Cleanup: Main `foreach ID` code: Remove `MAX_LIBARRAY` and improve comments.

The `MAX_LIBARRAY` define was an annoying doublon to the `INDEX_ID_MAX` enum value
now defined in `DNA_ID.h`, and it is no more useful.

And comments were somewhat outdated. Also added an explanation about
chosen order for the `INDEX_ID_<IDTYPE>` order.

8 files changed, 27 insertions, 28 deletions

diff --git a/source/blender/blenkernel/intern/blendfile.c b/source/blender/blenkernel/intern/blendfile.c
index 32710c4fa60..101f4b7caf6 100644
--- a/source/blender/blenkernel/intern/blendfile.c
+++ b/source/blender/blenkernel/intern/blendfile.c
@@ -865,7 +865,7 @@ bool BKE_blendfile_write_partial(Main *bmain_src,
                                  ReportList *reports)
 {
   Main *bmain_dst = MEM_callocN(sizeof(Main), "copybuffer");
-  ListBase *lbarray_dst[MAX_LIBARRAY], *lbarray_src[MAX_LIBARRAY];
+  ListBase *lbarray_dst[INDEX_ID_MAX], *lbarray_src[INDEX_ID_MAX];
   int a, retval;
 
   void *path_list_backup = NULL;
diff --git a/source/blender/blenkernel/intern/bpath.c b/source/blender/blenkernel/intern/bpath.c
index 2ad0ac950d0..47427beccba 100644
--- a/source/blender/blenkernel/intern/bpath.c
+++ b/source/blender/blenkernel/intern/bpath.c
@@ -783,7 +783,7 @@ void BKE_bpath_traverse_main(Main *bmain,
                              const int flag,
                              void *bpath_user_data)
 {
-  ListBase *lbarray[MAX_LIBARRAY];
+  ListBase *lbarray[INDEX_ID_MAX];
   int a = set_listbasepointers(bmain, lbarray);
   while (a--) {
     BKE_bpath_traverse_id_list(bmain, lbarray[a], visit_cb, flag, bpath_user_data);
diff --git a/source/blender/blenkernel/intern/idtype.c b/source/blender/blenkernel/intern/idtype.c
index 1889d1c4eb0..fee70922570 100644
--- a/source/blender/blenkernel/intern/idtype.c
+++ b/source/blender/blenkernel/intern/idtype.c
@@ -63,7 +63,7 @@ bool BKE_idtype_cache_key_cmp(const void *key_a_v, const void *key_b_v)
          (key_a->offset_in_ID != key_b->offset_in_ID) || (key_a->cache_v != key_b->cache_v);
 }
 
-static IDTypeInfo *id_types[MAX_LIBARRAY] = {NULL};
+static IDTypeInfo *id_types[INDEX_ID_MAX] = {NULL};
 
 static void id_type_init(void)
 {
diff --git a/source/blender/blenkernel/intern/lib_id.c b/source/blender/blenkernel/intern/lib_id.c
index 54c2f5f5565..a511c1f9c4c 100644
--- a/source/blender/blenkernel/intern/lib_id.c
+++ b/source/blender/blenkernel/intern/lib_id.c
@@ -916,7 +916,7 @@ void BKE_main_id_tag_idcode(struct Main *mainvar,
  */
 void BKE_main_id_tag_all(struct Main *mainvar, const int tag, const bool value)
 {
-  ListBase *lbarray[MAX_LIBARRAY];
+  ListBase *lbarray[INDEX_ID_MAX];
   int a;
 
   a = set_listbasepointers(mainvar, lbarray);
@@ -949,7 +949,7 @@ void BKE_main_id_flag_listbase(ListBase *lb, const int flag, const bool value)
  */
 void BKE_main_id_flag_all(Main *bmain, const int flag, const bool value)
 {
-  ListBase *lbarray[MAX_LIBARRAY];
+  ListBase *lbarray[INDEX_ID_MAX];
   int a;
   a = set_listbasepointers(bmain, lbarray);
   while (a--) {
@@ -1870,7 +1870,7 @@ void BKE_library_make_local(Main *bmain,
                             const bool untagged_only,
                             const bool set_fake)
 {
-  ListBase *lbarray[MAX_LIBARRAY];
+  ListBase *lbarray[INDEX_ID_MAX];
 
