Wrong instances for events starting Sunday and recurring on multiple weekdays every n weeks

UNCONFIRMED
Unassigned

Status

Calendar
Internal Components
UNCONFIRMED
17 days ago
17 days ago

People

(Reporter: rsjtdrjgfuzkfg (Dirk Steinmetz), Unassigned)

Tracking

Details

Attachments

(1 attachment)

(Reporter)

Description

17 days ago
Created attachment 8939470 [details]
Reproduction.ics

Recurrence rules causing a repetition on multiple weekdays every n weeks depend on the first day of the week (WKST, defaults to Monday). If an event with such a rule starts on a Sunday with default WKST, the event's instances are not calculated correctly.

STR:
0. Thunderbird 52 or 59a (current nightly) with Lightning installed, clean profile
1. Import the attached ics file to the Home calendar

Expected:
A repeating event is added, with the first instances being 2018-01-07, 2018-01-15, 2018-01-16, ...

Actual:
A repeating event is added, with the first instances being 2018-01-07, 2018-01-08, 2018-01-09, ...

It seems as if the week is identified according to Sunday as first day of the week (starting 2018-01-07) and then the instances are shifted (starting 2018-01-08). That way, there are 8 consecutive events in the first week...

Note that the example event can also be created through the UI: set start of Week to Monday and add a new event on a Sunday, repeating every 2 weeks on multiple days.
You need to log in before you can comment on or make changes to this bug.