[tz] isdst bug Europe/Dublin (tzdb-2019c)
stefan.rueger at theblueorange.space
Sat Dec 7 17:21:05 UTC 2019
Looks like zdump claims Dublin has DST during winter, not summer:
$ ./zdump -i -c2020,2021 Europe/Dublin
- - +00 GMT 1
2020-03-29 02 +01 IST
2020-10-25 01 +00 GMT 1
Compare with the output for London, which is as I would expect:
$ ./zdump -i -c2020,2021 Europe/London
- - +00 GMT
2020-03-29 02 +01 BST 1
2020-10-25 01 +00 GMT
Generally, I think it's neater if the time stretches with the larger GMT values are considered DST. This is almost always true, except for Europe/Dublin, Eire, Africa/Casablanca and Africa/El_Aaiun.
Morocco (and Western Sahara) change the time to have shorter fasts during Ramadan, so to speak to *not* save daylight. I would therefore still argue that the time outside Ramadan should be considered DST and the time during Ramadan the non-DST time.
I am aware that the view "DST means larger GMT value" is not a precise definition (a region that change times zones in quick succession might easily accrue more than two GMT values within a few years). It's therefore not a great candidate for implementation in zic/zdump. However, I hold that periodic *future* annual back-and-forth switches should adopt that principle.
Anyway, over to you
PS: You are providing an *amazing* service - many thanks for that!
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