mcs/mcs/delegate.cs

   1 //
   2 // delegate.cs: Delegate Handler
   3 //
   4 // Authors:
   5 //     Ravi Pratap (ravi@ximian.com)
   6 //     Miguel de Icaza (miguel@ximian.com)
   7 //     Marek Safar (marek.safar@gmail.com)
   8 //
   9 // Dual licensed under the terms of the MIT X11 or GNU GPL
  10 //
  11 // Copyright 2001 Ximian, Inc (http://www.ximian.com)
  12 // Copyright 2003-2009 Novell, Inc (http://www.novell.com)
  13 // Copyright 2011 Xamarin Inc
  14 //
  15
  16 using System;
  17
  18 #if STATIC
  19 using SecurityType = System.Collections.Generic.List<IKVM.Reflection.Emit.CustomAttributeBuilder>;
  20 using IKVM.Reflection;
  21 using IKVM.Reflection.Emit;
  22 #else
  23 using SecurityType = System.Collections.Generic.Dictionary<System.Security.Permissions.SecurityAction, System.Security.PermissionSet>;
  24 using System.Reflection;
  25 using System.Reflection.Emit;
  26 #endif
  27
  28 namespace Mono.CSharp {
  29
  30         //
  31         // Delegate container implementation
  32         //
  33         public class Delegate : TypeDefinition, IParametersMember
  34         {
  35                 FullNamedExpression ReturnType;
  36                 readonly ParametersCompiled parameters;
  37
  38                 Constructor Constructor;
  39                 Method InvokeBuilder;
  40                 Method BeginInvokeBuilder;
  41                 Method EndInvokeBuilder;
  42
  43                 static readonly string[] attribute_targets = new string [] { "type", "return" };
  44
  45                 public static readonly string InvokeMethodName = "Invoke";
  46
  47                 Expression instance_expr;
  48                 ReturnParameter return_attributes;
  49
  50                 SecurityType declarative_security;
  51
  52                 const Modifiers MethodModifiers = Modifiers.PUBLIC | Modifiers.VIRTUAL;
  53
  54                 const Modifiers AllowedModifiers =
  55                         Modifiers.NEW |
  56                         Modifiers.PUBLIC |
  57                         Modifiers.PROTECTED |
  58                         Modifiers.INTERNAL |
  59                         Modifiers.UNSAFE |
  60                         Modifiers.PRIVATE;
  61
  62                 public Delegate (TypeContainer parent, FullNamedExpression type, Modifiers mod_flags, MemberName name, ParametersCompiled param_list,
  63                                  Attributes attrs)
  64                         : base (parent, name, attrs, MemberKind.Delegate)
  65
  66                 {
  67                         this.ReturnType = type;
  68                         ModFlags        = ModifiersExtensions.Check (AllowedModifiers, mod_flags,
  69                                                            IsTopLevel ? Modifiers.INTERNAL :
  70                                                            Modifiers.PRIVATE, name.Location, Report);
  71                         parameters      = param_list;
  72                         spec = new TypeSpec (Kind, null, this, null, ModFlags | Modifiers.SEALED);
  73                 }
  74
  75                 #region Properties
  76                 public TypeSpec MemberType {
  77                         get {
  78                                 return ReturnType.Type;
  79                         }
  80                 }
  81
  82                 public AParametersCollection Parameters {
  83                         get {
  84                                 return parameters;
  85                         }
  86                 }
  87
  88                 public FullNamedExpression TypExpression {
  89                         get {
  90                                 return ReturnType;
  91                         }
  92                 }
  93
  94                 #endregion
  95
  96                 public override void Accept (StructuralVisitor visitor)
  97                 {
  98                         visitor.Visit (this);
  99                 }
 100
 101                 public override void ApplyAttributeBuilder (Attribute a, MethodSpec ctor, byte[] cdata, PredefinedAttributes pa)
 102                 {
 103                         if (a.Target == AttributeTargets.ReturnValue) {
 104                                 CreateReturnBuilder ();
 105                                 return_attributes.ApplyAttributeBuilder (a, ctor, cdata, pa);
 106                                 return;
 107                         }
 108
 109                         if (a.IsValidSecurityAttribute ()) {
 110                                 a.ExtractSecurityPermissionSet (ctor, ref declarative_security);
 111                                 return;
 112                         }
 113
 114                         base.ApplyAttributeBuilder (a, ctor, cdata, pa);
 115                 }
 116
 117                 public override AttributeTargets AttributeTargets {
 118                         get {
 119                                 return AttributeTargets.Delegate;
 120                         }
 121                 }
 122
 123                 ReturnParameter CreateReturnBuilder ()
 124                 {
 125                         return return_attributes ?? (return_attributes = new ReturnParameter (this, InvokeBuilder.MethodBuilder, Location));
 126                 }
 127
 128                 protected override bool DoDefineMembers ()
 129                 {
 130                         var builtin_types = Compiler.BuiltinTypes;
 131
 132                         var ctor_parameters = ParametersCompiled.CreateFullyResolved (
 133                                 new [] {
 134                                         new Parameter (new TypeExpression (builtin_types.Object, Location), "object", Parameter.Modifier.NONE, null, Location),
 135                                         new Parameter (new TypeExpression (builtin_types.IntPtr, Location), "method", Parameter.Modifier.NONE, null, Location)
 136                                 },
 137                                 new [] {
 138                                         builtin_types.Object,
 139                                         builtin_types.IntPtr
 140                                 }
 141                         );
 142
 143                         Constructor = new Constructor (this, Constructor.ConstructorName,
 144                                 Modifiers.PUBLIC, null, ctor_parameters, Location);
 145                         Constructor.Define ();
 146
 147                         //
