mcs/mcs/delegate.cs

   1 //
   2 // delegate.cs: Delegate Handler
   3 //
   4 // Authors:
   5 //     Ravi Pratap (ravi@ximian.com)
   6 //     Miguel de Icaza (miguel@ximian.com)
   7 //     Marek Safar (marek.safar@gmail.com)
   8 //
   9 // Dual licensed under the terms of the MIT X11 or GNU GPL
  10 //
  11 // Copyright 2001 Ximian, Inc (http://www.ximian.com)
  12 // Copyright 2003-2009 Novell, Inc (http://www.novell.com)
  13 // Copyright 2011 Xamarin Inc
  14 //
  15
  16 using System;
  17
  18 #if STATIC
  19 using SecurityType = System.Collections.Generic.List<IKVM.Reflection.Emit.CustomAttributeBuilder>;
  20 using IKVM.Reflection;
  21 using IKVM.Reflection.Emit;
  22 #else
  23 using SecurityType = System.Collections.Generic.Dictionary<System.Security.Permissions.SecurityAction, System.Security.PermissionSet>;
  24 using System.Reflection;
  25 using System.Reflection.Emit;
  26 #endif
  27
  28 namespace Mono.CSharp {
  29
  30         //
  31         // Delegate container implementation
  32         //
  33         public class Delegate : TypeDefinition, IParametersMember
  34         {
  35                 FullNamedExpression ReturnType;
  36                 readonly ParametersCompiled parameters;
  37
  38                 Constructor Constructor;
  39                 Method InvokeBuilder;
  40                 Method BeginInvokeBuilder;
  41                 Method EndInvokeBuilder;
  42
  43                 static readonly string[] attribute_targets = new string [] { "type", "return" };
  44
  45                 public static readonly string InvokeMethodName = "Invoke";
  46
  47                 Expression instance_expr;
  48                 ReturnParameter return_attributes;
  49
  50                 SecurityType declarative_security;
  51
  52                 const Modifiers MethodModifiers = Modifiers.PUBLIC | Modifiers.VIRTUAL;
  53
  54                 const Modifiers AllowedModifiers =
  55                         Modifiers.NEW |
  56                         Modifiers.PUBLIC |
  57                         Modifiers.PROTECTED |
  58                         Modifiers.INTERNAL |
  59                         Modifiers.UNSAFE |
  60                         Modifiers.PRIVATE;
  61
  62                 public Delegate (TypeContainer parent, FullNamedExpression type, Modifiers mod_flags, MemberName name, ParametersCompiled param_list,
  63                                  Attributes attrs)
  64                         : base (parent, name, attrs, MemberKind.Delegate)
  65
  66                 {
  67                         this.ReturnType = type;
  68                         ModFlags        = ModifiersExtensions.Check (AllowedModifiers, mod_flags,
  69                                                            IsTopLevel ? Modifiers.INTERNAL :
  70                                                            Modifiers.PRIVATE, name.Location, Report);
  71                         parameters      = param_list;
  72                         spec = new TypeSpec (Kind, null, this, null, ModFlags | Modifiers.SEALED);
  73                 }
  74
  75                 #region Properties
  76                 public TypeSpec MemberType {
  77                         get {
  78                                 return ReturnType.Type;
  79                         }
  80                 }
  81
  82                 public AParametersCollection Parameters {
  83                         get {
  84                                 return parameters;
  85                         }
  86                 }
  87
  88                 public FullNamedExpression TypExpression {
  89                         get {
  90                                 return ReturnType;
  91                         }
  92                 }
  93
  94                 #endregion
  95
  96                 public override void Accept (StructuralVisitor visitor)
  97                 {
  98                         visitor.Visit (this);
  99                 }
 100
 101                 public override void ApplyAttributeBuilder (Attribute a, MethodSpec ctor, byte[] cdata, PredefinedAttributes pa)
 102                 {
 103                         if (a.Target == AttributeTargets.ReturnValue) {
 104                                 if (return_attributes == null)
 105                                         return_attributes = new ReturnParameter (this, InvokeBuilder.MethodBuilder, Location);
 106
 107                                 return_attributes.ApplyAttributeBuilder (a, ctor, cdata, pa);
 108                                 return;
 109                         }
 110
 111                         if (a.IsValidSecurityAttribute ()) {
 112                                 a.ExtractSecurityPermissionSet (ctor, ref declarative_security);
 113                                 return;
 114                         }
 115
 116                         base.ApplyAttributeBuilder (a, ctor, cdata, pa);
 117                 }
 118
 119                 public override AttributeTargets AttributeTargets {
 120                         get {
 121                                 return AttributeTargets.Delegate;
 122                         }
 123                 }
 124
 125                 protected override bool DoDefineMembers ()
 126                 {
 127                         var builtin_types = Compiler.BuiltinTypes;
 128
 129                         var ctor_parameters = ParametersCompiled.CreateFullyResolved (
 130                                 new [] {
 131                                         new Parameter (new TypeExpression (builtin_types.Object, Location), "object", Parameter.Modifier.NONE, null, Location),
 132                                         new Parameter (new TypeExpression (builtin_types.IntPtr, Location), "method", Parameter.Modifier.NONE, null, Location)
 133                                 },
 134                                 new [] {
 135                                         builtin_types.Object,
 136                                         builtin_types.IntPtr
 137                                 }
 138                         );
 139
 140                         Constructor = new Constructor (this, Constructor.ConstructorName,
 141                                 Modifiers.PUBLIC, null, ctor_parameters, Location);
 142                         Constructor.Define ();
 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                         var p = parameters;
 151
 152                         if (!p.Resolve (this))
 153                                 return false;
 154
 155                         //
 156                         // Invoke method
 157                         //
 158
 159                         // Check accessibility
 160                         foreach (var partype in p.Types) {
 161                                 if (!IsAccessibleAs (partype)) {
 162                                         Report.SymbolRelatedToPreviousError (partype);
 163                                         Report.Error (59, Location,
 164                                                 "Inconsistent accessibility: parameter type `{0}' is less accessible than delegate `{1}'",
 165                                                 partype.GetSignatureForError (), GetSignatureForError ());
 166                                 }
 167                         }
 168
 169                         var ret_type = ReturnType.ResolveAsType (this);
 170                         if (ret_type == null)
 171                                 return false;
 172
 173                         //
 174                         // We don't have to check any others because they are all
 175                         // guaranteed to be accessible - they are standard types.
