Remove ABCMeta metaclass, keep abstractmethods

newsfragments/4579.bugfix.rst

@@ -0,0 +1 @@
+Remove `abc.ABCMeta` metaclass from abstract classes. `pypa/setuptools#4503 <https://github.com/pypa/setuptools/pull/4503>`_ had an unintended consequence of causing potential ``TypeError: metaclass conflict: the metaclass of a derived class must be a (non-strict) subclass of the metaclasses of all its bases`` -- by :user:`Avasam`

pkg_resources/__init__.py

@@ -23,7 +23,6 @@
 from __future__ import annotations
 
 import sys
-from abc import ABC
 
 if sys.version_info < (3, 8):  # noqa: UP036 # Check for unsupported versions
     raise RuntimeError("Python 3.8 or later is required")
@@ -306,7 +305,7 @@ def get_supported_platform():
 ]
 
 
-class ResolutionError(Exception, ABC):
+class ResolutionError(Exception):
     """Abstract base for dependency resolution errors"""
 
     def __repr__(self):

setuptools/__init__.py

@@ -6,7 +6,7 @@
 import os
 import re
 import sys
-from abc import ABC, abstractmethod
+from abc import abstractmethod
 from typing import TYPE_CHECKING, TypeVar, overload
 
 sys.path.extend(((vendor_path := os.path.join(os.path.dirname(os.path.dirname(__file__)), 'setuptools', '_vendor')) not in sys.path) * [vendor_path])  # fmt: skip
@@ -120,7 +120,7 @@ def setup(**attrs):
     _Command = monkey.get_unpatched(distutils.core.Command)
 
 
-class Command(_Command, ABC):
+class Command(_Command):
     """
     Setuptools internal actions are organized using a *command design pattern*.
     This means that each action (or group of closely related actions) executed during

setuptools/command/setopt.py

@@ -1,6 +1,5 @@
 import configparser
 import os
-from abc import ABC
 
 from .. import Command
 from ..unicode_utils import _cfg_read_utf8_with_fallback
@@ -70,7 +69,7 @@ def edit_config(filename, settings, dry_run=False):
             opts.write(f)
 
 
-class option_base(Command, ABC):
+class option_base(Command):
     """Abstract base class for commands that mess with config files"""
 
     user_options = [

setuptools/sandbox.py

@@ -11,7 +11,6 @@
 import sys
 import tempfile
 import textwrap
-from abc import ABC
 
 import pkg_resources
 from pkg_resources import working_set
@@ -263,7 +262,7 @@ def run_setup(setup_script, args):
             # Normal exit, just return
 
 
-class AbstractSandbox(ABC):
+class AbstractSandbox:
     """Wrap 'os' module and 'open()' builtin for virtualizing setup scripts"""
 
     _active = False