(open-line): Shield undo from the hack to insert at pt-1.

1 files changed, 11 insertions, 1 deletions

diff --git a/lisp/simple.el b/lisp/simple.el
index d4eac802e33..243b1eeb211 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -28,7 +28,17 @@ With arg N, insert N newlines."
   (interactive "*p")
   (let* ((do-fill-prefix (and fill-prefix (bolp)))
          (flag (and (null do-fill-prefix) (bolp) (not (bobp)))))
-    (if flag (forward-char -1))
+    ;; If this is a simple case, and we are at the beginning of a line,
+    ;; actually insert the newline *before* the preceding newline
+    ;; instead of after.  That makes better display behavior.
+    (if flag
+        (progn
+          ;; If undo is enabled, don't let this hack be visible:
+          ;; record the real value of point as the place to move back to
+          ;; if we undo this insert.
+          (if (and buffer-undo-list (not (eq buffer-undo-list t)))
+              (setq buffer-undo-list (cons (point) buffer-undo-list)))
+          (forward-char -1)))
     (while (> arg 0)
       (save-excursion
         (insert ?\n))