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 //
   8 // Licensed under the terms of the GNU GPL
   9 //
  10 // (C) 2001 Ximian, Inc (http://www.ximian.com)
  11 //
  12 //
  13
  14 using System;
  15 using System.Collections;
  16 using System.Reflection;
  17 using System.Reflection.Emit;
  18 using System.Text;
  19
  20 namespace Mono.CSharp {
  21
  22         /// <summary>
  23         ///   Holds Delegates
  24         /// </summary>
  25         public class Delegate : DeclSpace {
  26                 public Expression ReturnType;
  27                 public Parameters      Parameters;
  28
  29                 public ConstructorBuilder ConstructorBuilder;
  30                 public MethodBuilder      InvokeBuilder;
  31                 public MethodBuilder      BeginInvokeBuilder;
  32                 public MethodBuilder      EndInvokeBuilder;
  33
  34                 Type ret_type;
  35
  36                 static string[] attribute_targets = new string [] { "type", "return" };
  37
  38                 Expression instance_expr;
  39                 MethodBase delegate_method;
  40                 ReturnParameter return_attributes;
  41
  42                 const int AllowedModifiers =
  43                         Modifiers.NEW |
  44                         Modifiers.PUBLIC |
  45                         Modifiers.PROTECTED |
  46                         Modifiers.INTERNAL |
  47                         Modifiers.UNSAFE |
  48                         Modifiers.PRIVATE;
  49
  50                 public Delegate (NamespaceEntry ns, TypeContainer parent, Expression type,
  51                                  int mod_flags, MemberName name, Parameters param_list,
  52                                  Attributes attrs)
  53                         : base (ns, parent, name, attrs)
  54
  55                 {
  56                         this.ReturnType = type;
  57                         ModFlags        = Modifiers.Check (AllowedModifiers, mod_flags,
  58                                                            IsTopLevel ? Modifiers.INTERNAL :
  59                                                            Modifiers.PRIVATE, name.Location);
  60                         Parameters      = param_list;
  61                 }
  62
  63                 public override void ApplyAttributeBuilder(Attribute a, CustomAttributeBuilder cb)
  64                 {
  65                         if (a.Target == AttributeTargets.ReturnValue) {
  66                                 if (return_attributes == null)
  67                                         return_attributes = new ReturnParameter (InvokeBuilder, Location);
  68
  69                                 return_attributes.ApplyAttributeBuilder (a, cb);
  70                                 return;
  71                         }
  72
  73                         base.ApplyAttributeBuilder (a, cb);
  74                 }
  75
  76                 public override TypeBuilder DefineType ()
  77                 {
  78                         if (TypeBuilder != null)
  79                                 return TypeBuilder;
  80
  81                         if (TypeManager.multicast_delegate_type == null && !RootContext.StdLib) {
  82                                 Namespace system = RootNamespace.Global.GetNamespace ("System", true);
  83                                 TypeExpr expr = system.Lookup (this, "MulticastDelegate", Location) as TypeExpr;
  84                                 TypeManager.multicast_delegate_type = expr.Type;
  85                         }
  86
  87                         if (TypeManager.multicast_delegate_type == null)
  88                                 throw new InternalErrorException ("System.MulticastDelegate unresolved");
  89
  90                         if (IsTopLevel) {
  91                                 if (TypeManager.NamespaceClash (Name, Location))
  92                                         return null;
  93
  94                                 ModuleBuilder builder = CodeGen.Module.Builder;
  95
  96                                 TypeBuilder = builder.DefineType (
  97                                         Name, TypeAttr, TypeManager.multicast_delegate_type);
  98                         } else {
  99                                 TypeBuilder builder = Parent.TypeBuilder;
 100
 101                                 string name = Name.Substring (1 + Name.LastIndexOf ('.'));
 102                                 TypeBuilder = builder.DefineNestedType (
 103                                         name, TypeAttr, TypeManager.multicast_delegate_type);
 104                         }
 105
 106                         TypeManager.AddUserType (this);
 107
 108                         return TypeBuilder;
 109                 }
 110
 111                 public override bool Define ()
 112                 {
 113                         // FIXME: POSSIBLY make this static, as it is always constant
 114                         //
 115                         Type [] const_arg_types = new Type [2];
 116                         const_arg_types [0] = TypeManager.object_type;
 117                         const_arg_types [1] = TypeManager.intptr_type;
 118
 119                         const MethodAttributes ctor_mattr = MethodAttributes.RTSpecialName | MethodAttributes.SpecialName |
 120                                 MethodAttributes.HideBySig | MethodAttributes.Public;
 121
 122                         ConstructorBuilder = TypeBuilder.DefineConstructor (ctor_mattr,
 123                                                                             CallingConventions.Standard,
 124                                                                             const_arg_types);
 125
