From: Junio C Hamano <gitster@pobox.com>
To: Jeff King <peff@peff.net>
Cc: Raman Gupta <rocketraman@gmail.com>, git@vger.kernel.org
Subject: Re: [RFC] Git rerere and non-conflicting changes during conflict resolution
Date: Wed, 26 Jul 2017 01:06:16 -0700 [thread overview]
Message-ID: <xmqq60eftyfb.fsf@gitster.mtv.corp.google.com> (raw)
In-Reply-To: <20170725205843.bi6kyqjlzyodmxuq@sigill.intra.peff.net> (Jeff King's message of "Tue, 25 Jul 2017 16:58:43 -0400")
Jeff King <peff@peff.net> writes:
> Hrm. That doesn't quite work, though. Because if your <A,B> are the
> merge, then merging a topic to next will get an "A" that is a merge
> commit from next. But that commit will never end up in master. What's
> causing the conflict is really some "A" that is in the history between
> the merge base and "A" (but we don't know which).
There may be a misunderstanding. When I said the key <A,B> is a
pair of branch names, I didn't mean 'A' to be the name of an
integration branch (e.g. 'pu') and 'B' to be the name of a topic.
Rather, both 'A' and 'B' are the names of topic branches.
IOW, instead of having refs/merge-fix/sd/branch-copy that says "I
know when I merge sd/branch-copy to pu or jch, there is a semantic
conflict with some unnamed topic that is likely to be already in
there", i.e. keying with only a single topic name, the ideal I
presented would say 'sd/branch-copy and mh/packed-ref-store topics
are both by themselves OK, but when merged together, the end result
of textual merge needs to be further fixed up by cherry-picking this
change', by keying a change with a pair of topic names,
sd/branch-copy (which introduces a new method in the ref backend
vtable) and mh/packed-ref-store (which adds a new ref backend). The
latter does not know the need for the new method, and the former
does not know the need to implement its new method in a new backend,
so a merge needs a trivial implementation of the new method added to
the new backend, which is what refs/merge-fix/sd/branch-copy does.
And better yet, instead of A=sd/branch-copy B=mh/packed-ref-store,
we could point at the exact commit on each of these branches that
introduce the semantic conflict. I would probably pick these two
A=52d59cc6 ("branch: add a --copy (-c) option to go with --move (-m)", 2017-06-18)
B=67be7c5a ("packed-backend: new module for handling packed references", 2017-06-23)
so when we are on commit X that has A but not B, and are trying to
merge branch Y that has B but not A, we want the merge-fix to kick
in. Walking "rev-list --left-right X...Y" and noticing A and B in
the output would be a way to notice it.
[footnote]
*1* https://github.com/gitster/git/ should mirror these refs in the
refs/merge-fix/ hierarchymentioned in the body of this article.
prev parent reply other threads:[~2017-07-26 8:06 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-25 15:09 [RFC] Git rerere and non-conflicting changes during conflict resolution Raman Gupta
2017-07-25 17:52 ` Jeff King
2017-07-25 19:54 ` Raman Gupta
2017-07-25 20:25 ` Jeff King
2017-07-25 20:26 ` Junio C Hamano
2017-07-25 20:40 ` Junio C Hamano
2017-07-25 20:58 ` Jeff King
2017-07-26 7:14 ` Junio C Hamano
2017-07-27 21:01 ` Junio C Hamano
2017-07-26 8:06 ` Junio C Hamano [this message]
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