 public void Error_UnexpectedKind (DeclSpace ds, string expected, Location loc)
1010                 {
1011                         Error_UnexpectedKind (ds, expected, ExprClassName, loc);
1012                 }
1013
1014                 public void Error_UnexpectedKind (DeclSpace ds, string expected, string was, Location loc)
1015                 {
1016                         string name = GetSignatureForError ();
1017                         if (ds != null)
1018                                 name = ds.GetSignatureForError () + '.' + name;
1019
1020                         Report.Error (118, loc, "`{0}' is a `{1}' but a `{2}' was expected",
1021                               name, was, expected);
1022                 }
1023
1024                 public void Error_UnexpectedKind (ResolveFlags flags, Location loc)
1025                 {
1026                         string [] valid = new string [4];
1027                         int count = 0;
1028
1029                         if ((flags & ResolveFlags.VariableOrValue) != 0) {
1030                                 valid [count++] = "variable";
1031                                 valid [count++] = "value";
1032                         }
1033
1034                         if ((flags & ResolveFlags.Type) != 0)
1035                                 valid [count++] = "type";
1036
1037                         if ((flags & ResolveFlags.MethodGroup) != 0)
1038                                 valid [count++] = "method group";
1039
1040                         if (count == 0)
1041                                 valid [count++] = "unknown";
1042
1043                         StringBuilder sb = new StringBuilder (valid [0]);
1044                         for (int i = 1; i < count - 1; i++) {
1045                                 sb.Append ("', `");
1046                                 sb.Append (valid [i]);
1047                         }
1048                         if (count > 1) {
1049                                 sb.Append ("' or `");
1050                                 sb.Append (valid [count - 1]);
1051                         }
1052
1053                         Report.Error (119, loc,
1054                                 "Expression denotes a `{0}', where a `{1}' was expected", ExprClassName, sb.ToString ());
1055                 }
1056
1057                 public static void UnsafeError (Location loc)
1058                 {
1059                         Report.Error (214, loc, "Pointers and fixed size buffers may only be used in an unsafe context");
1060                 }
1061
1062                 //
1063                 // Load the object from the pointer.
1064                 //
1065                 public static void LoadFromPtr (ILGenerator ig, Type t)
1066                 {
1067                         if (t == TypeManager.int32_type)
1068                                 ig.Emit (OpCodes.Ldind_I4);
1069                         else if (t == TypeManager.uint32_type)
1070                                 ig.Emit (OpCodes.Ldind_U4);
1071                         else if (t == TypeManager.short_type)
1072                                 ig.Emit (OpCodes.Ldind_I2);
1073                         else if (t == TypeManager.ushort_type)
1074                                 ig.Emit (OpCodes.Ldind_U2);
1075                         else if (t == TypeManager.char_type)
1076                                 ig.Emit (OpCodes.Ldind_U2);
1077                         else if (t == TypeManager.byte_type)
1078                                 ig.Emit (OpCodes.Ldind_U1);
1079                         else if (t == TypeManager.sbyte_type)
1080                                 ig.Emit (OpCodes.Ldind_I1);
1081                         else if (t == TypeManager.uint64_type)
1082                                 ig.Emit (OpCodes.Ldind_I8);
1083                         else if (t == TypeManager.int64_type)
1084                                 ig.Emit (OpCodes.Ldind_I8);
1085                         else if (t == TypeManager.float_type)
1086                                 ig.Emit (OpCodes.Ldind_R4);
1087                         else if (t == TypeManager.double_type)
1088                                 ig.Emit (OpCodes.Ldind_R8);
1089                         else if (t == TypeManager.bool_type)
1090                                 ig.Emit (OpCodes.Ldind_I1);
1091                         else if (t == TypeManager.intptr_type)
1092                                 ig.Emit (OpCodes.Ldind_I);
1093                         else if (TypeManager.IsEnumType (t)) {
1094                                 if (t == TypeManager.enum_type)
1095                                         ig.Emit (OpCodes.Ldind_Ref);
1096                                 else
1097                                         LoadFromPtr (ig, TypeManager.GetEnumUnderlyingType (t));
1098                         } else if (t.IsValueType || TypeManager.IsGenericParameter (t))
1099                                 ig.Emit (OpCodes.Ldobj, t);
1100                         else if (t.IsPointer)
1101                                 ig.Emit (OpCodes.Ldind_I);
1102                         else
1103                                 ig.Emit (OpCodes.Ldind_Ref);
1104                 }
1105
1106                 //
1107                 // The stack contains the pointer and the value of type `type'
1108                 //
1109                 public static void StoreFromPtr (ILGenerator ig, Type type)
1110                 {
1111                         if (TypeManager.IsEnumType (type))
1112                                 type = TypeManager.GetEnumUnderlyingType (type);
1113                         if (type == TypeManager.int32_type || type == TypeManager.uint32_type)
1114                                 ig.Emit (OpCodes.Stind_I4);
1115                         else if (type == TypeManager.int64_type || type == TypeManager.uint64_type)
1116                                 ig.Emit (OpCodes.Stind_I8);
1117                         else if (type == TypeManager.char_type || type == TypeManager.short_type ||
1118                                  type == TypeManager.ushort_type)
1119                                 ig.Emit (OpCodes.Stind_I2);
1120                         else if (type == TypeManager.float_type)
1121                                 ig.Emit (OpCodes.Stind_R4);
1122                         else if (type == TypeManager.double_type)
1123                                 ig.Emit (OpCodes.Stind_R8);
1124                         else if (type == TypeManager.byte_type || type == TypeManager.sbyte_type ||
1125                                  type == TypeManager.bool_type)
1126                                 ig.Emit (OpCodes.Stind_I1);
1127                         else if (type == TypeManager.intptr_type)
1128                                 ig.Emit (OpCodes.Stind_I);
1129                         else if (type.IsValueType || TypeManager.IsGenericParameter (type))
1130                                 ig.Emit (OpCodes.Stobj, type);
1131                         else
1132                                 ig.Emit (OpCodes.Stind_Ref);
1133                 }
1134
1135                 //
1136                 // Returns the size of type `t' if known, otherwise, 0
1137                 //
1138                 public static int GetTypeSize (Type t)
1139                 {
1140                         t = TypeManager.TypeToCoreType (t);
1141                         if (t == TypeManager.int32_type ||
1142                             t == TypeManager.uint32_type ||
1143                             t == TypeManager.float_type)
1144                                 return 4;
1145                         else if (t == TypeManager.int64_type ||
1146                                  t == TypeManager.uint64_type ||
1147                                  t == TypeManager.double_type)
1148                                 return 8;
1149                         else if (t == TypeManager.byte_type ||
1150                                  t == TypeManager.sbyte_type ||
1151                                  t == TypeManager.bool_type)
1152                                 return 1;
1153                         else if (t == TypeManager.short_type ||
1154                                  t == TypeManager.char_type ||
1155                                  t == TypeManager.ushort_type)
1156                                 return 2;
1157                         else if (t == TypeManager.decimal_type)
1158                                 return 16;
1159                         else
1160                                 return 0;
1161                 }
1162
1163                 protected void Error_CannotCallAbstractBase (string name)
1164                 {
1165                         Report.Error (205, loc, "Cannot call an abstract base member `{0}'", name);
1166                 }
1167
1168                 protected void Error_CannotModifyIntermediateExpressionValue (EmitContext ec)
1169                 {
1170                         Report.SymbolRelatedToPreviousError (type);
1171                         if (ec.CurrentInitializerVariable != null) {
1172                                 Report.Error (1918, loc, "Members of a value type property `{0}' cannot be assigned with an object initializer",
1173                                         GetSignatureForError ());
1174                         } else {
1175                                 Report.Error (1612, loc, "Cannot modify a value type return value of `{0}'. Consider storing the value in a temporary variable",
1176                                         GetSignatureForError ());
1177                         }
1178                 }
1179
1180                 //
1181                 // Converts `source' to an int, uint, long or ulong.
1182                 //
1183                 public Expression ConvertExpressionToArrayIndex (EmitContext ec, Expression source)
1184                 {
1185                         Expression converted;
1186
1187                         using (ec.With (EmitContext.Flags.CheckState, true)) {
1188                                 converted = Convert.ImplicitConversion (ec, source, TypeManager.int32_type, source.loc);
1189                                 if (converted == null)
1190                                         converted = Convert.ImplicitConversion (ec, source, TypeManager.uint32_type, source.loc);
1191                                 if (converted == null)
1192                                         converted = Convert.ImplicitConversion (ec, source, TypeManager.int64_type, source.loc);
1193                                 if (converted == null)
1194                                         converted = Convert.ImplicitConversion (ec, source, TypeManager.uint64_type, source.loc);
1195
1196                                 if (converted == null) {
1197                                         source.Error_ValueCannotBeConverted (ec, source.loc, TypeManager.int32_type, false);
1198                                         return null;
1199                                 }
1200                         }
1201
1202                         //
1203                         // Only positive constants are allowed at compile time
1204                         //
1205                         Constant c = converted as Constant;
1206                         if (c != null) {
1207                                 if (c.IsNegative) {
1208                                         Error_NegativeArrayIndex (source.loc);
1209                                 }
1210                                 return c;
1211                         }
1212
1213                         return new ArrayIndexCast (converted).Resolve (ec);
1214                 }
1215
1216                 //
1217                 // Derived classes implement this method by cloning the fields that
1218                 // could become altered during the Resolve stage
1219                 //
1220                 // Only expressions that are created for the parser need to implement
1221                 // this.
1222                 //
1223                 protected virtual void CloneTo (CloneContext clonectx, Expression target)
1224                 {
1225                         throw new NotImplementedException (
1226                                 String.Format (
1227                                         "CloneTo not implemented for expression {0}", this.GetType ()));
1228                 }
1229
1230                 //
1231                 // Clones an expression created by the parser.
1232                 //
1233                 // We only support expressions created by the parser so far, not
1234                 // expressions that have been resolved (many more classes would need
1235                 // to implement CloneTo).
1236                 //
1237                 // This infrastructure is here merely for Lambda expressions which
1238                 // compile the same code using different type values for the same
1239                 // arguments to find the correct overload
1240                 //
1241                 public Expression Clone (CloneContext clonectx)
1242                 {
1243                         Expression cloned = (Expression) MemberwiseClone ();
1244                         CloneTo (clonectx, cloned);
1245
1246                         return cloned;
1247                 }
1248
1249                 //
1250                 // Implementation of expression to expression tree conversion
1251                 //
1252                 public abstract Expression CreateExpressionTree (EmitContext ec);
1253
1254                 protected Expression CreateExpressionFactoryCall (string name, ArrayList args)
1255                 {
1256                         return CreateExpressionFactoryCall (name, null, args, loc);
1257                 }
1258
1259                 protected Expression CreateExpressionFactoryCall (string name, TypeArguments typeArguments, ArrayList args)
1260                 {
1261                         return CreateExpressionFactoryCall (name, typeArguments, args, loc);
1262                 }
1263
1264                 public static Expression CreateExpressionFactoryCall (string name, TypeArguments typeArguments, ArrayList args, Location loc)
1265                 {
1266                         return new Invocation (new MemberAccess (CreateExpressionTypeExpression (loc), name, typeArguments, loc), args);
1267                 }
1268
1269                 protected static TypeExpr CreateExpressionTypeExpression (Location loc)
1270                 {
1271                         TypeExpr texpr = TypeManager.expression_type_expr;
1272                         if (texpr == null) {
1273                                 Type t = TypeManager.CoreLookupType ("System.Linq.Expressions", "Expression", Kind.Class, true);
1274                                 if (t == null)
1275                                         return null;
1276
1277                                 TypeManager.expression_type_expr = texpr = new TypeExpression (t, Location.Null);
1278                         }
1279
1280                         return texpr;
1281                 }
1282
1283                 public virtual void MutateHoistedGenericType (AnonymousMethodStorey storey)
1284                 {
1285                         // TODO: It should probably be type = storey.MutateType (type);
1286                 }
1287         }
1288
1289         /// <summary>
1290         ///   This is just a base class for expressions that can
1291         ///   appear on statements (invocations, object creation,
1292         ///   assignments, post/pre increment and decrement).  The idea
1293         ///   being that they would support an extra Emition interface that
1294         ///   does not leave a result on the stack.
1295         /// </summary>
1296         public abstract class ExpressionStatement : Expression {
1297
1298                 public virtual ExpressionStatement ResolveStatement (EmitContext ec)
1299                 {
1300                         Expression e = Resolve (ec);
1301                         if (e == null)
1302                                 return null;
1303
1304                         ExpressionStatement es = e as ExpressionStatement;
1305                         if (es == null)
1306                                 Error_InvalidExpressionStatement ();
1307
1308                         return es;
1309                 }
1310
1311                 /// <summary>
1312                 ///   Requests the expression to be emitted in a `statement'
1313                 ///   context.  This means that no new value is left on the
1314                 ///   stack after invoking this method (constrasted with
1315                 ///   Emit that will always leave a value on the stack).
1316                 /// </summary>
1317                 public abstract void EmitStatement (EmitContext ec);
1318
1319                 public override void EmitSideEffect (EmitContext ec)
1320                 {
1321                         EmitStatement (ec);
1322                 }
1323         }
1324
1325         /// <summary>
1326         ///   This kind of cast is used to encapsulate the child
1327         ///   whose type is child.Type into an expression that is
1328         ///   reported to return "return_type".  This is used to encapsulate
1329         ///   expressions which have compatible types, but need to be dealt
1330         ///   at higher levels with.
1331         ///
1332         ///   For example, a "byte" expression could be encapsulated in one
1333         ///   of these as an "unsigned int".  The type for the expression
1334         ///   would be "unsigned int".
1335         ///
1336         /// </summary>
1337         public abstract class TypeCast : Expression
1338         {
1339                 protected Expression child;
1340
1341                 protected TypeCast (Expression child, Type return_type)
1342                 {
1343                         eclass = child.eclass;
1344                         loc = child.Location;
1345                         type = return_type;
1346                         this.child = child;
1347                 }
1348
1349                 public override Expression CreateExpressionTree (EmitContext ec)
1350                 {
1351                         ArrayList args = new ArrayList (2);
1352                         args.Add (new Argument (child.CreateExpressionTree (ec)));
1353                         args.Add (new Argument (new TypeOf (new TypeExpression (type, loc), loc)));
1354
1355                         if (type.IsPointer || child.Type.IsPointer)
1356                                 Error_PointerInsideExpressionTree ();
1357
1358                         return CreateExpressionFactoryCall (ec.CheckState ? "ConvertChecked" : "Convert", args);
1359                 }
1360
1361                 public override Expression DoResolve (EmitContext ec)
1362                 {
1363                         // This should never be invoked, we are born in fully
1364                         // initialized state.
1365
1366                         return this;
1367                 }
1368
1369                 public override void Emit (EmitContext ec)
1370                 {
1371                         child.Emit (ec);
1372                 }
1373
1374                 public override bool GetAttributableValue (Type value_type, out object value)
1375                 {
1376                         return child.GetAttributableValue (value_type, out value);
1377                 }
1378
1379                 public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
1380                 {
1381                         child.MutateHoistedGenericType (storey);
1382                 }
1383
1384                 protected override void CloneTo (CloneContext clonectx, Expression t)
1385                 {
1386                         TypeCast target = (TypeCast) t;
1387
1388                         target.child = child.Clone (clonectx);
1389                 }
1390
1391                 public override bool IsNull {
1392                         get { return child.IsNull; }
1393                 }
1394         }
1395
1396         public class EmptyCast : TypeCast {
1397                 EmptyCast (Expression child, Type target_type)
1398                         : base (child, target_type)
1399                 {
1400                 }
1401
1402                 public static Expression Create (Expression child, Type type)
1403                 {
1404                         Constant c = child as Constant;
1405                         if (c != null)
1406                                 return new EmptyConstantCast (c, type);
1407
1408                         EmptyCast e = child as EmptyCast;
1409                         if (e != null)
1410                                 return new EmptyCast (e.child, type);
1411
1412                         return new EmptyCast (child, type);
1413                 }
1414
1415                 public override void EmitBranchable (EmitContext ec, Label label, bool on_true)
1416                 {
1417                         child.EmitBranchable (ec, label, on_true);
1418                 }
1419
1420                 public override void EmitSideEffect (EmitContext ec)
1421                 {
1422                         child.EmitSideEffect (ec);
1423                 }
1424         }
1425
1426         /// <summary>
1427         ///    Performs a cast using an operator (op_Explicit or op_Implicit)
1428         /// </summary>
1429         public class OperatorCast : TypeCast {
1430                 MethodInfo conversion_operator;
1431                 bool find_explicit;
1432
1433                 public OperatorCast (Expression child, Type target_type) : this (child, target_type, false) {}
1434
1435                 public OperatorCast (Expression child, Type target_type, bool find_explicit)
1436                         : base (child, target_type)
1437                 {
1438                         this.find_explicit = find_explicit;
1439                 }
1440
1441                 // Returns the implicit operator that converts from
1442                 // 'child.Type' to our target type (type)
1443                 MethodInfo GetConversionOperator (bool find_explicit)
1444                 {
1445                         string operator_name = find_explicit ? "op_Explicit" : "op_Implicit";
1446
1447                         MemberInfo [] mi;
1448
1449                         mi = TypeManager.MemberLookup (child.Type, child.Type, child.Type, MemberTypes.Method,
1450                                 BindingFlags.Static | BindingFlags.Public, operator_name, null);
1451
1452                         if (mi == null){
1453                                 mi = TypeManager.MemberLookup (type, type, type, MemberTypes.Method,
1454                                                                BindingFlags.Static | BindingFlags.Public, operator_name, null);
1455                         }
1456
1457                         foreach (MethodInfo oper in mi) {
1458                                 ParameterData pd = TypeManager.GetParameterData (oper);
1459
1460                                 if (pd.ParameterType (0) == child.Type && TypeManager.TypeToCoreType (oper.ReturnType) == type)
1461                                         return oper;
1462                         }
1463
1464                         return null;
1465
1466
1467                 }
1468                 public override void Emit (EmitContext ec)
1469                 {
1470                         ILGenerator ig = ec.ig;
1471
1472                         child.Emit (ec);
1473                         conversion_operator = GetConversionOperator (find_explicit);
1474
1475                         if (conversion_operator == null)
1476                                 throw new InternalErrorException ("Outer conversion routine is out of sync");
1477
1478                         ig.Emit (OpCodes.Call, conversion_operator);
1479                 }
1480
1481         }
1482
1483         /// <summary>
1484         ///     This is a numeric cast to a Decimal
1485         /// </summary>
1486         public class CastToDecimal : TypeCast {
1487                 MethodInfo conversion_operator;
1488
1489                 public CastToDecimal (Expression child)
1490                         : this (child, false)
1491                 {
1492                 }
1493
1494                 public CastToDecimal (Expression child, bool find_explicit)
1495                         : base (child, TypeManager.decimal_type)
1496                 {
1497                         conversion_operator = GetConversionOperator (find_explicit);
1498
1499                         if (conversion_operator == null)
1500                                 throw new InternalErrorException ("Outer conversion routine is out of sync");
1501                 }
1502
1503                 // Returns the implicit operator that converts from
1504                 // 'child.Type' to System.Decimal.
1505                 MethodInfo GetConversionOperator (bool find_explicit)
1506                 {
1507                         string operator_name = find_explicit ? "op_Explicit" : "op_Implicit";
1508
1509                         MemberInfo [] mi = TypeManager.MemberLookup (type, type, type, MemberTypes.Method,
1510                                 BindingFlags.Static | BindingFlags.Public, operator_name, null);
1511
1512                         foreach (MethodInfo oper in mi) {
1513                                 ParameterData pd = TypeManager.GetParameterData (oper);
1514
1515                                 if (pd.ParameterType (0) == child.Type && TypeManager.TypeToCoreType (oper.ReturnType) == type)
1516                                         return oper;
1517                         }
1518
1519                         return null;
1520                 }
1521                 public override void Emit (EmitContext ec)
1522                 {
1523                         ILGenerator ig = ec.ig;
1524                         child.Emit (ec);
1525
1526                         ig.Emit (OpCodes.Call, conversion_operator);
1527                 }
1528         }
1529
1530         /// <summary>
1531         ///     This is an explicit numeric cast from a Decimal
1532         /// </summary>
1533         public class CastFromDecimal : TypeCast
1534         {
1535                 static IDictionary operators;
1536
1537                 public CastFromDecimal (Expression child, Type return_type)
1538                         : base (child, return_type)
1539                 {
1540                         if (child.Type != TypeManager.decimal_type)
1541                                 throw new InternalErrorException (
1542                                         "The expected type is Decimal, instead it is " + child.Type.FullName);
1543                 }
1544
1545                 // Returns the explicit operator that converts from an
1546                 // express of type System.Decimal to 'type'.
1547                 public Expression Resolve ()
1548                 {
1549                         if (operators == null) {
1550                                  MemberInfo[] all_oper = TypeManager.MemberLookup (TypeManager.decimal_type,
1551                                         TypeManager.decimal_type, TypeManager.decimal_type, MemberTypes.Method,
1552                                         BindingFlags.Static | BindingFlags.Public, "op_Explicit", null);
1553
1554                                 operators = new System.Collections.Specialized.HybridDictionary ();
1555                                 foreach (MethodInfo oper in all_oper) {
1556                                         ParameterData pd = TypeManager.GetParameterData (oper);
1557                                         if (pd.ParameterType (0) == TypeManager.decimal_type)
1558                                                 operators.Add (TypeManager.TypeToCoreType (oper.ReturnType), oper);
1559                                 }
1560                         }
1561
1562                         return operators.Contains (type) ? this : null;
1563                 }
1564
1565                 public override void Emit (EmitContext ec)
1566                 {
1567                         ILGenerator ig = ec.ig;
1568                         child.Emit (ec);
1569
1570                         ig.Emit (OpCodes.Call, (MethodInfo)operators [type]);
1571                 }
1572         }
1573
1574
1575         //
1576         // Constant specialization of EmptyCast.
1577         // We need to special case this since an empty cast of
1578         // a constant is still a constant.
