Re: Using Origin hashes to improve rebase behavior

From: skillzero@gmail.com <skillzero@gmail.com>
Date: Feb 11, 2011, 10:02 UTC
Message-ID: <AANLkTikrVPCr92XHirn1u=73eM--T190V-7nbE6fo8ng@mail.gmail.com>
In-Reply-To: <m21v3fvbix.fsf@hermes.luannocracy.com>

On Thu, Feb 10, 2011 at 1:13 PM, John Wiegley <johnw@boostpro.com> wrote:

Show 39 quoted lines

> The following proposal is a check to see if this approach would be sane and
> whether someone is already doing similar work.  If not, I offer to implement
> this solution.
>
> THE PROBLEM
>
> Say I have a master from which I have branched locally, and that this private
> branch has four commits:
>
>    a   b   c
>    o---o---o
>             \
>              o---o---o---o
>              1   2   3   4
>
> I then decide to cherry pick commit 3 onto master.  Please believe that my
> situation is such that I cannot immediately rebase the private branch to drop
> the now-duplicated change.  I end up with this:
>
>    a   b   c   3'
>    o---o---o---o
>             \
>              o---o---o---o
>              1   2   3   4
>
> Later, there is work on master which changes the same lines of code that 3'
> has changed.  The commit which changes 3' is e*
>
>    a   b   c   3'  d   e*  f
>    o---o---o---o---o---o---o
>             \
>              o---o---o---o
>              1   2   3   4
>
> At a later date, I want to rebase the private branch onto master.  What will
> happen is that the changes in 3 will conflict with the rewritten changes in
> e*.  However, I'd like Git to know that 3 was already incorporated at some
> earlier time, and *not consider it during the rebase*, since it doesn't need
> to.

I don't know very much about how git really works so what I'm saying may be dumb, but rather than record where a commit came from, would it be reasonable for rebase to look at the patch-id for each change on the topic branch after the merge base and automatically remove topic branch commits that match that patch-id? So in your example, rebase would check each topic branch commit against 3', d, e*, and f and see that the 3' patch-id is the same as the topic branch 3 and remove topic branch 3 before it gets to e*?