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 IKVM.Reflection;
  20 using IKVM.Reflection.Emit;
  21 #else
  22 using System.Reflection;
  23 using System.Reflection.Emit;
  24 #endif
  25
  26 namespace Mono.CSharp {
  27
  28         //
  29         // Delegate container implementation
  30         //
  31         public class Delegate : TypeDefinition, IParametersMember
  32         {
  33                 FullNamedExpression ReturnType;
  34                 readonly ParametersCompiled parameters;
  35
  36                 Constructor Constructor;
  37                 Method InvokeBuilder;
  38                 Method BeginInvokeBuilder;
  39                 Method EndInvokeBuilder;
  40
  41                 static readonly string[] attribute_targets = new string [] { "type", "return" };
  42
  43                 public static readonly string InvokeMethodName = "Invoke";
  44
  45                 Expression instance_expr;
  46                 ReturnParameter return_attributes;
  47
  48                 const Modifiers MethodModifiers = Modifiers.PUBLIC | Modifiers.VIRTUAL;
  49
  50                 const Modifiers AllowedModifiers =
  51                         Modifiers.NEW |
  52                         Modifiers.PUBLIC |
  53                         Modifiers.PROTECTED |
  54                         Modifiers.INTERNAL |
  55                         Modifiers.UNSAFE |
  56                         Modifiers.PRIVATE;
  57
  58                 public Delegate (TypeContainer parent, FullNamedExpression type, Modifiers mod_flags, MemberName name, ParametersCompiled param_list,
  59                                  Attributes attrs)
  60                         : base (parent, name, attrs, MemberKind.Delegate)
  61
  62                 {
  63                         this.ReturnType = type;
  64                         ModFlags        = ModifiersExtensions.Check (AllowedModifiers, mod_flags,
  65                                                            IsTopLevel ? Modifiers.INTERNAL :
  66                                                            Modifiers.PRIVATE, name.Location, Report);
  67                         parameters      = param_list;
  68                         spec = new TypeSpec (Kind, null, this, null, ModFlags | Modifiers.SEALED);
  69                 }
  70
  71                 #region Properties
  72                 public TypeSpec MemberType {
  73                         get {
  74                                 return ReturnType.Type;
  75                         }
  76                 }
  77
  78                 public AParametersCollection Parameters {
  79                         get {
  80                                 return parameters;
  81                         }
  82                 }
  83
  84                 public FullNamedExpression TypExpression {
  85                         get {
  86                                 return ReturnType;
  87                         }
  88                 }
  89
  90                 #endregion
  91
  92                 public override void Accept (StructuralVisitor visitor)
  93                 {
  94                         visitor.Visit (this);
  95                 }
  96
  97                 public override void ApplyAttributeBuilder (Attribute a, MethodSpec ctor, byte[] cdata, PredefinedAttributes pa)
  98                 {
  99                         if (a.Target == AttributeTargets.ReturnValue) {
 100                                 if (return_attributes == null)
 101                                         return_attributes = new ReturnParameter (this, InvokeBuilder.MethodBuilder, Location);
 102
 103                                 return_attributes.ApplyAttributeBuilder (a, ctor, cdata, pa);
 104                                 return;
 105                         }
 106
 107                         base.ApplyAttributeBuilder (a, ctor, cdata, pa);
 108                 }
 109
 110                 public override AttributeTargets AttributeTargets {
 111                         get {
 112                                 return AttributeTargets.Delegate;
 113                         }
 114                 }
 115
 116                 protected override bool DoDefineMembers ()
 117                 {
 118                         var builtin_types = Compiler.BuiltinTypes;
 119
 120                         var ctor_parameters = ParametersCompiled.CreateFullyResolved (
 121                                 new [] {
 122                                         new Parameter (new TypeExpression (builtin_types.Object, Location), "object", Parameter.Modifier.NONE, null, Location),
 123                                         new Parameter (new TypeExpression (builtin_types.IntPtr, Location), "method", Parameter.Modifier.NONE, null, Location)
 124                                 },
 125                                 new [] {
 126                                         builtin_types.Object,
 127                                         builtin_types.IntPtr
 128                                 }
 129                         );
 130
 131                         Constructor = new Constructor (this, Constructor.ConstructorName,
 132                                 Modifiers.PUBLIC, null, ctor_parameters, Location);
 133                         Constructor.Define ();
 134
 135                         //
 136                         // Here the various methods like Invoke, BeginInvoke etc are defined
 137                         //
 138                         // First, call the `out of band' special method for
 139                         // defining recursively any types we need:
 140                         //
 141                         var p = parameters;
 142
 143                         if (!p.Resolve (this))
 144                                 return false;
 145
 146                         //
 147                         // Invoke method
 148                         //
 149
 150                         // Check accessibility
 151                         foreach (var partype in p.Types) {
 152                                 if (!IsAccessibleAs (partype)) {
 153                                         Report.SymbolRelatedToPreviousError (partype);
 154                                         Report.Error (59, Location,
 155                                                 "Inconsistent accessibility: parameter type `{0}' is less accessible than delegate `{1}'",
 156                                                 partype.GetSignatureForError (), GetSignatureForError ());
 157                                 }
 158                         }
 159
 160                         var ret_type = ReturnType.ResolveAsType (this);
 161                         if (ret_type == null)
 162                                 return false;
 163
 164                         //
 165                         // We don't have to check any others because they are all
 166                         // guaranteed to be accessible - they are standard types.
