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                         InvokeBuilder.PrepareEmit ();
 301                         if (BeginInvokeBuilder != null) {
 302                                 BeginInvokeBuilder.PrepareEmit ();
 303                                 EndInvokeBuilder.PrepareEmit ();
 304                         }
 305                 }
 306
 307                 public override void Emit ()
 308                 {
 309                         base.Emit ();
 310
 311                         if (ReturnType.Type != null) {
 312                                 if (ReturnType.Type.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
 313                                         return_attributes = new ReturnParameter (this, InvokeBuilder.MethodBuilder, Location);
 314                                         Module.PredefinedAttributes.Dynamic.EmitAttribute (return_attributes.Builder);
 315                                 } else if (ReturnType.Type.HasDynamicElement) {
 316                                         return_attributes = new ReturnParameter (this, InvokeBuilder.MethodBuilder, Location);
 317                                         Module.PredefinedAttributes.Dynamic.EmitAttribute (return_attributes.Builder, ReturnType.Type, Location);
 318                                 }
 319
 320                                 ConstraintChecker.Check (this, ReturnType.Type, ReturnType.Location);
 321                         }
 322
 323                         Constructor.ParameterInfo.ApplyAttributes (this, Constructor.ConstructorBuilder);
 324                         Constructor.ConstructorBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 325
 326                         parameters.CheckConstraints (this);
 327                         parameters.ApplyAttributes (this, InvokeBuilder.MethodBuilder);
 328                         InvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 329
 330                         if (BeginInvokeBuilder != null) {
 331                                 BeginInvokeBuilder.ParameterInfo.ApplyAttributes (this, BeginInvokeBuilder.MethodBuilder);
 332                                 EndInvokeBuilder.ParameterInfo.ApplyAttributes (this, EndInvokeBuilder.MethodBuilder);
 333
 334                                 BeginInvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 335                                 EndInvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 336                         }
 337                 }
 338
 339                 protected override TypeSpec[] ResolveBaseTypes (out FullNamedExpression base_class)
 340                 {
 341                         base_type = Compiler.BuiltinTypes.MulticastDelegate;
 342                         base_class = null;
 343                         return null;
 344                 }
 345
 346                 protected override TypeAttributes TypeAttr {
 347                         get {
 348                                 return base.TypeAttr | TypeAttributes.Class | TypeAttributes.Sealed;
 349                         }
 350                 }
 351
 352                 public override string[] ValidAttributeTargets {
 353                         get {
 354                                 return attribute_targets;
 355                         }
 356                 }
 357
 358                 //TODO: duplicate
 359                 protected override bool VerifyClsCompliance ()
 360                 {
 361                         if (!base.VerifyClsCompliance ()) {
 362                                 return false;
 363                         }
 364
 365                         parameters.VerifyClsCompliance (this);
 366
 367                         if (!InvokeBuilder.MemberType.IsCLSCompliant ()) {
 368                                 Report.Warning (3002, 1, Location, "Return type of `{0}' is not CLS-compliant",
 369                                         GetSignatureForError ());
 370                         }
 371                         return true;
 372                 }
 373
 374
 375                 public static MethodSpec GetConstructor (TypeSpec delType)
 376                 {
 377                         var ctor = MemberCache.FindMember (delType, MemberFilter.Constructor (null), BindingRestriction.DeclaredOnly);
 378                         return (MethodSpec) ctor;
 379                 }
 380
 381                 //
 382                 // Returns the "Invoke" from a delegate type
 383                 //
 384                 public static MethodSpec GetInvokeMethod (TypeSpec delType)
 385                 {
 386                         var invoke = MemberCache.FindMember (delType,
 387                                 MemberFilter.Method (InvokeMethodName, 0, null, null),
 388                                 BindingRestriction.DeclaredOnly);
