mcs/mcs/anonymous.cs

   1 //
   2 // anonymous.cs: Support for anonymous methods and types
   3 //
   4 // Author:
   5 //   Miguel de Icaza (miguel@ximain.com)
   6 //   Marek Safar (marek.safar@gmail.com)
   7 //
   8 // Dual licensed under the terms of the MIT X11 or GNU GPL
   9 // Copyright 2003-2008 Novell, Inc.
  10 //
  11
  12 using System;
  13 using System.Text;
  14 using System.Collections;
  15 using System.Collections.Specialized;
  16 using System.Reflection;
  17 using System.Reflection.Emit;
  18
  19 namespace Mono.CSharp {
  20
  21         public abstract class CompilerGeneratedClass : Class
  22         {
  23                 public static string MakeName (string host, string typePrefix, string name, int id)
  24                 {
  25                         return "<" + host + ">" + typePrefix + "__" + name + id.ToString ("X");
  26                 }
  27
  28                 protected CompilerGeneratedClass (DeclSpace parent, MemberName name, int mod)
  29                         : base (parent.NamespaceEntry, parent, name, mod | Modifiers.COMPILER_GENERATED | Modifiers.SEALED, null)
  30                 {
  31                 }
  32
  33                 protected CompilerGeneratedClass (DeclSpace parent, GenericMethod generic, MemberName name, int mod)
  34                         : this (parent, name, mod)
  35                 {
  36                         if (generic != null) {
  37                                 ArrayList list = new ArrayList ();
  38                                 foreach (TypeParameter tparam in generic.TypeParameters) {
  39                                         if (tparam.Constraints != null)
  40                                                 list.Add (tparam.Constraints.Clone ());
  41                                 }
  42                                 SetParameterInfo (list);
  43                         }
  44                 }
  45
  46                 protected void CheckMembersDefined ()
  47                 {
  48                         if (members_defined)
  49                                 throw new InternalErrorException ("Helper class already defined!");
  50                 }
  51         }
  52
  53         //
  54         // Anonymous method storey is created when an anonymous method uses
  55         // variable or parameter from outer scope. They are then hoisted to
  56         // anonymous method storey (captured)
  57         //
  58         public class AnonymousMethodStorey : CompilerGeneratedClass
  59         {
  60                 class StoreyFieldPair {
  61                         public readonly AnonymousMethodStorey Storey;
  62                         public readonly Field Field;
  63
  64                         public StoreyFieldPair (AnonymousMethodStorey storey, Field field)
  65                         {
  66                                 this.Storey = storey;
  67                                 this.Field = field;
  68                         }
  69
  70                         public override int GetHashCode ()
  71                         {
  72                                 return Storey.ID.GetHashCode ();
  73                         }
  74
  75                         public override bool Equals (object obj)
  76                         {
  77                                 return (AnonymousMethodStorey)obj == Storey;
  78                         }
  79                 }
  80
  81                 sealed class HoistedGenericField : Field
  82                 {
  83                         public HoistedGenericField (DeclSpace parent, FullNamedExpression type, int mod, string name,
  84                                   Attributes attrs, Location loc)
  85                                 : base (parent, type, mod, new MemberName (name, loc), attrs)
  86                         {
  87                         }
  88
  89                         protected override bool ResolveMemberType ()
  90                         {
  91                                 if (!base.ResolveMemberType ())
  92                                         return false;
  93
  94                                 AnonymousMethodStorey parent = ((AnonymousMethodStorey) Parent).GetGenericStorey ();
  95                                 if (parent != null)
  96                                         member_type = parent.MutateType (member_type);
  97
  98                                 return true;
  99                         }
 100                 }
 101
 102                 //
 103                 // Needed to delay hoisted _this_ initialization. When an anonymous
 104                 // method is used inside ctor and _this_ is hoisted, base ctor has to
 105                 // be called first, otherwise _this_ will be initialized with
 106                 // uninitialized value.
 107                 //
 108                 sealed class ThisInitializer : Statement
 109                 {
 110                         readonly HoistedThis hoisted_this;
 111
 112                         public ThisInitializer (HoistedThis hoisted_this)
 113                         {
 114                                 this.hoisted_this = hoisted_this;
 115                         }
 116
 117                         protected override void DoEmit (EmitContext ec)
 118                         {
 119                                 hoisted_this.EmitHoistingAssignment (ec);
 120                         }
 121
 122                         protected override void CloneTo (CloneContext clonectx, Statement target)
 123                         {
 124                                 // Nothing to clone
 125                         }
 126
 127                         public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
 128                         {
 129                                 // Nothing to mutate
 130                         }
 131                 }
 132
 133                 // Unique storey ID
 134                 public readonly int ID;
 135                 static int unique_id;
 136
 137                 public readonly Block OriginalSourceBlock;
 138
 139                 // A list of StoreyFieldPair with local field keeping parent storey instance
 140                 ArrayList used_parent_storeys;
 141                 ArrayList children_references;
 142
 143                 // A list of hoisted parameters
 144                 protected ArrayList hoisted_params;
 145                 protected ArrayList hoisted_locals;
 146
 147                 // Hoisted this
 148                 protected HoistedThis hoisted_this;
 149
 150                 // Local variable which holds this storey instance
 151                 public LocalTemporary Instance;
 152
 153                 public AnonymousMethodStorey (Block block, DeclSpace parent, MemberBase host, GenericMethod generic, string name)
 154                         : base (parent, generic, MakeMemberName (host, name, generic, block.StartLocation), Modifiers.PRIVATE)
 155                 {
 156                         Parent = parent;
 157                         OriginalSourceBlock = block;
 158                         ID = unique_id++;
 159                 }
 160
 161                 static MemberName MakeMemberName (MemberBase host, string name, GenericMethod generic, Location loc)
 162                 {
 163                         string host_name = host == null ? null : host.Name;
 164                         string tname = MakeName (host_name, "c", name, unique_id);
 165                         TypeArguments args = null;
 166                         if (generic != null) {
 167                                 args = new TypeArguments ();
 168                                 foreach (TypeParameter tparam in generic.CurrentTypeParameters)
 169                                         args.Add (new TypeParameterName (tparam.Name, null, loc));
 170                         }
 171
 172                         return new MemberName (tname, args, loc);
 173                 }
 174
 175                 public void AddCapturedThisField (EmitContext ec)
 176                 {
 177                         TypeExpr type_expr = new TypeExpression (ec.ContainerType, Location);
 178                         Field f = AddCompilerGeneratedField ("<>f__this", type_expr);
 179                         f.Define ();
 180                         hoisted_this = new HoistedThis (this, f);
 181                 }
 182
 183                 public Field AddCapturedVariable (string name, Type type)
 184                 {
 185                         CheckMembersDefined ();
 186
 187                         FullNamedExpression field_type = new TypeExpression (type, Location);
 188                         if (!IsGeneric)
 189                                 return AddCompilerGeneratedField (name, field_type);
 190
 191                         const int mod = Modifiers.INTERNAL | Modifiers.COMPILER_GENERATED;
 192                         Field f = new HoistedGenericField (this, field_type, mod, name, null, Location);
 193                         AddField (f);
 194                         return f;
 195                 }
 196
 197                 protected Field AddCompilerGeneratedField (string name, FullNamedExpression type)
 198                 {
 199                         const int mod = Modifiers.INTERNAL | Modifiers.COMPILER_GENERATED;
 200                         Field f = new Field (this, type, mod, new MemberName (name, Location), null);
 201                         AddField (f);
 202                         return f;
 203                 }
 204
 205                 //
 206                 // Creates a link between block and the anonymous method storey
 207                 //
 208                 // An anonymous method can reference variables from any outer block, but they are
 209                 // hoisted in their own ExplicitBlock. When more than one block is referenced we
 210                 // need to create another link between those variable storeys
 211                 //
 212                 public void AddReferenceFromChildrenBlock (ExplicitBlock block)
 213                 {
 214                         if (children_references == null)
 215                                 children_references = new ArrayList ();
 216
 217                         if (!children_references.Contains (block))
 218                                 children_references.Add (block);
 219                 }
 220
 221                 public void AddParentStoreyReference (AnonymousMethodStorey storey)
 222                 {
 223                         CheckMembersDefined ();
 224
 225                         if (used_parent_storeys == null)
 226                                 used_parent_storeys = new ArrayList ();
 227                         else if (used_parent_storeys.IndexOf (storey) != -1)
 228                                 return;
 229
 230                         TypeExpr type_expr = new TypeExpression (storey.TypeBuilder, Location);
 231                         Field f = AddCompilerGeneratedField ("<>f__ref$" + storey.ID, type_expr);
 232                         used_parent_storeys.Add (new StoreyFieldPair (storey, f));
 233                 }
 234
 235                 public void CaptureLocalVariable (EmitContext ec, LocalInfo local_info)
 236                 {
 237                         ec.CurrentBlock.Explicit.HasCapturedVariable = true;
 238                         if (ec.CurrentBlock.Explicit != local_info.Block.Explicit)
 239                                 AddReferenceFromChildrenBlock (ec.CurrentBlock.Explicit);
 240
 241                         if (local_info.HoistedVariableReference != null)
 242                                 return;
 243
 244                         HoistedVariable var = new HoistedLocalVariable (this, local_info, GetVariableMangledName (local_info));
 245                         local_info.HoistedVariableReference = var;
 246
 247                         if (hoisted_locals == null)
 248                                 hoisted_locals = new ArrayList ();
 249
 250                         hoisted_locals.Add (var);
 251                 }
 252
 253                 public void CaptureParameter (EmitContext ec, ParameterReference param_ref)
 254                 {
 255                         ec.CurrentBlock.Explicit.HasCapturedVariable = true;
 256                         AddReferenceFromChildrenBlock (ec.CurrentBlock.Explicit);
 257
 258                         if (param_ref.GetHoistedVariable (ec) != null)
 259                                 return;
 260
 261                         if (hoisted_params == null)
 262                                 hoisted_params = new ArrayList (2);
 263
 264                         HoistedVariable expr = new HoistedParameter (this, param_ref);
 265                         param_ref.Parameter.HoistedVariableReference = expr;
 266                         hoisted_params.Add (expr);
 267                 }
 268
 269                 public void ChangeParentStorey (AnonymousMethodStorey parentStorey)
 270                 {
 271                         Parent = parentStorey;
 272                         type_params = null;
 273                 }
 274
 275                 //
 276                 // Initializes all hoisted variables
 277                 //
 278                 public void EmitStoreyInstantiation (EmitContext ec)
 279                 {
 280                         // There can be only one instance variable for each storey type
 281                         if (Instance != null)
 282                                 throw new InternalErrorException ();
 283
 284                         SymbolWriter.OpenCompilerGeneratedBlock (ec.ig);
 285
 286                         //
 287                         // Create an instance of storey type
 288                         //
 289                         Expression storey_type_expr;
 290                         if (is_generic) {
 291                                 //
 292                                 // Use current method type parameter (MVAR) for top level storey only. All
 293                                 // nested storeys use class type parameter (VAR)
 294                                 //
 295                                 TypeParameter[] tparams = ec.CurrentAnonymousMethod != null && ec.CurrentAnonymousMethod.Storey != null ?
