gh-102549: [Enum] fail enum creation when data type raises in __init__ (GH-103149)

(cherry picked from commit 2a4d8c0a9e88f45047da640ce5a92b304d2d39b1)

Co-authored-by: Ethan Furman <ethan@stoneleaf.us>

1 files changed, 11 insertions, 14 deletions

diff --git a/Lib/enum.py b/Lib/enum.py
index 9138e50..13da287 100644
--- a/Lib/enum.py
+++ b/Lib/enum.py
@@ -250,23 +250,20 @@ class _proto_member:
             args = (args, )     # wrap it one more time
         if not enum_class._use_args_:
             enum_member = enum_class._new_member_(enum_class)
-            if not hasattr(enum_member, '_value_'):
+        else:
+            enum_member = enum_class._new_member_(enum_class, *args)
+        if not hasattr(enum_member, '_value_'):
+            if enum_class._member_type_ is object:
+                enum_member._value_ = value
+            else:
                 try:
                     enum_member._value_ = enum_class._member_type_(*args)
                 except Exception as exc:
-                    enum_member._value_ = value
-        else:
-            enum_member = enum_class._new_member_(enum_class, *args)
-            if not hasattr(enum_member, '_value_'):
-                if enum_class._member_type_ is object:
-                    enum_member._value_ = value
-                else:
-                    try:
-                        enum_member._value_ = enum_class._member_type_(*args)
-                    except Exception as exc:
-                        raise TypeError(
-                                '_value_ not set in __new__, unable to create it'
-                                ) from None
+                    new_exc = TypeError(
+                            '_value_ not set in __new__, unable to create it'
+                            )
+                    new_exc.__cause__ = exc
+                    raise new_exc
         value = enum_member._value_
         enum_member._name_ = member_name
         enum_member.__objclass__ = enum_class