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