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

2692. Static and explicit object member functions with the same parameter-type-lists

[Accepted at the February, 2023 meeting as part of paper P2797R0.]

(Split off from issue 2687.)

Consider:

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

    void g();
  };

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

It is obvious that #2 is ill-formed, but what about #1? One possible answer is to make such declarations conflict.

Suggested resolution:

1. Change in 6.4.1 [basic.scope.scope] paragraph 3, adding bullets, a follows:

   Two function templates have corresponding signatures if

   • their template-parameter-lists have the same length,
   • their corresponding template-parameters are equivalent,
   • they have equivalent
     • parameter-type-lists or non-object-parameter-type-lists and
     • return types (if any), and,
   • if both are non-static members, they have corresponding object parameters.

2. Change in 6.4.1 [basic.scope.scope] bullet 4.3.1 as follows:

   • both declare functions with the same parameter-type-list or non-object-parameter-type-list [Footnote: ...], equivalent (13.7.7.2 [temp.over.link]) trailing requires-clauses (if any, except as specified in 13.7.5 [temp.friend]), and, if both are non-static members, they have corresponding object parameters, or

CWG 2023-01-27

Forward to EWG to determine whether such member declarations are considered sufficiently confusing to outweigh concerns of language orthogonality; see plusplus/papers#1455.