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
  17 #if STATIC
  18 using IKVM.Reflection;
  19 using IKVM.Reflection.Emit;
  20 #else
  21 using System.Reflection;
  22 using System.Reflection.Emit;
  23 #endif
  24
  25 namespace Mono.CSharp {
  26
  27         //
  28         // Delegate container implementation
  29         //
  30         public class Delegate : TypeContainer, IParametersMember
  31         {
  32                 FullNamedExpression ReturnType;
  33                 readonly ParametersCompiled parameters;
  34
  35                 Constructor Constructor;
  36                 Method InvokeBuilder;
  37                 Method BeginInvokeBuilder;
  38                 Method EndInvokeBuilder;
  39
  40                 static readonly string[] attribute_targets = new string [] { "type", "return" };
  41
  42                 public static readonly string InvokeMethodName = "Invoke";
  43
  44                 Expression instance_expr;
  45                 ReturnParameter return_attributes;
  46
  47                 const Modifiers MethodModifiers = Modifiers.PUBLIC | Modifiers.VIRTUAL;
  48
  49                 const Modifiers AllowedModifiers =
  50                         Modifiers.NEW |
  51                         Modifiers.PUBLIC |
  52                         Modifiers.PROTECTED |
  53                         Modifiers.INTERNAL |
  54                         Modifiers.UNSAFE |
  55                         Modifiers.PRIVATE;
  56
  57                 public Delegate (NamespaceEntry ns, DeclSpace parent, FullNamedExpression type,
  58                                  Modifiers mod_flags, MemberName name, ParametersCompiled param_list,
  59                                  Attributes attrs)
  60                         : base (ns, parent, name, attrs, MemberKind.Delegate)
  61
  62                 {
  63                         this.ReturnType = type;
  64                         ModFlags        = ModifiersExtensions.Check (AllowedModifiers, mod_flags,
  65                                                            IsTopLevel ? Modifiers.INTERNAL :
  66                                                            Modifiers.PRIVATE, name.Location, Report);
  67                         parameters      = param_list;
  68                         spec = new TypeSpec (Kind, null, this, null, ModFlags | Modifiers.SEALED);
  69                 }
  70
  71                 #region Properties
  72                 public TypeSpec MemberType {
  73                         get {
  74                                 return ReturnType.Type;
  75                         }
  76                 }
  77
  78                 public AParametersCollection Parameters {
  79                         get {
  80                                 return parameters;
  81                         }
  82                 }
  83                 #endregion
  84
  85                 public override void Accept (StructuralVisitor visitor)
  86                 {
  87                         visitor.Visit (this);
  88                 }
  89
  90                 public override void ApplyAttributeBuilder (Attribute a, MethodSpec ctor, byte[] cdata, PredefinedAttributes pa)
  91                 {
  92                         if (a.Target == AttributeTargets.ReturnValue) {
  93                                 if (return_attributes == null)
  94                                         return_attributes = new ReturnParameter (this, InvokeBuilder.MethodBuilder, Location);
  95
  96                                 return_attributes.ApplyAttributeBuilder (a, ctor, cdata, pa);
  97                                 return;
  98                         }
  99
 100                         base.ApplyAttributeBuilder (a, ctor, cdata, pa);
 101                 }
 102
 103                 public override AttributeTargets AttributeTargets {
 104                         get {
 105                                 return AttributeTargets.Delegate;
 106                         }
 107                 }
 108
 109                 protected override bool DoDefineMembers ()
 110                 {
 111                         var buildin_types = Compiler.BuildinTypes;
 112
 113                         var ctor_parameters = ParametersCompiled.CreateFullyResolved (
 114                                 new [] {
 115                                         new Parameter (new TypeExpression (buildin_types.Object, Location), "object", Parameter.Modifier.NONE, null, Location),
 116                                         new Parameter (new TypeExpression (buildin_types.IntPtr, Location), "method", Parameter.Modifier.NONE, null, Location)
 117                                 },
 118                                 new [] {
 119                                         buildin_types.Object,
 120                                         buildin_types.IntPtr
