bug#71853: 29.4; `kill-compilation` does not kill compilation process on Windows

[Eli Zaretskii <eliz@gnu.org>]

> From: Tze Chian Kam <tze.chian.kam@gmail.com>
> Date: Tue, 2 Jul 2024 16:36:38 +1000
> Cc: 71853@debbugs.gnu.org
> 
> > From: Tze Chian Kam
> > Date: Tue, 2 Jul 2024 16:26:32 +1000
> >
> > > From: Eli Zaretskii
> > > Date: Mon, 01 Jul 2024 14:27:09 +0300
> > >
> > > > From: Tze Chian Kam <tze.chian.kam@gmail.com>
> > > > Date: Mon, 1 Jul 2024 12:53:51 +1000
> > > > Cc: 71853@debbugs.gnu.org
> > > >
> > > > > > Sorry, I used a Python file:
> > > > > > ```
> > > > > > import time
> > > > > >
> > > > > > while True:
> > > > > >     print("active")
> > > > > >     sleep(1)
> > > > > > ```
> > > > >
> > > > > And how exactly did you invoke this?  Please show the complete
> > > > > command you typed at the prompt of "M-x compile", because trying
> > > > > to reproduce this (see below) I could't.
> > > >
> > > > I did "M-x compile RET python loop.py RET". Also, when running this
> > > > program, it does not output anything in the *compilation* buffer ("active"
> > > > is not printed every second).
> > >
> > > The fact that it doesn't print "active" is already a sign of some
> > > problem.
> > >
> > > Where did you download your Python from?  Is it a native Windows
> > > executable, or something else, like Cygwin or MSYS2 build of Python?
> >
> > It is a MSYS2 build of Python.
> >
> > I just tested with Emacs in my global path (so I can launch Emacs from
> > Powershell/Command Prompt) and it "C-c C-k' works (using native
> > Windows Python) but I still can't see the prints before killing the process.
> 
> I can see the prints if I do "print("active", flush=True)". Does that mean
> there is a flushing problem on my Emacs?

Something like that, yes.  But I don't understand why it happens for
you with "emacs -Q" and the native Windows Python; it doesn't happen
for me.