CWG3143 [diff.dcl] Annex C statement about type of enumerators incorrect after rebase to C23

[hubert-reinterpretcast]

Full name of submitter (unless configured in github; will be published with the issue): Hubert Tong

Reference (section label): [diff.dcl]

Link to reflector thread (if any): N/A

Issue description:

https://wg21.link/diff.dcl#12 states that the type of enumerators in C is int. This is not true in C23 since the adoption of https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3029.htm and https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3030.htm.

Suggested resolution:

Replace "is int" with "can be int".

[frederick-vs-ja]

In addition to this fix, I think it's better to have a more robust example which directly relies on type difference.

[jensmaurer]

@frederick-vs-ja , specific suggestions welcome.

[frederick-vs-ja]

Maybe the following one would be OK, as C23 also have auto type deduction added via WG14 N3007 (demo):

void f() {
  enum e { A };
  auto x = A;
  int* p = &x; // valid C, invalid C++
}

[hubert-reinterpretcast]

Maybe the following one would be OK, as C23 also have auto type deduction added via WG14 N3007 (demo):

With this example, the "How widely used" needs to change too.

[jensmaurer]

CWG3143

[hubert-reinterpretcast]

@jensmaurer, I think "or another integer type" is confusing (if correct under some specific reading). If the type of an enumerator is not int in C, it can have enumeration type (although enumeration types are integer types in C but not C++).