1struct tree_decl
2{
3  unsigned in_system_header_flag:1;
4};
5union tree_node
6{
7  struct tree_decl decl;
8};
9typedef union tree_node *tree;
10static int
11redeclaration_error_message (olddecl)
12     tree olddecl;
13{
14  if (({olddecl;})->decl.in_system_header_flag)
15    ;
16}
17