Fix libOverride resync issues in some corner-cases.

This commit fixes two different issues:
* In some cases, when an object was added to a sub-collection and used
  into a different subcollection, and the root common collection would
  not need to be resynced, it would end up creating multiple overrides
  of the new object. This was affecting both normal and recursive
  resync.
* In recurisve resync case, the barrier code to define what is part or
  not of a override group/hierarchy was wrong.

Note that the current solution for the first issue is sub-optimal (it
goes back to the root of the override hierarchy and resync the whole
thing), a better solution is TODO for now.

1 files changed, 90 insertions, 16 deletions

diff --git a/source/blender/blenkernel/intern/lib_override.c b/source/blender/blenkernel/intern/lib_override.c
index 83bd2b6abb7..5af37aeb13e 100644
--- a/source/blender/blenkernel/intern/lib_override.c
+++ b/source/blender/blenkernel/intern/lib_override.c
@@ -428,7 +428,8 @@ bool BKE_lib_override_library_create_from_tag(Main *bmain,
 
         /* If other ID is a linked one, but not from the same library as our reference, then we
          * consider we should also remap it, as part of recursive resync. */
-        if ((other_id->tag & LIB_TAG_DOIT) != 0 && other_id->lib != reference_id->lib) {
+        if ((other_id->tag & LIB_TAG_DOIT) != 0 && other_id->lib != reference_id->lib &&
+            other_id != local_id) {
           BKE_libblock_relink_ex(bmain,
                                  other_id,
                                  reference_id,
@@ -468,6 +469,8 @@ typedef struct LibOverrideGroupTagData {
   ID *id_root;
   uint tag;
   uint missing_tag;
+  /* Whether we are looping on override data, or their references (linked) one. */
+  bool is_override;
 } LibOverrideGroupTagData;
 
 /* Tag all IDs in dependency relationships within an override hierarchy/group.
@@ -480,6 +483,7 @@ static bool lib_override_hierarchy_dependencies_recursive_tag(LibOverrideGroupTa
 {
   Main *bmain = data->bmain;
   ID *id = data->id_root;
+  const bool is_override = data->is_override;
 
   MainIDRelationsEntry *entry = BLI_ghash_lookup(bmain->relations->relations_from_pointers, id);
   BLI_assert(entry != NULL);
@@ -501,16 +505,16 @@ static bool lib_override_hierarchy_dependencies_recursive_tag(LibOverrideGroupTa
     }
     /* We only consider IDs from the same library. */
     ID *to_id = *to_id_entry->id_pointer.to;
-    if (!ID_IS_LINKED(to_id) && !ID_IS_OVERRIDE_LIBRARY(to_id)) {
-      /* Pure local data is a barrier of dependency in override cases. */
+    if (to_id == NULL || to_id->lib != id->lib ||
+        (is_override && !ID_IS_OVERRIDE_LIBRARY(to_id))) {
+      /* IDs from different libraries, or non-override IDs in case we are processing overrides, are
+       * both barriers of dependency. */
       continue;
     }
-    if (to_id != NULL && to_id->lib == id->lib) {
-      LibOverrideGroupTagData sub_data = *data;
-      sub_data.id_root = to_id;
-      if (lib_override_hierarchy_dependencies_recursive_tag(&sub_data)) {
-        id->tag |= data->tag;
-      }
+    LibOverrideGroupTagData sub_data = *data;
+    sub_data.id_root = to_id;
+    if (lib_override_hierarchy_dependencies_recursive_tag(&sub_data)) {
+      id->tag |= data->tag;
     }
   }
 
@@ -522,6 +526,7 @@ static void lib_override_linked_group_tag_recursive(LibOverrideGroupTagData *dat
   Main *bmain = data->bmain;
   ID *id_owner = data->id_root;
   BLI_assert(ID_IS_LINKED(id_owner));
+  BLI_assert(!data->is_override);
   const uint tag = data->tag;
   const uint missing_tag = data->missing_tag;
 
@@ -587,6 +592,7 @@ static void lib_override_linked_group_tag(LibOverrideGroupTagData *data)
 {
   Main *bmain = data->bmain;
   ID *id_root = data->id_root;
+  BLI_assert(!data->is_override);
 
   if ((id_root->tag & LIB_TAG_MISSING)) {
     id_root->tag |= data->missing_tag;
@@ -618,6 +624,7 @@ static void lib_override_local_group_tag_recursive(LibOverrideGroupTagData *data
   Main *bmain = data->bmain;
   ID *id_owner = data->id_root;
   BLI_assert(ID_IS_OVERRIDE_LIBRARY(id_owner));
+  BLI_assert(data->is_override);
   const uint tag = data->tag;
   const uint missing_tag = data->missing_tag;
 
@@ -674,6 +681,7 @@ static void lib_override_local_group_tag(LibOverrideGroupTagData *data)
 {
   ID *id_root = data->id_root;
   BLI_assert(ID_IS_OVERRIDE_LIBRARY_REAL(id_root));
+  BLI_assert(data->is_override);
 
   if ((id_root->override_library->reference->tag & LIB_TAG_MISSING)) {
     id_root->tag |= data->missing_tag;
@@ -689,8 +697,11 @@ static void lib_override_local_group_tag(LibOverrideGroupTagData *data)
 static bool lib_override_library_create_do(Main *bmain, ID *id_root)
 {
   BKE_main_relations_create(bmain, 0);
-  LibOverrideGroupTagData data = {
-      .bmain = bmain, .id_root = id_root, .tag = LIB_TAG_DOIT, .missing_tag = LIB_TAG_MISSING};
+  LibOverrideGroupTagData data = {.bmain = bmain,
+                                  .id_root = id_root,
+                                  .tag = LIB_TAG_DOIT,
+                                  .missing_tag = LIB_TAG_MISSING,
+                                  .is_override = false};
   lib_override_linked_group_tag(&data);
 
