[cfe-dev] objc_subclassing_restricted attribute bug

[Aaron Ballman via cfe-dev]

On Thu, Oct 13, 2016 at 8:30 AM, Alfred Zien via cfe-dev
<cfe-dev at lists.llvm.org> wrote:
> Hi! Found a bug. If you add objc_subclassing_restricted attribute to both
> parent and child classes it compiles without any error. So attribute appears
> to be useless, as you can't rely on it.

Do you have -Wunknown-attributes enabled? You should get a diagnostic
telling you that the unknown attribute is unsupported, as that is not
an attribute Clang understands (it's not listed in Attr.td).
(http://coliru.stacked-crooked.com/a/eb3ba9326e8648ea)

~Aaron

>
> Code to reproduce bug:
>
> #import <Foundation/Foundation.h>
>
> #define FINAL __attribute__((objc_subclassing_restricted))
>
> FINAL
> @interface Parent : NSObject
> @end
> @implementation Parent
> @end
>
> FINAL
> @interface Child : Parent
> @end
> @implementation Child
> @end
>
> int main(int argc, const char * argv[]) {
>   return 0;
> }
>
>
>
>
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