 296                                         ec.CurrentAnonymousMethod.Storey.TypeParameters :
 297                                         ec.GenericDeclContainer.TypeParameters;
 298
 299                                 TypeArguments targs = new TypeArguments ();
 300
 301                                 if (tparams.Length < CountTypeParameters) {
 302                                         TypeParameter[] parent_tparams = ec.DeclContainer.Parent.PartialContainer.TypeParameters;
 303                                         for (int i = 0; i < parent_tparams.Length; ++i)
 304                                                 targs.Add (new TypeParameterExpr (parent_tparams[i], Location));
 305                                 }
 306
 307                                 for (int i = 0; i < tparams.Length; ++i)
 308                                         targs.Add (new TypeParameterExpr (tparams[i], Location));
 309
 310                                 storey_type_expr = new GenericTypeExpr (TypeBuilder, targs, Location);
 311                         } else {
 312                                 storey_type_expr = new TypeExpression (TypeBuilder, Location);
 313                         }
 314
 315                         Expression e = new New (storey_type_expr, new ArrayList (0), Location).Resolve (ec);
 316                         e.Emit (ec);
 317
 318                         Instance = new LocalTemporary (storey_type_expr.Type);
 319                         Instance.Store (ec);
 320
 321                         EmitHoistedFieldsInitialization (ec);
 322
 323                         SymbolWriter.DefineScopeVariable (ID, Instance.Builder);
 324                         SymbolWriter.CloseCompilerGeneratedBlock (ec.ig);
 325                 }
 326
 327                 void EmitHoistedFieldsInitialization (EmitContext ec)
 328                 {
 329                         //
 330                         // Initialize all storey reference fields by using local or hoisted variables
 331                         //
 332                         if (used_parent_storeys != null) {
 333                                 foreach (StoreyFieldPair sf in used_parent_storeys) {
 334                                         //
 335                                         // Setting local field
 336                                         //
 337                                         Expression instace_expr = GetStoreyInstanceExpression (ec);
 338                                         FieldExpr f_set_expr = TypeManager.IsGenericType (instace_expr.Type) ?
 339                                                 new FieldExpr (sf.Field.FieldBuilder, instace_expr.Type, Location) :
 340                                                 new FieldExpr (sf.Field.FieldBuilder, Location);
 341                                         f_set_expr.InstanceExpression = instace_expr;
 342
 343                                         SimpleAssign a = new SimpleAssign (f_set_expr, sf.Storey.GetStoreyInstanceExpression (ec));
 344                                         if (a.Resolve (ec) != null)
 345                                                 a.EmitStatement (ec);
 346                                 }
 347                         }
 348
 349                         //
 350                         // Define hoisted `this' in top-level storey only
 351                         //
 352                         if (OriginalSourceBlock.Explicit.HasCapturedThis && !(Parent is AnonymousMethodStorey)) {
 353                                 AddCapturedThisField (ec);
 354                                 OriginalSourceBlock.AddScopeStatement (new ThisInitializer (hoisted_this));
 355                         }
 356
 357                         //
 358                         // Setting currect anonymous method to null blocks any further variable hoisting
 359                         //
 360                         AnonymousExpression ae = ec.CurrentAnonymousMethod;
 361                         ec.CurrentAnonymousMethod = null;
 362
 363                         if (hoisted_params != null) {
 364                                 EmitHoistedParameters (ec, hoisted_params);
 365                         }
 366
 367                         ec.CurrentAnonymousMethod = ae;
 368                 }
 369
 370                 protected virtual void EmitHoistedParameters (EmitContext ec, ArrayList hoisted)
 371                 {
 372                         foreach (HoistedParameter hp in hoisted) {
 373                                 hp.EmitHoistingAssignment (ec);
 374                         }
 375                 }
 376
 377                 public override void EmitType ()
 378                 {
 379                         SymbolWriter.DefineAnonymousScope (ID);
 380
 381                         if (hoisted_this != null)
 382                                 hoisted_this.EmitSymbolInfo ();
 383
 384                         if (hoisted_locals != null) {
 385                                 foreach (HoistedVariable local in hoisted_locals)
 386                                         local.EmitSymbolInfo ();
 387                         }
 388
 389                         if (hoisted_params != null) {
 390                                 foreach (HoistedParameter param in hoisted_params)
 391                                         param.EmitSymbolInfo ();
 392                         }
 393
 394                         if (used_parent_storeys != null) {
 395                                 foreach (StoreyFieldPair sf in used_parent_storeys) {
 396                                         SymbolWriter.DefineCapturedScope (ID, sf.Storey.ID, sf.Field.Name);
 397                                 }
 398                         }
 399
 400                         base.EmitType ();
 401                 }
 402
 403                 public AnonymousMethodStorey GetGenericStorey ()
 404                 {
 405                         DeclSpace storey = this;
 406                         while (storey != null && storey.CurrentTypeParameters.Length == 0)
 407                                 storey = storey.Parent;
 408
 409                         return storey as AnonymousMethodStorey;
 410                 }
 411
 412                 //
 413                 // Returns a field which holds referenced storey instance
 414                 //
 415                 Field GetReferencedStoreyField (AnonymousMethodStorey storey)
 416                 {
 417                         if (used_parent_storeys == null)
 418                                 return null;
 419
 420                         foreach (StoreyFieldPair sf in used_parent_storeys) {
 421                                 if (sf.Storey == storey)
 422                                         return sf.Field;
 423                         }
 424
 425                         return null;
 426                 }
 427
 428                 //
 429                 // Creates storey instance expression regardless of currect IP
 430                 //
 431                 public Expression GetStoreyInstanceExpression (EmitContext ec)
 432                 {
 433                         AnonymousExpression am = ec.CurrentAnonymousMethod;
 434
 435                         //
 436                         // Access from original block -> storey
 437                         //
 438                         if (am == null)
 439                                 return Instance;
 440
 441                         //
 442                         // Access from anonymous method implemented as a static -> storey
 443                         //
 444                         if (am.Storey == null)
 445                                 return Instance;
 446
 447                         Field f = am.Storey.GetReferencedStoreyField (this);
 448                         if (f == null) {
 449                                 if (am.Storey == this) {
 450                                         //
 451                                         // Access inside of same storey (S -> S)
 452                                         //
 453                                         return new CompilerGeneratedThis (TypeBuilder, Location);
 454                                 }
 455                                 //
 456                                 // External field access
 457                                 //
 458                                 return Instance;
 459                         }
 460
 461                         //
 462                         // Storey was cached to local field
 463                         //
 464                         FieldExpr f_ind = new FieldExpr (f.FieldBuilder, Location);
 465                         f_ind.InstanceExpression = new CompilerGeneratedThis (TypeBuilder, Location);
 466                         return f_ind;
 467                 }
 468
 469                 protected virtual string GetVariableMangledName (LocalInfo local_info)
 470                 {
 471                         //
 472                         // No need to mangle anonymous method hoisted variables cause they
 473                         // are hoisted in their own scopes
 474                         //
 475                         return local_info.Name;
 476                 }
 477
 478                 public HoistedThis HoistedThis {
 479                         get { return hoisted_this; }
 480                 }
 481
 482                 //
 483                 // Mutate type dispatcher
 484                 //
 485                 public Type MutateType (Type type)
 486                 {
 487 #if GMCS_SOURCE
 488                         if (TypeManager.IsGenericType (type))
