Convert some already generic things to GenericAlias to be consistent (p…

…ython#14)

Lib/os.py

@@ -27,6 +27,7 @@
 import stat as st
 
 from _collections_abc import _check_methods
+from types import GenericAlias
 
 _names = sys.builtin_module_names
 
@@ -1060,8 +1061,9 @@ def __subclasshook__(cls, subclass):
             return _check_methods(subclass, '__fspath__')
         return NotImplemented
 
-    def __class_getitem__(cls, type):
-        return cls
+    def __class_getitem__(cls, item):
+        """Internal: PEP 585."""
+        return GenericAlias(cls, item)
 
 
 if name == 'nt':

Lib/subprocess.py

@@ -52,6 +52,7 @@
 import warnings
 import contextlib
 from time import monotonic as _time
+import types
 
 try:
     import pwd
@@ -446,17 +447,9 @@ def __repr__(self):
             args.append('stderr={!r}'.format(self.stderr))
         return "{}({})".format(type(self).__name__, ', '.join(args))
 
-    def __class_getitem__(cls, type):
-        """Provide minimal support for using this class as generic
-        (for example in type annotations).
-
-        See PEP 484 and PEP 560 for more details. For example,
-        `CompletedProcess[bytes]` is a valid expression at runtime
-        (type argument `bytes` indicates the type used for stdout).
-        Note, no type checking happens at runtime, but a static type
-        checker can be used.
-        """
-        return cls
+    def __class_getitem__(cls, item):
+        """Internal: PEP 585."""
+        return types.GenericAlias(cls, item)
 
 
     def check_returncode(self):
@@ -1000,16 +993,9 @@ def __repr__(self):
             obj_repr = obj_repr[:76] + "...>"
         return obj_repr
 
-    def __class_getitem__(cls, type):
-        """Provide minimal support for using this class as generic
-        (for example in type annotations).
-
-        See PEP 484 and PEP 560 for more details. For example, `Popen[bytes]`
-        is a valid expression at runtime (type argument `bytes` indicates the
-        type used for stdout). Note, no type checking happens at runtime, but
-        a static type checker can be used.
-        """
-        return cls
+    def __class_getitem__(cls, item):
+        """Internal: PEP 585."""
+        return types.GenericAlias(cls, item)
 
     @property
     def universal_newlines(self):

Lib/tempfile.py

@@ -44,6 +44,7 @@
 import errno as _errno
 from random import Random as _Random
 import sys as _sys
+import types as _types
 import weakref as _weakref
 import _thread
 _allocate_lock = _thread.allocate_lock
@@ -643,17 +644,9 @@ def __init__(self, max_size=0, mode='w+b', buffering=-1,
                                    'encoding': encoding, 'newline': newline,
                                    'dir': dir, 'errors': errors}
 
-    def __class_getitem__(cls, type):
-        """Provide minimal support for using this class as generic
-        (for example in type annotations).
-
-        See PEP 484 and PEP 560 for more details. For example,
-        `SpooledTemporaryFile[str]` is a valid expression at runtime (type
-        argument `str` indicates whether the file is open in bytes or text
-        mode). Note, no type checking happens at runtime, but a static type
-        checker can be used.
-        """
-        return cls
+    def __class_getitem__(cls, item):
+        """Internal: PEP 585."""
+        return _types.GenericAlias(cls, item)
 
     def _check(self, file):
         if self._rolled: return

Lib/test/test_os.py

@@ -25,6 +25,7 @@
 import tempfile
 import threading
 import time
+import types
 import unittest
 import uuid
 import warnings
@@ -4080,7 +4081,7 @@ class A(os.PathLike):
         self.assertTrue(issubclass(FakePath, os.PathLike))
 
     def test_pathlike_class_getitem(self):
-        self.assertIs(os.PathLike[bytes], os.PathLike)
+        self.assertIsInstance(os.PathLike[bytes], types.GenericAlias)
 
 
 class TimesTests(unittest.TestCase):

Lib/test/test_subprocess.py

@@ -11,6 +11,7 @@
 import tempfile
 import time
 import traceback
+import types
 import selectors
 import sysconfig
 import select
@@ -1436,8 +1437,8 @@ def test_file_not_found_with_bad_cwd(self):
         self.assertEqual(c.exception.filename, '/some/nonexistent/directory')
 
     def test_class_getitems(self):
-        self.assertIs(subprocess.Popen[bytes], subprocess.Popen)
-        self.assertIs(subprocess.CompletedProcess[str], subprocess.CompletedProcess)
+        self.assertIsInstance(subprocess.Popen[bytes], types.GenericAlias)
+        self.assertIsInstance(subprocess.CompletedProcess[str], types.GenericAlias)
 
 class RunFuncTestCase(BaseTestCase):
     def run_python(self, code, **kwargs):

Lib/test/test_tempfile.py

@@ -10,6 +10,7 @@
 import warnings
 import contextlib
 import stat
+import types
 import weakref
 from unittest import mock
 
@@ -1230,8 +1231,8 @@ def test_truncate_with_size_parameter(self):
         self.assertEqual(os.fstat(f.fileno()).st_size, 20)
 
     def test_class_getitem(self):
-        self.assertIs(tempfile.SpooledTemporaryFile[bytes],
-                      tempfile.SpooledTemporaryFile)
+        self.assertIsInstance(tempfile.SpooledTemporaryFile[bytes],
+                      types.GenericAlias)
 
 if tempfile.NamedTemporaryFile is not tempfile.TemporaryFile: