AC_CACHE_CHECK([whether fflush works on input streams],
[gl_cv_func_fflush_stdin],
[echo hello world > conftest.txt
AC_RUN_IFELSE([AC_LANG_PROGRAM(
[[
#include <stdio.h>
AC_CACHE_CHECK([whether fflush works on input streams],
[gl_cv_func_fflush_stdin],
[echo hello world > conftest.txt
AC_RUN_IFELSE([AC_LANG_PROGRAM(
[[
#include <stdio.h>