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

Philip Paeps philip at trouble.is
Wed Jan 24 22:44:57 UTC 2018

On 2018-01-24 18:36:42 (+0000), Stephen Colebourne wrote:
>> 99.9999% of people (not being zic) should really be ignoring those
>> files, and everything they contain (the remaining percentage are the
>> people who maintain the data - all 10 or 20 or so of them in the world).
>> Everything else should be based upon the zoneinfo output files from
>> zic
>This hasn't been true for many many years. The source files are parsed
>by every downstream program I know. Its been discussed before as to
>why this is. I'd strongly suggest accepting that the source files are
>a primary interface, which is why negative SAVE values matter to
>downstream users.
>As for the rest, well I'm not going to reply to each line. With no
>acceptance of the concept of backwards compatibility, discussion is
>pretty pointless. If there was a simple bug fix that solves all the
>problems, I'd gladly do my part. There isn't such a fix - every avenue
>other than insisting on positive SAVE values will make things worse.
>Want to make things truly better? Agree to move TZDB under the
>auspices of CLDR, so it can be managed by a paid team who actually
>understand stability and compatibility, and the trade off of those
>against some abstract notion of purity. As a combined dataset, there
>would be the ability to solve the text problem in a realistic and
>pragmatic way.

Wow. That's harsh.

>TZDB is not the centre of the universe. It is a small cog in a much
>bigger machine. Its time to accept that.

Neither is Java the centre of the universe.  Java is just one terribly 
broken downstream consumer with flawed expectations.

But I don't think pointing fingers (at anyone) is going to make anything 
actually better.

The tzdb could (and should) improve "expectation management" but 
downstram consumers could (and should) also improve their expectations 
from the data.

As usual "be strict in what you send and liberal in what you accept" 
should be a guiding principle.  The tzdb should be as correct as 
possible and downstream consumers should be (become) as flexible as 
possible to accept the crazy reality we happen to live in.  Currently, 
historically and in the future.

People in control of timezones *will* continue to mess with them in ways 
we don't expect.  Negative savings have happened once.  There is nothing 
to stop anyone from having a negative savings of twelve minutes relative 
to their "standard" timezone which happens to be called summer time...  
And software will just have to cope or people will get cranky.


Philip Paeps
Senior Reality Engineer
Ministry of Information

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