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.TypeExpression = null;
 312                                 EndInvokeBuilder.TypeExpression = null;
 313                                 BeginInvokeBuilder.PrepareEmit ();
 314                                 EndInvokeBuilder.PrepareEmit ();
 315                         }
 316                 }
 317
 318                 public override void Emit ()
 319                 {
 320                         base.Emit ();
 321
 322                         if (declarative_security != null) {
 323                                 foreach (var de in declarative_security) {
 324 #if STATIC
 325                                         TypeBuilder.__AddDeclarativeSecurity (de);
 326 #else
 327                                         TypeBuilder.AddDeclarativeSecurity (de.Key, de.Value);
 328 #endif
 329                                 }
 330                         }
 331
 332                         if (ReturnType.Type != null) {
 333                                 if (ReturnType.Type.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
 334                                         return_attributes = new ReturnParameter (this, InvokeBuilder.MethodBuilder, Location);
 335                                         Module.PredefinedAttributes.Dynamic.EmitAttribute (return_attributes.Builder);
 336                                 } else if (ReturnType.Type.HasDynamicElement) {
 337                                         return_attributes = new ReturnParameter (this, InvokeBuilder.MethodBuilder, Location);
 338                                         Module.PredefinedAttributes.Dynamic.EmitAttribute (return_attributes.Builder, ReturnType.Type, Location);
 339                                 }
 340
 341                                 ConstraintChecker.Check (this, ReturnType.Type, ReturnType.Location);
 342                         }
 343
 344                         Constructor.ParameterInfo.ApplyAttributes (this, Constructor.ConstructorBuilder);
 345                         Constructor.ConstructorBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 346
 347                         parameters.CheckConstraints (this);
 348                         parameters.ApplyAttributes (this, InvokeBuilder.MethodBuilder);
 349                         InvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 350
 351                         if (BeginInvokeBuilder != null) {
 352                                 BeginInvokeBuilder.ParameterInfo.ApplyAttributes (this, BeginInvokeBuilder.MethodBuilder);
 353                                 EndInvokeBuilder.ParameterInfo.ApplyAttributes (this, EndInvokeBuilder.MethodBuilder);
 354
 355                                 BeginInvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 356                                 EndInvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 357                         }
 358                 }
 359
 360                 protected override TypeSpec[] ResolveBaseTypes (out FullNamedExpression base_class)
 361                 {
 362                         base_type = Compiler.BuiltinTypes.MulticastDelegate;
 363                         base_class = null;
 364                         return null;
 365                 }
 366
 367                 protected override TypeAttributes TypeAttr {
 368                         get {
 369                                 return base.TypeAttr | TypeAttributes.Class | TypeAttributes.Sealed;
 370                         }
 371                 }
 372
 373                 public override string[] ValidAttributeTargets {
 374                         get {
 375                                 return attribute_targets;
 376                         }
 377                 }
 378
 379                 //TODO: duplicate
 380                 protected override bool VerifyClsCompliance ()
 381                 {
 382                         if (!base.VerifyClsCompliance ()) {
 383                                 return false;
 384                         }
 385
 386                         parameters.VerifyClsCompliance (this);
 387
 388                         if (!InvokeBuilder.MemberType.IsCLSCompliant ()) {
 389                                 Report.Warning (3002, 1, Location, "Return type of `{0}' is not CLS-compliant",
 390                                         GetSignatureForError ());
 391                         }
 392                         return true;
 393                 }
 394
 395
 396                 public static MethodSpec GetConstructor (TypeSpec delType)
 397                 {
 398                         var ctor = MemberCache.FindMember (delType, MemberFilter.Constructor (null), BindingRestriction.DeclaredOnly);
 399                         return (MethodSpec) ctor;
 400                 }
 401
 402                 //
 403                 // Returns the "Invoke" from a delegate type
