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 [] param_types;
  35                 Type ret_type;
  36
  37                 static string[] attribute_targets = new string [] { "type", "return" };
  38
  39                 Expression instance_expr;
  40                 MethodBase delegate_method;
  41                 ReturnParameter return_attributes;
  42
  43                 const int AllowedModifiers =
  44                         Modifiers.NEW |
  45                         Modifiers.PUBLIC |
  46                         Modifiers.PROTECTED |
  47                         Modifiers.INTERNAL |
  48                         Modifiers.UNSAFE |
  49                         Modifiers.PRIVATE;
  50
  51                 public Delegate (NamespaceEntry ns, TypeContainer parent, Expression type,
  52                                  int mod_flags, string name, Parameters param_list,
  53                                  Attributes attrs, Location l)
  54                         : base (ns, parent, name, attrs, l)
  55
  56                 {
  57                         this.ReturnType = type;
  58                         ModFlags        = Modifiers.Check (AllowedModifiers, mod_flags,
  59                                                            IsTopLevel ? Modifiers.INTERNAL :
  60                                                            Modifiers.PRIVATE, l);
  61                         Parameters      = param_list;
  62                 }
  63
  64                 public override void ApplyAttributeBuilder(Attribute a, CustomAttributeBuilder cb)
  65                 {
  66                         if (a.Target == AttributeTargets.ReturnValue) {
  67                                 if (return_attributes == null)
  68                                         return_attributes = new ReturnParameter (InvokeBuilder, Location);
  69
  70                                 return_attributes.ApplyAttributeBuilder (a, cb);
  71                                 return;
  72                         }
  73
  74                         base.ApplyAttributeBuilder (a, cb);
  75                 }
  76
  77                 public override TypeBuilder DefineType ()
  78                 {
  79                         if (TypeBuilder != null)
  80                                 return TypeBuilder;
  81
  82                         TypeAttributes attr = Modifiers.TypeAttr (ModFlags, IsTopLevel) |
  83                                 TypeAttributes.Class | TypeAttributes.Sealed;
  84
  85                         if (IsTopLevel) {
  86                                 if (TypeManager.NamespaceClash (Name, Location))
  87                                         return null;
  88
  89                                 ModuleBuilder builder = CodeGen.Module.Builder;
  90
  91                                 TypeBuilder = builder.DefineType (
  92                                         Name, attr, TypeManager.multicast_delegate_type);
  93                         } else {
  94                                 TypeBuilder builder = Parent.TypeBuilder;
  95
  96                                 string name = Name.Substring (1 + Name.LastIndexOf ('.'));
  97                                 TypeBuilder = builder.DefineNestedType (
  98                                         name, attr, TypeManager.multicast_delegate_type);
  99                         }
 100
 101                         TypeManager.AddDelegateType (Name, TypeBuilder, this);
 102
 103                         return TypeBuilder;
 104                 }
 105
 106                 public override bool DefineMembers (TypeContainer container)
 107                 {
 108                         return true;
 109                 }
 110
 111                 public override bool Define ()
 112                 {
 113                         MethodAttributes mattr;
 114                         int i;
 115                         EmitContext ec = new EmitContext (this, this, Location, null,
 116                                                           null, ModFlags, false);
 117
 118                         // FIXME: POSSIBLY make this static, as it is always constant
 119                         //
 120                         Type [] const_arg_types = new Type [2];
 121                         const_arg_types [0] = TypeManager.object_type;
 122                         const_arg_types [1] = TypeManager.intptr_type;
 123
 124                         mattr = MethodAttributes.RTSpecialName | MethodAttributes.SpecialName |
 125                                 MethodAttributes.HideBySig | MethodAttributes.Public;
 126
 127                         ConstructorBuilder = TypeBuilder.DefineConstructor (mattr,
 128                                                                             CallingConventions.Standard,
 129                                                                             const_arg_types);
 130
 131                         ConstructorBuilder.DefineParameter (1, ParameterAttributes.None, "object");
 132                         ConstructorBuilder.DefineParameter (2, ParameterAttributes.None, "method");
 133                         //
 134                         // HACK because System.Reflection.Emit is lame
 135                         //
 136                         //
 137                         // FIXME: POSSIBLY make these static, as they are always the same
 138                         Parameter [] fixed_pars = new Parameter [2];
 139                         fixed_pars [0] = new Parameter (null, null, Parameter.Modifier.NONE, null);
 140                         fixed_pars [1] = new Parameter (null, null, Parameter.Modifier.NONE, null);
 141                         Parameters const_parameters = new Parameters (fixed_pars, null, Location);
 142
 143                         TypeManager.RegisterMethod (
 144                                 ConstructorBuilder,
 145                                 new InternalParameters (const_arg_types, const_parameters),
 146                                 const_arg_types);
