C++中临时的保证寿命？

#include<iostream>

class MyClass {
public:
    MyClass() { std::cout << "MyClass constructor"<< std::endl; }
    ~MyClass() { std::cout << "MyClass destructor"<< std::endl; }
};

void foo(const MyClass &obj) {
    // ...
}

int main() {
    foo(MyClass());
    return 0;
}

#include<iostream>
#include<vector>

class MyClass {
public:
    MyClass() { std::cout << "MyClass constructor"<< std::endl; }
    ~MyClass() { std::cout << "MyClass destructor"<< std::endl; }
};

void foo(MyClass obj) {
    // ...
}

int main() {
    foo(std::move(MyClass()));
    return 0;
}