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 2003-2008 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 Parameters      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, Parameters 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)
  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);
  77                                 return;
  78                         }
  79
  80                         base.ApplyAttributeBuilder (a, cb);
  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 = CodeGen.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 GMCS_SOURCE
 140                         if (IsGeneric) {
 141                                 foreach (TypeParameter type_param in TypeParameters) {
 142                                         if (!type_param.Resolve (this))
 143                                                 return false;
 144                                 }
 145
 146                                 foreach (TypeParameter type_param in TypeParameters) {
 147                                         if (!type_param.DefineType (this))
 148                                                 return false;
 149                                 }
 150
 151                                 foreach (TypeParameter type_param in TypeParameters) {
 152                                         if (!type_param.CheckDependencies ())
 153                                                 return false;
 154                                 }
 155                         }
 156 #endif
 157                         member_cache = new MemberCache (TypeManager.multicast_delegate_type, this);
 158
 159                         // FIXME: POSSIBLY make this static, as it is always constant
 160                         //
 161                         Type [] const_arg_types = new Type [2];
 162                         const_arg_types [0] = TypeManager.object_type;
 163                         const_arg_types [1] = TypeManager.intptr_type;
 164
 165                         const MethodAttributes ctor_mattr = MethodAttributes.RTSpecialName | MethodAttributes.SpecialName |
 166                                 MethodAttributes.HideBySig | MethodAttributes.Public;
 167
 168                         ConstructorBuilder = TypeBuilder.DefineConstructor (ctor_mattr,
 169                                                                             CallingConventions.Standard,
 170                                                                             const_arg_types);
 171
 172                         ConstructorBuilder.DefineParameter (1, ParameterAttributes.None, "object");
 173                         ConstructorBuilder.DefineParameter (2, ParameterAttributes.None, "method");
 174                         //
 175                         // HACK because System.Reflection.Emit is lame
 176                         //
 177                         Parameter [] fixed_pars = new Parameter [2];
 178                         fixed_pars [0] = new Parameter (TypeManager.object_type, "object",
 179                                                         Parameter.Modifier.NONE, null, Location);
 180                         fixed_pars [1] = new Parameter (TypeManager.intptr_type, "method",
 181                                                         Parameter.Modifier.NONE, null, Location);
 182                         Parameters const_parameters = new Parameters (fixed_pars);
 183                         const_parameters.Resolve (null);
 184
 185                         TypeManager.RegisterMethod (ConstructorBuilder, const_parameters);
 186                         member_cache.AddMember (ConstructorBuilder, this);
 187
 188                         ConstructorBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 189
 190                         //
 191                         // Here the various methods like Invoke, BeginInvoke etc are defined
 192                         //
 193                         // First, call the `out of band' special method for
 194                         // defining recursively any types we need:
 195
 196                         if (!Parameters.Resolve (this))
 197                                 return false;
 198
 199                         //
 200                         // Invoke method
 201                         //
 202
 203                         // Check accessibility
 204                         foreach (Type partype in Parameters.Types){
 205                                 if (!IsAccessibleAs (partype)) {
 206                                         Report.SymbolRelatedToPreviousError (partype);
 207                                         Report.Error (59, Location,
 208                                                       "Inconsistent accessibility: parameter type `" +
 209                                                       TypeManager.CSharpName (partype) + "' is less " +
 210                                                           "accessible than delegate `" + GetSignatureForError () + "'");
 211                                         return false;
 212                                 }
 213                         }
 214
 215                         ReturnType = ReturnType.ResolveAsTypeTerminal (this, false);
 216                         if (ReturnType == null)
 217                                 return false;
 218
 219                         ret_type = ReturnType.Type;
 220
 221                         if (!IsAccessibleAs (ret_type)) {
 222                                 Report.SymbolRelatedToPreviousError (ret_type);
 223                                 Report.Error (58, Location,
 224                                               "Inconsistent accessibility: return type `" +
 225                                               TypeManager.CSharpName (ret_type) + "' is less " +
 226                                               "accessible than delegate `" + GetSignatureForError () + "'");
 227                                 return false;
 228                         }
 229
 230                         CheckProtectedModifier ();
 231
 232                         if (RootContext.StdLib && (ret_type == TypeManager.arg_iterator_type || ret_type == TypeManager.typed_reference_type)) {
 233                                 Method.Error1599 (Location, ret_type);
 234                                 return false;
 235                         }
 236
 237                         //
 238                         // We don't have to check any others because they are all
 239                         // guaranteed to be accessible - they are standard types.
