diff --git Lib/_abcoll.py Lib/_abcoll.py index 326c1f9..58b6672 100644 --- Lib/_abcoll.py +++ Lib/_abcoll.py @@ -305,18 +305,24 @@ class MutableSet(Set): return self def __ixor__(self, it): - 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): - 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 Lib/test/test_collections.py Lib/test/test_collections.py index 4330583..bec6dc0 100644 --- Lib/test/test_collections.py +++ Lib/test/test_collections.py @@ -487,6 +487,21 @@ class TestCollectionABCs(ABCTestCase): 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)