friend48.c

gcc-you can use this code to learn something about gcc, and inquire further into linux,

// Build don't link:
// Origin: Mark Mitchell <[e-mail]>

template <class T>
class C {
  template <class U>
  friend class ::C;
};

namespace N 
{
template <class T>
class D {
  template <class U>
  friend class N::D;
};
};