Fix T86332: Error using lambda in annotations in Python 3.10

Callbacks used in `bpy.props` didn't hold a references to the functions
they used.

While this has been the case since early 2.5x it didn't cause any
problems as long as the class held a reference.

With Python 3.10 or when using `from __future__ import annotations`,
the annotations are no longer owned by the class once evaluated.

Resolve this by holding a reference in the module, which now supports
traverse & clear callbacks so the objects are visible to Python's
garbage collector.

Also refactor storage of Python data, moving from an array into a struct.

1 files changed, 17 insertions, 6 deletions

diff --git a/source/blender/makesrna/intern/rna_define.c b/source/blender/makesrna/intern/rna_define.c
index 5e188285e39..019823a7de3 100644
--- a/source/blender/makesrna/intern/rna_define.c
+++ b/source/blender/makesrna/intern/rna_define.c
@@ -3305,12 +3305,6 @@ void RNA_def_property_enum_funcs_runtime(PropertyRNA *prop,
   }
 }
 
-void RNA_def_property_enum_py_data(PropertyRNA *prop, void *py_data)
-{
-  EnumPropertyRNA *eprop = (EnumPropertyRNA *)prop;
-  eprop->py_data = py_data;
-}
-
 void RNA_def_property_string_funcs(PropertyRNA *prop,
                                    const char *get,
                                    const char *length,
@@ -4632,11 +4626,28 @@ void RNA_def_property_duplicate_pointers(StructOrFunctionRNA *cont_, PropertyRNA
   prop->flag_internal |= PROP_INTERN_FREE_POINTERS;
 }
 
+static void (*g_py_data_clear_fn)(PropertyRNA *prop) = NULL;
+
+/**
+ * Set the callback used to decrement the user count of a property.
+ *
+ * This function is called when freeing each dynamically defined property.
+ */
+void RNA_def_property_free_pointers_set_py_data_callback(
+    void (*py_data_clear_fn)(PropertyRNA *prop))
+{
+  g_py_data_clear_fn = py_data_clear_fn;
+}
+
 void RNA_def_property_free_pointers(PropertyRNA *prop)
 {
   if (prop->flag_internal & PROP_INTERN_FREE_POINTERS) {
     int a;
 
+    if (g_py_data_clear_fn) {
+      g_py_data_clear_fn(prop);
+    }
+
     if (prop->identifier) {
       MEM_freeN((void *)prop->identifier);
     }