(undo): Use undo-equiv-table to detect

unexpected changes since previous undo.
(undo-list-saved): Variable deleted.
(buffer-disable-undo): Don't alter undo-list-saved.

diff --git a/lisp/simple.el b/lisp/simple.el
index f5bc8a40fa67b2792b2bdde3a8babe36b85d7b0d..735c65948bfd8211829f1bb471a61922d1f02eb8 100644 (file)
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -1234,10 +1234,6 @@ Return 0 if current buffer is not a mini-buffer."
 (defvar undo-no-redo nil
   "If t, `undo' doesn't go through redo entries.")
 
-(defvar undo-list-saved nil
-  "The value of `buffer-undo-list' saved by the last undo command.")
-(make-variable-buffer-local 'undo-list-saved)
-
 (defun undo (&optional arg)
   "Undo some previous changes.
 Repeat this command to undo more changes.
@@ -1266,7 +1262,9 @@ as an argument limits undo to changes within the current region."
                 (let ((list buffer-undo-list))
                   (while (eq (car list) nil)
                     (setq list (cdr list)))
-                  (eq undo-list-saved list)))
+                  ;; If the last undo record made was made by undo
+                  ;; it shows nothing else happened in between.
+                  (gethash list undo-equiv-table)))
       (setq undo-in-region
            (if transient-mark-mode mark-active (and arg (not (numberp arg)))))
       (if undo-in-region
@@ -1320,7 +1318,6 @@ as an argument limits undo to changes within the current region."
        (setq prev tail tail (cdr tail))))
     ;; Record what the current undo list says,
     ;; so the next command can tell if the buffer was modified in between.
-    (setq undo-list-saved buffer-undo-list)
     (and modified (not (buffer-modified-p))
         (delete-auto-save-file-if-necessary recent-save))))
 
@@ -1329,8 +1326,7 @@ as an argument limits undo to changes within the current region."
 No argument or nil as argument means do this for the current buffer."
   (interactive)
   (with-current-buffer (if buffer (get-buffer buffer) (current-buffer))
-    (setq buffer-undo-list t
-         undo-list-saved nil)))
+    (setq buffer-undo-list t)))
 
 (defun undo-only (&optional arg)
   "Undo some previous changes.