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 // Copyright 2011 Xamarin Inc
  14 //
  15
  16 using System;
  17
  18 #if STATIC
  19 using IKVM.Reflection;
  20 using IKVM.Reflection.Emit;
  21 #else
  22 using System.Reflection;
  23 using System.Reflection.Emit;
  24 #endif
  25
  26 namespace Mono.CSharp {
  27
  28         //
  29         // Delegate container implementation
  30         //
  31         public class Delegate : TypeDefinition, IParametersMember
  32         {
  33                 FullNamedExpression ReturnType;
  34                 readonly ParametersCompiled parameters;
  35
  36                 Constructor Constructor;
  37                 Method InvokeBuilder;
  38                 Method BeginInvokeBuilder;
  39                 Method EndInvokeBuilder;
  40
  41                 static readonly string[] attribute_targets = new string [] { "type", "return" };
  42
  43                 public static readonly string InvokeMethodName = "Invoke";
  44
  45                 Expression instance_expr;
  46                 ReturnParameter return_attributes;
  47
  48                 const Modifiers MethodModifiers = Modifiers.PUBLIC | Modifiers.VIRTUAL;
  49
  50                 const Modifiers AllowedModifiers =
  51                         Modifiers.NEW |
  52                         Modifiers.PUBLIC |
  53                         Modifiers.PROTECTED |
  54                         Modifiers.INTERNAL |
  55                         Modifiers.UNSAFE |
  56                         Modifiers.PRIVATE;
  57
  58                 public Delegate (TypeContainer parent, FullNamedExpression type, Modifiers mod_flags, MemberName name, ParametersCompiled param_list,
  59                                  Attributes attrs)
  60                         : base (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
  84                 public FullNamedExpression TypExpression {
  85                         get {
  86                                 return ReturnType;
  87                         }
  88                 }
  89
  90                 #endregion
  91
  92                 public override void Accept (StructuralVisitor visitor)
  93                 {
  94                         visitor.Visit (this);
  95                 }
  96
  97                 public override void ApplyAttributeBuilder (Attribute a, MethodSpec ctor, byte[] cdata, PredefinedAttributes pa)
  98                 {
  99                         if (a.Target == AttributeTargets.ReturnValue) {
 100                                 if (return_attributes == null)
 101                                         return_attributes = new ReturnParameter (this, InvokeBuilder.MethodBuilder, Location);
 102
 103                                 return_attributes.ApplyAttributeBuilder (a, ctor, cdata, pa);
 104                                 return;
 105                         }
 106
 107                         base.ApplyAttributeBuilder (a, ctor, cdata, pa);
 108                 }
 109
 110                 public override AttributeTargets AttributeTargets {
 111                         get {
 112                                 return AttributeTargets.Delegate;
 113                         }
 114                 }
 115
 116                 protected override bool DoDefineMembers ()
 117                 {
 118                         var builtin_types = Compiler.BuiltinTypes;
 119
 120                         var ctor_parameters = ParametersCompiled.CreateFullyResolved (
 121                                 new [] {
 122                                         new Parameter (new TypeExpression (builtin_types.Object, Location), "object", Parameter.Modifier.NONE, null, Location),
 123                                         new Parameter (new TypeExpression (builtin_types.IntPtr, Location), "method", Parameter.Modifier.NONE, null, Location)
 124                                 },
 125                                 new [] {
 126                                         builtin_types.Object,
 127                                         builtin_types.IntPtr
 128                                 }
 129                         );
 130
 131                         Constructor = new Constructor (this, Constructor.ConstructorName,
 132                                 Modifiers.PUBLIC, null, ctor_parameters, Location);
 133                         Constructor.Define ();
 134
 135                         //
 136                         // Here the various methods like Invoke, BeginInvoke etc are defined
 137                         //
 138                         // First, call the `out of band' special method for
 139                         // defining recursively any types we need:
 140                         //
 141                         var p = parameters;
 142
 143                         if (!p.Resolve (this))
 144                                 return false;
 145
 146                         //
 147                         // Invoke method
 148                         //
 149
 150                         // Check accessibility
 151                         foreach (var partype in p.Types) {
 152                                 if (!IsAccessibleAs (partype)) {
 153                                         Report.SymbolRelatedToPreviousError (partype);
 154                                         Report.Error (59, Location,
 155                                                 "Inconsistent accessibility: parameter type `{0}' is less accessible than delegate `{1}'",
 156                                                 TypeManager.CSharpName (partype), GetSignatureForError ());
 157                                 }
 158                         }
 159
 160                         var ret_type = ReturnType.ResolveAsType (this);
 161                         if (ret_type == null)
 162                                 return false;
 163
 164                         //
 165                         // We don't have to check any others because they are all
 166                         // guaranteed to be accessible - they are standard types.
