bpo-44242: [Enum] improve error messages (GH-26669)
(cherry picked from commit c956734d7af83ad31f847d31d0d26df087add9a4)
Co-authored-by: Ethan Furman <ethan@stoneleaf.us>
Co-authored-by: Ethan Furman <ethan@stoneleaf.us>
diff --git a/Lib/enum.py b/Lib/enum.py
index 5263e51..bf3460c 100644
--- a/Lib/enum.py
+++ b/Lib/enum.py
@@ -1,5 +1,7 @@
import sys
from types import MappingProxyType, DynamicClassAttribute
+from operator import or_ as _or_
+from functools import reduce
from builtins import property as _bltin_property, bin as _bltin_bin
@@ -97,6 +99,9 @@ def _iter_bits_lsb(num):
yield b
num ^= b
+def show_flag_values(value):
+ return list(_iter_bits_lsb(value))
+
def bin(num, max_bits=None):
"""
Like built-in bin(), except negative values are represented in
@@ -1601,14 +1606,16 @@ def __call__(self, enumeration):
else:
raise Exception('verify: unknown type %r' % enum_type)
if missing:
- raise ValueError('invalid %s %r: missing values %s' % (
+ raise ValueError(('invalid %s %r: missing values %s' % (
enum_type, cls_name, ', '.join((str(m) for m in missing)))
- )
+ )[:256])
+ # limit max length to protect against DOS attacks
elif check is NAMED_FLAGS:
# examine each alias and check for unnamed flags
member_names = enumeration._member_names_
member_values = [m.value for m in enumeration]
- missing = []
+ missing_names = []
+ missing_value = 0
for name, alias in enumeration._member_map_.items():
if name in member_names:
# not an alias
@@ -1616,16 +1623,22 @@ def __call__(self, enumeration):
values = list(_iter_bits_lsb(alias.value))
missed = [v for v in values if v not in member_values]
if missed:
- plural = ('', 's')[len(missed) > 1]
- a = ('a ', '')[len(missed) > 1]
- missing.append('%r is missing %snamed flag%s for value%s %s' % (
- name, a, plural, plural,
- ', '.join(str(v) for v in missed)
- ))
- if missing:
+ missing_names.append(name)
+ missing_value |= reduce(_or_, missed)
+ if missing_names:
+ if len(missing_names) == 1:
+ alias = 'alias %s is missing' % missing_names[0]
+ else:
+ alias = 'aliases %s and %s are missing' % (
+ ', '.join(missing_names[:-1]), missing_names[-1]
+ )
+ if _is_single_bit(missing_value):
+ value = 'value 0x%x' % missing_value
+ else:
+ value = 'combined values of 0x%x' % missing_value
raise ValueError(
- 'invalid Flag %r: %s'
- % (cls_name, '; '.join(missing))
+ 'invalid Flag %r: %s %s [use `enum.show_flag_values(value)` for details]'
+ % (cls_name, alias, value)
)
return enumeration
diff --git a/Lib/test/test_enum.py b/Lib/test/test_enum.py
index 9a7882b..ceb0da8 100644
--- a/Lib/test/test_enum.py
+++ b/Lib/test/test_enum.py
@@ -2158,9 +2158,6 @@ def __init__(self, *args):
self._valid = True
@classmethod
def _missing_(cls, value):
- # encountered an unknown value!
- # Luckily I'm a LenientStrEnum, so I won't crash just yet.
- # You might want to add a new case though.
unknown = cls._member_type_.__new__(cls, value)
unknown._valid = False
unknown._name_ = value.upper()
@@ -3586,7 +3583,7 @@ class Bizarre(Flag):
self.assertEqual(Bizarre.d.value, 6)
with self.assertRaisesRegex(
ValueError,
- "invalid Flag 'Bizarre': 'b' is missing named flags for values 1, 2; 'd' is missing a named flag for value 2",
+ "invalid Flag 'Bizarre': aliases b and d are missing combined values of 0x3 .use `enum.show_flag_values.value.` for details.",
):
@verify(NAMED_FLAGS)
class Bizarre(Flag):
@@ -3594,6 +3591,7 @@ class Bizarre(Flag):
c = 4
d = 6
#
+ self.assertEqual(enum.show_flag_values(3), [1, 2])
class Bizarre(IntFlag):
b = 3
c = 4
@@ -3604,13 +3602,13 @@ class Bizarre(IntFlag):
self.assertEqual(Bizarre.d.value, 6)
with self.assertRaisesRegex(
ValueError,
- "invalid Flag 'Bizarre': 'b' is missing named flags for values 1, 2; 'd' is missing a named flag for value 2",
+ "invalid Flag 'Bizarre': alias d is missing value 0x2 .use `enum.show_flag_values.value.` for details.",
):
@verify(NAMED_FLAGS)
class Bizarre(IntFlag):
- b = 3
c = 4
d = 6
+ self.assertEqual(enum.show_flag_values(2), [2])
def test_unique_clean(self):
@verify(UNIQUE)
@@ -3877,7 +3875,7 @@ class Missing:
class MiscTestCase(unittest.TestCase):
def test__all__(self):
- support.check__all__(self, enum, not_exported={'bin'})
+ support.check__all__(self, enum, not_exported={'bin', 'show_flag_values'})
# These are unordered here on purpose to ensure that declaration order