 176                         //
 177                         if (!IsAccessibleAs (ret_type)) {
 178                                 Report.SymbolRelatedToPreviousError (ret_type);
 179                                 Report.Error (58, Location,
 180                                                   "Inconsistent accessibility: return type `" +
 181                                                   ret_type.GetSignatureForError () + "' is less " +
 182                                                   "accessible than delegate `" + GetSignatureForError () + "'");
 183                                 return false;
 184                         }
 185
 186                         CheckProtectedModifier ();
 187
 188                         if (Compiler.Settings.StdLib && ret_type.IsSpecialRuntimeType) {
 189                                 Method.Error1599 (Location, ret_type, Report);
 190                                 return false;
 191                         }
 192
 193                         VarianceDecl.CheckTypeVariance (ret_type, Variance.Covariant, this);
 194
 195                         var resolved_rt = new TypeExpression (ret_type, Location);
 196                         InvokeBuilder = new Method (this, resolved_rt, MethodModifiers, new MemberName (InvokeMethodName), p, null);
 197                         InvokeBuilder.Define ();
 198
 199                         //
 200                         // Don't emit async method for compiler generated delegates (e.g. dynamic site containers)
 201                         //
 202                         if (!IsCompilerGenerated) {
 203                                 DefineAsyncMethods (resolved_rt);
 204                         }
 205
 206                         return true;
 207                 }
 208
 209                 void DefineAsyncMethods (TypeExpression returnType)
 210                 {
 211                         var iasync_result = Module.PredefinedTypes.IAsyncResult;
 212                         var async_callback = Module.PredefinedTypes.AsyncCallback;
 213
 214                         //
 215                         // It's ok when async types don't exist, the delegate will have Invoke method only
 216                         //
 217                         if (!iasync_result.Define () || !async_callback.Define ())
 218                                 return;
 219
 220                         //
 221                         // BeginInvoke
 222                         //
 223                         ParametersCompiled async_parameters;
 224                         if (Parameters.Count == 0) {
 225                                 async_parameters = ParametersCompiled.EmptyReadOnlyParameters;
 226                         } else {
 227                                 var compiled = new Parameter[Parameters.Count];
 228                                 for (int i = 0; i < compiled.Length; ++i) {
 229                                         var p = parameters[i];
 230                                         compiled[i] = new Parameter (new TypeExpression (parameters.Types[i], Location),
 231                                                 p.Name,
 232                                                 p.ModFlags & Parameter.Modifier.RefOutMask,
 233                                                 p.OptAttributes == null ? null : p.OptAttributes.Clone (), Location);
 234                                 }
 235
 236                                 async_parameters = new ParametersCompiled (compiled);
 237                         }
 238
 239                         async_parameters = ParametersCompiled.MergeGenerated (Compiler, async_parameters, false,
 240                                 new Parameter[] {
 241                                         new Parameter (new TypeExpression (async_callback.TypeSpec, Location), "callback", Parameter.Modifier.NONE, null, Location),
 242                                         new Parameter (new TypeExpression (Compiler.BuiltinTypes.Object, Location), "object", Parameter.Modifier.NONE, null, Location)
 243                                 },
 244                                 new [] {
 245                                         async_callback.TypeSpec,
 246                                         Compiler.BuiltinTypes.Object
 247                                 }
 248                         );
 249
 250                         BeginInvokeBuilder = new Method (this,
 251                                 new TypeExpression (iasync_result.TypeSpec, Location), MethodModifiers,
 252                                 new MemberName ("BeginInvoke"), async_parameters, null);
 253                         BeginInvokeBuilder.Define ();
 254
 255                         //
 256                         // EndInvoke is a bit more interesting, all the parameters labeled as
 257                         // out or ref have to be duplicated here.