 148                         // Here the various methods like Invoke, BeginInvoke etc are defined
 149                         //
 150                         // First, call the `out of band' special method for
 151                         // defining recursively any types we need:
 152                         //
 153                         var p = parameters;
 154
 155                         if (!p.Resolve (this))
 156                                 return false;
 157
 158                         //
 159                         // Invoke method
 160                         //
 161
 162                         // Check accessibility
 163                         foreach (var partype in p.Types) {
 164                                 if (!IsAccessibleAs (partype)) {
 165                                         Report.SymbolRelatedToPreviousError (partype);
 166                                         Report.Error (59, Location,
 167                                                 "Inconsistent accessibility: parameter type `{0}' is less accessible than delegate `{1}'",
 168                                                 partype.GetSignatureForError (), GetSignatureForError ());
 169                                 }
 170                         }
 171
 172                         var ret_type = ReturnType.ResolveAsType (this);
 173                         if (ret_type == null)
 174                                 return false;
 175
 176                         //
 177                         // We don't have to check any others because they are all
 178                         // guaranteed to be accessible - they are standard types.
 179                         //
 180                         if (!IsAccessibleAs (ret_type)) {
 181                                 Report.SymbolRelatedToPreviousError (ret_type);
 182                                 Report.Error (58, Location,
 183                                                   "Inconsistent accessibility: return type `" +
 184                                                   ret_type.GetSignatureForError () + "' is less " +
 185                                                   "accessible than delegate `" + GetSignatureForError () + "'");
 186                                 return false;
 187                         }
 188
 189                         CheckProtectedModifier ();
 190
 191                         if (Compiler.Settings.StdLib && ret_type.IsSpecialRuntimeType) {
 192                                 Method.Error1599 (Location, ret_type, Report);
 193                                 return false;
 194                         }
 195
 196                         VarianceDecl.CheckTypeVariance (ret_type, Variance.Covariant, this);
 197
 198                         var resolved_rt = new TypeExpression (ret_type, Location);
 199                         InvokeBuilder = new Method (this, resolved_rt, MethodModifiers, new MemberName (InvokeMethodName), p, null);
 200                         InvokeBuilder.Define ();
 201
 202                         //
 203                         // Don't emit async method for compiler generated delegates (e.g. dynamic site containers)
 204                         //
 205                         if (!IsCompilerGenerated) {
 206                                 DefineAsyncMethods (resolved_rt);
 207                         }
 208
 209                         return true;
 210                 }
 211
 212                 void DefineAsyncMethods (TypeExpression returnType)
 213                 {
 214                         var iasync_result = Module.PredefinedTypes.IAsyncResult;
 215                         var async_callback = Module.PredefinedTypes.AsyncCallback;
 216
 217                         //
 218                         // It's ok when async types don't exist, the delegate will have Invoke method only
 219                         //
 220                         if (!iasync_result.Define () || !async_callback.Define ())
 221                                 return;
 222
 223                         //
 224                         // BeginInvoke
 225                         //
 226                         ParametersCompiled async_parameters;
 227                         if (Parameters.Count == 0) {
 228                                 async_parameters = ParametersCompiled.EmptyReadOnlyParameters;
 229                         } else {
 230                                 var compiled = new Parameter[Parameters.Count];
 231                                 for (int i = 0; i < compiled.Length; ++i) {
 232                                         var p = parameters[i];
 233                                         compiled[i] = new Parameter (new TypeExpression (parameters.Types[i], Location),
 234                                                 p.Name,
 235                                                 p.ModFlags & Parameter.Modifier.RefOutMask,
 236                                                 p.OptAttributes == null ? null : p.OptAttributes.Clone (), Location);
 237                                 }
 238
 239                                 async_parameters = new ParametersCompiled (compiled);
 240                         }
 241
 242                         async_parameters = ParametersCompiled.MergeGenerated (Compiler, async_parameters, false,
 243                                 new Parameter[] {
 244                                         new Parameter (new TypeExpression (async_callback.TypeSpec, Location), "callback", Parameter.Modifier.NONE, null, Location),
 245                                         new Parameter (new TypeExpression (Compiler.BuiltinTypes.Object, Location), "object", Parameter.Modifier.NONE, null, Location)
 246                                 },
 247                                 new [] {
 248                                         async_callback.TypeSpec,
 249                                         Compiler.BuiltinTypes.Object
 250                                 }
 251                         );
 252
 253                         BeginInvokeBuilder = new Method (this,
 254                                 new TypeExpression (iasync_result.TypeSpec, Location), MethodModifiers,
 255                                 new MemberName ("BeginInvoke"), async_parameters, null);
 256                         BeginInvokeBuilder.Define ();
 257
 258                         //
 259                         // EndInvoke is a bit more interesting, all the parameters labeled as
 260                         // out or ref have to be duplicated here.
