Re: [PATCH 09/12] builtin/show-ref: ensure mutual exclusiveness of subcommands

> The git-show-ref(1) command has three different modes, of which one is
> implicit and the other two can be chosen explicitly by passing a flag.
> But while these modes are standalone and cause us to execute completely
> separate code paths, we gladly accept the case where a user asks for
> both `--exclude-existing` and `--verify` at the same time even though it
> is not obvious what will happen. Spoiler: we ignore `--verify` and
> execute the `--exclude-existing` mode.
>
> Let's explicitly detect this invalid usage and die in case both modes
> were requested.
>
> Signed-off-by: Patrick Steinhardt <ps@pks.im>
> ---
> diff --git a/builtin/show-ref.c b/builtin/show-ref.c
> @@ -269,6 +269,9 @@ int cmd_show_ref(int argc, const char **argv, const char *prefix)
> +       if ((!!exclude_existing_opts.enabled + !!verify) > 1)
> +               die(_("only one of --exclude-existing or --verify can be given"));