 121                                 }
 122                         );
 123
 124                         Constructor = new Constructor (this, Constructor.ConstructorName,
 125                                 Modifiers.PUBLIC, null, ctor_parameters, null, Location);
 126                         Constructor.Define ();
 127
 128                         //
 129                         // Here the various methods like Invoke, BeginInvoke etc are defined
 130                         //
 131                         // First, call the `out of band' special method for
 132                         // defining recursively any types we need:
 133                         //
 134                         var p = parameters;
 135
 136                         if (!p.Resolve (this))
 137                                 return false;
 138
 139                         //
 140                         // Invoke method
 141                         //
 142
 143                         // Check accessibility
 144                         foreach (var partype in p.Types) {
 145                                 if (!IsAccessibleAs (partype)) {
 146                                         Report.SymbolRelatedToPreviousError (partype);
 147                                         Report.Error (59, Location,
 148                                                 "Inconsistent accessibility: parameter type `{0}' is less accessible than delegate `{1}'",
 149                                                 TypeManager.CSharpName (partype), GetSignatureForError ());
 150                                 }
 151                         }
 152
 153                         ReturnType = ReturnType.ResolveAsTypeTerminal (this, false);
 154                         if (ReturnType == null)
 155                                 return false;
 156
 157                         var ret_type = ReturnType.Type;
 158
 159                         //
 160                         // We don't have to check any others because they are all
 161                         // guaranteed to be accessible - they are standard types.
 162                         //
 163                         if (!IsAccessibleAs (ret_type)) {
 164                                 Report.SymbolRelatedToPreviousError (ret_type);
 165                                 Report.Error (58, Location,
 166                                                   "Inconsistent accessibility: return type `" +
 167                                                   TypeManager.CSharpName (ret_type) + "' is less " +
 168                                                   "accessible than delegate `" + GetSignatureForError () + "'");
 169                                 return false;
 170                         }
 171
 172                         CheckProtectedModifier ();
 173
 174                         if (Compiler.Settings.StdLib && ret_type.IsSpecialRuntimeType) {
 175                                 Method.Error1599 (Location, ret_type, Report);
 176                                 return false;
 177                         }
 178
 179                         TypeManager.CheckTypeVariance (ret_type, Variance.Covariant, this);
 180
 181                         InvokeBuilder = new Method (this, null, ReturnType, MethodModifiers, new MemberName (InvokeMethodName), p, null);
 182                         InvokeBuilder.Define ();
 183
 184                         //
 185                         // Don't emit async method for compiler generated delegates (e.g. dynamic site containers)
 186                         //
 187                         if (!IsCompilerGenerated) {
 188                                 DefineAsyncMethods (Parameters.CallingConvention);
 189                         }
 190
 191                         return true;
 192                 }
 193
 194                 void DefineAsyncMethods (CallingConventions cc)
 195                 {
 196                         var iasync_result = Module.PredefinedTypes.IAsyncResult;
 197                         var async_callback = Module.PredefinedTypes.AsyncCallback;
 198
 199                         //
 200                         // It's ok when async types don't exist, the delegate will have Invoke method only
 201                         //
 202                         if (!iasync_result.Define () || !async_callback.Define ())
 203                                 return;
 204
 205                         //
 206                         // BeginInvoke
 207                         //
 208                         ParametersCompiled async_parameters;
 209                         if (Parameters.Count == 0) {
 210                                 async_parameters = ParametersCompiled.EmptyReadOnlyParameters;
 211                         } else {
 212                                 var compiled = new Parameter[Parameters.Count];
 213                                 for (int i = 0; i < compiled.Length; ++i) {