 261                         //
 262
 263                         //
 264                         // Define parameters, and count out/ref parameters
 265                         //
 266                         ParametersCompiled end_parameters;
 267                         int out_params = 0;
 268
 269                         foreach (Parameter p in Parameters.FixedParameters) {
 270                                 if ((p.ModFlags & Parameter.Modifier.RefOutMask) != 0)
 271                                         ++out_params;
 272                         }
 273
 274                         if (out_params > 0) {
 275                                 Parameter[] end_params = new Parameter[out_params];
 276
 277                                 int param = 0;
 278                                 for (int i = 0; i < Parameters.FixedParameters.Length; ++i) {
 279                                         Parameter p = parameters [i];
 280                                         if ((p.ModFlags & Parameter.Modifier.RefOutMask) == 0)
 281                                                 continue;
 282
 283                                         end_params [param++] = new Parameter (new TypeExpression (p.Type, Location),
 284                                                 p.Name,
 285                                                 p.ModFlags & Parameter.Modifier.RefOutMask,
 286                                                 p.OptAttributes == null ? null : p.OptAttributes.Clone (), Location);
 287                                 }
 288
 289                                 end_parameters = new ParametersCompiled (end_params);
 290                         } else {
 291                                 end_parameters = ParametersCompiled.EmptyReadOnlyParameters;
 292                         }
 293
 294                         end_parameters = ParametersCompiled.MergeGenerated (Compiler, end_parameters, false,
 295                                 new Parameter (
 296                                         new TypeExpression (iasync_result.TypeSpec, Location),
 297                                         "result", Parameter.Modifier.NONE, null, Location),
 298                                 iasync_result.TypeSpec);
 299
 300                         //
 301                         // Create method, define parameters, register parameters with type system
 302                         //
 303                         EndInvokeBuilder = new Method (this, returnType, MethodModifiers, new MemberName ("EndInvoke"), end_parameters, null);
 304                         EndInvokeBuilder.Define ();
 305                 }
 306
 307                 public override void PrepareEmit ()
 308                 {
 309                         if ((caching_flags & Flags.CloseTypeCreated) != 0)
 310                                 return;
 311
 312                         InvokeBuilder.PrepareEmit ();
 313                         if (BeginInvokeBuilder != null) {
 314                                 BeginInvokeBuilder.TypeExpression = null;
 315                                 EndInvokeBuilder.TypeExpression = null;
 316                                 BeginInvokeBuilder.PrepareEmit ();
 317                                 EndInvokeBuilder.PrepareEmit ();
 318                         }
 319                 }
 320
 321                 public override void Emit ()
 322                 {
 323                         base.Emit ();
 324
 325                         if (declarative_security != null) {
 326                                 foreach (var de in declarative_security) {
 327 #if STATIC
 328                                         TypeBuilder.__AddDeclarativeSecurity (de);
 329 #else
 330                                         TypeBuilder.AddDeclarativeSecurity (de.Key, de.Value);
 331 #endif
 332                                 }
 333                         }
 334
 335                         var rtype = ReturnType.Type;
 336                         if (rtype != null) {
 337                                 if (rtype.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
 338                                         Module.PredefinedAttributes.Dynamic.EmitAttribute (CreateReturnBuilder ().Builder);
 339                                 } else if (rtype.HasDynamicElement) {
 340                                         Module.PredefinedAttributes.Dynamic.EmitAttribute (CreateReturnBuilder ().Builder, rtype, Location);
 341                                 }
 342
 343                                 if (rtype.HasNamedTupleElement) {
 344                                         Module.PredefinedAttributes.TupleElementNames.EmitAttribute (CreateReturnBuilder ().Builder, rtype, Location);
 345                                 }
 346
 347                                 ConstraintChecker.Check (this, ReturnType.Type, ReturnType.Location);
 348                         }
 349
 350                         Constructor.ParameterInfo.ApplyAttributes (this, Constructor.ConstructorBuilder);
 351                         Constructor.ConstructorBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 352
 353                         parameters.CheckConstraints (this);
 354                         parameters.ApplyAttributes (this, InvokeBuilder.MethodBuilder);
 355                         InvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 356
 357                         if (BeginInvokeBuilder != null) {
 358                                 BeginInvokeBuilder.ParameterInfo.ApplyAttributes (this, BeginInvokeBuilder.MethodBuilder);
 359                                 EndInvokeBuilder.ParameterInfo.ApplyAttributes (this, EndInvokeBuilder.MethodBuilder);
 360
 361                                 BeginInvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 362                                 EndInvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 363                         }
 364                 }
 365
 366                 protected override TypeSpec[] ResolveBaseTypes (out FullNamedExpression base_class)
 367                 {
 368                         base_type = Compiler.BuiltinTypes.MulticastDelegate;
 369                         base_class = null;
 370                         return null;
 371                 }
