Buddhist: should it have an April new year before 1941?

[sffc]

We can keep the month codes the same. It's only the ordinal months that change.

[robertbastian]

• @hsivonen What would this mean for Java, etc?
• @sffc We're already deviating on Chinese, Hijri, etc. That ship has sailed
• @hsivonen Java doesn't do Chinese or Dangi. Of Hijri, it only ships Umm-al Qura, and to the extent dates stay within almanac, hopefully that part agrees. Java does Japanese only from 6 Meiji onward, so what's in the Java range matches Temporal. If you're going to touch Buddhist, that seems like a breaking change.
• @robertbastian Yeah, maybe let sleeping dogs lie
• @robertbastian Wikipedia actually calls this calendar Thai Solar, and there's a different lunar calendar that it calls Buddhist. If we get into this discussion we should also discuss the name, but I'd much prefer just saying this is the Buddhist calendar as implemented by systems like Java, JS, and ICU before us
• @sffc I agree that this probably isn't a problem worth solving on the existing Buddhist, and it's nice that we have a potential path to solving it by adding a new calendar with a new code.
• @robertbastian This is essentially a calendar change from a calendar using one era to one using another. We don't model the Julian/Gregorian change, because it's going to be messy. Implementing this would require a lot of special cases in code.
• @sffc I don't think this would be hard to implement. The month would count from M04 through M03, with the ordinal month mappings changing. This is easy to model. I think we should eventually support Gregorian switchovers, and Thai switchovers could be added at the same time.
• @robertbastian Do we want to document this as the "proleptic Thai solar buddhist calendar"? It's specifically not https://en.wikipedia.org/wiki/Buddhist_calendar
• @robertbastian - In 3.0 we should maybe rename a few calendars to be more accurate, Dangi is also a weird name
• @sffc Maybe
• @hsivonen Here is a link to Java docs. At least according to Java docs, their Thai Buddhist calendar is defined as a year shift proleptically: https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/time/chrono/ThaiBuddhistChronology.html
• @sffc Let's form a conclusion with the CLDR group on Monday. It seems like we mostly agree.