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2010-01-12 Zoltan Varga <vargaz@gmail.com>
[mcs.git] / mcs / generic.cs
blob6808bb643f50609b646075889866236406eef33d
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 int interface_constraints_pos = 0;
150 if ((attrs & GenericParameterAttributes.NotNullableValueTypeConstraint) != 0) {
151 base_type = TypeManager.value_type;
152 interface_constraints_pos = 1;
153 } else if ((attrs & GenericParameterAttributes.ReferenceTypeConstraint) != 0) {
154 if (constraints.Length > 0 && constraints[0].IsClass) {
155 class_constraint = base_type = constraints[0];
156 interface_constraints_pos = 1;
157 } else {
158 base_type = TypeManager.object_type;
159 }
160 } else {
161 base_type = TypeManager.object_type;
162 }
163
164 if (constraints.Length > interface_constraints_pos) {
165 if (interface_constraints_pos == 0) {
166 iface_constraints = constraints;
167 } else {
168 iface_constraints = new Type[constraints.Length - interface_constraints_pos];
169 Array.Copy (constraints, interface_constraints_pos, iface_constraints, 0, iface_constraints.Length);
170 }
171 } else {
172 iface_constraints = Type.EmptyTypes;
173 }
174 }
175
176 public override string TypeParameter
177 {
178 get { return name; }
179 }
180
181 public override GenericParameterAttributes Attributes
182 {
183 get { return attrs; }
184 }
185
186 public override Type ClassConstraint
187 {
188 get { return class_constraint; }
189 }
190
191 public override Type EffectiveBaseClass
192 {
193 get { return base_type; }
194 }
195
196 public override Type[] InterfaceConstraints
197 {
198 get { return iface_constraints; }
199 }
200 }
201
202 public enum Variance
203 {
204 //
205 // Don't add or modify internal values, they are used as -/+ calculation signs
206 //
207 None = 0,
208 Covariant = 1,
209 Contravariant = -1
210 }
211
212 public enum SpecialConstraint
213 {
214 Constructor,
215 ReferenceType,
216 ValueType
217 }
218
219 /// <summary>
220 /// Tracks the constraints for a type parameter from a generic type definition.
221 /// </summary>
222 public class Constraints : GenericConstraints {
223 string name;
224 ArrayList constraints;
225 Location loc;
226
227 //
228 // name is the identifier, constraints is an arraylist of
229 // Expressions (with types) or `true' for the constructor constraint.
230 //
231 public Constraints (string name, ArrayList constraints,
232 Location loc)
233 {
234 this.name = name;
235 this.constraints = constraints;
236 this.loc = loc;
237 }
238
239 public override string TypeParameter {
240 get {
241 return name;
242 }
243 }
244
245 public Constraints Clone ()
246 {
247 return new Constraints (name, constraints, loc);
248 }
249
250 GenericParameterAttributes attrs;
251 TypeExpr class_constraint;
252 ArrayList iface_constraints;
253 ArrayList type_param_constraints;
254 int num_constraints;
255 Type class_constraint_type;
256 Type[] iface_constraint_types;
257 Type effective_base_type;
258 bool resolved;
259 bool resolved_types;
260
261 /// <summary>
262 /// Resolve the constraints - but only resolve things into Expression's, not
263 /// into actual types.
264 /// </summary>
265 public bool Resolve (MemberCore ec, TypeParameter tp, Report Report)
266 {
267 if (resolved)
268 return true;
269
270 if (ec == null)
271 return false;
272
273 iface_constraints = new ArrayList (2); // TODO: Too expensive allocation
274 type_param_constraints = new ArrayList ();
275
276 foreach (object obj in constraints) {
277 if (HasConstructorConstraint) {
278 Report.Error (401, loc,
279 "The new() constraint must be the last constraint specified");
280 return false;
281 }
282
283 if (obj is SpecialConstraint) {
284 SpecialConstraint sc = (SpecialConstraint) obj;
285
286 if (sc == SpecialConstraint.Constructor) {
287 if (!HasValueTypeConstraint) {
288 attrs |= GenericParameterAttributes.DefaultConstructorConstraint;
289 continue;
290 }
291
292 Report.Error (451, loc, "The `new()' constraint " +
293 "cannot be used with the `struct' constraint");
294 return false;
295 }
296
297 if ((num_constraints > 0) || HasReferenceTypeConstraint || HasValueTypeConstraint) {
298 Report.Error (449, loc, "The `class' or `struct' " +
299 "constraint must be the first constraint specified");
300 return false;
301 }
302
303 if (sc == SpecialConstraint.ReferenceType)
304 attrs |= GenericParameterAttributes.ReferenceTypeConstraint;
305 else
306 attrs |= GenericParameterAttributes.NotNullableValueTypeConstraint;
307 continue;
308 }
309
310 int errors = Report.Errors;
311 FullNamedExpression fn = ((Expression) obj).ResolveAsTypeStep (ec, false);
312
313 if (fn == null) {
314 if (errors != Report.Errors)
315 return false;
316
317 NamespaceEntry.Error_NamespaceNotFound (loc, ((Expression)obj).GetSignatureForError (), Report);
318 return false;
319 }
320
321 TypeExpr expr;
322 GenericTypeExpr cexpr = fn as GenericTypeExpr;
323 if (cexpr != null) {
324 expr = cexpr.ResolveAsBaseTerminal (ec, false);
325 } else
326 expr = ((Expression) obj).ResolveAsTypeTerminal (ec, false);
327
328 if ((expr == null) || (expr.Type == null))
329 return false;
330
331 if (!ec.IsAccessibleAs (fn.Type)) {
332 Report.SymbolRelatedToPreviousError (fn.Type);
333 Report.Error (703, loc,
334 "Inconsistent accessibility: constraint type `{0}' is less accessible than `{1}'",
335 fn.GetSignatureForError (), ec.GetSignatureForError ());
336 return false;
337 }
338
339 if (TypeManager.IsGenericParameter (expr.Type))
340 type_param_constraints.Add (expr);
341 else if (expr.IsInterface)
342 iface_constraints.Add (expr);
343 else if (class_constraint != null || iface_constraints.Count != 0) {
344 Report.Error (406, loc,
345 "The class type constraint `{0}' must be listed before any other constraints. Consider moving type constraint to the beginning of the constraint list",
346 expr.GetSignatureForError ());
347 return false;
348 } else if (HasReferenceTypeConstraint || HasValueTypeConstraint) {
349 Report.Error (450, loc, "`{0}': cannot specify both " +
350 "a constraint class and the `class' " +
351 "or `struct' constraint", expr.GetSignatureForError ());
352 return false;
353 } else
354 class_constraint = expr;
355
356
357 //
358 // Checks whether each generic method parameter constraint type
359 // is valid with respect to T
360 //
361 if (tp != null && tp.Type.DeclaringMethod != null) {
362 TypeManager.CheckTypeVariance (expr.Type, Variance.Contravariant, ec as MemberCore);
363 }
364
365 num_constraints++;
366 }
367
368 ArrayList list = new ArrayList ();
369 foreach (TypeExpr iface_constraint in iface_constraints) {
370 foreach (Type type in list) {
371 if (!type.Equals (iface_constraint.Type))
372 continue;
373
374 Report.Error (405, loc,
375 "Duplicate constraint `{0}' for type " +
376 "parameter `{1}'.", iface_constraint.GetSignatureForError (),
377 name);
378 return false;
379 }
380
381 list.Add (iface_constraint.Type);
382 }
383
384 foreach (TypeExpr expr in type_param_constraints) {
385 foreach (Type type in list) {
386 if (!type.Equals (expr.Type))
387 continue;
388
389 Report.Error (405, loc,
390 "Duplicate constraint `{0}' for type " +
391 "parameter `{1}'.", expr.GetSignatureForError (), name);
392 return false;
393 }
394
395 list.Add (expr.Type);
396 }
397
398 iface_constraint_types = new Type [list.Count];
399 list.CopyTo (iface_constraint_types, 0);
400
401 if (class_constraint != null) {
402 class_constraint_type = class_constraint.Type;
403 if (class_constraint_type == null)
404 return false;
405
406 if (class_constraint_type.IsSealed) {
407 if (class_constraint_type.IsAbstract)
408 {
409 Report.Error (717, loc, "`{0}' is not a valid constraint. Static classes cannot be used as constraints",
410 TypeManager.CSharpName (class_constraint_type));
411 }
412 else
413 {
414 Report.Error (701, loc, "`{0}' is not a valid constraint. A constraint must be an interface, " +
415 "a non-sealed class or a type parameter", TypeManager.CSharpName(class_constraint_type));
416 }
417 return false;
418 }
419
420 if ((class_constraint_type == TypeManager.array_type) ||
421 (class_constraint_type == TypeManager.delegate_type) ||
422 (class_constraint_type == TypeManager.enum_type) ||
423 (class_constraint_type == TypeManager.value_type) ||
424 (class_constraint_type == TypeManager.object_type) ||
425 class_constraint_type == TypeManager.multicast_delegate_type) {
426 Report.Error (702, loc,
427 "A constraint cannot be special class `{0}'",
428 TypeManager.CSharpName (class_constraint_type));
429 return false;
430 }
431
432 if (TypeManager.IsDynamicType (class_constraint_type)) {
433 Report.Error (1967, loc, "A constraint cannot be the dynamic type");
434 return false;
435 }
436 }
437
438 if (class_constraint_type != null)
439 effective_base_type = class_constraint_type;
440 else if (HasValueTypeConstraint)
441 effective_base_type = TypeManager.value_type;
442 else
443 effective_base_type = TypeManager.object_type;
444
445 if ((attrs & GenericParameterAttributes.NotNullableValueTypeConstraint) != 0)
446 attrs |= GenericParameterAttributes.DefaultConstructorConstraint;
447
448 resolved = true;
449 return true;
450 }
451
452 bool CheckTypeParameterConstraints (Type tparam, ref TypeExpr prevConstraint, ArrayList seen, Report Report)
453 {
454 seen.Add (tparam);
455
456 Constraints constraints = TypeManager.LookupTypeParameter (tparam).Constraints;
457 if (constraints == null)
458 return true;
459
460 if (constraints.HasValueTypeConstraint) {
461 Report.Error (456, loc,
462 "Type parameter `{0}' has the `struct' constraint, so it cannot be used as a constraint for `{1}'",
463 tparam.Name, name);
464 return false;
465 }
466
467 //
468 // Checks whether there are no conflicts between type parameter constraints
469 //
470 // class Foo<T, U>
471 // where T : A
472 // where U : A, B // A and B are not convertible
473 //
474 if (constraints.HasClassConstraint) {
475 if (prevConstraint != null) {
476 Type t2 = constraints.ClassConstraint;
477 TypeExpr e2 = constraints.class_constraint;
478
479 if (!Convert.ImplicitReferenceConversionExists (prevConstraint, t2) &&
480 !Convert.ImplicitReferenceConversionExists (e2, prevConstraint.Type)) {
481 Report.Error (455, loc,
482 "Type parameter `{0}' inherits conflicting constraints `{1}' and `{2}'",
483 name, TypeManager.CSharpName (prevConstraint.Type), TypeManager.CSharpName (t2));
484 return false;
485 }
486 }
487
488 prevConstraint = constraints.class_constraint;
489 }
490
491 if (constraints.type_param_constraints == null)
492 return true;
493
494 foreach (TypeExpr expr in constraints.type_param_constraints) {
495 if (seen.Contains (expr.Type)) {
496 Report.Error (454, loc, "Circular constraint " +
497 "dependency involving `{0}' and `{1}'",
498 tparam.Name, expr.GetSignatureForError ());
499 return false;
500 }
501
502 if (!CheckTypeParameterConstraints (expr.Type, ref prevConstraint, seen, Report))
503 return false;
504 }
505
506 return true;
507 }
508
509 /// <summary>
510 /// Resolve the constraints into actual types.
