[PATCH 05/10] dir.[ch]: make DIR_INIT mandatory

The dir_init() initializer has been documented as being mandatory
since eceba532141 (dir: fix problematic API to avoid memory leaks,
2020-08-18), but both it and my ce93a4c6127 (dir.[ch]: replace
dir_init() with DIR_INIT, 2021-07-01) managed to miss this callsite in
"add-interactive.c" added before those two commits in
ab1e1cccaf6 (built-in add -i: re-implement `add-untracked` in C,
2019-11-29).

In addition my change to remove dir_init() neglected to update this
documentation. Let's use "must be initialized with" in reference to
"DIR_INIT". We have one lazy initialization which pre-dates
eceba532141 in dir.c. Adjusting this callsite is a prerequisite for
removing it in favor of trusting the macro to initialize the "struct
dir_struct" correctly.

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
---
 add-interactive.c | 2 +-
 dir.h             | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/add-interactive.c b/add-interactive.c
index 6498ae196f1..27daea8d1b3 100644
--- a/add-interactive.c
+++ b/add-interactive.c

@@ -826,7 +826,7 @@ static int get_untracked_files(struct repository *r,
 			       struct prefix_item_list *files,
 			       const struct pathspec *ps)
 {
-	struct dir_struct dir = { 0 };
+	struct dir_struct dir = DIR_INIT;
 	size_t i;
 	struct strbuf buf = STRBUF_INIT;
 

diff --git a/dir.h b/dir.h
index 83f46c0fb4c..ff3b4a7f602 100644
--- a/dir.h
+++ b/dir.h

@@ -19,7 +19,7 @@
  * CE_SKIP_WORKTREE marked. If you want to exclude files, make sure you have
  * loaded the index first.
  *
- * - Prepare `struct dir_struct dir` using `dir_init()` function.
+ * - The `struct dir_struct dir` must be initialized with `DIR_INIT`.
  *
  * - To add single exclude pattern, call `add_pattern_list()` and then
  *   `add_pattern()`.

-- 
2.33.0.1404.g83021034c5d