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                                                 partype.GetSignatureForError (), 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                                                   ret_type.GetSignatureForError () + "' 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                         VarianceDecl.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 (resolved_rt);
 195                         }
 196
 197                         return true;
 198                 }
 199
 200                 void DefineAsyncMethods (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                         InvokeBuilder.PrepareEmit ();
 302                         if (BeginInvokeBuilder != null) {
 303                                 BeginInvokeBuilder.PrepareEmit ();
 304                                 EndInvokeBuilder.PrepareEmit ();
 305                         }
 306                 }
 307
 308                 public override void Emit ()
 309                 {
 310                         base.Emit ();
 311
 312                         if (ReturnType.Type != null) {
 313                                 if (ReturnType.Type.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
 314                                         return_attributes = new ReturnParameter (this, InvokeBuilder.MethodBuilder, Location);
 315                                         Module.PredefinedAttributes.Dynamic.EmitAttribute (return_attributes.Builder);
 316                                 } else if (ReturnType.Type.HasDynamicElement) {
 317                                         return_attributes = new ReturnParameter (this, InvokeBuilder.MethodBuilder, Location);
 318                                         Module.PredefinedAttributes.Dynamic.EmitAttribute (return_attributes.Builder, ReturnType.Type, Location);
 319                                 }
 320
 321                                 ConstraintChecker.Check (this, ReturnType.Type, ReturnType.Location);
 322                         }
 323
 324                         Constructor.ParameterInfo.ApplyAttributes (this, Constructor.ConstructorBuilder);
 325                         Constructor.ConstructorBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 326
 327                         parameters.CheckConstraints (this);
 328                         parameters.ApplyAttributes (this, InvokeBuilder.MethodBuilder);
 329                         InvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 330
 331                         if (BeginInvokeBuilder != null) {
 332                                 BeginInvokeBuilder.ParameterInfo.ApplyAttributes (this, BeginInvokeBuilder.MethodBuilder);
 333                                 EndInvokeBuilder.ParameterInfo.ApplyAttributes (this, EndInvokeBuilder.MethodBuilder);
 334
 335                                 BeginInvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 336                                 EndInvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 337                         }
 338                 }
 339
 340                 protected override TypeSpec[] ResolveBaseTypes (out FullNamedExpression base_class)
 341                 {
 342                         base_type = Compiler.BuiltinTypes.MulticastDelegate;
 343                         base_class = null;
 344                         return null;
 345                 }
 346
 347                 protected override TypeAttributes TypeAttr {
 348                         get {
 349                                 return base.TypeAttr | TypeAttributes.Class | TypeAttributes.Sealed;
 350                         }
 351                 }
 352
 353                 public override string[] ValidAttributeTargets {
 354                         get {
 355                                 return attribute_targets;
 356                         }
 357                 }
 358
 359                 //TODO: duplicate
 360                 protected override bool VerifyClsCompliance ()
 361                 {
 362                         if (!base.VerifyClsCompliance ()) {
 363                                 return false;
 364                         }
 365
 366                         parameters.VerifyClsCompliance (this);
 367
 368                         if (!InvokeBuilder.MemberType.IsCLSCompliant ()) {
 369                                 Report.Warning (3002, 1, Location, "Return type of `{0}' is not CLS-compliant",
 370                                         GetSignatureForError ());
 371                         }
 372                         return true;
 373                 }
 374
 375
 376                 public static MethodSpec GetConstructor (TypeSpec delType)
 377                 {
 378                         var ctor = MemberCache.FindMember (delType, MemberFilter.Constructor (null), BindingRestriction.DeclaredOnly);
 379                         return (MethodSpec) ctor;
 380                 }
 381
 382                 //
 383                 // Returns the "Invoke" from a delegate type
 384                 //
 385                 public static MethodSpec GetInvokeMethod (TypeSpec delType)
 386                 {
 387                         var invoke = MemberCache.FindMember (delType,
 388                                 MemberFilter.Method (InvokeMethodName, 0, null, null),
 389                                 BindingRestriction.DeclaredOnly);
 390
