Update from Gnulib

This incorporates:
2020-08-16 time_rz: remove unused functions
2020-08-16 time_rz: fix issues with mktime_z failures
2020-08-16 nstrftime: Guide inlining also on clang
2020-08-16 intprops: Avoid bogus warning on clang
2020-08-16 libc-config: Enable __REDIRECT macro also on clang
2020-08-16 regex: Use initializer shorthand syntax also with clang
2020-08-16 regex: Use space optimization also with clang
2020-08-16 Use _Static_assert and static_assert when present on clang
2020-08-16 Use 'throw ()' for optimization in C++ mode also on clang
2020-08-16 stdio: Don't break attribute 'scanf' on clang
2020-08-16 Fix "warning: 'format' attribute ...: rpl_printf"
2020-08-16 Fix "warning: attribute declaration must precede definition"
2020-08-16 Fix undesired warnings
2020-08-16 Don't use Autoconf quadrigraphsxo
2020-08-16 Fix quoting of AC_LANG_PROGRAM arguments
2020-08-16 Assume autoconf >= 2.64
2020-08-15 nstrftime: be more predictable about errno
2020-08-15 canonicalize: Fix autoconf test on MSVC/clang
2020-08-15 Support compiling without -loldnames on native Windows
2020-08-14 mktime, mktime-internal: Remove obsolete code
2020-08-14 Assume tzset exists
* lib/c++defs.h, lib/canonicalize-lgpl.c, lib/cdefs.h, lib/dup2.c:
* lib/fcntl.in.h, lib/getopt-cdefs.in.h, lib/intprops.h, lib/md5.h:
* lib/mktime.c, lib/nstrftime.c, lib/open.c, lib/regcomp.c:
* lib/regex_internal.h, lib/stdio.in.h, lib/stdlib.in.h:
* lib/strftime.h, lib/string.in.h, lib/sys_select.in.h:
* lib/sys_stat.in.h, lib/sys_time.in.h, lib/time.in.h, lib/time_rz.c:
* lib/unistd.in.h, lib/verify.h, m4/00gnulib.m4:
* m4/absolute-header.m4, m4/alloca.m4, m4/canonicalize.m4, m4/dup2.m4:
* m4/fchmodat.m4, m4/fcntl.m4, m4/fdopendir.m4, m4/fpending.m4:
* m4/futimens.m4, m4/getdtablesize.m4, m4/getloadavg.m4:
* m4/gnulib-common.m4, m4/include_next.m4, m4/largefile.m4:
* m4/manywarnings.m4, m4/mktime.m4, m4/nstrftime.m4, m4/open-slash.m4:
* m4/pselect.m4, m4/pthread_sigmask.m4, m4/time_h.m4, m4/utimens.m4:
* m4/utimensat.m4, m4/utimes.m4, m4/warnings.m4:
Copy from Gnulib.
* lib/gnulib.mk.in: Regenerate.

26 files changed, 168 insertions, 132 deletions

diff --git a/m4/00gnulib.m4 b/m4/00gnulib.m4
index 06eff4f3863..14628c363b7 100644
--- a/m4/00gnulib.m4
+++ b/m4/00gnulib.m4
@@ -1,44 +1,12 @@
-# 00gnulib.m4 serial 7
+# 00gnulib.m4 serial 8
 dnl Copyright (C) 2009-2020 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 This file must be named something that sorts before all other
-dnl gnulib-provided .m4 files.  The first part is needed until such time
-dnl as we can assume Autoconf 2.64, with its improved AC_DEFUN_ONCE and
-dnl m4_divert semantics.  The second part is needed until the clang fix
-dnl has been included in Autoconf.
-
-# Until autoconf 2.63, handling of the diversion stack required m4_init
-# to be called first; but this does not happen with aclocal.  Wrapping
-# the entire execution in another layer of the diversion stack fixes this.
-# Worse, prior to autoconf 2.62, m4_wrap depended on the underlying m4
-# for whether it was FIFO or LIFO; in order to properly balance with
-# m4_init, we need to undo our push just before anything wrapped within
-# the m4_init body.  The way to ensure this is to wrap both sides of
-# m4_init with a one-shot macro that does the pop at the right time.
-m4_ifndef([_m4_divert_diversion],
-[m4_divert_push([KILL])
-m4_define([gl_divert_fixup], [m4_divert_pop()m4_define([$0])])
-m4_define([m4_init],
-  [gl_divert_fixup()]m4_defn([m4_init])[gl_divert_fixup()])])
-
-
-# AC_DEFUN_ONCE([NAME], VALUE)
-# ----------------------------
-# Define NAME to expand to VALUE on the first use (whether by direct
-# expansion, or by AC_REQUIRE), and to nothing on all subsequent uses.
-# Avoid bugs in AC_REQUIRE in Autoconf 2.63 and earlier.  This
-# definition is slower than the version in Autoconf 2.64, because it
-# can only use interfaces that existed since 2.59; but it achieves the
-# same effect.  Quoting is necessary to avoid confusing Automake.
-m4_version_prereq([2.63.263], [],
-[m4_define([AC][_DEFUN_ONCE],
-  [AC][_DEFUN([$1],
-    [AC_REQUIRE([_gl_DEFUN_ONCE([$1])],
-      [m4_indir([_gl_DEFUN_ONCE([$1])])])])]dnl
-[AC][_DEFUN([_gl_DEFUN_ONCE([$1])], [$2])])])
+dnl gnulib-provided .m4 files.  It is needed until the clang fix has
+dnl been included in Autoconf.
 
