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gh-129139: Fix __setstate__ on exhausted list iterators in free-threaded build #146269

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gh-129139: Fix __setstate__ on exhausted list iterators in free-threaded build #146269

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14 changes: 14 additions & 0 deletions Lib/test/test_list.py
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Original file line number Diff line number Diff line change
Expand Up @@ -213,6 +213,20 @@ def test_reversed_pickle(self):
a[:] = data
self.assertEqual(list(it), [])

def test_exhausted_iterator_setstate(self):
# gh-129139: __setstate__ on an exhausted iterator must not revive it
it = iter([1, 2, 3])
list(it) # exhaust the iterator
it.__setstate__(0)
self.assertRaises(StopIteration, next, it)

def test_exhausted_reversed_iterator_setstate(self):
# gh-129139: __setstate__ on an exhausted reversed iterator must not revive it
it = reversed([1, 2, 3])
list(it) # exhaust the iterator
it.__setstate__(0)
self.assertRaises(StopIteration, next, it)

def test_step_overflow(self):
a = [0, 1, 2, 3, 4]
a[1::sys.maxsize] = [0]
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1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Core_and_Builtins/2026-03-22-00-00-00.gh-issue-129139.8hyhJC.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
In free-threaded build, fix ``__setstate__`` on exhausted list iterators and reversed list iterators reviving the iterator instead of being a no-op.
4 changes: 2 additions & 2 deletions Objects/listobject.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4108,7 +4108,7 @@ listiter_setstate(PyObject *self, PyObject *state)
Py_ssize_t index = PyLong_AsSsize_t(state);
if (index == -1 && PyErr_Occurred())
return NULL;
if (it->it_seq != NULL) {
if (it->it_seq != NULL && FT_ATOMIC_LOAD_SSIZE_RELAXED(it->it_index) >= 0) {
if (index < -1)
index = -1;
else if (index > PyList_GET_SIZE(it->it_seq))
Expand Down Expand Up @@ -4260,7 +4260,7 @@ listreviter_setstate(PyObject *self, PyObject *state)
Py_ssize_t index = PyLong_AsSsize_t(state);
if (index == -1 && PyErr_Occurred())
return NULL;
if (it->it_seq != NULL) {
if (it->it_seq != NULL && FT_ATOMIC_LOAD_SSIZE_RELAXED(it->it_index) >= 0) {
if (index < -1)
index = -1;
else if (index > PyList_GET_SIZE(it->it_seq) - 1)
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