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 2003-2008 Novell, Inc (http://www.ximian.com)
  13 //
  14
  15 using System;
  16 using System.Collections;
  17 using System.Reflection;
  18 using System.Reflection.Emit;
  19 using System.Text;
  20
  21 namespace Mono.CSharp {
  22
  23         /// <summary>
  24         ///   Holds Delegates
  25         /// </summary>
  26         public class Delegate : DeclSpace, IMemberContainer
  27         {
  28                 FullNamedExpression ReturnType;
  29                 public ParametersCompiled      Parameters;
  30
  31                 public ConstructorBuilder ConstructorBuilder;
  32                 public MethodBuilder      InvokeBuilder;
  33                 public MethodBuilder      BeginInvokeBuilder;
  34                 public MethodBuilder      EndInvokeBuilder;
  35
  36                 Type ret_type;
  37
  38                 static string[] attribute_targets = new string [] { "type", "return" };
  39
  40                 Expression instance_expr;
  41                 MethodBase delegate_method;
  42                 ReturnParameter return_attributes;
  43
  44                 MemberCache member_cache;
  45
  46                 const MethodAttributes mattr = MethodAttributes.Public | MethodAttributes.HideBySig |
  47                         MethodAttributes.Virtual | MethodAttributes.NewSlot;
  48
  49                 const int AllowedModifiers =
  50                         Modifiers.NEW |
  51                         Modifiers.PUBLIC |
  52                         Modifiers.PROTECTED |
  53                         Modifiers.INTERNAL |
  54                         Modifiers.UNSAFE |
  55                         Modifiers.PRIVATE;
  56
  57                 public Delegate (NamespaceEntry ns, DeclSpace parent, FullNamedExpression type,
  58                                  int mod_flags, MemberName name, ParametersCompiled param_list,
  59                                  Attributes attrs)
  60                         : base (ns, parent, name, attrs)
  61
  62                 {
  63                         this.ReturnType = type;
  64                         ModFlags        = Modifiers.Check (AllowedModifiers, mod_flags,
  65                                                            IsTopLevel ? Modifiers.INTERNAL :
  66                                                            Modifiers.PRIVATE, name.Location);
  67                         Parameters      = param_list;
  68                 }
  69
  70                 public override void ApplyAttributeBuilder (Attribute a, CustomAttributeBuilder cb, PredefinedAttributes pa)
  71                 {
  72                         if (a.Target == AttributeTargets.ReturnValue) {
  73                                 if (return_attributes == null)
  74                                         return_attributes = new ReturnParameter (InvokeBuilder, Location);
  75
  76                                 return_attributes.ApplyAttributeBuilder (a, cb, pa);
  77                                 return;
  78                         }
  79
  80                         base.ApplyAttributeBuilder (a, cb, pa);
  81                 }
  82
  83                 public override TypeBuilder DefineType ()
  84                 {
  85                         if (TypeBuilder != null)
  86                                 return TypeBuilder;
  87
  88                         if (IsTopLevel) {
  89                                 if (TypeManager.NamespaceClash (Name, Location))
  90                                         return null;
  91
  92                                 ModuleBuilder builder = Module.Builder;
  93
  94                                 TypeBuilder = builder.DefineType (
  95                                         Name, TypeAttr, TypeManager.multicast_delegate_type);
  96                         } else {
  97                                 TypeBuilder builder = Parent.TypeBuilder;
  98
  99                                 string name = Name.Substring (1 + Name.LastIndexOf ('.'));
 100                                 TypeBuilder = builder.DefineNestedType (
 101                                         name, TypeAttr, TypeManager.multicast_delegate_type);
 102                         }
 103
 104                         TypeManager.AddUserType (this);
 105
 106 #if GMCS_SOURCE
 107                         if (IsGeneric) {
 108                                 string[] param_names = new string [TypeParameters.Length];
 109                                 for (int i = 0; i < TypeParameters.Length; i++)
 110                                         param_names [i] = TypeParameters [i].Name;
 111
 112                                 GenericTypeParameterBuilder[] gen_params;
 113                                 gen_params = TypeBuilder.DefineGenericParameters (param_names);
 114
 115                                 int offset = CountTypeParameters - CurrentTypeParameters.Length;
 116                                 for (int i = offset; i < gen_params.Length; i++)
 117                                         CurrentTypeParameters [i - offset].Define (gen_params [i]);
 118
 119                                 foreach (TypeParameter type_param in CurrentTypeParameters) {
 120                                         if (!type_param.Resolve (this))
 121                                                 return null;
 122                                 }
 123
 124                                 Expression current = new SimpleName (
 125                                         MemberName.Basename, TypeParameters, Location);
 126                                 current = current.ResolveAsTypeTerminal (this, false);
 127                                 if (current == null)
 128                                         return null;
 129
 130                                 CurrentType = current.Type;
