Imported Upstream version 1.21upstream/1.21

270 files changed, 6675 insertions, 3322 deletions

diff --git a/m4/00gnulib.m4 b/m4/00gnulib.m4
index e3e0fb6..14628c3 100644
--- a/m4/00gnulib.m4
+++ b/m4/00gnulib.m4
@@ -1,43 +1,82 @@
-# 00gnulib.m4 serial 3
-dnl Copyright (C) 2009-2019 Free Software Foundation, Inc.
+# 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.  It is needed until such time as we can
-dnl assume Autoconf 2.64, with its improved AC_DEFUN_ONCE and
-dnl m4_divert semantics.
+dnl gnulib-provided .m4 files.  It is needed until the clang fix has
+dnl 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])])])
+# The following definitions arrange to use a compiler option
+# -Werror=implicit-function-declaration in AC_CHECK_DECL, when the
+# compiler is clang.  Without it, clang implicitly declares "known"
+# library functions in C mode, but not in C++ mode, which would cause
+# Gnulib to omit a declaration and thus later produce an error in C++
+# mode.  As of clang 9.0, these "known" functions are identified through
+# LIBBUILTIN invocations in the LLVM source file
+# llvm/tools/clang/include/clang/Basic/Builtins.def.
+# It's not possible to AC_REQUIRE the extra tests from AC_CHECK_DECL,
+# because AC_CHECK_DECL, like other Autoconf built-ins, is not supposed
+# to AC_REQUIRE anything: some configure.ac files have their first
+# AC_CHECK_DECL executed conditionally.  Therefore append the extra tests
+# to AC_PROG_CC.
+AC_DEFUN([gl_COMPILER_CLANG],
+[
+dnl AC_REQUIRE([AC_PROG_CC])
+  AC_CACHE_CHECK([whether the compiler is clang],
+    [gl_cv_compiler_clang],
+    [dnl Use _AC_COMPILE_IFELSE instead of AC_EGREP_CPP, to avoid error
+     dnl "circular dependency of AC_LANG_COMPILER(C)" if AC_PROG_CC has
+     dnl not yet been invoked.
+     _AC_COMPILE_IFELSE(
+        [AC_LANG_PROGRAM([[
+           #ifdef __clang__
+           barfbarf
+           #endif
+           ]],[[]])
+        ],
+        [gl_cv_compiler_clang=no],
+        [gl_cv_compiler_clang=yes])
+    ])
+])
+AC_DEFUN([gl_COMPILER_PREPARE_CHECK_DECL],
+[
+dnl AC_REQUIRE([AC_PROG_CC])
+dnl AC_REQUIRE([gl_COMPILER_CLANG])
+  AC_CACHE_CHECK([for compiler option needed when checking for declarations],
+    [gl_cv_compiler_check_decl_option],
+    [if test $gl_cv_compiler_clang = yes; then
+       dnl Test whether the compiler supports the option
+       dnl '-Werror=implicit-function-declaration'.
+       save_ac_compile="$ac_compile"
+       ac_compile="$ac_compile -Werror=implicit-function-declaration"
+       dnl Use _AC_COMPILE_IFELSE instead of AC_COMPILE_IFELSE, to avoid a
+       dnl warning "AC_COMPILE_IFELSE was called before AC_USE_SYSTEM_EXTENSIONS".
+       _AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]],[[]])],
+         [gl_cv_compiler_check_decl_option='-Werror=implicit-function-declaration'],
+         [gl_cv_compiler_check_decl_option=none])
+       ac_compile="$save_ac_compile"
+     else
+       gl_cv_compiler_check_decl_option=none
+     fi
+    ])
+  if test "x$gl_cv_compiler_check_decl_option" != xnone; then
+    ac_compile_for_check_decl="$ac_compile $gl_cv_compiler_check_decl_option"
+  else
+    ac_compile_for_check_decl="$ac_compile"
+  fi
+])
+dnl Redefine _AC_CHECK_DECL_BODY so that it references ac_compile_for_check_decl
+dnl instead of ac_compile.  If, for whatever reason, the override of AC_PROG_CC
+dnl in zzgnulib.m4 is inactive, use the original ac_compile.
+m4_define([_AC_CHECK_DECL_BODY],
+[  ac_save_ac_compile="$ac_compile"
+  if test -n "$ac_compile_for_check_decl"; then
+    ac_compile="$ac_compile_for_check_decl"
+  fi]
+m4_defn([_AC_CHECK_DECL_BODY])[  ac_compile="$ac_save_ac_compile"
+])
 
 # gl_00GNULIB
 # -----------
diff --git a/m4/__inline.m4 b/m4/__inline.m4
index e1aa310..520c8c4 100644
--- a/m4/__inline.m4
+++ b/m4/__inline.m4
@@ -1,5 +1,5 @@
 # Test for __inline keyword
-dnl Copyright 2017-2019 Free Software Foundation, Inc.
+dnl Copyright 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.
diff --git a/m4/absolute-header.m4 b/m4/absolute-header.m4
index a8f2cba..c043233 100644
--- a/m4/absolute-header.m4
+++ b/m4/absolute-header.m4
@@ -1,5 +1,5 @@
-# absolute-header.m4 serial 16
-dnl Copyright (C) 2006-2019 Free Software Foundation, Inc.
