Creating unaligned references is UB, so it's illegal to take a reference to a packed struct field. However, even if you just wanted to create a raw pointer to t

Creating unaligned references is UB, so it's illegal to take a reference to a packed struct field. However, even if you just wanted to create a raw pointer to that field, you would've had to do `&packed.f2 as *const u16`, which is technically UB since you do create a temporary reference before casting it to a pointer. I'm sure one way to solve that is to just allow that as a special case; say that `&<expr> as *const _` semantically doesn't actually create a reference. But, the way the lang team went is to have a separate macro that transforms `ptr::addr_of!(<expr>)` to something like C's `&<expr>` operator, so that it creates a raw pointer directly instead of a reference.