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I had an unusual timezone related bug. I was adding "Night mode" to Nova Launcher, allowing a dark theme to be applied after sunset. To accurately calculate sunrise/sunset the location permission is required, but that's the only thing Nova Launcher needs the permission for, and only Android 6.0+ has runtime (optional) permissions so I didn't want to force the permission on everybody and needed a fallback. I knew that time zones aren't offsets but locations (ish) and for calculating sunrise/sunset they should be close enough. Nova pulls the device's time zone (something like America/Chicago ), maps it to a lat/long, and calculates the sunrise/sunset. It just depends on how accurate the timezone data is. Public beta went fine, but stable release we start getting a small, but concerning, amount of emails from people saying that their icons won't load, or disappear, after the update. We're asking for information trying to find a pattern, but it's across different Android versions and devices. Finally we notice all the carriers are Canadian. Then it gets more specific, it's Winnipeg (turned out it was actually Manitoba, the province Winnipeg is in). First thing I test is setting my device timezone to America/Winnipeg, but everything works fine for me. We're getting some more device information from the reporters, and their timezone isn't America/Winnipeg. but America/Resolute. That must be close to Winnipeg right?
https://goo.gl/maps/E5vj5nHfJgu
Notice how far north it is.
https://www.timeanddate.com/astronomy/canada/resolute
And the sunrise/sunset times, or lack thereof... I actually anticipated this, and there was some code to just use hard coded times for cities too far north to have a sane sunrise/sunset. However either that code broke later, or it only worked with GPS coordinates, and I assumed all the timezones were safe. I don't know why carriers in Winnipeg report the timezone as Resolute, but the fix came in two stages. 1) Properly handle locations that don't have sane sunrise/sunset times. and 2) Treat America/Resolute as America/Winnipeg |