[tz] RFC 8536bis

[Michael H Deckers]

    On 2024-01-31 21:23, Paul Eggert wrote:

> That merely causes zic to accept .zi input containing four transitions 
> per year for the foreseeable future. Input like this, for example:
>
>   Rule Troll 2005 max - Mar       1 1:00u 1:00 +01
>   Rule Troll 2005 max - Mar lastSun 1:00u 2:00 +02
>   Rule Troll 2005 max - Oct lastSun 1:00u 1:00 +01
>   Rule Troll 2004 max - Nov       7 1:00u 0:00 +00
>   Zone Antarctica/Troll 0    -     -00 2005 Feb 12
>                         0:00 Troll %s
>
> (This isn't in tzdata, but it could be once we can assume tzcode 2014b 
> or later.)
>
> When zic sees input like this, it generates a big TZif file with 
> explicit transitions out to the year 2407 (2005 + 402 years). The big 
> TZif file does not have a TZ string, because no TZ string can 
> represent all these transitions.



    Maybe I did not get it. Are you saying that zic (after 2014b) treats 
the input

         # Rule NAME    FROM    TO      -       IN      ON AT      
SAVE    LETTER/S
         Rule   Troll   2005    max     -       Mar      1 1:00u   
1:00    +01
         Rule   Troll   2005    max     -       Mar     lastSun 1:00u   
2:00    +02
         Rule   Troll   2005    max     -       Oct     lastSun 1:00u   
1:00    +01
         Rule   Troll   2004    max     -       Nov      7 1:00u   
0:00    +00

    as if it were

         # Rule NAME    FROM    TO      -       IN      ON AT      
SAVE    LETTER/S
         Rule   Troll   2005    2407    -       Mar      1 1:00u   
1:00    +01
         Rule   Troll   2005    2407    -       Mar     lastSun 1:00u   
2:00    +02
         Rule   Troll   2005    2407    -       Oct     lastSun 1:00u   
1:00    +01
         Rule   Troll   2004    2407    -       Nov      7 1:00u   
0:00    +00

    If so -- why don't we just specify Rule Troll in the latter form so that
    it correctly describes what is produced by zic? No change in zic would
    have been required.

    Or does zic treat it as if it were

         # Rule NAME    FROM    TO      -       IN      ON AT      
SAVE    LETTER/S
         Rule   Troll   2005    2407    -       Mar      1 1:00u   
1:00    +01
         Rule   Troll   2005    2407    -       Mar     lastSun 1:00u   
2:00    +02
         Rule   Troll   2005    2407    -       Oct     lastSun 1:00u   
1:00    +01
         Rule   Troll   2004    2406    -       Nov      7 1:00u   
0:00    +00

    Where is this behavior of zic documented so that one can find out?

    More basically, I believe that a compiler that tacitly changes the
    source code in this manner if it cannot correctly compile the
    original source is detrimental to the production of reliable software.

    Michael Deckers.