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                         Parameter[] compiled = new Parameter[Parameters.Count];
 174                         for (int i = 0; i < compiled.Length; ++i)
 175                                 compiled[i] = new Parameter (new TypeExpression (Parameters.Types[i], Location),
 176                                         Parameters.FixedParameters[i].Name,
 177                                         Parameters.FixedParameters[i].ModFlags & (Parameter.Modifier.REF | Parameter.Modifier.OUT),
 178                                         null, Location);
 179
 180                         ParametersCompiled async_parameters = new ParametersCompiled (Compiler, compiled);
 181
 182                         async_parameters = ParametersCompiled.MergeGenerated (Compiler, async_parameters, false,
 183                                 new Parameter[] {
 184                                         new Parameter (new TypeExpression (TypeManager.asynccallback_type, Location), "callback", Parameter.Modifier.NONE, null, Location),
 185                                         new Parameter (new TypeExpression (TypeManager.object_type, Location), "object", Parameter.Modifier.NONE, null, Location)
 186                                 },
 187                                 new [] {
 188                                         TypeManager.asynccallback_type,
 189                                         TypeManager.object_type
 190                                 }
 191                         );
 192
 193                         BeginInvokeBuilder = new Method (this, null,
 194                                 new TypeExpression (TypeManager.iasyncresult_type, Location), MethodModifiers,
 195                                 new MemberName ("BeginInvoke"), async_parameters, null);
 196                         BeginInvokeBuilder.Define ();
 197
 198                         //
 199                         // EndInvoke is a bit more interesting, all the parameters labeled as
 200                         // out or ref have to be duplicated here.
 201                         //
 202
 203                         //
 204                         // Define parameters, and count out/ref parameters
 205                         //
 206                         ParametersCompiled end_parameters;
 207                         int out_params = 0;
 208
 209                         foreach (Parameter p in Parameters.FixedParameters) {
 210                                 if ((p.ModFlags & Parameter.Modifier.ISBYREF) != 0)
 211                                         ++out_params;
 212                         }
 213
 214                         if (out_params > 0) {
 215                                 var end_param_types = new TypeSpec [out_params];
 216                                 Parameter[] end_params = new Parameter[out_params];
 217
 218                                 int param = 0;
 219                                 for (int i = 0; i < Parameters.FixedParameters.Length; ++i) {
 220                                         Parameter p = Parameters [i];
 221                                         if ((p.ModFlags & Parameter.Modifier.ISBYREF) == 0)
 222                                                 continue;
 223
 224                                         end_param_types[param] = Parameters.Types[i];
 225                                         end_params[param] = p;
 226                                         ++param;
 227                                 }
 228                                 end_parameters = ParametersCompiled.CreateFullyResolved (end_params, end_param_types);
 229                         } else {
 230                                 end_parameters = ParametersCompiled.EmptyReadOnlyParameters;
 231                         }
 232
 233                         end_parameters = ParametersCompiled.MergeGenerated (Compiler, end_parameters, false,
 234                                 new Parameter (
 235                                         new TypeExpression (TypeManager.iasyncresult_type, Location),
 236                                         "result", Parameter.Modifier.NONE, null, Location),
 237                                 TypeManager.iasyncresult_type);
 238
 239                         //
 240                         // Create method, define parameters, register parameters with type system
 241                         //
 242                         EndInvokeBuilder = new Method (this, null, ReturnType, MethodModifiers, new MemberName ("EndInvoke"), end_parameters, null);
 243                         EndInvokeBuilder.Define ();
 244                 }
 245
 246                 public override void DefineConstants ()
 247                 {
 248                         if (!Parameters.IsEmpty && Parameters[Parameters.Count - 1].HasDefaultValue) {
 249                                 var rc = new ResolveContext (this);
