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


2483. Language linkage of static member functions

Section: 9.11  [dcl.link]     Status: C++23     Submitter: Davis Herring     Date: 2021-03-11

[Accepted as a DR at the February, 2023 meeting.]

According to 9.11 [dcl.link] paragraph 5,

A C language linkage is ignored in determining the language linkage of class members, friend functions with a trailing requires-clause, and the function type of class member functions.

It doesn't make sense that static member functions should behave like non-static member functions in this regard:

   extern "C" {
     struct A {
       static void f();
       constexpr static void (*p)()=f; // error: must point to a function whose type has C language linkage
     };
   }

Suggested resolution:

Change 9.11 [dcl.link] paragraph 5 as follows:

A C language linkage is ignored in determining the language linkage of class members, friend functions with a trailing requires-clause, and the function type of non-static class member functions.

Notes from the August, 2021 teleconference:

There was some question as to whether a linkage specification should affect the language linkage of any function declarators within class scope. The question was also raised as to whether some non-typedef syntax should be available for affecting language linkage, which would be a question for EWG.

Proposed resolution (approved by CWG 2022-11-10):

Change 9.11 [dcl.link] paragraph 5 as follows:

A C language linkage is ignored in determining the language linkage of class members, friend functions with a trailing requires-clause, and the function type of non-static class member functions.