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2009-07-28 Jb Evain <jbevain@novell.com>
[mcs.git] / mcs / generic.cs
blob427d903e410f391c8b7e9fa40871ff6a3eae8216
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;
18 using System.Text;
19 using System.Text.RegularExpressions;
20
21 namespace Mono.CSharp {
22
23 /// <summary>
24 /// Abstract base class for type parameter constraints.
25 /// The type parameter can come from a generic type definition or from reflection.
26 /// </summary>
27 public abstract class GenericConstraints {
28 public abstract string TypeParameter {
29 get;
30 }
31
32 public abstract GenericParameterAttributes Attributes {
33 get;
34 }
35
36 public bool HasConstructorConstraint {
37 get { return (Attributes & GenericParameterAttributes.DefaultConstructorConstraint) != 0; }
38 }
39
40 public bool HasReferenceTypeConstraint {
41 get { return (Attributes & GenericParameterAttributes.ReferenceTypeConstraint) != 0; }
42 }
43
44 public bool HasValueTypeConstraint {
45 get { return (Attributes & GenericParameterAttributes.NotNullableValueTypeConstraint) != 0; }
46 }
47
48 public virtual bool HasClassConstraint {
49 get { return ClassConstraint != null; }
50 }
51
52 public abstract Type ClassConstraint {
53 get;
54 }
55
56 public abstract Type[] InterfaceConstraints {
57 get;
58 }
59
60 public abstract Type EffectiveBaseClass {
61 get;
62 }
63
64 // <summary>
65 // Returns whether the type parameter is "known to be a reference type".
66 // </summary>
67 public virtual bool IsReferenceType {
68 get {
69 if (HasReferenceTypeConstraint)
70 return true;
71 if (HasValueTypeConstraint)
72 return false;
73
74 if (ClassConstraint != null) {
75 if (ClassConstraint.IsValueType)
76 return false;
77
78 if (ClassConstraint != TypeManager.object_type)
79 return true;
80 }
81
82 foreach (Type t in InterfaceConstraints) {
83 if (!t.IsGenericParameter)
84 continue;
85
86 GenericConstraints gc = TypeManager.GetTypeParameterConstraints (t);
87 if ((gc != null) && gc.IsReferenceType)
88 return true;
89 }
90
91 return false;
92 }
93 }
94
95 // <summary>
96 // Returns whether the type parameter is "known to be a value type".
97 // </summary>
98 public virtual bool IsValueType {
99 get {
100 if (HasValueTypeConstraint)
101 return true;
102 if (HasReferenceTypeConstraint)
103 return false;
104
105 if (ClassConstraint != null) {
106 if (!TypeManager.IsValueType (ClassConstraint))
107 return false;
108
109 if (ClassConstraint != TypeManager.value_type)
110 return true;
111 }
112
113 foreach (Type t in InterfaceConstraints) {
114 if (!t.IsGenericParameter)
115 continue;
116
117 GenericConstraints gc = TypeManager.GetTypeParameterConstraints (t);
118 if ((gc != null) && gc.IsValueType)
119 return true;
120 }
121
122 return false;
123 }
124 }
125 }
126
127 public class ReflectionConstraints : GenericConstraints
128 {
129 GenericParameterAttributes attrs;
130 Type base_type;
131 Type class_constraint;
132 Type[] iface_constraints;
133 string name;
134
135 public static GenericConstraints GetConstraints (Type t)
136 {
137 Type[] constraints = t.GetGenericParameterConstraints ();
138 GenericParameterAttributes attrs = t.GenericParameterAttributes;
139 if (constraints.Length == 0 && attrs == GenericParameterAttributes.None)
140 return null;
141 return new ReflectionConstraints (t.Name, constraints, attrs);
142 }
143
144 private ReflectionConstraints (string name, Type[] constraints, GenericParameterAttributes attrs)
145 {
146 this.name = name;
147 this.attrs = attrs;
148
149 if ((constraints.Length > 0) && !constraints[0].IsInterface) {
150 class_constraint = constraints[0];
151 iface_constraints = new Type[constraints.Length - 1];
152 Array.Copy (constraints, 1, iface_constraints, 0, constraints.Length - 1);
153 } else
154 iface_constraints = constraints;
155
156 if (HasValueTypeConstraint)
157 base_type = TypeManager.value_type;
158 else if (class_constraint != null)
159 base_type = class_constraint;
160 else
161 base_type = TypeManager.object_type;
162 }
163
164 public override string TypeParameter
165 {
166 get { return name; }
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 public enum SpecialConstraint
201 {
202 Constructor,
203 ReferenceType,
204 ValueType
205 }
206
207 /// <summary>
208 /// Tracks the constraints for a type parameter from a generic type definition.
209 /// </summary>
210 public class Constraints : GenericConstraints {
211 string name;
212 ArrayList constraints;
213 Location loc;
214
215 //
216 // name is the identifier, constraints is an arraylist of
217 // Expressions (with types) or `true' for the constructor constraint.
218 //
219 public Constraints (string name, ArrayList constraints,
220 Location loc)
221 {
222 this.name = name;
223 this.constraints = constraints;
224 this.loc = loc;
225 }
226
227 public override string TypeParameter {
228 get {
229 return name;
230 }
231 }
232
233 public Constraints Clone ()
234 {
235 return new Constraints (name, constraints, loc);
236 }
237
238 GenericParameterAttributes attrs;
239 TypeExpr class_constraint;
240 ArrayList iface_constraints;
241 ArrayList type_param_constraints;
242 int num_constraints;
243 Type class_constraint_type;
244 Type[] iface_constraint_types;
245 Type effective_base_type;
246 bool resolved;
247 bool resolved_types;
248
249 /// <summary>
250 /// Resolve the constraints - but only resolve things into Expression's, not
251 /// into actual types.
252 /// </summary>
253 public bool Resolve (IResolveContext ec, TypeParameter tp)
254 {
255 if (resolved)
256 return true;
257
258 iface_constraints = new ArrayList (2); // TODO: Too expensive allocation
259 type_param_constraints = new ArrayList ();
260
261 foreach (object obj in constraints) {
262 if (HasConstructorConstraint) {
263 Report.Error (401, loc,
264 "The new() constraint must be the last constraint specified");
265 return false;
266 }
267
268 if (obj is SpecialConstraint) {
269 SpecialConstraint sc = (SpecialConstraint) obj;
270
271 if (sc == SpecialConstraint.Constructor) {
272 if (!HasValueTypeConstraint) {
273 attrs |= GenericParameterAttributes.DefaultConstructorConstraint;
274 continue;
275 }
276
277 Report.Error (451, loc, "The `new()' constraint " +
278 "cannot be used with the `struct' constraint");
279 return false;
280 }
281
282 if ((num_constraints > 0) || HasReferenceTypeConstraint || HasValueTypeConstraint) {
283 Report.Error (449, loc, "The `class' or `struct' " +
284 "constraint must be the first constraint specified");
285 return false;
286 }
287
288 if (sc == SpecialConstraint.ReferenceType)
289 attrs |= GenericParameterAttributes.ReferenceTypeConstraint;
290 else
291 attrs |= GenericParameterAttributes.NotNullableValueTypeConstraint;
292 continue;
293 }
294
295 int errors = Report.Errors;
296 FullNamedExpression fn = ((Expression) obj).ResolveAsTypeStep (ec, false);
297
298 if (fn == null) {
299 if (errors != Report.Errors)
300 return false;
301
302 NamespaceEntry.Error_NamespaceNotFound (loc, ((Expression)obj).GetSignatureForError ());
303 return false;
304 }
305
306 TypeExpr expr;
307 GenericTypeExpr cexpr = fn as GenericTypeExpr;
308 if (cexpr != null) {
309 expr = cexpr.ResolveAsBaseTerminal (ec, false);
310 } else
311 expr = ((Expression) obj).ResolveAsTypeTerminal (ec, false);
312
313 if ((expr == null) || (expr.Type == null))
314 return false;
315
316 if (!ec.GenericDeclContainer.IsAccessibleAs (fn.Type)) {
317 Report.SymbolRelatedToPreviousError (fn.Type);
318 Report.Error (703, loc,
319 "Inconsistent accessibility: constraint type `{0}' is less accessible than `{1}'",
320 fn.GetSignatureForError (), ec.GenericDeclContainer.GetSignatureForError ());
321 return false;
322 }
323
324 TypeParameterExpr texpr = expr as TypeParameterExpr;
325 if (texpr != null)
326 type_param_constraints.Add (expr);
327 else if (expr.IsInterface)
328 iface_constraints.Add (expr);
329 else if (class_constraint != null || iface_constraints.Count != 0) {
330 Report.Error (406, loc,
331 "The class type constraint `{0}' must be listed before any other constraints. Consider moving type constraint to the beginning of the constraint list",
332 expr.GetSignatureForError ());
333 return false;
334 } else if (HasReferenceTypeConstraint || HasValueTypeConstraint) {
335 Report.Error (450, loc, "`{0}': cannot specify both " +
336 "a constraint class and the `class' " +
337 "or `struct' constraint", expr.GetSignatureForError ());
338 return false;
339 } else
340 class_constraint = expr;
341
342
343 //
344 // Checks whether each generic method parameter constraint type
345 // is valid with respect to T
346 //
347 if (tp != null && tp.Type.DeclaringMethod != null) {
348 TypeManager.CheckTypeVariance (expr.Type, Variance.Contravariant, ec as MemberCore);
349 }
350
351 num_constraints++;
352 }
353
354 ArrayList list = new ArrayList ();
355 foreach (TypeExpr iface_constraint in iface_constraints) {
356 foreach (Type type in list) {
357 if (!type.Equals (iface_constraint.Type))
358 continue;
359
360 Report.Error (405, loc,
361 "Duplicate constraint `{0}' for type " +
362 "parameter `{1}'.", iface_constraint.GetSignatureForError (),
363 name);
364 return false;
365 }
366
367 list.Add (iface_constraint.Type);
368 }
369
370 foreach (TypeParameterExpr expr in type_param_constraints) {
371 foreach (Type type in list) {
372 if (!type.Equals (expr.Type))
373 continue;
374
375 Report.Error (405, loc,
376 "Duplicate constraint `{0}' for type " +
377 "parameter `{1}'.", expr.GetSignatureForError (), name);
378 return false;
379 }
380
381 list.Add (expr.Type);
382 }
383
384 iface_constraint_types = new Type [list.Count];
385 list.CopyTo (iface_constraint_types, 0);
386
387 if (class_constraint != null) {
388 class_constraint_type = class_constraint.Type;
389 if (class_constraint_type == null)
390 return false;
391
392 if (class_constraint_type.IsSealed) {
393 if (class_constraint_type.IsAbstract)
394 {
395 Report.Error (717, loc, "`{0}' is not a valid constraint. Static classes cannot be used as constraints",
396 TypeManager.CSharpName (class_constraint_type));
397 }
398 else
399 {
400 Report.Error (701, loc, "`{0}' is not a valid constraint. A constraint must be an interface, " +
401 "a non-sealed class or a type parameter", TypeManager.CSharpName(class_constraint_type));
402 }
403 return false;
404 }
405
406 if ((class_constraint_type == TypeManager.array_type) ||
407 (class_constraint_type == TypeManager.delegate_type) ||
408 (class_constraint_type == TypeManager.enum_type) ||
409 (class_constraint_type == TypeManager.value_type) ||
410 (class_constraint_type == TypeManager.object_type) ||
411 class_constraint_type == TypeManager.multicast_delegate_type) {
412 Report.Error (702, loc,
413 "A constraint cannot be special class `{0}'",
414 TypeManager.CSharpName (class_constraint_type));
415 return false;
416 }
417 }
418
419 if (class_constraint_type != null)
420 effective_base_type = class_constraint_type;
421 else if (HasValueTypeConstraint)
422 effective_base_type = TypeManager.value_type;
423 else
424 effective_base_type = TypeManager.object_type;
425
426 if ((attrs & GenericParameterAttributes.NotNullableValueTypeConstraint) != 0)
427 attrs |= GenericParameterAttributes.DefaultConstructorConstraint;
428
429 resolved = true;
430 return true;
431 }
432
433 bool CheckTypeParameterConstraints (TypeParameter tparam, ref TypeExpr prevConstraint, ArrayList seen)
434 {
435 seen.Add (tparam);
436
437 Constraints constraints = tparam.Constraints;
438 if (constraints == null)
439 return true;
440
441 if (constraints.HasValueTypeConstraint) {
442 Report.Error (456, loc,
443 "Type parameter `{0}' has the `struct' constraint, so it cannot be used as a constraint for `{1}'",
444 tparam.Name, name);
445 return false;
446 }
447
448 //
449 // Checks whether there are no conflicts between type parameter constraints
450 //
451 // class Foo<T, U>
452 // where T : A
453 // where U : A, B // A and B are not convertible
454 //
455 if (constraints.HasClassConstraint) {
456 if (prevConstraint != null) {
457 Type t2 = constraints.ClassConstraint;
458 TypeExpr e2 = constraints.class_constraint;
459
460 if (!Convert.ImplicitReferenceConversionExists (prevConstraint, t2) &&
461 !Convert.ImplicitReferenceConversionExists (e2, prevConstraint.Type)) {
462 Report.Error (455, loc,
463 "Type parameter `{0}' inherits conflicting constraints `{1}' and `{2}'",
464 name, TypeManager.CSharpName (prevConstraint.Type), TypeManager.CSharpName (t2));
465 return false;
466 }
467 }
468
469 prevConstraint = constraints.class_constraint;
470 }
471
472 if (constraints.type_param_constraints == null)
473 return true;
474
475 foreach (TypeParameterExpr expr in constraints.type_param_constraints) {
476 if (seen.Contains (expr.TypeParameter)) {
477 Report.Error (454, loc, "Circular constraint " +
478 "dependency involving `{0}' and `{1}'",
479 tparam.Name, expr.GetSignatureForError ());
480 return false;
481 }
482
483 if (!CheckTypeParameterConstraints (expr.TypeParameter, ref prevConstraint, seen))
484 return false;
485 }
486
487 return true;
488 }
489
490 /// <summary>
491 /// Resolve the constraints into actual types.
