[tz] Joda-Time compiler broken again

Paul Eggert eggert at cs.ucla.edu
Mon Dec 28 02:52:09 UTC 2020

On 12/27/20 5:31 PM, Stephen Colebourne wrote:
> the seemingly innocuous change from
> Jun 1 00:00 to May 31 24:00 caused the issue

Thanks for looking into the problem. As I understand it the relevant law 
said May 31 at the end of the UT day not June 1 at the start of the day, 
which is why we changed the data.

It is odd that Joda-Time handles "Jul 31 24:00" correctly (as this has 
been in tzdb since 2014e for the Egypt rule), but it mishandles "May 31 
24:00u" in 2020e. I guess the trailing "u" is part of what triggers the bug.

Does your fix to Joda-Time mean that we need not worry about this issue 
in tzdb? That is, can we just tell people to upgrade to the latest 
Joda-Time release?

If that's not realistic, I can look into modifying ziguard.awk to avoid 
using 24:00u in the rearguard format. 24:00u is used only in the Zion 
rule, and this rule is used only in Zones where STDOFF is 2:00, so we 
can change all the "24:00u"s to "2:00s"s the next day. This would be a 
bit of a hack as I'd have to modify ziguard.awk to do some calendar 
arithmetic (e.g., it'd need to know that the next day after Sep 30 is 
Oct 1), which is why I'm hoping that we can just ask people to upgrade 

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