 489                                 return MutateGenericType (type);
 490
 491                         if (TypeManager.IsGenericParameter (type))
 492                                 return MutateGenericArgument (type);
 493
 494                         if (type.IsArray)
 495                                 return MutateArrayType (type);
 496 #endif
 497                         return type;
 498                 }
 499
 500                 //
 501                 // Changes method type arguments (MVAR) to storey (VAR) type arguments
 502                 //
 503                 public MethodInfo MutateGenericMethod (MethodInfo method)
 504                 {
 505 #if GMCS_SOURCE
 506                         Type [] t_args = TypeManager.GetGenericArguments (method);
 507                         if (TypeManager.IsGenericType (method.DeclaringType)) {
 508                                 Type t = MutateGenericType (method.DeclaringType);
 509                                 if (t != method.DeclaringType) {
 510                                         method = (MethodInfo) TypeManager.DropGenericMethodArguments (method);
 511                                         if (method.Module == CodeGen.Module.Builder)
 512                                                 method = TypeBuilder.GetMethod (t, method);
 513                                         else
 514                                                 method = (MethodInfo) MethodInfo.GetMethodFromHandle (method.MethodHandle, t.TypeHandle);
 515                                 }
 516                         }
 517
 518                         if (t_args == null || t_args.Length == 0)
 519                                 return method;
 520
 521                         for (int i = 0; i < t_args.Length; ++i)
 522                                 t_args [i] = MutateType (t_args [i]);
 523
 524                         return method.GetGenericMethodDefinition ().MakeGenericMethod (t_args);
 525 #else
 526                         throw new NotSupportedException ();
 527 #endif
 528                 }
 529
 530                 public ConstructorInfo MutateConstructor (ConstructorInfo ctor)
 531                 {
 532 #if GMCS_SOURCE
 533                         if (TypeManager.IsGenericType (ctor.DeclaringType)) {
 534                                 Type t = MutateGenericType (ctor.DeclaringType);
 535                                 if (t != ctor.DeclaringType) {
 536                                         ctor = (ConstructorInfo) TypeManager.DropGenericMethodArguments (ctor);
 537                                         if (ctor.Module == CodeGen.Module.Builder)
 538                                                 return TypeBuilder.GetConstructor (t, ctor);
 539
 540                                         return (ConstructorInfo) ConstructorInfo.GetMethodFromHandle (ctor.MethodHandle, t.TypeHandle);
 541                                 }
 542                         }
 543 #endif
 544                         return ctor;
 545                 }
 546
 547                 public FieldInfo MutateField (FieldInfo field)
 548                 {
 549 #if GMCS_SOURCE
 550                         if (TypeManager.IsGenericType (field.DeclaringType)) {
 551                                 Type t = MutateGenericType (field.DeclaringType);
 552                                 if (t != field.DeclaringType) {
 553                                         // TODO: It should throw on imported types
 554                                         return TypeBuilder.GetField (t, field);
 555                                 }
 556                         }
 557 #endif
 558                         return field;
 559                 }
 560
 561 #if GMCS_SOURCE
 562                 protected Type MutateArrayType (Type array)
 563                 {
 564                         int rank = array.GetArrayRank ();
 565                         Type element = TypeManager.GetElementType (array);
 566                         if (element.IsArray) {
 567                                 element = MutateArrayType (element);
 568                         } else if (TypeManager.IsGenericParameter (element)) {
 569                                 element = MutateGenericArgument (element);
 570                         } else if (TypeManager.IsGenericType (element)) {
 571                                 element = MutateGenericType (element);
 572                         } else {
 573                                 return array;
 574                         }
 575
 576                         return element.MakeArrayType (rank);
 577                 }
 578
 579                 protected Type MutateGenericType (Type type)
 580                 {
 581                         Type [] t_args = TypeManager.GetTypeArguments (type);
 582                         if (t_args == null || t_args.Length == 0)
 583                                 return type;
 584
 585                         for (int i = 0; i < t_args.Length; ++i)
 586                                 t_args [i] = MutateType (t_args [i]);
 587
 588                         return type.GetGenericTypeDefinition ().MakeGenericType (t_args);
 589                 }
 590 #endif
 591
 592                 //
 593                 // Changes method generic argument (MVAR) to type generic argument (VAR)
 594                 //
 595                 public Type MutateGenericArgument (Type type)
 596                 {
 597                         foreach (TypeParameter tp in CurrentTypeParameters) {
 598                                 if (tp.Name == type.Name) {
 599                                         return tp.Type;
 600                                 }
 601                         }
 602
 603                         return type;
 604                 }
 605
 606                 public ArrayList ReferencesFromChildrenBlock {
 607                         get { return children_references; }
 608                 }
 609
 610                 public static void Reset ()
 611                 {
 612                         unique_id = 0;
 613                 }
 614         }
 615
 616         public abstract class HoistedVariable
 617         {
 618                 class ExpressionTreeProxy : Expression
 619                 {
 620                         readonly HoistedVariable hv;
 621
 622                         public ExpressionTreeProxy (HoistedVariable hv)
 623                         {
 624                                 this.hv = hv;
 625                         }
 626
 627                         public override Expression CreateExpressionTree (EmitContext ec)
 628                         {
 629                                 throw new NotSupportedException ("ET");
 630                         }
 631
 632                         public override Expression DoResolve (EmitContext ec)
 633                         {
 634                                 eclass = ExprClass.Value;
 635                                 type = TypeManager.expression_type_expr.Type;
 636                                 return this;
 637                         }
 638
 639                         public override void Emit (EmitContext ec)
 640                         {
 641                                 Expression e = hv.GetFieldExpression (ec).CreateExpressionTree (ec);
 642                                 // This should never fail
 643                                 e = e.Resolve (ec);
 644                                 if (e != null)
 645                                         e.Emit (ec);
 646                         }
 647                 }
 648
 649                 protected readonly AnonymousMethodStorey storey;
 650                 protected Field field;
 651                 Hashtable cached_inner_access; // TODO: Hashtable is too heavyweight
 652                 FieldExpr cached_outer_access;
 653
 654                 protected HoistedVariable (AnonymousMethodStorey storey, string name, Type type)
 655                         : this (storey, storey.AddCapturedVariable (name, type))
 656                 {
 657                 }
 658
 659                 protected HoistedVariable (AnonymousMethodStorey storey, Field field)
 660                 {
 661                         this.storey = storey;
 662                         this.field = field;
 663                 }
 664
 665                 public void AddressOf (EmitContext ec, AddressOp mode)
 666                 {
 667                         GetFieldExpression (ec).AddressOf (ec, mode);
 668                 }
 669
 670                 public Expression CreateExpressionTree (EmitContext ec)
 671                 {
 672                         return new ExpressionTreeProxy (this);
 673                 }
 674
 675                 public void Emit (EmitContext ec)
 676                 {
 677                         GetFieldExpression (ec).Emit (ec);
 678                 }
 679
 680                 //
 681                 // Creates field access expression for hoisted variable
 682                 //
 683                 protected FieldExpr GetFieldExpression (EmitContext ec)
 684                 {
 685                         if (ec.CurrentAnonymousMethod == null || ec.CurrentAnonymousMethod.Storey == null) {
 686                                 if (cached_outer_access != null)
 687                                         return cached_outer_access;
 688
 689                                 //
 690                                 // When setting top-level hoisted variable in generic storey
 691                                 // change storey generic types to method generic types (VAR -> MVAR)
 692                                 //
 693                                 cached_outer_access = storey.MemberName.IsGeneric ?
