Re: small b4 feature request

[Jeff Layton <jlayton@kernel.org>]

On Tue, 2024-12-10 at 17:16 -0500, Konstantin Ryabitsev wrote:
> On Mon, Dec 09, 2024 at 05:13:31PM -0500, Jeff Layton wrote:
> > First, let me say that I love b4. It's great for managing a patch
> > series over time.
> 
> Great to hear, thanks!
> 
> > I often carry around the b4 commit at the base of my patch pile and end
> > up having to rebase on top of it. It would be great to have a way to
> > specify the b4 tracking commit symbolically to git so I could do this
> > without having to lookup the commit ID of the b4 head:
> > 
> >     $ git rebase -i B4_HEAD
> 
> I'm having a hard time wrapping my head around this (pun not intended). Is the
> commit in question the tip of the b4 branch, or the base commit?
> 
> In either case there is already a way to obtain this information with b4,
> e.g.:
> 
>     b4 prep --show-info base-commit
>     b4 prep --show-info end-commit
>     b4 prep --show-info series-range
> 
> So, e.g. if you want to rebase one prep-managed branch on top of another, you
> could do [1]:
> 
>     git rebase -i $(b4 prep --show-info b4/some-branch:end-commit)
> 
> Does this do what you need, or am I misunderstanding the situation?
> 
> [1]: apparently, show-info for a non-current branch was broken in master and
> 0.14.y, so you'll need the latest master or stable-0.14.y.
> 

That does help.

I was thinking that B4_HEAD to be the empty commit at the bottom of the
series-range that b4 uses to track the series. IOW:

    b4 prep --show-info series-range | cut -d'.' -f1

...but now that I look at the b4 innards, I see that there are
different cover-letter tracking strategies. Maybe just using "base-
commit" would be simplest. So I guess I can do what I need with:

    $ git rebase -i $(b4 prep --show-info base-commit)

It has the empty tracking commit in my setup, but I can live with that.

Thanks!
-- 
Jeff Layton <jlayton@kernel.org>