From d01a33662c2b4606ee35a44493e9fab73bdbe3b5 Mon Sep 17 00:00:00 2001 From: "Basil L. Contovounesios" Date: Mon, 13 Oct 2025 16:19:42 +0200 Subject: [PATCH] Improve m4-mode font lock Emacs 28 started fontifying several 'composite' (non-builtin) GNU M4 macros which, while listed under '(m4) Macro index', are not defined by GNU M4, and are included in its manual for illustrative purposes. These macro keywords range from clearly misleading (e.g., 'example', which the GNU M4 manual explicitly describes as nonexistent), to common in Autoconf's M4sugar layer (e.g., 'm4_quote'), to variations thereof (e.g., 'foreachq'). It is arguably too late to revert all of these additions, so this patch selects a handful to remove, and categorizes the rest; this should make it easier to hide some categories behind a font lock level or user option in the future, if desired. This patch reverts the Emacs 28 addition of 'example', and removes the older 'file', 'line', and 'gnu' macros. GNU M4 renamed 'gnu' to '__gnu__' already in 1990; and I couldn't find references to the other two which exist as '__file__' and '__line__', respectively. The remaining macros are partitioned into three sets: built-in, M4sugar-like, and other (bug#80412). For discussion, see also: https://lists.gnu.org/r/emacs-devel/2025-10/msg00357.html * lisp/progmodes/m4-mode.el (m4-program-options): Remove stale commentary. (m4--macro-list): Remove, replacing with... (m4--builtin, m4--autoconf, m4--composite): ...these new rx definitions. All uses changed. Remove 'example', 'file', 'gnu', and 'line' as keywords. (m4-font-lock-keywords): For consistency with real #-comments, fontify dnl macro with font-lock-comment-delimiter-face, and only the rest of its line with font-lock-comment-face. Fontify argument references with font-lock-variable-use-face rather than font-lock-variable-name-face. Use font lock faces rather than their eponymous but obsolete variables. Remove redundant entries for $@ and $*. Prefer shy regexp groups where applicable. (m4-mode-syntax-table): Quote syntactically special characters. (m4-m4-buffer): DRY using m4-m4-region. (m4-m4-region): Take region bounds as optional arguments, as recommended under '(elisp) The Mark'. Quote shell command. Support non-contiguous regions. (m4-current-defun-name): Recognize m4 backtick in addition to Autoconf bracket. Prefer shy regexp groups where applicable. (m4-mode): Simplify font-lock-defaults. * test/lisp/progmodes/m4-mode-resources/font-lock.m4: * test/lisp/progmodes/m4-mode-tests.el: New test files. --- lisp/progmodes/m4-mode.el | 94 ++++++++++--------- .../progmodes/m4-mode-resources/font-lock.m4 | 30 ++++++ test/lisp/progmodes/m4-mode-tests.el | 55 +++++++++++ 3 files changed, 134 insertions(+), 45 deletions(-) create mode 100644 test/lisp/progmodes/m4-mode-resources/font-lock.m4 create mode 100644 test/lisp/progmodes/m4-mode-tests.el diff --git a/lisp/progmodes/m4-mode.el b/lisp/progmodes/m4-mode.el index eff74530c3b..9f3d2bb3448 100644 --- a/lisp/progmodes/m4-mode.el +++ b/lisp/progmodes/m4-mode.el @@ -50,7 +50,6 @@ If m4 is not in your PATH, set this to an absolute file name." :version "24.4" :type 'file) -;;options to m4 (defcustom m4-program-options nil "Options to pass to `m4-program'." :type '(repeat string)) @@ -60,34 +59,40 @@ If m4 is not in your PATH, set this to an absolute file name." ;;or ;;(defconst m4-program-options '("--prefix-builtins")) -;; Needed at compile-time for `m4-font-lock-keywords' below. -(eval-and-compile - (defconst m4--macro-list - ;; From (info "(m4) Macro