Suggested resolution:

Change in 11.6 [class.local] paragraph 3 as follows:

A class nested within a local class is a local class. A member of a local class X shall be declared only in the definition of X or, if the member is an enumeration or a nested class, in the nearest enclosing block scope of X.

(From submission #907.)

Consider:

  void f() {
    struct X {
      struct S;
      enum E : int;
    };
    struct X::S {};         // OK
    enum X::E : int {};     // ill-formed, but all major implementations accept
  }