1struct priv;
2typedef struct priv* priv_ptr;
3
4#define NULL (void*)0
5
6struct S
7{
8  priv_ptr p;
9};
10
11typedef struct S* s_ptr;
12
13void
14foo(s_ptr, int a);
15
16s_ptr
17bar(s_ptr, char a);
18
19void
20baz(s_ptr);
21