 126                         ConstructorBuilder.DefineParameter (1, ParameterAttributes.None, "object");
 127                         ConstructorBuilder.DefineParameter (2, ParameterAttributes.None, "method");
 128                         //
 129                         // HACK because System.Reflection.Emit is lame
 130                         //
 131                         Parameter [] fixed_pars = new Parameter [2];
 132                         fixed_pars [0] = new Parameter (TypeManager.object_type, "object",
 133                                                         Parameter.Modifier.NONE, null, Location);
 134                         fixed_pars [1] = new Parameter (TypeManager.intptr_type, "method",
 135                                                         Parameter.Modifier.NONE, null, Location);
 136                         Parameters const_parameters = new Parameters (fixed_pars);
 137                         const_parameters.Resolve (null);
 138
 139                         TypeManager.RegisterMethod (ConstructorBuilder, const_parameters);
 140
 141
 142                         ConstructorBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 143
 144                         //
 145                         // Here the various methods like Invoke, BeginInvoke etc are defined
 146                         //
 147                         // First, call the `out of band' special method for
 148                         // defining recursively any types we need:
 149
 150                         if (!Parameters.Resolve (this))
 151                                 return false;
 152
 153                         //
 154                         // Invoke method
 155                         //
 156
 157                         // Check accessibility
 158                         foreach (Type partype in Parameters.Types){
 159                                 if (!Parent.AsAccessible (partype, ModFlags)) {
 160                                         Report.Error (59, Location,
 161                                                       "Inconsistent accessibility: parameter type `" +
 162                                                       TypeManager.CSharpName (partype) + "' is less " +
 163                                                       "accessible than delegate `" + Name + "'");
 164                                         return false;
 165                                 }
 166                         }
 167
 168                         ReturnType = ReturnType.ResolveAsTypeTerminal (this, false);
 169                         if (ReturnType == null)
 170                                 return false;
 171
 172                         ret_type = ReturnType.Type;
 173
 174                         if (!Parent.AsAccessible (ret_type, ModFlags)) {
 175                                 Report.Error (58, Location,
 176                                               "Inconsistent accessibility: return type `" +
 177                                               TypeManager.CSharpName (ret_type) + "' is less " +
 178                                               "accessible than delegate `" + Name + "'");
 179                                 return false;
 180                         }
 181
 182                         if (RootContext.StdLib && (ret_type == TypeManager.arg_iterator_type || ret_type == TypeManager.typed_reference_type)) {
 183                                 Method.Error1599 (Location, ret_type);
 184                                 return false;
 185                         }
 186
 187                         //
 188                         // We don't have to check any others because they are all
 189                         // guaranteed to be accessible - they are standard types.
 190                         //
 191
 192                         CallingConventions cc = Parameters.CallingConvention;
 193
 194                         const MethodAttributes mattr = MethodAttributes.Public | MethodAttributes.HideBySig | MethodAttributes.Virtual | MethodAttributes.NewSlot;
 195
 196                         InvokeBuilder = TypeBuilder.DefineMethod ("Invoke",
 197                                                                   mattr,
 198                                                                   cc,
 199                                                                   ret_type,
 200                                                                   Parameters.Types);
 201
 202                         InvokeBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 203
 204                         TypeManager.RegisterMethod (InvokeBuilder, Parameters);
 205
 206                         //
 207                         // BeginInvoke
 208                         //
 209
 210                         Parameters async_parameters = Parameters.MergeGenerated (Parameters,
 211                                 new Parameter (TypeManager.asynccallback_type, "callback", Parameter.Modifier.NONE, null, Location),
 212                                 new Parameter (TypeManager.object_type, "object", Parameter.Modifier.NONE, null, Location));
 213
 214                         BeginInvokeBuilder = TypeBuilder.DefineMethod ("BeginInvoke",
 215                                 mattr, cc, TypeManager.iasyncresult_type, async_parameters.Types);
 216
 217                         BeginInvokeBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 218                         async_parameters.ApplyAttributes (BeginInvokeBuilder);
 219                         TypeManager.RegisterMethod (BeginInvokeBuilder, async_parameters);
 220
 221                         //
 222                         // EndInvoke is a bit more interesting, all the parameters labeled as
 223                         // out or ref have to be duplicated here.
