And to elaborate on this, there&#x27;s a namespace clash: Arc in Rust is _atomic_ reference counting, and Swift is _automatic_ reference counting, which, even more confusingly, is implemented using atomic reference counting in my understanding.<p>Automatic reference counting inserts all of the refcount bumps. In Rust, you have to write the up count yourself, but not the downcount.<p>But, reference counting isn&#x27;t used very often, at least in my experience. It&#x27;s very useful when you have non-scoped threads, though.