dnl Time zone functions: tzalloc, localtime_rz, etc.

dnl Copyright (C) 2015-2018 Free Software Foundation, Inc.

dnl This file is free software; the Free Software Foundation

dnl gives unlimited permission to copy and/or distribute it,

dnl with or without modifications, as long as this notice is preserved.

dnl Written by Paul Eggert.

AC_DEFUN([gl_TIME_RZ],

[

  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])

  AC_REQUIRE([gl_HEADER_TIME_H_DEFAULTS])

  AC_REQUIRE([AC_STRUCT_TIMEZONE])

  # Mac OS X 10.6 loops forever with some time_t values.

  # See Bug#27706, Bug#27736, and

  # https://lists.gnu.org/r/bug-gnulib/2017-07/msg00142.html

  AC_CACHE_CHECK([whether localtime loops forever near extrema],

    [gl_cv_func_localtime_infloop_bug],

    [gl_cv_func_localtime_infloop_bug=no

     AC_RUN_IFELSE(

       [AC_LANG_PROGRAM(

          [[#include <stdlib.h>

            #include <string.h>

            #include <unistd.h>

            #include <time.h>

          ]], [[

            time_t t = -67768038400666600;

            struct tm *tm;

            char *tz = getenv ("TZ");

            if (! (tz && strcmp (tz, "QQQ0") == 0))

              return 0;

            alarm (2);

            tm = localtime (&t);

            /* Use TM and *TM to suppress over-optimization.  */

            return tm && tm->tm_isdst;

          ]])],

       [(TZ=QQQ0 ./conftest$EXEEXT) >/dev/null 2>&1 ||

           gl_cv_func_localtime_infloop_bug=yes],

       [],

       [gl_cv_func_localtime_infloop_bug="guessing no"])])

  if test "$gl_cv_func_localtime_infloop_bug" = yes; then

      AC_DEFINE([HAVE_LOCALTIME_INFLOOP_BUG], 1,

        [Define if localtime-like functions can loop forever on

         extreme arguments.])

  fi

  AC_CHECK_TYPES([timezone_t], [], [], [[#include <time.h>]])

  if test "$ac_cv_type_timezone_t" = yes; then

    HAVE_TIMEZONE_T=1

  fi

])