Subject: bug#1448: 23.0.60; update to cvs emacs crash report

From: "Juanma Barranquero" <[email-masked]>
Date: Fri, 28 Nov 2008 10:25:09 +0100

merge 872 1446 1447 1448
quit

On Fri, Nov 28, 2008 at 06:15, Feng li <[email-masked]> wrote:

> Start emacs with "-q". Press "C-h b" to bring up the keybinding
> help. Switch to the keybinding help window and press "PgDn" a few times
> will cause emacs to crash.
>
> I have rebuilt a new emacs binary with debug info and attached the back
> trace of the crash location at below.

What you're seeing is bug#872 (also #1179).

I originally thought it depended on
`display-unibyte-via-language-environment', but it is not so; I've
seen it (and suffered it) through several different incarnations.

What they all have in common:

 - Using a "recent" MinGW GCC (4.2.1, 4.3.0-alpha, etc.)
 - Compiling with optimization
 - Trying to display unibyte (or, perhaps, some composed characters,
I'm not sure)
 - It *always* happens when draw_glyphs is running
 - It mostly happens in fill_glyph_string

I can reproduce it at will in a lot of ways, for example:

  M-x ucs-insert AEGEAN CHECK MARK <RET>

or

  (let ((my-map (make-keymap)))
    (suppress-keymap my-map)
    (substitute-command-keys "\\{my-map}"))

or having `display-unibyte-via-language-environment' set to t and
`debug' being called for whatever reason, etc. etc.

I've been trying to debug it, without success (it doesn't help that I
know very little about the glyph handling code). I'm not even sure
whether it is a compiler bug, or a bug in Emacs (it happens in code
that was undergoing changes quite recently).

  Juanma