http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52680
--- Comment #4 from Matt Kline <mkline at cs dot wisc.edu> 2012-03-30 19:19:03 UTC --- Where should I specify that flag? _GLIBCXX_USE_NANOSLEEP is still undefined when I build gcc with configure CFLAGS='-O3' --disable-bootstrap --disable-multilib --enable-ibstdccxx-time=rt --enable-languages=c,c++