mcs/mcs/delegate.cs

   1 //
   2 // delegate.cs: Delegate Handler
   3 //
   4 // Authors:
   5 //     Ravi Pratap (ravi@ximian.com)
   6 //     Miguel de Icaza (miguel@ximian.com)
   7 //     Marek Safar (marek.safar@gmail.com)
   8 //
   9 // Dual licensed under the terms of the MIT X11 or GNU GPL
  10 //
  11 // Copyright 2001 Ximian, Inc (http://www.ximian.com)
  12 // Copyright 2003-2009 Novell, Inc (http://www.novell.com)
  13 //
  14
  15 using System;
  16 using System.Reflection;
  17 using System.Reflection.Emit;
  18
  19 namespace Mono.CSharp {
  20
  21         //
  22         // Delegate container implementation
  23         //
  24         public class Delegate : TypeContainer, IParametersMember
  25         {
  26                 FullNamedExpression ReturnType;
  27                 readonly ParametersCompiled parameters;
  28
  29                 Constructor Constructor;
  30                 Method InvokeBuilder;
  31                 Method BeginInvokeBuilder;
  32                 Method EndInvokeBuilder;
  33
  34                 static readonly string[] attribute_targets = new string [] { "type", "return" };
  35
  36                 public static readonly string InvokeMethodName = "Invoke";
  37
  38                 Expression instance_expr;
  39                 ReturnParameter return_attributes;
  40
  41                 const Modifiers MethodModifiers = Modifiers.PUBLIC | Modifiers.VIRTUAL;
  42
  43                 const Modifiers AllowedModifiers =
  44                         Modifiers.NEW |
  45                         Modifiers.PUBLIC |
  46                         Modifiers.PROTECTED |
  47                         Modifiers.INTERNAL |
  48                         Modifiers.UNSAFE |
  49                         Modifiers.PRIVATE;
  50
  51                 public Delegate (NamespaceEntry ns, DeclSpace parent, FullNamedExpression type,
  52                                  Modifiers mod_flags, MemberName name, ParametersCompiled param_list,
  53                                  Attributes attrs)
  54                         : base (ns, parent, name, attrs, MemberKind.Delegate)
  55
  56                 {
  57                         this.ReturnType = type;
  58                         ModFlags        = ModifiersExtensions.Check (AllowedModifiers, mod_flags,
  59                                                            IsTopLevel ? Modifiers.INTERNAL :
  60                                                            Modifiers.PRIVATE, name.Location, Report);
  61                         parameters      = param_list;
  62                         spec = new TypeSpec (Kind, null, this, null, ModFlags | Modifiers.SEALED);
  63                 }
  64
  65                 #region Properties
  66                 public TypeSpec MemberType {
  67                         get {
  68                                 return ReturnType.Type;
  69                         }
  70                 }
  71
  72                 public AParametersCollection Parameters {
  73                         get {
  74                                 return parameters;
  75                         }
  76                 }
  77                 #endregion
  78
  79                 public override void ApplyAttributeBuilder (Attribute a, MethodSpec ctor, byte[] cdata, PredefinedAttributes pa)
  80                 {
  81                         if (a.Target == AttributeTargets.ReturnValue) {
  82                                 if (return_attributes == null)
  83                                         return_attributes = new ReturnParameter (this, InvokeBuilder.MethodBuilder, Location);
  84
  85                                 return_attributes.ApplyAttributeBuilder (a, ctor, cdata, pa);
  86                                 return;
  87                         }
  88
  89                         base.ApplyAttributeBuilder (a, ctor, cdata, pa);
  90                 }
  91
  92                 public override AttributeTargets AttributeTargets {
  93                         get {
  94                                 return AttributeTargets.Delegate;
  95                         }
  96                 }
  97
  98                 protected override bool DoDefineMembers ()
  99                 {
 100                         var ctor_parameters = ParametersCompiled.CreateFullyResolved (
 101                                 new [] {
 102                                         new Parameter (new TypeExpression (TypeManager.object_type, Location), "object", Parameter.Modifier.NONE, null, Location),
 103                                         new Parameter (new TypeExpression (TypeManager.intptr_type, Location), "method", Parameter.Modifier.NONE, null, Location)
 104                                 },
 105                                 new [] {
 106                                         TypeManager.object_type,