 404                 //
 405                 public static MethodSpec GetInvokeMethod (TypeSpec delType)
 406                 {
 407                         var invoke = MemberCache.FindMember (delType,
 408                                 MemberFilter.Method (InvokeMethodName, 0, null, null),
 409                                 BindingRestriction.DeclaredOnly);
 410
 411                         return (MethodSpec) invoke;
 412                 }
 413
 414                 public static AParametersCollection GetParameters (TypeSpec delType)
 415                 {
 416                         var invoke_mb = GetInvokeMethod (delType);
 417                         return invoke_mb.Parameters;
 418                 }
 419
 420                 //
 421                 // 15.2 Delegate compatibility
 422                 //
 423                 public static bool IsTypeCovariant (ResolveContext rc, TypeSpec a, TypeSpec b)
 424                 {
 425                         //
 426                         // For each value parameter (a parameter with no ref or out modifier), an
 427                         // identity conversion or implicit reference conversion exists from the
 428                         // parameter type in D to the corresponding parameter type in M
 429                         //
 430                         if (a == b)
 431                                 return true;
 432
 433                         if (rc.Module.Compiler.Settings.Version == LanguageVersion.ISO_1)
 434                                 return false;
 435
 436                         if (a.IsGenericParameter && b.IsGenericParameter)
 437                                 return a == b;
 438
 439                         return Convert.ImplicitReferenceConversionExists (a, b);
 440                 }
 441
 442                 public static string FullDelegateDesc (MethodSpec invoke_method)
 443                 {
 444                         return TypeManager.GetFullNameSignature (invoke_method).Replace (".Invoke", "");
 445                 }
 446
 447                 public Expression InstanceExpression {
 448                         get {
 449                                 return instance_expr;
 450                         }
 451                         set {
 452                                 instance_expr = value;
 453                         }
 454                 }
 455         }
 456
 457         //
 458         // Base class for `NewDelegate' and `ImplicitDelegateCreation'
 459         //
 460         public abstract class DelegateCreation : Expression, OverloadResolver.IErrorHandler
 461         {
 462                 bool conditional_access_receiver;
 463                 protected MethodSpec constructor_method;
 464                 protected MethodGroupExpr method_group;
 465
 466                 public bool AllowSpecialMethodsInvocation { get; set; }
 467
 468                 public override bool ContainsEmitWithAwait ()
 469                 {
 470                         var instance = method_group.InstanceExpression;
 471                         return instance != null && instance.ContainsEmitWithAwait ();
 472                 }
 473
 474                 public static Arguments CreateDelegateMethodArguments (ResolveContext rc, AParametersCollection pd, TypeSpec[] types, Location loc)
 475                 {
 476                         Arguments delegate_arguments = new Arguments (pd.Count);
 477                         for (int i = 0; i < pd.Count; ++i) {
 478                                 Argument.AType atype_modifier;
 479                                 switch (pd.FixedParameters [i].ModFlags & Parameter.Modifier.RefOutMask) {
 480                                 case Parameter.Modifier.REF:
 481                                         atype_modifier = Argument.AType.Ref;
 482                                         break;
 483                                 case Parameter.Modifier.OUT:
 484                                         atype_modifier = Argument.AType.Out;
 485                                         break;
 486                                 default:
 487                                         atype_modifier = 0;
 488                                         break;
 489                                 }
 490
 491                                 var ptype = types[i];
 492                                 if (ptype.BuiltinType == BuiltinTypeSpec.Type.Dynamic)
 493                                         ptype = rc.BuiltinTypes.Object;
 494
 495                                 delegate_arguments.Add (new Argument (new TypeExpression (ptype, loc), atype_modifier));
 496                         }
 497
 498                         return delegate_arguments;
 499                 }
 500
 501                 public override Expression CreateExpressionTree (ResolveContext ec)
 502                 {