492 /// </summary>
493 public bool ResolveTypes (IResolveContext ec)
494 {
495 if (resolved_types)
496 return true;
497
498 resolved_types = true;
499
500 foreach (object obj in constraints) {
501 GenericTypeExpr cexpr = obj as GenericTypeExpr;
502 if (cexpr == null)
503 continue;
504
505 if (!cexpr.CheckConstraints (ec))
506 return false;
507 }
508
509 if (type_param_constraints.Count != 0) {
510 ArrayList seen = new ArrayList ();
511 TypeExpr prev_constraint = class_constraint;
512 foreach (TypeParameterExpr expr in type_param_constraints) {
513 if (!CheckTypeParameterConstraints (expr.TypeParameter, ref prev_constraint, seen))
514 return false;
515 seen.Clear ();
516 }
517 }
518
519 for (int i = 0; i < iface_constraints.Count; ++i) {
520 TypeExpr iface_constraint = (TypeExpr) iface_constraints [i];
521 iface_constraint = iface_constraint.ResolveAsTypeTerminal (ec, false);
522 if (iface_constraint == null)
523 return false;
524 iface_constraints [i] = iface_constraint;
525 }
526
527 if (class_constraint != null) {
528 class_constraint = class_constraint.ResolveAsTypeTerminal (ec, false);
529 if (class_constraint == null)
530 return false;
531 }
532
533 return true;
534 }
535
536 public override GenericParameterAttributes Attributes {
537 get { return attrs; }
538 }
539
540 public override bool HasClassConstraint {
541 get { return class_constraint != null; }
542 }
543
544 public override Type ClassConstraint {
545 get { return class_constraint_type; }
546 }
547
548 public override Type[] InterfaceConstraints {
549 get { return iface_constraint_types; }
550 }
551
552 public override Type EffectiveBaseClass {
553 get { return effective_base_type; }
554 }
555
556 public bool IsSubclassOf (Type t)
557 {
558 if ((class_constraint_type != null) &&
559 class_constraint_type.IsSubclassOf (t))
560 return true;
561
562 if (iface_constraint_types == null)
563 return false;
564
565 foreach (Type iface in iface_constraint_types) {
566 if (TypeManager.IsSubclassOf (iface, t))
567 return true;
568 }
569
570 return false;
571 }
572
573 public Location Location {
574 get {
575 return loc;
576 }
577 }
578
579 /// <summary>
580 /// This is used when we're implementing a generic interface method.
581 /// Each method type parameter in implementing method must have the same
582 /// constraints than the corresponding type parameter in the interface
583 /// method. To do that, we're called on each of the implementing method's
584 /// type parameters.
585 /// </summary>
586 public bool AreEqual (GenericConstraints gc)
587 {
588 if (gc.Attributes != attrs)
589 return false;
590
591 if (HasClassConstraint != gc.HasClassConstraint)
592 return false;
593 if (HasClassConstraint && !TypeManager.IsEqual (gc.ClassConstraint, ClassConstraint))
594 return false;
595
596 int gc_icount = gc.InterfaceConstraints != null ?
597 gc.InterfaceConstraints.Length : 0;
598 int icount = InterfaceConstraints != null ?
599 InterfaceConstraints.Length : 0;
600
601 if (gc_icount != icount)
602 return false;
603
604 for (int i = 0; i < gc.InterfaceConstraints.Length; ++i) {
605 Type iface = gc.InterfaceConstraints [i];
606 if (iface.IsGenericType)
607 iface = iface.GetGenericTypeDefinition ();
608
609 bool ok = false;
610 for (int ii = 0; i < InterfaceConstraints.Length; ++ii) {
611 Type check = InterfaceConstraints [ii];
612 if (check.IsGenericType)
613 check = check.GetGenericTypeDefinition ();
614
615 if (TypeManager.IsEqual (iface, check)) {
616 ok = true;
617 break;
618 }
619 }
620
621 if (!ok)
622 return false;
623 }
624
625 return true;
626 }
627
628 public void VerifyClsCompliance ()
629 {
630 if (class_constraint_type != null && !AttributeTester.IsClsCompliant (class_constraint_type))
631 Warning_ConstrainIsNotClsCompliant (class_constraint_type, class_constraint.Location);
632
633 if (iface_constraint_types != null) {
634 for (int i = 0; i < iface_constraint_types.Length; ++i) {
635 if (!AttributeTester.IsClsCompliant (iface_constraint_types [i]))
636 Warning_ConstrainIsNotClsCompliant (iface_constraint_types [i],
637 ((TypeExpr)iface_constraints [i]).Location);
638 }
639 }
640 }
641
642 void Warning_ConstrainIsNotClsCompliant (Type t, Location loc)
643 {
644 Report.SymbolRelatedToPreviousError (t);
645 Report.Warning (3024, 1, loc, "Constraint type `{0}' is not CLS-compliant",
646 TypeManager.CSharpName (t));
647 }
648 }
649
650 /// <summary>
651 /// A type parameter from a generic type definition.
652 /// </summary>
653 public class TypeParameter : MemberCore, IMemberContainer
654 {
655 static readonly string[] attribute_target = new string [] { "type parameter" };
656
657 DeclSpace decl;
658 GenericConstraints gc;
659 Constraints constraints;
660 GenericTypeParameterBuilder type;
661 MemberCache member_cache;
662 Variance variance;
663
664 public TypeParameter (DeclSpace parent, DeclSpace decl, string name,
665 Constraints constraints, Attributes attrs, Variance variance, Location loc)
666 : base (parent, new MemberName (name, loc), attrs)
667 {
668 this.decl = decl;
669 this.constraints = constraints;
670 this.variance = variance;
671 }
672
673 public GenericConstraints GenericConstraints {
674 get { return gc != null ? gc : constraints; }
675 }
676
677 public Constraints Constraints {
678 get { return constraints; }
679 }
680
681 public DeclSpace DeclSpace {
682 get { return decl; }
683 }
684
685 public Variance Variance {
686 get { return variance; }
687 }
688
689 public Type Type {
690 get { return type; }
691 }
692
693 /// <summary>
694 /// This is the first method which is called during the resolving
695 /// process; we're called immediately after creating the type parameters
696 /// with SRE (by calling `DefineGenericParameters()' on the TypeBuilder /
697 /// MethodBuilder).
698 ///
699 /// We're either called from TypeContainer.DefineType() or from
700 /// GenericMethod.Define() (called from Method.Define()).
701 /// </summary>
702 public void Define (GenericTypeParameterBuilder type)
703 {
704 if (this.type != null)
705 throw new InvalidOperationException ();
706
707 this.type = type;
708 TypeManager.AddTypeParameter (type, this);
709 }
710
711 public void ErrorInvalidVariance (MemberCore mc, Variance expected)
712 {
713 Report.SymbolRelatedToPreviousError (mc);
714 string input_variance = Variance == Variance.Contravariant ? "contravariant" : "covariant";
715 string gtype_variance;
716 switch (expected) {
717 case Variance.Contravariant: gtype_variance = "contravariantly"; break;
718 case Variance.Covariant: gtype_variance = "covariantly"; break;
719 default: gtype_variance = "invariantly"; break;
720 }
721
722 Delegate d = mc as Delegate;
723 string parameters = d != null ? d.Parameters.GetSignatureForError () : "";
724
725 Report.Error (1961, Location,
726 "The {2} type parameter `{0}' must be {3} valid on `{1}{4}'",
727 GetSignatureForError (), mc.GetSignatureForError (), input_variance, gtype_variance, parameters);
728 }
729
730 /// <summary>
731 /// This is the second method which is called during the resolving
732 /// process - in case of class type parameters, we're called from
733 /// TypeContainer.ResolveType() - after it resolved the class'es
734 /// base class and interfaces. For method type parameters, we're
735 /// called immediately after Define().
736 ///
737 /// We're just resolving the constraints into expressions here, we
738 /// don't resolve them into actual types.
739 ///
740 /// Note that in the special case of partial generic classes, we may be
741 /// called _before_ Define() and we may also be called multiple types.
742 /// </summary>
743 public bool Resolve (DeclSpace ds)
744 {
745 if (constraints != null) {
746 if (!constraints.Resolve (ds, this)) {
747 constraints = null;
748 return false;
749 }
750 }
751
752 return true;
753 }
754
755 /// <summary>
756 /// This is the third method which is called during the resolving
757 /// process. We're called immediately after calling DefineConstraints()
758 /// on all of the current class'es type parameters.
759 ///
760 /// Our job is to resolve the constraints to actual types.
761 ///
762 /// Note that we may have circular dependencies on type parameters - this
763 /// is why Resolve() and ResolveType() are separate.
764 /// </summary>
765 public bool ResolveType (IResolveContext ec)
766 {
767 if (constraints != null) {
768 if (!constraints.ResolveTypes (ec)) {
769 constraints = null;
770 return false;
771 }
772 }
773
774 return true;
775 }
776
777 /// <summary>
778 /// This is the fourth and last method which is called during the resolving
779 /// process. We're called after everything is fully resolved and actually
780 /// register the constraints with SRE and the TypeManager.