 391                         return (MethodSpec) invoke;
 392                 }
 393
 394                 public static AParametersCollection GetParameters (TypeSpec delType)
 395                 {
 396                         var invoke_mb = GetInvokeMethod (delType);
 397                         return invoke_mb.Parameters;
 398                 }
 399
 400                 //
 401                 // 15.2 Delegate compatibility
 402                 //
 403                 public static bool IsTypeCovariant (ResolveContext rc, TypeSpec a, TypeSpec b)
 404                 {
 405                         //
 406                         // For each value parameter (a parameter with no ref or out modifier), an
 407                         // identity conversion or implicit reference conversion exists from the
 408                         // parameter type in D to the corresponding parameter type in M
 409                         //
 410                         if (a == b)
 411                                 return true;
 412
 413                         if (rc.Module.Compiler.Settings.Version == LanguageVersion.ISO_1)
 414                                 return false;
 415
 416                         if (a.IsGenericParameter && b.IsGenericParameter)
 417                                 return a == b;
 418
 419                         return Convert.ImplicitReferenceConversionExists (a, b);
 420                 }
 421
 422                 public static string FullDelegateDesc (MethodSpec invoke_method)
 423                 {
 424                         return TypeManager.GetFullNameSignature (invoke_method).Replace (".Invoke", "");
 425                 }
 426
 427                 public Expression InstanceExpression {
 428                         get {
 429                                 return instance_expr;
 430                         }
 431                         set {
 432                                 instance_expr = value;
 433                         }
 434                 }
 435         }
 436
 437         //
 438         // Base class for `NewDelegate' and `ImplicitDelegateCreation'
 439         //
 440         public abstract class DelegateCreation : Expression, OverloadResolver.IErrorHandler
 441         {
 442                 protected MethodSpec constructor_method;
 443                 protected MethodGroupExpr method_group;
 444
 445                 public bool AllowSpecialMethodsInvocation { get; set; }
 446
 447                 public override bool ContainsEmitWithAwait ()
 448                 {
 449                         return false;
 450                 }
 451
 452                 public static Arguments CreateDelegateMethodArguments (ResolveContext rc, AParametersCollection pd, TypeSpec[] types, Location loc)
 453                 {
 454                         Arguments delegate_arguments = new Arguments (pd.Count);
 455                         for (int i = 0; i < pd.Count; ++i) {
 456                                 Argument.AType atype_modifier;
 457                                 switch (pd.FixedParameters [i].ModFlags & Parameter.Modifier.RefOutMask) {
 458                                 case Parameter.Modifier.REF:
 459                                         atype_modifier = Argument.AType.Ref;
 460                                         break;
 461                                 case Parameter.Modifier.OUT:
 462                                         atype_modifier = Argument.AType.Out;
 463                                         break;
 464                                 default:
 465                                         atype_modifier = 0;
 466                                         break;
 467                                 }
 468
 469                                 var ptype = types[i];
 470                                 if (ptype.BuiltinType == BuiltinTypeSpec.Type.Dynamic)
 471                                         ptype = rc.BuiltinTypes.Object;
 472
 473                                 delegate_arguments.Add (new Argument (new TypeExpression (ptype, loc), atype_modifier));
 474                         }
 475
 476                         return delegate_arguments;
 477                 }
 478
 479                 public override Expression CreateExpressionTree (ResolveContext ec)
 480                 {
 481                         MemberAccess ma = new MemberAccess (new MemberAccess (new QualifiedAliasMember ("global", "System", loc), "Delegate", loc), "CreateDelegate", loc);
 482
 483                         Arguments args = new Arguments (3);
 484                         args.Add (new Argument (new TypeOf (type, loc)));
 485
 486                         if (method_group.InstanceExpression == null)
 487                                 args.Add (new Argument (new NullLiteral (loc)));
 488                         else
 489                                 args.Add (new Argument (method_group.InstanceExpression));
 490
 491                         args.Add (new Argument (method_group.CreateExpressionTree (ec)));
 492                         Expression e = new Invocation (ma, args).Resolve (ec);
 493                         if (e == null)
 494                                 return null;
 495
 496                         e = Convert.ExplicitConversion (ec, e, type, loc);
 497                         if (e == null)
 498                                 return null;
 499
 500                         return e.CreateExpressionTree (ec);