 214                                         var p = parameters[i];
 215                                         compiled[i] = new Parameter (new TypeExpression (parameters.Types[i], Location),
 216                                                 p.Name,
 217                                                 p.ModFlags & (Parameter.Modifier.REF | Parameter.Modifier.OUT),
 218                                                 p.OptAttributes == null ? null : p.OptAttributes.Clone (), Location);
 219                                 }
 220
 221                                 async_parameters = new ParametersCompiled (compiled);
 222                         }
 223
 224                         async_parameters = ParametersCompiled.MergeGenerated (Compiler, async_parameters, false,
 225                                 new Parameter[] {
 226                                         new Parameter (new TypeExpression (async_callback.TypeSpec, Location), "callback", Parameter.Modifier.NONE, null, Location),
 227                                         new Parameter (new TypeExpression (Compiler.BuildinTypes.Object, Location), "object", Parameter.Modifier.NONE, null, Location)
 228                                 },
 229                                 new [] {
 230                                         async_callback.TypeSpec,
 231                                         Compiler.BuildinTypes.Object
 232                                 }
 233                         );
 234
 235                         BeginInvokeBuilder = new Method (this, null,
 236                                 new TypeExpression (iasync_result.TypeSpec, Location), MethodModifiers,
 237                                 new MemberName ("BeginInvoke"), async_parameters, null);
 238                         BeginInvokeBuilder.Define ();
 239
 240                         //
 241                         // EndInvoke is a bit more interesting, all the parameters labeled as
 242                         // out or ref have to be duplicated here.
 243                         //
 244
 245                         //
 246                         // Define parameters, and count out/ref parameters
 247                         //
 248                         ParametersCompiled end_parameters;
 249                         int out_params = 0;
 250
 251                         foreach (Parameter p in Parameters.FixedParameters) {
 252                                 if ((p.ModFlags & Parameter.Modifier.ISBYREF) != 0)
 253                                         ++out_params;
 254                         }
 255
 256                         if (out_params > 0) {
 257                                 Parameter[] end_params = new Parameter[out_params];
 258
 259                                 int param = 0;
 260                                 for (int i = 0; i < Parameters.FixedParameters.Length; ++i) {
 261                                         Parameter p = parameters [i];
 262                                         if ((p.ModFlags & Parameter.Modifier.ISBYREF) == 0)
 263                                                 continue;
 264
 265                                         end_params [param++] = new Parameter (new TypeExpression (p.Type, Location),
 266                                                 p.Name,
 267                                                 p.ModFlags & (Parameter.Modifier.REF | Parameter.Modifier.OUT),
 268                                                 p.OptAttributes == null ? null : p.OptAttributes.Clone (), Location);
 269                                 }
 270
 271                                 end_parameters = new ParametersCompiled (end_params);
 272                         } else {
 273                                 end_parameters = ParametersCompiled.EmptyReadOnlyParameters;
 274                         }
 275
 276                         end_parameters = ParametersCompiled.MergeGenerated (Compiler, end_parameters, false,
 277                                 new Parameter (
 278                                         new TypeExpression (iasync_result.TypeSpec, Location),
 279                                         "result", Parameter.Modifier.NONE, null, Location),
 280                                 iasync_result.TypeSpec);
 281
 282                         //
 283                         // Create method, define parameters, register parameters with type system
 284                         //
 285                         EndInvokeBuilder = new Method (this, null, ReturnType, MethodModifiers, new MemberName ("EndInvoke"), end_parameters, null);
 286                         EndInvokeBuilder.Define ();
 287                 }
 288
 289                 public override void DefineConstants ()
 290                 {
 291                         if (!Parameters.IsEmpty) {
 292                                 parameters.ResolveDefaultValues (this);
