Re: [PATCH] rebase: Allow merge strategies to be used when rebasing

From: Junio C Hamano <junkio@cox.net>
Date: Jun 19, 2006, 21:55 UTC
Message-ID: <7vbqso95f3.fsf@assigned-by-dhcp.cox.net>
In-Reply-To: <20060619213951.GA6987@hand.yhbt.net>

Eric Wong <normalperson@yhbt.net> writes:

Show 8 quoted lines

> Junio C Hamano <junkio@cox.net> wrote:
>
>>  - You kept the original "format-patch piped to am" workflow
>>    optionally working.
>
> I left it as the default, too.  I figured that it's best not
> to change the default (and most likely faster) behavior of
> something people rely on.

I should have said: "You kept ... working, which is good".

Show 10 quoted lines

>> I think the three-way merge you would want here is not between B
>> and G using E as the pivot, but between B and G using A as the
>> pivot.  That's how cherry-pick and revert works.  I would
>> leverage the interface that is one level lower for this -- the
>> strategy modules themselves.
>> 
>> 	git-merge-$strategy $cmt^ -- HEAD $cmt
>
> Changing the 'git-merge $strategy_args "rebase-merge: $cmt" HEAD "$cmt"'
> line in call_merge() to this seems to have broken more tests.

Oh, that is to be expected if you changed git-merge -s recursive with git-merge-recursive without other changes. The former makes a commit (which your original patch later used to create a separate commit chain and discarded); the latter does not make a commit but expects the caller to create a commit out of the resulting index file.

> I'm not an expert at merging strategies by any measure, I've just
> trusted merge-recursive to Do The Right Thing(TM) more often than not,
> and use rerere to avoid repeating work.

I was originally hoping that rebasing would just be a matter of listing sequence of commits to be ported onto a new base and running "git-cherry-pick" on each of them in sequence. Now cherry-pick does not use merge machinery (hence does not use git-merge-recursive), but if we change that then updating rebase would be pretty much straightforward. It just needs a UI layer to guide the user through recovery process when the merge does not resolve cleanly in the middle, no?