 107                                         TypeManager.intptr_type
 108                                 }
 109                         );
 110
 111                         Constructor = new Constructor (this, Constructor.ConstructorName,
 112                                 Modifiers.PUBLIC, null, ctor_parameters, null, Location);
 113                         Constructor.Define ();
 114
 115                         //
 116                         // Here the various methods like Invoke, BeginInvoke etc are defined
 117                         //
 118                         // First, call the `out of band' special method for
 119                         // defining recursively any types we need:
 120                         //
 121                         var p = parameters;
 122
 123                         if (!p.Resolve (this))
 124                                 return false;
 125
 126                         //
 127                         // Invoke method
 128                         //
 129
 130                         // Check accessibility
 131                         foreach (var partype in p.Types) {
 132                                 if (!IsAccessibleAs (partype)) {
 133                                         Report.SymbolRelatedToPreviousError (partype);
 134                                         Report.Error (59, Location,
 135                                                 "Inconsistent accessibility: parameter type `{0}' is less accessible than delegate `{1}'",
 136                                                 TypeManager.CSharpName (partype), GetSignatureForError ());
 137                                 }
 138                         }
 139
 140                         ReturnType = ReturnType.ResolveAsTypeTerminal (this, false);
 141                         if (ReturnType == null)
 142                                 return false;
 143
 144                         var ret_type = ReturnType.Type;
 145
 146                         //
 147                         // We don't have to check any others because they are all
 148                         // guaranteed to be accessible - they are standard types.
 149                         //
 150                         if (!IsAccessibleAs (ret_type)) {
 151                                 Report.SymbolRelatedToPreviousError (ret_type);
 152                                 Report.Error (58, Location,
 153                                                   "Inconsistent accessibility: return type `" +
 154                                                   TypeManager.CSharpName (ret_type) + "' is less " +
 155                                                   "accessible than delegate `" + GetSignatureForError () + "'");
 156                                 return false;
 157                         }
 158
 159                         CheckProtectedModifier ();
 160
 161                         if (RootContext.StdLib && TypeManager.IsSpecialType (ret_type)) {
 162                                 Method.Error1599 (Location, ret_type, Report);
 163                                 return false;
 164                         }
 165
 166                         TypeManager.CheckTypeVariance (ret_type, Variance.Covariant, this);
 167
 168                         InvokeBuilder = new Method (this, null, ReturnType, MethodModifiers, new MemberName (InvokeMethodName), p, null);
 169                         InvokeBuilder.Define ();
 170
 171                         //
 172                         // Don't emit async method for compiler generated delegates (e.g. dynamic site containers)
 173                         //
 174                         if (!IsCompilerGenerated) {
 175                                 DefineAsyncMethods (Parameters.CallingConvention);
 176                         }
 177
 178                         return true;
 179                 }
 180
 181                 void DefineAsyncMethods (CallingConventions cc)
 182                 {
 183                         var iasync_result = Module.PredefinedTypes.IAsyncResult;
 184                         var async_callback = Module.PredefinedTypes.AsyncCallback;
 185
 186                         //
 187                         // It's ok when async types don't exist, the delegate will have Invoke method only
 188                         //
 189                         if (!iasync_result.Define () || !async_callback.Define ())
 190                                 return;
 191
 192                         //
 193                         // BeginInvoke
 194                         //
 195                         ParametersCompiled async_parameters;
 196                         if (Parameters.Count == 0) {
 197                                 async_parameters = ParametersCompiled.EmptyReadOnlyParameters;
 198                         } else {