 694                                         new FieldExpr (field.FieldBuilder, storey.Instance.Type, field.Location) :
 695                                         new FieldExpr (field.FieldBuilder, field.Location);
 696
 697                                 cached_outer_access.InstanceExpression = storey.GetStoreyInstanceExpression (ec);
 698                                 cached_outer_access.Resolve (ec);
 699                                 return cached_outer_access;
 700                         }
 701
 702                         FieldExpr inner_access;
 703                         if (cached_inner_access != null) {
 704                                 inner_access = (FieldExpr) cached_inner_access [ec.CurrentAnonymousMethod];
 705                         } else {
 706                                 inner_access = null;
 707                                 cached_inner_access = new Hashtable (4);
 708                         }
 709
 710                         if (inner_access == null) {
 711                                 inner_access = new FieldExpr (field.FieldBuilder, field.Location);
 712                                 inner_access.InstanceExpression = storey.GetStoreyInstanceExpression (ec);
 713                                 inner_access.Resolve (ec);
 714                                 cached_inner_access.Add (ec.CurrentAnonymousMethod, inner_access);
 715                         }
 716
 717                         return inner_access;
 718                 }
 719
 720                 public abstract void EmitSymbolInfo ();
 721
 722                 public void Emit (EmitContext ec, bool leave_copy)
 723                 {
 724                         GetFieldExpression (ec).Emit (ec, leave_copy);
 725                 }
 726
 727                 public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool prepare_for_load)
 728                 {
 729                         GetFieldExpression (ec).EmitAssign (ec, source, leave_copy, false);
 730                 }
 731         }
 732
 733         class HoistedParameter : HoistedVariable
 734         {
 735                 sealed class HoistedFieldAssign : Assign
 736                 {
 737                         public HoistedFieldAssign (Expression target, Expression source)
 738                                 : base (target, source, source.Location)
 739                         {
 740                         }
 741
 742                         protected override Expression ResolveConversions (EmitContext ec)
 743                         {
 744                                 //
 745                                 // Implicit conversion check fails for hoisted type arguments
 746                                 // as they are of different types (!!0 x !0)
 747                                 //
 748                                 return this;
 749                         }
 750                 }
 751
 752                 readonly ParameterReference parameter;
 753
 754                 public HoistedParameter (AnonymousMethodStorey scope, ParameterReference par)
 755                         : base (scope, par.Name, par.Type)
 756                 {
 757                         this.parameter = par;
 758                 }
 759
 760                 public HoistedParameter (HoistedParameter hp, string name)
 761                         : base (hp.storey, name, hp.parameter.Type)
 762                 {
 763                         this.parameter = hp.parameter;
 764                 }
 765
 766                 public void EmitHoistingAssignment (EmitContext ec)
 767                 {
 768                         //
 769                         // Remove hoisted redirection to emit assignment from original parameter
 770                         //
 771                         HoistedVariable temp = parameter.Parameter.HoistedVariableReference;
 772                         parameter.Parameter.HoistedVariableReference = null;
 773
 774                         Assign a = new HoistedFieldAssign (GetFieldExpression (ec), parameter);
 775                         if (a.Resolve (ec) != null)
 776                                 a.EmitStatement (ec);
 777
 778                         parameter.Parameter.HoistedVariableReference = temp;
 779                 }
 780
 781                 public override void EmitSymbolInfo ()
 782                 {
 783                         SymbolWriter.DefineCapturedParameter (storey.ID, field.Name, field.Name);
 784                 }
 785
 786                 public Field Field {
 787                         get { return field; }
 788                 }
 789         }
 790
 791         class HoistedLocalVariable : HoistedVariable
 792         {
 793                 readonly string name;
 794
 795                 public HoistedLocalVariable (AnonymousMethodStorey scope, LocalInfo local, string name)
 796                         : base (scope, name, local.VariableType)
 797                 {
 798                         this.name = local.Name;
 799                 }
 800
 801                 public override void EmitSymbolInfo ()
 802                 {
 803                         SymbolWriter.DefineCapturedLocal (storey.ID, name, field.Name);
 804                 }
 805         }
 806
 807         public class HoistedThis : HoistedVariable
 808         {
 809                 public HoistedThis (AnonymousMethodStorey storey, Field field)
 810                         : base (storey, field)
 811                 {
 812                 }
 813
 814                 public void EmitHoistingAssignment (EmitContext ec)
 815                 {
 816                         SimpleAssign a = new SimpleAssign (GetFieldExpression (ec), ec.GetThis (field.Location));
 817                         if (a.Resolve (ec) != null)
 818                                 a.EmitStatement (ec);
 819                 }
 820
 821                 public override void EmitSymbolInfo ()
 822                 {
 823                         SymbolWriter.DefineCapturedThis (storey.ID, field.Name);
 824                 }
 825
 826                 public Field Field {
 827                         get { return field; }
 828                 }
 829         }
 830
 831         //
 832         // Anonymous method expression as created by parser
 833         //
 834         public class AnonymousMethodExpression : Expression
 835         {
 836                 ListDictionary compatibles;
 837                 public ToplevelBlock Block;
 838
 839                 public AnonymousMethodExpression (Location loc)
 840                 {
 841                         this.loc = loc;
 842                         this.compatibles = new ListDictionary ();
 843                 }
 844
 845                 public override string ExprClassName {
 846                         get {
 847                                 return "anonymous method";
 848                         }
 849                 }
 850
 851                 public virtual bool HasExplicitParameters {
 852                         get {
 853                                 return Parameters != ParametersCompiled.Undefined;
 854                         }
 855                 }
 856
 857                 public ParametersCompiled Parameters {
 858                         get { return Block.Parameters; }
 859                 }
 860
 861                 //
 862                 // Returns true if the body of lambda expression can be implicitly
 863                 // converted to the delegate of type `delegate_type'
 864                 //
 865                 public bool ImplicitStandardConversionExists (EmitContext ec, Type delegate_type)
 866                 {
 867                         using (ec.Set (EmitContext.Flags.ProbingMode)) {
 868                                 return Compatible (ec, delegate_type) != null;
 869                         }
 870                 }
 871
 872                 protected Type CompatibleChecks (EmitContext ec, Type delegate_type)
 873                 {
 874                         if (TypeManager.IsDelegateType (delegate_type))
 875                                 return delegate_type;
 876
 877 #if GMCS_SOURCE
 878                         if (TypeManager.DropGenericTypeArguments (delegate_type) == TypeManager.expression_type) {
 879                                 delegate_type = TypeManager.GetTypeArguments (delegate_type) [0];
 880                                 if (TypeManager.IsDelegateType (delegate_type))
 881                                         return delegate_type;
 882
 883                                 Report.Error (835, loc, "Cannot convert `{0}' to an expression tree of non-delegate type `{1}'",
 884                                         GetSignatureForError (), TypeManager.CSharpName (delegate_type));
 885                                 return null;
 886                         }
 887 #endif
 888
 889                         Report.Error (1660, loc, "Cannot convert `{0}' to non-delegate type `{1}'",
 890                                       GetSignatureForError (), TypeManager.CSharpName (delegate_type));
 891                         return null;
 892                 }
 893
 894                 protected bool VerifyExplicitParameters (Type delegate_type, AParametersCollection parameters, bool ignore_error)
 895                 {
 896                         if (VerifyParameterCompatibility (delegate_type, parameters, ignore_error))
 897                                 return true;
 898
 899                         if (!ignore_error)
 900                                 Report.Error (1661, loc,
 901                                         "Cannot convert `{0}' to delegate type `{1}' since there is a parameter mismatch",
 902                                         GetSignatureForError (), TypeManager.CSharpName (delegate_type));
 903
 904                         return false;
 905                 }
 906
 907                 protected bool VerifyParameterCompatibility (Type delegate_type, AParametersCollection invoke_pd, bool ignore_errors)
 908                 {
 909                         if (Parameters.Count != invoke_pd.Count) {
 910                                 if (ignore_errors)
 911                                         return false;
 912
 913                                 Report.Error (1593, loc, "Delegate `{0}' does not take `{1}' arguments",
 914                                               TypeManager.CSharpName (delegate_type), Parameters.Count.ToString ());
 915                                 return false;
 916                         }
 917
 918                         bool has_implicit_parameters = !HasExplicitParameters;
 919                         bool error = false;
 920
 921                         for (int i = 0; i < Parameters.Count; ++i) {
 922                                 Parameter.Modifier p_mod = invoke_pd.FixedParameters [i].ModFlags;
 923                                 if (Parameters.FixedParameters [i].ModFlags != p_mod && p_mod != Parameter.Modifier.PARAMS) {
 924                                         if (ignore_errors)
 925                                                 return false;
 926
 927                                         if (p_mod == Parameter.Modifier.NONE)
 928                                                 Report.Error (1677, loc, "Parameter `{0}' should not be declared with the `{1}' keyword",
 929                                                               (i + 1).ToString (), Parameter.GetModifierSignature (Parameters.FixedParameters [i].ModFlags));
 930                                         else
 931                                                 Report.Error (1676, loc, "Parameter `{0}' must be declared with the `{1}' keyword",
 932                                                               (i+1).ToString (), Parameter.GetModifierSignature (p_mod));
 933                                         error = true;
 934                                 }
 935
 936                                 if (has_implicit_parameters)
 937                                         continue;
 938
 939                                 Type type = invoke_pd.Types [i];
 940
 941                                 // We assume that generic parameters are always inflated
 942                                 if (TypeManager.IsGenericParameter (type))
 943                                         continue;
 944
 945                                 if (TypeManager.HasElementType (type) && TypeManager.IsGenericParameter (TypeManager.GetElementType (type)))
 946                                         continue;
 947
 948                                 if (invoke_pd.Types [i] != Parameters.Types [i]) {
 949                                         if (ignore_errors)
 950                                                 return false;
 951
 952                                         Report.Error (1678, loc, "Parameter `{0}' is declared as type `{1}' but should be `{2}'",
 953                                                       (i+1).ToString (),
 954                                                       TypeManager.CSharpName (Parameters.Types [i]),
 955                                                       TypeManager.CSharpName (invoke_pd.Types [i]));
 956                                         error = true;
 957                                 }
 958                         }
 959
 960                         return !error;
 961                 }
 962
 963                 //
 964                 // Infers type arguments based on explicit arguments
 965                 //
 966                 public bool ExplicitTypeInference (TypeInferenceContext type_inference, Type delegate_type)
 967                 {
 968                         if (!HasExplicitParameters)
 969                                 return false;
 970
 971                         if (!TypeManager.IsDelegateType (delegate_type)) {
 972 #if GMCS_SOURCE
 973                                 if (TypeManager.DropGenericTypeArguments (delegate_type) != TypeManager.expression_type)
 974                                         return false;
 975
 976                                 delegate_type = delegate_type.GetGenericArguments () [0];
 977                                 if (!TypeManager.IsDelegateType (delegate_type))
 978                                         return false;
 979 #else
 980                                 return false;
 981 #endif
 982                         }
 983
 984                         AParametersCollection d_params = TypeManager.GetDelegateParameters (delegate_type);
 985                         if (d_params.Count != Parameters.Count)
 986                                 return false;
 987
 988                         for (int i = 0; i < Parameters.Count; ++i) {
 989                                 Type itype = d_params.Types [i];
 990                                 if (!TypeManager.IsGenericParameter (itype)) {
 991                                         if (!TypeManager.HasElementType (itype))
 992                                                 continue;
 993
 994                                         if (!TypeManager.IsGenericParameter (TypeManager.GetElementType (itype)))
 995                                             continue;
 996                                 }
 997                                 type_inference.ExactInference (Parameters.Types [i], itype);
 998                         }
 999                         return true;
1000                 }
1001
1002                 public Type InferReturnType (EmitContext ec, TypeInferenceContext tic, Type delegate_type)
1003                 {
1004                         AnonymousMethodBody am;
1005                         using (ec.Set (EmitContext.Flags.ProbingMode | EmitContext.Flags.InferReturnType)) {
1006                                 am = CompatibleMethod (ec, tic, GetType (), delegate_type);
1007                         }
1008
1009                         if (am == null)
1010                                 return null;
1011
1012                         // Stop referencing gmcs NullLiteral type
1013                         if (am.ReturnType == TypeManager.null_type)
1014                                 am.ReturnType = null;
1015
1016                         return am.ReturnType;
1017                 }
1018
1019                 //
1020                 // Returns AnonymousMethod container if this anonymous method
1021                 // expression can be implicitly converted to the delegate type `delegate_type'
1022                 //
1023                 public Expression Compatible (EmitContext ec, Type type)
1024                 {
1025                         Expression am = (Expression) compatibles [type];
1026                         if (am != null)
1027                                 return am;
1028
1029                         Type delegate_type = CompatibleChecks (ec, type);
1030                         if (delegate_type == null)
1031                                 return null;
1032
1033                         //
1034                         // At this point its the first time we know the return type that is
1035                         // needed for the anonymous method.  We create the method here.
