Virtual box has been discussed many many times on this Forum,..
The Open Source Initiative has approved the license as open source, but
Debian, Fedora and the Free Software Foundation have rejected it because "It
requires you to publish the source code publicly whenever you “Deploy”
the covered software, and “Deploy” is defined to include many kinds of
private use."
https://en.wikipedia.org/wiki/Watcom_C/C%2B%2B
https://wiki.archlinux.org/index.php/Open_Watcom
Debian Wiki !!!...
A proprietary extra package enhances the base experience
https://wiki.debian.org/VirtualBox
https://processor.revolvy.com/topic/Watcom%20C%20compiler&item_type=topic
Watcom C/C++ was a commercial product until it was discontinued, then
released as freeware under the name Open Watcom C/C++.