 147
 148
 149                         ConstructorBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 150
 151                         //
 152                         // Here the various methods like Invoke, BeginInvoke etc are defined
 153                         //
 154                         // First, call the `out of band' special method for
 155                         // defining recursively any types we need:
 156
 157                         if (!Parameters.ComputeAndDefineParameterTypes (this))
 158                                 return false;
 159
 160                         param_types = Parameters.GetParameterInfo (this);
 161                         if (param_types == null)
 162                                 return false;
 163
 164                         //
 165                         // Invoke method
 166                         //
 167
 168                         // Check accessibility
 169                         foreach (Type partype in param_types){
 170                                 if (!Parent.AsAccessible (partype, ModFlags)) {
 171                                         Report.Error (59, Location,
 172                                                       "Inconsistent accessibility: parameter type `" +
 173                                                       TypeManager.CSharpName (partype) + "` is less " +
 174                                                       "accessible than delegate `" + Name + "'");
 175                                         return false;
 176                                 }
 177                                 if (partype.IsPointer && !UnsafeOK (Parent))
 178                                         return false;
 179                         }
 180
 181                         ReturnType = ResolveTypeExpr (ReturnType, false, Location);
 182                         if (ReturnType == null)
 183                             return false;
 184
 185                         ret_type = ReturnType.Type;
 186                         if (ret_type == null)
 187                                 return false;
 188
 189                         if (!Parent.AsAccessible (ret_type, ModFlags)) {
 190                                 Report.Error (58, Location,
 191                                               "Inconsistent accessibility: return type `" +
 192                                               TypeManager.CSharpName (ret_type) + "` is less " +
 193                                               "accessible than delegate `" + Name + "'");
 194                                 return false;
 195                         }
 196
 197                         if (ret_type.IsPointer && !UnsafeOK (Parent))
 198                                 return false;
 199
 200                         //
 201                         // We don't have to check any others because they are all
 202                         // guaranteed to be accessible - they are standard types.
 203                         //
 204
 205                         CallingConventions cc = Parameters.GetCallingConvention ();
 206
 207                         mattr = MethodAttributes.Public | MethodAttributes.HideBySig | MethodAttributes.Virtual;
 208
 209                         InvokeBuilder = TypeBuilder.DefineMethod ("Invoke",
 210                                                                   mattr,
 211                                                                   cc,
 212                                                                   ret_type,
 213                                                                   param_types);
 214
 215                         //
 216                         // Define parameters, and count out/ref parameters
 217                         //
 218                         int out_params = 0;
 219                         i = 0;
 220                         if (Parameters.FixedParameters != null){
 221                                 int top = Parameters.FixedParameters.Length;
 222                                 Parameter p;
 223
 224                                 for (; i < top; i++) {
 225                                         p = Parameters.FixedParameters [i];
 226                                         p.DefineParameter (ec, InvokeBuilder, null, i + 1, Location);
 227
 228                                         if ((p.ModFlags & Parameter.Modifier.ISBYREF) != 0)
 229                                                 out_params++;
 230                                 }
 231                         }
 232                         if (Parameters.ArrayParameter != null){
 233                                 Parameter p = Parameters.ArrayParameter;
 234                                 p.DefineParameter (ec, InvokeBuilder, null, i + 1, Location);
 235                         }
 236
 237                         InvokeBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 238
 239                         TypeManager.RegisterMethod (InvokeBuilder,
 240                                                     new InternalParameters (Parent, Parameters),
 241                                                     param_types);
 242
 243                         //
 244                         // BeginInvoke
 245                         //
 246                         int params_num = param_types.Length;
 247                         Type [] async_param_types = new Type [params_num + 2];
 248
 249                         param_types.CopyTo (async_param_types, 0);
 250
 251                         async_param_types [params_num] = TypeManager.asynccallback_type;
 252                         async_param_types [params_num + 1] = TypeManager.object_type;
 253
 254                         mattr = MethodAttributes.Public | MethodAttributes.HideBySig |
 255                                 MethodAttributes.Virtual | MethodAttributes.NewSlot;
 256
 257                         BeginInvokeBuilder = TypeBuilder.DefineMethod ("BeginInvoke",
 258                                                                        mattr,
