#include <boost/serialization/static_warning.hpp>
#include <boost/static_assert.hpp>
#include <boost/type_traits/is_same.hpp>

#include <cstdint>

template <typename T>
struct safe_convertable
{
public:
    explicit safe_convertable(T& ref) :
            _ref(ref)
    { }
    
    template <typename TDestination>
    operator TDestination ()
    {
        typedef boost::is_same<T, TDestination> same_type;
        BOOST_STATIC_WARNING(same_type::value);
        // This will fail, as expected:
        //BOOST_STATIC_ASSERT(same_type::value);
        return _ref;
    }
private:
    T& _ref;
};

template <typename T>
safe_convertable<T> get(T& ref)
{
    return safe_convertable<T>(ref);
}

int main()
{
    int64_t x = 0;
    // this should fail:
    int32_t y = get(x);
    
    return y;
}