submodule--helper: use correct display path helper

Replace a chunk of code in update_submodule() with an equivalent
do_get_submodule_displaypath() invocation. This is already tested by
t/t7406-submodule-update.sh:'submodule update --init --recursive from
subdirectory', so no tests are added.

The two are equivalent because:

- Exactly one of recursive_prefix|prefix is non-NULL at a time; prefix
  is set at the superproject level, and recursive_prefix is set when
  recursing into submodules. There is also a BUG() statement in
  get_submodule_displaypath() that asserts that both cannot be non-NULL.

- In get_submodule_displaypath(), get_super_prefix() always returns NULL
  because "--super-prefix" is never passed. Thus calling it is
  equivalent to calling do_get_submodule_displaypath() with super_prefix
  = NULL.

Therefore:

- When recursive_prefix is non-NULL, prefix is NULL, and thus
  get_submodule_displaypath() just returns prefixed_path. This is
  identical to calling do_get_submodule_displaypath() with super_prefix
  = recursive_prefix because the return value is still the concatenation
  of recursive_prefix + update_data->sm_path.

- When prefix is non-NULL, prefixed_path = update_data->sm_path. Thus
  calling get_submodule_displaypath() with prefixed_path is equivalent
  to calling do_get_submodule_displaypath() with update_data->sm_path

Signed-off-by: Glen Choo <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: chooglen

builtin/submodule--helper.c

@@ -2464,19 +2464,11 @@ static void update_data_to_args(struct update_data *update_data, struct strvec *
 
 static int update_submodule(struct update_data *update_data)
 {
-	char *prefixed_path;
-
 	ensure_core_worktree(update_data->sm_path);
 
-	if (update_data->recursive_prefix)
-		prefixed_path = xstrfmt("%s%s", update_data->recursive_prefix,
-					update_data->sm_path);
-	else
-		prefixed_path = xstrdup(update_data->sm_path);
-
-	update_data->displaypath = get_submodule_displaypath(prefixed_path,
-							     update_data->prefix);
-	free(prefixed_path);
+	update_data->displaypath = do_get_submodule_displaypath(update_data->sm_path,
+								update_data->prefix,
+								update_data->recursive_prefix);
 
 	determine_submodule_update_strategy(the_repository, update_data->just_cloned,
 					    update_data->sm_path, update_data->update_default,