Fix (studio-reported) liboverrides potential infinite loop in hierarchy root doversion.

Drivers make it way too easy to create dependenciy loops between IDs, so
need to use the same trick as in other dependency-following code in this
file to prevent those infinite loops.

hard to predict for sure how bad of a hierarchy root this can end up
producing, but in general cases think this should be OK.

1 files changed, 14 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/lib_override.c b/source/blender/blenkernel/intern/lib_override.c
index e42320fa2ca..f53780d1cbb 100644
--- a/source/blender/blenkernel/intern/lib_override.c
+++ b/source/blender/blenkernel/intern/lib_override.c
@@ -1102,6 +1102,16 @@ static ID *lib_override_root_find(Main *bmain, ID *id, const int curr_level, int
   MainIDRelationsEntry *entry = BLI_ghash_lookup(bmain->relations->relations_from_pointers, id);
   BLI_assert(entry != NULL);
 
+  if (entry->tags & MAINIDRELATIONS_ENTRY_TAGS_PROCESSED && ID_IS_OVERRIDE_LIBRARY_REAL(id)) {
+    /* This ID has already been processed. */
+    BLI_assert(id->override_library != NULL);
+    *r_best_level = curr_level;
+    return id->override_library->hierarchy_root;
+  }
+  /* This way we won't process again that ID, should we encounter it again through another
+   * relationship hierarchy. */
+  entry->tags |= MAINIDRELATIONS_ENTRY_TAGS_PROCESSED;
+
   int best_level_candidate = curr_level;
   ID *best_root_id_candidate = id;
 
@@ -1130,6 +1140,8 @@ static ID *lib_override_root_find(Main *bmain, ID *id, const int curr_level, int
     }
   }
 
+  BLI_assert(best_root_id_candidate != NULL);
+
   *r_best_level = best_level_candidate;
   return best_root_id_candidate;
 }
@@ -1244,6 +1256,8 @@ void BKE_lib_override_library_main_hierarchy_root_ensure(Main *bmain)
       continue;
     }
 
+    BKE_main_relations_tag_set(bmain, MAINIDRELATIONS_ENTRY_TAGS_PROCESSED, false);
+
     int best_level = 0;
     ID *id_root = lib_override_root_find(bmain, id, best_level, &best_level);