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 2003-2011 Novell, Inc.
  10 // Copyright 2011 Xamarin Inc
  11 //
  12
  13 using System;
  14 using System.Collections.Generic;
  15 using Mono.CompilerServices.SymbolWriter;
  16 using System.Diagnostics;
  17
  18 #if STATIC
  19 using IKVM.Reflection;
  20 using IKVM.Reflection.Emit;
  21 #else
  22 using System.Reflection;
  23 using System.Reflection.Emit;
  24 #endif
  25
  26 namespace Mono.CSharp {
  27
  28         public abstract class CompilerGeneratedContainer : ClassOrStruct
  29         {
  30                 protected CompilerGeneratedContainer (TypeContainer parent, MemberName name, Modifiers mod)
  31                         : this (parent, name, mod, MemberKind.Class)
  32                 {
  33                 }
  34
  35                 protected CompilerGeneratedContainer (TypeContainer parent, MemberName name, Modifiers mod, MemberKind kind)
  36                         : base (parent, name, null, kind)
  37                 {
  38                         Debug.Assert ((mod & Modifiers.AccessibilityMask) != 0);
  39
  40                         ModFlags = mod | Modifiers.COMPILER_GENERATED | Modifiers.SEALED;
  41                         spec = new TypeSpec (Kind, null, this, null, ModFlags);
  42                 }
  43
  44                 protected void CheckMembersDefined ()
  45                 {
  46                         if (HasMembersDefined)
  47                                 throw new InternalErrorException ("Helper class already defined!");
  48                 }
  49
  50                 protected override bool DoDefineMembers ()
  51                 {
  52                         if (Kind == MemberKind.Class && !IsStatic && !PartialContainer.HasInstanceConstructor) {
  53                                 DefineDefaultConstructor (false);
  54                         }
  55
  56                         return base.DoDefineMembers ();
  57                 }
  58
  59                 protected static MemberName MakeMemberName (MemberBase host, string name, int unique_id, TypeParameters tparams, Location loc)
  60                 {
  61                         string host_name = host == null ? null : host is InterfaceMemberBase ? ((InterfaceMemberBase)host).GetFullName (host.MemberName) : host.MemberName.Name;
  62                         string tname = MakeName (host_name, "c", name, unique_id);
  63                         TypeParameters args = null;
  64                         if (tparams != null) {
  65                                 args = new TypeParameters (tparams.Count);
  66
  67                                 // Type parameters will be filled later when we have TypeContainer
  68                                 // instance, for now we need only correct arity to create valid name
  69                                 for (int i = 0; i < tparams.Count; ++i)
  70                                         args.Add ((TypeParameter) null);
  71                         }
  72
  73                         return new MemberName (tname, args, loc);
  74                 }
  75
  76                 public static string MakeName (string host, string typePrefix, string name, int id)
  77                 {
  78                         return "<" + host + ">" + typePrefix + "__" + name + id.ToString ("X");
  79                 }
  80
  81                 protected override TypeSpec[] ResolveBaseTypes (out FullNamedExpression base_class)
  82                 {
  83                         base_type = Compiler.BuiltinTypes.Object;
  84
  85                         base_class = null;
  86                         return null;
  87                 }
  88         }
  89
  90         public class HoistedStoreyClass : CompilerGeneratedContainer
  91         {
  92                 public sealed class HoistedField : Field
  93                 {
  94                         public HoistedField (HoistedStoreyClass parent, FullNamedExpression type, Modifiers mod, string name,
  95                                   Attributes attrs, Location loc)
  96                                 : base (parent, type, mod, new MemberName (name, loc), attrs)
  97                         {
  98                         }
  99
 100                         protected override bool ResolveMemberType ()
 101                         {
 102                                 if (!base.ResolveMemberType ())
 103                                         return false;
 104
 105                                 HoistedStoreyClass parent = ((HoistedStoreyClass) Parent).GetGenericStorey ();
 106                                 if (parent != null && parent.Mutator != null)
 107                                         member_type = parent.Mutator.Mutate (MemberType);
 108
 109                                 return true;
 110                         }
 111                 }
 112
 113                 protected TypeParameterMutator mutator;
 114
 115                 public HoistedStoreyClass (TypeDefinition parent, MemberName name, TypeParameters tparams, Modifiers mods, MemberKind kind)
 116                         : base (parent, name, mods | Modifiers.PRIVATE, kind)
 117                 {
 118
 119                         if (tparams != null) {
 120                                 var type_params = name.TypeParameters;
 121                                 var src = new TypeParameterSpec[tparams.Count];
 122                                 var dst = new TypeParameterSpec[tparams.Count];
 123
 124                                 for (int i = 0; i < tparams.Count; ++i) {
 125                                         type_params[i] = tparams[i].CreateHoistedCopy (spec);
 126
 127                                         src[i] = tparams[i].Type;
 128                                         dst[i] = type_params[i].Type;
 129                                 }
 130
 131                                 // A copy is not enough, inflate any type parameter constraints
 132                                 // using a new type parameters
 133                                 var inflator = new TypeParameterInflator (this, null, src, dst);
 134                                 for (int i = 0; i < tparams.Count; ++i) {
 135                                         src[i].InflateConstraints (inflator, dst[i]);
 136                                 }
 137
 138                                 mutator = new TypeParameterMutator (tparams, type_params);
 139                         }
 140                 }
 141
 142                 #region Properties
 143
 144                 public TypeParameterMutator Mutator {
 145                         get {
 146                                 return mutator;
 147                         }
 148                         set {
 149                                 mutator = value;
 150                         }
 151                 }
 152
 153                 #endregion
 154
 155                 public HoistedStoreyClass GetGenericStorey ()
 156                 {
 157                         TypeContainer storey = this;
 158                         while (storey != null && storey.CurrentTypeParameters == null)
 159                                 storey = storey.Parent;
 160
 161                         return storey as HoistedStoreyClass;
 162                 }
 163         }
 164
 165
 166         //
 167         // Anonymous method storey is created when an anonymous method uses
 168         // variable or parameter from outer scope. They are then hoisted to
 169         // anonymous method storey (captured)
 170         //
 171         public class AnonymousMethodStorey : HoistedStoreyClass
 172         {
 173                 struct StoreyFieldPair
 174                 {
 175                         public readonly AnonymousMethodStorey Storey;
 176                         public readonly Field Field;
 177
 178                         public StoreyFieldPair (AnonymousMethodStorey storey, Field field)
 179                         {
 180                                 this.Storey = storey;
 181                                 this.Field = field;
 182                         }
 183                 }
 184
 185                 //
 186                 // Needed to delay hoisted _this_ initialization. When an anonymous
 187                 // method is used inside ctor and _this_ is hoisted, base ctor has to
 188                 // be called first, otherwise _this_ will be initialized with
 189                 // uninitialized value.
 190                 //
 191                 sealed class ThisInitializer : Statement
 192                 {
 193                         readonly HoistedThis hoisted_this;
 194
 195                         public ThisInitializer (HoistedThis hoisted_this)
 196                         {
 197                                 this.hoisted_this = hoisted_this;
 198                         }
 199
 200                         protected override void DoEmit (EmitContext ec)
 201                         {
 202                                 hoisted_this.EmitAssign (ec, new CompilerGeneratedThis (ec.CurrentType, loc), false, false);
 203                         }
 204
 205                         protected override void CloneTo (CloneContext clonectx, Statement target)
 206                         {
 207                                 // Nothing to clone
 208                         }
 209                 }
 210
 211                 // Unique storey ID
 212                 public readonly int ID;
 213
 214                 public readonly ExplicitBlock OriginalSourceBlock;
 215
 216                 // A list of StoreyFieldPair with local field keeping parent storey instance
 217                 List<StoreyFieldPair> used_parent_storeys;
 218                 List<ExplicitBlock> children_references;
 219
 220                 // A list of hoisted parameters
 221                 protected List<HoistedParameter> hoisted_params;
 222                 List<HoistedParameter> hoisted_local_params;
 223                 protected List<HoistedVariable> hoisted_locals;
 224
 225                 // Hoisted this
 226                 protected HoistedThis hoisted_this;
 227
 228                 // Local variable which holds this storey instance
 229                 public Expression Instance;
 230
 231                 bool initialize_hoisted_this;
 232
 233                 public AnonymousMethodStorey (ExplicitBlock block, TypeDefinition parent, MemberBase host, TypeParameters tparams, string name, MemberKind kind)
 234                         : base (parent, MakeMemberName (host, name, parent.Module.CounterAnonymousContainers, tparams, block.StartLocation),
 235                                 tparams, 0, kind)
 236                 {
 237                         OriginalSourceBlock = block;
 238                         ID = parent.Module.CounterAnonymousContainers++;
 239                 }
 240
 241                 public void AddCapturedThisField (EmitContext ec)
 242                 {
 243                         TypeExpr type_expr = new TypeExpression (ec.CurrentType, Location);
 244                         Field f = AddCompilerGeneratedField ("$this", type_expr);
 245                         hoisted_this = new HoistedThis (this, f);
 246
 247                         initialize_hoisted_this = true;
 248                 }
 249
 250                 public Field AddCapturedVariable (string name, TypeSpec type)
 251                 {
 252                         CheckMembersDefined ();
 253
 254                         FullNamedExpression field_type = new TypeExpression (type, Location);
 255                         if (!spec.IsGenericOrParentIsGeneric)
 256                                 return AddCompilerGeneratedField (name, field_type);
 257
 258                         const Modifiers mod = Modifiers.INTERNAL | Modifiers.COMPILER_GENERATED;
 259                         Field f = new HoistedField (this, field_type, mod, name, null, Location);
 260                         AddField (f);
 261                         return f;
 262                 }
 263
 264                 protected Field AddCompilerGeneratedField (string name, FullNamedExpression type)
 265                 {
 266                         return AddCompilerGeneratedField (name, type, false);
 267                 }
 268
 269                 protected Field AddCompilerGeneratedField (string name, FullNamedExpression type, bool privateAccess)
 270                 {
 271                         Modifiers mod = Modifiers.COMPILER_GENERATED | (privateAccess ? Modifiers.PRIVATE : Modifiers.INTERNAL);
 272                         Field f = new Field (this, type, mod, new MemberName (name, Location), null);
 273                         AddField (f);
 274                         return f;
 275                 }
 276
 277                 //
 278                 // Creates a link between hoisted variable block and the anonymous method storey
 279                 //
 280                 // An anonymous method can reference variables from any outer block, but they are
 281                 // hoisted in their own ExplicitBlock. When more than one block is referenced we
 282                 // need to create another link between those variable storeys
 283                 //
 284                 public void AddReferenceFromChildrenBlock (ExplicitBlock block)
 285                 {
 286                         if (children_references == null)
 287                                 children_references = new List<ExplicitBlock> ();
 288
 289                         if (!children_references.Contains (block))
 290                                 children_references.Add (block);
 291                 }
 292
 293                 public void AddParentStoreyReference (EmitContext ec, AnonymousMethodStorey storey)
 294                 {
 295                         CheckMembersDefined ();
 296
 297                         if (used_parent_storeys == null)
 298                                 used_parent_storeys = new List<StoreyFieldPair> ();
 299                         else if (used_parent_storeys.Exists (i => i.Storey == storey))
 300                                 return;
 301
 302                         TypeExpr type_expr = storey.CreateStoreyTypeExpression (ec);
 303                         Field f = AddCompilerGeneratedField ("<>f__ref$" + storey.ID, type_expr);
 304                         used_parent_storeys.Add (new StoreyFieldPair (storey, f));
 305                 }
 306
 307                 public void CaptureLocalVariable (ResolveContext ec, LocalVariable localVariable)
 308                 {
 309                         if (this is StateMachine) {
 310                                 if (ec.CurrentBlock.ParametersBlock != localVariable.Block.ParametersBlock)
 311                                         ec.CurrentBlock.Explicit.HasCapturedVariable = true;
 312                         } else {
 313                                 ec.CurrentBlock.Explicit.HasCapturedVariable = true;
 314                         }
 315
 316                         var hoisted = localVariable.HoistedVariant;
 317                         if (hoisted != null && hoisted.Storey != this && hoisted.Storey is StateMachine) {
 318                                 // TODO: It's too late the field is defined in HoistedLocalVariable ctor
 319                                 hoisted.Storey.hoisted_locals.Remove (hoisted);
 320                                 hoisted = null;
 321                         }
 322
 323                         if (hoisted == null) {
 324                                 hoisted = new HoistedLocalVariable (this, localVariable, GetVariableMangledName (localVariable));
 325                                 localVariable.HoistedVariant = hoisted;
 326
 327                                 if (hoisted_locals == null)
 328                                         hoisted_locals = new List<HoistedVariable> ();
 329
 330                                 hoisted_locals.Add (hoisted);
 331                         }
 332
 333                         if (ec.CurrentBlock.Explicit != localVariable.Block.Explicit && !(hoisted.Storey is StateMachine))
 334                                 hoisted.Storey.AddReferenceFromChildrenBlock (ec.CurrentBlock.Explicit);
 335                 }
 336
 337                 public void CaptureParameter (ResolveContext ec, ParametersBlock.ParameterInfo parameterInfo, ParameterReference parameterReference)
 338                 {
 339                         if (!(this is StateMachine)) {
 340                                 ec.CurrentBlock.Explicit.HasCapturedVariable = true;
 341                         }
 342
 343                         var hoisted = parameterInfo.Parameter.HoistedVariant;
 344
 345                         if (parameterInfo.Block.StateMachine != null) {
 346                                 //
 347                                 // Another storey in same block exists but state machine does not
 348                                 // have parameter captured. We need to add it there as well to
 349                                 // proxy parameter value correctly.