781 /// </summary>
782 public bool DefineType (IResolveContext ec)
783 {
784 return DefineType (ec, null, null, false);
785 }
786
787 /// <summary>
788 /// This is the fith and last method which is called during the resolving
789 /// process. We're called after everything is fully resolved and actually
790 /// register the constraints with SRE and the TypeManager.
791 ///
792 /// The `builder', `implementing' and `is_override' arguments are only
793 /// applicable to method type parameters.
794 /// </summary>
795 public bool DefineType (IResolveContext ec, MethodBuilder builder,
796 MethodInfo implementing, bool is_override)
797 {
798 if (!ResolveType (ec))
799 return false;
800
801 if (implementing != null) {
802 if (is_override && (constraints != null)) {
803 Report.Error (460, Location,
804 "`{0}': Cannot specify constraints for overrides or explicit interface implementation methods",
805 TypeManager.CSharpSignature (builder));
806 return false;
807 }
808
809 MethodBase mb = TypeManager.DropGenericMethodArguments (implementing);
810
811 int pos = type.GenericParameterPosition;
812 Type mparam = mb.GetGenericArguments () [pos];
813 GenericConstraints temp_gc = ReflectionConstraints.GetConstraints (mparam);
814
815 if (temp_gc != null)
816 gc = new InflatedConstraints (temp_gc, implementing.DeclaringType);
817 else if (constraints != null)
818 gc = new InflatedConstraints (constraints, implementing.DeclaringType);
819
820 bool ok = true;
821 if (constraints != null) {
822 if (temp_gc == null)
823 ok = false;
824 else if (!constraints.AreEqual (gc))
825 ok = false;
826 } else {
827 if (!is_override && (temp_gc != null))
828 ok = false;
829 }
830
831 if (!ok) {
832 Report.SymbolRelatedToPreviousError (implementing);
833
834 Report.Error (
835 425, Location, "The constraints for type " +
836 "parameter `{0}' of method `{1}' must match " +
837 "the constraints for type parameter `{2}' " +
838 "of interface method `{3}'. Consider using " +
839 "an explicit interface implementation instead",
840 Name, TypeManager.CSharpSignature (builder),
841 TypeManager.CSharpName (mparam), TypeManager.CSharpSignature (mb));
842 return false;
843 }
844 } else if (DeclSpace is CompilerGeneratedClass) {
845 TypeParameter[] tparams = DeclSpace.TypeParameters;
846 Type[] types = new Type [tparams.Length];
847 for (int i = 0; i < tparams.Length; i++)
848 types [i] = tparams [i].Type;
849
850 if (constraints != null)
851 gc = new InflatedConstraints (constraints, types);
852 } else {
853 gc = (GenericConstraints) constraints;
854 }
855
856 SetConstraints (type);
857 return true;
858 }
859
860 public void SetConstraints (GenericTypeParameterBuilder type)
861 {
862 GenericParameterAttributes attr = GenericParameterAttributes.None;
863 if (variance == Variance.Contravariant)
864 attr |= GenericParameterAttributes.Contravariant;
865 else if (variance == Variance.Covariant)
866 attr |= GenericParameterAttributes.Covariant;
867
868 if (gc != null) {
869 if (gc.HasClassConstraint || gc.HasValueTypeConstraint)
870 type.SetBaseTypeConstraint (gc.EffectiveBaseClass);
871
872 attr |= gc.Attributes;
873 type.SetInterfaceConstraints (gc.InterfaceConstraints);
874 TypeManager.RegisterBuilder (type, gc.InterfaceConstraints);
875 }
876
877 type.SetGenericParameterAttributes (attr);
878 }
879
880 /// <summary>
881 /// This is called for each part of a partial generic type definition.
882 ///
883 /// If `new_constraints' is not null and we don't already have constraints,
884 /// they become our constraints. If we already have constraints, we must
885 /// check that they're the same.
886 /// con
887 /// </summary>
888 public bool UpdateConstraints (IResolveContext ec, Constraints new_constraints)
889 {
890 if (type == null)
891 throw new InvalidOperationException ();
892
893 if (new_constraints == null)
894 return true;
895
896 if (!new_constraints.Resolve (ec, this))
897 return false;
898 if (!new_constraints.ResolveTypes (ec))
899 return false;
900
901 if (constraints != null)
902 return constraints.AreEqual (new_constraints);
903
904 constraints = new_constraints;
905 return true;
906 }
907
908 public override void Emit ()
909 {
910 if (OptAttributes != null)
911 OptAttributes.Emit ();
912
913 base.Emit ();
914 }
915
916 public override string DocCommentHeader {
917 get {
918 throw new InvalidOperationException (
919 "Unexpected attempt to get doc comment from " + this.GetType () + ".");
920 }
921 }
922
923 //
924 // MemberContainer
925 //
926
927 public override bool Define ()
928 {
929 return true;
930 }
931
932 public override void ApplyAttributeBuilder (Attribute a, CustomAttributeBuilder cb, PredefinedAttributes pa)
933 {
934 type.SetCustomAttribute (cb);
935 }
936
937 public override AttributeTargets AttributeTargets {
938 get {
939 return AttributeTargets.GenericParameter;
940 }
941 }
942
943 public override string[] ValidAttributeTargets {
944 get {
945 return attribute_target;
946 }
947 }
948
949 //
950 // IMemberContainer
951 //
952
953 string IMemberContainer.Name {
954 get { return Name; }
955 }
956
957 MemberCache IMemberContainer.BaseCache {
958 get {
959 if (gc == null)
960 return null;
961
962 if (gc.EffectiveBaseClass.BaseType == null)
963 return null;
964
965 return TypeManager.LookupMemberCache (gc.EffectiveBaseClass.BaseType);
966 }
967 }
968
969 bool IMemberContainer.IsInterface {
970 get { return false; }
971 }
972
973 MemberList IMemberContainer.GetMembers (MemberTypes mt, BindingFlags bf)
974 {
975 throw new NotSupportedException ();
976 }
977
978 public MemberCache MemberCache {
979 get {
980 if (member_cache != null)
981 return member_cache;
982
983 if (gc == null)
984 return null;
985
986 Type[] ifaces = TypeManager.ExpandInterfaces (gc.InterfaceConstraints);
987 member_cache = new MemberCache (this, gc.EffectiveBaseClass, ifaces);
988
989 return member_cache;
990 }
991 }
992
993 public MemberList FindMembers (MemberTypes mt, BindingFlags bf,
994 MemberFilter filter, object criteria)
995 {
996 if (gc == null)
997 return MemberList.Empty;
998
999 ArrayList members = new ArrayList ();
1000
1001 if (gc.HasClassConstraint) {
1002 MemberList list = TypeManager.FindMembers (
1003 gc.ClassConstraint, mt, bf, filter, criteria);
1004
1005 members.AddRange (list);
1006 }
1007
1008 Type[] ifaces = TypeManager.ExpandInterfaces (gc.InterfaceConstraints);
1009 foreach (Type t in ifaces) {
1010 MemberList list = TypeManager.FindMembers (
1011 t, mt, bf, filter, criteria);
1012
1013 members.AddRange (list);
1014 }
1015
1016 return new MemberList (members);
1017 }
1018
1019 public bool IsSubclassOf (Type t)
1020 {
1021 if (type.Equals (t))
1022 return true;
1023
1024 if (constraints != null)
1025 return constraints.IsSubclassOf (t);
1026
1027 return false;
1028 }
1029
1030 public void InflateConstraints (Type declaring)
1031 {
1032 if (constraints != null)
1033 gc = new InflatedConstraints (constraints, declaring);
1034 }
1035
1036 public override bool IsClsComplianceRequired ()
1037 {
1038 return false;
1039 }
1040
1041 protected class InflatedConstraints : GenericConstraints
1042 {
1043 GenericConstraints gc;
1044 Type base_type;
1045 Type class_constraint;
1046 Type[] iface_constraints;
1047 Type[] dargs;
1048
1049 public InflatedConstraints (GenericConstraints gc, Type declaring)
1050 : this (gc, TypeManager.GetTypeArguments (declaring))
1051 { }
1052
1053 public InflatedConstraints (GenericConstraints gc, Type[] dargs)
1054 {
1055 this.gc = gc;
1056 this.dargs = dargs;
1057
1058 ArrayList list = new ArrayList ();
1059 if (gc.HasClassConstraint)
1060 list.Add (inflate (gc.ClassConstraint));
1061 foreach (Type iface in gc.InterfaceConstraints)
1062 list.Add (inflate (iface));
1063
1064 bool has_class_constr = false;
1065 if (list.Count > 0) {
1066 Type first = (Type) list [0];
1067 has_class_constr = !first.IsGenericParameter && !first.IsInterface;
1068 }
1069
1070 if ((list.Count > 0) && has_class_constr) {
1071 class_constraint = (Type) list [0];
1072 iface_constraints = new Type [list.Count - 1];
1073 list.CopyTo (1, iface_constraints, 0, list.Count - 1);
1074 } else {
1075 iface_constraints = new Type [list.Count];
1076 list.CopyTo (iface_constraints, 0);
1077 }
1078
1079 if (HasValueTypeConstraint)
1080 base_type = TypeManager.value_type;
1081 else if (class_constraint != null)
1082 base_type = class_constraint;
1083 else
1084 base_type = TypeManager.object_type;
1085 }
1086
1087 Type inflate (Type t)
1088 {
1089 if (t == null)
1090 return null;
1091 if (t.IsGenericParameter)
1092 return t.GenericParameterPosition < dargs.Length ? dargs [t.GenericParameterPosition] : t;
1093 if (t.IsGenericType) {
1094 Type[] args = t.GetGenericArguments ();
1095 Type[] inflated = new Type [args.Length];
1096
1097 for (int i = 0; i < args.Length; i++)
1098 inflated [i] = inflate (args [i]);
1099
1100 t = t.GetGenericTypeDefinition ();
1101 t = t.MakeGenericType (inflated);
1102 }
1103
1104 return t;
1105 }
1106
1107 public override string TypeParameter {
1108 get { return gc.TypeParameter; }
1109 }
1110
1111 public override GenericParameterAttributes Attributes {
1112 get { return gc.Attributes; }
1113 }
1114
1115 public override Type ClassConstraint {
1116 get { return class_constraint; }
1117 }
1118
1119 public override Type EffectiveBaseClass {
1120 get { return base_type; }
1121 }
1122
1123 public override Type[] InterfaceConstraints {
1124 get { return iface_constraints; }
1125 }
1126 }
1127 }
1128
1129 /// <summary>
1130 /// A TypeExpr which already resolved to a type parameter.
1131 /// </summary>
1132 public class TypeParameterExpr : TypeExpr {
1133 TypeParameter type_parameter;
1134
1135 public TypeParameter TypeParameter {
1136 get {
1137 return type_parameter;
1138 }
1139 }
1140
1141 public TypeParameterExpr (TypeParameter type_parameter, Location loc)
1142 {
1143 this.type_parameter = type_parameter;
1144 this.loc = loc;
1145 }
1146
1147 protected override TypeExpr DoResolveAsTypeStep (IResolveContext ec)
1148 {
1149 throw new NotSupportedException ();
1150 }
1151
1152 public override FullNamedExpression ResolveAsTypeStep (IResolveContext ec, bool silent)
1153 {
1154 type = type_parameter.Type;
1155 eclass = ExprClass.TypeParameter;
1156 return this;
1157 }
1158
1159 public override bool IsInterface {
1160 get { return false; }
1161 }
1162
1163 public override bool CheckAccessLevel (DeclSpace ds)
1164 {
1165 return true;
1166 }
1167 }
1168
1169 //
1170 // Tracks the type arguments when instantiating a generic type. It's used
1171 // by both type arguments and type parameters
1172 //
1173 public class TypeArguments {
1174 ArrayList args;
1175 Type[] atypes;
1176
1177 public TypeArguments ()
1178 {
1179 args = new ArrayList ();
1180 }
1181
1182 public TypeArguments (params FullNamedExpression[] types)
1183 {
1184 this.args = new ArrayList (types);
1185 }
1186
1187 public void Add (FullNamedExpression type)
1188 {
1189 args.Add (type);
1190 }
1191
1192 public void Add (TypeArguments new_args)
1193 {
1194 args.AddRange (new_args.args);
1195 }
1196
1197 // TODO: Should be deleted
1198 public TypeParameterName[] GetDeclarations ()
1199 {
1200 return (TypeParameterName[]) args.ToArray (typeof (TypeParameterName));
1201 }
1202
1203 /// <summary>
1204 /// We may only be used after Resolve() is called and return the fully
1205 /// resolved types.