1579         //
1580         public class EmptyConstantCast : Constant
1581         {
1582                 public readonly Constant child;
1583
1584                 public EmptyConstantCast(Constant child, Type type)
1585                         : base (child.Location)
1586                 {
1587                         eclass = child.eclass;
1588                         this.child = child;
1589                         this.type = type;
1590                 }
1591
1592                 public override string AsString ()
1593                 {
1594                         return child.AsString ();
1595                 }
1596
1597                 public override object GetValue ()
1598                 {
1599                         return child.GetValue ();
1600                 }
1601
1602                 public override Constant ConvertExplicitly (bool in_checked_context, Type target_type)
1603                 {
1604                         // FIXME: check that 'type' can be converted to 'target_type' first
1605                         return child.ConvertExplicitly (in_checked_context, target_type);
1606                 }
1607
1608                 public override Expression CreateExpressionTree (EmitContext ec)
1609                 {
1610                         ArrayList args = new ArrayList (2);
1611                         args.Add (new Argument (child.CreateExpressionTree (ec)));
1612                         args.Add (new Argument (new TypeOf (new TypeExpression (type, loc), loc)));
1613                         if (type.IsPointer)
1614                                 Error_PointerInsideExpressionTree ();
1615
1616                         return CreateExpressionFactoryCall ("Convert", args);
1617                 }
1618
1619                 public override Constant Increment ()
1620                 {
1621                         return child.Increment ();
1622                 }
1623
1624                 public override bool IsDefaultValue {
1625                         get { return child.IsDefaultValue; }
1626                 }
1627
1628                 public override bool IsNegative {
1629                         get { return child.IsNegative; }
1630                 }
1631
1632                 public override bool IsNull {
1633                         get { return child.IsNull; }
1634                 }
1635
1636                 public override bool IsZeroInteger {
1637                         get { return child.IsZeroInteger; }
1638                 }
1639
1640                 public override void Emit (EmitContext ec)
1641                 {
1642                         child.Emit (ec);
1643                 }
1644
1645                 public override void EmitBranchable (EmitContext ec, Label label, bool on_true)
1646                 {
1647                         child.EmitBranchable (ec, label, on_true);
1648                 }
1649
1650                 public override void EmitSideEffect (EmitContext ec)
1651                 {
1652                         child.EmitSideEffect (ec);
1653                 }
1654
1655                 public override Constant ConvertImplicitly (Type target_type)
1656                 {
1657                         // FIXME: Do we need to check user conversions?
1658                         if (!Convert.ImplicitStandardConversionExists (this, target_type))
1659                                 return null;
1660                         return child.ConvertImplicitly (target_type);
1661                 }
1662         }
1663
1664
1665         /// <summary>
1666         ///  This class is used to wrap literals which belong inside Enums
1667         /// </summary>
1668         public class EnumConstant : Constant {
1669                 public Constant Child;
1670
1671                 public EnumConstant (Constant child, Type enum_type):
1672                         base (child.Location)
1673                 {
1674                         eclass = child.eclass;
1675                         this.Child = child;
1676                         type = enum_type;
1677                 }
1678
1679                 public override Expression DoResolve (EmitContext ec)
1680                 {
1681                         // This should never be invoked, we are born in fully
1682                         // initialized state.
1683
1684                         return this;
1685                 }
1686
1687                 public override void Emit (EmitContext ec)
1688                 {
1689                         Child.Emit (ec);
1690                 }
1691
1692                 public override void EmitBranchable (EmitContext ec, Label label, bool on_true)
1693                 {
1694                         Child.EmitBranchable (ec, label, on_true);
1695                 }
1696
1697                 public override void EmitSideEffect (EmitContext ec)
1698                 {
1699                         Child.EmitSideEffect (ec);
1700                 }
1701
1702                 public override bool GetAttributableValue (Type value_type, out object value)
1703                 {
1704                         value = GetTypedValue ();
1705                         return true;
1706                 }
1707
1708                 public override string GetSignatureForError()
1709                 {
1710                         return TypeManager.CSharpName (Type);
1711                 }
1712
1713                 public override object GetValue ()
1714                 {
1715                         return Child.GetValue ();
1716                 }
1717
1718                 public override object GetTypedValue ()
1719                 {
1720                         // FIXME: runtime is not ready to work with just emited enums
1721                         if (!RootContext.StdLib) {
1722                                 return Child.GetValue ();
1723                         }
1724
1725                         return System.Enum.ToObject (type, Child.GetValue ());
1726                 }
1727
1728                 public override string AsString ()
1729                 {
1730                         return TypeManager.CSharpEnumValue (type, Child.GetValue ());
1731                 }
1732
1733                 public override Constant Increment()
1734                 {
1735                         return new EnumConstant (Child.Increment (), type);
1736                 }
1737
1738                 public override bool IsDefaultValue {
1739                         get {
1740                                 return Child.IsDefaultValue;
1741                         }
1742                 }
1743
1744                 public override bool IsZeroInteger {
1745                         get { return Child.IsZeroInteger; }
1746                 }
1747
1748                 public override bool IsNegative {
1749                         get {
1750                                 return Child.IsNegative;
1751                         }
1752                 }
1753
1754                 public override Constant ConvertExplicitly(bool in_checked_context, Type target_type)
1755                 {
1756                         if (Child.Type == target_type)
1757                                 return Child;
1758
1759                         return Child.ConvertExplicitly (in_checked_context, target_type);
1760                 }
1761
1762                 public override Constant ConvertImplicitly (Type type)
1763                 {
1764                         Type this_type = TypeManager.DropGenericTypeArguments (Type);
1765                         type = TypeManager.DropGenericTypeArguments (type);
1766
1767                         if (this_type == type) {
1768                                 // This is workaround of mono bug. It can be removed when the latest corlib spreads enough
1769                                 if (TypeManager.IsEnumType (type.UnderlyingSystemType))
1770                                         return this;
1771
1772                                 Type child_type = TypeManager.DropGenericTypeArguments (Child.Type);
1773                                 if (type.UnderlyingSystemType != child_type)
1774                                         Child = Child.ConvertImplicitly (type.UnderlyingSystemType);
1775                                 return this;
1776                         }
1777
1778                         if (!Convert.ImplicitStandardConversionExists (this, type)){
1779                                 return null;
1780                         }
1781
1782                         return Child.ConvertImplicitly(type);
1783                 }
1784
1785         }
1786
1787         /// <summary>
1788         ///   This kind of cast is used to encapsulate Value Types in objects.
1789         ///
1790         ///   The effect of it is to box the value type emitted by the previous
1791         ///   operation.
1792         /// </summary>
1793         public class BoxedCast : TypeCast {
1794
1795                 public BoxedCast (Expression expr, Type target_type)
1796                         : base (expr, target_type)
1797                 {
1798                         eclass = ExprClass.Value;
1799                 }
1800
1801                 public override Expression DoResolve (EmitContext ec)
1802                 {
1803                         // This should never be invoked, we are born in fully
1804                         // initialized state.
1805
1806                         return this;
1807                 }
1808
1809                 public override void Emit (EmitContext ec)
1810                 {
1811                         base.Emit (ec);
1812
1813                         ec.ig.Emit (OpCodes.Box, child.Type);
1814                 }
1815
1816                 public override void EmitSideEffect (EmitContext ec)
1817                 {
1818                         // boxing is side-effectful, since it involves runtime checks, except when boxing to Object or ValueType
1819                         // so, we need to emit the box+pop instructions in most cases
1820                         if (child.Type.IsValueType &&
1821                             (type == TypeManager.object_type || type == TypeManager.value_type))
1822                                 child.EmitSideEffect (ec);
1823                         else
1824                                 base.EmitSideEffect (ec);
1825                 }
1826         }
1827
1828         public class UnboxCast : TypeCast {
1829                 public UnboxCast (Expression expr, Type return_type)
1830                         : base (expr, return_type)
1831                 {
1832                 }
1833
1834                 public override Expression DoResolve (EmitContext ec)
1835                 {
1836                         // This should never be invoked, we are born in fully
1837                         // initialized state.
1838
1839                         return this;
1840                 }
1841
1842                 public override Expression DoResolveLValue (EmitContext ec, Expression right_side)
1843                 {
1844                         if (right_side == EmptyExpression.LValueMemberAccess || right_side == EmptyExpression.LValueMemberOutAccess)
1845                                 Report.Error (445, loc, "Cannot modify the result of an unboxing conversion");
1846                         return base.DoResolveLValue (ec, right_side);
1847                 }
1848
1849                 public override void Emit (EmitContext ec)
1850                 {
1851                         Type t = type;
1852                         ILGenerator ig = ec.ig;
1853
1854                         base.Emit (ec);
1855 #if GMCS_SOURCE
1856                         if (t.IsGenericParameter || t.IsGenericType && t.IsValueType)
1857                                 ig.Emit (OpCodes.Unbox_Any, t);
1858                         else
1859 #endif
1860                         {
1861                                 ig.Emit (OpCodes.Unbox, t);
1862
1863                                 LoadFromPtr (ig, t);
1864                         }
1865                 }
1866
1867                 public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
1868                 {
1869                         type = storey.MutateType (type);
1870                 }
1871         }
1872
1873         /// <summary>
1874         ///   This is used to perform explicit numeric conversions.
1875         ///
1876         ///   Explicit numeric conversions might trigger exceptions in a checked
1877         ///   context, so they should generate the conv.ovf opcodes instead of
1878         ///   conv opcodes.
1879         /// </summary>
1880         public class ConvCast : TypeCast {
1881                 public enum Mode : byte {
1882                         I1_U1, I1_U2, I1_U4, I1_U8, I1_CH,
1883                         U1_I1, U1_CH,
1884                         I2_I1, I2_U1, I2_U2, I2_U4, I2_U8, I2_CH,
1885                         U2_I1, U2_U1, U2_I2, U2_CH,
1886                         I4_I1, I4_U1, I4_I2, I4_U2, I4_U4, I4_U8, I4_CH,
1887                         U4_I1, U4_U1, U4_I2, U4_U2, U4_I4, U4_CH,
1888                         I8_I1, I8_U1, I8_I2, I8_U2, I8_I4, I8_U4, I8_U8, I8_CH,
1889                         U8_I1, U8_U1, U8_I2, U8_U2, U8_I4, U8_U4, U8_I8, U8_CH,
1890                         CH_I1, CH_U1, CH_I2,
1891                         R4_I1, R4_U1, R4_I2, R4_U2, R4_I4, R4_U4, R4_I8, R4_U8, R4_CH,
1892                         R8_I1, R8_U1, R8_I2, R8_U2, R8_I4, R8_U4, R8_I8, R8_U8, R8_CH, R8_R4
1893                 }
1894
1895                 Mode mode;
1896
1897                 public ConvCast (Expression child, Type return_type, Mode m)
1898                         : base (child, return_type)
1899                 {
1900                         mode = m;
1901                 }
1902
1903                 public override Expression DoResolve (EmitContext ec)
1904                 {
1905                         // This should never be invoked, we are born in fully
1906                         // initialized state.
1907
1908                         return this;
1909                 }
1910
1911                 public override string ToString ()
1912                 {
1913                         return String.Format ("ConvCast ({0}, {1})", mode, child);
1914                 }
1915
1916                 public override void Emit (EmitContext ec)
1917                 {
1918                         ILGenerator ig = ec.ig;
1919
1920                         base.Emit (ec);
1921
1922                         if (ec.CheckState){
1923                                 switch (mode){
1924                                 case Mode.I1_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
1925                                 case Mode.I1_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
1926                                 case Mode.I1_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
1927                                 case Mode.I1_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
1928                                 case Mode.I1_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
1929
1930                                 case Mode.U1_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1931                                 case Mode.U1_CH: /* nothing */ break;
1932
1933                                 case Mode.I2_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
1934                                 case Mode.I2_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
1935                                 case Mode.I2_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
1936                                 case Mode.I2_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
1937                                 case Mode.I2_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
1938                                 case Mode.I2_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
1939
1940                                 case Mode.U2_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1941                                 case Mode.U2_U1: ig.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1942                                 case Mode.U2_I2: ig.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1943                                 case Mode.U2_CH: /* nothing */ break;
1944
1945                                 case Mode.I4_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
1946                                 case Mode.I4_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
1947                                 case Mode.I4_I2: ig.Emit (OpCodes.Conv_Ovf_I2); break;
1948                                 case Mode.I4_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
1949                                 case Mode.I4_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
1950                                 case Mode.I4_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
1951                                 case Mode.I4_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
1952
1953                                 case Mode.U4_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1954                                 case Mode.U4_U1: ig.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1955                                 case Mode.U4_I2: ig.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1956                                 case Mode.U4_U2: ig.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1957                                 case Mode.U4_I4: ig.Emit (OpCodes.Conv_Ovf_I4_Un); break;
1958                                 case Mode.U4_CH: ig.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1959
1960                                 case Mode.I8_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
1961                                 case Mode.I8_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
1962                                 case Mode.I8_I2: ig.Emit (OpCodes.Conv_Ovf_I2); break;
1963                                 case Mode.I8_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
1964                                 case Mode.I8_I4: ig.Emit (OpCodes.Conv_Ovf_I4); break;
1965                                 case Mode.I8_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
1966                                 case Mode.I8_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
1967                                 case Mode.I8_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
1968
1969                                 case Mode.U8_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1970                                 case Mode.U8_U1: ig.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1971                                 case Mode.U8_I2: ig.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1972                                 case Mode.U8_U2: ig.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1973                                 case Mode.U8_I4: ig.Emit (OpCodes.Conv_Ovf_I4_Un); break;
1974                                 case Mode.U8_U4: ig.Emit (OpCodes.Conv_Ovf_U4_Un); break;
1975                                 case Mode.U8_I8: ig.Emit (OpCodes.Conv_Ovf_I8_Un); break;
1976                                 case Mode.U8_CH: ig.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1977
1978                                 case Mode.CH_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1979                                 case Mode.CH_U1: ig.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1980                                 case Mode.CH_I2: ig.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1981
1982                                 case Mode.R4_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
1983                                 case Mode.R4_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
1984                                 case Mode.R4_I2: ig.Emit (OpCodes.Conv_Ovf_I2); break;
1985                                 case Mode.R4_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
1986                                 case Mode.R4_I4: ig.Emit (OpCodes.Conv_Ovf_I4); break;
1987                                 case Mode.R4_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
1988                                 case Mode.R4_I8: ig.Emit (OpCodes.Conv_Ovf_I8); break;
1989                                 case Mode.R4_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
1990                                 case Mode.R4_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
1991
1992                                 case Mode.R8_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
1993                                 case Mode.R8_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
1994                                 case Mode.R8_I2: ig.Emit (OpCodes.Conv_Ovf_I2); break;
1995                                 case Mode.R8_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
1996                                 case Mode.R8_I4: ig.Emit (OpCodes.Conv_Ovf_I4); break;
1997                                 case Mode.R8_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
1998                                 case Mode.R8_I8: ig.Emit (OpCodes.Conv_Ovf_I8); break;
1999                                 case Mode.R8_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
2000                                 case Mode.R8_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
2001                                 case Mode.R8_R4: ig.Emit (OpCodes.Conv_R4); break;
2002                                 }
2003                         } else {
2004                                 switch (mode){
2005                                 case Mode.I1_U1: ig.Emit (OpCodes.Conv_U1); break;
2006                                 case Mode.I1_U2: ig.Emit (OpCodes.Conv_U2); break;
2007                                 case Mode.I1_U4: ig.Emit (OpCodes.Conv_U4); break;
2008                                 case Mode.I1_U8: ig.Emit (OpCodes.Conv_I8); break;
2009                                 case Mode.I1_CH: ig.Emit (OpCodes.Conv_U2); break;
2010
2011                                 case Mode.U1_I1: ig.Emit (OpCodes.Conv_I1); break;
2012                                 case Mode.U1_CH: ig.Emit (OpCodes.Conv_U2); break;
2013
2014                                 case Mode.I2_I1: ig.Emit (OpCodes.Conv_I1); break;
2015                                 case Mode.I2_U1: ig.Emit (OpCodes.Conv_U1); break;
2016                                 case Mode.I2_U2: ig.Emit (OpCodes.Conv_U2); break;
2017                                 case Mode.I2_U4: ig.Emit (OpCodes.Conv_U4); break;
2018                                 case Mode.I2_U8: ig.Emit (OpCodes.Conv_I8); break;
2019                                 case Mode.I2_CH: ig.Emit (OpCodes.Conv_U2); break;
2020
2021                                 case Mode.U2_I1: ig.Emit (OpCodes.Conv_I1); break;
2022                                 case Mode.U2_U1: ig.Emit (OpCodes.Conv_U1); break;
2023                                 case Mode.U2_I2: ig.Emit (OpCodes.Conv_I2); break;
2024                                 case Mode.U2_CH: /* nothing */ break;
2025
2026                                 case Mode.I4_I1: ig.Emit (OpCodes.Conv_I1); break;
2027                                 case Mode.I4_U1: ig.Emit (OpCodes.Conv_U1); break;
2028                                 case Mode.I4_I2: ig.Emit (OpCodes.Conv_I2); break;
2029                                 case Mode.I4_U4: /* nothing */ break;
2030                                 case Mode.I4_U2: ig.Emit (OpCodes.Conv_U2); break;
2031                                 case Mode.I4_U8: ig.Emit (OpCodes.Conv_I8); break;
2032                                 case Mode.I4_CH: ig.Emit (OpCodes.Conv_U2); break;
2033
2034                                 case Mode.U4_I1: ig.Emit (OpCodes.Conv_I1); break;
2035                                 case Mode.U4_U1: ig.Emit (OpCodes.Conv_U1); break;
2036                                 case Mode.U4_I2: ig.Emit (OpCodes.Conv_I2); break;
2037                                 case Mode.U4_U2: ig.Emit (OpCodes.Conv_U2); break;
2038                                 case Mode.U4_I4: /* nothing */ break;
2039                                 case Mode.U4_CH: ig.Emit (OpCodes.Conv_U2); break;
2040
2041                                 case Mode.I8_I1: ig.Emit (OpCodes.Conv_I1); break;
2042                                 case Mode.I8_U1: ig.Emit (OpCodes.Conv_U1); break;
2043                                 case Mode.I8_I2: ig.Emit (OpCodes.Conv_I2); break;
2044                                 case Mode.I8_U2: ig.Emit (OpCodes.Conv_U2); break;
2045                                 case Mode.I8_I4: ig.Emit (OpCodes.Conv_I4); break;
2046                                 case Mode.I8_U4: ig.Emit (OpCodes.Conv_U4); break;
2047                                 case Mode.I8_U8: /* nothing */ break;
2048                                 case Mode.I8_CH: ig.Emit (OpCodes.Conv_U2); break;
2049
2050                                 case Mode.U8_I1: ig.Emit (OpCodes.Conv_I1); break;
2051                                 case Mode.U8_U1: ig.Emit (OpCodes.Conv_U1); break;
2052                                 case Mode.U8_I2: ig.Emit (OpCodes.Conv_I2); break;
2053                                 case Mode.U8_U2: ig.Emit (OpCodes.Conv_U2); break;
2054                                 case Mode.U8_I4: ig.Emit (OpCodes.Conv_I4); break;
2055                                 case Mode.U8_U4: ig.Emit (OpCodes.Conv_U4); break;
2056                                 case Mode.U8_I8: /* nothing */ break;
2057                                 case Mode.U8_CH: ig.Emit (OpCodes.Conv_U2); break;
2058
2059                                 case Mode.CH_I1: ig.Emit (OpCodes.Conv_I1); break;
2060                                 case Mode.CH_U1: ig.Emit (OpCodes.Conv_U1); break;
2061                                 case Mode.CH_I2: ig.Emit (OpCodes.Conv_I2); break;
2062
2063                                 case Mode.R4_I1: ig.Emit (OpCodes.Conv_I1); break;
2064                                 case Mode.R4_U1: ig.Emit (OpCodes.Conv_U1); break;
2065                                 case Mode.R4_I2: ig.Emit (OpCodes.Conv_I2); break;
2066                                 case Mode.R4_U2: ig.Emit (OpCodes.Conv_U2); break;
2067                                 case Mode.R4_I4: ig.Emit (OpCodes.Conv_I4); break;
2068                                 case Mode.R4_U4: ig.Emit (OpCodes.Conv_U4); break;
2069                                 case Mode.R4_I8: ig.Emit (OpCodes.Conv_I8); break;
2070                                 case Mode.R4_U8: ig.Emit (OpCodes.Conv_U8); break;
2071                                 case Mode.R4_CH: ig.Emit (OpCodes.Conv_U2); break;
2072
2073                                 case Mode.R8_I1: ig.Emit (OpCodes.Conv_I1); break;
2074                                 case Mode.R8_U1: ig.Emit (OpCodes.Conv_U1); break;
2075                                 case Mode.R8_I2: ig.Emit (OpCodes.Conv_I2); break;
2076                                 case Mode.R8_U2: ig.Emit (OpCodes.Conv_U2); break;
2077                                 case Mode.R8_I4: ig.Emit (OpCodes.Conv_I4); break;
2078                                 case Mode.R8_U4: ig.Emit (OpCodes.Conv_U4); break;
2079                                 case Mode.R8_I8: ig.Emit (OpCodes.Conv_I8); break;
2080                                 case Mode.R8_U8: ig.Emit (OpCodes.Conv_U8); break;
2081                                 case Mode.R8_CH: ig.Emit (OpCodes.Conv_U2); break;
2082                                 case Mode.R8_R4: ig.Emit (OpCodes.Conv_R4); break;
2083                                 }
2084                         }
2085                 }
2086         }
2087
2088         public class OpcodeCast : TypeCast {
2089                 OpCode op, op2;
2090                 bool second_valid;
2091
2092                 public OpcodeCast (Expression child, Type return_type, OpCode op)
2093                         : base (child, return_type)
2094
2095                 {
2096                         this.op = op;
2097                         second_valid = false;
2098                 }
2099
2100                 public OpcodeCast (Expression child, Type return_type, OpCode op, OpCode op2)
2101                         : base (child, return_type)
2102
2103                 {
2104                         this.op = op;
2105                         this.op2 = op2;
2106                         second_valid = true;
2107                 }
2108
2109                 public override Expression DoResolve (EmitContext ec)
2110                 {
2111                         // This should never be invoked, we are born in fully
2112                         // initialized state.
2113
2114                         return this;
2115                 }
2116
2117                 public override void Emit (EmitContext ec)
2118                 {
2119                         base.Emit (ec);
2120                         ec.ig.Emit (op);
2121
2122                         if (second_valid)
2123                                 ec.ig.Emit (op2);
2124                 }
2125
2126                 public Type UnderlyingType {
2127                         get { return child.Type; }
2128                 }
2129         }
2130
2131         /// <summary>
2132         ///   This kind of cast is used to encapsulate a child and cast it
2133         ///   to the class requested
2134         /// </summary>
2135         public sealed class ClassCast : TypeCast {
2136                 Type child_generic_parameter;
2137
2138                 public ClassCast (Expression child, Type return_type)
2139                         : base (child, return_type)
2140
2141                 {
2142                         if (TypeManager.IsGenericParameter (child.Type))
2143                                 child_generic_parameter = child.Type;
2144                 }
2145
2146                 public override Expression DoResolve (EmitContext ec)
2147                 {
2148                         // This should never be invoked, we are born in fully
2149                         // initialized state.