 350                                 //
 351                                 if (hoisted == null && parameterInfo.Block.StateMachine != this) {
 352                                         var storey = parameterInfo.Block.StateMachine;
 353
 354                                         hoisted = new HoistedParameter (storey, parameterReference);
 355                                         parameterInfo.Parameter.HoistedVariant = hoisted;
 356
 357                                         if (storey.hoisted_params == null)
 358                                                 storey.hoisted_params = new List<HoistedParameter> ();
 359
 360                                         storey.hoisted_params.Add (hoisted);
 361                                 }
 362
 363                                 //
 364                                 // Lift captured parameter from value type storey to reference type one. Otherwise
 365                                 // any side effects would be done on a copy
 366                                 //
 367                                 if (hoisted != null && hoisted.Storey != this && hoisted.Storey is StateMachine) {
 368                                         if (hoisted_local_params == null)
 369                                                 hoisted_local_params = new List<HoistedParameter> ();
 370
 371                                         hoisted_local_params.Add (hoisted);
 372                                         hoisted = null;
 373                                 }
 374                         }
 375
 376                         if (hoisted == null) {
 377                                 hoisted = new HoistedParameter (this, parameterReference);
 378                                 parameterInfo.Parameter.HoistedVariant = hoisted;
 379
 380                                 if (hoisted_params == null)
 381                                         hoisted_params = new List<HoistedParameter> ();
 382
 383                                 hoisted_params.Add (hoisted);
 384                         }
 385
 386                         //
 387                         // Register link between current block and parameter storey. It will
 388                         // be used when setting up storey definition to deploy storey reference
 389                         // when parameters are used from multiple blocks
 390                         //
 391                         if (ec.CurrentBlock.Explicit != parameterInfo.Block) {
 392                                 hoisted.Storey.AddReferenceFromChildrenBlock (ec.CurrentBlock.Explicit);
 393                         }
 394                 }
 395
 396                 TypeExpr CreateStoreyTypeExpression (EmitContext ec)
 397                 {
 398                         //
 399                         // Create an instance of storey type
 400                         //
 401                         TypeExpr storey_type_expr;
 402                         if (CurrentTypeParameters != null) {
 403                                 //
 404                                 // Use current method type parameter (MVAR) for top level storey only. All
 405                                 // nested storeys use class type parameter (VAR)
 406                                 //
 407                                 var tparams = ec.CurrentAnonymousMethod != null && ec.CurrentAnonymousMethod.Storey != null ?
 408                                         ec.CurrentAnonymousMethod.Storey.CurrentTypeParameters :
 409                                         ec.CurrentTypeParameters;
 410
 411                                 TypeArguments targs = new TypeArguments ();
 412
 413                                 //
 414                                 // Use type parameter name instead of resolved type parameter
 415                                 // specification to resolve to correctly nested type parameters
 416                                 //
 417                                 for (int i = 0; i < tparams.Count; ++i)
 418                                         targs.Add (new SimpleName (tparams [i].Name, Location)); //  new TypeParameterExpr (tparams[i], Location));
 419
 420                                 storey_type_expr = new GenericTypeExpr (Definition, targs, Location);
 421                         } else {
 422                                 storey_type_expr = new TypeExpression (CurrentType, Location);
 423                         }
 424
 425                         return storey_type_expr;
 426                 }
 427
 428                 public void SetNestedStoryParent (AnonymousMethodStorey parentStorey)
 429                 {
 430                         Parent = parentStorey;
 431                         spec.IsGeneric = false;
 432                         spec.DeclaringType = parentStorey.CurrentType;
 433                         MemberName.TypeParameters = null;
 434                 }
 435
 436                 protected override bool DoResolveTypeParameters ()
 437                 {
 438                         // Although any storey can have type parameters they are all clones of method type
 439                         // parameters therefore have to mutate MVAR references in any of cloned constraints
 440                         if (CurrentTypeParameters != null) {
 441                                 for (int i = 0; i < CurrentTypeParameters.Count; ++i) {
 442                                         var spec = CurrentTypeParameters[i].Type;
 443                                         spec.BaseType = mutator.Mutate (spec.BaseType);
 444                                         if (spec.InterfacesDefined != null) {
 445                                                 var mutated = new TypeSpec[spec.InterfacesDefined.Length];
 446                                                 for (int ii = 0; ii < mutated.Length; ++ii) {
 447                                                         mutated[ii] = mutator.Mutate (spec.InterfacesDefined[ii]);
 448                                                 }
 449
 450                                                 spec.InterfacesDefined = mutated;
 451                                         }
 452
 453                                         if (spec.TypeArguments != null) {
 454                                                 spec.TypeArguments = mutator.Mutate (spec.TypeArguments);
 455                                         }
 456                                 }
 457                         }
 458
 459                         //
 460                         // Update parent cache as we most likely passed the point
 461                         // where the cache was constructed
 462                         //
 463                         Parent.CurrentType.MemberCache.AddMember (this.spec);
 464
 465                         return true;
 466                 }
 467
 468                 //
 469                 // Initializes all hoisted variables
 470                 //
 471                 public void EmitStoreyInstantiation (EmitContext ec, ExplicitBlock block)
 472                 {
 473                         // There can be only one instance variable for each storey type
 474                         if (Instance != null)
 475                                 throw new InternalErrorException ();
 476
 477                         //
 478                         // Create an instance of this storey
 479                         //
 480                         ResolveContext rc = new ResolveContext (ec.MemberContext);
 481                         rc.CurrentBlock = block;
 482
 483                         var storey_type_expr = CreateStoreyTypeExpression (ec);
 484                         var source = new New (storey_type_expr, null, Location).Resolve (rc);
 485
 486                         //
 487                         // When the current context is async (or iterator) lift local storey
 488                         // instantiation to the currect storey
 489                         //
 490                         if (ec.CurrentAnonymousMethod is StateMachineInitializer && (block.HasYield || block.HasAwait)) {
 491                                 //
 492                                 // Unfortunately, normal capture mechanism could not be used because we are
 493                                 // too late in the pipeline and standart assign cannot be used either due to
 494                                 // recursive nature of GetStoreyInstanceExpression
 495                                 //
 496                                 var field = ec.CurrentAnonymousMethod.Storey.AddCompilerGeneratedField (
 497                                         LocalVariable.GetCompilerGeneratedName (block), storey_type_expr, true);
 498
 499                                 field.Define ();
 500                                 field.Emit ();
 501
 502                                 var fexpr = new FieldExpr (field, Location);
 503                                 fexpr.InstanceExpression = new CompilerGeneratedThis (ec.CurrentType, Location);
 504                                 fexpr.EmitAssign (ec, source, false, false);
 505                                 Instance = fexpr;
 506                         } else {
 507                                 var local = TemporaryVariableReference.Create (source.Type, block, Location);
 508                                 if (source.Type.IsStruct) {
 509                                         local.LocalInfo.CreateBuilder (ec);
 510                                 } else {
 511                                         local.EmitAssign (ec, source);
 512                                 }
 513
 514                                 Instance = local;
 515                         }
 516
 517                         EmitHoistedFieldsInitialization (rc, ec);
 518
 519                         // TODO: Implement properly
 520                         //SymbolWriter.DefineScopeVariable (ID, Instance.Builder);
 521                 }
 522
 523                 void EmitHoistedFieldsInitialization (ResolveContext rc, EmitContext ec)
 524                 {
 525                         //
 526                         // Initialize all storey reference fields by using local or hoisted variables
 527                         //
 528                         if (used_parent_storeys != null) {
 529                                 foreach (StoreyFieldPair sf in used_parent_storeys) {
 530                                         //
 531                                         // Get instance expression of storey field
 532                                         //
 533                                         Expression instace_expr = GetStoreyInstanceExpression (ec);
 534                                         var fs = sf.Field.Spec;
 535                                         if (TypeManager.IsGenericType (instace_expr.Type))
 536                                                 fs = MemberCache.GetMember (instace_expr.Type, fs);
 537
 538                                         FieldExpr f_set_expr = new FieldExpr (fs, Location);
 539                                         f_set_expr.InstanceExpression = instace_expr;
 540
 541                                         // TODO: CompilerAssign expression
 542                                         SimpleAssign a = new SimpleAssign (f_set_expr, sf.Storey.GetStoreyInstanceExpression (ec));
 543                                         if (a.Resolve (rc) != null)
 544                                                 a.EmitStatement (ec);
 545                                 }
 546                         }
 547
 548                         //
 549                         // Initialize hoisted `this' only once, everywhere else will be
 550                         // referenced indirectly
 551                         //
 552                         if (initialize_hoisted_this) {
 553                                 rc.CurrentBlock.AddScopeStatement (new ThisInitializer (hoisted_this));
 554                         }
 555
 556                         //
 557                         // Setting currect anonymous method to null blocks any further variable hoisting
 558                         //
 559                         AnonymousExpression ae = ec.CurrentAnonymousMethod;
 560                         ec.CurrentAnonymousMethod = null;
 561
 562                         if (hoisted_params != null) {
 563                                 EmitHoistedParameters (ec, hoisted_params);
 564                         }
 565
 566                         ec.CurrentAnonymousMethod = ae;
 567                 }
 568
 569                 protected virtual void EmitHoistedParameters (EmitContext ec, List<HoistedParameter> hoisted)
 570                 {
 571                         foreach (HoistedParameter hp in hoisted) {
 572                                 //
 573                                 // Parameters could be proxied via local fields for value type storey
 574                                 //
 575                                 if (hoisted_local_params != null) {
 576                                         var local_param = hoisted_local_params.Find (l => l.Parameter.Parameter == hp.Parameter.Parameter);
 577                                         var source = new FieldExpr (local_param.Field, Location);
 578                                         source.InstanceExpression = new CompilerGeneratedThis (CurrentType, Location);
 579                                         hp.EmitAssign (ec, source, false, false);
 580                                         continue;
 581                                 }
 582
 583                                 hp.EmitHoistingAssignment (ec);
 584                         }
 585                 }
 586
 587                 //
 588                 // Returns a field which holds referenced storey instance
 589                 //
 590                 Field GetReferencedStoreyField (AnonymousMethodStorey storey)
 591                 {
 592                         if (used_parent_storeys == null)