 # The following definitions arrange to use a compiler option
 # -Werror=implicit-function-declaration in AC_CHECK_DECL, when the
diff --git a/m4/absolute-header.m4 b/m4/absolute-header.m4
index 39726ba57ba..c043233de36 100644
--- a/m4/absolute-header.m4
+++ b/m4/absolute-header.m4
@@ -1,4 +1,4 @@
-# absolute-header.m4 serial 16
+# absolute-header.m4 serial 17
 dnl Copyright (C) 2006-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -22,23 +22,21 @@ dnl From Derek Price.
 AC_DEFUN([gl_ABSOLUTE_HEADER],
 [AC_REQUIRE([AC_CANONICAL_HOST])
 AC_LANG_PREPROC_REQUIRE()dnl
-dnl FIXME: gl_absolute_header and ac_header_exists must be used unquoted
-dnl until we can assume autoconf 2.64 or newer.
 m4_foreach_w([gl_HEADER_NAME], [$1],
   [AS_VAR_PUSHDEF([gl_absolute_header],
                   [gl_cv_absolute_]m4_defn([gl_HEADER_NAME]))dnl
   AC_CACHE_CHECK([absolute name of <]m4_defn([gl_HEADER_NAME])[>],
-    m4_defn([gl_absolute_header]),
+    [gl_absolute_header],
     [AS_VAR_PUSHDEF([ac_header_exists],
                     [ac_cv_header_]m4_defn([gl_HEADER_NAME]))dnl
     AC_CHECK_HEADERS_ONCE(m4_defn([gl_HEADER_NAME]))dnl
-    if test AS_VAR_GET(ac_header_exists) = yes; then
+    if test AS_VAR_GET([ac_header_exists]) = yes; then
       gl_ABSOLUTE_HEADER_ONE(m4_defn([gl_HEADER_NAME]))
     fi
     AS_VAR_POPDEF([ac_header_exists])dnl
     ])dnl
   AC_DEFINE_UNQUOTED(AS_TR_CPP([ABSOLUTE_]m4_defn([gl_HEADER_NAME])),
-                     ["AS_VAR_GET(gl_absolute_header)"],
+                     ["AS_VAR_GET([gl_absolute_header])"],
                      [Define this to an absolute name of <]m4_defn([gl_HEADER_NAME])[>.])
   AS_VAR_POPDEF([gl_absolute_header])dnl
 ])dnl
diff --git a/m4/alloca.m4 b/m4/alloca.m4
index b777f8450ce..d8414896308 100644
--- a/m4/alloca.m4
+++ b/m4/alloca.m4
@@ -1,4 +1,4 @@
-# alloca.m4 serial 17
+# alloca.m4 serial 18
 dnl Copyright (C) 2002-2004, 2006-2007, 2009-2020 Free Software Foundation,
 dnl Inc.
 dnl This file is free software; the Free Software Foundation
@@ -102,7 +102,7 @@ AH_VERBATIM([STACK_DIRECTION],
         STACK_DIRECTION > 0 => grows toward higher addresses
         STACK_DIRECTION < 0 => grows toward lower addresses
         STACK_DIRECTION = 0 => direction of growth unknown */
-@%:@undef STACK_DIRECTION])dnl
+#undef STACK_DIRECTION])dnl
 AC_DEFINE_UNQUOTED(STACK_DIRECTION, $ac_cv_c_stack_direction)
 ])
 ])
diff --git a/m4/canonicalize.m4 b/m4/canonicalize.m4
index bdc5c8f71a7..14ea3e12fa0 100644
--- a/m4/canonicalize.m4
+++ b/m4/canonicalize.m4
@@ -1,4 +1,4 @@
-# canonicalize.m4 serial 31
+# canonicalize.m4 serial 33
 
 dnl Copyright (C) 2003-2007, 2009-2020 Free Software Foundation, Inc.
 
