It is not used within paraslash and is already defined on MacOS.
#if __GNUC__ >= 3
# define inline inline __attribute__ ((always_inline))
-# define __pure __attribute__ ((pure))
# define __noreturn __attribute__ ((noreturn))
# define __malloc __attribute__ ((malloc))
# define __used __attribute__ ((used))
#else
# define inline /* no inline */
-# define __pure /* no pure */
# define __noreturn /* no noreturn */
# define __malloc /* no malloc */
# define __used /* no used */