Add support for drop!/reword! commits to `git rebase -i`

[dscho]

This was already discussed briefly on the Git mailing list: https://public-inbox.org/git/alpine.DEB.2.21.1.1710151754070.40514@virtualbox/

In short, the reword! semantics are relatively easy in my mind: it would be called as

git commit --reword <commit>

would take staged changes (if any), otherwise implicitly --allow-empty,
then create a commit message to be edited in this style:

reword! <original-oneline>

<original-oneline>

<original-body>

This would be presented to the user in an editor (similar to git commit --amend).

Upon rebase --autosquash, it would work like a squash! but comment out all
previous commit messages, and also comment out the reword! line and the
empty line after that.

In case of multiple reword!, the last one would win, and it would
naturally integrate in any fixup!/squash! workflow.

What is more difficult is something else I frequently need: drop!
. That is, I want to explicitly mark a commit to be excluded in
subsequent rebase --autosquash. I guess the best way would be to
implement a

git revert --drop <commit>

that would work as if you called git revert -n <commit> && git commit -m 'drop! '"$(git show -s --oneline <commit>)", and upon rebase --autosquash, it would reorder like fixup!/squash!/reword!, replace the pickof the previous line (if it was apick) by dropand comment out the currentpick drop! ` line.

The reason why the semantics are more difficult in that case is that drop!
does not mix well with fixup!/squash!/reword!.

[Hasaber8]

Has this project already been taken up or is still available to be worked upon?
-Rohan

[dscho]

I am unaware of any effort so far, so go right ahead!

[Hasaber8]

Correct me if I'm wrong , currently even if we try and skip a single commit in git rebase -i it gets squashed, without it been shown in th editor.

[dscho]

Correct me if I'm wrong , current even if we try and skip a single commit in git rebase -i it gets squashed, without it been shown in th editor.

If I understand your question right, you're asking whether git rebase --skip still applies the currently-picked commit? It does not...

[Hasaber8]

Correct me if I'm wrong , current even if we try and skip a single commit in git rebase -i it gets squashed, without it been shown in th editor.

If I understand your question right, you're asking whether git rebase --skip still applies the currently-picked commit? It does not...

The drop! semantics if executed properly will be a very good thing to use! This surely will be an interesting project to do!

[phillipwood]

I've got some patches that implement the reword! part of this as amend! They need a little work - adding documentation, checking the test coverage and adjusting them to accommodate the recent changes to handling empty commits if anyone wants to pick them up

[phillipwood]

git revert --drop <commit>

that would work as if you called git revert -n <commit> && git commit -m 'drop! '"$(git show -s --oneline <commit>)",

Do we need to actually do the revert? - If we want to drop the commit can't we use an empty commit (git commit -m 'drop! '"$(git show -s --oneline <commit>)")? If we actually try to revert the commit there is the potential for conflicts when running revert which would create unnecessary work for the user.

Edit: We need the revert so that the effects of the dropped commit are reversed for any commits we build on top of the drop! commit before we rebase.

[dscho]

git revert --drop <commit>

that would work as if you called git revert -n <commit> && git commit -m 'drop! '"$(git show -s --oneline <commit>)",

Do we need to actually do the revert?

Yes. The point of dropping a given commit is to drop its changes, too, and that's a revert. Otherwise the tree after git revert --drop <commit> would not have dropped the changes!

[LemmingAvalanche]

Isn’t all of this implemented now?

[dscho]

Isn’t all of this implemented now?

I might have missed it, is the drop! part implemented now?

[LemmingAvalanche]

@dscho Oh no sorry, I just tested (git version 2.46.2) and git rebase -i --autosquash does not translate drop! commits to the drop command in the todo editor.

Disregard that.