To clarify, it was already on for clang on posix (since clang tries to imitate gcc there). That CL made it work on win clang as well.

Meh, we're switching to clang on win in m62, and in that config WARN_UNUSED_RESULT already does something.

I meh'd on another thread for the same reasons, so I think it's fine to WontFix.

However, I'll open a bug on moving to the C++17 [[nodiscard]] attribute, since that will eventually be the proper solution and it should work everywhere.