+# 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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -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], [$1],
   [AS_VAR_PUSHDEF([gl_absolute_header],
                   [gl_cv_absolute_]m4_defn([gl_HEADER_NAME]))dnl
   AC_CACHE_CHECK([absolute name of <]m4_defn([gl_HEADER_NAME])[>],
-    m4_defn([gl_absolute_header]),
+    [gl_absolute_header],
     [AS_VAR_PUSHDEF([ac_header_exists],
                     [ac_cv_header_]m4_defn([gl_HEADER_NAME]))dnl
     AC_CHECK_HEADERS_ONCE(m4_defn([gl_HEADER_NAME]))dnl
-    if test AS_VAR_GET(ac_header_exists) = yes; then
+    if test AS_VAR_GET([ac_header_exists]) = yes; then
       gl_ABSOLUTE_HEADER_ONE(m4_defn([gl_HEADER_NAME]))
     fi
     AS_VAR_POPDEF([ac_header_exists])dnl
     ])dnl
   AC_DEFINE_UNQUOTED(AS_TR_CPP([ABSOLUTE_]m4_defn([gl_HEADER_NAME])),
-                     ["AS_VAR_GET(gl_absolute_header)"],
+                     ["AS_VAR_GET([gl_absolute_header])"],
                      [Define this to an absolute name of <]m4_defn([gl_HEADER_NAME])[>.])
   AS_VAR_POPDEF([gl_absolute_header])dnl
 ])dnl
diff --git a/m4/access.m4 b/m4/access.m4
new file mode 100644
index 0000000..cfe799d
--- /dev/null
+++ b/m4/access.m4
@@ -0,0 +1,16 @@
+# access.m4 serial 1
+dnl Copyright (C) 2019-2020 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_FUNC_ACCESS],
+[
+  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  dnl On native Windows, access (= _access) does not support the X_OK mode.
+  dnl It works by chance on some versions of mingw.
+  case "$host_os" in
+    mingw*) REPLACE_ACCESS=1 ;;
+  esac
+])
diff --git a/m4/af_alg.m4 b/m4/af_alg.m4
index 498c933..418d690 100644
--- a/m4/af_alg.m4
+++ b/m4/af_alg.m4
@@ -1,5 +1,5 @@
 # af_alg.m4 serial 4
-dnl Copyright 2018-2019 Free Software Foundation, Inc.
+dnl Copyright 2018-2020 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.
diff --git a/m4/alloca.m4 b/m4/alloca.m4
index 29bd289..e3c377c 100644
--- a/m4/alloca.m4
+++ b/m4/alloca.m4
@@ -1,5 +1,5 @@
-# alloca.m4 serial 15
-dnl Copyright (C) 2002-2004, 2006-2007, 2009-2019 Free Software Foundation,
+# alloca.m4 serial 20
+dnl Copyright (C) 2002-2004, 2006-2007, 2009-2020 Free Software Foundation,
 dnl Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -50,13 +50,13 @@ AC_DEFUN([gl_FUNC_ALLOCA],
 # STACK_DIRECTION is already handled by AC_FUNC_ALLOCA.
 AC_DEFUN([gl_PREREQ_ALLOCA], [:])
 
-# This works around a bug in autoconf <= 2.68.
-# See <https://lists.gnu.org/r/bug-gnulib/2011-06/msg00277.html>.
+m4_version_prereq([2.70], [], [
 
-m4_version_prereq([2.69], [] ,[
-
-# This is taken from the following Autoconf patch:
-# https://git.savannah.gnu.org/gitweb/?p=autoconf.git;a=commitdiff;h=6cd9f12520b0d6f76d3230d7565feba1ecf29497
+# This works around a bug in autoconf <= 2.68 and has simplifications
+# from 2.70.  See:
+# https://lists.gnu.org/r/bug-gnulib/2011-06/msg00277.html
+# https://git.savannah.gnu.org/cgit/autoconf.git/commit/?id=6cd9f12520b0d6f76d3230d7565feba1ecf29497
+# https://git.savannah.gnu.org/cgit/autoconf.git/commit/?id=15edf7fd8094fd14a89d9891dd72a9624762597a
 
 # _AC_LIBOBJ_ALLOCA
 # -----------------
@@ -72,26 +72,6 @@ AC_LIBSOURCES(alloca.c)
 AC_SUBST([ALLOCA], [\${LIBOBJDIR}alloca.$ac_objext])dnl
 AC_DEFINE(C_ALLOCA, 1, [Define to 1 if using 'alloca.c'.])
 
-AC_CACHE_CHECK(whether 'alloca.c' needs Cray hooks, ac_cv_os_cray,
-[AC_EGREP_CPP(webecray,
-[#if defined CRAY && ! defined CRAY2
-webecray
-#else
-wenotbecray
-#endif
-], ac_cv_os_cray=yes, ac_cv_os_cray=no)])
-if test $ac_cv_os_cray = yes; then
-  for ac_func in _getb67 GETB67 getb67; do
-    AC_CHECK_FUNC($ac_func,
-                  [AC_DEFINE_UNQUOTED(CRAY_STACKSEG_END, $ac_func,
-                                      [Define to one of '_getb67', 'GETB67',
-                                       'getb67' for Cray-2 and Cray-YMP
-                                       systems. This function is required for
-                                       'alloca.c' support on those systems.])