 167                         //
 168                         if (!IsAccessibleAs (ret_type)) {
 169                                 Report.SymbolRelatedToPreviousError (ret_type);
 170                                 Report.Error (58, Location,
 171                                                   "Inconsistent accessibility: return type `" +
 172                                                   TypeManager.CSharpName (ret_type) + "' is less " +
 173                                                   "accessible than delegate `" + GetSignatureForError () + "'");
 174                                 return false;
 175                         }
 176
 177                         CheckProtectedModifier ();
 178
 179                         if (Compiler.Settings.StdLib && ret_type.IsSpecialRuntimeType) {
 180                                 Method.Error1599 (Location, ret_type, Report);
 181                                 return false;
 182                         }
 183
 184                         TypeManager.CheckTypeVariance (ret_type, Variance.Covariant, this);
 185
 186                         var resolved_rt = new TypeExpression (ret_type, Location);
 187                         InvokeBuilder = new Method (this, resolved_rt, MethodModifiers, new MemberName (InvokeMethodName), p, null);
 188                         InvokeBuilder.Define ();
 189
 190                         //
 191                         // Don't emit async method for compiler generated delegates (e.g. dynamic site containers)
 192                         //
 193                         if (!IsCompilerGenerated) {
 194                                 DefineAsyncMethods (Parameters.CallingConvention, resolved_rt);
 195                         }
 196
 197                         return true;
 198                 }
 199
 200                 void DefineAsyncMethods (CallingConventions cc, TypeExpression returnType)
 201                 {
 202                         var iasync_result = Module.PredefinedTypes.IAsyncResult;
 203                         var async_callback = Module.PredefinedTypes.AsyncCallback;
 204
 205                         //
 206                         // It's ok when async types don't exist, the delegate will have Invoke method only
 207                         //
 208                         if (!iasync_result.Define () || !async_callback.Define ())
 209                                 return;
 210
 211                         //
 212                         // BeginInvoke
 213                         //
 214                         ParametersCompiled async_parameters;
 215                         if (Parameters.Count == 0) {
 216                                 async_parameters = ParametersCompiled.EmptyReadOnlyParameters;
 217                         } else {
 218                                 var compiled = new Parameter[Parameters.Count];
 219                                 for (int i = 0; i < compiled.Length; ++i) {
 220                                         var p = parameters[i];
 221                                         compiled[i] = new Parameter (new TypeExpression (parameters.Types[i], Location),
 222                                                 p.Name,
 223                                                 p.ModFlags & Parameter.Modifier.RefOutMask,
 224                                                 p.OptAttributes == null ? null : p.OptAttributes.Clone (), Location);
 225                                 }
 226
 227                                 async_parameters = new ParametersCompiled (compiled);
 228                         }
 229
 230                         async_parameters = ParametersCompiled.MergeGenerated (Compiler, async_parameters, false,
 231                                 new Parameter[] {
 232                                         new Parameter (new TypeExpression (async_callback.TypeSpec, Location), "callback", Parameter.Modifier.NONE, null, Location),
 233                                         new Parameter (new TypeExpression (Compiler.BuiltinTypes.Object, Location), "object", Parameter.Modifier.NONE, null, Location)
 234                                 },
 235                                 new [] {
 236                                         async_callback.TypeSpec,
 237                                         Compiler.BuiltinTypes.Object
 238                                 }
 239                         );
 240
 241                         BeginInvokeBuilder = new Method (this,
 242                                 new TypeExpression (iasync_result.TypeSpec, Location), MethodModifiers,
 243                                 new MemberName ("BeginInvoke"), async_parameters, null);
 244                         BeginInvokeBuilder.Define ();
 245
 246                         //
 247                         // EndInvoke is a bit more interesting, all the parameters labeled as
 248                         // out or ref have to be duplicated here.