   LinkNode *todo_ids = NULL;
   LinkNode *copied_ids = NULL;
diff --git a/source/blender/blenkernel/intern/lib_id_delete.c b/source/blender/blenkernel/intern/lib_id_delete.c
index 7c5032c97f4..1d7f89e1e8d 100644
--- a/source/blender/blenkernel/intern/lib_id_delete.c
+++ b/source/blender/blenkernel/intern/lib_id_delete.c
@@ -240,7 +240,7 @@ void BKE_id_free_us(Main *bmain, void *idv) /* test users */
 static size_t id_delete(Main *bmain, const bool do_tagged_deletion)
 {
   const int tag = LIB_TAG_DOIT;
-  ListBase *lbarray[MAX_LIBARRAY];
+  ListBase *lbarray[INDEX_ID_MAX];
   Link dummy_link = {0};
   int base_count, i;
 
diff --git a/source/blender/blenkernel/intern/lib_query.c b/source/blender/blenkernel/intern/lib_query.c
index 796bc3dc3d0..acd0c10040c 100644
--- a/source/blender/blenkernel/intern/lib_query.c
+++ b/source/blender/blenkernel/intern/lib_query.c
@@ -440,7 +440,7 @@ bool BKE_library_id_can_use_idtype(ID *id_owner, const short id_type_used)
 typedef struct IDUsersIter {
   ID *id;
 
-  ListBase *lb_array[MAX_LIBARRAY];
+  ListBase *lb_array[INDEX_ID_MAX];
   int lb_idx;
 
   ID *curr_id;
@@ -514,7 +514,7 @@ int BKE_library_ID_use_ID(ID *id_user, ID *id_used)
 static bool library_ID_is_used(Main *bmain, void *idv, const bool check_linked)
 {
   IDUsersIter iter;
-  ListBase *lb_array[MAX_LIBARRAY];
+  ListBase *lb_array[INDEX_ID_MAX];
   ID *id = idv;
   int i = set_listbasepointers(bmain, lb_array);
   bool is_defined = false;
@@ -567,7 +567,7 @@ bool BKE_library_ID_is_indirectly_used(Main *bmain, void *idv)
 void BKE_library_ID_test_usages(Main *bmain, void *idv, bool *is_used_local, bool *is_used_linked)
 {
   IDUsersIter iter;
-  ListBase *lb_array[MAX_LIBARRAY];
+  ListBase *lb_array[INDEX_ID_MAX];
   ID *id = idv;
   int i = set_listbasepointers(bmain, lb_array);
   bool is_defined = false;
@@ -805,7 +805,7 @@ void BKE_library_unused_linked_data_set_tag(Main *bmain, const bool do_init_tag)
  */
 void BKE_library_indirectly_used_data_tag_clear(Main *bmain)
 {
-  ListBase *lb_array[MAX_LIBARRAY];
+  ListBase *lb_array[INDEX_ID_MAX];
 
   bool do_loop = true;
   while (do_loop) {
diff --git a/source/blender/blenkernel/intern/main.c b/source/blender/blenkernel/intern/main.c
index 6f94b3355fa..ead1c5bf721 100644
--- a/source/blender/blenkernel/intern/main.c
+++ b/source/blender/blenkernel/intern/main.c
@@ -53,7 +53,7 @@ Main *BKE_main_new(void)
 void BKE_main_free(Main *mainvar)
 {
   /* also call when reading a file, erase all, etc */
-  ListBase *lbarray[MAX_LIBARRAY];
+  ListBase *lbarray[INDEX_ID_MAX];
   int a;
 
   /* Since we are removing whole main, no need to bother 'properly'
@@ -532,18 +532,17 @@ ListBase *which_libbase(Main *bmain, short type)
 }
 