 501                 }
 502
 503                 protected override Expression DoResolve (ResolveContext ec)
 504                 {
 505                         constructor_method = Delegate.GetConstructor (type);
 506
 507                         var invoke_method = Delegate.GetInvokeMethod (type);
 508
 509                         Arguments arguments = CreateDelegateMethodArguments (ec, invoke_method.Parameters, invoke_method.Parameters.Types, loc);
 510                         method_group = method_group.OverloadResolve (ec, ref arguments, this, OverloadResolver.Restrictions.CovariantDelegate);
 511                         if (method_group == null)
 512                                 return null;
 513
 514                         var delegate_method = method_group.BestCandidate;
 515
 516                         if (delegate_method.DeclaringType.IsNullableType) {
 517                                 ec.Report.Error (1728, loc, "Cannot create delegate from method `{0}' because it is a member of System.Nullable<T> type",
 518                                         delegate_method.GetSignatureForError ());
 519                                 return null;
 520                         }
 521
 522                         if (!AllowSpecialMethodsInvocation)
 523                                 Invocation.IsSpecialMethodInvocation (ec, delegate_method, loc);
 524
 525                         ExtensionMethodGroupExpr emg = method_group as ExtensionMethodGroupExpr;
 526                         if (emg != null) {
 527                                 method_group.InstanceExpression = emg.ExtensionExpression;
 528                                 TypeSpec e_type = emg.ExtensionExpression.Type;
 529                                 if (TypeSpec.IsValueType (e_type)) {
 530                                         ec.Report.Error (1113, loc, "Extension method `{0}' of value type `{1}' cannot be used to create delegates",
 531                                                 delegate_method.GetSignatureForError (), e_type.GetSignatureForError ());
 532                                 }
 533                         }
 534
 535                         TypeSpec rt = method_group.BestCandidateReturnType;
 536                         if (rt.BuiltinType == BuiltinTypeSpec.Type.Dynamic)
 537                                 rt = ec.BuiltinTypes.Object;
 538
 539                         if (!Delegate.IsTypeCovariant (ec, rt, invoke_method.ReturnType)) {
 540                                 Expression ret_expr = new TypeExpression (delegate_method.ReturnType, loc);
 541                                 Error_ConversionFailed (ec, delegate_method, ret_expr);
 542                         }
 543
 544                         if (method_group.IsConditionallyExcluded) {
 545                                 ec.Report.SymbolRelatedToPreviousError (delegate_method);
 546                                 MethodOrOperator m = delegate_method.MemberDefinition as MethodOrOperator;
 547                                 if (m != null && m.IsPartialDefinition) {
 548                                         ec.Report.Error (762, loc, "Cannot create delegate from partial method declaration `{0}'",
 549                                                 delegate_method.GetSignatureForError ());
 550                                 } else {
 551                                         ec.Report.Error (1618, loc, "Cannot create delegate with `{0}' because it has a Conditional attribute",
 552                                                 TypeManager.CSharpSignature (delegate_method));
 553                                 }
 554                         }
 555
 556                         var expr = method_group.InstanceExpression;
 557                         if (expr != null && (expr.Type.IsGenericParameter || !TypeSpec.IsReferenceType (expr.Type)))
 558                                 method_group.InstanceExpression = new BoxedCast (expr, ec.BuiltinTypes.Object);
 559
 560                         eclass = ExprClass.Value;
 561                         return this;
 562                 }
 563
 564                 public override void Emit (EmitContext ec)
 565                 {
 566                         if (method_group.InstanceExpression == null)
 567                                 ec.EmitNull ();
 568                         else
 569                                 method_group.InstanceExpression.Emit (ec);
 570
 571                         var delegate_method = method_group.BestCandidate;
 572
 573                         // Any delegate must be sealed
 574                         if (!delegate_method.DeclaringType.IsDelegate && delegate_method.IsVirtual && !method_group.IsBase) {
 575                                 ec.Emit (OpCodes.Dup);
 576                                 ec.Emit (OpCodes.Ldvirtftn, delegate_method);
 577                         } else {
 578                                 ec.Emit (OpCodes.Ldftn, delegate_method);
 579                         }
 580
 581                         ec.Emit (OpCodes.Newobj, constructor_method);
 582                 }
 583
 584                 void Error_ConversionFailed (ResolveContext ec, MethodSpec method, Expression return_type)
 585                 {
 586                         var invoke_method = Delegate.GetInvokeMethod (type);
 587                         string member_name = method_group.InstanceExpression != null ?
