This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 116a. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.

2024-12-19

207. using-declarations and protected access

[Moved to DR at 10/01 meeting.]

Consider the following example:

  class A {
  protected:
    static void f() {};
  };

  class B : A {
  public:
    using A::f;
    void g() {
      A::f();
    }
  };

The standard says in 11.8.3 [class.access.base] paragraph 4 that the call to A::f is ill-formed:

A member m is accessible when named in class N if

• m as a member of N is public, or
• m as a member of N is private, and the reference occurs in a member or friend of class N, or
• m as a member of N is protected, and the reference occurs in a member or friend of class N, or in a member or friend of a class P derived from N, where m as a member of P is private or protected, or
• there exists a base class B of N that is accessible at the point of reference, and m is accessible when named in class B.

Here, m is A::f and N is A.

• f as a member of A is public? No.
• f as a member of A is private? No.
• f as a member of A is protected? Yes.
• reference in a member or friend of A? No.
• reference in a member or friend of a class derived from A? Yes, B.
• f as a member of B private or protected? No, public.
• base of A accessible at point of reference? No.

It seems clear to me that the third bullet should say "public, private or protected".

Steve Adamczyk:The words were written before using-declarations existed, and therefore didn't anticipate this case.

Proposed resolution (04/01):

Modify the third bullet of the third change ("A member m is accessible...") in the resolution of issue 9 to read "public, private, or protected" instead of "private or protected."