bpo-44342: [Enum] fix data type search (GH-26667)

In an inheritance chain of

  int -> my_int -> final_int

the data type is now final_int (not my_int)
(cherry picked from commit 3a7cccf)

Co-authored-by: Ethan Furman <[email protected]>

Co-authored-by: Ethan Furman <[email protected]>

Author: miss-islington

Lib/enum.py

@@ -823,7 +823,7 @@ def _find_data_type(bases):
                         data_types.add(candidate or base)
                         break
                     else:
-                        candidate = base
+                        candidate = candidate or base
             if len(data_types) > 1:
                 raise TypeError('%r: too many data types: %r' % (class_name, data_types))
             elif data_types:

Lib/test/test_enum.py

@@ -658,6 +658,14 @@ class MyEnum(HexInt, enum.Enum):
             def __repr__(self):
                 return '<%s.%s: %r>' % (self.__class__.__name__, self._name_, self._value_)
         self.assertEqual(repr(MyEnum.A), '<MyEnum.A: 0x1>')
+        #
+        class SillyInt(HexInt):
+            pass
+        class MyOtherEnum(SillyInt, enum.Enum):
+            D = 4
+            E = 5
+            F = 6
+        self.assertIs(MyOtherEnum._member_type_, SillyInt)
 
     def test_too_many_data_types(self):
         with self.assertRaisesRegex(TypeError, 'too many data types'):