bug#14541: 24.3.50; `ediff-buffers' does not play well with recent Cygwin version

[Achim Gratz <Stromeko@nexgo.de>]

Drew Adams writes:
>> It is not your business (or anyone else's but the user) to set that
>> environment variable.  
>
> I am the user.  Just trying to make the recent Cygwin versionn work with
> Emacs, like an older version did.

You are putting this file on EmacsWiki for others to use, aren't you?
Secondly, that warning is there for a reason, so simply switching it off
certainly isn't going to do the right thing for everyone.

>> Don't.  You might override other settings that the user wants to take
>> effect or at best produce a confusing no-op.  You'd be much better off
>> if you would use cygpath to convert to POSIX instead.
>
> I'll leave it in setup-cygwin.el, at least for now.  But I'll add a
> comment per what Eli said: that if come other Cygwin process started
> earlier and turned this off then turning it on here has no effect.

Again: it simply doesn't work the way you think it works.  The comment
isn't helping that issue in any way.  It is wrong to do this in
setup-cygwin.el even when you want this environment variable to have
exactly that value.  It must already be set before Emacs gets started.

> Sounds like the only good approach for an Emacs user on Windows, with
> Cygwin installed, is to set the env var at the system level.  If that
> is the case (please confirm) then I'll mention that too in a
> setup-cygwin.el comment.  (And we might want to mention that in the
> Emacs manual?)

The only way to have it working reliably is to set it from the system
panel, then log off and on again.

I'm not sure what you want Emacs to document: the problem is that you
are using non-Windows tools together with a Windows Emacs and you aren't
correctly converting the different path conventions by these tools and
Emacs.  That is not a Cygwin problem and not an Emacs problem.

> OK, I suppose that's not the only good approach.  I guess you're
> suggesting another, for someone who is willing to change to POSIX:
> use the cygpath utility.  Feel free to document that one (for Emacs
> users)...

Actually, emacs-w32 from Cygwin is much better in almost all regards and
doesn't have the problem to begin with because it never uses any Windows
path names.


Regards,
Achim.
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