http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54847
--- Comment #32 from Jack Howarth <howarth at nitro dot med.uc.edu> 2012-10-08 15:31:30 UTC --- Would something simple like... Index: acinclude.m4 =================================================================== --- acinclude.m4 (revision 192212) +++ acinclude.m4 (working copy) @@ -1236,7 +1236,7 @@ AC_DEFUN([GLIBCXX_ENABLE_LIBSTDCXX_TIME] [#include <unistd.h> #include <time.h> ], - [#if _POSIX_TIMERS > 0 + [#if (_POSIX_TIMERS > 0 || defined(__APPLE__)) timespec tp; #endif clock_gettime(CLOCK_REALTIME, &tp); be acceptable? We have the options of __APPLE_CC__, __APPLE__ or __MACH__ from the preprocessor defines emitted by FSF gcc trunk on darwin.