Compiler Error C3213

base class 'base_type' is less accessible than 'derived_type'

A type that will be visible from an assembly must use publicly visible base classes.

The following sample generates C3213:

// C3213.cpp
// compile with: /clr
private ref struct privateG {
public:
   int i;
};

public ref struct publicG {
public:
   int i;
};

public ref struct V : public privateG {   // C3213
public:
   int j;
};

public ref struct W: public publicG {   // OK
public:
   int j;
};