[tz] [PROPOSED] Merge timezones that are alike since 1970

Paul Eggert eggert at cs.ucla.edu
Tue Jun 1 23:46:28 UTC 2021


On 5/28/21 6:16 PM, Arthur David Olson via tz wrote:
> A philosophical note: maintaining and processing information about the
> oddball stuff that's been done in the past helps ensure the ability to cope
> if the same sort of oddball stuff is done in the future.

Yes, that's long been a stated goal of tzdb - you added a note to that 
effect to the README file in (let me check the repository...) 1986! Paul 
Ganssle followed up today with a similar comment.

I think every tzdb feature used by 'backzone' also occurs in the other 
files, so backzone's practical contribution to exercising zic etc. is 
limited. That being said, we can be more systematic about using 
'backzone' that way. Proposed patch attached, and installed in the 
development repository.

If someone wants to contribute further improvements of automated testing 
of 'backzone' that would be nice. Realistically, though, 'backzone' will 
continue to be lower-quality than the other files, as we lack the human 
time to check and/or improve it despite its known problems.

By the way, one problem I have with "make check_public" is its large 
amount of not-that-useful 'zic -v' chatter like 'warning: "europe", line 
3679: rule goes past start/end of month; will not work with pre-2004 
versions of zic (rule from "europe", line 3660)' which causes me (and I 
assume everyone else) to ignore the chatter. Perhaps we should add an 
option to zic controlling diagnostic age - pre-2004 is pretty old 
nowadays - and change the default for zic -v to not warn about stuff 
that's been in zic for five years or so. After all, there's no point 
having tests if people always ignore test results.

On 6/1/21 11:42 AM, Paul Ganssle via tz wrote:

> The conversation instead
> goes, "Here's the rule we're using" and the follow up is, "That's a
> stupid rule, you should change it." then a bunch of people pile on in
> both sides and no time is saved.

Yes, we've had our share of pile-ons. There is a distinction, though, 
between tz mailing-list politics (the focus of much of the recent 
discussion) and real-world politics (things like, "is Kosovo a 
country?"). My main worry is the latter not the former, in that I think 
it's worth making minor technical changes to tzdb now to help forestall 
potentially major real-world political problems down the road, problems 
that could be worse than being sued by astrologers. Admittedly not 
everyone sees things this way.
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