 224                         //
 225
 226                         //
 227                         // Define parameters, and count out/ref parameters
 228                         //
 229                         Parameters end_parameters;
 230                         int out_params = 0;
 231
 232                         foreach (Parameter p in Parameters.FixedParameters) {
 233                                 if ((p.ModFlags & Parameter.Modifier.ISBYREF) != 0)
 234                                         ++out_params;
 235                         }
 236
 237                         if (out_params > 0) {
 238                                 Type [] end_param_types = new Type [out_params];
 239                                 Parameter [] end_params = new Parameter [out_params ];
 240
 241                                 int param = 0;
 242                                 for (int i = 0; i < Parameters.FixedParameters.Length; ++i) {
 243                                         Parameter p = Parameters.FixedParameters [i];
 244                                         if ((p.ModFlags & Parameter.Modifier.ISBYREF) == 0)
 245                                                 continue;
 246
 247                                         end_param_types [param] = p.ExternalType();
 248                                         end_params [param] = p;
 249                                         ++param;
 250                                 }
 251                                 end_parameters = new Parameters (end_params, end_param_types);
 252                         }
 253                         else {
 254                                 end_parameters = Parameters.EmptyReadOnlyParameters;
 255                         }
 256
 257                         end_parameters = Parameters.MergeGenerated (end_parameters,
 258                                 new Parameter (TypeManager.iasyncresult_type, "result", Parameter.Modifier.NONE, null, Location));
 259
 260                         //
 261                         // Create method, define parameters, register parameters with type system
 262                         //
 263                         EndInvokeBuilder = TypeBuilder.DefineMethod ("EndInvoke", mattr, cc, ret_type, end_parameters.Types);
 264                         EndInvokeBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 265
 266                         end_parameters.ApplyAttributes (EndInvokeBuilder);
 267                         TypeManager.RegisterMethod (EndInvokeBuilder, end_parameters);
 268
 269                         return true;
 270                 }
 271
 272                 public override void Emit ()
 273                 {
 274                         Parameters.ApplyAttributes (InvokeBuilder);
 275
 276                         if (OptAttributes != null) {
 277                                 OptAttributes.Emit ();
 278                         }
 279
 280                         base.Emit ();
 281                 }
 282
 283                 protected override TypeAttributes TypeAttr {
 284                         get {
 285                                 return Modifiers.TypeAttr (ModFlags, IsTopLevel) |
 286                                         TypeAttributes.Class | TypeAttributes.Sealed |
 287                                         base.TypeAttr;
 288                         }
 289                 }
 290
 291                 public override string[] ValidAttributeTargets {
 292                         get {
 293                                 return attribute_targets;
 294                         }
 295                 }
 296
 297                 //TODO: duplicate
 298                 protected override bool VerifyClsCompliance ()
 299                 {
 300                         if (!base.VerifyClsCompliance ()) {
 301                                 return false;
 302                         }
 303
 304                         Parameters.VerifyClsCompliance ();
 305
 306                         if (!AttributeTester.IsClsCompliant (ReturnType.Type)) {
 307                                 Report.Error (3002, Location, "Return type of `{0}' is not CLS-compliant", GetSignatureForError ());
 308                         }
 309                         return true;
 310                 }
 311
 312                 //
 313                 // Returns the MethodBase for "Invoke" from a delegate type, this is used
 314                 // to extract the signature of a delegate.
 315                 //
 316                 public static MethodInfo GetInvokeMethod (Type container_type, Type delegate_type, Location loc)
 317                 {
 318                         Expression ml = Expression.MemberLookup (container_type, delegate_type,
 319                                 "Invoke", loc);
 320
 321                         if (!(ml is MethodGroupExpr)) {
 322                                 Report.Error (-100, loc, "Internal error: could not find Invoke method!");
 323                                 return null;
 324                         }
 325
 326                         return (MethodInfo) (((MethodGroupExpr) ml).Methods [0]);
 327                 }
 328
 329                 /// <summary>
 330                 ///  Verifies whether the method in question is compatible with the delegate
 331                 ///  Returns the method itself if okay and null if not.