 258                         //
 259
 260                         //
 261                         // Define parameters, and count out/ref parameters
 262                         //
 263                         ParametersCompiled end_parameters;
 264                         int out_params = 0;
 265
 266                         foreach (Parameter p in Parameters.FixedParameters) {
 267                                 if ((p.ModFlags & Parameter.Modifier.RefOutMask) != 0)
 268                                         ++out_params;
 269                         }
 270
 271                         if (out_params > 0) {
 272                                 Parameter[] end_params = new Parameter[out_params];
 273
 274                                 int param = 0;
 275                                 for (int i = 0; i < Parameters.FixedParameters.Length; ++i) {
 276                                         Parameter p = parameters [i];
 277                                         if ((p.ModFlags & Parameter.Modifier.RefOutMask) == 0)
 278                                                 continue;
 279
 280                                         end_params [param++] = new Parameter (new TypeExpression (p.Type, Location),
 281                                                 p.Name,
 282                                                 p.ModFlags & Parameter.Modifier.RefOutMask,
 283                                                 p.OptAttributes == null ? null : p.OptAttributes.Clone (), Location);
 284                                 }
 285
 286                                 end_parameters = new ParametersCompiled (end_params);
 287                         } else {
 288                                 end_parameters = ParametersCompiled.EmptyReadOnlyParameters;
 289                         }
 290
 291                         end_parameters = ParametersCompiled.MergeGenerated (Compiler, end_parameters, false,
 292                                 new Parameter (
 293                                         new TypeExpression (iasync_result.TypeSpec, Location),
 294                                         "result", Parameter.Modifier.NONE, null, Location),
 295                                 iasync_result.TypeSpec);
 296
 297                         //
 298                         // Create method, define parameters, register parameters with type system
 299                         //
 300                         EndInvokeBuilder = new Method (this, returnType, MethodModifiers, new MemberName ("EndInvoke"), end_parameters, null);
 301                         EndInvokeBuilder.Define ();
 302                 }
 303
 304                 public override void PrepareEmit ()
 305                 {
 306                         if ((caching_flags & Flags.CloseTypeCreated) != 0)
 307                                 return;
 308
 309                         InvokeBuilder.PrepareEmit ();
 310                         if (BeginInvokeBuilder != null) {
 311                                 BeginInvokeBuilder.PrepareEmit ();
 312                                 EndInvokeBuilder.PrepareEmit ();
 313                         }
 314                 }
 315
 316                 public override void Emit ()
 317                 {
 318                         base.Emit ();
 319
 320                         if (declarative_security != null) {
 321                                 foreach (var de in declarative_security) {
 322 #if STATIC
 323                                         TypeBuilder.__AddDeclarativeSecurity (de);
 324 #else
 325                                         TypeBuilder.AddDeclarativeSecurity (de.Key, de.Value);
 326 #endif
 327                                 }
 328                         }
 329
 330                         if (ReturnType.Type != null) {
 331                                 if (ReturnType.Type.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
 332                                         return_attributes = new ReturnParameter (this, InvokeBuilder.MethodBuilder, Location);
 333                                         Module.PredefinedAttributes.Dynamic.EmitAttribute (return_attributes.Builder);
 334                                 } else if (ReturnType.Type.HasDynamicElement) {
 335                                         return_attributes = new ReturnParameter (this, InvokeBuilder.MethodBuilder, Location);
 336                                         Module.PredefinedAttributes.Dynamic.EmitAttribute (return_attributes.Builder, ReturnType.Type, Location);
 337                                 }
 338
 339                                 ConstraintChecker.Check (this, ReturnType.Type, ReturnType.Location);
 340                         }
 341
 342                         Constructor.ParameterInfo.ApplyAttributes (this, Constructor.ConstructorBuilder);
 343                         Constructor.ConstructorBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 344
 345                         parameters.CheckConstraints (this);
 346                         parameters.ApplyAttributes (this, InvokeBuilder.MethodBuilder);
 347                         InvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 348
 349                         if (BeginInvokeBuilder != null) {
 350                                 BeginInvokeBuilder.ParameterInfo.ApplyAttributes (this, BeginInvokeBuilder.MethodBuilder);
 351                                 EndInvokeBuilder.ParameterInfo.ApplyAttributes (this, EndInvokeBuilder.MethodBuilder);
 352
 353                                 BeginInvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 354                                 EndInvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 355                         }
 356                 }
 357
 358                 protected override TypeSpec[] ResolveBaseTypes (out FullNamedExpression base_class)
 359                 {
 360                         base_type = Compiler.BuiltinTypes.MulticastDelegate;
 361                         base_class = null;
 362                         return null;
 363                 }
 364
 365                 protected override TypeAttributes TypeAttr {
 366                         get {
