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Zero-duration time-based midnight-to-midnight same-day events will be set to all-day the next time you open the Event Editor

Affected version

  • OS: Fedora Silverblue 36.20221011.0, Fedora Workstation 41
  • GNOME calendar version: 43.0 via Flathub, nightly/48 via GNOME Nightly

Bug summary

When I try to add an event that's set at midnight, it gets added parsed as an all-day event the next time you open it for editing.

Steps to reproduce

  1. Click a cell in month view to add a new single-day event, click "Edit details"
    (edit by @jfft: or just use Ctrl+N directly).

  2. Type a name (title) for the event

  3. Switch from the "All Day" toggle to "Time Slot" and leave everything else at the defaults — i.e. leave "Starts" at the default time of 00:00.
    Edit by @jfft: with the git version as of 3793001b, this only happens if you also leave the "Ends" time at 00:00

  4. Click "Save" to add the event.

  5. Reopen the event in the event editor

What happened

The event gets saved as an all-day event.

  • Edit by @jfft: not strictly technically true: it correctly gets saved as a time-based event in the file format as per #889 (comment 2337742), however it resets the next time you open the editing GUI (this issue here, as per #889 (comment 2339371)) or reschedule the event via drag and drop (issue #1360).

If I go back to edit the event, untick "All Day" again, and save again, the same thing happens — it remains set as an all-day event even though I literally just unselected that.

  • Edit by @jfft: the problem seems to be that the event editor converts it to "All Day" when opening the event editor dialog.

Bonus "step 6" by @jfft with version 48: if you try to switch the event back to "Time Slot" and save, undefined behavior will happen; the event will disappear entirely even if it's still stored in the backend, because the start date ends up being after the end date (so then this ties into #1358), and behind the scenes you would get:

gcal_range_tree_add_range: assertion 'range' failed
gcal_range_new: assertion 'g_date_time_compare (range_start, range_end) <= 0' failed

See video below:

issue_889_heisenbug_with_nightly_from_2025-02-03

What did you expect to happen

I expected the event to get added as a partial-day event, starting at midnight, like what would happen if I add an event that is not exactly midnight-to-midnight (e.g. 00:01 start time).

Important notes for spec compliance, in the comments below:

Edited by Jeff Fortin