[tz] leap second theory

Brian Inglis Brian.Inglis at SystematicSw.ab.ca
Sun Aug 18 00:23:00 UTC 2019

On 2019-08-17 17:38, Howard Hinnant wrote:
> On Aug 17, 2019, at 4:45 PM, Paul Eggert <eggert at cs.ucla.edu> wrote:
>> … the 'leapseconds' file, which nowadays is used more often than the
>> direct approach, or at least that's my impression.
> Here’s another data point for you:
> http://eel.is/c++draft/time.clock.utc.overview#1
> This is the draft C++20 spec which specifies two clocks:
> 1.  system_clock:  Models Unix Time (does not count leap seconds).
> 2.  utc_clock:  Counts leap seconds.
> And provides bidirectional mappings between these two sets of time points. 
> And the easiest way to implement that mapping is to read in the IANA tz 
> leapseconds file.

WG14/C is looking at:


which seems somewhat based on the POSIX standard.

The POSIX Austin CSRG is discussing clarifying tm_isdst:


and other issues.

Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada

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