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

From: Jim Porter <[email-masked]>
Date: Wed, 29 Nov 2023 19:42:46 -0800

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...