source: kBuild/vendor/grep/current/gnulib-tests/test-sys_select.c

/* Test of <sys/select.h> substitute.
   Copyright (C) 2007-2021 Free Software Foundation, Inc.

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */

/* Written by Bruno Haible <bruno@clisp.org>, 2007.  */

#include <config.h>

#include <sys/select.h>

#include "signature.h"

/* The following may be macros without underlying functions, so only
   check signature if they are not macros.  */
#ifndef FD_CLR
SIGNATURE_CHECK (FD_CLR, void, (int, fd_set *));
#endif
#ifndef FD_ISSET
SIGNATURE_CHECK (FD_ISSET, void, (int, fd_set *));
#endif
#ifndef FD_SET
SIGNATURE_CHECK (FD_SET, int, (int, fd_set *));
#endif
#ifndef FD_ZERO
SIGNATURE_CHECK (FD_ZERO, void, (fd_set *));
#endif

/* Check that the 'struct timeval' type is defined.  */
struct timeval a;

/* Check that a.tv_sec is wide enough to hold a time_t, ignoring
   signedness issues.  */
typedef int verify_tv_sec_type[sizeof (time_t) <= sizeof (a.tv_sec) ? 1 : -1];

/* Check that sigset_t is defined.  */
sigset_t t2;

int
main (void)
{
  /* Check that FD_ZERO can be used.  This should not yield a warning
     such as "warning: implicit declaration of function 'memset'".  */
  fd_set fds;
  FD_ZERO (&fds);

  return 0;
}