2150
2151                         return this;
2152                 }
2153
2154                 public override void Emit (EmitContext ec)
2155                 {
2156                         base.Emit (ec);
2157
2158                         if (child_generic_parameter != null)
2159                                 ec.ig.Emit (OpCodes.Box, child_generic_parameter);
2160
2161 #if GMCS_SOURCE
2162                         if (type.IsGenericParameter)
2163                                 ec.ig.Emit (OpCodes.Unbox_Any, type);
2164                         else
2165 #endif
2166                                 ec.ig.Emit (OpCodes.Castclass, type);
2167                 }
2168
2169                 public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
2170                 {
2171                         type = storey.MutateType (type);
2172                         if (child_generic_parameter != null)
2173                                 child_generic_parameter = storey.MutateGenericArgument (child_generic_parameter);
2174
2175                         base.MutateHoistedGenericType (storey);
2176                 }
2177         }
2178
2179         //
2180         // Used when resolved expression has different representations for
2181         // expression trees and emit phase
2182         //
2183         public class ReducedExpression : Expression
2184         {
2185                 class ReducedConstantExpression : Constant
2186                 {
2187                         readonly Constant expr;
2188                         readonly Expression orig_expr;
2189
2190                         public ReducedConstantExpression (Constant expr, Expression orig_expr)
2191                                 : base (expr.Location)
2192                         {
2193                                 this.expr = expr;
2194                                 this.orig_expr = orig_expr;
2195                                 eclass = expr.eclass;
2196                                 type = expr.Type;
2197                         }
2198
2199                         public override string AsString ()
2200                         {
2201                                 return expr.AsString ();
2202                         }
2203
2204                         public override Expression CreateExpressionTree (EmitContext ec)
2205                         {
2206                                 return orig_expr.CreateExpressionTree (ec);
2207                         }
2208
2209                         public override object GetValue ()
2210                         {
2211                                 return expr.GetValue ();
2212                         }
2213
2214                         public override Constant ConvertExplicitly (bool in_checked_context, Type target_type)
2215                         {
2216                                 throw new NotImplementedException ();
2217                         }
2218
2219                         public override Expression DoResolve (EmitContext ec)
2220                         {
2221                                 return this;
2222                         }
2223
2224                         public override Constant Increment ()
2225                         {
2226                                 throw new NotImplementedException ();
2227                         }
2228
2229                         public override bool IsDefaultValue {
2230                                 get {
2231                                         return expr.IsDefaultValue;
2232                                 }
2233                         }
2234
2235                         public override bool IsNegative {
2236                                 get {
2237                                         return expr.IsNegative;
2238                                 }
2239                         }
2240
2241                         public override void Emit (EmitContext ec)
2242                         {
2243                                 expr.Emit (ec);
2244                         }
2245                 }
2246
2247                 readonly Expression expr, orig_expr;
2248
2249                 private ReducedExpression (Expression expr, Expression orig_expr)
2250                 {
2251                         this.expr = expr;
2252                         this.orig_expr = orig_expr;
2253                         this.loc = orig_expr.Location;
2254                 }
2255
2256                 public static Expression Create (Constant expr, Expression original_expr)
2257                 {
2258                         return new ReducedConstantExpression (expr, original_expr);
2259                 }
2260
2261                 public static Expression Create (Expression expr, Expression original_expr)
2262                 {
2263                         Constant c = expr as Constant;
2264                         if (c != null)
2265                                 return Create (c, original_expr);
2266
2267                         return new ReducedExpression (expr, original_expr);
2268                 }
2269
2270                 public override Expression CreateExpressionTree (EmitContext ec)
2271                 {
2272                         return orig_expr.CreateExpressionTree (ec);
2273                 }
2274
2275                 public override Expression DoResolve (EmitContext ec)
2276                 {
2277                         eclass = expr.eclass;
2278                         type = expr.Type;
2279                         return this;
2280                 }
2281
2282                 public override void Emit (EmitContext ec)
2283                 {
2284                         expr.Emit (ec);
2285                 }
2286
2287                 public override void EmitBranchable (EmitContext ec, Label target, bool on_true)
2288                 {
2289                         expr.EmitBranchable (ec, target, on_true);
2290                 }
2291         }
2292
2293         //
2294         // Unresolved type name expressions
2295         //
2296         public abstract class ATypeNameExpression : FullNamedExpression
2297         {
2298                 public readonly string Name;
2299                 protected TypeArguments targs;
2300
2301                 protected ATypeNameExpression (string name, Location l)
2302                 {
2303                         Name = name;
2304                         loc = l;
2305                 }
2306
2307                 protected ATypeNameExpression (string name, TypeArguments targs, Location l)
2308                 {
2309                         Name = name;
2310                         this.targs = targs;
2311                         loc = l;
2312                 }
2313
2314                 public bool HasTypeArguments {
2315                         get {
2316                                 return targs != null;
2317                         }
2318                 }
2319
2320                 public override string GetSignatureForError ()
2321                 {
2322                         if (targs != null) {
2323                                 return TypeManager.RemoveGenericArity (Name) + "<" +
2324                                         targs.GetSignatureForError () + ">";
2325                         }
2326
2327                         return Name;
2328                 }
2329         }
2330
2331         /// <summary>
2332         ///   SimpleName expressions are formed of a single word and only happen at the beginning
2333         ///   of a dotted-name.
2334         /// </summary>
2335         public class SimpleName : ATypeNameExpression {
2336                 bool in_transit;
2337
2338                 public SimpleName (string name, Location l)
2339                         : base (name, l)
2340                 {
2341                 }
2342
2343                 public SimpleName (string name, TypeArguments args, Location l)
2344                         : base (name, args, l)
2345                 {
2346                 }
2347
2348                 public SimpleName (string name, TypeParameter[] type_params, Location l)
2349                         : base (name, l)
2350                 {
2351                         targs = new TypeArguments (l);
2352                         foreach (TypeParameter type_param in type_params)
2353                                 targs.Add (new TypeParameterExpr (type_param, l));
2354                 }
2355
2356                 public static string RemoveGenericArity (string name)
2357                 {
2358                         int start = 0;
2359                         StringBuilder sb = null;
2360                         do {
2361                                 int pos = name.IndexOf ('`', start);
2362                                 if (pos < 0) {
2363                                         if (start == 0)
2364                                                 return name;
2365
2366                                         sb.Append (name.Substring (start));
2367                                         break;
2368                                 }
2369
2370                                 if (sb == null)
2371                                         sb = new StringBuilder ();
2372                                 sb.Append (name.Substring (start, pos-start));
2373
2374                                 pos++;
2375                                 while ((pos < name.Length) && Char.IsNumber (name [pos]))
2376                                         pos++;
2377
2378                                 start = pos;
2379                         } while (start < name.Length);
2380
2381                         return sb.ToString ();
2382                 }
2383
2384                 public SimpleName GetMethodGroup ()
2385                 {
2386                         return new SimpleName (RemoveGenericArity (Name), targs, loc);
2387                 }
2388
2389                 public static void Error_ObjectRefRequired (EmitContext ec, Location l, string name)
2390                 {
2391                         if (ec.IsInFieldInitializer)
2392                                 Report.Error (236, l,
2393                                         "A field initializer cannot reference the nonstatic field, method, or property `{0}'",
2394                                         name);
2395                         else
2396                                 Report.Error (
2397                                         120, l, "`{0}': An object reference is required for the nonstatic field, method or property",
2398                                         name);
2399                 }
2400
2401                 public bool IdenticalNameAndTypeName (EmitContext ec, Expression resolved_to, Location loc)
2402                 {
2403                         return resolved_to != null && resolved_to.Type != null &&
2404                                 resolved_to.Type.Name == Name &&
2405                                 (ec.DeclContainer.LookupNamespaceOrType (Name, loc, /* ignore_cs0104 = */ true) != null);
2406                 }
2407
2408                 public override Expression DoResolve (EmitContext ec)
2409                 {
2410                         return SimpleNameResolve (ec, null, false);
2411                 }
2412
2413                 public override Expression DoResolveLValue (EmitContext ec, Expression right_side)
2414                 {
2415                         return SimpleNameResolve (ec, right_side, false);
2416                 }
2417
2418
2419                 public Expression DoResolve (EmitContext ec, bool intermediate)
2420                 {
2421                         return SimpleNameResolve (ec, null, intermediate);
2422                 }
2423
2424                 static bool IsNestedChild (Type t, Type parent)
2425                 {
2426                         while (parent != null) {
2427                                 if (TypeManager.IsNestedChildOf (t, TypeManager.DropGenericTypeArguments (parent)))
2428                                         return true;
2429
2430                                 parent = parent.BaseType;
2431                         }
2432
2433                         return false;
2434                 }
2435
2436                 FullNamedExpression ResolveNested (IResolveContext ec, Type t)
2437                 {
2438                         if (!TypeManager.IsGenericTypeDefinition (t) && !TypeManager.IsGenericType (t))
2439                                 return null;
2440
2441                         DeclSpace ds = ec.DeclContainer;
2442                         while (ds != null && !IsNestedChild (t, ds.TypeBuilder))
2443                                 ds = ds.Parent;
2444
2445                         if (ds == null)
2446                                 return null;
2447
2448                         Type[] gen_params = TypeManager.GetTypeArguments (t);
2449
2450                         int arg_count = targs != null ? targs.Count : 0;
2451
2452                         for (; (ds != null) && ds.IsGeneric; ds = ds.Parent) {
2453                                 if (arg_count + ds.CountTypeParameters == gen_params.Length) {
2454                                         TypeArguments new_args = new TypeArguments (loc);
2455                                         foreach (TypeParameter param in ds.TypeParameters)
2456                                                 new_args.Add (new TypeParameterExpr (param, loc));
2457
2458                                         if (targs != null)
2459                                                 new_args.Add (targs);
2460
2461                                         return new ConstructedType (t, new_args, loc);
2462                                 }
2463                         }
2464
2465                         return null;
2466                 }
2467
2468                 public override FullNamedExpression ResolveAsTypeStep (IResolveContext ec, bool silent)
2469                 {
2470                         FullNamedExpression fne = ec.GenericDeclContainer.LookupGeneric (Name, loc);
2471                         if (fne != null)
2472                                 return fne.ResolveAsTypeStep (ec, silent);
2473
2474                         int errors = Report.Errors;
2475                         fne = ec.DeclContainer.LookupNamespaceOrType (Name, loc, /*ignore_cs0104=*/ false);
2476
2477                         if (fne != null) {
2478                                 if (fne.Type == null)
2479                                         return fne;
2480
2481                                 FullNamedExpression nested = ResolveNested (ec, fne.Type);
2482                                 if (nested != null)
2483                                         return nested.ResolveAsTypeStep (ec, false);
2484
2485                                 if (targs != null) {
2486                                         ConstructedType ct = new ConstructedType (fne, targs, loc);
2487                                         return ct.ResolveAsTypeStep (ec, false);
2488                                 }
2489
2490                                 return fne;
2491                         }
2492
2493                         if (silent || errors != Report.Errors)
2494                                 return null;
2495
2496                         Error_TypeOrNamespaceNotFound (ec);
2497                         return null;
2498                 }
2499
2500                 protected virtual void Error_TypeOrNamespaceNotFound (IResolveContext ec)
2501                 {
2502                         MemberCore mc = ec.DeclContainer.GetDefinition (Name);
2503                         if (mc != null) {
2504                                 Error_UnexpectedKind (ec.DeclContainer, "type", GetMemberType (mc), loc);
2505                                 return;
2506                         }
2507
2508                         string ns = ec.DeclContainer.NamespaceEntry.NS.Name;
2509                         string fullname = (ns.Length > 0) ? ns + "." + Name : Name;
2510                         foreach (Assembly a in RootNamespace.Global.Assemblies) {
2511                                 Type type = a.GetType (fullname);
2512                                 if (type != null) {
2513                                         Report.SymbolRelatedToPreviousError (type);
2514                                         Expression.ErrorIsInaccesible (loc, TypeManager.CSharpName (type));
2515                                         return;
2516                                 }
2517                         }
2518
2519                         Type t = ec.DeclContainer.LookupAnyGeneric (Name);
2520                         if (t != null) {
2521                                 Namespace.Error_InvalidNumberOfTypeArguments (t, loc);
2522                                 return;
2523                         }
2524
2525                         if (targs != null) {
2526                                 FullNamedExpression retval = ec.DeclContainer.LookupNamespaceOrType (SimpleName.RemoveGenericArity (Name), loc, true);
2527                                 if (retval != null) {
2528                                         Namespace.Error_TypeArgumentsCannotBeUsed (retval.Type, loc);
2529                                         return;
2530                                 }
2531                         }
2532
2533                         NamespaceEntry.Error_NamespaceNotFound (loc, Name);
2534                 }
2535
2536                 // TODO: I am still not convinced about this. If someone else will need it
2537                 // implement this as virtual property in MemberCore hierarchy
2538                 public static string GetMemberType (MemberCore mc)
2539                 {
2540                         if (mc is Property)
2541                                 return "property";
2542                         if (mc is Indexer)
2543                                 return "indexer";
2544                         if (mc is FieldBase)
2545                                 return "field";
2546                         if (mc is MethodCore)
2547                                 return "method";
2548                         if (mc is EnumMember)
2549                                 return "enum";
2550                         if (mc is Event)
2551                                 return "event";
2552
2553                         return "type";
2554                 }
2555
2556                 Expression SimpleNameResolve (EmitContext ec, Expression right_side, bool intermediate)
2557                 {
2558                         if (in_transit)
2559                                 return null;
2560
2561                         in_transit = true;
2562                         Expression e = DoSimpleNameResolve (ec, right_side, intermediate);
2563                         in_transit = false;
2564
2565                         if (e == null)
2566                                 return null;
2567
2568                         if (ec.CurrentBlock == null || ec.CurrentBlock.CheckInvariantMeaningInBlock (Name, e, Location))
2569                                 return e;
2570
2571                         return null;
2572                 }
2573
2574                 /// <remarks>
2575                 ///   7.5.2: Simple Names.
2576                 ///
2577                 ///   Local Variables and Parameters are handled at
2578                 ///   parse time, so they never occur as SimpleNames.
2579                 ///
2580                 ///   The `intermediate' flag is used by MemberAccess only
2581                 ///   and it is used to inform us that it is ok for us to
2582                 ///   avoid the static check, because MemberAccess might end
2583                 ///   up resolving the Name as a Type name and the access as
2584                 ///   a static type access.
2585                 ///
2586                 ///   ie: Type Type; .... { Type.GetType (""); }
2587                 ///
2588                 ///   Type is both an instance variable and a Type;  Type.GetType
2589                 ///   is the static method not an instance method of type.
2590                 /// </remarks>
2591                 Expression DoSimpleNameResolve (EmitContext ec, Expression right_side, bool intermediate)
2592                 {
2593                         Expression e = null;
2594
2595                         //
2596                         // Stage 1: Performed by the parser (binding to locals or parameters).
2597                         //
2598                         Block current_block = ec.CurrentBlock;
2599                         if (current_block != null){
2600                                 LocalInfo vi = current_block.GetLocalInfo (Name);
2601                                 if (vi != 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                                         LocalVariableReference var = new LocalVariableReference (ec.CurrentBlock, Name, loc);
2610                                         if (right_side != null) {
2611                                                 return var.ResolveLValue (ec, right_side, loc);
2612                                         } else {
2613                                                 ResolveFlags rf = ResolveFlags.VariableOrValue;
2614                                                 if (intermediate)
2615                                                         rf |= ResolveFlags.DisableFlowAnalysis;
2616                                                 return var.Resolve (ec, rf);
2617                                         }
2618                                 }
2619
2620                                 ParameterReference pref = current_block.Toplevel.GetParameterReference (Name, loc);
2621                                 if (pref != null) {
2622                                         if (targs != null) {
2623                                                 Report.Error (307, loc,
2624                                                               "The variable `{0}' cannot be used with type arguments",
2625                                                               Name);
2626                                                 return null;
2627                                         }
2628
2629                                         if (right_side != null)
2630                                                 return pref.ResolveLValue (ec, right_side, loc);
2631                                         else
2632                                                 return pref.Resolve (ec);
2633                                 }
2634
2635                                 Expression expr = current_block.Toplevel.GetTransparentIdentifier (Name);
2636                                 if (expr != null) {
2637                                         if (right_side != null)
2638                                                 return expr.ResolveLValue (ec, right_side, loc);
2639                                         return expr.Resolve (ec);
2640                                 }
2641                         }
2642
2643                         //
2644                         // Stage 2: Lookup members
2645                         //
2646
2647                         Type almost_matched_type = null;
2648                         ArrayList almost_matched = null;
2649                         for (DeclSpace lookup_ds = ec.DeclContainer; lookup_ds != null; lookup_ds = lookup_ds.Parent) {
2650                                 // either RootDeclSpace or GenericMethod
2651                                 if (lookup_ds.TypeBuilder == null)
2652                                         continue;
2653
2654                                 e = MemberLookup (ec.ContainerType, lookup_ds.TypeBuilder, Name, loc);
2655                                 if (e != null) {
2656                                         if (e is PropertyExpr) {
2657                                                 // since TypeManager.MemberLookup doesn't know if we're doing a lvalue access or not,
2658                                                 // it doesn't know which accessor to check permissions against
2659                                                 if (((PropertyExpr) e).IsAccessibleFrom (ec.ContainerType, right_side != null))
2660                                                         break;
2661                                         } else if (e is EventExpr) {
2662                                                 if (((EventExpr) e).IsAccessibleFrom (ec.ContainerType))
2663                                                         break;
2664                                         } else {
2665                                                 break;
2666                                         }
2667                                         e = null;
2668                                 }
2669
2670                                 if (almost_matched == null && almost_matched_members.Count > 0) {
2671                                         almost_matched_type = lookup_ds.TypeBuilder;
2672                                         almost_matched = (ArrayList) almost_matched_members.Clone ();
2673                                 }
2674                         }
2675
2676                         if (e == null) {
2677                                 if (almost_matched == null && almost_matched_members.Count > 0) {
2678                                         almost_matched_type = ec.ContainerType;
2679                                         almost_matched = (ArrayList) almost_matched_members.Clone ();
2680                                 }
2681                                 e = ResolveAsTypeStep (ec, true);
2682                         }
2683
2684                         if (e == null) {
2685                                 if (current_block != null) {
2686                                         IKnownVariable ikv = current_block.Explicit.GetKnownVariable (Name);
2687                                         if (ikv != null) {
2688                                                 LocalInfo li = ikv as LocalInfo;
2689                                                 // Supress CS0219 warning
2690                                                 if (li != null)
2691                                                         li.Used = true;
2692
2693                                                 Error_VariableIsUsedBeforeItIsDeclared (Name);
2694                                                 return null;
2695                                         }
2696                                 }
2697
2698                                 if (almost_matched != null)
2699                                         almost_matched_members = almost_matched;
2700                                 if (almost_matched_type == null)
2701                                         almost_matched_type = ec.ContainerType;
2702                                 Error_MemberLookupFailed (ec.ContainerType, null, almost_matched_type, Name,
2703                                         ec.DeclContainer.Name, AllMemberTypes, AllBindingFlags);
2704                                 return null;
2705                         }
2706
2707                         if (e is TypeExpr) {
2708                                 if (targs == null)
2709                                         return e;
2710
2711                                 ConstructedType ct = new ConstructedType (
2712                                         e.Type, targs, loc);
2713                                 return ct.ResolveAsTypeStep (ec, false);
2714                         }
2715
2716                         if (e is MemberExpr) {
2717                                 MemberExpr me = (MemberExpr) e;
2718
2719                                 Expression left;
2720                                 if (me.IsInstance) {
2721                                         if (ec.IsStatic || ec.IsInFieldInitializer) {
2722                                                 //
2723                                                 // Note that an MemberExpr can be both IsInstance and IsStatic.
2724                                                 // An unresolved MethodGroupExpr can contain both kinds of methods
2725                                                 // and each predicate is true if the MethodGroupExpr contains
2726                                                 // at least one of that kind of method.
2727                                                 //
2728
2729                                                 if (!me.IsStatic &&
2730                                                     (!intermediate || !IdenticalNameAndTypeName (ec, me, loc))) {
2731                                                         Error_ObjectRefRequired (ec, loc, me.GetSignatureForError ());
2732                                                         return null;
2733                                                 }
2734
2735                                                 //
2736                                                 // Pass the buck to MemberAccess and Invocation.
2737                                                 //
2738                                                 left = EmptyExpression.Null;
2739                                         } else {
2740                                                 left = ec.GetThis (loc);
2741                                         }
2742                                 } else {
2743                                         left = new TypeExpression (ec.ContainerType, loc);
2744                                 }
2745
2746                                 me = me.ResolveMemberAccess (ec, left, loc, null);
2747                                 if (me == null)
2748                                         return null;
2749
2750                                 if (targs != null) {
2751                                         targs.Resolve (ec);
2752                                         me.SetTypeArguments (targs);
2753                                 }
2754
2755                                 if (!me.IsStatic && (me.InstanceExpression != null) &&
2756                                     TypeManager.IsNestedFamilyAccessible (me.InstanceExpression.Type, me.DeclaringType) &&
2757                                     me.InstanceExpression.Type != me.DeclaringType &&
2758                                     !TypeManager.IsFamilyAccessible (me.InstanceExpression.Type, me.DeclaringType) &&
2759                                     (!intermediate || !IdenticalNameAndTypeName (ec, e, loc))) {
2760                                         Report.Error (38, loc, "Cannot access a nonstatic member of outer type `{0}' via nested type `{1}'",
2761                                                 TypeManager.CSharpName (me.DeclaringType), TypeManager.CSharpName (me.InstanceExpression.Type));
2762                                         return null;
2763                                 }
2764
2765                                 return (right_side != null)
2766                                         ? me.DoResolveLValue (ec, right_side)
2767                                         : me.DoResolve (ec);
2768                         }
2769
2770                         return e;
2771                 }
2772
2773                 protected override void CloneTo (CloneContext clonectx, Expression target)
2774                 {
2775                         // CloneTo: Nothing, we do not keep any state on this expression
2776                 }
2777         }
2778
2779         /// <summary>
2780         ///   Represents a namespace or a type.  The name of the class was inspired by
2781         ///   section 10.8.1 (Fully Qualified Names).
