+dnl CF_TRY_XOPEN_SOURCE version: 1 updated: 2011/10/30 17:09:50
+dnl -------------------
+dnl If _XOPEN_SOURCE is not defined in the compile environment, check if we
+dnl can define it successfully.
+AC_DEFUN([CF_TRY_XOPEN_SOURCE],[
+AC_CACHE_CHECK(if we should define _XOPEN_SOURCE,cf_cv_xopen_source,[
+ AC_TRY_COMPILE([
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+],[
+#ifndef _XOPEN_SOURCE
+make an error
+#endif],
+ [cf_cv_xopen_source=no],
+ [cf_save="$CPPFLAGS"
+ CPPFLAGS="$CPPFLAGS -D_XOPEN_SOURCE=$cf_XOPEN_SOURCE"
+ AC_TRY_COMPILE([
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+],[
+#ifdef _XOPEN_SOURCE
+make an error
+#endif],
+ [cf_cv_xopen_source=no],
+ [cf_cv_xopen_source=$cf_XOPEN_SOURCE])
+ CPPFLAGS="$cf_save"
+ ])
+])
+
+if test "$cf_cv_xopen_source" != no ; then
+ CF_REMOVE_DEFINE(CFLAGS,$CFLAGS,_XOPEN_SOURCE)
+ CF_REMOVE_DEFINE(CPPFLAGS,$CPPFLAGS,_XOPEN_SOURCE)
+ cf_temp_xopen_source="-D_XOPEN_SOURCE=$cf_cv_xopen_source"
+ CF_ADD_CFLAGS($cf_temp_xopen_source)
+fi
+])
+dnl ---------------------------------------------------------------------------