This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 114b. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.

2024-05-06


139. Error in friend lookup example

Section: 6.5.3  [basic.lookup.unqual]     Status: CD1     Submitter: Mike Miller     Date: 14 Jul 1999

[Moved to DR at 10/01 meeting.]

The example in 6.5.3 [basic.lookup.unqual] paragraph 3 is incorrect:

    typedef int f;
    struct A {
        friend void f(A &);
        operator int();
        void g(A a) {
            f(a);
        }
    };
Regardless of the resolution of other issues concerning the lookup of names in friend declarations, this example is ill-formed (the function and the typedef cannot exist in the same scope).

One possible repair of the example would be to make f a class with a constructor taking either A or int as its parameter.

(See also issues 95, 136, 138, 143, 165, and 166.)

Proposed resolution (04/01):

  1. Change the example in 6.5.3 [basic.lookup.unqual] paragraph 3 to read:

        typedef int f;
        namespace N {
            struct A {
                friend int f(A &);
                operator int();
                void g(A a) {
                    int i = f(a);
                          // f is the typedef, not the friend function:
                          // equivalent to int(a)
                }
            };
        }
    
  2. Delete the sentence immediately following the example:

    The expression f(a) is a cast-expression equivalent to int(a).