2782         /// </summary>
2783         public abstract class FullNamedExpression : Expression {
2784
2785                 public override Expression CreateExpressionTree (EmitContext ec)
2786                 {
2787                         throw new NotSupportedException ("ET");
2788                 }
2789
2790                 public override FullNamedExpression ResolveAsTypeStep (IResolveContext ec, bool silent)
2791                 {
2792                         return this;
2793                 }
2794
2795                 public override void Emit (EmitContext ec)
2796                 {
2797                         throw new InternalErrorException ("FullNamedExpression `{0}' found in resolved tree",
2798                                 GetSignatureForError ());
2799                 }
2800         }
2801
2802         /// <summary>
2803         ///   Expression that evaluates to a type
2804         /// </summary>
2805         public abstract class TypeExpr : FullNamedExpression {
2806                 override public FullNamedExpression ResolveAsTypeStep (IResolveContext ec, bool silent)
2807                 {
2808                         TypeExpr t = DoResolveAsTypeStep (ec);
2809                         if (t == null)
2810                                 return null;
2811
2812                         eclass = ExprClass.Type;
2813                         return t;
2814                 }
2815
2816                 override public Expression DoResolve (EmitContext ec)
2817                 {
2818                         return ResolveAsTypeTerminal (ec, false);
2819                 }
2820
2821                 public virtual bool CheckAccessLevel (DeclSpace ds)
2822                 {
2823                         return ds.CheckAccessLevel (Type);
2824                 }
2825
2826                 public virtual bool AsAccessible (DeclSpace ds)
2827                 {
2828                         return ds.IsAccessibleAs (Type);
2829                 }
2830
2831                 public virtual bool IsClass {
2832                         get { return Type.IsClass; }
2833                 }
2834
2835                 public virtual bool IsValueType {
2836                         get { return Type.IsValueType; }
2837                 }
2838
2839                 public virtual bool IsInterface {
2840                         get { return Type.IsInterface; }
2841                 }
2842
2843                 public virtual bool IsSealed {
2844                         get { return Type.IsSealed; }
2845                 }
2846
2847                 public virtual bool CanInheritFrom ()
2848                 {
2849                         if (Type == TypeManager.enum_type ||
2850                             (Type == TypeManager.value_type && RootContext.StdLib) ||
2851                             Type == TypeManager.multicast_delegate_type ||
2852                             Type == TypeManager.delegate_type ||
2853                             Type == TypeManager.array_type)
2854                                 return false;
2855
2856                         return true;
2857                 }
2858
2859                 protected abstract TypeExpr DoResolveAsTypeStep (IResolveContext ec);
2860
2861                 public override bool Equals (object obj)
2862                 {
2863                         TypeExpr tobj = obj as TypeExpr;
2864                         if (tobj == null)
2865                                 return false;
2866
2867                         return Type == tobj.Type;
2868                 }
2869
2870                 public override int GetHashCode ()
2871                 {
2872                         return Type.GetHashCode ();
2873                 }
2874
2875                 public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
2876                 {
2877                         type = storey.MutateType (type);
2878                 }
2879         }
2880
2881         /// <summary>
2882         ///   Fully resolved Expression that already evaluated to a type
2883         /// </summary>
2884         public class TypeExpression : TypeExpr {
2885                 public TypeExpression (Type t, Location l)
2886                 {
2887                         Type = t;
2888                         eclass = ExprClass.Type;
2889                         loc = l;
2890                 }
2891
2892                 protected override TypeExpr DoResolveAsTypeStep (IResolveContext ec)
2893                 {
2894                         return this;
2895                 }
2896
2897                 public override TypeExpr ResolveAsTypeTerminal (IResolveContext ec, bool silent)
2898                 {
2899                         return this;
2900                 }
2901         }
2902
2903         /// <summary>
2904         ///   Used to create types from a fully qualified name.  These are just used
2905         ///   by the parser to setup the core types.  A TypeLookupExpression is always
2906         ///   classified as a type.
2907         /// </summary>
2908         public sealed class TypeLookupExpression : TypeExpr {
2909                 readonly string name;
2910
2911                 public TypeLookupExpression (string name)
2912                 {
2913                         this.name = name;
2914                         eclass = ExprClass.Type;
2915                 }
2916
2917                 public override TypeExpr ResolveAsTypeTerminal (IResolveContext ec, bool silent)
2918                 {
2919                         // It's null for corlib compilation only
2920                         if (type == null)
2921                                 return DoResolveAsTypeStep (ec);
2922
2923                         return this;
2924                 }
2925
2926                 private class UnexpectedType
2927                 {
2928                 }
2929
2930                 // This performes recursive type lookup, providing support for generic types.
2931                 // For example, given the type:
2932                 //
2933                 // System.Collections.Generic.KeyValuePair`2[[System.Int32],[System.String]]
2934                 //
2935                 // The types will be checked in the following order:
2936                 //                                                                             _
2937                 // System                                                                       |
2938                 // System.Collections                                                           |
2939                 // System.Collections.Generic                                                   |
2940                 //                        _                                                     |
2941                 //     System              | recursive call 1                                   |
2942                 //     System.Int32       _|                                                    | main method call
2943                 //                        _                                                     |
2944                 //     System              | recursive call 2                                   |
2945                 //     System.String      _|                                                    |
2946                 //                                                                              |
2947                 // System.Collections.Generic.KeyValuePair`2[[System.Int32],[System.String]]   _|
2948                 //
2949                 private Type TypeLookup (IResolveContext ec, string name)
2950                 {
2951                         int index = 0;
2952                         int dot = 0;
2953                         bool done = false;
2954                         FullNamedExpression resolved = null;
2955                         Type type = null;
2956                         Type recursive_type = null;
2957                         while (index < name.Length) {
2958                                 if (name[index] == '[') {
2959                                         int open = index;
2960                                         int braces = 1;
2961                                         do {
2962                                                 index++;
2963                                                 if (name[index] == '[')
2964                                                         braces++;
2965                                                 else if (name[index] == ']')
2966                                                         braces--;
2967                                         } while (braces > 0);
2968                                         recursive_type = TypeLookup (ec, name.Substring (open + 1, index - open - 1));
2969                                         if (recursive_type == null || (recursive_type == typeof(UnexpectedType)))
2970                                                 return recursive_type;
2971                                 }
2972                                 else {
2973                                         if (name[index] == ',')
2974                                                 done = true;
2975                                         else if ((name[index] == '.' && !done) || (index == name.Length && name[0] != '[')) {
2976                                                 string substring = name.Substring(dot, index - dot);
2977
2978                                                 if (resolved == null)
2979                                                         resolved = RootNamespace.Global.Lookup (ec.DeclContainer, substring, Location.Null);
2980                                                 else if (resolved is Namespace)
2981                                                     resolved = (resolved as Namespace).Lookup (ec.DeclContainer, substring, Location.Null);
2982                                                 else if (type != null)
2983                                                         type = TypeManager.GetNestedType (type, substring);
2984                                                 else
2985                                                         return null;
2986
2987                                                 if (resolved == null)
2988                                                         return null;
2989                                                 else if (type == null && resolved is TypeExpr)
2990                                                         type = resolved.Type;
2991
2992                                                 dot = index + 1;
2993                                         }
2994                                 }
2995                                 index++;
2996                         }
2997                         if (name[0] != '[') {
2998                                 string substring = name.Substring(dot, index - dot);
2999
3000                                 if (type != null)
3001                                         return TypeManager.GetNestedType (type, substring);
3002
3003                                 if (resolved != null) {
3004                                         resolved = (resolved as Namespace).Lookup (ec.DeclContainer, substring, Location.Null);
3005                                         if (resolved is TypeExpr)
3006                                                 return resolved.Type;
3007
3008                                         if (resolved == null)
3009                                                 return null;
3010
3011                                         resolved.Error_UnexpectedKind (ec.DeclContainer, "type", loc);
3012                                         return typeof (UnexpectedType);
3013                                 }
3014                                 else
3015                                         return null;
3016                         }
3017                         else
3018                                 return recursive_type;
3019                         }
3020
3021                 protected override TypeExpr DoResolveAsTypeStep (IResolveContext ec)
3022                 {
3023                         Type t = TypeLookup (ec, name);
3024                         if (t == null) {
3025                                 NamespaceEntry.Error_NamespaceNotFound (loc, name);
3026                                 return null;
3027                         }
3028                         if (t == typeof(UnexpectedType))
3029                                 return null;
3030                         type = t;
3031                         return this;
3032                 }
3033
3034                 protected override void CloneTo (CloneContext clonectx, Expression target)
3035                 {
3036                         // CloneTo: Nothing, we do not keep any state on this expression
3037                 }
3038
3039                 public override string GetSignatureForError ()
3040                 {
3041                         if (type == null)
3042                                 return TypeManager.CSharpName (name);
3043
3044                         return base.GetSignatureForError ();
3045                 }
3046         }
3047
3048         /// <summary>
3049         ///   Represents an "unbound generic type", ie. typeof (Foo<>).
3050         ///   See 14.5.11.
3051         /// </summary>
3052         public class UnboundTypeExpression : TypeExpr
3053         {
3054                 MemberName name;
3055
3056                 public UnboundTypeExpression (MemberName name, Location l)
3057                 {
3058                         this.name = name;
3059                         loc = l;
3060                 }
3061
3062                 protected override void CloneTo (CloneContext clonectx, Expression target)
3063                 {
3064                         // Nothing to clone
3065                 }
3066
3067                 protected override TypeExpr DoResolveAsTypeStep (IResolveContext ec)
3068                 {
3069                         Expression expr;
3070                         if (name.Left != null) {
3071                                 Expression lexpr = name.Left.GetTypeExpression ();
3072                                 expr = new MemberAccess (lexpr, name.Basename);
3073                         } else {
3074                                 expr = new SimpleName (name.Basename, loc);
3075                         }
3076
3077                         FullNamedExpression fne = expr.ResolveAsTypeStep (ec, false);
3078                         if (fne == null)
3079                                 return null;
3080
3081                         type = fne.Type;
3082                         return new TypeExpression (type, loc);
3083                 }
3084         }
3085
3086         /// <summary>
3087         ///   This class denotes an expression which evaluates to a member
3088         ///   of a struct or a class.
3089         /// </summary>
3090         public abstract class MemberExpr : Expression
3091         {
3092                 protected bool is_base;
3093
3094                 /// <summary>
3095                 ///   The name of this member.
3096                 /// </summary>
3097                 public abstract string Name {
3098                         get;
3099                 }
3100
3101                 //
3102                 // When base.member is used
3103                 //
3104                 public bool IsBase {
3105                         get { return is_base; }
3106                         set { is_base = value; }
3107                 }
3108
3109                 /// <summary>
3110                 ///   Whether this is an instance member.
3111                 /// </summary>
3112                 public abstract bool IsInstance {
3113                         get;
3114                 }
3115
3116                 /// <summary>
3117                 ///   Whether this is a static member.
3118                 /// </summary>
3119                 public abstract bool IsStatic {
3120                         get;
3121                 }
3122
3123                 /// <summary>
3124                 ///   The type which declares this member.
3125                 /// </summary>
3126                 public abstract Type DeclaringType {
3127                         get;
3128                 }
3129
3130                 /// <summary>
3131                 ///   The instance expression associated with this member, if it's a
3132                 ///   non-static member.
3133                 /// </summary>
3134                 public Expression InstanceExpression;
3135
3136                 public static void error176 (Location loc, string name)
3137                 {
3138                         Report.Error (176, loc, "Static member `{0}' cannot be accessed " +
3139                                       "with an instance reference, qualify it with a type name instead", name);
3140                 }
3141
3142                 public static void Error_BaseAccessInExpressionTree (Location loc)
3143                 {
3144                         Report.Error (831, loc, "An expression tree may not contain a base access");
3145                 }
3146
3147                 public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
3148                 {
3149                         if (InstanceExpression != null)
3150                                 InstanceExpression.MutateHoistedGenericType (storey);
3151                 }
3152
3153                 // TODO: possible optimalization
3154                 // Cache resolved constant result in FieldBuilder <-> expression map
3155                 public virtual MemberExpr ResolveMemberAccess (EmitContext ec, Expression left, Location loc,
3156                                                                SimpleName original)
3157                 {
3158                         //
3159                         // Precondition:
3160                         //   original == null || original.Resolve (...) ==> left
3161                         //
3162
3163                         if (left is TypeExpr) {
3164                                 left = left.ResolveAsTypeTerminal (ec, true);
3165                                 if (left == null)
3166                                         return null;
3167
3168                                 if (!IsStatic) {
3169                                         SimpleName.Error_ObjectRefRequired (ec, loc, GetSignatureForError ());
3170                                         return null;
3171                                 }
3172
3173                                 return this;
3174                         }
3175
3176                         if (!IsInstance) {
3177                                 if (original != null && original.IdenticalNameAndTypeName (ec, left, loc))
3178                                         return this;
3179
3180                                 return ResolveExtensionMemberAccess (left);
3181                         }
3182
3183                         InstanceExpression = left;
3184                         return this;
3185                 }
3186
3187                 protected virtual MemberExpr ResolveExtensionMemberAccess (Expression left)
3188                 {
3189                         error176 (loc, GetSignatureForError ());
3190                         return this;
3191                 }
3192
3193                 protected void EmitInstance (EmitContext ec, bool prepare_for_load)
3194                 {
3195                         if (IsStatic)
3196                                 return;
3197
3198                         if (InstanceExpression == EmptyExpression.Null) {
3199                                 SimpleName.Error_ObjectRefRequired (ec, loc, GetSignatureForError ());
3200                                 return;
3201                         }
3202
3203                         if (InstanceExpression.Type.IsValueType) {
3204                                 if (InstanceExpression is IMemoryLocation) {
3205                                         ((IMemoryLocation) InstanceExpression).AddressOf (ec, AddressOp.LoadStore);
3206                                 } else {
3207                                         LocalTemporary t = new LocalTemporary (InstanceExpression.Type);
3208                                         InstanceExpression.Emit (ec);
3209                                         t.Store (ec);
3210                                         t.AddressOf (ec, AddressOp.Store);
3211                                 }
3212                         } else
3213                                 InstanceExpression.Emit (ec);
3214
3215                         if (prepare_for_load)
3216                                 ec.ig.Emit (OpCodes.Dup);
3217                 }
3218
3219                 public virtual void SetTypeArguments (TypeArguments ta)
3220                 {
3221                         // TODO: need to get correct member type
3222                         Report.Error (307, loc, "The property `{0}' cannot be used with type arguments",
3223                                 GetSignatureForError ());
3224                 }
3225         }
3226
3227         ///
3228         /// Represents group of extension methods
3229         ///
3230         public class ExtensionMethodGroupExpr : MethodGroupExpr
3231         {
3232                 readonly NamespaceEntry namespace_entry;
3233                 public Expression ExtensionExpression;
3234                 Argument extension_argument;
3235
3236                 public ExtensionMethodGroupExpr (ArrayList list, NamespaceEntry n, Type extensionType, Location l)
3237                         : base (list, extensionType, l)
3238                 {
3239                         this.namespace_entry = n;
3240                 }
3241
3242                 public override bool IsStatic {
3243                         get { return true; }
3244                 }
3245
3246                 public bool IsTopLevel {
3247                         get { return namespace_entry == null; }
3248                 }
3249
3250                 public override void EmitArguments (EmitContext ec, ArrayList arguments)
3251                 {
3252                         if (arguments == null)
3253                                 arguments = new ArrayList (1);
3254                         arguments.Insert (0, extension_argument);
3255                         base.EmitArguments (ec, arguments);
3256                 }
3257
3258                 public override void EmitCall (EmitContext ec, ArrayList arguments)
3259                 {
3260                         if (arguments == null)
3261                                 arguments = new ArrayList (1);
3262                         arguments.Insert (0, extension_argument);
3263                         base.EmitCall (ec, arguments);
3264                 }
3265
3266                 public override MethodGroupExpr OverloadResolve (EmitContext ec, ref ArrayList arguments, bool may_fail, Location loc)
3267                 {
3268                         if (arguments == null)
3269                                 arguments = new ArrayList (1);
3270
3271                         arguments.Insert (0, new Argument (ExtensionExpression));
3272                         MethodGroupExpr mg = ResolveOverloadExtensions (ec, arguments, namespace_entry, loc);
3273
3274                         // Store resolved argument and restore original arguments
3275                         if (mg != null)
3276                                 ((ExtensionMethodGroupExpr)mg).extension_argument = (Argument)arguments [0];
3277                         arguments.RemoveAt (0);
3278
3279                         return mg;
3280                 }
3281
3282                 MethodGroupExpr ResolveOverloadExtensions (EmitContext ec, ArrayList arguments, NamespaceEntry ns, Location loc)
3283                 {
3284                         // Use normal resolve rules
3285                         MethodGroupExpr mg = base.OverloadResolve (ec, ref arguments, ns != null, loc);
3286                         if (mg != null)
3287                                 return mg;
3288
3289                         if (ns == null)
3290                                 return null;
3291
3292                         // Search continues
3293                         ExtensionMethodGroupExpr e = ns.LookupExtensionMethod (type, null, Name, loc);
3294                         if (e == null)
3295                                 return base.OverloadResolve (ec, ref arguments, false, loc);
3296
3297                         e.ExtensionExpression = ExtensionExpression;
3298                         e.SetTypeArguments (type_arguments);
3299                         return e.ResolveOverloadExtensions (ec, arguments, e.namespace_entry, loc);
3300                 }
3301         }
3302
3303         /// <summary>
3304         ///   MethodGroupExpr represents a group of method candidates which
3305         ///   can be resolved to the best method overload
3306         /// </summary>
3307         public class MethodGroupExpr : MemberExpr
3308         {
3309                 public interface IErrorHandler
3310                 {
3311                         bool NoExactMatch (EmitContext ec, MethodBase method);
3312                 }
3313
3314                 public IErrorHandler CustomErrorHandler;
3315                 public MethodBase [] Methods;
3316                 MethodBase best_candidate;
3317                 // TODO: make private
3318                 public TypeArguments type_arguments;
3319                 bool identical_type_name;
3320                 Type delegate_type;
3321
3322                 public MethodGroupExpr (MemberInfo [] mi, Type type, Location l)
3323                         : this (type, l)
3324                 {
3325                         Methods = new MethodBase [mi.Length];
3326                         mi.CopyTo (Methods, 0);
3327                 }
3328
3329                 public MethodGroupExpr (ArrayList list, Type type, Location l)
3330                         : this (type, l)
3331                 {
3332                         try {
3333                                 Methods = (MethodBase[])list.ToArray (typeof (MethodBase));
3334                         } catch {
3335                                 foreach (MemberInfo m in list){
3336                                         if (!(m is MethodBase)){
3337                                                 Console.WriteLine ("Name " + m.Name);
3338                                                 Console.WriteLine ("Found a: " + m.GetType ().FullName);
3339                                         }
3340                                 }
3341                                 throw;
3342                         }
3343
3344
3345                 }
3346
3347                 protected MethodGroupExpr (Type type, Location loc)
3348                 {
3349                         this.loc = loc;
3350                         eclass = ExprClass.MethodGroup;
3351                         this.type = type;
3352                 }
3353
3354                 public override Type DeclaringType {
3355                         get {
3356                                 //
3357                                 // We assume that the top-level type is in the end
3358                                 //
3359                                 return Methods [Methods.Length - 1].DeclaringType;
3360                                 //return Methods [0].DeclaringType;
3361                         }
3362                 }
3363
3364                 public Type DelegateType {
3365                         set {
3366                                 delegate_type = value;
3367                         }
3368                 }
3369
3370                 public bool IdenticalTypeName {
3371                         get {
3372                                 return identical_type_name;
3373                         }
3374
3375                         set {
3376                                 identical_type_name = value;
3377                         }
3378                 }
3379
3380                 public override string GetSignatureForError ()
3381                 {
3382                         if (best_candidate != null)
3383                                 return TypeManager.CSharpSignature (best_candidate);
3384
3385                         return TypeManager.CSharpSignature (Methods [0]);
3386                 }
3387
3388                 public override string Name {
3389                         get {
3390                                 return Methods [0].Name;
3391                         }
3392                 }
3393
3394                 public override bool IsInstance {
3395                         get {
3396                                 if (best_candidate != null)
3397                                         return !best_candidate.IsStatic;
3398
3399                                 foreach (MethodBase mb in Methods)
3400                                         if (!mb.IsStatic)
3401                                                 return true;
3402
3403                                 return false;
3404                         }
3405                 }
3406
3407                 public override bool IsStatic {
3408                         get {
3409                                 if (best_candidate != null)
3410                                         return best_candidate.IsStatic;
3411
3412                                 foreach (MethodBase mb in Methods)
3413                                         if (mb.IsStatic)
3414                                                 return true;
3415
3416                                 return false;
3417                         }
3418                 }
3419
3420                 public static explicit operator ConstructorInfo (MethodGroupExpr mg)
3421                 {
3422                         return (ConstructorInfo)mg.best_candidate;
3423                 }
3424
3425                 public static explicit operator MethodInfo (MethodGroupExpr mg)
3426                 {
3427                         return (MethodInfo)mg.best_candidate;
3428                 }
3429
3430                 //
3431                 //  7.4.3.3  Better conversion from expression
3432                 //  Returns :   1    if a->p is better,
3433                 //              2    if a->q is better,
3434                 //              0 if neither is better
3435                 //
3436                 static int BetterExpressionConversion (EmitContext ec, Argument a, Type p, Type q)
3437                 {
3438                         Type argument_type = TypeManager.TypeToCoreType (a.Type);
3439                         if (argument_type == TypeManager.anonymous_method_type && RootContext.Version > LanguageVersion.ISO_2) {
3440                                 //
3441                                 // Uwrap delegate from Expression<T>
3442                                 //
3443                                 if (TypeManager.DropGenericTypeArguments (p) == TypeManager.expression_type) {
3444                                         p = TypeManager.GetTypeArguments (p) [0];
3445                                 }
3446                                 if (TypeManager.DropGenericTypeArguments (q) == TypeManager.expression_type) {
3447                                         q = TypeManager.GetTypeArguments (q) [0];
3448                                 }
3449
3450                                 p = Delegate.GetInvokeMethod (null, p).ReturnType;
3451                                 q = Delegate.GetInvokeMethod (null, q).ReturnType;
3452                         } else {
3453                                 if (argument_type == p)
3454                                         return 1;
3455
3456                                 if (argument_type == q)
3457                                         return 2;
3458                         }
3459
3460                         return BetterTypeConversion (ec, p, q);
3461                 }
3462
3463                 //
3464                 // 7.4.3.4  Better conversion from type
3465                 //
3466                 public static int BetterTypeConversion (EmitContext ec, Type p, Type q)
3467                 {
3468                         if (p == null || q == null)
3469                                 throw new InternalErrorException ("BetterTypeConversion got a null conversion");
3470
3471                         if (p == TypeManager.int32_type) {
3472                                 if (q == TypeManager.uint32_type || q == TypeManager.uint64_type)
3473                                         return 1;
3474                         } else if (p == TypeManager.int64_type) {
3475                                 if (q == TypeManager.uint64_type)
3476                                         return 1;
3477                         } else if (p == TypeManager.sbyte_type) {
3478                                 if (q == TypeManager.byte_type || q == TypeManager.ushort_type ||
3479                                         q == TypeManager.uint32_type || q == TypeManager.uint64_type)
3480                                         return 1;
3481                         } else if (p == TypeManager.short_type) {
3482                                 if (q == TypeManager.ushort_type || q == TypeManager.uint32_type ||
3483                                         q == TypeManager.uint64_type)
3484                                         return 1;
3485                         }
3486
3487                         if (q == TypeManager.int32_type) {
3488                                 if (p == TypeManager.uint32_type || p == TypeManager.uint64_type)
3489                                         return 2;
3490                         } if (q == TypeManager.int64_type) {
3491                                 if (p == TypeManager.uint64_type)
3492                                         return 2;
3493                         } else if (q == TypeManager.sbyte_type) {
3494                                 if (p == TypeManager.byte_type || p == TypeManager.ushort_type ||
3495                                         p == TypeManager.uint32_type || p == TypeManager.uint64_type)
3496                                         return 2;
3497                         } if (q == TypeManager.short_type) {
3498                                 if (p == TypeManager.ushort_type || p == TypeManager.uint32_type ||
3499                                         p == TypeManager.uint64_type)
3500                                         return 2;
3501                         }
3502
3503                         // TODO: this is expensive
3504                         Expression p_tmp = new EmptyExpression (p);
3505                         Expression q_tmp = new EmptyExpression (q);
3506
3507                         bool p_to_q = Convert.ImplicitConversionExists (ec, p_tmp, q);
3508                         bool q_to_p = Convert.ImplicitConversionExists (ec, q_tmp, p);
3509
3510                         if (p_to_q && !q_to_p)
3511                                 return 1;
3512
3513                         if (q_to_p && !p_to_q)
3514                                 return 2;
3515
3516                         return 0;
3517                 }
3518
3519                 /// <summary>
3520                 ///   Determines "Better function" between candidate
3521                 ///   and the current best match
3522                 /// </summary>
3523                 /// <remarks>
3524                 ///    Returns a boolean indicating :
3525                 ///     false if candidate ain't better
3526                 ///     true  if candidate is better than the current best match
3527                 /// </remarks>
3528                 static bool BetterFunction (EmitContext ec, ArrayList args, int argument_count,
3529                         MethodBase candidate, bool candidate_params,
3530                         MethodBase best, bool best_params)
3531                 {
3532                         ParameterData candidate_pd = TypeManager.GetParameterData (candidate);
3533                         ParameterData best_pd = TypeManager.GetParameterData (best);
3534
3535                         bool better_at_least_one = false;
3536                         bool same = true;
3537                         for (int j = 0, c_idx = 0, b_idx = 0; j < argument_count; ++j, ++c_idx, ++b_idx)
3538                         {
3539                                 Argument a = (Argument) args [j];
3540
3541                                 Type ct = TypeManager.TypeToCoreType (candidate_pd.ParameterType (c_idx));
3542                                 Type bt = TypeManager.TypeToCoreType (best_pd.ParameterType (b_idx));
3543
3544                                 if (candidate_params && candidate_pd.ParameterModifier (c_idx) == Parameter.Modifier.PARAMS)
3545                                 {
3546                                         ct = TypeManager.GetElementType (ct);
3547                                         --c_idx;
3548                                 }
3549
3550                                 if (best_params && best_pd.ParameterModifier (b_idx) == Parameter.Modifier.PARAMS)
3551                                 {
3552                                         bt = TypeManager.GetElementType (bt);
3553                                         --b_idx;
3554                                 }
3555
3556                                 if (ct.Equals (bt))
3557                                         continue;
3558
3559                                 same = false;
3560                                 int result = BetterExpressionConversion (ec, a, ct, bt);
3561
3562                                 // for each argument, the conversion to 'ct' should be no worse than
3563                                 // the conversion to 'bt'.