 372
 373                 protected override TypeAttributes TypeAttr {
 374                         get {
 375                                 return base.TypeAttr | TypeAttributes.Class | TypeAttributes.Sealed;
 376                         }
 377                 }
 378
 379                 public override string[] ValidAttributeTargets {
 380                         get {
 381                                 return attribute_targets;
 382                         }
 383                 }
 384
 385                 //TODO: duplicate
 386                 protected override bool VerifyClsCompliance ()
 387                 {
 388                         if (!base.VerifyClsCompliance ()) {
 389                                 return false;
 390                         }
 391
 392                         parameters.VerifyClsCompliance (this);
 393
 394                         if (!InvokeBuilder.MemberType.IsCLSCompliant ()) {
 395                                 Report.Warning (3002, 1, Location, "Return type of `{0}' is not CLS-compliant",
 396                                         GetSignatureForError ());
 397                         }
 398                         return true;
 399                 }
 400
 401
 402                 public static MethodSpec GetConstructor (TypeSpec delType)
 403                 {
 404                         var ctor = MemberCache.FindMember (delType, MemberFilter.Constructor (null), BindingRestriction.DeclaredOnly);
 405                         return (MethodSpec) ctor;
 406                 }
 407
 408                 //
 409                 // Returns the "Invoke" from a delegate type
 410                 //
 411                 public static MethodSpec GetInvokeMethod (TypeSpec delType)
 412                 {
 413                         var invoke = MemberCache.FindMember (delType,
 414                                 MemberFilter.Method (InvokeMethodName, 0, null, null),
 415                                 BindingRestriction.DeclaredOnly);
 416
 417                         return (MethodSpec) invoke;
 418                 }
 419
 420                 public static AParametersCollection GetParameters (TypeSpec delType)
 421                 {
 422                         var invoke_mb = GetInvokeMethod (delType);
 423                         return invoke_mb.Parameters;
 424                 }
 425
 426                 //
 427                 // 15.2 Delegate compatibility
 428                 //
 429                 public static bool IsTypeCovariant (ResolveContext rc, TypeSpec a, TypeSpec b)
 430                 {
 431                         //
 432                         // For each value parameter (a parameter with no ref or out modifier), an
 433                         // identity conversion or implicit reference conversion exists from the
 434                         // parameter type in D to the corresponding parameter type in M
 435                         //
 436                         if (a == b)
 437                                 return true;
 438
 439                         if (rc.Module.Compiler.Settings.Version == LanguageVersion.ISO_1)
 440                                 return false;
 441
 442                         if (a.IsGenericParameter && b.IsGenericParameter)
 443                                 return a == b;
 444
 445                         return Convert.ImplicitReferenceConversionExists (a, b);
 446                 }
 447
 448                 public static string FullDelegateDesc (MethodSpec invoke_method)
 449                 {
 450                         return TypeManager.GetFullNameSignature (invoke_method).Replace (".Invoke", "");
 451                 }
 452
 453                 public Expression InstanceExpression {
 454                         get {
 455                                 return instance_expr;
 456                         }
 457                         set {
 458                                 instance_expr = value;
 459                         }
 460                 }
 461         }
 462
 463         //
 464         // Base class for `NewDelegate' and `ImplicitDelegateCreation'
 465         //
 466         public abstract class DelegateCreation : Expression, OverloadResolver.IErrorHandler
 467         {
 468                 protected MethodSpec constructor_method;
 469                 protected MethodGroupExpr method_group;
 470
 471                 public bool AllowSpecialMethodsInvocation { get; set; }
 472
 473                 public override bool ContainsEmitWithAwait ()
 474                 {
 475                         var instance = method_group.InstanceExpression;
 476                         return instance != null && instance.ContainsEmitWithAwait ();
 477                 }
 478
 479                 public static Arguments CreateDelegateMethodArguments (ResolveContext rc, AParametersCollection pd, TypeSpec[] types, Location loc)
 480                 {
 481                         Arguments delegate_arguments = new Arguments (pd.Count);
 482                         for (int i = 0; i < pd.Count; ++i) {
 483                                 Argument.AType atype_modifier;
 484                                 switch (pd.FixedParameters [i].ModFlags & Parameter.Modifier.RefOutMask) {
 485                                 case Parameter.Modifier.REF:
 486                                         atype_modifier = Argument.AType.Ref;
 487                                         break;
 488                                 case Parameter.Modifier.OUT:
 489                                         atype_modifier = Argument.AType.Out;
 490                                         break;
 491                                 default:
 492                                         atype_modifier = 0;
 493                                         break;
 494                                 }
 495
 496                                 var ptype = types[i];
 497                                 if (ptype.BuiltinType == BuiltinTypeSpec.Type.Dynamic)
 498                                         ptype = rc.BuiltinTypes.Object;
 499
 500                                 delegate_arguments.Add (new Argument (new TypeExpression (ptype, loc), atype_modifier));
 501                         }
 502
