9 Declarations [dcl.dcl]

9.7 Enumerations [enum]

9.7.2 The using enum declaration [enum.udecl]

using-enum-declaration:
using elaborated-enum-specifier ;

The elaborated-enum-specifier shall not name a dependent type and the type shall have a reachable enum-specifier.

A using-enum-declaration introduces the enumerator names of the named enumeration as if by a using-declaration for each enumerator.

[Note 1:

A using-enum-declaration in class scope adds the enumerators of the named enumeration as members to the scope.

This means they are accessible for member lookup.

[Example 1: enum class fruit { orange, apple }; struct S { using enum fruit; // OK, introduces orange and apple into S }; void f() { S s; s.orange; // OK, names fruit::orange S::orange; // OK, names fruit::orange } — end example]

— end note]

[Note 2:

Two using-enum-declarations that introduce two enumerators of the same name conflict.

[Example 2: enum class fruit { orange, apple }; enum class color { red, orange }; void f() { using enum fruit; // OK using enum color; // error: color::orange and fruit::orange conflict } — end example]

— end note]