AC_DEFUN([AX_C___ATTRIBUTE__], [

  AC_MSG_CHECKING(for __attribute__)

  AC_CACHE_VAL(ac_cv___attribute__, [

    AC_TRY_COMPILE(

      [#include <stdlib.h>

       static void foo(void) __attribute__ ((unused));

       void foo(void) { exit(1); }],

      [],

      ac_cv___attribute__=yes,

      ac_cv___attribute__=no

    )])

  if test "$ac_cv___attribute__" = "yes"; then

    AC_DEFINE(HAVE___ATTRIBUTE__, 1, [define if your compiler has __attribute__])

  fi

  AC_MSG_RESULT($ac_cv___attribute__)

])