 503                         MemberAccess ma = new MemberAccess (new MemberAccess (new QualifiedAliasMember ("global", "System", loc), "Delegate", loc), "CreateDelegate", loc);
 504
 505                         Arguments args = new Arguments (3);
 506                         args.Add (new Argument (new TypeOf (type, loc)));
 507
 508                         if (method_group.InstanceExpression == null)
 509                                 args.Add (new Argument (new NullLiteral (loc)));
 510                         else
 511                                 args.Add (new Argument (method_group.InstanceExpression));
 512
 513                         args.Add (new Argument (method_group.CreateExpressionTree (ec)));
 514                         Expression e = new Invocation (ma, args).Resolve (ec);
 515                         if (e == null)
 516                                 return null;
 517
 518                         e = Convert.ExplicitConversion (ec, e, type, loc);
 519                         if (e == null)
 520                                 return null;
 521
 522                         return e.CreateExpressionTree (ec);
 523                 }
 524
 525                 protected override Expression DoResolve (ResolveContext ec)
 526                 {
 527                         constructor_method = Delegate.GetConstructor (type);
 528
 529                         var invoke_method = Delegate.GetInvokeMethod (type);
 530
 531                         if (!ec.HasSet (ResolveContext.Options.ConditionalAccessReceiver)) {
 532                                 if (method_group.HasConditionalAccess ()) {
 533                                         conditional_access_receiver = true;
 534                                         ec.Set (ResolveContext.Options.ConditionalAccessReceiver);
 535                                 }
 536                         }
 537
 538                         Arguments arguments = CreateDelegateMethodArguments (ec, invoke_method.Parameters, invoke_method.Parameters.Types, loc);
 539                         method_group = method_group.OverloadResolve (ec, ref arguments, this, OverloadResolver.Restrictions.CovariantDelegate);
 540
 541                         if (conditional_access_receiver)
 542                                 ec.With (ResolveContext.Options.ConditionalAccessReceiver, false);
 543
 544                         if (method_group == null)
 545                                 return null;
 546
 547                         var delegate_method = method_group.BestCandidate;
 548
 549                         if (delegate_method.DeclaringType.IsNullableType) {
 550                                 ec.Report.Error (1728, loc, "Cannot create delegate from method `{0}' because it is a member of System.Nullable<T> type",
 551                                         delegate_method.GetSignatureForError ());
 552                                 return null;
 553                         }
 554
 555                         if (!AllowSpecialMethodsInvocation)
 556                                 Invocation.IsSpecialMethodInvocation (ec, delegate_method, loc);
 557
 558                         ExtensionMethodGroupExpr emg = method_group as ExtensionMethodGroupExpr;
 559                         if (emg != null) {
 560                                 method_group.InstanceExpression = emg.ExtensionExpression;
 561                                 TypeSpec e_type = emg.ExtensionExpression.Type;
 562                                 if (TypeSpec.IsValueType (e_type)) {
 563                                         ec.Report.Error (1113, loc, "Extension method `{0}' of value type `{1}' cannot be used to create delegates",
 564                                                 delegate_method.GetSignatureForError (), e_type.GetSignatureForError ());
 565                                 }
 566                         }
 567
 568                         TypeSpec rt = method_group.BestCandidateReturnType;
 569                         if (rt.BuiltinType == BuiltinTypeSpec.Type.Dynamic)
 570                                 rt = ec.BuiltinTypes.Object;
 571
 572                         if (!Delegate.IsTypeCovariant (ec, rt, invoke_method.ReturnType)) {
 573                                 Expression ret_expr = new TypeExpression (delegate_method.ReturnType, loc);
 574                                 Error_ConversionFailed (ec, delegate_method, ret_expr);
 575                         }
 576
 577                         if (method_group.IsConditionallyExcluded) {
 578                                 ec.Report.SymbolRelatedToPreviousError (delegate_method);
 579                                 MethodOrOperator m = delegate_method.MemberDefinition as MethodOrOperator;
 580                                 if (m != null && m.IsPartialDefinition) {
 581                                         ec.Report.Error (762, loc, "Cannot create delegate from partial method declaration `{0}'",