 503                         return delegate_arguments;
 504                 }
 505
 506                 public override Expression CreateExpressionTree (ResolveContext ec)
 507                 {
 508                         Arguments args = new Arguments (2);
 509                         args.Add (new Argument (new TypeOf (type, loc)));
 510
 511                         if (method_group.InstanceExpression == null)
 512                                 args.Add (new Argument (new NullLiteral (loc)));
 513                         else
 514                                 args.Add (new Argument (method_group.InstanceExpression));
 515
 516                         Expression ma;
 517                         var create_v45 = ec.Module.PredefinedMembers.MethodInfoCreateDelegate.Get ();
 518                         if (create_v45 != null) {
 519                                 //
 520                                 // .NET 4.5 has better API but it produces different instance than Delegate::CreateDelegate
 521                                 // and because csc uses this enhancement we have to as well to be fully compatible
 522                                 //
 523                                 var mg = MethodGroupExpr.CreatePredefined (create_v45, create_v45.DeclaringType, loc);
 524                                 mg.InstanceExpression = method_group.CreateExpressionTree (ec);
 525                                 ma = mg;
 526                         } else {
 527                                 ma = new MemberAccess (new MemberAccess (new QualifiedAliasMember ("global", "System", loc), "Delegate", loc), "CreateDelegate", loc);
 528                                 args.Add (new Argument (method_group.CreateExpressionTree (ec)));
 529                         }
 530
 531                         Expression e = new Invocation (ma, args).Resolve (ec);
 532                         if (e == null)
 533                                 return null;
 534
 535                         e = Convert.ExplicitConversion (ec, e, type, loc);
 536                         if (e == null)
 537                                 return null;
 538
 539                         return e.CreateExpressionTree (ec);
 540                 }
 541
 542                 void ResolveConditionalAccessReceiver (ResolveContext rc)
 543                 {
 544                         // LAMESPEC: Not sure why this is explicitly disallowed with very odd error message
 545                         if (!rc.HasSet (ResolveContext.Options.DontSetConditionalAccessReceiver) && method_group.HasConditionalAccess ()) {
 546                                 Error_OperatorCannotBeApplied (rc, loc, "?", method_group.Type);
 547                         }
 548                 }
 549
 550                 protected override Expression DoResolve (ResolveContext ec)
 551                 {
 552                         constructor_method = Delegate.GetConstructor (type);
 553
 554                         var invoke_method = Delegate.GetInvokeMethod (type);
 555
 556                         ResolveConditionalAccessReceiver (ec);
 557
 558                         Arguments arguments = CreateDelegateMethodArguments (ec, invoke_method.Parameters, invoke_method.Parameters.Types, loc);
 559                         method_group = method_group.OverloadResolve (ec, ref arguments, this, OverloadResolver.Restrictions.CovariantDelegate);
 560
 561                         if (method_group == null)
 562                                 return null;
 563
 564                         var delegate_method = method_group.BestCandidate;
 565
 566                         if (delegate_method.DeclaringType.IsNullableType) {
 567                                 ec.Report.Error (1728, loc, "Cannot create delegate from method `{0}' because it is a member of System.Nullable<T> type",
 568                                         delegate_method.GetSignatureForError ());
 569                                 return null;
 570                         }
 571
 572                         if (!AllowSpecialMethodsInvocation)
 573                                 Invocation.IsSpecialMethodInvocation (ec, delegate_method, loc);
 574
 575                         ExtensionMethodGroupExpr emg = method_group as ExtensionMethodGroupExpr;
 576                         if (emg != null) {
 577                                 method_group.InstanceExpression = emg.ExtensionExpression;
 578                                 TypeSpec e_type = emg.ExtensionExpression.Type;
 579                                 if (TypeSpec.IsValueType (e_type)) {
 580                                         ec.Report.Error (1113, loc, "Extension method `{0}' of value type `{1}' cannot be used to create delegates",
 581                                                 delegate_method.GetSignatureForError (), e_type.GetSignatureForError ());
 582                                 }
 583                         }
 584
 585                         TypeSpec rt = method_group.BestCandidateReturnType;
 586                         if (rt.BuiltinType == BuiltinTypeSpec.Type.Dynamic)
 587                                 rt = ec.BuiltinTypes.Object;
 588
 589                         if (!Delegate.IsTypeCovariant (ec, rt, invoke_method.ReturnType)) {
 590                                 Expression ret_expr = new TypeExpression (delegate_method.ReturnType, loc);
 591                                 Error_ConversionFailed (ec, delegate_method, ret_expr);
 592                         }
 593
 594                         if (method_group.IsConditionallyExcluded) {
 595                                 ec.Report.SymbolRelatedToPreviousError (delegate_method);
 596                                 MethodOrOperator m = delegate_method.MemberDefinition as MethodOrOperator;
 597                                 if (m != null && m.IsPartialDefinition) {
 598                                         ec.Report.Error (762, loc, "Cannot create delegate from partial method declaration `{0}'",
 599                                                 delegate_method.GetSignatureForError ());
 600                                 } else {
 601                                         ec.Report.Error (1618, loc, "Cannot create delegate with `{0}' because it has a Conditional attribute",