3564                                 if (result == 2)
3565                                         return false;
3566
3567                                 // for at least one argument, the conversion to 'ct' should be better than
3568                                 // the conversion to 'bt'.
3569                                 if (result != 0)
3570                                         better_at_least_one = true;
3571                         }
3572
3573                         if (better_at_least_one)
3574                                 return true;
3575
3576                         //
3577                         // This handles the case
3578                         //
3579                         //   Add (float f1, float f2, float f3);
3580                         //   Add (params decimal [] foo);
3581                         //
3582                         // The call Add (3, 4, 5) should be ambiguous.  Without this check, the
3583                         // first candidate would've chosen as better.
3584                         //
3585                         if (!same)
3586                                 return false;
3587
3588                         //
3589                         // The two methods have equal parameter types.  Now apply tie-breaking rules
3590                         //
3591                         if (TypeManager.IsGenericMethod (best) && !TypeManager.IsGenericMethod (candidate))
3592                                 return true;
3593                         if (!TypeManager.IsGenericMethod (best) && TypeManager.IsGenericMethod (candidate))
3594                                 return false;
3595
3596                         //
3597                         // This handles the following cases:
3598                         //
3599                         //   Trim () is better than Trim (params char[] chars)
3600                         //   Concat (string s1, string s2, string s3) is better than
3601                         //     Concat (string s1, params string [] srest)
3602                         //   Foo (int, params int [] rest) is better than Foo (params int [] rest)
3603                         //
3604                         if (!candidate_params && best_params)
3605                                 return true;
3606                         if (candidate_params && !best_params)
3607                                 return false;
3608
3609                         int candidate_param_count = candidate_pd.Count;
3610                         int best_param_count = best_pd.Count;
3611
3612                         if (candidate_param_count != best_param_count)
3613                                 // can only happen if (candidate_params && best_params)
3614                                 return candidate_param_count > best_param_count;
3615
3616                         //
3617                         // now, both methods have the same number of parameters, and the parameters have the same types
3618                         // Pick the "more specific" signature
3619                         //
3620
3621                         MethodBase orig_candidate = TypeManager.DropGenericMethodArguments (candidate);
3622                         MethodBase orig_best = TypeManager.DropGenericMethodArguments (best);
3623
3624                         ParameterData orig_candidate_pd = TypeManager.GetParameterData (orig_candidate);
3625                         ParameterData orig_best_pd = TypeManager.GetParameterData (orig_best);
3626
3627                         bool specific_at_least_once = false;
3628                         for (int j = 0; j < candidate_param_count; ++j)
3629                         {
3630                                 Type ct = TypeManager.TypeToCoreType (orig_candidate_pd.ParameterType (j));
3631                                 Type bt = TypeManager.TypeToCoreType (orig_best_pd.ParameterType (j));
3632                                 if (ct.Equals (bt))
3633                                         continue;
3634                                 Type specific = MoreSpecific (ct, bt);
3635                                 if (specific == bt)
3636                                         return false;
3637                                 if (specific == ct)
3638                                         specific_at_least_once = true;
3639                         }
3640
3641                         if (specific_at_least_once)
3642                                 return true;
3643
3644                         // FIXME: handle lifted operators
3645                         // ...
3646
3647                         return false;
3648                 }
3649
3650                 protected override MemberExpr ResolveExtensionMemberAccess (Expression left)
3651                 {
3652                         if (!IsStatic)
3653                                 return base.ResolveExtensionMemberAccess (left);
3654
3655                         //
3656                         // When left side is an expression and at least one candidate method is
3657                         // static, it can be extension method
3658                         //
3659                         InstanceExpression = left;
3660                         return this;
3661                 }
3662
3663                 public override MemberExpr ResolveMemberAccess (EmitContext ec, Expression left, Location loc,
3664                                                                 SimpleName original)
3665                 {
3666                         if (!(left is TypeExpr) &&
3667                             original != null && original.IdenticalNameAndTypeName (ec, left, loc))
3668                                 IdenticalTypeName = true;
3669
3670                         return base.ResolveMemberAccess (ec, left, loc, original);
3671                 }
3672
3673                 public override Expression CreateExpressionTree (EmitContext ec)
3674                 {
3675                         if (best_candidate == null) {
3676                                 Report.Error (1953, loc, "An expression tree cannot contain an expression with method group");
3677                                 return null;
3678                         }
3679
3680                         if (best_candidate.IsConstructor)
3681                                 return new TypeOfConstructorInfo (best_candidate, loc);
3682
3683                         IMethodData md = TypeManager.GetMethod (best_candidate);
3684                         if (md != null && md.IsExcluded ())
3685                                 Report.Error (765, loc,
3686                                         "Partial methods with only a defining declaration or removed conditional methods cannot be used in an expression tree");
3687
3688                         return new TypeOfMethodInfo (best_candidate, loc);
3689                 }
3690
3691                 override public Expression DoResolve (EmitContext ec)
3692                 {
3693                         if (InstanceExpression != null) {
3694                                 InstanceExpression = InstanceExpression.DoResolve (ec);
3695                                 if (InstanceExpression == null)
3696                                         return null;
3697                         }
3698
3699                         return this;
3700                 }
3701
3702                 public void ReportUsageError ()
3703                 {
3704                         Report.Error (654, loc, "Method `" + DeclaringType + "." +
3705                                       Name + "()' is referenced without parentheses");
3706                 }
3707
3708                 override public void Emit (EmitContext ec)
3709                 {
3710                         ReportUsageError ();
3711                 }
3712
3713                 public virtual void EmitArguments (EmitContext ec, ArrayList arguments)
3714                 {
3715                         Invocation.EmitArguments (ec, arguments, false, null);
3716                 }
3717
3718                 public virtual void EmitCall (EmitContext ec, ArrayList arguments)
3719                 {
3720                         Invocation.EmitCall (ec, IsBase, InstanceExpression, best_candidate, arguments, loc);
3721                 }
3722
3723                 protected virtual void Error_InvalidArguments (EmitContext ec, Location loc, int idx, MethodBase method,
3724                                                                                                         Argument a, ParameterData expected_par, Type paramType)
3725                 {
3726                         if (a is CollectionElementInitializer.ElementInitializerArgument) {
3727                                 Report.SymbolRelatedToPreviousError (method);
3728                                 if ((expected_par.ParameterModifier (idx) & 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                                 Report.Error (1502, loc, "The best overloaded method match for `{0}' has some invalid arguments",
3738                                                   TypeManager.CSharpSignature (method));
3739                         } else
3740                                 Report.Error (1594, loc, "Delegate `{0}' has some invalid arguments",
3741                                         TypeManager.CSharpName (delegate_type));
3742
3743                         Parameter.Modifier mod = expected_par.ParameterModifier (idx);
3744
3745                         string index = (idx + 1).ToString ();
3746                         if (((mod & (Parameter.Modifier.REF | Parameter.Modifier.OUT)) ^
3747                                 (a.Modifier & (Parameter.Modifier.REF | Parameter.Modifier.OUT))) != 0) {
3748                                 if ((mod & Parameter.Modifier.ISBYREF) == 0)
3749                                         Report.Error (1615, loc, "Argument `{0}' should not be passed with the `{1}' keyword",
3750                                                 index, Parameter.GetModifierSignature (a.Modifier));
3751                                 else
3752                                         Report.Error (1620, loc, "Argument `{0}' must be passed with the `{1}' keyword",
3753                                                 index, Parameter.GetModifierSignature (mod));
3754                         } else {
3755                                 string p1 = a.GetSignatureForError ();
3756                                 string p2 = TypeManager.CSharpName (paramType);
3757
3758                                 if (p1 == p2) {
3759                                         Report.ExtraInformation (loc, "(equally named types possibly from different assemblies in previous ");
3760                                         Report.SymbolRelatedToPreviousError (a.Expr.Type);
3761                                         Report.SymbolRelatedToPreviousError (paramType);
3762                                 }
3763                                 Report.Error (1503, loc, "Argument {0}: Cannot convert type `{1}' to `{2}'", index, p1, p2);
3764                         }
3765                 }
3766
3767                 public override void Error_ValueCannotBeConverted (EmitContext ec, Location loc, Type target, bool expl)
3768                 {
3769                         Report.Error (428, loc, "Cannot convert method group `{0}' to non-delegate type `{1}'. Consider using parentheses to invoke the method",
3770                                 Name, TypeManager.CSharpName (target));
3771                 }
3772
3773                 protected virtual int GetApplicableParametersCount (MethodBase method, ParameterData parameters)
3774                 {
3775                         return parameters.Count;
3776                 }
3777
3778                 public static bool IsAncestralType (Type first_type, Type second_type)
3779                 {
3780                         return first_type != second_type &&
3781                                 (TypeManager.IsSubclassOf (second_type, first_type) ||
3782                                 TypeManager.ImplementsInterface (second_type, first_type));
3783                 }
3784
3785                 ///
3786                 /// Determines if the candidate method is applicable (section 14.4.2.1)
3787                 /// to the given set of arguments
3788                 /// A return value rates candidate method compatibility,
3789                 /// 0 = the best, int.MaxValue = the worst
3790                 ///
3791                 public int IsApplicable (EmitContext ec,
3792                                                  ArrayList arguments, int arg_count, ref MethodBase method, ref bool params_expanded_form)
3793                 {
3794                         MethodBase candidate = method;
3795
3796                         ParameterData pd = TypeManager.GetParameterData (candidate);
3797                         int param_count = GetApplicableParametersCount (candidate, pd);
3798
3799                         if (arg_count != param_count) {
3800                                 if (!pd.HasParams)
3801                                         return int.MaxValue - 10000 + Math.Abs (arg_count - param_count);
3802                                 if (arg_count < param_count - 1)
3803                                         return int.MaxValue - 10000 + Math.Abs (arg_count - param_count);
3804                         }
3805
3806 #if GMCS_SOURCE
3807                         //
3808                         // 1. Handle generic method using type arguments when specified or type inference
3809                         //
3810                         if (TypeManager.IsGenericMethod (candidate)) {
3811                                 if (type_arguments != null) {
3812                                         Type [] g_args = candidate.GetGenericArguments ();
3813                                         if (g_args.Length != type_arguments.Count)
3814                                                 return int.MaxValue - 20000 + Math.Abs (type_arguments.Count - g_args.Length);
3815
3816                                         // TODO: Don't create new method, create Parameters only
3817                                         method = ((MethodInfo) candidate).MakeGenericMethod (type_arguments.Arguments);
3818                                         candidate = method;
3819                                         pd = TypeManager.GetParameterData (candidate);
3820                                 } else {
3821                                         int score = TypeManager.InferTypeArguments (ec, arguments, ref candidate);
3822                                         if (score != 0)
3823                                                 return score - 20000;
3824
3825                                         if (TypeManager.IsGenericMethodDefinition (candidate))
3826                                                 throw new InternalErrorException ("A generic method `{0}' definition took part in overload resolution",
3827                                                         TypeManager.CSharpSignature (candidate));
3828
3829                                         pd = TypeManager.GetParameterData (candidate);
3830                                 }
3831                         } else {
3832                                 if (type_arguments != null)
3833                                         return int.MaxValue - 15000;
3834                         }
3835 #endif
3836
3837                         //
3838                         // 2. Each argument has to be implicitly convertible to method parameter
3839                         //
3840                         method = candidate;
3841                         Parameter.Modifier p_mod = 0;
3842                         Type pt = null;
3843                         for (int i = 0; i < arg_count; i++) {
3844                                 Argument a = (Argument) arguments [i];
3845                                 Parameter.Modifier a_mod = a.Modifier &
3846                                         ~(Parameter.Modifier.OUTMASK | Parameter.Modifier.REFMASK);
3847
3848                                 if (p_mod != Parameter.Modifier.PARAMS) {
3849                                         p_mod = pd.ParameterModifier (i) & ~(Parameter.Modifier.OUTMASK | Parameter.Modifier.REFMASK);
3850
3851                                         if (p_mod == Parameter.Modifier.ARGLIST) {
3852                                                 if (a.Type == TypeManager.runtime_argument_handle_type)
3853                                                         continue;
3854
3855                                                 p_mod = 0;
3856                                         }
3857
3858                                         pt = pd.ParameterType (i);
3859                                 } else {
3860                                         params_expanded_form = true;
3861                                 }
3862
3863                                 int score = 1;
3864                                 if (!params_expanded_form)
3865                                         score = IsArgumentCompatible (ec, a_mod, a, p_mod & ~Parameter.Modifier.PARAMS, pt);
3866
3867                                 if (score != 0 && (p_mod & Parameter.Modifier.PARAMS) != 0) {
3868                                         // It can be applicable in expanded form
3869                                         score = IsArgumentCompatible (ec, a_mod, a, 0, pt.GetElementType ());
3870                                         if (score == 0)
3871                                                 params_expanded_form = true;
3872                                 }
3873
3874                                 if (score != 0) {
3875                                         if (params_expanded_form)
3876                                                 ++score;
3877                                         return (arg_count - i) * 2 + score;
3878                                 }
3879                         }
3880
3881                         if (arg_count != param_count)
3882                                 params_expanded_form = true;
3883
3884                         return 0;
3885                 }
3886
3887                 int IsArgumentCompatible (EmitContext ec, Parameter.Modifier arg_mod, Argument argument, Parameter.Modifier param_mod, Type parameter)
3888                 {
3889                         //
3890                         // Types have to be identical when ref or out modifer is used
3891                         //
3892                         if (arg_mod != 0 || param_mod != 0) {
3893                                 if (TypeManager.HasElementType (parameter))
3894                                         parameter = parameter.GetElementType ();
3895
3896                                 Type a_type = argument.Type;
3897                                 if (TypeManager.HasElementType (a_type))
3898                                         a_type = a_type.GetElementType ();
3899
3900                                 if (a_type != parameter)
3901                                         return 2;
3902
3903                                 return 0;
3904                         }
3905
3906                         if (delegate_type != null ?
3907                                 !Delegate.IsTypeCovariant (argument.Expr, parameter) :
3908                                 !Convert.ImplicitConversionExists (ec, argument.Expr, parameter))
3909                                 return 2;
3910
3911                         if (arg_mod != param_mod)
3912                                 return 1;
3913
3914                         return 0;
3915                 }
3916
3917                 public static bool IsOverride (MethodBase cand_method, MethodBase base_method)
3918                 {
3919                         if (!IsAncestralType (base_method.DeclaringType, cand_method.DeclaringType))
3920                                 return false;
3921
3922                         ParameterData cand_pd = TypeManager.GetParameterData (cand_method);
3923                         ParameterData base_pd = TypeManager.GetParameterData (base_method);
3924
3925                         if (cand_pd.Count != base_pd.Count)
3926                                 return false;
3927
3928                         for (int j = 0; j < cand_pd.Count; ++j)
3929                         {
3930                                 Parameter.Modifier cm = cand_pd.ParameterModifier (j);
3931                                 Parameter.Modifier bm = base_pd.ParameterModifier (j);
3932                                 Type ct = TypeManager.TypeToCoreType (cand_pd.ParameterType (j));
3933                                 Type bt = TypeManager.TypeToCoreType (base_pd.ParameterType (j));
3934
3935                                 if (cm != bm || ct != bt)
3936                                         return false;
3937                         }
3938
3939                         return true;
3940                 }
3941
3942                 public static MethodGroupExpr MakeUnionSet (Expression mg1, Expression mg2, Location loc)
3943                 {
3944                         MemberInfo [] miset;
3945                         MethodGroupExpr union;
3946
3947                         if (mg1 == null) {
3948                                 if (mg2 == null)
3949                                         return null;
3950                                 return (MethodGroupExpr) mg2;
3951                         } else {
3952                                 if (mg2 == null)
3953                                         return (MethodGroupExpr) mg1;
3954                         }
3955
3956                         MethodGroupExpr left_set = null, right_set = null;
3957                         int length1 = 0, length2 = 0;
3958
3959                         left_set = (MethodGroupExpr) mg1;
3960                         length1 = left_set.Methods.Length;
3961
3962                         right_set = (MethodGroupExpr) mg2;
3963                         length2 = right_set.Methods.Length;
3964
3965                         ArrayList common = new ArrayList ();
3966
3967                         foreach (MethodBase r in right_set.Methods){
3968                                 if (TypeManager.ArrayContainsMethod (left_set.Methods, r))
3969                                         common.Add (r);
3970                         }
3971
3972                         miset = new MemberInfo [length1 + length2 - common.Count];
3973                         left_set.Methods.CopyTo (miset, 0);
3974
3975                         int k = length1;
3976
3977                         foreach (MethodBase r in right_set.Methods) {
3978                                 if (!common.Contains (r))
3979                                         miset [k++] = r;
3980                         }
3981
3982                         union = new MethodGroupExpr (miset, mg1.Type, loc);
3983
3984                         return union;
3985                 }
3986
3987                 static Type MoreSpecific (Type p, Type q)
3988                 {
3989                         if (TypeManager.IsGenericParameter (p) && !TypeManager.IsGenericParameter (q))
3990                                 return q;
3991                         if (!TypeManager.IsGenericParameter (p) && TypeManager.IsGenericParameter (q))
3992                                 return p;
3993
3994                         if (TypeManager.HasElementType (p))
3995                         {
3996                                 Type pe = TypeManager.GetElementType (p);
3997                                 Type qe = TypeManager.GetElementType (q);
3998                                 Type specific = MoreSpecific (pe, qe);
3999                                 if (specific == pe)
4000                                         return p;
4001                                 if (specific == qe)
4002                                         return q;
4003                         }
4004                         else if (TypeManager.IsGenericType (p))
4005                         {
4006                                 Type[] pargs = TypeManager.GetTypeArguments (p);
4007                                 Type[] qargs = TypeManager.GetTypeArguments (q);
4008
4009                                 bool p_specific_at_least_once = false;
4010                                 bool q_specific_at_least_once = false;
4011
4012                                 for (int i = 0; i < pargs.Length; i++)
4013                                 {
4014                                         Type specific = MoreSpecific (pargs [i], qargs [i]);
4015                                         if (specific == pargs [i])
4016                                                 p_specific_at_least_once = true;
4017                                         if (specific == qargs [i])
4018                                                 q_specific_at_least_once = true;
4019                                 }
4020
4021                                 if (p_specific_at_least_once && !q_specific_at_least_once)
4022                                         return p;
4023                                 if (!p_specific_at_least_once && q_specific_at_least_once)
4024                                         return q;
4025                         }
4026
4027                         return null;
4028                 }
4029
4030                 public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
4031                 {
4032                         base.MutateHoistedGenericType (storey);
4033
4034                         MethodInfo mi = best_candidate as MethodInfo;
4035                         if (mi != null) {
4036                                 best_candidate = storey.MutateGenericMethod (mi);
4037                                 return;
4038                         }
4039
4040                         best_candidate = storey.MutateConstructor ((ConstructorInfo) this);
4041                 }
4042
4043                 /// <summary>
4044                 ///   Find the Applicable Function Members (7.4.2.1)
4045                 ///
4046                 ///   me: Method Group expression with the members to select.
4047                 ///       it might contain constructors or methods (or anything
4048                 ///       that maps to a method).
4049                 ///
4050                 ///   Arguments: ArrayList containing resolved Argument objects.
4051                 ///
4052                 ///   loc: The location if we want an error to be reported, or a Null
4053                 ///        location for "probing" purposes.
4054                 ///
4055                 ///   Returns: The MethodBase (either a ConstructorInfo or a MethodInfo)
4056                 ///            that is the best match of me on Arguments.