1206 /// </summary>
1207 public Type[] Arguments {
1208 get {
1209 return atypes;
1210 }
1211 }
1212
1213 public int Count {
1214 get {
1215 return args.Count;
1216 }
1217 }
1218
1219 public string GetSignatureForError()
1220 {
1221 StringBuilder sb = new StringBuilder();
1222 for (int i = 0; i < Count; ++i)
1223 {
1224 Expression expr = (Expression)args [i];
1225 sb.Append(expr.GetSignatureForError());
1226 if (i + 1 < Count)
1227 sb.Append(',');
1228 }
1229 return sb.ToString();
1230 }
1231
1232 /// <summary>
1233 /// Resolve the type arguments.
1234 /// </summary>
1235 public bool Resolve (IResolveContext ec)
1236 {
1237 if (atypes != null)
1238 return atypes.Length != 0;
1239
1240 int count = args.Count;
1241 bool ok = true;
1242
1243 atypes = new Type [count];
1244
1245 for (int i = 0; i < count; i++){
1246 TypeExpr te = ((FullNamedExpression) args[i]).ResolveAsTypeTerminal (ec, false);
1247 if (te == null) {
1248 ok = false;
1249 continue;
1250 }
1251
1252 atypes[i] = te.Type;
1253
1254 if (te.Type.IsSealed && te.Type.IsAbstract) {
1255 Report.Error (718, te.Location, "`{0}': static classes cannot be used as generic arguments",
1256 te.GetSignatureForError ());
1257 ok = false;
1258 }
1259
1260 if (te.Type.IsPointer || TypeManager.IsSpecialType (te.Type)) {
1261 Report.Error (306, te.Location,
1262 "The type `{0}' may not be used as a type argument",
1263 te.GetSignatureForError ());
1264 ok = false;
1265 }
1266 }
1267
1268 if (!ok)
1269 atypes = Type.EmptyTypes;
1270
1271 return ok;
1272 }
1273
1274 public TypeArguments Clone ()
1275 {
1276 TypeArguments copy = new TypeArguments ();
1277 foreach (Expression ta in args)
1278 copy.args.Add (ta);
1279
1280 return copy;
1281 }
1282 }
1283
1284 public class TypeParameterName : SimpleName
1285 {
1286 Attributes attributes;
1287 Variance variance;
1288
1289 public TypeParameterName (string name, Attributes attrs, Location loc)
1290 : this (name, attrs, Variance.None, loc)
1291 {
1292 }
1293
1294 public TypeParameterName (string name, Attributes attrs, Variance variance, Location loc)
1295 : base (name, loc)
1296 {
1297 attributes = attrs;
1298 this.variance = variance;
1299 }
1300
1301 public Attributes OptAttributes {
1302 get {
1303 return attributes;
1304 }
1305 }
1306
1307 public Variance Variance {
1308 get {
1309 return variance;
1310 }
1311 }
1312 }
1313
1314 /// <summary>
1315 /// A reference expression to generic type
1316 /// </summary>
1317 class GenericTypeExpr : TypeExpr
1318 {
1319 TypeArguments args;
1320 Type[] gen_params; // TODO: Waiting for constrains check cleanup
1321 Type open_type;
1322
1323 //
1324 // Should be carefully used only with defined generic containers. Type parameters
1325 // can be used as type arguments in this case.
1326 //
1327 // TODO: This could be GenericTypeExpr specialization
1328 //
1329 public GenericTypeExpr (DeclSpace gType, Location l)
1330 {
1331 open_type = gType.TypeBuilder.GetGenericTypeDefinition ();
1332
1333 args = new TypeArguments ();
1334 foreach (TypeParameter type_param in gType.TypeParameters)
1335 args.Add (new TypeParameterExpr (type_param, l));
1336
1337 this.loc = l;
1338 }
1339
1340 /// <summary>
1341 /// Instantiate the generic type `t' with the type arguments `args'.
1342 /// Use this constructor if you already know the fully resolved
1343 /// generic type.
1344 /// </summary>
1345 public GenericTypeExpr (Type t, TypeArguments args, Location l)
1346 {
1347 open_type = t.GetGenericTypeDefinition ();
1348
1349 loc = l;
1350 this.args = args;
1351 }
1352
1353 public TypeArguments TypeArguments {
1354 get { return args; }
1355 }
1356
1357 public override string GetSignatureForError ()
1358 {
1359 return TypeManager.CSharpName (type);
1360 }
1361
1362 protected override TypeExpr DoResolveAsTypeStep (IResolveContext ec)
1363 {
1364 if (eclass != ExprClass.Invalid)
1365 return this;
1366
1367 eclass = ExprClass.Type;
1368
1369 if (!args.Resolve (ec))
1370 return null;
1371
1372 gen_params = open_type.GetGenericArguments ();
1373 Type[] atypes = args.Arguments;
1374
1375 if (atypes.Length != gen_params.Length) {
1376 Namespace.Error_InvalidNumberOfTypeArguments (open_type, loc);
1377 return null;
1378 }
1379
1380 //
1381 // Now bind the parameters
1382 //
1383 type = open_type.MakeGenericType (atypes);
1384 return this;
1385 }
1386
1387 /// <summary>
1388 /// Check the constraints; we're called from ResolveAsTypeTerminal()
1389 /// after fully resolving the constructed type.
1390 /// </summary>
1391 public bool CheckConstraints (IResolveContext ec)
1392 {
1393 return ConstraintChecker.CheckConstraints (ec, open_type, gen_params, args.Arguments, loc);
1394 }
1395
1396 public override bool CheckAccessLevel (DeclSpace ds)
1397 {
1398 return ds.CheckAccessLevel (open_type);
1399 }
1400
1401 public override bool IsClass {
1402 get { return open_type.IsClass; }
1403 }
1404
1405 public override bool IsValueType {
1406 get { return TypeManager.IsStruct (open_type); }
1407 }
1408
1409 public override bool IsInterface {
1410 get { return open_type.IsInterface; }
1411 }
1412
1413 public override bool IsSealed {
1414 get { return open_type.IsSealed; }
1415 }
1416
1417 public override bool Equals (object obj)
1418 {
1419 GenericTypeExpr cobj = obj as GenericTypeExpr;
1420 if (cobj == null)
1421 return false;
1422
1423 if ((type == null) || (cobj.type == null))
1424 return false;
1425
1426 return type == cobj.type;
1427 }
1428
1429 public override int GetHashCode ()
1430 {
1431 return base.GetHashCode ();
1432 }
1433 }
1434
1435 public abstract class ConstraintChecker
1436 {
1437 protected readonly Type[] gen_params;
1438 protected readonly Type[] atypes;
1439 protected readonly Location loc;
1440
1441 protected ConstraintChecker (Type[] gen_params, Type[] atypes, Location loc)
1442 {
1443 this.gen_params = gen_params;
1444 this.atypes = atypes;
1445 this.loc = loc;
1446 }
1447
1448 /// <summary>
1449 /// Check the constraints; we're called from ResolveAsTypeTerminal()
1450 /// after fully resolving the constructed type.
1451 /// </summary>
1452 public bool CheckConstraints (IResolveContext ec)
1453 {
1454 for (int i = 0; i < gen_params.Length; i++) {
1455 if (!CheckConstraints (ec, i))
1456 return false;
1457 }
1458
1459 return true;
1460 }
1461
1462 protected bool CheckConstraints (IResolveContext ec, int index)
1463 {
1464 Type atype = atypes [index];
1465 Type ptype = gen_params [index];
1466
1467 if (atype == ptype)
1468 return true;
1469
1470 Expression aexpr = new EmptyExpression (atype);
1471
1472 GenericConstraints gc = TypeManager.GetTypeParameterConstraints (ptype);
1473 if (gc == null)
1474 return true;
1475
1476 bool is_class, is_struct;
1477 if (atype.IsGenericParameter) {
1478 GenericConstraints agc = TypeManager.GetTypeParameterConstraints (atype);
1479 if (agc != null) {
1480 if (agc is Constraints)
1481 ((Constraints) agc).Resolve (ec, null);
1482 is_class = agc.IsReferenceType;
1483 is_struct = agc.IsValueType;
1484 } else {
1485 is_class = is_struct = false;
1486 }
1487 } else {
1488 is_class = TypeManager.IsReferenceType (atype);
1489 is_struct = TypeManager.IsValueType (atype) && !TypeManager.IsNullableType (atype);
1490 }
1491
1492 //
1493 // First, check the `class' and `struct' constraints.
1494 //
1495 if (gc.HasReferenceTypeConstraint && !is_class) {
1496 Report.Error (452, loc, "The type `{0}' must be " +
1497 "a reference type in order to use it " +
1498 "as type parameter `{1}' in the " +
1499 "generic type or method `{2}'.",
1500 TypeManager.CSharpName (atype),
1501 TypeManager.CSharpName (ptype),
1502 GetSignatureForError ());
1503 return false;
1504 } else if (gc.HasValueTypeConstraint && !is_struct) {
1505 Report.Error (453, loc, "The type `{0}' must be a " +
1506 "non-nullable value type in order to use it " +
1507 "as type parameter `{1}' in the " +
1508 "generic type or method `{2}'.",
1509 TypeManager.CSharpName (atype),
1510 TypeManager.CSharpName (ptype),
1511 GetSignatureForError ());
1512 return false;
1513 }
1514
1515 //
1516 // The class constraint comes next.
1517 //
1518 if (gc.HasClassConstraint) {
1519 if (!CheckConstraint (ec, ptype, aexpr, gc.ClassConstraint))
1520 return false;
1521 }
1522
1523 //
1524 // Now, check the interface constraints.
1525 //
1526 if (gc.InterfaceConstraints != null) {
1527 foreach (Type it in gc.InterfaceConstraints) {
1528 if (!CheckConstraint (ec, ptype, aexpr, it))
1529 return false;
1530 }
1531 }
1532
1533 //
1534 // Finally, check the constructor constraint.