 /**
- * puts into array *lb pointers to all the #ListBase structs in main,
- * and returns the number of them as the function result. This is useful for
- * generic traversal of all the blocks in a Main (by traversing all the
- * lists in turn), without worrying about block types.
+ * Put the pointers to all the #ListBase structs in given `bmain` into the `*lb[INDEX_ID_MAX]`
+ * array, and return the number of those for convinience.
  *
- * \note #MAX_LIBARRAY define should match this code */
-int set_listbasepointers(Main *bmain, ListBase **lb)
+ * This is useful for generic traversal of all the blocks in a #Main (by traversing all the lists
+ * in turn), without worrying about block types.
+ *
+ * \note The order of each ID type #ListBase in the array is determined by the `INDEX_ID_<IDTYPE>`
+ * enum definitions in `DNA_ID.h`. See also the #FOREACH_MAIN_ID_BEGIN macro in `BKE_main.h`
+ */
+int set_listbasepointers(Main *bmain, ListBase *lb[INDEX_ID_MAX])
 {
-  /* BACKWARDS! also watch order of free-ing! (mesh<->mat), first items freed last.
-   * This is important because freeing data decreases user-counts of other data-blocks,
-   * if this data is its self freed it can crash. */
-
   /* Libraries may be accessed from pretty much any other ID. */
   lb[INDEX_ID_LI] = &(bmain->libraries);
 
@@ -606,5 +605,5 @@ int set_listbasepointers(Main *bmain, ListBase **lb)
 
   lb[INDEX_ID_NULL] = NULL;
 
-  return (MAX_LIBARRAY - 1);
+  return (INDEX_ID_MAX - 1);
 }
diff --git a/source/blender/blenkernel/intern/main_idmap.c b/source/blender/blenkernel/intern/main_idmap.c
index 21f5e9c6fb2..1d362db4432 100644
--- a/source/blender/blenkernel/intern/main_idmap.c
+++ b/source/blender/blenkernel/intern/main_idmap.c
@@ -66,7 +66,7 @@ struct IDNameLib_TypeMap {
  * Opaque structure, external API users only see this.
  */
 struct IDNameLib_Map {
-  struct IDNameLib_TypeMap type_maps[MAX_LIBARRAY];
+  struct IDNameLib_TypeMap type_maps[INDEX_ID_MAX];
   struct GHash *uuid_map;
   struct Main *bmain;
   struct GSet *valid_id_pointers;
@@ -77,7 +77,7 @@ static struct IDNameLib_TypeMap *main_idmap_from_idcode(struct IDNameLib_Map *id
                                                         short id_type)
 {
   if (id_map->idmap_types & MAIN_IDMAP_TYPE_NAME) {
-    for (int i = 0; i < MAX_LIBARRAY; i++) {
+    for (int i = 0; i < INDEX_ID_MAX; i++) {
       if (id_map->type_maps[i].id_type == id_type) {
         return &id_map->type_maps[i];
       }
@@ -108,13 +108,13 @@ struct IDNameLib_Map *BKE_main_idmap_create(struct Main *bmain,
   id_map->idmap_types = idmap_types;
 
   int index = 0;
-  while (index < MAX_LIBARRAY) {
+  while (index < INDEX_ID_MAX) {
     struct IDNameLib_TypeMap *type_map = &id_map->type_maps[index];
     type_map->map = NULL;
     type_map->id_type = BKE_idtype_idcode_iter_step(&index);
     BLI_assert(type_map->id_type != 0);
   }
-  BLI_assert(index == MAX_LIBARRAY);
+  BLI_assert(index == INDEX_ID_MAX);
 
   if (idmap_types & MAIN_IDMAP_TYPE_UUID) {
     ID *id;
@@ -231,7 +231,7 @@ void BKE_main_idmap_destroy(struct IDNameLib_Map *id_map)
 {
   if (id_map->idmap_types & MAIN_IDMAP_TYPE_NAME) {
     struct IDNameLib_TypeMap *type_map = id_map->type_maps;
-    for (int i = 0; i < MAX_LIBARRAY; i++, type_map++) {
+    for (int i = 0; i < INDEX_ID_MAX; i++, type_map++) {
       if (type_map->map) {
         BLI_ghash_free(type_map->map, NULL, NULL);
         type_map->map = NULL;