[Bug c++/101687] New: Scoped enumerators of a member enumeration shall not be referred by a class member access expression

[Bug c++/101687] New: Scoped enumerators of a member enumeration shall not be referred by a class member access expression

[xmh970252187 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101687

            Bug ID: 101687
           Summary: Scoped enumerators of a member enumeration shall not
                    be referred by a class member access expression
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: xmh970252187 at gmail dot com
  Target Milestone: ---

struct A{
    enum class C{
        a = 0
    };
};
int main(){
   A a;
   auto c = a.C::a;  //#1
}

> Each enum-name and each unscoped enumerator is declared in the scope that immediately contains the enum-specifier. 

> An enumerator declared in class scope can be referred to using the class member access operators (​::​, . (dot) and -> (arrow)), see [expr.ref].

According to the above rule, A::C::a shouldn't appear in the id-expression of a
member access expression, which means `#1` should be ill-formed.

[Bug c++/101687] Scoped enumerators of a member enumeration shall not be referred by a class member access expression

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101687

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2021-08-05
     Ever confirmed|0                           |1

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.

GCC 4.7.4 used to ICE on this.

[Bug c++/101687] Scoped enumerators of a member enumeration shall not be referred by a class member access expression

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101687

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Hmm, MSVC also accepts this code but clang does not.

[Bug c++/101687] Scoped enumerators of a member enumeration shall not be referred by a class member access expression

[xmh970252187 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101687

--- Comment #3 from jim x <xmh970252187 at gmail dot com> ---
I think CWG2557 is clear with this aspect
https://cplusplus.github.io/CWG/issues/2557.html

[Bug c++/101687] Scoped enumerators of a member enumeration shall not be referred by a class member access expression

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101687

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |SUSPENDED

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Suspending as the defect report is still considered open but is in the process
of drafting:
https://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#2557