从函数返回的unique_ptr的范围是什么？

unique_ptr<A> source()
{
    return unique_ptr<A>(new A);
}


void doSomething(A &a)  
{  
    // ...
}  

void test()  
{  
    doSomething(*source().get());   // unsafe?
    // When does the returned unique_ptr go out of scope?
}

int Func()
{
  int ret = 5;

  return ret;
}

void doSomething(int a) { ... }


doSomething(Func());