Rust is capable of eliminating unnecessary count increments and decrements for Rc fairly often. The compiler doesn't usually need specific knowledge -- if there is a +1 and then a -1 LLVM is smart enough to cancel that out on its own. I'd actually be curious to see examples where it doesn't.

I mean, how often are you cloning an Rc? It’s not like c++ where passing a shared_ptr to a function is going to copy it. Most of the time you’re going to move it.