feature/fix-mode-names-overlap ef86afda 6/6: Commit for initialization codes

[Ikumi Keita]

branch: feature/fix-mode-names-overlap
commit ef86afdac5d72e23096bb06fff7452b867545128
Author: Ikumi Keita <ikumi@ikumi.que.jp>
Commit: Ikumi Keita <ikumi@ikumi.que.jp>

    Commit for initialization codes
    
    * tex-site.el.in: Arrange initialization code to work with new major
    mode names, making use of Emacs 29 new feature
    `major-mode-remap-alist'.
    * tex.el (TeX-format-list, TeX-tex-mode, TeX-modes): Adapt doc strings
    and comments.
---
 tex-site.el.in | 57 ++++++++++++++++++++++++++++++++++++++++++---------------
 tex.el         | 29 ++++++++++++++++++++---------
 2 files changed, 62 insertions(+), 24 deletions(-)

diff --git a/tex-site.el.in b/tex-site.el.in
index 05ef1156..f788772b 100644
--- a/tex-site.el.in
+++ b/tex-site.el.in
@@ -46,6 +46,12 @@
   ;; Try and support the case where someone loads tex-site.el or
   ;; auctex.el directly, in the old way.
   (provide 'tex-site)        ;Avoid (re)loading tex-site from auctex-autoloads.
+
+  ;; Delete predefined autoloads by tex-mode.el so that AUCTeX
+  ;; autoloads provided aftarwards take precedence.
+  (fset 'plain-TeX-mode nil)
+  (fset 'LaTeX-mode nil)
+
   (load "auctex-autoloads" 'noerror 'nomessage))
 
 ;; Define here in order for `M-x customize-group <RET> AUCTeX <RET>'
@@ -82,12 +88,12 @@ shared by all users of a site."
   :type 'directory)
 
 (defconst TeX-mode-alist
-  '((tex-mode . tex-mode)
-    (plain-tex-mode . tex-mode)
-    (texinfo-mode . texinfo)
-    (latex-mode . tex-mode)
-    (doctex-mode . tex-mode))
-  "Alist of built-in TeX modes and their load files.")
+  '((tex-mode . TeX-tex-mode)
+    (plain-tex-mode . plain-TeX-mode)
+    (texinfo-mode . Texinfo-mode)
+    (latex-mode . LaTeX-mode)
+    (doctex-mode . docTeX-mode))
+  "Alist of built-in TeX modes and their counterparts in AUCTeX.")
 
 (defalias 'TeX-load-hack #'ignore)
 
@@ -100,25 +106,36 @@ shared by all users of a site."
 (defun TeX-modes-set (var value &optional _ignored)
   "Set VAR (which should be `TeX-modes') to VALUE.
 
-This places either the standard or the AUCTeX versions of
-functions into the respective function cell of the mode."
+Arrange the redirection of the built-in TeX modes according to VALUE.
+- The built-in modes in VALUE are redirected to the corresponding
+  AUCTeX major modes.
+- The built-in modes not in VALUE discard redirection, if any.
+If `major-mode-remap-alist' is available, use it for redirection.
+Otherwise, use advice facility."
   (custom-set-default var value)
-  (let ((list TeX-mode-alist) elt)
-    (while list
-      (setq elt (car (pop list)))
-      (let ((dst (intern (concat "TeX-" (symbol-name elt)))))
-        (if (memq elt value)
+  (let (elt dst)
+    (dolist (entry TeX-mode-alist)
+      (setq elt (car entry)
+            dst (cdr entry))
+      (if (memq elt value)
+          (if (boundp 'major-mode-remap-alist)
+              (push (cons elt dst) major-mode-remap-alist)
+            ;; COMPATIBILITY for Emacs<29
             (advice-add elt :override dst
                         ;; COMPATIBILITY for Emacs 28.[12]
                         ;; Give it higher precedence than the :around
                         ;; advice given to `tex-mode' in tex-mode.el.
                         ;; 
<URL:https://lists.gnu.org/r/auctex-devel/2022-09/msg00050.html>
-                        '((depth . -10)))
+                        '((depth . -10))))
+        (if (boundp 'major-mode-remap-alist)
+            (setq major-mode-remap-alist
+                  (assq-delete-all elt major-mode-remap-alist))
+          ;; COMPATIBILITY for Emacs<29
           (advice-remove elt dst))))))
 
 (defcustom TeX-modes
   (mapcar #'car TeX-mode-alist)
-  "List of modes provided by AUCTeX.
+  "List of built-in TeX modes redirected to AUCTeX modes.
 
