Strongeesh typedefs in C++17

strong.cpp

#include <iostream>

struct UserName { std::string name; };
struct Password { std::string pwd; };

template<typename T>
auto peek(const T& packed) {
    static_assert(std::is_aggregate_v<T>, "Should be struct");
    // we can further enforce T to have single field with 
    const auto& [value] = packed;
    return value;
}

void login(UserName name, Password pass) {
    std::cout << peek(name) << ":" << peek(pass) << "\n";
}

int main(int argc, char** argv) {
    login(UserName{"vlad"}, Password{"abc"});
    // Wont compile: login(Password{"abc"}, UserName{"vlad"});
}