From: Alejandro Colomar <alx@kernel.org>
Date: Mon, 05 Oct 2026 13:28:21 GMT
Subject: Re: git-rebase-walk
Message-ID: <asOaLyiJUmINFFFH@debian>
In-Reply-To: <95796d0d-5928-4108-bc27-b7ace4459d2a@gmail.com>

Hi Phillip,

> Date: 2026-10-04 11:03:39+0100
> From: Phillip Wood <phillip.wood123@gmail.com>
>
> On 02/10/2026 07:46, Patrick Steinhardt wrote:
> > On Thu, Oct 01, 2026 at 05:51:58PM +0200, Alejandro Colomar wrote:
> > > 
> > > My script I use it in shadow-utils and in the Linux man-pages project,
> > > and is in use today.  I was wondering if there was interest in
> > > integrating it to git(1).
> > 
> > I guess the answer is "maybe". The fact that multiple folks have solved
> > similar issues over the course of many years is an indicator that the
> > funcitonality may be more generally useful. But it probably shouldn't be
> > a separate script, so if we wanted to integrate it I'd think the best
> > way forward would be to integrate it into git-rebase(1) directly.
> 
> I agree that would be the best way forward. Adding an "--incremental", or
> "--progressive" option to rebase would be useful I think. For ease of use, I
> have a strong preference for an implementation where "rebase --continue"
> handles rebasing onto progressively more recent bases, rather than the multi
> shot approach where the user has to run "git rebase --incremental" multiple
> times. Having a multi-shot approach makes it much less clear when we've
> successfully rebased onto the desired base.

For rebasing a single branch, having --continue do what you suggest
wouldn't be too problematic.

However, for when rebasing a tree of branches, I really need a
multi-shot operation, since I want to advance branches in a very
specific order.

Below is a shell session performing such a rebase, which hopefully shows
why I need this to be multi-shot.

On the simpler case of a single branch, I'd still prefer a multi-shot
approach where --continue only advances one rebase operation, because at
the end of it I want to stop, and check git-range-diff(1) to make sure
it all makes sense.

I've indented the output of commands, so that they are easier to
distinguish.

	alx@debian:~/tmp/brebase$ git log --all --graph --oneline
		* G ada8aff4f08a (r/B, B) foo j
		* G d6163efdc2db bar i
		| * G 450f3a7f4f25 (r/HEAD, r/C, C) bar l
		| * G f7309b21ebfa bar k
		|/  
		* G e949e24ba457 (HEAD -> A, r/A) bar h
		*   G 607b450498be bar g
		|\  
		| * G b787bcd373d9 bar e
		* | G c496b325576f baz f
		|/  
		| * G dfd9156d099a (r/main, main) foo d
		| * G 4940c7d739be bar c
		| * G cebc8fde25bb foo b
		|/  
		* G 1dcb901ebf60 foo a
	alx@debian:~/tmp/brebase$ git brebase --rebase-merges main
		Rebase: conflict
		Bisecting: 0 revisions left to test after this (roughly 1 step)
		[4940c7d739be44c0ca32c1d610b85fd5650e1528] bar c
		running '.git/bisect-rebase/git-bisect-run-callback'
		Rebase: conflict
		Bisecting: 0 revisions left to test after this (roughly 0 steps)
		[cebc8fde25bbe16c0f5f48e39642b3551f4f56e6] foo b
		running '.git/bisect-rebase/git-bisect-run-callback'
		Rebase: success
		4940c7d739be44c0ca32c1d610b85fd5650e1528 is the first 'bad' commit
		commit 4940c7d739be44c0ca32c1d610b85fd5650e1528
		Author: Alejandro Colomar <alx@kernel.org>
		Date:   2026-10-05 14:42:32 +0200