511 /// </summary>
512 public bool ResolveTypes (IMemberContext ec, Report r)
513 {
514 if (resolved_types)
515 return true;
516
517 resolved_types = true;
518
519 foreach (object obj in constraints) {
520 GenericTypeExpr cexpr = obj as GenericTypeExpr;
521 if (cexpr == null)
522 continue;
523
524 if (!cexpr.CheckConstraints (ec))
525 return false;
526 }
527
528 if (type_param_constraints.Count != 0) {
529 ArrayList seen = new ArrayList ();
530 TypeExpr prev_constraint = class_constraint;
531 foreach (TypeExpr expr in type_param_constraints) {
532 if (!CheckTypeParameterConstraints (expr.Type, ref prev_constraint, seen, r))
533 return false;
534 seen.Clear ();
535 }
536 }
537
538 for (int i = 0; i < iface_constraints.Count; ++i) {
539 TypeExpr iface_constraint = (TypeExpr) iface_constraints [i];
540 iface_constraint = iface_constraint.ResolveAsTypeTerminal (ec, false);
541 if (iface_constraint == null)
542 return false;
543 iface_constraints [i] = iface_constraint;
544 }
545
546 if (class_constraint != null) {
547 class_constraint = class_constraint.ResolveAsTypeTerminal (ec, false);
548 if (class_constraint == null)
549 return false;
550 }
551
552 return true;
553 }
554
555 public override GenericParameterAttributes Attributes {
556 get { return attrs; }
557 }
558
559 public override bool HasClassConstraint {
560 get { return class_constraint != null; }
561 }
562
563 public override Type ClassConstraint {
564 get { return class_constraint_type; }
565 }
566
567 public override Type[] InterfaceConstraints {
568 get { return iface_constraint_types; }
569 }
570
571 public override Type EffectiveBaseClass {
572 get { return effective_base_type; }
573 }
574
575 public bool IsSubclassOf (Type t)
576 {
577 if ((class_constraint_type != null) &&
578 class_constraint_type.IsSubclassOf (t))
579 return true;
580
581 if (iface_constraint_types == null)
582 return false;
583
584 foreach (Type iface in iface_constraint_types) {
585 if (TypeManager.IsSubclassOf (iface, t))
586 return true;
587 }
588
589 return false;
590 }
591
592 public Location Location {
593 get {
594 return loc;
595 }
596 }
597
598 /// <summary>
599 /// This is used when we're implementing a generic interface method.
600 /// Each method type parameter in implementing method must have the same
601 /// constraints than the corresponding type parameter in the interface
602 /// method. To do that, we're called on each of the implementing method's
603 /// type parameters.
604 /// </summary>
605 public bool AreEqual (GenericConstraints gc)
606 {
607 if (gc.Attributes != attrs)
608 return false;
609
610 if (HasClassConstraint != gc.HasClassConstraint)
611 return false;
612 if (HasClassConstraint && !TypeManager.IsEqual (gc.ClassConstraint, ClassConstraint))
613 return false;
614
615 int gc_icount = gc.InterfaceConstraints != null ?
616 gc.InterfaceConstraints.Length : 0;
617 int icount = InterfaceConstraints != null ?
618 InterfaceConstraints.Length : 0;
619
620 if (gc_icount != icount)
621 return false;
622
623 for (int i = 0; i < gc.InterfaceConstraints.Length; ++i) {
624 Type iface = gc.InterfaceConstraints [i];
625 if (iface.IsGenericType)
626 iface = iface.GetGenericTypeDefinition ();
627
628 bool ok = false;
629 for (int ii = 0; ii < InterfaceConstraints.Length; ii++) {
630 Type check = InterfaceConstraints [ii];
631 if (check.IsGenericType)
632 check = check.GetGenericTypeDefinition ();
633
634 if (TypeManager.IsEqual (iface, check)) {
635 ok = true;
636 break;
637 }
638 }
639
640 if (!ok)
641 return false;
642 }
643
644 return true;
645 }
646
647 public void VerifyClsCompliance (Report r)
648 {
649 if (class_constraint_type != null && !AttributeTester.IsClsCompliant (class_constraint_type))
650 Warning_ConstrainIsNotClsCompliant (class_constraint_type, class_constraint.Location, r);
651
652 if (iface_constraint_types != null) {
653 for (int i = 0; i < iface_constraint_types.Length; ++i) {
654 if (!AttributeTester.IsClsCompliant (iface_constraint_types [i]))
655 Warning_ConstrainIsNotClsCompliant (iface_constraint_types [i],
656 ((TypeExpr)iface_constraints [i]).Location, r);
657 }
658 }
659 }
660
661 void Warning_ConstrainIsNotClsCompliant (Type t, Location loc, Report Report)
662 {
663 Report.SymbolRelatedToPreviousError (t);
664 Report.Warning (3024, 1, loc, "Constraint type `{0}' is not CLS-compliant",
665 TypeManager.CSharpName (t));
666 }
667 }
668
669 /// <summary>
670 /// A type parameter from a generic type definition.
671 /// </summary>
672 public class TypeParameter : MemberCore, IMemberContainer
673 {
674 static readonly string[] attribute_target = new string [] { "type parameter" };
675
676 DeclSpace decl;
677 GenericConstraints gc;
678 Constraints constraints;
679 GenericTypeParameterBuilder type;
680 MemberCache member_cache;
681 Variance variance;
682
683 public TypeParameter (DeclSpace parent, DeclSpace decl, string name,
684 Constraints constraints, Attributes attrs, Variance variance, Location loc)
685 : base (parent, new MemberName (name, loc), attrs)
686 {
687 this.decl = decl;
688 this.constraints = constraints;
689 this.variance = variance;
690 }
691
692 public GenericConstraints GenericConstraints {
693 get { return gc != null ? gc : constraints; }
694 }
695
696 public Constraints Constraints {
697 get { return constraints; }
698 }
699
700 public DeclSpace DeclSpace {
701 get { return decl; }
702 }
703
704 public Variance Variance {
705 get { return variance; }
706 }
707
708 public Type Type {
709 get { return type; }
710 }
711
712 /// <summary>
713 /// This is the first method which is called during the resolving
714 /// process; we're called immediately after creating the type parameters
715 /// with SRE (by calling `DefineGenericParameters()' on the TypeBuilder /
716 /// MethodBuilder).
717 ///
718 /// We're either called from TypeContainer.DefineType() or from
719 /// GenericMethod.Define() (called from Method.Define()).
720 /// </summary>
721 public void Define (GenericTypeParameterBuilder type)
722 {
723 if (this.type != null)
724 throw new InvalidOperationException ();
725
726 this.type = type;
727 TypeManager.AddTypeParameter (type, this);
728 }
729
730 public void ErrorInvalidVariance (IMemberContext mc, Variance expected)
731 {
732 // TODO: Report.SymbolRelatedToPreviousError (mc);
733 string input_variance = Variance == Variance.Contravariant ? "contravariant" : "covariant";
734 string gtype_variance;
735 switch (expected) {
736 case Variance.Contravariant: gtype_variance = "contravariantly"; break;
737 case Variance.Covariant: gtype_variance = "covariantly"; break;
738 default: gtype_variance = "invariantly"; break;
739 }
740
741 Delegate d = mc as Delegate;
742 string parameters = d != null ? d.Parameters.GetSignatureForError () : "";
743
744 Report.Error (1961, Location,
745 "The {2} type parameter `{0}' must be {3} valid on `{1}{4}'",
746 GetSignatureForError (), mc.GetSignatureForError (), input_variance, gtype_variance, parameters);
747 }
748
749 /// <summary>
750 /// This is the second method which is called during the resolving
751 /// process - in case of class type parameters, we're called from
752 /// TypeContainer.ResolveType() - after it resolved the class'es
753 /// base class and interfaces. For method type parameters, we're
754 /// called immediately after Define().
755 ///
756 /// We're just resolving the constraints into expressions here, we
757 /// don't resolve them into actual types.
758 ///
759 /// Note that in the special case of partial generic classes, we may be
760 /// called _before_ Define() and we may also be called multiple types.
761 /// </summary>
762 public bool Resolve (DeclSpace ds)
763 {
764 if (constraints != null) {
765 if (!constraints.Resolve (ds, this, Report)) {
766 constraints = null;
767 return false;
768 }
769 }
770
771 return true;
772 }
773
774 /// <summary>
775 /// This is the third method which is called during the resolving
776 /// process. We're called immediately after calling DefineConstraints()
777 /// on all of the current class'es type parameters.
778 ///
779 /// Our job is to resolve the constraints to actual types.
780 ///
781 /// Note that we may have circular dependencies on type parameters - this
782 /// is why Resolve() and ResolveType() are separate.
783 /// </summary>
784 public bool ResolveType (IMemberContext ec)
785 {
786 if (constraints != null) {
787 if (!constraints.ResolveTypes (ec, Report)) {
788 constraints = null;
789 return false;
790 }
791 }
792
793 return true;
794 }
795
796 /// <summary>
797 /// This is the fourth and last method which is called during the resolving
798 /// process. We're called after everything is fully resolved and actually
799 /// register the constraints with SRE and the TypeManager.
800 /// </summary>
801 public bool DefineType (IMemberContext ec)
802 {
803 return DefineType (ec, null, null, false);
804 }
805
806 /// <summary>
807 /// This is the fith and last method which is called during the resolving
808 /// process. We're called after everything is fully resolved and actually
809 /// register the constraints with SRE and the TypeManager.
810 ///
811 /// The `builder', `implementing' and `is_override' arguments are only
812 /// applicable to method type parameters.
813 /// </summary>
814 public bool DefineType (IMemberContext ec, MethodBuilder builder,
815 MethodInfo implementing, bool is_override)
816 {
817 if (!ResolveType (ec))
818 return false;
819
820 if (implementing != null) {
821 if (is_override && (constraints != null)) {
822 Report.Error (460, Location,
823 "`{0}': Cannot specify constraints for overrides or explicit interface implementation methods",
824 TypeManager.CSharpSignature (builder));
825 return false;
826 }
827
828 MethodBase mb = TypeManager.DropGenericMethodArguments (implementing);
829
830 int pos = type.GenericParameterPosition;
831 Type mparam = mb.GetGenericArguments () [pos];
832 GenericConstraints temp_gc = ReflectionConstraints.GetConstraints (mparam);
833
834 if (temp_gc != null)
835 gc = new InflatedConstraints (temp_gc, implementing.DeclaringType);
836 else if (constraints != null)
837 gc = new InflatedConstraints (constraints, implementing.DeclaringType);
838
839 bool ok = true;
840 if (constraints != null) {
841 if (temp_gc == null)
842 ok = false;
843 else if (!constraints.AreEqual (gc))
844 ok = false;
845 } else {
846 if (!is_override && (temp_gc != null))
847 ok = false;
848 }
849
850 if (!ok) {
851 Report.SymbolRelatedToPreviousError (implementing);
852
853 Report.Error (
854 425, Location, "The constraints for type " +
855 "parameter `{0}' of method `{1}' must match " +
856 "the constraints for type parameter `{2}' " +
857 "of interface method `{3}'. Consider using " +
858 "an explicit interface implementation instead",
859 Name, TypeManager.CSharpSignature (builder),
860 TypeManager.CSharpName (mparam), TypeManager.CSharpSignature (mb));
861 return false;
862 }
863 } else if (DeclSpace is CompilerGeneratedClass) {
864 TypeParameter[] tparams = DeclSpace.TypeParameters;
865 Type[] types = new Type [tparams.Length];
866 for (int i = 0; i < tparams.Length; i++)
867 types [i] = tparams [i].Type;
868
869 if (constraints != null)
870 gc = new InflatedConstraints (constraints, types);
871 } else {
872 gc = (GenericConstraints) constraints;
873 }
874
875 SetConstraints (type);
876 return true;
877 }
878
879 public static TypeParameter FindTypeParameter (TypeParameter[] tparams, string name)
880 {
881 foreach (var tp in tparams) {
882 if (tp.Name == name)
883 return tp;
884 }
885
886 return null;
887 }
888
889 public void SetConstraints (GenericTypeParameterBuilder type)
890 {
891 GenericParameterAttributes attr = GenericParameterAttributes.None;
892 if (variance == Variance.Contravariant)
893 attr |= GenericParameterAttributes.Contravariant;
894 else if (variance == Variance.Covariant)
895 attr |= GenericParameterAttributes.Covariant;
896
897 if (gc != null) {
898 if (gc.HasClassConstraint || gc.HasValueTypeConstraint)
899 type.SetBaseTypeConstraint (gc.EffectiveBaseClass);
900
901 attr |= gc.Attributes;
902 type.SetInterfaceConstraints (gc.InterfaceConstraints);
903 TypeManager.RegisterBuilder (type, gc.InterfaceConstraints);
904 }
905
906 type.SetGenericParameterAttributes (attr);
907 }
908
909 /// <summary>
910 /// This is called for each part of a partial generic type definition.