 249                         //
 250
 251                         //
 252                         // Define parameters, and count out/ref parameters
 253                         //
 254                         ParametersCompiled end_parameters;
 255                         int out_params = 0;
 256
 257                         foreach (Parameter p in Parameters.FixedParameters) {
 258                                 if ((p.ModFlags & Parameter.Modifier.RefOutMask) != 0)
 259                                         ++out_params;
 260                         }
 261
 262                         if (out_params > 0) {
 263                                 Parameter[] end_params = new Parameter[out_params];
 264
 265                                 int param = 0;
 266                                 for (int i = 0; i < Parameters.FixedParameters.Length; ++i) {
 267                                         Parameter p = parameters [i];
 268                                         if ((p.ModFlags & Parameter.Modifier.RefOutMask) == 0)
 269                                                 continue;
 270
 271                                         end_params [param++] = new Parameter (new TypeExpression (p.Type, Location),
 272                                                 p.Name,
 273                                                 p.ModFlags & Parameter.Modifier.RefOutMask,
 274                                                 p.OptAttributes == null ? null : p.OptAttributes.Clone (), Location);
 275                                 }
 276
 277                                 end_parameters = new ParametersCompiled (end_params);
 278                         } else {
 279                                 end_parameters = ParametersCompiled.EmptyReadOnlyParameters;
 280                         }
 281
 282                         end_parameters = ParametersCompiled.MergeGenerated (Compiler, end_parameters, false,
 283                                 new Parameter (
 284                                         new TypeExpression (iasync_result.TypeSpec, Location),
 285                                         "result", Parameter.Modifier.NONE, null, Location),
 286                                 iasync_result.TypeSpec);
 287
 288                         //
 289                         // Create method, define parameters, register parameters with type system
 290                         //
 291                         EndInvokeBuilder = new Method (this, returnType, MethodModifiers, new MemberName ("EndInvoke"), end_parameters, null);
 292                         EndInvokeBuilder.Define ();
 293                 }
 294
 295                 public override void PrepareEmit ()
 296                 {
 297                         if (!Parameters.IsEmpty) {
 298                                 parameters.ResolveDefaultValues (this);
 299                         }
 300                 }
 301
 302                 public override void Emit ()
 303                 {
 304                         base.Emit ();
 305
 306                         if (ReturnType.Type != null) {
 307                                 if (ReturnType.Type.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
 308                                         return_attributes = new ReturnParameter (this, InvokeBuilder.MethodBuilder, Location);
 309                                         Module.PredefinedAttributes.Dynamic.EmitAttribute (return_attributes.Builder);
 310                                 } else if (ReturnType.Type.HasDynamicElement) {
 311                                         return_attributes = new ReturnParameter (this, InvokeBuilder.MethodBuilder, Location);
 312                                         Module.PredefinedAttributes.Dynamic.EmitAttribute (return_attributes.Builder, ReturnType.Type, Location);
 313                                 }
 314
 315                                 ConstraintChecker.Check (this, ReturnType.Type, ReturnType.Location);
 316                         }
 317
 318                         Constructor.ParameterInfo.ApplyAttributes (this, Constructor.ConstructorBuilder);
 319                         Constructor.ConstructorBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 320
 321                         parameters.CheckConstraints (this);
 322                         parameters.ApplyAttributes (this, InvokeBuilder.MethodBuilder);
 323                         InvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 324
