bug#58888: 28.1.90; font-lock-defaults not respected when hack-local-variables unsafe variable dialogue is displayed before setting the defaults

[Stefan Monnier via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

> Any idea how many major modes out there don't use run-mode-hooks?

Hard to tell.  I did a quick

    grep '^[^;]*kill-all-local-variables' $(grep -L run-mode-hooks **/*.el)

in our own code, and it shows a fairly large number of occurrences, but
once you look at them it's not clear what to make of them.  Many of them
don't bother to define an actual mode for the buffer, they just call
`kill-all-local-variables` then fill the buffer somehow, occasionally do
some major-mode-like setup such as `use-local-map`, and finally display
the result to the user.

> We are basically breaking those with this change, right?

Yes.  More specifically the minor modes defined with
`define-globalized-minor-mode` will stay inactive in them.

> Please don't quote `like this`.  (I think you should by now have a
> commit hook in your init files that replaces the quoting with our
> style, because this seems to be ubiquitous in all your writings.)

I do my best to follow the ugly `...' convention in ELisp file and the
'...' convention in our other files, but not for anything else.
I strongly prefer the Markdown convention over '...' because it's
a convention enshrined in many tools.  I could live with the Org
convention if you prefer, but I strongly feel that we should
use notational conventions that tools are able to use.

> IMO, this NEWS entry is not detailed enough.  First, it should mention
> that run-mode-hooks is the modern way of running the mode's hook, a
> replacement for run-hooks.  And second, it should at least hint on
> what will happen with modes which don't use run-mode-hooks, so that
> affected users could identify the problem when they see its signs.
>
> Also, I think we should tell in the ELisp manual that run-mode-hooks
> is now a must, not just a preference, and we should mention in the
> Minor Modes chapter that the globalized minor modes will work
> correctly only if the major mode uses run-mode-hooks to run its hooks.

I'll get back to this once we decide we do want the change.


        Stefan