911 ///
912 /// If `new_constraints' is not null and we don't already have constraints,
913 /// they become our constraints. If we already have constraints, we must
914 /// check that they're the same.
915 /// con
916 /// </summary>
917 public bool UpdateConstraints (MemberCore ec, Constraints new_constraints)
918 {
919 if (type == null)
920 throw new InvalidOperationException ();
921
922 if (new_constraints == null)
923 return true;
924
925 if (!new_constraints.Resolve (ec, this, Report))
926 return false;
927 if (!new_constraints.ResolveTypes (ec, Report))
928 return false;
929
930 if (constraints != null)
931 return constraints.AreEqual (new_constraints);
932
933 constraints = new_constraints;
934 return true;
935 }
936
937 public override void Emit ()
938 {
939 if (OptAttributes != null)
940 OptAttributes.Emit ();
941
942 base.Emit ();
943 }
944
945 public override string DocCommentHeader {
946 get {
947 throw new InvalidOperationException (
948 "Unexpected attempt to get doc comment from " + this.GetType () + ".");
949 }
950 }
951
952 //
953 // MemberContainer
954 //
955
956 public override bool Define ()
957 {
958 return true;
959 }
960
961 public override void ApplyAttributeBuilder (Attribute a, CustomAttributeBuilder cb, PredefinedAttributes pa)
962 {
963 type.SetCustomAttribute (cb);
964 }
965
966 public override AttributeTargets AttributeTargets {
967 get {
968 return AttributeTargets.GenericParameter;
969 }
970 }
971
972 public override string[] ValidAttributeTargets {
973 get {
974 return attribute_target;
975 }
976 }
977
978 //
979 // IMemberContainer
980 //
981
982 string IMemberContainer.Name {
983 get { return Name; }
984 }
985
986 MemberCache IMemberContainer.BaseCache {
987 get {
988 if (gc == null)
989 return null;
990
991 if (gc.EffectiveBaseClass.BaseType == null)
992 return null;
993
994 return TypeManager.LookupMemberCache (gc.EffectiveBaseClass.BaseType);
995 }
996 }
997
998 bool IMemberContainer.IsInterface {
999 get { return false; }
1000 }
1001
1002 MemberList IMemberContainer.GetMembers (MemberTypes mt, BindingFlags bf)
1003 {
1004 throw new NotSupportedException ();
1005 }
1006
1007 public MemberCache MemberCache {
1008 get {
1009 if (member_cache != null)
1010 return member_cache;
1011
1012 if (gc == null)
1013 return null;
1014
1015 Type[] ifaces = TypeManager.ExpandInterfaces (gc.InterfaceConstraints);
1016 member_cache = new MemberCache (this, gc.EffectiveBaseClass, ifaces);
1017
1018 return member_cache;
1019 }
1020 }
1021
1022 public MemberList FindMembers (MemberTypes mt, BindingFlags bf,
1023 MemberFilter filter, object criteria)
1024 {
1025 if (gc == null)
1026 return MemberList.Empty;
1027
1028 ArrayList members = new ArrayList ();
1029
1030 if (gc.HasClassConstraint) {
1031 MemberList list = TypeManager.FindMembers (
1032 gc.ClassConstraint, mt, bf, filter, criteria);
1033
1034 members.AddRange (list);
1035 }
1036
1037 Type[] ifaces = TypeManager.ExpandInterfaces (gc.InterfaceConstraints);
1038 foreach (Type t in ifaces) {
1039 MemberList list = TypeManager.FindMembers (
1040 t, mt, bf, filter, criteria);
1041
1042 members.AddRange (list);
1043 }
1044
1045 return new MemberList (members);
1046 }
1047
1048 public bool IsSubclassOf (Type t)
1049 {
1050 if (type.Equals (t))
1051 return true;
1052
1053 if (constraints != null)
1054 return constraints.IsSubclassOf (t);
1055
1056 return false;
1057 }
1058
1059 public void InflateConstraints (Type declaring)
1060 {
1061 if (constraints != null)
1062 gc = new InflatedConstraints (constraints, declaring);
1063 }
1064
1065 public override bool IsClsComplianceRequired ()
1066 {
1067 return false;
1068 }
1069
1070 protected class InflatedConstraints : GenericConstraints
1071 {
1072 GenericConstraints gc;
1073 Type base_type;
1074 Type class_constraint;
1075 Type[] iface_constraints;
1076 Type[] dargs;
1077
1078 public InflatedConstraints (GenericConstraints gc, Type declaring)
1079 : this (gc, TypeManager.GetTypeArguments (declaring))
1080 { }
1081
1082 public InflatedConstraints (GenericConstraints gc, Type[] dargs)
1083 {
1084 this.gc = gc;
1085 this.dargs = dargs;
1086
1087 ArrayList list = new ArrayList ();
1088 if (gc.HasClassConstraint)
1089 list.Add (inflate (gc.ClassConstraint));
1090 foreach (Type iface in gc.InterfaceConstraints)
1091 list.Add (inflate (iface));
1092
1093 bool has_class_constr = false;
1094 if (list.Count > 0) {
1095 Type first = (Type) list [0];
1096 has_class_constr = !first.IsGenericParameter && !first.IsInterface;
1097 }
1098
1099 if ((list.Count > 0) && has_class_constr) {
1100 class_constraint = (Type) list [0];
1101 iface_constraints = new Type [list.Count - 1];
1102 list.CopyTo (1, iface_constraints, 0, list.Count - 1);
1103 } else {
1104 iface_constraints = new Type [list.Count];
1105 list.CopyTo (iface_constraints, 0);
1106 }
1107
1108 if (HasValueTypeConstraint)
1109 base_type = TypeManager.value_type;
1110 else if (class_constraint != null)
1111 base_type = class_constraint;
1112 else
1113 base_type = TypeManager.object_type;
1114 }
1115
1116 Type inflate (Type t)
1117 {
1118 if (t == null)
1119 return null;
1120 if (t.IsGenericParameter)
1121 return t.GenericParameterPosition < dargs.Length ? dargs [t.GenericParameterPosition] : t;
1122 if (t.IsGenericType) {
1123 Type[] args = t.GetGenericArguments ();
1124 Type[] inflated = new Type [args.Length];
1125
1126 for (int i = 0; i < args.Length; i++)
1127 inflated [i] = inflate (args [i]);
1128
1129 t = t.GetGenericTypeDefinition ();
1130 t = t.MakeGenericType (inflated);
1131 }
1132
1133 return t;
1134 }
1135
1136 public override string TypeParameter {
1137 get { return gc.TypeParameter; }
1138 }
1139
1140 public override GenericParameterAttributes Attributes {
1141 get { return gc.Attributes; }
1142 }
1143
1144 public override Type ClassConstraint {
1145 get { return class_constraint; }
1146 }
1147
1148 public override Type EffectiveBaseClass {
1149 get { return base_type; }
1150 }
1151
1152 public override Type[] InterfaceConstraints {
1153 get { return iface_constraints; }
1154 }
1155 }
1156 }
1157
1158 /// <summary>
1159 /// A TypeExpr which already resolved to a type parameter.
1160 /// </summary>
1161 public class TypeParameterExpr : TypeExpr {
1162
1163 public TypeParameterExpr (TypeParameter type_parameter, Location loc)
1164 {
1165 this.type = type_parameter.Type;
1166 this.eclass = ExprClass.TypeParameter;
1167 this.loc = loc;
1168 }
1169
1170 protected override TypeExpr DoResolveAsTypeStep (IMemberContext ec)
1171 {
1172 throw new NotSupportedException ();
1173 }
1174
1175 public override FullNamedExpression ResolveAsTypeStep (IMemberContext ec, bool silent)
1176 {
1177 return this;
1178 }
1179
1180 public override bool IsInterface {
1181 get { return false; }
1182 }
1183
1184 public override bool CheckAccessLevel (IMemberContext ds)
1185 {
1186 return true;
1187 }
1188 }
1189
1190 //
1191 // Tracks the type arguments when instantiating a generic type. It's used
1192 // by both type arguments and type parameters
1193 //
1194 public class TypeArguments {
1195 ArrayList args;
1196 Type[] atypes;
1197
1198 public TypeArguments ()
1199 {
1200 args = new ArrayList ();
1201 }
1202
1203 public TypeArguments (params FullNamedExpression[] types)
1204 {
1205 this.args = new ArrayList (types);
1206 }
1207
1208 public void Add (FullNamedExpression type)
1209 {
1210 args.Add (type);
1211 }
1212
1213 public void Add (TypeArguments new_args)
1214 {
1215 args.AddRange (new_args.args);
1216 }
1217
1218 // TODO: Should be deleted
1219 public TypeParameterName[] GetDeclarations ()
1220 {
1221 return (TypeParameterName[]) args.ToArray (typeof (TypeParameterName));
1222 }
1223
1224 /// <summary>
1225 /// We may only be used after Resolve() is called and return the fully
1226 /// resolved types.
1227 /// </summary>
1228 public Type[] Arguments {
1229 get {
1230 return atypes;
1231 }
1232 }
1233
1234 public int Count {
1235 get {
1236 return args.Count;
1237 }
1238 }
1239
1240 public string GetSignatureForError()
1241 {
1242 StringBuilder sb = new StringBuilder();
1243 for (int i = 0; i < Count; ++i)
1244 {
1245 Expression expr = (Expression)args [i];
1246 sb.Append(expr.GetSignatureForError());
1247 if (i + 1 < Count)
1248 sb.Append(',');
1249 }
1250 return sb.ToString();
1251 }
1252
1253 /// <summary>
1254 /// Resolve the type arguments.
