// 函数原型
template <class T> T&& forward (typename remove_reference<T>::type& t) noexcept;
template <class T> T&& forward (typename remove_reference<T>::type&& t) noexcept;// 精简之后的样子
std::forward<T>(t);

推导规则:

#include <iostream>
using namespace std;template<typename T>
void printValue(T& t)
{cout << "l-value: " << t << endl;
}template<typename T>
void printValue(T&& t)
{cout << "r-value: " << t << endl;
}template<typename T>
void testForward(T && v)
{printValue(v);printValue(move(v));printValue(forward<T>(v));cout << endl;
}int main()
{testForward(520);int num = 1314;testForward(num);testForward(forward<int>(num));testForward(forward<int&>(num));testForward(forward<int&&>(num));return 0;
}/*作者: 苏丙榅
链接: https://subingwen.cn/cpp/move-forward/#2-forward
来源: 爱编程的大丙*/

测试结果:

该文参考于下面链接
链接: https://subingwen.cn/cpp/move-forward/#2-forward