Rebasing multiple branches

Rebasing multiple branches

[Leonid Podolny]

Hi,
I need to rebase a rather complicated formation of branches.

My situation is like this (I hope ASCII graphics survive the sending):

         B--o--o--o--o--o--o  <--branch A
        /                   \
o--o--A--o--E  <--master    C--o--o--o--D  <--branch C
        \                   /
         C--o--o--o--o--o--o  <--branch B

I would like to rebase all three branches A, B and C onto commit E, and 
it's very important to keep the information about merges. For instance, 
if I take commit C and rebase it onto D, it serializes all the 
intermediate commits.
The only solution I managed to come up with is as follows:
- Take branch A and rebase it onto D (branch A').
- Same with branch B.
- Open a new branch C' from commit E.
- Merge A' and B' into C'.
- Manually cherry-pick all commits from commit C to commit D into branch C'.


The last step is way too ugly to be the only possible solution :)

Re: Rebasing multiple branches

[Johannes Sixt]

Am 12/21/2010 14:40, schrieb Leonid Podolny:
>         B--o--o--o--o--o--o  <--branch A
>        /                   \
> o--o--A--o--E  <--master    C--o--o--o--D  <--branch C
>        \                   /
>         C--o--o--o--o--o--o  <--branch B
> 
> I would like to rebase all three branches A, B and C onto commit E,...

git rebase master A
git rebase master B
git merge A
git rebase -i HEAD C

The last rebase I propose as interactive so that you can remove those
commits before D~3 that you have already rebased, because they are likely
to conflict unnecessarily, and you would --skip them anyway.

(Note: "C" is the branch C, not the commit C. Please make labels
unambiguous next time.)

-- Hannes

Re: Rebasing multiple branches

[Enrico Weigelt]

* Johannes Sixt <j.sixt@viscovery.net> wrote:
> Am 12/21/2010 14:40, schrieb Leonid Podolny:
> >         B--o--o--o--o--o--o  <--branch A
> >        /                   \
> > o--o--A--o--E  <--master    C--o--o--o--D  <--branch C
> >        \                   /
> >         C--o--o--o--o--o--o  <--branch B
> > 
> > I would like to rebase all three branches A, B and C onto commit E,...
> 
> git rebase master A
> git rebase master B
> git merge A
> git rebase -i HEAD C
> 
> The last rebase I propose as interactive so that you can remove those
> commits before D~3 that you have already rebased, because they are likely
> to conflict unnecessarily, and you would --skip them anyway.

Why not this way ?

git checkout D
git rebase -p -i D~3 --onto C'

(C' is the merged branch of A' and B').


So:

git checkout branch_A -b rebasing_A
git rebase master			# rebase old A to master
git checkout branch_B -b rebasing_B
git rebase master			# rebase old B to master
git checkout -b rebased_merge
git merge rebasing_A			# we're on B', merge in A'
git checkout branch_C
git rebase -p -i C --onto rebased_merge # set D~3..D ontop of it


cu
-- 
----------------------------------------------------------------------
 Enrico Weigelt, metux IT service -- http://www.metux.de/

 phone:  +49 36207 519931  email: weigelt@metux.de
 mobile: +49 151 27565287  icq:   210169427         skype: nekrad666
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Re: Rebasing multiple branches

[Leonid Podolny]

On 12/22/2010 04:36 PM, Enrico Weigelt wrote:
> Why not this way ?
>
> git checkout D
> git rebase -p -i D~3 --onto C'
>
> (C' is the merged branch of A' and B').
>
>
> So:
>
> git checkout branch_A -b rebasing_A
> git rebase master			# rebase old A to master
> git checkout branch_B -b rebasing_B
> git rebase master			# rebase old B to master
> git checkout -b rebased_merge
> git merge rebasing_A			# we're on B', merge in A'
> git checkout branch_C
> git rebase -p -i C --onto rebased_merge # set D~3..D ontop of it
>
>
> cu

Ah, nice. I didn't notice the -p option. However, the man page advises 
against using -p and -i together.

Re: Rebasing multiple branches

[Enrico Weigelt]

* Leonid Podolny <leonidp.lists@gmail.com> wrote:

> Ah, nice. I didn't notice the -p option. However, the man page advises 
> against using -p and -i together.

Last time I checked, -i required -p ...


cu
-- 
----------------------------------------------------------------------
 Enrico Weigelt, metux IT service -- http://www.metux.de/

 phone:  +49 36207 519931  email: weigelt@metux.de
 mobile: +49 151 27565287  icq:   210169427         skype: nekrad666
----------------------------------------------------------------------
 Embedded-Linux / Portierung / Opensource-QM / Verteilte Systeme
----------------------------------------------------------------------

Re: Rebasing multiple branches

[Thomas Rast]

Please don't cull the Cc lists.  Unless he's subscribed, Leonid never
got your reply!

Enrico Weigelt wrote:
> * Leonid Podolny <leonidp.lists@gmail.com> wrote:
> 
> > Ah, nice. I didn't notice the -p option. However, the man page advises 
> > against using -p and -i together.
> 
> Last time I checked, -i required -p ...

-p internally implies -i, but the user doesn't have to know that ;-)

The problem is that the todo file language is not expressive enough
for what -p needs to do.  Running a rebase -p without changing the
todo file should behave reasonably.  On the other hand, if you
rearrange or extend the todo file in many cases that gives unexpected
results.

Hence the recommendation to not use it with -i.

-- 
Thomas Rast
trast@{inf,student}.ethz.ch