4057                 ///
4058                 /// </summary>
4059                 public virtual MethodGroupExpr OverloadResolve (EmitContext ec, ref ArrayList Arguments,
4060                         bool may_fail, Location loc)
4061                 {
4062                         bool method_params = false;
4063                         Type applicable_type = null;
4064                         int arg_count = 0;
4065                         ArrayList candidates = new ArrayList (2);
4066                         ArrayList candidate_overrides = null;
4067
4068                         //
4069                         // Used to keep a map between the candidate
4070                         // and whether it is being considered in its
4071                         // normal or expanded form
4072                         //
4073                         // false is normal form, true is expanded form
4074                         //
4075                         Hashtable candidate_to_form = null;
4076
4077                         if (Arguments != null)
4078                                 arg_count = Arguments.Count;
4079
4080                         if (RootContext.Version == LanguageVersion.ISO_1 && Name == "Invoke" && TypeManager.IsDelegateType (DeclaringType)) {
4081                                 if (!may_fail)
4082                                         Report.Error (1533, loc, "Invoke cannot be called directly on a delegate");
4083                                 return null;
4084                         }
4085
4086                         int nmethods = Methods.Length;
4087
4088                         if (!IsBase) {
4089                                 //
4090                                 // Methods marked 'override' don't take part in 'applicable_type'
4091                                 // computation, nor in the actual overload resolution.
4092                                 // However, they still need to be emitted instead of a base virtual method.
4093                                 // So, we salt them away into the 'candidate_overrides' array.
4094                                 //
4095                                 // In case of reflected methods, we replace each overriding method with
4096                                 // its corresponding base virtual method.  This is to improve compatibility
4097                                 // with non-C# libraries which change the visibility of overrides (#75636)
4098                                 //
4099                                 int j = 0;
4100                                 for (int i = 0; i < Methods.Length; ++i) {
4101                                         MethodBase m = Methods [i];
4102                                         if (TypeManager.IsOverride (m)) {
4103                                                 if (candidate_overrides == null)
4104                                                         candidate_overrides = new ArrayList ();
4105                                                 candidate_overrides.Add (m);
4106                                                 m = TypeManager.TryGetBaseDefinition (m);
4107                                         }
4108                                         if (m != null)
4109                                                 Methods [j++] = m;
4110                                 }
4111                                 nmethods = j;
4112                         }
4113
4114                         //
4115                         // Enable message recording, it's used mainly by lambda expressions
4116                         //
4117                         Report.IMessageRecorder msg_recorder = new Report.MessageRecorder ();
4118                         Report.IMessageRecorder prev_recorder = Report.SetMessageRecorder (msg_recorder);
4119
4120                         //
4121                         // First we construct the set of applicable methods
4122                         //
4123                         bool is_sorted = true;
4124                         int best_candidate_rate = int.MaxValue;
4125                         for (int i = 0; i < nmethods; i++) {
4126                                 Type decl_type = Methods [i].DeclaringType;
4127
4128                                 //
4129                                 // If we have already found an applicable method
4130                                 // we eliminate all base types (Section 14.5.5.1)
4131                                 //
4132                                 if (applicable_type != null && IsAncestralType (decl_type, applicable_type))
4133                                         continue;
4134
4135                                 //
4136                                 // Check if candidate is applicable (section 14.4.2.1)
4137                                 //
4138                                 bool params_expanded_form = false;
4139                                 int candidate_rate = IsApplicable (ec, Arguments, arg_count, ref Methods [i], ref params_expanded_form);
4140
4141                                 if (candidate_rate < best_candidate_rate) {
4142                                         best_candidate_rate = candidate_rate;
4143                                         best_candidate = Methods [i];
4144                                 }
4145
4146                                 if (params_expanded_form) {
4147                                         if (candidate_to_form == null)
4148                                                 candidate_to_form = new PtrHashtable ();
4149                                         MethodBase candidate = Methods [i];
4150                                         candidate_to_form [candidate] = candidate;
4151                                 }
4152
4153                                 if (candidate_rate != 0) {
4154                                         if (msg_recorder != null)
4155                                                 msg_recorder.EndSession ();
4156                                         continue;
4157                                 }
4158
4159                                 msg_recorder = null;
4160                                 candidates.Add (Methods [i]);
4161
4162                                 if (applicable_type == null)
4163                                         applicable_type = decl_type;
4164                                 else if (applicable_type != decl_type) {
4165                                         is_sorted = false;
4166                                         if (IsAncestralType (applicable_type, decl_type))
4167                                                 applicable_type = decl_type;
4168                                 }
4169                         }
4170
4171                         Report.SetMessageRecorder (prev_recorder);
4172                         if (msg_recorder != null && msg_recorder.PrintMessages ())
4173                                 return null;
4174
4175                         int candidate_top = candidates.Count;
4176
4177                         if (applicable_type == null) {
4178                                 //
4179                                 // When we found a top level method which does not match and it's
4180                                 // not an extension method. We start extension methods lookup from here
4181                                 //
4182                                 if (InstanceExpression != null) {
4183                                         ExtensionMethodGroupExpr ex_method_lookup = ec.TypeContainer.LookupExtensionMethod (type, Name, loc);
4184                                         if (ex_method_lookup != null) {
4185                                                 ex_method_lookup.ExtensionExpression = InstanceExpression;
4186                                                 ex_method_lookup.SetTypeArguments (type_arguments);
4187                                                 return ex_method_lookup.OverloadResolve (ec, ref Arguments, may_fail, loc);
4188                                         }
4189                                 }
4190
4191                                 if (may_fail)
4192                                         return null;
4193
4194                                 //
4195                                 // Okay so we have failed to find exact match so we
4196                                 // return error info about the closest match
4197                                 //
4198                                 if (best_candidate != null) {
4199                                         if (CustomErrorHandler != null) {
4200                                                 if (CustomErrorHandler.NoExactMatch (ec, best_candidate))
4201                                                         return null;
4202                                         }
4203
4204                                         ParameterData pd = TypeManager.GetParameterData (best_candidate);
4205                                         bool cand_params = candidate_to_form != null && candidate_to_form.Contains (best_candidate);
4206                                         if (arg_count == pd.Count || pd.HasParams) {
4207                                                 if (TypeManager.IsGenericMethodDefinition (best_candidate)) {
4208                                                         if (type_arguments == null) {
4209                                                                 Report.Error (411, loc,
4210                                                                         "The type arguments for method `{0}' cannot be inferred from " +
4211                                                                         "the usage. Try specifying the type arguments explicitly",
4212                                                                         TypeManager.CSharpSignature (best_candidate));
4213                                                                 return null;
4214                                                         }
4215
4216                                                         Type [] g_args = TypeManager.GetGenericArguments (best_candidate);
4217                                                         if (type_arguments.Count != g_args.Length) {
4218                                                                 Report.SymbolRelatedToPreviousError (best_candidate);
4219                                                                 Report.Error (305, loc, "Using the generic method `{0}' requires `{1}' type argument(s)",
4220                                                                         TypeManager.CSharpSignature (best_candidate),
4221                                                                         g_args.Length.ToString ());
4222                                                                 return null;
4223                                                         }
4224                                                 } else {
4225                                                         if (type_arguments != null && !TypeManager.IsGenericMethod (best_candidate)) {
4226                                                                 Namespace.Error_TypeArgumentsCannotBeUsed (best_candidate, loc);
4227                                                                 return null;
4228                                                         }
4229                                                 }
4230
4231                                                 if (!VerifyArgumentsCompat (ec, ref Arguments, arg_count, best_candidate, cand_params, may_fail, loc))
4232                                                         return null;
4233                                         }
4234                                 }
4235
4236                                 if (almost_matched_members.Count != 0) {
4237                                         Error_MemberLookupFailed (ec.ContainerType, type, type, ".ctor",
4238                                         null, MemberTypes.Constructor, AllBindingFlags);
4239                                         return null;
4240                                 }
4241
4242                                 //
4243                                 // We failed to find any method with correct argument count
4244                                 //
4245                                 if (Name == ConstructorInfo.ConstructorName) {
4246                                         Report.SymbolRelatedToPreviousError (type);
4247                                         Report.Error (1729, loc,
4248                                                 "The type `{0}' does not contain a constructor that takes `{1}' arguments",
4249                                                 TypeManager.CSharpName (type), arg_count);
4250                                 } else {
4251                                         Report.Error (1501, loc, "No overload for method `{0}' takes `{1}' arguments",
4252                                                 Name, arg_count.ToString ());
4253                                 }
4254
4255                                 return null;
4256                         }
4257
4258                         if (!is_sorted) {
4259                                 //
4260                                 // At this point, applicable_type is _one_ of the most derived types
4261                                 // in the set of types containing the methods in this MethodGroup.
4262                                 // Filter the candidates so that they only contain methods from the
4263                                 // most derived types.
4264                                 //
4265
4266                                 int finalized = 0; // Number of finalized candidates
4267
4268                                 do {
4269                                         // Invariant: applicable_type is a most derived type
4270
4271                                         // We'll try to complete Section 14.5.5.1 for 'applicable_type' by
4272                                         // eliminating all it's base types.  At the same time, we'll also move
4273                                         // every unrelated type to the end of the array, and pick the next
4274                                         // 'applicable_type'.
4275
4276                                         Type next_applicable_type = null;
4277                                         int j = finalized; // where to put the next finalized candidate
4278                                         int k = finalized; // where to put the next undiscarded candidate
4279                                         for (int i = finalized; i < candidate_top; ++i) {
4280                                                 MethodBase candidate = (MethodBase) candidates [i];
4281                                                 Type decl_type = candidate.DeclaringType;
4282
4283                                                 if (decl_type == applicable_type) {
4284                                                         candidates [k++] = candidates [j];
4285                                                         candidates [j++] = candidates [i];
4286                                                         continue;
4287                                                 }
4288
4289                                                 if (IsAncestralType (decl_type, applicable_type))
4290                                                         continue;
4291
4292                                                 if (next_applicable_type != null &&
4293                                                         IsAncestralType (decl_type, next_applicable_type))
4294                                                         continue;
4295
4296                                                 candidates [k++] = candidates [i];
4297
4298                                                 if (next_applicable_type == null ||
4299                                                         IsAncestralType (next_applicable_type, decl_type))
4300                                                         next_applicable_type = decl_type;
4301                                         }
4302
4303                                         applicable_type = next_applicable_type;
4304                                         finalized = j;
4305                                         candidate_top = k;
4306                                 } while (applicable_type != null);
4307                         }
4308
4309                         //
4310                         // Now we actually find the best method
4311                         //
4312
4313                         best_candidate = (MethodBase) candidates [0];
4314                         if (delegate_type == null)
4315                                 method_params = candidate_to_form != null && candidate_to_form.Contains (best_candidate);
4316
4317                         for (int ix = 1; ix < candidate_top; ix++) {
4318                                 MethodBase candidate = (MethodBase) candidates [ix];
4319
4320                                 if (candidate == best_candidate)
4321                                         continue;
4322
4323                                 bool cand_params = candidate_to_form != null && candidate_to_form.Contains (candidate);
4324
4325                                 if (BetterFunction (ec, Arguments, arg_count,
4326                                         candidate, cand_params,
4327                                         best_candidate, method_params)) {
4328                                         best_candidate = candidate;
4329                                         method_params = cand_params;
4330                                 }
4331                         }
4332                         //
4333                         // Now check that there are no ambiguities i.e the selected method
4334                         // should be better than all the others
4335                         //
4336                         MethodBase ambiguous = null;
4337                         for (int ix = 1; ix < candidate_top; ix++) {
4338                                 MethodBase candidate = (MethodBase) candidates [ix];
4339
4340                                 if (candidate == best_candidate)
4341                                         continue;
4342
4343                                 bool cand_params = candidate_to_form != null && candidate_to_form.Contains (candidate);
4344                                 if (!BetterFunction (ec, Arguments, arg_count,
4345                                         best_candidate, method_params,
4346                                         candidate, cand_params))
4347                                 {
4348                                         if (!may_fail)
4349                                                 Report.SymbolRelatedToPreviousError (candidate);
4350                                         ambiguous = candidate;
4351                                 }
4352                         }
4353
4354                         if (ambiguous != null) {
4355                                 Report.SymbolRelatedToPreviousError (best_candidate);
4356                                 Report.Error (121, loc, "The call is ambiguous between the following methods or properties: `{0}' and `{1}'",
4357                                         TypeManager.CSharpSignature (ambiguous), TypeManager.CSharpSignature (best_candidate));
4358                                 return this;
4359                         }
4360
4361                         //
4362                         // If the method is a virtual function, pick an override closer to the LHS type.
4363                         //
4364                         if (!IsBase && best_candidate.IsVirtual) {
4365                                 if (TypeManager.IsOverride (best_candidate))
4366                                         throw new InternalErrorException (
4367                                                 "Should not happen.  An 'override' method took part in overload resolution: " + best_candidate);
4368
4369                                 if (candidate_overrides != null) {
4370                                         Type[] gen_args = null;
4371                                         bool gen_override = false;
4372                                         if (TypeManager.IsGenericMethod (best_candidate))
4373                                                 gen_args = TypeManager.GetGenericArguments (best_candidate);
4374
4375                                         foreach (MethodBase candidate in candidate_overrides) {
4376                                                 if (TypeManager.IsGenericMethod (candidate)) {
4377                                                         if (gen_args == null)
4378                                                                 continue;
4379
4380                                                         if (gen_args.Length != TypeManager.GetGenericArguments (candidate).Length)
4381                                                                 continue;
4382                                                 } else {
4383                                                         if (gen_args != null)
4384                                                                 continue;
4385                                                 }
4386
4387                                                 if (IsOverride (candidate, best_candidate)) {
4388                                                         gen_override = true;
4389                                                         best_candidate = candidate;
4390                                                 }
4391                                         }
4392
4393                                         if (gen_override && gen_args != null) {
4394 #if GMCS_SOURCE
4395                                                 best_candidate = ((MethodInfo) best_candidate).MakeGenericMethod (gen_args);
4396 #endif
4397                                         }
4398                                 }
4399                         }
4400
4401                         //
4402                         // And now check if the arguments are all
4403                         // compatible, perform conversions if
4404                         // necessary etc. and return if everything is
4405                         // all right
4406                         //
4407                         if (!VerifyArgumentsCompat (ec, ref Arguments, arg_count, best_candidate,
4408                                 method_params, may_fail, loc))
4409                                 return null;
4410
4411                         if (best_candidate == null)
4412                                 return null;
4413
4414                         MethodBase the_method = TypeManager.DropGenericMethodArguments (best_candidate);
4415 #if GMCS_SOURCE
4416                         if (the_method.IsGenericMethodDefinition &&
4417                             !ConstraintChecker.CheckConstraints (ec, the_method, best_candidate, loc))
4418                                 return null;
4419 #endif
4420
4421                         IMethodData data = TypeManager.GetMethod (the_method);
4422                         if (data != null)
4423                                 data.SetMemberIsUsed ();
4424
4425                         return this;
4426                 }
4427
4428                 public override void SetTypeArguments (TypeArguments ta)
4429                 {
4430                         type_arguments = ta;
4431                 }
4432
4433                 public bool VerifyArgumentsCompat (EmitContext ec, ref ArrayList arguments,
4434                                                           int arg_count, MethodBase method,
4435                                                           bool chose_params_expanded,
4436                                                           bool may_fail, Location loc)
4437                 {
4438                         ParameterData pd = TypeManager.GetParameterData (method);
4439
4440                         int errors = Report.Errors;
4441                         Parameter.Modifier p_mod = 0;
4442                         Type pt = null;
4443                         int a_idx = 0, a_pos = 0;
4444                         Argument a = null;
4445                         ArrayList params_initializers = null;
4446
4447                         for (; a_idx < arg_count; a_idx++, ++a_pos) {
4448                                 a = (Argument) arguments [a_idx];
4449                                 if (p_mod != Parameter.Modifier.PARAMS) {
4450                                         p_mod = pd.ParameterModifier (a_idx);
4451                                         pt = pd.ParameterType (a_idx);
4452
4453                                         if (p_mod == Parameter.Modifier.ARGLIST) {
4454                                                 if (a.Type != TypeManager.runtime_argument_handle_type)
4455                                                         break;
4456                                                 continue;
4457                                         }
4458
4459                                         if (pt.IsPointer && !ec.InUnsafe) {
4460                                                 if (may_fail)
4461                                                         return false;
4462
4463                                                 UnsafeError (loc);
4464                                         }
4465
4466                                         if (p_mod == Parameter.Modifier.PARAMS) {
4467                                                 if (chose_params_expanded) {
4468                                                         params_initializers = new ArrayList (arg_count - a_idx);
4469                                                         pt = TypeManager.GetElementType (pt);
4470                                                 }
4471                                         } else if (p_mod != 0) {
4472                                                 pt = TypeManager.GetElementType (pt);
4473                                         }
4474                                 }
4475
4476                                 //
4477                                 // Types have to be identical when ref or out modifer is used
4478                                 //
4479                                 if (a.Modifier != 0 || (p_mod & ~Parameter.Modifier.PARAMS) != 0) {
4480                                         if ((p_mod & ~Parameter.Modifier.PARAMS) != a.Modifier)
4481                                                 break;
4482
4483                                         if (!TypeManager.IsEqual (a.Expr.Type, pt))
4484                                                 break;
4485
4486                                         continue;
4487                                 }
4488
4489                                 Expression conv;
4490                                 if (TypeManager.IsEqual (a.Type, pt)) {
4491                                         conv = a.Expr;
4492                                 } else {
4493                                         conv = Convert.ImplicitConversion (ec, a.Expr, pt, loc);
4494                                         if (conv == null)
4495                                                 break;
4496                                 }
4497
4498                                 //
4499                                 // Convert params arguments to an array initializer
4500                                 //
4501                                 if (params_initializers != null) {
4502                                         // we choose to use 'a.Expr' rather than 'conv' so that
4503                                         // we don't hide the kind of expression we have (esp. CompoundAssign.Helper)
4504                                         params_initializers.Add (a.Expr);
4505                                         arguments.RemoveAt (a_idx--);
4506                                         --arg_count;
4507                                         continue;
4508                                 }
4509
4510                                 // Update the argument with the implicit conversion
4511                                 a.Expr = conv;
4512                         }
4513
4514                         //
4515                         // Fill not provided arguments required by params modifier
4516                         //
4517                         if (params_initializers == null && pd.HasParams && arg_count < pd.Count && a_idx + 1 == pd.Count) {
4518                                 if (arguments == null)
4519                                         arguments = new ArrayList (1);
4520
4521                                 pt = pd.Types [GetApplicableParametersCount (method, pd) - 1];
4522                                 pt = TypeManager.GetElementType (pt);
4523                                 params_initializers = new ArrayList (0);
4524                         }
4525
4526                         if (a_idx == arg_count) {
4527                                 //
4528                                 // Append an array argument with all params arguments
4529                                 //
4530                                 if (params_initializers != null) {
4531                                         arguments.Add (new Argument (
4532                                                 new ArrayCreation (new TypeExpression (pt, loc), "[]",
4533                                                 params_initializers, loc).Resolve (ec)));
4534                                 }
4535                                 return true;
4536                         }
4537
4538                         if (!may_fail && Report.Errors == errors) {
4539                                 if (CustomErrorHandler != null)
4540                                         CustomErrorHandler.NoExactMatch (ec, best_candidate);
4541                                 else
4542                                         Error_InvalidArguments (ec, loc, a_pos, method, a, pd, pt);
4543                         }
4544                         return false;
4545                 }
4546         }
4547
4548         public class ConstantExpr : MemberExpr
4549         {
4550                 FieldInfo constant;
4551
4552                 public ConstantExpr (FieldInfo constant, Location loc)
4553                 {
4554                         this.constant = constant;
4555                         this.loc = loc;
4556                 }
4557
4558                 public override string Name {
4559                         get { throw new NotImplementedException (); }
4560                 }
4561
4562                 public override bool IsInstance {
4563                         get { return !IsStatic; }
4564                 }
4565
4566                 public override bool IsStatic {
4567                         get { return constant.IsStatic; }
4568                 }
4569
4570                 public override Type DeclaringType {
4571                         get { return constant.DeclaringType; }
4572                 }
4573
4574                 public override MemberExpr ResolveMemberAccess (EmitContext ec, Expression left, Location loc, SimpleName original)
4575                 {
4576                         constant = TypeManager.GetGenericFieldDefinition (constant);
4577
4578                         IConstant ic = TypeManager.GetConstant (constant);
4579                         if (ic == null) {
4580                                 if (constant.IsLiteral) {
4581                                         ic = new ExternalConstant (constant);
4582                                 } else {
4583                                         ic = ExternalConstant.CreateDecimal (constant);
4584                                         // HACK: decimal field was not resolved as constant
4585                                         if (ic == null)
4586                                                 return new FieldExpr (constant, loc).ResolveMemberAccess (ec, left, loc, original);
4587                                 }
4588                                 TypeManager.RegisterConstant (constant, ic);
4589                         }
4590
4591                         return base.ResolveMemberAccess (ec, left, loc, original);
4592                 }
4593
4594                 public override Expression CreateExpressionTree (EmitContext ec)
4595                 {
4596                         throw new NotSupportedException ("ET");
4597                 }
4598
4599                 public override Expression DoResolve (EmitContext ec)
4600                 {
4601                         IConstant ic = TypeManager.GetConstant (constant);
4602                         if (ic.ResolveValue ()) {
4603                                 if (!ec.IsInObsoleteScope)
4604                                         ic.CheckObsoleteness (loc);
4605                         }
4606
4607                         return ic.CreateConstantReference (loc);
4608                 }
4609
4610                 public override void Emit (EmitContext ec)
4611                 {
4612                         throw new NotSupportedException ();
4613                 }
4614
4615                 public override string GetSignatureForError ()
4616                 {
4617                         return TypeManager.GetFullNameSignature (constant);
4618                 }
4619         }
4620
4621         /// <summary>
4622         ///   Fully resolved expression that evaluates to a Field
4623         /// </summary>
4624         public class FieldExpr : MemberExpr, IAssignMethod, IMemoryLocation, IVariable {
4625                 public readonly FieldInfo FieldInfo;
4626                 readonly Type constructed_generic_type;
4627                 VariableInfo variable_info;
4628
4629                 LocalTemporary temp;
4630                 bool prepared;
4631                 bool in_initializer;
4632
4633                 public FieldExpr (FieldInfo fi, Location l, bool in_initializer):
4634                         this (fi, l)
4635                 {
4636                         this.in_initializer = in_initializer;
4637                 }
4638
4639                 public FieldExpr (FieldInfo fi, Location l)
4640                 {
4641                         FieldInfo = fi;
4642                         eclass = ExprClass.Variable;
4643                         type = TypeManager.TypeToCoreType (fi.FieldType);
4644                         loc = l;
4645                 }
4646
4647                 public FieldExpr (FieldInfo fi, Type genericType, Location l)
4648                         : this (fi, l)
4649                 {
4650                         this.constructed_generic_type = genericType;
4651                 }
4652
4653                 public override string Name {
4654                         get {
4655                                 return FieldInfo.Name;
4656                         }
4657                 }
4658
4659                 public override bool IsInstance {
4660                         get {
4661                                 return !FieldInfo.IsStatic;
4662                         }
4663                 }
4664
4665                 public override bool IsStatic {
4666                         get {
4667                                 return FieldInfo.IsStatic;
4668                         }
4669                 }
4670
4671                 public override Type DeclaringType {
4672                         get {
4673                                 return FieldInfo.DeclaringType;
4674                         }
4675                 }
4676
4677                 public override string GetSignatureForError ()
4678                 {
4679                         return TypeManager.GetFullNameSignature (FieldInfo);
4680                 }
4681
4682                 public VariableInfo VariableInfo {
4683                         get {
4684                                 return variable_info;
4685                         }
4686                 }
4687
4688                 public override MemberExpr ResolveMemberAccess (EmitContext ec, Expression left, Location loc,
4689                                                                 SimpleName original)
4690                 {
4691                         FieldInfo fi = TypeManager.GetGenericFieldDefinition (FieldInfo);
4692                         Type t = fi.FieldType;
4693
4694                         if (t.IsPointer && !ec.InUnsafe) {
4695                                 UnsafeError (loc);
4696                         }
4697
4698                         return base.ResolveMemberAccess (ec, left, loc, original);
4699                 }
4700
4701                 public override Expression CreateExpressionTree (EmitContext ec)
4702                 {
4703                         Expression instance;
4704                         if (InstanceExpression == null) {
4705                                 instance = new NullLiteral (loc);
4706                         } else {
4707                                 instance = InstanceExpression.CreateExpressionTree (ec);
4708                         }
4709
4710                         ArrayList args = new ArrayList (2);
4711                         args.Add (new Argument (instance));
4712                         args.Add (new Argument (CreateTypeOfExpression ()));
4713                         return CreateExpressionFactoryCall ("Field", args);
4714                 }
4715
4716                 public Expression CreateTypeOfExpression ()
4717                 {
4718                         return new TypeOfField (FieldInfo, loc);
4719                 }
4720
4721                 override public Expression DoResolve (EmitContext ec)
4722                 {
4723                         return DoResolve (ec, false, false);
4724                 }
4725
4726                 Expression DoResolve (EmitContext ec, bool lvalue_instance, bool out_access)
4727                 {
4728                         if (!FieldInfo.IsStatic){
4729                                 if (InstanceExpression == null){
4730                                         //
4731                                         // This can happen when referencing an instance field using
4732                                         // a fully qualified type expression: TypeName.InstanceField = xxx
4733                                         //
4734                                         SimpleName.Error_ObjectRefRequired (ec, loc, GetSignatureForError ());
4735                                         return null;
4736                                 }
4737
4738                                 // Resolve the field's instance expression while flow analysis is turned
4739                                 // off: when accessing a field "a.b", we must check whether the field
4740                                 // "a.b" is initialized, not whether the whole struct "a" is initialized.
