GNU bug report logs - #4823
w32 paths `substitute-in-file-name' fails when environmental variable is set for \\ style paths:

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Message #5 received at submit <at> emacsbugs.donarmstrong.com (full text, mbox):

From: MON KEY <monkey <at> sandpframing.com>
To: bug-gnu-emacs <at> gnu.org
Subject: w32 paths `substitute-in-file-name' fails when environmental variable 
	is set for \\ style paths:
Date: Wed, 28 Oct 2009 16:19:44 -0400

w32 paths `substitute-in-file-name' fails when environmental variable
is set for \\ style paths:

;; :SITUATION-1 w/out trailing `\\'
(setenv "HOME2" "C:\\home\\me")
(getenv "HOME2")
;=> "C:\\home\\me"
(substitute-in-file-name "$HOME2\\.emacs")
;=> "C:\\home\\me/emacs"
(substitute-in-file-name "$HOME2/.emacs")
;=>"C:\\home\\me/.emacs"
(substitute-in-file-name "$HOME2.emacs")
;=> "C:\\home\\me.emacs"

;; :SITUATION-2 with trailing `\\'
(setenv "HOME2" "C:\\home\\me\\")
(getenv "HOME2")
;=> "C:\\home\\me\\"
(substitute-in-file-name "$HOME2\\.emacs")
;=> "/.emacs"
(substitute-in-file-name "$HOME2\.emacs")
;=> "C:\\home\\me\\.emacs"
(substitute-in-file-name "$HOME2//.emacs")
;=> "/.emacs"
(substitute-in-file-name "$HOME2.emacs")
;=> "C:\\home\\me\\.emacs"

;; ON FOLLOWING SYSTEM:
GNU Emacs 23.1.50.1 (i386-mingw-nt5.1.2600)
 of 2009-06-30 on LENNART-69DE564 (patched)

Message #10 received at 4823 <at> emacsbugs.donarmstrong.com (full text, mbox):

From: Juanma Barranquero <lekktu <at> gmail.com>
To: MON KEY <monkey <at> sandpframing.com>
Cc: 4823 <at> debbugs.gnu.org
Subject: Re: bug#4823: w32 paths `substitute-in-file-name' fails when 
	environmental variable is set for \\ style paths:
Date: Wed, 28 Oct 2009 22:38:34 +0100

On Wed, Oct 28, 2009 at 21:19, MON KEY <monkey <at> sandpframing.com> wrote:

> ;; :SITUATION-1 w/out trailing `\\'

> (substitute-in-file-name "$HOME2\\.emacs")
> ;=> "C:\\home\\me/emacs"

I get "C:\\home\\me/.emacs", which seems correct.

> (substitute-in-file-name "$HOME2/.emacs")
> ;=>"C:\\home\\me/.emacs"
> (substitute-in-file-name "$HOME2.emacs")
> ;=> "C:\\home\\me.emacs"

These seem correct to me.

> ;; :SITUATION-2 with trailing `\\'

> (substitute-in-file-name "$HOME2\\.emacs")
> ;=> "/.emacs"

$HOME2\\.emacs ==> "C:\\home\\me\\\\.emacs" ==> C:\home\me\\.emacs

According to the docstring of `substitute-in-file-name':

  If `//' appears, everything up to and including the first of
  those `/' is discarded.

and \\ (quoted to \\\\) is equivalent to // in w32 filenames (at least
for Emacs).

> (substitute-in-file-name "$HOME2\.emacs")
> ;=> "C:\\home\\me\\.emacs"

$HOME2\.emacs ==> "C:\\home\\me\\\.emacs" ==> C:\home\me\.emacs

so this is correct (remember that "\." == ".").

> (substitute-in-file-name "$HOME2//.emacs")
> ;=> "/.emacs"

This is similar to the \\\\ case above:

$HOME2//.emacs ==> "C:\\home\\me\\//.emacs" ==> C:\home\me\//.emacs

which could arguably be //.emacs, but that does not seem very useful.

> (substitute-in-file-name "$HOME2.emacs")
> ;=> "C:\\home\\me\\.emacs"

That seems correct.

What where you expecting in each case?

    Juanma

Message #15 received at 4823 <at> emacsbugs.donarmstrong.com (full text, mbox):

From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: Juanma Barranquero <lekktu <at> gmail.com>
Cc: 4823 <at> debbugs.gnu.org, MON KEY <monkey <at> sandpframing.com>
Subject: Re: bug#4823: w32 paths `substitute-in-file-name' fails when environmental variable is set for \\ style paths:
Date: Wed, 28 Oct 2009 20:43:33 -0400

> According to the docstring of `substitute-in-file-name':

>   If `//' appears, everything up to and including the first of
>   those `/' is discarded.

Admittedly, I think substitute-in-file-name implements this feature
incorrectly, because the double-slash handling should be done before
envvar expansion (envvars ceom from outside Emacs usually, so they
generally rely on the convention that /foo///bar is equivalent to
/foo/bar rather than to /bar).

OTOH if an envvar holds "http://foo/bar", then we'd want to use
url-handler-mode's implementation of substitute-in-file-name, which
would argue for doing expansion early.  It's probably tricky to get it
to do the right thing in "all" cases.


        Stefan

Message #18 received at 4823 <at> debbugs.gnu.org (full text, mbox):

From: Juanma Barranquero <lekktu <at> gmail.com>
To: Stefan Monnier <monnier <at> iro.umontreal.ca>
Cc: 4823 <at> debbugs.gnu.org, MON KEY <monkey <at> sandpframing.com>
Subject: Re: bug#4823: w32 paths `substitute-in-file-name' fails when
	environmental variable is set for \\ style paths:
Date: Sat, 2 Jul 2011 03:39:54 +0200

I'm closing this one because the original reported behavior is not a
bug, and there's nothing else to do.

    Juanma

Message #23 received at 4823-done <at> debbugs.gnu.org (full text, mbox):

From: Juanma Barranquero <lekktu <at> gmail.com>
To: 4823-done <at> debbugs.gnu.org
Subject: Re: bug#4823: w32 paths `substitute-in-file-name' fails when
	environmental variable is set for \\ style paths:
Date: Sat, 2 Jul 2011 03:47:18 +0200

> I'm closing this one

No, *now* I'm closing it...

    Juanma

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