boost::combine, range-based for and structured bindings

The real answer is to use either boost::tie or grab the range-v3 zip() which actually yields a std::tuple.

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The for educational purposes only answer is just to adapt the structured bindings machinery for boost::tuples::cons. That type already has a get() which works with ADL and does the right thing, so all we need to do is provide tuple_size and tuple_element (which ends up being really easy to do since these exact traits already exist in Boost):

namespace std {
    template <typename T, typename U>
    struct tuple_size<boost::tuples::cons<T, U>>
        : boost::tuples::length<boost::tuples::cons<T, U>>
    { };

    template <size_t I, typename T, typename U>
    struct tuple_element<I, boost::tuples::cons<T, U>>
        : boost::tuples::element<I, boost::tuples::cons<T, U>>
    { };
}

But don't actually do that in real code, since really only the type author should opt-in to this kind of thing.

That'll make the structured binding just work.