`date.strftime` and `datetime.strftime` format dates wrong in some locales.

petergraham

Bug report

Bug description:

date.strftime and datetime.strftime format dates wrong in some locales. For example, when the locale is Bulgaria the '%A' format string returns an incorrect value.

>>> locale.setlocale(locale.LC_TIME, 'bg')    # 'bg' is Bulgaria
>>> date_str = datetime.date(2025, 2, 25).strftime('%A') # %A is locale's day of the week
>>> date_str
'âòîðíèê'
>>> date_str.encode('cp1252').decode('cp1251')  # I think we're interpreting a cp1251 string as cp1252
'вторник'  # Google tells me this is Tuesday in Bulgarian

This also fails with the '%x' format string

I've only tested this on Windows.

My guess is that CPython is making a narrow character API call and using the wrong code page. It should be using the wide character call instead.

CPython versions tested on:

3.13

Operating systems tested on:

Windows