 199                                 var compiled = new Parameter[Parameters.Count];
 200                                 for (int i = 0; i < compiled.Length; ++i) {
 201                                         var p = parameters[i];
 202                                         compiled[i] = new Parameter (new TypeExpression (parameters.Types[i], Location),
 203                                                 p.Name,
 204                                                 p.ModFlags & (Parameter.Modifier.REF | Parameter.Modifier.OUT),
 205                                                 p.OptAttributes == null ? null : p.OptAttributes.Clone (), Location);
 206                                 }
 207
 208                                 async_parameters = new ParametersCompiled (compiled);
 209                         }
 210
 211                         async_parameters = ParametersCompiled.MergeGenerated (Compiler, async_parameters, false,
 212                                 new Parameter[] {
 213                                         new Parameter (new TypeExpression (async_callback.TypeSpec, Location), "callback", Parameter.Modifier.NONE, null, Location),
 214                                         new Parameter (new TypeExpression (TypeManager.object_type, Location), "object", Parameter.Modifier.NONE, null, Location)
 215                                 },
 216                                 new [] {
 217                                         async_callback.TypeSpec,
 218                                         TypeManager.object_type
 219                                 }
 220                         );
 221
 222                         BeginInvokeBuilder = new Method (this, null,
 223                                 new TypeExpression (iasync_result.TypeSpec, Location), MethodModifiers,
 224                                 new MemberName ("BeginInvoke"), async_parameters, null);
 225                         BeginInvokeBuilder.Define ();
 226
 227                         //
 228                         // EndInvoke is a bit more interesting, all the parameters labeled as
 229                         // out or ref have to be duplicated here.
 230                         //
 231
 232                         //
 233                         // Define parameters, and count out/ref parameters
 234                         //
 235                         ParametersCompiled end_parameters;
 236                         int out_params = 0;
 237
 238                         foreach (Parameter p in Parameters.FixedParameters) {
 239                                 if ((p.ModFlags & Parameter.Modifier.ISBYREF) != 0)
 240                                         ++out_params;
 241                         }
 242
 243                         if (out_params > 0) {
 244                                 Parameter[] end_params = new Parameter[out_params];
 245
 246                                 int param = 0;
 247                                 for (int i = 0; i < Parameters.FixedParameters.Length; ++i) {
 248                                         Parameter p = parameters [i];
 249                                         if ((p.ModFlags & Parameter.Modifier.ISBYREF) == 0)
 250                                                 continue;
 251
 252                                         end_params [param++] = new Parameter (new TypeExpression (p.Type, Location),
 253                                                 p.Name,
 254                                                 p.ModFlags & (Parameter.Modifier.REF | Parameter.Modifier.OUT),
 255                                                 p.OptAttributes == null ? null : p.OptAttributes.Clone (), Location);
 256                                 }
 257
 258                                 end_parameters = new ParametersCompiled (end_params);
 259                         } else {
 260                                 end_parameters = ParametersCompiled.EmptyReadOnlyParameters;
 261                         }
 262
 263                         end_parameters = ParametersCompiled.MergeGenerated (Compiler, end_parameters, false,
 264                                 new Parameter (
 265                                         new TypeExpression (iasync_result.TypeSpec, Location),
 266                                         "result", Parameter.Modifier.NONE, null, Location),
 267                                 iasync_result.TypeSpec);
 268
 269                         //
 270                         // Create method, define parameters, register parameters with type system
 271                         //
 272                         EndInvokeBuilder = new Method (this, null, ReturnType, MethodModifiers, new MemberName ("EndInvoke"), end_parameters, null);
 273                         EndInvokeBuilder.Define ();
 274                 }
 275
 276                 public override void DefineConstants ()