 588                                 Delegate.FullDelegateDesc (method) :
 589                                 TypeManager.GetFullNameSignature (method);
 590
 591                         ec.Report.SymbolRelatedToPreviousError (type);
 592                         ec.Report.SymbolRelatedToPreviousError (method);
 593                         if (ec.Module.Compiler.Settings.Version == LanguageVersion.ISO_1) {
 594                                 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",
 595                                         method.ReturnType.GetSignatureForError (), member_name,
 596                                         invoke_method.ReturnType.GetSignatureForError (), Delegate.FullDelegateDesc (invoke_method));
 597                                 return;
 598                         }
 599
 600                         if (return_type == null) {
 601                                 ec.Report.Error (123, loc, "A method or delegate `{0}' parameters do not match delegate `{1}' parameters",
 602                                         member_name, Delegate.FullDelegateDesc (invoke_method));
 603                                 return;
 604                         }
 605
 606                         ec.Report.Error (407, loc, "A method or delegate `{0} {1}' return type does not match delegate `{2} {3}' return type",
 607                                 return_type.GetSignatureForError (), member_name,
 608                                 invoke_method.ReturnType.GetSignatureForError (), Delegate.FullDelegateDesc (invoke_method));
 609                 }
 610
 611                 public static bool ImplicitStandardConversionExists (ResolveContext ec, MethodGroupExpr mg, TypeSpec target_type)
 612                 {
 613 //                      if (target_type == TypeManager.delegate_type || target_type == TypeManager.multicast_delegate_type)
 614 //                              return false;
 615
 616                         var invoke = Delegate.GetInvokeMethod (target_type);
 617
 618                         Arguments arguments = CreateDelegateMethodArguments (ec, invoke.Parameters, invoke.Parameters.Types, mg.Location);
 619                         return mg.OverloadResolve (ec, ref arguments, null, OverloadResolver.Restrictions.CovariantDelegate | OverloadResolver.Restrictions.ProbingOnly) != null;
 620                 }
 621
 622                 #region IErrorHandler Members
 623
 624                 bool OverloadResolver.IErrorHandler.AmbiguousCandidates (ResolveContext ec, MemberSpec best, MemberSpec ambiguous)
 625                 {
 626                         return false;
 627                 }
 628
 629                 bool OverloadResolver.IErrorHandler.ArgumentMismatch (ResolveContext rc, MemberSpec best, Argument arg, int index)
 630                 {
 631                         Error_ConversionFailed (rc, best as MethodSpec, null);
 632                         return true;
 633                 }
 634
 635                 bool OverloadResolver.IErrorHandler.NoArgumentMatch (ResolveContext rc, MemberSpec best)
 636                 {
 637                         Error_ConversionFailed (rc, best as MethodSpec, null);
 638                         return true;
 639                 }
 640
 641                 bool OverloadResolver.IErrorHandler.TypeInferenceFailed (ResolveContext rc, MemberSpec best)
 642                 {
 643                         return false;
 644                 }
 645
 646                 #endregion
 647         }
 648
 649         //
 650         // Created from the conversion code
 651         //
 652         public class ImplicitDelegateCreation : DelegateCreation
 653         {
 654                 Field mg_cache;
 655
 656                 public ImplicitDelegateCreation (TypeSpec delegateType, MethodGroupExpr mg, Location loc)
 657                 {
 658                         type = delegateType;
 659                         this.method_group = mg;
 660                         this.loc = loc;
 661                 }
 662
 663                 //
 664                 // Returns true when type is MVAR or has MVAR reference
 665                 //
 666                 public static bool ContainsMethodTypeParameter (TypeSpec type)
 667                 {
 668                         var tps = type as TypeParameterSpec;
 669                         if (tps != null)
 670                                 return tps.IsMethodOwned;
 671
 672                         var ec = type as ElementTypeSpec;
 673                         if (ec != null)
 674                                 return ContainsMethodTypeParameter (ec.Element);
 675
 676                         foreach (var t in type.TypeArguments) {
 677                                 if (ContainsMethodTypeParameter (t)) {
 678                                         return true;
 679                                 }
 680                         }
 681
 682                         if (type.IsNested)
 683                                 return ContainsMethodTypeParameter (type.DeclaringType);
 684
