-/* Red-black tree that maps SHA1 message digests of security descriptors to
- * security IDs, which are themselves indices into the table of security
- * descriptors in the 'struct wim_security_data'. */
+struct wim_security_data;
+struct avl_tree_node;
+
+/* Map from SHA1 message digests of security descriptors to security IDs, which
+ * are themselves indices into the table of security descriptors in the 'struct
+ * wim_security_data'. */