 367                                 return base.TypeAttr | TypeAttributes.Class | TypeAttributes.Sealed;
 368                         }
 369                 }
 370
 371                 public override string[] ValidAttributeTargets {
 372                         get {
 373                                 return attribute_targets;
 374                         }
 375                 }
 376
 377                 //TODO: duplicate
 378                 protected override bool VerifyClsCompliance ()
 379                 {
 380                         if (!base.VerifyClsCompliance ()) {
 381                                 return false;
 382                         }
 383
 384                         parameters.VerifyClsCompliance (this);
 385
 386                         if (!InvokeBuilder.MemberType.IsCLSCompliant ()) {
 387                                 Report.Warning (3002, 1, Location, "Return type of `{0}' is not CLS-compliant",
 388                                         GetSignatureForError ());
 389                         }
 390                         return true;
 391                 }
 392
 393
 394                 public static MethodSpec GetConstructor (TypeSpec delType)
 395                 {
 396                         var ctor = MemberCache.FindMember (delType, MemberFilter.Constructor (null), BindingRestriction.DeclaredOnly);
 397                         return (MethodSpec) ctor;
 398                 }
 399
 400                 //
 401                 // Returns the "Invoke" from a delegate type
 402                 //
 403                 public static MethodSpec GetInvokeMethod (TypeSpec delType)
 404                 {
 405                         var invoke = MemberCache.FindMember (delType,
 406                                 MemberFilter.Method (InvokeMethodName, 0, null, null),
 407                                 BindingRestriction.DeclaredOnly);
 408
 409                         return (MethodSpec) invoke;
 410                 }
 411
 412                 public static AParametersCollection GetParameters (TypeSpec delType)
 413                 {
 414                         var invoke_mb = GetInvokeMethod (delType);
 415                         return invoke_mb.Parameters;
 416                 }
 417
 418                 //
 419                 // 15.2 Delegate compatibility
 420                 //
 421                 public static bool IsTypeCovariant (ResolveContext rc, TypeSpec a, TypeSpec b)
 422                 {
 423                         //
 424                         // For each value parameter (a parameter with no ref or out modifier), an
 425                         // identity conversion or implicit reference conversion exists from the
 426                         // parameter type in D to the corresponding parameter type in M
 427                         //
 428                         if (a == b)
 429                                 return true;
 430
 431                         if (rc.Module.Compiler.Settings.Version == LanguageVersion.ISO_1)
 432                                 return false;
 433
 434                         if (a.IsGenericParameter && b.IsGenericParameter)
 435                                 return a == b;
 436
 437                         return Convert.ImplicitReferenceConversionExists (a, b);
 438                 }
 439
 440                 public static string FullDelegateDesc (MethodSpec invoke_method)
 441                 {
 442                         return TypeManager.GetFullNameSignature (invoke_method).Replace (".Invoke", "");
 443                 }
 444
 445                 public Expression InstanceExpression {
 446                         get {
 447                                 return instance_expr;
 448                         }
 449                         set {
 450                                 instance_expr = value;
 451                         }
 452                 }
 453         }
 454
 455         //
 456         // Base class for `NewDelegate' and `ImplicitDelegateCreation'
 457         //
 458         public abstract class DelegateCreation : Expression, OverloadResolver.IErrorHandler
 459         {
 460                 bool conditional_access_receiver;
 461                 protected MethodSpec constructor_method;
 462                 protected MethodGroupExpr method_group;
 463
 464                 public bool AllowSpecialMethodsInvocation { get; set; }
 465
 466                 public override bool ContainsEmitWithAwait ()
 467                 {
 468                         var instance = method_group.InstanceExpression;
 469                         return instance != null && instance.ContainsEmitWithAwait ();
 470                 }
 471
 472                 public static Arguments CreateDelegateMethodArguments (ResolveContext rc, AParametersCollection pd, TypeSpec[] types, Location loc)
 473                 {
 474                         Arguments delegate_arguments = new Arguments (pd.Count);
 475                         for (int i = 0; i < pd.Count; ++i) {
 476                                 Argument.AType atype_modifier;
 477                                 switch (pd.FixedParameters [i].ModFlags & Parameter.Modifier.RefOutMask) {
 478                                 case Parameter.Modifier.REF:
 479                                         atype_modifier = Argument.AType.Ref;
 480                                         break;
 481                                 case Parameter.Modifier.OUT:
 482                                         atype_modifier = Argument.AType.Out;
 483                                         break;
 484                                 default:
 485                                         atype_modifier = 0;
 486                                         break;
 487                                 }
 488
 489                                 var ptype = types[i];
 490                                 if (ptype.BuiltinType == BuiltinTypeSpec.Type.Dynamic)
 491                                         ptype = rc.BuiltinTypes.Object;
 492
 493                                 delegate_arguments.Add (new Argument (new TypeExpression (ptype, loc), atype_modifier));
 494                         }