1535 //
1536
1537 if (!gc.HasConstructorConstraint)
1538 return true;
1539
1540 if (TypeManager.IsBuiltinType (atype) || TypeManager.IsValueType (atype))
1541 return true;
1542
1543 if (HasDefaultConstructor (atype))
1544 return true;
1545
1546 Report_SymbolRelatedToPreviousError ();
1547 Report.SymbolRelatedToPreviousError (atype);
1548 Report.Error (310, loc, "The type `{0}' must have a public " +
1549 "parameterless constructor in order to use it " +
1550 "as parameter `{1}' in the generic type or " +
1551 "method `{2}'",
1552 TypeManager.CSharpName (atype),
1553 TypeManager.CSharpName (ptype),
1554 GetSignatureForError ());
1555 return false;
1556 }
1557
1558 protected bool CheckConstraint (IResolveContext ec, Type ptype, Expression expr,
1559 Type ctype)
1560 {
1561 if (TypeManager.HasGenericArguments (ctype)) {
1562 Type[] types = TypeManager.GetTypeArguments (ctype);
1563
1564 TypeArguments new_args = new TypeArguments ();
1565
1566 for (int i = 0; i < types.Length; i++) {
1567 Type t = types [i];
1568
1569 if (t.IsGenericParameter) {
1570 int pos = t.GenericParameterPosition;
1571 t = atypes [pos];
1572 }
1573 new_args.Add (new TypeExpression (t, loc));
1574 }
1575
1576 TypeExpr ct = new GenericTypeExpr (ctype, new_args, loc);
1577 if (ct.ResolveAsTypeStep (ec, false) == null)
1578 return false;
1579 ctype = ct.Type;
1580 } else if (ctype.IsGenericParameter) {
1581 int pos = ctype.GenericParameterPosition;
1582 if (ctype.DeclaringMethod == null) {
1583 // FIXME: Implement
1584 return true;
1585 } else {
1586 ctype = atypes [pos];
1587 }
1588 }
1589
1590 if (Convert.ImplicitStandardConversionExists (expr, ctype))
1591 return true;
1592
1593 Report_SymbolRelatedToPreviousError ();
1594 Report.SymbolRelatedToPreviousError (expr.Type);
1595
1596 if (TypeManager.IsNullableType (expr.Type) && ctype.IsInterface) {
1597 Report.Error (313, loc,
1598 "The type `{0}' cannot be used as type parameter `{1}' in the generic type or method `{2}'. " +
1599 "The nullable type `{0}' never satisfies interface constraint of type `{3}'",
1600 TypeManager.CSharpName (expr.Type), TypeManager.CSharpName (ptype),
1601 GetSignatureForError (), TypeManager.CSharpName (ctype));
1602 } else {
1603 Report.Error (309, loc,
1604 "The type `{0}' must be convertible to `{1}' in order to " +
1605 "use it as parameter `{2}' in the generic type or method `{3}'",
1606 TypeManager.CSharpName (expr.Type), TypeManager.CSharpName (ctype),
1607 TypeManager.CSharpName (ptype), GetSignatureForError ());
1608 }
1609 return false;
1610 }
1611
1612 static bool HasDefaultConstructor (Type atype)
1613 {
1614 TypeParameter tparam = TypeManager.LookupTypeParameter (atype);
1615 if (tparam != null) {
1616 if (tparam.GenericConstraints == null)
1617 return false;
1618
1619 return tparam.GenericConstraints.HasConstructorConstraint ||
1620 tparam.GenericConstraints.HasValueTypeConstraint;
1621 }
1622
1623 if (atype.IsAbstract)
1624 return false;
1625
1626 again:
1627 atype = TypeManager.DropGenericTypeArguments (atype);
1628 if (atype is TypeBuilder) {
1629 TypeContainer tc = TypeManager.LookupTypeContainer (atype);
1630 if (tc.InstanceConstructors == null) {
1631 atype = atype.BaseType;
1632 goto again;
1633 }
1634
1635 foreach (Constructor c in tc.InstanceConstructors) {
1636 if ((c.ModFlags & Modifiers.PUBLIC) == 0)
1637 continue;
1638 if ((c.Parameters.FixedParameters != null) &&
1639 (c.Parameters.FixedParameters.Length != 0))
1640 continue;
1641 if (c.Parameters.HasArglist || c.Parameters.HasParams)
1642 continue;
1643
1644 return true;
1645 }
1646 }
1647
1648 MemberInfo [] list = TypeManager.MemberLookup (null, null, atype, MemberTypes.Constructor,
1649 BindingFlags.Public | BindingFlags.Instance | BindingFlags.DeclaredOnly,
1650 ConstructorInfo.ConstructorName, null);
1651
1652 if (list == null)
1653 return false;
1654
1655 foreach (MethodBase mb in list) {
1656 AParametersCollection pd = TypeManager.GetParameterData (mb);
1657 if (pd.Count == 0)
1658 return true;
1659 }
1660
1661 return false;
1662 }
1663
1664 protected abstract string GetSignatureForError ();
1665 protected abstract void Report_SymbolRelatedToPreviousError ();
1666
1667 public static bool CheckConstraints (EmitContext ec, MethodBase definition,
1668 MethodBase instantiated, Location loc)
1669 {
1670 MethodConstraintChecker checker = new MethodConstraintChecker (
1671 definition, definition.GetGenericArguments (),
1672 instantiated.GetGenericArguments (), loc);
1673
1674 return checker.CheckConstraints (ec);
1675 }
1676
1677 public static bool CheckConstraints (IResolveContext ec, Type gt, Type[] gen_params,
1678 Type[] atypes, Location loc)
1679 {
1680 TypeConstraintChecker checker = new TypeConstraintChecker (
1681 gt, gen_params, atypes, loc);
1682
1683 return checker.CheckConstraints (ec);
1684 }
1685
1686 protected class MethodConstraintChecker : ConstraintChecker
1687 {
1688 MethodBase definition;
1689
1690 public MethodConstraintChecker (MethodBase definition, Type[] gen_params,
1691 Type[] atypes, Location loc)
1692 : base (gen_params, atypes, loc)
1693 {
1694 this.definition = definition;
1695 }
1696
1697 protected override string GetSignatureForError ()
1698 {
1699 return TypeManager.CSharpSignature (definition);
1700 }
1701
1702 protected override void Report_SymbolRelatedToPreviousError ()
1703 {
1704 Report.SymbolRelatedToPreviousError (definition);
1705 }
1706 }
1707
1708 protected class TypeConstraintChecker : ConstraintChecker
1709 {
1710 Type gt;
1711
1712 public TypeConstraintChecker (Type gt, Type[] gen_params, Type[] atypes,
1713 Location loc)
1714 : base (gen_params, atypes, loc)
1715 {
1716 this.gt = gt;
1717 }
1718
1719 protected override string GetSignatureForError ()
1720 {
1721 return TypeManager.CSharpName (gt);
1722 }
1723
1724 protected override void Report_SymbolRelatedToPreviousError ()
1725 {
1726 Report.SymbolRelatedToPreviousError (gt);
1727 }
1728 }
1729 }
1730
1731 /// <summary>
1732 /// A generic method definition.
1733 /// </summary>
1734 public class GenericMethod : DeclSpace
1735 {
1736 FullNamedExpression return_type;
1737 ParametersCompiled parameters;
1738
1739 public GenericMethod (NamespaceEntry ns, DeclSpace parent, MemberName name,
1740 FullNamedExpression return_type, ParametersCompiled parameters)
1741 : base (ns, parent, name, null)
1742 {
1743 this.return_type = return_type;
1744 this.parameters = parameters;
1745 }
1746
1747 public override TypeBuilder DefineType ()
1748 {
1749 throw new Exception ();
1750 }
1751
1752 public override bool Define ()
1753 {
1754 for (int i = 0; i < TypeParameters.Length; i++)
1755 if (!TypeParameters [i].Resolve (this))
1756 return false;
1757
1758 return true;
1759 }
1760
1761 /// <summary>
1762 /// Define and resolve the type parameters.
1763 /// We're called from Method.Define().
1764 /// </summary>
1765 public bool Define (MethodOrOperator m)
1766 {
1767 TypeParameterName[] names = MemberName.TypeArguments.GetDeclarations ();
1768 string[] snames = new string [names.Length];
1769 for (int i = 0; i < names.Length; i++) {
1770 string type_argument_name = names[i].Name;
1771 int idx = parameters.GetParameterIndexByName (type_argument_name);
1772 if (idx >= 0) {
1773 Block b = m.Block;
1774 if (b == null)
1775 b = new Block (null);
1776
1777 b.Error_AlreadyDeclaredTypeParameter (parameters [i].Location,
1778 type_argument_name, "method parameter");
1779 }
1780
1781 snames[i] = type_argument_name;
1782 }
1783
1784 GenericTypeParameterBuilder[] gen_params = m.MethodBuilder.DefineGenericParameters (snames);
1785 for (int i = 0; i < TypeParameters.Length; i++)
1786 TypeParameters [i].Define (gen_params [i]);
1787
1788 if (!Define ())
1789 return false;
1790
1791 for (int i = 0; i < TypeParameters.Length; i++) {
1792 if (!TypeParameters [i].ResolveType (this))
1793 return false;
1794 }
1795
1796 return true;
1797 }
1798
1799 /// <summary>
1800 /// We're called from MethodData.Define() after creating the MethodBuilder.
1801 /// </summary>
1802 public bool DefineType (EmitContext ec, MethodBuilder mb,
1803 MethodInfo implementing, bool is_override)
1804 {
1805 for (int i = 0; i < TypeParameters.Length; i++)
1806 if (!TypeParameters [i].DefineType (
1807 ec, mb, implementing, is_override))
1808 return false;
1809
1810 bool ok = parameters.Resolve (ec);
1811
1812 if ((return_type != null) && (return_type.ResolveAsTypeTerminal (ec, false) == null))
1813 ok = false;
1814
1815 return ok;
1816 }
1817
1818 public void EmitAttributes ()
1819 {
1820 for (int i = 0; i < TypeParameters.Length; i++)
1821 TypeParameters [i].Emit ();
1822
1823 if (OptAttributes != null)
1824 OptAttributes.Emit ();
1825 }
1826
1827 public override MemberList FindMembers (MemberTypes mt, BindingFlags bf,
1828 MemberFilter filter, object criteria)
1829 {
1830 throw new Exception ();
1831 }
1832
1833 public override MemberCache MemberCache {
1834 get {
1835 return null;
1836 }
1837 }
1838
1839 public override AttributeTargets AttributeTargets {
1840 get {
1841 return AttributeTargets.Method | AttributeTargets.ReturnValue;
1842 }
1843 }
1844
1845 public override string DocCommentHeader {
1846 get { return "M:"; }
1847 }
1848
1849 public new void VerifyClsCompliance ()
1850 {
1851 foreach (TypeParameter tp in TypeParameters) {
1852 if (tp.Constraints == null)
1853 continue;
1854
1855 tp.Constraints.VerifyClsCompliance ();
1856 }
1857 }
1858 }
1859
1860 public partial class TypeManager
1861 {
1862 static public Type activator_type;
1863
1864 public static TypeContainer LookupGenericTypeContainer (Type t)
1865 {
1866 t = DropGenericTypeArguments (t);
1867 return LookupTypeContainer (t);
1868 }
1869
1870 public static Variance GetTypeParameterVariance (Type type)
1871 {
1872 TypeParameter tparam = LookupTypeParameter (type);
1873 if (tparam != null)
1874 return tparam.Variance;
1875
1876 switch (type.GenericParameterAttributes & GenericParameterAttributes.VarianceMask) {
1877 case GenericParameterAttributes.Covariant:
1878 return Variance.Covariant;
1879 case GenericParameterAttributes.Contravariant:
1880 return Variance.Contravariant;
1881 default:
1882 return Variance.None;
1883 }
1884 }
1885
1886 public static Variance CheckTypeVariance (Type t, Variance expected, MemberCore member)
1887 {
1888 TypeParameter tp = LookupTypeParameter (t);
1889 if (tp != null) {
1890 Variance v = tp.Variance;
1891 if (expected == Variance.None && v != expected ||
1892 expected == Variance.Covariant && v == Variance.Contravariant ||
1893 expected == Variance.Contravariant && v == Variance.Covariant)
1894 tp.ErrorInvalidVariance (member, expected);
1895
1896 return expected;
1897 }
1898
1899 if (t.IsGenericType) {
1900 Type[] targs_definition = GetTypeArguments (DropGenericTypeArguments (t));
1901 Type[] targs = GetTypeArguments (t);
1902 for (int i = 0; i < targs_definition.Length; ++i) {
1903 Variance v = GetTypeParameterVariance (targs_definition[i]);
1904 CheckTypeVariance (targs[i], (Variance) ((int)v * (int)expected), member);
1905 }
1906
1907 return expected;
1908 }
1909
1910 if (t.IsArray)
1911 return CheckTypeVariance (GetElementType (t), expected, member);
1912
1913 return Variance.None;
1914 }
1915
1916 public static bool IsVariantOf (Type type1, Type type2)
1917 {
1918 if (!type1.IsGenericType || !type2.IsGenericType)
1919 return false;
1920
1921 Type generic_target_type = DropGenericTypeArguments (type2);
1922 if (DropGenericTypeArguments (type1) != generic_target_type)
1923 return false;
1924
1925 Type[] t1 = GetTypeArguments (type1);
1926 Type[] t2 = GetTypeArguments (type2);
1927 Type[] targs_definition = GetTypeArguments (generic_target_type);
1928 for (int i = 0; i < targs_definition.Length; ++i) {
1929 Variance v = GetTypeParameterVariance (targs_definition [i]);
1930 if (v == Variance.None) {
1931 if (t1[i] == t2[i])
1932 continue;
1933 return false;
1934 }
1935
1936 if (v == Variance.Covariant) {
1937 if (!Convert.ImplicitReferenceConversionExists (new EmptyExpression (t1 [i]), t2 [i]))
1938 return false;
1939 } else if (!Convert.ImplicitReferenceConversionExists (new EmptyExpression (t2[i]), t1[i])) {
1940 return false;
1941 }
1942 }
1943
1944 return true;
1945 }
1946
1947 /// <summary>
1948 /// Check whether `a' and `b' may become equal generic types.