 131                         }
 132 #endif
 133
 134                         return TypeBuilder;
 135                 }
 136
 137                 public override bool Define ()
 138                 {
 139                         if (IsGeneric) {
 140                                 foreach (TypeParameter type_param in TypeParameters) {
 141                                         if (!type_param.Resolve (this))
 142                                                 return false;
 143                                 }
 144
 145                                 foreach (TypeParameter type_param in TypeParameters) {
 146                                         if (!type_param.DefineType (this))
 147                                                 return false;
 148                                 }
 149                         }
 150
 151                         member_cache = new MemberCache (TypeManager.multicast_delegate_type, this);
 152
 153                         // FIXME: POSSIBLY make this static, as it is always constant
 154                         //
 155                         Type [] const_arg_types = new Type [2];
 156                         const_arg_types [0] = TypeManager.object_type;
 157                         const_arg_types [1] = TypeManager.intptr_type;
 158
 159                         const MethodAttributes ctor_mattr = MethodAttributes.RTSpecialName | MethodAttributes.SpecialName |
 160                                 MethodAttributes.HideBySig | MethodAttributes.Public;
 161
 162                         ConstructorBuilder = TypeBuilder.DefineConstructor (ctor_mattr,
 163                                                                             CallingConventions.Standard,
 164                                                                             const_arg_types);
 165
 166                         ConstructorBuilder.DefineParameter (1, ParameterAttributes.None, "object");
 167                         ConstructorBuilder.DefineParameter (2, ParameterAttributes.None, "method");
 168                         //
 169                         // HACK because System.Reflection.Emit is lame
 170                         //
 171                         IParameterData [] fixed_pars = new IParameterData [] {
 172                                 new ParameterData ("object", Parameter.Modifier.NONE),
 173                                 new ParameterData ("method", Parameter.Modifier.NONE)
 174                         };
 175
 176                         AParametersCollection const_parameters = new ParametersImported (
 177                                 fixed_pars,
 178                                 new Type[] { TypeManager.object_type, TypeManager.intptr_type });
 179
 180                         TypeManager.RegisterMethod (ConstructorBuilder, const_parameters);
 181                         member_cache.AddMember (ConstructorBuilder, this);
 182
 183                         ConstructorBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 184
 185                         //
 186                         // Here the various methods like Invoke, BeginInvoke etc are defined
 187                         //
 188                         // First, call the `out of band' special method for
 189                         // defining recursively any types we need:
 190
 191                         if (!Parameters.Resolve (this))
 192                                 return false;
 193
 194                         //
 195                         // Invoke method
 196                         //
 197
 198                         // Check accessibility
 199                         foreach (Type partype in Parameters.Types){
 200                                 if (!IsAccessibleAs (partype)) {
 201                                         Report.SymbolRelatedToPreviousError (partype);
 202                                         Report.Error (59, Location,
 203                                                       "Inconsistent accessibility: parameter type `{0}' is less accessible than delegate `{1}'",
 204                                                       TypeManager.CSharpName (partype),
 205                                                       GetSignatureForError ());
 206                                         return false;
 207                                 }
 208                         }
 209
 210                         ReturnType = ReturnType.ResolveAsTypeTerminal (this, false);
 211                         if (ReturnType == null)
 212                                 return false;
 213
 214                         ret_type = ReturnType.Type;
 215
 216                         if (!IsAccessibleAs (ret_type)) {
 217                                 Report.SymbolRelatedToPreviousError (ret_type);
 218                                 Report.Error (58, Location,
 219                                               "Inconsistent accessibility: return type `" +
 220                                               TypeManager.CSharpName (ret_type) + "' is less " +
 221                                               "accessible than delegate `" + GetSignatureForError () + "'");
 222                                 return false;
 223                         }
 224
 225                         CheckProtectedModifier ();
 226
 227                         if (RootContext.StdLib && TypeManager.IsSpecialType (ret_type)) {
 228                                 Method.Error1599 (Location, ret_type);
 229                                 return false;
 230                         }
 231
 232                         TypeManager.CheckTypeVariance (ret_type, Variance.Covariant, this);
 233
 234                         //
 235                         // We don't have to check any others because they are all
 236                         // guaranteed to be accessible - they are standard types.