 495
 496                         return delegate_arguments;
 497                 }
 498
 499                 public override Expression CreateExpressionTree (ResolveContext ec)
 500                 {
 501                         MemberAccess ma = new MemberAccess (new MemberAccess (new QualifiedAliasMember ("global", "System", loc), "Delegate", loc), "CreateDelegate", loc);
 502
 503                         Arguments args = new Arguments (3);
 504                         args.Add (new Argument (new TypeOf (type, loc)));
 505
 506                         if (method_group.InstanceExpression == null)
 507                                 args.Add (new Argument (new NullLiteral (loc)));
 508                         else
 509                                 args.Add (new Argument (method_group.InstanceExpression));
 510
 511                         args.Add (new Argument (method_group.CreateExpressionTree (ec)));
 512                         Expression e = new Invocation (ma, args).Resolve (ec);
 513                         if (e == null)
 514                                 return null;
 515
 516                         e = Convert.ExplicitConversion (ec, e, type, loc);
 517                         if (e == null)
 518                                 return null;
 519
 520                         return e.CreateExpressionTree (ec);
 521                 }
 522
 523                 protected override Expression DoResolve (ResolveContext ec)
 524                 {
 525                         constructor_method = Delegate.GetConstructor (type);
 526
 527                         var invoke_method = Delegate.GetInvokeMethod (type);
 528
 529                         if (!ec.HasSet (ResolveContext.Options.ConditionalAccessReceiver)) {
 530                                 if (method_group.HasConditionalAccess ()) {
 531                                         conditional_access_receiver = true;
 532                                         ec.Set (ResolveContext.Options.ConditionalAccessReceiver);
 533                                 }
 534                         }
 535
 536                         Arguments arguments = CreateDelegateMethodArguments (ec, invoke_method.Parameters, invoke_method.Parameters.Types, loc);
 537                         method_group = method_group.OverloadResolve (ec, ref arguments, this, OverloadResolver.Restrictions.CovariantDelegate);
 538
 539                         if (conditional_access_receiver)
 540                                 ec.With (ResolveContext.Options.ConditionalAccessReceiver, false);
 541
 542                         if (method_group == null)
 543                                 return null;
 544
 545                         var delegate_method = method_group.BestCandidate;
 546
 547                         if (delegate_method.DeclaringType.IsNullableType) {
 548                                 ec.Report.Error (1728, loc, "Cannot create delegate from method `{0}' because it is a member of System.Nullable<T> type",
 549                                         delegate_method.GetSignatureForError ());
 550                                 return null;
 551                         }
 552
 553                         if (!AllowSpecialMethodsInvocation)
 554                                 Invocation.IsSpecialMethodInvocation (ec, delegate_method, loc);
 555
 556                         ExtensionMethodGroupExpr emg = method_group as ExtensionMethodGroupExpr;
 557                         if (emg != null) {
 558                                 method_group.InstanceExpression = emg.ExtensionExpression;
 559                                 TypeSpec e_type = emg.ExtensionExpression.Type;
 560                                 if (TypeSpec.IsValueType (e_type)) {
 561                                         ec.Report.Error (1113, loc, "Extension method `{0}' of value type `{1}' cannot be used to create delegates",
 562                                                 delegate_method.GetSignatureForError (), e_type.GetSignatureForError ());
 563                                 }
 564                         }
 565
 566                         TypeSpec rt = method_group.BestCandidateReturnType;
 567                         if (rt.BuiltinType == BuiltinTypeSpec.Type.Dynamic)
 568                                 rt = ec.BuiltinTypes.Object;
 569
 570                         if (!Delegate.IsTypeCovariant (ec, rt, invoke_method.ReturnType)) {
 571                                 Expression ret_expr = new TypeExpression (delegate_method.ReturnType, loc);
 572                                 Error_ConversionFailed (ec, delegate_method, ret_expr);
 573                         }
 574
 575                         if (method_group.IsConditionallyExcluded) {
 576                                 ec.Report.SymbolRelatedToPreviousError (delegate_method);
 577                                 MethodOrOperator m = delegate_method.MemberDefinition as MethodOrOperator;
 578                                 if (m != null && m.IsPartialDefinition) {
 579                                         ec.Report.Error (762, loc, "Cannot create delegate from partial method declaration `{0}'",
 580                                                 delegate_method.GetSignatureForError ());
 581                                 } else {
 582                                         ec.Report.Error (1618, loc, "Cannot create delegate with `{0}' because it has a Conditional attribute",
 583                                                 TypeManager.CSharpSignature (delegate_method));
 584                                 }
 585                         }
 586
 587                         var expr = method_group.InstanceExpression;
 588                         if (expr != null && (expr.Type.IsGenericParameter || !TypeSpec.IsReferenceType (expr.Type)))
 589                                 method_group.InstanceExpression = new BoxedCast (expr, ec.BuiltinTypes.Object);
 590
 591                         eclass = ExprClass.Value;
 592                         return this;
 593                 }
 594
 595                 public override void Emit (EmitContext ec)
 596                 {
 597                         if (conditional_access_receiver)
