[CodesInChaos]

I thought `UnsafeCell` is only exempt from the aliasing rules, not the memory model? I.e. the compiler can use it as it wants, if it can prove that it's not accessed in the meantime (which can be difficult without relying aliasing rules, but possible if the code is simple enough)

[carllerche]

To be honest, I'm not entirely following what you see as the danger. The compiler can't generate code that randomly goes and writes at pointer locations.