Thank you for the bug report, Thomas!

 Ar an seachtú lá déag de mí na Nollaig, scríobh Thomas Mittelstaedt: 

 > Just had a little crash
 > 
 > Fatal error: assertion failed, file eval.c, line 1489, Attempt to call 
 > Lisp code from within redisplay without being properly wrapped
 > 
 > Fatal error (6).
 >
 > [...]
 >
 > Lisp backtrace follows:
 > 
 >   # (unwind-protect ...)
 >   # (unwind-protect ...)
 >   # (unwind-protect ...)
 >   # (unwind-protect ...)
 >   # (unwind-protect ...)
 >   # (unwind-protect ...)
 >   # (unwind-protect ...)
 >   # bind (did)
 >   G19744(65717)

This a call to the lambda on line 548 of dialog.el. The lambda was on
delete-frame-hook, so error means the frame in question was deleted from
within redisplay.

 >   # (unwind-protect ...)
 >   # bind (inhibit-quit)
 >   # (unwind-protect ...)
 >   # (unwind-protect ...)
 >
 > [...]
 > 
 > (gdb) bt
 > #0  0xc01ffd40 in kill () from /usr/lib/libc.2
 > #1  0x000e69fc in fatal_error_signal (sig=6) at emacs.c:3800
 > #2  <signal handler called>
 > #3  0xc01e494c in fflush () from /usr/lib/libc.2
 > #4  0x002afa00 in do_symval_forwarding (valcontents=0, buffer=0x0,
 >     console=0x402aa924) at symbols.c:1083
 > #5  0x40cfe5d4 in ?? ()
 > #6  0x40cfe5d4 in ?? ()
 > Backtrace stopped: previous frame identical to this frame (corrupt stack?)

Shame there’s not a better C stack available--I can’t find a place where
this will happen from a few minutes’ looking. 

Anyway, given that we know it’s happened, and that the _trapping_problems
code should prevent it happening in the future, does anyone have any
objections to this? 

diff -r dfd878799ef0 src/frame.c
--- a/src/frame.c	Fri Dec 14 14:25:04 2007 +0100
+++ b/src/frame.c	Mon Dec 17 16:33:35 2007 +0100
@@ -1540,7 +1540,8 @@ delete_frame_internal (struct frame *f, 
      user code there could do any number of dangerous things, including
      signalling an error. */

-  va_run_hook_with_args (Qdelete_frame_hook, 1, frame);
+  va_run_hook_with_args_trapping_problems
+    (Qframe, Qdelete_frame_hook, 1, frame);

   if (!FRAME_LIVE_P (f)) /* Make sure the delete-frame-hook didn't */
     {		         /* go ahead and delete anything. */
@@ -1553,7 +1554,8 @@ delete_frame_internal (struct frame *f, 
      signal an error. */
   if (XINT (Flength (DEVICE_FRAME_LIST (d))) == 1)
     {
-      va_run_hook_with_args (Qdelete_device_hook, 1, device);
+      va_run_hook_with_args_trapping_problems
+	(Qdevice, Qdelete_device_hook, 1, device);
       if (!FRAME_LIVE_P (f)) /* Make sure the delete-device-hook didn't */
 	{		     /*	go ahead and delete anything. */
 	  UNGCPRO;
@@ -1562,7 +1564,8 @@ delete_frame_internal (struct frame *f, 

       if (XINT (Flength (CONSOLE_DEVICE_LIST (con))) == 1)
 	{
-	  va_run_hook_with_args (Qdelete_console_hook, 1, console);
+	  va_run_hook_with_args_trapping_problems
+	    (Qconsole, Qdelete_console_hook, 1, console);
 	  if (!FRAME_LIVE_P (f)) /* Make sure the delete-console-hook didn't */
 	    {			 /* go ahead and delete anything. */
 	      UNGCPRO;