-    break])
-  done
-fi
-
 AC_CACHE_CHECK([stack direction for C alloca],
                [ac_cv_c_stack_direction],
 [AC_RUN_IFELSE([AC_LANG_SOURCE(
@@ -122,7 +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)
 ])# _AC_LIBOBJ_ALLOCA
 ])
diff --git a/m4/arpa_inet_h.m4 b/m4/arpa_inet_h.m4
index 46c7d28..b394494 100644
--- a/m4/arpa_inet_h.m4
+++ b/m4/arpa_inet_h.m4
@@ -1,5 +1,5 @@
-# arpa_inet_h.m4 serial 13
-dnl Copyright (C) 2006, 2008-2019 Free Software Foundation, Inc.
+# arpa_inet_h.m4 serial 14
+dnl Copyright (C) 2006, 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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -24,6 +24,8 @@ AC_DEFUN([gl_HEADER_ARPA_INET],
 
   AC_REQUIRE([gl_FEATURES_H])
 
+  gl_PREREQ_SYS_H_WS2TCPIP
+
   dnl Check for declarations of anything we want to poison if the
   dnl corresponding gnulib module is not in use.
   gl_WARN_ON_USE_PREPARE([[
diff --git a/m4/asm-underscore.m4 b/m4/asm-underscore.m4
index 0f6bee4..6446e71 100644
--- a/m4/asm-underscore.m4
+++ b/m4/asm-underscore.m4
@@ -1,5 +1,5 @@
-# asm-underscore.m4 serial 4
-dnl Copyright (C) 2010-2019 Free Software Foundation, Inc.
+# asm-underscore.m4 serial 5
+dnl Copyright (C) 2010-2020 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.
@@ -63,8 +63,19 @@ AC_DEFUN([gl_C_ASM],
 MicrosoftCompiler
 #endif
     ],
-    [gl_asmext='asm'
-     gl_c_asm_opt='-c -Fa'
+    [dnl Microsoft's 'cl' and 'clang-cl' produce an .asm file, whereas 'clang'
+     dnl produces a .s file. Need to distinguish 'clang' and 'clang-cl'.
+     rm -f conftest*
+     echo 'int dummy;' > conftest.c
+     AC_TRY_COMMAND(${CC-cc} $CFLAGS $CPPFLAGS -c conftest.c) >/dev/null 2>&1
+     if test -f conftest.o; then
+       gl_asmext='s'
+       gl_c_asm_opt='-S'
+     else
+       gl_asmext='asm'
+       gl_c_asm_opt='-c -Fa'
+     fi
+     rm -f conftest*
     ],
     [gl_asmext='s'
      gl_c_asm_opt='-S'
diff --git a/m4/base32.m4 b/m4/base32.m4
index 8eb4cec..2d07d44 100644
--- a/m4/base32.m4
+++ b/m4/base32.m4
@@ -1,5 +1,5 @@
 # base32.m4 serial 4
-dnl Copyright (C) 2004, 2006, 2009-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2004, 2006, 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.
diff --git a/m4/btowc.m4 b/m4/btowc.m4
index 85c2cbf..ec19ea0 100644
--- a/m4/btowc.m4
+++ b/m4/btowc.m4
@@ -1,5 +1,5 @@
-# btowc.m4 serial 11
-dnl Copyright (C) 2008-2019 Free Software Foundation, Inc.
+# btowc.m4 serial 12
+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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -28,14 +28,6 @@ AC_DEFUN([gl_FUNC_BTOWC],
       [
         AC_RUN_IFELSE(
           [AC_LANG_SOURCE([[
-#include <string.h>
-/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
-   <wchar.h>.
-   BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be
-   included before <wchar.h>.  */
-#include <stddef.h>
-#include <stdio.h>
-#include <time.h>
 #include <wchar.h>
 int main ()
 {
@@ -79,14 +71,7 @@ changequote([,])dnl
           AC_RUN_IFELSE(
             [AC_LANG_SOURCE([[
 #include <locale.h>
-#include <string.h>
-/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
-   <wchar.h>.
-   BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be
-   included before <wchar.h>.  */
-#include <stddef.h>
 #include <stdio.h>
-#include <time.h>
 #include <wchar.h>
 int main ()
 {
diff --git a/m4/builtin-expect.m4 b/m4/builtin-expect.m4
index b65fbf8..a6e8895 100644
--- a/m4/builtin-expect.m4
+++ b/m4/builtin-expect.m4
@@ -1,6 +1,6 @@
 dnl Check for __builtin_expect.
 
-dnl Copyright 2016-2019 Free Software Foundation, Inc.
+dnl Copyright 2016-2020 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.
diff --git a/m4/byteswap.m4 b/m4/byteswap.m4
index 05fc6cd..0f43994 100644
--- a/m4/byteswap.m4
+++ b/m4/byteswap.m4
@@ -1,5 +1,5 @@
 # byteswap.m4 serial 4
-dnl Copyright (C) 2005, 2007, 2009-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/canonicalize.m4 b/m4/canonicalize.m4
new file mode 100644
index 0000000..404db4c
--- /dev/null
+++ b/m4/canonicalize.m4
@@ -0,0 +1,145 @@
+# canonicalize.m4 serial 35
+
+dnl Copyright (C) 2003-2007, 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,
+dnl with or without modifications, as long as this notice is preserved.
