friend8.c

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

// Build don't link:
// 
// Copyright (C) 2000 Free Software Foundation, Inc.
// Contributed by Nathan Sidwell 14 Aug 2000 <[e-mail]>

// We failed to diagnose when a class friend declaration did not use an
// elaborated type specifier.

struct Y;
struct Z;
struct X
{
  friend class Z;
  friend Y;         // ERROR - friend must use aggr tag
};