https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70217
--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> --- We can probably do something in os_defines.h like: #if __cplusplus < 201103L && __STRICT_ANSI__ #undef _GLIBCXX_USE_C99_STDIO // etc. #endif