 332                 /// </summary>
 333                 public static MethodBase VerifyMethod (Type container_type, Type delegate_type, MethodBase mb,
 334                                                        Location loc)
 335                 {
 336                         ParameterData pd = TypeManager.GetParameterData (mb);
 337
 338                         int pd_count = pd.Count;
 339
 340                         MethodBase invoke_mb = GetInvokeMethod (container_type, delegate_type, loc);
 341                         if (invoke_mb == null)
 342                                 return null;
 343
 344                         ParameterData invoke_pd = TypeManager.GetParameterData (invoke_mb);
 345
 346                         if (invoke_pd.Count != pd_count)
 347                                 return null;
 348
 349                         for (int i = pd_count; i > 0; ) {
 350                                 i--;
 351
 352                                 Type invoke_pd_type = invoke_pd.ParameterType (i);
 353                                 Type pd_type = pd.ParameterType (i);
 354                                 Parameter.Modifier invoke_pd_type_mod = invoke_pd.ParameterModifier (i);
 355                                 Parameter.Modifier pd_type_mod = pd.ParameterModifier (i);
 356
 357                                 if (invoke_pd_type == pd_type &&
 358                                     invoke_pd_type_mod == pd_type_mod)
 359                                         continue;
 360
 361                                 if (invoke_pd_type.IsSubclassOf (pd_type) &&
 362                                                 invoke_pd_type_mod == pd_type_mod)
 363                                         if (RootContext.Version == LanguageVersion.ISO_1) {
 364                                                 Report.FeatureIsNotStandardized (loc, "contravariance");
 365                                                 return null;
 366                                         } else
 367                                                 continue;
 368
 369                                 return null;
 370                         }
 371
 372                         Type invoke_mb_retval = ((MethodInfo) invoke_mb).ReturnType;
 373                         Type mb_retval = ((MethodInfo) mb).ReturnType;
 374                         if (invoke_mb_retval == mb_retval)
 375                                 return mb;
 376
 377                         if (mb_retval.IsSubclassOf (invoke_mb_retval))
 378                                 if (RootContext.Version == LanguageVersion.ISO_1) {
 379                                         Report.FeatureIsNotStandardized (loc, "covariance");
 380                                         return null;
 381                                 }
 382                                 else
 383                                         return mb;
 384
 385                         return null;
 386                 }
 387
 388                 // <summary>
 389                 //  Verifies whether the invocation arguments are compatible with the
 390                 //  delegate's target method
 391                 // </summary>
 392                 public static bool VerifyApplicability (EmitContext ec, Type delegate_type,
 393                                                         ArrayList args, Location loc)
 394                 {
 395                         int arg_count;
 396
 397                         if (args == null)
 398                                 arg_count = 0;
 399                         else
 400                                 arg_count = args.Count;
 401
 402                         Expression ml = Expression.MemberLookup (
 403                                 ec.ContainerType, delegate_type, "Invoke", loc);
 404
 405                         MethodGroupExpr me = ml as MethodGroupExpr;
 406                         if (me == null) {
 407                                 Report.Error (-100, loc, "Internal error: could not find Invoke method!" + delegate_type);
 408                                 return false;
 409                         }
 410
 411                         MethodBase mb = me.Methods [0];
 412                         ParameterData pd = TypeManager.GetParameterData (mb);
 413
 414                         int pd_count = pd.Count;
 415
 416                         bool params_method = pd.HasParams;
 417                         bool is_params_applicable = false;
 418                         bool is_applicable = Invocation.IsApplicable (ec, args, arg_count, mb);
 419
 420                         if (!is_applicable && params_method &&
 421                             Invocation.IsParamsMethodApplicable (ec, args, arg_count, mb))
 422                                 is_applicable = is_params_applicable = true;
 423
 424                         if (!is_applicable && !params_method && arg_count != pd_count) {
 425                                 Report.Error (1593, loc, "Delegate `{0}' does not take `{1}' arguments",
 426                                         TypeManager.CSharpName (delegate_type), arg_count.ToString ());
 427                                 return false;
 428                         }
 429
 430                         return Invocation.VerifyArgumentsCompat (
 431                                         ec, args, arg_count, mb,
 432                                         is_params_applicable || (!is_applicable && params_method),
 433                                         delegate_type, false, loc);
 434                 }
 435
 436                 /// <summary>
 437                 ///  Verifies whether the delegate in question is compatible with this one in
 438                 ///  order to determine if instantiation from the same is possible.