+
+# Provides canonicalize_file_name and canonicalize_filename_mode, but does
+# not provide or fix realpath.
+AC_DEFUN([gl_FUNC_CANONICALIZE_FILENAME_MODE],
+[
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+  AC_REQUIRE([gl_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK])
+  AC_CHECK_FUNCS_ONCE([canonicalize_file_name faccessat])
+  AC_REQUIRE([gl_DOUBLE_SLASH_ROOT])
+  AC_REQUIRE([gl_FUNC_REALPATH_WORKS])
+  if test $ac_cv_func_canonicalize_file_name = no; then
+    HAVE_CANONICALIZE_FILE_NAME=0
+  else
+    case "$gl_cv_func_realpath_works" in
+      *yes) ;;
+      *)    REPLACE_CANONICALIZE_FILE_NAME=1 ;;
+    esac
+  fi
+])
+
+# Provides canonicalize_file_name and realpath.
+AC_DEFUN([gl_CANONICALIZE_LGPL],
+[
+  AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
+  AC_REQUIRE([gl_CANONICALIZE_LGPL_SEPARATE])
+  if test $ac_cv_func_canonicalize_file_name = no; then
+    HAVE_CANONICALIZE_FILE_NAME=0
+    if test $ac_cv_func_realpath = no; then
+      HAVE_REALPATH=0
+    else
+      case "$gl_cv_func_realpath_works" in
+        *yes) ;;
+        *)    REPLACE_REALPATH=1 ;;
+      esac
+    fi
+  else
+    case "$gl_cv_func_realpath_works" in
+      *yes)
+        ;;
+      *)
+        REPLACE_CANONICALIZE_FILE_NAME=1
+        REPLACE_REALPATH=1
+        ;;
+    esac
+  fi
+])
+
+# Like gl_CANONICALIZE_LGPL, except prepare for separate compilation
+# (no REPLACE_CANONICALIZE_FILE_NAME, no REPLACE_REALPATH, no AC_LIBOBJ).
+AC_DEFUN([gl_CANONICALIZE_LGPL_SEPARATE],
+[
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+  AC_REQUIRE([gl_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK])
+  AC_CHECK_FUNCS_ONCE([canonicalize_file_name faccessat])
+
+  dnl On native Windows, we use _getcwd(), regardless whether getcwd() is
+  dnl available through the linker option '-loldnames'.
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  case "$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])
+])
+
+# Check whether realpath works.  Assume that if a platform has both
+# realpath and canonicalize_file_name, but the former is broken, then
+# so is the latter.
+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([
+      AC_LANG_PROGRAM([[
+        ]GL_NOCRASH[
+        #include <stdlib.h>
+        #include <string.h>
+      ]], [[
+        int result = 0;
+        {
+          char *name = realpath ("conftest.a", NULL);
+          if (!(name && *name == '/'))
+            result |= 1;
+          free (name);
+        }
+        {
+          char *name = realpath ("conftest.b/../conftest.a", NULL);
+          if (name != NULL)
+            result |= 2;
+          free (name);
+        }
+        {
+          char *name = realpath ("conftest.a/", NULL);
+          if (name != NULL)
+            result |= 4;
+          free (name);
+        }
+        {
+          char *name1 = realpath (".", NULL);
+          char *name2 = realpath ("conftest.d//./..", NULL);
+          if (! name1 || ! name2 || strcmp (name1, name2))
+            result |= 8;
+          free (name1);
+          free (name2);
+        }
+        return result;
+      ]])
+     ],
+     [gl_cv_func_realpath_works=yes],
+     [gl_cv_func_realpath_works=no],
+     [case "$host_os" in
+                       # Guess yes on glibc systems.
+        *-gnu* | gnu*) gl_cv_func_realpath_works="guessing yes" ;;
+                       # Guess yes on musl systems.
+        *-musl*)       gl_cv_func_realpath_works="guessing yes" ;;
+                       # Guess no on native Windows.
+        mingw*)        gl_cv_func_realpath_works="guessing no" ;;
+                       # If we don't know, obey --enable-cross-guesses.
+        *)             gl_cv_func_realpath_works="$gl_cross_guess_normal" ;;
+      esac
+     ])
+    rm -rf conftest.a conftest.d
+  ])
+  case "$gl_cv_func_realpath_works" in
+    *yes)
+      AC_DEFINE([FUNC_REALPATH_WORKS], [1], [Define to 1 if realpath()
+        can malloc memory, always gives an absolute path, and handles
+        trailing slash correctly.])
+      ;;
+  esac
+])
diff --git a/m4/chdir-long.m4 b/m4/chdir-long.m4
new file mode 100644
index 0000000..a6e67b5
--- /dev/null
+++ b/m4/chdir-long.m4
@@ -0,0 +1,30 @@
+#serial 17
+
+# Use Gnulib's robust chdir function.
+# It can handle arbitrarily long directory names, which means
+# that when it is given the name of an existing directory, it
+# never fails with ENAMETOOLONG.
+# Arrange to compile chdir-long.c only on systems that define PATH_MAX.
+
+dnl Copyright (C) 2004-2007, 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,
+dnl with or without modifications, as long as this notice is preserved.
+
+# Written by Jim Meyering.
