Subject: bug#4422: diff-switches is a bad idea

From: Lars Ingebrigtsen <[email-masked]>
Date: Tue, 01 Oct 2019 15:18:29 +0200

Reuben Thomas <[email-masked]> writes:

> I'm using Emacs 23, and I have just been puzzling over why vc-diff
> stopped working in CVS checkouts. I eventually traced it to
> diff-switches: I have mine set to "-Nur", quite reasonably, I think,
> but of course "-r" means something quite different to CVS, and I ended
> up with a hard-to-understand error message about tags.
>
> I suggest not using diff-switches (this would also remove some
> special-case code, as no other vc command respects a non-vc option
> like this.) Yes, some users will have to configure the same thing in
> two places, but others will be saved the confusion I had. For the
> switches to be commoned up sensibly, a more structured approach to
> setting them is needed that takes semantics into account, and that way
> lies madness.

(I'm going through old bug reports that unfortunately didn't get any
response at the time.)

I'm not extremely familiar with the vc code, but looking at it in Emacs
27, at least, the switches for diff in CVS comes from
vc-cvs-diff-switches, if I read the `vc-switches' function correctly.

So has this problem gone away in the years since this was reported?

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no