2 files changed, 20 insertions, 0 deletions
diff --git a/clang/lib/Sema/SemaDeclObjC.cpp b/clang/lib/Sema/SemaDeclObjC.cpp
index 299f101bdbf..80d46bcabbe 100644
--- a/clang/lib/Sema/SemaDeclObjC.cpp
+++ b/clang/lib/Sema/SemaDeclObjC.cpp
@@ -835,6 +835,9 @@ bool Sema::isPropertyReadonly(ObjCPropertyDecl *PDecl,
         ObjCImplementations[IDecl->getIdentifier()])
     if (ImpDecl->getInstanceMethod(PDecl->getSetterName()))
       return false;
+  // If all fails, look at the super class.
+  if (ObjCInterfaceDecl *SIDecl = IDecl->getSuperClass())
+    return isPropertyReadonly(PDecl, SIDecl);
   return true;
 }
 
diff --git a/clang/test/SemaObjC/writable-property-in-superclass.m b/clang/test/SemaObjC/writable-property-in-superclass.m
new file mode 100644
index 00000000000..182b1c47bb3
--- /dev/null
+++ b/clang/test/SemaObjC/writable-property-in-superclass.m
@@ -0,0 +1,17 @@
+// RUN: clang-cc  -fsyntax-only -verify %s
+
+@interface MessageStore
+@property (assign, readonly) int P;
+@end
+
+@interface MessageStore (CAT)
+@property (assign) int P;
+@end
+
+@interface  NeXTMbox : MessageStore
+@end
+
+@implementation NeXTMbox
+- (void) Meth { self.P = 1; }
+@end
+