[Bug] ValueError: RRULE UNTIL values must be specified in UTC when DTSTART is timezone-aware

[niccokunzmann]

Problem

Timezones and other components can have rrules that are timezone aware. Repetitions might be calculated with timezone awareness.

State now (2.9.0)

dateutil: rrule calculation cannot mix datetimes with timezones with datetimes without timezones

recurring-ical-events: This has been fixed in recurring-ical-events for the event/journal/todo repetition calculation based on dateutil's rrule. However, the icalendar library uses dateutil.rrule straight to create the timezones required without those fixes.

Proposal

My proposal would be to fix the code of dateutil so it can mix timezone awareness with non-timezone aware datetimes. The tests and examples from recurring-ical-events would be sufficient.

Example files

VTIMEZONE: Abfall_EG_1_Ost_2024.txt

See also:

• [BUG] VTIMEZONE to_tz results in ValueError: RRULE UNTIL values must be specified in UTC when DTSTART is timezone-aware collective/icalendar#708
• bug: RRULE Timezone must be in UTC format - ends in Z niccokunzmann/python-recurring-ical-events#28
• RRULE UNTIL values must be specified in UTC when DTSTART is timezone-aware niccokunzmann/python-recurring-ical-events#4
• Add support for all the parameters of RDATE #872
• rrule-parser fails on example-timezone definition in rfc5545 #1006