@@ -56,7 +56,16 @@ AC_DEFUN([gl_CANONICALIZE_LGPL],
 AC_DEFUN([gl_CANONICALIZE_LGPL_SEPARATE],
 [
   AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
-  AC_CHECK_FUNCS_ONCE([canonicalize_file_name getcwd readlink])
+  AC_CHECK_FUNCS_ONCE([canonicalize_file_name readlink])
+
+  dnl On native Windows, we use _getcwd(), regardless whether getcwd() is
+  dnl available through the linker option '-loldnames'.
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  case "$host_os" in
+    mingw*) ;;
+    *)      AC_CHECK_FUNCS([getcwd]) ;;
+  esac
+
   AC_REQUIRE([gl_DOUBLE_SLASH_ROOT])
   AC_REQUIRE([gl_FUNC_REALPATH_WORKS])
   AC_CHECK_HEADERS_ONCE([sys/param.h])
@@ -70,6 +79,7 @@ AC_DEFUN([gl_FUNC_REALPATH_WORKS],
   AC_CHECK_FUNCS_ONCE([realpath])
   AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
   AC_CACHE_CHECK([whether realpath works], [gl_cv_func_realpath_works], [
+    rm -rf conftest.a conftest.d
     touch conftest.a
     mkdir conftest.d
     AC_RUN_IFELSE([
diff --git a/m4/dup2.m4 b/m4/dup2.m4
index 462bfd0e526..a82798d6bba 100644
--- a/m4/dup2.m4
+++ b/m4/dup2.m4
@@ -1,4 +1,4 @@
-#serial 26
+#serial 27
 dnl Copyright (C) 2002, 2005, 2007, 2009-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -16,6 +16,7 @@ AC_DEFUN([gl_FUNC_DUP2],
            #include <limits.h>
            #include <sys/resource.h>
            #include <unistd.h>
+           ]GL_MDA_DEFINES[
            #ifndef RLIM_SAVED_CUR
            # define RLIM_SAVED_CUR RLIM_INFINITY
            #endif
diff --git a/m4/fchmodat.m4 b/m4/fchmodat.m4
index e3f2f048162..cf5c87999c5 100644
--- a/m4/fchmodat.m4
+++ b/m4/fchmodat.m4
@@ -1,4 +1,4 @@
-# fchmodat.m4 serial 4
+# fchmodat.m4 serial 5
 dnl Copyright (C) 2004-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -40,7 +40,7 @@ AC_DEFUN([gl_FUNC_FCHMODAT],
               #ifndef S_IRWXO
                #define S_IRWXO 0007
               #endif
-            ]],
+            ]GL_MDA_DEFINES],
             [[
               int permissive = S_IRWXU | S_IRWXG | S_IRWXO;
               int desired = S_IRUSR | S_IWUSR;
diff --git a/m4/fcntl.m4 b/m4/fcntl.m4
index 562ae2395df..ea24f3d64ef 100644
--- a/m4/fcntl.m4
+++ b/m4/fcntl.m4
@@ -1,4 +1,4 @@
-# fcntl.m4 serial 9
+# fcntl.m4 serial 10
 dnl Copyright (C) 2009-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -34,6 +34,7 @@ AC_DEFUN([gl_FUNC_FCNTL],
               #include <limits.h>
               #include <sys/resource.h>
               #include <unistd.h>
+              ]GL_MDA_DEFINES[
               #ifndef RLIM_SAVED_CUR
               # define RLIM_SAVED_CUR RLIM_INFINITY
               #endif
diff --git a/m4/fdopendir.m4 b/m4/fdopendir.m4
index d9cc1a00173..9937a74ea8d 100644
--- a/m4/fdopendir.m4
+++ b/m4/fdopendir.m4
@@ -1,4 +1,4 @@
-# serial 12
+# serial 14
 # See if we need to provide fdopendir.
 
 dnl Copyright (C) 2009-2020 Free Software Foundation, Inc.
@@ -25,10 +25,12 @@ AC_DEFUN([gl_FUNC_FDOPENDIR],
   else
     AC_CACHE_CHECK([whether fdopendir works],
       [gl_cv_func_fdopendir_works],
-      [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
+      [AC_RUN_IFELSE(
+         [AC_LANG_PROGRAM([[
 #include <dirent.h>
 #include <fcntl.h>
 #include <unistd.h>
+]GL_MDA_DEFINES[
 #if !HAVE_DECL_FDOPENDIR
 extern
 # ifdef __cplusplus
@@ -36,12 +38,14 @@ extern
 # endif
 DIR *fdopendir (int);
 #endif
-]], [int result = 0;
-     int fd = open ("conftest.c", O_RDONLY);
-     if (fd < 0) result |= 1;
-     if (fdopendir (fd)) result |= 2;
-     if (close (fd)) result |= 4;
-     return result;])],
+]],
+            [[int result = 0;
+              int fd = open ("conftest.c", O_RDONLY);
+              if (fd < 0) result |= 1;
+              if (fdopendir (fd)) result |= 2;
+              if (close (fd)) result |= 4;
+              return result;
+            ]])],
          [gl_cv_func_fdopendir_works=yes],
          [gl_cv_func_fdopendir_works=no],
          [case "$host_os" in
diff --git a/m4/fpending.m4 b/m4/fpending.m4
index ea9725e4890..edabcec5f0b 100644
--- a/m4/fpending.m4
+++ b/m4/fpending.m4
@@ -1,4 +1,4 @@
-# serial 22
+# serial 23
 