 582                                                 delegate_method.GetSignatureForError ());
 583                                 } else {
 584                                         ec.Report.Error (1618, loc, "Cannot create delegate with `{0}' because it has a Conditional attribute",
 585                                                 TypeManager.CSharpSignature (delegate_method));
 586                                 }
 587                         }
 588
 589                         var expr = method_group.InstanceExpression;
 590                         if (expr != null && (expr.Type.IsGenericParameter || !TypeSpec.IsReferenceType (expr.Type)))
 591                                 method_group.InstanceExpression = new BoxedCast (expr, ec.BuiltinTypes.Object);
 592
 593                         eclass = ExprClass.Value;
 594                         return this;
 595                 }
 596
 597                 public override void Emit (EmitContext ec)
 598                 {
 599                         if (conditional_access_receiver)
 600                                 ec.ConditionalAccess = new ConditionalAccessContext (type, ec.DefineLabel ());
 601
 602                         if (method_group.InstanceExpression == null) {
 603                                 ec.EmitNull ();
 604                         } else {
 605                                 var ie = new InstanceEmitter (method_group.InstanceExpression, false);
 606                                 ie.Emit (ec, method_group.ConditionalAccess);
 607                         }
 608
 609                         var delegate_method = method_group.BestCandidate;
 610
 611                         // Any delegate must be sealed
 612                         if (!delegate_method.DeclaringType.IsDelegate && delegate_method.IsVirtual && !method_group.IsBase) {
 613                                 ec.Emit (OpCodes.Dup);
 614                                 ec.Emit (OpCodes.Ldvirtftn, delegate_method);
 615                         } else {
 616                                 ec.Emit (OpCodes.Ldftn, delegate_method);
 617                         }
 618
 619                         ec.Emit (OpCodes.Newobj, constructor_method);
 620
 621                         if (conditional_access_receiver)
 622                                 ec.CloseConditionalAccess (null);
 623                 }
 624
 625                 public override void FlowAnalysis (FlowAnalysisContext fc)
 626                 {
 627                         var da = conditional_access_receiver ? fc.BranchDefiniteAssignment () : null;
 628
 629                         base.FlowAnalysis (fc);
 630                         method_group.FlowAnalysis (fc);
 631
 632                         if (conditional_access_receiver)
 633                                 fc.DefiniteAssignment = da;
 634                 }
 635
 636                 void Error_ConversionFailed (ResolveContext ec, MethodSpec method, Expression return_type)
 637                 {
 638                         var invoke_method = Delegate.GetInvokeMethod (type);
 639                         string member_name = method_group.InstanceExpression != null ?
 640                                 Delegate.FullDelegateDesc (method) :
 641                                 TypeManager.GetFullNameSignature (method);
 642
 643                         ec.Report.SymbolRelatedToPreviousError (type);
 644                         ec.Report.SymbolRelatedToPreviousError (method);
 645                         if (ec.Module.Compiler.Settings.Version == LanguageVersion.ISO_1) {
 646                                 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",
 647                                         method.ReturnType.GetSignatureForError (), member_name,
 648                                         invoke_method.ReturnType.GetSignatureForError (), Delegate.FullDelegateDesc (invoke_method));
 649                                 return;
 650                         }
 651
 652                         if (return_type == null) {
 653                                 ec.Report.Error (123, loc, "A method or delegate `{0}' parameters do not match delegate `{1}' parameters",
 654                                         member_name, Delegate.FullDelegateDesc (invoke_method));
 655                                 return;
 656                         }
 657
 658                         ec.Report.Error (407, loc, "A method or delegate `{0} {1}' return type does not match delegate `{2} {3}' return type",
 659                                 return_type.GetSignatureForError (), member_name,
 660                                 invoke_method.ReturnType.GetSignatureForError (), Delegate.FullDelegateDesc (invoke_method));
 661                 }
 662
 663                 public static bool ImplicitStandardConversionExists (ResolveContext ec, MethodGroupExpr mg, TypeSpec target_type)
