Re: rewrite history

From: Junio C Hamano <gitster@pobox.com>
Date: Jun 16, 2011, 19:43 UTC
Message-ID: <7vhb7ph8aj.fsf@alter.siamese.dyndns.org>
In-Reply-To: <20110616192644.GB13466@sigill.intra.peff.net>

Jeff King <peff@peff.net> writes:

Show 21 quoted lines

> On Thu, Jun 16, 2011 at 11:17:58PM +0400, Ilya Basin wrote:
>
>> Hi list. There were 2 branches. One's HEAD was modified to match a
>> specific commit at another branch. Now, how to merge them according to
>> this scheme?
>> 
>> A---B---X---E---F
>>                      =>  C---D---X---E---F
>> C---D---X'
>> 
>> X and X' have no difference. I tried to write a script to cherry-pick
>> E and F, but some of commits are merges and cherry-pick fails.
>
> I think you just want to rebase using the "-p" option to preserve
> merges. Something like:
>
>   $ git checkout -b rebased-branch F
>   $ git rebase -p --onto D B
>
> that will pick X, E, and F, and replay them on top of D, resulting in
> the graph you showed above.

Eh, careful. Nobody said the change between B and X is any similar to the change between D and X'. Replaying the changes E and F introduce on top of X' to arrive at C--D--X'-E--F is the best you could do, i.e.

>   $ git rebase -p --onto X' X
>
> if you wanted to keep X' instead of X.

is more like "even if you wanted to keep X instead of X'".

If you prefer commit message of X over X', you can rebase -i it after you are done the first round to get rid of A and B, though.

But wouldn't filter-branch a better tool for this? Graft to pretend that the parent of X is D instead of B, and filter the branch with F at its tip, that is.