Curious ObjC typechecking... bug?

Clang Frontend
#1

Why does the following pass Clang's type checker?

@protocol PF
-(int)pf;
@end

@interface Foo : NSObject <PF>
- (double) pf;
@end

@implementation Foo
- (double) pf { return 2.0; }
@end

It seems to me that there should at least be a "return type differs" warning because 'pf' in the protocol has a different signature than 'pf' in the interface... if not an error, because 'Foo' doesn't really implement 'PF'.

I could also be missing some language rule here. Thoughts?

Jon

#2

Try -Woverriding-method-mismatch option.

- Fariborz

#3

Try *-Woverriding-method-mismatch option.*
*

Ah, thanks.

Is there a useful pattern that's the reason why that one isn't on by default?

Cheers,

Jon

#4

It is plausible that people may want to override protocol’s methods in adapting classes with
different types. But I am not sure if this is the reason or it is legacy of gcc not insisting on matching types.

- Fariborz