gettimeofday: Remove workaround for Mac OS X 10.0

[Bruno Haible]

Similarly, Mac OS X 10.0 is obsolete since it was end-of-support in 2004 [1].
Some people, like me, still have a Mac OS X 10.5 machine around, but 10.0
is surely extremely rare by now.

[1] https://en.wikipedia.org/wiki/MacOS#Release_history


2020-07-26  Bruno Haible  <bruno@clisp.org>

        gettimeofday: Remove workaround for Mac OS X 10.0.
        * m4/gettimeofday.m4 (gl_FUNC_GETTIMEOFDAY_CLOBBER): Remove macro.
        (gl_FUNC_GETTIMEOFDAY): Don't invoke it.
        * lib/gettimeofday.c: Don't include localtime-buffer.h.
        (gettimeofday): Don't test GETTIMEOFDAY_CLOBBERS_LOCALTIME.
        * lib/localtime.c: Don't test GETTIMEOFDAY_CLOBBERS_LOCALTIME.
        * modules/gettimeofday (Depends-on): Remove localtime-buffer.
        * modules/localtime-buffer: Remove file.
        * lib/localtime-buffer.h: Remove file.
        * lib/localtime-buffer.c: Remove file.
        * m4/localtime-buffer.m4: Remove file.
        * MODULES.html.sh (Date and time <time.h>): Remove localtime-buffer.

diff --git a/MODULES.html.sh b/MODULES.html.sh
index 43a6dba..11a4a77 100755
--- a/MODULES.html.sh
+++ b/MODULES.html.sh
@@ -1727,7 +1727,6 @@ func_all_modules ()
 
   func_begin_table
   func_module fprintftime
-  func_module localtime-buffer
   func_module nstrftime
   func_module strftime-fixes
   func_module time_rz
diff --git a/lib/gettimeofday.c b/lib/gettimeofday.c
index 305ab98..8b758a1 100644
--- a/lib/gettimeofday.c
+++ b/lib/gettimeofday.c
@@ -29,8 +29,6 @@
 # include <windows.h>
 #endif
 
-#include "localtime-buffer.h"
-
 #ifdef WINDOWS_NATIVE
 
 /* Don't assume that UNICODE is not defined.  */
@@ -123,11 +121,6 @@ gettimeofday (struct timeval *restrict tv, void *restrict 
tz)
 #else
 
 # if HAVE_GETTIMEOFDAY
-#  if GETTIMEOFDAY_CLOBBERS_LOCALTIME
-  /* Save and restore the contents of the buffer used for localtime's
-     result around the call to gettimeofday.  */
-  struct tm save = *localtime_buffer_addr;
-#  endif
 
 #  if defined timeval /* 'struct timeval' overridden by gnulib?  */
 #   undef timeval
@@ -142,10 +135,6 @@ gettimeofday (struct timeval *restrict tv, void *restrict 
tz)
   int result = gettimeofday (tv, (struct timezone *) tz);
 #  endif
 
-#  if GETTIMEOFDAY_CLOBBERS_LOCALTIME
-  *localtime_buffer_addr = save;
-#  endif
-
   return result;
 
