That's actually really nice. It does appear that Rust will peel all the layers away when opt-level is 2 or higher. I could live with that. You can (re)set th

That's actually really nice. It does appear that Rust will peel all the layers away when opt-level is 2 or higher. I could live with that. You can (re)set the value from anywhere, but at least it has to be marked unsafe. Fair enough! When I tried to do this a couple years ago (with mem::uninitialized), I failed to get something usable. I think I was also concerned that having to use unsafe for the reads would prohibit compiler optimizations, even if it could be wrapped in a safe wrapper as you did here. Maybe that was worrying for nothing. Maybe it's time to try Rust again.