 167                         //
 168                         if (!IsAccessibleAs (ret_type)) {
 169                                 Report.SymbolRelatedToPreviousError (ret_type);
 170                                 Report.Error (58, Location,
 171                                                   "Inconsistent accessibility: return type `" +
 172                                                   ret_type.GetSignatureForError () + "' is less " +
 173                                                   "accessible than delegate `" + GetSignatureForError () + "'");
 174                                 return false;
 175                         }
 176
 177                         CheckProtectedModifier ();
 178
 179                         if (Compiler.Settings.StdLib && ret_type.IsSpecialRuntimeType) {
 180                                 Method.Error1599 (Location, ret_type, Report);
 181                                 return false;
 182                         }
 183
 184                         VarianceDecl.CheckTypeVariance (ret_type, Variance.Covariant, this);
 185
 186                         var resolved_rt = new TypeExpression (ret_type, Location);
 187                         InvokeBuilder = new Method (this, resolved_rt, MethodModifiers, new MemberName (InvokeMethodName), p, null);
 188                         InvokeBuilder.Define ();
 189
 190                         //
 191                         // Don't emit async method for compiler generated delegates (e.g. dynamic site containers)
 192                         //
 193                         if (!IsCompilerGenerated) {
 194                                 DefineAsyncMethods (resolved_rt);
 195                         }
 196
 197                         return true;
 198                 }
 199
 200                 void DefineAsyncMethods (TypeExpression returnType)
 201                 {
 202                         var iasync_result = Module.PredefinedTypes.IAsyncResult;
 203                         var async_callback = Module.PredefinedTypes.AsyncCallback;
 204
 205                         //
 206                         // It's ok when async types don't exist, the delegate will have Invoke method only
 207                         //
 208                         if (!iasync_result.Define () || !async_callback.Define ())
 209                                 return;
 210
 211                         //
 212                         // BeginInvoke
 213                         //
 214                         ParametersCompiled async_parameters;
 215                         if (Parameters.Count == 0) {
 216                                 async_parameters = ParametersCompiled.EmptyReadOnlyParameters;
 217                         } else {
 218                                 var compiled = new Parameter[Parameters.Count];
 219                                 for (int i = 0; i < compiled.Length; ++i) {
 220                                         var p = parameters[i];
 221                                         compiled[i] = new Parameter (new TypeExpression (parameters.Types[i], Location),
 222                                                 p.Name,
 223                                                 p.ModFlags & Parameter.Modifier.RefOutMask,
 224                                                 p.OptAttributes == null ? null : p.OptAttributes.Clone (), Location);
 225                                 }
 226
 227                                 async_parameters = new ParametersCompiled (compiled);
 228                         }
 229
 230                         async_parameters = ParametersCompiled.MergeGenerated (Compiler, async_parameters, false,
 231                                 new Parameter[] {
 232                                         new Parameter (new TypeExpression (async_callback.TypeSpec, Location), "callback", Parameter.Modifier.NONE, null, Location),
 233                                         new Parameter (new TypeExpression (Compiler.BuiltinTypes.Object, Location), "object", Parameter.Modifier.NONE, null, Location)
 234                                 },
 235                                 new [] {
 236                                         async_callback.TypeSpec,
 237                                         Compiler.BuiltinTypes.Object
 238                                 }
 239                         );
 240
 241                         BeginInvokeBuilder = new Method (this,
 242                                 new TypeExpression (iasync_result.TypeSpec, Location), MethodModifiers,
 243                                 new MemberName ("BeginInvoke"), async_parameters, null);
 244                         BeginInvokeBuilder.Define ();
 245
 246                         //
 247                         // EndInvoke is a bit more interesting, all the parameters labeled as
 248                         // out or ref have to be duplicated here.
