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From: Siddharth Asthana <siddharthasthana31@gmail•com>
To: Johannes Schindelin <Johannes.Schindelin@gmx•de>
Cc: git@vger•kernel.org, christian.couder@gmail•com, ps@pks•im,
	newren@gmail•com, gitster@pobox•com, phillip.wood123@gmail•com,
	phillip.wood@dunelm•org.uk, karthik.188@gmail•com,
	code@khaugsbakk•name, rybak.a.v@gmail•com, jltobler@gmail•com,
	toon@iotcl•com, johncai86@gmail•com
Subject: Re: [PATCH 0/1] replay: add --revert option to reverse commit changes
Date: Thu, 27 Nov 2025 00:48:53 +0530	[thread overview]
Message-ID: <27fef9e1-bf26-48af-b3df-35948937c891@gmail.com> (raw)
In-Reply-To: <4d75da90-7e85-573a-bb10-0c63a02b076c@gmx.de>


On 25/11/25 22:55, Johannes Schindelin wrote:
> Hi Siddharth,
>
> On Tue, 25 Nov 2025, Siddharth Asthana wrote:
>
>> The `git replay` command currently supports cherry-picking commits for
>> server-side history rewriting, but lacks the ability to revert them.
>> This patch adds a `--revert` option to enable reversing commits directly
>> on bare repositories.
>>
>> At GitLab, we use replay in Gitaly for efficient server-side operations.
>> Adding revert functionality enables us to reverse problematic commits
>> without client-side roundtrips, reducing network overhead.
>>
>> The implementation leverages the insight that cherry-pick and revert are
>> essentially the same merge operation with swapped arguments. By swapping
>> the base and pickme trees when calling `merge_incore_nonrecursive()`, we
>> effectively reverse the diff direction. The existing conflict handling,
>> ref updates, and atomic transaction support work unchanged.


Hi Johannes,
Thanks for the review!


> Are you reverting rebased Merge Requests commit by commit? If not, I would
> suggest the shortcut to use `merge-tree` directly for the entire Merge
> Request.


That's a great point. At GitLab, we have use cases for both approaches:

1.  For quick undoing an entire MR, the `merge-tree` approach you 
suggest is indeed more efficient and avoids unnecessary intermediate 
conflicts.

2. For commit-by-commit reverts, we need individual revert commits with 
proper attribution (which commit is being reverted) for auditability and 
history clarity. This is particularly useful when only specific commits 
from a merged branch need to be reverted.


I will add a note in the documentation mentioning the `merge-tree` 
alternative for whole-MR reverts.


> That is, if `$BASE` corresponds to the base branch onto which the
> Merge Request was rebased, and `$TIP` corresponds to the Merge Request's
> rebased tip commit, then the following will revert that Merge Request:
>
> 	git merge-tree --merge-base $TIP HEAD $BASE
>
> The upside is that this can potentially avoid a lot of unnecessary merge
> conflicts. The downside is that it does not revert the rebased Merge
> Request commit by commit.
>
> The patch itself looks fine to me, if a bit too extensive on the side of
> adding tests


Agreed. Looking at the tests again, I can consolidate several of them:
- The bare repo test can be merged with the basic revert test
- The multiple commits test overlaps with the basic functionality

I will trim down to essential coverage in v2: basic revert, conflict 
handling, and Reapply behavior.

Thanks,
Siddharth


> : Remember, a nimble test suite that catches a bug once is
> better than a long-running test suite that would catch a bug several times
> _iff_ it didn't tax the developer's patience so much that it is
> interrupted and aborted. You probably agree that Git's CI runtimes are
> already counter-productively long.
>
> Ciao,
> Johannes
>
>> The revert message generation logic is extracted into a new shared
>> `sequencer_format_revert_header()` function in `sequencer.c`, allowing
>> code reuse between `sequencer.c` and `builtin/replay.c`. The commit
>> messages follow `git revert` conventions, including "Revert"/"Reapply"
>> prefixes and the original commit SHA.
>>
>> This patch includes comprehensive tests covering various scenarios:
>> bare repositories, --advance mode, conflicts, reapply behavior, and
>> multiple commits.
>>
>> Siddharth Asthana (1):
>>    replay: add --revert option to reverse commit changes
>>
>>   Documentation/git-replay.adoc |  35 +++++++-
>>   builtin/replay.c              |  86 ++++++++++++++----
>>   sequencer.c                   |  23 +++++
>>   sequencer.h                   |   8 ++
>>   t/t3650-replay-basics.sh      | 160 ++++++++++++++++++++++++++++++++++
>>   5 files changed, 295 insertions(+), 17 deletions(-)
>>
>> -- 
>> 2.51.0
>>
>>

  parent reply	other threads:[~2025-11-26 19:19 UTC|newest]