 293                         }
 294                 }
 295
 296                 public override void EmitType ()
 297                 {
 298                         if (ReturnType.Type != null) {
 299                                 if (ReturnType.Type.BuildinType == BuildinTypeSpec.Type.Dynamic) {
 300                                         return_attributes = new ReturnParameter (this, InvokeBuilder.MethodBuilder, Location);
 301                                         Module.PredefinedAttributes.Dynamic.EmitAttribute (return_attributes.Builder);
 302                                 } else if (ReturnType.Type.HasDynamicElement) {
 303                                         return_attributes = new ReturnParameter (this, InvokeBuilder.MethodBuilder, Location);
 304                                         Module.PredefinedAttributes.Dynamic.EmitAttribute (return_attributes.Builder, ReturnType.Type, Location);
 305                                 }
 306                         }
 307
 308                         Constructor.ParameterInfo.ApplyAttributes (this, Constructor.ConstructorBuilder);
 309                         Constructor.ConstructorBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 310
 311                         parameters.ApplyAttributes (this, InvokeBuilder.MethodBuilder);
 312                         InvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 313
 314                         if (BeginInvokeBuilder != null) {
 315                                 BeginInvokeBuilder.ParameterInfo.ApplyAttributes (this, BeginInvokeBuilder.MethodBuilder);
 316                                 EndInvokeBuilder.ParameterInfo.ApplyAttributes (this, EndInvokeBuilder.MethodBuilder);
 317
 318                                 BeginInvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 319                                 EndInvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 320                         }
 321
 322                         if (OptAttributes != null) {
 323                                 OptAttributes.Emit ();
 324                         }
 325
 326                         base.Emit ();
 327                 }
 328
 329                 protected override TypeExpr[] ResolveBaseTypes (out TypeExpr base_class)
 330                 {
 331                         base_type = Compiler.BuildinTypes.MulticastDelegate;
 332                         base_class = null;
 333                         return null;
 334                 }
 335
 336                 protected override TypeAttributes TypeAttr {
 337                         get {
 338                                 return ModifiersExtensions.TypeAttr (ModFlags, IsTopLevel) |
 339                                         TypeAttributes.Class | TypeAttributes.Sealed |
 340                                         base.TypeAttr;
 341                         }
 342                 }
 343
 344                 public override string[] ValidAttributeTargets {
 345                         get {
 346                                 return attribute_targets;
 347                         }
 348                 }
 349
 350                 //TODO: duplicate
 351                 protected override bool VerifyClsCompliance ()
 352                 {
 353                         if (!base.VerifyClsCompliance ()) {
 354                                 return false;
 355                         }
 356
 357                         parameters.VerifyClsCompliance (this);
 358
 359                         if (!ReturnType.Type.IsCLSCompliant ()) {
 360                                 Report.Warning (3002, 1, Location, "Return type of `{0}' is not CLS-compliant",
 361                                         GetSignatureForError ());
 362                         }
 363                         return true;
 364                 }
 365
 366
 367                 public static MethodSpec GetConstructor (TypeSpec delType)
 368                 {
 369                         var ctor = MemberCache.FindMember (delType, MemberFilter.Constructor (null), BindingRestriction.DeclaredOnly);
 370                         return (MethodSpec) ctor;
 371                 }
 372
 373                 //
 374                 // Returns the "Invoke" from a delegate type
 375                 //
 376                 public static MethodSpec GetInvokeMethod (TypeSpec delType)
 377                 {
 378                         var invoke = MemberCache.FindMember (delType,
 379                                 MemberFilter.Method (InvokeMethodName, 0, null, null),
 380                                 BindingRestriction.DeclaredOnly);
 381
 382                         return (MethodSpec) invoke;
 383                 }
 384
 385                 public static AParametersCollection GetParameters (TypeSpec delType)
 386                 {
 387                         var invoke_mb = GetInvokeMethod (delType);