 # else
diff --git a/lib/localtime-buffer.c b/lib/localtime-buffer.c
deleted file mode 100644
index 91b073e..0000000
--- a/lib/localtime-buffer.c
+++ /dev/null
@@ -1,60 +0,0 @@
-/* Provide access to the last buffer returned by localtime() or gmtime().
-
-   Copyright (C) 2001-2003, 2005-2007, 2009-2020 Free Software Foundation, Inc.
-
-   This program is free software; you can redistribute it and/or modify
-   it under the terms of the GNU General Public License as published by
-   the Free Software Foundation; either version 2, or (at your option)
-   any later version.
-
-   This program is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-   GNU General Public License for more details.
-
-   You should have received a copy of the GNU General Public License
-   along with this program; if not, see <https://www.gnu.org/licenses/>.  */
-
-/* written by Jim Meyering */
-
-#include <config.h>
-
-/* Specification.  */
-#include "localtime-buffer.h"
-
-#if GETTIMEOFDAY_CLOBBERS_LOCALTIME
-
-static struct tm tm_zero_buffer;
-struct tm *localtime_buffer_addr = &tm_zero_buffer;
-
-/* This is a wrapper for localtime.
-
-   On the first call, record the address of the static buffer that
-   localtime uses for its result.  */
-
-struct tm *
-rpl_localtime (time_t const *timep)
-#undef localtime
-{
-  struct tm *tm = localtime (timep);
-
-  if (localtime_buffer_addr == &tm_zero_buffer)
-    localtime_buffer_addr = tm;
-
-  return tm;
-}
-
-/* Same as above, since gmtime and localtime use the same buffer.  */
-struct tm *
-rpl_gmtime (time_t const *timep)
-#undef gmtime
-{
-  struct tm *tm = gmtime (timep);
-
-  if (localtime_buffer_addr == &tm_zero_buffer)
-    localtime_buffer_addr = tm;
-
-  return tm;
-}
-
-#endif
diff --git a/lib/localtime-buffer.h b/lib/localtime-buffer.h
deleted file mode 100644
index 9939d81..0000000
--- a/lib/localtime-buffer.h
+++ /dev/null
@@ -1,27 +0,0 @@
-/* Provide access to the last buffer returned by localtime() or gmtime().
-
-   Copyright (C) 2001-2003, 2005-2007, 2009-2020 Free Software Foundation, Inc.
-
-   This program is free software; you can redistribute it and/or modify
-   it under the terms of the GNU General Public License as published by
-   the Free Software Foundation; either version 2, or (at your option)
-   any later version.
-
-   This program is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-   GNU General Public License for more details.
-
-   You should have received a copy of the GNU General Public License
-   along with this program; if not, see <https://www.gnu.org/licenses/>.  */
-
-/* written by Jim Meyering */
-
-#include <time.h>
-
-#if GETTIMEOFDAY_CLOBBERS_LOCALTIME
-
-/* The address of the last buffer returned by localtime() or gmtime().  */
-extern struct tm *localtime_buffer_addr;
-
-#endif
diff --git a/lib/localtime.c b/lib/localtime.c
index 9070993..f5e6767 100644
--- a/lib/localtime.c
+++ b/lib/localtime.c
@@ -19,18 +19,15 @@
 /* Specification.  */
 #include <time.h>
 
-/* Keep consistent with localtime-buffer.c!  */
-#if !GETTIMEOFDAY_CLOBBERS_LOCALTIME
+#include <stdlib.h>
+#include <string.h>
 
-# include <stdlib.h>
-# include <string.h>
-
-# undef localtime
+#undef localtime
 
 struct tm *
 rpl_localtime (const time_t *tp)
 {
-# if defined _WIN32 && ! defined __CYGWIN__
+#if defined _WIN32 && ! defined __CYGWIN__
   /* Rectify the value of the environment variable TZ.
      There are four possible kinds of such values:
        - Traditional US time zone names, e.g. "PST8PDT".  Syntax: see
@@ -56,9 +53,7 @@ rpl_localtime (const time_t *tp)
   const char *tz = getenv ("TZ");
   if (tz != NULL && strchr (tz, '/') != NULL)
     _putenv ("TZ=");
-# endif
+#endif
 
   return localtime (tp);
 }
-
-#endif
diff --git a/m4/gettimeofday.m4 b/m4/gettimeofday.m4
index c72b3ea..578ed49 100644
--- a/m4/gettimeofday.m4
+++ b/m4/gettimeofday.m4
@@ -1,4 +1,4 @@
-# serial 27
+# serial 28
 
 # Copyright (C) 2001-2003, 2005, 2007, 2009-2020 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
@@ -19,7 +19,6 @@ AC_DEFUN([gl_FUNC_GETTIMEOFDAY],
   if test $ac_cv_func_gettimeofday != yes; then
     HAVE_GETTIMEOFDAY=0
   else
-    gl_FUNC_GETTIMEOFDAY_CLOBBER
     AC_CACHE_CHECK([for gettimeofday with POSIX signature],
       [gl_cv_func_gettimeofday_posix_signature],
       [AC_COMPILE_IFELSE(
@@ -66,63 +65,5 @@ int gettimeofday (struct timeval *restrict, struct timezone 
*restrict);
      declaration of the second argument to gettimeofday.])
 ])
 
