[tz] NetBSD vs Darwin timezone API
eggert at cs.ucla.edu
Fri Nov 11 02:46:45 UTC 2016
On 11/10/2016 05:12 PM, Guy Harris wrote:
>> Emacs wants a consistent and complete snapshot of the current rule set for all times from now into the indefinite future.
> To what use does it put that snapshot?
It's the calendar code contributed by E.M. Reingold. As I recall, Emacs
can tell you what day and time DST is scheduled to begin in the year
2039, even on a platform with signed 32-bit time_t so that
localtime/mktime do not work that far into the future. The calendar code
uses Y-M-D arithmetic to work around the Y2038 problem. (Lots of hairy
stuff there, written back when you couldn't reasonably tell people to
get 64-bit machines but people still wanted to calculate the date of
Easter 1066 in the Julian calendar, that sort of thing.)
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