diff --git a/Lib/_abcoll.py b/Lib/_abcoll.py index d3e23c1e446..cac06e0825f 100644 --- a/Lib/_abcoll.py +++ b/Lib/_abcoll.py @@ -321,18 +321,24 @@ def __iand__(self, it: Iterable): return self def __ixor__(self, it: Iterable): - if not isinstance(it, Set): - it = self._from_iterable(it) - for value in it: - if value in self: - self.discard(value) - else: - self.add(value) + if it is self: + self.clear() + else: + if not isinstance(it, Set): + it = self._from_iterable(it) + for value in it: + if value in self: + self.discard(value) + else: + self.add(value) return self def __isub__(self, it: Iterable): - for value in it: - self.discard(value) + if it is self: + self.clear() + else: + for value in it: + self.discard(value) return self MutableSet.register(set) diff --git a/Lib/test/test_collections.py b/Lib/test/test_collections.py index da80baa9970..75d660d6287 100644 --- a/Lib/test/test_collections.py +++ b/Lib/test/test_collections.py @@ -526,6 +526,21 @@ def __repr__(self): s = MySet([5,43,2,1]) self.assertEqual(s.pop(), 1) + def test_issue8750(self): + empty = WithSet() + full = WithSet(range(10)) + s = WithSet(full) + s -= s + self.assertEqual(s, empty) + s = WithSet(full) + s ^= s + self.assertEqual(s, empty) + s = WithSet(full) + s &= s + self.assertEqual(s, full) + s |= s + self.assertEqual(s, full) + def test_Mapping(self): for sample in [dict]: self.assertIsInstance(sample(), Mapping) diff --git a/Misc/NEWS b/Misc/NEWS index 5d234647edd..304977b385c 100644 --- a/Misc/NEWS +++ b/Misc/NEWS @@ -126,6 +126,9 @@ Extensions Library ------- +- Issue #8750: Fixed MutableSet's methods to correctly handle + reflexive operations, namely x -= x and x ^= x. + - Issue #9129: smtpd.py is vulnerable to DoS attacks deriving from missing error handling when accepting a new connection.