 389
 390                         return (MethodSpec) invoke;
 391                 }
 392
 393                 public static AParametersCollection GetParameters (TypeSpec delType)
 394                 {
 395                         var invoke_mb = GetInvokeMethod (delType);
 396                         return invoke_mb.Parameters;
 397                 }
 398
 399                 //
 400                 // 15.2 Delegate compatibility
 401                 //
 402                 public static bool IsTypeCovariant (ResolveContext rc, TypeSpec a, TypeSpec b)
 403                 {
 404                         //
 405                         // For each value parameter (a parameter with no ref or out modifier), an
 406                         // identity conversion or implicit reference conversion exists from the
 407                         // parameter type in D to the corresponding parameter type in M
 408                         //
 409                         if (a == b)
 410                                 return true;
 411
 412                         if (rc.Module.Compiler.Settings.Version == LanguageVersion.ISO_1)
 413                                 return false;
 414
 415                         if (a.IsGenericParameter && b.IsGenericParameter)
 416                                 return a == b;
 417
 418                         return Convert.ImplicitReferenceConversionExists (a, b);
 419                 }
 420
 421                 public static string FullDelegateDesc (MethodSpec invoke_method)
 422                 {
 423                         return TypeManager.GetFullNameSignature (invoke_method).Replace (".Invoke", "");
 424                 }
 425
 426                 public Expression InstanceExpression {
 427                         get {
 428                                 return instance_expr;
 429                         }
 430                         set {
 431                                 instance_expr = value;
 432                         }
 433                 }
 434         }
 435
 436         //
 437         // Base class for `NewDelegate' and `ImplicitDelegateCreation'
 438         //
 439         public abstract class DelegateCreation : Expression, OverloadResolver.IErrorHandler
 440         {
 441                 bool conditional_access_receiver;
 442                 protected MethodSpec constructor_method;
 443                 protected MethodGroupExpr method_group;
 444
 445                 public bool AllowSpecialMethodsInvocation { get; set; }
 446
 447                 public override bool ContainsEmitWithAwait ()
 448                 {
 449                         var instance = method_group.InstanceExpression;
 450                         return instance != null && instance.ContainsEmitWithAwait ();
 451                 }
 452
 453                 public static Arguments CreateDelegateMethodArguments (ResolveContext rc, AParametersCollection pd, TypeSpec[] types, Location loc)
 454                 {
 455                         Arguments delegate_arguments = new Arguments (pd.Count);
 456                         for (int i = 0; i < pd.Count; ++i) {
 457                                 Argument.AType atype_modifier;
 458                                 switch (pd.FixedParameters [i].ModFlags & Parameter.Modifier.RefOutMask) {
 459                                 case Parameter.Modifier.REF:
 460                                         atype_modifier = Argument.AType.Ref;
 461                                         break;
 462                                 case Parameter.Modifier.OUT:
 463                                         atype_modifier = Argument.AType.Out;
 464                                         break;
 465                                 default:
 466                                         atype_modifier = 0;
 467                                         break;
 468                                 }
 469
 470                                 var ptype = types[i];
 471                                 if (ptype.BuiltinType == BuiltinTypeSpec.Type.Dynamic)
 472                                         ptype = rc.BuiltinTypes.Object;
 473
 474                                 delegate_arguments.Add (new Argument (new TypeExpression (ptype, loc), atype_modifier));
 475                         }
 476
 477                         return delegate_arguments;
 478                 }
 479
 480                 public override Expression CreateExpressionTree (ResolveContext ec)
 481                 {
 482                         MemberAccess ma = new MemberAccess (new MemberAccess (new QualifiedAliasMember ("global", "System", loc), "Delegate", loc), "CreateDelegate", loc);
 483
 484                         Arguments args = new Arguments (3);
 485                         args.Add (new Argument (new TypeOf (type, loc)));
