https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84555
--- Comment #1 from Romain Geissler <romain.geissler at amadeus dot com> --- This example emits: error: ‘char* __builtin_strncpy(char*, const char*, long unsigned int)’ output truncated before terminating nul copying 3 bytes from a string of the same length [-Werror=stringop-truncation] return __builtin_strncpy(dest, source, size); ~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~ cc1plus: all warnings being treated as errors while one would expect that no warning is emitted here.