__builtin_mul_overflow_p  137 lib/intprops-internal.h # define _GL_HAS_BUILTIN_OVERFLOW_P __has_builtin (__builtin_mul_overflow_p)
__builtin_mul_overflow_p  183 lib/intprops.h    __builtin_mul_overflow_p (a, b, (__typeof__ ((a) * (b))) 0)