http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59177
--- Comment #3 from Andy Lutomirski <luto at mit dot edu> --- I can't get gcc trunk to build right now, but I just distcleaned and rebuilt the 4.8 branch truck on Fedora 19, which has glibc-2.17-19.fc19.x86_64. It defines _GLIBCXX_USE_CLOCK_GETTIME_SYSCALL. This happens because: configure:19349: checking for clock_gettime, nanosleep and sched_yield configure:19378: result: no I think that the underlying problem is that --enable-libstdcxx-time defaults to "no". Shouldn't it default to "yes" (and hence run the fancy configure checks)? Configuring with ./configure --enable-libstdcxx-time does the right thing.