 237                         //
 238
 239                         CallingConventions cc = Parameters.CallingConvention;
 240
 241                         InvokeBuilder = TypeBuilder.DefineMethod ("Invoke",
 242                                                                   mattr,
 243                                                                   cc,
 244                                                                   ret_type,
 245                                                                   Parameters.GetEmitTypes ());
 246
 247                         InvokeBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 248
 249                         TypeManager.RegisterMethod (InvokeBuilder, Parameters);
 250                         member_cache.AddMember (InvokeBuilder, this);
 251
 252                         if (TypeManager.iasyncresult_type != null && TypeManager.asynccallback_type != null) {
 253                                 DefineAsyncMethods (cc);
 254                         }
 255
 256                         return true;
 257                 }
 258
 259                 void DefineAsyncMethods (CallingConventions cc)
 260                 {
 261                         //
 262                         // BeginInvoke
 263                         //
 264                         ParametersCompiled async_parameters = ParametersCompiled.MergeGenerated (Parameters, false,
 265                                 new Parameter [] {
 266                                         new Parameter (null, "callback", Parameter.Modifier.NONE, null, Location),
 267                                         new Parameter (null, "object", Parameter.Modifier.NONE, null, Location)
 268                                 },
 269                                 new Type [] {
 270                                         TypeManager.asynccallback_type,
 271                                         TypeManager.object_type
 272                                 }
 273                         );
 274
 275                         BeginInvokeBuilder = TypeBuilder.DefineMethod ("BeginInvoke",
 276                                 mattr, cc, TypeManager.iasyncresult_type, async_parameters.GetEmitTypes ());
 277
 278                         BeginInvokeBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 279                         TypeManager.RegisterMethod (BeginInvokeBuilder, async_parameters);
 280                         member_cache.AddMember (BeginInvokeBuilder, this);
 281
 282                         //
 283                         // EndInvoke is a bit more interesting, all the parameters labeled as
 284                         // out or ref have to be duplicated here.
 285                         //
 286
 287                         //
 288                         // Define parameters, and count out/ref parameters
 289                         //
 290                         ParametersCompiled end_parameters;
 291                         int out_params = 0;
 292
 293                         foreach (Parameter p in Parameters.FixedParameters) {
 294                                 if ((p.ModFlags & Parameter.Modifier.ISBYREF) != 0)
 295                                         ++out_params;
 296                         }
 297
 298                         if (out_params > 0) {
 299                                 Type [] end_param_types = new Type [out_params];
 300                                 Parameter[] end_params = new Parameter [out_params];
 301
 302                                 int param = 0;
 303                                 for (int i = 0; i < Parameters.FixedParameters.Length; ++i) {
 304                                         Parameter p = Parameters [i];
 305                                         if ((p.ModFlags & Parameter.Modifier.ISBYREF) == 0)
 306                                                 continue;
 307
 308                                         end_param_types [param] = Parameters.Types [i];
 309                                         end_params [param] = p;
 310                                         ++param;
 311                                 }
 312                                 end_parameters = ParametersCompiled.CreateFullyResolved (end_params, end_param_types);
 313                         } else {
 314                                 end_parameters = ParametersCompiled.EmptyReadOnlyParameters;
 315                         }
 316
 317                         end_parameters = ParametersCompiled.MergeGenerated (end_parameters, false,
 318                                 new Parameter (null, "result", Parameter.Modifier.NONE, null, Location), TypeManager.iasyncresult_type);
 319
 320                         //
 321                         // Create method, define parameters, register parameters with type system
 322                         //
 323                         EndInvokeBuilder = TypeBuilder.DefineMethod ("EndInvoke", mattr, cc, ret_type, end_parameters.GetEmitTypes ());
 324                         EndInvokeBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 325
 326                         end_parameters.ApplyAttributes (EndInvokeBuilder);
 327                         TypeManager.RegisterMethod (EndInvokeBuilder, end_parameters);
 328                         member_cache.AddMember (EndInvokeBuilder, this);
 329                 }
 330
 331                 public override void Emit ()
 332                 {
 333                         Parameters.ApplyAttributes (InvokeBuilder);
 334
 335                         if (BeginInvokeBuilder != null) {
 336                                 ParametersCompiled p = (ParametersCompiled) TypeManager.GetParameterData (BeginInvokeBuilder);
 337                                 p.ApplyAttributes (BeginInvokeBuilder);
 338                         }
 339
 340                         if (OptAttributes != null) {
 341                                 OptAttributes.Emit ();
 342                         }
 343
 344                         base.Emit ();
 345                 }
 346
 347                 protected override TypeAttributes TypeAttr {
 348                         get {
 349                                 return Modifiers.TypeAttr (ModFlags, IsTopLevel) |
 350                                         TypeAttributes.Class | TypeAttributes.Sealed |
