gh-102558: [Enum] fix AttributeError during member repr() (GH-102601)

(cherry picked from commit bd063756b3)

Co-authored-by: Dong-hee Na <donghee.na@python.org>

Lib/enum.py

@@ -1187,6 +1187,8 @@ def _missing_(cls, value):
         return None
 
     def __repr__(self):
+        if not isinstance(self, Enum):
+            return repr(self)
         v_repr = self.__class__._value_repr_ or repr
         return "<%s.%s: %s>" % (self.__class__.__name__, self._name_, v_repr(self._value_))
 

Lib/test/test_enum.py

@@ -11,7 +11,7 @@
 import builtins as bltns
 from collections import OrderedDict
 from datetime import date
-from enum import Enum, IntEnum, StrEnum, EnumType, Flag, IntFlag, unique, auto
+from enum import Enum, EnumMeta, 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, _iter_bits_lsb
@@ -632,6 +632,13 @@ class MySubEnum(MyEnum):
             theother = auto()
         self.assertEqual(repr(MySubEnum.that), "My name is that.")
 
+    def test_multiple_superclasses_repr(self):
+        class _EnumSuperClass(metaclass=EnumMeta):
+            pass
+        class E(_EnumSuperClass, Enum):
+            A = 1
+        self.assertEqual(repr(E.A), "<E.A: 1>")
+
     def test_reversed_iteration_order(self):
         self.assertEqual(
                 list(reversed(self.MainEnum)),