4741
4742                                 if (lvalue_instance) {
4743                                         using (ec.With (EmitContext.Flags.DoFlowAnalysis, false)) {
4744                                                 Expression right_side =
4745                                                         out_access ? EmptyExpression.LValueMemberOutAccess : EmptyExpression.LValueMemberAccess;
4746                                                 InstanceExpression = InstanceExpression.ResolveLValue (ec, right_side, loc);
4747                                         }
4748                                 } else {
4749                                         ResolveFlags rf = ResolveFlags.VariableOrValue | ResolveFlags.DisableFlowAnalysis;
4750                                         InstanceExpression = InstanceExpression.Resolve (ec, rf);
4751                                 }
4752
4753                                 if (InstanceExpression == null)
4754                                         return null;
4755
4756                                 using (ec.Set (EmitContext.Flags.OmitStructFlowAnalysis)) {
4757                                         InstanceExpression.CheckMarshalByRefAccess (ec);
4758                                 }
4759                         }
4760
4761                         if (!in_initializer && !ec.IsInFieldInitializer) {
4762                                 ObsoleteAttribute oa;
4763                                 FieldBase f = TypeManager.GetField (FieldInfo);
4764                                 if (f != null) {
4765                                         if (!ec.IsInObsoleteScope)
4766                                                 f.CheckObsoleteness (loc);
4767
4768                                         // To be sure that type is external because we do not register generated fields
4769                                 } else if (!(FieldInfo.DeclaringType is TypeBuilder)) {
4770                                         oa = AttributeTester.GetMemberObsoleteAttribute (FieldInfo);
4771                                         if (oa != null)
4772                                                 AttributeTester.Report_ObsoleteMessage (oa, TypeManager.GetFullNameSignature (FieldInfo), loc);
4773                                 }
4774                         }
4775
4776                         IFixedBuffer fb = AttributeTester.GetFixedBuffer (FieldInfo);
4777                         if (fb != null) {
4778                                 if (!ec.InFixedInitializer && ec.ContainerType.IsValueType) {
4779                                         Report.Error (1666, loc, "You cannot use fixed size buffers contained in unfixed expressions. Try using the fixed statement");
4780                                 }
4781
4782                                 if (InstanceExpression.eclass != ExprClass.Variable) {
4783                                         Report.SymbolRelatedToPreviousError (FieldInfo);
4784                                         Report.Error (1708, loc, "`{0}': Fixed size buffers can only be accessed through locals or fields",
4785                                                 TypeManager.GetFullNameSignature (FieldInfo));
4786                                 }
4787
4788                                 return new FixedBufferPtr (this, fb.ElementType, loc).Resolve (ec);
4789                         }
4790
4791                         // If the instance expression is a local variable or parameter.
4792                         IVariable var = InstanceExpression as IVariable;
4793                         if (var == null || var.VariableInfo == null)
4794                                 return this;
4795
4796                         VariableInfo vi = var.VariableInfo;
4797                         if (!vi.IsFieldAssigned (ec, FieldInfo.Name, loc))
4798                                 return null;
4799
4800                         variable_info = vi.GetSubStruct (FieldInfo.Name);
4801                         return this;
4802                 }
4803
4804                 static readonly int [] codes = {
4805                         191,    // instance, write access
4806                         192,    // instance, out access
4807                         198,    // static, write access
4808                         199,    // static, out access
4809                         1648,   // member of value instance, write access
4810                         1649,   // member of value instance, out access
4811                         1650,   // member of value static, write access
4812                         1651    // member of value static, out access
4813                 };
4814
4815                 static readonly string [] msgs = {
4816                         /*0191*/ "A readonly field `{0}' cannot be assigned to (except in a constructor or a variable initializer)",
4817                         /*0192*/ "A readonly field `{0}' cannot be passed ref or out (except in a constructor)",
4818                         /*0198*/ "A static readonly field `{0}' cannot be assigned to (except in a static constructor or a variable initializer)",
4819                         /*0199*/ "A static readonly field `{0}' cannot be passed ref or out (except in a static constructor)",
4820                         /*1648*/ "Members of readonly field `{0}' cannot be modified (except in a constructor or a variable initializer)",
4821                         /*1649*/ "Members of readonly field `{0}' cannot be passed ref or out (except in a constructor)",
4822                         /*1650*/ "Fields of static readonly field `{0}' cannot be assigned to (except in a static constructor or a variable initializer)",
4823                         /*1651*/ "Fields of static readonly field `{0}' cannot be passed ref or out (except in a static constructor)"
4824                 };
4825
4826                 // The return value is always null.  Returning a value simplifies calling code.
4827                 Expression Report_AssignToReadonly (Expression right_side)
4828                 {
4829                         int i = 0;
4830                         if (right_side == EmptyExpression.OutAccess || right_side == EmptyExpression.LValueMemberOutAccess)
4831                                 i += 1;
4832                         if (IsStatic)
4833                                 i += 2;
4834                         if (right_side == EmptyExpression.LValueMemberAccess || right_side == EmptyExpression.LValueMemberOutAccess)
4835                                 i += 4;
4836                         Report.Error (codes [i], loc, msgs [i], GetSignatureForError ());
4837
4838                         return null;
4839                 }
4840
4841                 override public Expression DoResolveLValue (EmitContext ec, Expression right_side)
4842                 {
4843                         IVariable var = InstanceExpression as IVariable;
4844                         if (var != null && var.VariableInfo != null)
4845                                 var.VariableInfo.SetFieldAssigned (ec, FieldInfo.Name);
4846
4847                         bool lvalue_instance = !FieldInfo.IsStatic && FieldInfo.DeclaringType.IsValueType;
4848                         bool out_access = right_side == EmptyExpression.OutAccess || right_side == EmptyExpression.LValueMemberOutAccess;
4849
4850                         Expression e = DoResolve (ec, lvalue_instance, out_access);
4851
4852                         if (e == null)
4853                                 return null;
4854
4855                         FieldBase fb = TypeManager.GetField (FieldInfo);
4856                         if (fb != null)
4857                                 fb.SetAssigned ();
4858
4859                         if (FieldInfo.IsInitOnly) {
4860                                 // InitOnly fields can only be assigned in constructors or initializers
4861                                 if (!ec.IsInFieldInitializer && !ec.IsConstructor)
4862                                         return Report_AssignToReadonly (right_side);
4863
4864                                 if (ec.IsConstructor) {
4865                                         Type ctype = ec.TypeContainer.CurrentType;
4866                                         if (ctype == null)
4867                                                 ctype = ec.ContainerType;
4868
4869                                         // InitOnly fields cannot be assigned-to in a different constructor from their declaring type
4870                                         if (!TypeManager.IsEqual (ctype, FieldInfo.DeclaringType))
4871                                                 return Report_AssignToReadonly (right_side);
4872                                         // static InitOnly fields cannot be assigned-to in an instance constructor
4873                                         if (IsStatic && !ec.IsStatic)
4874                                                 return Report_AssignToReadonly (right_side);
4875                                         // instance constructors can't modify InitOnly fields of other instances of the same type
4876                                         if (!IsStatic && !(InstanceExpression is This))
4877                                                 return Report_AssignToReadonly (right_side);
4878                                 }
4879                         }
4880
4881                         if (right_side == EmptyExpression.OutAccess &&
4882                             !IsStatic && !(InstanceExpression is This) && TypeManager.mbr_type != null && TypeManager.IsSubclassOf (DeclaringType, TypeManager.mbr_type)) {
4883                                 Report.SymbolRelatedToPreviousError (DeclaringType);
4884                                 Report.Warning (197, 1, loc,
4885                                                 "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",
4886                                                 GetSignatureForError ());
4887                         }
4888
4889                         return this;
4890                 }
4891
4892                 bool is_marshal_by_ref ()
4893                 {
4894                         return !IsStatic && Type.IsValueType && TypeManager.mbr_type != null && TypeManager.IsSubclassOf (DeclaringType, TypeManager.mbr_type);
4895                 }
4896
4897                 public override void CheckMarshalByRefAccess (EmitContext ec)
4898                 {
4899                         if (is_marshal_by_ref () && !(InstanceExpression is This)) {
4900                                 Report.SymbolRelatedToPreviousError (DeclaringType);
4901                                 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",
4902                                                 GetSignatureForError ());
4903                         }
4904                 }
4905
4906                 public override int GetHashCode ()
4907                 {
4908                         return FieldInfo.GetHashCode ();
4909                 }
4910
4911                 public bool IsFixed {
4912                         get {
4913                                 IVariable variable = InstanceExpression as IVariable;
4914                                 // A variable of the form V.I is fixed when V is a fixed variable of a struct type.
4915                                 // We defer the InstanceExpression check after the variable check to avoid a
4916                                 // separate null check on InstanceExpression.
4917                                 return variable != null && InstanceExpression.Type.IsValueType && variable.IsFixed;
4918                         }
4919                 }
4920
4921                 public override bool Equals (object obj)
4922                 {
4923                         FieldExpr fe = obj as FieldExpr;
4924                         if (fe == null)
4925                                 return false;
4926
4927                         if (FieldInfo != fe.FieldInfo)
4928                                 return false;
4929
4930                         if (InstanceExpression == null || fe.InstanceExpression == null)
4931                                 return true;
4932
4933                         return InstanceExpression.Equals (fe.InstanceExpression);
4934                 }
4935
4936                 public void Emit (EmitContext ec, bool leave_copy)
4937                 {
4938                         ILGenerator ig = ec.ig;
4939                         bool is_volatile = false;
4940
4941                         FieldBase f = TypeManager.GetField (FieldInfo);
4942                         if (f != null){
4943                                 if ((f.ModFlags & Modifiers.VOLATILE) != 0)
4944                                         is_volatile = true;
4945
4946                                 f.SetMemberIsUsed ();
4947                         }
4948
4949                         if (FieldInfo.IsStatic){
4950                                 if (is_volatile)
4951                                         ig.Emit (OpCodes.Volatile);
4952
4953                                 ig.Emit (OpCodes.Ldsfld, GetConstructedFieldInfo ());
4954                         } else {
4955                                 if (!prepared)
4956                                         EmitInstance (ec, false);
4957
4958                                 IFixedBuffer ff = AttributeTester.GetFixedBuffer (FieldInfo);
4959                                 if (ff != null) {
4960                                         ig.Emit (OpCodes.Ldflda, GetConstructedFieldInfo ());
4961                                         ig.Emit (OpCodes.Ldflda, ff.Element);
4962                                 } else {
4963                                         if (is_volatile)
4964                                                 ig.Emit (OpCodes.Volatile);
4965
4966                                         ig.Emit (OpCodes.Ldfld, GetConstructedFieldInfo ());
4967                                 }
4968                         }
4969
4970                         if (leave_copy) {
4971                                 ec.ig.Emit (OpCodes.Dup);
4972                                 if (!FieldInfo.IsStatic) {
4973                                         temp = new LocalTemporary (this.Type);
4974                                         temp.Store (ec);
4975                                 }
4976                         }
4977                 }
4978
4979                 public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool prepare_for_load)
4980                 {
4981                         FieldAttributes fa = FieldInfo.Attributes;
4982                         bool is_static = (fa & FieldAttributes.Static) != 0;
4983                         bool is_readonly = (fa & FieldAttributes.InitOnly) != 0;
4984                         ILGenerator ig = ec.ig;
4985
4986                         if (is_readonly && !ec.IsConstructor){
4987                                 Report_AssignToReadonly (source);
4988                                 return;
4989                         }
4990
4991                         prepared = prepare_for_load;
4992                         EmitInstance (ec, prepared);
4993
4994                         source.Emit (ec);
4995                         if (leave_copy) {
4996                                 ec.ig.Emit (OpCodes.Dup);
4997                                 if (!FieldInfo.IsStatic) {
4998                                         temp = new LocalTemporary (this.Type);
4999                                         temp.Store (ec);
5000                                 }
5001                         }
5002
5003                         FieldBase f = TypeManager.GetField (FieldInfo);
5004                         if (f != null){
5005                                 if ((f.ModFlags & Modifiers.VOLATILE) != 0)
5006                                         ig.Emit (OpCodes.Volatile);
5007
5008                                 f.SetAssigned ();
5009                         }
5010
5011                         if (is_static)
5012                                 ig.Emit (OpCodes.Stsfld, GetConstructedFieldInfo ());
5013                         else
5014                                 ig.Emit (OpCodes.Stfld, GetConstructedFieldInfo ());
5015
5016                         if (temp != null) {
5017                                 temp.Emit (ec);
5018                                 temp.Release (ec);
5019                                 temp = null;
5020                         }
5021                 }
5022
5023                 public override void Emit (EmitContext ec)
5024                 {
5025                         Emit (ec, false);
5026                 }
5027
5028                 public override void EmitSideEffect (EmitContext ec)
5029                 {
5030                         FieldBase f = TypeManager.GetField (FieldInfo);
5031                         bool is_volatile = f != null && (f.ModFlags & Modifiers.VOLATILE) != 0;
5032
5033                         if (is_volatile || is_marshal_by_ref ())
5034                                 base.EmitSideEffect (ec);
5035                 }
5036
5037                 public void AddressOf (EmitContext ec, AddressOp mode)
5038                 {
5039                         ILGenerator ig = ec.ig;
5040
5041                         FieldBase f = TypeManager.GetField (FieldInfo);
5042                         if (f != null){
5043                                 if ((f.ModFlags & Modifiers.VOLATILE) != 0){
5044                                         Report.Warning (420, 1, loc, "`{0}': A volatile field references will not be treated as volatile",
5045                                                         f.GetSignatureForError ());
5046                                 }
5047
5048                                 if ((mode & AddressOp.Store) != 0)
5049                                         f.SetAssigned ();
5050                                 if ((mode & AddressOp.Load) != 0)
5051                                         f.SetMemberIsUsed ();
5052                         }
5053
5054                         //
5055                         // Handle initonly fields specially: make a copy and then
5056                         // get the address of the copy.
5057                         //
5058                         bool need_copy;
5059                         if (FieldInfo.IsInitOnly){
5060                                 need_copy = true;
5061                                 if (ec.IsConstructor){
5062                                         if (FieldInfo.IsStatic){
5063                                                 if (ec.IsStatic)
5064                                                         need_copy = false;
5065                                         } else
5066                                                 need_copy = false;
5067                                 }
5068                         } else
5069                                 need_copy = false;
5070
5071                         if (need_copy){
5072                                 LocalBuilder local;
5073                                 Emit (ec);
5074                                 local = ig.DeclareLocal (type);
5075                                 ig.Emit (OpCodes.Stloc, local);
5076                                 ig.Emit (OpCodes.Ldloca, local);
5077                                 return;
5078                         }
5079
5080
5081                         if (FieldInfo.IsStatic){
5082                                 ig.Emit (OpCodes.Ldsflda, GetConstructedFieldInfo ());
5083                         } else {
5084                                 if (!prepared)
5085                                         EmitInstance (ec, false);
5086                                 ig.Emit (OpCodes.Ldflda, GetConstructedFieldInfo ());
5087                         }
5088                 }
5089
5090                 FieldInfo GetConstructedFieldInfo ()
5091                 {
5092                         if (constructed_generic_type == null)
5093                                 return FieldInfo;
5094 #if GMCS_SOURCE
5095                         return TypeBuilder.GetField (constructed_generic_type, FieldInfo);
5096 #else
5097                         throw new NotSupportedException ();
5098 #endif
5099                 }
5100         }
5101
5102
5103         /// <summary>
5104         ///   Expression that evaluates to a Property.  The Assign class
5105         ///   might set the `Value' expression if we are in an assignment.
5106         ///
5107         ///   This is not an LValue because we need to re-write the expression, we
5108         ///   can not take data from the stack and store it.
5109         /// </summary>
5110         public class PropertyExpr : MemberExpr, IAssignMethod {
5111                 public readonly PropertyInfo PropertyInfo;
5112                 MethodInfo getter, setter;
5113                 bool is_static;
5114
5115                 bool resolved;
5116
5117                 LocalTemporary temp;
5118                 bool prepared;
5119
5120                 public PropertyExpr (Type container_type, PropertyInfo pi, Location l)
5121                 {
5122                         PropertyInfo = pi;
5123                         eclass = ExprClass.PropertyAccess;
5124                         is_static = false;
5125                         loc = l;
5126
5127                         type = TypeManager.TypeToCoreType (pi.PropertyType);
5128
5129                         ResolveAccessors (container_type);
5130                 }
5131
5132                 public override string Name {
5133                         get {
5134                                 return PropertyInfo.Name;
5135                         }
5136                 }
5137
5138                 public override bool IsInstance {
5139                         get {
5140                                 return !is_static;
5141                         }
5142                 }
5143
5144                 public override bool IsStatic {
5145                         get {
5146                                 return is_static;
5147                         }
5148                 }
5149
5150                 public override Expression CreateExpressionTree (EmitContext ec)
5151                 {
5152                         ArrayList args;
5153                         if (IsSingleDimensionalArrayLength ()) {
5154                                 args = new ArrayList (1);
5155                                 args.Add (new Argument (InstanceExpression.CreateExpressionTree (ec)));
5156                                 return CreateExpressionFactoryCall ("ArrayLength", args);
5157                         }
5158
5159                         if (is_base) {
5160                                 Error_BaseAccessInExpressionTree (loc);
5161                                 return null;
5162                         }
5163
5164                         args = new ArrayList (2);
5165                         if (InstanceExpression == null)
5166                                 args.Add (new Argument (new NullLiteral (loc)));
5167                         else
5168                                 args.Add (new Argument (InstanceExpression.CreateExpressionTree (ec)));
5169                         args.Add (new Argument (new TypeOfMethodInfo (getter, loc)));
5170                         return CreateExpressionFactoryCall ("Property", args);
5171                 }
5172
5173                 public Expression CreateSetterTypeOfExpression ()
5174                 {
5175                         return new TypeOfMethodInfo (setter, loc);
5176                 }
5177
5178                 public override Type DeclaringType {
5179                         get {
5180                                 return PropertyInfo.DeclaringType;
5181                         }
5182                 }
5183
5184                 public override string GetSignatureForError ()
5185                 {
5186                         return TypeManager.GetFullNameSignature (PropertyInfo);
5187                 }
5188
5189                 void FindAccessors (Type invocation_type)
5190                 {
5191                         const BindingFlags flags = BindingFlags.Public | BindingFlags.NonPublic |
5192                                 BindingFlags.Static | BindingFlags.Instance |
5193                                 BindingFlags.DeclaredOnly;
5194
5195                         Type current = PropertyInfo.DeclaringType;
5196                         for (; current != null; current = current.BaseType) {
5197                                 MemberInfo[] group = TypeManager.MemberLookup (
5198                                         invocation_type, invocation_type, current,
5199                                         MemberTypes.Property, flags, PropertyInfo.Name, null);
5200
5201                                 if (group == null)
5202                                         continue;
5203
5204                                 if (group.Length != 1)
5205                                         // Oooops, can this ever happen ?