 325                         if (BeginInvokeBuilder != null) {
 326                                 BeginInvokeBuilder.ParameterInfo.ApplyAttributes (this, BeginInvokeBuilder.MethodBuilder);
 327                                 EndInvokeBuilder.ParameterInfo.ApplyAttributes (this, EndInvokeBuilder.MethodBuilder);
 328
 329                                 BeginInvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 330                                 EndInvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 331                         }
 332                 }
 333
 334                 protected override TypeSpec[] ResolveBaseTypes (out FullNamedExpression base_class)
 335                 {
 336                         base_type = Compiler.BuiltinTypes.MulticastDelegate;
 337                         base_class = null;
 338                         return null;
 339                 }
 340
 341                 protected override TypeAttributes TypeAttr {
 342                         get {
 343                                 return base.TypeAttr | TypeAttributes.Class | TypeAttributes.Sealed;
 344                         }
 345                 }
 346
 347                 public override string[] ValidAttributeTargets {
 348                         get {
 349                                 return attribute_targets;
 350                         }
 351                 }
 352
 353                 //TODO: duplicate
 354                 protected override bool VerifyClsCompliance ()
 355                 {
 356                         if (!base.VerifyClsCompliance ()) {
 357                                 return false;
 358                         }
 359
 360                         parameters.VerifyClsCompliance (this);
 361
 362                         if (!InvokeBuilder.MemberType.IsCLSCompliant ()) {
 363                                 Report.Warning (3002, 1, Location, "Return type of `{0}' is not CLS-compliant",
 364                                         GetSignatureForError ());
 365                         }
 366                         return true;
 367                 }
 368
 369
 370                 public static MethodSpec GetConstructor (TypeSpec delType)
 371                 {
 372                         var ctor = MemberCache.FindMember (delType, MemberFilter.Constructor (null), BindingRestriction.DeclaredOnly);
 373                         return (MethodSpec) ctor;
 374                 }
 375
 376                 //
 377                 // Returns the "Invoke" from a delegate type
 378                 //
 379                 public static MethodSpec GetInvokeMethod (TypeSpec delType)
 380                 {
 381                         var invoke = MemberCache.FindMember (delType,
 382                                 MemberFilter.Method (InvokeMethodName, 0, null, null),
 383                                 BindingRestriction.DeclaredOnly);
 384
 385                         return (MethodSpec) invoke;
 386                 }
 387
 388                 public static AParametersCollection GetParameters (TypeSpec delType)
 389                 {
 390                         var invoke_mb = GetInvokeMethod (delType);
 391                         return invoke_mb.Parameters;
 392                 }
 393
 394                 //
 395                 // 15.2 Delegate compatibility
 396                 //
 397                 public static bool IsTypeCovariant (ResolveContext rc, TypeSpec a, TypeSpec b)
 398                 {
 399                         //
 400                         // For each value parameter (a parameter with no ref or out modifier), an
 401                         // identity conversion or implicit reference conversion exists from the
 402                         // parameter type in D to the corresponding parameter type in M
 403                         //
 404                         if (a == b)
 405                                 return true;
 406
 407                         if (rc.Module.Compiler.Settings.Version == LanguageVersion.ISO_1)
 408                                 return false;
 409
 410                         if (a.IsGenericParameter && b.IsGenericParameter)
 411                                 return a == b;
 412
 413                         return Convert.ImplicitReferenceConversionExists (a, b);
 414                 }
 415
 416                 public static string FullDelegateDesc (MethodSpec invoke_method)
 417                 {