 259                                                                        cc,
 260                                                                        TypeManager.iasyncresult_type,
 261                                                                        async_param_types);
 262
 263                         i = 0;
 264                         if (Parameters.FixedParameters != null){
 265                                 int top = Parameters.FixedParameters.Length;
 266                                 Parameter p;
 267
 268                                 for (i = 0 ; i < top; i++) {
 269                                         p = Parameters.FixedParameters [i];
 270
 271                                         p.DefineParameter (ec, BeginInvokeBuilder, null, i + 1, Location);
 272                                 }
 273                         }
 274                         if (Parameters.ArrayParameter != null){
 275                                 Parameter p = Parameters.ArrayParameter;
 276                                 p.DefineParameter (ec, BeginInvokeBuilder, null, i + 1, Location);
 277
 278                                 i++;
 279                         }
 280
 281                         BeginInvokeBuilder.DefineParameter (i + 1, ParameterAttributes.None, "callback");
 282                         BeginInvokeBuilder.DefineParameter (i + 2, ParameterAttributes.None, "object");
 283
 284                         BeginInvokeBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 285
 286                         Parameter [] async_params = new Parameter [params_num + 2];
 287                         int n = 0;
 288                         if (Parameters.FixedParameters != null){
 289                                 Parameters.FixedParameters.CopyTo (async_params, 0);
 290                                 n = Parameters.FixedParameters.Length;
 291                         }
 292                         if (Parameters.ArrayParameter != null)
 293                                 async_params [n] = Parameters.ArrayParameter;
 294
 295                         async_params [params_num] = new Parameter (
 296                                 TypeManager.system_asynccallback_expr, "callback",
 297                                                                    Parameter.Modifier.NONE, null);
 298                         async_params [params_num + 1] = new Parameter (
 299                                 TypeManager.system_object_expr, "object",
 300                                                                    Parameter.Modifier.NONE, null);
 301
 302                         Parameters async_parameters = new Parameters (async_params, null, Location);
 303                         async_parameters.ComputeAndDefineParameterTypes (this);
 304
 305                         async_parameters.ComputeAndDefineParameterTypes (this);
 306                         TypeManager.RegisterMethod (BeginInvokeBuilder,
 307                                                     new InternalParameters (Parent, async_parameters),
 308                                                     async_param_types);
 309
 310                         //
 311                         // EndInvoke is a bit more interesting, all the parameters labeled as
 312                         // out or ref have to be duplicated here.
 313                         //
 314
 315                         Type [] end_param_types = new Type [out_params + 1];
 316                         Parameter [] end_params = new Parameter [out_params + 1];
 317                         int param = 0;
 318                         if (out_params > 0){
 319                                 int top = Parameters.FixedParameters.Length;
 320                                 for (i = 0; i < top; i++){
 321                                         Parameter p = Parameters.FixedParameters [i];
 322                                         if ((p.ModFlags & Parameter.Modifier.ISBYREF) == 0)
 323                                                 continue;
 324
 325                                         end_param_types [param] = param_types [i];
 326                                         end_params [param] = p;
 327                                         param++;
 328                                 }
 329                         }
 330                         end_param_types [out_params] = TypeManager.iasyncresult_type;
 331                         end_params [out_params] = new Parameter (TypeManager.system_iasyncresult_expr, "result", Parameter.Modifier.NONE, null);
 332
 333                         //
 334                         // Create method, define parameters, register parameters with type system
 335                         //
 336                         EndInvokeBuilder = TypeBuilder.DefineMethod ("EndInvoke", mattr, cc, ret_type, end_param_types);
 337                         EndInvokeBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 338
 339                         //
 340                         // EndInvoke: Label the parameters
 341                         //
 342                         EndInvokeBuilder.DefineParameter (out_params + 1, ParameterAttributes.None, "result");
 343                         for (i = 0; i < end_params.Length-1; i++){
 344                                 EndInvokeBuilder.DefineParameter (i + 1, end_params [i].Attributes, end_params [i].Name);
 345                         }
 346
 347                         Parameters end_parameters = new Parameters (end_params, null, Location);
 348                         end_parameters.ComputeAndDefineParameterTypes (this);
 349
 350                         TypeManager.RegisterMethod (
 351                                 EndInvokeBuilder,
 352                                 new InternalParameters (Parent, end_parameters),
 353                                 end_param_types);
 354
 355                         return true;
 356                 }
 357
 358                 public override void Emit ()
 359                 {