 602                                                 TypeManager.CSharpSignature (delegate_method));
 603                                 }
 604                         }
 605
 606                         var expr = method_group.InstanceExpression;
 607                         if (expr != null && (expr.Type.IsGenericParameter || !TypeSpec.IsReferenceType (expr.Type)))
 608                                 method_group.InstanceExpression = new BoxedCast (expr, ec.BuiltinTypes.Object);
 609
 610                         eclass = ExprClass.Value;
 611                         return this;
 612                 }
 613
 614                 public override void Emit (EmitContext ec)
 615                 {
 616                         if (method_group.InstanceExpression == null) {
 617                                 ec.EmitNull ();
 618                         } else {
 619                                 var ie = new InstanceEmitter (method_group.InstanceExpression, false);
 620                                 ie.Emit (ec, method_group.ConditionalAccess);
 621                         }
 622
 623                         var delegate_method = method_group.BestCandidate;
 624
 625                         // Any delegate must be sealed
 626                         if (!delegate_method.DeclaringType.IsDelegate && delegate_method.IsVirtual && !method_group.IsBase) {
 627                                 ec.Emit (OpCodes.Dup);
 628                                 ec.Emit (OpCodes.Ldvirtftn, delegate_method);
 629                         } else {
 630                                 ec.Emit (OpCodes.Ldftn, delegate_method);
 631                         }
 632
 633                         ec.Emit (OpCodes.Newobj, constructor_method);
 634                 }
 635
 636                 public override void FlowAnalysis (FlowAnalysisContext fc)
 637                 {
 638                         base.FlowAnalysis (fc);
 639                         method_group.FlowAnalysis (fc);
 640                 }
 641
 642                 void Error_ConversionFailed (ResolveContext ec, MethodSpec method, Expression return_type)
 643                 {
 644                         var invoke_method = Delegate.GetInvokeMethod (type);
 645                         string member_name = method_group.InstanceExpression != null ?
 646                                 Delegate.FullDelegateDesc (method) :
 647                                 TypeManager.GetFullNameSignature (method);
 648
 649                         ec.Report.SymbolRelatedToPreviousError (type);
 650                         ec.Report.SymbolRelatedToPreviousError (method);
 651                         if (ec.Module.Compiler.Settings.Version == LanguageVersion.ISO_1) {
 652                                 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",
 653                                         method.ReturnType.GetSignatureForError (), member_name,
 654                                         invoke_method.ReturnType.GetSignatureForError (), Delegate.FullDelegateDesc (invoke_method));
 655                                 return;
 656                         }
 657
 658                         if (return_type == null) {
 659                                 ec.Report.Error (123, loc, "A method or delegate `{0}' parameters do not match delegate `{1}' parameters",
 660                                         member_name, Delegate.FullDelegateDesc (invoke_method));
 661                                 return;
 662                         }
 663
 664                         ec.Report.Error (407, loc, "A method or delegate `{0} {1}' return type does not match delegate `{2} {3}' return type",
 665                                 return_type.GetSignatureForError (), member_name,
 666                                 invoke_method.ReturnType.GetSignatureForError (), Delegate.FullDelegateDesc (invoke_method));
 667                 }
 668
 669                 public static bool ImplicitStandardConversionExists (ResolveContext ec, MethodGroupExpr mg, TypeSpec target_type)
 670                 {
 671 //                      if (target_type == TypeManager.delegate_type || target_type == TypeManager.multicast_delegate_type)
 672 //                              return false;
 673
 674                         var invoke = Delegate.GetInvokeMethod (target_type);
 675
 676                         Arguments arguments = CreateDelegateMethodArguments (ec, invoke.Parameters, invoke.Parameters.Types, mg.Location);
 677                         mg = mg.OverloadResolve (ec, ref arguments, null, OverloadResolver.Restrictions.CovariantDelegate | OverloadResolver.Restrictions.ProbingOnly);
 678                         return mg != null && Delegate.IsTypeCovariant (ec, mg.BestCandidateReturnType, invoke.ReturnType);
 679                 }
 680
 681                 #region IErrorHandler Members
 682
 683                 bool OverloadResolver.IErrorHandler.AmbiguousCandidates (ResolveContext ec, MemberSpec best, MemberSpec ambiguous)
 684                 {
 685                         return false;
 686                 }
 687
 688                 bool OverloadResolver.IErrorHandler.ArgumentMismatch (ResolveContext rc, MemberSpec best, Argument arg, int index)
 689                 {
 690                         Error_ConversionFailed (rc, best as MethodSpec, null);
 691                         return true;
 692                 }
 693
 694                 bool OverloadResolver.IErrorHandler.NoArgumentMatch (ResolveContext rc, MemberSpec best)
 695                 {
 696                         Error_ConversionFailed (rc, best as MethodSpec, null);
 697                         return true;
 698                 }
 699
 700                 bool OverloadResolver.IErrorHandler.TypeInferenceFailed (ResolveContext rc, MemberSpec best)
 701                 {
 702                         return false;
 703                 }
 704
 705                 #endregion
 706         }
 707
 708         //
 709         // Created from the conversion code
 710         //
 711         public class ImplicitDelegateCreation : DelegateCreation
 712         {
 713                 Field mg_cache;
 714
 715                 public ImplicitDelegateCreation (TypeSpec delegateType, MethodGroupExpr mg, Location loc)