 593                                 return null;
 594
 595                         foreach (StoreyFieldPair sf in used_parent_storeys) {
 596                                 if (sf.Storey == storey)
 597                                         return sf.Field;
 598                         }
 599
 600                         return null;
 601                 }
 602
 603                 //
 604                 // Creates storey instance expression regardless of currect IP
 605                 //
 606                 public Expression GetStoreyInstanceExpression (EmitContext ec)
 607                 {
 608                         AnonymousExpression am = ec.CurrentAnonymousMethod;
 609
 610                         //
 611                         // Access from original block -> storey
 612                         //
 613                         if (am == null)
 614                                 return Instance;
 615
 616                         //
 617                         // Access from anonymous method implemented as a static -> storey
 618                         //
 619                         if (am.Storey == null)
 620                                 return Instance;
 621
 622                         Field f = am.Storey.GetReferencedStoreyField (this);
 623                         if (f == null) {
 624                                 if (am.Storey == this) {
 625                                         //
 626                                         // Access from inside of same storey (S -> S)
 627                                         //
 628                                         return new CompilerGeneratedThis (CurrentType, Location);
 629                                 }
 630
 631                                 //
 632                                 // External field access
 633                                 //
 634                                 return Instance;
 635                         }
 636
 637                         //
 638                         // Storey was cached to local field
 639                         //
 640                         FieldExpr f_ind = new FieldExpr (f, Location);
 641                         f_ind.InstanceExpression = new CompilerGeneratedThis (CurrentType, Location);
 642                         return f_ind;
 643                 }
 644
 645                 protected virtual string GetVariableMangledName (LocalVariable local_info)
 646                 {
 647                         //
 648                         // No need to mangle anonymous method hoisted variables cause they
 649                         // are hoisted in their own scopes
 650                         //
 651                         return local_info.Name;
 652                 }
 653
 654                 public HoistedThis HoistedThis {
 655                         get {
 656                                 return hoisted_this;
 657                         }
 658                         set {
 659                                 hoisted_this = value;
 660                         }
 661                 }
 662
 663                 public IList<ExplicitBlock> ReferencesFromChildrenBlock {
 664                         get { return children_references; }
 665                 }
 666         }
 667
 668         public abstract class HoistedVariable
 669         {
 670                 //
 671                 // Hoisted version of variable references used in expression
 672                 // tree has to be delayed until we know its location. The variable
 673                 // doesn't know its location until all stories are calculated
 674                 //
 675                 class ExpressionTreeVariableReference : Expression
 676                 {
 677                         readonly HoistedVariable hv;
 678
 679                         public ExpressionTreeVariableReference (HoistedVariable hv)
 680                         {
 681                                 this.hv = hv;
 682                         }
 683
 684                         public override bool ContainsEmitWithAwait ()
 685                         {
 686                                 return false;
 687                         }
 688
 689                         public override Expression CreateExpressionTree (ResolveContext ec)
 690                         {
 691                                 return hv.CreateExpressionTree ();
 692                         }
 693
 694                         protected override Expression DoResolve (ResolveContext ec)
 695                         {
 696                                 eclass = ExprClass.Value;
 697                                 type = ec.Module.PredefinedTypes.Expression.Resolve ();
 698                                 return this;
 699                         }
 700
 701                         public override void Emit (EmitContext ec)
 702                         {
 703                                 ResolveContext rc = new ResolveContext (ec.MemberContext);
 704                                 Expression e = hv.GetFieldExpression (ec).CreateExpressionTree (rc, false);
 705                                 // This should never fail
 706                                 e = e.Resolve (rc);
 707                                 if (e != null)
 708                                         e.Emit (ec);
 709                         }
 710                 }
 711
 712                 protected readonly AnonymousMethodStorey storey;
 713                 protected Field field;
 714                 Dictionary<AnonymousExpression, FieldExpr> cached_inner_access; // TODO: Hashtable is too heavyweight
 715                 FieldExpr cached_outer_access;
 716
 717                 protected HoistedVariable (AnonymousMethodStorey storey, string name, TypeSpec type)
 718                         : this (storey, storey.AddCapturedVariable (name, type))
 719                 {
 720                 }
 721
 722                 protected HoistedVariable (AnonymousMethodStorey storey, Field field)
 723                 {
 724                         this.storey = storey;
 725                         this.field = field;
 726                 }
 727
 728                 public AnonymousMethodStorey Storey {
 729                         get {
 730                                 return storey;
 731                         }
 732                 }
 733
 734                 public void AddressOf (EmitContext ec, AddressOp mode)
 735                 {
 736                         GetFieldExpression (ec).AddressOf (ec, mode);
 737                 }
 738
 739                 public Expression CreateExpressionTree ()
 740                 {
 741                         return new ExpressionTreeVariableReference (this);
 742                 }
 743
 744                 public void Emit (EmitContext ec)
 745                 {
 746                         GetFieldExpression (ec).Emit (ec);
 747                 }
 748
 749                 public Expression EmitToField (EmitContext ec)
 750                 {
 751                         return GetFieldExpression (ec);
 752                 }
 753
 754                 //
 755                 // Creates field access expression for hoisted variable
 756                 //
 757                 protected virtual FieldExpr GetFieldExpression (EmitContext ec)
 758                 {
 759                         if (ec.CurrentAnonymousMethod == null || ec.CurrentAnonymousMethod.Storey == null) {
 760                                 if (cached_outer_access != null)
 761                                         return cached_outer_access;
 762
 763                                 //
 764                                 // When setting top-level hoisted variable in generic storey
 765                                 // change storey generic types to method generic types (VAR -> MVAR)
 766                                 //
 767                                 if (storey.Instance.Type.IsGenericOrParentIsGeneric) {
 768                                         var fs = MemberCache.GetMember (storey.Instance.Type, field.Spec);
 769                                         cached_outer_access = new FieldExpr (fs, field.Location);
 770                                 } else {
 771                                         cached_outer_access = new FieldExpr (field, field.Location);
 772                                 }
 773
 774                                 cached_outer_access.InstanceExpression = storey.GetStoreyInstanceExpression (ec);
 775                                 return cached_outer_access;
 776                         }
 777
 778                         FieldExpr inner_access;
 779                         if (cached_inner_access != null) {
 780                                 if (!cached_inner_access.TryGetValue (ec.CurrentAnonymousMethod, out inner_access))
 781                                         inner_access = null;
 782                         } else {
 783                                 inner_access = null;
 784                                 cached_inner_access = new Dictionary<AnonymousExpression, FieldExpr> (4);
 785                         }
 786
 787                         if (inner_access == null) {
 788                                 if (field.Parent.IsGenericOrParentIsGeneric) {
 789                                         var fs = MemberCache.GetMember (field.Parent.CurrentType, field.Spec);
 790                                         inner_access = new FieldExpr (fs, field.Location);
 791                                 } else {
 792                                         inner_access = new FieldExpr (field, field.Location);
 793                                 }
 794
 795                                 inner_access.InstanceExpression = storey.GetStoreyInstanceExpression (ec);
 796                                 cached_inner_access.Add (ec.CurrentAnonymousMethod, inner_access);
 797                         }
 798
 799                         return inner_access;
 800                 }
 801
 802                 public void Emit (EmitContext ec, bool leave_copy)
 803                 {
 804                         GetFieldExpression (ec).Emit (ec, leave_copy);
 805                 }
 806
 807                 public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool isCompound)
 808                 {
 809                         GetFieldExpression (ec).EmitAssign (ec, source, leave_copy, false);
 810                 }
 811         }
 812
 813         public class HoistedParameter : HoistedVariable
 814         {
 815                 sealed class HoistedFieldAssign : CompilerAssign
 816                 {
 817                         public HoistedFieldAssign (Expression target, Expression source)
 818                                 : base (target, source, target.Location)
 819                         {
 820                         }
 821
 822                         protected override Expression ResolveConversions (ResolveContext ec)
 823                         {
 824                                 //
 825                                 // Implicit conversion check fails for hoisted type arguments
 826                                 // as they are of different types (!!0 x !0)
 827                                 //
 828                                 return this;
 829                         }
 830                 }
 831
 832                 readonly ParameterReference parameter;
 833
 834                 public HoistedParameter (AnonymousMethodStorey scope, ParameterReference par)
 835                         : base (scope, par.Name, par.Type)
 836                 {
 837                         this.parameter = par;
 838                 }
 839
 840                 public HoistedParameter (HoistedParameter hp, string name)
 841                         : base (hp.storey, name, hp.parameter.Type)
 842                 {
 843                         this.parameter = hp.parameter;
 844                 }
 845
 846                 #region Properties
 847
 848                 public Field Field {
 849                         get {
 850                                 return field;
 851                         }
 852                 }
 853
 854                 public ParameterReference Parameter {
 855                         get {
 856                                 return parameter;
 857                         }
 858                 }
 859
 860                 #endregion
 861
 862                 public void EmitHoistingAssignment (EmitContext ec)
 863                 {
 864                         //
 865                         // Remove hoisted redirection to emit assignment from original parameter
 866                         //
 867                         var temp = parameter.Parameter.HoistedVariant;
 868                         parameter.Parameter.HoistedVariant = null;
 869
 870                         var a = new HoistedFieldAssign (GetFieldExpression (ec), parameter);
 871                         a.EmitStatement (ec);
 872
 873                         parameter.Parameter.HoistedVariant = temp;
 874                 }
 875         }
 876
 877         class HoistedLocalVariable : HoistedVariable
 878         {
 879                 public HoistedLocalVariable (AnonymousMethodStorey storey, LocalVariable local, string name)
 880                         : base (storey, name, local.Type)
 881                 {
 882                 }
 883         }
 884
 885         public class HoistedThis : HoistedVariable
 886         {
 887                 public HoistedThis (AnonymousMethodStorey storey, Field field)
 888                         : base (storey, field)
 889                 {
 890                 }
 891
 892                 public Field Field {
 893                         get {
 894                                 return field;
 895                         }
 896                 }
 897         }
 898
 899         //
 900         // Anonymous method expression as created by parser
 901         //
 902         public class AnonymousMethodExpression : Expression
 903         {
 904                 //
