Re: editing a VC diff to modify the current version

[Prabath Liyanage <pliyanag@byteecho.net>]

emacsq via Users list for the GNU Emacs text editor
<help-gnu-emacs@gnu.org> writes:

> When I tried vscode I found an interesting feature:
>
> When I modify a file under VC then I always make a diff before checkin to see everything is right. Sometimes the changes have a typo or a simple modification occurs to me which could be done right in the diff. With vscode you can actually edit the diff and the changes are reflected back to the current version, so you don't have to go back to the file, do the modifications, make a diff again to see everything is right, etc.
>
> Emacs' manual mentions this about editing diffs:
>
> You can edit a Diff mode buffer like any other buffer. (If it is read-only, you need to make it writable first; see[Misc Buffer](https://www.gnu.org/software/emacs/manual/html_node/emacs/Misc-Buffer.html).) Whenever you edit a hunk, Diff mode attempts to automatically correct the line numbers in the hunk headers, to ensure that the patch remains correct, and could still be applied bypatch. To disable automatic line number correction, change the variablediff-update-on-the-flytonil.
>
> So it seems like emacs supports the other direction, treating the diff as a patch file which can be applied to the original to get the current version.
>
> These days comparing the current file to the last version under VC seems more usual, people more often make diffs before commit to see if their current changes are right, than doing it to make sure the patch file they create is correct.
>
> Can emacs support the workflow described above? That is applying edits in the diff buffer automatically to the file on disk. If not then it could be a useful improvement.

Maybe I am off the mark here, does vc-ediff/vc-diff or magit-ediff
(assuming you're using git) meet your requirements?