 This variable can't be set normally; use customize for that, or
 set it with `TeX-modes-set'."
@@ -127,6 +144,16 @@ set it with `TeX-modes-set'."
   :set #'TeX-modes-set
   :initialize #'custom-initialize-reset)
 
+;; COMPATIBILITY for Emacs<29, which executes
+;; (defalias 'LaTeX-mode #'latex-mode) etc. in tex-mode.el.
+;; This `with-eval-after-load' should be removed when the supported
+;; emacsens version becomes 29 or higher and (defun TeX-LaTeX-mode
+;; ...) etc. are turned into (define-derived-mode LaTeX-mode ...) etc.
+(with-eval-after-load 'tex-mode
+  (progn
+    (defalias 'plain-TeX-mode #'TeX-plain-TeX-mode)
+    (defalias 'LaTeX-mode #'TeX-LaTeX-mode)))
+
 (defconst AUCTeX-version "@AUCTEXVERSION@"
   "AUCTeX version.
 If not a regular release, the date of the last change.")
diff --git a/tex.el b/tex.el
index f7810aa0..db8b9981 100644
--- a/tex.el
+++ b/tex.el
@@ -3675,12 +3675,12 @@ A list with an entry for each format package available 
at the site.
 
 Each entry is a list with three elements.
 
-1. The name of the format package.
-2. The name of the major mode.
+1. The name of the format package (as string).
+2. The name of the major mode (as symbol).
 3. A regexp typically matched in the beginning of the file.
 
-When entering `tex-mode', each regexp is tried in turn in order to find
-the major mode to be used.")
+When entering `TeX-tex-mode', each regexp is tried in turn in
+order to find the major mode to be used.")
 
 (defcustom TeX-default-mode #'LaTeX-mode
   "Mode to enter for a new file when it can't be determined otherwise."
@@ -3696,16 +3696,27 @@ the major mode to be used.")
 
 ;;;###autoload
 (defun TeX-tex-mode ()
-  "Major mode in AUCTeX for editing TeX or LaTeX files.
+  "Call suitable AUCTeX major mode for editing TeX or LaTeX files.
 Tries to guess whether this file is for plain TeX or LaTeX.
 
 The algorithm is as follows:
 
-   1) if the file is empty or `TeX-force-default-mode' is not set to nil,
-      `TeX-default-mode' is chosen
-   2) If \\documentstyle or \\begin{, \\section{, \\part{ or \\chapter{ is
+   1) If the file is empty or `TeX-force-default-mode' is not set to nil,
+      `TeX-default-mode' is chosen.
+   2) If non-commented out content matches with regular expression in
+      `TeX-format-list', use the associated major mode.  For example,
+      if \\documentclass or \\begin{, \\section{, \\part{ or \\chapter{ is
       found, `LaTeX-mode' is selected.
-   3) Otherwise, use `plain-TeX-mode'"
+   3) Otherwise, use `TeX-default-mode'.
+
+By default, `TeX-format-list' has a fallback entry for
+`plain-TeX-mode', thus non-empty file which didn't match any
+other entries will enter `plain-TeX-mode'."
+  ;; This is a dispatch function meaningful only as target of
+  ;; `auto-mode-alist' and `major-mode-remap-alist'.  Hence we don't
+  ;; use `define-derived-mode'.  Note that it isn't a proper major
+  ;; mode and it actually makes little sense to specify this for
+  ;; "mode:" tag of file local variable.
   (interactive)
 
   (funcall (if (or (equal (buffer-size) 0)