pin is purely a property of a pointer, so Pin<i32> doesn’t make sense. While you’re right that Box gives you a stable address, you can still move out of a Box,

pin is purely a property of a pointer, so Pin<i32> doesn’t make sense. While you’re right that Box gives you a stable address, you can still move out of a Box, or swap something into the Box. Pin<Box<P>> prevents that.