问C++成员函数指针定义

EN

#include <iostream>
#include <functional>

struct B {
    template <class C, class M, class T>
    void call1(C (M::*member)(), T *instance) {
        std::function<void()> fp = std::bind(member, instance);
        fp();
    }

    template <class C, class M, class T>
    void call2(C (M::*member), T *instance) {
        std::function<void()> fp = std::bind(member, instance);
        fp();
    }

    void foo() {
        call1(&B::func, this); // works
        call2(&B::func, this); // works

        call1(&B::func2, this); // Error: no matching member function for call to 'call2'
        call2(&B::func2, this); // works
    }

    void func() {
        std::cout << "func\n";
    }

    void func2() const volatile {
        std::cout << "func2\n";
    }
};

int main() {
    B{}.foo();
}