zfs: Disable -Wunused-variable for environ in main in zfs_main.c.

[jhb]

Summary

There is an extern declaration of the global variable environ (which
has no portable header that defines it) that is unused on FreeBSD due
to zfs_setproctitle_init() being a stub.

Reported by: GCC

[rew]

would it be worth the effort to fix this upstream? something like:

diff --git a/cmd/zfs/zfs_main.c b/cmd/zfs/zfs_main.c
index 9d48b2b32..2e48ca680 100644
--- a/cmd/zfs/zfs_main.c
+++ b/cmd/zfs/zfs_main.c
@@ -8672,7 +8672,6 @@ main(int argc, char **argv)
        int i = 0;
        const char *cmdname;
        char **newargv;
-       extern char **environ;

        (void) setlocale(LC_ALL, "");
        (void) setlocale(LC_NUMERIC, "C");
diff --git a/include/libzutil.h b/include/libzutil.h
index 4d4bddaad..948ac08cd 100644
--- a/include/libzutil.h
+++ b/include/libzutil.h
@@ -183,6 +183,7 @@ _LIBZUTIL_H int printf_color(const char *color, const char *format, ...);
 _LIBZUTIL_H const char *zfs_basename(const char *path);
 _LIBZUTIL_H ssize_t zfs_dirnamelen(const char *path);
 #ifdef __linux__
+extern char **environ;
 _LIBZUTIL_H void zfs_setproctitle_init(int argc, char *argv[], char *envp[]);
 _LIBZUTIL_H void zfs_setproctitle(const char *fmt, ...);
 #else

[emaste]

would it be worth the effort to fix this upstream?

I prefer that if someone's willing to shepherd it in, but in the meantime adding the warning flag is sensible.

[rew]

In D38231#868911, @emaste wrote:

would it be worth the effort to fix this upstream?

I prefer that if someone's willing to shepherd it in, but in the meantime adding the warning flag is sensible.

https://github.com/openzfs/zfs/pull/14441

[jhb]

For now I've merged this change, but it should be reverted once an upstream fix is merged back to main.

[emaste]

Upstream change has been merged in, so it's now just a matter of waiting until it comes back to FreeBSD