https://github.com/python/cpython/commit/cef423cbe20dab5af89f4cbcfc9abda3cd5ba9f5 commit: cef423cbe20dab5af89f4cbcfc9abda3cd5ba9f5 branch: 3.13 author: Miss Islington (bot) <[email protected]> committer: encukou <[email protected]> date: 2026-03-12T10:45:43+01:00 summary:
[3.13] gh-145492: Fix defaultdict __repr__ infinite recursion (GH-145659) (GH-145746) (cherry picked from commit 2d35f9bc1cf61b27639ed992dfbf363ab436fd8b) Includes test fix-up from GH-145788 (cherry picked from commit aa4240ebea1aacc907b1efa58e7f547d90cff3b1) Co-authored-by: Thomas Kowalski <[email protected]> Co-authored-by: Matt Van Horn <[email protected]> files: A Misc/NEWS.d/next/Library/2026-03-09-00-00-00.gh-issue-145492.457Afc.rst M Lib/test/test_defaultdict.py M Modules/_collectionsmodule.c diff --git a/Lib/test/test_defaultdict.py b/Lib/test/test_defaultdict.py index fbd7354a915a0a..a193eb10f16d17 100644 --- a/Lib/test/test_defaultdict.py +++ b/Lib/test/test_defaultdict.py @@ -204,5 +204,20 @@ def default_factory(): self.assertEqual(test_dict[key], 2) self.assertEqual(count, 2) + def test_repr_recursive_factory(self): + # gh-145492: defaultdict.__repr__ should not cause infinite recursion + # when the factory's __repr__ calls repr() on the defaultdict. + class ProblematicFactory: + def __call__(self): + return {} + def __repr__(self): + repr(dd) + return f"ProblematicFactory for {dd}" + + dd = defaultdict(ProblematicFactory()) + # Should not raise RecursionError + r = repr(dd) + self.assertIn("ProblematicFactory for", r) + if __name__ == "__main__": unittest.main() diff --git a/Misc/NEWS.d/next/Library/2026-03-09-00-00-00.gh-issue-145492.457Afc.rst b/Misc/NEWS.d/next/Library/2026-03-09-00-00-00.gh-issue-145492.457Afc.rst new file mode 100644 index 00000000000000..297ee4099f12c5 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2026-03-09-00-00-00.gh-issue-145492.457Afc.rst @@ -0,0 +1,3 @@ +Fix infinite recursion in :class:`collections.defaultdict` ``__repr__`` +when a ``defaultdict`` contains itself. Based on analysis by KowalskiThomas +in :gh:`145492`. diff --git a/Modules/_collectionsmodule.c b/Modules/_collectionsmodule.c index f5fc0d02a16607..b2c3d0e42be4cb 100644 --- a/Modules/_collectionsmodule.c +++ b/Modules/_collectionsmodule.c @@ -2337,9 +2337,10 @@ defdict_repr(defdictobject *dd) } defrepr = PyUnicode_FromString("..."); } - else + else { defrepr = PyObject_Repr(dd->default_factory); - Py_ReprLeave(dd->default_factory); + Py_ReprLeave(dd->default_factory); + } } if (defrepr == NULL) { Py_DECREF(baserepr); _______________________________________________ Python-checkins mailing list -- [email protected] To unsubscribe send an email to [email protected] https://mail.python.org/mailman3//lists/python-checkins.python.org Member address: [email protected]
