bug#54766: [PATCH] 28.1.0; Native comp: Inherit working directory for sub processes (MS Windows)

[Eli Zaretskii]

> From: Robin Putters <robin.putters@keronic.com>
> Date: Thu, 7 Apr 2022 14:35:57 +0000
> 
> On MS Windows systems, where the Emacs executable is typically not in the 
> PATH, creating the async sub processes for the native compiler will fail 
> because they are started in a random working directory. The included patch 
> will inherit the working directory from the parent emacs process by setting 
> default-directory before creating the sub process.    

Please tell more about the failure and its reasons.  The compilation
command does this:

                   (process (make-process
                             :name (concat "Compiling: " source-file)
                             :buffer (with-current-buffer
                                         (get-buffer-create
                                          comp-async-buffer-name)
                                       (setf buffer-read-only t)
                                       (current-buffer))
                             :command (list
                                       (expand-file-name invocation-name
                                                         invocation-directory)
                                       "--batch" "-l" temp-file)

So the program we invoked already has its executable file name
expanded relative to invocation-directory, and we shouldn't need PATH
at all.  What am I missing?