I think you were confused by someone who described that "counting machinery" at too high a level of abstraction. Compile-time counting is implemented in the com

I think you were confused by someone who described that "counting machinery" at too high a level of abstraction. Compile-time counting is implemented in the compiler, runtime counting requires you to opt-in by wrapping the type in a special wrapper type. This wrapper type requires two special language features: a way to run code when a type is "dropped" (think destroyed), and a way to have a type forward method calls to another type. But any regular code can use these features. That lets you write a straightforward wrapper that forwards calls and manages the reference counting (increment on clone, decrement on drop). There's a bit more cleverness in the math, but it's all regular rust code. See <https://doc.rust-lang.org/src/alloc/rc.rs.html#15896 https://doc.rust-lang.org/src/alloc/rc.rs.html#15896> This lack of special standard-library-only magic is a key part of rust's appeal to me. Those same features let the crate parking_lot implement a better mutex than the standard library, for example.