 250                                 Parameters.ResolveDefaultValues (rc);
 251                         }
 252                 }
 253
 254                 public override void EmitType ()
 255                 {
 256                         if (ReturnType.Type == InternalType.Dynamic) {
 257                                 return_attributes = new ReturnParameter (this, InvokeBuilder.MethodBuilder, Location);
 258                                 PredefinedAttributes.Get.Dynamic.EmitAttribute (return_attributes.Builder);
 259                         } else {
 260                                 var trans_flags = TypeManager.HasDynamicTypeUsed (ReturnType.Type);
 261                                 if (trans_flags != null) {
 262                                         var pa = PredefinedAttributes.Get.DynamicTransform;
 263                                         if (pa.Constructor != null || pa.ResolveConstructor (Location, ArrayContainer.MakeType (TypeManager.bool_type))) {
 264                                                 return_attributes = new ReturnParameter (this, InvokeBuilder.MethodBuilder, Location);
 265                                                 return_attributes.Builder.SetCustomAttribute (
 266                                                         new CustomAttributeBuilder (pa.Constructor, new object [] { trans_flags }));
 267                                         }
 268                                 }
 269                         }
 270
 271                         Parameters.ApplyAttributes (InvokeBuilder.MethodBuilder);
 272
 273                         Constructor.ConstructorBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 274                         InvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 275
 276                         if (BeginInvokeBuilder != null) {
 277                                 BeginInvokeBuilder.ParameterInfo.ApplyAttributes (BeginInvokeBuilder.MethodBuilder);
 278
 279                                 BeginInvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 280                                 EndInvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 281                         }
 282
 283                         if (OptAttributes != null) {
 284                                 OptAttributes.Emit ();
 285                         }
 286
 287                         base.Emit ();
 288                 }
 289
 290                 protected override TypeExpr[] ResolveBaseTypes (out TypeExpr base_class)
 291                 {
 292                         base_type = TypeManager.multicast_delegate_type;
 293                         base_class = null;
 294                         return null;
 295                 }
 296
 297                 protected override TypeAttributes TypeAttr {
 298                         get {
 299                                 return ModifiersExtensions.TypeAttr (ModFlags, IsTopLevel) |
 300                                         TypeAttributes.Class | TypeAttributes.Sealed |
 301                                         base.TypeAttr;
 302                         }
 303                 }
 304
 305                 public override string[] ValidAttributeTargets {
 306                         get {
 307                                 return attribute_targets;
 308                         }
 309                 }
 310
 311                 //TODO: duplicate
 312                 protected override bool VerifyClsCompliance ()
 313                 {
 314                         if (!base.VerifyClsCompliance ()) {
 315                                 return false;
 316                         }
 317
 318                         Parameters.VerifyClsCompliance (this);
 319
 320                         if (!ReturnType.Type.IsCLSCompliant ()) {
 321                                 Report.Warning (3002, 1, Location, "Return type of `{0}' is not CLS-compliant",
 322                                         GetSignatureForError ());
 323                         }
 324                         return true;
 325                 }
 326
 327
 328                 public static MethodSpec GetConstructor (CompilerContext ctx, TypeSpec container_type, TypeSpec delType)
 329                 {
 330                         var ctor = MemberCache.FindMember (delType, MemberFilter.Constructor (null), BindingRestriction.DeclaredOnly);
 331                         return (MethodSpec) ctor;
 332                 }
 333
 334                 //
 335                 // Returns the "Invoke" from a delegate type
 336                 //
 337                 public static MethodSpec GetInvokeMethod (CompilerContext ctx, TypeSpec delType)
 338                 {
 339                         var invoke = MemberCache.FindMember (delType,
 340                                 MemberFilter.Method (InvokeMethodName, 0, null, null),
 341                                 BindingRestriction.DeclaredOnly);
