RRULE: Gracefully handle offset-naive and offset-aware datetimes

[htgoebel]

The following code fails with TypeError: can't compare offset-naive and offset-aware datetimes.

event = """
BEGIN:VCALENDAR
VERSION:2.0
BEGIN:VEVENT
DTSTART;VALUE=DATE:20130117
DTEND;VALUE=DATE:20130118
RRULE:FREQ=WEEKLY;UNTIL=20130330T230000Z;BYDAY=TH
SUMMARY:Meeting
END:VEVENT
END:VCALENDAR
""".strip()

import vobject

ev = vobject.readOne(event).vevent
ev.getrruleset(addRDate=True)

Traceback:

  File "…/site-packages/vobject/icalendar.py", line 501, in getrruleset
    if rruleset._rrule[-1][0] != adddtstart:
  File "…site-packages/dateutil/rrule.py", line 159, in __getitem__
    res = advance_iterator(gen)
  File "…/site-packages/dateutil/rrule.py", line 860, in _iter
    if until and res > until:
TypeError: can't compare offset-naive and offset-aware datetimes

Actual values are:

• res = datetime.datetime(2013, 1, 17, 0, 0) from DTSTART;VALUE=DATE:20130117
• until = datetime.datetime(2013, 3, 30, 23, 0, tzinfo=tzutc()) from RRULE:FREQ=WEEKLY;UNTIL=20130330T230000Z;BYDAY=TH

[htgoebel]

The cause of this problem seems to be at icalendar line 447:

rule = rrule.rrulestr(value, dtstart=dtstart)
until = rule._until

If dtstart has no timezone, util will have a time-zone (utc) (see below).

Just behind this place there is code handling the case that until.tzinfo != dtstart.tzinfo, but only if isinstance(dtstart, datetime.datetime). I assume the case isinstance(dtstart, datetime.date). needs to be handled here, too.

Insights from my debugging-session:

> …/site-packages/vobject/icalendar.py(447)getrruleset()
-> rule = rrule.rrulestr(value, dtstart=dtstart)
(Pdb) n
> …/site-packages/vobject/icalendar.py(448)getrruleset()
-> until = rule._until
(Pdb) p dtstart
datetime.date(2013, 1, 17)
(Pdb) p until
datetime.datetime(2013, 3, 30, 23, 0, tzinfo=tzutc())
(Pdb) p rule._tzinfo
None
(Pdb) p until.tzinfo
tzutc()