+
+AC_DEFUN([gl_FUNC_CHDIR_LONG],
+[
+  AC_REQUIRE([gl_PATHMAX_SNIPPET_PREREQ])
+  AC_CACHE_CHECK([whether this system supports file names of any length],
+    [gl_cv_have_unlimited_file_name_length],
+    [AC_EGREP_CPP([have_arbitrary_file_name_length_limit],
+                  gl_PATHMAX_SNIPPET[
+#ifdef PATH_MAX
+have_arbitrary_file_name_length_limit
+#endif],
+    [gl_cv_have_unlimited_file_name_length=no],
+    [gl_cv_have_unlimited_file_name_length=yes])])
+])
+
+AC_DEFUN([gl_PREREQ_CHDIR_LONG], [:])
diff --git a/m4/clock_time.m4 b/m4/clock_time.m4
index 8f7a7fc..f4f51fa 100644
--- a/m4/clock_time.m4
+++ b/m4/clock_time.m4
@@ -1,5 +1,5 @@
 # clock_time.m4 serial 10
-dnl Copyright (C) 2002-2006, 2009-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2002-2006, 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.
diff --git a/m4/close.m4 b/m4/close.m4
index 7013a13..378ec4c 100644
--- a/m4/close.m4
+++ b/m4/close.m4
@@ -1,5 +1,5 @@
 # close.m4 serial 9
-dnl Copyright (C) 2008-2019 Free Software Foundation, Inc.
+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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/closedir.m4 b/m4/closedir.m4
new file mode 100644
index 0000000..66f6d4e
--- /dev/null
+++ b/m4/closedir.m4
@@ -0,0 +1,31 @@
+# closedir.m4 serial 6
+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,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_FUNC_CLOSEDIR],
+[
+  AC_REQUIRE([gl_DIRENT_H_DEFAULTS])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+
+  AC_CHECK_FUNCS([closedir])
+  if test $ac_cv_func_closedir = no; then
+    HAVE_CLOSEDIR=0
+  fi
+  dnl Replace closedir() for supporting the gnulib-defined fchdir() function,
+  dnl to keep fchdir's bookkeeping up-to-date.
+  m4_ifdef([gl_FUNC_FCHDIR], [
+    gl_TEST_FCHDIR
+    if test $HAVE_FCHDIR = 0; then
+      if test $HAVE_CLOSEDIR = 1; then
+        REPLACE_CLOSEDIR=1
+      fi
+    fi
+  ])
+  dnl Replace closedir() for supporting the gnulib-defined dirfd() function.
+  case $host_os,$HAVE_CLOSEDIR in
+    os2*,1)
+      REPLACE_CLOSEDIR=1;;
+  esac
+])
diff --git a/m4/codeset.m4 b/m4/codeset.m4
index 280f556..9b019cf 100644
--- a/m4/codeset.m4
+++ b/m4/codeset.m4
@@ -1,5 +1,5 @@
 # codeset.m4 serial 5 (gettext-0.18.2)
-dnl Copyright (C) 2000-2002, 2006, 2008-2014, 2016, 2019 Free Software
+dnl Copyright (C) 2000-2002, 2006, 2008-2014, 2016, 2019-2020 Free Software
 dnl Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
diff --git a/m4/ctype.m4 b/m4/ctype.m4
new file mode 100644
index 0000000..0b123d5
--- /dev/null
+++ b/m4/ctype.m4
@@ -0,0 +1,32 @@
+# ctype_h.m4 serial 6
+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.
+
+AC_DEFUN([gl_CTYPE_H],
+[
+  AC_REQUIRE([gl_CTYPE_H_DEFAULTS])
+
+  dnl <ctype.h> is always overridden, because of GNULIB_POSIXCHECK.
+  gl_NEXT_HEADERS([ctype.h])
+
+  dnl Check for declarations of anything we want to poison if the
+  dnl corresponding gnulib module is not in use.
+  gl_WARN_ON_USE_PREPARE([[#include <ctype.h>
+    ]], [isblank])
+])
+
+AC_DEFUN([gl_CTYPE_MODULE_INDICATOR],
+[
+  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
+  AC_REQUIRE([gl_CTYPE_H_DEFAULTS])
+  gl_MODULE_INDICATOR_SET_VARIABLE([$1])
+])
+
+AC_DEFUN([gl_CTYPE_H_DEFAULTS],
+[
+  GNULIB_ISBLANK=0; AC_SUBST([GNULIB_ISBLANK])
+  dnl Assume proper GNU behavior unless another module says otherwise.
+  HAVE_ISBLANK=1;   AC_SUBST([HAVE_ISBLANK])
+])
diff --git a/m4/d-ino.m4 b/m4/d-ino.m4
new file mode 100644
index 0000000..64ce9ce
--- /dev/null
+++ b/m4/d-ino.m4
@@ -0,0 +1,60 @@
+# serial 20
+
+dnl From Jim Meyering.
+dnl
+dnl Check whether struct dirent has a member named d_ino.
+dnl
+
+# Copyright (C) 1997, 1999-2001, 2003-2004, 2006-2007, 2009-2020 Free Software
+# Foundation, Inc.
