type-string.cpp

#include <iostream>
#include <string>

template <char... Characters>
struct string_literal {
   static const std::size_t string_length = sizeof...(Characters);
   static constexpr char str[string_length] = {Characters...};
};

template <char... Characters>
constexpr char string_literal<Characters...>::str[];

template <typename CharT, CharT ...String>
constexpr auto operator "" _op() -> string_literal<String...>
{
    return string_literal<String...>();;
}

template <typename T>
struct foo
{
    typedef T literal;
};

typedef foo<decltype("hello!"_op)> foo_fak;

int main() {
    std::cout << foo_fak::literal::str << std::endl;
    return 0;
}