Hey all, I have the exact same problem as this old message on the gcc-help mailing list.
http://gcc.gnu.org/ml/gcc-help/2010-03/msg00114.html Since the original author did such a great job explaining it, I'm just going to paste it here: ------ I have a function like void myLog(const char *format, ...); Now I want to let the compiler check the passed parameters if they fit to the format string like printf. I know this can be done easily with the following: void myLog(const char *format, ...) __attribute__((format(printf, 1, 2))); Now my problem is: I also want to accept the "%@" specifier that is accepted in Obj-C NSStrings or NSLog. The "%@" specifier accepts Obj-C objects (NSObject or id) or Core Foundation Object References (CFTypeRef). I saw that NSLog is declared this way: void NSLog(NSString *format, ...) __attribute__((format(__NSString__, 1, 2))); Problem is that I don't have an NSString as format string parameter in my function. I have a plain old C-string (it should also work in C++ code, not only in Obj-C or Obj-C++ code). But it accepts the "%@" specifier (I am using Core Foundation in the Implementation under-the-hood). When I use the __NSString__ declaration like NSLog, gcc gives me an error message that my format parameter is not an NSString. Sure, it is not. But it doesn't matter. I just want gcc to do the format parameter checking like that. Is there any chance to get gcc check my passed parameters the "Objective-C way" with "%@" included but still having the format string passed as plain old C-string? It there any other types than __NSString__ I could try? -------- Any suggestions? Cheers, Dave
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