BKE Collection: Add new function to rebuild parent relationships.

It's not always possible to keep 'by hand' parent relationships valid in
collections hierarchy. Add functions to remake those
(re-using/factorizing code from `readfile.c` `lib_link_collection_data()`
function).

Can't stress again how painful it is to have those kind of backward
relationships in our data structures, those *always* end up being
serious issues to keep in sync... Should only be generated on the fly
when needed, period. :(

1 files changed, 3 insertions, 12 deletions

diff --git a/source/blender/blenloader/intern/readfile.c b/source/blender/blenloader/intern/readfile.c
index 5edba272cd4..de6e5a80912 100644
--- a/source/blender/blenloader/intern/readfile.c
+++ b/source/blender/blenloader/intern/readfile.c
@@ -6228,20 +6228,11 @@ static void lib_link_collection_data(FileData *fd, Library *lib, Collection *col
     }
   }
 
-  for (CollectionChild *child = collection->children.first, *child_next = NULL; child;
-       child = child_next) {
-    child_next = child->next;
+  for (CollectionChild *child = collection->children.first; child != NULL; child = child->next) {
     child->collection = newlibadr_us(fd, lib, child->collection);
-
-    if (child->collection == NULL || BKE_collection_find_cycle(collection, child->collection)) {
-      BLI_freelinkN(&collection->children, child);
-    }
-    else {
-      CollectionParent *cparent = MEM_callocN(sizeof(CollectionParent), "CollectionParent");
-      cparent->collection = collection;
-      BLI_addtail(&child->collection->parents, cparent);
-    }
   }
+
+  BKE_collection_parent_relations_rebuild(collection);
 }
 
 static void lib_link_collection(FileData *fd, Main *main)