Does Microsoft use Windows to compile Windows?

In September 2020, most of the source code for windows XP and server 2003 was on a torrent. That leak did not include winlogin and some drivers.

A couple of people compiled it.

Here is a video of compiling the windows 2003 source code on an XP box.

https://odysee.com/@AlphaNerd:8/windows-server-2003-full-bui...

Yes, why wouldn't they?

Now they probably had NT compiling Windows 9X versions but today the distinction is less accentuated. Probably still on Windows Server

hey use their own “Visual C++” compiler. However, they don't stick to the commercially-available releases