bug#19910: 24.4; Japanese font names are decoded incorrectly in Cygwin's emacs-w32 in LANG=ja_JP.UTF-8

[Eli Zaretskii <eliz@gnu.org>]

> From: Stefan Kangas <stefan@marxist.se>
> Cc: Fujii Hironori <fujii.hironori@gmail.com>,  19910@debbugs.gnu.org
> Date: Sun, 01 Dec 2019 09:21:56 +0100
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> Date: Fri, 20 Feb 2015 19:39:55 +0900
> >> From: Fujii Hironori <fujii.hironori@gmail.com>
> >> 
> >> (font-family-list) returns incorrectly decoded Japanese font names.
> >> My locale-coding-system is utf-8-unix.
> >> 
> >> If I do (setq locale-coding-system 'cp932), it returns correct font names.
> >> But, locale-coding-system is used in other places (e.g. M-x term and M-x man).
> >> locale-coding-system must be utf-8 in my Emacs.
> >
> > The problem is in w32font.c: it should call the "wide" (a.k.a.
> > "Unicode") APIs, and then decode strings using utf-16le, like we do in
> > w32fns.c with encoding strings we pass to w32 GUI APIs.
> 
> That was 5 years ago.  Is any of this still an issue on recent
> versions of Emacs?

I don't think anything's changed in that department, so the problem
should still be there.

However, I have an idea of a much simpler fix for this, but I need a
volunteer who has this problem to test a patch I'd like to write to
fix this.  Anyone?