Thread overview: 96+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-11-25 17:00 [PATCH 0/1] replay: add --revert option to reverse commit changes Siddharth Asthana
2025-11-25 17:00 ` [PATCH 1/1] " Siddharth Asthana
2025-11-25 19:22   ` Junio C Hamano
2025-11-25 19:30     ` Junio C Hamano
2025-11-25 19:39       ` Junio C Hamano
2025-11-25 20:06         ` Junio C Hamano
2025-11-26 19:31           ` Siddharth Asthana
2025-11-26 19:28         ` Siddharth Asthana
2025-11-26 19:26     ` Siddharth Asthana
2025-11-26 21:13       ` Junio C Hamano
2025-11-27 19:23         ` Siddharth Asthana
2025-11-26 11:10   ` Phillip Wood
2025-11-26 17:35     ` Elijah Newren
2025-11-26 18:41       ` Junio C Hamano
2025-11-26 21:17         ` Junio C Hamano
2025-11-26 23:06           ` Elijah Newren
2025-11-26 23:14             ` Junio C Hamano
2025-11-26 23:57               ` Elijah Newren
2025-11-26 19:50       ` Siddharth Asthana
2025-11-26 19:39     ` Siddharth Asthana
2025-11-27 16:21       ` Phillip Wood
2025-11-27 19:24         ` Siddharth Asthana
2025-11-25 17:25 ` [PATCH 0/1] " Johannes Schindelin
2025-11-25 18:02   ` Junio C Hamano
2025-11-26 19:18   ` Siddharth Asthana [this message]
2025-11-26 21:04     ` Junio C Hamano
2025-11-27 19:21       ` Siddharth Asthana
2025-11-27 20:17         ` Junio C Hamano
2025-11-28  8:07         ` Elijah Newren
2025-11-28  8:24           ` Siddharth Asthana
2025-11-28 16:35             ` Junio C Hamano
2025-11-28 17:07               ` Elijah Newren
2025-11-28 20:50                 ` Junio C Hamano
2025-11-28 22:03                   ` Elijah Newren
2025-11-29  5:59                     ` Junio C Hamano
2025-12-02 20:16 ` [PATCH v2 0/2] replay: add --revert mode " Siddharth Asthana
2025-12-02 20:16   ` [PATCH v2 1/2] sequencer: extract revert message formatting into shared function Siddharth Asthana
2025-12-05 11:33     ` Patrick Steinhardt
2025-12-07 23:00       ` Siddharth Asthana
2025-12-08  7:07         ` Patrick Steinhardt
2026-02-11 13:03           ` Toon Claes
2026-02-11 13:40             ` Patrick Steinhardt
2026-02-11 15:23             ` Kristoffer Haugsbakk
2026-02-11 17:41               ` Junio C Hamano
2026-02-18 22:53             ` Siddharth Asthana
2025-12-02 20:16   ` [PATCH v2 2/2] replay: add --revert mode to reverse commit changes Siddharth Asthana
2025-12-05 11:33     ` Patrick Steinhardt
2025-12-07 23:03       ` Siddharth Asthana
2025-12-16 16:23     ` Phillip Wood
2026-02-18 23:42   ` [PATCH v3 0/2] " Siddharth Asthana
2026-02-18 23:42     ` [PATCH v3 1/2] sequencer: extract revert message formatting into shared function Siddharth Asthana
2026-02-20 17:01       ` Toon Claes
2026-02-25 21:53         ` Junio C Hamano
2026-03-06  4:55           ` Siddharth Asthana
2026-03-06  4:31         ` Siddharth Asthana
2026-02-26 14:27       ` Phillip Wood
2026-03-06  5:00         ` Siddharth Asthana
2026-02-18 23:42     ` [PATCH v3 2/2] replay: add --revert mode to reverse commit changes Siddharth Asthana
2026-02-20 17:35       ` Toon Claes
2026-02-20 20:23         ` Junio C Hamano
2026-02-23  9:13         ` Christian Couder
2026-02-23 11:23           ` Toon Claes
2026-03-06  5:05         ` Siddharth Asthana
2026-02-26 14:45       ` Phillip Wood
2026-03-06  5:28         ` Siddharth Asthana
2026-03-06 15:52           ` Phillip Wood
2026-03-06 16:20             ` Siddharth Asthana
2026-03-13  5:40     ` [PATCH v4 0/2] " Siddharth Asthana
2026-03-13  5:40       ` [PATCH v4 1/2] sequencer: extract revert message formatting into shared function Siddharth Asthana
2026-03-13 15:53         ` Junio C Hamano
2026-03-16 19:12           ` Toon Claes
2026-03-16 16:57         ` Phillip Wood
2026-03-13  5:40       ` [PATCH v4 2/2] replay: add --revert mode to reverse commit changes Siddharth Asthana
2026-03-16 16:57         ` Phillip Wood
2026-03-16 19:52         ` Toon Claes
2026-03-17 10:11           ` Phillip Wood
2026-03-16 16:59       ` [PATCH v4 0/2] " Phillip Wood
2026-03-16 19:53       ` Toon Claes
2026-03-24 22:03       ` [PATCH v5 " Siddharth Asthana
2026-03-24 22:04         ` [PATCH v5 1/2] sequencer: extract revert message formatting into shared function Siddharth Asthana
2026-03-24 22:04         ` [PATCH v5 2/2] replay: add --revert mode to reverse commit changes Siddharth Asthana
2026-03-25  6:29           ` Junio C Hamano
2026-03-25 15:10             ` Toon Claes
2026-03-25 15:38               ` Siddharth Asthana
2026-03-25 16:44               ` Phillip Wood
2026-03-25 15:36             ` Siddharth Asthana
2026-03-25 20:23         ` [PATCH v6 0/2] " Siddharth Asthana
2026-03-25 20:23           ` [PATCH v6 1/2] sequencer: extract revert message formatting into shared function Siddharth Asthana
2026-03-25 20:23           ` [PATCH v6 2/2] replay: add --revert mode to reverse commit changes Siddharth Asthana
2026-03-28  4:33             ` Tian Yuchen
2026-03-29 16:17               ` Siddharth Asthana
2026-03-30 17:23                 ` Tian Yuchen
2026-03-31  8:08                   ` Toon Claes
2026-03-31  8:11                 ` Toon Claes
2026-03-25 20:23           ` [PATCH v6 1/2] sequencer: extract revert message formatting into shared function Siddharth Asthana
2026-03-25 20:23           ` [PATCH v6 2/2] replay: add --revert mode to reverse commit changes Siddharth Asthana

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