bpo-39587: Enum - use correct mixed-in data type (GH-22263) (GH-22266)
(cherry picked from commit bff01f3a3aac0c15fe8fbe8b2f561f7927d117a1)
diff --git a/Lib/enum.py b/Lib/enum.py
index 49b552b..9dfba3c 100644
--- a/Lib/enum.py
+++ b/Lib/enum.py
@@ -481,14 +481,25 @@
return object, Enum
def _find_data_type(bases):
+ data_types = []
for chain in bases:
+ candidate = None
for base in chain.__mro__:
if base is object:
continue
elif '__new__' in base.__dict__:
if issubclass(base, Enum):
continue
- return base
+ data_types.append(candidate or base)
+ break
+ elif not issubclass(base, Enum):
+ candidate = base
+ if len(data_types) > 1:
+ raise TypeError('too many data types: %r' % data_types)
+ elif data_types:
+ return data_types[0]
+ else:
+ return None
# ensure final parent class is an Enum derivative, find any concrete
# data type, and check that Enum has no members