 360                         if (OptAttributes != null) {
 361                                 EmitContext ec = new EmitContext (
 362                                         Parent, this, Location, null, null, ModFlags, false);
 363                                 Parameters.LabelParameters (ec, InvokeBuilder, Location);
 364                                 OptAttributes.Emit (ec, this);
 365                         }
 366
 367                         base.Emit ();
 368                 }
 369
 370                 public override string[] ValidAttributeTargets {
 371                         get {
 372                                 return attribute_targets;
 373                         }
 374                 }
 375
 376                 //TODO: duplicate
 377                 protected override bool VerifyClsCompliance (DeclSpace ds)
 378                 {
 379                         if (!base.VerifyClsCompliance (ds)) {
 380                                 return false;
 381                         }
 382
 383                         AttributeTester.AreParametersCompliant (Parameters.FixedParameters, Location);
 384
 385                         if (!AttributeTester.IsClsCompliant (ReturnType.Type)) {
 386                                 Report.Error (3002, Location, "Return type of '{0}' is not CLS-compliant", GetSignatureForError ());
 387                         }
 388                         return true;
 389                 }
 390
 391                 /// <summary>
 392                 ///  Verifies whether the method in question is compatible with the delegate
 393                 ///  Returns the method itself if okay and null if not.
 394                 /// </summary>
 395                 public static MethodBase VerifyMethod (EmitContext ec, Type delegate_type, MethodBase mb,
 396                                                        Location loc)
 397                 {
 398                         ParameterData pd = Invocation.GetParameterData (mb);
 399
 400                         int pd_count = pd.Count;
 401
 402                         Expression ml = Expression.MemberLookup (
 403                                 ec, delegate_type, "Invoke", loc);
 404
 405                         if (!(ml is MethodGroupExpr)) {
 406                                 Report.Error (-100, loc, "Internal error: could not find Invoke method!");
 407                                 return null;
 408                         }
 409
 410                         MethodBase invoke_mb = ((MethodGroupExpr) ml).Methods [0];
 411
 412                         ParameterData invoke_pd = Invocation.GetParameterData (invoke_mb);
 413
 414                         if (invoke_pd.Count != pd_count)
 415                                 return null;
 416
 417                         for (int i = pd_count; i > 0; ) {
 418                                 i--;
 419
 420                                 if (invoke_pd.ParameterType (i) == pd.ParameterType (i) &&
 421                                     invoke_pd.ParameterModifier (i) == pd.ParameterModifier (i))
 422                                         continue;
 423                                 else {
 424                                         return null;
 425                                 }
 426                         }
 427
 428                         if (((MethodInfo) invoke_mb).ReturnType == ((MethodInfo) mb).ReturnType)
 429                                 return mb;
 430                         else
 431                                 return null;
 432                 }
 433
 434                 // <summary>
 435                 //  Verifies whether the invocation arguments are compatible with the
 436                 //  delegate's target method
 437                 // </summary>
 438                 public static bool VerifyApplicability (EmitContext ec, Type delegate_type,
 439                                                         ArrayList args, Location loc)
 440                 {
 441                         int arg_count;
 442
 443                         if (args == null)
 444                                 arg_count = 0;
 445                         else
 446                                 arg_count = args.Count;
 447
 448                         Expression ml = Expression.MemberLookup (
 449                                 ec, delegate_type, "Invoke", loc);
 450
 451                         if (!(ml is MethodGroupExpr)) {
 452                                 Report.Error (-100, loc, "Internal error: could not find Invoke method!" + delegate_type);
 453                                 return false;
 454                         }
 455
 456                         MethodBase mb = ((MethodGroupExpr) ml).Methods [0];
 457                         ParameterData pd = Invocation.GetParameterData (mb);
 458
 459                         int pd_count = pd.Count;
 460
 461                         bool params_method = (pd_count != 0) &&
 462                                 (pd.ParameterModifier (pd_count - 1) == Parameter.Modifier.PARAMS);
 463
 464                         if (!params_method && pd_count != arg_count) {
 465                                 Report.Error (1593, loc,
 466                                               "Delegate '" + delegate_type.ToString ()
 467                                               + "' does not take '" + arg_count + "' arguments");
 468                                 return false;
 469                         }
 470
 471                         //
 472                         // Consider the case:
 473                         //   delegate void FOO(param object[] args);
 474                         //   FOO f = new FOO(...);
 475                         //   f(new object[] {1, 2, 3});
 476                         //
 477                         // This should be treated like f(1,2,3).  This is done by ignoring the
 478                         // 'param' modifier for that invocation.  If that fails, then the
 479                         // 'param' modifier is considered.
