Re: 23.0.60; Segmentation fault loading auto-lang.el

[Chong Yidong]

> - download http://www.marquardt-home.de/auto-lang.el to ~/.elisp/
> - run emacs -Q
> - M-x load-file
> - choose file ~/.elisp/auto-lang.el
> => Emacs segfaults (same result with emacs -Q -nw)

This is due to an infinite nesting depth in regexp-opt, which can be
tracked down to the following problem:

(let ((str (string-as-unibyte "ä")))
  (string-match (char-to-string (string-to-char str)) str))

evaluates to 0 in Emacs 22, and to nil in Emacs 23.  It turns out that
this screws up the use of all-completions in regexp-opt-group.

Anyone have any idea what's going on here?