Bug in Instant.plus(Duration) on JS for large Instants and small Durations

[lukellmann]

Running this code on JS produces an unexpected result

val instant = Instant.fromEpochMilliseconds(Long.MAX_VALUE) + 999_999.nanoseconds
println(instant) // expected some positive (clamped) value, got -1000000-01-01T00:00:00Z

The reason for this seems to be this line of code.

1. Instant.fromEpochMilliseconds(Long.MAX_VALUE) gives the max instant on JS (+1000000-12-31T23:59:59.999999999Z)
2. plusFix overflows and throws a DateTimeException
3. here is the actual bug: because the added amount is smaller than one second, seconds is 0, resulting in Instant.MIN being returned

The line should probably be something like this instead:

if (duration.isPositive()) MAX else MIN

[lukellmann]

This might also apply to native (haven't tested it though), jvm seems fine.

[lukellmann]

Can confirm that it also happens on native, will open a PR to fix this.

[ilya-g]

Yes, makes sense to check for duration.isPositive() instead of seconds > 0

[lukellmann]

When can we expect the next release containing the fix?

[05nelsonm]

I believe my issue might be related to this ticket, but wanted to check before opening a new one.

The value was produced on jvm. Converting from a String back to an Instant works fine.

"+5881633-11-04T10:50:52.288260993Z".toInstant()

On native though converting that same String to an Instant throws a DateTimeFormatException.

[dkhalanskyjb]

@05nelsonm it's not related, Native and JS support a much smaller range of years than JVM, namely years ±1000000 at most, instead of ±1000000000 for the JVM. We didn't consider dates outside the smaller range to be useful in practice.

[05nelsonm]

Thanks. Will open a separate ticket then.

Edit: created #269