ax_posix.m4

AC_DEFUN([AX_POSIX], [
	AC_MSG_CHECKING([for POSIX 2008 support])
	AC_COMPILE_IFELSE([AC_LANG_SOURCE([
		#define _POSIX_C_SOURCE 200809L
		#include <unistd.h>
		# if !defined(_POSIX_VERSION) || _POSIX_VERSION < 200809L
		# error "Not POSIX 2008"
		#endif
		int main() { return 0; }
	])], [
		AC_MSG_RESULT([yes])
		AC_DEFINE([_POSIX_SOURCE], [1], [defined if POSIX is available])
		AC_DEFINE([_POSIX_C_SOURCE], [200809L], [defined if POSIX 2008 is available])
	], [
		AC_MSG_RESULT([no])
		AC_MSG_ERROR([POSIX 2008 support is required])
	])
])