 240                         //
 241
 242                         CallingConventions cc = Parameters.CallingConvention;
 243
 244                         InvokeBuilder = TypeBuilder.DefineMethod ("Invoke",
 245                                                                   mattr,
 246                                                                   cc,
 247                                                                   ret_type,
 248                                                                   Parameters.Types);
 249
 250                         InvokeBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 251
 252                         TypeManager.RegisterMethod (InvokeBuilder, Parameters);
 253                         member_cache.AddMember (InvokeBuilder, this);
 254
 255                         if (TypeManager.iasyncresult_type != null && TypeManager.asynccallback_type != null) {
 256                                 DefineAsyncMethods (cc);
 257                         }
 258
 259                         return true;
 260                 }
 261
 262                 void DefineAsyncMethods (CallingConventions cc)
 263                 {
 264                         //
 265                         // BeginInvoke
 266                         //
 267                         Parameters async_parameters = Parameters.MergeGenerated (Parameters,
 268                                 new Parameter (TypeManager.asynccallback_type, "callback", Parameter.Modifier.NONE, null, Location),
 269                                 new Parameter (TypeManager.object_type, "object", Parameter.Modifier.NONE, null, Location));
 270
 271                         BeginInvokeBuilder = TypeBuilder.DefineMethod ("BeginInvoke",
 272                                 mattr, cc, TypeManager.iasyncresult_type, async_parameters.Types);
 273
 274                         BeginInvokeBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 275                         TypeManager.RegisterMethod (BeginInvokeBuilder, async_parameters);
 276                         member_cache.AddMember (BeginInvokeBuilder, this);
 277
 278                         //
 279                         // EndInvoke is a bit more interesting, all the parameters labeled as
 280                         // out or ref have to be duplicated here.
 281                         //
 282
 283                         //
 284                         // Define parameters, and count out/ref parameters
 285                         //
 286                         Parameters end_parameters;
 287                         int out_params = 0;
 288
 289                         foreach (Parameter p in Parameters.FixedParameters) {
 290                                 if ((p.ModFlags & Parameter.Modifier.ISBYREF) != 0)
 291                                         ++out_params;
 292                         }
 293
 294                         if (out_params > 0) {
 295                                 Type [] end_param_types = new Type [out_params];
 296                                 Parameter [] end_params = new Parameter [out_params];
 297
 298                                 int param = 0;
 299                                 for (int i = 0; i < Parameters.FixedParameters.Length; ++i) {
 300                                         Parameter p = Parameters.FixedParameters [i];
 301                                         if ((p.ModFlags & Parameter.Modifier.ISBYREF) == 0)
 302                                                 continue;
 303
 304                                         end_param_types [param] = p.ExternalType ();
 305                                         end_params [param] = p;
 306                                         ++param;
 307                                 }
 308                                 end_parameters = Parameters.CreateFullyResolved (end_params, end_param_types);
 309                         } else {
 310                                 end_parameters = Parameters.EmptyReadOnlyParameters;
 311                         }
 312
 313                         end_parameters = Parameters.MergeGenerated (end_parameters,
 314                                 new Parameter (TypeManager.iasyncresult_type, "result", Parameter.Modifier.NONE, null, Location));
 315
 316                         //
 317                         // Create method, define parameters, register parameters with type system
 318                         //
 319                         EndInvokeBuilder = TypeBuilder.DefineMethod ("EndInvoke", mattr, cc, ret_type, end_parameters.Types);
 320                         EndInvokeBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 321
 322                         end_parameters.ApplyAttributes (EndInvokeBuilder);
 323                         TypeManager.RegisterMethod (EndInvokeBuilder, end_parameters);
 324                         member_cache.AddMember (EndInvokeBuilder, this);
 325                 }
 326
 327                 public override void Emit ()
 328                 {
 329                         Parameters.ApplyAttributes (InvokeBuilder);
 330
 331                         if (BeginInvokeBuilder != null) {
 332                                 Parameters p = (Parameters) TypeManager.GetParameterData (BeginInvokeBuilder);
 333                                 p.ApplyAttributes (BeginInvokeBuilder);
 334                         }
 335
 336                         if (OptAttributes != null) {
 337                                 OptAttributes.Emit ();
 338                         }
 339
 340                         base.Emit ();
 341                 }
 342
 343                 protected override TypeAttributes TypeAttr {
 344                         get {
 345                                 return Modifiers.TypeAttr (ModFlags, IsTopLevel) |
 346                                         TypeAttributes.Class | TypeAttributes.Sealed |
