--- /dev/null
+// RUN: %clang_cc1 -fsyntax-only -fobjc-nonfragile-abi2 -verify %s
+
+/**
+When processing @synthesize, treat ivars in a class extension the same as ivars in the class @interface,
+and treat ivars in a superclass extension the same as ivars in the superclass @interface.
+In particular, when searching for an ivar to back an @synthesize, do look at ivars in the class's own class
+extension but ignore any ivars in superclass class extensions.
+*/
+
+@interface Super {
+ int ISA;
+}
+@end
+
+@interface Super() {
+ int Property; // expected-note {{previously declared 'Property' here}}
+}
+@end
+
+@interface SomeClass : Super {
+ int interfaceIvar1;
+ int interfaceIvar2;
+}
+@property int Property;
+@property int Property1;
+@end
+
+@interface SomeClass () {
+ int Property1;
+}
+@end
+
+@implementation SomeClass
+@synthesize Property; // expected-error {{property 'Property' attempting to use ivar 'Property' declared in super class 'Super'}}
+@synthesize Property1; // OK
+@end