bpo-41789: honor object overrides in Enum classes (GH-22250)

EnumMeta double-checks that `__repr__`, `__str__`, `__format__`, and `__reduce_ex__` are not the same as `object`'s, and replaces them if they are -- even if that replacement was intentionally done in the Enum being constructed. This patch fixes that. Automerge-Triggered-By: @ethanfurman

Author: ethanfurman

Lib/enum.py

@@ -250,7 +250,11 @@ def __new__(metacls, cls, bases, classdict):
 
  # double check that repr and friends are not the mixin's or various
  # things break (such as pickle)
+ # however, if the method is defined in the Enum itself, don't replace
+ # it
  for name in ('__repr__', '__str__', '__format__', '__reduce_ex__'):
+ if name in classdict:
+ continue
  class_method = getattr(enum_class, name)
  obj_method = getattr(member_type, name, None)
  enum_method = getattr(first_enum, name, None)

Lib/test/test_enum.py

@@ -560,6 +560,14 @@ def test_format_enum_str(self):
  self.assertFormatIsValue('{:>20}', Directional.WEST)
  self.assertFormatIsValue('{:<20}', Directional.WEST)
 
+ def test_object_str_override(self):
+ class Colors(Enum):
+ RED, GREEN, BLUE = 1, 2, 3
+ def __repr__(self):
+ return "test.%s" % (self._name_, )
+ __str__ = object.__str__
+ self.assertEqual(str(Colors.RED), 'test.RED')
+
  def test_enum_str_override(self):
  class MyStrEnum(Enum):
  def __str__(self):
@@ -602,7 +610,6 @@ def repr(self):
  class Huh(MyStr, MyInt, Enum):
  One = 1
 
-
  def test_hash(self):
  Season = self.Season
  dates = {}

Misc/NEWS.d/next/Library/2020-09-14-19-27-46.bpo-41789.pI_uZQ.rst

@@ -0,0 +1,2 @@
+Honor `object` overrides in `Enum` class creation (specifically, `__str__`,
+`__repr__`, `__format__`, and `__reduce_ex__`).