index") - '("__file__" "__gnu__" "__line__" "__os2__" "__program__" "__unix__" - "__windows__" "argn" "array" "array_set" "builtin" "capitalize" - "changecom" "changequote" "changeword" "cleardivert" "cond" "copy" - "curry" "debugfile" "debugmode" "decr" "define" "define_blind" - "defn" "divert" "divnum" "dnl" "downcase" "dquote" "dquote_elt" - "dumpdef" "errprint" "esyscmd" "eval" "example" "exch" - "fatal_error" "file" "foreach" "foreachq" "forloop" "format" "gnu" - "ifdef" "ifelse" "include" "incr" "index" "indir" "join" "joinall" - "len" "line" "m4exit" "m4wrap" "maketemp" "mkstemp" "nargs" "os2" - "patsubst" "popdef" "pushdef" "quote" "regexp" "rename" "reverse" - "shift" "sinclude" "stack_foreach" "stack_foreach_lifo" - "stack_foreach_sep" "stack_foreach_sep_lifo" "substr" "syscmd" - "sysval" "traceoff" "traceon" "translit" "undefine" "undivert" - "unix" "upcase" "windows") - "List of valid m4 macros for M4 mode.")) +;; Matches the name of m4 built-in macros. +;; From (info "(m4) Macro index"), modulo sample composite macros. +(rx-define m4--builtin + (| "__file__" "__gnu__" "__line__" "__os2__" "__program__" "__unix__" + "__windows__" "builtin" "changecom" "changequote" "changeword" + "debugfile" "debugmode" "decr" "define" "defn" "divert" "divnum" + "dnl" "dumpdef" "errprint" "esyscmd" "eval" "format" "ifdef" "ifelse" + "include" "incr" "index" "indir" "len" "m4exit" "m4wrap" "maketemp" + "mkstemp" "os2" "patsubst" "popdef" "pushdef" "regexp" "shift" + "sinclude" "substr" "syscmd" "sysval" "traceoff" "traceon" "translit" + "undefine" "undivert" "unix" "windows")) + +;; Matches the name of m4 composite macros with analogues in M4sugar. +(rx-define m4--autoconf + (| "argn" "cleardivert" "cond" "copy" "curry" "dquote" "dquote_elt" + "foreach" "join" "joinall" "quote" "rename" "reverse" "stack_foreach" + "stack_foreach_lifo" "stack_foreach_sep" "stack_foreach_sep_lifo")) + +;; Matches the name of other m4 composite macros given as examples in +;; the manual or sources of GNU M4. +(rx-define m4--composite + (| "array" "array_set" "capitalize" "define_blind" "downcase" + "exch" "fatal_error" "foreachq" "forloop" "nargs" "upcase")) (defvar m4-font-lock-keywords (eval-when-compile - `(("\\(\\_<\\(m4_\\)?dnl\\_>\\).*$" (0 font-lock-comment-face t)) - ("\\$[*#@0-9]" . font-lock-variable-name-face) - ("\\$@" . font-lock-variable-name-face) - ("\\$\\*" . font-lock-variable-name-face) - (,(concat "\\_<\\(m4_\\)?" (regexp-opt m4--macro-list) "\\_>") - . font-lock-keyword-face))) + `(("\\(\\_<\\(?:m4_\\)?dnl\\_>\\)\\(.*\\)$" + (1 'font-lock-comment-delimiter-face t) + (2 'font-lock-comment-face t)) + ("\\$[*#@0-9]" . 'font-lock-variable-use-face) + ,(rx symbol-start + (? "m4_") + (| m4--builtin m4--autoconf m4--composite) + symbol-end))) "Default `font-lock-keywords' for M4 mode.") (defcustom m4-mode-hook nil @@ -98,11 +103,11 @@ If m4 is not in your PATH, set this to an absolute file name." (defvar m4-mode-syntax-table (let ((table (make-syntax-table))) (modify-syntax-entry ?` "('" table) - (modify-syntax-entry ?' ")`" table) + (modify-syntax-entry ?\' ")`" table) (modify-syntax-entry ?# "<\n" table) (modify-syntax-entry ?\n ">#" table) - (modify-syntax-entry ?{ "." table) - (modify-syntax-entry ?} "." table) + (modify-syntax-entry ?\{ "." table) + (modify-syntax-entry ?\} "." table) (modify-syntax-entry ?_ "_" table) (modify-syntax-entry ?* "." table) (modify-syntax-entry ?\" "." table) @@ -140,27 +145,26 @@ If m4 is not in your PATH, set this to an absolute file name." (defun m4-m4-buffer () "Send contents of the current buffer to m4." (interactive) - (shell-command-on-region - (point-min) (point-max) - (mapconcat #'identity (cons m4-program m4-program-options) "\s") - "*m4-output*" nil) - (switch-to-buffer-other-window "*m4-output*")) + (m4-m4-region (point-min) (point-max))) -(defun m4-m4-region () - "Send contents of the current region to m4." - (interactive) - (shell-command-on-region - (point) (mark) - (mapconcat #'identity (cons m4-program m4-program-options) "\s") - "*m4-output*" nil) - (switch-to-buffer-other-window "*m4-output*")) +(defun m4-m4-region (&optional start end) + "Send the contents of the region between START and END to m4. +When nil, START and END default to the active region." + (interactive "r") + (let ((buf "*m4-output*")) + (shell-command-on-region + (or start (region-beginning)) (or end (region-end)) + (mapconcat #'shell-quote-argument (cons m4-program m4-program-options) " ") + buf nil nil nil (use-region-noncontiguous-p)) + (pop-to-buffer buf))) (defun m4-current-defun-name () "Return the name of the M4 function at point, or nil." (save-excursion (if (re-search-backward - "^\\(\\(m4_\\)?define\\|A._DEFUN\\)(\\[?