GH-104898: Add __slots__ to os.PathLike (GH-104899)

Lib/os.py

@@ -1079,6 +1079,8 @@ class PathLike(abc.ABC):
 
     """Abstract base class for implementing the file system path protocol."""
 
+    __slots__ = ()
+
     @abc.abstractmethod
     def __fspath__(self):
         """Return the file system path representation of the object."""

Lib/pathlib.py

@@ -233,7 +233,7 @@ class _PathParents(Sequence):
         return "<{}.parents>".format(type(self._path).__name__)
 
 
-class PurePath(object):
+class PurePath(os.PathLike):
     """Base class for manipulating paths without I/O.
 
     PurePath represents a filesystem path and offers operations which
@@ -707,10 +707,6 @@ class PurePath(object):
                 return False
         return True
 
-# Can't subclass os.PathLike from PurePath and keep the constructor
-# optimizations in PurePath.__slots__.
-os.PathLike.register(PurePath)
-
 
 class PurePosixPath(PurePath):
     """PurePath subclass for non-Windows systems.

Lib/test/test_os.py

@@ -4640,6 +4640,12 @@ class TestPEP519(unittest.TestCase):
     def test_pathlike_class_getitem(self):
         self.assertIsInstance(os.PathLike[bytes], types.GenericAlias)
 
+    def test_pathlike_subclass_slots(self):
+        class A(os.PathLike):
+            __slots__ = ()
+            def __fspath__(self):
+                return ''
+        self.assertFalse(hasattr(A(), '__dict__'))
 
 class TimesTests(unittest.TestCase):
     def test_times(self):

Misc/NEWS.d/next/Library/2023-05-24-22-50-21.gh-issue-104898.UbT2S4.rst

@@ -0,0 +1 @@
+Add missing :attr:`~object.__slots__` to :class:`os.PathLike`.