Why do I get C2248 (inaccessible member) with a protected static member?

问题

Let's say I have:

#include <Windows.h>
#include <iostream>
#include <vector>

std::vector<int> Base::m_intList;

class Base
{
public:
    Base();
protected:
    static std::vector<int> m_intList;
};

class Derived : Base
{
public:
    Derived();
protected:
    bool fWhatever;
};

class MoreDerived : Derived
{
public:
    MoreDerived();
private:
    HRESULT DoStuff();
};

Base::Base()
{

}

Derived::Derived()
{

}

MoreDerived::MoreDerived()
{

}

HRESULT MoreDerived::DoStuff()
{
    for (auto it = m_intList.begin(); it != m_intList.end(); it++)
    {
        std::cout << *it;
    }
}

When I try to compile this, I get "m_intList: cannot access inaccessible member declared in class 'MoreDerived'".

Question: Why can't I access a protected static member in the derived class's DoStuff function?

回答1:

class Derived : Base means class Derived : private Base. The behaviour of private inheritance is:

• protected members of the base class become private members of the derived class.
• private members of the base class have no access as members of the derived class.

So m_intList is:

• protected in Base
• private in Derived
• no access in MoreDerived

hence your error.

来源：https://stackoverflow.com/questions/42966024/why-do-i-get-c2248-inaccessible-member-with-a-protected-static-member