+/* Search whether an element is already in the list.
+ The list is assumed to be sorted with COMPAR.
+ Only list elements with indices >= START_INDEX and < END_INDEX are
+ considered; the implementation uses these bounds to minimize the number
+ of COMPAR invocations.
+ Return its position if found, or (size_t)(-1) if not present in the list.
+ If the list contains several copies of ELT, the position of the leftmost one
+ is returned. */
+extern size_t gl_sortedlist_indexof_from_to (gl_list_t list,
+ gl_listelement_compar_fn compar,
+ size_t start_index,
+ size_t end_index,
+ const void *elt);
+