Inspired by some other recent thread here, I would like to discuss the legality of ReactOS. So far it's been found that Wine no longer accepts contributions from ReactOS, as they stated on their website "Don't look at ReactOS code either (not even header files). A lot of it was reverse-engineered using methods that are not appropriate for Wine, and it's therefore not a usable source of information for us. [1]" (source: https://wiki.winehq.org/Clean_Room_Guidelines)
Also found https://www.osnews.com/story/15175/review-reactos/ with some comments from ReactOS developer.
Finally, after some deep searching I found https://web.archive.org/web/20070106124749if_/http://www.reactos.org:80/wiki/index.php/TinyKRNL it is no longer available on their website. From one side they say that they had relationship with Tinykrnl and the latter used dirty reverse engineering methods. On the other side they said they couldn't directly utilize it. I also found that Tinykrnl and ReactOS had at least two common developers.
I don't know what to think about it. I'm puzzled.