		    bar c

		 bar | 1 +
		 1 file changed, 1 insertion(+)
		 create mode 100644 bar
		bisect found first 'bad' commit
		Auto-merging bar
		CONFLICT (add/add): Merge conflict in bar
		error: could not apply 899eeb5c4e32... bar e
		hint: Resolve all conflicts manually, mark them as resolved with
		hint: "git add/rm <conflicted_files>", then run "git rebase --continue".
		hint: You can instead skip this commit: run "git rebase --skip".
		hint: To abort and get back to the state before "git rebase", run "git rebase --abort".
		hint: Disable this message with "git config set advice.mergeConflict false"
		Could not apply 899eeb5c4e32... # bar e
	alx@debian:~/tmp/brebase$ git rebase --abort 
	alx@debian:~/tmp/brebase$ git log --all --graph --oneline
		* 655c38e3cee8 (HEAD -> A) bar h
		*   1ababced193d bar g
		|\  
		| * 899eeb5c4e32 bar e
		* | 761c9dbcfa5b baz f
		|/  
		| * ada8aff4f08a (r/B, B) foo j
		| * d6163efdc2db bar i
		| | * 450f3a7f4f25 (r/HEAD, r/C, C) bar l
		| | * f7309b21ebfa bar k
		| |/  
		| * e949e24ba457 (r/A) bar h
		| *   607b450498be bar g
		| |\  
		| | * b787bcd373d9 bar e
		| * | c496b325576f baz f
		| |/  
		| | * dfd9156d099a (r/main, main) foo d
		| | * 4940c7d739be bar c
		| |/  
		|/|   
		* | cebc8fde25bb foo b
		|/  
		* 1dcb901ebf60 foo a
	alx@debian:~/tmp/brebase$ git switch B 
		Switched to branch 'B'
		Your branch is up to date with 'r/B'.
	alx@debian:~/tmp/brebase$ git brebase A
		Rebase: conflict
		Bisecting: 2 revisions left to test after this (roughly 1 step)
		[899eeb5c4e32397f0fe138c5b9f486d4682939cb] bar e
		running '.git/bisect-rebase/git-bisect-run-callback'
		Rebase: conflict
		Bisecting: 0 revisions left to test after this (roughly 0 steps)
		[cebc8fde25bbe16c0f5f48e39642b3551f4f56e6] foo b
		running '.git/bisect-rebase/git-bisect-run-callback'
		Rebase: conflict
		cebc8fde25bbe16c0f5f48e39642b3551f4f56e6 is the first 'bad' commit
		commit cebc8fde25bbe16c0f5f48e39642b3551f4f56e6
		Author: Alejandro Colomar <alx@kernel.org>
		Date:   2026-10-05 14:42:04 +0200

