bug#4422: diff-switches is a bad idea

[Reuben Thomas]

On Tue, 1 Oct 2019 at 14:18, Lars Ingebrigtsen <larsi@gnus.org> wrote:

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?

Not as far as I can tell. It is still necessary for me to set `vc-diff-switches` explicitly, e.g. to `t`, meaning "no switches". From the docstring for vc-switches:

In decreasing order of preference, return the value of:
vc-BACKEND-OP-switches (e.g. `vc-cvs-diff-switches');
vc-OP-switches (e.g. `vc-diff-switches'); or, in the case of
diff only, `diff-switches'.

In other words, `diff-switches` is still used by vc.el, and I still think that's a bad idea.

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