1949 /// The algorithm to do that is a little bit complicated.
1950 /// </summary>
1951 public static bool MayBecomeEqualGenericTypes (Type a, Type b, Type[] class_inferred,
1952 Type[] method_inferred)
1953 {
1954 if (a.IsGenericParameter) {
1955 //
1956 // If a is an array of a's type, they may never
1957 // become equal.
1958 //
1959 while (b.IsArray) {
1960 b = GetElementType (b);
1961 if (a.Equals (b))
1962 return false;
1963 }
1964
1965 //
1966 // If b is a generic parameter or an actual type,
1967 // they may become equal:
1968 //
1969 // class X<T,U> : I<T>, I<U>
1970 // class X<T> : I<T>, I<float>
1971 //
1972 if (b.IsGenericParameter || !b.IsGenericType) {
1973 int pos = a.GenericParameterPosition;
1974 Type[] args = a.DeclaringMethod != null ? method_inferred : class_inferred;
1975 if (args [pos] == null) {
1976 args [pos] = b;
1977 return true;
1978 }
1979
1980 return args [pos] == a;
1981 }
1982
1983 //
1984 // We're now comparing a type parameter with a
1985 // generic instance. They may become equal unless
1986 // the type parameter appears anywhere in the
1987 // generic instance:
1988 //
1989 // class X<T,U> : I<T>, I<X<U>>
1990 // -> error because you could instanciate it as
1991 // X<X<int>,int>
1992 //
1993 // class X<T> : I<T>, I<X<T>> -> ok
1994 //
1995
1996 Type[] bargs = GetTypeArguments (b);
1997 for (int i = 0; i < bargs.Length; i++) {
1998 if (a.Equals (bargs [i]))
1999 return false;
2000 }
2001
2002 return true;
2003 }
2004
2005 if (b.IsGenericParameter)
2006 return MayBecomeEqualGenericTypes (b, a, class_inferred, method_inferred);
2007
2008 //
2009 // At this point, neither a nor b are a type parameter.
2010 //
2011 // If one of them is a generic instance, let
2012 // MayBecomeEqualGenericInstances() compare them (if the
2013 // other one is not a generic instance, they can never
2014 // become equal).
2015 //
2016
2017 if (a.IsGenericType || b.IsGenericType)
2018 return MayBecomeEqualGenericInstances (a, b, class_inferred, method_inferred);
2019
2020 //
2021 // If both of them are arrays.
2022 //
2023
2024 if (a.IsArray && b.IsArray) {
2025 if (a.GetArrayRank () != b.GetArrayRank ())
2026 return false;
2027
2028 a = GetElementType (a);
2029 b = GetElementType (b);
2030
2031 return MayBecomeEqualGenericTypes (a, b, class_inferred, method_inferred);
2032 }
2033
2034 //
2035 // Ok, two ordinary types.
2036 //
2037
2038 return a.Equals (b);
2039 }
2040
2041 //
2042 // Checks whether two generic instances may become equal for some
2043 // particular instantiation (26.3.1).
2044 //
2045 public static bool MayBecomeEqualGenericInstances (Type a, Type b,
2046 Type[] class_inferred,
2047 Type[] method_inferred)
2048 {
2049 if (!a.IsGenericType || !b.IsGenericType)
2050 return false;
2051 if (a.GetGenericTypeDefinition () != b.GetGenericTypeDefinition ())
2052 return false;
2053
2054 return MayBecomeEqualGenericInstances (
2055 GetTypeArguments (a), GetTypeArguments (b), class_inferred, method_inferred);
2056 }
2057
2058 public static bool MayBecomeEqualGenericInstances (Type[] aargs, Type[] bargs,
2059 Type[] class_inferred,
2060 Type[] method_inferred)
2061 {
2062 if (aargs.Length != bargs.Length)
2063 return false;
2064
2065 for (int i = 0; i < aargs.Length; i++) {
2066 if (!MayBecomeEqualGenericTypes (aargs [i], bargs [i], class_inferred, method_inferred))
2067 return false;
2068 }
2069
2070 return true;
2071 }
2072
2073 /// <summary>
2074 /// Type inference. Try to infer the type arguments from `method',
2075 /// which is invoked with the arguments `arguments'. This is used
2076 /// when resolving an Invocation or a DelegateInvocation and the user
2077 /// did not explicitly specify type arguments.
2078 /// </summary>
2079 public static int InferTypeArguments (EmitContext ec, Arguments arguments, ref MethodBase method)
2080 {
2081 ATypeInference ti = ATypeInference.CreateInstance (arguments);
2082 Type[] i_args = ti.InferMethodArguments (ec, method);
2083 if (i_args == null)
2084 return ti.InferenceScore;
2085
2086 if (i_args.Length == 0)
2087 return 0;
2088
2089 method = ((MethodInfo) method).MakeGenericMethod (i_args);
2090 return 0;
2091 }
2092
2093 /// <summary>
2094 /// Type inference.
2095 /// </summary>
2096 public static bool InferTypeArguments (AParametersCollection param, ref MethodBase method)
2097 {
2098 if (!TypeManager.IsGenericMethod (method))
2099 return true;
2100
2101 ATypeInference ti = ATypeInference.CreateInstance (DelegateCreation.CreateDelegateMethodArguments (param, Location.Null));
2102 Type[] i_args = ti.InferDelegateArguments (method);
2103 if (i_args == null)
2104 return false;
2105
2106 method = ((MethodInfo) method).MakeGenericMethod (i_args);
2107 return true;
2108 }
2109 }
2110
2111 abstract class ATypeInference
2112 {
2113 protected readonly Arguments arguments;
2114 protected readonly int arg_count;
2115
2116 protected ATypeInference (Arguments arguments)
2117 {
2118 this.arguments = arguments;
2119 if (arguments != null)
2120 arg_count = arguments.Count;
2121 }
2122
2123 public static ATypeInference CreateInstance (Arguments arguments)
2124 {
2125 return new TypeInference (arguments);
2126 }
2127
2128 public virtual int InferenceScore {
2129 get {
2130 return int.MaxValue;
2131 }
2132 }
2133
2134 public abstract Type[] InferMethodArguments (EmitContext ec, MethodBase method);
2135 public abstract Type[] InferDelegateArguments (MethodBase method);
2136 }
2137
2138 //
2139 // Implements C# type inference
2140 //
2141 class TypeInference : ATypeInference
2142 {
2143 //
2144 // Tracks successful rate of type inference
2145 //
2146 int score = int.MaxValue;
2147
2148 public TypeInference (Arguments arguments)
2149 : base (arguments)
2150 {
2151 }
2152
2153 public override int InferenceScore {
2154 get {
2155 return score;
2156 }
2157 }
2158
2159 public override Type[] InferDelegateArguments (MethodBase method)
2160 {
2161 AParametersCollection pd = TypeManager.GetParameterData (method);
2162 if (arg_count != pd.Count)
2163 return null;
2164
2165 Type[] d_gargs = method.GetGenericArguments ();
2166 TypeInferenceContext context = new TypeInferenceContext (d_gargs);
2167
2168 // A lower-bound inference is made from each argument type Uj of D
2169 // to the corresponding parameter type Tj of M
2170 for (int i = 0; i < arg_count; ++i) {
2171 Type t = pd.Types [i];
2172 if (!t.IsGenericParameter)
2173 continue;
2174
2175 context.LowerBoundInference (arguments [i].Expr.Type, t);
2176 }
2177
2178 if (!context.FixAllTypes ())
2179 return null;
2180
2181 return context.InferredTypeArguments;
2182 }
2183
2184 public override Type[] InferMethodArguments (EmitContext ec, MethodBase method)
2185 {
2186 Type[] method_generic_args = method.GetGenericArguments ();
2187 TypeInferenceContext context = new TypeInferenceContext (method_generic_args);
2188 if (!context.UnfixedVariableExists)
2189 return Type.EmptyTypes;
2190
2191 AParametersCollection pd = TypeManager.GetParameterData (method);
2192 if (!InferInPhases (ec, context, pd))
2193 return null;
2194
2195 return context.InferredTypeArguments;
2196 }
2197
2198 //
2199 // Implements method type arguments inference
2200 //
2201 bool InferInPhases (EmitContext ec, TypeInferenceContext tic, AParametersCollection methodParameters)
2202 {
2203 int params_arguments_start;
2204 if (methodParameters.HasParams) {
2205 params_arguments_start = methodParameters.Count - 1;
2206 } else {
2207 params_arguments_start = arg_count;
2208 }
2209
2210 Type [] ptypes = methodParameters.Types;
2211
2212 //
2213 // The first inference phase
2214 //
2215 Type method_parameter = null;
2216 for (int i = 0; i < arg_count; i++) {
2217 Argument a = arguments [i];
2218 if (a == null)
2219 continue;
2220
2221 if (i < params_arguments_start) {
2222 method_parameter = methodParameters.Types [i];
2223 } else if (i == params_arguments_start) {
2224 if (arg_count == params_arguments_start + 1 && TypeManager.HasElementType (a.Type))
2225 method_parameter = methodParameters.Types [params_arguments_start];
2226 else
2227 method_parameter = TypeManager.GetElementType (methodParameters.Types [params_arguments_start]);
2228
2229 ptypes = (Type[]) ptypes.Clone ();
2230 ptypes [i] = method_parameter;
2231 }
2232
2233 //
2234 // When a lambda expression, an anonymous method
2235 // is used an explicit argument type inference takes a place
2236 //
2237 AnonymousMethodExpression am = a.Expr as AnonymousMethodExpression;
2238 if (am != null) {
2239 if (am.ExplicitTypeInference (tic, method_parameter))
2240 --score;
2241 continue;
2242 }
2243
2244 if (a.IsByRef) {
