bug#25183: 26.0.50; expanding quoted file name on w32

[npostavs]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Noam Postavsky <npostavs@users.sourceforge.net>
>> Date: Sat, 24 Dec 2016 12:43:24 -0500
>> Cc: Michael Albinus <michael.albinus@gmx.de>, 25183@debbugs.gnu.org
>> 
>> >>     (expand-file-name "/:~/path/./file") => (error "/: quoting relative 
>> >> file name")
>> >
>> > expand-file-name doesn't signal errors, and I don't think it would be
>> > a good idea to have it start doing that.
>> 
>> I think the status quo (leaving it inconsistent) is okay too (garbage
>> in, garbage out).
>
> But expansion of "~" in the Windows build should be bypassed in this
> case, don't you agree?

In the case of "/:~/whatever" I think any output is fine, since the
input is meaningless.  Avoiding ~-expansion is okay, though I don't
think it's actually a problem either way.

For reference, on a GNU system, doing

$ echo xx > '~'
$ emacs -Q '/:~'

opens up the $HOME directory, even though the "~" is not expanded by
`expand-file-name'.