True, looking at the new regexp in emacs the escape characters are highlighted in red, indicating an error. I can verify Mattias' modification still works for me.
I can't properly verify the bracketed version of the warning since I don't get those with my ModelSim, but if I manually type out a warning with brackets it does get highlighted when using re-builder. With Reto's modification on the other hand
the bracket warning is not highlighted.
From: Mattias Engdegård <mattiasengdegard@gmail.com> on behalf of Mattias Engdegård <mattias.engdegard@gmail.com>
Sent: Saturday, April 1, 2023 2:01:19 PM
To: reto@gnu.org <reto@gnu.org>
Cc: Cyril Arnould <cyril.arnould@outlook.com>; Eli Zaretskii <eliz@gnu.org>; friedrich.beckmann@gmx.de <friedrich.beckmann@gmx.de>; 62508@debbugs.gnu.org <62508@debbugs.gnu.org>
Subject: bug#62508: 28.2; vhdl-mode ModelSim compile warnings aren't highlighted
The new regexp,
"^\\(ERROR\\|WARNING\\|\\*\\* Error\\|\\*\\* Warning\\)[^:]*:\\( *\[[0-9]\]\\| ([^)]+)\\)? \\([^ \t\n]+\\)(\\([0-9]+\\)):"
^^^^^^^^^
isn't quite right: there are single-escaped square brackets, and the original regexp permitted multiple digits, not just one, between square brackets. The part
"\[[0-9]\]"
should probably be
"\\[[0-9]+]"
but the author needs to confirm this.