 249                         //
 250
 251                         //
 252                         // Define parameters, and count out/ref parameters
 253                         //
 254                         ParametersCompiled end_parameters;
 255                         int out_params = 0;
 256
 257                         foreach (Parameter p in Parameters.FixedParameters) {
 258                                 if ((p.ModFlags & Parameter.Modifier.RefOutMask) != 0)
 259                                         ++out_params;
 260                         }
 261
 262                         if (out_params > 0) {
 263                                 Parameter[] end_params = new Parameter[out_params];
 264
 265                                 int param = 0;
 266                                 for (int i = 0; i < Parameters.FixedParameters.Length; ++i) {
 267                                         Parameter p = parameters [i];
 268                                         if ((p.ModFlags & Parameter.Modifier.RefOutMask) == 0)
 269                                                 continue;
 270
 271                                         end_params [param++] = new Parameter (new TypeExpression (p.Type, Location),
 272                                                 p.Name,
 273                                                 p.ModFlags & Parameter.Modifier.RefOutMask,
 274                                                 p.OptAttributes == null ? null : p.OptAttributes.Clone (), Location);
 275                                 }
 276
 277                                 end_parameters = new ParametersCompiled (end_params);
 278                         } else {
 279                                 end_parameters = ParametersCompiled.EmptyReadOnlyParameters;
 280                         }
 281
 282                         end_parameters = ParametersCompiled.MergeGenerated (Compiler, end_parameters, false,
 283                                 new Parameter (
 284                                         new TypeExpression (iasync_result.TypeSpec, Location),
 285                                         "result", Parameter.Modifier.NONE, null, Location),
 286                                 iasync_result.TypeSpec);
 287
 288                         //
 289                         // Create method, define parameters, register parameters with type system
 290                         //
 291                         EndInvokeBuilder = new Method (this, returnType, MethodModifiers, new MemberName ("EndInvoke"), end_parameters, null);
 292                         EndInvokeBuilder.Define ();
 293                 }
 294
 295                 public override void PrepareEmit ()
 296                 {
 297                         if ((caching_flags & Flags.CloseTypeCreated) != 0)
 298                                 return;
 299
 300                         if (!Parameters.IsEmpty) {
 301                                 parameters.ResolveDefaultValues (this);
 302                         }
 303
 304                         InvokeBuilder.PrepareEmit ();
 305                         if (BeginInvokeBuilder != null) {
 306                                 BeginInvokeBuilder.PrepareEmit ();
 307                                 EndInvokeBuilder.PrepareEmit ();
 308                         }
 309                 }
 310
 311                 public override void Emit ()
 312                 {
 313                         base.Emit ();
 314
 315                         if (ReturnType.Type != null) {
 316                                 if (ReturnType.Type.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
 317                                         return_attributes = new ReturnParameter (this, InvokeBuilder.MethodBuilder, Location);
 318                                         Module.PredefinedAttributes.Dynamic.EmitAttribute (return_attributes.Builder);
 319                                 } else if (ReturnType.Type.HasDynamicElement) {
 320                                         return_attributes = new ReturnParameter (this, InvokeBuilder.MethodBuilder, Location);
 321                                         Module.PredefinedAttributes.Dynamic.EmitAttribute (return_attributes.Builder, ReturnType.Type, Location);
 322                                 }
 323
 324                                 ConstraintChecker.Check (this, ReturnType.Type, ReturnType.Location);
 325                         }
 326
 327                         Constructor.ParameterInfo.ApplyAttributes (this, Constructor.ConstructorBuilder);
 328                         Constructor.ConstructorBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 329
 330                         parameters.CheckConstraints (this);
 331                         parameters.ApplyAttributes (this, InvokeBuilder.MethodBuilder);
 332                         InvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 333
 334                         if (BeginInvokeBuilder != null) {
 335                                 BeginInvokeBuilder.ParameterInfo.ApplyAttributes (this, BeginInvokeBuilder.MethodBuilder);
 336                                 EndInvokeBuilder.ParameterInfo.ApplyAttributes (this, EndInvokeBuilder.MethodBuilder);
 337
 338                                 BeginInvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 339                                 EndInvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 340                         }
 341                 }
 342
 343                 protected override TypeSpec[] ResolveBaseTypes (out FullNamedExpression base_class)
 344                 {
 345                         base_type = Compiler.BuiltinTypes.MulticastDelegate;
 346                         base_class = null;
 347                         return null;
 348                 }
 349
 350                 protected override TypeAttributes TypeAttr {
 351                         get {
 352                                 return base.TypeAttr | TypeAttributes.Class | TypeAttributes.Sealed;
 353                         }
 354                 }
 355
 356                 public override string[] ValidAttributeTargets {
 357                         get {
 358                                 return attribute_targets;
 359                         }
 360                 }
 361
 362                 //TODO: duplicate
 363                 protected override bool VerifyClsCompliance ()
 364                 {
 365                         if (!base.VerifyClsCompliance ()) {
 366                                 return false;
 367                         }
 368
 369                         parameters.VerifyClsCompliance (this);
 370
 371                         if (!InvokeBuilder.MemberType.IsCLSCompliant ()) {
