threads / discuss / 25488

git rebase and merge commits

Subject: git rebase and merge commits

## tl;dr

5 messages between Oct 20, 2010 and Oct 25, 2010.

replies: 4people: 3as markdown or json

Dominique Quatravaux· Oct 20, 2010, 16:45 UTC · lore

Hi all, I'm trying to write "git shove", a wrapper around git rebase --interactive that would turn this

# A---B---C---K targetbranch # / \ # D---E---F---G---H---I--J srcbranch

into this:

# A---B---C---I'---K' targetbranch # / \ # D---E---F---G---H'---J' srcbranch #

(ie I has been shoved into targetbranch).

It seemed to me that the first step should be to simply rebase I, H, and J (in this order) onto C. Unfortunately git rebase --interactive -p C proposes a git-rebase-todo that contains only "noop"; if I forcefully put this instead,

edit iiii I edit hhhh H edit jjjj J

it seems to me that the HEAD jumps backward to the original H on the second rebase step, instead of daisy-chaining H behind I. This is with git 1.7.3.1.

Here are the outputs of git log --graph --pretty=oneline --abbrev-commit at each rebase step:

1/3
* a810395 I
*   1cfccc7 H
|\
| * c477d4e C
| * 7002290 B
| * aa9f1d0 A
* | b614d31 G
* | 2ad4496 F
|/
* 0d512e9 E
* b6cbc2b D
2/3
*   1cfccc7 H
|\
| * c477d4e C
| * 7002290 B
| * aa9f1d0 A
* | b614d31 G
* | 2ad4496 F
|/
* 0d512e9 E
* b6cbc2b D
3/3
* 3a41a45 J
* a810395 I
*   1cfccc7 H
|\
| * c477d4e C
| * 7002290 B
| * aa9f1d0 A
* | b614d31 G
* | 2ad4496 F
|/
* 0d512e9 E
* b6cbc2b D
Is there a way to do a real rebase of a merge commit?

FWIW, here is the script I use to create my toy environment in the current directory:

function _make_commit() {
  echo "$1" > "$1"
  git add "$1"
  git commit -a -m "$1"
  git tag "$1" HEAD
}
function _prepare_merged_history() {
  git init
  _make_commit "D"
  git checkout -b targetbranch
  _make_commit "E"
  _make_commit "A"
  _make_commit "B"
  _make_commit "C"
  _make_commit "K"
  git checkout E
  git checkout -b srcbranch
  _make_commit "F"
  _make_commit "G"
  git merge  -m "H" C
  git tag H HEAD
  _make_commit "I"
  _make_commit "J"
}
function _git_rebase_todo_line() {
  echo -n "pick "
  git rev-list -n 1 --pretty=oneline --abbrev-commit --abbrev=7 "$1"
}
function _make_git_rebase_todo() {
  {
    _git_rebase_todo_line refs/tags/I
    _git_rebase_todo_line refs/tags/H
    _git_rebase_todo_line refs/tags/J
  } > git-rebase-todo
}

[ -d ".git" ] && exit _prepare_merged_history _make_git_rebase_todo

Thanks in advance,
-- 
  Dominique Quatravaux
  +41 79 609 40 72
Jonathan Nieder· Oct 20, 2010, 17:32 UTC · re: Dominique Quatravaux · lore

Re: git rebase and merge commits

Hi Dominique,
Dominique Quatravaux wrote:
Show 15 quoted lines
> #        A---B---C---K targetbranch
> #       /         \
> #  D---E---F---G---H---I--J srcbranch
> 
> into this:
> 
> #   A---B---C---I'---K'  targetbranch
> #  /             \
> # D---E---F---G---H'---J' srcbranch
> #
> 
> (ie I has been shoved into targetbranch).
> 
> It seemed to me that the first step should be to simply rebase I, H, and J (in
> this order) onto C. Unfortunately git rebase --interactive -p C proposes
[...]

I'm sorry to break this news, but "rebase --interactive --preserve-merges" (unlike "rebase --preserve-merges" without --interactive) was never implemented completely. See the BUGS section of the git-rebase man page.

Luckily, there is a roadmap for anyone interested in implementing it. Maybe it could be you? See [1] and the surrounding thread.

Thanks for your interest, Jonathan

[1] http://thread.gmane.org/gmane.comp.version-control.git/148059/focus=148144
Joshua Jensen· Oct 20, 2010, 17:44 UTC · re: Jonathan Nieder · lore

Re: git rebase and merge commits

----- Original Message -----
From: Jonathan Nieder
Date: 10/20/2010 11:32 AM
Show 11 quoted lines
> I'm sorry to break this news, but "rebase --interactive --preserve-merges"
> (unlike "rebase --preserve-merges" without --interactive) was never
> implemented completely.  See the BUGS section of the git-rebase man page.
>
> Luckily, there is a roadmap for anyone interested in implementing it.  Maybe
> it could be you?  See [1] and the surrounding thread.
>
> Thanks for your interest,
> Jonathan
>
> [1] http://thread.gmane.org/gmane.comp.version-control.git/148059/focus=148144

I applied that patch to my git-rebase--interactive, although it did not cleanly apply. I hacked a few bits to get it going again. I could post the entire file here, if someone wants to clean it up.

It does properly rebase the first-parent merges fine.
Josh
Joshua Jensen· Oct 20, 2010, 18:12 UTC · re: Joshua Jensen · lore

Re: git rebase and merge commits

----- Original Message -----
From: Joshua Jensen
Date: 10/20/2010 11:44 AM
Show 23 quoted lines
> ----- Original Message -----
> From: Jonathan Nieder
> Date: 10/20/2010 11:32 AM
>> I'm sorry to break this news, but "rebase --interactive 
>> --preserve-merges"
>> (unlike "rebase --preserve-merges" without --interactive) was never
>> implemented completely.  See the BUGS section of the git-rebase man 
>> page.
>>
>> Luckily, there is a roadmap for anyone interested in implementing 
>> it.  Maybe
>> it could be you?  See [1] and the surrounding thread.
>>
>> Thanks for your interest,
>> Jonathan
>>
>> [1] 
>> http://thread.gmane.org/gmane.comp.version-control.git/148059/focus=148144
> I applied that patch to my git-rebase--interactive, although it did 
> not cleanly apply.  I hacked a few bits to get it going again.  I 
> could post the entire file here, if someone wants to clean it up.
>
> It does properly rebase the first-parent merges fine.

Never mind. I applied this patch: http://marc.info/?l=git&m=119379735525213&w=2

Josh
Dominique Quatravaux· Oct 25, 2010, 11:23 UTC · re: Jonathan Nieder · lore

Re: git rebase and merge commits

On Wed, Oct 20, 2010 at 7:32 PM, Jonathan Nieder <jrnieder@gmail.com> wrote:
Show 8 quoted lines
> Luckily, there is a roadmap for anyone interested in implementing it.  Maybe
> it could be you?  See [1] and the surrounding thread.
>
> Thanks for your interest,
> Jonathan
>
> [1] http://thread.gmane.org/gmane.comp.version-control.git/148059/focus=148144
>

I gave it a shot last week, but this is more that I can chew on in my spare time. Sorry! Thanks for the information anyway.

-- 
  Dominique Quatravaux
  +41 79 609 40 72

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