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