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2010-03-05 Rodrigo Kumpera <rkumpera@novell.com>
[mcs.git] / mcs / generic.cs
blob2c468dd7ca7ff54f0db30b6c95200e0d9197404a
1 //
2 // generic.cs: Generics support
3 //
4 // Authors: Martin Baulig (martin@ximian.com)
5 // Miguel de Icaza (miguel@ximian.com)
6 // Marek Safar (marek.safar@gmail.com)
7 //
8 // Dual licensed under the terms of the MIT X11 or GNU GPL
9 //
10 // Copyright 2001, 2002, 2003 Ximian, Inc (http://www.ximian.com)
11 // Copyright 2004-2008 Novell, Inc
12 //
13 using System;
14 using System.Reflection;
15 using System.Reflection.Emit;
16 using System.Globalization;
17 using System.Collections.Generic;
18 using System.Text;
19
20 namespace Mono.CSharp {
21
22 /// <summary>
23 /// Abstract base class for type parameter constraints.
24 /// The type parameter can come from a generic type definition or from reflection.
25 /// </summary>
26 public abstract class GenericConstraints {
27 public abstract GenericParameterAttributes Attributes {
28 get;
29 }
30
31 public bool HasConstructorConstraint {
32 get { return (Attributes & GenericParameterAttributes.DefaultConstructorConstraint) != 0; }
33 }
34
35 public bool HasReferenceTypeConstraint {
36 get { return (Attributes & GenericParameterAttributes.ReferenceTypeConstraint) != 0; }
37 }
38
39 public bool HasValueTypeConstraint {
40 get { return (Attributes & GenericParameterAttributes.NotNullableValueTypeConstraint) != 0; }
41 }
42
43 public virtual bool HasClassConstraint {
44 get { return ClassConstraint != null; }
45 }
46
47 public abstract Type ClassConstraint {
48 get;
49 }
50
51 public abstract Type[] InterfaceConstraints {
52 get;
53 }
54
55 public abstract Type EffectiveBaseClass {
56 get;
57 }
58
59 // <summary>
60 // Returns whether the type parameter is "known to be a reference type".
61 // </summary>
62 public virtual bool IsReferenceType {
63 get {
64 if (HasReferenceTypeConstraint)
65 return true;
66 if (HasValueTypeConstraint)
67 return false;
68
69 if (ClassConstraint != null) {
70 if (ClassConstraint.IsValueType)
71 return false;
72
73 if (ClassConstraint != TypeManager.object_type)
74 return true;
75 }
76
77 foreach (Type t in InterfaceConstraints) {
78 if (!t.IsGenericParameter)
79 continue;
80
81 GenericConstraints gc = TypeManager.GetTypeParameterConstraints (t);
82 if ((gc != null) && gc.IsReferenceType)
83 return true;
84 }
85
86 return false;
87 }
88 }
89
90 // <summary>
91 // Returns whether the type parameter is "known to be a value type".
92 // </summary>
93 public virtual bool IsValueType {
94 get {
95 if (HasValueTypeConstraint)
96 return true;
97 if (HasReferenceTypeConstraint)
98 return false;
99
100 if (ClassConstraint != null) {
101 if (!TypeManager.IsValueType (ClassConstraint))
102 return false;
103
104 if (ClassConstraint != TypeManager.value_type)
105 return true;
106 }
107
108 foreach (Type t in InterfaceConstraints) {
109 if (!t.IsGenericParameter)
110 continue;
111
112 GenericConstraints gc = TypeManager.GetTypeParameterConstraints (t);
113 if ((gc != null) && gc.IsValueType)
114 return true;
115 }
116
117 return false;
118 }
119 }
120 }
121
122 public class ReflectionConstraints : GenericConstraints
123 {
124 GenericParameterAttributes attrs;
125 Type base_type;
126 Type class_constraint;
127 Type[] iface_constraints;
128
129 public static GenericConstraints GetConstraints (Type t)
130 {
131 Type[] constraints = t.GetGenericParameterConstraints ();
132 GenericParameterAttributes attrs = t.GenericParameterAttributes;
133 if (constraints.Length == 0 && attrs == GenericParameterAttributes.None)
134 return null;
135 return new ReflectionConstraints (t.Name, constraints, attrs);
136 }
137
138 private ReflectionConstraints (string name, Type[] constraints, GenericParameterAttributes attrs)
139 {
140 this.attrs = attrs;
141
142 int interface_constraints_pos = 0;
143 if ((attrs & GenericParameterAttributes.NotNullableValueTypeConstraint) != 0) {
144 base_type = TypeManager.value_type;
145 interface_constraints_pos = 1;
146 } else if ((attrs & GenericParameterAttributes.ReferenceTypeConstraint) != 0) {
147 if (constraints.Length > 0 && constraints[0].IsClass) {
148 class_constraint = base_type = constraints[0];
149 interface_constraints_pos = 1;
150 } else {
151 base_type = TypeManager.object_type;
152 }
153 } else {
154 base_type = TypeManager.object_type;
155 }
156
157 if (constraints.Length > interface_constraints_pos) {
158 if (interface_constraints_pos == 0) {
159 iface_constraints = constraints;
160 } else {
161 iface_constraints = new Type[constraints.Length - interface_constraints_pos];
162 Array.Copy (constraints, interface_constraints_pos, iface_constraints, 0, iface_constraints.Length);
163 }
164 } else {
165 iface_constraints = Type.EmptyTypes;
166 }
167 }
168
169 public override GenericParameterAttributes Attributes
170 {
171 get { return attrs; }
172 }
173
174 public override Type ClassConstraint
175 {
176 get { return class_constraint; }
177 }
178
179 public override Type EffectiveBaseClass
180 {
181 get { return base_type; }
182 }
183
184 public override Type[] InterfaceConstraints
185 {
186 get { return iface_constraints; }
187 }
188 }
189
190 public enum Variance
191 {
192 //
193 // Don't add or modify internal values, they are used as -/+ calculation signs
194 //
195 None = 0,
196 Covariant = 1,
197 Contravariant = -1
198 }
199
200 [Flags]
201 public enum SpecialConstraint
202 {
203 None = 0,
204 Constructor = 1 << 2,
205 Class = 1 << 3,
206 Struct = 1 << 4
207 }
208
209 public class SpecialContraintExpr : FullNamedExpression
210 {
211 public SpecialContraintExpr (SpecialConstraint constraint, Location loc)
212 {
213 this.loc = loc;
214 this.Constraint = constraint;
215 }
216
217 public SpecialConstraint Constraint { get; private set; }
218
219 protected override Expression DoResolve (ResolveContext rc)
220 {
221 throw new NotImplementedException ();
222 }
223 }
224
225 //
226 // A set of parsed constraints for a type parameter
227 //
228 public class Constraints : GenericConstraints
229 {
230 SimpleMemberName tparam;
231 List<FullNamedExpression> constraints;
232 Location loc;
233 GenericParameterAttributes attrs;
234 TypeExpr class_constraint;
235 List<TypeExpr> iface_constraints;
236 List<TypeExpr> type_param_constraints;
237 int num_constraints;
238 Type class_constraint_type;
239 Type[] iface_constraint_types;
240 Type effective_base_type;
241 bool resolved;
242 bool resolved_types;
243
244 //
245 // name is the identifier, constraints is an arraylist of
246 // Expressions (with types) or `true' for the constructor constraint.
247 //
248 public Constraints (SimpleMemberName tparam, List<FullNamedExpression> constraints, Location loc)
249 {
250 this.tparam = tparam;
251 this.constraints = constraints;
252 this.loc = loc;
253 }
254
255 #region Properties
256
257 public SimpleMemberName TypeParameter {
258 get {
259 return tparam;
260 }
261 }
262
263 #endregion
264
265 public Constraints Clone ()
266 {
267 return new Constraints (tparam, constraints, loc);
268 }
269
270 /// <summary>
271 /// Resolve the constraints - but only resolve things into Expression's, not
272 /// into actual types.
273 /// </summary>
274 public bool Resolve (MemberCore ec, TypeParameter tp, Report Report)
275 {
276 if (resolved)
277 return true;
278
279 if (ec == null)
280 return false;
281
282 iface_constraints = new List<TypeExpr> (2); // TODO: Too expensive allocation
283 type_param_constraints = new List<TypeExpr> ();
284
285 foreach (var obj in constraints) {
286
287 if (obj is SpecialContraintExpr) {
288 SpecialConstraint sc = ((SpecialContraintExpr) obj).Constraint;
289
290 if (sc == SpecialConstraint.Constructor) {
291 if (!HasValueTypeConstraint) {
292 attrs |= GenericParameterAttributes.DefaultConstructorConstraint;
293 continue;
294 }
295 }
296
297 if (sc == SpecialConstraint.Class)
298 attrs |= GenericParameterAttributes.ReferenceTypeConstraint;
299 else
300 attrs |= GenericParameterAttributes.NotNullableValueTypeConstraint;
301 continue;
302 }
303
304 int errors = Report.Errors;
305 FullNamedExpression fn = obj.ResolveAsTypeStep (ec, false);
306
307 if (fn == null) {
308 if (errors != Report.Errors)
309 return false;
310
311 NamespaceEntry.Error_NamespaceNotFound (loc, obj.GetSignatureForError (), Report);
312 return false;
313 }
314
315 TypeExpr expr;
316 GenericTypeExpr cexpr = fn as GenericTypeExpr;
317 if (cexpr != null) {
318 expr = cexpr.ResolveAsBaseTerminal (ec, false);
319 if (expr != null && cexpr.HasDynamicArguments ()) {
320 Report.Error (1968, cexpr.Location,
321 "A constraint cannot be the dynamic type `{0}'",
322 cexpr.GetSignatureForError ());
323 expr = null;
324 }
325 } else
326 expr = ((Expression) obj).ResolveAsTypeTerminal (ec, false);
327
328 if ((expr == null) || (expr.Type == null))
329 return false;
330
331 if (TypeManager.IsGenericParameter (expr.Type))
332 type_param_constraints.Add (expr);
333 else if (expr.IsInterface)
334 iface_constraints.Add (expr);
335 else if (class_constraint != null || iface_constraints.Count != 0) {
336 Report.Error (406, loc,
337 "The class type constraint `{0}' must be listed before any other constraints. Consider moving type constraint to the beginning of the constraint list",
338 expr.GetSignatureForError ());
339 return false;
340 } else if (HasReferenceTypeConstraint || HasValueTypeConstraint) {
341 Report.Error (450, loc, "`{0}': cannot specify both " +
342 "a constraint class and the `class' " +
343 "or `struct' constraint", expr.GetSignatureForError ());
344 return false;
345 } else
346 class_constraint = expr;
347
348
349 //
350 // Checks whether each generic method parameter constraint type
351 // is valid with respect to T
352 //
353 if (tp != null && tp.Type.DeclaringMethod != null) {
354 TypeManager.CheckTypeVariance (expr.Type, Variance.Contravariant, ec as MemberCore);
355 }
356
357 if (!ec.IsAccessibleAs (fn.Type)) {
358 Report.SymbolRelatedToPreviousError (fn.Type);
359 Report.Error (703, loc,
360 "Inconsistent accessibility: constraint type `{0}' is less accessible than `{1}'",
361 fn.GetSignatureForError (), ec.GetSignatureForError ());
362 }
363
364 num_constraints++;
365 }
366
367 var list = new List<Type> ();
368 foreach (TypeExpr iface_constraint in iface_constraints) {
369 foreach (Type type in list) {
370 if (!type.Equals (iface_constraint.Type))
371 continue;
372
373 Report.Error (405, loc,
374 "Duplicate constraint `{0}' for type " +
375 "parameter `{1}'.", iface_constraint.GetSignatureForError (),
376 tparam.Value);
377 return false;
378 }
379
380 list.Add (iface_constraint.Type);
381 }
382
383 foreach (TypeExpr expr in type_param_constraints) {
384 foreach (Type type in list) {
385 if (!type.Equals (expr.Type))
386 continue;
387
388 Report.Error (405, loc,
389 "Duplicate constraint `{0}' for type " +
390 "parameter `{1}'.", expr.GetSignatureForError (), tparam.Value);
391 return false;
392 }
393
394 list.Add (expr.Type);
395 }
396
397 iface_constraint_types = new Type [list.Count];
398 list.CopyTo (iface_constraint_types, 0);
399
400 if (class_constraint != null) {
401 class_constraint_type = class_constraint.Type;
402 if (class_constraint_type == null)
403 return false;
404
405 if (class_constraint_type.IsSealed) {
406 if (class_constraint_type.IsAbstract)
407 {
408 Report.Error (717, loc, "`{0}' is not a valid constraint. Static classes cannot be used as constraints",
