pythongh-93820: Pickle enum.Flag by name

Author: serhiy-storchaka

Lib/enum.py

@@ -1370,7 +1370,16 @@ class Flag(Enum, boundary=STRICT):
     """
 
     def __reduce_ex__(self, proto):
-        return self.__class__, (self._value_, )
+        for m in self:
+            rest = self._value_ & ~m._value_
+            if rest:
+                return _or_, (m, self.__class__(rest))
+            else:
+                break
+        if self._name_ is None:
+            return self.__class__, (self._value_,)
+        else:
+            return getattr, (self.__class__, self._name_)
 
     _numeric_repr_ = repr
 

Lib/test/test_enum.py

@@ -65,10 +65,27 @@ class FloatStooges(float, Enum):
     class FlagStooges(Flag):
         LARRY = 1
         CURLY = 2
-        MOE = 3
+        MOE = 4
 except Exception as exc:
     FlagStooges = exc
 
+class FlagStoogesWithZero(Flag):
+    NOFLAG = 0
+    LARRY = 1
+    CURLY = 2
+    MOE = 4
+
+class IntFlagStooges(IntFlag):
+    LARRY = 1
+    CURLY = 2
+    MOE = 4
+
+class IntFlagStoogesWithZero(IntFlag):
+    NOFLAG = 0
+    LARRY = 1
+    CURLY = 2
+    MOE = 4
+
 # for pickle test and subclass tests
 class Name(StrEnum):
     BDFL = 'Guido van Rossum'
@@ -2956,9 +2973,32 @@ def test_programatic_function_from_dict(self):
     def test_pickle(self):
         if isinstance(FlagStooges, Exception):
             raise FlagStooges
-        test_pickle_dump_load(self.assertIs, FlagStooges.CURLY|FlagStooges.MOE)
+        test_pickle_dump_load(self.assertIs, FlagStooges.CURLY)
+        test_pickle_dump_load(self.assertEqual,
+                        FlagStooges.CURLY|FlagStooges.MOE)
+        test_pickle_dump_load(self.assertEqual,
+                        FlagStooges.CURLY&~FlagStooges.CURLY)
         test_pickle_dump_load(self.assertIs, FlagStooges)
 
+        test_pickle_dump_load(self.assertIs, FlagStoogesWithZero.CURLY)
+        test_pickle_dump_load(self.assertEqual,
+                        FlagStoogesWithZero.CURLY|FlagStoogesWithZero.MOE)
+        test_pickle_dump_load(self.assertIs, FlagStoogesWithZero.NOFLAG)
+
+        test_pickle_dump_load(self.assertIs, IntFlagStooges.CURLY)
+        test_pickle_dump_load(self.assertEqual,
+                        IntFlagStooges.CURLY|IntFlagStooges.MOE)
+        test_pickle_dump_load(self.assertEqual,
+                        IntFlagStooges.CURLY|IntFlagStooges.MOE|0x30)
+        test_pickle_dump_load(self.assertEqual, IntFlagStooges(0))
+        test_pickle_dump_load(self.assertEqual, IntFlagStooges(0x30))
+        test_pickle_dump_load(self.assertIs, IntFlagStooges)
+
+        test_pickle_dump_load(self.assertIs, IntFlagStoogesWithZero.CURLY)
+        test_pickle_dump_load(self.assertEqual,
+                        IntFlagStoogesWithZero.CURLY|IntFlagStoogesWithZero.MOE)
+        test_pickle_dump_load(self.assertIs, IntFlagStoogesWithZero.NOFLAG)
+
     @unittest.skipIf(
             python_version >= (3, 12),
             '__contains__ now returns True/False for all inputs',

Misc/NEWS.d/next/Library/2022-06-16-11-16-53.gh-issue-93820.00X0Y5.rst

@@ -0,0 +1 @@
+Pickle :class:`enum.Flag` by name.