 388                         return invoke_mb.Parameters;
 389                 }
 390
 391                 //
 392                 // 15.2 Delegate compatibility
 393                 //
 394                 public static bool IsTypeCovariant (ResolveContext rc, Expression a, TypeSpec b)
 395                 {
 396                         //
 397                         // For each value parameter (a parameter with no ref or out modifier), an
 398                         // identity conversion or implicit reference conversion exists from the
 399                         // parameter type in D to the corresponding parameter type in M
 400                         //
 401                         if (a.Type == b)
 402                                 return true;
 403
 404                         if (rc.Module.Compiler.Settings.Version == LanguageVersion.ISO_1)
 405                                 return false;
 406
 407                         return Convert.ImplicitReferenceConversionExists (a, b);
 408                 }
 409
 410                 public static string FullDelegateDesc (MethodSpec invoke_method)
 411                 {
 412                         return TypeManager.GetFullNameSignature (invoke_method).Replace (".Invoke", "");
 413                 }
 414
 415                 public Expression InstanceExpression {
 416                         get {
 417                                 return instance_expr;
 418                         }
 419                         set {
 420                                 instance_expr = value;
 421                         }
 422                 }
 423         }
 424
 425         //
 426         // Base class for `NewDelegate' and `ImplicitDelegateCreation'
 427         //
 428         public abstract class DelegateCreation : Expression, OverloadResolver.IErrorHandler
 429         {
 430                 protected MethodSpec constructor_method;
 431                 protected MethodGroupExpr method_group;
 432
 433                 public static Arguments CreateDelegateMethodArguments (AParametersCollection pd, TypeSpec[] types, Location loc)
 434                 {
 435                         Arguments delegate_arguments = new Arguments (pd.Count);
 436                         for (int i = 0; i < pd.Count; ++i) {
 437                                 Argument.AType atype_modifier;
 438                                 switch (pd.FixedParameters [i].ModFlags) {
 439                                 case Parameter.Modifier.REF:
 440                                         atype_modifier = Argument.AType.Ref;
 441                                         break;
 442                                 case Parameter.Modifier.OUT:
 443                                         atype_modifier = Argument.AType.Out;
 444                                         break;
 445                                 default:
 446                                         atype_modifier = 0;
 447                                         break;
 448                                 }
 449
 450                                 delegate_arguments.Add (new Argument (new TypeExpression (types [i], loc), atype_modifier));
 451                         }
 452
 453                         return delegate_arguments;
 454                 }
 455
 456                 public override Expression CreateExpressionTree (ResolveContext ec)
 457                 {
 458                         MemberAccess ma = new MemberAccess (new MemberAccess (new QualifiedAliasMember ("global", "System", loc), "Delegate", loc), "CreateDelegate", loc);
 459
 460                         Arguments args = new Arguments (3);
 461                         args.Add (new Argument (new TypeOf (new TypeExpression (type, loc), loc)));
 462
 463                         if (method_group.InstanceExpression == null)
 464                                 args.Add (new Argument (new NullLiteral (loc)));
 465                         else
 466                                 args.Add (new Argument (method_group.InstanceExpression));
 467
 468                         args.Add (new Argument (method_group.CreateExpressionTree (ec)));
 469                         Expression e = new Invocation (ma, args).Resolve (ec);
 470                         if (e == null)
 471                                 return null;
 472
 473                         e = Convert.ExplicitConversion (ec, e, type, loc);
 474                         if (e == null)
 475                                 return null;
 476
 477                         return e.CreateExpressionTree (ec);
 478                 }
 479
 480                 protected override Expression DoResolve (ResolveContext ec)
 481                 {
 482                         constructor_method = Delegate.GetConstructor (type);
 483
 484                         var invoke_method = Delegate.GetInvokeMethod (type);
