#include <iostream>
#include <map>
#include <utility>

class W {
    public:
        W() { std::cout << "W()\n"; }
        W(int a) : a_(a) { std::cout << "W(int a)\n"; }
        int get_a() { return a_; }
    private:
        int a_;
};

void foo_at(W bar) {
    std::map<int, W> map;
    map[0] = bar;
}

void foo_insert(W bar) {
    std::map<int, W> map;
    map.insert(std::make_pair(0, bar));
}

void foo_emplace(W bar) {
    std::map<int, W> map;
    map.emplace(std::make_pair(0, bar));
}

int main() {
    std::cout << "foo_at\n";
    foo_at(W(10));
    std::cout << "foo_insert\n";
    foo_insert(W(10));
    std::cout << "foo_emplace\n";
    foo_emplace(W(10));

    return 0;
}