http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54847
--- Comment #28 from Jack Howarth <howarth at nitro dot med.uc.edu> 2012-10-08 14:02:46 UTC --- It seems like there is only two possible patches here using the existing infrastructure in acinclude.m4 that would allow darwin's nanosleep() to be found when passing --enable-libstdcxx-time=yes. Either... Index: acinclude.m4 =================================================================== --- acinclude.m4 (revision 192206) +++ acinclude.m4 (working copy) @@ -1249,7 +1249,7 @@ AC_DEFUN([GLIBCXX_ENABLE_LIBSTDCXX_TIME] [#include <unistd.h> #include <time.h> ], - [#if _POSIX_TIMERS > 0 + [#if _POSIX_TIMERS != 0 timespec tp; #endif nanosleep(&tp, 0); or Index: acinclude.m4 =================================================================== --- acinclude.m4 (revision 192206) +++ acinclude.m4 (working copy) @@ -1249,10 +1249,8 @@ AC_DEFUN([GLIBCXX_ENABLE_LIBSTDCXX_TIME] [#include <unistd.h> #include <time.h> ], - [#if _POSIX_TIMERS > 0 - timespec tp; - #endif - nanosleep(&tp, 0); + [timespec tp; + nanosleep(&tp, 0); ], [ac_has_nanosleep=yes], [ac_has_nanosleep=no]) AC_MSG_RESULT($ac_has_nanosleep) Or are you going to demand that the use of pre-2008 POSIX nanosleep() be only accepted on a target-specific basis?