https://github.com/python/cpython/commit/49365bd110a254a6a304d2f880482bfeb2e4490d
commit: 49365bd110a254a6a304d2f880482bfeb2e4490d
branch: main
author: Ethan Furman <et...@stoneleaf.us>
committer: ethanfurman <et...@stoneleaf.us>
date: 2025-07-10T16:49:09-07:00
summary:
gh-107538: [Enum] fix handling of inverted/negative values (GH-132273)
* Fix flag mask inversion when unnamed flags exist.
For example:
class Flag(enum.Flag):
A = 0x01
B = 0x02
MASK = 0xff
~Flag.MASK is Flag(0)
* EJECT and KEEP flags (IntEnum is KEEP) use direct value.
* correct Flag inversion to only flip flag bits
IntFlag will flip all bits -- this only makes a difference in flag sets with
missing values.
* correct negative assigned values in flags
negative values are no longer used as-is, but become inverted; i.e.
class Y(self.enum_type):
A = auto()
B = auto()
C = ~A # aka ~1 aka 0b1 110 (from enum.bin()) aka 6
D = auto()
assert Y.C. is Y.B|Y.D
files:
A Misc/NEWS.d/next/Library/2023-07-05-14-34-10.gh-issue-105497.HU5u89.rst
A Misc/NEWS.d/next/Library/2025-04-08-07-25-10.gh-issue-107583.JGfbhq.rst
M Lib/enum.py
M Lib/test/test_enum.py
diff --git a/Lib/enum.py b/Lib/enum.py
index 01fecca3e5aac0..538b9cc8e96fc1 100644
--- a/Lib/enum.py
+++ b/Lib/enum.py
@@ -535,7 +535,7 @@ def __new__(metacls, cls, bases, classdict, *,
boundary=None, _simple=False, **k
# now set the __repr__ for the value
classdict['_value_repr_'] = metacls._find_data_repr_(cls, bases)
#
- # Flag structures (will be removed if final class is not a Flag
+ # Flag structures (will be removed if final class is not a Flag)
classdict['_boundary_'] = (
boundary
or getattr(first_enum, '_boundary_', None)
@@ -544,6 +544,29 @@ def __new__(metacls, cls, bases, classdict, *,
boundary=None, _simple=False, **k
classdict['_singles_mask_'] = 0
classdict['_all_bits_'] = 0
classdict['_inverted_'] = None
+ # check for negative flag values and invert if found (using
_proto_members)
+ if Flag is not None and bases and issubclass(bases[-1], Flag):
+ bits = 0
+ inverted = []
+ for n in member_names:
+ p = classdict[n]
+ if isinstance(p.value, int):
+ if p.value < 0:
+ inverted.append(p)
+ else:
+ bits |= p.value
+ elif p.value is None:
+ pass
+ elif isinstance(p.value, tuple) and p.value and
isinstance(p.value[0], int):
+ if p.value[0] < 0:
+ inverted.append(p)
+ else:
+ bits |= p.value[0]
+ for p in inverted:
+ if isinstance(p.value, int):
+ p.value = bits & p.value
+ else:
+ p.value = (bits & p.value[0], ) + p.value[1:]
try:
classdict['_%s__in_progress' % cls] = True
enum_class = super().__new__(metacls, cls, bases, classdict,
**kwds)
@@ -1487,7 +1510,10 @@ def _missing_(cls, value):
)
if value < 0:
neg_value = value
- value = all_bits + 1 + value
+ if cls._boundary_ in (EJECT, KEEP):
+ value = all_bits + 1 + value
+ else:
+ value = singles_mask & value
# get members and unknown
unknown = value & ~flag_mask
aliases = value & ~singles_mask
diff --git a/Lib/test/test_enum.py b/Lib/test/test_enum.py
index bbc7630fa83f45..2dd585f246d506 100644
--- a/Lib/test/test_enum.py
+++ b/Lib/test/test_enum.py
@@ -1002,12 +1002,18 @@ class OpenAB(self.enum_type):
self.assertIs(~(A|B), OpenAB(252))
self.assertIs(~AB_MASK, OpenAB(0))
self.assertIs(~OpenAB(0), AB_MASK)