		    foo b

		 foo | 2 +-
		 1 file changed, 1 insertion(+), 1 deletion(-)
		bisect found first 'bad' commit
		Auto-merging foo
		CONFLICT (content): Merge conflict in foo
		error: could not apply ada8aff4f08a... foo j
		hint: Resolve all conflicts manually, mark them as resolved with
		hint: "git add/rm <conflicted_files>", then run "git rebase --continue".
		hint: You can instead skip this commit: run "git rebase --skip".
		hint: To abort and get back to the state before "git rebase", run "git rebase --abort".
		hint: Disable this message with "git config set advice.mergeConflict false"
		Could not apply ada8aff4f08a... # foo j
	alx@debian:~/tmp/brebase$ echo j >foo
	alx@debian:~/tmp/brebase$ git add foo 
	alx@debian:~/tmp/brebase$ git rebase --continue 
		[detached HEAD 2e0b72e7440a] foo j
		 1 file changed, 1 insertion(+), 1 deletion(-)
		Successfully rebased and updated refs/heads/B.
	alx@debian:~/tmp/brebase$ git log --all --graph --oneline
		* 2e0b72e7440a (HEAD -> B) foo j
		* a1c6c1fb7ca2 bar i
		* d8fa6c4da463 bar h
		* bef9f1c4da4d bar e
		* 0bac26895b94 baz f
		| * 655c38e3cee8 (A) bar h
		| *   1ababced193d bar g
		| |\  
		| | * 899eeb5c4e32 bar e
		| |/  
		|/|   
		| * 761c9dbcfa5b baz f
		|/  
		| * ada8aff4f08a (r/B) foo j
		| * d6163efdc2db bar i
		| | * 450f3a7f4f25 (r/HEAD, r/C, C) bar l
		| | * f7309b21ebfa bar k
		| |/  
		| * e949e24ba457 (r/A) bar h
		| *   607b450498be bar g
		| |\  
		| | * b787bcd373d9 bar e
		| * | c496b325576f baz f
		| |/  
		| | * dfd9156d099a (r/main, main) foo d
		| | * 4940c7d739be bar c
		| |/  
		|/|   
		* | cebc8fde25bb foo b
		|/  
		* 1dcb901ebf60 foo a
	alx@debian:~/tmp/brebase$ git brebase A
		Rebase: success
	alx@debian:~/tmp/brebase$ git log --all --graph --oneline
		* 5ff93a00f9f2 (HEAD -> B) foo j
		* 01522206a7bc bar i
		* 655c38e3cee8 (A) bar h
		*   1ababced193d bar g
		|\  
		| * 899eeb5c4e32 bar e
		* | 761c9dbcfa5b baz f
		|/  
		| * ada8aff4f08a (r/B) foo j
		| * d6163efdc2db bar i
		| | * 450f3a7f4f25 (r/HEAD, r/C, C) bar l
		| | * f7309b21ebfa bar k
		| |/  
		| * e949e24ba457 (r/A) bar h
		| *   607b450498be bar g
		| |\  
		| | * b787bcd373d9 bar e
		| * | c496b325576f baz f
		| |/  
		| | * dfd9156d099a (r/main, main) foo d
		| | * 4940c7d739be bar c
		| |/  
		|/|   
		* | cebc8fde25bb foo b
		|/  
		* 1dcb901ebf60 foo a
	alx@debian:~/tmp/brebase$ git switch C
		Switched to branch 'C'
	alx@debian:~/tmp/brebase$ git brebase A
		Rebase: success
	alx@debian:~/tmp/brebase$ git log --all --graph --oneline
		* 06d462903420 (HEAD -> C) bar l
		* 20f0a887b83b bar k
		| * 5ff93a00f9f2 (B) foo j
		| * 01522206a7bc bar i
		|/  
		* 655c38e3cee8 (A) bar h
		*   1ababced193d bar g
		|\  
		| * 899eeb5c4e32 bar e
		* | 761c9dbcfa5b baz f
		|/  
		| * ada8aff4f08a (r/B) foo j
		| * d6163efdc2db bar i
		| | * 450f3a7f4f25 (r/HEAD, r/C) bar l
		| | * f7309b21ebfa bar k
		| |/  
		| * e949e24ba457 (r/A) bar h
		| *   607b450498be bar g
		| |\  
		| | * b787bcd373d9 bar e
		| * | c496b325576f baz f
		| |/  
		| | * dfd9156d099a (r/main, main) foo d
		| | * 4940c7d739be bar c
		| |/  
		|/|   
		* | cebc8fde25bb foo b
		|/  
		* 1dcb901ebf60 foo a
	alx@debian:~/tmp/brebase$ git switch A
		Switched to branch 'A'
	alx@debian:~/tmp/brebase$ git brebase --rebase-merges main
		Rebase: conflict
		Bisecting: 0 revisions left to test after this (roughly 0 steps)
		[4940c7d739be44c0ca32c1d610b85fd5650e1528] bar c
		running '.git/bisect-rebase/git-bisect-run-callback'
		Rebase: conflict
		4940c7d739be44c0ca32c1d610b85fd5650e1528 is the first 'bad' commit
		commit 4940c7d739be44c0ca32c1d610b85fd5650e1528
		Author: Alejandro Colomar <alx@kernel.org>
		Date:   2026-10-05 14:42:32 +0200

