Is it legal to pass a newly constructed object by reference to a function?

Question

Specifically, is the following legal C++?

class A{};

void foo(A*);
void bar(const A&);

int main(void)
{
    foo(&A());  // 1
    bar(A());  // 2
}

It a

Answer 1

It is legal. We use it sometime to provide a default value which we might want to ignore.

int dosomething(error_code& _e = ignore_errorcode()) {
    //do something
}

In the above case it will construct an empty error code object if no error_code is passed to the function.