 351                                         base.TypeAttr;
 352                         }
 353                 }
 354
 355                 public override string[] ValidAttributeTargets {
 356                         get {
 357                                 return attribute_targets;
 358                         }
 359                 }
 360
 361                 //TODO: duplicate
 362                 protected override bool VerifyClsCompliance ()
 363                 {
 364                         if (!base.VerifyClsCompliance ()) {
 365                                 return false;
 366                         }
 367
 368                         Parameters.VerifyClsCompliance ();
 369
 370                         if (!AttributeTester.IsClsCompliant (ReturnType.Type)) {
 371                                 Report.Warning (3002, 1, Location, "Return type of `{0}' is not CLS-compliant",
 372                                         GetSignatureForError ());
 373                         }
 374                         return true;
 375                 }
 376
 377
 378                 public static ConstructorInfo GetConstructor (Type container_type, Type delegate_type)
 379                 {
 380                         Type dt = delegate_type;
 381                         Type[] g_args = null;
 382                         if (TypeManager.IsGenericType (delegate_type)) {
 383                                 g_args = TypeManager.GetTypeArguments (delegate_type);
 384                                 delegate_type = TypeManager.DropGenericTypeArguments (delegate_type);
 385                         }
 386
 387                         Delegate d = TypeManager.LookupDelegate (delegate_type);
 388                         if (d != null) {
 389 #if GMCS_SOURCE
 390                                 if (g_args != null)
 391                                         return TypeBuilder.GetConstructor (dt, d.ConstructorBuilder);
 392 #endif
 393                                 return d.ConstructorBuilder;
 394                         }
 395
 396                         Expression ml = Expression.MemberLookup (container_type,
 397                                 null, dt, ConstructorInfo.ConstructorName, MemberTypes.Constructor,
 398                                 BindingFlags.Public | BindingFlags.Instance | BindingFlags.DeclaredOnly, Location.Null);
 399
 400                         MethodGroupExpr mg = ml as MethodGroupExpr;
 401                         if (mg == null) {
 402                                 Report.Error (-100, Location.Null, "Internal error: could not find delegate constructor!");
 403                                 // FIXME: null will cause a crash later
 404                                 return null;
 405                         }
 406
 407                         return (ConstructorInfo) mg.Methods[0];
 408                 }
 409
 410                 //
 411                 // Returns the MethodBase for "Invoke" from a delegate type, this is used
 412                 // to extract the signature of a delegate.
 413                 //
 414                 public static MethodInfo GetInvokeMethod (Type container_type, Type delegate_type)
 415                 {
 416                         Type dt = delegate_type;
 417
 418                         Type[] g_args = null;
 419                         if (TypeManager.IsGenericType (delegate_type)) {
 420                                 g_args = TypeManager.GetTypeArguments (delegate_type);
 421                                 delegate_type = TypeManager.DropGenericTypeArguments (delegate_type);
 422                         }
 423
 424                         Delegate d = TypeManager.LookupDelegate (delegate_type);
 425                         MethodInfo invoke;
 426                         if (d != null) {
 427 #if GMCS_SOURCE
 428                                 if (g_args != null) {
 429                                         invoke = TypeBuilder.GetMethod (dt, d.InvokeBuilder);
 430 #if MS_COMPATIBLE
 431                                         ParametersCompiled p = (ParametersCompiled) d.Parameters.InflateTypes (g_args, g_args);
 432                                         TypeManager.RegisterMethod (invoke, p);
 433 #endif
 434                                         return invoke;
 435                                 }
 436 #endif
 437                                 return d.InvokeBuilder;
 438                         }
 439
 440                         Expression ml = Expression.MemberLookup (container_type, null, dt,
 441                                 "Invoke", Location.Null);
 442
 443                         MethodGroupExpr mg = ml as MethodGroupExpr;
 444                         if (mg == null) {
 445                                 Report.Error (-100, Location.Null, "Internal error: could not find Invoke method!");
 446                                 // FIXME: null will cause a crash later
 447                                 return null;
 448                         }
 449
 450                         invoke = (MethodInfo) mg.Methods[0];
 451 #if MS_COMPATIBLE
 452                         if (g_args != null) {
 453                                 AParametersCollection p = TypeManager.GetParameterData (invoke);
 454                                 p = p.InflateTypes (g_args, g_args);
 455                                 TypeManager.RegisterMethod (invoke, p);
 456                                 return invoke;
 457                         }
 458 #endif
 459
 460                         return invoke;
 461                 }
 462
 463                 //
 464                 // 15.2 Delegate compatibility
 465                 //
 466                 public static bool IsTypeCovariant (Expression a, Type b)
 467                 {
 468                         //
 469                         // For each value parameter (a parameter with no ref or out modifier), an
 470                         // identity conversion or implicit reference conversion exists from the
 471                         // parameter type in D to the corresponding parameter type in M
 472                         //
 473                         if (a.Type == b)
 474                                 return true;
 475
