List where libical doesn't fully support all the features described in the RFCs.

Contributions to help us fix these limitations are welcome.

RFC 5545

Recurrence Rule section 3.3.10

• BYSETPOS is only supported for MONTHLY and YEARLY frequencies (https://github.com/libical/libical/issues/795)

• FREQ=YEARLY, BYYEARDAY can't be combined with BYWEEKNO, BYMONTH or BYMONTHDAY

  ref: https://github.com/libical/libical/blob/cfd401b9d043214395888de1d9daf52263e3245b/src/libical/icalrecur.c#L2882

• FREQ=YEARLY, BYWEEKNO can't be combined with BYYEARDAY, BYMONTH or BYMONTHDAY

  ref: https://github.com/libical/libical/blob/cfd401b9d043214395888de1d9daf52263e3245b/src/libical/icalrecur.c#L2928

Recurrence Rule sections 3.8.5.3, DURATION 3.3.6

• The lib (e.g. icalcomponent_foreach_recurrence(), icalcomponent_get_dtend()) does not differentiate between nominal and exact durations. According to the RFC, when a component's duration is specified using the DURATION property rather than DTEND, the nominal duration must be used to calculate each recurrence's duration. However, the current implementation always uses the exact duration, which can cause discrepancies if a recurrence spans a daylight saving time transition.

  ref: https://github.com/libical/libical/issues/630