 347                                         base.TypeAttr;
 348                         }
 349                 }
 350
 351                 public override string[] ValidAttributeTargets {
 352                         get {
 353                                 return attribute_targets;
 354                         }
 355                 }
 356
 357                 //TODO: duplicate
 358                 protected override bool VerifyClsCompliance ()
 359                 {
 360                         if (!base.VerifyClsCompliance ()) {
 361                                 return false;
 362                         }
 363
 364                         Parameters.VerifyClsCompliance ();
 365
 366                         if (!AttributeTester.IsClsCompliant (ReturnType.Type)) {
 367                                 Report.Error (3002, Location, "Return type of `{0}' is not CLS-compliant", GetSignatureForError ());
 368                         }
 369                         return true;
 370                 }
 371
 372
 373                 public static ConstructorInfo GetConstructor (Type container_type, Type delegate_type)
 374                 {
 375                         Type dt = delegate_type;
 376 #if GMCS_SOURCE
 377                         Type[] g_args = null;
 378                         if (delegate_type.IsGenericType) {
 379                                 g_args = delegate_type.GetGenericArguments ();
 380                                 delegate_type = delegate_type.GetGenericTypeDefinition ();
 381                         }
 382 #endif
 383
 384                         Delegate d = TypeManager.LookupDelegate (delegate_type);
 385                         if (d != null) {
 386 #if GMCS_SOURCE
 387                                 if (g_args != null)
 388                                         return TypeBuilder.GetConstructor (dt, d.ConstructorBuilder);
 389 #endif
 390                                 return d.ConstructorBuilder;
 391                         }
 392
 393                         Expression ml = Expression.MemberLookup (container_type,
 394                                 null, dt, ConstructorInfo.ConstructorName, MemberTypes.Constructor,
 395                                 BindingFlags.Public | BindingFlags.Instance | BindingFlags.DeclaredOnly, Location.Null);
 396
 397                         MethodGroupExpr mg = ml as MethodGroupExpr;
 398                         if (mg == null) {
 399                                 Report.Error (-100, Location.Null, "Internal error: could not find delegate constructor!");
 400                                 // FIXME: null will cause a crash later
 401                                 return null;
 402                         }
 403
 404                         return (ConstructorInfo) mg.Methods[0];
 405                 }
 406
 407                 //
 408                 // Returns the MethodBase for "Invoke" from a delegate type, this is used
 409                 // to extract the signature of a delegate.
 410                 //
 411                 public static MethodInfo GetInvokeMethod (Type container_type, Type delegate_type)
 412                 {
 413                         Type dt = delegate_type;
 414 #if GMCS_SOURCE
 415                         Type[] g_args = null;
 416                         if (delegate_type.IsGenericType) {
 417                                 g_args = delegate_type.GetGenericArguments ();
 418                                 delegate_type = delegate_type.GetGenericTypeDefinition ();
 419                         }
 420 #endif
 421                         Delegate d = TypeManager.LookupDelegate (delegate_type);
 422                         if (d != null) {
 423 #if GMCS_SOURCE
 424                                 if (g_args != null) {
 425                                         MethodInfo invoke = TypeBuilder.GetMethod (dt, d.InvokeBuilder);
 426 #if MS_COMPATIBLE
 427                                         Parameters p = (Parameters) d.Parameters.InflateTypes (g_args, g_args);
 428                                         TypeManager.RegisterMethod (invoke, p);
 429 #endif
 430                                         return invoke;
 431                                 }
 432 #endif
 433                                 return d.InvokeBuilder;
 434                         }
 435
 436                         Expression ml = Expression.MemberLookup (container_type, null, dt,
 437                                 "Invoke", Location.Null);
 438
 439                         MethodGroupExpr mg = ml as MethodGroupExpr;
 440                         if (mg == null) {
 441                                 Report.Error (-100, Location.Null, "Internal error: could not find Invoke method!");
 442                                 // FIXME: null will cause a crash later
 443                                 return null;
 444                         }
 445
 446                         return (MethodInfo) mg.Methods[0];
 447                 }
 448
 449                 public static bool IsTypeCovariant (Expression a, Type b)
 450                 {
 451                         Type a_type = a.Type;
 452                         if (a_type == b)
 453                                 return true;
 454
 455                         if (RootContext.Version == LanguageVersion.ISO_1)
 456                                 return false;
 457
 458                         if (a.Type.IsValueType)
 459                                 return false;
 460
 461                         return Convert.ImplicitReferenceConversionCore (
 462                                 a, b);
 463                 }
 464
 465                 /// <summary>
 466                 ///  Verifies whether the method in question is compatible with the delegate
 467                 ///  Returns the method itself if okay and null if not.
