cache-tree API: remove redundant update_main_cache_tree()

Remove the redundant update_main_cache_tree() function, and make its
users use cache_tree_update() instead.

The behavior of populating the "the_index.cache_tree" if it wasn't
present already was needed when this function was introduced in [1],
but it hasn't been needed since [2]; The "cache_tree_update()" will
now lazy-allocate, so there's no need for the wrapper.

1. 996277c520 (Refactor cache_tree_update idiom from commit,
   2011-12-06)
2. fb0882648e (cache-tree: clean up cache_tree_update(), 2021-01-23)

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/commit.c

@@ -414,7 +414,7 @@ static const char *prepare_index(const char **argv, const char *prefix,
 		discard_index(&the_index);
 		read_index_from(&the_index, get_lock_file_path(&index_lock),
 				get_git_dir());
-		if (update_main_cache_tree(WRITE_TREE_SILENT) == 0) {
+		if (cache_tree_update(&the_index, WRITE_TREE_SILENT) == 0) {
 			if (reopen_lock_file(&index_lock) < 0)
 				die(_("unable to write index file"));
 			if (write_locked_index(&the_index, &index_lock, 0))
@@ -444,7 +444,7 @@ static const char *prepare_index(const char **argv, const char *prefix,
 				       LOCK_DIE_ON_ERROR);
 		add_files_to_cache(also ? prefix : NULL, &pathspec, 0);
 		refresh_cache_or_die(refresh_flags);
-		update_main_cache_tree(WRITE_TREE_SILENT);
+		cache_tree_update(&the_index, WRITE_TREE_SILENT);
 		if (write_locked_index(&the_index, &index_lock, 0))
 			die(_("unable to write new_index file"));
 		commit_style = COMMIT_NORMAL;
@@ -467,7 +467,7 @@ static const char *prepare_index(const char **argv, const char *prefix,
 		refresh_cache_or_die(refresh_flags);
 		if (the_index.cache_changed
 		    || !cache_tree_fully_valid(the_index.cache_tree))
-			update_main_cache_tree(WRITE_TREE_SILENT);
+			cache_tree_update(&the_index, WRITE_TREE_SILENT);
 		if (write_locked_index(&the_index, &index_lock,
 				       COMMIT_LOCK | SKIP_IF_UNCHANGED))
 			die(_("unable to write new_index file"));
@@ -516,7 +516,7 @@ static const char *prepare_index(const char **argv, const char *prefix,
 	repo_hold_locked_index(the_repository, &index_lock, LOCK_DIE_ON_ERROR);
 	add_remove_files(&partial);
 	refresh_index(&the_index, REFRESH_QUIET, NULL, NULL, NULL);
-	update_main_cache_tree(WRITE_TREE_SILENT);
+	cache_tree_update(&the_index, WRITE_TREE_SILENT);
 	if (write_locked_index(&the_index, &index_lock, 0))
 		die(_("unable to write new_index file"));
 
@@ -1079,7 +1079,7 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
 	}
 	read_index_from(&the_index, index_file, get_git_dir());
 
-	if (update_main_cache_tree(0)) {
+	if (cache_tree_update(&the_index, 0)) {
 		error(_("Error building trees"));
 		return 0;
 	}

cache-tree.h

@@ -53,14 +53,4 @@ int write_index_as_tree(struct object_id *oid, struct index_state *index_state,
 void prime_cache_tree(struct repository *, struct index_state *, struct tree *);
 
 int cache_tree_matches_traversal(struct cache_tree *, struct name_entry *ent, struct traverse_info *info);
-
-#ifdef USE_THE_INDEX_COMPATIBILITY_MACROS
-static inline int update_main_cache_tree(int flags)
-{
-	if (!the_index.cache_tree)
-		the_index.cache_tree = cache_tree();
-	return cache_tree_update(&the_index, flags);
-}
-#endif
-
 #endif

contrib/coccinelle/index-compatibility.cocci

@@ -94,6 +94,9 @@ identifier ACT = active_cache_tree;
 |
 - cache_name_pos
 + index_name_pos
+|
+- update_main_cache_tree
++ cache_tree_update
 )
   (
 + &the_index,