 480                         //
 481                         // One issue is that 'VerifyArgumentsCompat' modifies the elements of
 482                         // the 'args' array.  However, the modifications appear idempotent.
 483                         // Normal 'Invocation's also have the same behaviour, implicitly.
 484                         //
 485
 486                         bool ans = false;
 487                         if (arg_count == pd_count)
 488                                 ans = Invocation.VerifyArgumentsCompat (
 489                                         ec, args, arg_count, mb, false,
 490                                         delegate_type, false, loc);
 491                         if (!ans && params_method)
 492                                 ans = Invocation.VerifyArgumentsCompat (
 493                                         ec, args, arg_count, mb, true,
 494                                         delegate_type, false, loc);
 495                         return ans;
 496                 }
 497
 498                 /// <summary>
 499                 ///  Verifies whether the delegate in question is compatible with this one in
 500                 ///  order to determine if instantiation from the same is possible.
 501                 /// </summary>
 502                 public static bool VerifyDelegate (EmitContext ec, Type delegate_type, Type probe_type, Location loc)
 503                 {
 504                         Expression ml = Expression.MemberLookup (
 505                                 ec, delegate_type, "Invoke", loc);
 506
 507                         if (!(ml is MethodGroupExpr)) {
 508                                 Report.Error (-100, loc, "Internal error: could not find Invoke method!");
 509                                 return false;
 510                         }
 511
 512                         MethodBase mb = ((MethodGroupExpr) ml).Methods [0];
 513                         ParameterData pd = Invocation.GetParameterData (mb);
 514
 515                         Expression probe_ml = Expression.MemberLookup (
 516                                 ec, delegate_type, "Invoke", loc);
 517
 518                         if (!(probe_ml is MethodGroupExpr)) {
 519                                 Report.Error (-100, loc, "Internal error: could not find Invoke method!");
 520                                 return false;
 521                         }
 522
 523                         MethodBase probe_mb = ((MethodGroupExpr) probe_ml).Methods [0];
 524                         ParameterData probe_pd = Invocation.GetParameterData (probe_mb);
 525
 526                         if (((MethodInfo) mb).ReturnType != ((MethodInfo) probe_mb).ReturnType)
 527                                 return false;
 528
 529                         if (pd.Count != probe_pd.Count)
 530                                 return false;
 531
 532                         for (int i = pd.Count; i > 0; ) {
 533                                 i--;
 534
 535                                 if (pd.ParameterType (i) != probe_pd.ParameterType (i) ||
 536                                     pd.ParameterModifier (i) != probe_pd.ParameterModifier (i))
 537                                         return false;
 538                         }
 539
 540                         return true;
 541                 }
 542
 543                 public static string FullDelegateDesc (Type del_type, MethodBase mb, ParameterData pd)
 544                 {
 545                         StringBuilder sb = new StringBuilder (TypeManager.CSharpName (((MethodInfo) mb).ReturnType));
 546
 547                         sb.Append (" " + del_type.ToString ());
 548                         sb.Append (" (");
 549
 550                         int length = pd.Count;
 551
 552                         for (int i = length; i > 0; ) {
 553                                 i--;
 554
 555                                 sb.Append (pd.ParameterDesc (length - i - 1));
 556                                 if (i != 0)
 557                                         sb.Append (", ");
 558                         }
 559
 560                         sb.Append (")");
 561                         return sb.ToString ();
 562
 563                 }
 564
 565                 // Hack around System.Reflection as found everywhere else
 566                 public override MemberList FindMembers (MemberTypes mt, BindingFlags bf,
 567                                                         MemberFilter filter, object criteria)
 568                 {
 569                         ArrayList members = new ArrayList ();
 570
 571                         if ((mt & MemberTypes.Method) != 0) {
 572                                 if (ConstructorBuilder != null)
 573                                 if (filter (ConstructorBuilder, criteria))
 574                                         members.Add (ConstructorBuilder);
 575
 576                                 if (InvokeBuilder != null)
 577                                 if (filter (InvokeBuilder, criteria))
 578                                         members.Add (InvokeBuilder);
 579
 580                                 if (BeginInvokeBuilder != null)
 581                                 if (filter (BeginInvokeBuilder, criteria))
 582                                         members.Add (BeginInvokeBuilder);
 583
 584                                 if (EndInvokeBuilder != null)
 585                                 if (filter (EndInvokeBuilder, criteria))
 586                                         members.Add (EndInvokeBuilder);
 587                         }
 588
 589                         return new MemberList (members);
 590                 }
 591
