Subject: Re: bug#74307: 30.0.92; emacs-lisp font-locking word regexp

From: Eli Zaretskii <[email-masked]>
Date: Thu, 14 Nov 2024 10:11:43 +0200

> From: Roland Winkler <[email-masked]>
> Date: Mon, 11 Nov 2024 00:28:34 -0600
> 
> Starting from emacs -Q, put the following into a buffer with
> emacs-lisp-mode
> 
>   (setq foo "\\<foo\\>")
> 
> The part "foo\\" of the string "\\<foo\\>" will get
> font-lock-variable-name-face, which looks odd.
> 
> I believe, this is due to a clause in lisp-mode.el that says
> 
>          ;; Words inside \\[], \\<>, \\{} or \\`' tend to be for
>          ;; `substitute-command-keys'.
> 
> But this assumption is not always correct, in particular if ">" is
> preceded by "\\", which happens when constructing regexps.

I believe you are saying that in

         (,(rx "\\\\" (or (seq "<" (group-n 1 lisp-mode-symbol) ">")
                          (seq "{" (group-n 1 lisp-mode-symbol) "}")))
          (1 font-lock-variable-name-face prepend))

we should use something like the below instead?

     (,(rx "\\\\" (or (seq "<" (group-n 1 lisp-mode-symbol) (not "\\\\") ">")
                      (seq "{" (group-n 1 lisp-mode-symbol) (not "\\\\") "}"))

And similarly for \\[] etc.?