 342
 343                         return (MethodSpec) invoke;
 344                 }
 345
 346                 public static AParametersCollection GetParameters (CompilerContext ctx, TypeSpec delType)
 347                 {
 348                         var invoke_mb = GetInvokeMethod (ctx, delType);
 349                         return invoke_mb.Parameters;
 350                 }
 351
 352                 //
 353                 // 15.2 Delegate compatibility
 354                 //
 355                 public static bool IsTypeCovariant (Expression a, TypeSpec b)
 356                 {
 357                         //
 358                         // For each value parameter (a parameter with no ref or out modifier), an
 359                         // identity conversion or implicit reference conversion exists from the
 360                         // parameter type in D to the corresponding parameter type in M
 361                         //
 362                         if (a.Type == b)
 363                                 return true;
 364
 365                         if (RootContext.Version == LanguageVersion.ISO_1)
 366                                 return false;
 367
 368                         return Convert.ImplicitReferenceConversionExists (a, b);
 369                 }
 370
 371                 public static string FullDelegateDesc (MethodSpec invoke_method)
 372                 {
 373                         return TypeManager.GetFullNameSignature (invoke_method).Replace (".Invoke", "");
 374                 }
 375
 376                 public Expression InstanceExpression {
 377                         get {
 378                                 return instance_expr;
 379                         }
 380                         set {
 381                                 instance_expr = value;
 382                         }
 383                 }
 384         }
 385
 386         //
 387         // Base class for `NewDelegate' and `ImplicitDelegateCreation'
 388         //
 389         public abstract class DelegateCreation : Expression, OverloadResolver.IErrorHandler
 390         {
 391                 protected MethodSpec constructor_method;
 392                 protected MethodGroupExpr method_group;
 393
 394                 public static Arguments CreateDelegateMethodArguments (AParametersCollection pd, TypeSpec[] types, Location loc)
 395                 {
 396                         Arguments delegate_arguments = new Arguments (pd.Count);
 397                         for (int i = 0; i < pd.Count; ++i) {
 398                                 Argument.AType atype_modifier;
 399                                 switch (pd.FixedParameters [i].ModFlags) {
 400                                 case Parameter.Modifier.REF:
 401                                         atype_modifier = Argument.AType.Ref;
 402                                         break;
 403                                 case Parameter.Modifier.OUT:
 404                                         atype_modifier = Argument.AType.Out;
 405                                         break;
 406                                 default:
 407                                         atype_modifier = 0;
 408                                         break;
 409                                 }
 410
 411                                 delegate_arguments.Add (new Argument (new TypeExpression (types [i], loc), atype_modifier));
 412                         }
 413
 414                         return delegate_arguments;
 415                 }
 416
 417                 public override Expression CreateExpressionTree (ResolveContext ec)
 418                 {
 419                         MemberAccess ma = new MemberAccess (new MemberAccess (new QualifiedAliasMember ("global", "System", loc), "Delegate", loc), "CreateDelegate", loc);
 420
 421                         Arguments args = new Arguments (3);
 422                         args.Add (new Argument (new TypeOf (new TypeExpression (type, loc), loc)));
 423                         args.Add (new Argument (new NullLiteral (loc)));
 424                         args.Add (new Argument (method_group.CreateExpressionTree (ec)));
 425                         Expression e = new Invocation (ma, args).Resolve (ec);
 426                         if (e == null)
 427                                 return null;
 428
 429                         e = Convert.ExplicitConversion (ec, e, type, loc);
 430                         if (e == null)
 431                                 return null;
 432
 433                         return e.CreateExpressionTree (ec);
 434                 }
 435
 436                 protected override Expression DoResolve (ResolveContext ec)
 437                 {
 438                         constructor_method = Delegate.GetConstructor (ec.Compiler, ec.CurrentType, type);
 439
 440                         var invoke_method = Delegate.GetInvokeMethod (ec.Compiler, type);
