bug#22169: 25.0.50; File name compiletion doesn't work with non-ASCII characters on OS X

[Eli Zaretskii]

> Date: Mon, 14 Dec 2015 20:08:27 +0100
> From: Anders Lindgren <andlind@gmail.com>
> 
> In an empty directory:
> echo "alpha" > åäöalpha.txt
> echo "beta" > åäöbeta.txt
> Emacs -Q
> C-x C-f
> TAB # Emacs correctly echoes "åäö"
> TAB # Emacs incorrectly says "[No match]"
> 
> C-g # To get out of the previous C-x C-f
> C-x C-f
> å TAB # Emacs incorrectly says "[No match]"
> 
> The OS X file system is a bit bizarre in that it stores filenames using the
> decomposed UTF-8 format (for characters in specific ranges), this might have
> something to do with this.

This shouldn't cause any trouble, since Emacs encodes file names
before passing them to readdir, and decodes the results.  The encoding
and decoding process should take care of the decomposition and
composition.

What is the value of file-name-coding-system on that system?