http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54847
--- Comment #30 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-10-08 14:47:20 UTC --- Can we take a step back and determine what exactly this PR is about? Several of the comments make incorrect statements about the status quo, so I want to get the report clear. I don't understand comment 1. Contrary to comment 2, the configure check for sched_yield does *not* check _POSIX_TIMERS, so sched_yield should be used on darwin when --enable-libstdcxx-time is used. Is _GLIBCXX_USE_SCHED_YIELD defined on darwin when the --enable-libstdcxx-time option is used? That option *doesn't* enable the use of clock_gettime on darwin, because the function isn't available. That's unavoidable. That option does enable checking for nanosleep, but the check fails on darwin because nanosleep is available but darwin doesn't identify itself as supporting the Timers option (presumably because the rest of the option isn't supported.) If that's correct, could we change the bug description to be more accurate?