#include <functional>

template<int I> struct lambda2_arg
{
};

constexpr lambda2_arg<1> _1{};

namespace std
{

template<int I> struct is_placeholder< lambda2_arg<I> >: integral_constant<int, I>
{
};

} // namespace std

struct plus_equal
{
    template<class T1, class T2> decltype(auto) operator()(T1&& t1, T2&& t2) const
    {
        return std::forward<T1>(t1) += std::forward<T2>(t2);
    }
};

struct X
{
    int m;
};

int main()
{
    X x{ 1 };
    return std::bind( plus_equal(), std::bind( &X::m, _1 ), 1 )( x );
}