 372                                 Report.Warning (3002, 1, Location, "Return type of `{0}' is not CLS-compliant",
 373                                         GetSignatureForError ());
 374                         }
 375                         return true;
 376                 }
 377
 378
 379                 public static MethodSpec GetConstructor (TypeSpec delType)
 380                 {
 381                         var ctor = MemberCache.FindMember (delType, MemberFilter.Constructor (null), BindingRestriction.DeclaredOnly);
 382                         return (MethodSpec) ctor;
 383                 }
 384
 385                 //
 386                 // Returns the "Invoke" from a delegate type
 387                 //
 388                 public static MethodSpec GetInvokeMethod (TypeSpec delType)
 389                 {
 390                         var invoke = MemberCache.FindMember (delType,
 391                                 MemberFilter.Method (InvokeMethodName, 0, null, null),
 392                                 BindingRestriction.DeclaredOnly);
 393
 394                         return (MethodSpec) invoke;
 395                 }
 396
 397                 public static AParametersCollection GetParameters (TypeSpec delType)
 398                 {
 399                         var invoke_mb = GetInvokeMethod (delType);
 400                         return invoke_mb.Parameters;
 401                 }
 402
 403                 //
 404                 // 15.2 Delegate compatibility
 405                 //
 406                 public static bool IsTypeCovariant (ResolveContext rc, TypeSpec a, TypeSpec b)
 407                 {
 408                         //
 409                         // For each value parameter (a parameter with no ref or out modifier), an
 410                         // identity conversion or implicit reference conversion exists from the
 411                         // parameter type in D to the corresponding parameter type in M
 412                         //
 413                         if (a == b)
 414                                 return true;
 415
 416                         if (rc.Module.Compiler.Settings.Version == LanguageVersion.ISO_1)
 417                                 return false;
 418
 419                         if (a.IsGenericParameter && b.IsGenericParameter)
 420                                 return a == b;
 421
 422                         return Convert.ImplicitReferenceConversionExists (a, b);
 423                 }
 424
 425                 public static string FullDelegateDesc (MethodSpec invoke_method)
 426                 {
 427                         return TypeManager.GetFullNameSignature (invoke_method).Replace (".Invoke", "");
 428                 }
 429
 430                 public Expression InstanceExpression {
 431                         get {
 432                                 return instance_expr;
 433                         }
 434                         set {
 435                                 instance_expr = value;
 436                         }
 437                 }
 438         }
 439
 440         //
 441         // Base class for `NewDelegate' and `ImplicitDelegateCreation'
 442         //
 443         public abstract class DelegateCreation : Expression, OverloadResolver.IErrorHandler
 444         {
 445                 bool conditional_access_receiver;
 446                 protected MethodSpec constructor_method;
 447                 protected MethodGroupExpr method_group;
 448
 449                 public bool AllowSpecialMethodsInvocation { get; set; }
 450
 451                 public override bool ContainsEmitWithAwait ()
 452                 {
 453                         var instance = method_group.InstanceExpression;
 454                         return instance != null && instance.ContainsEmitWithAwait ();
 455                 }
 456
 457                 public static Arguments CreateDelegateMethodArguments (ResolveContext rc, AParametersCollection pd, TypeSpec[] types, Location loc)
 458                 {
 459                         Arguments delegate_arguments = new Arguments (pd.Count);
 460                         for (int i = 0; i < pd.Count; ++i) {
 461                                 Argument.AType atype_modifier;
 462                                 switch (pd.FixedParameters [i].ModFlags & Parameter.Modifier.RefOutMask) {
 463                                 case Parameter.Modifier.REF:
 464                                         atype_modifier = Argument.AType.Ref;
 465                                         break;
 466                                 case Parameter.Modifier.OUT:
 467                                         atype_modifier = Argument.AType.Out;
 468                                         break;
 469                                 default:
 470                                         atype_modifier = 0;
 471                                         break;
 472                                 }
 473
 474                                 var ptype = types[i];
 475                                 if (ptype.BuiltinType == BuiltinTypeSpec.Type.Dynamic)
 476                                         ptype = rc.BuiltinTypes.Object;
 477
 478                                 delegate_arguments.Add (new Argument (new TypeExpression (ptype, loc), atype_modifier));
 479                         }
 480
 481                         return delegate_arguments;
 482                 }
 483
 484                 public override Expression CreateExpressionTree (ResolveContext ec)
 485                 {
 486                         MemberAccess ma = new MemberAccess (new MemberAccess (new QualifiedAliasMember ("global", "System", loc), "Delegate", loc), "CreateDelegate", loc);
 487
 488                         Arguments args = new Arguments (3);
 489                         args.Add (new Argument (new TypeOf (type, loc)));
 490
 491                         if (method_group.InstanceExpression == null)
 492                                 args.Add (new Argument (new NullLiteral (loc)));
 493                         else
 494                                 args.Add (new Argument (method_group.InstanceExpression));
 495
 496                         args.Add (new Argument (method_group.CreateExpressionTree (ec)));
 497                         Expression e = new Invocation (ma, args).Resolve (ec);
 498                         if (e == null)
 499                                 return null;
 500
 501                         e = Convert.ExplicitConversion (ec, e, type, loc);
 502                         if (e == null)
 503                                 return null;
 504
 505                         return e.CreateExpressionTree (ec);
 506                 }
 507
 508                 protected override Expression DoResolve (ResolveContext ec)