1255 /// </summary>
1256 public bool Resolve (IMemberContext ec)
1257 {
1258 if (atypes != null)
1259 return atypes.Length != 0;
1260
1261 int count = args.Count;
1262 bool ok = true;
1263
1264 atypes = new Type [count];
1265
1266 for (int i = 0; i < count; i++){
1267 TypeExpr te = ((FullNamedExpression) args[i]).ResolveAsTypeTerminal (ec, false);
1268 if (te == null) {
1269 ok = false;
1270 continue;
1271 }
1272
1273 atypes[i] = te.Type;
1274
1275 if (te.Type.IsSealed && te.Type.IsAbstract) {
1276 ec.Compiler.Report.Error (718, te.Location, "`{0}': static classes cannot be used as generic arguments",
1277 te.GetSignatureForError ());
1278 ok = false;
1279 }
1280
1281 if (te.Type.IsPointer || TypeManager.IsSpecialType (te.Type)) {
1282 ec.Compiler.Report.Error (306, te.Location,
1283 "The type `{0}' may not be used as a type argument",
1284 te.GetSignatureForError ());
1285 ok = false;
1286 }
1287 }
1288
1289 if (!ok)
1290 atypes = Type.EmptyTypes;
1291
1292 return ok;
1293 }
1294
1295 public TypeArguments Clone ()
1296 {
1297 TypeArguments copy = new TypeArguments ();
1298 foreach (Expression ta in args)
1299 copy.args.Add (ta);
1300
1301 return copy;
1302 }
1303 }
1304
1305 public class TypeParameterName : SimpleName
1306 {
1307 Attributes attributes;
1308 Variance variance;
1309
1310 public TypeParameterName (string name, Attributes attrs, Location loc)
1311 : this (name, attrs, Variance.None, loc)
1312 {
1313 }
1314
1315 public TypeParameterName (string name, Attributes attrs, Variance variance, Location loc)
1316 : base (name, loc)
1317 {
1318 attributes = attrs;
1319 this.variance = variance;
1320 }
1321
1322 public Attributes OptAttributes {
1323 get {
1324 return attributes;
1325 }
1326 }
1327
1328 public Variance Variance {
1329 get {
1330 return variance;
1331 }
1332 }
1333 }
1334
1335 /// <summary>
1336 /// A reference expression to generic type
1337 /// </summary>
1338 class GenericTypeExpr : TypeExpr
1339 {
1340 TypeArguments args;
1341 Type[] gen_params; // TODO: Waiting for constrains check cleanup
1342 Type open_type;
1343
1344 //
1345 // Should be carefully used only with defined generic containers. Type parameters
1346 // can be used as type arguments in this case.
1347 //
1348 // TODO: This could be GenericTypeExpr specialization
1349 //
1350 public GenericTypeExpr (DeclSpace gType, Location l)
1351 {
1352 open_type = gType.TypeBuilder.GetGenericTypeDefinition ();
1353
1354 args = new TypeArguments ();
1355 foreach (TypeParameter type_param in gType.TypeParameters)
1356 args.Add (new TypeParameterExpr (type_param, l));
1357
1358 this.loc = l;
1359 }
1360
1361 /// <summary>
1362 /// Instantiate the generic type `t' with the type arguments `args'.
1363 /// Use this constructor if you already know the fully resolved
1364 /// generic type.
1365 /// </summary>
1366 public GenericTypeExpr (Type t, TypeArguments args, Location l)
1367 {
1368 open_type = t.GetGenericTypeDefinition ();
1369
1370 loc = l;
1371 this.args = args;
1372 }
1373
1374 public TypeArguments TypeArguments {
1375 get { return args; }
1376 }
1377
1378 public override string GetSignatureForError ()
1379 {
1380 return TypeManager.CSharpName (type);
1381 }
1382
1383 protected override TypeExpr DoResolveAsTypeStep (IMemberContext ec)
1384 {
1385 if (eclass != ExprClass.Invalid)
1386 return this;
1387
1388 eclass = ExprClass.Type;
1389
1390 if (!args.Resolve (ec))
1391 return null;
1392
1393 gen_params = open_type.GetGenericArguments ();
1394 Type[] atypes = args.Arguments;
1395
1396 if (atypes.Length != gen_params.Length) {
1397 Namespace.Error_InvalidNumberOfTypeArguments (open_type, loc);
1398 return null;
1399 }
1400
1401 //
1402 // Now bind the parameters
1403 //
1404 type = open_type.MakeGenericType (atypes);
1405 return this;
1406 }
1407
1408 /// <summary>
1409 /// Check the constraints; we're called from ResolveAsTypeTerminal()
1410 /// after fully resolving the constructed type.
1411 /// </summary>
1412 public bool CheckConstraints (IMemberContext ec)
1413 {
1414 return ConstraintChecker.CheckConstraints (ec, open_type, gen_params, args.Arguments, loc);
1415 }
1416
1417 public override bool CheckAccessLevel (IMemberContext mc)
1418 {
1419 return mc.CurrentTypeDefinition.CheckAccessLevel (open_type);
1420 }
1421
1422 public override bool IsClass {
1423 get { return open_type.IsClass; }
1424 }
1425
1426 public override bool IsValueType {
1427 get { return TypeManager.IsStruct (open_type); }
1428 }
1429
1430 public override bool IsInterface {
1431 get { return open_type.IsInterface; }
1432 }
1433
1434 public override bool IsSealed {
1435 get { return open_type.IsSealed; }
1436 }
1437
1438 public override bool Equals (object obj)
1439 {
1440 GenericTypeExpr cobj = obj as GenericTypeExpr;
1441 if (cobj == null)
1442 return false;
1443
1444 if ((type == null) || (cobj.type == null))
1445 return false;
1446
1447 return type == cobj.type;
1448 }
1449
1450 public override int GetHashCode ()
1451 {
1452 return base.GetHashCode ();
1453 }
1454 }
1455
1456 public abstract class ConstraintChecker
1457 {
1458 protected readonly Type[] gen_params;
1459 protected readonly Type[] atypes;
1460 protected readonly Location loc;
1461 protected Report Report;
1462
1463 protected ConstraintChecker (Type[] gen_params, Type[] atypes, Location loc, Report r)
1464 {
1465 this.gen_params = gen_params;
1466 this.atypes = atypes;
1467 this.loc = loc;
1468 this.Report = r;
1469 }
1470
1471 /// <summary>
1472 /// Check the constraints; we're called from ResolveAsTypeTerminal()
1473 /// after fully resolving the constructed type.
1474 /// </summary>
1475 public bool CheckConstraints (IMemberContext ec)
1476 {
1477 for (int i = 0; i < gen_params.Length; i++) {
1478 if (!CheckConstraints (ec, i))
1479 return false;
1480 }
1481
1482 return true;
1483 }
1484
1485 protected bool CheckConstraints (IMemberContext ec, int index)
1486 {
1487 Type atype = atypes [index];
1488 Type ptype = gen_params [index];
1489
1490 if (atype == ptype)
1491 return true;
1492
1493 Expression aexpr = new EmptyExpression (atype);
1494
1495 GenericConstraints gc = TypeManager.GetTypeParameterConstraints (ptype);
1496 if (gc == null)
1497 return true;
1498
1499 bool is_class, is_struct;
1500 if (atype.IsGenericParameter) {
1501 GenericConstraints agc = TypeManager.GetTypeParameterConstraints (atype);
1502 if (agc != null) {
1503 if (agc is Constraints) {
1504 // FIXME: No constraints can be resolved here, we are in
1505 // completely wrong/different context. This path is hit
1506 // when resolving base type of unresolved generic type
1507 // with constraints. We are waiting with CheckConsttraints
1508 // after type-definition but not in this case
1509 if (!((Constraints) agc).Resolve (null, null, Report))
1510 return true;
1511 }
1512 is_class = agc.IsReferenceType;
1513 is_struct = agc.IsValueType;
1514 } else {
1515 is_class = is_struct = false;
1516 }
1517 } else {
1518 is_class = TypeManager.IsReferenceType (atype);
1519 is_struct = TypeManager.IsValueType (atype) && !TypeManager.IsNullableType (atype);
1520 }
1521
1522 //
1523 // First, check the `class' and `struct' constraints.
1524 //
1525 if (gc.HasReferenceTypeConstraint && !is_class) {
1526 Report.Error (452, loc, "The type `{0}' must be " +
1527 "a reference type in order to use it " +
1528 "as type parameter `{1}' in the " +
1529 "generic type or method `{2}'.",
1530 TypeManager.CSharpName (atype),
1531 TypeManager.CSharpName (ptype),
1532 GetSignatureForError ());
1533 return false;
1534 } else if (gc.HasValueTypeConstraint && !is_struct) {
1535 Report.Error (453, loc, "The type `{0}' must be a " +
1536 "non-nullable value type in order to use it " +
1537 "as type parameter `{1}' in the " +
1538 "generic type or method `{2}'.",
1539 TypeManager.CSharpName (atype),
1540 TypeManager.CSharpName (ptype),
1541 GetSignatureForError ());
1542 return false;
1543 }
1544
1545 //
1546 // The class constraint comes next.
1547 //
1548 if (gc.HasClassConstraint) {
1549 if (!CheckConstraint (ec, ptype, aexpr, gc.ClassConstraint))
1550 return false;
1551 }
1552
1553 //
1554 // Now, check the interface constraints.
1555 //
1556 if (gc.InterfaceConstraints != null) {
1557 foreach (Type it in gc.InterfaceConstraints) {
1558 if (!CheckConstraint (ec, ptype, aexpr, it))
1559 return false;
1560 }
1561 }
1562
1563 //
1564 // Finally, check the constructor constraint.