 441
 442                         Arguments arguments = CreateDelegateMethodArguments (invoke_method.Parameters, invoke_method.Parameters.Types, loc);
 443                         method_group = method_group.OverloadResolve (ec, ref arguments, this, OverloadResolver.Restrictions.Covariant);
 444                         if (method_group == null)
 445                                 return null;
 446
 447                         var delegate_method = method_group.BestCandidate;
 448
 449                         if (TypeManager.IsNullableType (delegate_method.DeclaringType)) {
 450                                 ec.Report.Error (1728, loc, "Cannot create delegate from method `{0}' because it is a member of System.Nullable<T> type",
 451                                         delegate_method.GetSignatureForError ());
 452                                 return null;
 453                         }
 454
 455                         Invocation.IsSpecialMethodInvocation (ec, delegate_method, loc);
 456
 457                         ExtensionMethodGroupExpr emg = method_group as ExtensionMethodGroupExpr;
 458                         if (emg != null) {
 459                                 method_group.InstanceExpression = emg.ExtensionExpression;
 460                                 TypeSpec e_type = emg.ExtensionExpression.Type;
 461                                 if (TypeManager.IsValueType (e_type)) {
 462                                         ec.Report.Error (1113, loc, "Extension method `{0}' of value type `{1}' cannot be used to create delegates",
 463                                                 delegate_method.GetSignatureForError (), TypeManager.CSharpName (e_type));
 464                                 }
 465                         }
 466
 467                         TypeSpec rt = delegate_method.ReturnType;
 468                         Expression ret_expr = new TypeExpression (rt, loc);
 469                         if (!Delegate.IsTypeCovariant (ret_expr, invoke_method.ReturnType)) {
 470                                 Error_ConversionFailed (ec, delegate_method, ret_expr);
 471                         }
 472
 473                         if (delegate_method.IsConditionallyExcluded (loc)) {
 474                                 ec.Report.SymbolRelatedToPreviousError (delegate_method);
 475                                 MethodOrOperator m = delegate_method.MemberDefinition as MethodOrOperator;
 476                                 if (m != null && m.IsPartialDefinition) {
 477                                         ec.Report.Error (762, loc, "Cannot create delegate from partial method declaration `{0}'",
 478                                                 delegate_method.GetSignatureForError ());
 479                                 } else {
 480                                         ec.Report.Error (1618, loc, "Cannot create delegate with `{0}' because it has a Conditional attribute",
 481                                                 TypeManager.CSharpSignature (delegate_method));
 482                                 }
 483                         }
 484
 485                         var expr = method_group.InstanceExpression;
 486                         if (expr != null && (expr.Type.IsGenericParameter || !TypeManager.IsReferenceType (expr.Type)))
 487                                 method_group.InstanceExpression = new BoxedCast (expr, TypeManager.object_type);
 488
 489                         eclass = ExprClass.Value;
 490                         return this;
 491                 }
 492
 493                 public override void Emit (EmitContext ec)
 494                 {
 495                         if (method_group.InstanceExpression == null)
 496                                 ec.Emit (OpCodes.Ldnull);
 497                         else
 498                                 method_group.InstanceExpression.Emit (ec);
 499
 500                         var delegate_method = method_group.BestCandidate;
 501
 502                         // Any delegate must be sealed
 503                         if (!delegate_method.DeclaringType.IsDelegate && delegate_method.IsVirtual && !method_group.IsBase) {
 504                                 ec.Emit (OpCodes.Dup);
 505                                 ec.Emit (OpCodes.Ldvirtftn, delegate_method);
 506                         } else {
 507                                 ec.Emit (OpCodes.Ldftn, delegate_method);
 508                         }
 509
 510                         ec.Emit (OpCodes.Newobj, constructor_method);
 511                 }
 512
 513                 void Error_ConversionFailed (ResolveContext ec, MethodSpec method, Expression return_type)
 514                 {
 515                         var invoke_method = Delegate.GetInvokeMethod (ec.Compiler, type);
 516                         string member_name = method_group.InstanceExpression != null ?
