Subject: Re: [PATCH] provide a new "theirs" strategy, useful for rebase --onto

From: Paolo Bonzini <[email-masked]>
Date: Sun, 08 Jun 2008 16:06:33 -0700

Junio C Hamano wrote:
> Paolo Bonzini <[email-masked]> writes:
> 
>>    #! /bin/sh
>>    # git-merge-after-amend <branch>
>>    #
>>    # Makes it possible to do a fast-forward merge of <branch>
>>    # into HEAD, assuming that the first diverging commit of <branch>
>>    # is an --amend'ed version of the first diverging commit of HEAD.
> 
> Can this strong special case limitation "only the first one can be the
> amend" somehow be loosened?

Well, the point of the exercise is to split a *single* commit into a 
"base" commit (already available, possibly on another branch) and a 
"delta" (the amending, transformed into an independent commit whose 
parent is the "base").  Indeed you can do that for any commit.

The script uses the "git-merge-base" to compute the "base", and takes 
the following commit (on the path to HEAD) as the "delta".  That's what 
add the restriction.  You can definitely make a two-argument variation 
that, given arguments "B C" and history

     o--B     (it is irrelevant if B and C have common parents)

     o--o--C--D--E    HEAD

makes

     A--B--C'--D--E

Even in that case, I would make the script (which anyway is obviously 
not meant to be included in git, it's a commodity script) accept both 
variations: one-argument to do the special case, and two-arguments to 
generically split a commit into a base provided by the user + a delta.

Paolo