409 TypeManager.CSharpName (class_constraint_type));
410 }
411 else
412 {
413 Report.Error (701, loc, "`{0}' is not a valid constraint. A constraint must be an interface, " +
414 "a non-sealed class or a type parameter", TypeManager.CSharpName(class_constraint_type));
415 }
416 return false;
417 }
418
419 if ((class_constraint_type == TypeManager.array_type) ||
420 (class_constraint_type == TypeManager.delegate_type) ||
421 (class_constraint_type == TypeManager.enum_type) ||
422 (class_constraint_type == TypeManager.value_type) ||
423 (class_constraint_type == TypeManager.object_type) ||
424 class_constraint_type == TypeManager.multicast_delegate_type) {
425 Report.Error (702, loc,
426 "A constraint cannot be special class `{0}'",
427 TypeManager.CSharpName (class_constraint_type));
428 return false;
429 }
430
431 if (TypeManager.IsDynamicType (class_constraint_type)) {
432 Report.Error (1967, loc, "A constraint cannot be the dynamic type");
433 return false;
434 }
435 }
436
437 if (class_constraint_type != null)
438 effective_base_type = class_constraint_type;
439 else if (HasValueTypeConstraint)
440 effective_base_type = TypeManager.value_type;
441 else
442 effective_base_type = TypeManager.object_type;
443
444 if ((attrs & GenericParameterAttributes.NotNullableValueTypeConstraint) != 0)
445 attrs |= GenericParameterAttributes.DefaultConstructorConstraint;
446
447 resolved = true;
448 return true;
449 }
450
451 bool CheckTypeParameterConstraints (Type tparam, ref TypeExpr prevConstraint, List<Type> seen, Report Report)
452 {
453 seen.Add (tparam);
454
455 Constraints constraints = TypeManager.LookupTypeParameter (tparam).Constraints;
456 if (constraints == null)
457 return true;
458
459 if (constraints.HasValueTypeConstraint) {
460 Report.Error (456, loc,
461 "Type parameter `{0}' has the `struct' constraint, so it cannot be used as a constraint for `{1}'",
462 tparam.Name, this.tparam.Value);
463 return false;
464 }
465
466 //
467 // Checks whether there are no conflicts between type parameter constraints
468 //
469 // class Foo<T, U>
470 // where T : A
471 // where U : A, B // A and B are not convertible
472 //
473 if (constraints.HasClassConstraint) {
474 if (prevConstraint != null) {
475 Type t2 = constraints.ClassConstraint;
476 TypeExpr e2 = constraints.class_constraint;
477
478 if (!Convert.ImplicitReferenceConversionExists (prevConstraint, t2) &&
479 !Convert.ImplicitReferenceConversionExists (e2, prevConstraint.Type)) {
480 Report.Error (455, loc,
481 "Type parameter `{0}' inherits conflicting constraints `{1}' and `{2}'",
482 this.tparam.Value, TypeManager.CSharpName (prevConstraint.Type), TypeManager.CSharpName (t2));
483 return false;
484 }
485 }
486
487 prevConstraint = constraints.class_constraint;
488 }
489
490 if (constraints.type_param_constraints == null)
491 return true;
492
493 foreach (TypeExpr expr in constraints.type_param_constraints) {
494 if (seen.Contains (expr.Type)) {
495 Report.Error (454, loc, "Circular constraint " +
496 "dependency involving `{0}' and `{1}'",
497 tparam.Name, expr.GetSignatureForError ());
498 return false;
499 }
500
501 if (!CheckTypeParameterConstraints (expr.Type, ref prevConstraint, seen, Report))
502 return false;
503 }
504
505 return true;
506 }
507
508 /// <summary>
509 /// Resolve the constraints into actual types.
510 /// </summary>
511 public bool ResolveTypes (IMemberContext ec, Report r)
512 {
513 if (resolved_types)
514 return true;
515
516 resolved_types = true;
517
518 foreach (object obj in constraints) {
519 GenericTypeExpr cexpr = obj as GenericTypeExpr;
520 if (cexpr == null)
521 continue;
522
523 if (!cexpr.CheckConstraints (ec))
524 return false;
525 }
526
527 if (type_param_constraints.Count != 0) {
528 var seen = new List<Type> ();
529 TypeExpr prev_constraint = class_constraint;
530 foreach (TypeExpr expr in type_param_constraints) {
531 if (!CheckTypeParameterConstraints (expr.Type, ref prev_constraint, seen, r))
532 return false;
533 seen.Clear ();
534 }
535 }
536
537 for (int i = 0; i < iface_constraints.Count; ++i) {
538 TypeExpr iface_constraint = (TypeExpr) iface_constraints [i];
539 iface_constraint = iface_constraint.ResolveAsTypeTerminal (ec, false);
540 if (iface_constraint == null)
541 return false;
542 iface_constraints [i] = iface_constraint;
543 }
544
545 if (class_constraint != null) {
546 class_constraint = class_constraint.ResolveAsTypeTerminal (ec, false);
547 if (class_constraint == null)
548 return false;
549 }
550
551 return true;
552 }
553
554 public override GenericParameterAttributes Attributes {
555 get { return attrs; }
556 }
557
558 public override bool HasClassConstraint {
559 get { return class_constraint != null; }
560 }
561
562 public override Type ClassConstraint {
563 get { return class_constraint_type; }
564 }
565
566 public override Type[] InterfaceConstraints {
567 get { return iface_constraint_types; }
568 }
569
570 public override Type EffectiveBaseClass {
571 get { return effective_base_type; }
572 }
573
574 public bool IsSubclassOf (Type t)
575 {
576 if ((class_constraint_type != null) &&
577 class_constraint_type.IsSubclassOf (t))
578 return true;
579
580 if (iface_constraint_types == null)
581 return false;
582
583 foreach (Type iface in iface_constraint_types) {
584 if (TypeManager.IsSubclassOf (iface, t))
585 return true;
586 }
587
588 return false;
589 }
590
591 public Location Location {
592 get {
593 return loc;
594 }
595 }
596
597 /// <summary>
598 /// This is used when we're implementing a generic interface method.
599 /// Each method type parameter in implementing method must have the same
600 /// constraints than the corresponding type parameter in the interface
601 /// method. To do that, we're called on each of the implementing method's
602 /// type parameters.
603 /// </summary>
604 public bool AreEqual (GenericConstraints gc)
605 {
606 if (gc.Attributes != attrs)
607 return false;
608
609 if (HasClassConstraint != gc.HasClassConstraint)
610 return false;
611 if (HasClassConstraint && !TypeManager.IsEqual (gc.ClassConstraint, ClassConstraint))
612 return false;
613
614 int gc_icount = gc.InterfaceConstraints != null ?
615 gc.InterfaceConstraints.Length : 0;
616 int icount = InterfaceConstraints != null ?
617 InterfaceConstraints.Length : 0;
618
619 if (gc_icount != icount)
620 return false;
621
622 for (int i = 0; i < gc.InterfaceConstraints.Length; ++i) {
623 Type iface = gc.InterfaceConstraints [i];
624 if (iface.IsGenericType)
625 iface = iface.GetGenericTypeDefinition ();
626
627 bool ok = false;
628 for (int ii = 0; ii < InterfaceConstraints.Length; ii++) {
629 Type check = InterfaceConstraints [ii];
630 if (check.IsGenericType)
631 check = check.GetGenericTypeDefinition ();
632
633 if (TypeManager.IsEqual (iface, check)) {
634 ok = true;
635 break;
636 }
637 }
638
639 if (!ok)
640 return false;
641 }
642
643 return true;
644 }
645
646 public void VerifyClsCompliance (Report r)
647 {
648 if (class_constraint_type != null && !AttributeTester.IsClsCompliant (class_constraint_type))
649 Warning_ConstrainIsNotClsCompliant (class_constraint_type, class_constraint.Location, r);
650
651 if (iface_constraint_types != null) {
652 for (int i = 0; i < iface_constraint_types.Length; ++i) {
653 if (!AttributeTester.IsClsCompliant (iface_constraint_types [i]))
654 Warning_ConstrainIsNotClsCompliant (iface_constraint_types [i],
655 ((TypeExpr)iface_constraints [i]).Location, r);
656 }
657 }
658 }
659
660 void Warning_ConstrainIsNotClsCompliant (Type t, Location loc, Report Report)
661 {
662 Report.SymbolRelatedToPreviousError (t);
663 Report.Warning (3024, 1, loc, "Constraint type `{0}' is not CLS-compliant",
664 TypeManager.CSharpName (t));
665 }
666 }
667
668 /// <summary>
669 /// A type parameter from a generic type definition.
670 /// </summary>
671 public class TypeParameter : MemberCore, IMemberContainer
672 {
673 static readonly string[] attribute_target = new string [] { "type parameter" };
674
675 DeclSpace decl;
676 GenericConstraints gc;
677 Constraints constraints;
678 GenericTypeParameterBuilder type;
679 MemberCache member_cache;
680 Variance variance;
681
682 public TypeParameter (DeclSpace parent, DeclSpace decl, string name,
683 Constraints constraints, Attributes attrs, Variance variance, Location loc)
684 : base (parent, new MemberName (name, loc), attrs)
685 {
686 this.decl = decl;
687 this.constraints = constraints;
688 this.variance = variance;
689 }
690
691 public GenericConstraints GenericConstraints {
692 get { return gc != null ? gc : constraints; }
693 }
694
695 public Constraints Constraints {
696 get { return constraints; }
697 }
698
699 public DeclSpace DeclSpace {
700 get { return decl; }
701 }
702
703 public Variance Variance {
704 get { return variance; }
705 }
706
707 public Type Type {
708 get { return type; }
709 }
710
711 /// <summary>
712 /// This is the first method which is called during the resolving
713 /// process; we're called immediately after creating the type parameters
714 /// with SRE (by calling `DefineGenericParameters()' on the TypeBuilder /
715 /// MethodBuilder).
716 ///
717 /// We're either called from TypeContainer.DefineType() or from
718 /// GenericMethod.Define() (called from Method.Define()).
719 /// </summary>
720 public void Define (GenericTypeParameterBuilder type)
721 {
722 if (this.type != null)
723 throw new InvalidOperationException ();
724
725 this.type = type;
726 TypeManager.AddTypeParameter (type, this);
727 }
728
729 public void ErrorInvalidVariance (IMemberContext mc, Variance expected)
730 {
731 // TODO: Report.SymbolRelatedToPreviousError (mc);
732 string input_variance = Variance == Variance.Contravariant ? "contravariant" : "covariant";
733 string gtype_variance;
734 switch (expected) {
735 case Variance.Contravariant: gtype_variance = "contravariantly"; break;
736 case Variance.Covariant: gtype_variance = "covariantly"; break;
737 default: gtype_variance = "invariantly"; break;
738 }
739
740 Delegate d = mc as Delegate;
741 string parameters = d != null ? d.Parameters.GetSignatureForError () : "";
742
743 Report.Error (1961, Location,
744 "The {2} type parameter `{0}' must be {3} valid on `{1}{4}'",
745 GetSignatureForError (), mc.GetSignatureForError (), input_variance, gtype_variance, parameters);
746 }
747
748 /// <summary>
749 /// This is the second method which is called during the resolving
750 /// process - in case of class type parameters, we're called from
751 /// TypeContainer.ResolveType() - after it resolved the class'es
752 /// base class and interfaces. For method type parameters, we're
753 /// called immediately after Define().
754 ///
755 /// We're just resolving the constraints into expressions here, we
756 /// don't resolve them into actual types.
757 ///
758 /// Note that in the special case of partial generic classes, we may be
759 /// called _before_ Define() and we may also be called multiple types.
760 /// </summary>
761 public bool Resolve (DeclSpace ds)
762 {
763 if (constraints != null) {
764 if (!constraints.Resolve (ds, this, Report)) {
765 constraints = null;
766 return false;
767 }
768 }
769
770 return true;
771 }
772
773 /// <summary>
774 /// This is the third method which is called during the resolving
775 /// process. We're called immediately after calling DefineConstraints()
776 /// on all of the current class'es type parameters.