   BKE_main_relations_tag_set(bmain, MAINIDRELATIONS_ENTRY_TAGS_PROCESSED, false);
@@ -941,12 +952,16 @@ bool BKE_lib_override_library_resync(Main *bmain,
   ID *id_root_reference = id_root->override_library->reference;
 
   BKE_main_relations_create(bmain, 0);
-  LibOverrideGroupTagData data = {
-      .bmain = bmain, .id_root = id_root, .tag = LIB_TAG_DOIT, .missing_tag = LIB_TAG_MISSING};
+  LibOverrideGroupTagData data = {.bmain = bmain,
+                                  .id_root = id_root,
+                                  .tag = LIB_TAG_DOIT,
+                                  .missing_tag = LIB_TAG_MISSING,
+                                  .is_override = true};
   lib_override_local_group_tag(&data);
 
   BKE_main_relations_tag_set(bmain, MAINIDRELATIONS_ENTRY_TAGS_PROCESSED, false);
   data.id_root = id_root_reference;
+  data.is_override = false;
   lib_override_linked_group_tag(&data);
 
   BKE_main_relations_tag_set(bmain, MAINIDRELATIONS_ENTRY_TAGS_PROCESSED, false);
@@ -1284,6 +1299,58 @@ bool BKE_lib_override_library_resync(Main *bmain,
   return success;
 }
 
+/* Ensures parent collection (or objects) in the same override group are also tagged for resync.
+ *
+ * This is needed since otherwise, some (new) ID added in one sub-collection might be used in
+ * another unrelated sub-collection, if 'root' collection is not resynced separated resync of those
+ * sub-collections would be unaware that this is the same ID, and would re-generate several
+ * overrides for it.
+ *
+ * TODO: This is a sub-optimal, simple solution. At some point, we should rather find a way to
+ * resync a set of 'sub-roots' overrides, instead of having to 'go back' to the real root and
+ * resync the whole hierarchy. */
+static ID *lib_override_library_main_resync_find_root_recurse(ID *id, int *level)
+{
+  (*level)++;
+  ID *return_id = id;
+
+  switch (GS(id->name)) {
+    case ID_GR: {
+      /* Find the highest valid collection in the parenting hierarchy.
+       * Note that in practice, in any decent common case there is only one well defined root
+       * collection anyway. */
+      int max_level = *level;
+      Collection *collection = (Collection *)id;
+      LISTBASE_FOREACH (CollectionParent *, collection_parent_iter, &collection->parents) {
+        Collection *collection_parent = collection_parent_iter->collection;
+        if (ID_IS_OVERRIDE_LIBRARY_REAL(collection_parent) &&
+            collection_parent->id.lib == id->lib) {
+          int tmp_level = *level;
+          ID *tmp_id = lib_override_library_main_resync_find_root_recurse(&collection_parent->id,
+                                                                          &tmp_level);
+          if (tmp_level > max_level) {
+            max_level = tmp_level;
+            return_id = tmp_id;
+          }
+        }
+      }
+      break;
+    }
+    case ID_OB: {
+      Object *object = (Object *)id;
+      if (object->parent != NULL && ID_IS_OVERRIDE_LIBRARY_REAL(object->parent) &&
+          object->parent->id.lib == id->lib) {
+        return_id = lib_override_library_main_resync_find_root_recurse(&object->parent->id, level);
+      }
+      break;
+    }
+    default:
+      break;
+  }
+
+  return return_id;
+}
+
 /* Ensure resync of all overrides at one level of indirect usage.
  *
  * We need to handle each level independently, since an override at level n may be affected by
@@ -1319,7 +1386,8 @@ static void lib_override_library_main_resync_on_library_indirect_level(
     LibOverrideGroupTagData data = {.bmain = bmain,
                                     .id_root = id->override_library->reference,
                                     .tag = LIB_TAG_DOIT,
-                                    .missing_tag = LIB_TAG_MISSING};
+                                    .missing_tag = LIB_TAG_MISSING,
+                                    .is_override = false};
     lib_override_linked_group_tag(&data);
     BKE_main_relations_tag_set(bmain, MAINIDRELATIONS_ENTRY_TAGS_PROCESSED, false);
     lib_override_hierarchy_dependencies_recursive_tag(&data);
@@ -1403,6 +1471,9 @@ static void lib_override_library_main_resync_on_library_indirect_level(
             (!ID_IS_LINKED(id) && library_indirect_level != 0)) {
           continue;
         }
+
+        int level = 0;
+        id = lib_override_library_main_resync_find_root_recurse(id, &level);
         BLI_assert(ID_IS_OVERRIDE_LIBRARY_REAL(id));
         do_continue = true;
 
@@ -1557,8 +1628,11 @@ void BKE_lib_override_library_delete(Main *bmain, ID *id_root)
 
   /* Tag all library overrides in the chains of dependencies from the given root one. */
   BKE_main_relations_create(bmain, 0);
-  LibOverrideGroupTagData data = {
-      .bmain = bmain, .id_root = id_root, .tag = LIB_TAG_DOIT, .missing_tag = LIB_TAG_MISSING};
+  LibOverrideGroupTagData data = {.bmain = bmain,
+                                  .id_root = id_root,
+                                  .tag = LIB_TAG_DOIT,
+                                  .missing_tag = LIB_TAG_MISSING,
+                                  .is_override = true};
   lib_override_local_group_tag(&data);
 
   BKE_main_relations_free(bmain);