 598                                 ec.ConditionalAccess = new ConditionalAccessContext (type, ec.DefineLabel ());
 599
 600                         if (method_group.InstanceExpression == null) {
 601                                 ec.EmitNull ();
 602                         } else {
 603                                 var ie = new InstanceEmitter (method_group.InstanceExpression, false);
 604                                 ie.Emit (ec, method_group.ConditionalAccess);
 605                         }
 606
 607                         var delegate_method = method_group.BestCandidate;
 608
 609                         // Any delegate must be sealed
 610                         if (!delegate_method.DeclaringType.IsDelegate && delegate_method.IsVirtual && !method_group.IsBase) {
 611                                 ec.Emit (OpCodes.Dup);
 612                                 ec.Emit (OpCodes.Ldvirtftn, delegate_method);
 613                         } else {
 614                                 ec.Emit (OpCodes.Ldftn, delegate_method);
 615                         }
 616
 617                         ec.Emit (OpCodes.Newobj, constructor_method);
 618
 619                         if (conditional_access_receiver)
 620                                 ec.CloseConditionalAccess (null);
 621                 }
 622
 623                 public override void FlowAnalysis (FlowAnalysisContext fc)
 624                 {
 625                         base.FlowAnalysis (fc);
 626                         method_group.FlowAnalysis (fc);
 627
 628                         if (conditional_access_receiver)
 629                                 fc.ConditionalAccessEnd ();
 630                 }
 631
 632                 void Error_ConversionFailed (ResolveContext ec, MethodSpec method, Expression return_type)
 633                 {
 634                         var invoke_method = Delegate.GetInvokeMethod (type);
 635                         string member_name = method_group.InstanceExpression != null ?
 636                                 Delegate.FullDelegateDesc (method) :
 637                                 TypeManager.GetFullNameSignature (method);
 638
 639                         ec.Report.SymbolRelatedToPreviousError (type);
 640                         ec.Report.SymbolRelatedToPreviousError (method);
 641                         if (ec.Module.Compiler.Settings.Version == LanguageVersion.ISO_1) {
 642                                 ec.Report.Error (410, loc, "A method or delegate `{0} {1}' parameters and return type must be same as delegate `{2} {3}' parameters and return type",
 643                                         method.ReturnType.GetSignatureForError (), member_name,
 644                                         invoke_method.ReturnType.GetSignatureForError (), Delegate.FullDelegateDesc (invoke_method));
 645                                 return;
 646                         }
 647
 648                         if (return_type == null) {
 649                                 ec.Report.Error (123, loc, "A method or delegate `{0}' parameters do not match delegate `{1}' parameters",
 650                                         member_name, Delegate.FullDelegateDesc (invoke_method));
 651                                 return;
 652                         }
 653
 654                         ec.Report.Error (407, loc, "A method or delegate `{0} {1}' return type does not match delegate `{2} {3}' return type",
 655                                 return_type.GetSignatureForError (), member_name,
 656                                 invoke_method.ReturnType.GetSignatureForError (), Delegate.FullDelegateDesc (invoke_method));
 657                 }
 658
 659                 public static bool ImplicitStandardConversionExists (ResolveContext ec, MethodGroupExpr mg, TypeSpec target_type)
 660                 {
 661 //                      if (target_type == TypeManager.delegate_type || target_type == TypeManager.multicast_delegate_type)
 662 //                              return false;
 663
 664                         var invoke = Delegate.GetInvokeMethod (target_type);
 665
 666                         Arguments arguments = CreateDelegateMethodArguments (ec, invoke.Parameters, invoke.Parameters.Types, mg.Location);
 667                         mg = mg.OverloadResolve (ec, ref arguments, null, OverloadResolver.Restrictions.CovariantDelegate | OverloadResolver.Restrictions.ProbingOnly);
 668                         return mg != null && Delegate.IsTypeCovariant (ec, mg.BestCandidateReturnType, invoke.ReturnType);
 669                 }
 670
 671                 #region IErrorHandler Members
 672
 673                 bool OverloadResolver.IErrorHandler.AmbiguousCandidates (ResolveContext ec, MemberSpec best, MemberSpec ambiguous)
 674                 {
 675                         return false;
 676                 }
 677
 678                 bool OverloadResolver.IErrorHandler.ArgumentMismatch (ResolveContext rc, MemberSpec best, Argument arg, int index)
 679                 {
 680                         Error_ConversionFailed (rc, best as MethodSpec, null);
 681                         return true;
 682                 }
 683
 684                 bool OverloadResolver.IErrorHandler.NoArgumentMatch (ResolveContext rc, MemberSpec best)
 685                 {
 686                         Error_ConversionFailed (rc, best as MethodSpec, null);
 687                         return true;
 688                 }
 689
 690                 bool OverloadResolver.IErrorHandler.TypeInferenceFailed (ResolveContext rc, MemberSpec best)
 691                 {
 692                         return false;
 693                 }
 694
 695                 #endregion
 696         }
 697
 698         //
 699         // Created from the conversion code
 700         //
 701         public class ImplicitDelegateCreation : DelegateCreation
 702         {
 703                 Field mg_cache;
 704
 705                 public ImplicitDelegateCreation (TypeSpec delegateType, MethodGroupExpr mg, Location loc)
 706                 {
 707                         type = delegateType;
 708                         this.method_group = mg;
