CWG2692 Static and explicit object member functions with the same parameter-type-lists

[jensmaurer]

Consider this example:

  struct A {
    static void f(A);
    void f(this A);

    void g();
  };

  void A::g() {
    (&A::f)(A()); // #1
    (&A::f)();    // #2
  }

What should happen for #1? One possible answer is that the /member-specification/ of A is ill-formed because of conflicting declarations for f. That would also allow mangling the explicit-object member function A::f the same as the static member function.

See CWG2692

[erichkeane]

This was discussed in the February 6th, 2023 afternoon session in Issaquah.

No polls were taken, however Gašper has agreed to work with Barry to return with a paper exploring the design space, and propose a solution.

[erichkeane]

This was discussed in the February 8th, 2023 afternoon session in Issaquah. The following polls were taken:

Given:

struct A {
  static void f(A); // #A
  void f(this A);   // #B

  static void e(A const&); // #C
  void e() const&;         // #D

  void g() {
    // static + explicit memfn
    (&A::f)(A()); // #1
    f(A());       // #2
    (&A::f)();    // #3

    // static + implicit memfn
    (&A::e)(A()); // #4
    e(A());       // #5
    (&A::e)();    // #6
  }
};

#1 == #2, and #4 == #5

SF	F	N	A	SA
0	0	2	9	1

Result: Consensus Against

#1 is ambiguous, #2 calls '#A'
#4 is ambiguous, #5 calls '#C'

SF	F	N	A	SA
5	7	0	0	0

Result: Consensus

Authors will work with their core expert and bring this directly to CWG.

[jensmaurer]

Resolved by P2797R0.