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                         readonly AnonymousMethodStorey parent;
 195
 196                         public ThisInitializer (HoistedThis hoisted_this, AnonymousMethodStorey parent)
 197                         {
 198                                 this.hoisted_this = hoisted_this;
 199                                 this.parent = parent;
 200                         }
 201
 202                         protected override void DoEmit (EmitContext ec)
 203                         {
 204                                 Expression source;
 205
 206                                 if (parent == null)
 207                                         source = new CompilerGeneratedThis (ec.CurrentType, loc);
 208                                 else {
 209                                         source = new FieldExpr (parent.HoistedThis.Field, Location.Null) {
 210                                                 InstanceExpression = new CompilerGeneratedThis (ec.CurrentType, Location.Null)
 211                                         };
 212                                 }
 213
 214                                 hoisted_this.EmitAssign (ec, source, false, false);
 215                         }
 216
 217                         protected override bool DoFlowAnalysis (FlowAnalysisContext fc)
 218                         {
 219                                 return false;
 220                         }
 221
 222                         protected override void CloneTo (CloneContext clonectx, Statement target)
 223                         {
 224                                 // Nothing to clone
 225                         }
 226                 }
 227
 228                 // Unique storey ID
 229                 public readonly int ID;
 230
 231                 public readonly ExplicitBlock OriginalSourceBlock;
 232
 233                 // A list of StoreyFieldPair with local field keeping parent storey instance
 234                 List<StoreyFieldPair> used_parent_storeys;
 235                 List<ExplicitBlock> children_references;
 236
 237                 // A list of hoisted parameters
 238                 protected List<HoistedParameter> hoisted_params;
 239                 List<HoistedParameter> hoisted_local_params;
 240                 protected List<HoistedVariable> hoisted_locals;
 241
 242                 // Hoisted this
 243                 protected HoistedThis hoisted_this;
 244
 245                 // Local variable which holds this storey instance
 246                 public Expression Instance;
 247
 248                 bool initialize_hoisted_this;
 249                 AnonymousMethodStorey hoisted_this_parent;
 250
 251                 public AnonymousMethodStorey (ExplicitBlock block, TypeDefinition parent, MemberBase host, TypeParameters tparams, string name, MemberKind kind)
 252                         : base (parent, MakeMemberName (host, name, parent.PartialContainer.CounterAnonymousContainers, tparams, block.StartLocation),
 253                                 tparams, 0, kind)
 254                 {
 255                         OriginalSourceBlock = block;
 256                         ID = parent.PartialContainer.CounterAnonymousContainers++;
 257                 }
 258
 259                 public void AddCapturedThisField (EmitContext ec, AnonymousMethodStorey parent)
 260                 {
 261                         TypeExpr type_expr = new TypeExpression (ec.CurrentType, Location);
 262                         Field f = AddCompilerGeneratedField ("$this", type_expr);
 263                         hoisted_this = new HoistedThis (this, f);
 264
 265                         initialize_hoisted_this = true;
 266                         hoisted_this_parent = parent;
 267                 }
 268
 269                 public Field AddCapturedVariable (string name, TypeSpec type)
 270                 {
 271                         CheckMembersDefined ();
 272
 273                         FullNamedExpression field_type = new TypeExpression (type, Location);
 274                         if (!spec.IsGenericOrParentIsGeneric)
 275                                 return AddCompilerGeneratedField (name, field_type);
 276
 277                         const Modifiers mod = Modifiers.INTERNAL | Modifiers.COMPILER_GENERATED;
 278                         Field f = new HoistedField (this, field_type, mod, name, null, Location);
 279                         AddField (f);
 280                         return f;
 281                 }
 282
 283                 protected Field AddCompilerGeneratedField (string name, FullNamedExpression type)
 284                 {
 285                         return AddCompilerGeneratedField (name, type, false);
 286                 }
 287
 288                 protected Field AddCompilerGeneratedField (string name, FullNamedExpression type, bool privateAccess)
 289                 {
 290                         Modifiers mod = Modifiers.COMPILER_GENERATED | (privateAccess ? Modifiers.PRIVATE : Modifiers.INTERNAL);
 291                         Field f = new Field (this, type, mod, new MemberName (name, Location), null);
 292                         AddField (f);
 293                         return f;
 294                 }
 295
 296                 //
 297                 // Creates a link between hoisted variable block and the anonymous method storey
 298                 //
 299                 // An anonymous method can reference variables from any outer block, but they are
 300                 // hoisted in their own ExplicitBlock. When more than one block is referenced we
 301                 // need to create another link between those variable storeys
 302                 //
 303                 public void AddReferenceFromChildrenBlock (ExplicitBlock block)
 304                 {
 305                         if (children_references == null)
 306                                 children_references = new List<ExplicitBlock> ();
 307
 308                         if (!children_references.Contains (block))
 309                                 children_references.Add (block);
 310                 }
 311
 312                 public void AddParentStoreyReference (EmitContext ec, AnonymousMethodStorey storey)
 313                 {
 314                         CheckMembersDefined ();
 315
 316                         if (used_parent_storeys == null)
 317                                 used_parent_storeys = new List<StoreyFieldPair> ();
 318                         else if (used_parent_storeys.Exists (i => i.Storey == storey))
 319                                 return;
 320
 321                         TypeExpr type_expr = storey.CreateStoreyTypeExpression (ec);
 322                         Field f = AddCompilerGeneratedField ("<>f__ref$" + storey.ID, type_expr);
 323                         used_parent_storeys.Add (new StoreyFieldPair (storey, f));
 324                 }
 325
 326                 public void CaptureLocalVariable (ResolveContext ec, LocalVariable localVariable)
 327                 {
 328                         if (this is StateMachine) {
 329                                 if (ec.CurrentBlock.ParametersBlock != localVariable.Block.ParametersBlock)
 330                                         ec.CurrentBlock.Explicit.HasCapturedVariable = true;
 331                         } else {
 332                                 ec.CurrentBlock.Explicit.HasCapturedVariable = true;
 333                         }
 334
 335                         var hoisted = localVariable.HoistedVariant;
 336                         if (hoisted != null && hoisted.Storey != this && hoisted.Storey is StateMachine) {
 337                                 //
 338                                 // Variable is already hoisted but we need it in storey which can be shared
 339                                 //
 340                                 hoisted.Storey.hoisted_locals.Remove (hoisted);
 341                                 hoisted.Storey.Members.Remove (hoisted.Field);
 342                                 hoisted = null;
 343                         }
 344
 345                         if (hoisted == null) {
 346                                 hoisted = new HoistedLocalVariable (this, localVariable, GetVariableMangledName (localVariable));
 347                                 localVariable.HoistedVariant = hoisted;
 348
 349                                 if (hoisted_locals == null)
 350                                         hoisted_locals = new List<HoistedVariable> ();
 351
 352                                 hoisted_locals.Add (hoisted);
 353                         }
 354
 355                         if (ec.CurrentBlock.Explicit != localVariable.Block.Explicit && !(hoisted.Storey is StateMachine) && hoisted.Storey != null)
 356                                 hoisted.Storey.AddReferenceFromChildrenBlock (ec.CurrentBlock.Explicit);
 357                 }
 358
 359                 public void CaptureParameter (ResolveContext ec, ParametersBlock.ParameterInfo parameterInfo, ParameterReference parameterReference)
 360                 {
 361                         if (!(this is StateMachine)) {
 362                                 ec.CurrentBlock.Explicit.HasCapturedVariable = true;
 363                         }
 364
 365                         var hoisted = parameterInfo.Parameter.HoistedVariant;
 366
 367                         if (parameterInfo.Block.StateMachine != null) {
 368                                 //
 369                                 // Another storey in same block exists but state machine does not
 370                                 // have parameter captured. We need to add it there as well to
 371                                 // proxy parameter value correctly.
 372                                 //
 373                                 if (hoisted == null && parameterInfo.Block.StateMachine != this) {
 374                                         var storey = parameterInfo.Block.StateMachine;
 375
 376                                         hoisted = new HoistedParameter (storey, parameterReference);
 377                                         parameterInfo.Parameter.HoistedVariant = hoisted;
 378
 379                                         if (storey.hoisted_params == null)
 380                                                 storey.hoisted_params = new List<HoistedParameter> ();
 381
 382                                         storey.hoisted_params.Add (hoisted);
 383                                 }
 384
 385                                 //
 386                                 // Lift captured parameter from value type storey to reference type one. Otherwise
 387                                 // any side effects would be done on a copy
 388                                 //
 389                                 if (hoisted != null && hoisted.Storey != this && hoisted.Storey is StateMachine) {
 390                                         if (hoisted_local_params == null)
 391                                                 hoisted_local_params = new List<HoistedParameter> ();
 392
 393                                         hoisted_local_params.Add (hoisted);
 394                                         hoisted = null;
 395                                 }
 396                         }
 397
 398                         if (hoisted == null) {
 399                                 hoisted = new HoistedParameter (this, parameterReference);
 400                                 parameterInfo.Parameter.HoistedVariant = hoisted;
 401
 402                                 if (hoisted_params == null)
 403                                         hoisted_params = new List<HoistedParameter> ();
 404
 405                                 hoisted_params.Add (hoisted);
 406                         }
 407
 408                         //
 409                         // Register link between current block and parameter storey. It will
 410                         // be used when setting up storey definition to deploy storey reference
 411                         // when parameters are used from multiple blocks
 412                         //
 413                         if (ec.CurrentBlock.Explicit != parameterInfo.Block) {
 414                                 hoisted.Storey.AddReferenceFromChildrenBlock (ec.CurrentBlock.Explicit);
 415                         }
 416                 }
 417
 418                 TypeExpr CreateStoreyTypeExpression (EmitContext ec)
 419                 {
 420                         //
 421                         // Create an instance of storey type
 422                         //
 423                         TypeExpr storey_type_expr;
 424                         if (CurrentTypeParameters != null) {
 425                                 //
 426                                 // Use current method type parameter (MVAR) for top level storey only. All
 427                                 // nested storeys use class type parameter (VAR)
 428                                 //
 429                                 var tparams = ec.CurrentAnonymousMethod != null && ec.CurrentAnonymousMethod.Storey != null ?