 # Copyright (C) 2000-2001, 2004-2020 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
@@ -25,7 +25,7 @@ AC_DEFUN([gl_FUNC_FPENDING],
   AC_CACHE_CHECK([for __fpending], [gl_cv_func___fpending],
     [
       AC_LINK_IFELSE(
-        [AC_LANG_PROGRAM([$fp_headers],
+        [AC_LANG_PROGRAM([[$fp_headers]],
            [[return ! __fpending (stdin);]])],
         [gl_cv_func___fpending=yes],
         [gl_cv_func___fpending=no])
diff --git a/m4/futimens.m4 b/m4/futimens.m4
index dc5cfa94119..145b8ff0d51 100644
--- a/m4/futimens.m4
+++ b/m4/futimens.m4
@@ -1,4 +1,4 @@
-# serial 8
+# serial 9
 # See if we need to provide futimens replacement.
 
 dnl Copyright (C) 2009-2020 Free Software Foundation, Inc.
@@ -24,7 +24,8 @@ AC_DEFUN([gl_FUNC_FUTIMENS],
 #include <sys/stat.h>
 #include <unistd.h>
 #include <errno.h>
-]], [[struct timespec ts[2];
+]GL_MDA_DEFINES],
+     [[struct timespec ts[2];
       int fd = creat ("conftest.file", 0600);
       struct stat st;
       if (fd < 0) return 1;
diff --git a/m4/getdtablesize.m4 b/m4/getdtablesize.m4
index ab2e3feb37b..af328644adb 100644
--- a/m4/getdtablesize.m4
+++ b/m4/getdtablesize.m4
@@ -1,4 +1,4 @@
-# getdtablesize.m4 serial 7
+# getdtablesize.m4 serial 8
 dnl Copyright (C) 2008-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -29,13 +29,16 @@ AC_DEFUN([gl_FUNC_GETDTABLESIZE],
            dnl correctly require setrlimit before getdtablesize() can report
            dnl a larger value.
            AC_RUN_IFELSE([
-             AC_LANG_PROGRAM([[#include <unistd.h>]],
-               [int size = getdtablesize();
-                if (dup2 (0, getdtablesize()) != -1)
-                  return 1;
-                if (size != getdtablesize())
-                  return 2;
-               ])],
+             AC_LANG_PROGRAM(
+               [[#include <unistd.h>]
+                GL_MDA_DEFINES
+               ],
+               [[int size = getdtablesize();
+                 if (dup2 (0, getdtablesize()) != -1)
+                   return 1;
+                 if (size != getdtablesize())
+                   return 2;
+               ]])],
              [gl_cv_func_getdtablesize_works=yes],
              [gl_cv_func_getdtablesize_works=no],
              [case "$host_os" in
diff --git a/m4/getloadavg.m4 b/m4/getloadavg.m4
index 8e96965d828..9fe328efc02 100644
--- a/m4/getloadavg.m4
+++ b/m4/getloadavg.m4
@@ -7,7 +7,7 @@
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.
 
-#serial 9
+#serial 10
 
 # Autoconf defines AC_FUNC_GETLOADAVG, but that is obsolescent.
 # New applications should use gl_GETLOADAVG instead.
@@ -147,7 +147,7 @@ fi
 AC_CHECK_HEADERS([nlist.h],
 [AC_CHECK_MEMBERS([struct nlist.n_un.n_name],
                   [], [],
-                  [@%:@include <nlist.h>])
+                  [#include <nlist.h>])
  AC_LINK_IFELSE([AC_LANG_PROGRAM([[#include <nlist.h>]],
                    [[struct nlist x;
                     #ifdef HAVE_STRUCT_NLIST_N_UN_N_NAME
diff --git a/m4/gnulib-common.m4 b/m4/gnulib-common.m4
index 03da2287d48..33e56faa98e 100644
--- a/m4/gnulib-common.m4
+++ b/m4/gnulib-common.m4
@@ -1,4 +1,4 @@
-# gnulib-common.m4 serial 55
+# gnulib-common.m4 serial 57
 dnl Copyright (C) 2007-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -480,14 +480,6 @@ AC_DEFUN([gl_FEATURES_H],
   AC_SUBST([HAVE_FEATURES_H])
 ])
 
-# AS_VAR_IF(VAR, VALUE, [IF-MATCH], [IF-NOT-MATCH])
-# ----------------------------------------------------
-# Backport of autoconf-2.63b's macro.
-# Remove this macro when we can assume autoconf >= 2.64.
-m4_ifndef([AS_VAR_IF],
-[m4_define([AS_VAR_IF],
-[AS_IF([test x"AS_VAR_GET([$1])" = x""$2], [$3], [$4])])])
-
 # gl_PROG_CC_C99
 # Modifies the value of the shell variable CC in an attempt to make $CC
 # understand ISO C99 source code.
@@ -660,6 +652,72 @@ AC_DEFUN([gl_CACHE_VAL_SILENT],
   as_echo_n="$saved_as_echo_n"
 ])
 