 468                 /// </summary>
 469                 public static MethodBase VerifyMethod (Type container_type, Type delegate_type,
 470                                                        MethodGroupExpr old_mg, MethodBase mb,
 471                                                        Location loc)
 472                 {
 473                         MethodInfo invoke_mb = GetInvokeMethod (container_type, delegate_type);
 474                         if (invoke_mb == null)
 475                                 return null;
 476
 477                         ParameterData invoke_pd = TypeManager.GetParameterData (invoke_mb);
 478
 479 #if GMCS_SOURCE
 480                         if (old_mg.type_arguments == null &&
 481                             !TypeManager.InferTypeArguments (invoke_pd, ref mb))
 482                                 return null;
 483 #endif
 484
 485                         ParameterData pd = TypeManager.GetParameterData (mb);
 486
 487                         if (invoke_pd.Count != pd.Count)
 488                                 return null;
 489
 490                         for (int i = pd.Count; i > 0; ) {
 491                                 i--;
 492
 493                                 Type invoke_pd_type = invoke_pd.ParameterType (i);
 494                                 Type pd_type = pd.ParameterType (i);
 495                                 Parameter.Modifier invoke_pd_type_mod = invoke_pd.ParameterModifier (i);
 496                                 Parameter.Modifier pd_type_mod = pd.ParameterModifier (i);
 497
 498                                 invoke_pd_type_mod &= ~Parameter.Modifier.PARAMS;
 499                                 pd_type_mod &= ~Parameter.Modifier.PARAMS;
 500
 501                                 if (invoke_pd_type_mod != pd_type_mod)
 502                                         return null;
 503
 504                                 if (invoke_pd_type == pd_type)
 505                                         continue;
 506
 507                                 //if (!IsTypeCovariant (invoke_pd_type, pd_type))
 508                                 //      return null;
 509
 510                                 if (RootContext.Version == LanguageVersion.ISO_1)
 511                                         return null;
 512                         }
 513
 514                         Type invoke_mb_retval = ((MethodInfo) invoke_mb).ReturnType;
 515                         Type mb_retval = ((MethodInfo) mb).ReturnType;
 516                         if (TypeManager.TypeToCoreType (invoke_mb_retval) == TypeManager.TypeToCoreType (mb_retval))
 517                                 return mb;
 518
 519                         //if (!IsTypeCovariant (mb_retval, invoke_mb_retval))
 520                         //      return null;
 521
 522                         if (RootContext.Version == LanguageVersion.ISO_1)
 523                                 return null;
 524
 525                         return mb;
 526                 }
 527
 528                 // <summary>
 529                 //  Verifies whether the invocation arguments are compatible with the
 530                 //  delegate's target method
 531                 // </summary>
 532                 public static bool VerifyApplicability (EmitContext ec, Type delegate_type,
 533                                                         ArrayList args, Location loc)
 534                 {
 535                         int arg_count;
 536
 537                         if (args == null)
 538                                 arg_count = 0;
 539                         else
 540                                 arg_count = args.Count;
 541
 542                         Expression ml = Expression.MemberLookup (
 543                                 ec.ContainerType, delegate_type, "Invoke", loc);
 544
 545                         MethodGroupExpr me = ml as MethodGroupExpr;
 546                         if (me == null) {
 547                                 Report.Error (-100, loc, "Internal error: could not find Invoke method!" + delegate_type);
 548                                 return false;
 549                         }
 550
 551                         MethodBase mb = GetInvokeMethod (ec.ContainerType, delegate_type);
 552                         ParameterData pd = TypeManager.GetParameterData (mb);
 553
 554                         int pd_count = pd.Count;
 555
 556                         bool params_method = pd.HasParams;
 557                         bool is_params_applicable = false;
 558                         me.DelegateType = delegate_type;
 559                         bool is_applicable = me.IsApplicable (ec, args, arg_count, ref mb, ref is_params_applicable) == 0;
 560
 561                         if (!is_applicable && !params_method && arg_count != pd_count) {
 562                                 Report.Error (1593, loc, "Delegate `{0}' does not take `{1}' arguments",
 563                                         TypeManager.CSharpName (delegate_type), arg_count.ToString ());
 564                                 return false;
 565                         }
 566
 567                         return me.VerifyArgumentsCompat (
 568                                         ec, ref args, arg_count, mb,
 569                                         is_params_applicable || (!is_applicable && params_method),
 570                                         false, loc);
 571                 }
