#pragma once

struct NoTriviallyConstructible {
public:
    NoTriviallyConstructible() = delete;
};

struct NoCopyConstructible {
public:
    NoCopyConstructible(const  NoCopyConstructible&) = delete;
    NoCopyConstructible& operator=(const  NoCopyConstructible&) = delete;
};

template <>
struct Convert<NoTriviallyConstructible, int> {
    int operator()(const int& a) {
        return a;
    }
};

template <>
struct Convert<NoCopyConstructible, NoTriviallyConstructible> {
    int operator()(const int& a) {
        return a;
    }
};

template<typename T, typename Ti>
struct is_customly_convertible {
    template<typename T1>
    static void detect(...);

    template<typename T1>
    static decltype(T1().operator()(0))
        detect(decltype(&T1::operator()));

    template<typename T1>
    static decltype(T1().operator()({0, 0}))
        detect(decltype(&T1::operator()));

    static constexpr bool value = !std::is_same<void,
        decltype(detect<Convert<T, Ti>>(0))>::value;
};