+ self.assertIs(OpenAB(~4), OpenAB(251))
else:
self.assertIs(~A, B)
self.assertIs(~B, A)
+ self.assertIs(OpenAB(~1), B)
+ self.assertIs(OpenAB(~2), A)
self.assertIs(~(A|B), OpenAB(0))
self.assertIs(~AB_MASK, OpenAB(0))
self.assertIs(~OpenAB(0), (A|B))
+ self.assertIs(OpenAB(~3), OpenAB(0))
+ self.assertIs(OpenAB(~4), OpenAB(3))
+ self.assertIs(OpenAB(~33), B)
#
class OpenXYZ(self.enum_type):
X = 4
@@ -1031,6 +1037,9 @@ class OpenXYZ(self.enum_type):
self.assertIs(~X, Y|Z)
self.assertIs(~Y, X|Z)
self.assertIs(~Z, X|Y)
+ self.assertIs(OpenXYZ(~4), Y|Z)
+ self.assertIs(OpenXYZ(~2), X|Z)
+ self.assertIs(OpenXYZ(~1), X|Y)
self.assertIs(~(X|Y), Z)
self.assertIs(~(X|Z), Y)
self.assertIs(~(Y|Z), X)
@@ -1038,6 +1047,28 @@ class OpenXYZ(self.enum_type):
self.assertIs(~XYZ_MASK, OpenXYZ(0))
self.assertTrue(~OpenXYZ(0), (X|Y|Z))
+ def test_assigned_negative_value(self):
+ class X(self.enum_type):
+ A = auto()
+ B = auto()
+ C = A | B
+ D = ~A
+ self.assertEqual(list(X), [X.A, X.B])
+ self.assertIs(~X.A, X.B)
+ self.assertIs(X.D, X.B)
+ self.assertEqual(X.D.value, 2)
+ #
+ class Y(self.enum_type):
+ A = auto()
+ B = auto()
+ C = A | B
+ D = ~A
+ E = auto()
+ self.assertEqual(list(Y), [Y.A, Y.B, Y.E])
+ self.assertIs(~Y.A, Y.B|Y.E)
+ self.assertIs(Y.D, Y.B|Y.E)
+ self.assertEqual(Y.D.value, 6)
+
class TestPlainEnumClass(_EnumTests, _PlainOutputTests, unittest.TestCase):
enum_type = Enum
@@ -3680,6 +3711,8 @@ class SkipFlag(enum.Flag):
C = 4 | B
#
self.assertTrue(SkipFlag.C in (SkipFlag.A|SkipFlag.C))
+ self.assertTrue(SkipFlag.B in SkipFlag.C)
+ self.assertIs(SkipFlag(~1), SkipFlag.B)
self.assertRaisesRegex(ValueError, 'SkipFlag.. invalid value 42',
SkipFlag, 42)
#
class SkipIntFlag(enum.IntFlag):
@@ -3688,6 +3721,8 @@ class SkipIntFlag(enum.IntFlag):
C = 4 | B
#
self.assertTrue(SkipIntFlag.C in (SkipIntFlag.A|SkipIntFlag.C))
+ self.assertTrue(SkipIntFlag.B in SkipIntFlag.C)
+ self.assertIs(SkipIntFlag(~1), SkipIntFlag.B|SkipIntFlag.C)
self.assertEqual(SkipIntFlag(42).value, 42)
#
class MethodHint(Flag):
@@ -4727,6 +4762,8 @@ class Color(Flag):
BLUE = 4
WHITE = -1
# no error means success
+ self.assertEqual(list(Color.WHITE), [Color.RED, Color.GREEN,
Color.BLUE])
+ self.assertEqual(Color.WHITE.value, 7)
class TestInternals(unittest.TestCase):
diff --git
a/Misc/NEWS.d/next/Library/2023-07-05-14-34-10.gh-issue-105497.HU5u89.rst
b/Misc/NEWS.d/next/Library/2023-07-05-14-34-10.gh-issue-105497.HU5u89.rst
new file mode 100644
index 00000000000000..f4f2db08f73f50
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2023-07-05-14-34-10.gh-issue-105497.HU5u89.rst
@@ -0,0 +1 @@
+Fix flag mask inversion when unnamed flags exist.
diff --git
a/Misc/NEWS.d/next/Library/2025-04-08-07-25-10.gh-issue-107583.JGfbhq.rst
b/Misc/NEWS.d/next/Library/2025-04-08-07-25-10.gh-issue-107583.JGfbhq.rst
new file mode 100644
index 00000000000000..4235612627341b
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2025-04-08-07-25-10.gh-issue-107583.JGfbhq.rst
@@ -0,0 +1,4 @@
+Fix :class:`!Flag` inversion when flag set has missing values
+(:class:`!IntFlag` still flips all bits); fix negative assigned values
+during flag creation (both :class:`!Flag` and :class:`!IntFlag` ignore
+missing values).
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