-# AS_VAR_COPY was added in autoconf 2.63b
-m4_define_default([AS_VAR_COPY],
-[AS_LITERAL_IF([$1[]$2], [$1=$$2], [eval $1=\$$2])])
+dnl Expands to some code for use in .c programs that, on native Windows, defines
+dnl the Microsoft deprecated alias function names to the underscore-prefixed
+dnl actual function names. With this macro, these function names are available
+dnl without linking with '-loldnames' and without generating warnings.
+dnl Usage: Use it after all system header files are included.
+dnl          #include <...>
+dnl          #include <...>
+dnl          ]GL_MDA_DEFINES[
+dnl          ...
+AC_DEFUN([GL_MDA_DEFINES],[
+AC_REQUIRE([_GL_MDA_DEFINES])
+[$gl_mda_defines]
+])
+AC_DEFUN([_GL_MDA_DEFINES],
+[gl_mda_defines='
+#if defined _WIN32 && !defined __CYGWIN__
+#define access    _access
+#define chdir     _chdir
+#define chmod     _chmod
+#define close     _close
+#define creat     _creat
+#define dup       _dup
+#define dup2      _dup2
+#define ecvt      _ecvt
+#define execl     _execl
+#define execle    _execle
+#define execlp    _execlp
+#define execv     _execv
+#define execve    _execve
+#define execvp    _execvp
+#define execvpe   _execvpe
+#define fcloseall _fcloseall
+#define fcvt      _fcvt
+#define fdopen    _fdopen
+#define fileno    _fileno
+#define gcvt      _gcvt
+#define getcwd    _getcwd
+#define getpid    _getpid
+#define getw      _getw
+#define isatty    _isatty
+#define j0        _j0
+#define j1        _j1
+#define jn        _jn
+#define lfind     _lfind
+#define lsearch   _lsearch
+#define lseek     _lseek
+#define memccpy   _memccpy
+#define mkdir     _mkdir
+#define mktemp    _mktemp
+#define open      _open
+#define putenv    _putenv
+#define putw      _putw
+#define read      _read
+#define rmdir     _rmdir
+#define strdup    _strdup
+#define swab      _swab
+#define tempnam   _tempnam
+#define tzset     _tzset
+#define umask     _umask
+#define unlink    _unlink
+#define utime     _utime
+#define wcsdup    _wcsdup
+#define write     _write
+#define y0        _y0
+#define y1        _y1
+#define yn        _yn
+#endif
+'
+])
diff --git a/m4/include_next.m4 b/m4/include_next.m4
index 9009e293b53..33601aa3b43 100644
--- a/m4/include_next.m4
+++ b/m4/include_next.m4
@@ -1,4 +1,4 @@
-# include_next.m4 serial 24
+# include_next.m4 serial 25
 dnl Copyright (C) 2006-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -176,42 +176,40 @@ AC_DEFUN([gl_NEXT_HEADERS_INTERNAL],
     [AC_CHECK_HEADERS_ONCE([$1])
     ])
 
-dnl FIXME: gl_next_header and gl_header_exists must be used unquoted
-dnl until we can assume autoconf 2.64 or newer.
   m4_foreach_w([gl_HEADER_NAME], [$1],
     [AS_VAR_PUSHDEF([gl_next_header],
                     [gl_cv_next_]m4_defn([gl_HEADER_NAME]))
      if test $gl_cv_have_include_next = yes; then
-       AS_VAR_SET(gl_next_header, ['<'gl_HEADER_NAME'>'])
+       AS_VAR_SET([gl_next_header], ['<'gl_HEADER_NAME'>'])
      else
        AC_CACHE_CHECK(
          [absolute name of <]m4_defn([gl_HEADER_NAME])[>],
-         m4_defn([gl_next_header]),
+         [gl_next_header],
          [m4_if([$2], [check],
             [AS_VAR_PUSHDEF([gl_header_exists],
                             [ac_cv_header_]m4_defn([gl_HEADER_NAME]))
-             if test AS_VAR_GET(gl_header_exists) = yes; then
+             if test AS_VAR_GET([gl_header_exists]) = yes; then
              AS_VAR_POPDEF([gl_header_exists])
             ])
            gl_ABSOLUTE_HEADER_ONE(gl_HEADER_NAME)
            AS_VAR_COPY([gl_header], [gl_cv_absolute_]AS_TR_SH(gl_HEADER_NAME))
-           AS_VAR_SET(gl_next_header, ['"'$gl_header'"'])
+           AS_VAR_SET([gl_next_header], ['"'$gl_header'"'])
           m4_if([$2], [check],
             [else
-               AS_VAR_SET(gl_next_header, ['<'gl_HEADER_NAME'>'])
+               AS_VAR_SET([gl_next_header], ['<'gl_HEADER_NAME'>'])
              fi
             ])
          ])
      fi
      AC_SUBST(
        AS_TR_CPP([NEXT_]m4_defn([gl_HEADER_NAME])),
-       [AS_VAR_GET(gl_next_header)])
+       [AS_VAR_GET([gl_next_header])])
      if test $gl_cv_have_include_next = yes || test $gl_cv_have_include_next = buggy; then
        # INCLUDE_NEXT_AS_FIRST_DIRECTIVE='include_next'
        gl_next_as_first_directive='<'gl_HEADER_NAME'>'
      else
        # INCLUDE_NEXT_AS_FIRST_DIRECTIVE='include'
-       gl_next_as_first_directive=AS_VAR_GET(gl_next_header)
+       gl_next_as_first_directive=AS_VAR_GET([gl_next_header])
      fi
      AC_SUBST(
        AS_TR_CPP([NEXT_AS_FIRST_DIRECTIVE_]m4_defn([gl_HEADER_NAME])),
diff --git a/m4/largefile.m4 b/m4/largefile.m4
index f7140dd0a3a..f4c5d3a5cea 100644
--- a/m4/largefile.m4
+++ b/m4/largefile.m4
@@ -30,12 +30,12 @@ m4_version_prereq([2.70], [] ,[
 # _AC_SYS_LARGEFILE_TEST_INCLUDES
 # -------------------------------
 m4_define([_AC_SYS_LARGEFILE_TEST_INCLUDES],
-[@%:@include <sys/types.h>
+[#include <sys/types.h>
  /* Check that off_t can represent 2**63 - 1 correctly.
     We can't simply define LARGE_OFF_T to be 9223372036854775807,
     since some C++ compilers masquerading as C compilers
     incorrectly reject 9223372036854775807.  */
-@%:@define LARGE_OFF_T (((off_t) 1 << 31 << 31) - 1 + ((off_t) 1 << 31 << 31))
+#define LARGE_OFF_T (((off_t) 1 << 31 << 31) - 1 + ((off_t) 1 << 31 << 31))
   int off_t_is_large[[(LARGE_OFF_T % 2147483629 == 721
                        && LARGE_OFF_T % 2147483647 == 1)
                       ? 1 : -1]];[]dnl
@@ -54,7 +54,7 @@ m4_define([_AC_SYS_LARGEFILE_MACRO_VALUE],
     [AC_LANG_PROGRAM([$5], [$6])],
     [$3=no; break])
   m4_ifval([$6], [AC_LINK_IFELSE], [AC_COMPILE_IFELSE])(
-    [AC_LANG_PROGRAM([@%:@define $1 $2
+    [AC_LANG_PROGRAM([#define $1 $2
 $5], [$6])],
     [$3=$2; break])
   $3=unknown
diff --git a/m4/manywarnings.m4 b/m4/manywarnings.m4
index d18da048d9e..a37cd15b69a 100644
--- a/m4/manywarnings.m4
+++ b/m4/manywarnings.m4
@@ -1,4 +1,4 @@
-# manywarnings.m4 serial 20
+# manywarnings.m4 serial 21
 dnl Copyright (C) 2008-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -39,8 +39,7 @@ AC_DEFUN([gl_MANYWARN_ALL_GCC],
 [_AC_LANG_DISPATCH([$0], _AC_LANG, $@)])
 