1036                         //
1037
1038                         MethodInfo invoke_mb = Delegate.GetInvokeMethod (
1039                                 ec.ContainerType, delegate_type);
1040                         Type return_type = TypeManager.TypeToCoreType (invoke_mb.ReturnType);
1041
1042 #if MS_COMPATIBLE
1043                         Type[] g_args = delegate_type.GetGenericArguments ();
1044                         if (return_type.IsGenericParameter)
1045                                 return_type = g_args [return_type.GenericParameterPosition];
1046 #endif
1047
1048                         //
1049                         // Second: the return type of the delegate must be compatible with
1050                         // the anonymous type.   Instead of doing a pass to examine the block
1051                         // we satisfy the rule by setting the return type on the EmitContext
1052                         // to be the delegate type return type.
1053                         //
1054
1055                         try {
1056                                 int errors = Report.Errors;
1057                                 am = CompatibleMethod (ec, null, return_type, delegate_type);
1058                                 if (am != null && delegate_type != type && errors == Report.Errors)
1059                                         am = CreateExpressionTree (ec, delegate_type);
1060
1061                                 if (!ec.IsInProbingMode)
1062                                         compatibles.Add (type, am == null ? EmptyExpression.Null : am);
1063
1064                                 return am;
1065                         } catch (Exception e) {
1066                                 throw new InternalErrorException (e, loc);
1067                         }
1068                 }
1069
1070                 protected virtual Expression CreateExpressionTree (EmitContext ec, Type delegate_type)
1071                 {
1072                         return CreateExpressionTree (ec);
1073                 }
1074
1075                 public override Expression CreateExpressionTree (EmitContext ec)
1076                 {
1077                         Report.Error (1946, loc, "An anonymous method cannot be converted to an expression tree");
1078                         return null;
1079                 }
1080
1081                 protected virtual ParametersCompiled ResolveParameters (EmitContext ec, TypeInferenceContext tic, Type delegate_type)
1082                 {
1083                         AParametersCollection delegate_parameters = TypeManager.GetDelegateParameters (delegate_type);
1084
1085                         if (Parameters == ParametersCompiled.Undefined) {
1086                                 //
1087                                 // We provide a set of inaccessible parameters
1088                                 //
1089                                 Parameter[] fixedpars = new Parameter[delegate_parameters.Count];
1090
1091                                 for (int i = 0; i < delegate_parameters.Count; i++) {
1092                                         Parameter.Modifier i_mod = delegate_parameters.FixedParameters [i].ModFlags;
1093                                         if (i_mod == Parameter.Modifier.OUT) {
1094                                                 Report.Error (1688, loc, "Cannot convert anonymous " +
1095                                                                   "method block without a parameter list " +
1096                                                                   "to delegate type `{0}' because it has " +
1097                                                                   "one or more `out' parameters.",
1098                                                                   TypeManager.CSharpName (delegate_type));
1099                                                 return null;
1100                                         }
1101                                         fixedpars[i] = new Parameter (
1102                                                 null, null,
1103                                                 delegate_parameters.FixedParameters [i].ModFlags, null, loc);
1104                                 }
1105
1106                                 return ParametersCompiled.CreateFullyResolved (fixedpars, delegate_parameters.Types);
1107                         }
1108
1109                         if (!VerifyExplicitParameters (delegate_type, delegate_parameters, ec.IsInProbingMode)) {
1110                                 return null;
1111                         }
1112
1113                         return Parameters;
1114                 }
1115
1116                 public override Expression DoResolve (EmitContext ec)
1117                 {
1118                         if (!ec.IsAnonymousMethodAllowed) {
1119                                 Report.Error (1706, loc, "Anonymous methods and lambda expressions cannot be used in the current context");
1120                                 return null;
1121                         }
1122
1123                         //
1124                         // Set class type, set type
1125                         //
1126
1127                         eclass = ExprClass.Value;
1128
1129                         //
1130                         // This hack means `The type is not accessible
1131                         // anywhere', we depend on special conversion
1132                         // rules.
1133                         //
1134                         type = TypeManager.anonymous_method_type;
1135
1136                         if ((Parameters != null) && !Parameters.Resolve (ec))
1137                                 return null;
1138
1139                         // FIXME: The emitted code isn't very careful about reachability
1140                         // so, ensure we have a 'ret' at the end
1141                         if (ec.CurrentBranching != null &&
1142                             ec.CurrentBranching.CurrentUsageVector.IsUnreachable)
1143                                 ec.NeedReturnLabel ();
1144
1145                         return this;
1146                 }
1147
1148                 public override void Emit (EmitContext ec)
1149                 {
1150                         // nothing, as we only exist to not do anything.
1151                 }
1152
1153                 public static void Error_AddressOfCapturedVar (IVariableReference var, Location loc)
1154                 {
1155                         Report.Error (1686, loc,
1156                                 "Local variable or parameter `{0}' cannot have their address taken and be used inside an anonymous method or lambda expression",
1157                                 var.Name);
1158                 }
1159
1160                 public override string GetSignatureForError ()
1161                 {
1162                         return ExprClassName;
1163                 }
1164
1165                 protected AnonymousMethodBody CompatibleMethod (EmitContext ec, TypeInferenceContext tic, Type return_type, Type delegate_type)
1166                 {
1167                         ParametersCompiled p = ResolveParameters (ec, tic, delegate_type);
1168                         if (p == null)
1169                                 return null;
1170
1171                         ToplevelBlock b = ec.IsInProbingMode ? (ToplevelBlock) Block.PerformClone () : Block;
1172
1173                         AnonymousMethodBody anonymous = CompatibleMethodFactory (return_type, delegate_type, p, b);
1174                         if (!anonymous.Compatible (ec))
1175                                 return null;
1176
1177                         return anonymous;
1178                 }
1179
1180                 protected virtual AnonymousMethodBody CompatibleMethodFactory (Type return_type, Type delegate_type, ParametersCompiled p, ToplevelBlock b)
1181                 {
1182                         return new AnonymousMethodBody (p, b, return_type, delegate_type, loc);
1183                 }
1184
1185                 protected override void CloneTo (CloneContext clonectx, Expression t)
1186                 {
1187                         AnonymousMethodExpression target = (AnonymousMethodExpression) t;
1188
1189                         target.Block = (ToplevelBlock) clonectx.LookupBlock (Block);
1190                 }
1191         }
1192
1193         //
1194         // Abstract expression for any block which requires variables hoisting
1195         //
1196         public abstract class AnonymousExpression : Expression
1197         {
1198                 protected class AnonymousMethodMethod : Method
1199                 {
1200                         public readonly AnonymousExpression AnonymousMethod;
1201                         public readonly AnonymousMethodStorey Storey;
1202                         readonly string RealName;
1203
1204                         public AnonymousMethodMethod (DeclSpace parent, AnonymousExpression am, AnonymousMethodStorey storey,
1205                                                           GenericMethod generic, TypeExpr return_type,
1206                                                           int mod, string real_name, MemberName name,
1207                                                           ParametersCompiled parameters)
1208                                 : base (parent, generic, return_type, mod | Modifiers.COMPILER_GENERATED,
1209                                                 name, parameters, null)
1210                         {
1211                                 this.AnonymousMethod = am;
1212                                 this.Storey = storey;
1213                                 this.RealName = real_name;
1214
1215                                 Parent.PartialContainer.AddMethod (this);
1216                                 Block = am.Block;
1217                         }
1218
1219                         public override EmitContext CreateEmitContext (DeclSpace tc, ILGenerator ig)
1220                         {
1221                                 EmitContext aec = AnonymousMethod.aec;
1222                                 aec.ig = ig;
1223                                 aec.IsStatic = (ModFlags & Modifiers.STATIC) != 0;
1224                                 return aec;
1225                         }
1226
1227                         protected override bool ResolveMemberType ()
1228                         {
1229                                 if (!base.ResolveMemberType ())
1230                                         return false;
1231
1232                                 if (Storey != null && Storey.IsGeneric) {
1233                                         AnonymousMethodStorey gstorey = Storey.GetGenericStorey ();
1234                                         if (gstorey != null) {
1235                                                 if (!Parameters.IsEmpty) {
1236                                                         Type [] ptypes = Parameters.Types;
1237                                                         for (int i = 0; i < ptypes.Length; ++i)
1238                                                                 ptypes [i] = gstorey.MutateType (ptypes [i]);
1239                                                 }
1240
1241                                                 member_type = gstorey.MutateType (member_type);
1242                                         }
1243                                 }
1244
1245                                 return true;
1246                         }
1247
1248                         public override void Emit ()
1249                         {
1250                                 //
1251                                 // Before emitting any code we have to change all MVAR references to VAR
1252                                 // when the method is of generic type and has hoisted variables
1253                                 //
1254                                 if (Storey == Parent && Storey.IsGeneric) {
1255                                         AnonymousMethodStorey gstorey = Storey.GetGenericStorey ();
1256                                         if (gstorey != null) {
1257                                                 AnonymousMethod.aec.ReturnType = gstorey.MutateType (ReturnType);
