Bug report

According toISO-8601, a time of24:00 on a given date is a valid alternative to00:00 of the following date, however Python does not support this, raising the following error when attempted:ValueError: hour must be in 0..23.

This bug can be seen from multiple scenarios, specifically anything that internally calls the_check_time_fields function, such as the following:

>>>importdatetime>>>datetime.datetime(2022,1,2,24,0,0)# should be equivalent to 2022-01-03 00:00:00Traceback (mostrecentcalllast):File"<pyshell#2>",line1,in<module>datetime.datetime(2022,3,4,24,0,0)ValueError:hourmustbein0..23

The fix for this is relatively simple: have an explicit check within_check_time_fields for the scenario wherehour == 24 and minute == 0 and second == 0 and microsecond == 0, or more conciselyhour == 24 and not any((minute, second, microsecond)), and in this scenario increase the day by one (adjusting the week/month/year as necessary) and set the hour to 0.

I imagine thecheck_time_args C function would also have to be updated.

Your environment

• CPython versions tested on: 3.9.12, 3.10.7, 3.11.2 (presumably applies to all)
• Operating system and architecture: MacOS Ventura arm64 (presumably applies to all)

Linked PRs

• gh-102450: Add ISO-8601 alternative for midnight tofromisoformat() calls. #105856