Hi,
Somebody noticed that if you use the m4_ prefixed versions of m4 keywords, they weren't being highlighted correctly. I have a patch. Also updated my email address as author and maintainer.
diff -u build/emacs-24.5/lisp/progmodes/m4-mode.el m4-mode.el
--- build/emacs-24.5/lisp/progmodes/m4-mode.el 2015-04-02 03:23:06.000000000 -0400
+++ m4-mode.el 2015-09-18 21:12:54.606254163 -0400
@@ -2,8 +2,8 @@
;; Copyright (C) 1996-1997, 2001-2015 Free Software Foundation, Inc.
-;; Author: Andrew Csillag <address@hidden>
-;; Maintainer: Andrew Csillag <address@hidden>
+;; Author: Andrew Csillag <address@hidden>
+;; Maintainer: Andrew Csillag <address@hidden>
;; Keywords: languages, faces
;; This file is part of GNU Emacs.
@@ -70,8 +70,7 @@
("address@hidden" . font-lock-variable-name-face)
("\\\$\\\@" . font-lock-variable-name-face)
("\\\$\\\*" . font-lock-variable-name-face)
- ("\\b\\(builtin\\|change\\(com\\|quote\\|word\\)\\|d\\(e\\(bug\\(file\\|mode\\)\\|cr\\|f\\(ine\\|n\\)\\)\\|iv\\(ert\\|num\\)\\|nl\\|umpdef\\)\\|e\\(rrprint\\|syscmd\\|val\\)\\|f\\(ile\\|ormat\\)\\|gnu\\|i\\(f\\(def\\|else\\)\\|n\\(c\\(lude\\|r\\)\\|d\\(ex\\|ir\\)\\)\\)\\|l\\(en\\|ine\\)\\|m\\(4\\(exit\\|wrap\\)\\|aketemp\\)\\|p\\(atsubst\\|opdef\\|ushdef\\)\\|regexp\\|s\\(hift\\|include\\|ubstr\\|ys\\(cmd\\|val\\)\\)\\|tra\\(ceo\\(ff\\|n\\)\\|nslit\\)\\|un\\(d\\(efine\\|ivert\\)\\|ix\\)\\)\\b" . font-lock-keyword-face)
- ("\\b\\(m4_\\(builtin\\|change\\(com\\|quote\\|word\\)\\|d\\(e\\(bug\\(file\\|mode\\)\\|cr\\|f\\(ine\\|n\\)\\)\\|iv\\(ert\\|num\\)\\|nl\\|umpdef\\)\\|e\\(rrprint\\|syscmd\\|val\\)\\|f\\(ile\\|ormat\\)\\|i\\(f\\(def\\|else\\)\\|n\\(c\\(lude\\|r\\)\\|d\\(ex\\|ir\\)\\)\\)\\|l\\(en\\|ine\\)\\|m\\(4\\(_undefine\\|exit\\|wrap\\)\\|aketemp\\)\\|p\\(atsubst\\|opdef\\|ushdef\\)\\|regexp\\|s\\(hift\\|include\\|ubstr\\|ys\\(cmd\\|val\\)\\)\\|tra\\(ceo\\(ff\\|n\\)\\|nslit\\)\\|undivert\\)\\)\\b" . font-lock-keyword-face))
+ ("\\b\\(m4_\\)?\\(builtin\\|change\\(com\\|quote\\|word\\)\\|d\\(e\\(bug\\(file\\|mode\\)\\|cr\\|f\\(ine\\|n\\)\\)\\|iv\\(ert\\|num\\)\\|nl\\|umpdef\\)\\|e\\(rrprint\\|syscmd\\|val\\)\\|f\\(ile\\|ormat\\)\\|gnu\\|i\\(f\\(def\\|else\\)\\|n\\(c\\(lude\\|r\\)\\|d\\(ex\\|ir\\)\\)\\)\\|l\\(en\\|ine\\)\\|m\\(4\\(exit\\|wrap\\)\\|aketemp\\)\\|p\\(atsubst\\|opdef\\|ushdef\\)\\|regexp\\|s\\(hift\\|include\\|ubstr\\|ys\\(cmd\\|val\\)\\)\\|tra\\(ceo\\(ff\\|n\\)\\|nslit\\)\\|un\\(d\\(efine\\|ivert\\)\\|ix\\)\\)\\b" . font-lock-keyword-face))
"Default font-lock-keywords for `m4 mode'.")
(defcustom m4-mode-hook nil
Cheers,
Drew