 509                 {
 510                         constructor_method = Delegate.GetConstructor (type);
 511
 512                         var invoke_method = Delegate.GetInvokeMethod (type);
 513
 514                         if (!ec.HasSet (ResolveContext.Options.ConditionalAccessReceiver)) {
 515                                 if (method_group.HasConditionalAccess ()) {
 516                                         conditional_access_receiver = true;
 517                                         ec.Set (ResolveContext.Options.ConditionalAccessReceiver);
 518                                 }
 519                         }
 520
 521                         Arguments arguments = CreateDelegateMethodArguments (ec, invoke_method.Parameters, invoke_method.Parameters.Types, loc);
 522                         method_group = method_group.OverloadResolve (ec, ref arguments, this, OverloadResolver.Restrictions.CovariantDelegate);
 523
 524                         if (conditional_access_receiver)
 525                                 ec.With (ResolveContext.Options.ConditionalAccessReceiver, false);
 526
 527                         if (method_group == null)
 528                                 return null;
 529
 530                         var delegate_method = method_group.BestCandidate;
 531
 532                         if (delegate_method.DeclaringType.IsNullableType) {
 533                                 ec.Report.Error (1728, loc, "Cannot create delegate from method `{0}' because it is a member of System.Nullable<T> type",
 534                                         delegate_method.GetSignatureForError ());
 535                                 return null;
 536                         }
 537
 538                         if (!AllowSpecialMethodsInvocation)
 539                                 Invocation.IsSpecialMethodInvocation (ec, delegate_method, loc);
 540
 541                         ExtensionMethodGroupExpr emg = method_group as ExtensionMethodGroupExpr;
 542                         if (emg != null) {
 543                                 method_group.InstanceExpression = emg.ExtensionExpression;
 544                                 TypeSpec e_type = emg.ExtensionExpression.Type;
 545                                 if (TypeSpec.IsValueType (e_type)) {
 546                                         ec.Report.Error (1113, loc, "Extension method `{0}' of value type `{1}' cannot be used to create delegates",
 547                                                 delegate_method.GetSignatureForError (), e_type.GetSignatureForError ());
 548                                 }
 549                         }
 550
 551                         TypeSpec rt = method_group.BestCandidateReturnType;
 552                         if (rt.BuiltinType == BuiltinTypeSpec.Type.Dynamic)
 553                                 rt = ec.BuiltinTypes.Object;
 554
 555                         if (!Delegate.IsTypeCovariant (ec, rt, invoke_method.ReturnType)) {
 556                                 Expression ret_expr = new TypeExpression (delegate_method.ReturnType, loc);
 557                                 Error_ConversionFailed (ec, delegate_method, ret_expr);
 558                         }
 559
 560                         if (method_group.IsConditionallyExcluded) {
 561                                 ec.Report.SymbolRelatedToPreviousError (delegate_method);
 562                                 MethodOrOperator m = delegate_method.MemberDefinition as MethodOrOperator;
 563                                 if (m != null && m.IsPartialDefinition) {
 564                                         ec.Report.Error (762, loc, "Cannot create delegate from partial method declaration `{0}'",
 565                                                 delegate_method.GetSignatureForError ());
 566                                 } else {
 567                                         ec.Report.Error (1618, loc, "Cannot create delegate with `{0}' because it has a Conditional attribute",
 568                                                 TypeManager.CSharpSignature (delegate_method));
 569                                 }
 570                         }
 571
 572                         var expr = method_group.InstanceExpression;
 573                         if (expr != null && (expr.Type.IsGenericParameter || !TypeSpec.IsReferenceType (expr.Type)))
 574                                 method_group.InstanceExpression = new BoxedCast (expr, ec.BuiltinTypes.Object);
 575
 576                         eclass = ExprClass.Value;
 577                         return this;
 578                 }
 579
 580                 public override void Emit (EmitContext ec)
 581                 {
 582                         if (conditional_access_receiver)
 583                                 ec.ConditionalAccess = new ConditionalAccessContext (type, ec.DefineLabel ());
 584
 585                         if (method_group.InstanceExpression == null) {
 586                                 ec.EmitNull ();
 587                         } else {
 588                                 var ie = new InstanceEmitter (method_group.InstanceExpression, false);
 589                                 ie.Emit (ec, method_group.ConditionalAccess);
 590                         }
 591
 592                         var delegate_method = method_group.BestCandidate;
 593
 594                         // Any delegate must be sealed
 595                         if (!delegate_method.DeclaringType.IsDelegate && delegate_method.IsVirtual && !method_group.IsBase) {
 596                                 ec.Emit (OpCodes.Dup);
 597                                 ec.Emit (OpCodes.Ldvirtftn, delegate_method);
 598                         } else {
 599                                 ec.Emit (OpCodes.Ldftn, delegate_method);
 600                         }
 601
 602                         ec.Emit (OpCodes.Newobj, constructor_method);
 603
 604                         if (conditional_access_receiver)
 605                                 ec.CloseConditionalAccess (null);
 606                 }
 607
 608                 public override void FlowAnalysis (FlowAnalysisContext fc)
 609                 {
 610                         base.FlowAnalysis (fc);
 611                         method_group.FlowAnalysis (fc);
 612
 613                         if (conditional_access_receiver)
 614                                 fc.ConditionalAccessEnd ();
 615                 }
 616
 617                 void Error_ConversionFailed (ResolveContext ec, MethodSpec method, Expression return_type)
 618                 {
 619                         var invoke_method = Delegate.GetInvokeMethod (type);
 620                         string member_name = method_group.InstanceExpression != null ?