 439                 /// </summary>
 440                 public static bool VerifyDelegate (EmitContext ec, Type delegate_type, Type probe_type, Location loc)
 441                 {
 442                         Expression ml = Expression.MemberLookup (
 443                                 ec.ContainerType, delegate_type, "Invoke", loc);
 444
 445                         if (!(ml is MethodGroupExpr)) {
 446                                 Report.Error (-100, loc, "Internal error: could not find Invoke method!");
 447                                 return false;
 448                         }
 449
 450                         MethodBase mb = ((MethodGroupExpr) ml).Methods [0];
 451                         ParameterData pd = TypeManager.GetParameterData (mb);
 452
 453                         Expression probe_ml = Expression.MemberLookup (
 454                                 ec.ContainerType, delegate_type, "Invoke", loc);
 455
 456                         if (!(probe_ml is MethodGroupExpr)) {
 457                                 Report.Error (-100, loc, "Internal error: could not find Invoke method!");
 458                                 return false;
 459                         }
 460
 461                         MethodBase probe_mb = ((MethodGroupExpr) probe_ml).Methods [0];
 462                         ParameterData probe_pd = TypeManager.GetParameterData (probe_mb);
 463
 464                         if (((MethodInfo) mb).ReturnType != ((MethodInfo) probe_mb).ReturnType)
 465                                 return false;
 466
 467                         if (pd.Count != probe_pd.Count)
 468                                 return false;
 469
 470                         for (int i = pd.Count; i > 0; ) {
 471                                 i--;
 472
 473                                 if (pd.ParameterType (i) != probe_pd.ParameterType (i) ||
 474                                     pd.ParameterModifier (i) != probe_pd.ParameterModifier (i))
 475                                         return false;
 476                         }
 477
 478                         return true;
 479                 }
 480
 481                 public static string FullDelegateDesc (Type del_type, MethodBase mb, ParameterData pd)
 482                 {
 483                         StringBuilder sb = new StringBuilder ();
 484                         sb.Append (TypeManager.CSharpName (((MethodInfo) mb).ReturnType));
 485                         sb.Append (" ");
 486                         sb.Append (TypeManager.CSharpName (del_type));
 487                         sb.Append (pd.GetSignatureForError ());
 488                         return sb.ToString ();
 489                 }
 490
 491                 // Hack around System.Reflection as found everywhere else
 492                 public override MemberList FindMembers (MemberTypes mt, BindingFlags bf,
 493                                                         MemberFilter filter, object criteria)
 494                 {
 495                         ArrayList members = new ArrayList ();
 496
 497                         if ((mt & MemberTypes.Method) != 0) {
 498                                 if (ConstructorBuilder != null)
 499                                 if (filter (ConstructorBuilder, criteria))
 500                                         members.Add (ConstructorBuilder);
 501
 502                                 if (InvokeBuilder != null)
 503                                 if (filter (InvokeBuilder, criteria))
 504                                         members.Add (InvokeBuilder);
 505
 506                                 if (BeginInvokeBuilder != null)
 507                                 if (filter (BeginInvokeBuilder, criteria))
 508                                         members.Add (BeginInvokeBuilder);
 509
 510                                 if (EndInvokeBuilder != null)
 511                                 if (filter (EndInvokeBuilder, criteria))
 512                                         members.Add (EndInvokeBuilder);
 513                         }
 514
 515                         return new MemberList (members);
 516                 }
 517
 518                 public override MemberCache MemberCache {
 519                         get {
 520                                 return null;
 521                         }
 522                 }
 523
 524                 public Expression InstanceExpression {
 525                         get {
 526                                 return instance_expr;
 527                         }
 528                         set {
 529                                 instance_expr = value;
 530                         }
 531                 }
 532
 533                 public MethodBase TargetMethod {
 534                         get {
 535                                 return delegate_method;
 536                         }
 537                         set {
 538                                 delegate_method = value;
 539                         }
 540                 }
 541
 542                 public Type TargetReturnType {
 543                         get {
 544                                 return ret_type;
 545                         }
 546                 }
 547
 548                 public override AttributeTargets AttributeTargets {
 549                         get {
 550                                 return AttributeTargets.Delegate;
 551                         }
 552                 }
 553
 554                 //
 555                 //   Represents header string for documentation comment.
