Re: Finding a branch point in git

From: Jeff King <peff@peff.net>
Date: May 28, 2012, 19:06 UTC
Message-ID: <20120528190639.GA2478@sigill.intra.peff.net>
In-Reply-To: <CAMP44s04msWMOaaH8U30XXg5yXJnEd=bULJ7VPxWSD0Wfh2=EA@mail.gmail.com>

On Mon, May 28, 2012 at 02:36:04PM +0200, Felipe Contreras wrote:

Show 11 quoted lines

> > What about a history with multiple branches?
> >
> > --X--A--B--C--D----E  (master)
> >      \           /
> >       G--H--I---J   (branch X)
> >           \    /
> >            K--L    (branch Y)
> [...]
> 
> Yes, but then you would need to specify a second branch. I would avoid
> that if possible.

I agree that is less nice. But I don't think the operation is well-defined with a single branch. If you ask for "when did branch X split", then in the above graph it is unclear if you meant "split from master", or "split from Y".

Maybe you could assume "master", or assume "git symbolic-ref HEAD" as the second branch?

Show 8 quoted lines

> There's also another case that doesn't work:
> 
> -- X -- A -- B (master)
>          \
>           \
>            C (branch A)
> 
> Shouldn't be hard to add checks for those cases I think.

Actually, I think that one extends naturally. They are never merged, so your rev-list never finds a merge commit, and you can just take the merge base of the branch tips.

-Peff