1565 //
1566
1567 if (!gc.HasConstructorConstraint)
1568 return true;
1569
1570 if (TypeManager.IsValueType (atype))
1571 return true;
1572
1573 if (HasDefaultConstructor (atype))
1574 return true;
1575
1576 Report_SymbolRelatedToPreviousError ();
1577 Report.SymbolRelatedToPreviousError (atype);
1578 Report.Error (310, loc, "The type `{0}' must have a public " +
1579 "parameterless constructor in order to use it " +
1580 "as parameter `{1}' in the generic type or " +
1581 "method `{2}'",
1582 TypeManager.CSharpName (atype),
1583 TypeManager.CSharpName (ptype),
1584 GetSignatureForError ());
1585 return false;
1586 }
1587
1588 protected bool CheckConstraint (IMemberContext ec, Type ptype, Expression expr,
1589 Type ctype)
1590 {
1591 //
1592 // All this is needed because we don't have
1593 // real inflated type hierarchy
1594 //
1595 if (TypeManager.HasGenericArguments (ctype)) {
1596 Type[] types = TypeManager.GetTypeArguments (ctype);
1597
1598 TypeArguments new_args = new TypeArguments ();
1599
1600 for (int i = 0; i < types.Length; i++) {
1601 Type t = TypeManager.TypeToCoreType (types [i]);
1602
1603 if (t.IsGenericParameter) {
1604 int pos = t.GenericParameterPosition;
1605 if (t.DeclaringMethod == null && this is MethodConstraintChecker) {
1606 Type parent = ((MethodConstraintChecker) this).declaring_type;
1607 t = parent.GetGenericArguments ()[pos];
1608 } else {
1609 t = atypes [pos];
1610 }
1611 }
1612 new_args.Add (new TypeExpression (t, loc));
1613 }
1614
1615 TypeExpr ct = new GenericTypeExpr (ctype, new_args, loc);
1616 if (ct.ResolveAsTypeStep (ec, false) == null)
1617 return false;
1618 ctype = ct.Type;
1619 } else if (ctype.IsGenericParameter) {
1620 int pos = ctype.GenericParameterPosition;
1621 if (ctype.DeclaringMethod == null) {
1622 // FIXME: Implement
1623 return true;
1624 } else {
1625 ctype = atypes [pos];
1626 }
1627 }
1628
1629 if (Convert.ImplicitStandardConversionExists (expr, ctype))
1630 return true;
1631
1632 Report_SymbolRelatedToPreviousError ();
1633 Report.SymbolRelatedToPreviousError (expr.Type);
1634
1635 if (TypeManager.IsNullableType (expr.Type) && ctype.IsInterface) {
1636 Report.Error (313, loc,
1637 "The type `{0}' cannot be used as type parameter `{1}' in the generic type or method `{2}'. " +
1638 "The nullable type `{0}' never satisfies interface constraint of type `{3}'",
1639 TypeManager.CSharpName (expr.Type), TypeManager.CSharpName (ptype),
1640 GetSignatureForError (), TypeManager.CSharpName (ctype));
1641 } else {
1642 Report.Error (309, loc,
1643 "The type `{0}' must be convertible to `{1}' in order to " +
1644 "use it as parameter `{2}' in the generic type or method `{3}'",
1645 TypeManager.CSharpName (expr.Type), TypeManager.CSharpName (ctype),
1646 TypeManager.CSharpName (ptype), GetSignatureForError ());
1647 }
1648 return false;
1649 }
1650
1651 static bool HasDefaultConstructor (Type atype)
1652 {
1653 TypeParameter tparam = TypeManager.LookupTypeParameter (atype);
1654 if (tparam != null) {
1655 if (tparam.GenericConstraints == null)
1656 return false;
1657
1658 return tparam.GenericConstraints.HasConstructorConstraint ||
1659 tparam.GenericConstraints.HasValueTypeConstraint;
1660 }
1661
1662 if (atype.IsAbstract)
1663 return false;
1664
1665 again:
1666 atype = TypeManager.DropGenericTypeArguments (atype);
1667 if (atype is TypeBuilder) {
1668 TypeContainer tc = TypeManager.LookupTypeContainer (atype);
1669 if (tc.InstanceConstructors == null) {
1670 atype = atype.BaseType;
1671 goto again;
1672 }
1673
1674 foreach (Constructor c in tc.InstanceConstructors) {
1675 if ((c.ModFlags & Modifiers.PUBLIC) == 0)
1676 continue;
1677 if ((c.Parameters.FixedParameters != null) &&
1678 (c.Parameters.FixedParameters.Length != 0))
1679 continue;
1680 if (c.Parameters.HasArglist || c.Parameters.HasParams)
1681 continue;
1682
1683 return true;
1684 }
1685 }
1686
1687 MemberInfo [] list = TypeManager.MemberLookup (null, null, atype, MemberTypes.Constructor,
1688 BindingFlags.Public | BindingFlags.Instance | BindingFlags.DeclaredOnly,
1689 ConstructorInfo.ConstructorName, null);
1690
1691 if (list == null)
1692 return false;
1693
1694 foreach (MethodBase mb in list) {
1695 AParametersCollection pd = TypeManager.GetParameterData (mb);
1696 if (pd.Count == 0)
1697 return true;
1698 }
1699
1700 return false;
1701 }
1702
1703 protected abstract string GetSignatureForError ();
1704 protected abstract void Report_SymbolRelatedToPreviousError ();
1705
1706 public static bool CheckConstraints (IMemberContext ec, MethodBase definition,
1707 MethodBase instantiated, Location loc)
1708 {
1709 MethodConstraintChecker checker = new MethodConstraintChecker (
1710 definition, instantiated.DeclaringType, definition.GetGenericArguments (),
1711 instantiated.GetGenericArguments (), loc, ec.Compiler.Report);
1712
1713 return checker.CheckConstraints (ec);
1714 }
1715
1716 public static bool CheckConstraints (IMemberContext ec, Type gt, Type[] gen_params,
1717 Type[] atypes, Location loc)
1718 {
1719 TypeConstraintChecker checker = new TypeConstraintChecker (
1720 gt, gen_params, atypes, loc, ec.Compiler.Report);
1721
1722 return checker.CheckConstraints (ec);
1723 }
1724
1725 protected class MethodConstraintChecker : ConstraintChecker
1726 {
1727 MethodBase definition;
1728 public Type declaring_type;
1729
1730 public MethodConstraintChecker (MethodBase definition, Type declaringType, Type[] gen_params,
1731 Type[] atypes, Location loc, Report r)
1732 : base (gen_params, atypes, loc, r)
1733 {
1734 this.declaring_type = declaringType;
1735 this.definition = definition;
1736 }
1737
1738 protected override string GetSignatureForError ()
1739 {
1740 return TypeManager.CSharpSignature (definition);
1741 }
1742
1743 protected override void Report_SymbolRelatedToPreviousError ()
1744 {
1745 Report.SymbolRelatedToPreviousError (definition);
1746 }
1747 }
1748
1749 protected class TypeConstraintChecker : ConstraintChecker
1750 {
1751 Type gt;
1752
1753 public TypeConstraintChecker (Type gt, Type[] gen_params, Type[] atypes,
1754 Location loc, Report r)
1755 : base (gen_params, atypes, loc, r)
1756 {
1757 this.gt = gt;
1758 }
1759
1760 protected override string GetSignatureForError ()
1761 {
1762 return TypeManager.CSharpName (gt);
1763 }
1764
1765 protected override void Report_SymbolRelatedToPreviousError ()
1766 {
1767 Report.SymbolRelatedToPreviousError (gt);
1768 }
1769 }
1770 }
1771
1772 /// <summary>
1773 /// A generic method definition.
1774 /// </summary>
1775 public class GenericMethod : DeclSpace
1776 {
1777 FullNamedExpression return_type;
1778 ParametersCompiled parameters;
1779
1780 public GenericMethod (NamespaceEntry ns, DeclSpace parent, MemberName name,
1781 FullNamedExpression return_type, ParametersCompiled parameters)
1782 : base (ns, parent, name, null)
1783 {
1784 this.return_type = return_type;
1785 this.parameters = parameters;
1786 }
1787
1788 public override TypeContainer CurrentTypeDefinition {
1789 get {
1790 return Parent.CurrentTypeDefinition;
1791 }
1792 }
1793
1794 public override TypeParameter[] CurrentTypeParameters {
1795 get {
1796 return base.type_params;
1797 }
1798 }
1799
1800 public override TypeBuilder DefineType ()
1801 {
1802 throw new Exception ();
1803 }
1804
1805 public override bool Define ()
1806 {
1807 for (int i = 0; i < TypeParameters.Length; i++)
1808 if (!TypeParameters [i].Resolve (this))
1809 return false;
1810
1811 return true;
1812 }
1813
1814 /// <summary>
1815 /// Define and resolve the type parameters.
1816 /// We're called from Method.Define().
1817 /// </summary>
1818 public bool Define (MethodOrOperator m)
1819 {
1820 TypeParameterName[] names = MemberName.TypeArguments.GetDeclarations ();
1821 string[] snames = new string [names.Length];
1822 for (int i = 0; i < names.Length; i++) {
1823 string type_argument_name = names[i].Name;
1824 int idx = parameters.GetParameterIndexByName (type_argument_name);
1825 if (idx >= 0) {
1826 Block b = m.Block;
1827 if (b == null)
1828 b = new Block (null);
1829
1830 b.Error_AlreadyDeclaredTypeParameter (Report, parameters [i].Location,
1831 type_argument_name, "method parameter");
1832 }
1833
1834 snames[i] = type_argument_name;
1835 }
1836
1837 GenericTypeParameterBuilder[] gen_params = m.MethodBuilder.DefineGenericParameters (snames);
1838 for (int i = 0; i < TypeParameters.Length; i++)
1839 TypeParameters [i].Define (gen_params [i]);
1840
1841 if (!Define ())
1842 return false;
1843
1844 for (int i = 0; i < TypeParameters.Length; i++) {
1845 if (!TypeParameters [i].ResolveType (this))
1846 return false;
1847 }
1848
1849 return true;
1850 }
1851
1852 /// <summary>
1853 /// We're called from MethodData.Define() after creating the MethodBuilder.
1854 /// </summary>
1855 public bool DefineType (IMemberContext ec, MethodBuilder mb,
1856 MethodInfo implementing, bool is_override)
1857 {
1858 for (int i = 0; i < TypeParameters.Length; i++)
1859 if (!TypeParameters [i].DefineType (
1860 ec, mb, implementing, is_override))
1861 return false;
1862
1863 bool ok = parameters.Resolve (ec);
1864
1865 if ((return_type != null) && (return_type.ResolveAsTypeTerminal (ec, false) == null))
1866 ok = false;
1867
1868 return ok;
1869 }
1870
1871 public void EmitAttributes ()
1872 {
1873 for (int i = 0; i < TypeParameters.Length; i++)
1874 TypeParameters [i].Emit ();
1875
1876 if (OptAttributes != null)
1877 OptAttributes.Emit ();
1878 }
1879
1880 public override MemberList FindMembers (MemberTypes mt, BindingFlags bf,
1881 MemberFilter filter, object criteria)
1882 {
1883 throw new Exception ();
1884 }
1885
1886 public override string GetSignatureForError ()
1887 {
1888 return base.GetSignatureForError () + parameters.GetSignatureForError ();
1889 }
1890
1891 public override MemberCache MemberCache {
1892 get {
1893 return null;
1894 }
1895 }
1896
1897 public override AttributeTargets AttributeTargets {
1898 get {
1899 return AttributeTargets.Method | AttributeTargets.ReturnValue;
1900 }
1901 }
1902
1903 public override string DocCommentHeader {
1904 get { return "M:"; }
1905 }
1906
1907 public new void VerifyClsCompliance ()
1908 {
1909 foreach (TypeParameter tp in TypeParameters) {
1910 if (tp.Constraints == null)
1911 continue;
1912
1913 tp.Constraints.VerifyClsCompliance (Report);
1914 }
1915 }
1916 }
1917
1918 public partial class TypeManager
1919 {
1920 static public Type activator_type;
1921
1922 public static TypeContainer LookupGenericTypeContainer (Type t)
1923 {
1924 t = DropGenericTypeArguments (t);
1925 return LookupTypeContainer (t);
1926 }
1927
1928 public static Variance GetTypeParameterVariance (Type type)
1929 {
1930 TypeParameter tparam = LookupTypeParameter (type);
1931 if (tparam != null)
1932 return tparam.Variance;
1933
1934 switch (type.GenericParameterAttributes & GenericParameterAttributes.VarianceMask) {
1935 case GenericParameterAttributes.Covariant:
1936 return Variance.Covariant;
1937 case GenericParameterAttributes.Contravariant:
1938 return Variance.Contravariant;
1939 default:
1940 return Variance.None;
1941 }
1942 }
1943
1944 public static Variance CheckTypeVariance (Type t, Variance expected, IMemberContext member)
1945 {
1946 TypeParameter tp = LookupTypeParameter (t);
1947 if (tp != null) {
1948 Variance v = tp.Variance;
1949 if (expected == Variance.None && v != expected ||
1950 expected == Variance.Covariant && v == Variance.Contravariant ||
1951 expected == Variance.Contravariant && v == Variance.Covariant)
1952 tp.ErrorInvalidVariance (member, expected);
1953
1954 return expected;
1955 }
1956
1957 if (t.IsGenericType) {
1958 Type[] targs_definition = GetTypeArguments (DropGenericTypeArguments (t));
1959 Type[] targs = GetTypeArguments (t);
1960 for (int i = 0; i < targs_definition.Length; ++i) {
1961 Variance v = GetTypeParameterVariance (targs_definition[i]);
1962 CheckTypeVariance (targs[i], (Variance) ((int)v * (int)expected), member);
1963 }
1964
1965 return expected;
1966 }
1967
1968 if (t.IsArray)
1969 return CheckTypeVariance (GetElementType (t), expected, member);
1970
1971 return Variance.None;
1972 }
1973
1974 public static bool IsVariantOf (Type type1, Type type2)
1975 {
1976 if (!type1.IsGenericType || !type2.IsGenericType)
1977 return false;
1978
1979 Type generic_target_type = DropGenericTypeArguments (type2);
1980 if (DropGenericTypeArguments (type1) != generic_target_type)
1981 return false;
1982
1983 Type[] t1 = GetTypeArguments (type1);
1984 Type[] t2 = GetTypeArguments (type2);
1985 Type[] targs_definition = GetTypeArguments (generic_target_type);
1986 for (int i = 0; i < targs_definition.Length; ++i) {
1987 Variance v = GetTypeParameterVariance (targs_definition [i]);
1988 if (v == Variance.None) {
1989 if (t1[i] == t2[i])
1990 continue;
1991 return false;
1992 }
1993
1994 if (v == Variance.Covariant) {
1995 if (!Convert.ImplicitReferenceConversionExists (new EmptyExpression (t1 [i]), t2 [i]))
1996 return false;
1997 } else if (!Convert.ImplicitReferenceConversionExists (new EmptyExpression (t2[i]), t1[i])) {
1998 return false;
1999 }
2000 }
2001
2002 return true;
2003 }
2004
2005 /// <summary>
2006 /// Check whether `a' and `b' may become equal generic types.
