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# time_rz.m4
# serial 3
dnl Copyright (C) 2015-2025 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 This file is offered as-is, without any warranty.
dnl Time zone functions: tzalloc, localtime_rz, etc.
dnl Written by Paul Eggert.
AC_DEFUN([gl_TIME_RZ],
[
AC_REQUIRE([gl_TIME_H_DEFAULTS])
AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
AC_REQUIRE([AC_CANONICAL_HOST])
# On Mac OS X 10.6, localtime 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 works even near extrema],
[gl_cv_func_localtime_works],
[gl_cv_func_localtime_works=yes
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$EXEEXT) >/dev/null 2>&1 ||
gl_cv_func_localtime_works=no],
[],
[gl_cv_func_localtime_works="guessing yes"])])
if test "$gl_cv_func_localtime_works" = no; 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
gl_CHECK_FUNCS_ANDROID([tzalloc], [[#include <time.h>]])
if test $ac_cv_func_tzalloc = yes; then
HAVE_TZALLOC=1
fi
dnl Assume that tzalloc, localtime_rz, mktime_z are all defined together.
case "$gl_cv_onwards_func_tzalloc" in
yes)
case "$host_os" in
*-android*)
dnl The Android libc functions localtime_rz, mktime_z don't support
dnl a NULL timezone_t argument.
AC_DEFINE([NEED_TIMEZONE_NULL_SUPPORT], [1],
[Define to 1 if localtime_rz, mktime_z exist and can be used with
non-NULL timezone_t values.])
REPLACE_LOCALTIME_RZ=1
REPLACE_MKTIME_Z=1
;;
esac
;;
future*)
REPLACE_LOCALTIME_RZ=1
REPLACE_MKTIME_Z=1
;;
esac
])
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