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