 430                                         ec.CurrentAnonymousMethod.Storey.CurrentTypeParameters :
 431                                         ec.CurrentTypeParameters;
 432
 433                                 TypeArguments targs = new TypeArguments ();
 434
 435                                 //
 436                                 // Use type parameter name instead of resolved type parameter
 437                                 // specification to resolve to correctly nested type parameters
 438                                 //
 439                                 for (int i = 0; i < tparams.Count; ++i)
 440                                         targs.Add (new SimpleName (tparams [i].Name, Location)); //  new TypeParameterExpr (tparams[i], Location));
 441
 442                                 storey_type_expr = new GenericTypeExpr (Definition, targs, Location);
 443                         } else {
 444                                 storey_type_expr = new TypeExpression (CurrentType, Location);
 445                         }
 446
 447                         return storey_type_expr;
 448                 }
 449
 450                 public void SetNestedStoryParent (AnonymousMethodStorey parentStorey)
 451                 {
 452                         Parent = parentStorey;
 453                         spec.IsGeneric = false;
 454                         spec.DeclaringType = parentStorey.CurrentType;
 455                         MemberName.TypeParameters = null;
 456                 }
 457
 458                 protected override bool DoResolveTypeParameters ()
 459                 {
 460                         // Although any storey can have type parameters they are all clones of method type
 461                         // parameters therefore have to mutate MVAR references in any of cloned constraints
 462                         if (CurrentTypeParameters != null) {
 463                                 for (int i = 0; i < CurrentTypeParameters.Count; ++i) {
 464                                         var spec = CurrentTypeParameters[i].Type;
 465                                         spec.BaseType = mutator.Mutate (spec.BaseType);
 466                                         if (spec.InterfacesDefined != null) {
 467                                                 var mutated = new TypeSpec[spec.InterfacesDefined.Length];
 468                                                 for (int ii = 0; ii < mutated.Length; ++ii) {
 469                                                         mutated[ii] = mutator.Mutate (spec.InterfacesDefined[ii]);
 470                                                 }
 471
 472                                                 spec.InterfacesDefined = mutated;
 473                                         }
 474
 475                                         if (spec.TypeArguments != null) {
 476                                                 spec.TypeArguments = mutator.Mutate (spec.TypeArguments);
 477                                         }
 478                                 }
 479                         }
 480
 481                         //
 482                         // Update parent cache as we most likely passed the point
 483                         // where the cache was constructed
 484                         //
 485                         Parent.CurrentType.MemberCache.AddMember (this.spec);
 486
 487                         return true;
 488                 }
 489
 490                 //
 491                 // Initializes all hoisted variables
 492                 //
 493                 public void EmitStoreyInstantiation (EmitContext ec, ExplicitBlock block)
 494                 {
 495                         // There can be only one instance variable for each storey type
 496                         if (Instance != null)
 497                                 throw new InternalErrorException ();
 498
 499                         //
 500                         // Create an instance of this storey
 501                         //
 502                         ResolveContext rc = new ResolveContext (ec.MemberContext);
 503                         rc.CurrentBlock = block;
 504
 505                         var storey_type_expr = CreateStoreyTypeExpression (ec);
 506                         var source = new New (storey_type_expr, null, Location).Resolve (rc);
 507
 508                         //
 509                         // When the current context is async (or iterator) lift local storey
 510                         // instantiation to the currect storey
 511                         //
 512                         if (ec.CurrentAnonymousMethod is StateMachineInitializer && (block.HasYield || block.HasAwait)) {
 513                                 //
 514                                 // Unfortunately, normal capture mechanism could not be used because we are
 515                                 // too late in the pipeline and standart assign cannot be used either due to
 516                                 // recursive nature of GetStoreyInstanceExpression
 517                                 //
 518                                 var field = ec.CurrentAnonymousMethod.Storey.AddCompilerGeneratedField (
 519                                         LocalVariable.GetCompilerGeneratedName (block), storey_type_expr, true);
 520
 521                                 field.Define ();
 522                                 field.Emit ();
 523
 524                                 var fexpr = new FieldExpr (field, Location);
 525                                 fexpr.InstanceExpression = new CompilerGeneratedThis (ec.CurrentType, Location);
 526                                 fexpr.EmitAssign (ec, source, false, false);
 527                                 Instance = fexpr;
 528                         } else {
 529                                 var local = TemporaryVariableReference.Create (source.Type, block, Location, writeToSymbolFile: true);
 530                                 if (source.Type.IsStruct) {
 531                                         local.LocalInfo.CreateBuilder (ec);
 532                                 } else {
 533                                         local.EmitAssign (ec, source);
 534                                 }
 535
 536                                 Instance = local;
 537                         }
 538
 539                         EmitHoistedFieldsInitialization (rc, ec);
 540
 541                         // TODO: Implement properly
 542                         //SymbolWriter.DefineScopeVariable (ID, Instance.Builder);
 543                 }
 544
 545                 void EmitHoistedFieldsInitialization (ResolveContext rc, EmitContext ec)
 546                 {
 547                         //
 548                         // Initialize all storey reference fields by using local or hoisted variables
 549                         //
 550                         if (used_parent_storeys != null) {
 551                                 foreach (StoreyFieldPair sf in used_parent_storeys) {
 552                                         //
 553                                         // Get instance expression of storey field
 554                                         //
 555                                         Expression instace_expr = GetStoreyInstanceExpression (ec);
 556                                         var fs = sf.Field.Spec;
 557                                         if (TypeManager.IsGenericType (instace_expr.Type))
 558                                                 fs = MemberCache.GetMember (instace_expr.Type, fs);
 559
 560                                         FieldExpr f_set_expr = new FieldExpr (fs, Location);
 561                                         f_set_expr.InstanceExpression = instace_expr;
 562
 563                                         // TODO: CompilerAssign expression
 564                                         SimpleAssign a = new SimpleAssign (f_set_expr, sf.Storey.GetStoreyInstanceExpression (ec));
 565                                         if (a.Resolve (rc) != null)
 566                                                 a.EmitStatement (ec);
 567                                 }
 568                         }
 569
 570                         //
 571                         // Initialize hoisted `this' only once, everywhere else will be
 572                         // referenced indirectly
 573                         //
 574                         if (initialize_hoisted_this) {
 575                                 rc.CurrentBlock.AddScopeStatement (new ThisInitializer (hoisted_this, hoisted_this_parent));
 576                         }
 577
 578                         //
 579                         // Setting currect anonymous method to null blocks any further variable hoisting
 580                         //
 581                         AnonymousExpression ae = ec.CurrentAnonymousMethod;
 582                         ec.CurrentAnonymousMethod = null;
 583
 584                         if (hoisted_params != null) {
 585                                 EmitHoistedParameters (ec, hoisted_params);
 586                         }
 587
 588                         ec.CurrentAnonymousMethod = ae;
 589                 }
 590
 591                 protected virtual void EmitHoistedParameters (EmitContext ec, List<HoistedParameter> hoisted)
 592                 {
 593                         foreach (HoistedParameter hp in hoisted) {
 594                                 if (hp == null)
 595                                         continue;
 596
 597                                 //
 598                                 // Parameters could be proxied via local fields for value type storey
 599                                 //
 600                                 if (hoisted_local_params != null) {
 601                                         var local_param = hoisted_local_params.Find (l => l.Parameter.Parameter == hp.Parameter.Parameter);
 602                                         var source = new FieldExpr (local_param.Field, Location);
 603                                         source.InstanceExpression = new CompilerGeneratedThis (CurrentType, Location);
 604                                         hp.EmitAssign (ec, source, false, false);
 605                                         continue;
 606                                 }
 607
 608                                 hp.EmitHoistingAssignment (ec);
 609                         }
 610                 }
 611
 612                 //
 613                 // Returns a field which holds referenced storey instance
 614                 //
 615                 Field GetReferencedStoreyField (AnonymousMethodStorey storey)
 616                 {
 617                         if (used_parent_storeys == null)
 618                                 return null;
 619
 620                         foreach (StoreyFieldPair sf in used_parent_storeys) {
 621                                 if (sf.Storey == storey)
 622                                         return sf.Field;
 623                         }
 624
 625                         return null;
 626                 }
 627
 628                 //
 629                 // Creates storey instance expression regardless of currect IP
 630                 //
 631                 public Expression GetStoreyInstanceExpression (EmitContext ec)
 632                 {
 633                         AnonymousExpression am = ec.CurrentAnonymousMethod;
 634
 635                         //
 636                         // Access from original block -> storey
 637                         //
 638                         if (am == null)
 639                                 return Instance;
 640
 641                         //
 642                         // Access from anonymous method implemented as a static -> storey
 643                         //
 644                         if (am.Storey == null)
 645                                 return Instance;
 646
 647                         Field f = am.Storey.GetReferencedStoreyField (this);
 648                         if (f == null) {
 649                                 if (am.Storey == this) {
 650                                         //
 651                                         // Access from inside of same storey (S -> S)
 652                                         //
 653                                         return new CompilerGeneratedThis (CurrentType, Location);
 654                                 }
 655
 656                                 //
 657                                 // External field access
 658                                 //
 659                                 return Instance;
 660                         }
 661
 662                         //
 663                         // Storey was cached to local field
 664                         //
 665                         FieldExpr f_ind = new FieldExpr (f, Location);
 666                         f_ind.InstanceExpression = new CompilerGeneratedThis (CurrentType, Location);
 667                         return f_ind;
 668                 }
 669
 670                 protected virtual string GetVariableMangledName (LocalVariable local_info)
 671                 {
 672                         //
 673                         // No need to mangle anonymous method hoisted variables cause they
 674                         // are hoisted in their own scopes
 675                         //
 676                         return local_info.Name;
 677                 }
 678
 679                 public HoistedThis HoistedThis {
 680                         get {
 681                                 return hoisted_this;
 682                         }
 683                         set {
 684                                 hoisted_this = value;
 685                         }
 686                 }
 687
 688                 public IList<ExplicitBlock> ReferencesFromChildrenBlock {
 689                         get { return children_references; }
 690                 }
 691         }
 692
 693         public abstract class HoistedVariable
 694         {
 695                 //
 696                 // Hoisted version of variable references used in expression
 697                 // tree has to be delayed until we know its location. The variable
 698                 // doesn't know its location until all stories are calculated
 699                 //
 700                 class ExpressionTreeVariableReference : Expression
 701                 {
 702                         readonly HoistedVariable hv;
 703
 704                         public ExpressionTreeVariableReference (HoistedVariable hv)
 705                         {
 706                                 this.hv = hv;
 707                         }
 708
 709                         public override bool ContainsEmitWithAwait ()
 710                         {
 711                                 return false;
 712                         }
 713
 714                         public override Expression CreateExpressionTree (ResolveContext ec)
 715                         {
 716                                 return hv.CreateExpressionTree ();
 717                         }
 718
 719                         protected override Expression DoResolve (ResolveContext ec)
 720                         {
 721                                 eclass = ExprClass.Value;
 722                                 type = ec.Module.PredefinedTypes.Expression.Resolve ();
 723                                 return this;
 724                         }
 725
 726                         public override void Emit (EmitContext ec)
 727                         {
 728                                 ResolveContext rc = new ResolveContext (ec.MemberContext);
 729                                 Expression e = hv.GetFieldExpression (ec).CreateExpressionTree (rc, false);
 730                                 // This should never fail
 731                                 e = e.Resolve (rc);
 732                                 if (e != null)
 733                                         e.Emit (ec);
 734                         }