		    bar c

		 bar | 1 +
		 1 file changed, 1 insertion(+)
		 create mode 100644 bar
		bisect found first 'bad' commit
		Auto-merging bar
		CONFLICT (add/add): Merge conflict in bar
		error: could not apply 899eeb5c4e32... bar e
		hint: Resolve all conflicts manually, mark them as resolved with
		hint: "git add/rm <conflicted_files>", then run "git rebase --continue".
		hint: You can instead skip this commit: run "git rebase --skip".
		hint: To abort and get back to the state before "git rebase", run "git rebase --abort".
		hint: Disable this message with "git config set advice.mergeConflict false"
		Could not apply 899eeb5c4e32... # bar e
	alx@debian:~/tmp/brebase$ echo e >bar
	alx@debian:~/tmp/brebase$ git add bar 
	alx@debian:~/tmp/brebase$ git rebase --continue 
		[detached HEAD 2a4fa7fe2f44] bar e
		 1 file changed, 1 insertion(+), 1 deletion(-)
		Successfully rebased and updated refs/heads/A.
	alx@debian:~/tmp/brebase$ git log --all --graph --oneline
		* 0954f3d9b9e1 (HEAD -> A) bar h
		*   4f09c21bf2ca bar g
		|\  
		| * 2a4fa7fe2f44 bar e
		* | e42246e75159 baz f
		|/  
		| * 06d462903420 (C) bar l
		| * 20f0a887b83b bar k
		| | * 5ff93a00f9f2 (B) foo j
		| | * 01522206a7bc bar i
		| |/  
		| * 655c38e3cee8 bar h
		| *   1ababced193d bar g
		| |\  
		| | * 899eeb5c4e32 bar e
		| * | 761c9dbcfa5b baz f
		| |/  
		| | * ada8aff4f08a (r/B) foo j
		| | * d6163efdc2db bar i
		| | | * 450f3a7f4f25 (r/HEAD, r/C) bar l
		| | | * f7309b21ebfa bar k
		| | |/  
		| | * e949e24ba457 (r/A) bar h
		| | *   607b450498be bar g
		| | |\  
		| | | * b787bcd373d9 bar e
		| | * | c496b325576f baz f
		| | |/  
		| | | * dfd9156d099a (r/main, main) foo d
		| |_|/  
		|/| |   
		* | | 4940c7d739be bar c
		|/ /  
		* / cebc8fde25bb foo b
		|/  
		* 1dcb901ebf60 foo a
	alx@debian:~/tmp/brebase$ git rebase --onto A 655c38e3cee8 B
		Successfully rebased and updated refs/heads/B.
	alx@debian:~/tmp/brebase$ git rebase --onto A 655c38e3cee8 C
		Successfully rebased and updated refs/heads/C.
	alx@debian:~/tmp/brebase$ git log --all --graph --oneline
		* 4a4ba76f55a4 (HEAD -> C) bar l
		* 86350e1490f3 bar k
		| * 4b6b40b14255 (B) foo j
		| * ba5a233ee4bc bar i
		|/  
		* 0954f3d9b9e1 (A) bar h
		*   4f09c21bf2ca bar g
		|\  
		| * 2a4fa7fe2f44 bar e
		* | e42246e75159 baz f
		|/  
		| * ada8aff4f08a (r/B) foo j
		| * d6163efdc2db bar i
		| | * 450f3a7f4f25 (r/HEAD, r/C) bar l
		| | * f7309b21ebfa bar k
		| |/  
		| * e949e24ba457 (r/A) bar h
		| *   607b450498be bar g
		| |\  
		| | * b787bcd373d9 bar e
		| * | c496b325576f baz f
		| |/  
		| | * dfd9156d099a (r/main, main) foo d
		| |/  
		|/|   
		* | 4940c7d739be bar c
