bug#58888: 28.1.90; font-lock-defaults not respected when hack-local-variables unsafe variable dialogue is displayed before setting the defaults

[Stefan Monnier]

>> I pushed that patch to m`aster` because it fixed other cases
>> (e.g. bug#69431) but I think to fix bug#58888 we need the next step,
>> which is the patch below.
>>
>> Can you confirm that it fixes it for you as well?
>
> Yes, after make bootstrap, I am no longer able to reproduce the recipe.

Thanks for confirming.
Eli, any objection to the patch below?


        Stefan

>From 4fd9a51b4d9f2e2e0c04341eeabb656884059301 Mon Sep 17 00:00:00 2001
From: Stefan Monnier <monnier@iro.umontreal.ca>
Date: Wed, 10 Apr 2024 16:31:58 -0400
Subject: [PATCH] (define-globalized-minor-mode): Require the use of
 `run-mode-hooks`

When `define-globalized-minor-mode` was introduced (Emacs-22),
`run-mode-hooks` was brand new, so we could not expect all major
modes to use it and we had to rely on brittle workarounds to try
and approximate `after-change-major-mode-hook`.

These workarounds have undesirable side effects, and they're not
needed any more now that virtually all major modes have been
changed to use `run-mode-hooks`.

* lisp/emacs-lisp/easy-mmode.el (define-globalized-minor-mode):
Rely only on `after-change-major-mode-hook`.  Fixes bug#58888.
---
 etc/NEWS                      |  6 ++++
 lisp/emacs-lisp/easy-mmode.el | 58 +++--------------------------------
 2 files changed, 10 insertions(+), 54 deletions(-)

diff --git a/etc/NEWS b/etc/NEWS
index a2a3fe494cb..0da59201e55 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -1658,6 +1658,12 @@ documentation and examples.
 
 * Incompatible Lisp Changes in Emacs 30.1
 
+** 'define-globalized-minor-mode' requires that modes use 'run-mode-hooks'.
+Minor modes defined with 'define-globalized-minor-mode', such as
+'global-font-lock-mode', don't work any more with major modes which
+don't use 'run-mode-hooks'.  Major modes defined with
+'define-derived-mode' are not affected.
+
 ---
 ** Old derived.el functions removed.
 The following functions have been deleted because they were only used
diff --git a/lisp/emacs-lisp/easy-mmode.el b/lisp/emacs-lisp/easy-mmode.el
index 095bd5faa03..eaad9646985 100644
--- a/lisp/emacs-lisp/easy-mmode.el
+++ b/lisp/emacs-lisp/easy-mmode.el
@@ -495,11 +495,6 @@ define-globalized-minor-mode
         (MODE-buffers (intern (concat global-mode-name "-buffers")))
         (MODE-enable-in-buffer
          (intern (concat global-mode-name "-enable-in-buffer")))
-        (MODE-enable-in-buffers
-         (intern (concat global-mode-name "-enable-in-buffers")))
-        (MODE-check-buffers
-         (intern (concat global-mode-name "-check-buffers")))
-        (MODE-cmhh (intern (concat global-mode-name "-cmhh")))
         (minor-MODE-hook (intern (concat mode-name "-hook")))
         (MODE-set-explicitly (intern (concat mode-name "-set-explicitly")))
         (MODE-major-mode (intern (concat (symbol-name mode) "-major-mode")))
@@ -559,14 +554,9 @@ define-globalized-minor-mode
 
         ;; Setup hook to handle future mode changes and new buffers.
         (if ,global-mode
-            (progn
-              (add-hook 'after-change-major-mode-hook
-                        #',MODE-enable-in-buffer)
-              (add-hook 'find-file-hook #',MODE-check-buffers)
-              (add-hook 'change-major-mode-hook #',MODE-cmhh))
-          (remove-hook 'after-change-major-mode-hook #',MODE-enable-in-buffer)
-          (remove-hook 'find-file-hook #',MODE-check-buffers)
-          (remove-hook 'change-major-mode-hook #',MODE-cmhh))
+            (add-hook 'after-change-major-mode-hook
+                      #',MODE-enable-in-buffer)
+          (remove-hook 'after-change-major-mode-hook #',MODE-enable-in-buffer))
 
         ;; Go through existing buffers.
         (dolist (buf (buffer-list))
@@ -623,47 +613,7 @@ define-globalized-minor-mode
                    (funcall ,turn-on-function))
                (funcall ,turn-on-function))))
          (setq ,MODE-major-mode major-mode))
-       (put ',MODE-enable-in-buffer 'definition-name ',global-mode)
-
-       ;; In the normal case, major modes run `after-change-major-mode-hook'
-       ;; which will have called `MODE-enable-in-buffer' for us.  But some
-       ;; major modes don't use `run-mode-hooks' (customarily used via
-       ;; `define-derived-mode') and thus fail to run
-       ;; `after-change-major-mode-hook'.
-       ;; The functions below try to handle those major modes, with
-       ;; a combination of ugly hacks to try and catch those corner
-       ;; cases by listening to `change-major-mode-hook' to discover
-       ;; potential candidates and then checking in `post-command-hook'
-       ;; and `find-file-hook' if some of those still haven't run
-       ;; `after-change-major-mode-hook'.  FIXME: We should try and get
-       ;; rid of this ugly hack and rely purely on
-       ;; `after-change-major-mode-hook' because they can (and do) end
-       ;; up running `MODE-enable-in-buffer' too early (when the major
-       ;; isn't yet fully setup) in some cases (see bug#58888).
-
-       ;; The function that calls TURN-ON in each buffer.
-       (defun ,MODE-enable-in-buffers ()
-         (let ((buffers ,MODE-buffers))
-           ;; Clear MODE-buffers to avoid scanning the same list of
-           ;; buffers in recursive calls to MODE-enable-in-buffers.
-           ;; Otherwise it could lead to infinite recursion.
-           (setq ,MODE-buffers nil)
-           (dolist (buf buffers)
-             (when (buffer-live-p buf)
-              (with-current-buffer buf
-                (,MODE-enable-in-buffer))))))
-       (put ',MODE-enable-in-buffers 'definition-name ',global-mode)
-
-       (defun ,MODE-check-buffers ()
-        (,MODE-enable-in-buffers)
-        (remove-hook 'post-command-hook #',MODE-check-buffers))
-       (put ',MODE-check-buffers 'definition-name ',global-mode)
-
-       ;; The function that catches kill-all-local-variables.
-       (defun ,MODE-cmhh ()
-        (add-to-list ',MODE-buffers (current-buffer))
-        (add-hook 'post-command-hook #',MODE-check-buffers))
-       (put ',MODE-cmhh 'definition-name ',global-mode))))
+       (put ',MODE-enable-in-buffer 'definition-name ',global-mode))))
 
 (defun easy-mmode--globalized-predicate-p (predicate)
   (cond
-- 
2.43.0