 592                 public override MemberCache MemberCache {
 593                         get {
 594                                 return null;
 595                         }
 596                 }
 597
 598                 public Expression InstanceExpression {
 599                         get {
 600                                 return instance_expr;
 601                         }
 602                         set {
 603                                 instance_expr = value;
 604                         }
 605                 }
 606
 607                 public MethodBase TargetMethod {
 608                         get {
 609                                 return delegate_method;
 610                         }
 611                         set {
 612                                 delegate_method = value;
 613                         }
 614                 }
 615
 616                 public Type TargetReturnType {
 617                         get {
 618                                 return ret_type;
 619                         }
 620                 }
 621
 622                 public Type [] ParameterTypes {
 623                         get {
 624                                 return param_types;
 625                         }
 626                 }
 627
 628                 public override AttributeTargets AttributeTargets {
 629                         get {
 630                                 return AttributeTargets.Delegate;
 631                         }
 632                 }
 633
 634                 protected override void VerifyObsoleteAttribute()
 635                 {
 636                         CheckUsageOfObsoleteAttribute (ret_type);
 637
 638                         foreach (Type type in param_types) {
 639                                 CheckUsageOfObsoleteAttribute (type);
 640                         }
 641                 }
 642         }
 643
 644         //
 645         // Base class for `NewDelegate' and `ImplicitDelegateCreation'
 646         //
 647         public abstract class DelegateCreation : Expression {
 648                 protected MethodBase constructor_method;
 649                 protected MethodBase delegate_method;
 650                 protected MethodGroupExpr method_group;
 651                 protected Expression delegate_instance_expression;
 652
 653                 public DelegateCreation () {}
 654
 655                 public static void Error_NoMatchingMethodForDelegate (EmitContext ec, MethodGroupExpr mg, Type type, Location loc)
 656                 {
 657                         string method_desc;
 658
 659                         if (mg.Methods.Length > 1)
 660                                 method_desc = mg.Methods [0].Name;
 661                         else
 662                                 method_desc = Invocation.FullMethodDesc (mg.Methods [0]);
 663
 664                         Expression invoke_method = Expression.MemberLookup (
 665                                 ec, type, "Invoke", MemberTypes.Method,
 666                                 Expression.AllBindingFlags, loc);
 667                         MethodBase method = ((MethodGroupExpr) invoke_method).Methods [0];
 668                         ParameterData param = Invocation.GetParameterData (method);
 669                         string delegate_desc = Delegate.FullDelegateDesc (type, method, param);
 670
 671                         Report.Error (123, loc, "Method '" + method_desc + "' does not " +
 672                                       "match delegate '" + delegate_desc + "'");
 673                 }
 674
 675                 public override void Emit (EmitContext ec)
 676                 {
 677                         if (delegate_instance_expression == null || delegate_method.IsStatic)
 678                                 ec.ig.Emit (OpCodes.Ldnull);
 679                         else
 680                                 delegate_instance_expression.Emit (ec);
 681
 682                         if (delegate_method.IsVirtual && !method_group.IsBase) {
 683                                 ec.ig.Emit (OpCodes.Dup);
 684                                 ec.ig.Emit (OpCodes.Ldvirtftn, (MethodInfo) delegate_method);
 685                         } else
 686                                 ec.ig.Emit (OpCodes.Ldftn, (MethodInfo) delegate_method);
 687                         ec.ig.Emit (OpCodes.Newobj, (ConstructorInfo) constructor_method);
 688                 }
 689
 690                 protected bool ResolveConstructorMethod (EmitContext ec)
 691                 {
 692                         Expression ml = Expression.MemberLookup (
 693                                 ec, type, ".ctor", loc);
 694
 695                         if (!(ml is MethodGroupExpr)) {
 696                                 Report.Error (-100, loc, "Internal error: Could not find delegate constructor!");
 697                                 return false;
 698                         }
 699
 700                         constructor_method = ((MethodGroupExpr) ml).Methods [0];
 701                         return true;
 702                 }
 703
 704                 protected Expression ResolveMethodGroupExpr (EmitContext ec, MethodGroupExpr mg)
 705                 {
 706                         foreach (MethodInfo mi in mg.Methods){
 707                                 delegate_method  = Delegate.VerifyMethod (ec, type, mi, loc);
 708
 709                                 if (delegate_method != null)
 710                                         break;
 711                         }
 712
 713                         if (delegate_method == null) {
 714                                 Error_NoMatchingMethodForDelegate (ec, mg, type, loc);
 715                                 return null;
