Expand protocol allowlist to match CPythons (#676)

CHANGELOG.md

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 77b27dd..fcd2db5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,8 @@
   [#149172](https://github.com/python/cpython/pull/149172).
 - Fix setting of `__required_keys__` and `__optional_keys__` when inheriting
   keys with the same name.
+- Add support for `AsyncIterator`, `io.Reader`, `io.Writer` and `os.PathLike` protocols
+  as bases for other protocls.
 - Fix incorrect behaviour on Python 3.9 and Python 3.10 that meant that
   calling `isinstance` with `typing_extensions.Concatenate[...]` or
   `typing_extensions.Unpack[...]` as the first argument could have a different

src/test_typing_extensions.py

diff --git a/src/test_typing_extensions.py b/src/test_typing_extensions.py
index c3aede8..54b65f4 100644
--- a/src/test_typing_extensions.py
+++ b/src/test_typing_extensions.py
@@ -10,6 +10,7 @@
 import inspect
 import io
 import itertools
+import os
 import pickle
 import re
 import subprocess
@@ -3870,9 +3871,15 @@
             class CustomProtocol(TestCase, Protocol):
                 pass
 
+        class CustomPathLikeProtocol(os.PathLike, Protocol):
+            pass
+
         class CustomContextManager(typing.ContextManager, Protocol):
             pass
 
+        class CustomAsyncIterator(typing.AsyncIterator, Protocol):
+            pass
+
     @skip_if_py312b1
     def test_typing_extensions_protocol_allowlist(self):
         @runtime_checkable
@@ -7110,13 +7117,13 @@
             }
         if sys.version_info < (3, 13):
             exclude |= {
-                'NamedTuple', 'Protocol', 'runtime_checkable', 'Generator',
+                'NamedTuple', 'runtime_checkable', 'Generator',
                 'AsyncGenerator', 'ContextManager', 'AsyncContextManager',
                 'ParamSpec', 'TypeVar', 'TypeVarTuple', 'get_type_hints',
             }
         if sys.version_info < (3, 15):
             exclude |= {
-                'TypeAliasType'
+                'TypeAliasType', 'Protocol'
             }
         if not typing_extensions._PEP_728_IMPLEMENTED:
             exclude |= {'TypedDict', 'is_typeddict'}

src/typing_extensions.py

diff --git a/src/typing_extensions.py b/src/typing_extensions.py
index e370475..712a6ea 100644
--- a/src/typing_extensions.py
+++ b/src/typing_extensions.py
@@ -677,10 +677,13 @@
 _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'],
+    'io': ['Reader', 'Writer'],
     'typing_extensions': ['Buffer'],
+    'os': ['PathLike'],
 }
 
 
@@ -704,8 +707,10 @@
 
 # `__match_args__` attribute was removed from protocol members in 3.13,
 # we want to backport this change to older Python versions.
-# Breakpoint: https://github.com/python/cpython/pull/110683
-if sys.version_info >= (3, 13):
+# 3.14 additionally added `io.Reader`, `io.Writer` and `os.PathLike` to
+# the list of allowed protocol allowlist.
+# https://github.com/python/cpython/issues/127647
+if sys.version_info >= (3, 14):
     Protocol = typing.Protocol
 else:
     def _allow_reckless_class_checks(depth=2):