bug#52349: 29.0.50; vc-git and diff-mode: stage hunks

[Dmitry Gutov]

On 21.08.2022 21:53, Juri Linkov wrote:
> > Another solution for making sure the current backend supports the new
> > feature is to add a new backend function. Call it 'checkin-patch' or
> > `checkin-diff`.
> >
> > vc-git-checkin and vc-git-checking patch can share some implementation, so
> > most of code duplication can be avoided.
> >
> > But when a backend does not support this, the user will see a more-or-less
> > understandable error like "not supported".
>
> So a new patch adds a new backend function 'checkin-patch':

Looks pretty good. Thank you.

> > Perhaps we should also check that there are no existing staged changes for
> > those files, and if so, abort? This way we won't commit anything else by
> > accident.
>
> Will do later.

Shouldn't be too hard, if we don't try to do it eagerly. Just add a 
check inside (when vc-git-patch-string ...) in vc-git-checkin.