From: Junio C Hamano <gitster@pobox.com>
Date: Mon, 22 Sep 2025 15:54:34 GMT
Subject: Re: [PATCH 4/4] refs: do not clobber dangling symrefs
Message-ID: <xmqqwm5qv5xh.fsf@gitster.g>
In-Reply-To: <20250922122332.584428-1-toon@iotcl.com>

Toon Claes <toon@iotcl.com> writes:

> We use `update FOO_HEAD 000...000 000..000` to delete a symref, if that symref
> is dangling (otherwise the old oid would have resolved to something). I've
> attached a patch that would allow this (on top of your patches). Do you think it
> makes sense to allow this scenario?
> ...
> +	test_when_finished "git update-ref -d refs/heads/dangling" &&
> +	git symbolic-ref refs/heads/dangling refs/heads/does-not-exist &&
> +	echo "update refs/heads/dangling $Z $Z" >stdin &&
> +	git update-ref --no-deref --stdin <stdin &&

"git update-ref --help" seems to show that the "--stdin" mode has a
separate command that is designed for exactly the purpose of removing
a symbolic ref, though.  If you are changing the semantics of "update"
to make it safer while dealing with a dangling symbolic ref, do you
also need to touch the code path that handles "symref-delete" command?

> +	test_must_fail git rev-parse --verify refs/heads/dangling &&
> +	test_must_fail git rev-parse --verify refs/heads/does-not-exist
> +'
> +
>  test_done
> --
> 2.51.0