bug#73387: 30.0.90; C-x v v in diff-mode doesn't work after C-c C-n

[Sean Whitton <spwhitton@spwhitton.name>]

Hello,

On Tue 24 Sep 2024 at 08:36pm +03, Dmitry Gutov wrote:

> OTOH, maybe what you want to do here could be reached some other way -
> e.g. instead of 'C-x n n' we would have a command which edits the diff buffer
> to leave in only the hunks intersecting the current region. When the
> subsequent (buffer-string) would do the right thing.
>
> The latter might also be a better fit for the overall workflow we were
> thinking about (create a diff -> alter it as necessary -> commit).

Yeah, I already wrote something like that for my init.el.  I would like
to find some way to combine it with the existing C-c C-n, if we can.

Maybe:
if (equal (diff-bounds-of-hunk) (list (point-min) (point-max)),
then C-x v v prompts, "Kill all hunks but this one and commit? (y/n)" ?

Else if the buffer is narrowed, C-x v v signals a user-error that it
can't handle arbitrary narrowings.

Then it's just C-c C-n C-x v v but you're asked to confirm before all
the killing occurs, just in case.

-- 
Sean Whitton