 572
 573                 public static string FullDelegateDesc (MethodBase invoke_method)
 574                 {
 575                         return TypeManager.GetFullNameSignature (invoke_method).Replace (".Invoke", "");
 576                 }
 577
 578                 public override MemberCache MemberCache {
 579                         get {
 580                                 return member_cache;
 581                         }
 582                 }
 583
 584                 public Expression InstanceExpression {
 585                         get {
 586                                 return instance_expr;
 587                         }
 588                         set {
 589                                 instance_expr = value;
 590                         }
 591                 }
 592
 593                 public MethodBase TargetMethod {
 594                         get {
 595                                 return delegate_method;
 596                         }
 597                         set {
 598                                 delegate_method = value;
 599                         }
 600                 }
 601
 602                 public Type TargetReturnType {
 603                         get {
 604                                 return ret_type;
 605                         }
 606                 }
 607
 608                 public override AttributeTargets AttributeTargets {
 609                         get {
 610                                 return AttributeTargets.Delegate;
 611                         }
 612                 }
 613
 614                 //
 615                 //   Represents header string for documentation comment.
 616                 //
 617                 public override string DocCommentHeader {
 618                         get { return "T:"; }
 619                 }
 620
 621                 #region IMemberContainer Members
 622
 623                 string IMemberContainer.Name
 624                 {
 625                         get { throw new NotImplementedException (); }
 626                 }
 627
 628                 Type IMemberContainer.Type
 629                 {
 630                         get { throw new NotImplementedException (); }
 631                 }
 632
 633                 MemberCache IMemberContainer.BaseCache
 634                 {
 635                         get { throw new NotImplementedException (); }
 636                 }
 637
 638                 bool IMemberContainer.IsInterface {
 639                         get {
 640                                 return false;
 641                         }
 642                 }
 643
 644                 MemberList IMemberContainer.GetMembers (MemberTypes mt, BindingFlags bf)
 645                 {
 646                         throw new NotImplementedException ();
 647                 }
 648
 649                 #endregion
 650         }
 651
 652         //
 653         // Base class for `NewDelegate' and `ImplicitDelegateCreation'
 654         //
 655         public abstract class DelegateCreation : Expression, MethodGroupExpr.IErrorHandler
 656         {
 657                 protected ConstructorInfo constructor_method;
 658                 protected MethodInfo delegate_method;
 659                 // We keep this to handle IsBase only
 660                 protected MethodGroupExpr method_group;
 661                 protected Expression delegate_instance_expression;
 662
 663                 ArrayList CreateDelegateMethodArguments (MethodInfo invoke_method)
 664                 {
 665                         ParameterData pd = TypeManager.GetParameterData (invoke_method);
 666                         ArrayList delegate_arguments = new ArrayList (pd.Count);
 667                         for (int i = 0; i < pd.Count; ++i) {
 668                                 Argument.AType atype_modifier;
 669                                 Type atype = pd.Types [i];
 670                                 switch (pd.ParameterModifier (i)) {
 671                                         case Parameter.Modifier.REF:
 672                                                 atype_modifier = Argument.AType.Ref;
 673                                                 atype = atype.GetElementType ();
 674                                                 break;
 675                                         case Parameter.Modifier.OUT:
 676                                                 atype_modifier = Argument.AType.Out;
 677                                                 atype = atype.GetElementType ();
 678                                                 break;
 679                                         case Parameter.Modifier.ARGLIST:
 680                                                 // __arglist is not valid
 681                                                 throw new InternalErrorException ("__arglist modifier");
 682                                         default:
 683                                                 atype_modifier = Argument.AType.Expression;
 684                                                 break;
 685                                 }
 686                                 delegate_arguments.Add (new Argument (new TypeExpression (atype, loc), atype_modifier));
 687                         }
 688                         return delegate_arguments;
 689                 }
 690
 691                 public override Expression CreateExpressionTree (EmitContext ec)
 692                 {
 693                         MemberAccess ma = new MemberAccess (new MemberAccess (new QualifiedAliasMember ("global", "System", loc), "Delegate", loc), "CreateDelegate", loc);
 694
 695                         ArrayList args = new ArrayList (3);
 696                         args.Add (new Argument (new TypeOf (new TypeExpression (type, loc), loc)));
 697                         args.Add (new Argument (new NullLiteral (loc)));
 698                         args.Add (new Argument (new TypeOfMethodInfo (delegate_method, loc)));
 699                         Expression e = new Invocation (ma, args).Resolve (ec);
 700                         if (e == null)
 701                                 return null;
 702
 703                         e = Convert.ExplicitConversion (ec, e, type, loc);
 704                         if (e == null)
 705                                 return null;
 706
 707                         return e.CreateExpressionTree (ec);
 708                 }
 709
 710                 public override Expression DoResolve (EmitContext ec)
 711                 {
 712                         constructor_method = Delegate.GetConstructor (ec.ContainerType, type);
 713
 714                         MethodInfo invoke_method = Delegate.GetInvokeMethod (ec.ContainerType, type);
 715                         method_group.DelegateType = type;
 716                         method_group.CustomErrorHandler = this;
 717
 718                         ArrayList arguments = CreateDelegateMethodArguments (invoke_method);
 719                         method_group = method_group.OverloadResolve (ec, ref arguments, false, loc);
 720                         if (method_group == null)
 721                                 return null;
 722
 723                         delegate_method = (MethodInfo) method_group;
 724                         ExtensionMethodGroupExpr emg = method_group as ExtensionMethodGroupExpr;
 725                         if (emg != null) {
 726                                 delegate_instance_expression = emg.ExtensionExpression;
 727                                 Type e_type = delegate_instance_expression.Type;
 728                                 if (TypeManager.IsValueType (e_type)) {
 729                                         Report.Error (1113, loc, "Extension method `{0}' of value type `{1}' cannot be used to create delegates",
 730                                                 TypeManager.CSharpSignature (delegate_method), TypeManager.CSharpName (e_type));
 731                                 }
 732                         }
 733
 734                         Type rt = TypeManager.TypeToCoreType (delegate_method.ReturnType);
 735                         Expression ret_expr = new TypeExpression (rt, loc);
 736                         if (!Delegate.IsTypeCovariant (ret_expr, (TypeManager.TypeToCoreType (invoke_method.ReturnType)))) {
 737                                 Error_ConversionFailed (ec, delegate_method, ret_expr);
 738                         }
 739
 740                         DoResolveInstanceExpression (ec);
 741                         eclass = ExprClass.Value;
 742                         return this;
 743                 }
 744
 745                 void DoResolveInstanceExpression (EmitContext ec)
 746                 {
 747                         //
 748                         // Argument is another delegate
 749                         //
 750                         if (delegate_instance_expression != null)
 751                                 return;
 752
 753                         if (method_group.InstanceExpression != null)
 754                                 delegate_instance_expression = method_group.InstanceExpression;
 755                         else if (!delegate_method.IsStatic && !ec.IsStatic)
 756                                 delegate_instance_expression = ec.GetThis (loc);
 757
 758                         if (delegate_instance_expression != null && delegate_instance_expression.Type.IsValueType)
 759                                 delegate_instance_expression = new BoxedCast (
 760                                         delegate_instance_expression, TypeManager.object_type);
 761                 }
 762
 763                 public override void Emit (EmitContext ec)
 764                 {
 765                         if (delegate_instance_expression == null)
 766                                 ec.ig.Emit (OpCodes.Ldnull);
 767                         else
 768                                 delegate_instance_expression.Emit (ec);
 769
 770                         if (!delegate_method.DeclaringType.IsSealed && delegate_method.IsVirtual && !method_group.IsBase) {
 771                                 ec.ig.Emit (OpCodes.Dup);
 772                                 ec.ig.Emit (OpCodes.Ldvirtftn, (MethodInfo) delegate_method);
 773                         } else
 774                                 ec.ig.Emit (OpCodes.Ldftn, (MethodInfo) delegate_method);
 775                         ec.ig.Emit (OpCodes.Newobj, constructor_method);
 776                 }
 777
 778                 void Error_ConversionFailed (EmitContext ec, MethodBase method, Expression return_type)
 779                 {
 780                         MethodInfo invoke_method = Delegate.GetInvokeMethod (ec.ContainerType, type);
 781                         string member_name = delegate_instance_expression != null ?
 782                                 Delegate.FullDelegateDesc (method) :
 783                                 TypeManager.GetFullNameSignature (method);
 784
 785                         Report.SymbolRelatedToPreviousError (type);
 786                         Report.SymbolRelatedToPreviousError (method);
 787                         if (RootContext.Version == LanguageVersion.ISO_1) {
 788                                 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",
 789                                         TypeManager.CSharpName (((MethodInfo) method).ReturnType), member_name,
 790                                         TypeManager.CSharpName (invoke_method.ReturnType), Delegate.FullDelegateDesc (invoke_method));
 791                                 return;
 792                         }
 793                         if (return_type == null) {
 794                                 Report.Error (123, loc, "A method or delegate `{0}' parameters do not match delegate `{1}' parameters",
 795                                         member_name, Delegate.FullDelegateDesc (invoke_method));
 796                                 return;
 797                         }
 798
 799                         Report.Error (407, loc, "A method or delegate `{0} {1}' return type does not match delegate `{2} {3}' return type",
 800                                 return_type.GetSignatureForError (), member_name,
 801                                 TypeManager.CSharpName (invoke_method.ReturnType), Delegate.FullDelegateDesc (invoke_method));
 802                 }
 803
 804                 public static MethodBase ImplicitStandardConversionExists (MethodGroupExpr mg, Type target_type)
 805                 {
 806                         if (target_type == TypeManager.delegate_type || target_type == TypeManager.multicast_delegate_type)
 807                                 return null;
 808
 809                         foreach (MethodInfo mi in mg.Methods){
 810                                 MethodBase mb = Delegate.VerifyMethod (mg.DeclaringType, target_type, mg, mi, Location.Null);
 811                                 if (mb != null)
 812                                         return mb;
 813                         }
 814                         return null;
 815                 }
 816
 817                 #region IErrorHandler Members
 818
 819                 public bool NoExactMatch (EmitContext ec, MethodBase method)
 820                 {
 821                         if (TypeManager.IsGenericMethod (method))
 822                                 return false;
 823
 824                         Error_ConversionFailed (ec, method, null);
 825                         return true;
 826                 }
 827
 828                 #endregion
 829         }
 830
 831         //
 832         // Created from the conversion code
 833         //
 834         public class ImplicitDelegateCreation : DelegateCreation
 835         {
 836                 ImplicitDelegateCreation (Type t, MethodGroupExpr mg, Location l)
 837                 {
 838                         type = t;
 839                         this.method_group = mg;
 840                         loc = l;
 841                 }
 842
 843                 static public Expression Create (EmitContext ec, MethodGroupExpr mge,
 844                                                  Type target_type, Location loc)
 845                 {
 846                         ImplicitDelegateCreation d = new ImplicitDelegateCreation (target_type, mge, loc);
 847                         return d.DoResolve (ec);
 848                 }
 849         }
 850
 851         //
 852         // A delegate-creation-expression, invoked from the `New' class
 853         //
 854         public class NewDelegate : DelegateCreation
 855         {
 856                 public ArrayList Arguments;
 857
 858                 //
 859                 // This constructor is invoked from the `New' expression
 860                 //
 861                 public NewDelegate (Type type, ArrayList Arguments, Location loc)
 862                 {
 863                         this.type = type;
 864                         this.Arguments = Arguments;
 865                         this.loc  = loc;
 866                 }
 867
 868                 public override Expression DoResolve (EmitContext ec)
 869                 {
 870                         if (Arguments == null) {
 871                                 Error_InvalidDelegateArgument ();
 872                                 return null;
 873                         }
 874
 875                         Argument a = (Argument) Arguments [0];
 876                         if (!a.ResolveMethodGroup (ec))
 877                                 return null;
 878
 879                         Expression e = a.Expr;
 880                         if (e is AnonymousMethodExpression && RootContext.Version != LanguageVersion.ISO_1) {
 881                                 e = ((AnonymousMethodExpression) e).Compatible (ec, type);
 882                                 if (e == null)
 883                                         return null;
 884                                 return e.Resolve (ec);
 885                         }
 886
 887                         method_group = e as MethodGroupExpr;
 888                         if (method_group == null) {
 889                                 if (!TypeManager.IsDelegateType (e.Type)) {
 890                                         Report.Error (149, loc, "Method name expected");
 891                                         return null;
 892                                 }
 893
 894                                 //
 895                                 // An argument is not a method but another delegate
 896                                 //
 897                                 delegate_instance_expression = e;
 898                                 method_group = new MethodGroupExpr (new MemberInfo [] {
 899                                         Delegate.GetInvokeMethod (ec.ContainerType, e.Type) }, e.Type, loc);
 900                         }
 901
 902                         if (base.DoResolve (ec) == null)
 903                                 return null;
 904
 905                         if (TypeManager.IsNullableType (method_group.DeclaringType)) {
 906                                 Report.Error (1728, loc, "Cannot use method `{0}' as delegate creation expression because it is member of Nullable type",
 907                                         TypeManager.GetFullNameSignature (delegate_method));
 908                         }
 909
 910                         if (Invocation.IsMethodExcluded (delegate_method)) {
 911                                 Report.SymbolRelatedToPreviousError (delegate_method);
 912                                 Report.Error (1618, loc, "Cannot create delegate with `{0}' because it has a Conditional attribute",
 913                                         TypeManager.CSharpSignature (delegate_method));
 914                         }
 915
 916                         return this;
 917                 }
 918
 919                 void Error_InvalidDelegateArgument ()
 920                 {
 921                         Report.Error (149, loc, "Method name expected");
 922                 }
 923         }
 924
 925         public class DelegateInvocation : ExpressionStatement {
 926
 927                 readonly Expression InstanceExpr;
 928                 readonly ArrayList  Arguments;
 929
 930                 MethodBase method;
 931
 932                 public DelegateInvocation (Expression instance_expr, ArrayList args, Location loc)
 933                 {
 934                         this.InstanceExpr = instance_expr;
 935                         this.Arguments = args;
 936                         this.loc = loc;
 937                 }
 938
 939                 public override Expression DoResolve (EmitContext ec)
 940                 {
 941                         if (InstanceExpr is EventExpr) {
 942                                 ((EventExpr) InstanceExpr).Error_CannotAssign ();
 943                                 return null;
 944                         }
 945
 946                         Type del_type = InstanceExpr.Type;
 947                         if (del_type == null)
 948                                 return null;
 949
 950                         if (Arguments != null){
 951                                 foreach (Argument a in Arguments){
 952                                         if (!a.Resolve (ec, loc))
 953                                                 return null;
 954                                 }
 955                         }
 956
 957                         if (!Delegate.VerifyApplicability (ec, del_type, Arguments, loc))
 958                                 return null;
 959
 960                         method = Delegate.GetInvokeMethod (ec.ContainerType, del_type);
 961                         type = ((MethodInfo) method).ReturnType;
 962                         type = TypeManager.TypeToCoreType (type);
 963                         eclass = ExprClass.Value;
 964
 965                         return this;
 966                 }
 967
 968                 public override void Emit (EmitContext ec)
 969                 {
 970                         //
 971                         // Invocation on delegates call the virtual Invoke member
 972                         // so we are always `instance' calls
 973                         //
 974                         Invocation.EmitCall (ec, false, InstanceExpr, method, Arguments, loc);
 975                 }
 976
 977                 public override void EmitStatement (EmitContext ec)
 978                 {
 979                         Emit (ec);
 980                         //
 981                         // Pop the return value if there is one
 982                         //
 983                         if (method is MethodInfo){
 984                                 Type ret = ((MethodInfo)method).ReturnType;
 985                                 if (TypeManager.TypeToCoreType (ret) != TypeManager.void_type)
 986                                         ec.ig.Emit (OpCodes.Pop);
 987                         }
 988                 }
 989
 990         }
 991 }