bpo-34973: Fix crash in bytes constructor. (GH-9841)
Constructing bytes from mutating list could cause a crash.
diff --git a/Lib/test/test_bytes.py b/Lib/test/test_bytes.py
index b9c5b62..145411e 100644
--- a/Lib/test/test_bytes.py
+++ b/Lib/test/test_bytes.py
@@ -113,6 +113,23 @@
b = self.type2test([1, 2, 3])
self.assertEqual(b, b"\x01\x02\x03")
+ def test_from_mutating_list(self):
+ # Issue #34973: Crash in bytes constructor with mutating list.
+ class X:
+ def __index__(self):
+ a.clear()
+ return 42
+ a = [X(), X()]
+ self.assertEqual(bytes(a), b'*')
+
+ class Y:
+ def __index__(self):
+ if len(a) < 1000:
+ a.append(self)
+ return 42
+ a = [Y()]
+ self.assertEqual(bytes(a), b'*' * 1000) # should not crash
+
def test_from_index(self):
b = self.type2test([Indexable(), Indexable(1), Indexable(254),
Indexable(255)])