我使用的是int &&，并且用于的是左值函数，而不是右值

Question

我开始学习有关右值的参考。我试图理解我的代码，但我不懂一行，为什么对左值而不是右值使用函数。

#include <iostream>
void reference_fun(int &k) {
  std::cout << "reference to lvalue (object) = " << k << std::endl;
}

void reference_fun(int &&k) {
  std::cout << "reference to rvalue (temporary) = " << k << std::endl;
}

void test2(int &&k) {

  //rvalue in the body of the function becomes lvalue
  reference_fun(k);
  reference_fun(std::move(k));
}

int main() {
  int obj = 10;
  int &&rvalue = 10 + 10;
  reference_fun(obj);                                                     /* result as function to lvalue */
  reference_fun(321);                                                     /* result as function to rvalue */
  reference_fun(321 + 3);                                                 /* result as function to rvalue */
  reference_fun(rvalue); // I don't understand the result of this line, why is used function to lvalue, when rvalue is int && ?
  test2(14 + 10);                                                         /* result as function to lvalue and rvalue */
  // test2(rvalue); //compilation error
  return 0;
} 

这是我的输出：

reference to lvalue (object) = 10
reference to rvalue (temporary) = 321
reference to rvalue (temporary) = 324
reference to lvalue (object) = 20 //this line ?
reference to lvalue (object) = 24
reference to rvalue (temporary) = 24

我对此行有疑问：reference_fun(rvalue); 当我将void reference_fun(int &k);定义为void reference_fun(int &&k);时为何使用rvalue而不使用int&&吗？