Fix T98136: Crash undoing "Make Library Override" in some cases.

The 'OVERRIDE_HIDDEN' extra collection would often be mistakenly added
to a linked collection, which is totally forbidden and guaranteed to
crash on undo/redo.

Reworked the code instantiating that extra collection in a more generic
and hopefully robust way now.

1 files changed, 16 insertions, 2 deletions

diff --git a/source/blender/blenkernel/intern/lib_override.c b/source/blender/blenkernel/intern/lib_override.c
index 9dc64365f0c..67df6b5527e 100644
--- a/source/blender/blenkernel/intern/lib_override.c
+++ b/source/blender/blenkernel/intern/lib_override.c
@@ -1105,8 +1105,8 @@ static void lib_override_library_create_post_process(Main *bmain,
             if (ID_REAL_USERS(ob_new) != 0) {
               continue;
             }
-            default_instantiating_collection = BKE_collection_add(
-                bmain, (Collection *)id_root, "OVERRIDE_HIDDEN");
+            default_instantiating_collection = BKE_id_new(bmain, ID_GR, "OVERRIDE_HIDDEN");
+            id_us_min(&default_instantiating_collection->id);
             /* Hide the collection from viewport and render. */
             default_instantiating_collection->flag |= COLLECTION_HIDE_VIEWPORT |
                                                       COLLECTION_HIDE_RENDER;
@@ -1140,6 +1140,20 @@ static void lib_override_library_create_post_process(Main *bmain,
     }
   }
 
+  if (id_root != NULL && !ELEM(default_instantiating_collection, NULL, scene->master_collection)) {
+    ID *id_ref = id_root->newid != NULL ? id_root->newid : id_root;
+    switch (GS(id_ref->name)) {
+      case ID_GR:
+        BKE_collection_add_from_collection(
+            bmain, scene, (Collection *)id_ref, default_instantiating_collection);
+        break;
+      default:
+        /* Add to master collection. */
+        BKE_collection_add_from_collection(bmain, scene, NULL, default_instantiating_collection);
+        break;
+    }
+  }
+
   BLI_gset_free(all_objects_in_scene, NULL);
 }