bug#58486: [PATCH] Prevent .dir-locals.el from being byte-compiled

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

>>> When selecting a number of .el files in Dired and byte-compiling them
>>> I'll usually also select a .dir-locals.el file that won't compile.
>>> Would annotating them as non-byte-compilable files be sensible?
>>
>> Makes sense to me, FWIW.  Though Stefan M might point out that these
>> files should actually be called ".dir-locals.eld".  Which, BTW, we
>> should probably add support for.  And "*.eld" files should never be
>> compiled, I think?
>
> It's already handled by auto-mode-alist:
>
>   (defvar auto-mode-alist
>        ...
>        ;; .dir-locals.el is not really Elisp.  Could use the
>        ;; `dir-locals-file' constant if it weren't defined below.
>        ("\\.dir-locals\\(?:-2\\)?\\.el\\'" . lisp-data-mode)

To stay in the spirit of bug#58075, if we consider the major mode
specified in `auto-mode-alist` (and `mode:` cookies) as a proxy for
"file type", maybe we should arrange to try and avoid byte-compiling
those `.el` files whose major mode is `lisp-data-mode` (or: is not
`emacs-lisp-mode`)?


        Stefan