 716                         }
 717
 718                         //
 719                         // Check safe/unsafe of the delegate
 720                         //
 721                         if (!ec.InUnsafe){
 722                                 ParameterData param = Invocation.GetParameterData (delegate_method);
 723                                 int count = param.Count;
 724
 725                                 for (int i = 0; i < count; i++){
 726                                         if (param.ParameterType (i).IsPointer){
 727                                                 Expression.UnsafeError (loc);
 728                                                 return null;
 729                                         }
 730                                 }
 731                         }
 732
 733                         //TODO: implement caching when performance will be low
 734                         IMethodData md = TypeManager.GetMethod (delegate_method);
 735                         if (md == null) {
 736                                 if (System.Attribute.GetCustomAttribute (delegate_method, TypeManager.conditional_attribute_type) != null) {
 737                                         Report.Error (1618, loc, "Cannot create delegate with '{0}' because it has a Conditional attribute", TypeManager.CSharpSignature (delegate_method));
 738                                 }
 739                         } else {
 740                                 if (md.OptAttributes != null && md.OptAttributes.Search (TypeManager.conditional_attribute_type, ec) != null) {
 741                                         Report.Error (1618, loc, "Cannot create delegate with '{0}' because it has a Conditional attribute", TypeManager.CSharpSignature (delegate_method));
 742                                 }
 743                         }
 744
 745                         if (mg.InstanceExpression != null)
 746                                 delegate_instance_expression = mg.InstanceExpression.Resolve (ec);
 747                         else if (ec.IsStatic) {
 748                                 if (!delegate_method.IsStatic) {
 749                                         Report.Error (120, loc,
 750                                                       "An object reference is required for the non-static method " +
 751                                                       delegate_method.Name);
 752                                         return null;
 753                                 }
 754                                 delegate_instance_expression = null;
 755                         } else
 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 (mg.InstanceExpression);
 760
 761                         method_group = mg;
 762                         eclass = ExprClass.Value;
 763                         return this;
 764                 }
 765         }
 766
 767         //
 768         // Created from the conversion code
 769         //
 770         public class ImplicitDelegateCreation : DelegateCreation {
 771
 772                 ImplicitDelegateCreation (Type t, Location l)
 773                 {
 774                         type = t;
 775                         loc = l;
 776                 }
 777
 778                 public override Expression DoResolve (EmitContext ec)
 779                 {
 780                         return this;
 781                 }
 782
 783                 static public Expression Create (EmitContext ec, MethodGroupExpr mge, Type target_type, Location loc)
 784                 {
 785                         ImplicitDelegateCreation d = new ImplicitDelegateCreation (target_type, loc);
 786                         if (d.ResolveConstructorMethod (ec))
 787                                 return d.ResolveMethodGroupExpr (ec, mge);
 788                         else
 789                                 return null;
 790                 }
 791         }
 792
 793         //
 794         // A delegate-creation-expression, invoked from the `New' class
 795         //
 796         public class NewDelegate : DelegateCreation {
 797                 public ArrayList Arguments;
 798
 799                 //
 800                 // This constructor is invoked from the `New' expression
 801                 //
 802                 public NewDelegate (Type type, ArrayList Arguments, Location loc)
 803                 {
 804                         this.type = type;
 805                         this.Arguments = Arguments;
 806                         this.loc  = loc;
 807                 }
 808
 809                 public override Expression DoResolve (EmitContext ec)
 810                 {
 811                         if (Arguments == null || Arguments.Count != 1) {
 812                                 Report.Error (149, loc,
 813                                               "Method name expected");
 814                                 return null;
 815                         }
 816
 817                         if (!ResolveConstructorMethod (ec))
 818                                 return null;
 819
 820                         Argument a = (Argument) Arguments [0];
 821
 822                         if (!a.ResolveMethodGroup (ec, loc))
 823                                 return null;
 824
 825                         Expression e = a.Expr;
 826
 827                         MethodGroupExpr mg = e as MethodGroupExpr;
 828                         if (mg != null)
 829                                 return ResolveMethodGroupExpr (ec, mg);
 830
 831                         Type e_type = e.Type;
 832
 833                         if (!TypeManager.IsDelegateType (e_type)) {
 834                                 e.Error_UnexpectedKind ("method");