 621                                 Delegate.FullDelegateDesc (method) :
 622                                 TypeManager.GetFullNameSignature (method);
 623
 624                         ec.Report.SymbolRelatedToPreviousError (type);
 625                         ec.Report.SymbolRelatedToPreviousError (method);
 626                         if (ec.Module.Compiler.Settings.Version == LanguageVersion.ISO_1) {
 627                                 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",
 628                                         method.ReturnType.GetSignatureForError (), member_name,
 629                                         invoke_method.ReturnType.GetSignatureForError (), Delegate.FullDelegateDesc (invoke_method));
 630                                 return;
 631                         }
 632
 633                         if (return_type == null) {
 634                                 ec.Report.Error (123, loc, "A method or delegate `{0}' parameters do not match delegate `{1}' parameters",
 635                                         member_name, Delegate.FullDelegateDesc (invoke_method));
 636                                 return;
 637                         }
 638
 639                         ec.Report.Error (407, loc, "A method or delegate `{0} {1}' return type does not match delegate `{2} {3}' return type",
 640                                 return_type.GetSignatureForError (), member_name,
 641                                 invoke_method.ReturnType.GetSignatureForError (), Delegate.FullDelegateDesc (invoke_method));
 642                 }
 643
 644                 public static bool ImplicitStandardConversionExists (ResolveContext ec, MethodGroupExpr mg, TypeSpec target_type)
 645                 {
 646 //                      if (target_type == TypeManager.delegate_type || target_type == TypeManager.multicast_delegate_type)
 647 //                              return false;
 648
 649                         var invoke = Delegate.GetInvokeMethod (target_type);
 650
 651                         Arguments arguments = CreateDelegateMethodArguments (ec, invoke.Parameters, invoke.Parameters.Types, mg.Location);
 652                         mg = mg.OverloadResolve (ec, ref arguments, null, OverloadResolver.Restrictions.CovariantDelegate | OverloadResolver.Restrictions.ProbingOnly);
 653                         return mg != null && Delegate.IsTypeCovariant (ec, mg.BestCandidateReturnType, invoke.ReturnType);
 654                 }
 655
 656                 #region IErrorHandler Members
 657
 658                 bool OverloadResolver.IErrorHandler.AmbiguousCandidates (ResolveContext ec, MemberSpec best, MemberSpec ambiguous)
 659                 {
 660                         return false;
 661                 }
 662
 663                 bool OverloadResolver.IErrorHandler.ArgumentMismatch (ResolveContext rc, MemberSpec best, Argument arg, int index)
 664                 {
 665                         Error_ConversionFailed (rc, best as MethodSpec, null);
 666                         return true;
 667                 }
 668
 669                 bool OverloadResolver.IErrorHandler.NoArgumentMatch (ResolveContext rc, MemberSpec best)
 670                 {
 671                         Error_ConversionFailed (rc, best as MethodSpec, null);
 672                         return true;
 673                 }
 674
 675                 bool OverloadResolver.IErrorHandler.TypeInferenceFailed (ResolveContext rc, MemberSpec best)
 676                 {
 677                         return false;
 678                 }
 679
 680                 #endregion
 681         }
 682
 683         //
 684         // Created from the conversion code
 685         //
 686         public class ImplicitDelegateCreation : DelegateCreation
 687         {
 688                 Field mg_cache;
 689
 690                 public ImplicitDelegateCreation (TypeSpec delegateType, MethodGroupExpr mg, Location loc)
 691                 {
 692                         type = delegateType;
 693                         this.method_group = mg;
 694                         this.loc = loc;
 695                 }
 696
 697                 //
 698                 // Returns true when type is MVAR or has MVAR reference
 699                 //
 700                 public static bool ContainsMethodTypeParameter (TypeSpec type)
 701                 {
 702                         var tps = type as TypeParameterSpec;
 703                         if (tps != null)
 704                                 return tps.IsMethodOwned;
 705
 706                         var ec = type as ElementTypeSpec;
 707                         if (ec != null)
 708                                 return ContainsMethodTypeParameter (ec.Element);
 709
 710                         foreach (var t in type.TypeArguments) {
 711                                 if (ContainsMethodTypeParameter (t)) {
 712                                         return true;
 713                                 }
 714                         }
 715
 716                         if (type.IsNested)
 717                                 return ContainsMethodTypeParameter (type.DeclaringType);
 718
 719                         return false;
 720                 }
 721
 722                 bool HasMvar ()
 723                 {
 724                         if (ContainsMethodTypeParameter (type))
 725                                 return false;
 726
 727                         var best = method_group.BestCandidate;
