Re: [PATCH v3 1/2] rebase: skip branch symref aliases

From: Phillip Wood <phillip.wood123@gmail.com>
Date: Jul 29, 2026, 09:31 UTC
Message-ID: <61291144-60da-4e37-83ef-fe09e91c4f51@gmail.com>
In-Reply-To: <xmqqpl07fb1u.fsf@gitster.g>

On 28/07/2026 15:23, Junio C Hamano wrote:

Show 12 quoted lines

> Phillip Wood <phillip.wood123@gmail.com> writes:
> 
>>> But stepping back a bit, is having a HEAD that is a symref and
>>> points outside "refs/heads/" an invalid state?  Why are we catering
>>> to such a configuration to begin with?
>>
>> We allow HEAD to point to anything below "refs/" - see e9cc02f0e4
>> (symbolic-ref: allow refs/<whatever> in HEAD, 2009-02-13).
> 
> But that was about a low level mechanism that must be more lenient
> to be usable as repair tools to recover from such a broken state,
> no?

It checks the new value of HEAD, not the old one so I don't think so. The commit message talks about topgit using "git symbolic-ref" to set head outside "refs/heads/" - peff had previously tried to tighten it to reject non-branch refs but that broke topgit. I've just had a quick look at the topgit code and still sets HEAD to point to "refs/top-bases/..." by default[1], although there are plans to start using "refs/heads/{top-bases}/..." instead.

>  I thought the end-user facing commands like "git checkout" have
> been tightened long ago to stop users from getting into a situation
> that needs repairing in the first place.  And that was why I asked.

Yes "git checkout" detaches HEAD if you give a non-branch ref, but external tools can still use "git symbolic-ref" to bypass that. It appears topgit's rebase command is built around "git rebase"[2] so I think we need to continue to support rebasing a non-branch HEAD.

Thanks

Phillip

[1] https://github.com/mackyle/topgit/blob/master/tg.sh#L2683 [2] https://github.com/mackyle/topgit/blob/master/tg-rebase.sh#L56