[3.11] gh-93820: Pickle enum.Flag by name (GH-93891). (GH-94288)

(cherry picked from commit 536985814a7116f14c9bc90aa1b3e3d36d5b2367)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

1 files changed, 15 insertions, 1 deletions

diff --git a/Lib/enum.py b/Lib/enum.py
index 5bd4da9..e11093c 100644
--- a/Lib/enum.py
+++ b/Lib/enum.py
@@ -1286,7 +1286,21 @@ class Flag(Enum, boundary=STRICT):
     """
 
     def __reduce_ex__(self, proto):
-        return self.__class__, (self._value_, )
+        cls = self.__class__
+        unknown = self._value_ & ~cls._flag_mask_
+        member_value = self._value_ & cls._flag_mask_
+        if unknown and member_value:
+            return _or_, (cls(member_value), unknown)
+        for val in _iter_bits_lsb(member_value):
+            rest = member_value & ~val
+            if rest:
+                return _or_, (cls(rest), cls._value2member_map_.get(val))
+            else:
+                break
+        if self._name_ is None:
+            return cls, (self._value_,)
+        else:
+            return getattr, (cls, self._name_)
 
     _numeric_repr_ = repr