 485
 486                         Arguments arguments = CreateDelegateMethodArguments (invoke_method.Parameters, invoke_method.Parameters.Types, loc);
 487                         method_group = method_group.OverloadResolve (ec, ref arguments, this, OverloadResolver.Restrictions.CovariantDelegate);
 488                         if (method_group == null)
 489                                 return null;
 490
 491                         var delegate_method = method_group.BestCandidate;
 492
 493                         if (delegate_method.DeclaringType.IsNullableType) {
 494                                 ec.Report.Error (1728, loc, "Cannot create delegate from method `{0}' because it is a member of System.Nullable<T> type",
 495                                         delegate_method.GetSignatureForError ());
 496                                 return null;
 497                         }
 498
 499                         Invocation.IsSpecialMethodInvocation (ec, delegate_method, loc);
 500
 501                         ExtensionMethodGroupExpr emg = method_group as ExtensionMethodGroupExpr;
 502                         if (emg != null) {
 503                                 method_group.InstanceExpression = emg.ExtensionExpression;
 504                                 TypeSpec e_type = emg.ExtensionExpression.Type;
 505                                 if (TypeManager.IsValueType (e_type)) {
 506                                         ec.Report.Error (1113, loc, "Extension method `{0}' of value type `{1}' cannot be used to create delegates",
 507                                                 delegate_method.GetSignatureForError (), TypeManager.CSharpName (e_type));
 508                                 }
 509                         }
 510
 511                         TypeSpec rt = delegate_method.ReturnType;
 512                         Expression ret_expr = new TypeExpression (rt, loc);
 513                         if (!Delegate.IsTypeCovariant (ec, ret_expr, invoke_method.ReturnType)) {
 514                                 Error_ConversionFailed (ec, delegate_method, ret_expr);
 515                         }
 516
 517                         if (delegate_method.IsConditionallyExcluded (loc)) {
 518                                 ec.Report.SymbolRelatedToPreviousError (delegate_method);
 519                                 MethodOrOperator m = delegate_method.MemberDefinition as MethodOrOperator;
 520                                 if (m != null && m.IsPartialDefinition) {
 521                                         ec.Report.Error (762, loc, "Cannot create delegate from partial method declaration `{0}'",
 522                                                 delegate_method.GetSignatureForError ());
 523                                 } else {
 524                                         ec.Report.Error (1618, loc, "Cannot create delegate with `{0}' because it has a Conditional attribute",
 525                                                 TypeManager.CSharpSignature (delegate_method));
 526                                 }
 527                         }
 528
 529                         var expr = method_group.InstanceExpression;
 530                         if (expr != null && (expr.Type.IsGenericParameter || !TypeManager.IsReferenceType (expr.Type)))
 531                                 method_group.InstanceExpression = new BoxedCast (expr, ec.BuildinTypes.Object);
 532
 533                         eclass = ExprClass.Value;
 534                         return this;
 535                 }
 536
 537                 public override void Emit (EmitContext ec)
 538                 {
 539                         if (method_group.InstanceExpression == null)
 540                                 ec.Emit (OpCodes.Ldnull);
 541                         else
 542                                 method_group.InstanceExpression.Emit (ec);
 543
 544                         var delegate_method = method_group.BestCandidate;
 545
 546                         // Any delegate must be sealed
 547                         if (!delegate_method.DeclaringType.IsDelegate && delegate_method.IsVirtual && !method_group.IsBase) {
 548                                 ec.Emit (OpCodes.Dup);
 549                                 ec.Emit (OpCodes.Ldvirtftn, delegate_method);
 550                         } else {
 551                                 ec.Emit (OpCodes.Ldftn, delegate_method);
 552                         }
 553
 554                         ec.Emit (OpCodes.Newobj, constructor_method);
 555                 }
 556
 557                 void Error_ConversionFailed (ResolveContext ec, MethodSpec method, Expression return_type)
 558                 {
 559                         var invoke_method = Delegate.GetInvokeMethod (type);
 560                         string member_name = method_group.InstanceExpression != null ?
