unpack-trees: move checkout state into check_updates

The checkout state was introduced via 16da134b1f
(read-trees: refactor the unpack_trees() part, 2006-07-30). An attempt to
refactor the checkout state was done in b56aa5b268 (unpack-trees: pass
checkout state explicitly to check_updates(), 2016-09-13), but we can
go even further.

The `struct checkout state` is not used in unpack_trees apart from
initializing it, so move it into the function that makes use of it,
which is `check_updates`.

Signed-off-by: Stefan Beller <sbeller@google.com>
Reviewed-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

unpack-trees.c

@@ -218,14 +218,19 @@ static void unlink_entry(const struct cache_entry *ce)
 	schedule_dir_for_removal(ce->name, ce_namelen(ce));
 }
 
-static int check_updates(struct unpack_trees_options *o,
-			 const struct checkout *state)
+static int check_updates(struct unpack_trees_options *o)
 {
 	unsigned cnt = 0, total = 0;
+	int errs = 0;
 	struct progress *progress = NULL;
 	struct index_state *index = &o->result;
+	struct checkout state = CHECKOUT_INIT;
 	int i;
-	int errs = 0;
+
+	state.force = 1;
+	state.quiet = 1;
+	state.refresh_cache = 1;
+	state.istate = index;
 
 	if (o->update && o->verbose_update) {
 		for (total = cnt = 0; cnt < index->cache_nr; cnt++) {
@@ -240,7 +245,7 @@ static int check_updates(struct unpack_trees_options *o,
 	}
 
 	if (o->update)
-		git_attr_set_direction(GIT_ATTR_CHECKOUT, &o->result);
+		git_attr_set_direction(GIT_ATTR_CHECKOUT, index);
 	for (i = 0; i < index->cache_nr; i++) {
 		const struct cache_entry *ce = index->cache[i];
 
@@ -251,7 +256,7 @@ static int check_updates(struct unpack_trees_options *o,
 			continue;
 		}
 	}
-	remove_marked_cache_entries(&o->result);
+	remove_marked_cache_entries(index);
 	remove_scheduled_dirs();
 
 	for (i = 0; i < index->cache_nr; i++) {
@@ -264,7 +269,7 @@ static int check_updates(struct unpack_trees_options *o,
 			display_progress(progress, ++cnt);
 			ce->ce_flags &= ~CE_UPDATE;
 			if (o->update && !o->dry_run) {
-				errs |= checkout_entry(ce, state, NULL);
+				errs |= checkout_entry(ce, &state, NULL);
 			}
 		}
 	}
@@ -1094,14 +1099,9 @@ int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options
 	int i, ret;
 	static struct cache_entry *dfc;
 	struct exclude_list el;
-	struct checkout state = CHECKOUT_INIT;
 
 	if (len > MAX_UNPACK_TREES)
 		die("unpack_trees takes at most %d trees", MAX_UNPACK_TREES);
-	state.force = 1;
-	state.quiet = 1;
-	state.refresh_cache = 1;
-	state.istate = &o->result;
 
 	memset(&el, 0, sizeof(el));
 	if (!core_apply_sparse_checkout || !o->update)
@@ -1238,7 +1238,7 @@ int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options
 	}
 
 	o->src_index = NULL;
-	ret = check_updates(o, &state) ? (-2) : 0;
+	ret = check_updates(o) ? (-2) : 0;
 	if (o->dst_index) {
 		if (!ret) {
 			if (!o->result.cache_tree)