 905                 // Special conversion for nested expression tree lambdas
 906                 //
 907                 class Quote : ShimExpression
 908                 {
 909                         public Quote (Expression expr)
 910                                 : base (expr)
 911                         {
 912                         }
 913
 914                         public override Expression CreateExpressionTree (ResolveContext ec)
 915                         {
 916                                 var args = new Arguments (1);
 917                                 args.Add (new Argument (expr.CreateExpressionTree (ec)));
 918                                 return CreateExpressionFactoryCall (ec, "Quote", args);
 919                         }
 920
 921                         protected override Expression DoResolve (ResolveContext rc)
 922                         {
 923                                 expr = expr.Resolve (rc);
 924                                 if (expr == null)
 925                                         return null;
 926
 927                                 eclass = expr.eclass;
 928                                 type = expr.Type;
 929                                 return this;
 930                         }
 931                 }
 932
 933                 readonly Dictionary<TypeSpec, Expression> compatibles;
 934
 935                 public ParametersBlock Block;
 936
 937                 public AnonymousMethodExpression (Location loc)
 938                 {
 939                         this.loc = loc;
 940                         this.compatibles = new Dictionary<TypeSpec, Expression> ();
 941                 }
 942
 943                 #region Properties
 944
 945                 public override string ExprClassName {
 946                         get {
 947                                 return "anonymous method";
 948                         }
 949                 }
 950
 951                 public virtual bool HasExplicitParameters {
 952                         get {
 953                                 return Parameters != ParametersCompiled.Undefined;
 954                         }
 955                 }
 956
 957                 public ParametersCompiled Parameters {
 958                         get {
 959                                 return Block.Parameters;
 960                         }
 961                 }
 962
 963                 public ReportPrinter TypeInferenceReportPrinter {
 964                         get; set;
 965                 }
 966
 967                 #endregion
 968
 969                 //
 970                 // Returns true if the body of lambda expression can be implicitly
 971                 // converted to the delegate of type `delegate_type'
 972                 //
 973                 public bool ImplicitStandardConversionExists (ResolveContext ec, TypeSpec delegate_type)
 974                 {
 975                         using (ec.With (ResolveContext.Options.InferReturnType, false)) {
 976                                 using (ec.Set (ResolveContext.Options.ProbingMode)) {
 977                                         var prev = ec.Report.SetPrinter (TypeInferenceReportPrinter ?? new NullReportPrinter ());
 978
 979                                         var res = Compatible (ec, delegate_type) != null;
 980
 981                                         ec.Report.SetPrinter (prev);
 982
 983                                         return res;
 984                                 }
 985                         }
 986                 }
 987
 988                 TypeSpec CompatibleChecks (ResolveContext ec, TypeSpec delegate_type)
 989                 {
 990                         if (delegate_type.IsDelegate)
 991                                 return delegate_type;
 992
 993                         if (delegate_type.IsExpressionTreeType) {
 994                                 delegate_type = delegate_type.TypeArguments [0];
 995                                 if (delegate_type.IsDelegate)
 996                                         return delegate_type;
 997
 998                                 ec.Report.Error (835, loc, "Cannot convert `{0}' to an expression tree of non-delegate type `{1}'",
 999                                         GetSignatureForError (), TypeManager.CSharpName (delegate_type));
1000                                 return null;
1001                         }
1002
1003                         ec.Report.Error (1660, loc, "Cannot convert `{0}' to non-delegate type `{1}'",
1004                                       GetSignatureForError (), TypeManager.CSharpName (delegate_type));
1005                         return null;
1006                 }
1007
1008                 protected bool VerifyExplicitParameters (ResolveContext ec, TypeSpec delegate_type, AParametersCollection parameters)
1009                 {
1010                         if (VerifyParameterCompatibility (ec, delegate_type, parameters, ec.IsInProbingMode))
1011                                 return true;
1012
1013                         if (!ec.IsInProbingMode)
1014                                 ec.Report.Error (1661, loc,
1015                                         "Cannot convert `{0}' to delegate type `{1}' since there is a parameter mismatch",
1016                                         GetSignatureForError (), TypeManager.CSharpName (delegate_type));
1017
1018                         return false;
1019                 }
1020
1021                 protected bool VerifyParameterCompatibility (ResolveContext ec, TypeSpec delegate_type, AParametersCollection invoke_pd, bool ignore_errors)
1022                 {
1023                         if (Parameters.Count != invoke_pd.Count) {
1024                                 if (ignore_errors)
1025                                         return false;
1026
1027                                 ec.Report.Error (1593, loc, "Delegate `{0}' does not take `{1}' arguments",
1028                                               TypeManager.CSharpName (delegate_type), Parameters.Count.ToString ());
1029                                 return false;
1030                         }
1031
1032                         bool has_implicit_parameters = !HasExplicitParameters;
1033                         bool error = false;
1034
1035                         for (int i = 0; i < Parameters.Count; ++i) {
1036                                 Parameter.Modifier p_mod = invoke_pd.FixedParameters [i].ModFlags;
1037                                 if (Parameters.FixedParameters [i].ModFlags != p_mod && p_mod != Parameter.Modifier.PARAMS) {
1038                                         if (ignore_errors)
1039                                                 return false;
1040
1041                                         if (p_mod == Parameter.Modifier.NONE)
1042                                                 ec.Report.Error (1677, loc, "Parameter `{0}' should not be declared with the `{1}' keyword",
1043                                                               (i + 1).ToString (), Parameter.GetModifierSignature (Parameters.FixedParameters [i].ModFlags));
1044                                         else
1045                                                 ec.Report.Error (1676, loc, "Parameter `{0}' must be declared with the `{1}' keyword",
1046                                                               (i+1).ToString (), Parameter.GetModifierSignature (p_mod));
1047                                         error = true;
1048                                 }
1049
1050                                 if (has_implicit_parameters)
1051                                         continue;
1052
1053                                 TypeSpec type = invoke_pd.Types [i];
1054
1055                                 // We assume that generic parameters are always inflated
1056                                 if (TypeManager.IsGenericParameter (type))
1057                                         continue;
1058
1059                                 if (TypeManager.HasElementType (type) && TypeManager.IsGenericParameter (TypeManager.GetElementType (type)))
1060                                         continue;
1061
1062                                 if (!TypeSpecComparer.IsEqual (invoke_pd.Types [i], Parameters.Types [i])) {
1063                                         if (ignore_errors)
1064                                                 return false;
1065
1066                                         ec.Report.Error (1678, loc, "Parameter `{0}' is declared as type `{1}' but should be `{2}'",
1067                                                       (i+1).ToString (),
1068                                                       TypeManager.CSharpName (Parameters.Types [i]),
1069                                                       TypeManager.CSharpName (invoke_pd.Types [i]));
1070                                         error = true;
1071                                 }
1072                         }
1073
1074                         return !error;
1075                 }
1076
1077                 //
1078                 // Infers type arguments based on explicit arguments
1079                 //
1080                 public bool ExplicitTypeInference (ResolveContext ec, TypeInferenceContext type_inference, TypeSpec delegate_type)
1081                 {
1082                         if (!HasExplicitParameters)
1083                                 return false;
1084
1085                         if (!delegate_type.IsDelegate) {
1086                                 if (!delegate_type.IsExpressionTreeType)
1087                                         return false;
1088
1089                                 delegate_type = TypeManager.GetTypeArguments (delegate_type) [0];
1090                                 if (!delegate_type.IsDelegate)
1091                                         return false;
1092                         }
1093
1094                         AParametersCollection d_params = Delegate.GetParameters (delegate_type);
1095                         if (d_params.Count != Parameters.Count)
1096                                 return false;
1097
1098                         var ptypes = Parameters.Types;
1099                         var dtypes = d_params.Types;
1100                         for (int i = 0; i < Parameters.Count; ++i) {
1101                                 if (type_inference.ExactInference (ptypes[i], dtypes[i]) == 0) {
1102                                         //
1103                                         // Continue when 0 (quick path) does not mean inference failure. Checking for
1104                                         // same type handles cases like int -> int
1105                                         //
1106                                         if (ptypes[i] == dtypes[i])
1107                                                 continue;
1108
1109                                         return false;
1110                                 }
1111                         }
1112
1113                         return true;
1114                 }
1115
1116                 public TypeSpec InferReturnType (ResolveContext ec, TypeInferenceContext tic, TypeSpec delegate_type)
1117                 {
1118                         Expression expr;
1119                         AnonymousExpression am;
1120
1121                         if (compatibles.TryGetValue (delegate_type, out expr)) {
1122                                 am = expr as AnonymousExpression;
1123                                 return am == null ? null : am.ReturnType;
1124                         }
1125
1126                         using (ec.Set (ResolveContext.Options.ProbingMode | ResolveContext.Options.InferReturnType)) {
1127                                 ReportPrinter prev;
1128                                 if (TypeInferenceReportPrinter != null) {
1129                                         prev = ec.Report.SetPrinter (TypeInferenceReportPrinter);
1130                                 } else {
1131                                         prev = null;
1132                                 }
1133
1134                                 var body = CompatibleMethodBody (ec, tic, null, delegate_type);
1135                                 if (body != null) {
1136                                         am = body.Compatible (ec, body);
1137                                 } else {
1138                                         am = null;
1139                                 }
1140
1141                                 if (TypeInferenceReportPrinter != null) {
1142                                         ec.Report.SetPrinter (prev);
1143                                 }
1144                         }
1145
1146                         if (am == null)
1147                                 return null;
1148
1149 //                      compatibles.Add (delegate_type, am);
1150                         return am.ReturnType;
1151                 }
1152
1153                 public override bool ContainsEmitWithAwait ()
1154                 {
1155                         return false;
1156                 }
1157
1158                 //
1159                 // Returns AnonymousMethod container if this anonymous method
1160                 // expression can be implicitly converted to the delegate type `delegate_type'
1161                 //
1162                 public Expression Compatible (ResolveContext ec, TypeSpec type)
1163                 {
1164                         Expression am;
1165                         if (compatibles.TryGetValue (type, out am))
1166                                 return am;
1167
1168                         TypeSpec delegate_type = CompatibleChecks (ec, type);
1169                         if (delegate_type == null)
1170                                 return null;
1171
1172                         //
1173                         // At this point its the first time we know the return type that is
1174                         // needed for the anonymous method.  We create the method here.