 # Specialization for _AC_LANG = C.
-# Use of m4_defun rather than AC_DEFUN works around a bug in autoconf < 2.63b.
-m4_defun([gl_MANYWARN_ALL_GCC(C)],
+AC_DEFUN([gl_MANYWARN_ALL_GCC(C)],
 [
   AC_LANG_PUSH([C])
 
@@ -210,8 +209,7 @@ m4_defun([gl_MANYWARN_ALL_GCC(C)],
 ])
 
 # Specialization for _AC_LANG = C++.
-# Use of m4_defun rather than AC_DEFUN works around a bug in autoconf < 2.63b.
-m4_defun([gl_MANYWARN_ALL_GCC(C++)],
+AC_DEFUN([gl_MANYWARN_ALL_GCC(C++)],
 [
   gl_MANYWARN_ALL_GCC_CXX_IMPL([$1])
 ])
diff --git a/m4/mktime.m4 b/m4/mktime.m4
index 8d9b827fe21..4e7e423fa54 100644
--- a/m4/mktime.m4
+++ b/m4/mktime.m4
@@ -1,4 +1,4 @@
-# serial 32
+# serial 35
 dnl Copyright (C) 2002-2003, 2005-2007, 2009-2020 Free Software Foundation,
 dnl Inc.
 dnl This file is free software; the Free Software Foundation
@@ -31,7 +31,6 @@ AC_DEFUN([gl_FUNC_MKTIME_WORKS],
   dnl in Autoconf and because it invokes AC_LIBOBJ.
   AC_CHECK_HEADERS_ONCE([unistd.h])
   AC_CHECK_DECLS_ONCE([alarm])
-  AC_CHECK_FUNCS_ONCE([tzset])
   AC_REQUIRE([gl_MULTIARCH])
   AC_CACHE_CHECK([for working mktime], [gl_cv_func_working_mktime],
     [if test $APPLE_UNIVERSAL_BUILD = 1; then
@@ -55,13 +54,12 @@ AC_DEFUN([gl_FUNC_MKTIME_WORKS],
 # include <signal.h>
 #endif
 
+]GL_MDA_DEFINES[
+
 #ifndef TIME_T_IS_SIGNED
 # define TIME_T_IS_SIGNED 0
 #endif
 
-/* Work around redefinition to rpl_putenv by other config tests.  */
-#undef putenv
-
 static time_t time_t_max;
 static time_t time_t_min;
 
diff --git a/m4/nstrftime.m4 b/m4/nstrftime.m4
index 6f2762aa276..e4eb87de0b9 100644
--- a/m4/nstrftime.m4
+++ b/m4/nstrftime.m4
@@ -1,4 +1,4 @@
-# serial 35
+# serial 36
 