2007 /// The algorithm to do that is a little bit complicated.
2008 /// </summary>
2009 public static bool MayBecomeEqualGenericTypes (Type a, Type b, Type[] class_inferred,
2010 Type[] method_inferred)
2011 {
2012 if (a.IsGenericParameter) {
2013 //
2014 // If a is an array of a's type, they may never
2015 // become equal.
2016 //
2017 while (b.IsArray) {
2018 b = GetElementType (b);
2019 if (a.Equals (b))
2020 return false;
2021 }
2022
2023 //
2024 // If b is a generic parameter or an actual type,
2025 // they may become equal:
2026 //
2027 // class X<T,U> : I<T>, I<U>
2028 // class X<T> : I<T>, I<float>
2029 //
2030 if (b.IsGenericParameter || !b.IsGenericType) {
2031 int pos = a.GenericParameterPosition;
2032 Type[] args = a.DeclaringMethod != null ? method_inferred : class_inferred;
2033 if (args [pos] == null) {
2034 args [pos] = b;
2035 return true;
2036 }
2037
2038 return args [pos] == a;
2039 }
2040
2041 //
2042 // We're now comparing a type parameter with a
2043 // generic instance. They may become equal unless
2044 // the type parameter appears anywhere in the
2045 // generic instance:
2046 //
2047 // class X<T,U> : I<T>, I<X<U>>
2048 // -> error because you could instanciate it as
2049 // X<X<int>,int>
2050 //
2051 // class X<T> : I<T>, I<X<T>> -> ok
2052 //
2053
2054 Type[] bargs = GetTypeArguments (b);
2055 for (int i = 0; i < bargs.Length; i++) {
2056 if (a.Equals (bargs [i]))
2057 return false;
2058 }
2059
2060 return true;
2061 }
2062
2063 if (b.IsGenericParameter)
2064 return MayBecomeEqualGenericTypes (b, a, class_inferred, method_inferred);
2065
2066 //
2067 // At this point, neither a nor b are a type parameter.
2068 //
2069 // If one of them is a generic instance, let
2070 // MayBecomeEqualGenericInstances() compare them (if the
2071 // other one is not a generic instance, they can never
2072 // become equal).
2073 //
2074
2075 if (a.IsGenericType || b.IsGenericType)
2076 return MayBecomeEqualGenericInstances (a, b, class_inferred, method_inferred);
2077
2078 //
2079 // If both of them are arrays.
2080 //
2081
2082 if (a.IsArray && b.IsArray) {
2083 if (a.GetArrayRank () != b.GetArrayRank ())
2084 return false;
2085
2086 a = GetElementType (a);
2087 b = GetElementType (b);
2088
2089 return MayBecomeEqualGenericTypes (a, b, class_inferred, method_inferred);
2090 }
2091
2092 //
2093 // Ok, two ordinary types.
2094 //
2095
2096 return a.Equals (b);
2097 }
2098
2099 //
2100 // Checks whether two generic instances may become equal for some
2101 // particular instantiation (26.3.1).
2102 //
2103 public static bool MayBecomeEqualGenericInstances (Type a, Type b,
2104 Type[] class_inferred,
2105 Type[] method_inferred)
2106 {
2107 if (!a.IsGenericType || !b.IsGenericType)
2108 return false;
2109 if (a.GetGenericTypeDefinition () != b.GetGenericTypeDefinition ())
2110 return false;
2111
2112 return MayBecomeEqualGenericInstances (
2113 GetTypeArguments (a), GetTypeArguments (b), class_inferred, method_inferred);
2114 }
2115
2116 public static bool MayBecomeEqualGenericInstances (Type[] aargs, Type[] bargs,
2117 Type[] class_inferred,
2118 Type[] method_inferred)
2119 {
2120 if (aargs.Length != bargs.Length)
2121 return false;
2122
2123 for (int i = 0; i < aargs.Length; i++) {
2124 if (!MayBecomeEqualGenericTypes (aargs [i], bargs [i], class_inferred, method_inferred))
2125 return false;
2126 }
2127
2128 return true;
2129 }
2130
2131 /// <summary>
2132 /// Type inference. Try to infer the type arguments from `method',
2133 /// which is invoked with the arguments `arguments'. This is used
2134 /// when resolving an Invocation or a DelegateInvocation and the user
2135 /// did not explicitly specify type arguments.
2136 /// </summary>
2137 public static int InferTypeArguments (ResolveContext ec, Arguments arguments, ref MethodBase method)
2138 {
2139 ATypeInference ti = ATypeInference.CreateInstance (arguments);
2140 Type[] i_args = ti.InferMethodArguments (ec, method);
2141 if (i_args == null)
2142 return ti.InferenceScore;
2143
2144 if (i_args.Length == 0)
2145 return 0;
2146
2147 method = ((MethodInfo) method).MakeGenericMethod (i_args);
2148 return 0;
2149 }
2150
2151 /*
2152 public static bool InferTypeArguments (ResolveContext ec, AParametersCollection param, ref MethodBase method)
2153 {
2154 if (!TypeManager.IsGenericMethod (method))
2155 return true;
2156
2157 ATypeInference ti = ATypeInference.CreateInstance (DelegateCreation.CreateDelegateMethodArguments (param, Location.Null));
2158 Type[] i_args = ti.InferDelegateArguments (ec, method);
2159 if (i_args == null)
2160 return false;
2161
2162 method = ((MethodInfo) method).MakeGenericMethod (i_args);
2163 return true;
2164 }
2165 */
2166 }
2167
2168 abstract class ATypeInference
2169 {
2170 protected readonly Arguments arguments;
2171 protected readonly int arg_count;
2172
2173 protected ATypeInference (Arguments arguments)
2174 {
2175 this.arguments = arguments;
2176 if (arguments != null)
2177 arg_count = arguments.Count;
2178 }
2179
2180 public static ATypeInference CreateInstance (Arguments arguments)
2181 {
2182 return new TypeInference (arguments);
2183 }
2184
2185 public virtual int InferenceScore {
2186 get {
2187 return int.MaxValue;
2188 }
2189 }
2190
2191 public abstract Type[] InferMethodArguments (ResolveContext ec, MethodBase method);
2192 // public abstract Type[] InferDelegateArguments (ResolveContext ec, MethodBase method);
2193 }
2194
2195 //
2196 // Implements C# type inference
2197 //
2198 class TypeInference : ATypeInference
2199 {
2200 //
2201 // Tracks successful rate of type inference
2202 //
2203 int score = int.MaxValue;
2204
2205 public TypeInference (Arguments arguments)
2206 : base (arguments)
2207 {
2208 }
2209
2210 public override int InferenceScore {
2211 get {
2212 return score;
2213 }
2214 }
2215
2216 /*
2217 public override Type[] InferDelegateArguments (ResolveContext ec, MethodBase method)
2218 {
2219 AParametersCollection pd = TypeManager.GetParameterData (method);
2220 if (arg_count != pd.Count)
2221 return null;
2222
2223 Type[] d_gargs = method.GetGenericArguments ();
2224 TypeInferenceContext context = new TypeInferenceContext (d_gargs);
2225
2226 // A lower-bound inference is made from each argument type Uj of D
2227 // to the corresponding parameter type Tj of M
2228 for (int i = 0; i < arg_count; ++i) {
2229 Type t = pd.Types [i];
2230 if (!t.IsGenericParameter)
2231 continue;
2232
2233 context.LowerBoundInference (arguments [i].Expr.Type, t);
2234 }
2235
2236 if (!context.FixAllTypes (ec))
2237 return null;
2238
2239 return context.InferredTypeArguments;
2240 }
2241 */
2242 public override Type[] InferMethodArguments (ResolveContext ec, MethodBase method)
2243 {
2244 Type[] method_generic_args = method.GetGenericArguments ();
2245 TypeInferenceContext context = new TypeInferenceContext (method_generic_args);
2246 if (!context.UnfixedVariableExists)
2247 return Type.EmptyTypes;
2248
2249 AParametersCollection pd = TypeManager.GetParameterData (method);
2250 if (!InferInPhases (ec, context, pd))
2251 return null;
2252
2253 return context.InferredTypeArguments;
2254 }
2255
2256 //
2257 // Implements method type arguments inference
2258 //
2259 bool InferInPhases (ResolveContext ec, TypeInferenceContext tic, AParametersCollection methodParameters)
2260 {
2261 int params_arguments_start;
2262 if (methodParameters.HasParams) {
2263 params_arguments_start = methodParameters.Count - 1;
2264 } else {
2265 params_arguments_start = arg_count;
2266 }
2267
2268 Type [] ptypes = methodParameters.Types;
2269
2270 //
2271 // The first inference phase
2272 //
2273 Type method_parameter = null;
2274 for (int i = 0; i < arg_count; i++) {
2275 Argument a = arguments [i];
2276 if (a == null)
2277 continue;
2278
2279 if (i < params_arguments_start) {
2280 method_parameter = methodParameters.Types [i];
2281 } else if (i == params_arguments_start) {
2282 if (arg_count == params_arguments_start + 1 && TypeManager.HasElementType (a.Type))
2283 method_parameter = methodParameters.Types [params_arguments_start];
2284 else
2285 method_parameter = TypeManager.GetElementType (methodParameters.Types [params_arguments_start]);
2286
2287 ptypes = (Type[]) ptypes.Clone ();
2288 ptypes [i] = method_parameter;
2289 }
2290
2291 //
2292 // When a lambda expression, an anonymous method
2293 // is used an explicit argument type inference takes a place
2294 //
2295 AnonymousMethodExpression am = a.Expr as AnonymousMethodExpression;
2296 if (am != null) {
2297 if (am.ExplicitTypeInference (ec, tic, method_parameter))
2298 --score;
2299 continue;
2300 }
2301
2302 if (a.IsByRef) {
2303 score -= tic.ExactInference (a.Type, method_parameter);
2304 continue;
2305 }
2306
2307 if (a.Expr.Type == TypeManager.null_type)
2308 continue;
2309
2310 if (TypeManager.IsValueType (method_parameter)) {
2311 score -= tic.LowerBoundInference (a.Type, method_parameter);
2312 continue;
2313 }
2314
2315 //
2316 // Otherwise an output type inference is made