1175                         //
1176
1177                         var invoke_mb = Delegate.GetInvokeMethod (delegate_type);
1178                         TypeSpec return_type = invoke_mb.ReturnType;
1179
1180                         //
1181                         // Second: the return type of the delegate must be compatible with
1182                         // the anonymous type.   Instead of doing a pass to examine the block
1183                         // we satisfy the rule by setting the return type on the EmitContext
1184                         // to be the delegate type return type.
1185                         //
1186
1187                         var body = CompatibleMethodBody (ec, null, return_type, delegate_type);
1188                         if (body == null)
1189                                 return null;
1190
1191                         bool etree_conversion = delegate_type != type;
1192
1193                         try {
1194                                 if (etree_conversion) {
1195                                         if (ec.HasSet (ResolveContext.Options.ExpressionTreeConversion)) {
1196                                                 //
1197                                                 // Nested expression tree lambda use same scope as parent
1198                                                 // lambda, this also means no variable capturing between this
1199                                                 // and parent scope
1200                                                 //
1201                                                 am = body.Compatible (ec, ec.CurrentAnonymousMethod);
1202
1203                                                 //
1204                                                 // Quote nested expression tree
1205                                                 //
1206                                                 if (am != null)
1207                                                         am = new Quote (am);
1208                                         } else {
1209                                                 int errors = ec.Report.Errors;
1210
1211                                                 if (Block.IsAsync) {
1212                                                         ec.Report.Error (1989, loc, "Async lambda expressions cannot be converted to expression trees");
1213                                                 }
1214
1215                                                 using (ec.Set (ResolveContext.Options.ExpressionTreeConversion)) {
1216                                                         am = body.Compatible (ec);
1217                                                 }
1218
1219                                                 //
1220                                                 // Rewrite expressions into expression tree when targeting Expression<T>
1221                                                 //
1222                                                 if (am != null && errors == ec.Report.Errors)
1223                                                         am = CreateExpressionTree (ec, delegate_type);
1224                                         }
1225                                 } else {
1226                                         am = body.Compatible (ec);
1227                                 }
1228                         } catch (CompletionResult) {
1229                                 throw;
1230                         } catch (FatalException) {
1231                                 throw;
1232                         } catch (Exception e) {
1233                                 throw new InternalErrorException (e, loc);
1234                         }
1235
1236                         if (!ec.IsInProbingMode) {
1237                                 compatibles.Add (type, am ?? EmptyExpression.Null);
1238                         }
1239
1240                         return am;
1241                 }
1242
1243                 protected virtual Expression CreateExpressionTree (ResolveContext ec, TypeSpec delegate_type)
1244                 {
1245                         return CreateExpressionTree (ec);
1246                 }
1247
1248                 public override Expression CreateExpressionTree (ResolveContext ec)
1249                 {
1250                         ec.Report.Error (1946, loc, "An anonymous method cannot be converted to an expression tree");
1251                         return null;
1252                 }
1253
1254                 protected virtual ParametersCompiled ResolveParameters (ResolveContext ec, TypeInferenceContext tic, TypeSpec delegate_type)
1255                 {
1256                         var delegate_parameters = Delegate.GetParameters (delegate_type);
1257
1258                         if (Parameters == ParametersCompiled.Undefined) {
1259                                 //
1260                                 // We provide a set of inaccessible parameters
1261                                 //
1262                                 Parameter[] fixedpars = new Parameter[delegate_parameters.Count];
1263
1264                                 for (int i = 0; i < delegate_parameters.Count; i++) {
1265                                         Parameter.Modifier i_mod = delegate_parameters.FixedParameters [i].ModFlags;
1266                                         if ((i_mod & Parameter.Modifier.OUT) != 0) {
1267                                                 if (!ec.IsInProbingMode) {
1268                                                         ec.Report.Error (1688, loc,
1269                                                                 "Cannot convert anonymous method block without a parameter list to delegate type `{0}' because it has one or more `out' parameters",
1270                                                                 delegate_type.GetSignatureForError ());
1271                                                 }
1272
1273                                                 return null;
1274                                         }
1275                                         fixedpars[i] = new Parameter (
1276                                                 new TypeExpression (delegate_parameters.Types [i], loc), null,
1277                                                 delegate_parameters.FixedParameters [i].ModFlags, null, loc);
1278                                 }
1279
1280                                 return ParametersCompiled.CreateFullyResolved (fixedpars, delegate_parameters.Types);
1281                         }
1282
1283                         if (!VerifyExplicitParameters (ec, delegate_type, delegate_parameters)) {
1284                                 return null;
1285                         }
1286
1287                         return Parameters;
1288                 }
1289
1290                 protected override Expression DoResolve (ResolveContext ec)
1291                 {
1292                         if (ec.HasSet (ResolveContext.Options.ConstantScope)) {
1293                                 ec.Report.Error (1706, loc, "Anonymous methods and lambda expressions cannot be used in the current context");
1294                                 return null;
1295                         }
1296
1297                         //
1298                         // Set class type, set type
1299                         //
1300
1301                         eclass = ExprClass.Value;
1302
1303                         //
1304                         // This hack means `The type is not accessible
1305                         // anywhere', we depend on special conversion
1306                         // rules.
1307                         //
1308                         type = InternalType.AnonymousMethod;
1309
1310                         if (!DoResolveParameters (ec))
1311                                 return null;
1312
1313 #if !STATIC
1314                         // FIXME: The emitted code isn't very careful about reachability
1315                         // so, ensure we have a 'ret' at the end
1316                         BlockContext bc = ec as BlockContext;
1317                         if (bc != null && bc.CurrentBranching != null && bc.CurrentBranching.CurrentUsageVector.IsUnreachable)
1318                                 bc.NeedReturnLabel ();
1319 #endif
1320                         return this;
1321                 }
1322
1323                 protected virtual bool DoResolveParameters (ResolveContext rc)
1324                 {
1325                         return Parameters.Resolve (rc);
1326                 }
1327
1328                 public override void Emit (EmitContext ec)
1329                 {
1330                         // nothing, as we only exist to not do anything.
