Emacs 27 problem with :local keyword in defcustom

[Ikumi Keita]

Hi Arash,

I noticed that emacs 27.1 fails with the current AUCTeX master. When I
open circ.tex with emacs 27.1, it signals error with
"(wrong-type-argument number-or-marker-p nil)" in `TeX-auto-parse'. The
local values of `TeX-auto-parse-length' and `TeX-auto-x-parse-length'
are both nil in the circ.tex buffer.

It seems that it is due to introduction of :local keyword in defcustom:
,----
| 77a02f837a0d32e2f7b47764d6e7f64ad76001ba
| Author:     Arash Esbati <arash@gnu.org>
| AuthorDate: Thu Jan 18 22:55:12 2024 +0100
| Commit:     Arash Esbati <arash@gnu.org>
| CommitDate: Thu Jan 18 22:55:12 2024 +0100
| 
| Mark options as buffer-local with the :local keyword
`----
As far as I can see, it is a bug of emacs 27.1. The function
`custom-declare-variable', which is the essential part of `defcustom',
puts the `make-variable-buffer-local' declaration _before_ the actual
`defvar', thus ending up with inconsistent local values.

Hence we have to refrain from using :local in `defcustom' until we drop
support for emacs 27 :-(

Regards,
Ikumi Keita
#StandWithUkraine #StopWarInUkraine
#Gaza #StopMassiveKilling #CeasefireNOW