 486
 487                         if (method_group.InstanceExpression == null)
 488                                 args.Add (new Argument (new NullLiteral (loc)));
 489                         else
 490                                 args.Add (new Argument (method_group.InstanceExpression));
 491
 492                         args.Add (new Argument (method_group.CreateExpressionTree (ec)));
 493                         Expression e = new Invocation (ma, args).Resolve (ec);
 494                         if (e == null)
 495                                 return null;
 496
 497                         e = Convert.ExplicitConversion (ec, e, type, loc);
 498                         if (e == null)
 499                                 return null;
 500
 501                         return e.CreateExpressionTree (ec);
 502                 }
 503
 504                 protected override Expression DoResolve (ResolveContext ec)
 505                 {
 506                         constructor_method = Delegate.GetConstructor (type);
 507
 508                         var invoke_method = Delegate.GetInvokeMethod (type);
 509
 510                         if (!ec.HasSet (ResolveContext.Options.ConditionalAccessReceiver)) {
 511                                 if (method_group.HasConditionalAccess ()) {
 512                                         conditional_access_receiver = true;
 513                                         ec.Set (ResolveContext.Options.ConditionalAccessReceiver);
 514                                 }
 515                         }
 516
 517                         Arguments arguments = CreateDelegateMethodArguments (ec, invoke_method.Parameters, invoke_method.Parameters.Types, loc);
 518                         method_group = method_group.OverloadResolve (ec, ref arguments, this, OverloadResolver.Restrictions.CovariantDelegate);
 519
 520                         if (conditional_access_receiver)
 521                                 ec.With (ResolveContext.Options.ConditionalAccessReceiver, false);
 522
 523                         if (method_group == null)
 524                                 return null;
 525
 526                         var delegate_method = method_group.BestCandidate;
 527
 528                         if (delegate_method.DeclaringType.IsNullableType) {
 529                                 ec.Report.Error (1728, loc, "Cannot create delegate from method `{0}' because it is a member of System.Nullable<T> type",
 530                                         delegate_method.GetSignatureForError ());
 531                                 return null;
 532                         }
 533
 534                         if (!AllowSpecialMethodsInvocation)
 535                                 Invocation.IsSpecialMethodInvocation (ec, delegate_method, loc);
 536
 537                         ExtensionMethodGroupExpr emg = method_group as ExtensionMethodGroupExpr;
 538                         if (emg != null) {
 539                                 method_group.InstanceExpression = emg.ExtensionExpression;
 540                                 TypeSpec e_type = emg.ExtensionExpression.Type;
 541                                 if (TypeSpec.IsValueType (e_type)) {
 542                                         ec.Report.Error (1113, loc, "Extension method `{0}' of value type `{1}' cannot be used to create delegates",
 543                                                 delegate_method.GetSignatureForError (), e_type.GetSignatureForError ());
 544                                 }
 545                         }
 546
 547                         TypeSpec rt = method_group.BestCandidateReturnType;
 548                         if (rt.BuiltinType == BuiltinTypeSpec.Type.Dynamic)
 549                                 rt = ec.BuiltinTypes.Object;
 550
 551                         if (!Delegate.IsTypeCovariant (ec, rt, invoke_method.ReturnType)) {
 552                                 Expression ret_expr = new TypeExpression (delegate_method.ReturnType, loc);
 553                                 Error_ConversionFailed (ec, delegate_method, ret_expr);
 554                         }
 555
 556                         if (method_group.IsConditionallyExcluded) {
 557                                 ec.Report.SymbolRelatedToPreviousError (delegate_method);
 558                                 MethodOrOperator m = delegate_method.MemberDefinition as MethodOrOperator;
 559                                 if (m != null && m.IsPartialDefinition) {
 560                                         ec.Report.Error (762, loc, "Cannot create delegate from partial method declaration `{0}'",
 561                                                 delegate_method.GetSignatureForError ());
 562                                 } else {
