4.11.1 __has_attribute function-like macro

The predefined function-like macro

__has_attribute(attr)

evaluates to 1 if attr is a supported attribute. It evaluates to 0 otherwise. Example usage:

#ifndef __has_attribute // if we don't have __has_attribute, ignore it
    #define __has_attribute(x) 0
#endif
#if __has_attribute(deprecated)
   #define DEPRECATED __attribute__((deprecated))
#else
   #define DEPRECATED // attribute "deprecated" not available
#endif
void DEPRECATED old_func(int); // use the attribute if available