* lisp.h (XCONS, XSTRING, XSYMBOL, XFLOAT, XPROCESS, XWINDOW, XSUBR, XBUFFER):

Verify correct object type before returning pointer, using eassert.
* frame.h (XFRAME): Likewise.

* buffer.c (Frename_buffer, Fset_buffer_multibyte,
swap_out_buffer_local_variables, Fmove_overlay): Don't apply XSYMBOL, XBUFFER,
etc, to values that may be nil or of the wrong type.
* data.c (set_internal): Likewise.
* dispextern.h (WINDOW_WANTS_MODELINE_P, WINDOW_WANTS_HEADER_LINE_P): Likewise.
* fileio.c (auto_save_1): Likewise.
* insdel.c (check_markers): Likewise.
* marker.c (buf_charpos_to_bytepos, unchain_marker): Likewise.
* undo.c (record_insert): Likewise.
* vmsproc.c (child_sig): Likewise.
* window.c (unshow_buffer, window_loop): Likewise.
* xterm.c (x_erase_phys_cursor): Likewise.

1 files changed, 2 insertions, 1 deletions

diff --git a/src/undo.c b/src/undo.c
index 96e3eeb687c..a498f2aae72 100644
--- a/src/undo.c
+++ b/src/undo.c
@@ -54,7 +54,8 @@ record_insert (beg, length)
   if (NILP (pending_boundary))
     pending_boundary = Fcons (Qnil, Qnil);
 
-  if (current_buffer != XBUFFER (last_undo_buffer))
+  if (!BUFFERP (last_undo_buffer)
+      || current_buffer != XBUFFER (last_undo_buffer))
     Fundo_boundary ();
   XSETBUFFER (last_undo_buffer, current_buffer);