 277                 {
 278                         if (!Parameters.IsEmpty) {
 279                                 parameters.ResolveDefaultValues (this);
 280                         }
 281                 }
 282
 283                 public override void EmitType ()
 284                 {
 285                         if (ReturnType.Type != null) {
 286                                 if (ReturnType.Type == InternalType.Dynamic) {
 287                                         return_attributes = new ReturnParameter (this, InvokeBuilder.MethodBuilder, Location);
 288                                         Module.PredefinedAttributes.Dynamic.EmitAttribute (return_attributes.Builder);
 289                                 } else if (ReturnType.Type.HasDynamicElement) {
 290                                         return_attributes = new ReturnParameter (this, InvokeBuilder.MethodBuilder, Location);
 291                                         Module.PredefinedAttributes.Dynamic.EmitAttribute (return_attributes.Builder, ReturnType.Type, Location);
 292                                 }
 293                         }
 294
 295                         parameters.ApplyAttributes (this, InvokeBuilder.MethodBuilder);
 296
 297                         Constructor.ConstructorBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 298                         InvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 299
 300                         if (BeginInvokeBuilder != null) {
 301                                 BeginInvokeBuilder.ParameterInfo.ApplyAttributes (this, BeginInvokeBuilder.MethodBuilder);
 302                                 EndInvokeBuilder.ParameterInfo.ApplyAttributes (this, EndInvokeBuilder.MethodBuilder);
 303
 304                                 BeginInvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 305                                 EndInvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 306                         }
 307
 308                         if (OptAttributes != null) {
 309                                 OptAttributes.Emit ();
 310                         }
 311
 312                         base.Emit ();
 313                 }
 314
 315                 protected override TypeExpr[] ResolveBaseTypes (out TypeExpr base_class)
 316                 {
 317                         base_type = TypeManager.multicast_delegate_type;
 318                         base_class = null;
 319                         return null;
 320                 }
 321
 322                 protected override TypeAttributes TypeAttr {
 323                         get {
 324                                 return ModifiersExtensions.TypeAttr (ModFlags, IsTopLevel) |
 325                                         TypeAttributes.Class | TypeAttributes.Sealed |
 326                                         base.TypeAttr;
 327                         }
 328                 }
 329
 330                 public override string[] ValidAttributeTargets {
 331                         get {
 332                                 return attribute_targets;
 333                         }
 334                 }
 335
 336                 //TODO: duplicate
 337                 protected override bool VerifyClsCompliance ()
 338                 {
 339                         if (!base.VerifyClsCompliance ()) {
 340                                 return false;
 341                         }
 342
 343                         parameters.VerifyClsCompliance (this);
 344
 345                         if (!ReturnType.Type.IsCLSCompliant ()) {
 346                                 Report.Warning (3002, 1, Location, "Return type of `{0}' is not CLS-compliant",
 347                                         GetSignatureForError ());
 348                         }
 349                         return true;
 350                 }
 351
 352
 353                 public static MethodSpec GetConstructor (CompilerContext ctx, TypeSpec container_type, TypeSpec delType)
 354                 {
 355                         var ctor = MemberCache.FindMember (delType, MemberFilter.Constructor (null), BindingRestriction.DeclaredOnly);
 356                         return (MethodSpec) ctor;
 357                 }
 358
 359                 //
 360                 // Returns the "Invoke" from a delegate type
 361                 //
 362                 public static MethodSpec GetInvokeMethod (CompilerContext ctx, TypeSpec delType)
 363                 {
 364                         var invoke = MemberCache.FindMember (delType,
 365                                 MemberFilter.Method (InvokeMethodName, 0, null, null),
 366                                 BindingRestriction.DeclaredOnly);
 367
 368                         return (MethodSpec) invoke;
 369                 }
 370
