Mutually dependant using definitions

Question

I have some mutually dependent template instances. Normally I'd just forward declare them but I don't see how this is possible. Here is an example

#include <tuple>
#include <memory>

using Tuple = std::tuple<int,TupleContainer>;
using TupleContainer = std::unique_ptr<Tuple>;

int main()
{
    return 0;
}

Can't write Tuple first due to needing TupleContainer, can't write TupleContainer first due to needing Tuple.

How can I forward declare one of the using definitions?

Answer 1

I managed to do it by using a thin wrapper class around std::tuple and using a forward declaration.

#include <tuple>
#include <memory>

struct Tuple;
using TupleContainer = std::unique_ptr<Tuple>;

struct Tuple : public std::tuple<int,TupleContainer>{
    using std::tuple<int,TupleContainer>::tuple;
};

int main()
{
    return 0;
}