Uses allocator construction forward_as_tuple issue

main.cpp

using namespace std;

template<class A, class... Args>
auto add_and_forward(A a, Args&&... args)
{
	return forward_as_tuple(a, forward<Args>(args)...); // <--- here is our issue
}

template<class A, class T1, class T2>
auto join(A a, T1 t1, T2 t2)
{
	return make_tuple(piecewise_construct,
					  apply([&a](auto&&... args) {
		return add_and_forward(a, forward<decltype(args)>(args)...);
	}, forward<T1>(t1)),
					  apply([&a](auto&&... args) {
		return add_and_forward(a, forward<decltype(args)>(args)...);
	}, forward<T2>(t2)));
}

template<class A, class T1, class T2>
auto foward_pair(A a, pair<T1, T2>&& p)
{
	return join(a, forward_as_tuple(move(p).first),
				   forward_as_tuple(move(p).second));
}

struct Foo
{
	Foo(int, int) { }
};

int main()
{
	auto p = make_pair(42, 101);
	auto joined = foward_pair(1, move(p));
	make_from_tuple<pair<Foo, Foo>>(joined);
}

Ignore the spacing. Github won't let me change it.