 561                                 Delegate.FullDelegateDesc (method) :
 562                                 TypeManager.GetFullNameSignature (method);
 563
 564                         ec.Report.SymbolRelatedToPreviousError (type);
 565                         ec.Report.SymbolRelatedToPreviousError (method);
 566                         if (ec.Module.Compiler.Settings.Version == LanguageVersion.ISO_1) {
 567                                 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",
 568                                         TypeManager.CSharpName (method.ReturnType), member_name,
 569                                         TypeManager.CSharpName (invoke_method.ReturnType), Delegate.FullDelegateDesc (invoke_method));
 570                                 return;
 571                         }
 572
 573                         if (return_type == null) {
 574                                 ec.Report.Error (123, loc, "A method or delegate `{0}' parameters do not match delegate `{1}' parameters",
 575                                         member_name, Delegate.FullDelegateDesc (invoke_method));
 576                                 return;
 577                         }
 578
 579                         ec.Report.Error (407, loc, "A method or delegate `{0} {1}' return type does not match delegate `{2} {3}' return type",
 580                                 return_type.GetSignatureForError (), member_name,
 581                                 TypeManager.CSharpName (invoke_method.ReturnType), Delegate.FullDelegateDesc (invoke_method));
 582                 }
 583
 584                 public static bool ImplicitStandardConversionExists (ResolveContext ec, MethodGroupExpr mg, TypeSpec target_type)
 585                 {
 586 //                      if (target_type == TypeManager.delegate_type || target_type == TypeManager.multicast_delegate_type)
 587 //                              return false;
 588
 589                         var invoke = Delegate.GetInvokeMethod (target_type);
 590
 591                         Arguments arguments = CreateDelegateMethodArguments (invoke.Parameters, invoke.Parameters.Types, mg.Location);
 592                         return mg.OverloadResolve (ec, ref arguments, null, OverloadResolver.Restrictions.CovariantDelegate | OverloadResolver.Restrictions.ProbingOnly) != null;
 593                 }
 594
 595                 #region IErrorHandler Members
 596
 597                 bool OverloadResolver.IErrorHandler.AmbiguousCandidates (ResolveContext ec, MemberSpec best, MemberSpec ambiguous)
 598                 {
 599                         return false;
 600                 }
 601
 602                 bool OverloadResolver.IErrorHandler.ArgumentMismatch (ResolveContext rc, MemberSpec best, Argument arg, int index)
 603                 {
 604                         Error_ConversionFailed (rc, best as MethodSpec, null);
 605                         return true;
 606                 }
 607
 608                 bool OverloadResolver.IErrorHandler.NoArgumentMatch (ResolveContext rc, MemberSpec best)
 609                 {
 610                         Error_ConversionFailed (rc, best as MethodSpec, null);
 611                         return true;
 612                 }
 613
 614                 bool OverloadResolver.IErrorHandler.TypeInferenceFailed (ResolveContext rc, MemberSpec best)
 615                 {
 616                         return false;
 617                 }
 618
 619                 #endregion
 620         }
 621
 622         //
 623         // Created from the conversion code
 624         //
 625         public class ImplicitDelegateCreation : DelegateCreation
 626         {
 627                 ImplicitDelegateCreation (TypeSpec t, MethodGroupExpr mg, Location l)
 628                 {
 629                         type = t;
 630                         this.method_group = mg;
 631                         loc = l;
 632                 }
 633
 634                 static public Expression Create (ResolveContext ec, MethodGroupExpr mge,
 635                                                  TypeSpec target_type, Location loc)
 636                 {
 637                         ImplicitDelegateCreation d = new ImplicitDelegateCreation (target_type, mge, loc);
 638                         return d.DoResolve (ec);
 639                 }
 640         }
 641
 642         //
 643         // A delegate-creation-expression, invoked from the `New' class
 644         //
 645         public class NewDelegate : DelegateCreation
 646         {
 647                 public Arguments Arguments;
 648
 649                 //
 650                 // This constructor is invoked from the `New' expression
 651                 //
 652                 public NewDelegate (TypeSpec type, Arguments Arguments, Location loc)
 653                 {
 654                         this.type = type;
 655                         this.Arguments = Arguments;
 656                         this.loc  = loc;
 657                 }
 658
 659                 protected override Expression DoResolve (ResolveContext ec)
 660                 {
 661                         if (Arguments == null || Arguments.Count != 1) {
