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gh-157621: Clear weakrefs for ParamSpec attributes #157622

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Merged
JelleZijlstra merged 3 commits into from
Sep 17, 2026
+14 −0
Merged

gh-157621: Clear weakrefs for ParamSpec attributes #157622

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58c43da
gh-157621: Clear ParamSpec attribute weakrefs
GruffElixir Sep 16, 2026
7856788
gh-157621: Add NEWS entry
GruffElixir Sep 16, 2026
2ba5aca
gh-157621: Fix NEWS fragment filename
GruffElixir Sep 16, 2026
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11 changes: 11 additions & 0 deletions Lib/test/test_typing.py
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Original file line number Diff line number Diff line change
Expand Up @@ -10299,6 +10299,17 @@ def test_args_kwargs(self):
self.assertEqual(repr(P.args), "P.args")
self.assertEqual(repr(P.kwargs), "P.kwargs")

def test_args_kwargs_weakrefs(self):
P = ParamSpec('P')
for attr_name in ('args', 'kwargs'):
with self.subTest(attr_name=attr_name):
callback_fired = []
attr = getattr(P, attr_name)
ref = weakref.ref(attr, lambda _: callback_fired.append(True))
del attr
self.assertEqual(callback_fired, [True])
self.assertIsNone(ref())

def test_stringized(self):
P = ParamSpec('P')
class C(Generic[P]):
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2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Library/2026-09-16-14-04-38.gh-issue-157621.R6v2S8.rst
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@@ -0,0 +1,2 @@
Fix a crash when a weak-reference callback is attached to a
:class:`typing.ParamSpecArgs` or :class:`typing.ParamSpecKwargs` instance.
1 change: 1 addition & 0 deletions Objects/typevarobject.c
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Expand Up @@ -958,6 +958,7 @@ paramspecattr_dealloc(PyObject *self)
_PyObject_GC_UNTRACK(self);

Py_XDECREF(psa->__origin__);
PyObject_ClearWeakRefs(self);

Py_TYPE(self)->tp_free(self);
Py_DECREF(tp);
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