unload-feature: Handle local hooks (bug#5293)

Buffer-local hooks were introduced in

1994-09-30T20:47:13+00:00!rms@gnu.org
0e4d378b32 (add-hook): Initialize default value and local value.

but 'unload-feature' has not been updated to handle them.

* lisp/loadhist.el (unload-feature): Handle local hooks (bug#5293).

etc/NEWS

@@ -1748,6 +1748,9 @@ to lexical binding, where dynamic (special) variables bound in one
 file can affect code in another.  For details, see the manual section
 '(Elisp) Converting to Lexical Binding'.
 
+---
+** 'unload-feature' now also tries to undo additions to buffer-local hooks.
+
 
 * Changes in Emacs 28.1 on Non-Free Operating Systems
 

lisp/loadhist.el

@@ -300,6 +300,15 @@ something strange, such as redefining an Emacs function."
 			    (memq x unload-feature-special-hooks)))
 	       (dolist (func removables)
 	         (remove-hook x func)))))
+          (save-current-buffer
+            (dolist (buffer (buffer-list))
+              (pcase-dolist (`(,sym . ,val) (buffer-local-variables buffer))
+                (when (or (and (consp val)
+                               (string-match "-hooks?\\'" (symbol-name sym)))
+                          (memq sym unload-feature-special-hooks))
+                  (set-buffer buffer)
+                  (dolist (func removables)
+                    (remove-hook sym func t))))))
           ;; Remove any feature-symbols from auto-mode-alist as well.
           (dolist (func removables)
             (setq auto-mode-alist