Implement variance for Objective-C type parameters.
Introduce co- and contra-variance for Objective-C type parameters,
which allows us to express that (for example) an NSArray is covariant
in its type parameter. This means that NSArray<NSMutableString *> * is
a subtype of NSArray<NSString *> *, which is expected of the immutable
Foundation collections.
Type parameters can be annotated with __covariant or __contravariant
to make them co- or contra-variant, respectively. This feature can be
detected by __has_feature(objc_generics_variance). Implements
rdar://problem/20217490.
llvm-svn: 241549
diff --git a/clang/test/PCH/objc_parameterized_classes.m b/clang/test/PCH/objc_parameterized_classes.m
index 616d4a2..0c18858 100644
--- a/clang/test/PCH/objc_parameterized_classes.m
+++ b/clang/test/PCH/objc_parameterized_classes.m
@@ -12,11 +12,11 @@
@interface NSObject
@end
-@interface PC1<T, U : NSObject *> : NSObject
+@interface PC1<__covariant T, U : NSObject *> : NSObject
// expected-note@-2{{type parameter 'U' declared here}}
@end
-@interface PC1<T, U : NSObject *> (Cat1)
+@interface PC1<__covariant T, U : NSObject *> (Cat1)
@end
typedef PC1<id, NSObject *> PC1Specialization1;
@@ -34,4 +34,12 @@
typedef PC1Specialization2<id, NSObject *> PC1Specialization4; // expected-error{{already-specialized class type 'PC1Specialization2' (aka 'PC1Specialization1<NSObject>')}}
+@interface NSString : NSObject
+@end
+
+void testCovariance(PC1<NSObject *, NSObject *> *pc1a,
+ PC1<NSString *, NSObject *> *pc1b) {
+ pc1a = pc1b;
+}
+
#endif