 563                                         ec.Report.Error (1618, loc, "Cannot create delegate with `{0}' because it has a Conditional attribute",
 564                                                 TypeManager.CSharpSignature (delegate_method));
 565                                 }
 566                         }
 567
 568                         var expr = method_group.InstanceExpression;
 569                         if (expr != null && (expr.Type.IsGenericParameter || !TypeSpec.IsReferenceType (expr.Type)))
 570                                 method_group.InstanceExpression = new BoxedCast (expr, ec.BuiltinTypes.Object);
 571
 572                         eclass = ExprClass.Value;
 573                         return this;
 574                 }
 575
 576                 public override void Emit (EmitContext ec)
 577                 {
 578                         if (conditional_access_receiver)
 579                                 ec.ConditionalAccess = new ConditionalAccessContext (type, ec.DefineLabel ());
 580
 581                         if (method_group.InstanceExpression == null) {
 582                                 ec.EmitNull ();
 583                         } else {
 584                                 var ie = new InstanceEmitter (method_group.InstanceExpression, false);
 585                                 ie.Emit (ec, method_group.ConditionalAccess);
 586                         }
 587
 588                         var delegate_method = method_group.BestCandidate;
 589
 590                         // Any delegate must be sealed
 591                         if (!delegate_method.DeclaringType.IsDelegate && delegate_method.IsVirtual && !method_group.IsBase) {
 592                                 ec.Emit (OpCodes.Dup);
 593                                 ec.Emit (OpCodes.Ldvirtftn, delegate_method);
 594                         } else {
 595                                 ec.Emit (OpCodes.Ldftn, delegate_method);
 596                         }
 597
 598                         ec.Emit (OpCodes.Newobj, constructor_method);
 599
 600                         if (conditional_access_receiver)
 601                                 ec.CloseConditionalAccess (null);
 602                 }
 603
 604                 public override void FlowAnalysis (FlowAnalysisContext fc)
 605                 {
 606                         base.FlowAnalysis (fc);
 607                         method_group.FlowAnalysis (fc);
 608
 609                         if (conditional_access_receiver)
 610                                 fc.ConditionalAccessEnd ();
 611                 }
 612
 613                 void Error_ConversionFailed (ResolveContext ec, MethodSpec method, Expression return_type)
 614                 {
 615                         var invoke_method = Delegate.GetInvokeMethod (type);
 616                         string member_name = method_group.InstanceExpression != null ?
 617                                 Delegate.FullDelegateDesc (method) :
 618                                 TypeManager.GetFullNameSignature (method);
 619
 620                         ec.Report.SymbolRelatedToPreviousError (type);
 621                         ec.Report.SymbolRelatedToPreviousError (method);
 622                         if (ec.Module.Compiler.Settings.Version == LanguageVersion.ISO_1) {
 623                                 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",
 624                                         method.ReturnType.GetSignatureForError (), member_name,
 625                                         invoke_method.ReturnType.GetSignatureForError (), Delegate.FullDelegateDesc (invoke_method));
 626                                 return;
 627                         }
 628
 629                         if (return_type == null) {
 630                                 ec.Report.Error (123, loc, "A method or delegate `{0}' parameters do not match delegate `{1}' parameters",
 631                                         member_name, Delegate.FullDelegateDesc (invoke_method));
 632                                 return;
 633                         }
 634
 635                         ec.Report.Error (407, loc, "A method or delegate `{0} {1}' return type does not match delegate `{2} {3}' return type",
 636                                 return_type.GetSignatureForError (), member_name,
 637                                 invoke_method.ReturnType.GetSignatureForError (), Delegate.FullDelegateDesc (invoke_method));
 638                 }
 639
 640                 public static bool ImplicitStandardConversionExists (ResolveContext ec, MethodGroupExpr mg, TypeSpec target_type)
 641                 {
 642 //                      if (target_type == TypeManager.delegate_type || target_type == TypeManager.multicast_delegate_type)
 643 //                              return false;
 644
