Compiler Error C3183

cannot define unnamed class, struct or union inside of managed or WinRT type 'type'

A type that is embedded in a managed or WinRT type must be named.

The following sample generates C3183:

// C3183a.cpp
// compile with: /clr /c
ref class Test
{
   ref class
   {  // C3183, delete class or name it
      int a;
      int b;
   };
};