gh-118650: Exclude _repr_* methods from Enum's _sunder_ reservation (GH-118651)

Author: chrysn

Lib/enum.py

@@ -365,7 +365,10 @@ def __setitem__(self, key, value):
                     '_generate_next_value_', '_numeric_repr_', '_missing_', '_ignore_',
                     '_iter_member_', '_iter_member_by_value_', '_iter_member_by_def_',
                     '_add_alias_', '_add_value_alias_',
-                    ):
+                    # While not in use internally, those are common for pretty
+                    # printing and thus excluded from Enum's reservation of
+                    # _sunder_ names
+                    ) and not key.startswith('_repr_'):
                 raise ValueError(
                         '_sunder_ names, such as %r, are reserved for future Enum use'
                         % (key, )

Misc/NEWS.d/next/Library/2024-05-06-16-52-40.gh-issue-118650.qKz5lp.rst

@@ -0,0 +1,2 @@
+The ``enum`` module allows method named ``_repr_*`` to be defined on
+``Enum`` types.