Bug report

The default behaviour of Flag enums has chenged between Python v3.10 and v3.11

Your environment

Python v3.11rc2 on macOS

The following script...

from enum import Flag

class MethodHint(Flag):
    HiddenText = 0x10
    DigitsOnly = 0x01
    LettersOnly = 0x02
    OnlyMask = 0x0f

print(MethodHint.HiddenText|MethodHint.OnlyMask)

...raises a ValueError in v3.11 and prints...

MethodHint.HiddenText|OnlyMask|LettersOnly|DigitsOnly

in v3.10.

While it's not particularly sensible to bitwise-or a mask it is a significant change of behaviour without a deprecation period.

It will be common to have a mask value that covers more bits than currently defined when allowing for future expansion of the flags.