 735                 }
 736
 737                 protected readonly AnonymousMethodStorey storey;
 738                 protected Field field;
 739                 Dictionary<AnonymousExpression, FieldExpr> cached_inner_access; // TODO: Hashtable is too heavyweight
 740                 FieldExpr cached_outer_access;
 741
 742                 protected HoistedVariable (AnonymousMethodStorey storey, string name, TypeSpec type)
 743                         : this (storey, storey.AddCapturedVariable (name, type))
 744                 {
 745                 }
 746
 747                 protected HoistedVariable (AnonymousMethodStorey storey, Field field)
 748                 {
 749                         this.storey = storey;
 750                         this.field = field;
 751                 }
 752
 753                 public Field Field {
 754                         get {
 755                                 return field;
 756                         }
 757                 }
 758
 759                 public AnonymousMethodStorey Storey {
 760                         get {
 761                                 return storey;
 762                         }
 763                 }
 764
 765                 public void AddressOf (EmitContext ec, AddressOp mode)
 766                 {
 767                         GetFieldExpression (ec).AddressOf (ec, mode);
 768                 }
 769
 770                 public Expression CreateExpressionTree ()
 771                 {
 772                         return new ExpressionTreeVariableReference (this);
 773                 }
 774
 775                 public void Emit (EmitContext ec)
 776                 {
 777                         GetFieldExpression (ec).Emit (ec);
 778                 }
 779
 780                 public Expression EmitToField (EmitContext ec)
 781                 {
 782                         return GetFieldExpression (ec);
 783                 }
 784
 785                 //
 786                 // Creates field access expression for hoisted variable
 787                 //
 788                 protected virtual FieldExpr GetFieldExpression (EmitContext ec)
 789                 {
 790                         if (ec.CurrentAnonymousMethod == null || ec.CurrentAnonymousMethod.Storey == null) {
 791                                 if (cached_outer_access != null)
 792                                         return cached_outer_access;
 793
 794                                 //
 795                                 // When setting top-level hoisted variable in generic storey
 796                                 // change storey generic types to method generic types (VAR -> MVAR)
 797                                 //
 798                                 if (storey.Instance.Type.IsGenericOrParentIsGeneric) {
 799                                         var fs = MemberCache.GetMember (storey.Instance.Type, field.Spec);
 800                                         cached_outer_access = new FieldExpr (fs, field.Location);
 801                                 } else {
 802                                         cached_outer_access = new FieldExpr (field, field.Location);
 803                                 }
 804
 805                                 cached_outer_access.InstanceExpression = storey.GetStoreyInstanceExpression (ec);
 806                                 return cached_outer_access;
 807                         }
 808
 809                         FieldExpr inner_access;
 810                         if (cached_inner_access != null) {
 811                                 if (!cached_inner_access.TryGetValue (ec.CurrentAnonymousMethod, out inner_access))
 812                                         inner_access = null;
 813                         } else {
 814                                 inner_access = null;
 815                                 cached_inner_access = new Dictionary<AnonymousExpression, FieldExpr> (4);
 816                         }
 817
 818                         if (inner_access == null) {
 819                                 if (field.Parent.IsGenericOrParentIsGeneric) {
 820                                         var fs = MemberCache.GetMember (field.Parent.CurrentType, field.Spec);
 821                                         inner_access = new FieldExpr (fs, field.Location);
 822                                 } else {
 823                                         inner_access = new FieldExpr (field, field.Location);
 824                                 }
 825
 826                                 inner_access.InstanceExpression = storey.GetStoreyInstanceExpression (ec);
 827                                 cached_inner_access.Add (ec.CurrentAnonymousMethod, inner_access);
 828                         }
 829
 830                         return inner_access;
 831                 }
 832
 833                 public void Emit (EmitContext ec, bool leave_copy)
 834                 {
 835                         GetFieldExpression (ec).Emit (ec, leave_copy);
 836                 }
 837
 838                 public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool isCompound)
 839                 {
 840                         GetFieldExpression (ec).EmitAssign (ec, source, leave_copy, false);
 841                 }
 842         }
 843
 844         public class HoistedParameter : HoistedVariable
 845         {
 846                 sealed class HoistedFieldAssign : CompilerAssign
 847                 {
 848                         public HoistedFieldAssign (Expression target, Expression source)
 849                                 : base (target, source, target.Location)
 850                         {
 851                         }
 852
 853                         protected override Expression ResolveConversions (ResolveContext ec)
 854                         {
 855                                 //
 856                                 // Implicit conversion check fails for hoisted type arguments
 857                                 // as they are of different types (!!0 x !0)
 858                                 //
 859                                 return this;
 860                         }
 861                 }
 862
 863                 readonly ParameterReference parameter;
 864
 865                 public HoistedParameter (AnonymousMethodStorey scope, ParameterReference par)
 866                         : base (scope, par.Name, par.Type)
 867                 {
 868                         this.parameter = par;
 869                 }
 870
 871                 public HoistedParameter (HoistedParameter hp, string name)
 872                         : base (hp.storey, name, hp.parameter.Type)
 873                 {
 874                         this.parameter = hp.parameter;
 875                 }
 876
 877                 #region Properties
 878
 879                 public bool IsAssigned { get; set; }
 880
 881                 public ParameterReference Parameter {
 882                         get {
 883                                 return parameter;
 884                         }
 885                 }
 886
 887                 #endregion
 888
 889                 public void EmitHoistingAssignment (EmitContext ec)
 890                 {
 891                         //
 892                         // Remove hoisted redirection to emit assignment from original parameter
 893                         //
 894                         var temp = parameter.Parameter.HoistedVariant;
 895                         parameter.Parameter.HoistedVariant = null;
 896
 897                         var a = new HoistedFieldAssign (GetFieldExpression (ec), parameter);
 898                         a.EmitStatement (ec);
 899
 900                         parameter.Parameter.HoistedVariant = temp;
 901                 }
 902         }
 903
 904         class HoistedLocalVariable : HoistedVariable
 905         {
 906                 public HoistedLocalVariable (AnonymousMethodStorey storey, LocalVariable local, string name)
 907                         : base (storey, name, local.Type)
 908                 {
 909                 }
 910         }
 911
 912         public class HoistedThis : HoistedVariable
 913         {
 914                 public HoistedThis (AnonymousMethodStorey storey, Field field)
 915                         : base (storey, field)
 916                 {
 917                 }
 918         }
 919
 920         //
 921         // Anonymous method expression as created by parser
 922         //
 923         public class AnonymousMethodExpression : Expression
 924         {
 925                 //
 926                 // Special conversion for nested expression tree lambdas
 927                 //
 928                 class Quote : ShimExpression
 929                 {
 930                         public Quote (Expression expr)
 931                                 : base (expr)
 932                         {
 933                         }
 934
 935                         public override Expression CreateExpressionTree (ResolveContext ec)
 936                         {
 937                                 var args = new Arguments (1);
 938                                 args.Add (new Argument (expr.CreateExpressionTree (ec)));
 939                                 return CreateExpressionFactoryCall (ec, "Quote", args);
 940                         }
 941
 942                         protected override Expression DoResolve (ResolveContext rc)
 943                         {
 944                                 expr = expr.Resolve (rc);
 945                                 if (expr == null)
 946                                         return null;
 947
 948                                 eclass = expr.eclass;
 949                                 type = expr.Type;
 950                                 return this;
 951                         }
 952                 }
 953
 954                 readonly Dictionary<TypeSpec, Expression> compatibles;
 955
 956                 public ParametersBlock Block;
 957
 958                 public AnonymousMethodExpression (Location loc)
 959                 {
 960                         this.loc = loc;
 961                         this.compatibles = new Dictionary<TypeSpec, Expression> ();
 962                 }
 963
 964                 #region Properties
 965
 966                 public override string ExprClassName {
 967                         get {
 968                                 return "anonymous method";
 969                         }
 970                 }
 971
 972                 public virtual bool HasExplicitParameters {
 973                         get {
 974                                 return Parameters != ParametersCompiled.Undefined;
 975                         }
 976                 }
 977
 978                 public override bool IsSideEffectFree {
 979                         get {
 980                                 return true;
 981                         }
 982                 }
 983
 984                 public ParametersCompiled Parameters {
 985                         get {
 986                                 return Block.Parameters;
 987                         }
 988                 }
 989
 990                 public ReportPrinter TypeInferenceReportPrinter {
 991                         get; set;
 992                 }
 993
 994                 #endregion
 995
 996                 //
 997                 // Returns true if the body of lambda expression can be implicitly
 998                 // converted to the delegate of type `delegate_type'
 999                 //
1000                 public bool ImplicitStandardConversionExists (ResolveContext ec, TypeSpec delegate_type)
1001                 {
1002                         using (ec.With (ResolveContext.Options.InferReturnType, false)) {
1003                                 using (ec.Set (ResolveContext.Options.ProbingMode)) {
1004                                         var prev = ec.Report.SetPrinter (TypeInferenceReportPrinter ?? new NullReportPrinter ());
1005
1006                                         var res = Compatible (ec, delegate_type) != null;
1007
1008                                         ec.Report.SetPrinter (prev);
1009
1010                                         return res;
1011                                 }
1012                         }
1013                 }
1014
1015                 TypeSpec CompatibleChecks (ResolveContext ec, TypeSpec delegate_type)
1016                 {
1017                         if (delegate_type.IsDelegate)
1018                                 return delegate_type;
1019
1020                         if (delegate_type.IsExpressionTreeType) {
1021                                 delegate_type = delegate_type.TypeArguments [0];
1022                                 if (delegate_type.IsDelegate)
1023                                         return delegate_type;
1024
1025                                 ec.Report.Error (835, loc, "Cannot convert `{0}' to an expression tree of non-delegate type `{1}'",
1026                                         GetSignatureForError (), delegate_type.GetSignatureForError ());
1027                                 return null;
1028                         }
1029
1030                         ec.Report.Error (1660, loc, "Cannot convert `{0}' to non-delegate type `{1}'",
1031                                       GetSignatureForError (), delegate_type.GetSignatureForError ());
1032                         return null;
1033                 }
1034
1035                 protected bool VerifyExplicitParameters (ResolveContext ec, TypeInferenceContext tic, TypeSpec delegate_type, AParametersCollection parameters)
1036                 {
1037                         if (VerifyParameterCompatibility (ec, tic, delegate_type, parameters, ec.IsInProbingMode))
1038                                 return true;
1039
1040                         if (!ec.IsInProbingMode)
1041                                 ec.Report.Error (1661, loc,
1042                                         "Cannot convert `{0}' to delegate type `{1}' since there is a parameter mismatch",
1043                                         GetSignatureForError (), delegate_type.GetSignatureForError ());
1044
1045                         return false;
1046                 }
1047
1048                 protected bool VerifyParameterCompatibility (ResolveContext ec, TypeInferenceContext tic, TypeSpec delegate_type, AParametersCollection invoke_pd, bool ignore_errors)
1049                 {
1050                         if (Parameters.Count != invoke_pd.Count) {
1051                                 if (ignore_errors)
1052                                         return false;
1053
1054                                 ec.Report.Error (1593, loc, "Delegate `{0}' does not take `{1}' arguments",
1055                                               delegate_type.GetSignatureForError (), Parameters.Count.ToString ());
1056                                 return false;
1057                         }
1058
1059                         bool has_implicit_parameters = !HasExplicitParameters;
1060                         bool error = false;
1061
1062                         for (int i = 0; i < Parameters.Count; ++i) {
1063                                 Parameter.Modifier p_mod = invoke_pd.FixedParameters [i].ModFlags;
1064                                 if (Parameters.FixedParameters [i].ModFlags != p_mod && p_mod != Parameter.Modifier.PARAMS) {
1065                                         if (ignore_errors)
1066                                                 return false;
1067
1068                                         if (p_mod == Parameter.Modifier.NONE)
1069                                                 ec.Report.Error (1677, Parameters[i].Location, "Parameter `{0}' should not be declared with the `{1}' keyword",
1070                                                               (i + 1).ToString (), Parameter.GetModifierSignature (Parameters [i].ModFlags));
1071                                         else
1072                                                 ec.Report.Error (1676, Parameters[i].Location, "Parameter `{0}' must be declared with the `{1}' keyword",
