gh-78157: [Enum] nested classes will not be members in 3.13 (GH-92366)

- add member() and nonmember() functions
- add deprecation warning for internal classes in enums not
  becoming members in 3.13

Co-authored-by: edwardcwang

Lib/test/test_enum.py

@@ -12,6 +12,7 @@ from datetime import date
 from enum import Enum, IntEnum, StrEnum, EnumType, Flag, IntFlag, unique, auto
 from enum import STRICT, CONFORM, EJECT, KEEP, _simple_enum, _test_simple_enum
 from enum import verify, UNIQUE, CONTINUOUS, NAMED_FLAGS, ReprEnum
+from enum import member, nonmember
 from io import StringIO
 from pickle import dumps, loads, PicklingError, HIGHEST_PROTOCOL
 from test import support
@@ -938,6 +939,146 @@ class TestSpecial(unittest.TestCase):
             raise Theory
         self.assertEqual(Theory.__qualname__, 'spanish_inquisition')
 
+    def test_enum_of_types(self):
+        """Support using Enum to refer to types deliberately."""
+        class MyTypes(Enum):
+            i = int
+            f = float
+            s = str
+        self.assertEqual(MyTypes.i.value, int)
+        self.assertEqual(MyTypes.f.value, float)
+        self.assertEqual(MyTypes.s.value, str)
+        class Foo:
+            pass
+        class Bar:
+            pass
+        class MyTypes2(Enum):
+            a = Foo
+            b = Bar
+        self.assertEqual(MyTypes2.a.value, Foo)
+        self.assertEqual(MyTypes2.b.value, Bar)
+        class SpamEnumNotInner:
+            pass
+        class SpamEnum(Enum):
+            spam = SpamEnumNotInner
+        self.assertEqual(SpamEnum.spam.value, SpamEnumNotInner)
+
+    @unittest.skipIf(
+            python_version >= (3, 13),
+            'inner classes are not members',
+            )
+    def test_nested_classes_in_enum_are_members(self):
+        """
+        Check for warnings pre-3.13
+        """
+        with self.assertWarnsRegex(DeprecationWarning, 'will not become a member'):
+            class Outer(Enum):
+                a = 1
+                b = 2
+                class Inner(Enum):
+                    foo = 10
+                    bar = 11
+        self.assertTrue(isinstance(Outer.Inner, Outer))
+        self.assertEqual(Outer.a.value, 1)
+        self.assertEqual(Outer.Inner.value.foo.value, 10)
+        self.assertEqual(
+            list(Outer.Inner.value),
+            [Outer.Inner.value.foo, Outer.Inner.value.bar],
+            )
+        self.assertEqual(
+            list(Outer),
+            [Outer.a, Outer.b, Outer.Inner],
+            )
+
+    @unittest.skipIf(
+            python_version < (3, 13),
+            'inner classes are still members',
+            )
+    def test_nested_classes_in_enum_are_not_members(self):
+        """Support locally-defined nested classes."""
+        class Outer(Enum):
+            a = 1
+            b = 2
+            class Inner(Enum):
+                foo = 10
+                bar = 11
+        self.assertTrue(isinstance(Outer.Inner, type))
+        self.assertEqual(Outer.a.value, 1)
+        self.assertEqual(Outer.Inner.foo.value, 10)
+        self.assertEqual(
+            list(Outer.Inner),
+            [Outer.Inner.foo, Outer.Inner.bar],
+            )
+        self.assertEqual(
+            list(Outer),
+            [Outer.a, Outer.b],
+            )
+
+    def test_nested_classes_in_enum_with_nonmember(self):
+        class Outer(Enum):
+            a = 1
+            b = 2
+            @nonmember
+            class Inner(Enum):
+                foo = 10
+                bar = 11
+        self.assertTrue(isinstance(Outer.Inner, type))
+        self.assertEqual(Outer.a.value, 1)
+        self.assertEqual(Outer.Inner.foo.value, 10)
+        self.assertEqual(
+            list(Outer.Inner),
+            [Outer.Inner.foo, Outer.Inner.bar],
+            )
+        self.assertEqual(
+            list(Outer),
+            [Outer.a, Outer.b],
+            )
+
+    def test_enum_of_types_with_nonmember(self):
+        """Support using Enum to refer to types deliberately."""
+        class MyTypes(Enum):
+            i = int
+            f = nonmember(float)
+            s = str
+        self.assertEqual(MyTypes.i.value, int)
+        self.assertTrue(MyTypes.f is float)
+        self.assertEqual(MyTypes.s.value, str)
+        class Foo:
+            pass
+        class Bar:
+            pass
+        class MyTypes2(Enum):
+            a = Foo
+            b = nonmember(Bar)
+        self.assertEqual(MyTypes2.a.value, Foo)
+        self.assertTrue(MyTypes2.b is Bar)
+        class SpamEnumIsInner:
+            pass
+        class SpamEnum(Enum):
+            spam = nonmember(SpamEnumIsInner)
+        self.assertTrue(SpamEnum.spam is SpamEnumIsInner)
+
+    def test_nested_classes_in_enum_with_member(self):
+        """Support locally-defined nested classes."""
+        class Outer(Enum):
+            a = 1
+            b = 2
+            @member
+            class Inner(Enum):
+                foo = 10
+                bar = 11
+        self.assertTrue(isinstance(Outer.Inner, Outer))
+        self.assertEqual(Outer.a.value, 1)
+        self.assertEqual(Outer.Inner.value.foo.value, 10)
+        self.assertEqual(
+            list(Outer.Inner.value),
+            [Outer.Inner.value.foo, Outer.Inner.value.bar],
+            )
+        self.assertEqual(
+            list(Outer),
+            [Outer.a, Outer.b, Outer.Inner],
+            )
+
     def test_enum_with_value_name(self):
         class Huh(Enum):
             name = 1