 556                 //
 557                 public override string DocCommentHeader {
 558                         get { return "T:"; }
 559                 }
 560
 561         }
 562
 563         //
 564         // Base class for `NewDelegate' and `ImplicitDelegateCreation'
 565         //
 566         public abstract class DelegateCreation : Expression {
 567                 protected MethodBase constructor_method;
 568                 protected MethodBase delegate_method;
 569                 protected MethodGroupExpr method_group;
 570                 protected Expression delegate_instance_expression;
 571
 572                 protected DelegateCreation () {}
 573
 574                 public static void Error_NoMatchingMethodForDelegate (EmitContext ec, MethodGroupExpr mg, Type type, Location loc)
 575                 {
 576                         string method_desc;
 577                         MethodInfo found_method = (MethodInfo)mg.Methods [0];
 578
 579                         if (mg.Methods.Length > 1)
 580                                 method_desc = found_method.Name;
 581                         else
 582                                 method_desc = Invocation.FullMethodDesc (found_method);
 583
 584                         Expression invoke_method = Expression.MemberLookup (
 585                                 ec.ContainerType, type, "Invoke", MemberTypes.Method,
 586                                 Expression.AllBindingFlags, loc);
 587                         MethodInfo method = ((MethodGroupExpr) invoke_method).Methods [0] as MethodInfo;
 588
 589                         ParameterData param = TypeManager.GetParameterData (method);
 590                         string delegate_desc = Delegate.FullDelegateDesc (type, method, param);
 591
 592                         if (method.ReturnType != found_method.ReturnType) {
 593                                 Report.Error (407, loc, "`{0}' has the wrong return type to match the delegate `{1}'", method_desc, delegate_desc);
 594                         } else {
 595                                 Report.Error (123, loc, "Method `{0}' does not match delegate `{1}'", method_desc, delegate_desc);
 596                         }
 597                 }
 598
 599                 public override void Emit (EmitContext ec)
 600                 {
 601                         if (delegate_instance_expression == null || delegate_method.IsStatic)
 602                                 ec.ig.Emit (OpCodes.Ldnull);
 603                         else
 604                                 delegate_instance_expression.Emit (ec);
 605
 606                         if (delegate_method.IsVirtual && !method_group.IsBase) {
 607                                 ec.ig.Emit (OpCodes.Dup);
 608                                 ec.ig.Emit (OpCodes.Ldvirtftn, (MethodInfo) delegate_method);
 609                         } else
 610                                 ec.ig.Emit (OpCodes.Ldftn, (MethodInfo) delegate_method);
 611                         ec.ig.Emit (OpCodes.Newobj, (ConstructorInfo) constructor_method);
 612                 }
 613
 614                 protected bool ResolveConstructorMethod (EmitContext ec)
 615                 {
 616                         Expression ml = Expression.MemberLookup (
 617                                 ec.ContainerType, type, ".ctor", loc);
 618
 619                         if (!(ml is MethodGroupExpr)) {
 620                                 Report.Error (-100, loc, "Internal error: Could not find delegate constructor!");
 621                                 return false;
 622                         }
 623
 624                         constructor_method = ((MethodGroupExpr) ml).Methods [0];
 625                         return true;
 626                 }
 627
 628                 public static MethodBase ImplicitStandardConversionExists (MethodGroupExpr mg, Type targetType)
 629                 {
 630                         foreach (MethodInfo mi in mg.Methods){
 631                                 MethodBase mb = Delegate.VerifyMethod (mg.DeclaringType, targetType, mi, Location.Null);
 632                                 if (mb != null)
 633                                         return mb;
 634                         }
 635                         return null;
 636                 }
 637
 638                 protected Expression ResolveMethodGroupExpr (EmitContext ec, MethodGroupExpr mg)
 639                 {
 640                         delegate_method = ImplicitStandardConversionExists (mg, type);
 641
 642                         if (delegate_method == null) {
 643                                 Error_NoMatchingMethodForDelegate (ec, mg, type, loc);
 644                                 return null;
 645                         }
 646
 647                         //
 648                         // Check safe/unsafe of the delegate
 649                         //
 650                         if (!ec.InUnsafe){
 651                                 ParameterData param = TypeManager.GetParameterData (delegate_method);
 652                                 int count = param.Count;
 653
 654                                 for (int i = 0; i < count; i++){
 655                                         if (param.ParameterType (i).IsPointer){
 656                                                 Expression.UnsafeError (loc);
 657                                                 return null;
 658                                         }
 659                                 }
 660                         }
 661
 662                         //TODO: implement caching when performance will be low
 663                         IMethodData md = TypeManager.GetMethod (delegate_method);