 709                         this.loc = loc;
 710                 }
 711
 712                 //
 713                 // Returns true when type is MVAR or has MVAR reference
 714                 //
 715                 public static bool ContainsMethodTypeParameter (TypeSpec type)
 716                 {
 717                         var tps = type as TypeParameterSpec;
 718                         if (tps != null)
 719                                 return tps.IsMethodOwned;
 720
 721                         var ec = type as ElementTypeSpec;
 722                         if (ec != null)
 723                                 return ContainsMethodTypeParameter (ec.Element);
 724
 725                         foreach (var t in type.TypeArguments) {
 726                                 if (ContainsMethodTypeParameter (t)) {
 727                                         return true;
 728                                 }
 729                         }
 730
 731                         if (type.IsNested)
 732                                 return ContainsMethodTypeParameter (type.DeclaringType);
 733
 734                         return false;
 735                 }
 736
 737                 bool HasMvar ()
 738                 {
 739                         if (ContainsMethodTypeParameter (type))
 740                                 return false;
 741
 742                         var best = method_group.BestCandidate;
 743                         if (ContainsMethodTypeParameter (best.DeclaringType))
 744                                 return false;
 745
 746                         if (best.TypeArguments != null) {
 747                                 foreach (var ta in best.TypeArguments) {
 748                                         if (ContainsMethodTypeParameter (ta))
 749                                                 return false;
 750                                 }
 751                         }
 752
 753                         return true;
 754                 }
 755
 756                 protected override Expression DoResolve (ResolveContext ec)
 757                 {
 758                         var expr = base.DoResolve (ec);
 759                         if (expr == null)
 760                                 return ErrorExpression.Instance;
 761
 762                         if (ec.IsInProbingMode)
 763                                 return expr;
 764
 765                         //
 766                         // Cache any static delegate creation
 767                         //
 768                         if (method_group.InstanceExpression != null)
 769                                 return expr;
 770
 771                         //
 772                         // Cannot easily cache types with MVAR
 773                         //
 774                         if (!HasMvar ())
 775                                 return expr;
 776
 777                         //
 778                         // Create type level cache for a delegate instance
 779                         //
 780                         var parent = ec.CurrentMemberDefinition.Parent.PartialContainer;
 781                         int id = parent.MethodGroupsCounter++;
 782
 783                         mg_cache = new Field (parent, new TypeExpression (type, loc),
 784                                 Modifiers.STATIC | Modifiers.PRIVATE | Modifiers.COMPILER_GENERATED,
 785                                 new MemberName (CompilerGeneratedContainer.MakeName (null, "f", "mg$cache", id), loc), null);
 786                         mg_cache.Define ();
 787                         parent.AddField (mg_cache);
 788
 789                         return expr;
 790                 }
 791
 792                 public override void Emit (EmitContext ec)
 793                 {
 794                         Label l_initialized = ec.DefineLabel ();
 795
 796                         if (mg_cache != null) {
 797                                 ec.Emit (OpCodes.Ldsfld, mg_cache.Spec);
 798                                 ec.Emit (OpCodes.Brtrue_S, l_initialized);
 799                         }
 800
 801                         base.Emit (ec);
 802
 803                         if (mg_cache != null) {
 804                                 ec.Emit (OpCodes.Stsfld, mg_cache.Spec);
 805                                 ec.MarkLabel (l_initialized);
 806                                 ec.Emit (OpCodes.Ldsfld, mg_cache.Spec);
 807                         }
 808                 }
 809         }
 810
 811         //
 812         // A delegate-creation-expression, invoked from the `New' class
 813         //
 814         public class NewDelegate : DelegateCreation
 815         {
 816                 public Arguments Arguments;
 817
 818                 //
 819                 // This constructor is invoked from the `New' expression
 820                 //
 821                 public NewDelegate (TypeSpec type, Arguments Arguments, Location loc)
 822                 {
 823                         this.type = type;
 824                         this.Arguments = Arguments;
 825                         this.loc  = loc;
 826                 }
 827
 828                 protected override Expression DoResolve (ResolveContext ec)
 829                 {
 830                         if (Arguments == null || Arguments.Count != 1) {
 831                                 ec.Report.Error (149, loc, "Method name expected");
 832                                 return null;
 833                         }
 834
 835                         Argument a = Arguments [0];
 836                         if (!a.ResolveMethodGroup (ec))
 837                                 return null;
 838
 839                         Expression e = a.Expr;
 840
 841                         AnonymousMethodExpression ame = e as AnonymousMethodExpression;
 842                         if (ame != null && ec.Module.Compiler.Settings.Version != LanguageVersion.ISO_1) {
 843                                 e = ame.Compatible (ec, type);
 844                                 if (e == null)
 845                                         return null;
 846
 847                                 return e.Resolve (ec);
