bug#67540: 29.1; Emacs on Windows incorrectly capitalizes some environment variables

bug#67540: 29.1; Emacs on Windows incorrectly capitalizes some environment variables

[Dave Abrahams]

emacs -Q
M-! set

Now issue the "set" command from a CMD shell. Notice that the "Path"
environment variable has been renamed to "PATH" in Emacs.  This renaming
interferes with some tools operating correctly e.g. the swift compiler
(see https://swift.org).

I notice that the "ComSpec" variable is getting the same treatment

I am able to work around the problem as follows:

(defun unsetenv (var-name)
  (let ((current-prefix-arg '(4)))
	(funcall-interactively 'setenv var-name nil)))

(when (eq system-type 'windows-nt)
  (dolist (v '("Path" "ComSpec"))
          (let ((x (getenv v)))
               (unsetenv (upcase v))
               (setenv v x))))


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bug#67540: 29.1; Emacs on Windows incorrectly capitalizes some environment variables

[Jim Porter]

On 11/29/2023 6:29 PM, Dave Abrahams wrote:
> Now issue the "set" command from a CMD shell. Notice that the "Path"
> environment variable has been renamed to "PATH" in Emacs.  This renaming
> interferes with some tools operating correctly e.g. the swift compiler
> (see https://swift.org).

This sounds like there's a bug in the Swift compiler. Environment 
variables on MS-Windows are case-insensitive: 
<https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/getenv-wgetenv?view=msvc-170>. 
That documentation just covers 'getenv' (and 'wgetenv'), but I'm 
reasonably certain the same applies to the Win32 APIs as well.

It might be nice for Emacs to preserve the case of any existing 
environment variables on MS-Windows to be on the safe side though...

bug#67540: 29.1; Emacs on Windows incorrectly capitalizes some environment variables

[Eli Zaretskii]

> Date: Wed, 29 Nov 2023 19:42:46 -0800
> From: Jim Porter <jporterbugs@gmail.com>
> 
> On 11/29/2023 6:29 PM, Dave Abrahams wrote:
> > Now issue the "set" command from a CMD shell. Notice that the "Path"
> > environment variable has been renamed to "PATH" in Emacs.  This renaming
> > interferes with some tools operating correctly e.g. the swift compiler
> > (see https://swift.org).
> 
> This sounds like there's a bug in the Swift compiler. Environment 
> variables on MS-Windows are case-insensitive: 
> <https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/getenv-wgetenv?view=msvc-170>. 
> That documentation just covers 'getenv' (and 'wgetenv'), but I'm 
> reasonably certain the same applies to the Win32 APIs as well.

Right.

> It might be nice for Emacs to preserve the case of any existing 
> environment variables on MS-Windows to be on the safe side though...

That's impossible in practice: we'd need to "fix" every single Lisp
program and every place in the Emacs C code that compare against
"PATH" case-sensitively.  And what about user confusion, for those of
us who mostly work on Unix, but sometimes need to work on Windows?

We decided long ago to make these letter-case changes in the Windows
build of Emacs, and the decision held well since then.  I see no
reason to change that decision now, just because some program
misbehaves on Windows.

bug#67540: 29.1; Emacs on Windows incorrectly capitalizes some environment variables

[Dave Abrahams]

[-- Attachment #1: Type: text/plain, Size: 2006 bytes --]



