Compiler Error C2885

'class::identifier' : a using-declaration as a member of a class must be a member-declaration

You used a using declaration incorrectly. If you use the using keyword with a class member, C++ requires you to define that member inside another class (a derived class).

The following example shows the error:

class A {
public:
   int i;
};

void z() {
   using A::i; // error C2885, not member declaration
}