		* | cebc8fde25bb foo b
		|/  
		* 1dcb901ebf60 foo a
	alx@debian:~/tmp/brebase$ git switch A
		Switched to branch 'A'
	alx@debian:~/tmp/brebase$ git brebase --rebase-merges main
		Rebase: success
	alx@debian:~/tmp/brebase$ git log --all --graph --oneline
		* 30e2d96b3da5 (HEAD -> A) bar h
		*   01702a5b5d6b bar g
		|\  
		| * c961883d543a bar e
		* | e17aadb725c4 baz f
		|/  
		* dfd9156d099a (r/main, main) foo d
		| * 4a4ba76f55a4 (C) bar l
		| * 86350e1490f3 bar k
		| | * 4b6b40b14255 (B) foo j
		| | * ba5a233ee4bc bar i
		| |/  
		| * 0954f3d9b9e1 bar h
		| *   4f09c21bf2ca bar g
		| |\  
		| | * 2a4fa7fe2f44 bar e
		| |/  
		|/|   
		| * e42246e75159 baz f
		|/  
		* 4940c7d739be bar c
		* cebc8fde25bb foo b
		| * ada8aff4f08a (r/B) foo j
		| * d6163efdc2db bar i
		| | * 450f3a7f4f25 (r/HEAD, r/C) bar l
		| | * f7309b21ebfa bar k
		| |/  
		| * e949e24ba457 (r/A) bar h
		| *   607b450498be bar g
		| |\  
		| | * b787bcd373d9 bar e
		| |/  
		|/|   
		| * c496b325576f baz f
		|/  
		* 1dcb901ebf60 foo a
	alx@debian:~/tmp/brebase$ git rebase --onto A 0954f3d9b9e1 C
		Successfully rebased and updated refs/heads/C.
	alx@debian:~/tmp/brebase$ git rebase --onto A 0954f3d9b9e1 B
		Auto-merging foo
		CONFLICT (content): Merge conflict in foo
		error: could not apply 4b6b40b14255... foo j
		hint: Resolve all conflicts manually, mark them as resolved with
		hint: "git add/rm <conflicted_files>", then run "git rebase --continue".
		hint: You can instead skip this commit: run "git rebase --skip".
		hint: To abort and get back to the state before "git rebase", run "git rebase --abort".
		hint: Disable this message with "git config set advice.mergeConflict false"
		Could not apply 4b6b40b14255... # foo j
	alx@debian:~/tmp/brebase$ git rebase --abort 
	alx@debian:~/tmp/brebase$ git switch B
		Already on 'B'
		Your branch and 'r/B' have diverged,
		and have 8 and 6 different commits each, respectively.
		  (use "git pull" if you want to integrate the remote branch with yours)
	alx@debian:~/tmp/brebase$ git brebase A
		Rebase: conflict
		Bisecting: 2 revisions left to test after this (roughly 1 step)
		[c961883d543a2393aacfd6a8345e1d29e6857f7f] bar e
		running '.git/bisect-rebase/git-bisect-run-callback'
		Rebase: conflict
		Bisecting: 0 revisions left to test after this (roughly 0 steps)
		[dfd9156d099ad3507a2850294c7a584b80712f04] foo d
		running '.git/bisect-rebase/git-bisect-run-callback'
		Rebase: conflict
		dfd9156d099ad3507a2850294c7a584b80712f04 is the first 'bad' commit
		commit dfd9156d099ad3507a2850294c7a584b80712f04
		Author: Alejandro Colomar <alx@kernel.org>
		Date:   2026-10-05 14:42:50 +0200