2317 //
2318 score -= tic.OutputTypeInference (ec, a.Expr, method_parameter);
2319 }
2320
2321 //
2322 // Part of the second phase but because it happens only once
2323 // we don't need to call it in cycle
2324 //
2325 bool fixed_any = false;
2326 if (!tic.FixIndependentTypeArguments (ec, ptypes, ref fixed_any))
2327 return false;
2328
2329 return DoSecondPhase (ec, tic, ptypes, !fixed_any);
2330 }
2331
2332 bool DoSecondPhase (ResolveContext ec, TypeInferenceContext tic, Type[] methodParameters, bool fixDependent)
2333 {
2334 bool fixed_any = false;
2335 if (fixDependent && !tic.FixDependentTypes (ec, ref fixed_any))
2336 return false;
2337
2338 // If no further unfixed type variables exist, type inference succeeds
2339 if (!tic.UnfixedVariableExists)
2340 return true;
2341
2342 if (!fixed_any && fixDependent)
2343 return false;
2344
2345 // For all arguments where the corresponding argument output types
2346 // contain unfixed type variables but the input types do not,
2347 // an output type inference is made
2348 for (int i = 0; i < arg_count; i++) {
2349
2350 // Align params arguments
2351 Type t_i = methodParameters [i >= methodParameters.Length ? methodParameters.Length - 1: i];
2352
2353 if (!TypeManager.IsDelegateType (t_i)) {
2354 if (TypeManager.DropGenericTypeArguments (t_i) != TypeManager.expression_type)
2355 continue;
2356
2357 t_i = t_i.GetGenericArguments () [0];
2358 }
2359
2360 MethodInfo mi = Delegate.GetInvokeMethod (ec.Compiler, t_i, t_i);
2361 Type rtype = mi.ReturnType;
2362
2363 #if MS_COMPATIBLE
2364 // Blablabla, because reflection does not work with dynamic types
2365 Type[] g_args = t_i.GetGenericArguments ();
2366 rtype = g_args[rtype.GenericParameterPosition];
2367 #endif
2368
2369 if (tic.IsReturnTypeNonDependent (ec, mi, rtype))
2370 score -= tic.OutputTypeInference (ec, arguments [i].Expr, t_i);
2371 }
2372
2373
2374 return DoSecondPhase (ec, tic, methodParameters, true);
2375 }
2376 }
2377
2378 public class TypeInferenceContext
2379 {
2380 enum BoundKind
2381 {
2382 Exact = 0,
2383 Lower = 1,
2384 Upper = 2
2385 }
2386
2387 class BoundInfo
2388 {
2389 public readonly Type Type;
2390 public readonly BoundKind Kind;
2391
2392 public BoundInfo (Type type, BoundKind kind)
2393 {
2394 this.Type = type;
2395 this.Kind = kind;
2396 }
2397
2398 public override int GetHashCode ()
2399 {
2400 return Type.GetHashCode ();
2401 }
2402
2403 public override bool Equals (object obj)
2404 {
2405 BoundInfo a = (BoundInfo) obj;
2406 return Type == a.Type && Kind == a.Kind;
2407 }
2408 }
2409
2410 readonly Type[] unfixed_types;
2411 readonly Type[] fixed_types;
2412 readonly ArrayList[] bounds;
2413 bool failed;
2414
2415 public TypeInferenceContext (Type[] typeArguments)
2416 {
2417 if (typeArguments.Length == 0)
2418 throw new ArgumentException ("Empty generic arguments");
2419
2420 fixed_types = new Type [typeArguments.Length];
2421 for (int i = 0; i < typeArguments.Length; ++i) {
2422 if (typeArguments [i].IsGenericParameter) {
2423 if (bounds == null) {
2424 bounds = new ArrayList [typeArguments.Length];
2425 unfixed_types = new Type [typeArguments.Length];
2426 }
2427 unfixed_types [i] = typeArguments [i];
2428 } else {
2429 fixed_types [i] = typeArguments [i];
2430 }
2431 }
2432 }
2433
2434 //
2435 // Used together with AddCommonTypeBound fo implement
2436 // 7.4.2.13 Finding the best common type of a set of expressions
2437 //
2438 public TypeInferenceContext ()
2439 {
2440 fixed_types = new Type [1];
2441 unfixed_types = new Type [1];
2442 unfixed_types[0] = InternalType.Arglist; // it can be any internal type
2443 bounds = new ArrayList [1];
2444 }
2445
2446 public Type[] InferredTypeArguments {
2447 get {
2448 return fixed_types;
2449 }
2450 }
2451
2452 public void AddCommonTypeBound (Type type)
2453 {
2454 AddToBounds (new BoundInfo (type, BoundKind.Lower), 0);
2455 }
2456
2457 void AddToBounds (BoundInfo bound, int index)
2458 {
2459 //
2460 // Some types cannot be used as type arguments
2461 //
2462 if (bound.Type == TypeManager.void_type || bound.Type.IsPointer)
2463 return;
2464
2465 ArrayList a = bounds [index];
2466 if (a == null) {
2467 a = new ArrayList ();
2468 bounds [index] = a;
2469 } else {
2470 if (a.Contains (bound))
2471 return;
2472 }
2473
2474 //
2475 // SPEC: does not cover type inference using constraints
2476 //
2477 //if (TypeManager.IsGenericParameter (t)) {
2478 // GenericConstraints constraints = TypeManager.GetTypeParameterConstraints (t);
2479 // if (constraints != null) {
2480 // //if (constraints.EffectiveBaseClass != null)
2481 // // t = constraints.EffectiveBaseClass;
2482 // }
2483 //}
2484 a.Add (bound);
2485 }
2486
2487 bool AllTypesAreFixed (Type[] types)
2488 {
2489 foreach (Type t in types) {
2490 if (t.IsGenericParameter) {
2491 if (!IsFixed (t))
2492 return false;
2493 continue;
2494 }
2495
2496 if (t.IsGenericType)
2497 return AllTypesAreFixed (t.GetGenericArguments ());
2498 }
2499
2500 return true;
2501 }
2502
2503 //
2504 // 26.3.3.8 Exact Inference
2505 //
2506 public int ExactInference (Type u, Type v)
2507 {
2508 // If V is an array type
2509 if (v.IsArray) {
2510 if (!u.IsArray)
2511 return 0;
2512
2513 if (u.GetArrayRank () != v.GetArrayRank ())
2514 return 0;
2515
2516 return ExactInference (TypeManager.GetElementType (u), TypeManager.GetElementType (v));
2517 }
2518
2519 // If V is constructed type and U is constructed type
2520 if (v.IsGenericType && !v.IsGenericTypeDefinition) {
2521 if (!u.IsGenericType)
2522 return 0;
2523
2524 Type [] ga_u = u.GetGenericArguments ();
2525 Type [] ga_v = v.GetGenericArguments ();
2526 if (ga_u.Length != ga_v.Length)
2527 return 0;
2528
2529 int score = 0;
2530 for (int i = 0; i < ga_u.Length; ++i)
2531 score += ExactInference (ga_u [i], ga_v [i]);
2532
2533 return score > 0 ? 1 : 0;
2534 }
2535
2536 // If V is one of the unfixed type arguments
2537 int pos = IsUnfixed (v);
2538 if (pos == -1)
2539 return 0;
2540
2541 AddToBounds (new BoundInfo (u, BoundKind.Exact), pos);
2542 return 1;
2543 }
2544
2545 public bool FixAllTypes (ResolveContext ec)
2546 {
2547 for (int i = 0; i < unfixed_types.Length; ++i) {
2548 if (!FixType (ec, i))
2549 return false;
2550 }
2551 return true;
2552 }
2553
2554 //
2555 // All unfixed type variables Xi are fixed for which all of the following hold:
2556 // a, There is at least one type variable Xj that depends on Xi
2557 // b, Xi has a non-empty set of bounds
2558 //
2559 public bool FixDependentTypes (ResolveContext ec, ref bool fixed_any)
2560 {
2561 for (int i = 0; i < unfixed_types.Length; ++i) {
2562 if (unfixed_types[i] == null)
2563 continue;
2564
2565 if (bounds[i] == null)
2566 continue;
2567
2568 if (!FixType (ec, i))
2569 return false;
2570
2571 fixed_any = true;
2572 }
2573
2574 return true;
2575 }
2576
2577 //
2578 // All unfixed type variables Xi which depend on no Xj are fixed
2579 //
2580 public bool FixIndependentTypeArguments (ResolveContext ec, Type[] methodParameters, ref bool fixed_any)
2581 {
2582 ArrayList types_to_fix = new ArrayList (unfixed_types);
2583 for (int i = 0; i < methodParameters.Length; ++i) {
2584 Type t = methodParameters[i];
2585
2586 if (!TypeManager.IsDelegateType (t)) {
2587 if (TypeManager.DropGenericTypeArguments (t) != TypeManager.expression_type)
2588 continue;
2589
2590 t = t.GetGenericArguments () [0];
2591 }
2592
2593 if (t.IsGenericParameter)
2594 continue;
2595
2596 MethodInfo invoke = Delegate.GetInvokeMethod (ec.Compiler, t, t);
2597 Type rtype = invoke.ReturnType;
2598 if (!rtype.IsGenericParameter && !rtype.IsGenericType)
2599 continue;
2600
2601 #if MS_COMPATIBLE
2602 // Blablabla, because reflection does not work with dynamic types
2603 if (rtype.IsGenericParameter) {
2604 Type [] g_args = t.GetGenericArguments ();
2605 rtype = g_args [rtype.GenericParameterPosition];
2606 }
2607 #endif
2608 // Remove dependent types, they cannot be fixed yet
2609 RemoveDependentTypes (types_to_fix, rtype);
2610 }
2611
2612 foreach (Type t in types_to_fix) {
2613 if (t == null)
2614 continue;
2615
2616 int idx = IsUnfixed (t);
2617 if (idx >= 0 && !FixType (ec, idx)) {
2618 return false;
2619 }
2620 }
2621
2622 fixed_any = types_to_fix.Count > 0;
2623 return true;
2624 }
2625
2626 //
2627 // 26.3.3.10 Fixing
2628 //
2629 public bool FixType (ResolveContext ec, int i)
2630 {
2631 // It's already fixed
2632 if (unfixed_types[i] == null)
2633 throw new InternalErrorException ("Type argument has been already fixed");
2634
2635 if (failed)
2636 return false;
2637
2638 ArrayList candidates = (ArrayList)bounds [i];
2639 if (candidates == null)
2640 return false;
2641
2642 if (candidates.Count == 1) {
2643 unfixed_types[i] = null;
2644 Type t = ((BoundInfo) candidates[0]).Type;
2645 if (t == TypeManager.null_type)
2646 return false;
2647
2648 fixed_types [i] = t;
2649 return true;
2650 }
2651
2652 //
2653 // Determines a unique type from which there is
2654 // a standard implicit conversion to all the other
2655 // candidate types.
