Use `autoconf-mode' for Autoconf .m4 files

* lisp/files.el (auto-mode-alist): Use `autoconf-mode' (instead of
`m4-mode') for acinclude.m4/aclocal.m4/acsite.m4 files (bug#37133).

diff --git a/etc/NEWS b/etc/NEWS
index cf187598ce5f163d78b1d568e897658bf976e841..ec906aaf021cf568d358280ee4efb4141931c92f 100644 (file)
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -511,6 +511,10 @@ current and the previous or the next line, as before.
 \f
 * Changes in Specialized Modes and Packages in Emacs 27.1
 
+---
+** 'autoconf-mode' is now used instead of 'm4-mode' for the
+acinclude.m4/aclocal.m4/acsite.m4 files.
+
 ---
 ** On GNU/Linux, `M-x battery' will now list all batteries, no matter
 what they're named, and the `battery-linux-sysfs-regexp' variable has

diff --git a/lisp/files.el b/lisp/files.el
index f76635017d5caf771bc338b42d5eda7db99eb9c5..2a84c2c48f57f819895aec9f36e033918c445c65 100644 (file)
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -2719,6 +2719,8 @@ since only a single case-insensitive search through the alist is made."
      ("\\.bib\\'" . bibtex-mode)
      ("\\.bst\\'" . bibtex-style-mode)
      ("\\.sql\\'" . sql-mode)
+     ;; These .m4 files are Autoconf files.
+     ("\\(acinclude\\|aclocal\\|acsite\\)\\.m4\\'" . autoconf-mode)
      ("\\.m[4c]\\'" . m4-mode)
      ("\\.mf\\'" . metafont-mode)
      ("\\.mp\\'" . metapost-mode)