1  union R { int c; union R *p; };
       2  extern union R *w[];
       3  typedef struct { int t; } T;
       4  typedef struct { void *u; } U;
       5  union R *fn1 (void);
       6  void fn2 (int, const char *, union R *);
       7  void fn3 (void);
       8  int fn4 (union R *);
       9  void foo (U *x);