[steveklabnik]

My C is a bit Rusty, so I'll say that they follow http://llvm.org/docs/LangRef.html#noalias which says

    > Note that this definition of noalias is intentionally similar to the
    > definition of restrict in C99 for function arguments.

I'm not sure if they just mean 'similar' or if it's actually exact.

If you alias, you might break, as optimizations will assume otherwise.

Oh, and `&mut` pointers are safe to use, not unsafe.