--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/clang/test/SemaObjC/override-nullability.m	Thu Feb 13 15:10:13 2020 +0900
@@ -0,0 +1,15 @@
+// RUN: %clang_cc1 -fobjc-arc -fobjc-runtime-has-weak -Wnonnull %s -verify
+//rdar://19211059
+
+@interface NSObject @end
+
+@interface Base : NSObject
+- (nonnull id)bad:(nullable id)obj; // expected-note 2 {{previous declaration is here}}
+- (nullable id)notAsBad:(nonnull id)obj;
+@end
+
+@interface Sub : Base
+- (nullable id)bad:(nonnull id)obj; // expected-warning {{conflicting nullability specifier on return types, 'nullable' conflicts with existing specifier 'nonnull'}} \
+                                    // expected-warning {{conflicting nullability specifier on parameter types, 'nonnull' conflicts with existing specifier 'nullable'}}
+- (nonnull id)notAsBad:(nullable id)obj;
+@end