5206                                         return;
5207
5208                                 PropertyInfo pi = (PropertyInfo) group [0];
5209
5210                                 if (getter == null)
5211                                         getter = pi.GetGetMethod (true);
5212
5213                                 if (setter == null)
5214                                         setter = pi.GetSetMethod (true);
5215
5216                                 MethodInfo accessor = getter != null ? getter : setter;
5217
5218                                 if (!accessor.IsVirtual)
5219                                         return;
5220                         }
5221                 }
5222
5223                 //
5224                 // We also perform the permission checking here, as the PropertyInfo does not
5225                 // hold the information for the accessibility of its setter/getter
5226                 //
5227                 // TODO: Refactor to use some kind of cache together with GetPropertyFromAccessor
5228                 void ResolveAccessors (Type container_type)
5229                 {
5230                         FindAccessors (container_type);
5231
5232                         if (getter != null) {
5233                                 MethodBase the_getter = TypeManager.DropGenericMethodArguments (getter);
5234                                 IMethodData md = TypeManager.GetMethod (the_getter);
5235                                 if (md != null)
5236                                         md.SetMemberIsUsed ();
5237
5238                                 is_static = getter.IsStatic;
5239                         }
5240
5241                         if (setter != null) {
5242                                 MethodBase the_setter = TypeManager.DropGenericMethodArguments (setter);
5243                                 IMethodData md = TypeManager.GetMethod (the_setter);
5244                                 if (md != null)
5245                                         md.SetMemberIsUsed ();
5246
5247                                 is_static = setter.IsStatic;
5248                         }
5249                 }
5250
5251                 public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
5252                 {
5253                         if (InstanceExpression != null)
5254                                 InstanceExpression.MutateHoistedGenericType (storey);
5255
5256                         type = storey.MutateType (type);
5257                         getter = storey.MutateGenericMethod (getter);
5258                 }
5259
5260                 bool InstanceResolve (EmitContext ec, bool lvalue_instance, bool must_do_cs1540_check)
5261                 {
5262                         if (is_static) {
5263                                 InstanceExpression = null;
5264                                 return true;
5265                         }
5266
5267                         if (InstanceExpression == null) {
5268                                 SimpleName.Error_ObjectRefRequired (ec, loc, GetSignatureForError ());
5269                                 return false;
5270                         }
5271
5272                         InstanceExpression = InstanceExpression.DoResolve (ec);
5273                         if (lvalue_instance && InstanceExpression != null)
5274                                 InstanceExpression = InstanceExpression.ResolveLValue (ec, EmptyExpression.LValueMemberAccess, loc);
5275
5276                         if (InstanceExpression == null)
5277                                 return false;
5278
5279                         InstanceExpression.CheckMarshalByRefAccess (ec);
5280
5281                         if (must_do_cs1540_check && (InstanceExpression != EmptyExpression.Null) &&
5282                             !TypeManager.IsInstantiationOfSameGenericType (InstanceExpression.Type, ec.ContainerType) &&
5283                             !TypeManager.IsNestedChildOf (ec.ContainerType, InstanceExpression.Type) &&
5284                             !TypeManager.IsSubclassOf (InstanceExpression.Type, ec.ContainerType)) {
5285                                 Report.SymbolRelatedToPreviousError (PropertyInfo);
5286                                 Error_CannotAccessProtected (loc, PropertyInfo, InstanceExpression.Type, ec.ContainerType);
5287                                 return false;
5288                         }
5289
5290                         return true;
5291                 }
5292
5293                 void Error_PropertyNotFound (MethodInfo mi, bool getter)
5294                 {
5295                         // TODO: correctly we should compare arguments but it will lead to bigger changes
5296                         if (mi is MethodBuilder) {
5297                                 Error_TypeDoesNotContainDefinition (loc, PropertyInfo.DeclaringType, Name);
5298                                 return;
5299                         }
5300
5301                         StringBuilder sig = new StringBuilder (TypeManager.CSharpName (mi.DeclaringType));
5302                         sig.Append ('.');
5303                         ParameterData iparams = TypeManager.GetParameterData (mi);
5304                         sig.Append (getter ? "get_" : "set_");
5305                         sig.Append (Name);
5306                         sig.Append (iparams.GetSignatureForError ());
5307
5308                         Report.SymbolRelatedToPreviousError (mi);
5309                         Report.Error (1546, loc, "Property `{0}' is not supported by the C# language. Try to call the accessor method `{1}' directly",
5310                                 Name, sig.ToString ());
5311                 }
5312
5313                 public bool IsAccessibleFrom (Type invocation_type, bool lvalue)
5314                 {
5315                         bool dummy;
5316                         MethodInfo accessor = lvalue ? setter : getter;
5317                         if (accessor == null && lvalue)
5318                                 accessor = getter;
5319                         return accessor != null && IsAccessorAccessible (invocation_type, accessor, out dummy);
5320                 }
5321
5322                 bool IsSingleDimensionalArrayLength ()
5323                 {
5324                         if (DeclaringType != TypeManager.array_type || getter == null || Name != "Length")
5325                                 return false;
5326
5327                         string t_name = InstanceExpression.Type.Name;
5328                         int t_name_len = t_name.Length;
5329                         return t_name_len > 2 && t_name [t_name_len - 2] == '[';
5330                 }
5331
5332                 override public Expression DoResolve (EmitContext ec)
5333                 {
5334                         if (resolved)
5335                                 return this;
5336
5337                         if (getter != null){
5338                                 if (TypeManager.GetParameterData (getter).Count != 0){
5339                                         Error_PropertyNotFound (getter, true);
5340                                         return null;
5341                                 }
5342                         }
5343
5344                         if (getter == null){
5345                                 //
5346                                 // The following condition happens if the PropertyExpr was
5347                                 // created, but is invalid (ie, the property is inaccessible),
5348                                 // and we did not want to embed the knowledge about this in
5349                                 // the caller routine.  This only avoids double error reporting.
5350                                 //
5351                                 if (setter == null)
5352                                         return null;
5353
5354                                 if (InstanceExpression != EmptyExpression.Null) {
5355                                         Report.Error (154, loc, "The property or indexer `{0}' cannot be used in this context because it lacks the `get' accessor",
5356                                                 TypeManager.GetFullNameSignature (PropertyInfo));
5357                                         return null;
5358                                 }
5359                         }
5360
5361                         bool must_do_cs1540_check = false;
5362                         if (getter != null &&
5363                             !IsAccessorAccessible (ec.ContainerType, getter, out must_do_cs1540_check)) {
5364                                 PropertyBase.PropertyMethod pm = TypeManager.GetMethod (getter) as PropertyBase.PropertyMethod;
5365                                 if (pm != null && pm.HasCustomAccessModifier) {
5366                                         Report.SymbolRelatedToPreviousError (pm);
5367                                         Report.Error (271, loc, "The property or indexer `{0}' cannot be used in this context because the get accessor is inaccessible",
5368                                                 TypeManager.CSharpSignature (getter));
5369                                 }
5370                                 else {
5371                                         Report.SymbolRelatedToPreviousError (getter);
5372                                         ErrorIsInaccesible (loc, TypeManager.CSharpSignature (getter));
5373                                 }
5374                                 return null;
5375                         }
5376
5377                         if (!InstanceResolve (ec, false, must_do_cs1540_check))
5378                                 return null;
5379
5380                         //
5381                         // Only base will allow this invocation to happen.
5382                         //
5383                         if (IsBase && getter.IsAbstract) {
5384                                 Error_CannotCallAbstractBase (TypeManager.GetFullNameSignature (PropertyInfo));
5385                                 return null;
5386                         }
5387
5388                         if (PropertyInfo.PropertyType.IsPointer && !ec.InUnsafe){
5389                                 UnsafeError (loc);
5390                                 return null;
5391                         }
5392
5393                         resolved = true;
5394
5395                         return this;
5396                 }
5397
5398                 override public Expression DoResolveLValue (EmitContext ec, Expression right_side)
5399                 {
5400                         if (right_side == EmptyExpression.OutAccess) {
5401                                 if (ec.CurrentBlock.Toplevel.GetTransparentIdentifier (PropertyInfo.Name) != null) {
5402                                         Report.Error (1939, loc, "A range variable `{0}' may not be passes as `ref' or `out' parameter",
5403                                             PropertyInfo.Name);
5404                                 } else {
5405                                         Report.Error (206, loc, "A property or indexer `{0}' may not be passed as `ref' or `out' parameter",
5406                                               GetSignatureForError ());
5407                                 }
5408                                 return null;
5409                         }
5410
5411                         if (right_side == EmptyExpression.LValueMemberAccess || right_side == EmptyExpression.LValueMemberOutAccess) {
5412                                 Error_CannotModifyIntermediateExpressionValue (ec);
5413                         }
5414
5415                         if (setter == null){
5416                                 //
5417                                 // The following condition happens if the PropertyExpr was
5418                                 // created, but is invalid (ie, the property is inaccessible),
5419                                 // and we did not want to embed the knowledge about this in
5420                                 // the caller routine.  This only avoids double error reporting.
5421                                 //
5422                                 if (getter == null)
5423                                         return null;
5424                                 Report.Error (200, loc, "Property or indexer `{0}' cannot be assigned to (it is read only)",
5425                                               GetSignatureForError ());
5426                                 return null;
5427                         }
5428
5429                         if (TypeManager.GetParameterData (setter).Count != 1){
5430                                 Error_PropertyNotFound (setter, false);
5431                                 return null;
5432                         }
5433
5434                         bool must_do_cs1540_check;
5435                         if (!IsAccessorAccessible (ec.ContainerType, setter, out must_do_cs1540_check)) {
5436                                 PropertyBase.PropertyMethod pm = TypeManager.GetMethod (setter) as PropertyBase.PropertyMethod;
5437                                 if (pm != null && pm.HasCustomAccessModifier) {
5438                                         Report.SymbolRelatedToPreviousError (pm);
5439                                         Report.Error (272, loc, "The property or indexer `{0}' cannot be used in this context because the set accessor is inaccessible",
5440                                                 TypeManager.CSharpSignature (setter));
5441                                 }
5442                                 else {
5443                                         Report.SymbolRelatedToPreviousError (setter);
5444                                         ErrorIsInaccesible (loc, TypeManager.CSharpSignature (setter));
5445                                 }
5446                                 return null;
5447                         }
5448
5449                         if (!InstanceResolve (ec, PropertyInfo.DeclaringType.IsValueType, must_do_cs1540_check))
5450                                 return null;
5451
5452                         //
5453                         // Only base will allow this invocation to happen.
5454                         //
5455                         if (IsBase && setter.IsAbstract){
5456                                 Error_CannotCallAbstractBase (TypeManager.GetFullNameSignature (PropertyInfo));
5457                                 return null;
5458                         }
5459
5460                         return this;
5461                 }
5462
5463                 public override void Emit (EmitContext ec)
5464                 {
5465                         Emit (ec, false);
5466                 }
5467
5468                 public void Emit (EmitContext ec, bool leave_copy)
5469                 {
5470                         //
5471                         // Special case: length of single dimension array property is turned into ldlen
5472                         //
5473                         if (IsSingleDimensionalArrayLength ()) {
5474                                 if (!prepared)
5475                                         EmitInstance (ec, false);
5476                                 ec.ig.Emit (OpCodes.Ldlen);
5477                                 ec.ig.Emit (OpCodes.Conv_I4);
5478                                 return;
5479                         }
5480
5481                         Invocation.EmitCall (ec, IsBase, InstanceExpression, getter, null, loc, prepared, false);
5482
5483                         if (leave_copy) {
5484                                 ec.ig.Emit (OpCodes.Dup);
5485                                 if (!is_static) {
5486                                         temp = new LocalTemporary (this.Type);
5487                                         temp.Store (ec);
5488                                 }
5489                         }
5490                 }
5491
5492                 //
5493                 // Implements the IAssignMethod interface for assignments
5494                 //
5495                 public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool prepare_for_load)
5496                 {
5497                         Expression my_source = source;
5498
5499                         if (prepare_for_load) {
5500                                 prepared = true;
5501                                 source.Emit (ec);
5502
5503                                 if (leave_copy) {
5504                                         ec.ig.Emit (OpCodes.Dup);
5505                                         if (!is_static) {
5506                                                 temp = new LocalTemporary (this.Type);
5507                                                 temp.Store (ec);
5508                                         }
5509                                 }
5510                         } else if (leave_copy) {
5511                                 source.Emit (ec);
5512                                 temp = new LocalTemporary (this.Type);
5513                                 temp.Store (ec);
5514                                 my_source = temp;
5515                         }
5516
5517                         ArrayList args = new ArrayList (1);
5518                         args.Add (new Argument (my_source, Argument.AType.Expression));
5519
5520                         Invocation.EmitCall (ec, IsBase, InstanceExpression, setter, args, loc, false, prepared);
5521
5522                         if (temp != null) {
5523                                 temp.Emit (ec);
5524                                 temp.Release (ec);
5525                         }
5526                 }
5527         }
5528
5529         /// <summary>
5530         ///   Fully resolved expression that evaluates to an Event
5531         /// </summary>
5532         public class EventExpr : MemberExpr {
5533                 public readonly EventInfo EventInfo;
5534
5535                 bool is_static;
5536                 MethodInfo add_accessor, remove_accessor;
5537
5538                 public EventExpr (EventInfo ei, Location loc)
5539                 {
5540                         EventInfo = ei;
5541                         this.loc = loc;
5542                         eclass = ExprClass.EventAccess;
5543
5544                         add_accessor = TypeManager.GetAddMethod (ei);
5545                         remove_accessor = TypeManager.GetRemoveMethod (ei);
5546                         if (add_accessor.IsStatic || remove_accessor.IsStatic)
5547                                 is_static = true;
5548
5549                         if (EventInfo is MyEventBuilder){
5550                                 MyEventBuilder eb = (MyEventBuilder) EventInfo;
5551                                 type = eb.EventType;
5552                                 eb.SetUsed ();
5553                         } else
5554                                 type = EventInfo.EventHandlerType;
5555                 }
5556
5557                 public override string Name {
5558                         get {
5559                                 return EventInfo.Name;
5560                         }
5561                 }
5562
5563                 public override bool IsInstance {
5564                         get {
5565                                 return !is_static;
5566                         }
5567                 }
5568
5569                 public override bool IsStatic {
5570                         get {
5571                                 return is_static;
5572                         }
5573                 }
5574
5575                 public override Type DeclaringType {
5576                         get {
5577                                 return EventInfo.DeclaringType;
5578                         }
5579                 }
5580
5581                 void Error_AssignmentEventOnly ()
5582                 {
5583                         Report.Error (79, loc, "The event `{0}' can only appear on the left hand side of `+=' or `-=' operator",
5584                                 GetSignatureForError ());
5585                 }
5586
5587                 public override MemberExpr ResolveMemberAccess (EmitContext ec, Expression left, Location loc,
5588                                                                 SimpleName original)
5589                 {
5590                         //
5591                         // If the event is local to this class, we transform ourselves into a FieldExpr
5592                         //
5593
5594                         if (EventInfo.DeclaringType == ec.ContainerType ||
5595                             TypeManager.IsNestedChildOf(ec.ContainerType, EventInfo.DeclaringType)) {
5596                                 EventField mi = TypeManager.GetEventField (EventInfo);
5597
5598                                 if (mi != null) {
5599                                         if (!ec.IsInObsoleteScope)
5600                                                 mi.CheckObsoleteness (loc);
5601
5602                                         if ((mi.ModFlags & (Modifiers.ABSTRACT | Modifiers.EXTERN)) != 0 && !ec.IsInCompoundAssignment)
5603                                                 Error_AssignmentEventOnly ();
5604
5605                                         FieldExpr ml = new FieldExpr (mi.FieldBuilder, loc);
5606
5607                                         InstanceExpression = null;
5608
5609                                         return ml.ResolveMemberAccess (ec, left, loc, original);
5610                                 }
5611                         }
5612
5613                         if (left is This && !ec.IsInCompoundAssignment)
5614                                 Error_AssignmentEventOnly ();
5615
5616                         return base.ResolveMemberAccess (ec, left, loc, original);
5617                 }
5618
5619                 bool InstanceResolve (EmitContext ec, bool must_do_cs1540_check)
5620                 {
5621                         if (is_static) {
5622                                 InstanceExpression = null;
5623                                 return true;
5624                         }
5625
5626                         if (InstanceExpression == null) {
5627                                 SimpleName.Error_ObjectRefRequired (ec, loc, GetSignatureForError ());
5628                                 return false;
5629                         }
5630
5631                         InstanceExpression = InstanceExpression.DoResolve (ec);
5632                         if (InstanceExpression == null)
5633                                 return false;
5634
5635                         if (IsBase && add_accessor.IsAbstract) {
5636                                 Error_CannotCallAbstractBase(TypeManager.CSharpSignature(add_accessor));
5637                                 return false;
5638                         }
5639
5640                         //
5641                         // This is using the same mechanism as the CS1540 check in PropertyExpr.
5642                         // However, in the Event case, we reported a CS0122 instead.
5643                         //
5644                         if (must_do_cs1540_check && InstanceExpression != EmptyExpression.Null &&
5645                             InstanceExpression.Type != ec.ContainerType &&
5646                             TypeManager.IsSubclassOf (ec.ContainerType, InstanceExpression.Type)) {
5647                                 Report.SymbolRelatedToPreviousError (EventInfo);
5648                                 ErrorIsInaccesible (loc, TypeManager.CSharpSignature (EventInfo));
5649                                 return false;
5650                         }
5651
5652                         return true;
5653                 }
5654
5655                 public bool IsAccessibleFrom (Type invocation_type)
5656                 {
5657                         bool dummy;
5658                         return IsAccessorAccessible (invocation_type, add_accessor, out dummy) &&
5659                                 IsAccessorAccessible (invocation_type, remove_accessor, out dummy);
5660                 }
5661
5662                 public override Expression CreateExpressionTree (EmitContext ec)
5663                 {
5664                         throw new NotSupportedException ("ET");
5665                 }
5666
5667                 public override Expression DoResolveLValue (EmitContext ec, Expression right_side)
5668                 {
5669                         // contexts where an LValue is valid have already devolved to FieldExprs
5670                         Error_CannotAssign ();
5671                         return null;
5672                 }
5673
5674                 public override Expression DoResolve (EmitContext ec)
5675                 {
5676                         bool must_do_cs1540_check;
5677                         if (!(IsAccessorAccessible (ec.ContainerType, add_accessor, out must_do_cs1540_check) &&
5678                               IsAccessorAccessible (ec.ContainerType, remove_accessor, out must_do_cs1540_check))) {
5679                                 Report.SymbolRelatedToPreviousError (EventInfo);
5680                                 ErrorIsInaccesible (loc, TypeManager.CSharpSignature (EventInfo));
5681                                 return null;
5682                         }
5683
5684                         if (!InstanceResolve (ec, must_do_cs1540_check))
5685                                 return null;
5686
5687                         if (!ec.IsInCompoundAssignment) {
5688                                 Error_CannotAssign ();
5689                                 return null;
5690                         }
5691
5692                         return this;
5693                 }
5694
5695                 public override void Emit (EmitContext ec)
5696                 {
5697                         Error_CannotAssign ();
5698                 }
5699
5700                 public void Error_CannotAssign ()
5701                 {
5702                         Report.Error (70, loc,
5703                                 "The event `{0}' can only appear on the left hand side of += or -= when used outside of the type `{1}'",
5704                                 GetSignatureForError (), TypeManager.CSharpName (EventInfo.DeclaringType));
5705                 }
5706
5707                 public override string GetSignatureForError ()
5708                 {
5709                         return TypeManager.CSharpSignature (EventInfo);
5710                 }
5711
5712                 public void EmitAddOrRemove (EmitContext ec, bool is_add, Expression source)
5713                 {
5714                         ArrayList args = new ArrayList (1);
5715                         args.Add (new Argument (source, Argument.AType.Expression));
5716                         Invocation.EmitCall (ec, IsBase, InstanceExpression, is_add ? add_accessor : remove_accessor, args, loc);
5717                 }
5718         }
5719
5720         public class TemporaryVariable : VariableReference
5721         {
5722                 LocalInfo li;
5723
5724                 public TemporaryVariable (Type type, Location loc)
5725                 {
5726                         this.type = type;
5727                         this.loc = loc;
5728                         eclass = ExprClass.Variable;
5729                 }
5730
5731                 public override Expression CreateExpressionTree (EmitContext ec)
5732                 {
5733                         throw new NotSupportedException ("ET");
5734                 }
5735
5736                 public override Expression DoResolve (EmitContext ec)
5737                 {
5738                         if (li != null)
5739                                 return this;
5740
5741                         TypeExpr te = new TypeExpression (type, loc);
5742                         li = ec.CurrentBlock.AddTemporaryVariable (te, loc);
5743                         if (!li.Resolve (ec))
5744                                 return null;
5745
5746                         if (ec.MustCaptureVariable (li) && !ec.IsInProbingMode) {
5747                                 AnonymousMethodStorey storey = li.Block.Explicit.CreateAnonymousMethodStorey (ec);
5748                                 storey.CaptureLocalVariable (ec, li);
5749                         }
5750
5751                         return this;
5752                 }
5753
5754                 public override void Emit (EmitContext ec)
5755                 {
5756                         Emit (ec, false);
5757                 }
5758
5759                 public void EmitAssign (EmitContext ec, Expression source)
5760                 {
5761                         EmitAssign (ec, source, false, false);
5762                 }
5763
5764                 public override HoistedVariable HoistedVariable {
5765                         get { return li.HoistedVariableReference; }
5766                 }
5767
5768                 public override bool IsFixed {
5769                         get { return true; }
5770                 }
5771
5772                 public override bool IsRef {
5773                         get { return false; }
5774                 }
5775
5776                 public override ILocalVariable Variable {
5777                         get { return li; }
5778                 }
5779
5780                 public override VariableInfo VariableInfo {
5781                         get { throw new NotImplementedException (); }
5782                 }
5783         }
5784
5785         ///
5786         /// Handles `var' contextual keyword; var becomes a keyword only
5787         /// if no type called var exists in a variable scope
5788         ///
5789         public class VarExpr : SimpleName
5790         {
5791                 // Used for error reporting only
5792                 ArrayList initializer;
5793
5794                 public VarExpr (Location loc)
5795                         : base ("var", loc)
5796                 {
5797                 }
5798
5799                 public ArrayList VariableInitializer {
5800                         set {
5801                                 this.initializer = value;
5802                         }
5803                 }
5804
5805                 public bool InferType (EmitContext ec, Expression right_side)
5806                 {
5807                         if (type != null)
5808                                 throw new InternalErrorException ("An implicitly typed local variable could not be redefined");
5809
5810                         type = right_side.Type;
5811                         if (type == TypeManager.null_type || type == TypeManager.void_type || type == TypeManager.anonymous_method_type) {
5812                                 Report.Error (815, loc, "An implicitly typed local variable declaration cannot be initialized with `{0}'",
5813                                               right_side.GetSignatureForError ());
5814                                 return false;
5815                         }
5816
5817                         eclass = ExprClass.Variable;
5818                         return true;
5819                 }
5820
5821                 protected override void Error_TypeOrNamespaceNotFound (IResolveContext ec)
5822                 {
5823                         Report.Error (825, loc, "The contextual keyword `var' may only appear within a local variable declaration");
5824                 }
5825
5826                 public override TypeExpr ResolveAsContextualType (IResolveContext rc, bool silent)
5827                 {
5828                         TypeExpr te = base.ResolveAsContextualType (rc, true);
5829                         if (te != null)
5830                                 return te;
5831
5832                         if (initializer == null)
5833                                 return null;
5834
5835                         if (initializer.Count > 1) {
5836                                 Location loc = ((Mono.CSharp.CSharpParser.VariableDeclaration)initializer [1]).Location;
5837                                 Report.Error (819, loc, "An implicitly typed local variable declaration cannot include multiple declarators");
5838                                 initializer = null;
5839                                 return null;
5840                         }
5841
5842                         Expression variable_initializer = ((Mono.CSharp.CSharpParser.VariableDeclaration)initializer [0]).expression_or_array_initializer;
5843                         if (variable_initializer == null) {
5844                                 Report.Error (818, loc, "An implicitly typed local variable declarator must include an initializer");
5845                                 return null;
5846                         }
5847
5848                         return null;
5849                 }
5850         }
5851 }