 645                         var invoke = Delegate.GetInvokeMethod (target_type);
 646
 647                         Arguments arguments = CreateDelegateMethodArguments (ec, invoke.Parameters, invoke.Parameters.Types, mg.Location);
 648                         mg = mg.OverloadResolve (ec, ref arguments, null, OverloadResolver.Restrictions.CovariantDelegate | OverloadResolver.Restrictions.ProbingOnly);
 649                         return mg != null && Delegate.IsTypeCovariant (ec, mg.BestCandidateReturnType, invoke.ReturnType);
 650                 }
 651
 652                 #region IErrorHandler Members
 653
 654                 bool OverloadResolver.IErrorHandler.AmbiguousCandidates (ResolveContext ec, MemberSpec best, MemberSpec ambiguous)
 655                 {
 656                         return false;
 657                 }
 658
 659                 bool OverloadResolver.IErrorHandler.ArgumentMismatch (ResolveContext rc, MemberSpec best, Argument arg, int index)
 660                 {
 661                         Error_ConversionFailed (rc, best as MethodSpec, null);
 662                         return true;
 663                 }
 664
 665                 bool OverloadResolver.IErrorHandler.NoArgumentMatch (ResolveContext rc, MemberSpec best)
 666                 {
 667                         Error_ConversionFailed (rc, best as MethodSpec, null);
 668                         return true;
 669                 }
 670
 671                 bool OverloadResolver.IErrorHandler.TypeInferenceFailed (ResolveContext rc, MemberSpec best)
 672                 {
 673                         return false;
 674                 }
 675
 676                 #endregion
 677         }
 678
 679         //
 680         // Created from the conversion code
 681         //
 682         public class ImplicitDelegateCreation : DelegateCreation
 683         {
 684                 Field mg_cache;
 685
 686                 public ImplicitDelegateCreation (TypeSpec delegateType, MethodGroupExpr mg, Location loc)
 687                 {
 688                         type = delegateType;
 689                         this.method_group = mg;
 690                         this.loc = loc;
 691                 }
 692
 693                 //
 694                 // Returns true when type is MVAR or has MVAR reference
 695                 //
 696                 public static bool ContainsMethodTypeParameter (TypeSpec type)
 697                 {
 698                         var tps = type as TypeParameterSpec;
 699                         if (tps != null)
 700                                 return tps.IsMethodOwned;
 701
 702                         var ec = type as ElementTypeSpec;
 703                         if (ec != null)
 704                                 return ContainsMethodTypeParameter (ec.Element);
 705
 706                         foreach (var t in type.TypeArguments) {
 707                                 if (ContainsMethodTypeParameter (t)) {
 708                                         return true;
 709                                 }
 710                         }
 711
 712                         if (type.IsNested)
 713                                 return ContainsMethodTypeParameter (type.DeclaringType);
 714
 715                         return false;
 716                 }
 717
 718                 bool HasMvar ()
 719                 {
 720                         if (ContainsMethodTypeParameter (type))
 721                                 return false;
 722
 723                         var best = method_group.BestCandidate;
 724                         if (ContainsMethodTypeParameter (best.DeclaringType))
 725                                 return false;
 726
 727                         if (best.TypeArguments != null) {
 728                                 foreach (var ta in best.TypeArguments) {
 729                                         if (ContainsMethodTypeParameter (ta))
 730                                                 return false;
 731                                 }
 732                         }
 733
 734                         return true;
 735                 }
 736
 737                 protected override Expression DoResolve (ResolveContext ec)
 738                 {
 739                         var expr = base.DoResolve (ec);
 740                         if (expr == null)
 741                                 return ErrorExpression.Instance;
 742
 743                         if (ec.IsInProbingMode)
 744                                 return expr;
 745
 746                         //
 747                         // Cache any static delegate creation
 748                         //
 749                         if (method_group.InstanceExpression != null)
 750                                 return expr;
 751
 752                         //