1073                                                               (i+1).ToString (), Parameter.GetModifierSignature (p_mod));
1074                                         error = true;
1075                                 }
1076
1077                                 if (has_implicit_parameters)
1078                                         continue;
1079
1080                                 TypeSpec type = invoke_pd.Types [i];
1081
1082                                 if (tic != null)
1083                                         type = tic.InflateGenericArgument (ec, type);
1084
1085                                 if (!TypeSpecComparer.IsEqual (type, Parameters.Types [i])) {
1086                                         if (ignore_errors)
1087                                                 return false;
1088
1089                                         ec.Report.Error (1678, Parameters [i].Location, "Parameter `{0}' is declared as type `{1}' but should be `{2}'",
1090                                                       (i+1).ToString (),
1091                                                       Parameters.Types [i].GetSignatureForError (),
1092                                                       invoke_pd.Types [i].GetSignatureForError ());
1093                                         error = true;
1094                                 }
1095                         }
1096
1097                         return !error;
1098                 }
1099
1100                 //
1101                 // Infers type arguments based on explicit arguments
1102                 //
1103                 public bool ExplicitTypeInference (TypeInferenceContext type_inference, TypeSpec delegate_type)
1104                 {
1105                         if (!HasExplicitParameters)
1106                                 return false;
1107
1108                         if (!delegate_type.IsDelegate) {
1109                                 if (!delegate_type.IsExpressionTreeType)
1110                                         return false;
1111
1112                                 delegate_type = TypeManager.GetTypeArguments (delegate_type) [0];
1113                                 if (!delegate_type.IsDelegate)
1114                                         return false;
1115                         }
1116
1117                         AParametersCollection d_params = Delegate.GetParameters (delegate_type);
1118                         if (d_params.Count != Parameters.Count)
1119                                 return false;
1120
1121                         var ptypes = Parameters.Types;
1122                         var dtypes = d_params.Types;
1123                         for (int i = 0; i < Parameters.Count; ++i) {
1124                                 if (type_inference.ExactInference (ptypes[i], dtypes[i]) == 0) {
1125                                         //
1126                                         // Continue when 0 (quick path) does not mean inference failure. Checking for
1127                                         // same type handles cases like int -> int
1128                                         //
1129                                         if (ptypes[i] == dtypes[i])
1130                                                 continue;
1131
1132                                         return false;
1133                                 }
1134                         }
1135
1136                         return true;
1137                 }
1138
1139                 public TypeSpec InferReturnType (ResolveContext ec, TypeInferenceContext tic, TypeSpec delegate_type)
1140                 {
1141                         Expression expr;
1142                         AnonymousExpression am;
1143
1144                         if (compatibles.TryGetValue (delegate_type, out expr)) {
1145                                 am = expr as AnonymousExpression;
1146                                 return am == null ? null : am.ReturnType;
1147                         }
1148
1149                         using (ec.Set (ResolveContext.Options.ProbingMode | ResolveContext.Options.InferReturnType)) {
1150                                 ReportPrinter prev;
1151                                 if (TypeInferenceReportPrinter != null) {
1152                                         prev = ec.Report.SetPrinter (TypeInferenceReportPrinter);
1153                                 } else {
1154                                         prev = null;
1155                                 }
1156
1157                                 var body = CompatibleMethodBody (ec, tic, null, delegate_type);
1158                                 if (body != null) {
1159                                         am = body.Compatible (ec, body);
1160                                 } else {
1161                                         am = null;
1162                                 }
1163
1164                                 if (TypeInferenceReportPrinter != null) {
1165                                         ec.Report.SetPrinter (prev);
1166                                 }
1167                         }
1168
1169                         if (am == null)
1170                                 return null;
1171
1172 //                      compatibles.Add (delegate_type, am);
1173                         return am.ReturnType;
1174                 }
1175
1176                 public override bool ContainsEmitWithAwait ()
1177                 {
1178                         return false;
1179                 }
1180
1181                 //
1182                 // Returns AnonymousMethod container if this anonymous method
1183                 // expression can be implicitly converted to the delegate type `delegate_type'
1184                 //
1185                 public Expression Compatible (ResolveContext ec, TypeSpec type)
1186                 {
1187                         Expression am;
1188                         if (compatibles.TryGetValue (type, out am))
1189                                 return am;
1190
1191                         if (type == InternalType.ErrorType)
1192                                 return null;
1193
1194                         TypeSpec delegate_type = CompatibleChecks (ec, type);
1195                         if (delegate_type == null)
1196                                 return null;
1197
1198                         //
1199                         // At this point its the first time we know the return type that is
1200                         // needed for the anonymous method.  We create the method here.
1201                         //
1202
1203                         var invoke_mb = Delegate.GetInvokeMethod (delegate_type);
1204                         TypeSpec return_type = invoke_mb.ReturnType;
1205
1206                         //
1207                         // Second: the return type of the delegate must be compatible with
1208                         // the anonymous type.   Instead of doing a pass to examine the block
1209                         // we satisfy the rule by setting the return type on the EmitContext
1210                         // to be the delegate type return type.
1211                         //
1212
1213                         var body = CompatibleMethodBody (ec, null, return_type, delegate_type);
1214                         if (body == null)
1215                                 return null;
1216
1217                         bool etree_conversion = delegate_type != type;
1218
1219                         try {
1220                                 if (etree_conversion) {
1221                                         if (ec.HasSet (ResolveContext.Options.ExpressionTreeConversion)) {
1222                                                 //
1223                                                 // Nested expression tree lambda use same scope as parent
1224                                                 // lambda, this also means no variable capturing between this
1225                                                 // and parent scope
1226                                                 //
1227                                                 am = body.Compatible (ec, ec.CurrentAnonymousMethod);
1228
1229                                                 //
1230                                                 // Quote nested expression tree
1231                                                 //
1232                                                 if (am != null)
1233                                                         am = new Quote (am);
1234                                         } else {
1235                                                 int errors = ec.Report.Errors;
1236
1237                                                 if (Block.IsAsync) {
1238                                                         ec.Report.Error (1989, loc, "Async lambda expressions cannot be converted to expression trees");
1239                                                 }
1240
1241                                                 using (ec.Set (ResolveContext.Options.ExpressionTreeConversion)) {
1242                                                         am = body.Compatible (ec);
1243                                                 }
1244
1245                                                 //
1246                                                 // Rewrite expressions into expression tree when targeting Expression<T>
1247                                                 //
1248                                                 if (am != null && errors == ec.Report.Errors)
1249                                                         am = CreateExpressionTree (ec, delegate_type);
1250                                         }
1251                                 } else {
1252                                         am = body.Compatible (ec);
1253
1254                                         if (body.DirectMethodGroupConversion != null) {
1255                                                 var errors_printer = new SessionReportPrinter ();
1256                                                 var old = ec.Report.SetPrinter (errors_printer);
1257                                                 var expr = new ImplicitDelegateCreation (delegate_type, body.DirectMethodGroupConversion, loc) {
1258                                                         AllowSpecialMethodsInvocation = true
1259                                                 }.Resolve (ec);
1260                                                 ec.Report.SetPrinter (old);
1261                                                 if (expr != null && errors_printer.ErrorsCount == 0)
1262                                                         am = expr;
1263                                         }
1264                                 }
1265                         } catch (CompletionResult) {
1266                                 throw;
1267                         } catch (FatalException) {
1268                                 throw;
1269                         } catch (Exception e) {
1270                                 throw new InternalErrorException (e, loc);
1271                         }
1272
1273                         if (!ec.IsInProbingMode && !etree_conversion) {
1274                                 compatibles.Add (type, am ?? EmptyExpression.Null);
1275                         }
1276
1277                         return am;
1278                 }
1279
1280                 protected virtual Expression CreateExpressionTree (ResolveContext ec, TypeSpec delegate_type)
1281                 {
1282                         return CreateExpressionTree (ec);
1283                 }
1284
1285                 public override Expression CreateExpressionTree (ResolveContext ec)
1286                 {
1287                         ec.Report.Error (1946, loc, "An anonymous method cannot be converted to an expression tree");
1288                         return null;
1289                 }
1290
1291                 protected virtual ParametersCompiled ResolveParameters (ResolveContext ec, TypeInferenceContext tic, TypeSpec delegate_type)
1292                 {
1293                         var delegate_parameters = Delegate.GetParameters (delegate_type);
1294
1295                         if (Parameters == ParametersCompiled.Undefined) {
1296                                 //
1297                                 // We provide a set of inaccessible parameters
1298                                 //
1299                                 Parameter[] fixedpars = new Parameter[delegate_parameters.Count];
1300
1301                                 for (int i = 0; i < delegate_parameters.Count; i++) {
1302                                         Parameter.Modifier i_mod = delegate_parameters.FixedParameters [i].ModFlags;
1303                                         if ((i_mod & Parameter.Modifier.OUT) != 0) {
1304                                                 if (!ec.IsInProbingMode) {
1305                                                         ec.Report.Error (1688, loc,
1306                                                                 "Cannot convert anonymous method block without a parameter list to delegate type `{0}' because it has one or more `out' parameters",
1307                                                                 delegate_type.GetSignatureForError ());
1308                                                 }
1309
1310                                                 return null;
1311                                         }
1312                                         fixedpars[i] = new Parameter (
1313                                                 new TypeExpression (delegate_parameters.Types [i], loc), null,
1314                                                 delegate_parameters.FixedParameters [i].ModFlags, null, loc);
1315                                 }
1316
1317                                 return ParametersCompiled.CreateFullyResolved (fixedpars, delegate_parameters.Types);
1318                         }
1319
1320                         if (!VerifyExplicitParameters (ec, tic, delegate_type, delegate_parameters)) {
1321                                 return null;
1322                         }
1323
1324                         return Parameters;
1325                 }
1326
1327                 protected override Expression DoResolve (ResolveContext rc)
1328                 {
1329                         if (rc.HasSet (ResolveContext.Options.ConstantScope)) {
1330                                 rc.Report.Error (1706, loc, "Anonymous methods and lambda expressions cannot be used in the current context");
1331                                 return null;
1332                         }
1333
1334                         //
1335                         // Update top-level block generated duting parsing with actual top-level block
1336                         //
1337                         if (rc.HasAny (ResolveContext.Options.FieldInitializerScope | ResolveContext.Options.BaseInitializer) && rc.CurrentMemberDefinition.Parent.PartialContainer.PrimaryConstructorParameters != null) {
1338                                 var tb = rc.ConstructorBlock.ParametersBlock.TopBlock;
1339                                 if (Block.TopBlock != tb) {
1340                                         Block b = Block;
1341                                         while (b.Parent != Block.TopBlock && b != Block.TopBlock)
1342                                                 b = b.Parent;
1343
1344                                         b.Parent = tb;
1345                                         tb.IncludeBlock (Block, Block.TopBlock);
1346                                         b.ParametersBlock.TopBlock = tb;
1347                                 }
1348                         }
1349
1350                         eclass = ExprClass.Value;
1351
1352                         //
1353                         // This hack means `The type is not accessible
1354                         // anywhere', we depend on special conversion
1355                         // rules.
