c++ variant

test1.cpp

#include <variant>
#include <cstdio>

struct Thing {
    Thing() {
        std::printf("default constructor\n");
    }
    Thing(Thing &&other) {
        std::printf("move constructor\n");
    }
    ~Thing() {
        std::printf("destructor\n");
    }
};

std::variant<Thing, int> new_thing() {
    return Thing{};
}

int main () 
{
    auto v = new_thing();
    std::printf("after new\n");
}

// Outputs when compiled with C++17 -O0 on cpp.sh
// default constructor
// move constructor
// destructor
// after new
// destructor

test2.cpp

#include <variant>
#include <cstdio>

struct Thing {
    Thing() {
        std::printf("default constructor\n");
    }
    Thing(Thing &&other) {
        std::printf("move constructor\n");
    }
    ~Thing() {
        std::printf("destructor\n");
    }
};

std::variant<Thing, int> new_thing() {
    return std::variant<Thing, int>{std::in_place_type<Thing>};
}

int main () 
{
    auto v = new_thing();
    std::printf("after new\n");
}

// Outputs when compiled with C++17 -O0 on cpp.sh
// default constructor
// after new
// destructor