 517                                 Delegate.FullDelegateDesc (method) :
 518                                 TypeManager.GetFullNameSignature (method);
 519
 520                         ec.Report.SymbolRelatedToPreviousError (type);
 521                         ec.Report.SymbolRelatedToPreviousError (method);
 522                         if (RootContext.Version == LanguageVersion.ISO_1) {
 523                                 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",
 524                                         TypeManager.CSharpName (method.ReturnType), member_name,
 525                                         TypeManager.CSharpName (invoke_method.ReturnType), Delegate.FullDelegateDesc (invoke_method));
 526                                 return;
 527                         }
 528
 529                         if (return_type == null) {
 530                                 ec.Report.Error (123, loc, "A method or delegate `{0}' parameters do not match delegate `{1}' parameters",
 531                                         member_name, Delegate.FullDelegateDesc (invoke_method));
 532                                 return;
 533                         }
 534
 535                         ec.Report.Error (407, loc, "A method or delegate `{0} {1}' return type does not match delegate `{2} {3}' return type",
 536                                 return_type.GetSignatureForError (), member_name,
 537                                 TypeManager.CSharpName (invoke_method.ReturnType), Delegate.FullDelegateDesc (invoke_method));
 538                 }
 539
 540                 public static bool ImplicitStandardConversionExists (ResolveContext ec, MethodGroupExpr mg, TypeSpec target_type)
 541                 {
 542                         if (target_type == TypeManager.delegate_type || target_type == TypeManager.multicast_delegate_type)
 543                                 return false;
 544
 545                         var invoke = Delegate.GetInvokeMethod (ec.Compiler, target_type);
 546
 547                         Arguments arguments = CreateDelegateMethodArguments (invoke.Parameters, invoke.Parameters.Types, mg.Location);
 548                         return mg.OverloadResolve (ec, ref arguments, null, OverloadResolver.Restrictions.Covariant | OverloadResolver.Restrictions.ProbingOnly) != null;
 549                 }
 550
 551                 #region IErrorHandler Members
 552
 553                 bool OverloadResolver.IErrorHandler.AmbiguousCandidates (ResolveContext ec, MemberSpec best, MemberSpec ambiguous)
 554                 {
 555                         return false;
 556                 }
 557
 558                 bool OverloadResolver.IErrorHandler.ArgumentMismatch (ResolveContext rc, MemberSpec best, Argument arg, int index)
 559                 {
 560                         Error_ConversionFailed (rc, best as MethodSpec, null);
 561                         return true;
 562                 }
 563
 564                 bool OverloadResolver.IErrorHandler.NoArgumentMatch (ResolveContext rc, MemberSpec best)
 565                 {
 566                         Error_ConversionFailed (rc, best as MethodSpec, null);
 567                         return true;
 568                 }
 569
 570                 bool OverloadResolver.IErrorHandler.TypeInferenceFailed (ResolveContext rc, MemberSpec best)
 571                 {
 572                         return false;
 573                 }
 574
 575                 #endregion
 576         }
 577
 578         //
 579         // Created from the conversion code
 580         //
 581         public class ImplicitDelegateCreation : DelegateCreation
 582         {
 583                 ImplicitDelegateCreation (TypeSpec t, MethodGroupExpr mg, Location l)
 584                 {
 585                         type = t;
 586                         this.method_group = mg;
 587                         loc = l;
 588                 }
 589
 590                 static public Expression Create (ResolveContext ec, MethodGroupExpr mge,
 591                                                  TypeSpec target_type, Location loc)
 592                 {
 593                         ImplicitDelegateCreation d = new ImplicitDelegateCreation (target_type, mge, loc);
 594                         return d.DoResolve (ec);
 595                 }
 596         }
 597
 598         //
 599         // A delegate-creation-expression, invoked from the `New' class
 600         //
 601         public class NewDelegate : DelegateCreation
 602         {
 603                 public Arguments Arguments;
 604
 605                 //
 606                 // This constructor is invoked from the `New' expression
 607                 //
 608                 public NewDelegate (TypeSpec type, Arguments Arguments, Location loc)
 609                 {
 610                         this.type = type;
 611                         this.Arguments = Arguments;
 612                         this.loc  = loc;
 613                 }
 614
 615                 protected override Expression DoResolve (ResolveContext ec)
 616                 {
 617                         if (Arguments == null || Arguments.Count != 1) {
 618                                 ec.Report.Error (149, loc, "Method name expected");
 619                                 return null;