 753                         // Cannot easily cache types with MVAR
 754                         //
 755                         if (!HasMvar ())
 756                                 return expr;
 757
 758                         //
 759                         // Create type level cache for a delegate instance
 760                         //
 761                         var parent = ec.CurrentMemberDefinition.Parent.PartialContainer;
 762                         int id = parent.MethodGroupsCounter++;
 763
 764                         mg_cache = new Field (parent, new TypeExpression (type, loc),
 765                                 Modifiers.STATIC | Modifiers.PRIVATE | Modifiers.COMPILER_GENERATED,
 766                                 new MemberName (CompilerGeneratedContainer.MakeName (null, "f", "mg$cache", id), loc), null);
 767                         mg_cache.Define ();
 768                         parent.AddField (mg_cache);
 769
 770                         return expr;
 771                 }
 772
 773                 public override void Emit (EmitContext ec)
 774                 {
 775                         Label l_initialized = ec.DefineLabel ();
 776
 777                         if (mg_cache != null) {
 778                                 ec.Emit (OpCodes.Ldsfld, mg_cache.Spec);
 779                                 ec.Emit (OpCodes.Brtrue_S, l_initialized);
 780                         }
 781
 782                         base.Emit (ec);
 783
 784                         if (mg_cache != null) {
 785                                 ec.Emit (OpCodes.Stsfld, mg_cache.Spec);
 786                                 ec.MarkLabel (l_initialized);
 787                                 ec.Emit (OpCodes.Ldsfld, mg_cache.Spec);
 788                         }
 789                 }
 790         }
 791
 792         //
 793         // A delegate-creation-expression, invoked from the `New' class
 794         //
 795         public class NewDelegate : DelegateCreation
 796         {
 797                 public Arguments Arguments;
 798
 799                 //
 800                 // This constructor is invoked from the `New' expression
 801                 //
 802                 public NewDelegate (TypeSpec type, Arguments Arguments, Location loc)
 803                 {
 804                         this.type = type;
 805                         this.Arguments = Arguments;
 806                         this.loc  = loc;
 807                 }
 808
 809                 protected override Expression DoResolve (ResolveContext ec)
 810                 {
 811                         if (Arguments == null || Arguments.Count != 1) {
 812                                 ec.Report.Error (149, loc, "Method name expected");
 813                                 return null;
 814                         }
 815
 816                         Argument a = Arguments [0];
 817                         if (!a.ResolveMethodGroup (ec))
 818                                 return null;
 819
 820                         Expression e = a.Expr;
 821
 822                         AnonymousMethodExpression ame = e as AnonymousMethodExpression;
 823                         if (ame != null && ec.Module.Compiler.Settings.Version != LanguageVersion.ISO_1) {
 824                                 e = ame.Compatible (ec, type);
 825                                 if (e == null)
 826                                         return null;
 827
 828                                 return e.Resolve (ec);
 829                         }
 830
 831                         method_group = e as MethodGroupExpr;
 832                         if (method_group == null) {
 833                                 if (e.Type.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
 834                                         e = Convert.ImplicitConversionRequired (ec, e, type, loc);
 835                                 } else if (!e.Type.IsDelegate) {
 836                                         e.Error_UnexpectedKind (ec, ResolveFlags.MethodGroup | ResolveFlags.Type, loc);
 837                                         return null;
 838                                 }
 839
 840                                 //
 841                                 // An argument is not a method but another delegate
 842                                 //
 843                                 method_group = new MethodGroupExpr (Delegate.GetInvokeMethod (e.Type), e.Type, loc);
 844                                 method_group.InstanceExpression = e;
 845                         }
 846
 847                         return base.DoResolve (ec);
 848                 }
 849         }
 850
 851         //
 852         // Invocation converted to delegate Invoke call
 853         //
 854         class DelegateInvocation : ExpressionStatement
 855         {