 664                 {
 665 //                      if (target_type == TypeManager.delegate_type || target_type == TypeManager.multicast_delegate_type)
 666 //                              return false;
 667
 668                         var invoke = Delegate.GetInvokeMethod (target_type);
 669
 670                         Arguments arguments = CreateDelegateMethodArguments (ec, invoke.Parameters, invoke.Parameters.Types, mg.Location);
 671                         mg = mg.OverloadResolve (ec, ref arguments, null, OverloadResolver.Restrictions.CovariantDelegate | OverloadResolver.Restrictions.ProbingOnly);
 672                         return mg != null && Delegate.IsTypeCovariant (ec, mg.BestCandidateReturnType, invoke.ReturnType);
 673                 }
 674
 675                 #region IErrorHandler Members
 676
 677                 bool OverloadResolver.IErrorHandler.AmbiguousCandidates (ResolveContext ec, MemberSpec best, MemberSpec ambiguous)
 678                 {
 679                         return false;
 680                 }
 681
 682                 bool OverloadResolver.IErrorHandler.ArgumentMismatch (ResolveContext rc, MemberSpec best, Argument arg, int index)
 683                 {
 684                         Error_ConversionFailed (rc, best as MethodSpec, null);
 685                         return true;
 686                 }
 687
 688                 bool OverloadResolver.IErrorHandler.NoArgumentMatch (ResolveContext rc, MemberSpec best)
 689                 {
 690                         Error_ConversionFailed (rc, best as MethodSpec, null);
 691                         return true;
 692                 }
 693
 694                 bool OverloadResolver.IErrorHandler.TypeInferenceFailed (ResolveContext rc, MemberSpec best)
 695                 {
 696                         return false;
 697                 }
 698
 699                 #endregion
 700         }
 701
 702         //
 703         // Created from the conversion code
 704         //
 705         public class ImplicitDelegateCreation : DelegateCreation
 706         {
 707                 Field mg_cache;
 708
 709                 public ImplicitDelegateCreation (TypeSpec delegateType, MethodGroupExpr mg, Location loc)
 710                 {
 711                         type = delegateType;
 712                         this.method_group = mg;
 713                         this.loc = loc;
 714                 }
 715
 716                 //
 717                 // Returns true when type is MVAR or has MVAR reference
 718                 //
 719                 public static bool ContainsMethodTypeParameter (TypeSpec type)
 720                 {
 721                         var tps = type as TypeParameterSpec;
 722                         if (tps != null)
 723                                 return tps.IsMethodOwned;
 724
 725                         var ec = type as ElementTypeSpec;
 726                         if (ec != null)
 727                                 return ContainsMethodTypeParameter (ec.Element);
 728
 729                         foreach (var t in type.TypeArguments) {
 730                                 if (ContainsMethodTypeParameter (t)) {
 731                                         return true;
 732                                 }
 733                         }
 734
 735                         if (type.IsNested)
 736                                 return ContainsMethodTypeParameter (type.DeclaringType);
 737
 738                         return false;
 739                 }
 740
 741                 bool HasMvar ()
 742                 {
 743                         if (ContainsMethodTypeParameter (type))
 744                                 return false;
 745
 746                         var best = method_group.BestCandidate;
 747                         if (ContainsMethodTypeParameter (best.DeclaringType))
 748                                 return false;
 749
 750                         if (best.TypeArguments != null) {
 751                                 foreach (var ta in best.TypeArguments) {
 752                                         if (ContainsMethodTypeParameter (ta))
 753                                                 return false;
 754                                 }
 755                         }
 756
 757                         return true;
 758                 }
 759
 760                 protected override Expression DoResolve (ResolveContext ec)
 761                 {
 762                         var expr = base.DoResolve (ec);
 763                         if (expr == null)
 764                                 return ErrorExpression.Instance;
 765
 766                         if (ec.IsInProbingMode)
 767                                 return expr;
 768
 769                         //
 770                         // Cache any static delegate creation
 771                         //
