Same as with GC, neither need be a fixed choice; having a GC library/feature in Rust wouldn't mean that everything will be and must be GC'd; and it's still poss

Same as with GC, neither need be a fixed choice; having a GC library/feature in Rust wouldn't mean that everything will be and must be GC'd; and it's still possible to add unleakable types were it desired: https://rust-lang.github.io/keyword-generics-initiative/evaluation/unleakable-types.html https://rust-lang.github.io/keyword-generics-initiative/eval... while keeping neat things like Rc<T> available for things that don't care. (things get more messy when considering defaults and composability with existing libraries, but I'd say that such issues shouldn't prevent the existence of the options themselves)