 848                         }
 849
 850                         method_group = e as MethodGroupExpr;
 851                         if (method_group == null) {
 852                                 if (e.Type.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
 853                                         e = Convert.ImplicitConversionRequired (ec, e, type, loc);
 854                                 } else if (!e.Type.IsDelegate) {
 855                                         e.Error_UnexpectedKind (ec, ResolveFlags.MethodGroup | ResolveFlags.Type, loc);
 856                                         return null;
 857                                 }
 858
 859                                 //
 860                                 // An argument is not a method but another delegate
 861                                 //
 862                                 method_group = new MethodGroupExpr (Delegate.GetInvokeMethod (e.Type), e.Type, loc);
 863                                 method_group.InstanceExpression = e;
 864                         }
 865
 866                         return base.DoResolve (ec);
 867                 }
 868         }
 869
 870         //
 871         // Invocation converted to delegate Invoke call
 872         //
 873         class DelegateInvocation : ExpressionStatement
 874         {
 875                 readonly Expression InstanceExpr;
 876                 readonly bool conditionalAccessReceiver;
 877                 Arguments arguments;
 878                 MethodSpec method;
 879
 880                 public DelegateInvocation (Expression instance_expr, Arguments args, bool conditionalAccessReceiver, Location loc)
 881                 {
 882                         this.InstanceExpr = instance_expr;
 883                         this.arguments = args;
 884                         this.conditionalAccessReceiver = conditionalAccessReceiver;
 885                         this.loc = loc;
 886                 }
 887
 888                 public override bool ContainsEmitWithAwait ()
 889                 {
 890                         return InstanceExpr.ContainsEmitWithAwait () || (arguments != null && arguments.ContainsEmitWithAwait ());
 891                 }
 892
 893                 public override Expression CreateExpressionTree (ResolveContext ec)
 894                 {
 895                         Arguments args = Arguments.CreateForExpressionTree (ec, this.arguments,
 896                                 InstanceExpr.CreateExpressionTree (ec));
 897
 898                         return CreateExpressionFactoryCall (ec, "Invoke", args);
 899                 }
 900
 901                 public override void FlowAnalysis (FlowAnalysisContext fc)
 902                 {
 903                         InstanceExpr.FlowAnalysis (fc);
 904                         if (arguments != null)
 905                                 arguments.FlowAnalysis (fc);
 906                 }
 907
 908                 protected override Expression DoResolve (ResolveContext ec)
 909                 {
 910                         TypeSpec del_type = InstanceExpr.Type;
 911                         if (del_type == null)
 912                                 return null;
 913
 914                         //
 915                         // Do only core overload resolution the rest of the checks has been
 916                         // done on primary expression
 917                         //
 918                         method = Delegate.GetInvokeMethod (del_type);
 919                         var res = new OverloadResolver (new MemberSpec[] { method }, OverloadResolver.Restrictions.DelegateInvoke, loc);
 920                         var valid = res.ResolveMember<MethodSpec> (ec, ref arguments);
 921                         if (valid == null && !res.BestCandidateIsDynamic)
 922                                 return null;
 923
 924                         type = method.ReturnType;
 925                         if (conditionalAccessReceiver)
 926                                 type = LiftMemberType (ec, type);
 927
 928                         eclass = ExprClass.Value;
 929                         return this;
 930                 }
 931
 932                 public override void Emit (EmitContext ec)
 933                 {
 934                         if (conditionalAccessReceiver) {
 935                                 ec.ConditionalAccess = new ConditionalAccessContext (type, ec.DefineLabel ());
 936                         }
 937
 938                         //
 939                         // Invocation on delegates call the virtual Invoke member
 940                         // so we are always `instance' calls
 941                         //
 942                         var call = new CallEmitter ();
 943                         call.InstanceExpression = InstanceExpr;
 944                         call.Emit (ec, method, arguments, loc);
 945
 946                         if (conditionalAccessReceiver)
 947                                 ec.CloseConditionalAccess (type.IsNullableType && type !=  method.ReturnType ? type : null);
 948                 }
 949
 950                 public override void EmitStatement (EmitContext ec)
 951                 {
 952                         if (conditionalAccessReceiver) {
 953                                 ec.ConditionalAccess = new ConditionalAccessContext (type, ec.DefineLabel ()) {
 954                                         Statement = true
 955                                 };
 956                         }
 957
 958                         var call = new CallEmitter ();
 959                         call.InstanceExpression = InstanceExpr;
 960                         call.EmitStatement (ec, method, arguments, loc);
 961
 962                         if (conditionalAccessReceiver)
 963                                 ec.CloseConditionalAccess (null);
 964                 }
 965
 966                 public override System.Linq.Expressions.Expression MakeExpression (BuilderContext ctx)
 967                 {
 968                         return Invocation.MakeExpression (ctx, InstanceExpr, method, arguments);
 969                 }
 970         }
 971 }