bug#21695: 25.0.50; Change most occurrences of `setq' in Emacs manual to `customize-set-variable'? Really?

[Eli Zaretskii]

> From: Richard Stallman <rms@gnu.org>
> Date: Wed, 01 Sep 2021 23:42:04 -0400
> Cc: 21695@debbugs.gnu.org
> 
>   > Searching emacs 27.2 elisp source I find about 400 hits for :set.
> 
> That is more than I expected.  However, there around 8000 defcustoms
> in master as of May 11, and only 462 instances of :set.
> 
> Telling people to use customize-set-variable for all 8000 of them
> feels like the tail wagging the dog.

Yes.  But I don't see why the numbers matter here.  An option which
cannot be usefully change via setq mentions that in its doc string (or
at least it should; if it doesn't, that's a documentation bug), so all
we need to say in the manual is that such options exist, and they
announce the need to use customize-set-variable in their doc string by
such-and-such text.  Then the users will have enough information to
figure out which variable needs what method.

> I have a feeling that most of those 462 with :set actually require
> that people use customize-set-variable to set them in the init file.
> I suspect that, for most of them, :set is meant to handle the case
> where you change the setting once the feature is already in use.

That's an orthogonal issue, I think.  The issue at hand is how to
prevent users from mistakenly using setq where doing that is
insufficient.  We could independently see to it that the number of
options that actually need this is kept at a minimum.