 835                                 return null;
 836                         }
 837
 838                         method_group = Expression.MemberLookup (
 839                                 ec, type, "Invoke", MemberTypes.Method,
 840                                 Expression.AllBindingFlags, loc) as MethodGroupExpr;
 841
 842                         if (method_group == null) {
 843                                 Report.Error (-200, loc, "Internal error ! Could not find Invoke method!");
 844                                 return null;
 845                         }
 846
 847                         // This is what MS' compiler reports. We could always choose
 848                         // to be more verbose and actually give delegate-level specifics
 849                         if (!Delegate.VerifyDelegate (ec, type, e_type, loc)) {
 850                                 Report.Error (29, loc, "Cannot implicitly convert type '" + e_type + "' " +
 851                                               "to type '" + type + "'");
 852                                 return null;
 853                         }
 854
 855                         delegate_instance_expression = e;
 856                         delegate_method = method_group.Methods [0];
 857
 858                         eclass = ExprClass.Value;
 859                         return this;
 860                 }
 861         }
 862
 863         public class DelegateInvocation : ExpressionStatement {
 864
 865                 public Expression InstanceExpr;
 866                 public ArrayList  Arguments;
 867
 868                 MethodBase method;
 869
 870                 public DelegateInvocation (Expression instance_expr, ArrayList args, Location loc)
 871                 {
 872                         this.InstanceExpr = instance_expr;
 873                         this.Arguments = args;
 874                         this.loc = loc;
 875                 }
 876
 877                 public override Expression DoResolve (EmitContext ec)
 878                 {
 879                         if (InstanceExpr is EventExpr) {
 880
 881                                 EventInfo ei = ((EventExpr) InstanceExpr).EventInfo;
 882
 883                                 Expression ml = MemberLookup (
 884                                         ec, ec.ContainerType, ei.Name,
 885                                         MemberTypes.Event, AllBindingFlags | BindingFlags.DeclaredOnly, loc);
 886
 887                                 if (ml == null) {
 888                                         //
 889                                         // If this is the case, then the Event does not belong
 890                                         // to this Type and so, according to the spec
 891                                         // cannot be accessed directly
 892                                         //
 893                                         // Note that target will not appear as an EventExpr
 894                                         // in the case it is being referenced within the same type container;
 895                                         // it will appear as a FieldExpr in that case.
 896                                         //
 897
 898                                         Assign.error70 (ei, loc);
 899                                         return null;
 900                                 }
 901                         }
 902
 903
 904                         Type del_type = InstanceExpr.Type;
 905                         if (del_type == null)
 906                                 return null;
 907
 908                         if (Arguments != null){
 909                                 foreach (Argument a in Arguments){
 910                                         if (!a.Resolve (ec, loc))
 911                                                 return null;
 912                                 }
 913                         }
 914
 915                         if (!Delegate.VerifyApplicability (ec, del_type, Arguments, loc))
 916                                 return null;
 917
 918                         Expression lookup = Expression.MemberLookup (ec, del_type, "Invoke", loc);
 919                         if (!(lookup is MethodGroupExpr)) {
 920                                 Report.Error (-100, loc, "Internal error: could not find Invoke method!");
 921                                 return null;
 922                         }
 923
 924                         method = ((MethodGroupExpr) lookup).Methods [0];
 925                         type = ((MethodInfo) method).ReturnType;
 926                         eclass = ExprClass.Value;
 927
 928                         return this;
 929                 }
 930
 931                 public override void Emit (EmitContext ec)
 932                 {
 933                         //
 934                         // Invocation on delegates call the virtual Invoke member
 935                         // so we are always `instance' calls
 936                         //
 937                         Invocation.EmitCall (ec, false, false, InstanceExpr, method, Arguments, loc);
 938                 }
 939
 940                 public override void EmitStatement (EmitContext ec)
 941                 {
 942                         Emit (ec);
 943                         //
 944                         // Pop the return value if there is one
 945                         //
 946                         if (method is MethodInfo){
 947                                 if (((MethodInfo) method).ReturnType != TypeManager.void_type)
 948                                         ec.ig.Emit (OpCodes.Pop);
 949                         }
 950                 }
 951
 952         }
 953 }