1 files changed, 71 insertions, 0 deletions
diff --git a/setuptools/_vendor/importlib_metadata/_compat.py b/setuptools/_vendor/importlib_metadata/_compat.py
new file mode 100644
index 0000000..ef3136f
--- /dev/null
+++ b/setuptools/_vendor/importlib_metadata/_compat.py
@@ -0,0 +1,71 @@
+import sys
+import platform
+
+
+__all__ = ['install', 'NullFinder', 'Protocol']
+
+
+try:
+    from typing import Protocol
+except ImportError:  # pragma: no cover
+    from ..typing_extensions import Protocol  # type: ignore
+
+
+def install(cls):
+    """
+    Class decorator for installation on sys.meta_path.
+
+    Adds the backport DistributionFinder to sys.meta_path and
+    attempts to disable the finder functionality of the stdlib
+    DistributionFinder.
+    """
+    sys.meta_path.append(cls())
+    disable_stdlib_finder()
+    return cls
+
+
+def disable_stdlib_finder():
+    """
+    Give the backport primacy for discovering path-based distributions
+    by monkey-patching the stdlib O_O.
+
+    See #91 for more background for rationale on this sketchy
+    behavior.
+    """
+
+    def matches(finder):
+        return getattr(
+            finder, '__module__', None
+        ) == '_frozen_importlib_external' and hasattr(finder, 'find_distributions')
+
+    for finder in filter(matches, sys.meta_path):  # pragma: nocover
+        del finder.find_distributions
+
+
+class NullFinder:
+    """
+    A "Finder" (aka "MetaClassFinder") that never finds any modules,
+    but may find distributions.
+    """
+
+    @staticmethod
+    def find_spec(*args, **kwargs):
+        return None
+
+    # In Python 2, the import system requires finders
+    # to have a find_module() method, but this usage
+    # is deprecated in Python 3 in favor of find_spec().
+    # For the purposes of this finder (i.e. being present
+    # on sys.meta_path but having no other import
+    # system functionality), the two methods are identical.
+    find_module = find_spec
+
+
+def pypy_partial(val):
+    """
+    Adjust for variable stacklevel on partial under PyPy.
+
+    Workaround for #327.
+    """
+    is_pypy = platform.python_implementation() == 'PyPy'
+    return val + is_pypy