1356                         //
1357                         type = InternalType.AnonymousMethod;
1358
1359                         if (!DoResolveParameters (rc))
1360                                 return null;
1361
1362                         return this;
1363                 }
1364
1365                 protected virtual bool DoResolveParameters (ResolveContext rc)
1366                 {
1367                         return Parameters.Resolve (rc);
1368                 }
1369
1370                 public override void Emit (EmitContext ec)
1371                 {
1372                         // nothing, as we only exist to not do anything.
1373                 }
1374
1375                 public static void Error_AddressOfCapturedVar (ResolveContext rc, IVariableReference var, Location loc)
1376                 {
1377                         if (rc.CurrentAnonymousMethod is AsyncInitializer)
1378                                 return;
1379
1380                         rc.Report.Error (1686, loc,
1381                                 "Local variable or parameter `{0}' cannot have their address taken and be used inside an anonymous method, lambda expression or query expression",
1382                                 var.Name);
1383                 }
1384
1385                 public override string GetSignatureForError ()
1386                 {
1387                         return ExprClassName;
1388                 }
1389
1390                 AnonymousMethodBody CompatibleMethodBody (ResolveContext ec, TypeInferenceContext tic, TypeSpec return_type, TypeSpec delegate_type)
1391                 {
1392                         ParametersCompiled p = ResolveParameters (ec, tic, delegate_type);
1393                         if (p == null)
1394                                 return null;
1395
1396                         ParametersBlock b = ec.IsInProbingMode ? (ParametersBlock) Block.PerformClone () : Block;
1397
1398                         if (b.IsAsync) {
1399                                 var rt = return_type;
1400                                 if (rt != null && rt.Kind != MemberKind.Void && rt != ec.Module.PredefinedTypes.Task.TypeSpec && !rt.IsGenericTask) {
1401                                         ec.Report.Error (4010, loc, "Cannot convert async {0} to delegate type `{1}'",
1402                                                 GetSignatureForError (), delegate_type.GetSignatureForError ());
1403
1404                                         return null;
1405                                 }
1406
1407                                 b = b.ConvertToAsyncTask (ec, ec.CurrentMemberDefinition.Parent.PartialContainer, p, return_type, delegate_type, loc);
1408                         }
1409
1410                         return CompatibleMethodFactory (return_type ?? InternalType.ErrorType, delegate_type, p, b);
1411                 }
1412
1413                 protected virtual AnonymousMethodBody CompatibleMethodFactory (TypeSpec return_type, TypeSpec delegate_type, ParametersCompiled p, ParametersBlock b)
1414                 {
1415                         return new AnonymousMethodBody (p, b, return_type, delegate_type, loc);
1416                 }
1417
1418                 protected override void CloneTo (CloneContext clonectx, Expression t)
1419                 {
1420                         AnonymousMethodExpression target = (AnonymousMethodExpression) t;
1421
1422                         target.Block = (ParametersBlock) clonectx.LookupBlock (Block);
1423                 }
1424
1425                 public override object Accept (StructuralVisitor visitor)
1426                 {
1427                         return visitor.Visit (this);
1428                 }
1429         }
1430
1431         //
1432         // Abstract expression for any block which requires variables hoisting
1433         //
1434         public abstract class AnonymousExpression : ExpressionStatement
1435         {
1436                 protected class AnonymousMethodMethod : Method
1437                 {
1438                         public readonly AnonymousExpression AnonymousMethod;
1439                         public readonly AnonymousMethodStorey Storey;
1440
1441                         public AnonymousMethodMethod (TypeDefinition parent, AnonymousExpression am, AnonymousMethodStorey storey,
1442                                                           TypeExpr return_type,
1443                                                           Modifiers mod, MemberName name,
1444                                                           ParametersCompiled parameters)
1445                                 : base (parent, return_type, mod | Modifiers.COMPILER_GENERATED,
1446                                                 name, parameters, null)
1447                         {
1448                                 this.AnonymousMethod = am;
1449                                 this.Storey = storey;
1450
1451                                 Parent.PartialContainer.Members.Add (this);
1452                                 Block = new ToplevelBlock (am.block, parameters);
1453                         }
1454
1455                         public override EmitContext CreateEmitContext (ILGenerator ig, SourceMethodBuilder sourceMethod)
1456                         {
1457                                 EmitContext ec = new EmitContext (this, ig, ReturnType, sourceMethod);
1458                                 ec.CurrentAnonymousMethod = AnonymousMethod;
1459                                 return ec;
1460                         }
1461
1462                         protected override void DefineTypeParameters ()
1463                         {
1464                                 // Type parameters were cloned
1465                         }
1466
1467                         protected override bool ResolveMemberType ()
1468                         {
1469                                 if (!base.ResolveMemberType ())
1470                                         return false;
1471
1472                                 if (Storey != null && Storey.Mutator != null) {
1473                                         if (!parameters.IsEmpty) {
1474                                                 var mutated = Storey.Mutator.Mutate (parameters.Types);
1475                                                 if (mutated != parameters.Types)
1476                                                         parameters = ParametersCompiled.CreateFullyResolved ((Parameter[]) parameters.FixedParameters, mutated);
1477                                         }
1478
1479                                         member_type = Storey.Mutator.Mutate (member_type);
1480                                 }
1481
1482                                 return true;
1483                         }
1484
1485                         public override void Emit ()
1486                         {
1487                                 if (MethodBuilder == null) {
1488                                         Define ();
1489                                 }
1490
1491                                 base.Emit ();
1492                         }
1493                 }
1494
1495                 protected readonly ParametersBlock block;
1496
1497                 public TypeSpec ReturnType;
1498
1499                 protected AnonymousExpression (ParametersBlock block, TypeSpec return_type, Location loc)
1500                 {
1501                         this.ReturnType = return_type;
1502                         this.block = block;
1503                         this.loc = loc;
1504                 }
1505
1506                 public abstract string ContainerType { get; }
1507                 public abstract bool IsIterator { get; }
1508                 public abstract AnonymousMethodStorey Storey { get; }
1509
1510                 //
1511                 // The block that makes up the body for the anonymous method
1512                 //
1513                 public ParametersBlock Block {
1514                         get {
1515                                 return block;
1516                         }
1517                 }
1518
1519                 public AnonymousExpression Compatible (ResolveContext ec)
1520                 {
1521                         return Compatible (ec, this);
1522                 }
1523
1524                 public AnonymousExpression Compatible (ResolveContext ec, AnonymousExpression ae)
1525                 {
1526                         if (block.Resolved)
1527                                 return this;
1528
1529                         // TODO: Implement clone
1530                         BlockContext aec = new BlockContext (ec, block, ReturnType);
1531                         aec.CurrentAnonymousMethod = ae;
1532
1533                         var am = this as AnonymousMethodBody;
1534
1535                         if (ec.HasSet (ResolveContext.Options.InferReturnType) && am != null) {
1536                                 am.ReturnTypeInference = new TypeInferenceContext ();
1537                         }
1538
1539                         var bc = ec as BlockContext;
1540
1541                         if (bc != null) {
1542                                 aec.AssignmentInfoOffset = bc.AssignmentInfoOffset;
1543                                 aec.EnclosingLoop = bc.EnclosingLoop;
1544                                 aec.EnclosingLoopOrSwitch = bc.EnclosingLoopOrSwitch;
1545                                 aec.Switch = bc.Switch;
1546                         }
1547
1548                         var errors = ec.Report.Errors;
1549
1550                         bool res = Block.Resolve (aec);
1551
1552                         if (res && errors == ec.Report.Errors) {
1553                                 MarkReachable (new Reachability ());
1554
1555                                 if (!CheckReachableExit (ec.Report)) {
1556                                         return null;
1557                                 }
1558
1559                                 if (bc != null)
1560                                         bc.AssignmentInfoOffset = aec.AssignmentInfoOffset;
1561                         }
1562
1563                         if (am != null && am.ReturnTypeInference != null) {
1564                                 am.ReturnTypeInference.FixAllTypes (ec);
1565                                 ReturnType = am.ReturnTypeInference.InferredTypeArguments [0];
1566                                 am.ReturnTypeInference = null;
1567
1568                                 //
1569                                 // If e is synchronous the inferred return type is T
1570                                 // If e is asynchronous and the body of F is either an expression classified as nothing
1571                                 // or a statement block where no return statements have expressions, the inferred return type is Task
1572                                 // If e is async and has an inferred result type T, the inferred return type is Task<T>
