+
+ dnl Check for declarations of anything we want to poison if the
+ dnl corresponding gnulib module is not in use.
+ gl_WARN_ON_USE_PREPARE([[#include <unistd.h>
+/* Some systems declare various items in the wrong headers. */
+#ifndef __GLIBC__
+# include <fcntl.h>
+# include <stdio.h>
+# include <stdlib.h>
+# if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
+# include <io.h>
+# endif
+#endif
+ ]], [chown dup2 dup3 environ euidaccess faccessat fchdir fchownat
+ fsync ftruncate getcwd getdomainname getdtablesize getgroups
+ gethostname getlogin getlogin_r getpagesize getusershell setusershell
+ endusershell lchown link linkat lseek pipe2 pread readlink readlinkat
+ rmdir sleep symlink symlinkat unlink unlinkat usleep])