[tz] OpenJDK/CLDR/ICU/Joda issues with Ireland change
eggert at cs.ucla.edu
Fri Jan 26 22:16:34 UTC 2018
On 01/26/2018 01:39 PM, Michael H Deckers via tz wrote:
> Before this change proceeds, it is, in my opinion, necessary
> to obtain agreement on what the new significant (non-vestigial)
> role of the dst bit, if any, should be in the future (beyond the
> single case of Ireland).
I don't think there's much disagreement over what the bit means in the
context of the POSIX API. For example, POSIX specifies that this
means that standard time is abbreviated "IST" and is 1 hour ahead of
UTC, that daylight saving time is abbreviated "GMT" and is at UTC, and
that the European Union's current rules are in place for when to change
UTC offsets. tzcode and every other POSIX-compatible system support
this, and set tm_isdst=1 in winter with a negative DST offset when
operating in this locale. As far as I know there's no serious dispute
about this, nor is anybody seriously proposing to change this behavior.
That is, the tm_isdst API may be vestigial, but it's too late to change
what it means.
The disagreement is not over the role of the tm_isdst bit; it is whether
tzdb and/or OpenJDK should model Irish Standard Time as a standard time
(tm_isdst=0) or as a daylight saving time (tm_isdst=1), and similarly
for any other locales in a similar boat where standard time is ahead of
the alternative (or "daylight saving") time.
More information about the tz