Issue #5647: MutableSet.__iand__() no longer mutates self during iteration.
diff --git a/Lib/_abcoll.py b/Lib/_abcoll.py
index 40cc23e..990ff00 100644
--- a/Lib/_abcoll.py
+++ b/Lib/_abcoll.py
@@ -286,10 +286,9 @@
self.add(value)
return self
- def __iand__(self, c):
- for value in self:
- if value not in c:
- self.discard(value)
+ def __iand__(self, it):
+ for value in (self - it):
+ self.discard(value)
return self
def __ixor__(self, it):
diff --git a/Lib/test/test_collections.py b/Lib/test/test_collections.py
index 9e984ba..8ffa75b 100644
--- a/Lib/test/test_collections.py
+++ b/Lib/test/test_collections.py
@@ -327,6 +327,25 @@
B.register(C)
self.failUnless(issubclass(C, B))
+class WithSet(MutableSet):
+
+ def __init__(self, it=()):
+ self.data = set(it)
+
+ def __len__(self):
+ return len(self.data)
+
+ def __iter__(self):
+ return iter(self.data)
+
+ def __contains__(self, item):
+ return item in self.data
+
+ def add(self, item):
+ self.data.add(item)
+
+ def discard(self, item):
+ self.data.discard(item)
class TestCollectionABCs(ABCTestCase):
@@ -363,6 +382,12 @@
self.validate_abstract_methods(MutableSet, '__contains__', '__iter__', '__len__',
'add', 'discard')
+ def test_issue_5647(self):
+ # MutableSet.__iand__ mutated the set during iteration
+ s = WithSet('abcd')
+ s &= WithSet('cdef') # This used to fail
+ self.assertEqual(set(s), set('cd'))
+
def test_issue_4920(self):
# MutableSet.pop() method did not work
class MySet(collections.MutableSet):
diff --git a/Misc/NEWS b/Misc/NEWS
index f5e280c..2e01d0d 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -206,6 +206,8 @@
instead of performing them in functions. Helps prevent import deadlocking in
threads.
+- Issue #5647: MutableSet.__iand__() no longer mutates self during iteration.
+
- Actually make the SimpleXMLRPCServer CGI handler work.
- Issue #2522: locale.format now checks its first argument to ensure it has