1258                                                 block.MutateHoistedGenericType (gstorey);
1259                                         }
1260                                 }
1261
1262                                 if (MethodBuilder == null) {
1263                                         Define ();
1264                                 }
1265
1266                                 base.Emit ();
1267                         }
1268
1269                         public override void EmitExtraSymbolInfo (SourceMethod source)
1270                         {
1271                                 source.SetRealMethodName (RealName);
1272                         }
1273                 }
1274
1275                 //
1276                 // The block that makes up the body for the anonymous method
1277                 //
1278                 protected readonly ToplevelBlock Block;
1279
1280                 public Type ReturnType;
1281                 protected EmitContext aec;
1282
1283                 protected AnonymousExpression (ToplevelBlock block, Type return_type, Location loc)
1284                 {
1285                         this.ReturnType = return_type;
1286                         this.Block = block;
1287                         this.loc = loc;
1288                 }
1289
1290                 public abstract string ContainerType { get; }
1291                 public abstract bool IsIterator { get; }
1292                 public abstract AnonymousMethodStorey Storey { get; }
1293
1294                 public bool Compatible (EmitContext ec)
1295                 {
1296                         // TODO: Implement clone
1297                         aec = new EmitContext (
1298                                 ec.ResolveContext, ec.TypeContainer, ec.DeclContainer,
1299                                 Location, null, ReturnType,
1300                                 (ec.InUnsafe ? Modifiers.UNSAFE : 0), /* No constructor */ false);
1301
1302                         aec.CurrentAnonymousMethod = this;
1303                         aec.IsStatic = ec.IsStatic;
1304
1305                         IDisposable aec_dispose = null;
1306                         EmitContext.Flags flags = 0;
1307                         if (ec.InferReturnType)
1308                                 flags |= EmitContext.Flags.InferReturnType;
1309
1310                         if (ec.IsInProbingMode)
1311                                 flags |= EmitContext.Flags.ProbingMode;
1312
1313                         if (ec.IsInFieldInitializer)
1314                                 flags |= EmitContext.Flags.InFieldInitializer;
1315
1316                         if (ec.IsInUnsafeScope)
1317                                 flags |= EmitContext.Flags.InUnsafe;
1318
1319                         // HACK: Flag with 0 cannot be set
1320                         if (flags != 0)
1321                                 aec_dispose = aec.Set (flags);
1322
1323                         bool unreachable;
1324                         bool res = aec.ResolveTopBlock (ec, Block, Block.Parameters, null, out unreachable);
1325
1326                         if (ec.InferReturnType)
1327                                 ReturnType = aec.ReturnType;
1328
1329                         if (aec_dispose != null) {
1330                                 aec_dispose.Dispose ();
1331                         }
1332
1333                         return res;
1334                 }
1335
1336                 public void SetHasThisAccess ()
1337                 {
1338                         Block.HasCapturedThis = true;
1339                         ExplicitBlock b = Block.Parent.Explicit;
1340
1341                         while (b != null) {
1342                                 if (b.HasCapturedThis)
1343                                         return;
1344
1345                                 b.HasCapturedThis = true;
1346                                 b = b.Parent == null ? null : b.Parent.Explicit;
1347                         }
1348                 }
1349         }
1350
1351         public class AnonymousMethodBody : AnonymousExpression
1352         {
1353                 protected readonly ParametersCompiled parameters;
1354                 AnonymousMethodStorey storey;
1355
1356                 AnonymousMethodMethod method;
1357                 Field am_cache;
1358
1359                 static int unique_id;
1360
1361                 public AnonymousMethodBody (ParametersCompiled parameters,
1362                                         ToplevelBlock block, Type return_type, Type delegate_type,
1363                                         Location loc)
1364                         : base (block, return_type, loc)
1365                 {
1366                         this.type = delegate_type;
1367                         this.parameters = parameters;
1368                 }
1369
1370                 public override string ContainerType {
1371                         get { return "anonymous method"; }
1372                 }
1373
1374                 public override AnonymousMethodStorey Storey {
1375                         get { return storey; }
1376                 }
1377
1378                 public override bool IsIterator {
1379                         get { return false; }
1380                 }
1381
1382                 public override Expression CreateExpressionTree (EmitContext ec)
1383                 {
1384                         Report.Error (1945, loc, "An expression tree cannot contain an anonymous method expression");
1385                         return null;
1386                 }
1387
1388                 bool Define (EmitContext ec)
1389                 {
1390                         if (aec == null && !Compatible (ec))
1391                                 return false;
1392
1393                         return true;
1394                 }
1395
1396                 //
1397                 // Creates a host for the anonymous method
1398                 //
1399                 AnonymousMethodMethod DoCreateMethodHost (EmitContext ec)
1400                 {
1401                         //
1402                         // Anonymous method body can be converted to
1403                         //
1404                         // 1, an instance method in current scope when only `this' is hoisted
1405                         // 2, a static method in current scope when neither `this' nor any variable is hoisted
1406                         // 3, an instance method in compiler generated storey when any hoisted variable exists
1407                         //
1408
1409                         int modifiers;
1410                         if (Block.HasCapturedVariable || Block.HasCapturedThis) {
1411                                 storey = FindBestMethodStorey ();
1412                                 modifiers = storey != null ? Modifiers.INTERNAL : Modifiers.PRIVATE;
1413                         } else {
1414                                 if (ec.CurrentAnonymousMethod != null)
1415                                         storey = ec.CurrentAnonymousMethod.Storey;
1416
1417                                 modifiers = Modifiers.STATIC | Modifiers.PRIVATE;
1418                         }
1419
1420                         DeclSpace parent = storey != null ? storey : ec.TypeContainer;
1421
1422                         MemberCore mc = ec.ResolveContext as MemberCore;
1423                         string name = CompilerGeneratedClass.MakeName (parent != storey ? mc.Name : null,
1424                                 "m", null, unique_id++);
1425
1426                         MemberName member_name;
1427                         GenericMethod generic_method;
1428                         if (storey == null && mc.MemberName.IsGeneric) {
1429                                 member_name = new MemberName (name, mc.MemberName.TypeArguments.Clone (), Location);
1430
1431                                 generic_method = new GenericMethod (parent.NamespaceEntry, parent, member_name,
1432                                         new TypeExpression (ReturnType, Location), parameters);
1433
1434                                 ArrayList list = new ArrayList ();
1435                                 foreach (TypeParameter tparam in ((IMethodData)mc).GenericMethod.CurrentTypeParameters) {
1436                                         if (tparam.Constraints != null)
1437                                                 list.Add (tparam.Constraints.Clone ());
1438                                 }
1439                                 generic_method.SetParameterInfo (list);
1440                         } else {
1441                                 member_name = new MemberName (name, Location);
1442                                 generic_method = null;
1443                         }
1444
1445                         string real_name = String.Format (
1446                                 "{0}~{1}{2}", mc.GetSignatureForError (), GetSignatureForError (),
1447                                 parameters.GetSignatureForError ());
1448
1449                         return new AnonymousMethodMethod (parent,
1450                                 this, storey, generic_method, new TypeExpression (ReturnType, Location), modifiers,
1451                                 real_name, member_name, parameters);
1452                 }
1453
1454                 public override Expression DoResolve (EmitContext ec)
1455                 {
1456                         if (eclass == ExprClass.Invalid) {
1457                                 if (!Define (ec))
1458                                         return null;
1459                         }
1460
1461                         eclass = ExprClass.Value;
1462                         return this;
1463                 }
1464
1465                 public override void Emit (EmitContext ec)
1466                 {
1467                         //
1468                         // Use same anonymous method implementation for scenarios where same
1469                         // code is used from multiple blocks, e.g. field initializers
1470                         //
1471                         if (method == null) {
1472                                 //
1473                                 // Delay an anonymous method definition to avoid emitting unused code
1474                                 // for unreachable blocks or expression trees
1475                                 //
1476                                 method = DoCreateMethodHost (ec);
1477                                 method.Define ();
1478                         }
1479
1480                         bool is_static = (method.ModFlags & Modifiers.STATIC) != 0;
1481                         if (is_static && am_cache == null) {
1482                                 //
1483                                 // Creates a field cache to store delegate instance if it's not generic
1484                                 //
1485                                 if (!method.MemberName.IsGeneric) {
1486                                         TypeContainer parent = method.Parent.PartialContainer;
1487                                         int id = parent.Fields == null ? 0 : parent.Fields.Count;
1488                                         am_cache = new Field (parent, new TypeExpression (type, loc),
1489                                                 Modifiers.STATIC | Modifiers.PRIVATE | Modifiers.COMPILER_GENERATED,
1490                                                 new MemberName (CompilerGeneratedClass.MakeName (null, "f", "am$cache", id), loc), null);
1491                                         am_cache.Define ();
1492                                         parent.AddField (am_cache);
1493                                 } else {
1494                                         // TODO: Implement caching of generated generic static methods
1495                                         //
1496                                         // Idea:
1497                                         //
1498                                         // Some extra class is needed to capture variable generic type
1499                                         // arguments. Maybe we could re-use anonymous types, with a unique
1500                                         // anonymous method id, but they are quite heavy.
