http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53238
--- Comment #2 from Daniel Richard G. <skunk at iskunk dot org> 2012-05-04 20:33:46 UTC --- (In reply to comment #1) > You'll need to figure out why the configure test passes, most of us who work > on > that bit of code don't have access to AIX Below is the relevant excerpt from gcc-4.7.0/libstdc++-v3/acinclude.m4: ----8<---- AC_MSG_CHECKING([whether it can be safely assumed that mutex_timedlock is available]) AC_TRY_COMPILE([#include <unistd.h>], [ // In case of POSIX threads check _POSIX_TIMEOUTS. #if (defined(_PTHREADS) \ && (!defined(_POSIX_TIMEOUTS) || _POSIX_TIMEOUTS <= 0)) #error #endif ], [ac_gthread_use_mutex_timedlock=1], [ac_gthread_use_mutex_timedlock=0]) AC_DEFINE_UNQUOTED(_GTHREAD_USE_MUTEX_TIMEDLOCK, $ac_gthread_use_mutex_timedlock, [Define to 1 if mutex_timedlock is available.]) if test $ac_gthread_use_mutex_timedlock = 1 ; then res_mutex_timedlock=yes ; else res_mutex_timedlock=no ; fi AC_MSG_RESULT([$res_mutex_timedlock]) ---->8---- Neither _PTHREADS nor _POSIX_TIMEOUTS appear anywhere in /usr/include/. I'm a little mystified as to why this test is relying entirely on feature test macros, instead of checking for the existence of pthread_mutex_timedlock directly...