 418                         return TypeManager.GetFullNameSignature (invoke_method).Replace (".Invoke", "");
 419                 }
 420
 421                 public Expression InstanceExpression {
 422                         get {
 423                                 return instance_expr;
 424                         }
 425                         set {
 426                                 instance_expr = value;
 427                         }
 428                 }
 429         }
 430
 431         //
 432         // Base class for `NewDelegate' and `ImplicitDelegateCreation'
 433         //
 434         public abstract class DelegateCreation : Expression, OverloadResolver.IErrorHandler
 435         {
 436                 protected MethodSpec constructor_method;
 437                 protected MethodGroupExpr method_group;
 438
 439                 public override bool ContainsEmitWithAwait ()
 440                 {
 441                         return false;
 442                 }
 443
 444                 public static Arguments CreateDelegateMethodArguments (AParametersCollection pd, TypeSpec[] types, Location loc)
 445                 {
 446                         Arguments delegate_arguments = new Arguments (pd.Count);
 447                         for (int i = 0; i < pd.Count; ++i) {
 448                                 Argument.AType atype_modifier;
 449                                 switch (pd.FixedParameters [i].ModFlags) {
 450                                 case Parameter.Modifier.REF:
 451                                         atype_modifier = Argument.AType.Ref;
 452                                         break;
 453                                 case Parameter.Modifier.OUT:
 454                                         atype_modifier = Argument.AType.Out;
 455                                         break;
 456                                 default:
 457                                         atype_modifier = 0;
 458                                         break;
 459                                 }
 460
 461                                 delegate_arguments.Add (new Argument (new TypeExpression (types [i], loc), atype_modifier));
 462                         }
 463
 464                         return delegate_arguments;
 465                 }
 466
 467                 public override Expression CreateExpressionTree (ResolveContext ec)
 468                 {
 469                         MemberAccess ma = new MemberAccess (new MemberAccess (new QualifiedAliasMember ("global", "System", loc), "Delegate", loc), "CreateDelegate", loc);
 470
 471                         Arguments args = new Arguments (3);
 472                         args.Add (new Argument (new TypeOf (type, loc)));
 473
 474                         if (method_group.InstanceExpression == null)
 475                                 args.Add (new Argument (new NullLiteral (loc)));
 476                         else
 477                                 args.Add (new Argument (method_group.InstanceExpression));
 478
 479                         args.Add (new Argument (method_group.CreateExpressionTree (ec)));
 480                         Expression e = new Invocation (ma, args).Resolve (ec);
 481                         if (e == null)
 482                                 return null;
 483
 484                         e = Convert.ExplicitConversion (ec, e, type, loc);
 485                         if (e == null)
 486                                 return null;
 487
 488                         return e.CreateExpressionTree (ec);
 489                 }
 490
 491                 protected override Expression DoResolve (ResolveContext ec)
 492                 {
 493                         constructor_method = Delegate.GetConstructor (type);
 494
 495                         var invoke_method = Delegate.GetInvokeMethod (type);
 496
 497                         Arguments arguments = CreateDelegateMethodArguments (invoke_method.Parameters, invoke_method.Parameters.Types, loc);
 498                         method_group = method_group.OverloadResolve (ec, ref arguments, this, OverloadResolver.Restrictions.CovariantDelegate);
 499                         if (method_group == null)
 500                                 return null;
 501
 502                         var delegate_method = method_group.BestCandidate;
 503
 504                         if (delegate_method.DeclaringType.IsNullableType) {