> On Nov 29, 2023, at 11:22 PM, Eli Zaretskii <eliz@gnu.org> wrote:
> 
>> Date: Wed, 29 Nov 2023 19:42:46 -0800
>> From: Jim Porter <jporterbugs@gmail.com>
>> 
>> On 11/29/2023 6:29 PM, Dave Abrahams wrote:
>>> Now issue the "set" command from a CMD shell. Notice that the "Path"
>>> environment variable has been renamed to "PATH" in Emacs.  This renaming
>>> interferes with some tools operating correctly e.g. the swift compiler
>>> (see https://swift.org).
>> 
>> This sounds like there's a bug in the Swift compiler. Environment 
>> variables on MS-Windows are case-insensitive: 
>> <https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/getenv-wgetenv?view=msvc-170>. 
>> That documentation just covers 'getenv' (and 'wgetenv'), but I'm 
>> reasonably certain the same applies to the Win32 APIs as well.
> 
> Right.
> 
>> It might be nice for Emacs to preserve the case of any existing 
>> environment variables on MS-Windows to be on the safe side though...
> 
> That's impossible in practice: we'd need to "fix" every single Lisp
> program and every place in the Emacs C code that compare against
> "PATH" case-sensitively.  And what about user confusion, for those of
> us who mostly work on Unix, but sometimes need to work on Windows?

I don't think this is that hard to fix without breaking anybody.  Simply maintain a mapping of in-Emacs upcased environment variable names to the lowercased counterparts from which they came, and map back when setting up a process environment.

> We decided long ago to make these letter-case changes in the Windows
> build of Emacs, and the decision held well since then.  I see no
> reason to change that decision now, just because some program
> misbehaves on Windows.

“My” Windows expert told me that “Path is the correct spelling,” or I wouldn't have reported this as a bug.  Still, I think you could make the workaround described above, if you wanted to accomodate my "misbehaving" tools.


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bug#67540: 29.1; Emacs on Windows incorrectly capitalizes some environment variables

[Eli Zaretskii]

> From: Dave Abrahams <dave@boostpro.com>
> Date: Thu, 30 Nov 2023 16:13:03 -0800
> Cc: Jim Porter <jporterbugs@gmail.com>,
>  67540@debbugs.gnu.org
> 
>  It might be nice for Emacs to preserve the case of any existing 
>  environment variables on MS-Windows to be on the safe side though...
> 
>  That's impossible in practice: we'd need to "fix" every single Lisp
>  program and every place in the Emacs C code that compare against
>  "PATH" case-sensitively.  And what about user confusion, for those of
>  us who mostly work on Unix, but sometimes need to work on Windows?
> 
> I don't think this is that hard to fix without breaking anybody.  Simply maintain a mapping of in-Emacs
> upcased environment variable names to the lowercased counterparts from which they came, and
> map back when setting up a process environment.

This will not work reliably, because many programs invoked by Emacs as
sub-processes are ported Unix and GNU/Linux programs, and those expect
PATH, not Path in the environment.

bug#67540: 29.1; Emacs on Windows incorrectly capitalizes some environment variables

[Dave Abrahams]

You’re saying that these are ported UNIX programs that are only designed to work from inside of Emma, which has changed the spelling of the environment variable names?

Sent from my iPhone

> On Nov 30, 2023, at 11:14 PM, Eli Zaretskii <eliz@gnu.org> wrote:
> 
> 
>> 
>> From: Dave Abrahams <dave@boostpro.com>
>> Date: Thu, 30 Nov 2023 16:13:03 -0800
>> Cc: Jim Porter <jporterbugs@gmail.com>,
>> 67540@debbugs.gnu.org
>> 
>> It might be nice for Emacs to preserve the case of any existing
>> environment variables on MS-Windows to be on the safe side though...
>> 
>> That's impossible in practice: we'd need to "fix" every single Lisp
>> program and every place in the Emacs C code that compare against
>> "PATH" case-sensitively.  And what about user confusion, for those of
>> us who mostly work on Unix, but sometimes need to work on Windows?
>> 
>> I don't think this is that hard to fix without breaking anybody.  Simply maintain a mapping of in-Emacs
>> upcased environment variable names to the lowercased counterparts from which they came, and
>> map back when setting up a process environment.
> 
> This will not work reliably, because many programs invoked by Emacs as
> sub-processes are ported Unix and GNU/Linux programs, and those expect
> PATH, not Path in the environment.

bug#67540: 29.1; Emacs on Windows incorrectly capitalizes some environment variables

[Eli Zaretskii]

> From: Dave Abrahams <dave@boostpro.com>
> Date: Fri, 1 Dec 2023 12:34:40 -0800
> Cc: jporterbugs@gmail.com, 67540@debbugs.gnu.org
> 
> You’re saying that these are ported UNIX programs that are only designed to work from inside of Emma, which has changed the spelling of the environment variable names?

