Re: [RFC] Branches with --recurse-submodules

[Philippe Blain <levraiphilippeblain@gmail.com>]

Hi Glen,

Le 2021-11-10 à 13:21, Glen Choo a écrit :
> 
> I found some points that I should have given more attention to in the
> RFC. I'd appreciate any and all feedback :)
> 
> Glen Choo <chooglen@google.com> writes:
> 
>> In a superproject-submodule relationship there is some ambiguity in what
>> ‘checkout the branch `topic`’ should mean (does the submodule use its
>> topic branch, or the version recorded in the superproject’s gitlink?).
>> Our approach is to preserve existing semantics where reasonable - the
>> ref name refers to the superproject’s ref, just as it does without
>> --recurse-submodules.
> 
> Because a gitlink only contains a commit id, the submodule branch will
> use a plain commit id as the branch point. This gives the correct ref,
> but it gives no hints as to what the submodule branch should track.
> 
> The current thought process is to set up tracking using the ref name and
> the submodule's config. Thus, a more complete description of
> 
>    git branch --recurse-submodules topic origin/main
> 
> is something like:
> 
> * for each repository, create the 'topic' branch where each 'topic'
>    branch points to the version recorded in the superproject's
>    'origin/main'
> * for each repository, setup tracking for the 'topic' branch using the
>    repository's own 'origin/main' as the branch point
> 
> Note that there is no guarantee that a submodule's 'origin/main' points
> to the same commit as the superproject's 'origin/main', or if the
> submodule's 'origin/main' even exists.
> 
> If tracking information cannot be setup, we will still create the
> branch; we will only warn users when they run a command that requires
> tracking information e.g. fetch or push.

OK. That makes sense. Another option could be to track the branch pointed
to by origin/HEAD in the submodule (in an ideal world, that would point to
the default branch, but that has to be done mostly manually as of today...)