 505                                 ec.Report.Error (1728, loc, "Cannot create delegate from method `{0}' because it is a member of System.Nullable<T> type",
 506                                         delegate_method.GetSignatureForError ());
 507                                 return null;
 508                         }
 509
 510                         Invocation.IsSpecialMethodInvocation (ec, delegate_method, loc);
 511
 512                         ExtensionMethodGroupExpr emg = method_group as ExtensionMethodGroupExpr;
 513                         if (emg != null) {
 514                                 method_group.InstanceExpression = emg.ExtensionExpression;
 515                                 TypeSpec e_type = emg.ExtensionExpression.Type;
 516                                 if (TypeSpec.IsValueType (e_type)) {
 517                                         ec.Report.Error (1113, loc, "Extension method `{0}' of value type `{1}' cannot be used to create delegates",
 518                                                 delegate_method.GetSignatureForError (), TypeManager.CSharpName (e_type));
 519                                 }
 520                         }
 521
 522                         TypeSpec rt = delegate_method.ReturnType;
 523                         if (rt.BuiltinType == BuiltinTypeSpec.Type.Dynamic)
 524                                 rt = ec.BuiltinTypes.Object;
 525
 526                         if (!Delegate.IsTypeCovariant (ec, rt, invoke_method.ReturnType)) {
 527                                 Expression ret_expr = new TypeExpression (delegate_method.ReturnType, loc);
 528                                 Error_ConversionFailed (ec, delegate_method, ret_expr);
 529                         }
 530
 531                         if (delegate_method.IsConditionallyExcluded (ec, loc)) {
 532                                 ec.Report.SymbolRelatedToPreviousError (delegate_method);
 533                                 MethodOrOperator m = delegate_method.MemberDefinition as MethodOrOperator;
 534                                 if (m != null && m.IsPartialDefinition) {
 535                                         ec.Report.Error (762, loc, "Cannot create delegate from partial method declaration `{0}'",
 536                                                 delegate_method.GetSignatureForError ());
 537                                 } else {
 538                                         ec.Report.Error (1618, loc, "Cannot create delegate with `{0}' because it has a Conditional attribute",
 539                                                 TypeManager.CSharpSignature (delegate_method));
 540                                 }
 541                         }
 542
 543                         var expr = method_group.InstanceExpression;
 544                         if (expr != null && (expr.Type.IsGenericParameter || !TypeSpec.IsReferenceType (expr.Type)))
 545                                 method_group.InstanceExpression = new BoxedCast (expr, ec.BuiltinTypes.Object);
 546
 547                         eclass = ExprClass.Value;
 548                         return this;
 549                 }
 550
 551                 public override void Emit (EmitContext ec)
 552                 {
 553                         if (method_group.InstanceExpression == null)
 554                                 ec.EmitNull ();
 555                         else
 556                                 method_group.InstanceExpression.Emit (ec);
 557
 558                         var delegate_method = method_group.BestCandidate;
 559
 560                         // Any delegate must be sealed
 561                         if (!delegate_method.DeclaringType.IsDelegate && delegate_method.IsVirtual && !method_group.IsBase) {
 562                                 ec.Emit (OpCodes.Dup);
 563                                 ec.Emit (OpCodes.Ldvirtftn, delegate_method);
 564                         } else {
 565                                 ec.Emit (OpCodes.Ldftn, delegate_method);
 566                         }
 567
 568                         ec.Emit (OpCodes.Newobj, constructor_method);
 569                 }
 570
 571                 void Error_ConversionFailed (ResolveContext ec, MethodSpec method, Expression return_type)
 572                 {
 573                         var invoke_method = Delegate.GetInvokeMethod (type);
 574                         string member_name = method_group.InstanceExpression != null ?
