Fix T86170: Memory leak clearing the Python instance for COW id data

As Python can access COW ID's, ensure it's instance is kept on update.

This could happen when the "Use Self" argument was enabled for a driver.

1 files changed, 5 insertions, 0 deletions

diff --git a/source/blender/depsgraph/intern/eval/deg_eval_runtime_backup.h b/source/blender/depsgraph/intern/eval/deg_eval_runtime_backup.h
index c6249c83daa..0629dbe62b4 100644
--- a/source/blender/depsgraph/intern/eval/deg_eval_runtime_backup.h
+++ b/source/blender/depsgraph/intern/eval/deg_eval_runtime_backup.h
@@ -58,6 +58,11 @@ class RuntimeBackup {
    * copy-on-write mechanism. */
   bool have_backup;
 
+  /* Struct members of the ID pointer. */
+  struct {
+    void *py_instance;
+  } id_data;
+
   AnimationBackup animation_backup;
   SceneBackup scene_backup;
   SoundBackup sound_backup;