https://godbolt.org/z/zM3oxjrfn

and contrast this Rust:

https://rust.godbolt.org/z/1rMYcqY65

In your unique_ptr<T> example what you'd hidden (from me? Or perhaps from yourself) was that we're not destroying the unique_ptr, we're just destroying the Foo, and since the unique_ptr is null the destructor for that will be silent when the scope ends.