[tz] isdst bug Europe/Dublin (tzdb-2019c)

Paul Eggert eggert at cs.ucla.edu
Tue Dec 10 23:02:33 UTC 2019

On 12/7/19 9:21 AM, Stefan Rueger wrote:
> I think it's neater if the time stretches with the larger GMT values are considered DST.

It is a controversial area because there are two competing objectives: 
having standard time be the standard UT offset ('std' in POSIX) vs 
having DST's offset be greater than standard time's. As noted in the 
'europe' file, in a comment from Joseph S. Myers (2005-01-26):

"(Note that the time in the Republic of Ireland since 1968 has been 
defined in terms of standard time being GMT+1 with a period of winter 
time when it is GMT, rather than standard time being GMT with a period 
of summer time being GMT+1.)"

and we eventually went with that interpretation, as opposed to the one 
you suggested.

Morocco is similar, as are some other historic uses of "winter time" as 
DST. (Whether this practice "saves" daylight depends on whether one 
prefers morning to evening daylight. :-)

If you prefer the other interpretation, you can get it with 'make 

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