AC_CACHE_CHECK([whether open can visit directories],
[gl_cv_func_open_directory_works],
[AC_RUN_IFELSE([AC_LANG_PROGRAM([[#include <fcntl.h>
]], [return open(".", O_RDONLY) < 0;])],
[gl_cv_func_open_directory_works=yes],
[gl_cv_func_open_directory_works=no],
AC_CACHE_CHECK([whether open can visit directories],
[gl_cv_func_open_directory_works],
[AC_RUN_IFELSE([AC_LANG_PROGRAM([[#include <fcntl.h>
]], [return open(".", O_RDONLY) < 0;])],
[gl_cv_func_open_directory_works=yes],
[gl_cv_func_open_directory_works=no],