777 ///
778 /// Our job is to resolve the constraints to actual types.
779 ///
780 /// Note that we may have circular dependencies on type parameters - this
781 /// is why Resolve() and ResolveType() are separate.
782 /// </summary>
783 public bool ResolveType (IMemberContext ec)
784 {
785 if (constraints != null) {
786 if (!constraints.ResolveTypes (ec, Report)) {
787 constraints = null;
788 return false;
789 }
790 }
791
792 return true;
793 }
794
795 /// <summary>
796 /// This is the fourth and last method which is called during the resolving
797 /// process. We're called after everything is fully resolved and actually
798 /// register the constraints with SRE and the TypeManager.
799 /// </summary>
800 public bool DefineType (IMemberContext ec)
801 {
802 return DefineType (ec, null, null, false);
803 }
804
805 /// <summary>
806 /// This is the fith and last method which is called during the resolving
807 /// process. We're called after everything is fully resolved and actually
808 /// register the constraints with SRE and the TypeManager.
809 ///
810 /// The `builder', `implementing' and `is_override' arguments are only
811 /// applicable to method type parameters.
812 /// </summary>
813 public bool DefineType (IMemberContext ec, MethodBuilder builder,
814 MethodInfo implementing, bool is_override)
815 {
816 if (!ResolveType (ec))
817 return false;
818
819 if (implementing != null) {
820 if (is_override && (constraints != null)) {
821 Report.Error (460, Location,
822 "`{0}': Cannot specify constraints for overrides or explicit interface implementation methods",
823 TypeManager.CSharpSignature (builder));
824 return false;
825 }
826
827 MethodBase mb = TypeManager.DropGenericMethodArguments (implementing);
828
829 int pos = type.GenericParameterPosition;
830 Type mparam = mb.GetGenericArguments () [pos];
831 GenericConstraints temp_gc = ReflectionConstraints.GetConstraints (mparam);
832
833 if (temp_gc != null)
834 gc = new InflatedConstraints (temp_gc, implementing.DeclaringType);
835 else if (constraints != null)
836 gc = new InflatedConstraints (constraints, implementing.DeclaringType);
837
838 bool ok = true;
839 if (constraints != null) {
840 if (temp_gc == null)
841 ok = false;
842 else if (!constraints.AreEqual (gc))
843 ok = false;
844 } else {
845 if (!is_override && (temp_gc != null))
846 ok = false;
847 }
848
849 if (!ok) {
850 Report.SymbolRelatedToPreviousError (implementing);
851
852 Report.Error (
853 425, Location, "The constraints for type " +
854 "parameter `{0}' of method `{1}' must match " +
855 "the constraints for type parameter `{2}' " +
856 "of interface method `{3}'. Consider using " +
857 "an explicit interface implementation instead",
858 Name, TypeManager.CSharpSignature (builder),
859 TypeManager.CSharpName (mparam), TypeManager.CSharpSignature (mb));
860 return false;
861 }
862 } else if (DeclSpace is CompilerGeneratedClass) {
863 TypeParameter[] tparams = DeclSpace.TypeParameters;
864 Type[] types = new Type [tparams.Length];
865 for (int i = 0; i < tparams.Length; i++)
866 types [i] = tparams [i].Type;
867
868 if (constraints != null)
869 gc = new InflatedConstraints (constraints, types);
870 } else {
871 gc = (GenericConstraints) constraints;
872 }
873
874 SetConstraints (type);
875 return true;
876 }
877
878 public static TypeParameter FindTypeParameter (TypeParameter[] tparams, string name)
879 {
880 foreach (var tp in tparams) {
881 if (tp.Name == name)
882 return tp;
883 }
884
885 return null;
886 }
887
888 public void SetConstraints (GenericTypeParameterBuilder type)
889 {
890 GenericParameterAttributes attr = GenericParameterAttributes.None;
891 if (variance == Variance.Contravariant)
892 attr |= GenericParameterAttributes.Contravariant;
893 else if (variance == Variance.Covariant)
894 attr |= GenericParameterAttributes.Covariant;
895
896 if (gc != null) {
897 if (gc.HasClassConstraint || gc.HasValueTypeConstraint)
898 type.SetBaseTypeConstraint (gc.EffectiveBaseClass);
899
900 attr |= gc.Attributes;
901 type.SetInterfaceConstraints (gc.InterfaceConstraints);
902 TypeManager.RegisterBuilder (type, gc.InterfaceConstraints);
903 }
904
905 type.SetGenericParameterAttributes (attr);
906 }
907
908 /// <summary>
909 /// This is called for each part of a partial generic type definition.
910 ///
911 /// If `new_constraints' is not null and we don't already have constraints,
912 /// they become our constraints. If we already have constraints, we must
913 /// check that they're the same.
914 /// con
915 /// </summary>
916 public bool UpdateConstraints (MemberCore ec, Constraints new_constraints)
917 {
918 if (type == null)
919 throw new InvalidOperationException ();
920
921 if (new_constraints == null)
922 return true;
923
924 if (!new_constraints.Resolve (ec, this, Report))
925 return false;
926 if (!new_constraints.ResolveTypes (ec, Report))
927 return false;
928
929 if (constraints != null)
930 return constraints.AreEqual (new_constraints);
931
932 constraints = new_constraints;
933 return true;
934 }
935
936 public override void Emit ()
937 {
938 if (OptAttributes != null)
939 OptAttributes.Emit ();
940
941 base.Emit ();
942 }
943
944 public override string DocCommentHeader {
945 get {
946 throw new InvalidOperationException (
947 "Unexpected attempt to get doc comment from " + this.GetType () + ".");
948 }
949 }
950
951 //
952 // MemberContainer
953 //
954
955 public override bool Define ()
956 {
957 return true;
958 }
959
960 public override void ApplyAttributeBuilder (Attribute a, CustomAttributeBuilder cb, PredefinedAttributes pa)
961 {
962 type.SetCustomAttribute (cb);
963 }
964
965 public override AttributeTargets AttributeTargets {
966 get {
967 return AttributeTargets.GenericParameter;
968 }
969 }
970
971 public override string[] ValidAttributeTargets {
972 get {
973 return attribute_target;
974 }
975 }
976
977 //
978 // IMemberContainer
979 //
980
981 string IMemberContainer.Name {
982 get { return Name; }
983 }
984
985 MemberCache IMemberContainer.BaseCache {
986 get {
987 if (gc == null)
988 return null;
989
990 if (gc.EffectiveBaseClass.BaseType == null)
991 return null;
992
993 return TypeManager.LookupMemberCache (gc.EffectiveBaseClass.BaseType);
994 }
995 }
996
997 bool IMemberContainer.IsInterface {
998 get { return false; }
999 }
1000
1001 MemberList IMemberContainer.GetMembers (MemberTypes mt, BindingFlags bf)
1002 {
1003 throw new NotSupportedException ();
1004 }
1005
1006 public MemberCache MemberCache {
1007 get {
1008 if (member_cache != null)
1009 return member_cache;
1010
1011 if (gc == null)
1012 return null;
1013
1014 Type[] ifaces = TypeManager.ExpandInterfaces (gc.InterfaceConstraints);
1015 member_cache = new MemberCache (this, gc.EffectiveBaseClass, ifaces);
1016
1017 return member_cache;
1018 }
1019 }
1020
1021 public MemberList FindMembers (MemberTypes mt, BindingFlags bf,
1022 MemberFilter filter, object criteria)
1023 {
1024 if (gc == null)
1025 return MemberList.Empty;
1026
1027 var members = new List<MemberInfo> ();
1028
1029 if (gc.HasClassConstraint) {
1030 MemberList list = TypeManager.FindMembers (
1031 gc.ClassConstraint, mt, bf, filter, criteria);
1032
1033 members.AddRange (list);
1034 }
1035
1036 Type[] ifaces = TypeManager.ExpandInterfaces (gc.InterfaceConstraints);
1037 foreach (Type t in ifaces) {
1038 MemberList list = TypeManager.FindMembers (
1039 t, mt, bf, filter, criteria);
1040
1041 members.AddRange (list);
1042 }
1043
1044 return new MemberList (members);
1045 }
1046
1047 public bool IsSubclassOf (Type t)
1048 {
1049 if (type.Equals (t))
1050 return true;
1051
1052 if (constraints != null)
1053 return constraints.IsSubclassOf (t);
1054
1055 return false;
1056 }
1057
1058 public void InflateConstraints (Type declaring)
1059 {
1060 if (constraints != null)
1061 gc = new InflatedConstraints (constraints, declaring);
1062 }
1063
1064 public override bool IsClsComplianceRequired ()
1065 {
1066 return false;
1067 }
1068
1069 protected class InflatedConstraints : GenericConstraints
1070 {
1071 GenericConstraints gc;
1072 Type base_type;
1073 Type class_constraint;
1074 Type[] iface_constraints;
1075 Type[] dargs;
1076
1077 public InflatedConstraints (GenericConstraints gc, Type declaring)
1078 : this (gc, TypeManager.GetTypeArguments (declaring))
1079 { }
1080
1081 public InflatedConstraints (GenericConstraints gc, Type[] dargs)
1082 {
1083 this.gc = gc;
1084 this.dargs = dargs;
1085
1086 var list = new List<Type> ();
1087 if (gc.HasClassConstraint)
1088 list.Add (inflate (gc.ClassConstraint));
1089 foreach (Type iface in gc.InterfaceConstraints)
1090 list.Add (inflate (iface));
1091
1092 bool has_class_constr = false;
1093 if (list.Count > 0) {
1094 Type first = (Type) list [0];
1095 has_class_constr = !first.IsGenericParameter && !first.IsInterface;
1096 }
1097
1098 if ((list.Count > 0) && has_class_constr) {
1099 class_constraint = (Type) list [0];
1100 iface_constraints = new Type [list.Count - 1];
1101 list.CopyTo (1, iface_constraints, 0, list.Count - 1);
1102 } else {
1103 iface_constraints = new Type [list.Count];
1104 list.CopyTo (iface_constraints, 0);
1105 }
1106
1107 if (HasValueTypeConstraint)
1108 base_type = TypeManager.value_type;
1109 else if (class_constraint != null)
1110 base_type = class_constraint;
1111 else
1112 base_type = TypeManager.object_type;
1113 }
1114
1115 Type inflate (Type t)
1116 {
1117 if (t == null)
1118 return null;
1119 if (t.IsGenericParameter)
1120 return t.GenericParameterPosition < dargs.Length ? dargs [t.GenericParameterPosition] : t;
1121 if (t.IsGenericType) {
1122 Type[] args = t.GetGenericArguments ();
1123 Type[] inflated = new Type [args.Length];
1124
1125 for (int i = 0; i < args.Length; i++)
1126 inflated [i] = inflate (args [i]);
1127
1128 t = t.GetGenericTypeDefinition ();
1129 t = t.MakeGenericType (inflated);
1130 }
1131
1132 return t;
1133 }
1134
1135 public override GenericParameterAttributes Attributes {
1136 get { return gc.Attributes; }
1137 }
1138
1139 public override Type ClassConstraint {
1140 get { return class_constraint; }
1141 }
1142
1143 public override Type EffectiveBaseClass {
1144 get { return base_type; }
1145 }
1146
1147 public override Type[] InterfaceConstraints {
1148 get { return iface_constraints; }
1149 }
1150 }
1151 }
1152
1153 /// <summary>
1154 /// A TypeExpr which already resolved to a type parameter.