 371                 public static AParametersCollection GetParameters (CompilerContext ctx, TypeSpec delType)
 372                 {
 373                         var invoke_mb = GetInvokeMethod (ctx, delType);
 374                         return invoke_mb.Parameters;
 375                 }
 376
 377                 //
 378                 // 15.2 Delegate compatibility
 379                 //
 380                 public static bool IsTypeCovariant (Expression a, TypeSpec b)
 381                 {
 382                         //
 383                         // For each value parameter (a parameter with no ref or out modifier), an
 384                         // identity conversion or implicit reference conversion exists from the
 385                         // parameter type in D to the corresponding parameter type in M
 386                         //
 387                         if (a.Type == b)
 388                                 return true;
 389
 390                         if (RootContext.Version == LanguageVersion.ISO_1)
 391                                 return false;
 392
 393                         return Convert.ImplicitReferenceConversionExists (a, b);
 394                 }
 395
 396                 public static string FullDelegateDesc (MethodSpec invoke_method)
 397                 {
 398                         return TypeManager.GetFullNameSignature (invoke_method).Replace (".Invoke", "");
 399                 }
 400
 401                 public Expression InstanceExpression {
 402                         get {
 403                                 return instance_expr;
 404                         }
 405                         set {
 406                                 instance_expr = value;
 407                         }
 408                 }
 409         }
 410
 411         //
 412         // Base class for `NewDelegate' and `ImplicitDelegateCreation'
 413         //
 414         public abstract class DelegateCreation : Expression, OverloadResolver.IErrorHandler
 415         {
 416                 protected MethodSpec constructor_method;
 417                 protected MethodGroupExpr method_group;
 418
 419                 public static Arguments CreateDelegateMethodArguments (AParametersCollection pd, TypeSpec[] types, Location loc)
 420                 {
 421                         Arguments delegate_arguments = new Arguments (pd.Count);
 422                         for (int i = 0; i < pd.Count; ++i) {
 423                                 Argument.AType atype_modifier;
 424                                 switch (pd.FixedParameters [i].ModFlags) {
 425                                 case Parameter.Modifier.REF:
 426                                         atype_modifier = Argument.AType.Ref;
 427                                         break;
 428                                 case Parameter.Modifier.OUT:
 429                                         atype_modifier = Argument.AType.Out;
 430                                         break;
 431                                 default:
 432                                         atype_modifier = 0;
 433                                         break;
 434                                 }
 435
 436                                 delegate_arguments.Add (new Argument (new TypeExpression (types [i], loc), atype_modifier));
 437                         }
 438
 439                         return delegate_arguments;
 440                 }
 441
 442                 public override Expression CreateExpressionTree (ResolveContext ec)
 443                 {
 444                         MemberAccess ma = new MemberAccess (new MemberAccess (new QualifiedAliasMember ("global", "System", loc), "Delegate", loc), "CreateDelegate", loc);
 445
 446                         Arguments args = new Arguments (3);
 447                         args.Add (new Argument (new TypeOf (new TypeExpression (type, loc), loc)));
 448                         args.Add (new Argument (new NullLiteral (loc)));
 449                         args.Add (new Argument (method_group.CreateExpressionTree (ec)));
 450                         Expression e = new Invocation (ma, args).Resolve (ec);
 451                         if (e == null)
 452                                 return null;
 453
 454                         e = Convert.ExplicitConversion (ec, e, type, loc);
 455                         if (e == null)
 456                                 return null;
 457
 458                         return e.CreateExpressionTree (ec);
 459                 }
 460
 461                 protected override Expression DoResolve (ResolveContext ec)
 462                 {
 463                         constructor_method = Delegate.GetConstructor (ec.Compiler, ec.CurrentType, type);
 464
 465                         var invoke_method = Delegate.GetInvokeMethod (ec.Compiler, type);
 466
