Re: Aborting git rebase --edit-todo

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

Hi Victor,

On Thu, 3 Sep 2020, Victor Toni wrote:

> > It is rather unusual (or almost always wrong) to have a totally
> > empty commit log or initial todo list, so it is understandable for
> > Git in these situations to stop without doing anything further.
> >
> > There is no other sensible interpretations of what you are telling
> > Git to you by returning an empty buffer---it is extremely unlikely
> > you want to create a commit with no log message (without explicitly
> > allowing it with --allow-empty-message, the command is likely to
> > fail anyway), and it is extremely unlikely that you wanted to just
> > reset the tip of the branch to the --onto commit.
> >
> > Once an interactive rebase session has started and you are given the
> > remainder of the steps to edit and you give an empty buffer back,
> > however, there are two possible interpretations that are equally
> > sensible, I would think.
> >
> >  - One is that you are signaling that you are done with the rebase
> >    session and all the remaining commits are to be discarded.
> >
> >  - The other is that you botched editing the todo list, and you wish
> >    Git to give you another chance to edit it again.
> >
> > I think the implementor chose the first interpretation.  The "drop"
> > insn is a relatively recent invention, and back when it was missing
> > from the vocabulary, I do not think it was possible to say " discard
> > all the rest" without emptying the todo list, so that design is
> > understandable.
> >
> > Now we have the "drop" verb, the latter interpretation becomes
> > possible without making it impossible for the user to express the
> > former.  It might be a good idea to
> >
> >  (1) save away the original before allowing --edit-todo to edit,

We already do that:
https://github.com/git/git/blob/v2.28.0/rebase-interactive.c#L113-L115

> >
> >  (2) open the editor, and
> >
> >  (3) when getting an empty buffer back, go back to step (2) using
> >      the back-up made in step (1).

Yes, and we can claim that this is a bug fix to avoid having to respect a
deprecation phase.

> >
> > Either way, the todo list editor buffer can have additional comment
> > instructing what happens when the buffer is emptied.
> >
>
> Personally I would like to see your approach (1,2,3) implemented
> because it is not destructive. If the user wants to achieve something
> different he

or she, or they,

> can retry.
> Option / interpretation a)
>
> >  - One is that you are signaling that you are done with the rebase
> >    session and all the remaining commits are to be discarded.
>
> is more difficult to recover from. (I'm still thankful for `.git/logs/HEAD`)

Indeed, it is pretty tedious to recover from when you can originally made
edits to the todo list that you then accidentally discarded.

Ciao,
Dscho