2245 score -= tic.ExactInference (a.Type, method_parameter);
2246 continue;
2247 }
2248
2249 if (a.Expr.Type == TypeManager.null_type)
2250 continue;
2251
2252 if (TypeManager.IsValueType (method_parameter)) {
2253 score -= tic.LowerBoundInference (a.Type, method_parameter);
2254 continue;
2255 }
2256
2257 //
2258 // Otherwise an output type inference is made
2259 //
2260 score -= tic.OutputTypeInference (ec, a.Expr, method_parameter);
2261 }
2262
2263 //
2264 // Part of the second phase but because it happens only once
2265 // we don't need to call it in cycle
2266 //
2267 bool fixed_any = false;
2268 if (!tic.FixIndependentTypeArguments (ptypes, ref fixed_any))
2269 return false;
2270
2271 return DoSecondPhase (ec, tic, ptypes, !fixed_any);
2272 }
2273
2274 bool DoSecondPhase (EmitContext ec, TypeInferenceContext tic, Type[] methodParameters, bool fixDependent)
2275 {
2276 bool fixed_any = false;
2277 if (fixDependent && !tic.FixDependentTypes (ref fixed_any))
2278 return false;
2279
2280 // If no further unfixed type variables exist, type inference succeeds
2281 if (!tic.UnfixedVariableExists)
2282 return true;
2283
2284 if (!fixed_any && fixDependent)
2285 return false;
2286
2287 // For all arguments where the corresponding argument output types
2288 // contain unfixed type variables but the input types do not,
2289 // an output type inference is made
2290 for (int i = 0; i < arg_count; i++) {
2291
2292 // Align params arguments
2293 Type t_i = methodParameters [i >= methodParameters.Length ? methodParameters.Length - 1: i];
2294
2295 if (!TypeManager.IsDelegateType (t_i)) {
2296 if (TypeManager.DropGenericTypeArguments (t_i) != TypeManager.expression_type)
2297 continue;
2298
2299 t_i = t_i.GetGenericArguments () [0];
2300 }
2301
2302 MethodInfo mi = Delegate.GetInvokeMethod (t_i, t_i);
2303 Type rtype = mi.ReturnType;
2304
2305 #if MS_COMPATIBLE
2306 // Blablabla, because reflection does not work with dynamic types
2307 Type[] g_args = t_i.GetGenericArguments ();
2308 rtype = g_args[rtype.GenericParameterPosition];
2309 #endif
2310
2311 if (tic.IsReturnTypeNonDependent (mi, rtype))
2312 score -= tic.OutputTypeInference (ec, arguments [i].Expr, t_i);
2313 }
2314
2315
2316 return DoSecondPhase (ec, tic, methodParameters, true);
2317 }
2318 }
2319
2320 public class TypeInferenceContext
2321 {
2322 enum BoundKind
2323 {
2324 Exact = 0,
2325 Lower = 1,
2326 Upper = 2
2327 }
2328
2329 class BoundInfo
2330 {
2331 public readonly Type Type;
2332 public readonly BoundKind Kind;
2333
2334 public BoundInfo (Type type, BoundKind kind)
2335 {
2336 this.Type = type;
2337 this.Kind = kind;
2338 }
2339
2340 public override int GetHashCode ()
2341 {
2342 return Type.GetHashCode ();
2343 }
2344
2345 public override bool Equals (object obj)
2346 {
2347 BoundInfo a = (BoundInfo) obj;
2348 return Type == a.Type && Kind == a.Kind;
2349 }
2350 }
2351
2352 readonly Type[] unfixed_types;
2353 readonly Type[] fixed_types;
2354 readonly ArrayList[] bounds;
2355 bool failed;
2356
2357 public TypeInferenceContext (Type[] typeArguments)
2358 {
2359 if (typeArguments.Length == 0)
2360 throw new ArgumentException ("Empty generic arguments");
2361
2362 fixed_types = new Type [typeArguments.Length];
2363 for (int i = 0; i < typeArguments.Length; ++i) {
2364 if (typeArguments [i].IsGenericParameter) {
2365 if (bounds == null) {
2366 bounds = new ArrayList [typeArguments.Length];
2367 unfixed_types = new Type [typeArguments.Length];
2368 }
2369 unfixed_types [i] = typeArguments [i];
2370 } else {
2371 fixed_types [i] = typeArguments [i];
2372 }
2373 }
2374 }
2375
2376 public Type[] InferredTypeArguments {
2377 get {
2378 return fixed_types;
2379 }
2380 }
2381
2382 void AddToBounds (BoundInfo bound, int index)
2383 {
2384 //
2385 // Some types cannot be used as type arguments
2386 //
2387 if (bound.Type == TypeManager.void_type || bound.Type.IsPointer)
2388 return;
2389
2390 ArrayList a = bounds [index];
2391 if (a == null) {
2392 a = new ArrayList ();
2393 bounds [index] = a;
2394 } else {
2395 if (a.Contains (bound))
2396 return;
2397 }
2398
2399 //
2400 // SPEC: does not cover type inference using constraints
2401 //
2402 //if (TypeManager.IsGenericParameter (t)) {
2403 // GenericConstraints constraints = TypeManager.GetTypeParameterConstraints (t);
2404 // if (constraints != null) {
2405 // //if (constraints.EffectiveBaseClass != null)
2406 // // t = constraints.EffectiveBaseClass;
2407 // }
2408 //}
2409 a.Add (bound);
2410 }
2411
2412 bool AllTypesAreFixed (Type[] types)
2413 {
2414 foreach (Type t in types) {
2415 if (t.IsGenericParameter) {
2416 if (!IsFixed (t))
2417 return false;
2418 continue;
2419 }
2420
2421 if (t.IsGenericType)
2422 return AllTypesAreFixed (t.GetGenericArguments ());
2423 }
2424
2425 return true;
2426 }
2427
2428 //
2429 // 26.3.3.8 Exact Inference
2430 //
2431 public int ExactInference (Type u, Type v)
2432 {
2433 // If V is an array type
2434 if (v.IsArray) {
2435 if (!u.IsArray)
2436 return 0;
2437
2438 if (u.GetArrayRank () != v.GetArrayRank ())
2439 return 0;
2440
2441 return ExactInference (TypeManager.GetElementType (u), TypeManager.GetElementType (v));
2442 }
2443
2444 // If V is constructed type and U is constructed type
2445 if (v.IsGenericType && !v.IsGenericTypeDefinition) {
2446 if (!u.IsGenericType)
2447 return 0;
2448
2449 Type [] ga_u = u.GetGenericArguments ();
2450 Type [] ga_v = v.GetGenericArguments ();
2451 if (ga_u.Length != ga_v.Length)
2452 return 0;
2453
2454 int score = 0;
2455 for (int i = 0; i < ga_u.Length; ++i)
2456 score += ExactInference (ga_u [i], ga_v [i]);
2457
2458 return score > 0 ? 1 : 0;
2459 }
2460
2461 // If V is one of the unfixed type arguments
2462 int pos = IsUnfixed (v);
2463 if (pos == -1)
2464 return 0;
2465
2466 AddToBounds (new BoundInfo (u, BoundKind.Exact), pos);
2467 return 1;
2468 }
2469
2470 public bool FixAllTypes ()
2471 {
2472 for (int i = 0; i < unfixed_types.Length; ++i) {
2473 if (!FixType (i))
2474 return false;
2475 }
2476 return true;
2477 }
2478
2479 //
2480 // All unfixed type variables Xi are fixed for which all of the following hold:
2481 // a, There is at least one type variable Xj that depends on Xi
2482 // b, Xi has a non-empty set of bounds
2483 //
2484 public bool FixDependentTypes (ref bool fixed_any)
2485 {
2486 for (int i = 0; i < unfixed_types.Length; ++i) {
2487 if (unfixed_types[i] == null)
2488 continue;
2489
2490 if (bounds[i] == null)
2491 continue;
2492
2493 if (!FixType (i))
2494 return false;
2495
2496 fixed_any = true;
2497 }
2498
2499 return true;
2500 }
2501
2502 //
2503 // All unfixed type variables Xi which depend on no Xj are fixed
2504 //
2505 public bool FixIndependentTypeArguments (Type[] methodParameters, ref bool fixed_any)
2506 {
2507 ArrayList types_to_fix = new ArrayList (unfixed_types);
2508 for (int i = 0; i < methodParameters.Length; ++i) {
2509 Type t = methodParameters[i];
2510
2511 if (!TypeManager.IsDelegateType (t)) {
2512 if (TypeManager.DropGenericTypeArguments (t) != TypeManager.expression_type)
2513 continue;
2514
2515 t = t.GetGenericArguments () [0];
2516 }
2517
2518 if (t.IsGenericParameter)
2519 continue;
2520
2521 MethodInfo invoke = Delegate.GetInvokeMethod (t, t);
2522 Type rtype = invoke.ReturnType;
2523 if (!rtype.IsGenericParameter && !rtype.IsGenericType)
2524 continue;
2525
2526 #if MS_COMPATIBLE
2527 // Blablabla, because reflection does not work with dynamic types
2528 if (rtype.IsGenericParameter) {
2529 Type [] g_args = t.GetGenericArguments ();
2530 rtype = g_args [rtype.GenericParameterPosition];
2531 }
2532 #endif
2533 // Remove dependent types, they cannot be fixed yet
2534 RemoveDependentTypes (types_to_fix, rtype);
2535 }
2536
2537 foreach (Type t in types_to_fix) {
2538 if (t == null)
2539 continue;
2540
2541 int idx = IsUnfixed (t);
2542 if (idx >= 0 && !FixType (idx)) {
2543 return false;
2544 }
2545 }
2546
2547 fixed_any = types_to_fix.Count > 0;
2548 return true;
2549 }
2550
2551 //
2552 // 26.3.3.10 Fixing
2553 //
2554 public bool FixType (int i)
2555 {
2556 // It's already fixed
2557 if (unfixed_types[i] == null)
2558 throw new InternalErrorException ("Type argument has been already fixed");
2559
2560 if (failed)
2561 return false;
2562
2563 ArrayList candidates = (ArrayList)bounds [i];
2564 if (candidates == null)
2565 return false;
2566
2567 if (candidates.Count == 1) {
2568 unfixed_types[i] = null;
2569 fixed_types[i] = ((BoundInfo) candidates[0]).Type;
2570 return true;
2571 }
2572
2573 //
2574 // Determines a unique type from which there is
2575 // a standard implicit conversion to all the other
2576 // candidate types.