1501                                         //
1502                                         // Consider : "() => typeof(T);"
1503                                         //
1504                                         // We need something like
1505                                         // static class Wrap<Tn, Tm, DelegateType> {
1506                                         //              public static DelegateType cache;
1507                                         // }
1508                                         //
1509                                         // We then specialize local variable to capture all generic parameters
1510                                         // and delegate type, e.g. "Wrap<Ta, Tb, DelegateTypeInst> cache;"
1511                                         //
1512                                 }
1513                         }
1514
1515                         ILGenerator ig = ec.ig;
1516                         Label l_initialized = ig.DefineLabel ();
1517
1518                         if (am_cache != null) {
1519                                 ig.Emit (OpCodes.Ldsfld, am_cache.FieldBuilder);
1520                                 ig.Emit (OpCodes.Brtrue_S, l_initialized);
1521                         }
1522
1523                         //
1524                         // Load method delegate implementation
1525                         //
1526
1527                         if (is_static) {
1528                                 ig.Emit (OpCodes.Ldnull);
1529                         } else if (storey != null) {
1530                                 Expression e = storey.GetStoreyInstanceExpression (ec).Resolve (ec);
1531                                 if (e != null)
1532                                         e.Emit (ec);
1533                         } else {
1534                                 ig.Emit (OpCodes.Ldarg_0);
1535                         }
1536
1537                         MethodInfo delegate_method = method.MethodBuilder;
1538 #if GMCS_SOURCE
1539                         if (storey != null && storey.MemberName.IsGeneric) {
1540                                 Type t = storey.Instance.Type;
1541
1542                                 //
1543                                 // Mutate anonymous method instance type if we are in nested
1544                                 // hoisted generic anonymous method storey
1545                                 //
1546                                 if (ec.CurrentAnonymousMethod != null &&
1547                                         ec.CurrentAnonymousMethod.Storey != null &&
1548                                         ec.CurrentAnonymousMethod.Storey.IsGeneric) {
1549                                         t = storey.GetGenericStorey ().MutateType (t);
1550                                 }
1551
1552                                 delegate_method = TypeBuilder.GetMethod (t, delegate_method);
1553                         }
1554 #endif
1555                         ig.Emit (OpCodes.Ldftn, delegate_method);
1556
1557                         ConstructorInfo constructor_method = Delegate.GetConstructor (ec.ContainerType, type);
1558 #if MS_COMPATIBLE
1559             if (type.IsGenericType && type is TypeBuilder)
1560                 constructor_method = TypeBuilder.GetConstructor (type, constructor_method);
1561 #endif
1562                         ig.Emit (OpCodes.Newobj, constructor_method);
1563
1564                         if (am_cache != null) {
1565                                 ig.Emit (OpCodes.Stsfld, am_cache.FieldBuilder);
1566                                 ig.MarkLabel (l_initialized);
1567                                 ig.Emit (OpCodes.Ldsfld, am_cache.FieldBuilder);
1568                         }
1569                 }
1570
1571                 //
1572                 // Look for the best storey for this anonymous method
1573                 //
1574                 AnonymousMethodStorey FindBestMethodStorey ()
1575                 {
1576                         //
1577                         // Use the nearest parent block which has a storey
1578                         //
1579                         for (Block b = Block.Parent; b != null; b = b.Parent) {
1580                                 AnonymousMethodStorey s = b.Explicit.AnonymousMethodStorey;
1581                                 if (s != null)
1582                                         return s;
1583                         }
1584
1585                         return null;
1586                 }
1587
1588                 public override string GetSignatureForError ()
1589                 {
1590                         return TypeManager.CSharpName (type);
1591                 }
1592
1593                 public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
1594                 {
1595                         type = storey.MutateType (type);
1596                 }
1597
1598                 public static void Reset ()
1599                 {
1600                         unique_id = 0;
1601                 }
1602         }
1603
1604         //
1605         // Anonymous type container
1606         //
1607         public class AnonymousTypeClass : CompilerGeneratedClass
1608         {
1609                 sealed class AnonymousParameters : ParametersCompiled
1610                 {
1611                         public AnonymousParameters (params Parameter[] parameters)
1612                                 : base (parameters)
1613                         {
1614                         }
1615
1616                         protected override void ErrorDuplicateName (Parameter p)
1617                         {
1618                                 Report.Error (833, p.Location, "`{0}': An anonymous type cannot have multiple properties with the same name",
1619                                         p.Name);
1620                         }
1621                 }
1622
1623                 static int types_counter;
1624                 public const string ClassNamePrefix = "<>__AnonType";
1625                 public const string SignatureForError = "anonymous type";
1626
1627                 readonly ArrayList parameters;
1628
1629                 private AnonymousTypeClass (DeclSpace parent, MemberName name, ArrayList parameters, Location loc)
1630                         : base (parent, name, (RootContext.EvalMode ? Modifiers.PUBLIC : 0) | Modifiers.SEALED)
1631                 {
1632                         this.parameters = parameters;
1633                 }
1634
1635                 public static AnonymousTypeClass Create (TypeContainer parent, ArrayList parameters, Location loc)
1636                 {
1637                         if (RootContext.Version <= LanguageVersion.ISO_2)
1638                                 Report.FeatureIsNotAvailable (loc, "anonymous types");
1639
1640                         string name = ClassNamePrefix + types_counter++;
1641
1642                         SimpleName [] t_args = new SimpleName [parameters.Count];
1643                         TypeParameterName [] t_params = new TypeParameterName [parameters.Count];
1644                         Parameter [] ctor_params = new Parameter [parameters.Count];
1645                         for (int i = 0; i < parameters.Count; ++i) {
1646                                 AnonymousTypeParameter p = (AnonymousTypeParameter) parameters [i];
1647
1648                                 t_args [i] = new SimpleName ("<" + p.Name + ">__T", p.Location);
1649                                 t_params [i] = new TypeParameterName (t_args [i].Name, null, p.Location);
1650                                 ctor_params [i] = new Parameter (t_args [i], p.Name, 0, null, p.Location);
1651                         }
1652
1653                         //
1654                         // Create generic anonymous type host with generic arguments
1655                         // named upon properties names
1656                         //
1657                         AnonymousTypeClass a_type = new AnonymousTypeClass (parent.NamespaceEntry.SlaveDeclSpace,
1658                                 new MemberName (name, new TypeArguments (t_params), loc), parameters, loc);
1659
1660                         if (parameters.Count > 0)
1661                                 a_type.SetParameterInfo (null);
1662
1663                         Constructor c = new Constructor (a_type, name, Modifiers.PUBLIC | Modifiers.DEBUGGER_HIDDEN,
1664                                 null, new AnonymousParameters (ctor_params), null, loc);
1665                         c.Block = new ToplevelBlock (c.Parameters, loc);
1666
1667                         //
1668                         // Create fields and contructor body with field initialization
1669                         //
1670                         bool error = false;
1671                         for (int i = 0; i < parameters.Count; ++i) {
1672                                 AnonymousTypeParameter p = (AnonymousTypeParameter) parameters [i];
1673
1674                                 Field f = new Field (a_type, t_args [i], Modifiers.PRIVATE | Modifiers.READONLY,
1675                                         new MemberName ("<" + p.Name + ">", p.Location), null);
1676
1677                                 if (!a_type.AddField (f)) {
1678                                         error = true;
1679                                         continue;
1680                                 }
1681
1682                                 c.Block.AddStatement (new StatementExpression (
1683                                         new SimpleAssign (new MemberAccess (new This (p.Location), f.Name),
1684                                                 c.Block.GetParameterReference (p.Name, p.Location))));
1685
1686                                 ToplevelBlock get_block = new ToplevelBlock (p.Location);
1687                                 get_block.AddStatement (new Return (
1688                                         new MemberAccess (new This (p.Location), f.Name), p.Location));
1689                                 Accessor get_accessor = new Accessor (get_block, 0, null, null, p.Location);
1690                                 Property prop = new Property (a_type, t_args [i], Modifiers.PUBLIC,
1691                                         new MemberName (p.Name, p.Location), null, get_accessor, null, false);
1692                                 a_type.AddProperty (prop);
1693                         }
1694
1695                         if (error)
1696                                 return null;
1697
1698                         a_type.AddConstructor (c);
1699                         return a_type;
1700                 }
1701
1702                 public static void Reset ()
1703                 {
1704                         types_counter = 0;
1705                 }
1706
1707                 protected override bool AddToContainer (MemberCore symbol, string name)
1708                 {
1709                         MemberCore mc = (MemberCore) defined_names [name];
1710
1711                         if (mc == null) {
1712                                 defined_names.Add (name, symbol);
1713                                 return true;
1714                         }
1715
1716                         Report.SymbolRelatedToPreviousError (mc);
1717                         return false;
1718                 }
1719
1720                 void DefineOverrides ()
1721                 {
1722                         Location loc = Location;
1723
1724                         Method equals = new Method (this, null, TypeManager.system_boolean_expr,
1725                                 Modifiers.PUBLIC | Modifiers.OVERRIDE | Modifiers.DEBUGGER_HIDDEN, new MemberName ("Equals", loc),
