-int threeway_merge(struct cache_entry **stages, struct unpack_trees_options *o);
-int twoway_merge(struct cache_entry **src, struct unpack_trees_options *o);
-int bind_merge(struct cache_entry **src, struct unpack_trees_options *o);
-int oneway_merge(struct cache_entry **src, struct unpack_trees_options *o);
+int threeway_merge(const struct cache_entry * const *stages,
+ struct unpack_trees_options *o);
+int twoway_merge(const struct cache_entry * const *src,
+ struct unpack_trees_options *o);
+int bind_merge(const struct cache_entry * const *src,
+ struct unpack_trees_options *o);
+int oneway_merge(const struct cache_entry * const *src,
+ struct unpack_trees_options *o);