From 4735de50b568468e355517a3133799d1136a9be2 Mon Sep 17 00:00:00 2001
From: Jeong YunWon <jeong@youknowone.org>
Date: Mon, 30 Jun 2025 15:18:22 +0900
Subject: [PATCH 1/4] gh-136047 Allow typing._allow_reckless_class_checks to
 check `_py_abc`

When `abc.py` fails to import `_abc` and instead imports `_py_abc.ABCMeta`,
`_py_abc.ABCMeta.__module__` is set to `abc` to allow
`typing._allow_reckless_class_checks` to work with it.

Unfortunately, when `typing._caller` falls back to using `sys._getframe`,
its `globals()` contains the real module name instead of the module name of the frame's function.

This patch allows checking for `_py_abc` in that scenario.
---
 Lib/typing.py | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/Lib/typing.py b/Lib/typing.py
index ed1dd4fc6413a5..1b6a8898e17540 100644
--- a/Lib/typing.py
+++ b/Lib/typing.py
@@ -1843,11 +1843,15 @@ def _no_init_or_replace_init(self, *args, **kwargs):
     cls.__init__(self, *args, **kwargs)
 
 
+_RECKLESS_CLASS_CHECK_ALLOWED = {'abc', 'functools', None}
+_SYS_HAS_GETFRAMEMODULENAME = hasattr(sys, '_getframemodulename')
+if not _SYS_HAS_GETFRAMEMODULENAME:
+    _RECKLESS_CLASS_CHECK_ALLOWED.add('_py_abc')
+
+
 def _caller(depth=1, default='__main__'):
-    try:
+    if _SYS_HAS_GETFRAMEMODULENAME:
         return sys._getframemodulename(depth + 1) or default
-    except AttributeError:  # For platforms without _getframemodulename()
-        pass
     try:
         return sys._getframe(depth + 1).f_globals.get('__name__', default)
     except (AttributeError, ValueError):  # For platforms without _getframe()
@@ -1860,7 +1864,7 @@ def _allow_reckless_class_checks(depth=2):
     The abc and functools modules indiscriminately call isinstance() and
     issubclass() on the whole MRO of a user class, which may contain protocols.
     """
-    return _caller(depth) in {'abc', 'functools', None}
+    return _caller(depth) in _RECKLESS_CLASS_CHECK_ALLOWED
 
 
 _PROTO_ALLOWLIST = {

From 8e216945250997d880acb98b7d1eb82a0ab21e0d Mon Sep 17 00:00:00 2001
From: Jeong YunWon <jeong@youknowone.org>
Date: Mon, 30 Jun 2025 23:43:29 +0900
Subject: [PATCH 2/4] Revert "gh-136047 Allow
 typing._allow_reckless_class_checks to check `_py_abc`"

This reverts commit 4735de50b568468e355517a3133799d1136a9be2.
---
 Lib/typing.py | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/Lib/typing.py b/Lib/typing.py
index 1b6a8898e17540..ed1dd4fc6413a5 100644
--- a/Lib/typing.py
+++ b/Lib/typing.py
@@ -1843,15 +1843,11 @@ def _no_init_or_replace_init(self, *args, **kwargs):
     cls.__init__(self, *args, **kwargs)
 
 
-_RECKLESS_CLASS_CHECK_ALLOWED = {'abc', 'functools', None}
-_SYS_HAS_GETFRAMEMODULENAME = hasattr(sys, '_getframemodulename')
-if not _SYS_HAS_GETFRAMEMODULENAME:
-    _RECKLESS_CLASS_CHECK_ALLOWED.add('_py_abc')
-
-
 def _caller(depth=1, default='__main__'):
-    if _SYS_HAS_GETFRAMEMODULENAME:
+    try:
         return sys._getframemodulename(depth + 1) or default
+    except AttributeError:  # For platforms without _getframemodulename()
+        pass
     try:
         return sys._getframe(depth + 1).f_globals.get('__name__', default)
     except (AttributeError, ValueError):  # For platforms without _getframe()
@@ -1864,7 +1860,7 @@ def _allow_reckless_class_checks(depth=2):
     The abc and functools modules indiscriminately call isinstance() and
     issubclass() on the whole MRO of a user class, which may contain protocols.
     """
-    return _caller(depth) in _RECKLESS_CLASS_CHECK_ALLOWED
+    return _caller(depth) in {'abc', 'functools', None}
 
 
 _PROTO_ALLOWLIST = {

From 519898d00fdf28ae9d510a93fe117f0f2996ab43 Mon Sep 17 00:00:00 2001
From: Jeong YunWon <jeong@youknowone.org>
Date: Mon, 30 Jun 2025 23:45:29 +0900
Subject: [PATCH 3/4] Simply add _py_abc

---
 Lib/typing.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/Lib/typing.py b/Lib/typing.py
index ed1dd4fc6413a5..e8a61e64833602 100644
--- a/Lib/typing.py
+++ b/Lib/typing.py
@@ -1860,7 +1860,9 @@ def _allow_reckless_class_checks(depth=2):
     The abc and functools modules indiscriminately call isinstance() and
     issubclass() on the whole MRO of a user class, which may contain protocols.
     """
-    return _caller(depth) in {'abc', 'functools', None}
+    # gh-136047: When `_abc` module is not available, `_py_abc` is required to
+    # allow `_py_abc.ABCMeta` fallback.
+    return _caller(depth) in {'abc', '_py_abc', 'functools', None}
 
 
 _PROTO_ALLOWLIST = {

From 934705b9f45f32166a9824c75ea7a8c5adcce420 Mon Sep 17 00:00:00 2001
From: Jelle Zijlstra <jelle.zijlstra@gmail.com>
Date: Sat, 5 Jul 2025 06:59:49 -0700
Subject: [PATCH 4/4] blurb

---
 .../next/Library/2025-07-05-06-59-46.gh-issue-136047.qWvycf.rst | 2 ++
 1 file changed, 2 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Library/2025-07-05-06-59-46.gh-issue-136047.qWvycf.rst

diff --git a/Misc/NEWS.d/next/Library/2025-07-05-06-59-46.gh-issue-136047.qWvycf.rst b/Misc/NEWS.d/next/Library/2025-07-05-06-59-46.gh-issue-136047.qWvycf.rst
new file mode 100644
index 00000000000000..1a381860914bc3
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2025-07-05-06-59-46.gh-issue-136047.qWvycf.rst
@@ -0,0 +1,2 @@
+Fix issues with :mod:`typing` when the C implementation of :mod:`abc` is not
+available.