 728                         if (ContainsMethodTypeParameter (best.DeclaringType))
 729                                 return false;
 730
 731                         if (best.TypeArguments != null) {
 732                                 foreach (var ta in best.TypeArguments) {
 733                                         if (ContainsMethodTypeParameter (ta))
 734                                                 return false;
 735                                 }
 736                         }
 737
 738                         return true;
 739                 }
 740
 741                 protected override Expression DoResolve (ResolveContext ec)
 742                 {
 743                         var expr = base.DoResolve (ec);
 744                         if (expr == null)
 745                                 return ErrorExpression.Instance;
 746
 747                         if (ec.IsInProbingMode)
 748                                 return expr;
 749
 750                         //
 751                         // Cache any static delegate creation
 752                         //
 753                         if (method_group.InstanceExpression != null)
 754                                 return expr;
 755
 756                         //
 757                         // Cannot easily cache types with MVAR
 758                         //
 759                         if (!HasMvar ())
 760                                 return expr;
 761
 762                         //
 763                         // Create type level cache for a delegate instance
 764                         //
 765                         var parent = ec.CurrentMemberDefinition.Parent.PartialContainer;
 766                         int id = parent.MethodGroupsCounter++;
 767
 768                         mg_cache = new Field (parent, new TypeExpression (type, loc),
 769                                 Modifiers.STATIC | Modifiers.PRIVATE | Modifiers.COMPILER_GENERATED,
 770                                 new MemberName (CompilerGeneratedContainer.MakeName (null, "f", "mg$cache", id), loc), null);
 771                         mg_cache.Define ();
 772                         parent.AddField (mg_cache);
 773
 774                         return expr;
 775                 }
 776
 777                 public override void Emit (EmitContext ec)
 778                 {
 779                         Label l_initialized = ec.DefineLabel ();
 780
 781                         if (mg_cache != null) {
 782                                 ec.Emit (OpCodes.Ldsfld, mg_cache.Spec);
 783                                 ec.Emit (OpCodes.Brtrue_S, l_initialized);
 784                         }
 785
 786                         base.Emit (ec);
 787
 788                         if (mg_cache != null) {
 789                                 ec.Emit (OpCodes.Stsfld, mg_cache.Spec);
 790                                 ec.MarkLabel (l_initialized);
 791                                 ec.Emit (OpCodes.Ldsfld, mg_cache.Spec);
 792                         }
 793                 }
 794         }
 795
 796         //
 797         // A delegate-creation-expression, invoked from the `New' class
 798         //
 799         public class NewDelegate : DelegateCreation
 800         {
 801                 public Arguments Arguments;
 802
 803                 //
 804                 // This constructor is invoked from the `New' expression
 805                 //
 806                 public NewDelegate (TypeSpec type, Arguments Arguments, Location loc)
 807                 {
 808                         this.type = type;
 809                         this.Arguments = Arguments;
 810                         this.loc  = loc;
 811                 }
 812
 813                 protected override Expression DoResolve (ResolveContext ec)
 814                 {
 815                         if (Arguments == null || Arguments.Count != 1) {
 816                                 ec.Report.Error (149, loc, "Method name expected");
 817                                 return null;
 818                         }
 819
 820                         Argument a = Arguments [0];
 821                         if (!a.ResolveMethodGroup (ec))
 822                                 return null;
 823
 824                         Expression e = a.Expr;
 825
 826                         AnonymousMethodExpression ame = e as AnonymousMethodExpression;
 827                         if (ame != null && ec.Module.Compiler.Settings.Version != LanguageVersion.ISO_1) {
 828                                 e = ame.Compatible (ec, type);
 829                                 if (e == null)
 830                                         return null;
 831
 832                                 return e.Resolve (ec);
 833                         }
 834
 835                         method_group = e as MethodGroupExpr;
 836                         if (method_group == null) {
 837                                 if (e.Type.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
 838                                         e = Convert.ImplicitConversionRequired (ec, e, type, loc);
 839                                 } else if (!e.Type.IsDelegate) {
 840                                         e.Error_UnexpectedKind (ec, ResolveFlags.MethodGroup | ResolveFlags.Type, loc);
 841                                         return null;
 842                                 }
 843
 844                                 //