 575                                 Delegate.FullDelegateDesc (method) :
 576                                 TypeManager.GetFullNameSignature (method);
 577
 578                         ec.Report.SymbolRelatedToPreviousError (type);
 579                         ec.Report.SymbolRelatedToPreviousError (method);
 580                         if (ec.Module.Compiler.Settings.Version == LanguageVersion.ISO_1) {
 581                                 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",
 582                                         TypeManager.CSharpName (method.ReturnType), member_name,
 583                                         TypeManager.CSharpName (invoke_method.ReturnType), Delegate.FullDelegateDesc (invoke_method));
 584                                 return;
 585                         }
 586
 587                         if (return_type == null) {
 588                                 ec.Report.Error (123, loc, "A method or delegate `{0}' parameters do not match delegate `{1}' parameters",
 589                                         member_name, Delegate.FullDelegateDesc (invoke_method));
 590                                 return;
 591                         }
 592
 593                         ec.Report.Error (407, loc, "A method or delegate `{0} {1}' return type does not match delegate `{2} {3}' return type",
 594                                 return_type.GetSignatureForError (), member_name,
 595                                 TypeManager.CSharpName (invoke_method.ReturnType), Delegate.FullDelegateDesc (invoke_method));
 596                 }
 597
 598                 public static bool ImplicitStandardConversionExists (ResolveContext ec, MethodGroupExpr mg, TypeSpec target_type)
 599                 {
 600 //                      if (target_type == TypeManager.delegate_type || target_type == TypeManager.multicast_delegate_type)
 601 //                              return false;
 602
 603                         var invoke = Delegate.GetInvokeMethod (target_type);
 604
 605                         Arguments arguments = CreateDelegateMethodArguments (invoke.Parameters, invoke.Parameters.Types, mg.Location);
 606                         return mg.OverloadResolve (ec, ref arguments, null, OverloadResolver.Restrictions.CovariantDelegate | OverloadResolver.Restrictions.ProbingOnly) != null;
 607                 }
 608
 609                 #region IErrorHandler Members
 610
 611                 bool OverloadResolver.IErrorHandler.AmbiguousCandidates (ResolveContext ec, MemberSpec best, MemberSpec ambiguous)
 612                 {
 613                         return false;
 614                 }
 615
 616                 bool OverloadResolver.IErrorHandler.ArgumentMismatch (ResolveContext rc, MemberSpec best, Argument arg, int index)
 617                 {
 618                         Error_ConversionFailed (rc, best as MethodSpec, null);
 619                         return true;
 620                 }
 621
 622                 bool OverloadResolver.IErrorHandler.NoArgumentMatch (ResolveContext rc, MemberSpec best)
 623                 {
 624                         Error_ConversionFailed (rc, best as MethodSpec, null);
 625                         return true;
 626                 }
 627
 628                 bool OverloadResolver.IErrorHandler.TypeInferenceFailed (ResolveContext rc, MemberSpec best)
 629                 {
 630                         return false;
 631                 }
 632
 633                 #endregion
 634         }
 635
 636         //
 637         // Created from the conversion code
 638         //
 639         public class ImplicitDelegateCreation : DelegateCreation
 640         {
 641                 ImplicitDelegateCreation (TypeSpec t, MethodGroupExpr mg, Location l)
 642                 {
 643                         type = t;
 644                         this.method_group = mg;
 645                         loc = l;
 646                 }
 647
 648                 static public Expression Create (ResolveContext ec, MethodGroupExpr mge,
 649                                                  TypeSpec target_type, Location loc)
 650                 {
 651                         ImplicitDelegateCreation d = new ImplicitDelegateCreation (target_type, mge, loc);
 652                         return d.DoResolve (ec);
 653                 }
 654         }
 655
 656         //
 657         // A delegate-creation-expression, invoked from the `New' class
 658         //
 659         public class NewDelegate : DelegateCreation
 660         {
 661                 public Arguments Arguments;
 662
 663                 //
 664                 // This constructor is invoked from the `New' expression
 665                 //
 666                 public NewDelegate (TypeSpec type, Arguments Arguments, Location loc)
 667                 {
 668                         this.type = type;
 669                         this.Arguments = Arguments;
 670                         this.loc  = loc;
 671                 }
 672
 673                 protected override Expression DoResolve (ResolveContext ec)
 674                 {
 675                         if (Arguments == null || Arguments.Count != 1) {
 676                                 ec.Report.Error (149, loc, "Method name expected");
 677                                 return null;
 678                         }
 679
 680                         Argument a = Arguments [0];
