(undo): Correctly distinguish between numeric and non-numeric prefix

args in non-transient-mark-mode, as per the doc string.  When in
transient-mark-mode, treat all prefix-args as numeric.

2 files changed, 18 insertions, 9 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index dd2c3907dc8..73dc391a5ca 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,5 +1,10 @@
 2000-10-26  Miles Bader  <miles@lsi.nec.co.jp>
 
+        * simple.el (undo): Correctly distinguish between numeric and
+        non-numeric prefix args in non-transient-mark-mode, as per the doc
+        string.  When in transient-mark-mode, treat all prefix-args as
+        numeric.
+
         * simple.el (previous-matching-history-element): Position point on
         match.  Handle N == 0 correctly.  Miscellaneous cleanup.
 
diff --git a/lisp/simple.el b/lisp/simple.el
index c95fd36c863..8bf1a78dabf 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -879,9 +879,9 @@ Return 0 if current buffer is not a mini-buffer."
 Repeat this command to undo more changes.
 A numeric argument serves as a repeat count.
 
-Just C-u as argument requests selective undo,
-limited to changes within the current region.
-Likewise in Transient Mark mode when the mark is active."
+In Transient Mark mode when the mark is active, only undo changes within
+the current region.  Similarly, when not in Transient Mark mode, just C-u
+as an argument limits undo to changes within the current region."
   (interactive "*P")
   ;; If we don't get all the way thru, make last-command indicate that
   ;; for the following command.
@@ -890,12 +890,16 @@ Likewise in Transient Mark mode when the mark is active."
         (recent-save (recent-auto-save-p)))
     (or (eq (selected-window) (minibuffer-window))
         (message "Undo!"))
-    (or (eq last-command 'undo)
-        (progn (if (or arg (and transient-mark-mode mark-active))
-                   (undo-start (region-beginning) (region-end))
-                 (undo-start))
-               (undo-more 1)))
-    (undo-more (if arg (prefix-numeric-value arg) 1))
+    (unless (eq last-command 'undo)
+      (if (if transient-mark-mode mark-active (and arg (not (numberp arg))))
+          (undo-start (region-beginning) (region-end))
+        (undo-start))
+      ;; get rid of initial undo boundary
+      (undo-more 1))
+    (undo-more
+     (if (or transient-mark-mode (numberp arg))
+         (prefix-numeric-value arg)
+       1))
     ;; Don't specify a position in the undo record for the undo command.
     ;; Instead, undoing this should move point to where the change is.
     (let ((tail buffer-undo-list)