pythongh-126699: allow AsyncIterator to be used as a base for Protoco…

…ls (pythonGH-126702)

(cherry picked from commit feb3e0b)

Co-authored-by: Stephen Morton <github@tungol.org>

Lib/test/test_typing.py

@@ -3998,6 +3998,9 @@ class CustomProtocol(TestCase, Protocol):
         class CustomContextManager(typing.ContextManager, Protocol):
             pass
 
+        class CustomAsyncIterator(typing.AsyncIterator, Protocol):
+            pass
+
     def test_non_runtime_protocol_isinstance_check(self):
         class P(Protocol):
             x: int

Lib/typing.py

@@ -1815,7 +1815,8 @@ def _allow_reckless_class_checks(depth=2):
 _PROTO_ALLOWLIST = {
     'collections.abc': [
         'Callable', 'Awaitable', 'Iterable', 'Iterator', 'AsyncIterable',
-        'Hashable', 'Sized', 'Container', 'Collection', 'Reversible', 'Buffer',
+        'AsyncIterator', 'Hashable', 'Sized', 'Container', 'Collection',
+        'Reversible', 'Buffer',
     ],
     'contextlib': ['AbstractContextManager', 'AbstractAsyncContextManager'],
 }

Misc/NEWS.d/next/Library/2024-11-11-13-24-22.gh-issue-126699.ONGbMd.rst

@@ -0,0 +1 @@
+Allow :class:`collections.abc.AsyncIterator` to be a base for Protocols.