1155 /// </summary>
1156 public class TypeParameterExpr : TypeExpr {
1157
1158 public TypeParameterExpr (TypeParameter type_parameter, Location loc)
1159 {
1160 this.type = type_parameter.Type;
1161 this.eclass = ExprClass.TypeParameter;
1162 this.loc = loc;
1163 }
1164
1165 protected override TypeExpr DoResolveAsTypeStep (IMemberContext ec)
1166 {
1167 throw new NotSupportedException ();
1168 }
1169
1170 public override FullNamedExpression ResolveAsTypeStep (IMemberContext ec, bool silent)
1171 {
1172 return this;
1173 }
1174
1175 public override bool IsInterface {
1176 get { return false; }
1177 }
1178
1179 public override bool CheckAccessLevel (IMemberContext ds)
1180 {
1181 return true;
1182 }
1183 }
1184
1185 //
1186 // Tracks the type arguments when instantiating a generic type. It's used
1187 // by both type arguments and type parameters
1188 //
1189 public class TypeArguments {
1190 List<FullNamedExpression> args;
1191 Type[] atypes;
1192
1193 public TypeArguments ()
1194 {
1195 args = new List<FullNamedExpression> ();
1196 }
1197
1198 public TypeArguments (params FullNamedExpression[] types)
1199 {
1200 this.args = new List<FullNamedExpression> (types);
1201 }
1202
1203 public void Add (FullNamedExpression type)
1204 {
1205 args.Add (type);
1206 }
1207
1208 public void Add (TypeArguments new_args)
1209 {
1210 args.AddRange (new_args.args);
1211 }
1212
1213 // TODO: Kill this monster
1214 public TypeParameterName[] GetDeclarations ()
1215 {
1216 return args.ConvertAll (i => (TypeParameterName) i).ToArray ();
1217 }
1218
1219 /// <summary>
1220 /// We may only be used after Resolve() is called and return the fully
1221 /// resolved types.
1222 /// </summary>
1223 public Type[] Arguments {
1224 get {
1225 return atypes;
1226 }
1227 }
1228
1229 public int Count {
1230 get {
1231 return args.Count;
1232 }
1233 }
1234
1235 public string GetSignatureForError()
1236 {
1237 StringBuilder sb = new StringBuilder();
1238 for (int i = 0; i < Count; ++i)
1239 {
1240 Expression expr = (Expression)args [i];
1241 sb.Append(expr.GetSignatureForError());
1242 if (i + 1 < Count)
1243 sb.Append(',');
1244 }
1245 return sb.ToString();
1246 }
1247
1248 /// <summary>
1249 /// Resolve the type arguments.
1250 /// </summary>
1251 public bool Resolve (IMemberContext ec)
1252 {
1253 if (atypes != null)
1254 return atypes.Length != 0;
1255
1256 int count = args.Count;
1257 bool ok = true;
1258
1259 atypes = new Type [count];
1260
1261 for (int i = 0; i < count; i++){
1262 TypeExpr te = ((FullNamedExpression) args[i]).ResolveAsTypeTerminal (ec, false);
1263 if (te == null) {
1264 ok = false;
1265 continue;
1266 }
1267
1268 atypes[i] = te.Type;
1269
1270 if (te.Type.IsSealed && te.Type.IsAbstract) {
1271 ec.Compiler.Report.Error (718, te.Location, "`{0}': static classes cannot be used as generic arguments",
1272 te.GetSignatureForError ());
1273 ok = false;
1274 }
1275
1276 if (te.Type.IsPointer || TypeManager.IsSpecialType (te.Type)) {
1277 ec.Compiler.Report.Error (306, te.Location,
1278 "The type `{0}' may not be used as a type argument",
1279 te.GetSignatureForError ());
1280 ok = false;
1281 }
1282 }
1283
1284 if (!ok)
1285 atypes = Type.EmptyTypes;
1286
1287 return ok;
1288 }
1289
1290 public TypeArguments Clone ()
1291 {
1292 TypeArguments copy = new TypeArguments ();
1293 foreach (var ta in args)
1294 copy.args.Add (ta);
1295
1296 return copy;
1297 }
1298 }
1299
1300 public class TypeParameterName : SimpleName
1301 {
1302 Attributes attributes;
1303 Variance variance;
1304
1305 public TypeParameterName (string name, Attributes attrs, Location loc)
1306 : this (name, attrs, Variance.None, loc)
1307 {
1308 }
1309
1310 public TypeParameterName (string name, Attributes attrs, Variance variance, Location loc)
1311 : base (name, loc)
1312 {
1313 attributes = attrs;
1314 this.variance = variance;
1315 }
1316
1317 public Attributes OptAttributes {
1318 get {
1319 return attributes;
1320 }
1321 }
1322
1323 public Variance Variance {
1324 get {
1325 return variance;
1326 }
1327 }
1328 }
1329
1330 /// <summary>
1331 /// A reference expression to generic type
1332 /// </summary>
1333 class GenericTypeExpr : TypeExpr
1334 {
1335 TypeArguments args;
1336 Type[] gen_params; // TODO: Waiting for constrains check cleanup
1337 Type open_type;
1338
1339 //
1340 // Should be carefully used only with defined generic containers. Type parameters
1341 // can be used as type arguments in this case.
1342 //
1343 // TODO: This could be GenericTypeExpr specialization
1344 //
1345 public GenericTypeExpr (DeclSpace gType, Location l)
1346 {
1347 open_type = gType.TypeBuilder.GetGenericTypeDefinition ();
1348
1349 args = new TypeArguments ();
1350 foreach (TypeParameter type_param in gType.TypeParameters)
1351 args.Add (new TypeParameterExpr (type_param, l));
1352
1353 this.loc = l;
1354 }
1355
1356 /// <summary>
1357 /// Instantiate the generic type `t' with the type arguments `args'.
1358 /// Use this constructor if you already know the fully resolved
1359 /// generic type.
1360 /// </summary>
1361 public GenericTypeExpr (Type t, TypeArguments args, Location l)
1362 {
1363 open_type = t.GetGenericTypeDefinition ();
1364
1365 loc = l;
1366 this.args = args;
1367 }
1368
1369 public TypeArguments TypeArguments {
1370 get { return args; }
1371 }
1372
1373 public override string GetSignatureForError ()
1374 {
1375 return TypeManager.CSharpName (type);
1376 }
1377
1378 protected override TypeExpr DoResolveAsTypeStep (IMemberContext ec)
1379 {
1380 eclass = ExprClass.Type;
1381
1382 if (!args.Resolve (ec))
1383 return null;
1384
1385 gen_params = open_type.GetGenericArguments ();
1386 Type[] atypes = args.Arguments;
1387
1388 if (atypes.Length != gen_params.Length) {
1389 Namespace.Error_InvalidNumberOfTypeArguments (ec.Compiler.Report, open_type, loc);
1390 return null;
1391 }
1392
1393 //
1394 // Now bind the parameters
1395 //
1396 type = open_type.MakeGenericType (atypes);
1397 return this;
1398 }
1399
1400 /// <summary>
1401 /// Check the constraints; we're called from ResolveAsTypeTerminal()
1402 /// after fully resolving the constructed type.
1403 /// </summary>
1404 public bool CheckConstraints (IMemberContext ec)
1405 {
1406 return ConstraintChecker.CheckConstraints (ec, open_type, gen_params, args.Arguments, loc);
1407 }
1408
1409 public override bool CheckAccessLevel (IMemberContext mc)
1410 {
1411 return mc.CurrentTypeDefinition.CheckAccessLevel (open_type);
1412 }
1413
1414 public bool HasDynamicArguments ()
1415 {
1416 return HasDynamicArguments (args.Arguments);
1417 }
1418
1419 static bool HasDynamicArguments (Type[] args)
1420 {
1421 foreach (var item in args)
1422 {
1423 if (TypeManager.IsGenericType (item))
1424 return HasDynamicArguments (TypeManager.GetTypeArguments (item));
1425
1426 if (TypeManager.IsDynamicType (item))
1427 return true;
1428 }
1429
1430 return false;
1431 }
1432
1433 public override bool IsClass {
1434 get { return open_type.IsClass; }
1435 }
1436
1437 public override bool IsValueType {
1438 get { return TypeManager.IsStruct (open_type); }
1439 }
1440
1441 public override bool IsInterface {
1442 get { return open_type.IsInterface; }
1443 }
1444
1445 public override bool IsSealed {
1446 get { return open_type.IsSealed; }
1447 }
1448
1449 public override bool Equals (object obj)
1450 {
1451 GenericTypeExpr cobj = obj as GenericTypeExpr;
1452 if (cobj == null)
1453 return false;
1454
1455 if ((type == null) || (cobj.type == null))
1456 return false;
1457
1458 return type == cobj.type;
1459 }
1460
1461 public override int GetHashCode ()
1462 {
1463 return base.GetHashCode ();
1464 }
1465 }
1466
1467 public abstract class ConstraintChecker
1468 {
1469 protected readonly Type[] gen_params;
1470 protected readonly Type[] atypes;
1471 protected readonly Location loc;
1472 protected Report Report;
1473
1474 protected ConstraintChecker (Type[] gen_params, Type[] atypes, Location loc, Report r)
1475 {
1476 this.gen_params = gen_params;
1477 this.atypes = atypes;
1478 this.loc = loc;
1479 this.Report = r;
1480 }
1481
1482 /// <summary>
1483 /// Check the constraints; we're called from ResolveAsTypeTerminal()
1484 /// after fully resolving the constructed type.
1485 /// </summary>
1486 public bool CheckConstraints (IMemberContext ec)
1487 {
1488 for (int i = 0; i < gen_params.Length; i++) {
1489 if (!CheckConstraints (ec, i))
1490 return false;
1491 }
1492
1493 return true;
1494 }
1495
1496 protected bool CheckConstraints (IMemberContext ec, int index)
1497 {
1498 Type atype = TypeManager.TypeToCoreType (atypes [index]);
1499 Type ptype = gen_params [index];
1500
1501 if (atype == ptype)
1502 return true;
1503
1504 Expression aexpr = new EmptyExpression (atype);
1505
1506 GenericConstraints gc = TypeManager.GetTypeParameterConstraints (ptype);
1507 if (gc == null)
1508 return true;
1509
1510 bool is_class, is_struct;
1511 if (atype.IsGenericParameter) {
1512 GenericConstraints agc = TypeManager.GetTypeParameterConstraints (atype);
1513 if (agc != null) {
1514 if (agc is Constraints) {
1515 // FIXME: No constraints can be resolved here, we are in
1516 // completely wrong/different context. This path is hit
1517 // when resolving base type of unresolved generic type
1518 // with constraints. We are waiting with CheckConsttraints
1519 // after type-definition but not in this case
1520 if (!((Constraints) agc).Resolve (null, null, Report))
1521 return true;
1522 }
1523 is_class = agc.IsReferenceType;
1524 is_struct = agc.IsValueType;
1525 } else {
1526 is_class = is_struct = false;
1527 }
1528 } else {
1529 is_class = TypeManager.IsReferenceType (atype);
1530 is_struct = TypeManager.IsValueType (atype) && !TypeManager.IsNullableType (atype);
1531 }
1532
1533 //
1534 // First, check the `class' and `struct' constraints.
1535 //
1536 if (gc.HasReferenceTypeConstraint && !is_class) {
1537 Report.Error (452, loc, "The type `{0}' must be " +
1538 "a reference type in order to use it " +
1539 "as type parameter `{1}' in the " +
1540 "generic type or method `{2}'.",
1541 TypeManager.CSharpName (atype),
1542 TypeManager.CSharpName (ptype),
1543 GetSignatureForError ());
1544 return false;
1545 } else if (gc.HasValueTypeConstraint && !is_struct) {
1546 Report.Error (453, loc, "The type `{0}' must be a " +
1547 "non-nullable value type in order to use it " +
1548 "as type parameter `{1}' in the " +
1549 "generic type or method `{2}'.",
1550 TypeManager.CSharpName (atype),
1551 TypeManager.CSharpName (ptype),
1552 GetSignatureForError ());
1553 return false;
1554 }
1555
1556 //
1557 // The class constraint comes next.
1558 //
1559 if (gc.HasClassConstraint) {
1560 if (!CheckConstraint (ec, ptype, aexpr, gc.ClassConstraint))
1561 return false;
1562 }
1563
1564 //
1565 // Now, check the interface constraints.
1566 //
1567 if (gc.InterfaceConstraints != null) {
1568 foreach (Type it in gc.InterfaceConstraints) {
1569 if (!CheckConstraint (ec, ptype, aexpr, it))
1570 return false;
1571 }
1572 }
1573
1574 //
1575 // Finally, check the constructor constraint.