+
+# This file is free software; the Free Software Foundation
+# gives unlimited permission to copy and/or distribute it,
+# with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_CHECK_TYPE_STRUCT_DIRENT_D_INO],
+  [AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+   AC_CACHE_CHECK([for d_ino member in directory struct],
+                  [gl_cv_struct_dirent_d_ino],
+     [AC_RUN_IFELSE(
+        [AC_LANG_PROGRAM(
+           [[#include <sys/types.h>
+             #include <sys/stat.h>
+             #include <dirent.h>
+           ]],
+           [[DIR *dp = opendir (".");
+             struct dirent *e;
+             struct stat st;
+             if (! dp)
+               return 1;
+             e = readdir (dp);
+             if (! e)
+               { closedir (dp); return 2; }
+             if (lstat (e->d_name, &st) != 0)
+               { closedir (dp); return 3; }
+             if (e->d_ino != st.st_ino)
+               { closedir (dp); return 4; }
+             closedir (dp);
+             return 0;
+           ]])],
+           [gl_cv_struct_dirent_d_ino=yes],
+           [gl_cv_struct_dirent_d_ino=no],
+           [case "$host_os" in
+                            # Guess yes on glibc systems with Linux kernel.
+              linux*-gnu*)  gl_cv_struct_dirent_d_ino="guessing yes" ;;
+                            # Guess yes on musl systems with Linux kernel.
+              linux*-musl*) gl_cv_struct_dirent_d_ino="guessing yes" ;;
+                            # Guess no on native Windows.
+              mingw*)       gl_cv_struct_dirent_d_ino="guessing no" ;;
+                            # If we don't know, obey --enable-cross-guesses.
+              *)            gl_cv_struct_dirent_d_ino="$gl_cross_guess_normal" ;;
+            esac
+           ])])
+   case "$gl_cv_struct_dirent_d_ino" in
+     *yes)
+       AC_DEFINE([D_INO_IN_DIRENT], [1],
+         [Define if struct dirent has a member d_ino that actually works.])
+       ;;
+   esac
+  ]
+)
diff --git a/m4/dirent_h.m4 b/m4/dirent_h.m4
new file mode 100644
index 0000000..8bef6a0
--- /dev/null
+++ b/m4/dirent_h.m4
@@ -0,0 +1,64 @@
+# dirent_h.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,
+dnl with or without modifications, as long as this notice is preserved.
+
+dnl Written by Bruno Haible.
+
+AC_DEFUN([gl_DIRENT_H],
+[
+  dnl Use AC_REQUIRE here, so that the default behavior below is expanded
+  dnl once only, before all statements that occur in other macros.
+  AC_REQUIRE([gl_DIRENT_H_DEFAULTS])
+
+  dnl <dirent.h> is always overridden, because of GNULIB_POSIXCHECK.
+  gl_CHECK_NEXT_HEADERS([dirent.h])
+  if test $ac_cv_header_dirent_h = yes; then
+    HAVE_DIRENT_H=1
+  else
+    HAVE_DIRENT_H=0
+  fi
+  AC_SUBST([HAVE_DIRENT_H])
+
+  dnl Check for declarations of anything we want to poison if the
+  dnl corresponding gnulib module is not in use.
+  gl_WARN_ON_USE_PREPARE([[#include <dirent.h>
+    ]], [alphasort closedir dirfd fdopendir opendir readdir rewinddir scandir])
+])
+
+AC_DEFUN([gl_DIRENT_MODULE_INDICATOR],
+[
+  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
+  AC_REQUIRE([gl_DIRENT_H_DEFAULTS])
+  gl_MODULE_INDICATOR_SET_VARIABLE([$1])
+  dnl Define it also as a C macro, for the benefit of the unit tests.
+  gl_MODULE_INDICATOR_FOR_TESTS([$1])
+])
+
+AC_DEFUN([gl_DIRENT_H_DEFAULTS],
+[
+  AC_REQUIRE([gl_UNISTD_H_DEFAULTS]) dnl for REPLACE_FCHDIR
+  GNULIB_OPENDIR=0;     AC_SUBST([GNULIB_OPENDIR])
+  GNULIB_READDIR=0;     AC_SUBST([GNULIB_READDIR])
+  GNULIB_REWINDDIR=0;   AC_SUBST([GNULIB_REWINDDIR])
+  GNULIB_CLOSEDIR=0;    AC_SUBST([GNULIB_CLOSEDIR])
+  GNULIB_DIRFD=0;       AC_SUBST([GNULIB_DIRFD])
+  GNULIB_FDOPENDIR=0;   AC_SUBST([GNULIB_FDOPENDIR])
+  GNULIB_SCANDIR=0;     AC_SUBST([GNULIB_SCANDIR])
+  GNULIB_ALPHASORT=0;   AC_SUBST([GNULIB_ALPHASORT])
+  dnl Assume proper GNU behavior unless another module says otherwise.
