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emacs/m4/time_rz.m4
Paul Eggert 365e01cc9f Update copyright year to 2020
Run "TZ=UTC0 admin/update-copyright $(git ls-files)".
2020-01-01 00:59:52 +00:00

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dnl Time zone functions: tzalloc, localtime_rz, etc.
dnl Copyright (C) 2015-2020 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
])