Local Classes May Not Use Variables from the Function’s Scope

The names from the enclosing scope that a local class can access are limited. A local class can access only type names, static variables (§ 6.1.1, p. 205), and enumerators defined within the enclosing local scopes. A local class may not use the ordinary local variables of the function in which the class is defined:

int a, val;
void foo(int val)
{
    static int si;
    enum Loc { a = 1024, b };
    // Bar is local to foo
    struct Bar {
        Loc locVal; // ok: uses a local type name
        int barVal;
        void fooBar(Loc l = a)   // ok: default argument is Loc::a
        {
            barVal = val;    // error: val is local to foo
            barVal = ::val;  // ok: uses a global object
            barVal = si;     // ok: uses a static local object
            locVal = b;      // ok: uses an enumerator
        }
    };
    // . . .
}