Leap seconds definitely add way more complexity/uncertainty when dealing with timestamps in the future. I once made a program that would output the amount of ti

Leap seconds definitely add way more complexity/uncertainty when dealing with timestamps in the future. I once made a program that would output the amount of time remaining until some time in the future (with the future time represented as a Unix timestamp). I realized that it is simply not possible to report the number of seconds until an event >6 months in the future because we simply don't know if there might be a leap second or not between now and the time in the future. Perhaps the best approach for users would be to smear any leap seconds that are announced so it never has a hard jump, but it's still not ideal because if you really want to count down to the future time you simply can't.