[tz] New leapseconds.awk doesn't work on macOS

[Steffen Nurpmeso]

Guy Harris wrote in <4EDFA3A5-DA50-41BE-A248-EB850CB3A581 at alum.mit.edu>:
 |On Jan 10, 2020, at 10:26 PM, enh via tz <tz at iana.org> wrote:
 |> NetBSD already supported regular expressions in RS, and they
 |> upstreamed that to one-true-awk last year
 |
 |macOS:
 |
 | https://opensource.apple.com/source/awk/awk-24/
 |
 |uses what I'm guessing, based on the Lucent copyrights, is the One \
 |True Awk:
 |
 | https://github.com/onetrueawk/awk
 |
 |and I suspect most if not all of the *BSDs do so as well, but macOS \
 |seems to be using a 2007-vintage version.  Perhaps they should update, \

Debian systems use a historic mawk implementation worth
testing against, as it has no gsub and does not have character
classes (i finally have made a port for the Linux hobby
distribution i use to be able to do so easily).

And Sun xpg4/bin/awk expands \ sequences twice:

  -            gsub(/"/, "\\\\\"", LINE)
  +            # Sun xpg4/bin/awk expands those twice:
  +            #  Notice that backslash escapes are interpreted twice, once in
  +            #  lexical processing of the string and once in processing the
  +            #  regular expression.
  +               i = "\""
  +               gsub(/"/, "\\\\\"", i)
  +               i = (i == "\"")
  +            gsub(/"/, (i ? "\\\\\"" : "\134\134\""), LINE)

 |especially to a version that has...
 |
 |> (https://github.com/onetrueawk/awk/commit/643a5a3dad633431c6ce8831944c23\
 |> 059a6be309
 |> and https://github.com/onetrueawk/awk/commit/7cae39dfa53e17981990f649a2f\
 |> 6b4c1ba856112)
 |> so hopefully all the OSes not using gawk can unify at some point.
 |
 |...that change.
 |
 |> but, yeah, right now most awks don't have this ability.
 |
 |...so the tzcode should probably not depend on it.

And the other hand and in my experience packagers simply start
adding build time dependencies to work around such.
I unfortunately forced them to use gawk on MacOS and Debian in the
past...

 --End of <4EDFA3A5-DA50-41BE-A248-EB850CB3A581 at alum.mit.edu>

--steffen
|
|Der Kragenbaer,                The moon bear,
|der holt sich munter           he cheerfully and one by one
|einen nach dem anderen runter  wa.ks himself off
|(By Robert Gernhardt)