1726                                 Mono.CSharp.ParametersCompiled.CreateFullyResolved (new Parameter (null, "obj", 0, null, loc), TypeManager.object_type), null);
1727
1728                         Method tostring = new Method (this, null, TypeManager.system_string_expr,
1729                                 Modifiers.PUBLIC | Modifiers.OVERRIDE | Modifiers.DEBUGGER_HIDDEN, new MemberName ("ToString", loc),
1730                                 Mono.CSharp.ParametersCompiled.EmptyReadOnlyParameters, null);
1731
1732                         ToplevelBlock equals_block = new ToplevelBlock (equals.Parameters, loc);
1733                         TypeExpr current_type;
1734                         if (IsGeneric)
1735                                 current_type = new GenericTypeExpr (this, loc);
1736                         else
1737                                 current_type = new TypeExpression (TypeBuilder, loc);
1738
1739                         equals_block.AddVariable (current_type, "other", loc);
1740                         LocalVariableReference other_variable = new LocalVariableReference (equals_block, "other", loc);
1741
1742                         MemberAccess system_collections_generic = new MemberAccess (new MemberAccess (
1743                                 new QualifiedAliasMember ("global", "System", loc), "Collections", loc), "Generic", loc);
1744
1745                         Expression rs_equals = null;
1746                         Expression string_concat = new StringConstant ("{", loc);
1747                         Expression rs_hashcode = new IntConstant (-2128831035, loc);
1748                         for (int i = 0; i < parameters.Count; ++i) {
1749                                 AnonymousTypeParameter p = (AnonymousTypeParameter) parameters [i];
1750                                 Field f = (Field) Fields [i];
1751
1752                                 MemberAccess equality_comparer = new MemberAccess (new MemberAccess (
1753                                         system_collections_generic, "EqualityComparer",
1754                                                 new TypeArguments (new SimpleName (TypeParameters [i].Name, loc)), loc),
1755                                                 "Default", loc);
1756
1757                                 ArrayList arguments_equal = new ArrayList (2);
1758                                 arguments_equal.Add (new Argument (new MemberAccess (new This (f.Location), f.Name)));
1759                                 arguments_equal.Add (new Argument (new MemberAccess (other_variable, f.Name)));
1760
1761                                 Expression field_equal = new Invocation (new MemberAccess (equality_comparer,
1762                                         "Equals", loc), arguments_equal);
1763
1764                                 ArrayList arguments_hashcode = new ArrayList (1);
1765                                 arguments_hashcode.Add (new Argument (new MemberAccess (new This (f.Location), f.Name)));
1766                                 Expression field_hashcode = new Invocation (new MemberAccess (equality_comparer,
1767                                         "GetHashCode", loc), arguments_hashcode);
1768
1769                                 IntConstant FNV_prime = new IntConstant (16777619, loc);
1770                                 rs_hashcode = new Binary (Binary.Operator.Multiply,
1771                                         new Binary (Binary.Operator.ExclusiveOr, rs_hashcode, field_hashcode),
1772                                         FNV_prime);
1773
1774                                 Expression field_to_string = new Conditional (new Binary (Binary.Operator.Inequality,
1775                                         new MemberAccess (new This (f.Location), f.Name), new NullLiteral (loc)),
1776                                         new Invocation (new MemberAccess (
1777                                                 new MemberAccess (new This (f.Location), f.Name), "ToString"), null),
1778                                         new StringConstant (string.Empty, loc));
1779
1780                                 if (rs_equals == null) {
1781                                         rs_equals = field_equal;
1782                                         string_concat = new Binary (Binary.Operator.Addition,
1783                                                 string_concat,
1784                                                 new Binary (Binary.Operator.Addition,
1785                                                         new StringConstant (" " + p.Name + " = ", loc),
1786                                                         field_to_string));
1787                                         continue;
1788                                 }
1789
1790                                 //
1791                                 // Implementation of ToString () body using string concatenation
1792                                 //
1793                                 string_concat = new Binary (Binary.Operator.Addition,
1794                                         new Binary (Binary.Operator.Addition,
1795                                                 string_concat,
1796                                                 new StringConstant (", " + p.Name + " = ", loc)),
1797                                         field_to_string);
1798
1799                                 rs_equals = new Binary (Binary.Operator.LogicalAnd, rs_equals, field_equal);
1800                         }
1801
1802                         string_concat = new Binary (Binary.Operator.Addition,
1803                                 string_concat,
1804                                 new StringConstant (" }", loc));
1805
1806                         //
1807                         // Equals (object obj) override
1808                         //
1809                         equals_block.AddStatement (new StatementExpression (
1810                                 new SimpleAssign (other_variable,
1811                                         new As (equals_block.GetParameterReference ("obj", loc),
1812                                                 current_type, loc), loc)));
1813
1814                         Expression equals_test = new Binary (Binary.Operator.Inequality, other_variable, new NullLiteral (loc));
1815                         if (rs_equals != null)
1816                                 equals_test = new Binary (Binary.Operator.LogicalAnd, equals_test, rs_equals);
1817                         equals_block.AddStatement (new Return (equals_test, loc));
1818
1819                         equals.Block = equals_block;
1820                         equals.Define ();
1821                         AddMethod (equals);
1822
1823                         //
1824                         // GetHashCode () override
1825                         //
1826                         Method hashcode = new Method (this, null, TypeManager.system_int32_expr,
1827                                 Modifiers.PUBLIC | Modifiers.OVERRIDE | Modifiers.DEBUGGER_HIDDEN,
1828                                 new MemberName ("GetHashCode", loc),
1829                                 Mono.CSharp.ParametersCompiled.EmptyReadOnlyParameters, null);
1830
1831                         //
1832                         // Modified FNV with good avalanche behavior and uniform
1833                         // distribution with larger hash sizes.
1834                         //
1835                         // const int FNV_prime = 16777619;
1836                         // int hash = (int) 2166136261;
1837                         // foreach (int d in data)
1838                         //     hash = (hash ^ d) * FNV_prime;
1839                         // hash += hash << 13;
1840                         // hash ^= hash >> 7;
1841                         // hash += hash << 3;
1842                         // hash ^= hash >> 17;
1843                         // hash += hash << 5;
1844
1845                         ToplevelBlock hashcode_top = new ToplevelBlock (loc);
1846                         Block hashcode_block = new Block (hashcode_top);
1847                         hashcode_top.AddStatement (new Unchecked (hashcode_block));
1848
1849                         hashcode_block.AddVariable (TypeManager.system_int32_expr, "hash", loc);
1850                         LocalVariableReference hash_variable = new LocalVariableReference (hashcode_block, "hash", loc);
1851                         hashcode_block.AddStatement (new StatementExpression (
1852                                 new SimpleAssign (hash_variable, rs_hashcode)));
1853
1854                         hashcode_block.AddStatement (new StatementExpression (
1855                                 new CompoundAssign (Binary.Operator.Addition, hash_variable,
1856                                         new Binary (Binary.Operator.LeftShift, hash_variable, new IntConstant (13, loc)))));
1857                         hashcode_block.AddStatement (new StatementExpression (
1858                                 new CompoundAssign (Binary.Operator.ExclusiveOr, hash_variable,
1859                                         new Binary (Binary.Operator.RightShift, hash_variable, new IntConstant (7, loc)))));
1860                         hashcode_block.AddStatement (new StatementExpression (
1861                                 new CompoundAssign (Binary.Operator.Addition, hash_variable,
1862                                         new Binary (Binary.Operator.LeftShift, hash_variable, new IntConstant (3, loc)))));
1863                         hashcode_block.AddStatement (new StatementExpression (
1864                                 new CompoundAssign (Binary.Operator.ExclusiveOr, hash_variable,
1865                                         new Binary (Binary.Operator.RightShift, hash_variable, new IntConstant (17, loc)))));
1866                         hashcode_block.AddStatement (new StatementExpression (
1867                                 new CompoundAssign (Binary.Operator.Addition, hash_variable,
1868                                         new Binary (Binary.Operator.LeftShift, hash_variable, new IntConstant (5, loc)))));
1869
1870                         hashcode_block.AddStatement (new Return (hash_variable, loc));
1871                         hashcode.Block = hashcode_top;
1872                         hashcode.Define ();
1873                         AddMethod (hashcode);
1874
1875                         //
1876                         // ToString () override
1877                         //
1878
1879                         ToplevelBlock tostring_block = new ToplevelBlock (loc);
1880                         tostring_block.AddStatement (new Return (string_concat, loc));
1881                         tostring.Block = tostring_block;
1882                         tostring.Define ();
1883                         AddMethod (tostring);
1884                 }
1885
1886                 public override bool Define ()
1887                 {
1888                         if (!base.Define ())
1889                                 return false;
1890
1891                         DefineOverrides ();
1892                         return true;
1893                 }
1894
1895                 public override string GetSignatureForError ()
1896                 {
1897                         return SignatureForError;
1898                 }
1899
1900                 public ArrayList Parameters {
1901                         get {
1902                                 return parameters;
1903                         }
1904                 }
1905         }
1906 }