[3.12] [Enum] update class creation for RuntimeError changes (GH-111815) (GH-112526)

miss-islington · ethanfurman · web-flow · commit 749c8fdafbc9 · 2023-11-29T13:49:52.000-08:00
(cherry picked from commit f9e6ce0) Co-authored-by: Ethan Furman <ethan@stoneleaf.us>
diff --git a/Doc/howto/enum.rst b/Doc/howto/enum.rst
@@ -1439,7 +1439,6 @@ alias::
     Traceback (most recent call last):
       ...
     ValueError: aliases not allowed in DuplicateFreeEnum:  'GRENE' --> 'GREEN'
-    Error calling __set_name__ on '_proto_member' instance 'GRENE' in 'Color'
 
 .. note::
 
diff --git a/Lib/enum.py b/Lib/enum.py
@@ -581,12 +581,16 @@ def __new__(metacls, cls, bases, classdict, *, boundary=None, _simple=False, **k
         try:
             exc = None
             enum_class = super().__new__(metacls, cls, bases, classdict, **kwds)
-        except RuntimeError as e:
-            # any exceptions raised by member.__new__ will get converted to a
-            # RuntimeError, so get that original exception back and raise it instead
-            exc = e.__cause__ or e
+        except Exception as e:
+            # since 3.12 the line "Error calling __set_name__ on '_proto_member' instance ..."
+            # is tacked on to the error instead of raising a RuntimeError
+            # recreate the exception to discard
+            exc = type(e)(str(e))
+            exc.__cause__ = e.__cause__
+            exc.__context__ = e.__context__
+            tb = e.__traceback__
         if exc is not None:
-            raise exc
+            raise exc.with_traceback(tb)
         #
         # update classdict with any changes made by __init_subclass__
         classdict.update(enum_class.__dict__)