 476                         if (RootContext.Version == LanguageVersion.ISO_1)
 477                                 return false;
 478
 479                         return Convert.ImplicitReferenceConversionExists (a, b);
 480                 }
 481
 482                 // <summary>
 483                 //  Verifies whether the invocation arguments are compatible with the
 484                 //  delegate's target method
 485                 // </summary>
 486                 public static bool VerifyApplicability (EmitContext ec, Type delegate_type, ref Arguments args, Location loc)
 487                 {
 488                         int arg_count;
 489
 490                         if (args == null)
 491                                 arg_count = 0;
 492                         else
 493                                 arg_count = args.Count;
 494
 495                         MethodBase mb = GetInvokeMethod (ec.ContainerType, delegate_type);
 496                         MethodGroupExpr me = new MethodGroupExpr (new MemberInfo [] { mb }, delegate_type, loc);
 497
 498                         AParametersCollection pd = TypeManager.GetParameterData (mb);
 499
 500                         int pd_count = pd.Count;
 501
 502                         bool params_method = pd.HasParams;
 503                         bool is_params_applicable = false;
 504                         bool is_applicable = me.IsApplicable (ec, ref args, arg_count, ref mb, ref is_params_applicable) == 0;
 505                         if (args != null)
 506                                 arg_count = args.Count;
 507
 508                         if (!is_applicable && !params_method && arg_count != pd_count) {
 509                                 Report.Error (1593, loc, "Delegate `{0}' does not take `{1}' arguments",
 510                                         TypeManager.CSharpName (delegate_type), arg_count.ToString ());
 511                                 return false;
 512                         }
 513
 514                         return me.VerifyArgumentsCompat (
 515                                         ec, ref args, arg_count, mb,
 516                                         is_params_applicable || (!is_applicable && params_method),
 517                                         false, loc);
 518                 }
 519
 520                 public static string FullDelegateDesc (MethodBase invoke_method)
 521                 {
 522                         return TypeManager.GetFullNameSignature (invoke_method).Replace (".Invoke", "");
 523                 }
 524
 525                 public override MemberCache MemberCache {
 526                         get {
 527                                 return member_cache;
 528                         }
 529                 }
 530
 531                 public Expression InstanceExpression {
 532                         get {
 533                                 return instance_expr;
 534                         }
 535                         set {
 536                                 instance_expr = value;
 537                         }
 538                 }
 539
 540                 public MethodBase TargetMethod {
 541                         get {
 542                                 return delegate_method;
 543                         }
 544                         set {
 545                                 delegate_method = value;
 546                         }
 547                 }
 548
 549                 public Type TargetReturnType {
 550                         get {
 551                                 return ret_type;
 552                         }
 553                 }
 554
 555                 public override AttributeTargets AttributeTargets {
 556                         get {
 557                                 return AttributeTargets.Delegate;
 558                         }
 559                 }
 560
 561                 //
 562                 //   Represents header string for documentation comment.
 563                 //
 564                 public override string DocCommentHeader {
 565                         get { return "T:"; }
 566                 }
 567
 568                 #region IMemberContainer Members
 569
 570                 string IMemberContainer.Name
 571                 {
 572                         get { throw new NotImplementedException (); }
 573                 }
 574
 575                 Type IMemberContainer.Type
 576                 {
 577                         get { throw new NotImplementedException (); }
 578                 }
 579
 580                 MemberCache IMemberContainer.BaseCache
 581                 {
 582                         get { throw new NotImplementedException (); }
 583                 }
 584
 585                 bool IMemberContainer.IsInterface {
 586                         get {
 587                                 return false;
 588                         }
 589                 }
 590
 591                 MemberList IMemberContainer.GetMembers (MemberTypes mt, BindingFlags bf)
 592                 {
 593                         throw new NotImplementedException ();
 594                 }
 595
 596                 #endregion
 597         }
 598
 599         //
 600         // Base class for `NewDelegate' and `ImplicitDelegateCreation'
 601         //
 602         public abstract class DelegateCreation : Expression, MethodGroupExpr.IErrorHandler
 603         {
 604                 protected ConstructorInfo constructor_method;
 605                 protected MethodInfo delegate_method;
 606                 // We keep this to handle IsBase only
 607                 protected MethodGroupExpr method_group;
 608                 protected Expression delegate_instance_expression;
 609
 610                 // TODO: Should either cache it or use interface to abstract it
 611                 public static Arguments CreateDelegateMethodArguments (AParametersCollection pd, Location loc)
 612                 {
 613                         Arguments delegate_arguments = new Arguments (pd.Count);
 614                         for (int i = 0; i < pd.Count; ++i) {
 615                                 Argument.AType atype_modifier;
 616                                 Type atype = pd.Types [i];