 856                 readonly Expression InstanceExpr;
 857                 readonly bool conditionalAccessReceiver;
 858                 Arguments arguments;
 859                 MethodSpec method;
 860
 861                 public DelegateInvocation (Expression instance_expr, Arguments args, bool conditionalAccessReceiver, Location loc)
 862                 {
 863                         this.InstanceExpr = instance_expr;
 864                         this.arguments = args;
 865                         this.conditionalAccessReceiver = conditionalAccessReceiver;
 866                         this.loc = loc;
 867                 }
 868
 869                 public override bool ContainsEmitWithAwait ()
 870                 {
 871                         return InstanceExpr.ContainsEmitWithAwait () || (arguments != null && arguments.ContainsEmitWithAwait ());
 872                 }
 873
 874                 public override Expression CreateExpressionTree (ResolveContext ec)
 875                 {
 876                         Arguments args = Arguments.CreateForExpressionTree (ec, this.arguments,
 877                                 InstanceExpr.CreateExpressionTree (ec));
 878
 879                         return CreateExpressionFactoryCall (ec, "Invoke", args);
 880                 }
 881
 882                 public override void FlowAnalysis (FlowAnalysisContext fc)
 883                 {
 884                         InstanceExpr.FlowAnalysis (fc);
 885                         if (arguments != null)
 886                                 arguments.FlowAnalysis (fc);
 887                 }
 888
 889                 protected override Expression DoResolve (ResolveContext ec)
 890                 {
 891                         TypeSpec del_type = InstanceExpr.Type;
 892                         if (del_type == null)
 893                                 return null;
 894
 895                         //
 896                         // Do only core overload resolution the rest of the checks has been
 897                         // done on primary expression
 898                         //
 899                         method = Delegate.GetInvokeMethod (del_type);
 900                         var res = new OverloadResolver (new MemberSpec[] { method }, OverloadResolver.Restrictions.DelegateInvoke, loc);
 901                         var valid = res.ResolveMember<MethodSpec> (ec, ref arguments);
 902                         if (valid == null && !res.BestCandidateIsDynamic)
 903                                 return null;
 904
 905                         type = method.ReturnType;
 906                         if (conditionalAccessReceiver)
 907                                 type = LiftMemberType (ec, type);
 908
 909                         eclass = ExprClass.Value;
 910                         return this;
 911                 }
 912
 913                 public override void Emit (EmitContext ec)
 914                 {
 915                         if (conditionalAccessReceiver) {
 916                                 ec.ConditionalAccess = new ConditionalAccessContext (type, ec.DefineLabel ());
 917                         }
 918
 919                         //
 920                         // Invocation on delegates call the virtual Invoke member
 921                         // so we are always `instance' calls
 922                         //
 923                         var call = new CallEmitter ();
 924                         call.InstanceExpression = InstanceExpr;
 925                         call.Emit (ec, method, arguments, loc);
 926
 927                         if (conditionalAccessReceiver)
 928                                 ec.CloseConditionalAccess (type.IsNullableType && type !=  method.ReturnType ? type : null);
 929                 }
 930
 931                 public override void EmitStatement (EmitContext ec)
 932                 {
 933                         if (conditionalAccessReceiver) {
 934                                 ec.ConditionalAccess = new ConditionalAccessContext (type, ec.DefineLabel ()) {
 935                                         Statement = true
 936                                 };
 937                         }
 938
 939                         var call = new CallEmitter ();
 940                         call.InstanceExpression = InstanceExpr;
 941                         call.EmitStatement (ec, method, arguments, loc);
 942
 943                         if (conditionalAccessReceiver)
 944                                 ec.CloseConditionalAccess (null);
 945                 }
 946
 947                 public override System.Linq.Expressions.Expression MakeExpression (BuilderContext ctx)
 948                 {
 949                         return Invocation.MakeExpression (ctx, InstanceExpr, method, arguments);
 950                 }
 951         }
 952 }