Rust's borrow checker solves the problem of "get a reference to something interior, and the parent is deallocated". It knows (by static analysis) when an inner

Rust's borrow checker solves the problem of "get a reference to something interior, and the parent is deallocated". It knows (by static analysis) when an inner reference may be in use, and won't let the program compile if the parent could deallocate during that time. This works well even with externally refcounted objects. You can give reference to an inner object without increasing its refcount, and rely on the borrow checker not to allow the parent to decrease the refcount. Or you bump the refcount of the inner object and give it out as an independently owned object.