Factor out undo-ignore-read-only (bug#80049)

* lisp/vc/diff-mode.el (diff-undo): Rename to
undo-ignore-read-only.
(diff-mode-shared-map): Update "<remap> <undo>" binding.
* lisp/simple.el (undo-ignore-read-only): Rename from diff-undo.
* lisp/dired.el (dired-undo):
* lisp/proced.el (proced-undo): Call it.  New numeric prefix
argument to specify a repeat count.
* doc/emacs/dired.texi (Marks vs Flags):
* etc/NEWS: Document the change.

doc/emacs/dired.texi

@@ -733,7 +733,8 @@ Auto-Revert mode, you might want to set
 Undo changes in the Dired buffer, such as adding or removing
 marks (@code{dired-undo}).  @emph{This command does not revert the
 actual file operations, nor recover lost files!}  It just undoes
-changes in the buffer itself.
+changes in the buffer itself.  Like with @code{undo}, a numeric prefix
+argument specifies a repeat count.
 
 In some cases, using this after commands that operate on files can
 cause trouble.  For example, after renaming one or more files,

etc/NEWS

@@ -888,6 +888,14 @@ failed.
 You can now use 'C-u C-x .' to clear the fill prefix, similarly to how
 you could already use 'C-u C-x C-n' to clear the goal column.
 
++++
+** New prefix argument for 'C-/' in Dired and Proced modes.
+The Dired and Proced major modes bind mode-specific undo commands to the
+same keys to which 'undo' is globally bound, 'C-/', 'C-_' and 'C-x u'.
+These commands did not previously accept a prefix argument.
+Now a numeric prefix argument specifies a repeat count, just like it
+already did for 'undo'.
+
 
 * Changes in Specialized Modes and Packages in Emacs 31.1
 

lisp/dired.el

@@ -2893,13 +2893,13 @@ Keybindings:
     (concat "\\`d'-elete, \\`u'-ndelete, \\`x'-punge, \\`f'-ind, "
             "\\`o'-ther window, \\`R'-ename, \\`C'-opy, \\`h'-elp"))))
 
-(defun dired-undo ()
+(defun dired-undo (&optional arg)
   "Undo in a Dired buffer.
+A numeric ARG serves as a repeat count.
 This doesn't recover lost files, it just undoes changes in the buffer itself.
 You can use it to recover marks, killed lines or subdirs."
-  (interactive nil dired-mode)
-  (let ((inhibit-read-only t))
-    (undo))
+  (interactive "P" dired-mode)
+  (undo-ignore-read-only arg)
   (dired-build-subdir-alist)
   (message "Change in Dired buffer undone.
 Actual changes in files cannot be undone by Emacs."))

lisp/proced.el

@@ -2311,13 +2311,13 @@ STRING is an overall summary of the failures."
       (describe-mode)
     (message (substitute-command-keys proced-help-string))))
 
-(defun proced-undo ()
+(defun proced-undo (&optional arg)
   "Undo in a Proced buffer.
+A numeric ARG serves as a repeat count.
 This doesn't recover killed processes, it just undoes changes in the Proced
 buffer.  You can use it to recover marks."
-  (interactive nil proced-mode)
-  (let (buffer-read-only)
-    (undo))
+  (interactive "P" proced-mode)
+  (undo-ignore-read-only arg)
   (message "Change in Proced buffer undone.
 Killed processes cannot be recovered by Emacs."))
 

lisp/simple.el

@@ -3577,6 +3577,13 @@ as an argument limits undo to changes within the current region."
     (if message
 	(message "%s" message))))
 
+(defun undo-ignore-read-only (&optional arg)
+  "Perform `undo', ignoring the buffer's read-only status.
+A numeric ARG serves as a repeat count."
+  (interactive "P")
+  (let ((inhibit-read-only t))
+    (undo arg)))
+
 (defun buffer-disable-undo (&optional buffer)
   "Make BUFFER stop keeping undo information.
 No argument or nil as argument means do this for the current buffer."

lisp/vc/diff-mode.el

@@ -217,7 +217,7 @@ See also `diff-mode-read-only-map'."
   "RET" #'diff-goto-source
   "<mouse-2>" #'diff-goto-source
   "o" #'diff-goto-source                ; other-window
-  "<remap> <undo>" #'diff-undo
+  "<remap> <undo>" #'undo-ignore-read-only
 
   ;; The foregoing commands don't affect buffers beyond this one.
   ;; The following command is the only one that has a single-letter
@@ -2815,12 +2815,6 @@ Call FUN with two args (BEG and END) for each hunk."
 (defun diff--overlay-auto-delete (ol _after _beg _end &optional _len)
   (delete-overlay ol))
 
-(defun diff-undo (&optional arg)
-  "Perform `undo', ignoring the buffer's read-only status."
-  (interactive "P")
-  (let ((inhibit-read-only t))
-    (undo arg)))
-
 ;;;###autoload
 (defcustom diff-add-log-use-relative-names nil
   "Use relative file names when generating ChangeLog skeletons.