[tz] Irish Standard Time vs Irish Summer Time

[Robert Elz]

  From: Paul Eggert <eggert at cs.ucla.edu>
  Date: Sat, 20 Jan 2018 12:49:01 -0800
  Subject: Re: [tz] Irish Standard Time vs Irish Summer Time

  | An API standard could allow tm_zone to be either a char 
  | array or a char const * pointer,

While it is obviously possible, I'd suggest not the array form --
coming up with something that is big enough to withstand possible
future abbreviations, without ABI problems, or being forced to
arbitrarily limit their lengths to meet the lowest common value of
what the various implementations have chosen would be just too hard
to live with.  (And having implementations make it be absurdly large,
like 128 or something, just in case, would be just plain wasteful.)

I'd just forget that and assume it will be a pointer (to a const char *).

  | If tm_zone is a pointer, its lifetime 
  | would be that of the corresponding timezone_t object

Agreed.   For the majority of programs that don't call tzset,
that means for the lifetime of the program.  For those that
do, it is easy to manage.

kre