+
+ if test "x$cf_cv_gnu_library_219" = xyes; then
+ cf_save="$CPPFLAGS"
+ AC_CACHE_CHECK(if _XOPEN_SOURCE=$cf_gnu_xopen_source works with _DEFAULT_SOURCE,cf_cv_gnu_dftsrc_219,[
+ CF_ADD_CFLAGS(-D_DEFAULT_SOURCE -D_XOPEN_SOURCE=$cf_gnu_xopen_source)
+ AC_TRY_COMPILE([
+ #include <limits.h>
+ #include <sys/types.h>
+ ],[
+ #if (_XOPEN_SOURCE >= $cf_gnu_xopen_source) && (MB_LEN_MAX > 1)
+ return 0;
+ #else
+ # error GNU C library is too old
+ #endif],
+ [cf_cv_gnu_dftsrc_219=yes],
+ [cf_cv_gnu_dftsrc_219=no])
+ ])
+ test "x$cf_cv_gnu_dftsrc_219" = "xyes" || CPPFLAGS="$cf_save"
+ else
+ cf_cv_gnu_dftsrc_219=maybe
+ fi
+
+ if test "x$cf_cv_gnu_dftsrc_219" != xyes; then
+
+ AC_CACHE_CHECK(if we must define _GNU_SOURCE,cf_cv_gnu_source,[
+ AC_TRY_COMPILE([#include <sys/types.h>],[
+ #ifndef _XOPEN_SOURCE
+ #error expected _XOPEN_SOURCE to be defined
+ #endif],
+ [cf_cv_gnu_source=no],
+ [cf_save="$CPPFLAGS"
+ CF_ADD_CFLAGS(-D_GNU_SOURCE)
+ AC_TRY_COMPILE([#include <sys/types.h>],[
+ #ifdef _XOPEN_SOURCE
+ #error expected _XOPEN_SOURCE to be undefined
+ #endif],
+ [cf_cv_gnu_source=no],
+ [cf_cv_gnu_source=yes])
+ CPPFLAGS="$cf_save"
+ ])
+ ])
+
+ if test "$cf_cv_gnu_source" = yes
+ then
+ AC_CACHE_CHECK(if we should also define _DEFAULT_SOURCE,cf_cv_default_source,[
+ CF_APPEND_TEXT(CPPFLAGS,-D_GNU_SOURCE)
+ AC_TRY_COMPILE([#include <sys/types.h>],[
+ #ifdef _DEFAULT_SOURCE
+ #error expected _DEFAULT_SOURCE to be undefined
+ #endif],
+ [cf_cv_default_source=no],
+ [cf_cv_default_source=yes])
+ ])
+ if test "$cf_cv_default_source" = yes
+ then
+ CF_APPEND_TEXT(CPPFLAGS,-D_DEFAULT_SOURCE)
+ fi
+ fi
+ fi
+