No, they are not for Emacs only.  But they expect to see PATH, and
they compare case-sensitively with "PATH".  If you want to cater to
swift, which doesn't recognize "PATH", but does recognize "Path", why
not assume that there are other programs which do the opposite, and
which will be broken by the change you propose?

IOW, I don't see why we should change code that worked for decades
because a single application implements a case-sensitive search of
environment variables on MS-Windows, in direct contradiction of
platform conventions, and contrary to the behavior of every other
program I've ever used on Windows?

bug#67540: 29.1; Emacs on Windows incorrectly capitalizes some environment variables

[Dave Abrahams]

> On Dec 1, 2023, at 11:04 PM, Eli Zaretskii <eliz@gnu.org> wrote:
> 
>> From: Dave Abrahams <dave@boostpro.com>
>> Date: Fri, 1 Dec 2023 12:34:40 -0800
>> Cc: jporterbugs@gmail.com, 67540@debbugs.gnu.org
>> 
>> You’re saying that these are ported UNIX programs that are only designed to work from inside of Emma, which has changed the spelling of the environment variable names?
> 
> No, they are not for Emacs only.  But they expect to see PATH, and
> they compare case-sensitively with "PATH".  If you want to cater to
> swift, which doesn't recognize "PATH", but does recognize "Path", why
> not assume that there are other programs which do the opposite, and
> which will be broken by the change you propose?

I'm only not making that assumption because I haven't been able to find a single example, and because it's harder for me to imagine someone porting a program from one OS to another and only testing their port in a non-standard environment, whereas I've seen thousands of examples of code that (erroneously) only works when things are set up in the most usual way.

> IOW, I don't see why we should change code that worked for decades
> because a single application implements a case-sensitive search of
> environment variables on MS-Windows, in direct contradiction of
> platform conventions, and contrary to the behavior of every other
> program I've ever used on Windows?

I'm not saying you should, only that you could.  

You seem to be contradicting yourself.  Either every other program on Windows does case-insensitive environment searches and nobody would be broken by my suggestion, or there are some that, in direct contradiction of platform conventions, only look for PATH and would be broken if they saw Path.

Why would you want to do something like this?  Just that it's (IMO) far more likely you'll find software that only works properly on a given platform when things are set up in the standard way than it is that you'll find software that only works properly in a technically conforming but non-standard setup.  The choice is yours, obviously, but it seems to me one arrangement is much less likely to stimulate bugs than the other one.

bug#67540: 29.1; Emacs on Windows incorrectly capitalizes some environment variables

[Eli Zaretskii]

tags 67540 wontfix
thanks

> From: Dave Abrahams <dave@boostpro.com>
> Date: Wed, 29 Nov 2023 18:29:26 -0800
> 
> 
> 
> emacs -Q
> M-! set
> 
> Now issue the "set" command from a CMD shell. Notice that the "Path"
> environment variable has been renamed to "PATH" in Emacs.  This renaming
> interferes with some tools operating correctly e.g. the swift compiler
> (see https://swift.org).

You are saying that the swift compiler doesn't recognize "PATH"?  If
so, it's a bug in the swift compiler, since look up of environment
variables by cmd.exe at least is case-insensitive on Windows, and I
have yet to see a Windows program which doesn't do the same.  I
suggest reporting a bug against swift.

We cannot avoid up-casing Path and ComSpec in Emacs because that would
break many places in Emacs that assume they are spelled in CAPS.
(Obviously, PATH is much more critical than COMSPEC, but still.)  And
Emacs Lisp programs don't compare these variables case-insensitively.

So if swift and some other programs must have Path and not PATH, my
suggestion is to perform the letter-case changes when you invoke those
programs, and them alone, as doing that globally in Emacs will cause
problems elsewhere.