Merge branch 'main' into debt/remove-easy-installdebt/remove-easy-install

1 files changed, 73 insertions, 18 deletions

diff --git a/_distutils_hack/__init__.py b/_distutils_hack/__init__.py
index f7074162..605a6edc 100644
--- a/_distutils_hack/__init__.py
+++ b/_distutils_hack/__init__.py
@@ -1,18 +1,11 @@
+# don't import any costly modules
 import sys
 import os
-import re
-import importlib
-import warnings
 
 
 is_pypy = '__pypy__' in sys.builtin_module_names
 
 
-warnings.filterwarnings('ignore',
-                        r'.+ distutils\b.+ deprecated',
-                        DeprecationWarning)
-
-
 def warn_distutils_present():
     if 'distutils' not in sys.modules:
         return
@@ -20,6 +13,7 @@ def warn_distutils_present():
         # PyPy for 3.6 unconditionally imports distutils, so bypass the warning
         # https://foss.heptapod.net/pypy/pypy/-/blob/be829135bc0d758997b3566062999ee8b23872b4/lib-python/3/site.py#L250
         return
+    import warnings
     warnings.warn(
         "Distutils was imported before Setuptools, but importing Setuptools "
         "also replaces the `distutils` module in `sys.modules`. This may lead "
@@ -32,8 +26,12 @@ def warn_distutils_present():
 def clear_distutils():
     if 'distutils' not in sys.modules:
         return
+    import warnings
     warnings.warn("Setuptools is replacing distutils.")
-    mods = [name for name in sys.modules if re.match(r'distutils\b', name)]
+    mods = [
+        name for name in sys.modules
+        if name == "distutils" or name.startswith("distutils.")
+    ]
     for name in mods:
         del sys.modules[name]
 
@@ -42,23 +40,24 @@ def enabled():
     """
     Allow selection of distutils by environment variable.
     """
-    which = os.environ.get('SETUPTOOLS_USE_DISTUTILS', 'stdlib')
+    which = os.environ.get('SETUPTOOLS_USE_DISTUTILS', 'local')
     return which == 'local'
 
 
 def ensure_local_distutils():
+    import importlib
     clear_distutils()
 
     # With the DistutilsMetaFinder in place,
     # perform an import to cause distutils to be
     # loaded from setuptools._distutils. Ref #2906.
-    add_shim()
-    importlib.import_module('distutils')
-    remove_shim()
+    with shim():
+        importlib.import_module('distutils')
 
     # check that submodules load as expected
     core = importlib.import_module('distutils.core')
     assert '_distutils' in core.__file__, core.__file__
+    assert 'setuptools._distutils.log' not in sys.modules
 
 
 def do_override():
@@ -73,6 +72,14 @@ def do_override():
         ensure_local_distutils()
 
 
+class _TrivialRe:
+    def __init__(self, *patterns):
+        self._patterns = patterns
+
+    def match(self, string):
+        return all(pat in string for pat in self._patterns)
+
+
 class DistutilsMetaFinder:
     def find_spec(self, fullname, path, target=None):
         if path is not None:
@@ -83,18 +90,46 @@ class DistutilsMetaFinder:
         return method()
 
     def spec_for_distutils(self):
+        if self.is_cpython():
+            return
+
+        import importlib
         import importlib.abc
         import importlib.util
 
+        try:
+            mod = importlib.import_module('setuptools._distutils')
+        except Exception:
+            # There are a couple of cases where setuptools._distutils
+            # may not be present:
+            # - An older Setuptools without a local distutils is
+            #   taking precedence. Ref #2957.
+            # - Path manipulation during sitecustomize removes
+            #   setuptools from the path but only after the hook
+            #   has been loaded. Ref #2980.
+            # In either case, fall back to stdlib behavior.
+            return
+
         class DistutilsLoader(importlib.abc.Loader):
 
             def create_module(self, spec):
-                return importlib.import_module('setuptools._distutils')
+                mod.__name__ = 'distutils'
+                return mod
 
             def exec_module(self, module):
                 pass
 
-        return importlib.util.spec_from_loader('distutils', DistutilsLoader())
+        return importlib.util.spec_from_loader(
+            'distutils', DistutilsLoader(), origin=mod.__file__
+        )
+
+    @staticmethod
+    def is_cpython():
+        """
+        Suppress supplying distutils for CPython (build and tests).
+        Ref #2965 and #3007.
+        """
+        return os.path.isfile('pybuilddir.txt')
 
     def spec_for_pip(self):
         """
@@ -106,22 +141,42 @@ class DistutilsMetaFinder:
         clear_distutils()
         self.spec_for_distutils = lambda: None
 
-    @staticmethod
-    def pip_imported_during_build():
+    @classmethod
+    def pip_imported_during_build(cls):
         """
         Detect if pip is being imported in a build script. Ref #2355.
         """
         import traceback
         return any(
-            frame.f_globals['__file__'].endswith('setup.py')
+            cls.frame_file_is_setup(frame)
             for frame, line in traceback.walk_stack(None)
         )
 
+    @staticmethod
+    def frame_file_is_setup(frame):
+        """
+        Return True if the indicated frame suggests a setup.py file.
+        """
+        # some frames may not have __file__ (#2940)
+        return frame.f_globals.get('__file__', '').endswith('setup.py')
+
 
 DISTUTILS_FINDER = DistutilsMetaFinder()
 
 
 def add_shim():
+    DISTUTILS_FINDER in sys.meta_path or insert_shim()
+
+
+class shim:
+    def __enter__(self):
+        insert_shim()
+
+    def __exit__(self, exc, value, tb):
+        remove_shim()
+
+
+def insert_shim():
     sys.meta_path.insert(0, DISTUTILS_FINDER)