1573                                 //
1574                                 if (block.IsAsync && ReturnType != null) {
1575                                         ReturnType = ReturnType.Kind == MemberKind.Void ?
1576                                                 ec.Module.PredefinedTypes.Task.TypeSpec :
1577                                                 ec.Module.PredefinedTypes.TaskGeneric.TypeSpec.MakeGenericType (ec, new [] { ReturnType });
1578                                 }
1579                         }
1580
1581                         if (res && errors != ec.Report.Errors)
1582                                 return null;
1583
1584                         return res ? this : null;
1585                 }
1586
1587                 public override bool ContainsEmitWithAwait ()
1588                 {
1589                         return false;
1590                 }
1591
1592                 bool CheckReachableExit (Report report)
1593                 {
1594                         if (block.HasReachableClosingBrace && ReturnType.Kind != MemberKind.Void) {
1595                                 // FIXME: Flow-analysis on MoveNext generated code
1596                                 if (!IsIterator) {
1597                                         report.Error (1643, StartLocation,
1598                                                         "Not all code paths return a value in anonymous method of type `{0}'", GetSignatureForError ());
1599
1600                                         return false;
1601                                 }
1602                         }
1603
1604                         return true;
1605                 }
1606
1607                 public override void FlowAnalysis (FlowAnalysisContext fc)
1608                 {
1609                         // We are reachable, mark block body reachable too
1610                         MarkReachable (new Reachability ());
1611
1612                         CheckReachableExit (fc.Report);
1613
1614                         var das = fc.BranchDefiniteAssignment ();
1615                         var prev_pb = fc.ParametersBlock;
1616                         fc.ParametersBlock = Block;
1617                         var da_ontrue = fc.DefiniteAssignmentOnTrue;
1618                         var da_onfalse = fc.DefiniteAssignmentOnFalse;
1619                         var prev_tf = fc.TryFinally;
1620
1621                         fc.DefiniteAssignmentOnTrue = fc.DefiniteAssignmentOnFalse = null;
1622                         fc.TryFinally = null;
1623                         block.FlowAnalysis (fc);
1624
1625                         fc.ParametersBlock = prev_pb;
1626                         fc.DefiniteAssignment = das;
1627                         fc.DefiniteAssignmentOnTrue = da_ontrue;
1628                         fc.DefiniteAssignmentOnFalse = da_onfalse;
1629                         fc.TryFinally = prev_tf;
1630                 }
1631
1632                 public override void MarkReachable (Reachability rc)
1633                 {
1634                         block.MarkReachable (rc);
1635                 }
1636
1637                 public void SetHasThisAccess ()
1638                 {
1639                         ExplicitBlock b = block;
1640                         do {
1641                                 if (b.HasCapturedThis)
1642                                         return;
1643
1644                                 b.HasCapturedThis = true;
1645                                 b = b.Parent == null ? null : b.Parent.Explicit;
1646                         } while (b != null);
1647                 }
1648         }
1649
1650         public class AnonymousMethodBody : AnonymousExpression
1651         {
1652                 protected readonly ParametersCompiled parameters;
1653                 AnonymousMethodStorey storey;
1654
1655                 AnonymousMethodMethod method;
1656                 Field am_cache;
1657                 string block_name;
1658                 TypeInferenceContext return_inference;
1659
1660                 public AnonymousMethodBody (ParametersCompiled parameters,
1661                                         ParametersBlock block, TypeSpec return_type, TypeSpec delegate_type,
1662                                         Location loc)
1663                         : base (block, return_type, loc)
1664                 {
1665                         this.type = delegate_type;
1666                         this.parameters = parameters;
1667                 }
1668
1669                 #region Properties
1670
1671                 public override string ContainerType {
1672                         get { return "anonymous method"; }
1673                 }
1674
1675                 //
1676                 // Method-group instance for lambdas which can be replaced with
1677                 // simple method group call
1678                 //
1679                 public MethodGroupExpr DirectMethodGroupConversion {
1680                         get; set;
1681                 }
1682
1683                 public override bool IsIterator {
1684                         get {
1685                                 return false;
1686                         }
1687                 }
1688
1689                 public ParametersCompiled Parameters {
1690                         get {
1691                                 return parameters;
1692                         }
1693                 }
1694
1695                 public TypeInferenceContext ReturnTypeInference {
1696                         get {
1697                                 return return_inference;
1698                         }
1699                         set {
1700                                 return_inference = value;
1701                         }
1702                 }
1703
1704                 public override AnonymousMethodStorey Storey {
1705                         get {
1706                                 return storey;
1707                         }
1708                 }
1709
1710                 #endregion
1711
1712                 public override Expression CreateExpressionTree (ResolveContext ec)
1713                 {
1714                         ec.Report.Error (1945, loc, "An expression tree cannot contain an anonymous method expression");
1715                         return null;
1716                 }
1717
1718                 bool Define (ResolveContext ec)
1719                 {
1720                         if (!Block.Resolved && Compatible (ec) == null)
1721                                 return false;
1722
1723                         if (block_name == null) {
1724                                 MemberCore mc = (MemberCore) ec.MemberContext;
1725                                 block_name = mc.MemberName.Basename;
1726                         }
1727
1728                         return true;
1729                 }
1730
1731                 //
1732                 // Creates a host for the anonymous method
1733                 //
1734                 AnonymousMethodMethod DoCreateMethodHost (EmitContext ec)
1735                 {
1736                         //
1737                         // Anonymous method body can be converted to
1738                         //
1739                         // 1, an instance method in current scope when only `this' is hoisted
1740                         // 2, a static method in current scope when neither `this' nor any variable is hoisted
1741                         // 3, an instance method in compiler generated storey when any hoisted variable exists
1742                         //
1743
1744                         Modifiers modifiers;
1745                         TypeDefinition parent = null;
1746                         TypeParameters hoisted_tparams = null;
1747                         ParametersCompiled method_parameters = parameters;
1748
1749                         var src_block = Block.Original.Explicit;
1750                         if (src_block.HasCapturedVariable || src_block.HasCapturedThis) {
1751                                 parent = storey = FindBestMethodStorey ();
1752
1753                                 if (storey == null) {
1754                                         var top_block = src_block.ParametersBlock.TopBlock;
1755                                         var sm = top_block.StateMachine;
1756
1757                                         if (src_block.HasCapturedThis) {
1758                                                 //
1759                                                 // Remove hoisted 'this' request when simple instance method is
1760                                                 // enough. No hoisted variables only 'this' and don't need to
1761                                                 // propagate this to value type state machine.
1762                                                 //
1763                                                 StateMachine sm_parent;
1764                                                 var pb = src_block.ParametersBlock;
1765                                                 do {
1766                                                         sm_parent = pb.StateMachine;
1767                                                         pb = pb.Parent == null ? null : pb.Parent.ParametersBlock;
1768                                                 } while (sm_parent == null && pb != null);
1769
1770                                                 if (sm_parent == null) {
1771                                                         top_block.RemoveThisReferenceFromChildrenBlock (src_block);
1772                                                 } else if (sm_parent.Kind == MemberKind.Struct) {
1773                                                         //
1774                                                         // Special case where parent class is used to emit instance method
1775                                                         // because currect storey is of value type (async host) and we cannot
1776                                                         // use ldftn on non-boxed instances either to share mutated state
1777                                                         //
1778                                                         parent = sm_parent.Parent.PartialContainer;
1779                                                         hoisted_tparams = sm_parent.OriginalTypeParameters;
1780                                                 } else if (sm is IteratorStorey) {
1781                                                         //
1782                                                         // For iterators we can host everything in one class
1783                                                         //
1784                                                         parent = storey = sm;
1785                                                 }
1786                                         }
1787                                 }
1788
1789                                 modifiers = storey != null ? Modifiers.INTERNAL : Modifiers.PRIVATE;
1790                         } else {
1791                                 if (ec.CurrentAnonymousMethod != null)
1792                                         parent = storey = ec.CurrentAnonymousMethod.Storey;
1793
1794                                 modifiers = Modifiers.STATIC | Modifiers.PRIVATE;
1795
1796                                 //
1797                                 // Convert generated method to closed delegate method where unused
1798                                 // this argument is generated during compilation which speeds up dispatch
1799                                 // by about 25%
1800                                 //
1801                                 // Unused as it breaks compatibility
1802                                 //
1803                                 // method_parameters = ParametersCompiled.Prefix (method_parameters,
1804                                 //      new Parameter (null, null, 0, null, loc), ec.Module.Compiler.BuiltinTypes.Object);
1805                         }
1806
1807                         if (storey == null && hoisted_tparams == null)
1808                                 hoisted_tparams = ec.CurrentTypeParameters;
1809
1810                         if (parent == null)
1811                                 parent = ec.CurrentTypeDefinition.Parent.PartialContainer;
1812
1813                         string name = CompilerGeneratedContainer.MakeName (parent != storey ? block_name : null,
1814                                 "m", null, parent.PartialContainer.CounterAnonymousMethods++);
1815
1816                         MemberName member_name;
1817                         if (hoisted_tparams != null) {
1818                                 var type_params = new TypeParameters (hoisted_tparams.Count);
1819                                 for (int i = 0; i < hoisted_tparams.Count; ++i) {
1820                                     type_params.Add (hoisted_tparams[i].CreateHoistedCopy (null));
1821                                 }
1822
1823                                 member_name = new MemberName (name, type_params, Location);
1824                         } else {
1825                                 member_name = new MemberName (name, Location);
1826                         }
1827
1828                         return new AnonymousMethodMethod (parent,
1829                                 this, storey, new TypeExpression (ReturnType, Location), modifiers,
1830                                 member_name, method_parameters);
1831                 }
1832
1833                 protected override Expression DoResolve (ResolveContext ec)
1834                 {
1835                         if (!Define (ec))
1836                                 return null;
1837
1838                         eclass = ExprClass.Value;
1839                         return this;
1840                 }
1841
1842                 public override void Emit (EmitContext ec)
1843                 {
1844                         //
1845                         // Use same anonymous method implementation for scenarios where same
1846                         // code is used from multiple blocks, e.g. field initializers
1847                         //
1848                         if (method == null) {
1849                                 //
1850                                 // Delay an anonymous method definition to avoid emitting unused code
1851                                 // for unreachable blocks or expression trees
1852                                 //
1853                                 method = DoCreateMethodHost (ec);
1854                                 method.Define ();
1855                                 method.PrepareEmit ();
1856                         }
1857
1858                         bool is_static = (method.ModFlags & Modifiers.STATIC) != 0;
1859                         if (is_static && am_cache == null && !ec.IsStaticConstructor) {
1860                                 //
1861                                 // Creates a field cache to store delegate instance if it's not generic
1862                                 //
1863                                 if (!method.MemberName.IsGeneric) {
1864                                         var parent = method.Parent.PartialContainer;
1865                                         int id = parent.AnonymousMethodsCounter++;
1866                                         var cache_type = storey != null && storey.Mutator != null ? storey.Mutator.Mutate (type) : type;
1867
1868                                         am_cache = new Field (parent, new TypeExpression (cache_type, loc),
1869                                                 Modifiers.STATIC | Modifiers.PRIVATE | Modifiers.COMPILER_GENERATED,
1870                                                 new MemberName (CompilerGeneratedContainer.MakeName (null, "f", "am$cache", id), loc), null);
1871                                         am_cache.Define ();
1872                                         parent.AddField (am_cache);
1873                                 } else {
1874                                         // TODO: Implement caching of generated generic static methods
1875                                         //
1876                                         // Idea:
1877                                         //
1878                                         // Some extra class is needed to capture variable generic type
1879                                         // arguments. Maybe we could re-use anonymous types, with a unique
1880                                         // anonymous method id, but they are quite heavy.