 845                                 // An argument is not a method but another delegate
 846                                 //
 847                                 method_group = new MethodGroupExpr (Delegate.GetInvokeMethod (e.Type), e.Type, loc);
 848                                 method_group.InstanceExpression = e;
 849                         }
 850
 851                         return base.DoResolve (ec);
 852                 }
 853         }
 854
 855         //
 856         // Invocation converted to delegate Invoke call
 857         //
 858         class DelegateInvocation : ExpressionStatement
 859         {
 860                 readonly Expression InstanceExpr;
 861                 readonly bool conditionalAccessReceiver;
 862                 Arguments arguments;
 863                 MethodSpec method;
 864
 865                 public DelegateInvocation (Expression instance_expr, Arguments args, bool conditionalAccessReceiver, Location loc)
 866                 {
 867                         this.InstanceExpr = instance_expr;
 868                         this.arguments = args;
 869                         this.conditionalAccessReceiver = conditionalAccessReceiver;
 870                         this.loc = loc;
 871                 }
 872
 873                 public override bool ContainsEmitWithAwait ()
 874                 {
 875                         return InstanceExpr.ContainsEmitWithAwait () || (arguments != null && arguments.ContainsEmitWithAwait ());
 876                 }
 877
 878                 public override Expression CreateExpressionTree (ResolveContext ec)
 879                 {
 880                         Arguments args = Arguments.CreateForExpressionTree (ec, this.arguments,
 881                                 InstanceExpr.CreateExpressionTree (ec));
 882
 883                         return CreateExpressionFactoryCall (ec, "Invoke", args);
 884                 }
 885
 886                 public override void FlowAnalysis (FlowAnalysisContext fc)
 887                 {
 888                         InstanceExpr.FlowAnalysis (fc);
 889                         if (arguments != null)
 890                                 arguments.FlowAnalysis (fc);
 891                 }
 892
 893                 protected override Expression DoResolve (ResolveContext ec)
 894                 {
 895                         TypeSpec del_type = InstanceExpr.Type;
 896                         if (del_type == null)
 897                                 return null;
 898
 899                         //
 900                         // Do only core overload resolution the rest of the checks has been
 901                         // done on primary expression
 902                         //
 903                         method = Delegate.GetInvokeMethod (del_type);
 904                         var res = new OverloadResolver (new MemberSpec[] { method }, OverloadResolver.Restrictions.DelegateInvoke, loc);
 905                         var valid = res.ResolveMember<MethodSpec> (ec, ref arguments);
 906                         if (valid == null && !res.BestCandidateIsDynamic)
 907                                 return null;
 908
 909                         type = method.ReturnType;
 910                         if (conditionalAccessReceiver)
 911                                 type = LiftMemberType (ec, type);
 912
 913                         eclass = ExprClass.Value;
 914                         return this;
 915                 }
 916
 917                 public override void Emit (EmitContext ec)
 918                 {
 919                         if (conditionalAccessReceiver) {
 920                                 ec.ConditionalAccess = new ConditionalAccessContext (type, ec.DefineLabel ());
 921                         }
 922
 923                         //
 924                         // Invocation on delegates call the virtual Invoke member
 925                         // so we are always `instance' calls
 926                         //
 927                         var call = new CallEmitter ();
 928                         call.InstanceExpression = InstanceExpr;
 929                         call.Emit (ec, method, arguments, loc);
 930
 931                         if (conditionalAccessReceiver)
 932                                 ec.CloseConditionalAccess (type.IsNullableType && type !=  method.ReturnType ? type : null);
 933                 }
 934
 935                 public override void EmitStatement (EmitContext ec)
 936                 {
 937                         if (conditionalAccessReceiver) {
 938                                 ec.ConditionalAccess = new ConditionalAccessContext (type, ec.DefineLabel ()) {
 939                                         Statement = true
 940                                 };
 941                         }
 942
 943                         var call = new CallEmitter ();
 944                         call.InstanceExpression = InstanceExpr;
 945                         call.EmitStatement (ec, method, arguments, loc);
 946
 947                         if (conditionalAccessReceiver)
 948                                 ec.CloseConditionalAccess (null);
 949                 }
 950
 951                 public override System.Linq.Expressions.Expression MakeExpression (BuilderContext ctx)
 952                 {
 953                         return Invocation.MakeExpression (ctx, InstanceExpr, method, arguments);
 954                 }
 955         }
 956 }