 617                                 switch (pd.FixedParameters [i].ModFlags) {
 618                                 case Parameter.Modifier.REF:
 619                                         atype_modifier = Argument.AType.Ref;
 620                                         //atype = atype.GetElementType ();
 621                                         break;
 622                                 case Parameter.Modifier.OUT:
 623                                         atype_modifier = Argument.AType.Out;
 624                                         //atype = atype.GetElementType ();
 625                                         break;
 626                                 default:
 627                                         atype_modifier = 0;
 628                                         break;
 629                                 }
 630                                 delegate_arguments.Add (new Argument (new TypeExpression (atype, loc), atype_modifier));
 631                         }
 632                         return delegate_arguments;
 633                 }
 634
 635                 public override Expression CreateExpressionTree (EmitContext ec)
 636                 {
 637                         MemberAccess ma = new MemberAccess (new MemberAccess (new QualifiedAliasMember ("global", "System", loc), "Delegate", loc), "CreateDelegate", loc);
 638
 639                         Arguments args = new Arguments (3);
 640                         args.Add (new Argument (new TypeOf (new TypeExpression (type, loc), loc)));
 641                         args.Add (new Argument (new NullLiteral (loc)));
 642                         args.Add (new Argument (new TypeOfMethod (delegate_method, loc)));
 643                         Expression e = new Invocation (ma, args).Resolve (ec);
 644                         if (e == null)
 645                                 return null;
 646
 647                         e = Convert.ExplicitConversion (ec, e, type, loc);
 648                         if (e == null)
 649                                 return null;
 650
 651                         return e.CreateExpressionTree (ec);
 652                 }
 653
 654                 public override Expression DoResolve (EmitContext ec)
 655                 {
 656                         constructor_method = Delegate.GetConstructor (ec.ContainerType, type);
 657
 658                         MethodInfo invoke_method = Delegate.GetInvokeMethod (ec.ContainerType, type);
 659                         method_group.DelegateType = type;
 660                         method_group.CustomErrorHandler = this;
 661
 662                         Arguments arguments = CreateDelegateMethodArguments (TypeManager.GetParameterData (invoke_method), loc);
 663                         method_group = method_group.OverloadResolve (ec, ref arguments, false, loc);
 664                         if (method_group == null)
 665                                 return null;
 666
 667                         delegate_method = (MethodInfo) method_group;
 668
 669                         if (TypeManager.IsNullableType (delegate_method.DeclaringType)) {
 670                                 Report.Error (1728, loc, "Cannot create delegate from method `{0}' because it is a member of System.Nullable<T> type",
 671                                         TypeManager.GetFullNameSignature (delegate_method));
 672                                 return null;
 673                         }
 674
 675                         Invocation.IsSpecialMethodInvocation (delegate_method, loc);
 676
 677                         ExtensionMethodGroupExpr emg = method_group as ExtensionMethodGroupExpr;
 678                         if (emg != null) {
 679                                 delegate_instance_expression = emg.ExtensionExpression;
 680                                 Type e_type = delegate_instance_expression.Type;
 681                                 if (TypeManager.IsValueType (e_type)) {
 682                                         Report.Error (1113, loc, "Extension method `{0}' of value type `{1}' cannot be used to create delegates",
 683                                                 TypeManager.CSharpSignature (delegate_method), TypeManager.CSharpName (e_type));
 684                                 }
 685                         }
 686
 687                         Type rt = TypeManager.TypeToCoreType (delegate_method.ReturnType);
 688                         Expression ret_expr = new TypeExpression (rt, loc);
 689                         if (!Delegate.IsTypeCovariant (ret_expr, (TypeManager.TypeToCoreType (invoke_method.ReturnType)))) {
 690                                 Error_ConversionFailed (ec, delegate_method, ret_expr);
 691                         }
 692
 693                         if (Invocation.IsMethodExcluded (delegate_method, loc)) {
 694                                 Report.SymbolRelatedToPreviousError (delegate_method);
 695                                 MethodOrOperator m = TypeManager.GetMethod (delegate_method) as MethodOrOperator;
 696                                 if (m != null && m.IsPartialDefinition) {
 697                                         Report.Error (762, loc, "Cannot create delegate from partial method declaration `{0}'",
 698                                                 TypeManager.CSharpSignature (delegate_method));
 699                                 } else {
 700                                         Report.Error (1618, loc, "Cannot create delegate with `{0}' because it has a Conditional attribute",
 701                                                 TypeManager.CSharpSignature (delegate_method));
 702                                 }
 703                         }
 704
 705                         DoResolveInstanceExpression (ec);
 706                         eclass = ExprClass.Value;
 707                         return this;
 708                 }
 709
 710                 void DoResolveInstanceExpression (EmitContext ec)
 711                 {
 712                         //
 713                         // Argument is another delegate
 714                         //
 715                         if (delegate_instance_expression != null)
 716                                 return;
 717
