Enum forward declaration - what am I doing wrong?

Question

Programming

I'm trying to make an Enum forward declaration.
I want the enum to belong to SomeClass.
SomeClass.h

class SomeClass
{
public:
    enum class InnerEnum : int
    {
        A,
        B,
        C
    };
}

OtherClass.h

enum class SomeClass::InnerEnum : int;

class OtherClass
{
private:
    SomeClass::InnerEnum mVariable;
};

The error is like this:

error: opaque-enum-specifier must use a simple identifier enum class SomeClass::InnerEnum : int;

UPD
Exhaustive answer stackoverflow.com/questions/13842006/c-forward-dec...

Answer 1

You can’t just declare it like that, just like you can’t declare a class in this way

enum class SomeClass::InnerEnum : int; //not valid
class Outer::Inner; //not valid
class some_namespace::Class; //not valid