* simple.el (transpose-subr): Give clearer error when the mark is not set.

  (Bug#4807)

2 files changed, 6 insertions, 1 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 1442396b746..1ba5a0275ee 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,8 @@
+2009-10-26  Juanma Barranquero  <lekktu@gmail.com>
+
+        * simple.el (transpose-subr): Give clearer error when the mark
+        is not set.  (Bug#4807)
+
 2009-10-26  Michael Albinus  <michael.albinus@gmx.de>
 
         * net/tramp.el (tramp-perl-file-truename): New defconst.  Perl
diff --git a/lisp/simple.el b/lisp/simple.el
index 14dc128a790..117a93bcc0f 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -4852,7 +4852,7 @@ With argument 0, interchanges line point is in with line mark is in."
      ((= arg 0)
       (save-excursion
         (setq pos1 (funcall aux 1))
-        (goto-char (mark))
+        (goto-char (or (mark) (error "No mark set in this buffer")))
         (setq pos2 (funcall aux 1))
         (transpose-subr-1 pos1 pos2))
       (exchange-point-and-mark))