1881                                         //
1882                                         // Consider : "() => typeof(T);"
1883                                         //
1884                                         // We need something like
1885                                         // static class Wrap<Tn, Tm, DelegateType> {
1886                                         //              public static DelegateType cache;
1887                                         // }
1888                                         //
1889                                         // We then specialize local variable to capture all generic parameters
1890                                         // and delegate type, e.g. "Wrap<Ta, Tb, DelegateTypeInst> cache;"
1891                                         //
1892                                 }
1893                         }
1894
1895                         Label l_initialized = ec.DefineLabel ();
1896
1897                         if (am_cache != null) {
1898                                 ec.Emit (OpCodes.Ldsfld, am_cache.Spec);
1899                                 ec.Emit (OpCodes.Brtrue_S, l_initialized);
1900                         }
1901
1902                         //
1903                         // Load method delegate implementation
1904                         //
1905
1906                         if (is_static) {
1907                                 ec.EmitNull ();
1908                         } else if (storey != null) {
1909                                 Expression e = storey.GetStoreyInstanceExpression (ec).Resolve (new ResolveContext (ec.MemberContext));
1910                                 if (e != null) {
1911                                         e.Emit (ec);
1912                                 }
1913                         } else {
1914                                 ec.EmitThis ();
1915
1916                                 //
1917                                 // Special case for value type storey where this is not lifted but
1918                                 // droped off to parent class
1919                                 //
1920                                 if (ec.CurrentAnonymousMethod != null && ec.AsyncTaskStorey != null)
1921                                         ec.Emit (OpCodes.Ldfld, ec.AsyncTaskStorey.HoistedThis.Field.Spec);
1922                         }
1923
1924                         var delegate_method = method.Spec;
1925                         if (storey != null && storey.MemberName.IsGeneric) {
1926                                 //
1927                                 // Mutate anonymous method instance type if we are in nested
1928                                 // hoisted generic anonymous method storey
1929                                 //
1930                                 if (ec.IsAnonymousStoreyMutateRequired) {
1931                                         ec.Emit (OpCodes.Ldftn, delegate_method);
1932                                 } else {
1933                                         TypeSpec t = storey.Instance.Type;
1934                                         ec.Emit (OpCodes.Ldftn, TypeBuilder.GetMethod (t.GetMetaInfo (), (MethodInfo) delegate_method.GetMetaInfo ()));
1935                                 }
1936                         } else {
1937                                 if (delegate_method.IsGeneric) {
1938                                         TypeParameterSpec[] tparams;
1939                                         var sm = ec.CurrentAnonymousMethod == null ? null : ec.CurrentAnonymousMethod.Storey as StateMachine;
1940                                         if (sm != null && sm.OriginalTypeParameters != null) {
1941                                                 tparams = sm.CurrentTypeParameters.Types;
1942                                         } else {
1943                                                 tparams = method.TypeParameters;
1944                                         }
1945
1946                                         delegate_method = delegate_method.MakeGenericMethod (ec.MemberContext, tparams);
1947                                 }
1948
1949                                 ec.Emit (OpCodes.Ldftn, delegate_method);
1950                         }
1951
1952                         var constructor_method = Delegate.GetConstructor (type);
1953                         ec.Emit (OpCodes.Newobj, constructor_method);
1954
1955                         if (am_cache != null) {
1956                                 ec.Emit (OpCodes.Stsfld, am_cache.Spec);
1957                                 ec.MarkLabel (l_initialized);
1958                                 ec.Emit (OpCodes.Ldsfld, am_cache.Spec);
1959                         }
1960                 }
1961
1962                 public override void EmitStatement (EmitContext ec)
1963                 {
1964                         throw new NotImplementedException ();
1965                 }
1966
1967                 //
1968                 // Look for the best storey for this anonymous method
1969                 //
1970                 AnonymousMethodStorey FindBestMethodStorey ()
1971                 {
1972                         //
1973                         // Use the nearest parent block which has a storey
1974                         //
1975                         for (Block b = Block.Parent; b != null; b = b.Parent) {
1976                                 AnonymousMethodStorey s = b.Explicit.AnonymousMethodStorey;
1977                                 if (s != null)
1978                                         return s;
1979                         }
1980
1981                         return null;
1982                 }
1983
1984                 public override string GetSignatureForError ()
1985                 {
1986                         return type.GetSignatureForError ();
1987                 }
1988         }
1989
1990         //
1991         // Anonymous type container
1992         //
1993         public class AnonymousTypeClass : CompilerGeneratedContainer
1994         {
1995                 public const string ClassNamePrefix = "<>__AnonType";
1996                 public const string SignatureForError = "anonymous type";
1997
1998                 readonly IList<AnonymousTypeParameter> parameters;
1999
2000                 private AnonymousTypeClass (ModuleContainer parent, MemberName name, IList<AnonymousTypeParameter> parameters, Location loc)
2001                         : base (parent, name, parent.Evaluator != null ? Modifiers.PUBLIC : Modifiers.INTERNAL)
2002                 {
2003                         this.parameters = parameters;
2004                 }
2005
2006                 public static AnonymousTypeClass Create (TypeContainer parent, IList<AnonymousTypeParameter> parameters, Location loc)
2007                 {
2008                         string name = ClassNamePrefix + parent.Module.CounterAnonymousTypes++;
2009
2010                         ParametersCompiled all_parameters;
2011                         TypeParameters tparams = null;
2012                         SimpleName[] t_args;
2013
2014                         if (parameters.Count == 0) {
2015                                 all_parameters = ParametersCompiled.EmptyReadOnlyParameters;
2016                                 t_args = null;
2017                         } else {
2018                                 t_args = new SimpleName[parameters.Count];
2019                                 tparams = new TypeParameters ();
2020                                 Parameter[] ctor_params = new Parameter[parameters.Count];
2021                                 for (int i = 0; i < parameters.Count; ++i) {
2022                                         AnonymousTypeParameter p = parameters[i];
2023                                         for (int ii = 0; ii < i; ++ii) {
2024                                                 if (parameters[ii].Name == p.Name) {
2025                                                         parent.Compiler.Report.Error (833, parameters[ii].Location,
2026                                                                 "`{0}': An anonymous type cannot have multiple properties with the same name",
2027                                                                         p.Name);
2028
2029                                                         p = new AnonymousTypeParameter (null, "$" + i.ToString (), p.Location);
2030                                                         parameters[i] = p;
2031                                                         break;
2032                                                 }
2033                                         }
2034
2035                                         t_args[i] = new SimpleName ("<" + p.Name + ">__T", p.Location);
2036                                         tparams.Add (new TypeParameter (i, new MemberName (t_args[i].Name, p.Location), null, null, Variance.None));
2037                                         ctor_params[i] = new Parameter (t_args[i], p.Name, Parameter.Modifier.NONE, null, p.Location);
2038                                 }
2039
2040                                 all_parameters = new ParametersCompiled (ctor_params);
2041                         }
2042
2043                         //
2044                         // Create generic anonymous type host with generic arguments
2045                         // named upon properties names
2046                         //
2047                         AnonymousTypeClass a_type = new AnonymousTypeClass (parent.Module, new MemberName (name, tparams, loc), parameters, loc);
2048
2049                         Constructor c = new Constructor (a_type, name, Modifiers.PUBLIC | Modifiers.DEBUGGER_HIDDEN,
2050                                 null, all_parameters, loc);
2051                         c.Block = new ToplevelBlock (parent.Module.Compiler, c.ParameterInfo, loc);
2052
2053                         //
2054                         // Create fields and constructor body with field initialization
2055                         //
2056                         bool error = false;
2057                         for (int i = 0; i < parameters.Count; ++i) {
2058                                 AnonymousTypeParameter p = parameters [i];
2059
2060                                 Field f = new Field (a_type, t_args [i], Modifiers.PRIVATE | Modifiers.READONLY | Modifiers.DEBUGGER_HIDDEN,
2061                                         new MemberName ("<" + p.Name + ">", p.Location), null);
2062
2063                                 if (!a_type.AddField (f)) {
2064                                         error = true;
2065                                         continue;
2066                                 }
2067
2068                                 c.Block.AddStatement (new StatementExpression (
2069                                         new SimpleAssign (new MemberAccess (new This (p.Location), f.Name),
2070                                                 c.Block.GetParameterReference (i, p.Location))));
2071
2072                                 ToplevelBlock get_block = new ToplevelBlock (parent.Module.Compiler, p.Location);
2073                                 get_block.AddStatement (new Return (
2074                                         new MemberAccess (new This (p.Location), f.Name), p.Location));
2075
2076                                 Property prop = new Property (a_type, t_args [i], Modifiers.PUBLIC,
2077                                         new MemberName (p.Name, p.Location), null);
2078                                 prop.Get = new Property.GetMethod (prop, 0, null, p.Location);
2079                                 prop.Get.Block = get_block;
2080                                 a_type.AddMember (prop);
2081                         }
2082
2083                         if (error)
2084                                 return null;
2085
2086                         a_type.AddConstructor (c);
2087                         return a_type;
2088                 }
2089
2090                 protected override bool DoDefineMembers ()
2091                 {
2092                         if (!base.DoDefineMembers ())
2093                                 return false;
2094
2095                         Location loc = Location;
2096
2097                         var equals_parameters = ParametersCompiled.CreateFullyResolved (
2098                                 new Parameter (new TypeExpression (Compiler.BuiltinTypes.Object, loc), "obj", 0, null, loc), Compiler.BuiltinTypes.Object);
2099
2100                         Method equals = new Method (this, new TypeExpression (Compiler.BuiltinTypes.Bool, loc),
2101                                 Modifiers.PUBLIC | Modifiers.OVERRIDE | Modifiers.DEBUGGER_HIDDEN, new MemberName ("Equals", loc),
