namespace std { class type_info; }

#include <boost/preprocessor/cat.hpp>
#include <iostream>
#include <type_traits>
#include <string>
    
template< typename T >
struct eq1
{
    T a; T b;
    template< typename TX > static char check ( TX a, TX b, char(*)[sizeof
        (std::is_convertible<decltype(a == b), bool>)
    ]);
    template< typename TX > static long check ( ... );
    static const bool value = sizeof(char) == sizeof check<T>(a, b, 0);
};

template< typename T >
struct eq2
{
    T a; T b;
    template< typename TX > static char check ( TX a, TX b, char(*)[sizeof
        bool{a == b}
    ]);
    template< typename TX > static long check ( ... );
    static const bool value = sizeof(char) == sizeof check<T>(a, b, 0);
};

struct x { x(char*); };

int main ( void )
{
    std::cout << eq1<int>::value << std::endl;
    std::cout << eq1<x>::value << std::endl;
    std::cout << eq1<std::string>::value << std::endl;
    std::cout << std::endl;
    std::cout << eq2<int>::value << std::endl;
    std::cout << eq2<x>::value << std::endl;
    std::cout << eq2<std::string>::value << std::endl;
    return 0;
}