 772                         if (method_group.InstanceExpression != null)
 773                                 return expr;
 774
 775                         //
 776                         // Cannot easily cache types with MVAR
 777                         //
 778                         if (!HasMvar ())
 779                                 return expr;
 780
 781                         //
 782                         // Create type level cache for a delegate instance
 783                         //
 784                         var parent = ec.CurrentMemberDefinition.Parent.PartialContainer;
 785                         int id = parent.MethodGroupsCounter++;
 786
 787                         mg_cache = new Field (parent, new TypeExpression (type, loc),
 788                                 Modifiers.STATIC | Modifiers.PRIVATE | Modifiers.COMPILER_GENERATED,
 789                                 new MemberName (CompilerGeneratedContainer.MakeName (null, "f", "mg$cache", id), loc), null);
 790                         mg_cache.Define ();
 791                         parent.AddField (mg_cache);
 792
 793                         return expr;
 794                 }
 795
 796                 public override void Emit (EmitContext ec)
 797                 {
 798                         Label l_initialized = ec.DefineLabel ();
 799
 800                         if (mg_cache != null) {
 801                                 ec.Emit (OpCodes.Ldsfld, mg_cache.Spec);
 802                                 ec.Emit (OpCodes.Brtrue_S, l_initialized);
 803                         }
 804
 805                         base.Emit (ec);
 806
 807                         if (mg_cache != null) {
 808                                 ec.Emit (OpCodes.Stsfld, mg_cache.Spec);
 809                                 ec.MarkLabel (l_initialized);
 810                                 ec.Emit (OpCodes.Ldsfld, mg_cache.Spec);
 811                         }
 812                 }
 813         }
 814
 815         //
 816         // A delegate-creation-expression, invoked from the `New' class
 817         //
 818         public class NewDelegate : DelegateCreation
 819         {
 820                 public Arguments Arguments;
 821
 822                 //
 823                 // This constructor is invoked from the `New' expression
 824                 //
 825                 public NewDelegate (TypeSpec type, Arguments Arguments, Location loc)
 826                 {
 827                         this.type = type;
 828                         this.Arguments = Arguments;
 829                         this.loc  = loc;
 830                 }
 831
 832                 protected override Expression DoResolve (ResolveContext ec)
 833                 {
 834                         if (Arguments == null || Arguments.Count != 1) {
 835                                 ec.Report.Error (149, loc, "Method name expected");
 836                                 return null;
 837                         }
 838
 839                         Argument a = Arguments [0];
 840                         if (!a.ResolveMethodGroup (ec))
 841                                 return null;
 842
 843                         Expression e = a.Expr;
 844
 845                         AnonymousMethodExpression ame = e as AnonymousMethodExpression;
 846                         if (ame != null && ec.Module.Compiler.Settings.Version != LanguageVersion.ISO_1) {
 847                                 e = ame.Compatible (ec, type);
 848                                 if (e == null)
 849                                         return null;
 850
 851                                 return e.Resolve (ec);
 852                         }
 853
 854                         method_group = e as MethodGroupExpr;
 855                         if (method_group == null) {
 856                                 if (e.Type.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
 857                                         e = Convert.ImplicitConversionRequired (ec, e, type, loc);
 858                                 } else if (!e.Type.IsDelegate) {
 859                                         e.Error_UnexpectedKind (ec, ResolveFlags.MethodGroup | ResolveFlags.Type, loc);
 860                                         return null;
 861                                 }
 862
 863                                 //
 864                                 // An argument is not a method but another delegate
 865                                 //
 866                                 method_group = new MethodGroupExpr (Delegate.GetInvokeMethod (e.Type), e.Type, loc);
 867                                 method_group.InstanceExpression = e;
 868                         }
 869
 870                         return base.DoResolve (ec);
 871                 }
 872         }
 873
 874         //
 875         // Invocation converted to delegate Invoke call
 876         //