2102                                 equals_parameters, null);
2103
2104                         equals_parameters[0].Resolve (equals, 0);
2105
2106                         Method tostring = new Method (this, new TypeExpression (Compiler.BuiltinTypes.String, loc),
2107                                 Modifiers.PUBLIC | Modifiers.OVERRIDE | Modifiers.DEBUGGER_HIDDEN, new MemberName ("ToString", loc),
2108                                 ParametersCompiled.EmptyReadOnlyParameters, null);
2109
2110                         ToplevelBlock equals_block = new ToplevelBlock (Compiler, equals.ParameterInfo, loc);
2111
2112                         TypeExpr current_type;
2113                         if (CurrentTypeParameters != null) {
2114                                 var targs = new TypeArguments ();
2115                                 for (int i = 0; i < CurrentTypeParameters.Count; ++i) {
2116                                         targs.Add (new TypeParameterExpr (CurrentTypeParameters[i], Location));
2117                                 }
2118
2119                                 current_type = new GenericTypeExpr (Definition, targs, loc);
2120                         } else {
2121                                 current_type = new TypeExpression (Definition, loc);
2122                         }
2123
2124                         var li_other = LocalVariable.CreateCompilerGenerated (CurrentType, equals_block, loc);
2125                         equals_block.AddStatement (new BlockVariable (new TypeExpression (li_other.Type, loc), li_other));
2126                         var other_variable = new LocalVariableReference (li_other, loc);
2127
2128                         MemberAccess system_collections_generic = new MemberAccess (new MemberAccess (
2129                                 new QualifiedAliasMember ("global", "System", loc), "Collections", loc), "Generic", loc);
2130
2131                         Expression rs_equals = null;
2132                         Expression string_concat = new StringConstant (Compiler.BuiltinTypes, "{", loc);
2133                         Expression rs_hashcode = new IntConstant (Compiler.BuiltinTypes, -2128831035, loc);
2134                         for (int i = 0; i < parameters.Count; ++i) {
2135                                 var p = parameters [i];
2136                                 var f = (Field) Members [i * 2];
2137
2138                                 MemberAccess equality_comparer = new MemberAccess (new MemberAccess (
2139                                         system_collections_generic, "EqualityComparer",
2140                                                 new TypeArguments (new SimpleName (CurrentTypeParameters [i].Name, loc)), loc),
2141                                                 "Default", loc);
2142
2143                                 Arguments arguments_equal = new Arguments (2);
2144                                 arguments_equal.Add (new Argument (new MemberAccess (new This (f.Location), f.Name)));
2145                                 arguments_equal.Add (new Argument (new MemberAccess (other_variable, f.Name)));
2146
2147                                 Expression field_equal = new Invocation (new MemberAccess (equality_comparer,
2148                                         "Equals", loc), arguments_equal);
2149
2150                                 Arguments arguments_hashcode = new Arguments (1);
2151                                 arguments_hashcode.Add (new Argument (new MemberAccess (new This (f.Location), f.Name)));
2152                                 Expression field_hashcode = new Invocation (new MemberAccess (equality_comparer,
2153                                         "GetHashCode", loc), arguments_hashcode);
2154
2155                                 IntConstant FNV_prime = new IntConstant (Compiler.BuiltinTypes, 16777619, loc);
2156                                 rs_hashcode = new Binary (Binary.Operator.Multiply,
2157                                         new Binary (Binary.Operator.ExclusiveOr, rs_hashcode, field_hashcode),
2158                                         FNV_prime);
2159
2160                                 Expression field_to_string = new Conditional (new BooleanExpression (new Binary (Binary.Operator.Inequality,
2161                                         new MemberAccess (new This (f.Location), f.Name), new NullLiteral (loc))),
2162                                         new Invocation (new MemberAccess (
2163                                                 new MemberAccess (new This (f.Location), f.Name), "ToString"), null),
2164                                         new StringConstant (Compiler.BuiltinTypes, string.Empty, loc), loc);
2165
2166                                 if (rs_equals == null) {
2167                                         rs_equals = field_equal;
2168                                         string_concat = new Binary (Binary.Operator.Addition,
2169                                                 string_concat,
2170                                                 new Binary (Binary.Operator.Addition,
2171                                                         new StringConstant (Compiler.BuiltinTypes, " " + p.Name + " = ", loc),
2172                                                         field_to_string));
2173                                         continue;
2174                                 }
2175
2176                                 //
2177                                 // Implementation of ToString () body using string concatenation
2178                                 //
2179                                 string_concat = new Binary (Binary.Operator.Addition,
2180                                         new Binary (Binary.Operator.Addition,
2181                                                 string_concat,
2182                                                 new StringConstant (Compiler.BuiltinTypes, ", " + p.Name + " = ", loc)),
2183                                         field_to_string);
2184
2185                                 rs_equals = new Binary (Binary.Operator.LogicalAnd, rs_equals, field_equal);
2186                         }
2187
2188                         string_concat = new Binary (Binary.Operator.Addition,
2189                                 string_concat,
2190                                 new StringConstant (Compiler.BuiltinTypes, " }", loc));
2191
2192                         //
2193                         // Equals (object obj) override
2194                         //
2195                         var other_variable_assign = new TemporaryVariableReference (li_other, loc);
2196                         equals_block.AddStatement (new StatementExpression (
2197                                 new SimpleAssign (other_variable_assign,
2198                                         new As (equals_block.GetParameterReference (0, loc),
2199                                                 current_type, loc), loc)));
2200
2201                         Expression equals_test = new Binary (Binary.Operator.Inequality, other_variable, new NullLiteral (loc));
2202                         if (rs_equals != null)
2203                                 equals_test = new Binary (Binary.Operator.LogicalAnd, equals_test, rs_equals);
2204                         equals_block.AddStatement (new Return (equals_test, loc));
2205
2206                         equals.Block = equals_block;
2207                         equals.Define ();
2208                         Members.Add (equals);
2209
2210                         //
2211                         // GetHashCode () override
2212                         //
2213                         Method hashcode = new Method (this, new TypeExpression (Compiler.BuiltinTypes.Int, loc),
2214                                 Modifiers.PUBLIC | Modifiers.OVERRIDE | Modifiers.DEBUGGER_HIDDEN,
2215                                 new MemberName ("GetHashCode", loc),
2216                                 ParametersCompiled.EmptyReadOnlyParameters, null);
2217
2218                         //
2219                         // Modified FNV with good avalanche behavior and uniform
2220                         // distribution with larger hash sizes.
2221                         //
2222                         // const int FNV_prime = 16777619;
2223                         // int hash = (int) 2166136261;
2224                         // foreach (int d in data)
2225                         //     hash = (hash ^ d) * FNV_prime;
2226                         // hash += hash << 13;
2227                         // hash ^= hash >> 7;
2228                         // hash += hash << 3;
2229                         // hash ^= hash >> 17;
2230                         // hash += hash << 5;
2231
2232                         ToplevelBlock hashcode_top = new ToplevelBlock (Compiler, loc);
2233                         Block hashcode_block = new Block (hashcode_top, loc, loc);
2234                         hashcode_top.AddStatement (new Unchecked (hashcode_block, loc));
2235
2236                         var li_hash = LocalVariable.CreateCompilerGenerated (Compiler.BuiltinTypes.Int, hashcode_top, loc);
2237                         hashcode_block.AddStatement (new BlockVariable (new TypeExpression (li_hash.Type, loc), li_hash));
2238                         LocalVariableReference hash_variable_assign = new LocalVariableReference (li_hash, loc);
2239                         hashcode_block.AddStatement (new StatementExpression (
2240                                 new SimpleAssign (hash_variable_assign, rs_hashcode)));
2241
2242                         var hash_variable = new LocalVariableReference (li_hash, loc);
2243                         hashcode_block.AddStatement (new StatementExpression (
2244                                 new CompoundAssign (Binary.Operator.Addition, hash_variable,
2245                                         new Binary (Binary.Operator.LeftShift, hash_variable, new IntConstant (Compiler.BuiltinTypes, 13, loc)))));
2246                         hashcode_block.AddStatement (new StatementExpression (
2247                                 new CompoundAssign (Binary.Operator.ExclusiveOr, hash_variable,
2248                                         new Binary (Binary.Operator.RightShift, hash_variable, new IntConstant (Compiler.BuiltinTypes, 7, loc)))));
2249                         hashcode_block.AddStatement (new StatementExpression (
2250                                 new CompoundAssign (Binary.Operator.Addition, hash_variable,
2251                                         new Binary (Binary.Operator.LeftShift, hash_variable, new IntConstant (Compiler.BuiltinTypes, 3, loc)))));
2252                         hashcode_block.AddStatement (new StatementExpression (
2253                                 new CompoundAssign (Binary.Operator.ExclusiveOr, hash_variable,
2254                                         new Binary (Binary.Operator.RightShift, hash_variable, new IntConstant (Compiler.BuiltinTypes, 17, loc)))));
2255                         hashcode_block.AddStatement (new StatementExpression (
2256                                 new CompoundAssign (Binary.Operator.Addition, hash_variable,
2257                                         new Binary (Binary.Operator.LeftShift, hash_variable, new IntConstant (Compiler.BuiltinTypes, 5, loc)))));
2258
2259                         hashcode_block.AddStatement (new Return (hash_variable, loc));
2260                         hashcode.Block = hashcode_top;
2261                         hashcode.Define ();
2262                         Members.Add (hashcode);
2263
2264                         //
2265                         // ToString () override
2266                         //
2267
2268                         ToplevelBlock tostring_block = new ToplevelBlock (Compiler, loc);
2269                         tostring_block.AddStatement (new Return (string_concat, loc));
2270                         tostring.Block = tostring_block;
2271                         tostring.Define ();
2272                         Members.Add (tostring);
2273
2274                         return true;
2275                 }
2276
2277                 public override string GetSignatureForError ()
2278                 {
2279                         return SignatureForError;
2280                 }
2281
2282                 public override CompilationSourceFile GetCompilationSourceFile ()
2283                 {
2284                         return null;
2285                 }
2286
2287                 public IList<AnonymousTypeParameter> Parameters {
2288                         get {
2289                                 return parameters;
2290                         }
2291                 }
2292         }
2293 }