 664                         if (md == null) {
 665                                 if (System.Attribute.GetCustomAttribute (delegate_method, TypeManager.conditional_attribute_type) != null) {
 666                                         Report.SymbolRelatedToPreviousError (delegate_method);
 667                                         Report.Error (1618, loc, "Cannot create delegate with `{0}' because it has a Conditional attribute", TypeManager.CSharpSignature (delegate_method));
 668                                         return null;
 669                                 }
 670                         } else {
 671                                 md.SetMemberIsUsed ();
 672                                 if (md.OptAttributes != null && md.OptAttributes.Search (TypeManager.conditional_attribute_type) != null) {
 673                                         Report.SymbolRelatedToPreviousError (delegate_method);
 674                                         Report.Error (1618, loc, "Cannot create delegate with `{0}' because it has a Conditional attribute", TypeManager.CSharpSignature (delegate_method));
 675                                         return null;
 676                                 }
 677                         }
 678
 679                         if (mg.InstanceExpression != null)
 680                                 delegate_instance_expression = mg.InstanceExpression.Resolve (ec);
 681                         else if (ec.IsStatic) {
 682                                 if (!delegate_method.IsStatic) {
 683                                         Report.Error (120, loc, "`{0}': An object reference is required for the nonstatic field, method or property",
 684                                                       TypeManager.CSharpSignature (delegate_method));
 685                                         return null;
 686                                 }
 687                                 delegate_instance_expression = null;
 688                         } else
 689                                 delegate_instance_expression = ec.GetThis (loc);
 690
 691                         if (delegate_instance_expression != null && delegate_instance_expression.Type.IsValueType)
 692                                 delegate_instance_expression = new BoxedCast (
 693                                         delegate_instance_expression, TypeManager.object_type);
 694
 695                         method_group = mg;
 696                         eclass = ExprClass.Value;
 697                         return this;
 698                 }
 699         }
 700
 701         //
 702         // Created from the conversion code
 703         //
 704         public class ImplicitDelegateCreation : DelegateCreation {
 705
 706                 ImplicitDelegateCreation (Type t, Location l)
 707                 {
 708                         type = t;
 709                         loc = l;
 710                 }
 711
 712                 public override Expression DoResolve (EmitContext ec)
 713                 {
 714                         return this;
 715                 }
 716
 717                 static public Expression Create (EmitContext ec, MethodGroupExpr mge,
 718                                                  Type target_type, Location loc)
 719                 {
 720                         ImplicitDelegateCreation d = new ImplicitDelegateCreation (target_type, loc);
 721                         if (!d.ResolveConstructorMethod (ec))
 722                                 return null;
 723
 724                         return d.ResolveMethodGroupExpr (ec, mge);
 725                 }
 726         }
 727
 728         //
 729         // A delegate-creation-expression, invoked from the `New' class
 730         //
 731         public class NewDelegate : DelegateCreation {
 732                 public ArrayList Arguments;
 733
 734                 //
 735                 // This constructor is invoked from the `New' expression
 736                 //
 737                 public NewDelegate (Type type, ArrayList Arguments, Location loc)
 738                 {
 739                         this.type = type;
 740                         this.Arguments = Arguments;
 741                         this.loc  = loc;
 742                 }
 743
 744                 public override Expression DoResolve (EmitContext ec)
 745                 {
 746                         if (Arguments == null || Arguments.Count != 1) {
 747                                 Report.Error (149, loc,
 748                                               "Method name expected");
 749                                 return null;
 750                         }
 751
 752                         if (!ResolveConstructorMethod (ec))
 753                                 return null;
 754
 755                         Argument a = (Argument) Arguments [0];
 756
 757                         if (!a.ResolveMethodGroup (ec, loc))
 758                                 return null;
 759
 760                         Expression e = a.Expr;
 761
 762                         if (e is AnonymousMethod && RootContext.Version != LanguageVersion.ISO_1)
 763                                 return ((AnonymousMethod) e).Compatible (ec, type, false);
 764
 765                         MethodGroupExpr mg = e as MethodGroupExpr;
 766                         if (mg != null)
 767                                 return ResolveMethodGroupExpr (ec, mg);
 768
 769                         Type e_type = e.Type;
 770
 771                         if (!TypeManager.IsDelegateType (e_type)) {
 772                                 Report.Error (149, loc, "Method name expected");
 773                                 return null;