 716                 {
 717                         type = delegateType;
 718                         this.method_group = mg;
 719                         this.loc = loc;
 720                 }
 721
 722                 //
 723                 // Returns true when type is MVAR or has MVAR reference
 724                 //
 725                 public static bool ContainsMethodTypeParameter (TypeSpec type)
 726                 {
 727                         var tps = type as TypeParameterSpec;
 728                         if (tps != null)
 729                                 return tps.IsMethodOwned;
 730
 731                         var ec = type as ElementTypeSpec;
 732                         if (ec != null)
 733                                 return ContainsMethodTypeParameter (ec.Element);
 734
 735                         foreach (var t in type.TypeArguments) {
 736                                 if (ContainsMethodTypeParameter (t)) {
 737                                         return true;
 738                                 }
 739                         }
 740
 741                         if (type.IsNested)
 742                                 return ContainsMethodTypeParameter (type.DeclaringType);
 743
 744                         return false;
 745                 }
 746
 747                 bool HasMvar ()
 748                 {
 749                         if (ContainsMethodTypeParameter (type))
 750                                 return false;
 751
 752                         var best = method_group.BestCandidate;
 753                         if (ContainsMethodTypeParameter (best.DeclaringType))
 754                                 return false;
 755
 756                         if (best.TypeArguments != null) {
 757                                 foreach (var ta in best.TypeArguments) {
 758                                         if (ContainsMethodTypeParameter (ta))
 759                                                 return false;
 760                                 }
 761                         }
 762
 763                         return true;
 764                 }
 765
 766                 protected override Expression DoResolve (ResolveContext ec)
 767                 {
 768                         var expr = base.DoResolve (ec);
 769                         if (expr == null)
 770                                 return ErrorExpression.Instance;
 771
 772                         if (ec.IsInProbingMode)
 773                                 return expr;
 774
 775                         //
 776                         // Cache any static delegate creation
 777                         //
 778                         if (method_group.InstanceExpression != null)
 779                                 return expr;
 780
 781                         //
 782                         // Cannot easily cache types with MVAR
 783                         //
 784                         if (!HasMvar ())
 785                                 return expr;
 786
 787                         //
 788                         // Create type level cache for a delegate instance
 789                         //
 790                         var parent = ec.CurrentMemberDefinition.Parent.PartialContainer;
 791                         int id = parent.MethodGroupsCounter++;
 792
 793                         mg_cache = new Field (parent, new TypeExpression (type, loc),
 794                                 Modifiers.STATIC | Modifiers.PRIVATE | Modifiers.COMPILER_GENERATED,
 795                                 new MemberName (CompilerGeneratedContainer.MakeName (null, "f", "mg$cache", id), loc), null);
 796                         mg_cache.Define ();
 797                         parent.AddField (mg_cache);
 798
 799                         return expr;
 800                 }
 801
 802                 public override void Emit (EmitContext ec)
 803                 {
 804                         Label l_initialized = ec.DefineLabel ();
 805
 806                         if (mg_cache != null) {
 807                                 ec.Emit (OpCodes.Ldsfld, mg_cache.Spec);
 808                                 ec.Emit (OpCodes.Brtrue_S, l_initialized);
 809                         }
 810
 811                         base.Emit (ec);
 812
 813                         if (mg_cache != null) {
 814                                 ec.Emit (OpCodes.Stsfld, mg_cache.Spec);
 815                                 ec.MarkLabel (l_initialized);
 816                                 ec.Emit (OpCodes.Ldsfld, mg_cache.Spec);
 817                         }
 818                 }
 819         }
 820
 821         //
 822         // A delegate-creation-expression, invoked from the `New' class
 823         //
 824         public class NewDelegate : DelegateCreation
 825         {
 826                 public Arguments Arguments;
 827
 828                 //
 829                 // This constructor is invoked from the `New' expression
 830                 //
 831                 public NewDelegate (TypeSpec type, Arguments Arguments, Location loc)
 832                 {
 833                         this.type = type;
 834                         this.Arguments = Arguments;
 835                         this.loc  = loc;
 836                 }
 837
 838                 protected override Expression DoResolve (ResolveContext ec)
 839                 {
 840                         if (Arguments == null || Arguments.Count != 1) {
 841                                 ec.Report.Error (149, loc, "Method name expected");
 842                                 return null;
 843                         }
 844
 845                         Argument a = Arguments [0];
 846                         if (!a.ResolveMethodGroup (ec))
 847                                 return null;
 848
 849                         Expression e = a.Expr;
 850
 851                         AnonymousMethodExpression ame = e as AnonymousMethodExpression;
 852                         if (ame != null && ec.Module.Compiler.Settings.Version != LanguageVersion.ISO_1) {
 853                                 e = ame.Compatible (ec, type);
 854                                 if (e == null)
 855                                         return null;