2577 //
2578 Type best_candidate = null;
2579 int cii;
2580 int candidates_count = candidates.Count;
2581 for (int ci = 0; ci < candidates_count; ++ci) {
2582 BoundInfo bound = (BoundInfo)candidates [ci];
2583 for (cii = 0; cii < candidates_count; ++cii) {
2584 if (cii == ci)
2585 continue;
2586
2587 BoundInfo cbound = (BoundInfo) candidates[cii];
2588
2589 // Same type parameters with different bounds
2590 if (cbound.Type == bound.Type) {
2591 if (bound.Kind != BoundKind.Exact)
2592 bound = cbound;
2593
2594 continue;
2595 }
2596
2597 if (bound.Kind == BoundKind.Exact || cbound.Kind == BoundKind.Exact) {
2598 if (cbound.Kind != BoundKind.Exact) {
2599 if (!Convert.ImplicitConversionExists (null, new TypeExpression (cbound.Type, Location.Null), bound.Type)) {
2600 break;
2601 }
2602
2603 continue;
2604 }
2605
2606 if (bound.Kind != BoundKind.Exact) {
2607 if (!Convert.ImplicitConversionExists (null, new TypeExpression (bound.Type, Location.Null), cbound.Type)) {
2608 break;
2609 }
2610
2611 bound = cbound;
2612 continue;
2613 }
2614
2615 break;
2616 }
2617
2618 if (bound.Kind == BoundKind.Lower) {
2619 if (!Convert.ImplicitConversionExists (null, new TypeExpression (cbound.Type, Location.Null), bound.Type)) {
2620 break;
2621 }
2622 } else {
2623 if (!Convert.ImplicitConversionExists (null, new TypeExpression (bound.Type, Location.Null), cbound.Type)) {
2624 break;
2625 }
2626 }
2627 }
2628
2629 if (cii != candidates_count)
2630 continue;
2631
2632 if (best_candidate != null && best_candidate != bound.Type)
2633 return false;
2634
2635 best_candidate = bound.Type;
2636 }
2637
2638 if (best_candidate == null)
2639 return false;
2640
2641 unfixed_types[i] = null;
2642 fixed_types[i] = best_candidate;
2643 return true;
2644 }
2645
2646 //
2647 // Uses inferred types to inflate delegate type argument
2648 //
2649 public Type InflateGenericArgument (Type parameter)
2650 {
2651 if (parameter.IsGenericParameter) {
2652 //
2653 // Inflate method generic argument (MVAR) only
2654 //
2655 if (parameter.DeclaringMethod == null)
2656 return parameter;
2657
2658 return fixed_types [parameter.GenericParameterPosition];
2659 }
2660
2661 if (parameter.IsGenericType) {
2662 Type [] parameter_targs = parameter.GetGenericArguments ();
2663 for (int ii = 0; ii < parameter_targs.Length; ++ii) {
2664 parameter_targs [ii] = InflateGenericArgument (parameter_targs [ii]);
2665 }
2666 return parameter.GetGenericTypeDefinition ().MakeGenericType (parameter_targs);
2667 }
2668
2669 return parameter;
2670 }
2671
2672 //
2673 // Tests whether all delegate input arguments are fixed and generic output type
2674 // requires output type inference
2675 //
2676 public bool IsReturnTypeNonDependent (MethodInfo invoke, Type returnType)
2677 {
2678 if (returnType.IsGenericParameter) {
2679 if (IsFixed (returnType))
2680 return false;
2681 } else if (returnType.IsGenericType) {
2682 if (TypeManager.IsDelegateType (returnType)) {
2683 invoke = Delegate.GetInvokeMethod (returnType, returnType);
2684 return IsReturnTypeNonDependent (invoke, invoke.ReturnType);
2685 }
2686
2687 Type[] g_args = returnType.GetGenericArguments ();
2688
2689 // At least one unfixed return type has to exist
2690 if (AllTypesAreFixed (g_args))
2691 return false;
2692 } else {
2693 return false;
2694 }
2695
2696 // All generic input arguments have to be fixed
2697 AParametersCollection d_parameters = TypeManager.GetParameterData (invoke);
2698 return AllTypesAreFixed (d_parameters.Types);
2699 }
2700
2701 bool IsFixed (Type type)
2702 {
2703 return IsUnfixed (type) == -1;
2704 }
2705
2706 int IsUnfixed (Type type)
2707 {
2708 if (!type.IsGenericParameter)
2709 return -1;
2710
2711 //return unfixed_types[type.GenericParameterPosition] != null;
2712 for (int i = 0; i < unfixed_types.Length; ++i) {
2713 if (unfixed_types [i] == type)
2714 return i;
2715 }
2716
2717 return -1;
2718 }
2719
2720 //
2721 // 26.3.3.9 Lower-bound Inference
2722 //
2723 public int LowerBoundInference (Type u, Type v)
2724 {
2725 return LowerBoundInference (u, v, false);
2726 }
2727
2728 //
2729 // Lower-bound (false) or Upper-bound (true) inference based on inversed argument
2730 //
2731 int LowerBoundInference (Type u, Type v, bool inversed)
2732 {
2733 // If V is one of the unfixed type arguments
2734 int pos = IsUnfixed (v);
2735 if (pos != -1) {
2736 AddToBounds (new BoundInfo (u, inversed ? BoundKind.Upper : BoundKind.Lower), pos);
2737 return 1;
2738 }
2739
2740 // If U is an array type
2741 if (u.IsArray) {
2742 int u_dim = u.GetArrayRank ();
2743 Type v_i;
2744 Type u_i = TypeManager.GetElementType (u);
2745
2746 if (v.IsArray) {
2747 if (u_dim != v.GetArrayRank ())
2748 return 0;
2749
2750 v_i = TypeManager.GetElementType (v);
2751
2752 if (TypeManager.IsValueType (u_i))
2753 return ExactInference (u_i, v_i);
2754
2755 return LowerBoundInference (u_i, v_i, inversed);
2756 }
2757
2758 if (u_dim != 1)
2759 return 0;
2760
2761 if (v.IsGenericType) {
2762 Type g_v = v.GetGenericTypeDefinition ();
2763 if ((g_v != TypeManager.generic_ilist_type) && (g_v != TypeManager.generic_icollection_type) &&
2764 (g_v != TypeManager.generic_ienumerable_type))
2765 return 0;
2766
2767 v_i = TypeManager.GetTypeArguments (v) [0];
2768 if (TypeManager.IsValueType (u_i))
2769 return ExactInference (u_i, v_i);
2770
2771 return LowerBoundInference (u_i, v_i);
2772 }
2773 } else if (v.IsGenericType && !v.IsGenericTypeDefinition) {
2774 //
2775 // if V is a constructed type C<V1..Vk> and there is a unique type C<U1..Uk>
2776 // such that U is identical to, inherits from (directly or indirectly),
2777 // or implements (directly or indirectly) C<U1..Uk>
2778 //
2779 ArrayList u_candidates = new ArrayList ();
2780 if (u.IsGenericType)
2781 u_candidates.Add (u);
2782
2783 for (Type t = u.BaseType; t != null; t = t.BaseType) {
2784 if (t.IsGenericType && !t.IsGenericTypeDefinition)
2785 u_candidates.Add (t);
2786 }
2787
2788 // TODO: Implement GetGenericInterfaces only and remove
2789 // the if from foreach
2790 u_candidates.AddRange (TypeManager.GetInterfaces (u));
2791
2792 Type open_v = v.GetGenericTypeDefinition ();
2793 Type [] unique_candidate_targs = null;
2794 Type [] ga_v = v.GetGenericArguments ();
2795 foreach (Type u_candidate in u_candidates) {
2796 if (!u_candidate.IsGenericType || u_candidate.IsGenericTypeDefinition)
2797 continue;
2798
2799 if (TypeManager.DropGenericTypeArguments (u_candidate) != open_v)
2800 continue;
2801
2802 //
2803 // The unique set of types U1..Uk means that if we have an interface I<T>,
2804 // class U : I<int>, I<long> then no type inference is made when inferring
2805 // type I<T> by applying type U because T could be int or long
2806 //
2807 if (unique_candidate_targs != null) {
2808 Type[] second_unique_candidate_targs = u_candidate.GetGenericArguments ();
2809 if (TypeManager.IsEqual (unique_candidate_targs, second_unique_candidate_targs)) {
2810 unique_candidate_targs = second_unique_candidate_targs;
2811 continue;
2812 }
2813
2814 //
2815 // This should always cause type inference failure
2816 //
2817 failed = true;
2818 return 1;
2819 }
2820
2821 unique_candidate_targs = u_candidate.GetGenericArguments ();
2822 }
2823
2824 if (unique_candidate_targs != null) {
2825 Type[] ga_open_v = open_v.GetGenericArguments ();
2826 int score = 0;
2827 for (int i = 0; i < unique_candidate_targs.Length; ++i) {
2828 Variance variance = TypeManager.GetTypeParameterVariance (ga_open_v [i]);
2829
2830 Type u_i = unique_candidate_targs [i];
2831 if (variance == Variance.None || TypeManager.IsValueType (u_i)) {
2832 if (ExactInference (u_i, ga_v [i]) == 0)
2833 ++score;
2834 } else {
2835 bool upper_bound = (variance == Variance.Contravariant && !inversed) ||
2836 (variance == Variance.Covariant && inversed);
2837
2838 if (LowerBoundInference (u_i, ga_v [i], upper_bound) == 0)
2839 ++score;
2840 }
2841 }
2842 return score;
2843 }
2844 }
2845
2846 return 0;
2847 }
2848
2849 //
2850 // 26.3.3.6 Output Type Inference
2851 //
2852 public int OutputTypeInference (EmitContext ec, Expression e, Type t)
2853 {
2854 // If e is a lambda or anonymous method with inferred return type
2855 AnonymousMethodExpression ame = e as AnonymousMethodExpression;
2856 if (ame != null) {
2857 Type rt = ame.InferReturnType (ec, this, t);
2858 MethodInfo invoke = Delegate.GetInvokeMethod (t, t);
2859
2860 if (rt == null) {
2861 AParametersCollection pd = TypeManager.GetParameterData (invoke);
2862 return ame.Parameters.Count == pd.Count ? 1 : 0;
2863 }
2864
2865 Type rtype = invoke.ReturnType;
2866 #if MS_COMPATIBLE
2867 // Blablabla, because reflection does not work with dynamic types
2868 Type [] g_args = t.GetGenericArguments ();
2869 rtype = g_args [rtype.GenericParameterPosition];
2870 #endif
2871 return LowerBoundInference (rt, rtype) + 1;
2872 }
2873
2874 //
2875 // if E is a method group and T is a delegate type or expression tree type
2876 // return type Tb with parameter types T1..Tk and return type Tb, and overload
2877 // resolution of E with the types T1..Tk yields a single method with return type U,
2878 // then a lower-bound inference is made from U for Tb.
2879 //
2880 if (e is MethodGroupExpr) {
2881 // TODO: Or expression tree
2882 if (!TypeManager.IsDelegateType (t))
2883 return 0;
2884
2885 MethodInfo invoke = Delegate.GetInvokeMethod (t, t);
2886 Type rtype = invoke.ReturnType;
2887 #if MS_COMPATIBLE
2888 // Blablabla, because reflection does not work with dynamic types
2889 Type [] g_args = t.GetGenericArguments ();
2890 rtype = g_args [rtype.GenericParameterPosition];
2891 #endif
2892
2893 if (!TypeManager.IsGenericType (rtype))
2894 return 0;
2895
2896 MethodGroupExpr mg = (MethodGroupExpr) e;
2897 Arguments args = DelegateCreation.CreateDelegateMethodArguments (TypeManager.GetParameterData (invoke), e.Location);
2898 mg = mg.OverloadResolve (ec, ref args, true, e.Location);
2899 if (mg == null)
2900 return 0;
2901
2902 // TODO: What should happen when return type is of generic type ?
2903 throw new NotImplementedException ();
2904 // return LowerBoundInference (null, rtype) + 1;
2905 }
2906
2907 //
2908 // if e is an expression with type U, then
2909 // a lower-bound inference is made from U for T
2910 //
2911 return LowerBoundInference (e.Type, t) * 2;
2912 }
2913
2914 void RemoveDependentTypes (ArrayList types, Type returnType)
2915 {
2916 int idx = IsUnfixed (returnType);
2917 if (idx >= 0) {
2918 types [idx] = null;
2919 return;
2920 }
2921
2922 if (returnType.IsGenericType) {
2923 foreach (Type t in returnType.GetGenericArguments ()) {
2924 RemoveDependentTypes (types, t);
2925 }
2926 }
2927 }
2928
2929 public bool UnfixedVariableExists {
2930 get {
2931 if (unfixed_types == null)
2932 return false;
2933
2934 foreach (Type ut in unfixed_types)
2935 if (ut != null)
2936 return true;
2937 return false;
2938 }
2939 }
2940 }
2941 }
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