-
-dnl See if gettimeofday clobbers the static buffer that localtime uses
-dnl for its return value.  The gettimeofday function from Mac OS X 10.0.4
-dnl (i.e., Darwin 1.3.7) has this problem.
-dnl
-dnl If it does, then arrange to use gettimeofday and localtime only via
-dnl the wrapper functions that work around the problem.
-
-AC_DEFUN([gl_FUNC_GETTIMEOFDAY_CLOBBER],
-[
- AC_REQUIRE([gl_HEADER_SYS_TIME_H])
- AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
- AC_REQUIRE([gl_LOCALTIME_BUFFER_DEFAULTS])
-
- AC_CACHE_CHECK([whether gettimeofday clobbers localtime buffer],
-  [gl_cv_func_gettimeofday_clobber],
-  [AC_RUN_IFELSE(
-     [AC_LANG_PROGRAM(
-        [[#include <string.h>
-          #include <sys/time.h>
-          #include <time.h>
-          #include <stdlib.h>
-        ]],
-        [[
-          time_t t = 0;
-          struct tm *lt;
-          struct tm saved_lt;
-          struct timeval tv;
-          lt = localtime (&t);
-          saved_lt = *lt;
-          gettimeofday (&tv, NULL);
-          return memcmp (lt, &saved_lt, sizeof (struct tm)) != 0;
-        ]])],
-     [gl_cv_func_gettimeofday_clobber=no],
-     [gl_cv_func_gettimeofday_clobber=yes],
-     [# When cross-compiling:
-      case "$host_os" in
-                       # Guess all is fine on glibc systems.
-        *-gnu* | gnu*) gl_cv_func_gettimeofday_clobber="guessing no" ;;
-                       # Guess all is fine on musl systems.
-        *-musl*)       gl_cv_func_gettimeofday_clobber="guessing no" ;;
-                       # Guess no on native Windows.
-        mingw*)        gl_cv_func_gettimeofday_clobber="guessing no" ;;
-                       # If we don't know, obey --enable-cross-guesses.
-        *)             
gl_cv_func_gettimeofday_clobber="$gl_cross_guess_inverted" ;;
-      esac
-     ])])
-
- case "$gl_cv_func_gettimeofday_clobber" in
-   *yes)
-     REPLACE_GETTIMEOFDAY=1
-     AC_DEFINE([GETTIMEOFDAY_CLOBBERS_LOCALTIME], [1],
-       [Define if gettimeofday clobbers the localtime buffer.])
-     gl_LOCALTIME_BUFFER_NEEDED
-     ;;
- esac
-])
-
 # Prerequisites of lib/gettimeofday.c.
 AC_DEFUN([gl_PREREQ_GETTIMEOFDAY], [:])
diff --git a/m4/localtime-buffer.m4 b/m4/localtime-buffer.m4
deleted file mode 100644
index 09df3c9..0000000
--- a/m4/localtime-buffer.m4
+++ /dev/null
@@ -1,21 +0,0 @@
-# localtime-buffer.m4 serial 1
-dnl Copyright (C) 2017-2020 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.
-
-AC_DEFUN([gl_LOCALTIME_BUFFER_DEFAULTS],
-[
-  NEED_LOCALTIME_BUFFER=0
-])
-
-dnl Macro invoked from other modules, to signal that the compilation of
-dnl module 'localtime-buffer' is needed.
-AC_DEFUN([gl_LOCALTIME_BUFFER_NEEDED],
-[
-  AC_REQUIRE([gl_LOCALTIME_BUFFER_DEFAULTS])
-  AC_REQUIRE([gl_HEADER_TIME_H_DEFAULTS])
-  NEED_LOCALTIME_BUFFER=1
-  REPLACE_GMTIME=1
-  REPLACE_LOCALTIME=1
-])
diff --git a/modules/gettimeofday b/modules/gettimeofday
index 106e7a7..b4bdcc3 100644
--- a/modules/gettimeofday
+++ b/modules/gettimeofday
@@ -7,7 +7,6 @@ m4/gettimeofday.m4
 
 Depends-on:
 sys_time
-localtime-buffer [test $NEED_LOCALTIME_BUFFER = 1]
 
 configure.ac:
 gl_FUNC_GETTIMEOFDAY
diff --git a/modules/localtime-buffer b/modules/localtime-buffer
deleted file mode 100644
index e511d43..0000000
--- a/modules/localtime-buffer
+++ /dev/null
@@ -1,25 +0,0 @@
-Description:
-Access to the internal buffer of the localtime() function and the gmtime() 
function.
-
-Files:
-lib/localtime-buffer.h
-lib/localtime-buffer.c
-m4/localtime-buffer.m4
-
-Depends-on:
-time            [false]
-
-configure.ac:
-AC_REQUIRE([gl_LOCALTIME_BUFFER_DEFAULTS])
-AC_LIBOBJ([localtime-buffer])
-
-Makefile.am:
-
-Include:
-"localtime-buffer.h"
-
-License:
-LGPLv2+
-
-Maintainer:
-all