 467                         Arguments arguments = CreateDelegateMethodArguments (invoke_method.Parameters, invoke_method.Parameters.Types, loc);
 468                         method_group = method_group.OverloadResolve (ec, ref arguments, this, OverloadResolver.Restrictions.CovariantDelegate);
 469                         if (method_group == null)
 470                                 return null;
 471
 472                         var delegate_method = method_group.BestCandidate;
 473
 474                         if (TypeManager.IsNullableType (delegate_method.DeclaringType)) {
 475                                 ec.Report.Error (1728, loc, "Cannot create delegate from method `{0}' because it is a member of System.Nullable<T> type",
 476                                         delegate_method.GetSignatureForError ());
 477                                 return null;
 478                         }
 479
 480                         Invocation.IsSpecialMethodInvocation (ec, delegate_method, loc);
 481
 482                         ExtensionMethodGroupExpr emg = method_group as ExtensionMethodGroupExpr;
 483                         if (emg != null) {
 484                                 method_group.InstanceExpression = emg.ExtensionExpression;
 485                                 TypeSpec e_type = emg.ExtensionExpression.Type;
 486                                 if (TypeManager.IsValueType (e_type)) {
 487                                         ec.Report.Error (1113, loc, "Extension method `{0}' of value type `{1}' cannot be used to create delegates",
 488                                                 delegate_method.GetSignatureForError (), TypeManager.CSharpName (e_type));
 489                                 }
 490                         }
 491
 492                         TypeSpec rt = delegate_method.ReturnType;
 493                         Expression ret_expr = new TypeExpression (rt, loc);
 494                         if (!Delegate.IsTypeCovariant (ret_expr, invoke_method.ReturnType)) {
 495                                 Error_ConversionFailed (ec, delegate_method, ret_expr);
 496                         }
 497
 498                         if (delegate_method.IsConditionallyExcluded (loc)) {
 499                                 ec.Report.SymbolRelatedToPreviousError (delegate_method);
 500                                 MethodOrOperator m = delegate_method.MemberDefinition as MethodOrOperator;
 501                                 if (m != null && m.IsPartialDefinition) {
 502                                         ec.Report.Error (762, loc, "Cannot create delegate from partial method declaration `{0}'",
 503                                                 delegate_method.GetSignatureForError ());
 504                                 } else {
 505                                         ec.Report.Error (1618, loc, "Cannot create delegate with `{0}' because it has a Conditional attribute",
 506                                                 TypeManager.CSharpSignature (delegate_method));
 507                                 }
 508                         }
 509
 510                         var expr = method_group.InstanceExpression;
 511                         if (expr != null && (expr.Type.IsGenericParameter || !TypeManager.IsReferenceType (expr.Type)))
 512                                 method_group.InstanceExpression = new BoxedCast (expr, TypeManager.object_type);
 513
 514                         eclass = ExprClass.Value;
 515                         return this;
 516                 }
 517
 518                 public override void Emit (EmitContext ec)
 519                 {
 520                         if (method_group.InstanceExpression == null)
 521                                 ec.Emit (OpCodes.Ldnull);
 522                         else
 523                                 method_group.InstanceExpression.Emit (ec);
 524
 525                         var delegate_method = method_group.BestCandidate;
 526
 527                         // Any delegate must be sealed
 528                         if (!delegate_method.DeclaringType.IsDelegate && delegate_method.IsVirtual && !method_group.IsBase) {
 529                                 ec.Emit (OpCodes.Dup);
 530                                 ec.Emit (OpCodes.Ldvirtftn, delegate_method);
 531                         } else {
 532                                 ec.Emit (OpCodes.Ldftn, delegate_method);
 533                         }
 534
 535                         ec.Emit (OpCodes.Newobj, constructor_method);
 536                 }
 537
 538                 void Error_ConversionFailed (ResolveContext ec, MethodSpec method, Expression return_type)
 539                 {
 540                         var invoke_method = Delegate.GetInvokeMethod (ec.Compiler, type);
 541                         string member_name = method_group.InstanceExpression != null ?
