_POSIX_C_SOURCE    40 lib/stdio.in.h #if (defined __APPLE__ && defined __MACH__) && !defined _POSIX_C_SOURCE
_POSIX_C_SOURCE    38 lib/sys_select.in.h              && (! (defined _XOPEN_SOURCE || defined _POSIX_C_SOURCE)   \
_POSIX_C_SOURCE    52 lib/sys_select.in.h                               || defined _POSIX_C_SOURCE)               \
_POSIX_C_SOURCE    31 test/manual/etags/c-src/emacs/src/regex.h #if !defined _POSIX_C_SOURCE && !defined _POSIX_SOURCE && defined VMS