1576 //
1577
1578 if (!gc.HasConstructorConstraint)
1579 return true;
1580
1581 if (TypeManager.IsValueType (atype))
1582 return true;
1583
1584 if (HasDefaultConstructor (atype))
1585 return true;
1586
1587 Report_SymbolRelatedToPreviousError ();
1588 Report.SymbolRelatedToPreviousError (atype);
1589 Report.Error (310, loc, "The type `{0}' must have a public " +
1590 "parameterless constructor in order to use it " +
1591 "as parameter `{1}' in the generic type or " +
1592 "method `{2}'",
1593 TypeManager.CSharpName (atype),
1594 TypeManager.CSharpName (ptype),
1595 GetSignatureForError ());
1596 return false;
1597 }
1598
1599 Type InflateType(IMemberContext ec, Type ctype)
1600 {
1601 Type[] types = TypeManager.GetTypeArguments (ctype);
1602
1603 TypeArguments new_args = new TypeArguments ();
1604
1605 for (int i = 0; i < types.Length; i++) {
1606 Type t = TypeManager.TypeToCoreType (types [i]);
1607
1608 if (t.IsGenericParameter) {
1609 int pos = t.GenericParameterPosition;
1610 if (t.DeclaringMethod == null && this is MethodConstraintChecker) {
1611 Type parent = ((MethodConstraintChecker) this).declaring_type;
1612 t = parent.GetGenericArguments ()[pos];
1613 } else {
1614 t = atypes [pos];
1615 }
1616 } else if(TypeManager.HasGenericArguments(t)) {
1617 t = InflateType (ec, t);
1618 if (t == null) {
1619 return null;
1620 }
1621 }
1622 new_args.Add (new TypeExpression (t, loc));
1623 }
1624
1625 TypeExpr ct = new GenericTypeExpr (ctype, new_args, loc);
1626 if (ct.ResolveAsTypeStep (ec, false) == null)
1627 return null;
1628
1629 return ct.Type;
1630 }
1631
1632 protected bool CheckConstraint (IMemberContext ec, Type ptype, Expression expr,
1633 Type ctype)
1634 {
1635 //
1636 // All this is needed because we don't have
1637 // real inflated type hierarchy
1638 //
1639 if (TypeManager.HasGenericArguments (ctype)) {
1640 ctype = InflateType (ec, ctype);
1641 if(ctype == null) {
1642 return false;
1643 }
1644 } else if (ctype.IsGenericParameter) {
1645 int pos = ctype.GenericParameterPosition;
1646 if (ctype.DeclaringMethod == null) {
1647 // FIXME: Implement
1648 return true;
1649 } else {
1650 ctype = atypes [pos];
1651 }
1652 }
1653
1654 if (Convert.ImplicitStandardConversionExists (expr, ctype))
1655 return true;
1656
1657 Report_SymbolRelatedToPreviousError ();
1658 Report.SymbolRelatedToPreviousError (expr.Type);
1659
1660 if (TypeManager.IsNullableType (expr.Type) && ctype.IsInterface) {
1661 Report.Error (313, loc,
1662 "The type `{0}' cannot be used as type parameter `{1}' in the generic type or method `{2}'. " +
1663 "The nullable type `{0}' never satisfies interface constraint of type `{3}'",
1664 TypeManager.CSharpName (expr.Type), TypeManager.CSharpName (ptype),
1665 GetSignatureForError (), TypeManager.CSharpName (ctype));
1666 } else {
1667 Report.Error (309, loc,
1668 "The type `{0}' must be convertible to `{1}' in order to " +
1669 "use it as parameter `{2}' in the generic type or method `{3}'",
1670 TypeManager.CSharpName (expr.Type), TypeManager.CSharpName (ctype),
1671 TypeManager.CSharpName (ptype), GetSignatureForError ());
1672 }
1673 return false;
1674 }
1675
1676 static bool HasDefaultConstructor (Type atype)
1677 {
1678 TypeParameter tparam = TypeManager.LookupTypeParameter (atype);
1679 if (tparam != null) {
1680 if (tparam.GenericConstraints == null)
1681 return false;
1682
1683 return tparam.GenericConstraints.HasConstructorConstraint ||
1684 tparam.GenericConstraints.HasValueTypeConstraint;
1685 }
1686
1687 if (atype.IsAbstract)
1688 return false;
1689
1690 again:
1691 atype = TypeManager.DropGenericTypeArguments (atype);
1692 if (atype is TypeBuilder) {
1693 TypeContainer tc = TypeManager.LookupTypeContainer (atype);
1694 if (tc.InstanceConstructors == null) {
1695 atype = atype.BaseType;
1696 goto again;
1697 }
1698
1699 foreach (Constructor c in tc.InstanceConstructors) {
1700 if ((c.ModFlags & Modifiers.PUBLIC) == 0)
1701 continue;
1702 if ((c.Parameters.FixedParameters != null) &&
1703 (c.Parameters.FixedParameters.Length != 0))
1704 continue;
1705 if (c.Parameters.HasArglist || c.Parameters.HasParams)
1706 continue;
1707
1708 return true;
1709 }
1710 }
1711
1712 MemberInfo [] list = TypeManager.MemberLookup (null, null, atype, MemberTypes.Constructor,
1713 BindingFlags.Public | BindingFlags.Instance | BindingFlags.DeclaredOnly,
1714 ConstructorInfo.ConstructorName, null);
1715
1716 if (list == null)
1717 return false;
1718
1719 foreach (MethodBase mb in list) {
1720 AParametersCollection pd = TypeManager.GetParameterData (mb);
1721 if (pd.Count == 0)
1722 return true;
1723 }
1724
1725 return false;
1726 }
1727
1728 protected abstract string GetSignatureForError ();
1729 protected abstract void Report_SymbolRelatedToPreviousError ();
1730
1731 public static bool CheckConstraints (IMemberContext ec, MethodBase definition,
1732 MethodBase instantiated, Location loc)
1733 {
1734 MethodConstraintChecker checker = new MethodConstraintChecker (
1735 definition, instantiated.DeclaringType, definition.GetGenericArguments (),
1736 instantiated.GetGenericArguments (), loc, ec.Compiler.Report);
1737
1738 return checker.CheckConstraints (ec);
1739 }
1740
1741 public static bool CheckConstraints (IMemberContext ec, Type gt, Type[] gen_params,
1742 Type[] atypes, Location loc)
1743 {
1744 TypeConstraintChecker checker = new TypeConstraintChecker (
1745 gt, gen_params, atypes, loc, ec.Compiler.Report);
1746
1747 return checker.CheckConstraints (ec);
1748 }
1749
1750 protected class MethodConstraintChecker : ConstraintChecker
1751 {
1752 MethodBase definition;
1753 public Type declaring_type;
1754
1755 public MethodConstraintChecker (MethodBase definition, Type declaringType, Type[] gen_params,
1756 Type[] atypes, Location loc, Report r)
1757 : base (gen_params, atypes, loc, r)
1758 {
1759 this.declaring_type = declaringType;
1760 this.definition = definition;
1761 }
1762
1763 protected override string GetSignatureForError ()
1764 {
1765 return TypeManager.CSharpSignature (definition);
1766 }
1767
1768 protected override void Report_SymbolRelatedToPreviousError ()
1769 {
1770 Report.SymbolRelatedToPreviousError (definition);
1771 }
1772 }
1773
1774 protected class TypeConstraintChecker : ConstraintChecker
1775 {
1776 Type gt;
1777
1778 public TypeConstraintChecker (Type gt, Type[] gen_params, Type[] atypes,
1779 Location loc, Report r)
1780 : base (gen_params, atypes, loc, r)
1781 {
1782 this.gt = gt;
1783 }
1784
1785 protected override string GetSignatureForError ()
1786 {
1787 return TypeManager.CSharpName (gt);
1788 }
1789
1790 protected override void Report_SymbolRelatedToPreviousError ()
1791 {
1792 Report.SymbolRelatedToPreviousError (gt);
1793 }
1794 }
1795 }
1796
1797 /// <summary>
1798 /// A generic method definition.
1799 /// </summary>
1800 public class GenericMethod : DeclSpace
1801 {
1802 FullNamedExpression return_type;
1803 ParametersCompiled parameters;
1804
1805 public GenericMethod (NamespaceEntry ns, DeclSpace parent, MemberName name,
1806 FullNamedExpression return_type, ParametersCompiled parameters)
1807 : base (ns, parent, name, null)
1808 {
1809 this.return_type = return_type;
1810 this.parameters = parameters;
1811 }
1812
1813 public override TypeContainer CurrentTypeDefinition {
1814 get {
1815 return Parent.CurrentTypeDefinition;
1816 }
1817 }
1818
1819 public override TypeParameter[] CurrentTypeParameters {
1820 get {
1821 return base.type_params;
1822 }
1823 }
1824
1825 public override TypeBuilder DefineType ()
1826 {
1827 throw new Exception ();
1828 }
1829
1830 public override bool Define ()
1831 {
1832 for (int i = 0; i < TypeParameters.Length; i++)
1833 if (!TypeParameters [i].Resolve (this))
1834 return false;
1835
1836 return true;
1837 }
1838
1839 /// <summary>
1840 /// Define and resolve the type parameters.
1841 /// We're called from Method.Define().
1842 /// </summary>
1843 public bool Define (MethodOrOperator m)
1844 {
1845 TypeParameterName[] names = MemberName.TypeArguments.GetDeclarations ();
1846 string[] snames = new string [names.Length];
1847 for (int i = 0; i < names.Length; i++) {
1848 string type_argument_name = names[i].Name;
1849 int idx = parameters.GetParameterIndexByName (type_argument_name);
1850 if (idx >= 0) {
1851 Block b = m.Block;
1852 if (b == null)
1853 b = new Block (null);
1854
1855 b.Error_AlreadyDeclaredTypeParameter (Report, parameters [i].Location,
1856 type_argument_name, "method parameter");
1857 }
1858
1859 snames[i] = type_argument_name;
1860 }
1861
1862 GenericTypeParameterBuilder[] gen_params = m.MethodBuilder.DefineGenericParameters (snames);
1863 for (int i = 0; i < TypeParameters.Length; i++)
1864 TypeParameters [i].Define (gen_params [i]);
1865
1866 if (!Define ())
1867 return false;
1868
1869 for (int i = 0; i < TypeParameters.Length; i++) {
1870 if (!TypeParameters [i].ResolveType (this))
1871 return false;
1872 }
1873
1874 return true;
1875 }
1876
1877 /// <summary>
1878 /// We're called from MethodData.Define() after creating the MethodBuilder.
