Consider:

  struct S {
    int a;
  };
  int x = offsetof(S, S::a)

Is this valid? MSVC and gcc appear to support qualified-ids in the member-designator of offsetof; clang does not. Once that question is clarified, the rules about value-dependence may need to be amended, because a qualified-id might introduce type-dependence.

Specific questions:

• Is a qualified-id allowed to appear in a member-designator?
• Is a template-id allowed to appear in a member-designator?
• Is an offsetof expression a core constant expression (7.7 [expr.const])?

2023-08-23

Forwarded to EWG with paper issue #1616, by decision of the CWG chair.

EWG 2023-11-07

EWG is soliciting a paper to thoroughly explore the design space.