Right, so if &mut is always unique anyway then the presence of an UnsafeCell shouldn't affect it, since it's about weakening guarantees. In fact, looking at th

Right, so if &mut is always unique anyway then the presence of an UnsafeCell shouldn't affect it, since it's about weakening guarantees. In fact, looking at the compiler output (https://godbolt.org/g/kt2xfW https://godbolt.org/g/kt2xfW), it looks like only &T has noalias, and not &mut T. It does go away in the presence of UnsafeCell, but for &mut T it was never there in the first place. So either that's a place where we can still add more noalias annotations, or it's off for some subtle reason I'm not familiar with.