 # Copyright (C) 1996-1997, 1999-2007, 2009-2020 Free Software Foundation, Inc.
 #
@@ -17,8 +17,6 @@ AC_DEFUN([gl_FUNC_GNU_STRFTIME],
 
  AC_REQUIRE([gl_TM_GMTOFF])
 
- AC_CHECK_FUNCS_ONCE([tzset])
-
  AC_DEFINE([my_strftime], [nstrftime],
    [Define to the name of the strftime replacement function.])
 ])
diff --git a/m4/open-slash.m4 b/m4/open-slash.m4
index 1e57c96960e..5d84f2b548a 100644
--- a/m4/open-slash.m4
+++ b/m4/open-slash.m4
@@ -1,4 +1,4 @@
-# open-slash.m4 serial 1
+# open-slash.m4 serial 2
 dnl Copyright (C) 2007-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -25,6 +25,7 @@ AC_DEFUN([gl_OPEN_TRAILING_SLASH_BUG],
 #if HAVE_UNISTD_H
 # include <unistd.h>
 #endif
+]GL_MDA_DEFINES[
 int main ()
 {
   int result = 0;
diff --git a/m4/pselect.m4 b/m4/pselect.m4
index f3e5afe0b38..08a5823c6f9 100644
--- a/m4/pselect.m4
+++ b/m4/pselect.m4
@@ -1,4 +1,4 @@
-# pselect.m4 serial 8
+# pselect.m4 serial 9
 dnl Copyright (C) 2011-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -37,7 +37,8 @@ AC_DEFUN([gl_FUNC_PSELECT],
 #endif
 #include <unistd.h>
 #include <errno.h>
-]],[[
+]GL_MDA_DEFINES],
+[[
   fd_set set;
   dup2(0, 16);
   FD_ZERO(&set);
diff --git a/m4/pthread_sigmask.m4 b/m4/pthread_sigmask.m4
index d67511f73dd..030862de015 100644
--- a/m4/pthread_sigmask.m4
+++ b/m4/pthread_sigmask.m4
@@ -1,4 +1,4 @@
-# pthread_sigmask.m4 serial 18
+# pthread_sigmask.m4 serial 19
 dnl Copyright (C) 2011-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -220,6 +220,7 @@ int main ()
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
+]GL_MDA_DEFINES[
 static volatile int sigint_occurred;
 static void
 sigint_handler (int sig)
diff --git a/m4/time_h.m4 b/m4/time_h.m4
index d0f89327c4b..a15c09dc07b 100644
--- a/m4/time_h.m4
+++ b/m4/time_h.m4
@@ -121,7 +121,6 @@ AC_DEFUN([gl_HEADER_TIME_H_DEFAULTS],
   HAVE_NANOSLEEP=1;                      AC_SUBST([HAVE_NANOSLEEP])
   HAVE_STRPTIME=1;                       AC_SUBST([HAVE_STRPTIME])
   HAVE_TIMEGM=1;                         AC_SUBST([HAVE_TIMEGM])
-  HAVE_TZSET=1;                          AC_SUBST([HAVE_TZSET])
   dnl Even GNU libc does not have timezone_t yet.
   HAVE_TIMEZONE_T=0;                     AC_SUBST([HAVE_TIMEZONE_T])
   dnl If another module says to replace or to not replace, do that.
diff --git a/m4/utimens.m4 b/m4/utimens.m4
index 65617ac862c..3d31085fc6d 100644
--- a/m4/utimens.m4
+++ b/m4/utimens.m4
@@ -3,7 +3,7 @@ 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 serial 10
+dnl serial 11
 
 AC_DEFUN([gl_UTIMENS],
 [
@@ -24,7 +24,8 @@ AC_DEFUN([gl_UTIMENS],
 #include <stddef.h>
 #include <sys/times.h>
 #include <fcntl.h>
-]], [[    int fd = open ("conftest.file", O_RDWR);
+]GL_MDA_DEFINES],
+        [[int fd = open ("conftest.file", O_RDWR);
           if (fd < 0) return 1;
           if (futimesat (fd, NULL, NULL)) return 2;
         ]])],
diff --git a/m4/utimensat.m4 b/m4/utimensat.m4
index 2bc1bfebb5d..e9e4f26b1c1 100644
--- a/m4/utimensat.m4
+++ b/m4/utimensat.m4
@@ -1,4 +1,4 @@
-# serial 6
+# serial 7
 # See if we need to provide utimensat replacement.
 