 620                         }
 621
 622                         Argument a = Arguments [0];
 623                         if (!a.ResolveMethodGroup (ec))
 624                                 return null;
 625
 626                         Expression e = a.Expr;
 627
 628                         AnonymousMethodExpression ame = e as AnonymousMethodExpression;
 629                         if (ame != null && RootContext.Version != LanguageVersion.ISO_1) {
 630                                 e = ame.Compatible (ec, type);
 631                                 if (e == null)
 632                                         return null;
 633
 634                                 return e.Resolve (ec);
 635                         }
 636
 637                         method_group = e as MethodGroupExpr;
 638                         if (method_group == null) {
 639                                 if (e.Type == InternalType.Dynamic) {
 640                                         e = Convert.ImplicitConversionRequired (ec, e, type, loc);
 641                                 } else if (!e.Type.IsDelegate) {
 642                                         e.Error_UnexpectedKind (ec, ResolveFlags.MethodGroup | ResolveFlags.Type, loc);
 643                                         return null;
 644                                 }
 645
 646                                 //
 647                                 // An argument is not a method but another delegate
 648                                 //
 649                                 method_group = new MethodGroupExpr (Delegate.GetInvokeMethod (ec.Compiler, e.Type), e.Type, loc);
 650                                 method_group.InstanceExpression = e;
 651                         }
 652
 653                         return base.DoResolve (ec);
 654                 }
 655         }
 656
 657         //
 658         // Invocation converted to delegate Invoke call
 659         //
 660         class DelegateInvocation : ExpressionStatement
 661         {
 662                 readonly Expression InstanceExpr;
 663                 Arguments arguments;
 664                 MethodSpec method;
 665
 666                 public DelegateInvocation (Expression instance_expr, Arguments args, Location loc)
 667                 {
 668                         this.InstanceExpr = instance_expr;
 669                         this.arguments = args;
 670                         this.loc = loc;
 671                 }
 672
 673                 public override Expression CreateExpressionTree (ResolveContext ec)
 674                 {
 675                         Arguments args = Arguments.CreateForExpressionTree (ec, this.arguments,
 676                                 InstanceExpr.CreateExpressionTree (ec));
 677
 678                         return CreateExpressionFactoryCall (ec, "Invoke", args);
 679                 }
 680
 681                 protected override Expression DoResolve (ResolveContext ec)
 682                 {
 683                         if (InstanceExpr is EventExpr) {
 684                                 ((EventExpr) InstanceExpr).Error_CannotAssign (ec);
 685                                 return null;
 686                         }
 687
 688                         TypeSpec del_type = InstanceExpr.Type;
 689                         if (del_type == null)
 690                                 return null;
 691
 692                         //
 693                         // Do only core overload resolution the rest of the checks has been
 694                         // done on primary expression
 695                         //
 696                         method = Delegate.GetInvokeMethod (ec.Compiler, del_type);
 697                         var res = new OverloadResolver (new MemberSpec[] { method }, OverloadResolver.Restrictions.DelegateInvoke, loc);
 698                         var valid = res.ResolveMember<MethodSpec> (ec, ref arguments);
 699                         if (valid == null && !res.BestCandidateIsDynamic)
 700                                 return null;
 701
 702                         type = method.ReturnType;
 703                         eclass = ExprClass.Value;
 704                         return this;
 705                 }
 706
 707                 public override void Emit (EmitContext ec)
 708                 {
 709                         //
 710                         // Invocation on delegates call the virtual Invoke member
 711                         // so we are always `instance' calls
 712                         //
 713                         Invocation.EmitCall (ec, InstanceExpr, method, arguments, loc);
 714                 }
 715
 716                 public override void EmitStatement (EmitContext ec)
 717                 {
 718                         Emit (ec);
 719                         //
 720                         // Pop the return value if there is one
 721                         //
 722                         if (type != TypeManager.void_type)
 723                                 ec.Emit (OpCodes.Pop);
 724                 }
 725
 726                 public override System.Linq.Expressions.Expression MakeExpression (BuilderContext ctx)
 727                 {
 728                         return Invocation.MakeExpression (ctx, InstanceExpr, method, arguments);
 729                 }
 730         }
 731 }