1331                 }
1332
1333                 public static void Error_AddressOfCapturedVar (ResolveContext ec, IVariableReference var, Location loc)
1334                 {
1335                         ec.Report.Error (1686, loc,
1336                                 "Local variable or parameter `{0}' cannot have their address taken and be used inside an anonymous method, lambda expression or query expression",
1337                                 var.Name);
1338                 }
1339
1340                 public override string GetSignatureForError ()
1341                 {
1342                         return ExprClassName;
1343                 }
1344
1345                 AnonymousMethodBody CompatibleMethodBody (ResolveContext ec, TypeInferenceContext tic, TypeSpec return_type, TypeSpec delegate_type)
1346                 {
1347                         ParametersCompiled p = ResolveParameters (ec, tic, delegate_type);
1348                         if (p == null)
1349                                 return null;
1350
1351                         ParametersBlock b = ec.IsInProbingMode ? (ParametersBlock) Block.PerformClone () : Block;
1352
1353                         if (b.IsAsync) {
1354                                 var rt = return_type;
1355                                 if (rt != null && rt.Kind != MemberKind.Void && rt != ec.Module.PredefinedTypes.Task.TypeSpec && !rt.IsGenericTask) {
1356                                         ec.Report.Error (4010, loc, "Cannot convert async {0} to delegate type `{1}'",
1357                                                 GetSignatureForError (), delegate_type.GetSignatureForError ());
1358
1359                                         return null;
1360                                 }
1361
1362                                 b = b.ConvertToAsyncTask (ec, ec.CurrentMemberDefinition.Parent.PartialContainer, p, return_type, loc);
1363                         }
1364
1365                         return CompatibleMethodFactory (return_type ?? InternalType.Arglist, delegate_type, p, b);
1366                 }
1367
1368                 protected virtual AnonymousMethodBody CompatibleMethodFactory (TypeSpec return_type, TypeSpec delegate_type, ParametersCompiled p, ParametersBlock b)
1369                 {
1370                         return new AnonymousMethodBody (p, b, return_type, delegate_type, loc);
1371                 }
1372
1373                 protected override void CloneTo (CloneContext clonectx, Expression t)
1374                 {
1375                         AnonymousMethodExpression target = (AnonymousMethodExpression) t;
1376
1377                         target.Block = (ParametersBlock) clonectx.LookupBlock (Block);
1378                 }
1379
1380                 public override object Accept (StructuralVisitor visitor)
1381                 {
1382                         return visitor.Visit (this);
1383                 }
1384         }
1385
1386         //
1387         // Abstract expression for any block which requires variables hoisting
1388         //
1389         public abstract class AnonymousExpression : ExpressionStatement
1390         {
1391                 protected class AnonymousMethodMethod : Method
1392                 {
1393                         public readonly AnonymousExpression AnonymousMethod;
1394                         public readonly AnonymousMethodStorey Storey;
1395
1396                         public AnonymousMethodMethod (TypeDefinition parent, AnonymousExpression am, AnonymousMethodStorey storey,
1397                                                           TypeExpr return_type,
1398                                                           Modifiers mod, MemberName name,
1399                                                           ParametersCompiled parameters)
1400                                 : base (parent, return_type, mod | Modifiers.COMPILER_GENERATED,
1401                                                 name, parameters, null)
1402                         {
1403                                 this.AnonymousMethod = am;
1404                                 this.Storey = storey;
1405
1406                                 Parent.PartialContainer.Members.Add (this);
1407                                 Block = new ToplevelBlock (am.block, parameters);
1408                         }
1409
1410                         public override EmitContext CreateEmitContext (ILGenerator ig, SourceMethodBuilder sourceMethod)
1411                         {
1412                                 EmitContext ec = new EmitContext (this, ig, ReturnType, sourceMethod);
1413                                 ec.CurrentAnonymousMethod = AnonymousMethod;
1414                                 return ec;
1415                         }
1416
1417                         protected override void DefineTypeParameters ()
1418                         {
1419                                 // Type parameters were cloned
1420                         }
1421
1422                         protected override bool ResolveMemberType ()
1423                         {
1424                                 if (!base.ResolveMemberType ())
1425                                         return false;
1426
1427                                 if (Storey != null && Storey.Mutator != null) {
1428                                         if (!parameters.IsEmpty) {
1429                                                 var mutated = Storey.Mutator.Mutate (parameters.Types);
1430                                                 if (mutated != parameters.Types)
1431                                                         parameters = ParametersCompiled.CreateFullyResolved ((Parameter[]) parameters.FixedParameters, mutated);
1432                                         }
1433
1434                                         member_type = Storey.Mutator.Mutate (member_type);
1435                                 }
1436
1437                                 return true;
1438                         }
1439
1440                         public override void Emit ()
1441                         {
1442                                 if (MethodBuilder == null) {
1443                                         Define ();
1444                                 }
1445
1446                                 base.Emit ();
1447                         }
1448                 }
1449
1450                 protected readonly ParametersBlock block;
1451
1452                 public TypeSpec ReturnType;
1453
1454                 protected AnonymousExpression (ParametersBlock block, TypeSpec return_type, Location loc)
1455                 {
1456                         this.ReturnType = return_type;
1457                         this.block = block;
1458                         this.loc = loc;
1459                 }
1460
1461                 public abstract string ContainerType { get; }
1462                 public abstract bool IsIterator { get; }
1463                 public abstract AnonymousMethodStorey Storey { get; }
1464
1465                 //
1466                 // The block that makes up the body for the anonymous method
1467                 //
1468                 public ParametersBlock Block {
1469                         get {
1470                                 return block;
1471                         }
1472                 }
1473
1474                 public AnonymousExpression Compatible (ResolveContext ec)
1475                 {
1476                         return Compatible (ec, this);
1477                 }
1478
1479                 public AnonymousExpression Compatible (ResolveContext ec, AnonymousExpression ae)
1480                 {
1481                         if (block.Resolved)
1482                                 return this;
1483
1484                         // TODO: Implement clone
1485                         BlockContext aec = new BlockContext (ec, block, ReturnType);
1486                         aec.CurrentAnonymousMethod = ae;
1487
1488                         var am = this as AnonymousMethodBody;
1489
1490                         if (ec.HasSet (ResolveContext.Options.InferReturnType) && am != null) {
1491                                 am.ReturnTypeInference = new TypeInferenceContext ();
1492                         }
1493
1494                         var bc = ec as BlockContext;
1495                         if (bc != null)
1496                                 aec.FlowOffset = bc.FlowOffset;
1497
1498                         var errors = ec.Report.Errors;
1499
1500                         bool res = Block.Resolve (ec.CurrentBranching, aec, null);
1501
1502                         if (am != null && am.ReturnTypeInference != null) {
1503                                 am.ReturnTypeInference.FixAllTypes (ec);
1504                                 ReturnType = am.ReturnTypeInference.InferredTypeArguments [0];
1505                                 am.ReturnTypeInference = null;
1506
1507                                 //
1508                                 // If e is synchronous the inferred return type is T
1509                                 // If e is asynchronous the inferred return type is Task<T>
1510                                 //
1511                                 if (block.IsAsync && ReturnType != null) {
1512                                         ReturnType = ec.Module.PredefinedTypes.TaskGeneric.TypeSpec.MakeGenericType (ec, new [] { ReturnType });
1513                                 }
1514                         }
1515
1516                         if (res && errors != ec.Report.Errors)
1517                                 return null;
1518
1519                         return res ? this : null;
1520                 }
1521
1522                 public override bool ContainsEmitWithAwait ()
1523                 {
1524                         return false;
1525                 }
1526
1527                 public void SetHasThisAccess ()
1528                 {
1529                         ExplicitBlock b = block;
1530                         do {
1531                                 if (b.HasCapturedThis)
1532                                         return;
1533
1534                                 b.HasCapturedThis = true;
1535                                 b = b.Parent == null ? null : b.Parent.Explicit;
1536                         } while (b != null);
1537                 }
1538         }
1539
1540         public class AnonymousMethodBody : AnonymousExpression
1541         {
1542                 protected readonly ParametersCompiled parameters;
1543                 AnonymousMethodStorey storey;
1544
1545                 AnonymousMethodMethod method;
1546                 Field am_cache;
1547                 string block_name;
1548                 TypeInferenceContext return_inference;
1549
1550                 public AnonymousMethodBody (ParametersCompiled parameters,
1551                                         ParametersBlock block, TypeSpec return_type, TypeSpec delegate_type,
1552                                         Location loc)
1553                         : base (block, return_type, loc)
1554                 {
1555                         this.type = delegate_type;
1556                         this.parameters = parameters;
1557                 }
1558
1559                 #region Properties
1560
1561                 public override string ContainerType {
1562                         get { return "anonymous method"; }
1563                 }
1564
1565                 public override bool IsIterator {
1566                         get {
1567                                 return false;
1568                         }
1569                 }
1570
1571                 public ParametersCompiled Parameters {
1572                         get {
1573                                 return parameters;
1574                         }
1575                 }
1576
1577                 public TypeInferenceContext ReturnTypeInference {
1578                         get {
1579                                 return return_inference;
1580                         }
1581                         set {
1582                                 return_inference = value;
1583                         }
1584                 }
1585
1586                 public override AnonymousMethodStorey Storey {
1587                         get { return storey; }
1588                 }
1589
1590                 #endregion
1591
1592                 public override Expression CreateExpressionTree (ResolveContext ec)
1593                 {
1594                         ec.Report.Error (1945, loc, "An expression tree cannot contain an anonymous method expression");
1595                         return null;
1596                 }
1597
1598                 bool Define (ResolveContext ec)
1599                 {
1600                         if (!Block.Resolved && Compatible (ec) == null)
1601                                 return false;
1602
1603                         if (block_name == null) {
1604                                 MemberCore mc = (MemberCore) ec.MemberContext;
1605                                 block_name = mc.MemberName.Basename;
1606                         }
1607
1608                         return true;
1609                 }
1610
1611                 //
1612                 // Creates a host for the anonymous method
1613                 //
1614                 AnonymousMethodMethod DoCreateMethodHost (EmitContext ec)
1615                 {
1616                         //
1617                         // Anonymous method body can be converted to
1618                         //
1619                         // 1, an instance method in current scope when only `this' is hoisted
1620                         // 2, a static method in current scope when neither `this' nor any variable is hoisted
1621                         // 3, an instance method in compiler generated storey when any hoisted variable exists
1622                         //
1623
1624                         Modifiers modifiers;
1625                         TypeDefinition parent = null;
1626
1627                         var src_block = Block.Original.Explicit;
1628                         if (src_block.HasCapturedVariable || src_block.HasCapturedThis) {
1629                                 parent = storey = FindBestMethodStorey ();
1630
1631                                 if (storey == null) {
1632                                         var sm = src_block.ParametersBlock.TopBlock.StateMachine;
1633
1634                                         //
1635                                         // Remove hoisted this demand when simple instance method is enough (no hoisted variables only this)
1636                                         //
1637                                         if (src_block.HasCapturedThis && src_block.ParametersBlock.StateMachine == null) {
1638                                                 src_block.ParametersBlock.TopBlock.RemoveThisReferenceFromChildrenBlock (src_block);
1639
1640                                                 //
1641                                                 // Special case where parent class is used to emit instance method
1642                                                 // because currect storey is of value type (async host) and we don't
1643                                                 // want to create another childer storey to host this reference only
1644                                                 //
1645                                                 if (sm != null && sm.Kind == MemberKind.Struct)
1646                                                         parent = sm.Parent.PartialContainer;
1647                                         }
1648
1649                                         //
1650                                         // For iterators we can host everything in one class
1651                                         //
1652                                         if (sm is IteratorStorey)
1653                                                 parent = storey = sm;
1654                                 }
1655
1656                                 modifiers = storey != null ? Modifiers.INTERNAL : Modifiers.PRIVATE;
1657                         } else {
1658                                 if (ec.CurrentAnonymousMethod != null)
1659                                         parent = storey = ec.CurrentAnonymousMethod.Storey;
1660
1661                                 modifiers = Modifiers.STATIC | Modifiers.PRIVATE;
1662                         }
1663
1664                         if (parent == null)
1665                                 parent = ec.CurrentTypeDefinition.Parent.PartialContainer;
1666
1667                         string name = CompilerGeneratedContainer.MakeName (parent != storey ? block_name : null,
1668                                 "m", null, ec.Module.CounterAnonymousMethods++);
1669
1670                         MemberName member_name;
1671                         if (storey == null && ec.CurrentTypeParameters != null) {
1672
1673                                 var hoisted_tparams = ec.CurrentTypeParameters;
1674                                 var type_params = new TypeParameters (hoisted_tparams.Count);
1675                                 for (int i = 0; i < hoisted_tparams.Count; ++i) {
1676                                     type_params.Add (hoisted_tparams[i].CreateHoistedCopy (null));
1677                                 }
1678
1679                                 member_name = new MemberName (name, type_params, Location);
1680                         } else {
1681                                 member_name = new MemberName (name, Location);
1682                         }
1683
1684                         return new AnonymousMethodMethod (parent,
1685                                 this, storey, new TypeExpression (ReturnType, Location), modifiers,
1686                                 member_name, parameters);
1687                 }
1688
1689                 protected override Expression DoResolve (ResolveContext ec)
1690                 {
1691                         if (!Define (ec))
1692                                 return null;
1693
1694                         eclass = ExprClass.Value;
1695                         return this;
1696                 }
1697
1698                 public override void Emit (EmitContext ec)
1699                 {
1700                         //
1701                         // Use same anonymous method implementation for scenarios where same
1702                         // code is used from multiple blocks, e.g. field initializers
1703                         //
1704                         if (method == null) {
1705                                 //
1706                                 // Delay an anonymous method definition to avoid emitting unused code
1707                                 // for unreachable blocks or expression trees
1708                                 //
1709                                 method = DoCreateMethodHost (ec);
1710                                 method.Define ();
1711                         }
1712
1713                         bool is_static = (method.ModFlags & Modifiers.STATIC) != 0;
1714                         if (is_static && am_cache == null) {
1715                                 //
1716                                 // Creates a field cache to store delegate instance if it's not generic
1717                                 //
1718                                 if (!method.MemberName.IsGeneric) {
1719                                         var parent = method.Parent.PartialContainer;
1720                                         int id = parent.AnonymousMethodsCounter++;
1721                                         var cache_type = storey != null && storey.Mutator != null ? storey.Mutator.Mutate (type) : type;
1722
1723                                         am_cache = new Field (parent, new TypeExpression (cache_type, loc),
1724                                                 Modifiers.STATIC | Modifiers.PRIVATE | Modifiers.COMPILER_GENERATED,
1725                                                 new MemberName (CompilerGeneratedContainer.MakeName (null, "f", "am$cache", id), loc), null);
1726                                         am_cache.Define ();
1727                                         parent.AddField (am_cache);
1728                                 } else {
1729                                         // TODO: Implement caching of generated generic static methods
1730                                         //
1731                                         // Idea:
1732                                         //
1733                                         // Some extra class is needed to capture variable generic type
1734                                         // arguments. Maybe we could re-use anonymous types, with a unique
1735                                         // anonymous method id, but they are quite heavy.