1879 /// </summary>
1880 public bool DefineType (IMemberContext ec, MethodBuilder mb,
1881 MethodInfo implementing, bool is_override)
1882 {
1883 for (int i = 0; i < TypeParameters.Length; i++)
1884 if (!TypeParameters [i].DefineType (
1885 ec, mb, implementing, is_override))
1886 return false;
1887
1888 bool ok = parameters.Resolve (ec);
1889
1890 if ((return_type != null) && (return_type.ResolveAsTypeTerminal (ec, false) == null))
1891 ok = false;
1892
1893 return ok;
1894 }
1895
1896 public void EmitAttributes ()
1897 {
1898 for (int i = 0; i < TypeParameters.Length; i++)
1899 TypeParameters [i].Emit ();
1900
1901 if (OptAttributes != null)
1902 OptAttributes.Emit ();
1903 }
1904
1905 public override MemberList FindMembers (MemberTypes mt, BindingFlags bf,
1906 MemberFilter filter, object criteria)
1907 {
1908 throw new Exception ();
1909 }
1910
1911 public override string GetSignatureForError ()
1912 {
1913 return base.GetSignatureForError () + parameters.GetSignatureForError ();
1914 }
1915
1916 public override MemberCache MemberCache {
1917 get {
1918 return null;
1919 }
1920 }
1921
1922 public override AttributeTargets AttributeTargets {
1923 get {
1924 return AttributeTargets.Method | AttributeTargets.ReturnValue;
1925 }
1926 }
1927
1928 public override string DocCommentHeader {
1929 get { return "M:"; }
1930 }
1931
1932 public new void VerifyClsCompliance ()
1933 {
1934 foreach (TypeParameter tp in TypeParameters) {
1935 if (tp.Constraints == null)
1936 continue;
1937
1938 tp.Constraints.VerifyClsCompliance (Report);
1939 }
1940 }
1941 }
1942
1943 partial class TypeManager
1944 {
1945 public static TypeContainer LookupGenericTypeContainer (Type t)
1946 {
1947 t = DropGenericTypeArguments (t);
1948 return LookupTypeContainer (t);
1949 }
1950
1951 public static Variance GetTypeParameterVariance (Type type)
1952 {
1953 TypeParameter tparam = LookupTypeParameter (type);
1954 if (tparam != null)
1955 return tparam.Variance;
1956
1957 switch (type.GenericParameterAttributes & GenericParameterAttributes.VarianceMask) {
1958 case GenericParameterAttributes.Covariant:
1959 return Variance.Covariant;
1960 case GenericParameterAttributes.Contravariant:
1961 return Variance.Contravariant;
1962 default:
1963 return Variance.None;
1964 }
1965 }
1966
1967 public static Variance CheckTypeVariance (Type t, Variance expected, IMemberContext member)
1968 {
1969 TypeParameter tp = LookupTypeParameter (t);
1970 if (tp != null) {
1971 Variance v = tp.Variance;
1972 if (expected == Variance.None && v != expected ||
1973 expected == Variance.Covariant && v == Variance.Contravariant ||
1974 expected == Variance.Contravariant && v == Variance.Covariant)
1975 tp.ErrorInvalidVariance (member, expected);
1976
1977 return expected;
1978 }
1979
1980 if (t.IsGenericType) {
1981 Type[] targs_definition = GetTypeArguments (DropGenericTypeArguments (t));
1982 Type[] targs = GetTypeArguments (t);
1983 for (int i = 0; i < targs_definition.Length; ++i) {
1984 Variance v = GetTypeParameterVariance (targs_definition[i]);
1985 CheckTypeVariance (targs[i], (Variance) ((int)v * (int)expected), member);
1986 }
1987
1988 return expected;
1989 }
1990
1991 if (t.IsArray)
1992 return CheckTypeVariance (GetElementType (t), expected, member);
1993
1994 return Variance.None;
1995 }
1996
1997 public static bool IsVariantOf (Type type1, Type type2)
1998 {
1999 if (!type1.IsGenericType || !type2.IsGenericType)
2000 return false;
2001
2002 Type generic_target_type = DropGenericTypeArguments (type2);
2003 if (DropGenericTypeArguments (type1) != generic_target_type)
2004 return false;
2005
2006 Type[] t1 = GetTypeArguments (type1);
2007 Type[] t2 = GetTypeArguments (type2);
2008 Type[] targs_definition = GetTypeArguments (generic_target_type);
2009 for (int i = 0; i < targs_definition.Length; ++i) {
2010 Variance v = GetTypeParameterVariance (targs_definition [i]);
2011 if (v == Variance.None) {
2012 if (t1[i] == t2[i])
2013 continue;
2014 return false;
2015 }
2016
2017 if (v == Variance.Covariant) {
2018 if (!Convert.ImplicitReferenceConversionExists (new EmptyExpression (t1 [i]), t2 [i]))
2019 return false;
2020 } else if (!Convert.ImplicitReferenceConversionExists (new EmptyExpression (t2[i]), t1[i])) {
2021 return false;
2022 }
2023 }
2024
2025 return true;
2026 }
2027
2028 /// <summary>
2029 /// Check whether `a' and `b' may become equal generic types.
2030 /// The algorithm to do that is a little bit complicated.
2031 /// </summary>
2032 public static bool MayBecomeEqualGenericTypes (Type a, Type b, Type[] class_inferred,
2033 Type[] method_inferred)
2034 {
2035 if (a.IsGenericParameter) {
2036 //
2037 // If a is an array of a's type, they may never
2038 // become equal.
2039 //
2040 while (b.IsArray) {
2041 b = GetElementType (b);
2042 if (a.Equals (b))
2043 return false;
2044 }
2045
2046 //
2047 // If b is a generic parameter or an actual type,
2048 // they may become equal:
2049 //
2050 // class X<T,U> : I<T>, I<U>
2051 // class X<T> : I<T>, I<float>
2052 //
2053 if (b.IsGenericParameter || !b.IsGenericType) {
2054 int pos = a.GenericParameterPosition;
2055 Type[] args = a.DeclaringMethod != null ? method_inferred : class_inferred;
2056 if (args [pos] == null) {
2057 args [pos] = b;
2058 return true;
2059 }
2060
2061 return args [pos] == a;
2062 }
2063
2064 //
2065 // We're now comparing a type parameter with a
2066 // generic instance. They may become equal unless
2067 // the type parameter appears anywhere in the
2068 // generic instance:
2069 //
2070 // class X<T,U> : I<T>, I<X<U>>
2071 // -> error because you could instanciate it as
2072 // X<X<int>,int>
2073 //
2074 // class X<T> : I<T>, I<X<T>> -> ok
2075 //
2076
2077 Type[] bargs = GetTypeArguments (b);
2078 for (int i = 0; i < bargs.Length; i++) {
2079 if (a.Equals (bargs [i]))
2080 return false;
2081 }
2082
2083 return true;
2084 }
2085
2086 if (b.IsGenericParameter)
2087 return MayBecomeEqualGenericTypes (b, a, class_inferred, method_inferred);
2088
2089 //
2090 // At this point, neither a nor b are a type parameter.
2091 //
2092 // If one of them is a generic instance, let
2093 // MayBecomeEqualGenericInstances() compare them (if the
2094 // other one is not a generic instance, they can never
2095 // become equal).
2096 //
2097
2098 if (a.IsGenericType || b.IsGenericType)
2099 return MayBecomeEqualGenericInstances (a, b, class_inferred, method_inferred);
2100
2101 //
2102 // If both of them are arrays.
2103 //
2104
2105 if (a.IsArray && b.IsArray) {
2106 if (a.GetArrayRank () != b.GetArrayRank ())
2107 return false;
2108
2109 a = GetElementType (a);
2110 b = GetElementType (b);
2111
2112 return MayBecomeEqualGenericTypes (a, b, class_inferred, method_inferred);
2113 }
2114
2115 //
2116 // Ok, two ordinary types.
2117 //
2118
2119 return a.Equals (b);
2120 }
2121
2122 //
2123 // Checks whether two generic instances may become equal for some
2124 // particular instantiation (26.3.1).
2125 //
2126 public static bool MayBecomeEqualGenericInstances (Type a, Type b,
2127 Type[] class_inferred,
2128 Type[] method_inferred)
2129 {
2130 if (!a.IsGenericType || !b.IsGenericType)
2131 return false;
2132 if (a.GetGenericTypeDefinition () != b.GetGenericTypeDefinition ())
2133 return false;
2134
2135 return MayBecomeEqualGenericInstances (
2136 GetTypeArguments (a), GetTypeArguments (b), class_inferred, method_inferred);
2137 }
2138
2139 public static bool MayBecomeEqualGenericInstances (Type[] aargs, Type[] bargs,
2140 Type[] class_inferred,
2141 Type[] method_inferred)
2142 {
2143 if (aargs.Length != bargs.Length)
2144 return false;
2145
2146 for (int i = 0; i < aargs.Length; i++) {
2147 if (!MayBecomeEqualGenericTypes (aargs [i], bargs [i], class_inferred, method_inferred))
2148 return false;
2149 }
2150
2151 return true;
2152 }
2153
2154 /// <summary>
2155 /// Type inference. Try to infer the type arguments from `method',
2156 /// which is invoked with the arguments `arguments'. This is used
2157 /// when resolving an Invocation or a DelegateInvocation and the user
2158 /// did not explicitly specify type arguments.
2159 /// </summary>
2160 public static int InferTypeArguments (ResolveContext ec, Arguments arguments, ref MethodSpec method)
2161 {
2162 ATypeInference ti = ATypeInference.CreateInstance (arguments);
2163 Type[] i_args = ti.InferMethodArguments (ec, method);
2164 if (i_args == null)
2165 return ti.InferenceScore;
2166
2167 if (i_args.Length == 0)
2168 return 0;
2169
2170 method = method.Inflate (i_args);
2171 return 0;
2172 }
2173
2174 /*
2175 public static bool InferTypeArguments (ResolveContext ec, AParametersCollection param, ref MethodBase method)
2176 {
2177 if (!TypeManager.IsGenericMethod (method))
2178 return true;
2179
2180 ATypeInference ti = ATypeInference.CreateInstance (DelegateCreation.CreateDelegateMethodArguments (param, Location.Null));
2181 Type[] i_args = ti.InferDelegateArguments (ec, method);
2182 if (i_args == null)
2183 return false;
2184
2185 method = ((MethodInfo) method).MakeGenericMethod (i_args);
2186 return true;
2187 }
2188 */
2189 }
2190
2191 abstract class ATypeInference
2192 {
2193 protected readonly Arguments arguments;
2194 protected readonly int arg_count;
2195
2196 protected ATypeInference (Arguments arguments)
2197 {
2198 this.arguments = arguments;
2199 if (arguments != null)
2200 arg_count = arguments.Count;
2201 }
2202
2203 public static ATypeInference CreateInstance (Arguments arguments)
2204 {
2205 return new TypeInference (arguments);
2206 }
2207
2208 public virtual int InferenceScore {
2209 get {
2210 return int.MaxValue;
2211 }
2212 }
2213
2214 public abstract Type[] InferMethodArguments (ResolveContext ec, MethodSpec method);
2215 // public abstract Type[] InferDelegateArguments (ResolveContext ec, MethodBase method);
2216 }
2217
2218 //
2219 // Implements C# type inference
2220 //
2221 class TypeInference : ATypeInference
2222 {
2223 //
2224 // Tracks successful rate of type inference
2225 //
2226 int score = int.MaxValue;
2227
2228 public TypeInference (Arguments arguments)
2229 : base (arguments)
2230 {
2231 }
2232
2233 public override int InferenceScore {
2234 get {
2235 return score;
2236 }
2237 }
2238
2239 /*
2240 public override Type[] InferDelegateArguments (ResolveContext ec, MethodBase method)
2241 {
2242 AParametersCollection pd = TypeManager.GetParameterData (method);
2243 if (arg_count != pd.Count)
2244 return null;
2245
2246 Type[] d_gargs = method.GetGenericArguments ();
2247 TypeInferenceContext context = new TypeInferenceContext (d_gargs);
2248
2249 // A lower-bound inference is made from each argument type Uj of D
2250 // to the corresponding parameter type Tj of M
2251 for (int i = 0; i < arg_count; ++i) {
2252 Type t = pd.Types [i];
2253 if (!t.IsGenericParameter)
2254 continue;
2255
2256 context.LowerBoundInference (arguments [i].Expr.Type, t);
2257 }
2258
2259 if (!context.FixAllTypes (ec))
2260 return null;
2261
2262 return context.InferredTypeArguments;
2263 }
2264 */
2265 public override Type[] InferMethodArguments (ResolveContext ec, MethodSpec method)
2266 {
2267 var method_generic_args = method.GetGenericArguments ();
