Easy way to check a time is a leap second

[chronotope]

Easy way to check a time is a leap second

[lifthrasiir]

This is intentional and (while not yet in the currently released version) documented. Can you clarify what is this issue about? I would like to close this issue if your concern is simply a missing documentation.

The core rationale is that you can assume that there is no such thing as a leap second; the exception is when you actually get a leap second (:60 in the formatted string or >=1 fractional seconds), in which case it behaves like an extra fractional second following the original second. Only when you want to check if it were actually a leap second, you can look at the excess fractional seconds or (in the future) convert from the leap second to the linear scale like TAI and vice versa.

[alex]

The undelrying issue I am experiencing is this: I am parsing ASN.1 UTCTime values, which have the format you see in my original example, except they don't allow leap seconds (60 in the second value), while chrono's %S format does. I then did the natural thing, which was to write .second() >= 60 and error out in that case, however, obviously that case is never encountered, because the data is in nanoseconds().

So, I suppose I have two questions/comments:

1. The fact that Display showed :60 but .seconds() wasn't 60 was confusing.
2. Is there some other way I should reject values for which %S parses 60 that's better than d.second() >= 59 && d.nanosecond() > 0?

[lifthrasiir]

1. I feel this is basically a documentation problem, which I'd like to resolve. I already mentioned that Timelike::second always returns a number less than 60 and Timelike::nanosecond would represent a leap second, but any elaboration would be welcoming (I planned to do so eventually).
2. d.nanosecond() >= 1_000_000_000 should be sufficient to detect a leap second. Would a method Timelike::is_leap_second be good to have? Having a magic number is not very good but I had no concrete example for that method until now.

[alex]

is_leap_second() would be a great solution, it'd be more readable and let me delete several lines of comments :-)

[pitdicker]

Renamed this issue.

Adding something like Timelike::is_leap_second seems easy?

[djc]

@alex -- it's been a while. Is this still of interest to you?

[alex]

I'm no longer using Chrono for this application, so it doesn't impact me directly.

I do think it'd be valuable to have an is leap second API though!