Consider your statement against the fact that Microsoft are currently pushing a Linux subsystem in Windows. They are doing what is basically a clean-room imple

Consider your statement against the fact that Microsoft are currently pushing a Linux subsystem in Windows. They are doing what is basically a clean-room implementation of the Linux ABI to avoid the GPL. What stops ReactOS doing the reverse? Microsoft have had 13 years to review the source code for ReactOS and haven't had a problem with it so far. The only major issue arose internally: > A claim was made on 17 January 2006, by now former developer Hartmut Birr on the ReactOS developers mailing list (ros-dev) that ReactOS contained code derived from disassembling Microsoft Windows. The code that Birr disputed involved the function BadStack in syscall.S. as well as other unspecified items. Comparing this function to disassembled binaries from Windows XP, Birr argued that the BadStack function was simply copy-pasted from Windows XP, given that they were identical. Alex Ionescu, the author of the code, asserted that while the Windows XP binary in question was indeed disassembled and studied, the code was not merely copy-pasted, but reimplemented; the reason why the functions were identical, Ionescu claimed, was because there was only one possible way to implement the function.[1] [1]: https://en.wikipedia.org/wiki/ReactOS#Internal_audit https://en.wikipedia.org/wiki/ReactOS#Internal_audit