2268 TypeInferenceContext context = new TypeInferenceContext (method_generic_args);
2269 if (!context.UnfixedVariableExists)
2270 return Type.EmptyTypes;
2271
2272 AParametersCollection pd = method.Parameters;
2273 if (!InferInPhases (ec, context, pd))
2274 return null;
2275
2276 return context.InferredTypeArguments;
2277 }
2278
2279 //
2280 // Implements method type arguments inference
2281 //
2282 bool InferInPhases (ResolveContext ec, TypeInferenceContext tic, AParametersCollection methodParameters)
2283 {
2284 int params_arguments_start;
2285 if (methodParameters.HasParams) {
2286 params_arguments_start = methodParameters.Count - 1;
2287 } else {
2288 params_arguments_start = arg_count;
2289 }
2290
2291 Type [] ptypes = methodParameters.Types;
2292
2293 //
2294 // The first inference phase
2295 //
2296 Type method_parameter = null;
2297 for (int i = 0; i < arg_count; i++) {
2298 Argument a = arguments [i];
2299 if (a == null)
2300 continue;
2301
2302 if (i < params_arguments_start) {
2303 method_parameter = methodParameters.Types [i];
2304 } else if (i == params_arguments_start) {
2305 if (arg_count == params_arguments_start + 1 && TypeManager.HasElementType (a.Type))
2306 method_parameter = methodParameters.Types [params_arguments_start];
2307 else
2308 method_parameter = TypeManager.GetElementType (methodParameters.Types [params_arguments_start]);
2309
2310 ptypes = (Type[]) ptypes.Clone ();
2311 ptypes [i] = method_parameter;
2312 }
2313
2314 //
2315 // When a lambda expression, an anonymous method
2316 // is used an explicit argument type inference takes a place
2317 //
2318 AnonymousMethodExpression am = a.Expr as AnonymousMethodExpression;
2319 if (am != null) {
2320 if (am.ExplicitTypeInference (ec, tic, method_parameter))
2321 --score;
2322 continue;
2323 }
2324
2325 if (a.IsByRef) {
2326 score -= tic.ExactInference (a.Type, method_parameter);
2327 continue;
2328 }
2329
2330 if (a.Expr.Type == TypeManager.null_type)
2331 continue;
2332
2333 if (TypeManager.IsValueType (method_parameter)) {
2334 score -= tic.LowerBoundInference (a.Type, method_parameter);
2335 continue;
2336 }
2337
2338 //
2339 // Otherwise an output type inference is made
2340 //
2341 score -= tic.OutputTypeInference (ec, a.Expr, method_parameter);
2342 }
2343
2344 //
2345 // Part of the second phase but because it happens only once
2346 // we don't need to call it in cycle
2347 //
2348 bool fixed_any = false;
2349 if (!tic.FixIndependentTypeArguments (ec, ptypes, ref fixed_any))
2350 return false;
2351
2352 return DoSecondPhase (ec, tic, ptypes, !fixed_any);
2353 }
2354
2355 bool DoSecondPhase (ResolveContext ec, TypeInferenceContext tic, Type[] methodParameters, bool fixDependent)
2356 {
2357 bool fixed_any = false;
2358 if (fixDependent && !tic.FixDependentTypes (ec, ref fixed_any))
2359 return false;
2360
2361 // If no further unfixed type variables exist, type inference succeeds
2362 if (!tic.UnfixedVariableExists)
2363 return true;
2364
2365 if (!fixed_any && fixDependent)
2366 return false;
2367
2368 // For all arguments where the corresponding argument output types
2369 // contain unfixed type variables but the input types do not,
2370 // an output type inference is made
2371 for (int i = 0; i < arg_count; i++) {
2372
2373 // Align params arguments
2374 Type t_i = methodParameters [i >= methodParameters.Length ? methodParameters.Length - 1: i];
2375
2376 if (!TypeManager.IsDelegateType (t_i)) {
2377 if (TypeManager.DropGenericTypeArguments (t_i) != TypeManager.expression_type)
2378 continue;
2379
2380 t_i = t_i.GetGenericArguments () [0];
2381 }
2382
2383 var mi = Delegate.GetInvokeMethod (ec.Compiler, t_i, t_i);
2384 Type rtype = mi.ReturnType;
2385
2386 #if MS_COMPATIBLE
2387 // Blablabla, because reflection does not work with dynamic types
2388 // Type[] g_args = t_i.GetGenericArguments ();
2389 // rtype = g_args[rtype.GenericParameterPosition];
2390 #endif
2391
2392 if (tic.IsReturnTypeNonDependent (ec, mi, rtype))
2393 score -= tic.OutputTypeInference (ec, arguments [i].Expr, t_i);
2394 }
2395
2396
2397 return DoSecondPhase (ec, tic, methodParameters, true);
2398 }
2399 }
2400
2401 public class TypeInferenceContext
2402 {
2403 enum BoundKind
2404 {
2405 Exact = 0,
2406 Lower = 1,
2407 Upper = 2
2408 }
2409
2410 class BoundInfo
2411 {
2412 public readonly Type Type;
2413 public readonly BoundKind Kind;
2414
2415 public BoundInfo (Type type, BoundKind kind)
2416 {
2417 this.Type = type;
2418 this.Kind = kind;
2419 }
2420
2421 public override int GetHashCode ()
2422 {
2423 return Type.GetHashCode ();
2424 }
2425
2426 public override bool Equals (object obj)
2427 {
2428 BoundInfo a = (BoundInfo) obj;
2429 return Type == a.Type && Kind == a.Kind;
2430 }
2431 }
2432
2433 readonly Type[] unfixed_types;
2434 readonly Type[] fixed_types;
2435 readonly List<BoundInfo>[] bounds;
2436 bool failed;
2437
2438 public TypeInferenceContext (Type[] typeArguments)
2439 {
2440 if (typeArguments.Length == 0)
2441 throw new ArgumentException ("Empty generic arguments");
2442
2443 fixed_types = new Type [typeArguments.Length];
2444 for (int i = 0; i < typeArguments.Length; ++i) {
2445 if (typeArguments [i].IsGenericParameter) {
2446 if (bounds == null) {
2447 bounds = new List<BoundInfo> [typeArguments.Length];
2448 unfixed_types = new Type [typeArguments.Length];
2449 }
2450 unfixed_types [i] = typeArguments [i];
2451 } else {
2452 fixed_types [i] = typeArguments [i];
2453 }
2454 }
2455 }
2456
2457 //
2458 // Used together with AddCommonTypeBound fo implement
2459 // 7.4.2.13 Finding the best common type of a set of expressions
2460 //
2461 public TypeInferenceContext ()
2462 {
2463 fixed_types = new Type [1];
2464 unfixed_types = new Type [1];
2465 unfixed_types[0] = InternalType.Arglist; // it can be any internal type
2466 bounds = new List<BoundInfo> [1];
2467 }
2468
2469 public Type[] InferredTypeArguments {
2470 get {
2471 return fixed_types;
2472 }
2473 }
2474
2475 public void AddCommonTypeBound (Type type)
2476 {
2477 AddToBounds (new BoundInfo (type, BoundKind.Lower), 0);
2478 }
2479
2480 void AddToBounds (BoundInfo bound, int index)
2481 {
2482 //
2483 // Some types cannot be used as type arguments
2484 //
2485 if (bound.Type == TypeManager.void_type || bound.Type.IsPointer)
2486 return;
2487
2488 var a = bounds [index];
2489 if (a == null) {
2490 a = new List<BoundInfo> ();
2491 bounds [index] = a;
2492 } else {
2493 if (a.Contains (bound))
2494 return;
2495 }
2496
2497 //
2498 // SPEC: does not cover type inference using constraints
2499 //
2500 //if (TypeManager.IsGenericParameter (t)) {
2501 // GenericConstraints constraints = TypeManager.GetTypeParameterConstraints (t);
2502 // if (constraints != null) {
2503 // //if (constraints.EffectiveBaseClass != null)
2504 // // t = constraints.EffectiveBaseClass;
2505 // }
2506 //}
2507 a.Add (bound);
2508 }
2509
2510 bool AllTypesAreFixed (Type[] types)
2511 {
2512 foreach (Type t in types) {
2513 if (t.IsGenericParameter) {
2514 if (!IsFixed (t))
2515 return false;
2516 continue;
2517 }
2518
2519 if (t.IsGenericType)
2520 return AllTypesAreFixed (t.GetGenericArguments ());
2521 }
2522
2523 return true;
2524 }
2525
2526 //
2527 // 26.3.3.8 Exact Inference
2528 //
2529 public int ExactInference (Type u, Type v)
2530 {
2531 // If V is an array type
2532 if (v.IsArray) {
2533 if (!u.IsArray)
2534 return 0;
2535
2536 if (u.GetArrayRank () != v.GetArrayRank ())
2537 return 0;
2538
2539 return ExactInference (TypeManager.GetElementType (u), TypeManager.GetElementType (v));
2540 }
2541
2542 // If V is constructed type and U is constructed type
2543 if (v.IsGenericType && !v.IsGenericTypeDefinition) {
2544 if (!u.IsGenericType)
2545 return 0;
2546
2547 Type [] ga_u = u.GetGenericArguments ();
2548 Type [] ga_v = v.GetGenericArguments ();
2549 if (ga_u.Length != ga_v.Length)
2550 return 0;
2551
2552 int score = 0;
2553 for (int i = 0; i < ga_u.Length; ++i)
2554 score += ExactInference (ga_u [i], ga_v [i]);
2555
2556 return score > 0 ? 1 : 0;
2557 }
2558
2559 // If V is one of the unfixed type arguments
2560 int pos = IsUnfixed (v);
2561 if (pos == -1)
2562 return 0;
2563
2564 AddToBounds (new BoundInfo (u, BoundKind.Exact), pos);
2565 return 1;
2566 }
2567
2568 public bool FixAllTypes (ResolveContext ec)
2569 {
2570 for (int i = 0; i < unfixed_types.Length; ++i) {
2571 if (!FixType (ec, i))
2572 return false;
2573 }
2574 return true;
2575 }
2576
2577 //
2578 // All unfixed type variables Xi are fixed for which all of the following hold:
2579 // a, There is at least one type variable Xj that depends on Xi
2580 // b, Xi has a non-empty set of bounds
2581 //
2582 public bool FixDependentTypes (ResolveContext ec, ref bool fixed_any)
2583 {
2584 for (int i = 0; i < unfixed_types.Length; ++i) {
2585 if (unfixed_types[i] == null)
2586 continue;
2587
2588 if (bounds[i] == null)
2589 continue;
2590
2591 if (!FixType (ec, i))
2592 return false;
2593
2594 fixed_any = true;
2595 }
2596
2597 return true;
2598 }
2599
2600 //
2601 // All unfixed type variables Xi which depend on no Xj are fixed
2602 //
2603 public bool FixIndependentTypeArguments (ResolveContext ec, Type[] methodParameters, ref bool fixed_any)
2604 {
2605 var types_to_fix = new List<Type> (unfixed_types);
2606 for (int i = 0; i < methodParameters.Length; ++i) {
2607 Type t = methodParameters[i];
2608
2609 if (!TypeManager.IsDelegateType (t)) {
2610 if (TypeManager.DropGenericTypeArguments (t) != TypeManager.expression_type)
2611 continue;
2612
2613 t = t.GetGenericArguments () [0];
2614 }
2615
2616 if (t.IsGenericParameter)
2617 continue;
2618
2619 var invoke = Delegate.GetInvokeMethod (ec.Compiler, t, t);
2620 Type rtype = invoke.ReturnType;
2621 if (!rtype.IsGenericParameter && !rtype.IsGenericType)
2622 continue;
2623
2624 #if MS_COMPATIBLE
2625 // Blablabla, because reflection does not work with dynamic types
2626 // if (rtype.IsGenericParameter) {
2627 // Type [] g_args = t.GetGenericArguments ();
2628 // rtype = g_args [rtype.GenericParameterPosition];
2629 // }
2630 #endif
2631 // Remove dependent types, they cannot be fixed yet
2632 RemoveDependentTypes (types_to_fix, rtype);
2633 }
2634
2635 foreach (Type t in types_to_fix) {
2636 if (t == null)
2637 continue;
2638
2639 int idx = IsUnfixed (t);
2640 if (idx >= 0 && !FixType (ec, idx)) {
2641 return false;
2642 }
2643 }
2644
2645 fixed_any = types_to_fix.Count > 0;
2646 return true;
2647 }
2648
2649 //
2650 // 26.3.3.10 Fixing
2651 //
2652 public bool FixType (ResolveContext ec, int i)
2653 {
2654 // It's already fixed
2655 if (unfixed_types[i] == null)
2656 throw new InternalErrorException ("Type argument has been already fixed");
2657
2658 if (failed)
2659 return false;
2660
2661 var candidates = bounds [i];
2662 if (candidates == null)
2663 return false;
2664
2665 if (candidates.Count == 1) {
2666 unfixed_types[i] = null;
2667 Type t = candidates[0].Type;
2668 if (t == TypeManager.null_type)
2669 return false;
2670
2671 fixed_types [i] = t;
2672 return true;
2673 }
2674
2675 //
2676 // Determines a unique type from which there is
2677 // a standard implicit conversion to all the other
2678 // candidate types.