 718                         Expression instance = method_group.InstanceExpression;
 719                         if (instance != null && instance != EmptyExpression.Null) {
 720                                 delegate_instance_expression = instance;
 721                                 Type instance_type = delegate_instance_expression.Type;
 722                                 if (TypeManager.IsValueType (instance_type) || TypeManager.IsGenericParameter (instance_type)) {
 723                                         delegate_instance_expression = new BoxedCast (
 724                                                 delegate_instance_expression, TypeManager.object_type);
 725                                 }
 726                         } else if (!delegate_method.IsStatic && !ec.IsStatic) {
 727                                 delegate_instance_expression = ec.GetThis (loc);
 728                         }
 729                 }
 730
 731                 public override void Emit (EmitContext ec)
 732                 {
 733                         if (delegate_instance_expression == null)
 734                                 ec.ig.Emit (OpCodes.Ldnull);
 735                         else
 736                                 delegate_instance_expression.Emit (ec);
 737
 738                         if (!delegate_method.DeclaringType.IsSealed && delegate_method.IsVirtual && !method_group.IsBase) {
 739                                 ec.ig.Emit (OpCodes.Dup);
 740                                 ec.ig.Emit (OpCodes.Ldvirtftn, delegate_method);
 741                         } else {
 742                                 ec.ig.Emit (OpCodes.Ldftn, delegate_method);
 743                         }
 744
 745                         ec.ig.Emit (OpCodes.Newobj, constructor_method);
 746                 }
 747
 748                 void Error_ConversionFailed (EmitContext ec, MethodBase method, Expression return_type)
 749                 {
 750                         MethodInfo invoke_method = Delegate.GetInvokeMethod (ec.ContainerType, type);
 751                         string member_name = delegate_instance_expression != null ?
 752                                 Delegate.FullDelegateDesc (method) :
 753                                 TypeManager.GetFullNameSignature (method);
 754
 755                         Report.SymbolRelatedToPreviousError (type);
 756                         Report.SymbolRelatedToPreviousError (method);
 757                         if (RootContext.Version == LanguageVersion.ISO_1) {
 758                                 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",
 759                                         TypeManager.CSharpName (((MethodInfo) method).ReturnType), member_name,
 760                                         TypeManager.CSharpName (invoke_method.ReturnType), Delegate.FullDelegateDesc (invoke_method));
 761                                 return;
 762                         }
 763                         if (return_type == null) {
 764                                 Report.Error (123, loc, "A method or delegate `{0}' parameters do not match delegate `{1}' parameters",
 765                                         member_name, Delegate.FullDelegateDesc (invoke_method));
 766                                 return;
 767                         }
 768
 769                         Report.Error (407, loc, "A method or delegate `{0} {1}' return type does not match delegate `{2} {3}' return type",
 770                                 return_type.GetSignatureForError (), member_name,
 771                                 TypeManager.CSharpName (invoke_method.ReturnType), Delegate.FullDelegateDesc (invoke_method));
 772                 }
 773
 774                 public static bool ImplicitStandardConversionExists (EmitContext ec, MethodGroupExpr mg, Type target_type)
 775                 {
 776                         if (target_type == TypeManager.delegate_type || target_type == TypeManager.multicast_delegate_type)
 777                                 return false;
 778
 779                         mg.DelegateType = target_type;
 780                         MethodInfo invoke = Delegate.GetInvokeMethod (null, target_type);
 781
 782                         Arguments arguments = CreateDelegateMethodArguments (TypeManager.GetParameterData (invoke), mg.Location);
 783                         return mg.OverloadResolve (ec, ref arguments, true, mg.Location) != null;
 784                 }
 785
 786                 public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
 787                 {
 788                         if (delegate_instance_expression != null)
 789                                 delegate_instance_expression.MutateHoistedGenericType (storey);
 790
 791                         delegate_method = storey.MutateGenericMethod (delegate_method);
 792                         constructor_method = storey.MutateConstructor (constructor_method);
 793                 }
 794
 795                 #region IErrorHandler Members
 796
 797                 public bool NoExactMatch (EmitContext ec, MethodBase method)
 798                 {
 799                         if (TypeManager.IsGenericMethod (method))
 800                                 return false;
 801
 802                         Error_ConversionFailed (ec, method, null);
 803                         return true;
 804                 }
 805
 806                 public bool AmbiguousCall (MethodBase ambiguous)
 807                 {
 808                         return false;
 809                 }
 810
 811                 #endregion
 812         }
 813
 814         //
 815         // Created from the conversion code
 816         //
 817         public class ImplicitDelegateCreation : DelegateCreation
 818         {
 819                 ImplicitDelegateCreation (Type t, MethodGroupExpr mg, Location l)
 820                 {
 821                         type = t;
 822                         this.method_group = mg;
 823                         loc = l;
 824                 }
 825
 826                 static public Expression Create (EmitContext ec, MethodGroupExpr mge,
 827                                                  Type target_type, Location loc)
 828                 {