 685                         return false;
 686                 }
 687
 688                 bool HasMvar ()
 689                 {
 690                         if (ContainsMethodTypeParameter (type))
 691                                 return false;
 692
 693                         var best = method_group.BestCandidate;
 694                         if (ContainsMethodTypeParameter (best.DeclaringType))
 695                                 return false;
 696
 697                         if (best.TypeArguments != null) {
 698                                 foreach (var ta in best.TypeArguments) {
 699                                         if (ContainsMethodTypeParameter (ta))
 700                                                 return false;
 701                                 }
 702                         }
 703
 704                         return true;
 705                 }
 706
 707                 protected override Expression DoResolve (ResolveContext ec)
 708                 {
 709                         var expr = base.DoResolve (ec);
 710                         if (expr == null)
 711                                 return ErrorExpression.Instance;
 712
 713                         if (ec.IsInProbingMode)
 714                                 return expr;
 715
 716                         //
 717                         // Cache any static delegate creation
 718                         //
 719                         if (method_group.InstanceExpression != null)
 720                                 return expr;
 721
 722                         //
 723                         // Cannot easily cache types with MVAR
 724                         //
 725                         if (!HasMvar ())
 726                                 return expr;
 727
 728                         //
 729                         // Create type level cache for a delegate instance
 730                         //
 731                         var parent = ec.CurrentMemberDefinition.Parent.PartialContainer;
 732                         int id = parent.MethodGroupsCounter++;
 733
 734                         mg_cache = new Field (parent, new TypeExpression (type, loc),
 735                                 Modifiers.STATIC | Modifiers.PRIVATE | Modifiers.COMPILER_GENERATED,
 736                                 new MemberName (CompilerGeneratedContainer.MakeName (null, "f", "mg$cache", id), loc), null);
 737                         mg_cache.Define ();
 738                         parent.AddField (mg_cache);
 739
 740                         return expr;
 741                 }
 742
 743                 public override void Emit (EmitContext ec)
 744                 {
 745                         Label l_initialized = ec.DefineLabel ();
 746
 747                         if (mg_cache != null) {
 748                                 ec.Emit (OpCodes.Ldsfld, mg_cache.Spec);
 749                                 ec.Emit (OpCodes.Brtrue_S, l_initialized);
 750                         }
 751
 752                         base.Emit (ec);
 753
 754                         if (mg_cache != null) {
 755                                 ec.Emit (OpCodes.Stsfld, mg_cache.Spec);
 756                                 ec.MarkLabel (l_initialized);
 757                                 ec.Emit (OpCodes.Ldsfld, mg_cache.Spec);
 758                         }
 759                 }
 760         }
 761
 762         //
 763         // A delegate-creation-expression, invoked from the `New' class
 764         //
 765         public class NewDelegate : DelegateCreation
 766         {
 767                 public Arguments Arguments;
 768
 769                 //
 770                 // This constructor is invoked from the `New' expression
 771                 //
 772                 public NewDelegate (TypeSpec type, Arguments Arguments, Location loc)
 773                 {
 774                         this.type = type;
 775                         this.Arguments = Arguments;
 776                         this.loc  = loc;
 777                 }
 778
 779                 protected override Expression DoResolve (ResolveContext ec)
 780                 {
 781                         if (Arguments == null || Arguments.Count != 1) {
 782                                 ec.Report.Error (149, loc, "Method name expected");
 783                                 return null;
 784                         }
 785
 786                         Argument a = Arguments [0];
 787                         if (!a.ResolveMethodGroup (ec))
 788                                 return null;
 789
 790                         Expression e = a.Expr;
 791
 792                         AnonymousMethodExpression ame = e as AnonymousMethodExpression;
 793                         if (ame != null && ec.Module.Compiler.Settings.Version != LanguageVersion.ISO_1) {
 794                                 e = ame.Compatible (ec, type);
 795                                 if (e == null)
 796                                         return null;
 797
 798                                 return e.Resolve (ec);
 799                         }
