diff --git a/Lib/dataclasses.py b/Lib/dataclasses.py
index 83ea623dce6281..22b78bb2fbe6ed 100644
--- a/Lib/dataclasses.py
+++ b/Lib/dataclasses.py
@@ -1338,6 +1338,13 @@ def _add_slots(cls, is_frozen, weakref_slot, defined_fields):
or _update_func_cell_for__class__(member.fdel, cls, newcls)):
break
+ # gh-135228: Make sure the original class can be garbage collected.
+ # Bypass mapping proxy to allow __dict__ to be removed
+ old_cls_dict = cls.__dict__ | _deproxier
+ old_cls_dict.pop('__dict__', None)
+ if "__weakref__" in cls.__dict__:
+ del cls.__weakref__
+
return newcls
@@ -1732,3 +1739,11 @@ def _replace(self, /, **changes):
# changes that aren't fields, this will correctly raise a
# TypeError.
return self.__class__(**changes)
+
+
+# Hack to the get the underlying dict out of a mappingproxy
+# Use it with: cls.__dict__ | _deproxier
+class _Deproxier:
+ def __ror__(self, other):
+ return other
+_deproxier = _Deproxier()
diff --git a/Lib/test/test_dataclasses/__init__.py b/Lib/test/test_dataclasses/__init__.py
index e98a8f284cec9f..6bf5e5b3e5554b 100644
--- a/Lib/test/test_dataclasses/__init__.py
+++ b/Lib/test/test_dataclasses/__init__.py
@@ -3804,6 +3804,41 @@ class WithCorrectSuper(CorrectSuper):
# that we create internally.
self.assertEqual(CorrectSuper.args, ["default", "default"])
+ def test_original_class_is_gced(self):
+ # gh-135228: Make sure when we replace the class with slots=True, the original class
+ # gets garbage collected.
+ def make_simple():
+ @dataclass(slots=True)
+ class SlotsTest:
+ pass
+
+ return SlotsTest
+
+ def make_with_annotations():
+ @dataclass(slots=True)
+ class SlotsTest:
+ x: int
+
+ return SlotsTest
+
+ def make_with_annotations_and_method():
+ @dataclass(slots=True)
+ class SlotsTest:
+ x: int
+
+ def method(self) -> int:
+ return self.x
+
+ return SlotsTest
+
+ for make in (make_simple, make_with_annotations, make_with_annotations_and_method):
+ with self.subTest(make=make):
+ C = make()
+ support.gc_collect()
+ candidates = [cls for cls in object.__subclasses__() if cls.__name__ == 'SlotsTest'
+ and cls.__firstlineno__ == make.__code__.co_firstlineno + 1]
+ self.assertEqual(candidates, [C])
+
class TestDescriptors(unittest.TestCase):
def test_set_name(self):
diff --git a/Misc/NEWS.d/next/Library/2025-07-20-16-56-55.gh-issue-135228.n_XIao.rst b/Misc/NEWS.d/next/Library/2025-07-20-16-56-55.gh-issue-135228.n_XIao.rst
new file mode 100644
index 00000000000000..ee8962c6f46e75
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2025-07-20-16-56-55.gh-issue-135228.n_XIao.rst
@@ -0,0 +1,4 @@
+When :mod:`dataclasses` replaces a class with a slotted dataclass, the
+original class is now garbage collected again. Earlier changes in Python
+3.14 caused this class to remain in existence together with the replacement
+class synthesized by :mod:`dataclasses`.
pFad - Phonifier reborn
Pfad - The Proxy pFad of © 2024 Garber Painting. All rights reserved.
Note: This service is not intended for secure transactions such as banking, social media, email, or purchasing. Use at your own risk. We assume no liability whatsoever for broken pages.
Alternative Proxies:
Alternative Proxy
pFad Proxy
pFad v3 Proxy
pFad v4 Proxy