 829                         ImplicitDelegateCreation d = new ImplicitDelegateCreation (target_type, mge, loc);
 830                         return d.DoResolve (ec);
 831                 }
 832         }
 833
 834         //
 835         // A delegate-creation-expression, invoked from the `New' class
 836         //
 837         public class NewDelegate : DelegateCreation
 838         {
 839                 public Arguments Arguments;
 840
 841                 //
 842                 // This constructor is invoked from the `New' expression
 843                 //
 844                 public NewDelegate (Type type, Arguments Arguments, Location loc)
 845                 {
 846                         this.type = type;
 847                         this.Arguments = Arguments;
 848                         this.loc  = loc;
 849                 }
 850
 851                 public override Expression DoResolve (EmitContext ec)
 852                 {
 853                         if (Arguments == null || Arguments.Count != 1) {
 854                                 Error_InvalidDelegateArgument ();
 855                                 return null;
 856                         }
 857
 858                         Argument a = Arguments [0];
 859                         if (!a.ResolveMethodGroup (ec))
 860                                 return null;
 861
 862                         Expression e = a.Expr;
 863
 864                         AnonymousMethodExpression ame = e as AnonymousMethodExpression;
 865                         if (ame != null && RootContext.Version != LanguageVersion.ISO_1) {
 866                                 e = ame.Compatible (ec, type);
 867                                 if (e == null)
 868                                         return null;
 869
 870                                 return e.Resolve (ec);
 871                         }
 872
 873                         method_group = e as MethodGroupExpr;
 874                         if (method_group == null) {
 875                                 if (!TypeManager.IsDelegateType (e.Type)) {
 876                                         e.Error_UnexpectedKind (ResolveFlags.MethodGroup | ResolveFlags.Type, loc);
 877                                         return null;
 878                                 }
 879
 880                                 //
 881                                 // An argument is not a method but another delegate
 882                                 //
 883                                 delegate_instance_expression = e;
 884                                 method_group = new MethodGroupExpr (new MemberInfo [] {
 885                                         Delegate.GetInvokeMethod (ec.ContainerType, e.Type) }, e.Type, loc);
 886                         }
 887
 888                         return base.DoResolve (ec);
 889                 }
 890
 891                 void Error_InvalidDelegateArgument ()
 892                 {
 893                         Report.Error (149, loc, "Method name expected");
 894                 }
 895         }
 896
 897         public class DelegateInvocation : ExpressionStatement {
 898
 899                 readonly Expression InstanceExpr;
 900                 Arguments  Arguments;
 901                 MethodInfo method;
 902
 903                 public DelegateInvocation (Expression instance_expr, Arguments args, Location loc)
 904                 {
 905                         this.InstanceExpr = instance_expr;
 906                         this.Arguments = args;
 907                         this.loc = loc;
 908                 }
 909
 910                 public override Expression CreateExpressionTree (EmitContext ec)
 911                 {
 912                         Arguments args = Arguments.CreateForExpressionTree (ec, Arguments,
 913                                 InstanceExpr.CreateExpressionTree (ec));
 914
 915                         return CreateExpressionFactoryCall ("Invoke", args);
 916                 }
 917
 918                 public override Expression DoResolve (EmitContext ec)
 919                 {
 920                         if (InstanceExpr is EventExpr) {
 921                                 ((EventExpr) InstanceExpr).Error_CannotAssign ();
 922                                 return null;
 923                         }
 924
 925                         Type del_type = InstanceExpr.Type;
 926                         if (del_type == null)
 927                                 return null;
 928
 929                         if (!Delegate.VerifyApplicability (ec, del_type, ref Arguments, loc))
 930                                 return null;
 931
 932                         method = Delegate.GetInvokeMethod (ec.ContainerType, del_type);
 933                         type = TypeManager.TypeToCoreType (method.ReturnType);
 934                         eclass = ExprClass.Value;
 935
 936                         return this;
 937                 }
 938
 939                 public override void Emit (EmitContext ec)
 940                 {
 941                         //
 942                         // Invocation on delegates call the virtual Invoke member
 943                         // so we are always `instance' calls
 944                         //
 945                         Invocation.EmitCall (ec, false, InstanceExpr, method, Arguments, loc);
 946                 }
 947
 948                 public override void EmitStatement (EmitContext ec)
 949                 {
 950                         Emit (ec);
 951                         //
 952                         // Pop the return value if there is one
 953                         //
 954                         if (type != TypeManager.void_type)
 955                                 ec.ig.Emit (OpCodes.Pop);
 956                 }
 957
 958                 public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
 959                 {
 960                         method = storey.MutateGenericMethod (method);
 961                         type = storey.MutateType (type);
 962
 963                         if (Arguments != null)
 964                                 Arguments.MutateHoistedGenericType (storey);
 965
 966                         InstanceExpr.MutateHoistedGenericType (storey);
 967                 }
 968         }
 969 }