\\([A-Za-z0-9_]+\\)" nil t) - (match-string-no-properties 3)))) + "^\\(?:\\(?:m4_\\)?define\\|A._DEFUN\\)([[`]?\\([A-Za-z0-9_]+\\)" + nil t) + (match-string-no-properties 1)))) ;;;###autoload (define-derived-mode m4-mode prog-mode "m4" @@ -169,7 +173,7 @@ If m4 is not in your PATH, set this to an absolute file name." (setq-local parse-sexp-ignore-comments t) (setq-local add-log-current-defun-function #'m4-current-defun-name) (setq-local syntax-propertize-function m4-syntax-propertize) - (setq-local font-lock-defaults '(m4-font-lock-keywords nil))) + (setq-local font-lock-defaults '(m4-font-lock-keywords))) (provide 'm4-mode) ;;stuff to play with for debugging diff --git a/test/lisp/progmodes/m4-mode-resources/font-lock.m4 b/test/lisp/progmodes/m4-mode-resources/font-lock.m4 new file mode 100644 index 00000000000..90a6f333cf9 --- /dev/null +++ b/test/lisp/progmodes/m4-mode-resources/font-lock.m4 @@ -0,0 +1,30 @@ +# comment +# <- font-lock-comment-delimiter-face +# ^ font-lock-comment-face + + #comment +# ^ font-lock-comment-delimiter-face +# ^ font-lock-comment-face + +dnl discarded +# <- font-lock-comment-delimiter-face +# ^ font-lock-comment-face + + dnl`'discarded +# ^^^ font-lock-comment-delimiter-face +# ^^^ font-lock-comment-face + +define(`a', `$#`$*'$@') +# <- font-lock-keyword-face +# ^^ ^^ ^^ font-lock-variable-use-face + + m4_define(`b', ``$0$1$2$3$4`'$5$6$7$8$9'') +# ^^^^^^^^^ font-lock-keyword-face +# ^^^^^^^^^^ ^^^^^^^^^^ font-lock-variable-use-face + + m4`'_define(`c', `') +# ^^^^^^^^^^^ !font-lock-keyword-face + +m4_`'define(`d', `') +# <- !font-lock-keyword-face +# ^^^^^^ font-lock-keyword-face diff --git a/test/lisp/progmodes/m4-mode-tests.el b/test/lisp/progmodes/m4-mode-tests.el new file mode 100644 index 00000000000..e04d7d49fa8 --- /dev/null +++ b/test/lisp/progmodes/m4-mode-tests.el @@ -0,0 +1,55 @@ +;;; m4-mode-tests.el --- tests for m4-mode.el -*- lexical-binding: t -*- + +;; Copyright (C) 2025 Free Software Foundation, Inc. + +;; This file is part of GNU Emacs. + +;; GNU Emacs is free software: you can redistribute it and/or modify +;; it under the terms of the GNU General Public License as published by +;; the Free Software Foundation, either version 3 of the License, or +;; (at your option) any later version. + +;; GNU Emacs is distributed in the hope that it will be useful, +;; but WITHOUT ANY WARRANTY; without even the implied warranty of +;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +;; GNU General Public License for more details. + +;; You should have received a copy of the GNU General Public License +;; along with GNU Emacs. If not, see . + +;;; Code: + +(require 'ert) +(require 'ert-font-lock) +(require 'm4-mode) + +(ert-deftest m4-current-defun-name () + "Test `m4-current-defun-name' behavior." + (with-temp-buffer + (m4-mode) + (insert "define(`a', `')") + (should (equal (m4-current-defun-name) "a")) + ;; Not at toplevel. + (insert "define(`b', `')") + (should (equal (m4-current-defun-name) "a")) + (insert "\nm4_define(`c', `')") + (should (equal (m4-current-defun-name) "c")) + (insert "\nAC_DEFUN([d], [])") + (should (equal (m4-current-defun-name) "d")) + (insert "\nAU_DEFUN([e], [])") + (should (equal (m4-current-defun-name) "e")))) + +(ert-deftest m4-mode-comment-syntax () + "Test `m4-mode' comment syntax." + (with-temp-buffer + (m4-mode) + (insert "# comment") + (should (eq (syntax-ppss-context (syntax-ppss)) 'comment)) + (insert ?\n) + (should-not (syntax-ppss-context (syntax-ppss))))) + +(ert-font-lock-deftest-file m4-mode-font-lock + "Test `m4-mode' font lock." + m4-mode "font-lock.m4") + +;;; m4-mode-tests.el ends here