 856
 857                                 return e.Resolve (ec);
 858                         }
 859
 860                         method_group = e as MethodGroupExpr;
 861                         if (method_group == null) {
 862                                 if (e.Type.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
 863                                         e = Convert.ImplicitConversionRequired (ec, e, type, loc);
 864                                 } else if (!e.Type.IsDelegate) {
 865                                         e.Error_UnexpectedKind (ec, ResolveFlags.MethodGroup | ResolveFlags.Type, loc);
 866                                         return null;
 867                                 }
 868
 869                                 //
 870                                 // An argument is not a method but another delegate
 871                                 //
 872                                 method_group = new MethodGroupExpr (Delegate.GetInvokeMethod (e.Type), e.Type, loc);
 873                                 method_group.InstanceExpression = e;
 874                         }
 875
 876                         return base.DoResolve (ec);
 877                 }
 878         }
 879
 880         //
 881         // Invocation converted to delegate Invoke call
 882         //
 883         class DelegateInvocation : ExpressionStatement
 884         {
 885                 readonly Expression InstanceExpr;
 886                 readonly bool conditionalAccessReceiver;
 887                 Arguments arguments;
 888                 MethodSpec method;
 889
 890                 public DelegateInvocation (Expression instance_expr, Arguments args, bool conditionalAccessReceiver, Location loc)
 891                 {
 892                         this.InstanceExpr = instance_expr;
 893                         this.arguments = args;
 894                         this.conditionalAccessReceiver = conditionalAccessReceiver;
 895                         this.loc = loc;
 896                 }
 897
 898                 public override bool ContainsEmitWithAwait ()
 899                 {
 900                         return InstanceExpr.ContainsEmitWithAwait () || (arguments != null && arguments.ContainsEmitWithAwait ());
 901                 }
 902
 903                 public override Expression CreateExpressionTree (ResolveContext ec)
 904                 {
 905                         Arguments args = Arguments.CreateForExpressionTree (ec, this.arguments,
 906                                 InstanceExpr.CreateExpressionTree (ec));
 907
 908                         return CreateExpressionFactoryCall (ec, "Invoke", args);
 909                 }
 910
 911                 public override void FlowAnalysis (FlowAnalysisContext fc)
 912                 {
 913                         InstanceExpr.FlowAnalysis (fc);
 914                         if (arguments != null)
 915                                 arguments.FlowAnalysis (fc);
 916                 }
 917
 918                 protected override Expression DoResolve (ResolveContext ec)
 919                 {
 920                         TypeSpec del_type = InstanceExpr.Type;
 921                         if (del_type == null)
 922                                 return null;
 923
 924                         //
 925                         // Do only core overload resolution the rest of the checks has been
 926                         // done on primary expression
 927                         //
 928                         method = Delegate.GetInvokeMethod (del_type);
 929                         var res = new OverloadResolver (new MemberSpec[] { method }, OverloadResolver.Restrictions.DelegateInvoke, loc);
 930                         var valid = res.ResolveMember<MethodSpec> (ec, ref arguments);
 931                         if (valid == null && !res.BestCandidateIsDynamic)
 932                                 return null;
 933
 934                         type = method.ReturnType;
 935                         if (conditionalAccessReceiver)
 936                                 type = LiftMemberType (ec, type);
 937
 938                         eclass = ExprClass.Value;
 939                         return this;
 940                 }
 941
 942                 public override void Emit (EmitContext ec)
 943                 {
 944                         if (conditionalAccessReceiver) {
 945                                 ec.ConditionalAccess = new ConditionalAccessContext (type, ec.DefineLabel ());
 946                         }
 947
 948                         //
 949                         // Invocation on delegates call the virtual Invoke member
 950                         // so we are always `instance' calls
 951                         //
 952                         var call = new CallEmitter ();
 953                         call.InstanceExpression = InstanceExpr;
 954                         call.Emit (ec, method, arguments, loc);
 955
 956                         if (conditionalAccessReceiver)
 957                                 ec.CloseConditionalAccess (type.IsNullableType && type !=  method.ReturnType ? type : null);
 958                 }
 959
 960                 public override void EmitStatement (EmitContext ec)
 961                 {
 962                         if (conditionalAccessReceiver) {
 963                                 ec.ConditionalAccess = new ConditionalAccessContext (type, ec.DefineLabel ()) {
 964                                         Statement = true
 965                                 };
 966                         }
 967
 968                         var call = new CallEmitter ();
 969                         call.InstanceExpression = InstanceExpr;
 970                         call.EmitStatement (ec, method, arguments, loc);
 971
 972                         if (conditionalAccessReceiver)
 973                                 ec.CloseConditionalAccess (null);
 974                 }
 975
 976                 public override System.Linq.Expressions.Expression MakeExpression (BuilderContext ctx)
 977                 {
 978                         return Invocation.MakeExpression (ctx, InstanceExpr, method, arguments);
 979                 }
 980         }
 981 }