Re: [PATCH v3 2/4] remote: use remote_state parameter internally

From: Junio C Hamano <gitster@pobox.com>
Date: Oct 25, 2021, 20:33 UTC
Message-ID: <xmqqzgqwzvwx.fsf@gitster.g>
In-Reply-To: <kl6lzgqwaocl.fsf@chooglen-macbookpro.roam.corp.google.com>

Glen Choo <chooglen@google.com> writes:

Show 11 quoted lines

> Glen Choo <chooglen@google.com> writes:
>
>>> The caller is remote_get_1(); this funciton was called with
>>> "current_branch", which can be NULL until you have a repository and
>>> you've called read_config(), but otherwise shouldn't be.
>
> One possible culprit is working with detached HEAD, are you pushing with
> detached HEAD?
>
> "current_branch" is allowed to be NULL when HEAD does not point to a
> branch.

Good point. It is a good justification to make the remote_state available to the function, as branch==NULL that signals "there is no current branch in the repository" cannot be dereferenced to get to either the repository or the remote_state, yet the function needs access to remote_state even when branch==NULL.

What "branch" is pushremote_for_branch() meant to take? Is there a caller that asks a hypothetical "I know this is not a branch that is the current branch in the repository, but to which remote would we push if this branch _were_ the current one?" (and passes NULL to mean "there is a checked out branch, but what happens if our HEAD were detached?") question? Even if there isn't currently, do we want to add such callers in the future?

If the answer is yes, then the function need to take both branch and remote_state as two separate parameters. If the answer is no (i.e. we never ask hypothetical questions, we just ask what we should do in the current, real, state), then the function can just take the remote_state and remote_state->branch being NULL would be used as a signal that the HEAD is detached. I suspect it is the former, as this information is used in string-name-to-object translation for "topic@{push}" in object-name.c::interpret_branch_mark() function.

> However, if you are not using detached HEAD, the problem might be
> elsewhere..

I just checked. The repository the push is run in is bare and its HEAD is detached, pointing at a commit directly.