http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59188
--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> --- glibc (at least the 2.17 I have around) doesn't have sigsetjmp function at all, it only conditionally has sigsetjmp as a macro: #ifdef __USE_POSIX ... /* Store the calling environment in ENV, also saving the signal mask if SAVEMASK is nonzero. Return 0. */ # define sigsetjmp(env, savemask) __sigsetjmp (env, savemask) ... #endif so extern "C" int setjmp(void *env); extern "C" int _setjmp(void *env); extern "C" int sigsetjmp(void *env); extern "C" int __sigsetjmp(void *env); DEFINE_REAL(int, setjmp, void *env) DEFINE_REAL(int, _setjmp, void *env) DEFINE_REAL(int, sigsetjmp, void *env) DEFINE_REAL(int, __sigsetjmp, void *env) is just asking for trouble. Not to mention that the arguments are wrong even for __sigsetjmp, which has two arguments rather than just one. So, if it works with clang, must be purely by accident, perhaps the difference is that __USE_POSIX is defined in one case and not in the other one, or something, but still, it can't really work in either case.