 681                         if (!a.ResolveMethodGroup (ec))
 682                                 return null;
 683
 684                         Expression e = a.Expr;
 685
 686                         AnonymousMethodExpression ame = e as AnonymousMethodExpression;
 687                         if (ame != null && ec.Module.Compiler.Settings.Version != LanguageVersion.ISO_1) {
 688                                 e = ame.Compatible (ec, type);
 689                                 if (e == null)
 690                                         return null;
 691
 692                                 return e.Resolve (ec);
 693                         }
 694
 695                         method_group = e as MethodGroupExpr;
 696                         if (method_group == null) {
 697                                 if (e.Type.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
 698                                         e = Convert.ImplicitConversionRequired (ec, e, type, loc);
 699                                 } else if (!e.Type.IsDelegate) {
 700                                         e.Error_UnexpectedKind (ec, ResolveFlags.MethodGroup | ResolveFlags.Type, loc);
 701                                         return null;
 702                                 }
 703
 704                                 //
 705                                 // An argument is not a method but another delegate
 706                                 //
 707                                 method_group = new MethodGroupExpr (Delegate.GetInvokeMethod (e.Type), e.Type, loc);
 708                                 method_group.InstanceExpression = e;
 709                         }
 710
 711                         return base.DoResolve (ec);
 712                 }
 713         }
 714
 715         //
 716         // Invocation converted to delegate Invoke call
 717         //
 718         class DelegateInvocation : ExpressionStatement
 719         {
 720                 readonly Expression InstanceExpr;
 721                 Arguments arguments;
 722                 MethodSpec method;
 723
 724                 public DelegateInvocation (Expression instance_expr, Arguments args, Location loc)
 725                 {
 726                         this.InstanceExpr = instance_expr;
 727                         this.arguments = args;
 728                         this.loc = loc;
 729                 }
 730
 731                 public override bool ContainsEmitWithAwait ()
 732                 {
 733                         return InstanceExpr.ContainsEmitWithAwait () || (arguments != null && arguments.ContainsEmitWithAwait ());
 734                 }
 735
 736                 public override Expression CreateExpressionTree (ResolveContext ec)
 737                 {
 738                         Arguments args = Arguments.CreateForExpressionTree (ec, this.arguments,
 739                                 InstanceExpr.CreateExpressionTree (ec));
 740
 741                         return CreateExpressionFactoryCall (ec, "Invoke", args);
 742                 }
 743
 744                 protected override Expression DoResolve (ResolveContext ec)
 745                 {
 746                         TypeSpec del_type = InstanceExpr.Type;
 747                         if (del_type == null)
 748                                 return null;
 749
 750                         //
 751                         // Do only core overload resolution the rest of the checks has been
 752                         // done on primary expression
 753                         //
 754                         method = Delegate.GetInvokeMethod (del_type);
 755                         var res = new OverloadResolver (new MemberSpec[] { method }, OverloadResolver.Restrictions.DelegateInvoke, loc);
 756                         var valid = res.ResolveMember<MethodSpec> (ec, ref arguments);
 757                         if (valid == null && !res.BestCandidateIsDynamic)
 758                                 return null;
 759
 760                         type = method.ReturnType;
 761                         eclass = ExprClass.Value;
 762                         return this;
 763                 }
 764
 765                 public override void Emit (EmitContext ec)
 766                 {
 767                         //
 768                         // Invocation on delegates call the virtual Invoke member
 769                         // so we are always `instance' calls
 770                         //
 771                         var call = new CallEmitter ();
 772                         call.InstanceExpression = InstanceExpr;
 773                         call.EmitPredefined (ec, method, arguments);
 774                 }
 775
 776                 public override void EmitStatement (EmitContext ec)
 777                 {
 778                         Emit (ec);
 779                         //
 780                         // Pop the return value if there is one
 781                         //
 782                         if (type.Kind != MemberKind.Void)
 783                                 ec.Emit (OpCodes.Pop);
 784                 }
 785
 786                 public override System.Linq.Expressions.Expression MakeExpression (BuilderContext ctx)
 787                 {
 788                         return Invocation.MakeExpression (ctx, InstanceExpr, method, arguments);
 789                 }
 790         }
 791 }