DNA/RNA: add 'py_instance' for ID types

Avoid creating new Python instances
every time a scene, object, mesh .. etc are accessed.

Also resolves crashes T28724, T53530
although it's only valid for ID types, not modifiers vertices etc.

Back-ported from blender2.8 branch.

1 files changed, 12 insertions, 0 deletions

diff --git a/source/blender/makesrna/intern/rna_ID.c b/source/blender/makesrna/intern/rna_ID.c
index 9d42ba55ecc..9205e15671b 100644
--- a/source/blender/makesrna/intern/rna_ID.c
+++ b/source/blender/makesrna/intern/rna_ID.c
@@ -387,6 +387,14 @@ static void rna_ID_animation_data_free(ID *id, Main *bmain)
 	DAG_relations_tag_update(bmain);
 }
 
+#ifdef WITH_PYTHON
+void **rna_ID_instance(PointerRNA *ptr)
+{
+	ID *id = (ID *)ptr->data;
+	return &id->py_instance;
+}
+#endif
+
 static void rna_IDPArray_begin(CollectionPropertyIterator *iter, PointerRNA *ptr)
 {
 	IDProperty *prop = (IDProperty *)ptr->data;
@@ -1064,6 +1072,10 @@ static void rna_def_ID(BlenderRNA *brna)
 	                                "Tag the ID to update its display data, "
 	                                "e.g. when calling :class:`bpy.types.Scene.update`");
 	RNA_def_enum_flag(func, "refresh", update_flag_items, 0, "", "Type of updates to perform");
+
+#ifdef WITH_PYTHON
+	RNA_def_struct_register_funcs(srna, NULL, NULL, "rna_ID_instance");
+#endif
 }
 
 static void rna_def_library(BlenderRNA *brna)