1736                                         //
1737                                         // Consider : "() => typeof(T);"
1738                                         //
1739                                         // We need something like
1740                                         // static class Wrap<Tn, Tm, DelegateType> {
1741                                         //              public static DelegateType cache;
1742                                         // }
1743                                         //
1744                                         // We then specialize local variable to capture all generic parameters
1745                                         // and delegate type, e.g. "Wrap<Ta, Tb, DelegateTypeInst> cache;"
1746                                         //
1747                                 }
1748                         }
1749
1750                         Label l_initialized = ec.DefineLabel ();
1751
1752                         if (am_cache != null) {
1753                                 ec.Emit (OpCodes.Ldsfld, am_cache.Spec);
1754                                 ec.Emit (OpCodes.Brtrue_S, l_initialized);
1755                         }
1756
1757                         //
1758                         // Load method delegate implementation
1759                         //
1760
1761                         if (is_static) {
1762                                 ec.EmitNull ();
1763                         } else if (storey != null) {
1764                                 Expression e = storey.GetStoreyInstanceExpression (ec).Resolve (new ResolveContext (ec.MemberContext));
1765                                 if (e != null) {
1766                                         e.Emit (ec);
1767                                 }
1768                         } else {
1769                                 ec.EmitThis ();
1770
1771                                 //
1772                                 // Special case for value type storey where this is not lifted but
1773                                 // droped off to parent class
1774                                 //
1775                                 for (var b = Block.Parent; b != null; b = b.Parent) {
1776                                         if (b.ParametersBlock.StateMachine != null) {
1777                                                 ec.Emit (OpCodes.Ldfld, b.ParametersBlock.StateMachine.HoistedThis.Field.Spec);
1778                                                 break;
1779                                         }
1780                                 }
1781                         }
1782
1783                         var delegate_method = method.Spec;
1784                         if (storey != null && storey.MemberName.IsGeneric) {
1785                                 TypeSpec t = storey.Instance.Type;
1786
1787                                 //
1788                                 // Mutate anonymous method instance type if we are in nested
1789                                 // hoisted generic anonymous method storey
1790                                 //
1791                                 if (ec.IsAnonymousStoreyMutateRequired) {
1792                                         t = storey.Mutator.Mutate (t);
1793                                 }
1794
1795                                 ec.Emit (OpCodes.Ldftn, TypeBuilder.GetMethod (t.GetMetaInfo (), (MethodInfo) delegate_method.GetMetaInfo ()));
1796                         } else {
1797                                 if (delegate_method.IsGeneric)
1798                                         delegate_method = delegate_method.MakeGenericMethod (ec.MemberContext, method.TypeParameters);
1799
1800                                 ec.Emit (OpCodes.Ldftn, delegate_method);
1801                         }
1802
1803                         var constructor_method = Delegate.GetConstructor (type);
1804                         ec.Emit (OpCodes.Newobj, constructor_method);
1805
1806                         if (am_cache != null) {
1807                                 ec.Emit (OpCodes.Stsfld, am_cache.Spec);
1808                                 ec.MarkLabel (l_initialized);
1809                                 ec.Emit (OpCodes.Ldsfld, am_cache.Spec);
1810                         }
1811                 }
1812
1813                 public override void EmitStatement (EmitContext ec)
1814                 {
1815                         throw new NotImplementedException ();
1816                 }
1817
1818                 //
1819                 // Look for the best storey for this anonymous method
1820                 //
1821                 AnonymousMethodStorey FindBestMethodStorey ()
1822                 {
1823                         //
1824                         // Use the nearest parent block which has a storey
1825                         //
1826                         for (Block b = Block.Parent; b != null; b = b.Parent) {
1827                                 AnonymousMethodStorey s = b.Explicit.AnonymousMethodStorey;
1828                                 if (s != null)
1829                                         return s;
1830                         }
1831
1832                         return null;
1833                 }
1834
1835                 public override string GetSignatureForError ()
1836                 {
1837                         return TypeManager.CSharpName (type);
1838                 }
1839         }
1840
1841         //
1842         // Anonymous type container
1843         //
1844         public class AnonymousTypeClass : CompilerGeneratedContainer
1845         {
1846                 public const string ClassNamePrefix = "<>__AnonType";
1847                 public const string SignatureForError = "anonymous type";
1848
1849                 readonly IList<AnonymousTypeParameter> parameters;
1850
1851                 private AnonymousTypeClass (ModuleContainer parent, MemberName name, IList<AnonymousTypeParameter> parameters, Location loc)
1852                         : base (parent, name, parent.Evaluator != null ? Modifiers.PUBLIC : Modifiers.INTERNAL)
1853                 {
1854                         this.parameters = parameters;
1855                 }
1856
1857                 public static AnonymousTypeClass Create (TypeContainer parent, IList<AnonymousTypeParameter> parameters, Location loc)
1858                 {
1859                         string name = ClassNamePrefix + parent.Module.CounterAnonymousTypes++;
1860
1861                         ParametersCompiled all_parameters;
1862                         TypeParameters tparams = null;
1863                         SimpleName[] t_args;
1864
1865                         if (parameters.Count == 0) {
1866                                 all_parameters = ParametersCompiled.EmptyReadOnlyParameters;
1867                                 t_args = null;
1868                         } else {
1869                                 t_args = new SimpleName[parameters.Count];
1870                                 tparams = new TypeParameters ();
1871                                 Parameter[] ctor_params = new Parameter[parameters.Count];
1872                                 for (int i = 0; i < parameters.Count; ++i) {
1873                                         AnonymousTypeParameter p = parameters[i];
1874                                         for (int ii = 0; ii < i; ++ii) {
1875                                                 if (parameters[ii].Name == p.Name) {
1876                                                         parent.Compiler.Report.Error (833, parameters[ii].Location,
1877                                                                 "`{0}': An anonymous type cannot have multiple properties with the same name",
1878                                                                         p.Name);
1879
1880                                                         p = new AnonymousTypeParameter (null, "$" + i.ToString (), p.Location);
1881                                                         parameters[i] = p;
1882                                                         break;
1883                                                 }
1884                                         }
1885
1886                                         t_args[i] = new SimpleName ("<" + p.Name + ">__T", p.Location);
1887                                         tparams.Add (new TypeParameter (i, new MemberName (t_args[i].Name, p.Location), null, null, Variance.None));
1888                                         ctor_params[i] = new Parameter (t_args[i], p.Name, Parameter.Modifier.NONE, null, p.Location);
1889                                 }
1890
1891                                 all_parameters = new ParametersCompiled (ctor_params);
1892                         }
1893
1894                         //
1895                         // Create generic anonymous type host with generic arguments
1896                         // named upon properties names
1897                         //
1898                         AnonymousTypeClass a_type = new AnonymousTypeClass (parent.Module, new MemberName (name, tparams, loc), parameters, loc);
1899
1900                         Constructor c = new Constructor (a_type, name, Modifiers.PUBLIC | Modifiers.DEBUGGER_HIDDEN,
1901                                 null, all_parameters, loc);
1902                         c.Block = new ToplevelBlock (parent.Module.Compiler, c.ParameterInfo, loc);
1903
1904                         //
1905                         // Create fields and constructor body with field initialization
1906                         //
1907                         bool error = false;
1908                         for (int i = 0; i < parameters.Count; ++i) {
1909                                 AnonymousTypeParameter p = parameters [i];
1910
1911                                 Field f = new Field (a_type, t_args [i], Modifiers.PRIVATE | Modifiers.READONLY | Modifiers.DEBUGGER_HIDDEN,
1912                                         new MemberName ("<" + p.Name + ">", p.Location), null);
1913
1914                                 if (!a_type.AddField (f)) {
1915                                         error = true;
1916                                         continue;
1917                                 }
1918
1919                                 c.Block.AddStatement (new StatementExpression (
1920                                         new SimpleAssign (new MemberAccess (new This (p.Location), f.Name),
1921                                                 c.Block.GetParameterReference (i, p.Location))));
1922
1923                                 ToplevelBlock get_block = new ToplevelBlock (parent.Module.Compiler, p.Location);
1924                                 get_block.AddStatement (new Return (
1925                                         new MemberAccess (new This (p.Location), f.Name), p.Location));
1926
1927                                 Property prop = new Property (a_type, t_args [i], Modifiers.PUBLIC,
1928                                         new MemberName (p.Name, p.Location), null);
1929                                 prop.Get = new Property.GetMethod (prop, 0, null, p.Location);
1930                                 prop.Get.Block = get_block;
1931                                 a_type.AddMember (prop);
1932                         }
1933
1934                         if (error)
1935                                 return null;
1936
1937                         a_type.AddConstructor (c);
1938                         return a_type;
1939                 }
1940
1941                 protected override bool DoDefineMembers ()
1942                 {
1943                         if (!base.DoDefineMembers ())
1944                                 return false;
1945
1946                         Location loc = Location;
1947
1948                         var equals_parameters = ParametersCompiled.CreateFullyResolved (
1949                                 new Parameter (new TypeExpression (Compiler.BuiltinTypes.Object, loc), "obj", 0, null, loc), Compiler.BuiltinTypes.Object);
1950
1951                         Method equals = new Method (this, new TypeExpression (Compiler.BuiltinTypes.Bool, loc),
1952                                 Modifiers.PUBLIC | Modifiers.OVERRIDE | Modifiers.DEBUGGER_HIDDEN, new MemberName ("Equals", loc),
1953                                 equals_parameters, null);
1954
1955                         equals_parameters[0].Resolve (equals, 0);
1956
1957                         Method tostring = new Method (this, new TypeExpression (Compiler.BuiltinTypes.String, loc),
