bug#9655: 24.0.50; `set-locale-environment' should use completion

[Eli Zaretskii]

> Date: Mon, 03 Oct 2011 03:14:46 -0400
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: 9655@debbugs.gnu.org
> Reply-To: Eli Zaretskii <eliz@gnu.org>
> 
> > From: "Drew Adams" <drew.adams@oracle.com>
> > Date: Sun, 2 Oct 2011 12:45:03 -0700
> > 
> > It also says: "The locale names supported by your system can typically
> > be found in a directory named `/usr/share/locale' or `/usr/lib/locale'."
> > This does not help users who are not on a UNIX/Gnu/Linux platform.
> > Where can they be found on Windows, for instance?
> 
> Nowhere a mere mortal can see it.  The OS maintains the list of
> supported locales, and will divulge it via a certain C-level API.  But
> you cannot find that list by searching files or directories, AFAIK.
> As an interactive user, you can see the list in the Control Panel, but
> programmatically the list is available only through that API.

Forgot to mention that this API has a Lisp binding in Emacs:
w32-get-valid-locale-ids.  E.g., try

  (mapcar 'w32-get-locale-info (w32-get-valid-locale-ids))