 877         class DelegateInvocation : ExpressionStatement
 878         {
 879                 readonly Expression InstanceExpr;
 880                 readonly bool conditionalAccessReceiver;
 881                 Arguments arguments;
 882                 MethodSpec method;
 883
 884                 public DelegateInvocation (Expression instance_expr, Arguments args, bool conditionalAccessReceiver, Location loc)
 885                 {
 886                         this.InstanceExpr = instance_expr;
 887                         this.arguments = args;
 888                         this.conditionalAccessReceiver = conditionalAccessReceiver;
 889                         this.loc = loc;
 890                 }
 891
 892                 public override bool ContainsEmitWithAwait ()
 893                 {
 894                         return InstanceExpr.ContainsEmitWithAwait () || (arguments != null && arguments.ContainsEmitWithAwait ());
 895                 }
 896
 897                 public override Expression CreateExpressionTree (ResolveContext ec)
 898                 {
 899                         Arguments args = Arguments.CreateForExpressionTree (ec, this.arguments,
 900                                 InstanceExpr.CreateExpressionTree (ec));
 901
 902                         return CreateExpressionFactoryCall (ec, "Invoke", args);
 903                 }
 904
 905                 public override void FlowAnalysis (FlowAnalysisContext fc)
 906                 {
 907                         InstanceExpr.FlowAnalysis (fc);
 908                         if (arguments != null)
 909                                 arguments.FlowAnalysis (fc);
 910                 }
 911
 912                 protected override Expression DoResolve (ResolveContext ec)
 913                 {
 914                         TypeSpec del_type = InstanceExpr.Type;
 915                         if (del_type == null)
 916                                 return null;
 917
 918                         //
 919                         // Do only core overload resolution the rest of the checks has been
 920                         // done on primary expression
 921                         //
 922                         method = Delegate.GetInvokeMethod (del_type);
 923                         var res = new OverloadResolver (new MemberSpec[] { method }, OverloadResolver.Restrictions.DelegateInvoke, loc);
 924                         var valid = res.ResolveMember<MethodSpec> (ec, ref arguments);
 925                         if (valid == null && !res.BestCandidateIsDynamic)
 926                                 return null;
 927
 928                         type = method.ReturnType;
 929                         if (conditionalAccessReceiver)
 930                                 type = LiftMemberType (ec, type);
 931
 932                         eclass = ExprClass.Value;
 933                         return this;
 934                 }
 935
 936                 public override void Emit (EmitContext ec)
 937                 {
 938                         if (conditionalAccessReceiver) {
 939                                 ec.ConditionalAccess = new ConditionalAccessContext (type, ec.DefineLabel ());
 940                         }
 941
 942                         //
 943                         // Invocation on delegates call the virtual Invoke member
 944                         // so we are always `instance' calls
 945                         //
 946                         var call = new CallEmitter ();
 947                         call.InstanceExpression = InstanceExpr;
 948                         call.Emit (ec, method, arguments, loc);
 949
 950                         if (conditionalAccessReceiver)
 951                                 ec.CloseConditionalAccess (type.IsNullableType && type !=  method.ReturnType ? type : null);
 952                 }
 953
 954                 public override void EmitStatement (EmitContext ec)
 955                 {
 956                         if (conditionalAccessReceiver) {
 957                                 ec.ConditionalAccess = new ConditionalAccessContext (type, ec.DefineLabel ()) {
 958                                         Statement = true
 959                                 };
 960                         }
 961
 962                         var call = new CallEmitter ();
 963                         call.InstanceExpression = InstanceExpr;
 964                         call.EmitStatement (ec, method, arguments, loc);
 965
 966                         if (conditionalAccessReceiver)
 967                                 ec.CloseConditionalAccess (null);
 968                 }
 969
 970                 public override System.Linq.Expressions.Expression MakeExpression (BuilderContext ctx)
 971                 {
 972                         return Invocation.MakeExpression (ctx, InstanceExpr, method, arguments);
 973                 }
 974         }
 975 }