Classy disclaimer! matthieum's (long) reddit comment is also an informative read: https://www.reddit.com/r/rust/comments/1up0uhg/girls_just_wa...

    unsafe impl<T, const N: usize> Sync for WFQueue<T, N> {}
    unsafe impl<T, const N: usize> Send for WFQueue<T, N> {}

The fix is straightforward:

    unsafe impl<T: Sync, const N: usize> Sync for WFQueue<T, N> {}
    unsafe impl<T: Send, const N: usize> Send for WFQueue<T, N> {}

Actually, later on, the code makes a similar mistake, but only for one impl.

    unsafe impl<'a, T, const N: usize> Send for DrivableWFEnqueue<'a, T, N> where T: Send {}
    unsafe impl<'a, T, const N: usize> Send for DrivableWFDequeue<'a, T, N> {}

Sounds like fun.