2679 //
2680 Type best_candidate = null;
2681 int cii;
2682 int candidates_count = candidates.Count;
2683 for (int ci = 0; ci < candidates_count; ++ci) {
2684 BoundInfo bound = (BoundInfo)candidates [ci];
2685 for (cii = 0; cii < candidates_count; ++cii) {
2686 if (cii == ci)
2687 continue;
2688
2689 BoundInfo cbound = (BoundInfo) candidates[cii];
2690
2691 // Same type parameters with different bounds
2692 if (cbound.Type == bound.Type) {
2693 if (bound.Kind != BoundKind.Exact)
2694 bound = cbound;
2695
2696 continue;
2697 }
2698
2699 if (bound.Kind == BoundKind.Exact || cbound.Kind == BoundKind.Exact) {
2700 if (cbound.Kind != BoundKind.Exact) {
2701 if (!Convert.ImplicitConversionExists (ec, new TypeExpression (cbound.Type, Location.Null), bound.Type)) {
2702 break;
2703 }
2704
2705 continue;
2706 }
2707
2708 if (bound.Kind != BoundKind.Exact) {
2709 if (!Convert.ImplicitConversionExists (ec, new TypeExpression (bound.Type, Location.Null), cbound.Type)) {
2710 break;
2711 }
2712
2713 bound = cbound;
2714 continue;
2715 }
2716
2717 break;
2718 }
2719
2720 if (bound.Kind == BoundKind.Lower) {
2721 if (!Convert.ImplicitConversionExists (ec, new TypeExpression (cbound.Type, Location.Null), bound.Type)) {
2722 break;
2723 }
2724 } else {
2725 if (!Convert.ImplicitConversionExists (ec, new TypeExpression (bound.Type, Location.Null), cbound.Type)) {
2726 break;
2727 }
2728 }
2729 }
2730
2731 if (cii != candidates_count)
2732 continue;
2733
2734 if (best_candidate != null && best_candidate != bound.Type)
2735 return false;
2736
2737 best_candidate = bound.Type;
2738 }
2739
2740 if (best_candidate == null)
2741 return false;
2742
2743 unfixed_types[i] = null;
2744 fixed_types[i] = best_candidate;
2745 return true;
2746 }
2747
2748 //
2749 // Uses inferred types to inflate delegate type argument
2750 //
2751 public Type InflateGenericArgument (Type parameter)
2752 {
2753 if (parameter.IsGenericParameter) {
2754 //
2755 // Inflate method generic argument (MVAR) only
2756 //
2757 if (parameter.DeclaringMethod == null)
2758 return parameter;
2759
2760 return fixed_types [parameter.GenericParameterPosition];
2761 }
2762
2763 if (parameter.IsGenericType) {
2764 Type [] parameter_targs = parameter.GetGenericArguments ();
2765 for (int ii = 0; ii < parameter_targs.Length; ++ii) {
2766 parameter_targs [ii] = InflateGenericArgument (parameter_targs [ii]);
2767 }
2768 return parameter.GetGenericTypeDefinition ().MakeGenericType (parameter_targs);
2769 }
2770
2771 return parameter;
2772 }
2773
2774 //
2775 // Tests whether all delegate input arguments are fixed and generic output type
2776 // requires output type inference
2777 //
2778 public bool IsReturnTypeNonDependent (ResolveContext ec, MethodSpec invoke, Type returnType)
2779 {
2780 if (returnType.IsGenericParameter) {
2781 if (IsFixed (returnType))
2782 return false;
2783 } else if (returnType.IsGenericType) {
2784 if (TypeManager.IsDelegateType (returnType)) {
2785 invoke = Delegate.GetInvokeMethod (ec.Compiler, returnType, returnType);
2786 return IsReturnTypeNonDependent (ec, invoke, invoke.ReturnType);
2787 }
2788
2789 Type[] g_args = returnType.GetGenericArguments ();
2790
2791 // At least one unfixed return type has to exist
2792 if (AllTypesAreFixed (g_args))
2793 return false;
2794 } else {
2795 return false;
2796 }
2797
2798 // All generic input arguments have to be fixed
2799 AParametersCollection d_parameters = invoke.Parameters;
2800 return AllTypesAreFixed (d_parameters.Types);
2801 }
2802
2803 bool IsFixed (Type type)
2804 {
2805 return IsUnfixed (type) == -1;
2806 }
2807
2808 int IsUnfixed (Type type)
2809 {
2810 if (!type.IsGenericParameter)
2811 return -1;
2812
2813 //return unfixed_types[type.GenericParameterPosition] != null;
2814 for (int i = 0; i < unfixed_types.Length; ++i) {
2815 if (unfixed_types [i] == type)
2816 return i;
2817 }
2818
2819 return -1;
2820 }
2821
2822 //
2823 // 26.3.3.9 Lower-bound Inference
2824 //
2825 public int LowerBoundInference (Type u, Type v)
2826 {
2827 return LowerBoundInference (u, v, false);
2828 }
2829
2830 //
2831 // Lower-bound (false) or Upper-bound (true) inference based on inversed argument
2832 //
2833 int LowerBoundInference (Type u, Type v, bool inversed)
2834 {
2835 // If V is one of the unfixed type arguments
2836 int pos = IsUnfixed (v);
2837 if (pos != -1) {
2838 AddToBounds (new BoundInfo (u, inversed ? BoundKind.Upper : BoundKind.Lower), pos);
2839 return 1;
2840 }
2841
2842 // If U is an array type
2843 if (u.IsArray) {
2844 int u_dim = u.GetArrayRank ();
2845 Type v_i;
2846 Type u_i = TypeManager.GetElementType (u);
2847
2848 if (v.IsArray) {
2849 if (u_dim != v.GetArrayRank ())
2850 return 0;
2851
2852 v_i = TypeManager.GetElementType (v);
2853
2854 if (TypeManager.IsValueType (u_i))
2855 return ExactInference (u_i, v_i);
2856
2857 return LowerBoundInference (u_i, v_i, inversed);
2858 }
2859
2860 if (u_dim != 1)
2861 return 0;
2862
2863 if (v.IsGenericType) {
2864 Type g_v = v.GetGenericTypeDefinition ();
2865 if ((g_v != TypeManager.generic_ilist_type) && (g_v != TypeManager.generic_icollection_type) &&
2866 (g_v != TypeManager.generic_ienumerable_type))
2867 return 0;
2868
2869 v_i = TypeManager.TypeToCoreType (TypeManager.GetTypeArguments (v) [0]);
2870 if (TypeManager.IsValueType (u_i))
2871 return ExactInference (u_i, v_i);
2872
2873 return LowerBoundInference (u_i, v_i);
2874 }
2875 } else if (v.IsGenericType && !v.IsGenericTypeDefinition) {
2876 //
2877 // if V is a constructed type C<V1..Vk> and there is a unique type C<U1..Uk>
2878 // such that U is identical to, inherits from (directly or indirectly),
2879 // or implements (directly or indirectly) C<U1..Uk>
2880 //
2881 var u_candidates = new List<Type> ();
2882 if (u.IsGenericType)
2883 u_candidates.Add (u);
2884
2885 for (Type t = u.BaseType; t != null; t = t.BaseType) {
2886 if (t.IsGenericType && !t.IsGenericTypeDefinition)
2887 u_candidates.Add (t);
2888 }
2889
2890 // TODO: Implement GetGenericInterfaces only and remove
2891 // the if from foreach
2892 u_candidates.AddRange (TypeManager.GetInterfaces (u));
2893
2894 Type open_v = v.GetGenericTypeDefinition ();
2895 Type [] unique_candidate_targs = null;
2896 Type [] ga_v = v.GetGenericArguments ();
2897 foreach (Type u_candidate in u_candidates) {
2898 if (!u_candidate.IsGenericType || u_candidate.IsGenericTypeDefinition)
2899 continue;
2900
2901 if (TypeManager.DropGenericTypeArguments (u_candidate) != open_v)
2902 continue;
2903
2904 //
2905 // The unique set of types U1..Uk means that if we have an interface I<T>,
2906 // class U : I<int>, I<long> then no type inference is made when inferring
2907 // type I<T> by applying type U because T could be int or long
2908 //
2909 if (unique_candidate_targs != null) {
2910 Type[] second_unique_candidate_targs = u_candidate.GetGenericArguments ();
2911 if (TypeManager.IsEqual (unique_candidate_targs, second_unique_candidate_targs)) {
2912 unique_candidate_targs = second_unique_candidate_targs;
2913 continue;
2914 }
2915
2916 //
2917 // This should always cause type inference failure
2918 //
2919 failed = true;
2920 return 1;
2921 }
2922
2923 unique_candidate_targs = u_candidate.GetGenericArguments ();
2924 }
2925
2926 if (unique_candidate_targs != null) {
2927 Type[] ga_open_v = open_v.GetGenericArguments ();
2928 int score = 0;
2929 for (int i = 0; i < unique_candidate_targs.Length; ++i) {
2930 Variance variance = TypeManager.GetTypeParameterVariance (ga_open_v [i]);
2931
2932 Type u_i = unique_candidate_targs [i];
2933 if (variance == Variance.None || TypeManager.IsValueType (u_i)) {
2934 if (ExactInference (u_i, ga_v [i]) == 0)
2935 ++score;
2936 } else {
2937 bool upper_bound = (variance == Variance.Contravariant && !inversed) ||
2938 (variance == Variance.Covariant && inversed);
2939
2940 if (LowerBoundInference (u_i, ga_v [i], upper_bound) == 0)
2941 ++score;
2942 }
2943 }
2944 return score;
2945 }
2946 }
2947
2948 return 0;
2949 }
2950
2951 //
2952 // 26.3.3.6 Output Type Inference
2953 //
2954 public int OutputTypeInference (ResolveContext ec, Expression e, Type t)
2955 {
2956 // If e is a lambda or anonymous method with inferred return type
2957 AnonymousMethodExpression ame = e as AnonymousMethodExpression;
2958 if (ame != null) {
2959 Type rt = ame.InferReturnType (ec, this, t);
2960 var invoke = Delegate.GetInvokeMethod (ec.Compiler, t, t);
2961
2962 if (rt == null) {
2963 AParametersCollection pd = invoke.Parameters;
2964 return ame.Parameters.Count == pd.Count ? 1 : 0;
2965 }
2966
2967 Type rtype = invoke.ReturnType;
2968 #if MS_COMPATIBLE
2969 // Blablabla, because reflection does not work with dynamic types
2970 // Type [] g_args = t.GetGenericArguments ();
2971 // rtype = g_args [rtype.GenericParameterPosition];
2972 #endif
2973 return LowerBoundInference (rt, rtype) + 1;
2974 }
2975
2976 //
2977 // if E is a method group and T is a delegate type or expression tree type
2978 // return type Tb with parameter types T1..Tk and return type Tb, and overload
2979 // resolution of E with the types T1..Tk yields a single method with return type U,
2980 // then a lower-bound inference is made from U for Tb.
2981 //
2982 if (e is MethodGroupExpr) {
2983 // TODO: Or expression tree
2984 if (!TypeManager.IsDelegateType (t))
2985 return 0;
2986
2987 var invoke = Delegate.GetInvokeMethod (ec.Compiler, t, t);
2988 Type rtype = invoke.ReturnType;
2989 #if MS_COMPATIBLE
2990 // Blablabla, because reflection does not work with dynamic types
2991 // Type [] g_args = t.GetGenericArguments ();
2992 // rtype = g_args [rtype.GenericParameterPosition];
2993 #endif
2994
2995 if (!TypeManager.IsGenericType (rtype))
2996 return 0;
2997
2998 MethodGroupExpr mg = (MethodGroupExpr) e;
2999 Arguments args = DelegateCreation.CreateDelegateMethodArguments (invoke.Parameters, e.Location);
3000 mg = mg.OverloadResolve (ec, ref args, true, e.Location);
3001 if (mg == null)
3002 return 0;
3003
3004 // TODO: What should happen when return type is of generic type ?
3005 throw new NotImplementedException ();
3006 // return LowerBoundInference (null, rtype) + 1;
3007 }
3008
3009 //
3010 // if e is an expression with type U, then
3011 // a lower-bound inference is made from U for T
3012 //
3013 return LowerBoundInference (e.Type, t) * 2;
3014 }
3015
3016 void RemoveDependentTypes (List<Type> types, Type returnType)
3017 {
3018 int idx = IsUnfixed (returnType);
3019 if (idx >= 0) {
3020 types [idx] = null;
3021 return;
3022 }
3023
3024 if (returnType.IsGenericType) {
3025 foreach (Type t in returnType.GetGenericArguments ()) {
3026 RemoveDependentTypes (types, t);
3027 }
3028 }
3029 }
3030
3031 public bool UnfixedVariableExists {
3032 get {
3033 if (unfixed_types == null)
3034 return false;
3035
3036 foreach (Type ut in unfixed_types)
3037 if (ut != null)
3038 return true;
3039 return false;
3040 }
3041 }
3042 }
3043 }
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