 542                                 Delegate.FullDelegateDesc (method) :
 543                                 TypeManager.GetFullNameSignature (method);
 544
 545                         ec.Report.SymbolRelatedToPreviousError (type);
 546                         ec.Report.SymbolRelatedToPreviousError (method);
 547                         if (RootContext.Version == LanguageVersion.ISO_1) {
 548                                 ec.Report.Error (410, loc, "A method or delegate `{0} {1}' parameters and return type must be same as delegate `{2} {3}' parameters and return type",
 549                                         TypeManager.CSharpName (method.ReturnType), member_name,
 550                                         TypeManager.CSharpName (invoke_method.ReturnType), Delegate.FullDelegateDesc (invoke_method));
 551                                 return;
 552                         }
 553
 554                         if (return_type == null) {
 555                                 ec.Report.Error (123, loc, "A method or delegate `{0}' parameters do not match delegate `{1}' parameters",
 556                                         member_name, Delegate.FullDelegateDesc (invoke_method));
 557                                 return;
 558                         }
 559
 560                         ec.Report.Error (407, loc, "A method or delegate `{0} {1}' return type does not match delegate `{2} {3}' return type",
 561                                 return_type.GetSignatureForError (), member_name,
 562                                 TypeManager.CSharpName (invoke_method.ReturnType), Delegate.FullDelegateDesc (invoke_method));
 563                 }
 564
 565                 public static bool ImplicitStandardConversionExists (ResolveContext ec, MethodGroupExpr mg, TypeSpec target_type)
 566                 {
 567                         if (target_type == TypeManager.delegate_type || target_type == TypeManager.multicast_delegate_type)
 568                                 return false;
 569
 570                         var invoke = Delegate.GetInvokeMethod (ec.Compiler, target_type);
 571
 572                         Arguments arguments = CreateDelegateMethodArguments (invoke.Parameters, invoke.Parameters.Types, mg.Location);
 573                         return mg.OverloadResolve (ec, ref arguments, null, OverloadResolver.Restrictions.CovariantDelegate | OverloadResolver.Restrictions.ProbingOnly) != null;
 574                 }
 575
 576                 #region IErrorHandler Members
 577
 578                 bool OverloadResolver.IErrorHandler.AmbiguousCandidates (ResolveContext ec, MemberSpec best, MemberSpec ambiguous)
 579                 {
 580                         return false;
 581                 }
 582
 583                 bool OverloadResolver.IErrorHandler.ArgumentMismatch (ResolveContext rc, MemberSpec best, Argument arg, int index)
 584                 {
 585                         Error_ConversionFailed (rc, best as MethodSpec, null);
 586                         return true;
 587                 }
 588
 589                 bool OverloadResolver.IErrorHandler.NoArgumentMatch (ResolveContext rc, MemberSpec best)
 590                 {
 591                         Error_ConversionFailed (rc, best as MethodSpec, null);
 592                         return true;
 593                 }
 594
 595                 bool OverloadResolver.IErrorHandler.TypeInferenceFailed (ResolveContext rc, MemberSpec best)
 596                 {
 597                         return false;
 598                 }
 599
 600                 #endregion
 601         }
 602
 603         //
 604         // Created from the conversion code
 605         //
 606         public class ImplicitDelegateCreation : DelegateCreation
 607         {
 608                 ImplicitDelegateCreation (TypeSpec t, MethodGroupExpr mg, Location l)
 609                 {
 610                         type = t;
 611                         this.method_group = mg;
 612                         loc = l;
 613                 }
 614
 615                 static public Expression Create (ResolveContext ec, MethodGroupExpr mge,
 616                                                  TypeSpec target_type, Location loc)
 617                 {
 618                         ImplicitDelegateCreation d = new ImplicitDelegateCreation (target_type, mge, loc);
 619                         return d.DoResolve (ec);
 620                 }
 621         }
 622
 623         //
 624         // A delegate-creation-expression, invoked from the `New' class
 625         //
 626         public class NewDelegate : DelegateCreation
 627         {
 628                 public Arguments Arguments;
 629
 630                 //
 631                 // This constructor is invoked from the `New' expression
 632                 //
 633                 public NewDelegate (TypeSpec type, Arguments Arguments, Location loc)
 634                 {
 635                         this.type = type;
 636                         this.Arguments = Arguments;
 637                         this.loc  = loc;
 638                 }
 639
 640                 protected override Expression DoResolve (ResolveContext ec)
 641                 {
 642                         if (Arguments == null || Arguments.Count != 1) {