 774                         }
 775
 776                         method_group = Expression.MemberLookup (
 777                                 ec.ContainerType, type, "Invoke", MemberTypes.Method,
 778                                 Expression.AllBindingFlags, loc) as MethodGroupExpr;
 779
 780                         if (method_group == null) {
 781                                 Report.Error (-200, loc, "Internal error ! Could not find Invoke method!");
 782                                 return null;
 783                         }
 784
 785                         // This is what MS' compiler reports. We could always choose
 786                         // to be more verbose and actually give delegate-level specifics
 787                         if (!Delegate.VerifyDelegate (ec, type, e_type, loc)) {
 788                                 Report.Error (29, loc, "Cannot implicitly convert type '" + e_type + "' " +
 789                                               "to type '" + type + "'");
 790                                 return null;
 791                         }
 792
 793                         delegate_instance_expression = e;
 794                         delegate_method = method_group.Methods [0];
 795
 796                         eclass = ExprClass.Value;
 797                         return this;
 798                 }
 799         }
 800
 801         public class DelegateInvocation : ExpressionStatement {
 802
 803                 public Expression InstanceExpr;
 804                 public ArrayList  Arguments;
 805
 806                 MethodBase method;
 807
 808                 public DelegateInvocation (Expression instance_expr, ArrayList args, Location loc)
 809                 {
 810                         this.InstanceExpr = instance_expr;
 811                         this.Arguments = args;
 812                         this.loc = loc;
 813                 }
 814
 815                 public override Expression DoResolve (EmitContext ec)
 816                 {
 817                         if (InstanceExpr is EventExpr) {
 818
 819                                 EventInfo ei = ((EventExpr) InstanceExpr).EventInfo;
 820
 821                                 Expression ml = MemberLookup (
 822                                         ec.ContainerType, ec.ContainerType, ei.Name,
 823                                         MemberTypes.Event, AllBindingFlags | BindingFlags.DeclaredOnly, loc);
 824
 825                                 if (ml == null) {
 826                                         //
 827                                         // If this is the case, then the Event does not belong
 828                                         // to this Type and so, according to the spec
 829                                         // cannot be accessed directly
 830                                         //
 831                                         // Note that target will not appear as an EventExpr
 832                                         // in the case it is being referenced within the same type container;
 833                                         // it will appear as a FieldExpr in that case.
 834                                         //
 835
 836                                         Assign.error70 (ei, loc);
 837                                         return null;
 838                                 }
 839                         }
 840
 841
 842                         Type del_type = InstanceExpr.Type;
 843                         if (del_type == null)
 844                                 return null;
 845
 846                         if (Arguments != null){
 847                                 foreach (Argument a in Arguments){
 848                                         if (!a.Resolve (ec, loc))
 849                                                 return null;
 850                                 }
 851                         }
 852
 853                         if (!Delegate.VerifyApplicability (ec, del_type, Arguments, loc))
 854                                 return null;
 855
 856                         Expression lookup = Expression.MemberLookup (ec.ContainerType, del_type, "Invoke", loc);
 857                         if (!(lookup is MethodGroupExpr)) {
 858                                 Report.Error (-100, loc, "Internal error: could not find Invoke method!");
 859                                 return null;
 860                         }
 861
 862                         method = ((MethodGroupExpr) lookup).Methods [0];
 863                         type = ((MethodInfo) method).ReturnType;
 864                         eclass = ExprClass.Value;
 865
 866                         return this;
 867                 }
 868
 869                 public override void Emit (EmitContext ec)
 870                 {
 871                         //
 872                         // Invocation on delegates call the virtual Invoke member
 873                         // so we are always `instance' calls
 874                         //
 875                         Invocation.EmitCall (ec, false, false, InstanceExpr, method, Arguments, loc);
 876                 }
 877
 878                 public override void EmitStatement (EmitContext ec)
 879                 {
 880                         Emit (ec);
 881                         //
 882                         // Pop the return value if there is one
 883                         //
 884                         if (method is MethodInfo){
 885                                 if (((MethodInfo) method).ReturnType != TypeManager.void_type)
 886                                         ec.ig.Emit (OpCodes.Pop);
 887                         }
 888                 }
 889
 890         }
 891 }