2656 //
2657 Type best_candidate = null;
2658 int cii;
2659 int candidates_count = candidates.Count;
2660 for (int ci = 0; ci < candidates_count; ++ci) {
2661 BoundInfo bound = (BoundInfo)candidates [ci];
2662 for (cii = 0; cii < candidates_count; ++cii) {
2663 if (cii == ci)
2664 continue;
2665
2666 BoundInfo cbound = (BoundInfo) candidates[cii];
2667
2668 // Same type parameters with different bounds
2669 if (cbound.Type == bound.Type) {
2670 if (bound.Kind != BoundKind.Exact)
2671 bound = cbound;
2672
2673 continue;
2674 }
2675
2676 if (bound.Kind == BoundKind.Exact || cbound.Kind == BoundKind.Exact) {
2677 if (cbound.Kind != BoundKind.Exact) {
2678 if (!Convert.ImplicitConversionExists (ec, new TypeExpression (cbound.Type, Location.Null), bound.Type)) {
2679 break;
2680 }
2681
2682 continue;
2683 }
2684
2685 if (bound.Kind != BoundKind.Exact) {
2686 if (!Convert.ImplicitConversionExists (ec, new TypeExpression (bound.Type, Location.Null), cbound.Type)) {
2687 break;
2688 }
2689
2690 bound = cbound;
2691 continue;
2692 }
2693
2694 break;
2695 }
2696
2697 if (bound.Kind == BoundKind.Lower) {
2698 if (!Convert.ImplicitConversionExists (ec, new TypeExpression (cbound.Type, Location.Null), bound.Type)) {
2699 break;
2700 }
2701 } else {
2702 if (!Convert.ImplicitConversionExists (ec, new TypeExpression (bound.Type, Location.Null), cbound.Type)) {
2703 break;
2704 }
2705 }
2706 }
2707
2708 if (cii != candidates_count)
2709 continue;
2710
2711 if (best_candidate != null && best_candidate != bound.Type)
2712 return false;
2713
2714 best_candidate = bound.Type;
2715 }
2716
2717 if (best_candidate == null)
2718 return false;
2719
2720 unfixed_types[i] = null;
2721 fixed_types[i] = best_candidate;
2722 return true;
2723 }
2724
2725 //
2726 // Uses inferred types to inflate delegate type argument
2727 //
2728 public Type InflateGenericArgument (Type parameter)
2729 {
2730 if (parameter.IsGenericParameter) {
2731 //
2732 // Inflate method generic argument (MVAR) only
2733 //
2734 if (parameter.DeclaringMethod == null)
2735 return parameter;
2736
2737 return fixed_types [parameter.GenericParameterPosition];
2738 }
2739
2740 if (parameter.IsGenericType) {
2741 Type [] parameter_targs = parameter.GetGenericArguments ();
2742 for (int ii = 0; ii < parameter_targs.Length; ++ii) {
2743 parameter_targs [ii] = InflateGenericArgument (parameter_targs [ii]);
2744 }
2745 return parameter.GetGenericTypeDefinition ().MakeGenericType (parameter_targs);
2746 }
2747
2748 return parameter;
2749 }
2750
2751 //
2752 // Tests whether all delegate input arguments are fixed and generic output type
2753 // requires output type inference
2754 //
2755 public bool IsReturnTypeNonDependent (ResolveContext ec, MethodInfo invoke, Type returnType)
2756 {
2757 if (returnType.IsGenericParameter) {
2758 if (IsFixed (returnType))
2759 return false;
2760 } else if (returnType.IsGenericType) {
2761 if (TypeManager.IsDelegateType (returnType)) {
2762 invoke = Delegate.GetInvokeMethod (ec.Compiler, returnType, returnType);
2763 return IsReturnTypeNonDependent (ec, invoke, invoke.ReturnType);
2764 }
2765
2766 Type[] g_args = returnType.GetGenericArguments ();
2767
2768 // At least one unfixed return type has to exist
2769 if (AllTypesAreFixed (g_args))
2770 return false;
2771 } else {
2772 return false;
2773 }
2774
2775 // All generic input arguments have to be fixed
2776 AParametersCollection d_parameters = TypeManager.GetParameterData (invoke);
2777 return AllTypesAreFixed (d_parameters.Types);
2778 }
2779
2780 bool IsFixed (Type type)
2781 {
2782 return IsUnfixed (type) == -1;
2783 }
2784
2785 int IsUnfixed (Type type)
2786 {
2787 if (!type.IsGenericParameter)
2788 return -1;
2789
2790 //return unfixed_types[type.GenericParameterPosition] != null;
2791 for (int i = 0; i < unfixed_types.Length; ++i) {
2792 if (unfixed_types [i] == type)
2793 return i;
2794 }
2795
2796 return -1;
2797 }
2798
2799 //
2800 // 26.3.3.9 Lower-bound Inference
2801 //
2802 public int LowerBoundInference (Type u, Type v)
2803 {
2804 return LowerBoundInference (u, v, false);
2805 }
2806
2807 //
2808 // Lower-bound (false) or Upper-bound (true) inference based on inversed argument
2809 //
2810 int LowerBoundInference (Type u, Type v, bool inversed)
2811 {
2812 // If V is one of the unfixed type arguments
2813 int pos = IsUnfixed (v);
2814 if (pos != -1) {
2815 AddToBounds (new BoundInfo (u, inversed ? BoundKind.Upper : BoundKind.Lower), pos);
2816 return 1;
2817 }
2818
2819 // If U is an array type
2820 if (u.IsArray) {
2821 int u_dim = u.GetArrayRank ();
2822 Type v_i;
2823 Type u_i = TypeManager.GetElementType (u);
2824
2825 if (v.IsArray) {
2826 if (u_dim != v.GetArrayRank ())
2827 return 0;
2828
2829 v_i = TypeManager.GetElementType (v);
2830
2831 if (TypeManager.IsValueType (u_i))
2832 return ExactInference (u_i, v_i);
2833
2834 return LowerBoundInference (u_i, v_i, inversed);
2835 }
2836
2837 if (u_dim != 1)
2838 return 0;
2839
2840 if (v.IsGenericType) {
2841 Type g_v = v.GetGenericTypeDefinition ();
2842 if ((g_v != TypeManager.generic_ilist_type) && (g_v != TypeManager.generic_icollection_type) &&
2843 (g_v != TypeManager.generic_ienumerable_type))
2844 return 0;
2845
2846 v_i = TypeManager.TypeToCoreType (TypeManager.GetTypeArguments (v) [0]);
2847 if (TypeManager.IsValueType (u_i))
2848 return ExactInference (u_i, v_i);
2849
2850 return LowerBoundInference (u_i, v_i);
2851 }
2852 } else if (v.IsGenericType && !v.IsGenericTypeDefinition) {
2853 //
2854 // if V is a constructed type C<V1..Vk> and there is a unique type C<U1..Uk>
2855 // such that U is identical to, inherits from (directly or indirectly),
2856 // or implements (directly or indirectly) C<U1..Uk>
2857 //
2858 ArrayList u_candidates = new ArrayList ();
2859 if (u.IsGenericType)
2860 u_candidates.Add (u);
2861
2862 for (Type t = u.BaseType; t != null; t = t.BaseType) {
2863 if (t.IsGenericType && !t.IsGenericTypeDefinition)
2864 u_candidates.Add (t);
2865 }
2866
2867 // TODO: Implement GetGenericInterfaces only and remove
2868 // the if from foreach
2869 u_candidates.AddRange (TypeManager.GetInterfaces (u));
2870
2871 Type open_v = v.GetGenericTypeDefinition ();
2872 Type [] unique_candidate_targs = null;
2873 Type [] ga_v = v.GetGenericArguments ();
2874 foreach (Type u_candidate in u_candidates) {
2875 if (!u_candidate.IsGenericType || u_candidate.IsGenericTypeDefinition)
2876 continue;
2877
2878 if (TypeManager.DropGenericTypeArguments (u_candidate) != open_v)
2879 continue;
2880
2881 //
2882 // The unique set of types U1..Uk means that if we have an interface I<T>,
2883 // class U : I<int>, I<long> then no type inference is made when inferring
2884 // type I<T> by applying type U because T could be int or long
2885 //
2886 if (unique_candidate_targs != null) {
2887 Type[] second_unique_candidate_targs = u_candidate.GetGenericArguments ();
2888 if (TypeManager.IsEqual (unique_candidate_targs, second_unique_candidate_targs)) {
2889 unique_candidate_targs = second_unique_candidate_targs;
2890 continue;
2891 }
2892
2893 //
2894 // This should always cause type inference failure
2895 //
2896 failed = true;
2897 return 1;
2898 }
2899
2900 unique_candidate_targs = u_candidate.GetGenericArguments ();
2901 }
2902
2903 if (unique_candidate_targs != null) {
2904 Type[] ga_open_v = open_v.GetGenericArguments ();
2905 int score = 0;
2906 for (int i = 0; i < unique_candidate_targs.Length; ++i) {
2907 Variance variance = TypeManager.GetTypeParameterVariance (ga_open_v [i]);
2908
2909 Type u_i = unique_candidate_targs [i];
2910 if (variance == Variance.None || TypeManager.IsValueType (u_i)) {
2911 if (ExactInference (u_i, ga_v [i]) == 0)
2912 ++score;
2913 } else {
2914 bool upper_bound = (variance == Variance.Contravariant && !inversed) ||
2915 (variance == Variance.Covariant && inversed);
2916
2917 if (LowerBoundInference (u_i, ga_v [i], upper_bound) == 0)
2918 ++score;
2919 }
2920 }
2921 return score;
2922 }
2923 }
2924
2925 return 0;
2926 }
2927
2928 //
2929 // 26.3.3.6 Output Type Inference
2930 //
2931 public int OutputTypeInference (ResolveContext ec, Expression e, Type t)
2932 {
2933 // If e is a lambda or anonymous method with inferred return type
2934 AnonymousMethodExpression ame = e as AnonymousMethodExpression;
2935 if (ame != null) {
2936 Type rt = ame.InferReturnType (ec, this, t);
2937 MethodInfo invoke = Delegate.GetInvokeMethod (ec.Compiler, t, t);
2938
2939 if (rt == null) {
2940 AParametersCollection pd = TypeManager.GetParameterData (invoke);
2941 return ame.Parameters.Count == pd.Count ? 1 : 0;
2942 }
2943
2944 Type rtype = invoke.ReturnType;
2945 #if MS_COMPATIBLE
2946 // Blablabla, because reflection does not work with dynamic types
2947 Type [] g_args = t.GetGenericArguments ();
2948 rtype = g_args [rtype.GenericParameterPosition];
2949 #endif
2950 return LowerBoundInference (rt, rtype) + 1;
2951 }
2952
2953 //
2954 // if E is a method group and T is a delegate type or expression tree type
2955 // return type Tb with parameter types T1..Tk and return type Tb, and overload
2956 // resolution of E with the types T1..Tk yields a single method with return type U,
2957 // then a lower-bound inference is made from U for Tb.
2958 //
2959 if (e is MethodGroupExpr) {
2960 // TODO: Or expression tree
2961 if (!TypeManager.IsDelegateType (t))
2962 return 0;
2963
2964 MethodInfo invoke = Delegate.GetInvokeMethod (ec.Compiler, t, t);
2965 Type rtype = invoke.ReturnType;
2966 #if MS_COMPATIBLE
2967 // Blablabla, because reflection does not work with dynamic types
2968 Type [] g_args = t.GetGenericArguments ();
2969 rtype = g_args [rtype.GenericParameterPosition];
2970 #endif
2971
2972 if (!TypeManager.IsGenericType (rtype))
2973 return 0;
2974
2975 MethodGroupExpr mg = (MethodGroupExpr) e;
2976 Arguments args = DelegateCreation.CreateDelegateMethodArguments (TypeManager.GetParameterData (invoke), e.Location);
2977 mg = mg.OverloadResolve (ec, ref args, true, e.Location);
2978 if (mg == null)
2979 return 0;
2980
2981 // TODO: What should happen when return type is of generic type ?
2982 throw new NotImplementedException ();
2983 // return LowerBoundInference (null, rtype) + 1;
2984 }
2985
2986 //
2987 // if e is an expression with type U, then
2988 // a lower-bound inference is made from U for T
2989 //
2990 return LowerBoundInference (e.Type, t) * 2;
2991 }
2992
2993 void RemoveDependentTypes (ArrayList types, Type returnType)
2994 {
2995 int idx = IsUnfixed (returnType);
2996 if (idx >= 0) {
2997 types [idx] = null;
2998 return;
2999 }
3000
3001 if (returnType.IsGenericType) {
3002 foreach (Type t in returnType.GetGenericArguments ()) {
3003 RemoveDependentTypes (types, t);
3004 }
3005 }
3006 }
3007
3008 public bool UnfixedVariableExists {
3009 get {
3010 if (unfixed_types == null)
3011 return false;
3012
3013 foreach (Type ut in unfixed_types)
3014 if (ut != null)
3015 return true;
3016 return false;
3017 }
3018 }
3019 }
3020 }
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