From: Christian Tismer <tismer@stackless.com>

Date: Sat, 8 May 2021 16:06:23 +0200

Subject: py3.10-prep: reset the type cache after feature switching

When using feature switching in Python 3.10, there were

funny effects where switched and un-switched versions appeared

to co-exist.

It turned out that we were hit by function caching that

is now implemented for the LOAD_ATTR opcode.

It was not known that caching would happen at all for

PySide classes because we don't use Py_TPFLAGS_VALID_VERSION_TAG.

But actually, this flag is used internally by Python to do some

optimizations, and we just have to notify the interpreter of

type changes by PyType_Modified().

(cherry picked from commit 3a2b7c6f88bba04d8b7ddb571163d23c15c36a4f)

---

 sources/pyside2/libpyside/feature_select.cpp | 2 ++

 1 file changed, 2 insertions(+)

diff --git a/sources/pyside2/libpyside/feature_select.cpp b/sources/pyside2/libpyside/feature_select.cpp

index 6a21d16..3da7dde 100644

--- a/sources/pyside2/libpyside/feature_select.cpp

+++ b/sources/pyside2/libpyside/feature_select.cpp

@@ -405,6 +405,8 @@ static inline PyObject *SelectFeatureSet(PyTypeObject *type)

             if (!SelectFeatureSetSubtype(sub_type, select_id))

                 break;

         }

+        // PYSIDE-1436: Clear all caches for the type and subtypes.

+        PyType_Modified(type);

     }

     return type->tp_dict;

 }