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c++nestedfriend

Access private member of nested friend class in specialized template


The following code fails to compile in Visual studio 2103 Express preview:

template<int N> class TTOuter;

template<>
class TTOuter<1>
{
public:
    class inner
    {
        friend class TTOuter<1>;

    private:
        inner(int n) : data(n) {;}
        int data;
    };

private:
    inner x;

public:
    TTOuter(int n) : x(n) {;} //Fails here
};

Error: "TTOuter<1>::inner::inner(int n)" is inaccessible

An analogous access succeeds if the outer class is not a specialized template:

class Outer
{
public:
    class inner
    {
        friend class Outer;

    private:
        inner(int n) : data(n) { ; }
        int data;
    };

private:
    inner x;

public:
    Outer(int n) : x(n) { ; }
};

Gives no error.

I tried forward declaring TTOuter<1> like:

template<> class TTOuter<1>;

I also tried replacing the friend declaration by:

template<int N> friend class TTOuter;

But neither works.

Would appreciate any insight. Thank You.


Solution

  • I think it is nothing more than a typo in your code

    public:
        TOuter(int n) : x(n) {;} //Fails here
      //^^^^^^ Shouldn't it be TTouter???
    };
    

    Edited:

    If I edit a bit your code:

    class TTOuter<1>
    {
    public:
        typedef TTOuter this_type; // <-- I add this typedef
        class inner
        {
            friend class this_type; // <-- Intellisense works
            //friend class TTOuter<1>; // <-- intellisense barks
            inner(int n) : data(n) { ; }
            int data;
        };
        TTOuter(int n) : x(0) {}
    };
    

    Now intellisense stops complaining.