1 files changed, 47 insertions, 0 deletions
diff --git a/_distutils_importer/override.py b/_distutils_importer/override.py
new file mode 100644
index 00000000..91738485
--- /dev/null
+++ b/_distutils_importer/override.py
@@ -0,0 +1,47 @@
+import sys
+import re
+import importlib
+import warnings
+
+from . import enabled
+
+
+is_pypy = '__pypy__' in sys.builtin_module_names
+
+
+def warn_distutils_present():
+    if 'distutils' not in sys.modules:
+        return
+    if is_pypy and sys.version_info < (3, 7):
+        # 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
+    warnings.warn(
+        "Distutils was imported before Setuptools. This usage is discouraged "
+        "and may exhibit undesirable behaviors or errors. Please use "
+        "Setuptools' objects directly or at least import Setuptools first.")
+
+
+def clear_distutils():
+    if 'distutils' not in sys.modules:
+        return
+    warnings.warn("Setuptools is replacing distutils.")
+    mods = [name for name in sys.modules if re.match(r'distutils\b', name)]
+    for name in mods:
+        del sys.modules[name]
+
+
+def ensure_local_distutils():
+    clear_distutils()
+    distutils = importlib.import_module('setuptools._distutils')
+    distutils.__name__ = 'distutils'
+    sys.modules['distutils'] = distutils
+
+    # sanity check that submodules load as expected
+    core = importlib.import_module('distutils.core')
+    assert '_distutils' in core.__file__, core.__file__
+
+
+warn_distutils_present()
+if enabled():
+    ensure_local_distutils()