		    foo d

		 foo | 2 +-
		 1 file changed, 1 insertion(+), 1 deletion(-)
		bisect found first 'bad' commit
		Auto-merging foo
		CONFLICT (content): Merge conflict in foo
		error: could not apply 4b6b40b14255... foo j
		hint: Resolve all conflicts manually, mark them as resolved with
		hint: "git add/rm <conflicted_files>", then run "git rebase --continue".
		hint: You can instead skip this commit: run "git rebase --skip".
		hint: To abort and get back to the state before "git rebase", run "git rebase --abort".
		hint: Disable this message with "git config set advice.mergeConflict false"
		Could not apply 4b6b40b14255... # foo j
	alx@debian:~/tmp/brebase$ echo j >foo
	alx@debian:~/tmp/brebase$ git add foo 
	alx@debian:~/tmp/brebase$ git rebase --continue 
		[detached HEAD e7fdf07fd077] foo j
		 1 file changed, 1 insertion(+), 1 deletion(-)
		Successfully rebased and updated refs/heads/B.
	alx@debian:~/tmp/brebase$ git log --all --graph --oneline
		* e7fdf07fd077 (HEAD -> B) foo j
		* dddf632a735f bar i
		* 7ac284de12ba bar h
		* e4541508ab3e bar e
		* cefec5878c67 baz f
		| * 6c7952d6fec5 (C) bar l
		| * bd43684f73c8 bar k
		| * 30e2d96b3da5 (A) bar h
		| *   01702a5b5d6b bar g
		| |\  
		| | * c961883d543a bar e
		| |/  
		|/|   
		| * e17aadb725c4 baz f
		|/  
		* dfd9156d099a (r/main, main) foo d
		* 4940c7d739be bar c
		* cebc8fde25bb foo b
		| * ada8aff4f08a (r/B) foo j
		| * d6163efdc2db bar i
		| | * 450f3a7f4f25 (r/HEAD, r/C) bar l
		| | * f7309b21ebfa bar k
		| |/  
		| * e949e24ba457 (r/A) bar h
		| *   607b450498be bar g
		| |\  
		| | * b787bcd373d9 bar e
		| |/  
		|/|   
		| * c496b325576f baz f
		|/  
		* 1dcb901ebf60 foo a
	alx@debian:~/tmp/brebase$ git brebase A
		Rebase: success
	alx@debian:~/tmp/brebase$ git log --all --graph --oneline
		* 1201c4f20b19 (HEAD -> B) foo j
		* 44103f51a783 bar i
		| * 6c7952d6fec5 (C) bar l
		| * bd43684f73c8 bar k
		|/  
		* 30e2d96b3da5 (A) bar h
		*   01702a5b5d6b bar g
		|\  
		| * c961883d543a bar e
		* | e17aadb725c4 baz f
		|/  
		* dfd9156d099a (r/main, main) foo d
		* 4940c7d739be bar c
		* cebc8fde25bb foo b
		| * ada8aff4f08a (r/B) foo j
		| * d6163efdc2db bar i
		| | * 450f3a7f4f25 (r/HEAD, r/C) bar l
		| | * f7309b21ebfa bar k
		| |/  
		| * e949e24ba457 (r/A) bar h
		| *   607b450498be bar g
		| |\  
		| | * b787bcd373d9 bar e
		| |/  
		|/|   
		| * c496b325576f baz f
		|/  
		* 1dcb901ebf60 foo a

This would be impossible with an approach that handles all the way until
the end.  I need to be able to stop a bisect-rebase operation on one
branch in the middle, then do a bisect-rebase on its descendants, then
come back to bisect-rebase the parent branch.  Does this make sense?


Have a lovely day!
Alex


> 
> Thanks
> 
> Phillip
> 
> 
> > That's of course more involved though, so I understand in case you're
> > not interested in doing that.
> > 
> > > If not, I will likely provide it in the man-pages repository as a help
> > > tool (which might end up packed by distros as part of manpages-utils).
> > > Is that okay to you?  (I ask mainly because it's using the git-
> > > namespace for commands, so you should at lease be aware of it.)
> > 
> > I mean overall this is our primary way of extension, by picking up
> > utilities that have the "git-" prefix. So arguably you don't have to ask
> > us for permission to do that.
> > 
> > Whether it makes sense to distribute such a tool as part of
> > manpages-utils is a different question, and one where I myself am of a
> > split mind. But that feels more like a question for distributors rather
> > than for us in the Git project.
> > 
> > Thanks!
> > 
> > Patrick
> 

-- 
<https://www.alejandro-colomar.es>