 662                                 ec.Report.Error (149, loc, "Method name expected");
 663                                 return null;
 664                         }
 665
 666                         Argument a = Arguments [0];
 667                         if (!a.ResolveMethodGroup (ec))
 668                                 return null;
 669
 670                         Expression e = a.Expr;
 671
 672                         AnonymousMethodExpression ame = e as AnonymousMethodExpression;
 673                         if (ame != null && ec.Module.Compiler.Settings.Version != LanguageVersion.ISO_1) {
 674                                 e = ame.Compatible (ec, type);
 675                                 if (e == null)
 676                                         return null;
 677
 678                                 return e.Resolve (ec);
 679                         }
 680
 681                         method_group = e as MethodGroupExpr;
 682                         if (method_group == null) {
 683                                 if (e.Type.BuildinType == BuildinTypeSpec.Type.Dynamic) {
 684                                         e = Convert.ImplicitConversionRequired (ec, e, type, loc);
 685                                 } else if (!e.Type.IsDelegate) {
 686                                         e.Error_UnexpectedKind (ec, ResolveFlags.MethodGroup | ResolveFlags.Type, loc);
 687                                         return null;
 688                                 }
 689
 690                                 //
 691                                 // An argument is not a method but another delegate
 692                                 //
 693                                 method_group = new MethodGroupExpr (Delegate.GetInvokeMethod (e.Type), e.Type, loc);
 694                                 method_group.InstanceExpression = e;
 695                         }
 696
 697                         return base.DoResolve (ec);
 698                 }
 699         }
 700
 701         //
 702         // Invocation converted to delegate Invoke call
 703         //
 704         class DelegateInvocation : ExpressionStatement
 705         {
 706                 readonly Expression InstanceExpr;
 707                 Arguments arguments;
 708                 MethodSpec method;
 709
 710                 public DelegateInvocation (Expression instance_expr, Arguments args, Location loc)
 711                 {
 712                         this.InstanceExpr = instance_expr;
 713                         this.arguments = args;
 714                         this.loc = loc;
 715                 }
 716
 717                 public override Expression CreateExpressionTree (ResolveContext ec)
 718                 {
 719                         Arguments args = Arguments.CreateForExpressionTree (ec, this.arguments,
 720                                 InstanceExpr.CreateExpressionTree (ec));
 721
 722                         return CreateExpressionFactoryCall (ec, "Invoke", args);
 723                 }
 724
 725                 protected override Expression DoResolve (ResolveContext ec)
 726                 {
 727                         TypeSpec del_type = InstanceExpr.Type;
 728                         if (del_type == null)
 729                                 return null;
 730
 731                         //
 732                         // Do only core overload resolution the rest of the checks has been
 733                         // done on primary expression
 734                         //
 735                         method = Delegate.GetInvokeMethod (del_type);
 736                         var res = new OverloadResolver (new MemberSpec[] { method }, OverloadResolver.Restrictions.DelegateInvoke, loc);
 737                         var valid = res.ResolveMember<MethodSpec> (ec, ref arguments);
 738                         if (valid == null && !res.BestCandidateIsDynamic)
 739                                 return null;
 740
 741                         type = method.ReturnType;
 742                         eclass = ExprClass.Value;
 743                         return this;
 744                 }
 745
 746                 public override void Emit (EmitContext ec)
 747                 {
 748                         //
 749                         // Invocation on delegates call the virtual Invoke member
 750                         // so we are always `instance' calls
 751                         //
 752                         Invocation.EmitCall (ec, InstanceExpr, method, arguments, loc);
 753                 }
 754
 755                 public override void EmitStatement (EmitContext ec)
 756                 {
 757                         Emit (ec);
 758                         //
 759                         // Pop the return value if there is one
 760                         //
 761                         if (type.Kind != MemberKind.Void)
 762                                 ec.Emit (OpCodes.Pop);
 763                 }
 764
 765                 public override System.Linq.Expressions.Expression MakeExpression (BuilderContext ctx)
 766                 {
 767                         return Invocation.MakeExpression (ctx, InstanceExpr, method, arguments);
 768                 }
 769         }
 770 }