Re: expand-file-name, DOS/Windows, and directory separator

[Eli Zaretskii <eliz@gnu.org>]

> From: Eric Abrahamsen <eric@ericabrahamsen.net>
> Date: Tue, 15 Feb 2022 12:15:08 -0800
> 
> >> (file-name-split (expand-file-name <file> "/"))
> >
> > file-name-split is one of the functions that support both styles of
> > slashes, so you don't need to call expand-file-name at all.  (And "/"
> > is not really an absolute file name on Windows anyway).
> 
> The `expand-file-name' is in there to collapse multiple consecutive
> directory separators, which happens in the wild, as `file-name-split'
> doesn't do that by itself.

Then do call expand-file-name, but you don't need to assume anything
about slashes in the result.

> Just running this, where I've doubled the slashes so as not to raise
> an error:
> 
> (file-name-split "C:\\Users\\eric\\random")
> 
> Just returns the whole string.

I bet you did that on Unix?  Because here on MS-Windows it returns the
expected

   ("" "Users" "eric" "random")

> This code has to handle all the weirdness of different systems and
> filesystem layouts and search engines, so I'm being a little paranoid
> about it.

You don't need to be paranoid.  Emacs's file-name related primitives
are supposed to handle file names on all the supported systems;
anything else is a bug that should be fixed.