diff --git a/Lib/test/test_typing.py b/Lib/test/test_typing.py
index f6e0d203b5be86..1ad07b1fd6e379 100644
--- a/Lib/test/test_typing.py
+++ b/Lib/test/test_typing.py
@@ -3,6 +3,7 @@
import collections.abc
from collections import defaultdict
from functools import lru_cache, wraps
+import gc
import inspect
import itertools
import pickle
@@ -2758,6 +2759,19 @@ def x(self): ...
with self.assertRaisesRegex(TypeError, only_classes_allowed):
issubclass(1, BadPG)
+ def test_isinstance_checks_not_at_whim_of_gc(self):
+ self.addCleanup(gc.enable)
+ gc.disable()
+
+ with self.assertRaisesRegex(
+ TypeError,
+ "Protocols can only inherit from other protocols"
+ ):
+ class Foo(collections.abc.Mapping, Protocol):
+ pass
+
+ self.assertNotIsInstance([], collections.abc.Mapping)
+
def test_issubclass_and_isinstance_on_Protocol_itself(self):
class C:
def x(self): pass
diff --git a/Lib/typing.py b/Lib/typing.py
index c831ba847fc384..000b1586458db6 100644
--- a/Lib/typing.py
+++ b/Lib/typing.py
@@ -1771,6 +1771,25 @@ def _pickle_pskwargs(pskwargs):
class _ProtocolMeta(ABCMeta):
# This metaclass is somewhat unfortunate,
# but is necessary for several reasons...
+ def __new__(mcls, name, bases, namespace, /, **kwargs):
+ if name == "Protocol" and bases == (Generic,):
+ pass
+ elif Protocol in bases:
+ for base in bases:
+ if not (
+ base in {object, Generic}
+ or base.__name__ in _PROTO_ALLOWLIST.get(base.__module__, [])
+ or (
+ issubclass(base, Generic)
+ and getattr(base, "_is_protocol", False)
+ )
+ ):
+ raise TypeError(
+ f"Protocols can only inherit from other protocols, "
+ f"got {base!r}"
+ )
+ return super().__new__(mcls, name, bases, namespace, **kwargs)
+
def __init__(cls, *args, **kwargs):
super().__init__(*args, **kwargs)
if getattr(cls, "_is_protocol", False):
@@ -1906,14 +1925,7 @@ def _proto_hook(other):
if not cls._is_protocol:
return
- # ... otherwise check consistency of bases, and prohibit instantiation.
- for base in cls.__bases__:
- if not (base in (object, Generic) or
- base.__module__ in _PROTO_ALLOWLIST and
- base.__name__ in _PROTO_ALLOWLIST[base.__module__] or
- issubclass(base, Generic) and getattr(base, '_is_protocol', False)):
- raise TypeError('Protocols can only inherit from other'
- ' protocols, got %r' % base)
+ # ... otherwise prohibit instantiation.
if cls.__init__ is Protocol.__init__:
cls.__init__ = _no_init_or_replace_init
diff --git a/Misc/NEWS.d/next/Library/2023-06-04-12-16-47.gh-issue-105280.srRbCe.rst b/Misc/NEWS.d/next/Library/2023-06-04-12-16-47.gh-issue-105280.srRbCe.rst
new file mode 100644
index 00000000000000..8e469646604316
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2023-06-04-12-16-47.gh-issue-105280.srRbCe.rst
@@ -0,0 +1,4 @@
+Fix bug where ``isinstance([], collections.abc.Mapping)`` could evaluate to
+``True`` if garbage collection happened at the wrong time. The bug was
+caused by changes to the implementation of :class:`typing.Protocol` in
+Python 3.12.
pFad - Phonifier reborn
Pfad - The Proxy pFad of © 2024 Garber Painting. All rights reserved.
Note: This service is not intended for secure transactions such as banking, social media, email, or purchasing. Use at your own risk. We assume no liability whatsoever for broken pages.
Alternative Proxies:
Alternative Proxy
pFad Proxy
pFad v3 Proxy
pFad v4 Proxy