list: fix unused var warning.

[ccan] / ccan / list / list.h

diff --git a/ccan/list/list.h b/ccan/list/list.h
index 4a18f02d9c90e6465781582f54996afd402f6ee6..faad86f5c736a3a53ed08c79e74f92c39086a810 100644 (file)
--- a/ccan/list/list.h
+++ b/ccan/list/list.h
@@ -279,6 +279,8 @@ static inline void list_del_from(struct list_head *h, struct list_node *n)
  * Example:
  *     struct child *first;
  *     first = list_top(&parent->children, struct child, list);
+ *     if (!first)
+ *             printf("Empty list!\n");
  */
 #define list_top(h, type, member)                                      \
        ((type *)list_top_((h), list_off_(type, member)))
@@ -301,6 +303,8 @@ static inline const void *list_top_(const struct list_head *h, size_t off)
  * Example:
  *     struct child *last;
  *     last = list_tail(&parent->children, struct child, list);
+ *     if (!last)
+ *             printf("Empty list!\n");
  */
 #define list_tail(h, type, member) \
        ((type *)list_tail_((h), list_off_(type, member)))