How to copy (or swap) objects of a type that contains members that are references or const?

Question

The problem I am trying to address arises with making containers such as an std::vector of objects that contain reference and const data members:

Answer 1

This however loses the advantages of references over pointers

There is no advantage. Pointers and reference are different, but none is the better one. You use a reference to ensure that there is a valid instance and a pointer if passing a nullptr is valid. In your example you could pass a reference and store a pointer

struct Bar {
   Bar (Foo & foo) : foo_reference(&foo) {}
private:
   Foo * foo_reference;
};