(Fprimitive_undo): Check that undo function does not switch buffer.

1 files changed, 5 insertions, 0 deletions

diff --git a/src/undo.c b/src/undo.c
index 86237e2c59a..b4e16bfd0e5 100644
--- a/src/undo.c
+++ b/src/undo.c
@@ -557,6 +557,8 @@ Return what remains of the list.  */)
               else if (EQ (car, Qapply))
                 {
                   /* Element (apply FUN . ARGS) means call FUN to undo.  */
+                  struct buffer *save_buffer = current_buffer;
+
                   car = Fcar (cdr);
                   cdr = Fcdr (cdr);
                   if (INTEGERP (car))
@@ -582,6 +584,9 @@ Return what remains of the list.  */)
                     }
                   else
                     apply1 (car, cdr);
+
+                  if (save_buffer != current_buffer)
+                    error ("Undo function switched buffer");
                   did_apply = 1;
                 }
               else if (STRINGP (car) && INTEGERP (cdr))