+  HAVE_OPENDIR=1;       AC_SUBST([HAVE_OPENDIR])
+  HAVE_READDIR=1;       AC_SUBST([HAVE_READDIR])
+  HAVE_REWINDDIR=1;     AC_SUBST([HAVE_REWINDDIR])
+  HAVE_CLOSEDIR=1;      AC_SUBST([HAVE_CLOSEDIR])
+  HAVE_DECL_DIRFD=1;    AC_SUBST([HAVE_DECL_DIRFD])
+  HAVE_DECL_FDOPENDIR=1;AC_SUBST([HAVE_DECL_FDOPENDIR])
+  HAVE_FDOPENDIR=1;     AC_SUBST([HAVE_FDOPENDIR])
+  HAVE_SCANDIR=1;       AC_SUBST([HAVE_SCANDIR])
+  HAVE_ALPHASORT=1;     AC_SUBST([HAVE_ALPHASORT])
+  REPLACE_OPENDIR=0;    AC_SUBST([REPLACE_OPENDIR])
+  REPLACE_CLOSEDIR=0;   AC_SUBST([REPLACE_CLOSEDIR])
+  REPLACE_DIRFD=0;      AC_SUBST([REPLACE_DIRFD])
+  REPLACE_FDOPENDIR=0;  AC_SUBST([REPLACE_FDOPENDIR])
+])
diff --git a/m4/dirfd.m4 b/m4/dirfd.m4
new file mode 100644
index 0000000..d92445e
--- /dev/null
+++ b/m4/dirfd.m4
@@ -0,0 +1,86 @@
+# serial 26   -*- Autoconf -*-
+
+dnl Find out how to get the file descriptor associated with an open DIR*.
+
+# Copyright (C) 2001-2006, 2008-2020 Free Software Foundation, Inc.
+# This file is free software; the Free Software Foundation
+# gives unlimited permission to copy and/or distribute it,
+# with or without modifications, as long as this notice is preserved.
+
+dnl From Jim Meyering
+
+AC_DEFUN([gl_FUNC_DIRFD],
+[
+  AC_REQUIRE([gl_DIRENT_H_DEFAULTS])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+
+  dnl Persuade glibc <dirent.h> to declare dirfd().
+  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
+
+  AC_CHECK_FUNCS([dirfd])
+  AC_CHECK_DECLS([dirfd], , ,
+    [[#include <sys/types.h>
+      #include <dirent.h>]])
+  if test $ac_cv_have_decl_dirfd = no; then
+    HAVE_DECL_DIRFD=0
+  fi
+
+  AC_CACHE_CHECK([whether dirfd is a macro],
+    [gl_cv_func_dirfd_macro],
+    [AC_EGREP_CPP([dirent_header_defines_dirfd], [
+#include <sys/types.h>
+#include <dirent.h>
+#ifdef dirfd
+ dirent_header_defines_dirfd
+#endif],
+       [gl_cv_func_dirfd_macro=yes],
+       [gl_cv_func_dirfd_macro=no])])
+
+  # Use the replacement if we have no function or macro with that name,
+  # or if OS/2 kLIBC whose dirfd() does not work.
+  # Replace only if the system declares dirfd already.
+  case $ac_cv_func_dirfd,$gl_cv_func_dirfd_macro,$host_os,$ac_cv_have_decl_dirfd in
+    no,no,*,yes | *,*,os2*,yes)
+      REPLACE_DIRFD=1
+      AC_DEFINE([REPLACE_DIRFD], [1],
+        [Define to 1 if gnulib's dirfd() replacement is used.]);;
+  esac
+])
+
+dnl Prerequisites of lib/dirfd.c.
+AC_DEFUN([gl_PREREQ_DIRFD],
+[
+  AC_CACHE_CHECK([how to get the file descriptor associated with an open DIR*],
+                 [gl_cv_sys_dir_fd_member_name],
+    [
+      dirfd_save_CFLAGS=$CFLAGS
+      for ac_expr in d_fd dd_fd; do
+
+        CFLAGS="$CFLAGS -DDIR_FD_MEMBER_NAME=$ac_expr"
+        AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
+           #include <sys/types.h>
+           #include <dirent.h>]],
+          [[DIR *dir_p = opendir("."); (void) dir_p->DIR_FD_MEMBER_NAME;]])],
+          [dir_fd_found=yes]
+        )
+        CFLAGS=$dirfd_save_CFLAGS
+        test "$dir_fd_found" = yes && break
+      done
+      test "$dir_fd_found" = yes || ac_expr=no_such_member
+
+      gl_cv_sys_dir_fd_member_name=$ac_expr
+    ]
+  )
+  if test $gl_cv_sys_dir_fd_member_name != no_such_member; then
+    AC_DEFINE_UNQUOTED([DIR_FD_MEMBER_NAME],
+      [$gl_cv_sys_dir_fd_member_name],
+      [the name of the file descriptor member of DIR])
+  fi
+  AH_VERBATIM([DIR_TO_FD],
+              [#ifdef DIR_FD_MEMBER_NAME
+# define DIR_TO_FD(Dir_p) ((Dir_p)->DIR_FD_MEMBER_NAME)
+#else
+# define DIR_TO_FD(Dir_p) -1
+#endif
+])
+])
diff --git a/m4/dirname.m4 b/m4/dirname.m4
deleted file mode 100644
index 32141ae..0000000
--- a/m4/dirname.m4
+++ /dev/null
@@ -1,19 +0,0 @@
-#serial 10   -*- autoconf -*-
-dnl Copyright (C) 2002-2006, 2009-2019 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_DIRNAME],
-[
-  AC_REQUIRE([gl_DIRNAME_LGPL])
-])
-
-AC_DEFUN([gl_DIRNAME_LGPL],
-[
-  dnl Prerequisites of lib/dirname.h.
-  AC_REQUIRE([gl_DOUBLE_SLASH_ROOT])
-
-  dnl No prerequisites of lib/basename-lgpl.c, lib/dirname-lgpl.c,
-  dnl lib/stripslash.c.