1958                                 Modifiers.PUBLIC | Modifiers.OVERRIDE | Modifiers.DEBUGGER_HIDDEN, new MemberName ("ToString", loc),
1959                                 Mono.CSharp.ParametersCompiled.EmptyReadOnlyParameters, null);
1960
1961                         ToplevelBlock equals_block = new ToplevelBlock (Compiler, equals.ParameterInfo, loc);
1962
1963                         TypeExpr current_type;
1964                         if (CurrentTypeParameters != null) {
1965                                 var targs = new TypeArguments ();
1966                                 for (int i = 0; i < CurrentTypeParameters.Count; ++i) {
1967                                         targs.Add (new TypeParameterExpr (CurrentTypeParameters[i], Location));
1968                                 }
1969
1970                                 current_type = new GenericTypeExpr (Definition, targs, loc);
1971                         } else {
1972                                 current_type = new TypeExpression (Definition, loc);
1973                         }
1974
1975                         var li_other = LocalVariable.CreateCompilerGenerated (CurrentType, equals_block, loc);
1976                         equals_block.AddStatement (new BlockVariableDeclaration (new TypeExpression (li_other.Type, loc), li_other));
1977                         var other_variable = new LocalVariableReference (li_other, loc);
1978
1979                         MemberAccess system_collections_generic = new MemberAccess (new MemberAccess (
1980                                 new QualifiedAliasMember ("global", "System", loc), "Collections", loc), "Generic", loc);
1981
1982                         Expression rs_equals = null;
1983                         Expression string_concat = new StringConstant (Compiler.BuiltinTypes, "{", loc);
1984                         Expression rs_hashcode = new IntConstant (Compiler.BuiltinTypes, -2128831035, loc);
1985                         for (int i = 0; i < parameters.Count; ++i) {
1986                                 var p = parameters [i];
1987                                 var f = (Field) Members [i * 2];
1988
1989                                 MemberAccess equality_comparer = new MemberAccess (new MemberAccess (
1990                                         system_collections_generic, "EqualityComparer",
1991                                                 new TypeArguments (new SimpleName (CurrentTypeParameters [i].Name, loc)), loc),
1992                                                 "Default", loc);
1993
1994                                 Arguments arguments_equal = new Arguments (2);
1995                                 arguments_equal.Add (new Argument (new MemberAccess (new This (f.Location), f.Name)));
1996                                 arguments_equal.Add (new Argument (new MemberAccess (other_variable, f.Name)));
1997
1998                                 Expression field_equal = new Invocation (new MemberAccess (equality_comparer,
1999                                         "Equals", loc), arguments_equal);
2000
2001                                 Arguments arguments_hashcode = new Arguments (1);
2002                                 arguments_hashcode.Add (new Argument (new MemberAccess (new This (f.Location), f.Name)));
2003                                 Expression field_hashcode = new Invocation (new MemberAccess (equality_comparer,
2004                                         "GetHashCode", loc), arguments_hashcode);
2005
2006                                 IntConstant FNV_prime = new IntConstant (Compiler.BuiltinTypes, 16777619, loc);
2007                                 rs_hashcode = new Binary (Binary.Operator.Multiply,
2008                                         new Binary (Binary.Operator.ExclusiveOr, rs_hashcode, field_hashcode),
2009                                         FNV_prime);
2010
2011                                 Expression field_to_string = new Conditional (new BooleanExpression (new Binary (Binary.Operator.Inequality,
2012                                         new MemberAccess (new This (f.Location), f.Name), new NullLiteral (loc))),
2013                                         new Invocation (new MemberAccess (
2014                                                 new MemberAccess (new This (f.Location), f.Name), "ToString"), null),
2015                                         new StringConstant (Compiler.BuiltinTypes, string.Empty, loc), loc);
2016
2017                                 if (rs_equals == null) {
2018                                         rs_equals = field_equal;
2019                                         string_concat = new Binary (Binary.Operator.Addition,
2020                                                 string_concat,
2021                                                 new Binary (Binary.Operator.Addition,
2022                                                         new StringConstant (Compiler.BuiltinTypes, " " + p.Name + " = ", loc),
2023                                                         field_to_string));
2024                                         continue;
2025                                 }
2026
2027                                 //
2028                                 // Implementation of ToString () body using string concatenation
2029                                 //
2030                                 string_concat = new Binary (Binary.Operator.Addition,
2031                                         new Binary (Binary.Operator.Addition,
2032                                                 string_concat,
2033                                                 new StringConstant (Compiler.BuiltinTypes, ", " + p.Name + " = ", loc)),
2034                                         field_to_string);
2035
2036                                 rs_equals = new Binary (Binary.Operator.LogicalAnd, rs_equals, field_equal);
2037                         }
2038
2039                         string_concat = new Binary (Binary.Operator.Addition,
2040                                 string_concat,
2041                                 new StringConstant (Compiler.BuiltinTypes, " }", loc));
2042
2043                         //
2044                         // Equals (object obj) override
2045                         //
2046                         var other_variable_assign = new TemporaryVariableReference (li_other, loc);
2047                         equals_block.AddStatement (new StatementExpression (
2048                                 new SimpleAssign (other_variable_assign,
2049                                         new As (equals_block.GetParameterReference (0, loc),
2050                                                 current_type, loc), loc)));
2051
2052                         Expression equals_test = new Binary (Binary.Operator.Inequality, other_variable, new NullLiteral (loc));
2053                         if (rs_equals != null)
2054                                 equals_test = new Binary (Binary.Operator.LogicalAnd, equals_test, rs_equals);
2055                         equals_block.AddStatement (new Return (equals_test, loc));
2056
2057                         equals.Block = equals_block;
2058                         equals.Define ();
2059                         Members.Add (equals);
2060
2061                         //
2062                         // GetHashCode () override
2063                         //
2064                         Method hashcode = new Method (this, new TypeExpression (Compiler.BuiltinTypes.Int, loc),
2065                                 Modifiers.PUBLIC | Modifiers.OVERRIDE | Modifiers.DEBUGGER_HIDDEN,
2066                                 new MemberName ("GetHashCode", loc),
2067                                 Mono.CSharp.ParametersCompiled.EmptyReadOnlyParameters, null);
2068
2069                         //
2070                         // Modified FNV with good avalanche behavior and uniform
2071                         // distribution with larger hash sizes.
2072                         //
2073                         // const int FNV_prime = 16777619;
2074                         // int hash = (int) 2166136261;
2075                         // foreach (int d in data)
2076                         //     hash = (hash ^ d) * FNV_prime;
2077                         // hash += hash << 13;
2078                         // hash ^= hash >> 7;
2079                         // hash += hash << 3;
2080                         // hash ^= hash >> 17;
2081                         // hash += hash << 5;
2082
2083                         ToplevelBlock hashcode_top = new ToplevelBlock (Compiler, loc);
2084                         Block hashcode_block = new Block (hashcode_top, loc, loc);
2085                         hashcode_top.AddStatement (new Unchecked (hashcode_block, loc));
2086
2087                         var li_hash = LocalVariable.CreateCompilerGenerated (Compiler.BuiltinTypes.Int, hashcode_top, loc);
2088                         hashcode_block.AddStatement (new BlockVariableDeclaration (new TypeExpression (li_hash.Type, loc), li_hash));
2089                         LocalVariableReference hash_variable_assign = new LocalVariableReference (li_hash, loc);
2090                         hashcode_block.AddStatement (new StatementExpression (
2091                                 new SimpleAssign (hash_variable_assign, rs_hashcode)));
2092
2093                         var hash_variable = new LocalVariableReference (li_hash, loc);
2094                         hashcode_block.AddStatement (new StatementExpression (
2095                                 new CompoundAssign (Binary.Operator.Addition, hash_variable,
2096                                         new Binary (Binary.Operator.LeftShift, hash_variable, new IntConstant (Compiler.BuiltinTypes, 13, loc)))));
2097                         hashcode_block.AddStatement (new StatementExpression (
2098                                 new CompoundAssign (Binary.Operator.ExclusiveOr, hash_variable,
2099                                         new Binary (Binary.Operator.RightShift, hash_variable, new IntConstant (Compiler.BuiltinTypes, 7, loc)))));
2100                         hashcode_block.AddStatement (new StatementExpression (
2101                                 new CompoundAssign (Binary.Operator.Addition, hash_variable,
2102                                         new Binary (Binary.Operator.LeftShift, hash_variable, new IntConstant (Compiler.BuiltinTypes, 3, loc)))));
2103                         hashcode_block.AddStatement (new StatementExpression (
2104                                 new CompoundAssign (Binary.Operator.ExclusiveOr, hash_variable,
2105                                         new Binary (Binary.Operator.RightShift, hash_variable, new IntConstant (Compiler.BuiltinTypes, 17, loc)))));
2106                         hashcode_block.AddStatement (new StatementExpression (
2107                                 new CompoundAssign (Binary.Operator.Addition, hash_variable,
2108                                         new Binary (Binary.Operator.LeftShift, hash_variable, new IntConstant (Compiler.BuiltinTypes, 5, loc)))));
2109
2110                         hashcode_block.AddStatement (new Return (hash_variable, loc));
2111                         hashcode.Block = hashcode_top;
2112                         hashcode.Define ();
2113                         Members.Add (hashcode);
2114
2115                         //
2116                         // ToString () override
2117                         //
2118
2119                         ToplevelBlock tostring_block = new ToplevelBlock (Compiler, loc);
2120                         tostring_block.AddStatement (new Return (string_concat, loc));
2121                         tostring.Block = tostring_block;
2122                         tostring.Define ();
2123                         Members.Add (tostring);
2124
2125                         return true;
2126                 }
2127
2128                 public override string GetSignatureForError ()
2129                 {
2130                         return SignatureForError;
2131                 }
2132
2133                 public override CompilationSourceFile GetCompilationSourceFile ()
2134                 {
2135                         return null;
2136                 }
2137
2138                 public IList<AnonymousTypeParameter> Parameters {
2139                         get {
2140                                 return parameters;
2141                         }
2142                 }
2143         }
2144 }