 643                                 ec.Report.Error (149, loc, "Method name expected");
 644                                 return null;
 645                         }
 646
 647                         Argument a = Arguments [0];
 648                         if (!a.ResolveMethodGroup (ec))
 649                                 return null;
 650
 651                         Expression e = a.Expr;
 652
 653                         AnonymousMethodExpression ame = e as AnonymousMethodExpression;
 654                         if (ame != null && RootContext.Version != LanguageVersion.ISO_1) {
 655                                 e = ame.Compatible (ec, type);
 656                                 if (e == null)
 657                                         return null;
 658
 659                                 return e.Resolve (ec);
 660                         }
 661
 662                         method_group = e as MethodGroupExpr;
 663                         if (method_group == null) {
 664                                 if (e.Type == InternalType.Dynamic) {
 665                                         e = Convert.ImplicitConversionRequired (ec, e, type, loc);
 666                                 } else if (!e.Type.IsDelegate) {
 667                                         e.Error_UnexpectedKind (ec, ResolveFlags.MethodGroup | ResolveFlags.Type, loc);
 668                                         return null;
 669                                 }
 670
 671                                 //
 672                                 // An argument is not a method but another delegate
 673                                 //
 674                                 method_group = new MethodGroupExpr (Delegate.GetInvokeMethod (ec.Compiler, e.Type), e.Type, loc);
 675                                 method_group.InstanceExpression = e;
 676                         }
 677
 678                         return base.DoResolve (ec);
 679                 }
 680         }
 681
 682         //
 683         // Invocation converted to delegate Invoke call
 684         //
 685         class DelegateInvocation : ExpressionStatement
 686         {
 687                 readonly Expression InstanceExpr;
 688                 Arguments arguments;
 689                 MethodSpec method;
 690
 691                 public DelegateInvocation (Expression instance_expr, Arguments args, Location loc)
 692                 {
 693                         this.InstanceExpr = instance_expr;
 694                         this.arguments = args;
 695                         this.loc = loc;
 696                 }
 697
 698                 public override Expression CreateExpressionTree (ResolveContext ec)
 699                 {
 700                         Arguments args = Arguments.CreateForExpressionTree (ec, this.arguments,
 701                                 InstanceExpr.CreateExpressionTree (ec));
 702
 703                         return CreateExpressionFactoryCall (ec, "Invoke", args);
 704                 }
 705
 706                 protected override Expression DoResolve (ResolveContext ec)
 707                 {
 708                         TypeSpec del_type = InstanceExpr.Type;
 709                         if (del_type == null)
 710                                 return null;
 711
 712                         //
 713                         // Do only core overload resolution the rest of the checks has been
 714                         // done on primary expression
 715                         //
 716                         method = Delegate.GetInvokeMethod (ec.Compiler, del_type);
 717                         var res = new OverloadResolver (new MemberSpec[] { method }, OverloadResolver.Restrictions.DelegateInvoke, loc);
 718                         var valid = res.ResolveMember<MethodSpec> (ec, ref arguments);
 719                         if (valid == null && !res.BestCandidateIsDynamic)
 720                                 return null;
 721
 722                         type = method.ReturnType;
 723                         eclass = ExprClass.Value;
 724                         return this;
 725                 }
 726
 727                 public override void Emit (EmitContext ec)
 728                 {
 729                         //
 730                         // Invocation on delegates call the virtual Invoke member
 731                         // so we are always `instance' calls
 732                         //
 733                         Invocation.EmitCall (ec, InstanceExpr, method, arguments, loc);
 734                 }
 735
 736                 public override void EmitStatement (EmitContext ec)
 737                 {
 738                         Emit (ec);
 739                         //
 740                         // Pop the return value if there is one
 741                         //
 742                         if (type != TypeManager.void_type)
 743                                 ec.Emit (OpCodes.Pop);
 744                 }
 745
 746                 public override System.Linq.Expressions.Expression MakeExpression (BuilderContext ctx)
 747                 {
 748                         return Invocation.MakeExpression (ctx, InstanceExpr, method, arguments);
 749                 }
 750         }
 751 }