Re: [PATCH v2 5/5] branch -d: refuse deleting a branch which is currently checked out

[Eric Sunshine <sunshine@sunshineco.com>]

On Fri, Mar 25, 2016 at 2:28 PM, Kazuki Yamaguchi <k@rhe.jp> wrote:
> When a branch is checked out by current working tree, deleting the
> branch is forbidden. However when the branch is checked out only by
> other working trees, deleting is allowed.
> Use find_shared_symref() to check if the branch is in use, not just
> comparing with the current working tree's HEAD.
>
> Signed-off-by: Kazuki Yamaguchi <k@rhe.jp>
> ---
> diff --git a/builtin/branch.c b/builtin/branch.c
> @@ -215,16 +216,17 @@ static int delete_branches(int argc, const char **argv, int force, int kinds,
>                 int flags = 0;
>
>                 strbuf_branchname(&bname, argv[i]);
> -               if (kinds == FILTER_REFS_BRANCHES && !strcmp(head, bname.buf)) {
> +               free(name);
> +               name = mkpathdup(fmt, bname.buf);
> +
> +               if (kinds == FILTER_REFS_BRANCHES &&
> +                   find_shared_symref("HEAD", name)) {
>                         error(_("Cannot delete the branch '%s' "
> -                             "which you are currently on."), bname.buf);
> +                             "which is currently checked out."), bname.buf);

Would it be possible to do a better job of letting the user know what
went wrong by stating in which worktree(s) the branch is checked out?
My concern is that someone seeing this message might respond "huh? I
have 'master' checked out, so why is this telling me that 'foo' is
checked out", and not realize that 'foo' is in fact checked out in a
different worktree.