 800
 801                         method_group = e as MethodGroupExpr;
 802                         if (method_group == null) {
 803                                 if (e.Type.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
 804                                         e = Convert.ImplicitConversionRequired (ec, e, type, loc);
 805                                 } else if (!e.Type.IsDelegate) {
 806                                         e.Error_UnexpectedKind (ec, ResolveFlags.MethodGroup | ResolveFlags.Type, loc);
 807                                         return null;
 808                                 }
 809
 810                                 //
 811                                 // An argument is not a method but another delegate
 812                                 //
 813                                 method_group = new MethodGroupExpr (Delegate.GetInvokeMethod (e.Type), e.Type, loc);
 814                                 method_group.InstanceExpression = e;
 815                         }
 816
 817                         return base.DoResolve (ec);
 818                 }
 819         }
 820
 821         //
 822         // Invocation converted to delegate Invoke call
 823         //
 824         class DelegateInvocation : ExpressionStatement
 825         {
 826                 readonly Expression InstanceExpr;
 827                 Arguments arguments;
 828                 MethodSpec method;
 829
 830                 public DelegateInvocation (Expression instance_expr, Arguments args, Location loc)
 831                 {
 832                         this.InstanceExpr = instance_expr;
 833                         this.arguments = args;
 834                         this.loc = loc;
 835                 }
 836
 837                 public override bool ContainsEmitWithAwait ()
 838                 {
 839                         return InstanceExpr.ContainsEmitWithAwait () || (arguments != null && arguments.ContainsEmitWithAwait ());
 840                 }
 841
 842                 public override Expression CreateExpressionTree (ResolveContext ec)
 843                 {
 844                         Arguments args = Arguments.CreateForExpressionTree (ec, this.arguments,
 845                                 InstanceExpr.CreateExpressionTree (ec));
 846
 847                         return CreateExpressionFactoryCall (ec, "Invoke", args);
 848                 }
 849
 850                 public override void FlowAnalysis (FlowAnalysisContext fc)
 851                 {
 852                         InstanceExpr.FlowAnalysis (fc);
 853                         if (arguments != null)
 854                                 arguments.FlowAnalysis (fc);
 855                 }
 856
 857                 protected override Expression DoResolve (ResolveContext ec)
 858                 {
 859                         TypeSpec del_type = InstanceExpr.Type;
 860                         if (del_type == null)
 861                                 return null;
 862
 863                         //
 864                         // Do only core overload resolution the rest of the checks has been
 865                         // done on primary expression
 866                         //
 867                         method = Delegate.GetInvokeMethod (del_type);
 868                         var res = new OverloadResolver (new MemberSpec[] { method }, OverloadResolver.Restrictions.DelegateInvoke, loc);
 869                         var valid = res.ResolveMember<MethodSpec> (ec, ref arguments);
 870                         if (valid == null && !res.BestCandidateIsDynamic)
 871                                 return null;
 872
 873                         type = method.ReturnType;
 874                         eclass = ExprClass.Value;
 875                         return this;
 876                 }
 877
 878                 public override void Emit (EmitContext ec)
 879                 {
 880                         //
 881                         // Invocation on delegates call the virtual Invoke member
 882                         // so we are always `instance' calls
 883                         //
 884                         var call = new CallEmitter ();
 885                         call.InstanceExpression = InstanceExpr;
 886                         call.EmitPredefined (ec, method, arguments, loc);
 887                 }
 888
 889                 public override void EmitStatement (EmitContext ec)
 890                 {
 891                         Emit (ec);
 892                         //
 893                         // Pop the return value if there is one
 894                         //
 895                         if (type.Kind != MemberKind.Void)
 896                                 ec.Emit (OpCodes.Pop);
 897                 }
 898
 899                 public override System.Linq.Expressions.Expression MakeExpression (BuilderContext ctx)
 900                 {
 901                         return Invocation.MakeExpression (ctx, InstanceExpr, method, arguments);
 902                 }
 903         }
 904 }