[tz] Getting current tzdb version in use

[Brian Inglis]

On 2018-07-19 13:42, Paul Eggert wrote:
> On 07/19/2018 08:50 AM, lester at lsces.co.uk wrote:
>> The bottom line is that currently we have no way of knowing just what data is
>> being supplied. Even if the data matches the raw tz version, it may or may not
>> include the pre-1970 <tel:1970> data archived to backzone.
> 
> Yes, and this is partly why I have resisted putting version information into the
> installed files. Version info is typically not available unless you've merely
> cloned the development Git repository and have made no change to the data or to
> the 'make' parameters that select or alter the data, a situation that is
> reasonably rare in practice. It would take quite a bit of effort to get reliable
> version information in real installations, and nobody knows exactly what would
> be entailed in that effort. Since many people have requested version info I had
> compromised by putting a version string into tzdata.zi as a sort of experiment.
> The experiment has clearly failed so far.
> 
> That being said, we can improve things a bit by putting into tzdata.zi
> information about whether the file 'backward' was used, as well as whether the
> (dicey) file 'backzone' and the (obsolete) file 'pacificnew' were used. We can
> also record whether the rearguard (or vanguard) data format was selected.
> Proposed patch attached.

Also whether zone.tab or zone1970.tab was used, the leapseconds.nnn... file used
as leapseconds.list, REDO value {posix|right}_{only|right|posix}, and any other
zic input selections I missed.

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