[tz] OpenJDK/CLDR/ICU/Joda issues with Ireland change

Tim Parenti tim at timtimeonline.com
Wed Jan 24 16:56:40 UTC 2018

On 24 January 2018 at 11:19, Robert Elz <kre at munnari.oz.au> wrote:

>   | CLDR provides textual names for time-zones, as an array [winter,
>   | summer].
> That itself is a bug.   It assumes there are just two (not including for
> the "generic" name, mentioned in a later message from Yoshito Umaoka, which
> is probably the more useful one of the three anyway) - and there is
> no guarantee that will (or even always has) remain true.
> There is nothing to stop some locality (probably one at a high latitude)
> from deciding that they should advance the clocks in early spring, and
> then advance them further in early-mid summer, returning to the
> intermediate
> (or some other) value in late summer, and then to the original in late
> autumn (or fall if autumn happens to be called that in the relevant
> location).  What's more, they could give 4 different names to the 3 (or 4)
> different offsets, perhaps "winter time" "spring time" "summer time" and
> "autumn time" with 4 different abbreviations.
> There could even be a mid winter fallback of even more, just as there
> could be a mid summer skip forward of more.

In fact, this has apparently been the case for Antarctica/Troll for quite
some time.  Although the data is a little rough, and it is currently
commented out to avoid compatibility issues, the clear intent is to
eventually model it as correctly as possible — a warning that has been
present in this project for nearly four years already.


Indeed, CLDR having an array that only allows for two descriptive names *is* a
bug and an incompatibility with tz.  If proper attention had been paid to
the implicit dependencies of that project, this would be well-known
already.  While CLDR addresses this issue, some additional thought should
go into how linkages with tz data are handled, as Robert Elz mentioned, so
that if the translated/descriptive strings for a time zone need to depend
on the version of the tz data that generated them, they can… at which point
the problem of the projects independently patching will be about as solved
as it can be.

Tim Parenti
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