http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54847
--- Comment #25 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-10-08 10:59:46 UTC --- N.B. prior to POSIX 2008 nanosleep was part of the Timers option, if OS X supports that it should define _POSIX_TIMERS to 0, -1 or 200112L to indicate it's supported. POSIX 2008 moves the Timers functionality to the Base spec, and requires that _POSIX_TIMERS is defined to 200809L. In eiher case, a POSIX system supporting nanosleep should define _POSIX_TIMERS. The configure checks are based on well-documented, publicly-available standards, please try to understand them instead of proposing patches based on the misunderstanding that adding "struct" makes any difference to anything.