crash under X using compose-region with null string

[Johan Bockgård]

$ emacs -Q

Insert

    (compose-region 1 2 "")

in the *scratch* buffer and evaluate it.

Emacs crashes during redisplay:

Program received signal SIGSEGV, Segmentation fault.
set_glyph_string_background_width (s=0x0, start=1, last_x=892) at xdisp.c:19150
19150     if (start == s->row->used[s->area]
(gdb) 


In GNU Emacs 22.0.50.33 (x86_64-unknown-linux-gnu, X toolkit)
 of 2006-05-01 on muon
X server distributor `The X.Org Foundation', version 11.0.70000000
Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8
  default-enable-multibyte-characters: t