 dnl Copyright (C) 2009-2020 Free Software Foundation, Inc.
@@ -23,7 +23,8 @@ AC_DEFUN([gl_FUNC_UTIMENSAT],
 #include <fcntl.h>
 #include <sys/stat.h>
 #include <unistd.h>
-]],         [[int result = 0;
+]GL_MDA_DEFINES],
+            [[int result = 0;
               const char *f = "conftest.file";
               if (close (creat (f, 0600)))
                 return 1;
diff --git a/m4/utimes.m4 b/m4/utimes.m4
index e1056bbba4e..877bfd2a735 100644
--- a/m4/utimes.m4
+++ b/m4/utimes.m4
@@ -1,5 +1,5 @@
 # Detect some bugs in glibc's implementation of utimes.
-# serial 7
+# serial 8
 
 dnl Copyright (C) 2003-2005, 2009-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
@@ -34,6 +34,7 @@ AC_DEFUN([gl_FUNC_UTIMES],
 #include <stdio.h>
 #include <utime.h>
 #include <errno.h>
+]GL_MDA_DEFINES[
 
 static int
 inorder (time_t a, time_t b, time_t c)
diff --git a/m4/warnings.m4 b/m4/warnings.m4
index d272365f0a1..d4e4b073453 100644
--- a/m4/warnings.m4
+++ b/m4/warnings.m4
@@ -1,4 +1,4 @@
-# warnings.m4 serial 14
+# warnings.m4 serial 16
 dnl Copyright (C) 2008-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -23,8 +23,6 @@ m4_ifdef([AS_VAR_APPEND],
 # The effects of this macro depend on the current language (_AC_LANG).
 AC_DEFUN([gl_COMPILER_OPTION_IF],
 [
-dnl FIXME: gl_Warn must be used unquoted until we can assume Autoconf
-dnl 2.64 or newer.
 AS_VAR_PUSHDEF([gl_Warn], [gl_cv_warn_[]_AC_LANG_ABBREV[]_$1])dnl
 AS_VAR_PUSHDEF([gl_Flags], [_AC_LANG_PREFIX[]FLAGS])dnl
 AS_LITERAL_IF([$1],
@@ -34,13 +32,13 @@ case $gl_positive in
   -Wno-*) gl_positive=-W`expr "X$gl_positive" : 'X-Wno-\(.*\)'` ;;
 esac
 m4_pushdef([gl_Positive], [$gl_positive])])dnl
-AC_CACHE_CHECK([whether _AC_LANG compiler handles $1], m4_defn([gl_Warn]), [
+AC_CACHE_CHECK([whether _AC_LANG compiler handles $1], [gl_Warn], [
   gl_save_compiler_FLAGS="$gl_Flags"
   gl_AS_VAR_APPEND(m4_defn([gl_Flags]),
     [" $gl_unknown_warnings_are_errors ]m4_defn([gl_Positive])["])
-  AC_LINK_IFELSE([m4_default([$4], [AC_LANG_PROGRAM([])])],
-                 [AS_VAR_SET(gl_Warn, [yes])],
-                 [AS_VAR_SET(gl_Warn, [no])])
+  AC_LINK_IFELSE([m4_default([$4], [AC_LANG_PROGRAM([[]])])],
+                 [AS_VAR_SET([gl_Warn], [yes])],
+                 [AS_VAR_SET([gl_Warn], [no])])
   gl_Flags="$gl_save_compiler_FLAGS"
 ])
 AS_VAR_IF(gl_Warn, [yes], [$2], [$3])
@@ -59,8 +57,7 @@ AC_DEFUN([gl_UNKNOWN_WARNINGS_ARE_ERRORS],
 [_AC_LANG_DISPATCH([$0], _AC_LANG, $@)])
 
 # Specialization for _AC_LANG = C. This macro can be AC_REQUIREd.
-# Use of m4_defun rather than AC_DEFUN works around a bug in autoconf < 2.63b.
-m4_defun([gl_UNKNOWN_WARNINGS_ARE_ERRORS(C)],
+AC_DEFUN([gl_UNKNOWN_WARNINGS_ARE_ERRORS(C)],
 [
   AC_LANG_PUSH([C])
   gl_UNKNOWN_WARNINGS_ARE_ERRORS_IMPL
@@ -68,8 +65,7 @@ m4_defun([gl_UNKNOWN_WARNINGS_ARE_ERRORS(C)],
 ])
 
 # Specialization for _AC_LANG = C++. This macro can be AC_REQUIREd.
-# Use of m4_defun rather than AC_DEFUN works around a bug in autoconf < 2.63b.
-m4_defun([gl_UNKNOWN_WARNINGS_ARE_ERRORS(C++)],
+AC_DEFUN([gl_UNKNOWN_WARNINGS_ARE_ERRORS(C++)],
 [
   AC_LANG_PUSH([C++])
   gl_UNKNOWN_WARNINGS_ARE_ERRORS_IMPL
@@ -77,8 +73,7 @@ m4_defun([gl_UNKNOWN_WARNINGS_ARE_ERRORS(C++)],
 ])
 
 # Specialization for _AC_LANG = Objective C. This macro can be AC_REQUIREd.
-# Use of m4_defun rather than AC_DEFUN works around a bug in autoconf < 2.63b.
-m4_defun([gl_UNKNOWN_WARNINGS_ARE_ERRORS(Objective C)],
+AC_DEFUN([gl_UNKNOWN_WARNINGS_ARE_ERRORS(Objective C)],
 [
   AC_LANG_PUSH([Objective C])
   gl_UNKNOWN_WARNINGS_ARE_ERRORS_IMPL