From 42fee931d055a3ef8ed31abe44603b9b2856e04d Mon Sep 17 00:00:00 2001
From: Vlad Hoi <hoivladyslav@yahoo.com>
Date: Thu, 5 May 2022 16:40:01 +0300
Subject: [PATCH] bpo-43827: Make arguments to abc.ABCMeta.__new__ pos-only
 (#25385)

To avoid conflicts with `__init__subclass__`.
---
 Lib/abc.py                                          |  2 +-
 Lib/test/test_abc.py                                | 13 +++++++++++++
 Misc/ACKS                                           |  1 +
 .../2021-04-16-17-32-44.bpo-43827.uJaXdP.rst        |  1 +
 4 files changed, 16 insertions(+), 1 deletion(-)
 create mode 100644 Misc/NEWS.d/next/Library/2021-04-16-17-32-44.bpo-43827.uJaXdP.rst

diff --git a/Lib/abc.py b/Lib/abc.py
index 3c552cebb42..42048ddb855 100644
--- a/Lib/abc.py
+++ b/Lib/abc.py
@@ -102,7 +102,7 @@ class ABCMeta(type):
         implementations defined by the registering ABC be callable (not
         even via super()).
         """
-        def __new__(mcls, name, bases, namespace, **kwargs):
+        def __new__(mcls, name, bases, namespace, /, **kwargs):
             cls = super().__new__(mcls, name, bases, namespace, **kwargs)
             _abc_init(cls)
             return cls
diff --git a/Lib/test/test_abc.py b/Lib/test/test_abc.py
index c1d750dba83..1e7a0351db4 100644
--- a/Lib/test/test_abc.py
+++ b/Lib/test/test_abc.py
@@ -668,6 +668,19 @@ def __init_subclass__(cls, **kwargs):
             class Receiver(ReceivesClassKwargs, abc_ABC, x=1, y=2, z=3):
                 pass
             self.assertEqual(saved_kwargs, dict(x=1, y=2, z=3))
+
+        def test_positional_only_and_kwonlyargs_with_init_subclass(self):
+            saved_kwargs = {}
+
+            class A:
+                def __init_subclass__(cls, **kwargs):
+                    super().__init_subclass__()
+                    saved_kwargs.update(kwargs)
+
+            class B(A, metaclass=abc_ABCMeta, name="test"):
+                pass
+            self.assertEqual(saved_kwargs, dict(name="test"))
+
     return TestLegacyAPI, TestABC, TestABCWithInitSubclass
 
 TestLegacyAPI_Py, TestABC_Py, TestABCWithInitSubclass_Py = test_factory(abc.ABCMeta,
diff --git a/Misc/ACKS b/Misc/ACKS
index ec4de61ff92..2b9485e7aa8 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -753,6 +753,7 @@ Albert Hofkamp
 Chris Hogan
 Tomas Hoger
 Jonathan Hogg
+Vladyslav Hoi
 Kamilla Holanda
 Steve Holden
 Akintayo Holder
diff --git a/Misc/NEWS.d/next/Library/2021-04-16-17-32-44.bpo-43827.uJaXdP.rst b/Misc/NEWS.d/next/Library/2021-04-16-17-32-44.bpo-43827.uJaXdP.rst
new file mode 100644
index 00000000000..6e4f82f2d27
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2021-04-16-17-32-44.bpo-43827.uJaXdP.rst
@@ -0,0 +1 @@
+All positional-or-keyword parameters to ``ABCMeta.__new__`` are now positional-only to avoid conflicts with keyword arguments to be passed to :meth:`__init_subclass__`.