Consolidate distutils importing hacks into _distutils_importer package....

Consolidate distutils importing hacks into _distutils_importer package. Generate distutils-precedence.pth inline.

MANIFEST.in

@@ -13,5 +13,4 @@ include launcher.c
 include msvc-build-launcher.cmd
 include pytest.ini
 include tox.ini
-include distutils_precedence.pth
 exclude pyproject.toml  # Temporary workaround for #1644.

_distutils_importer/__init__.py

+"""
+Ensure that the local copy of distutils is preferred over stdlib.
+
+See https://github.com/pypa/setuptools/issues/417#issuecomment-392298401
+for more motivation.
+"""
+
 import sys
+import os
+
+
+def enabled():
+    """
+    Allow selection of distutils by environment variable.
+    """
+    which = os.environ.get('SETUPTOOLS_USE_DISTUTILS', 'stdlib')
+    return which == 'local'
 
 
 class DistutilsMetaFinder:
@@ -34,6 +50,3 @@ def remove_shim():
         sys.path.remove(DISTUTILS_FINDER)
     except ValueError:
         pass
-
-
-add_shim()

_distutils_importer/install.py

+from . import enabled, add_shim
+
+
+if enabled():
+    add_shim()

setuptools/distutils_patch.py → _distutils_importer/override.py

-"""
-Ensure that the local copy of distutils is preferred over stdlib.
-
-See https://github.com/pypa/setuptools/issues/417#issuecomment-392298401
-for more motivation.
-"""
-
 import sys
 import re
-import os
 import importlib
 import warnings
 
+from . import enabled
+
 
 is_pypy = '__pypy__' in sys.builtin_module_names
 
@@ -37,14 +31,6 @@ def clear_distutils():
         del sys.modules[name]
 
 
-def enabled():
-    """
-    Allow selection of distutils by environment variable.
-    """
-    which = os.environ.get('SETUPTOOLS_USE_DISTUTILS', 'stdlib')
-    return which == 'local'
-
-
 def ensure_local_distutils():
     clear_distutils()
     distutils = importlib.import_module('setuptools._distutils')

conftest.py

@@ -15,7 +15,7 @@ collect_ignore = [
     'tests/manual_test.py',
     'setuptools/tests/mod_with_constant.py',
     'setuptools/_distutils',
-    'setuptools/distutils_patch.py',
+    '_distutils_importer',
 ]
 
 

distutils_precedence.pth

-import os; (os.environ.get('SETUPTOOLS_USE_DISTUTILS', 'stdlib') == 'local' and __import__('_distutils_importer'))

setup.py

@@ -94,12 +94,8 @@ class install_with_pth(install):
 
     def initialize_options(self):
         install.initialize_options(self)
-
-        name = 'distutils_precedence'
-        with open(os.path.join(here, name + '.pth'), 'rt') as f:
-            contents = f.read()
-
-        self.extra_path = (name, contents)
+        self.extra_path = (
+            'distutils-precedence', 'import _distutils_importer.install')
 
     def finalize_options(self):
         install.finalize_options(self)

setuptools/__init__.py

@@ -5,8 +5,7 @@ import functools
 import os
 import re
 
-# Disabled for now due to: #2228, #2230
-import setuptools.distutils_patch  # noqa: F401
+import _distutils_importer.override  # noqa: F401
 
 import distutils.core
 from distutils.errors import DistutilsOptionError