-])
diff --git a/m4/double-slash-root.m4 b/m4/double-slash-root.m4
index 0c5afb1..c463ac4 100644
--- a/m4/double-slash-root.m4
+++ b/m4/double-slash-root.m4
@@ -1,5 +1,5 @@
 # double-slash-root.m4 serial 4   -*- Autoconf -*-
-dnl Copyright (C) 2006, 2008-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2006, 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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/dup.m4 b/m4/dup.m4
new file mode 100644
index 0000000..892de99
--- /dev/null
+++ b/m4/dup.m4
@@ -0,0 +1,54 @@
+# dup.m4 serial 7
+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,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_FUNC_DUP],
+[
+  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  m4_ifdef([gl_MSVC_INVAL], [
+    AC_REQUIRE([gl_MSVC_INVAL])
+    if test $HAVE_MSVC_INVALID_PARAMETER_HANDLER = 1; then
+      REPLACE_DUP=1
+    fi
+  ])
+  dnl Replace dup() for supporting the gnulib-defined fchdir() function,
+  dnl to keep fchdir's bookkeeping up-to-date.
+  m4_ifdef([gl_FUNC_FCHDIR], [
+    gl_TEST_FCHDIR
+    if test $HAVE_FCHDIR = 0; then
+      REPLACE_DUP=1
+    fi
+  ])
+  AC_CACHE_CHECK([whether dup works], [gl_cv_func_dup_works],
+    [AC_RUN_IFELSE(
+      [AC_LANG_PROGRAM([[#include <unistd.h>
+                         #include <fcntl.h>
+                         #include <errno.h>
+                       ]GL_MDA_DEFINES],
+         [[/* On OS/2 kLIBC, dup does not work on a directory fd.  */
+           int fd = open (".", O_RDONLY);
+           return fd < 0 ? 1 : dup (fd) < 0 ? 2 : 0;
+         ]])
+      ],
+      [gl_cv_func_dup_works=yes],
+      [gl_cv_func_dup_works=no],
+      [case "$host_os" in
+                 # Guess no on native Windows.
+         mingw*) gl_cv_func_dup_works="guessing no" ;;
+         *)      gl_cv_func_dup_works="guessing yes" ;;
+       esac
+      ])
+    ])
+  case "$gl_cv_func_dup_works" in
+    *yes) ;;
+    *)
+      REPLACE_DUP=1
+      ;;
+  esac
+])
+
+# Prerequisites of lib/dup.c.
+AC_DEFUN([gl_PREREQ_DUP], [:])
diff --git a/m4/dup2.m4 b/m4/dup2.m4
index b314247..a82798d 100644
--- a/m4/dup2.m4
+++ b/m4/dup2.m4
@@ -1,5 +1,5 @@
-#serial 25
-dnl Copyright (C) 2002, 2005, 2007, 2009-2019 Free Software Foundation, Inc.
+#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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -8,107 +8,95 @@ AC_DEFUN([gl_FUNC_DUP2],
 [
   AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
   AC_REQUIRE([AC_CANONICAL_HOST])
-  m4_ifdef([gl_FUNC_DUP2_OBSOLETE], [
-    AC_CHECK_FUNCS_ONCE([dup2])
-    if test $ac_cv_func_dup2 = no; then
-      HAVE_DUP2=0
-    fi
-  ], [
-    AC_DEFINE([HAVE_DUP2], [1], [Define to 1 if you have the 'dup2' function.])
-  ])
-  if test $HAVE_DUP2 = 1; then
-    AC_CACHE_CHECK([whether dup2 works], [gl_cv_func_dup2_works],
-      [AC_RUN_IFELSE([
-         AC_LANG_PROGRAM(
-           [[#include <errno.h>
-             #include <fcntl.h>
-             #include <limits.h>
-             #include <sys/resource.h>
-             #include <unistd.h>
-             #ifndef RLIM_SAVED_CUR
-             # define RLIM_SAVED_CUR RLIM_INFINITY
-             #endif
-             #ifndef RLIM_SAVED_MAX
-             # define RLIM_SAVED_MAX RLIM_INFINITY
-             #endif
-           ]],
-           [[int result = 0;
-             int bad_fd = INT_MAX;
-             struct rlimit rlim;
-             if (getrlimit (RLIMIT_NOFILE, &rlim) == 0
-                 && 0 <= rlim.rlim_cur && rlim.rlim_cur <= INT_MAX
-                 && rlim.rlim_cur != RLIM_INFINITY
-                 && rlim.rlim_cur != RLIM_SAVED_MAX
-                 && rlim.rlim_cur != RLIM_SAVED_CUR)
-               bad_fd = rlim.rlim_cur;
-             #ifdef FD_CLOEXEC
-               if (fcntl (1, F_SETFD, FD_CLOEXEC) == -1)
-                 result |= 1;
-             #endif
-             if (dup2 (1, 1) != 1)
-               result |= 2;
-             #ifdef FD_CLOEXEC
-               if (fcntl (1, F_GETFD) != FD_CLOEXEC)
-                 result |= 4;
-             #endif
-             close (0);
-             if (dup2 (0, 0) != -1)
-               result |= 8;
-             /* Many gnulib modules require POSIX conformance of EBADF.  */
-             if (dup2 (2, bad_fd) == -1 && errno != EBADF)
-               result |= 16;
-             /* Flush out some cygwin core dumps.  */
-             if (dup2 (2, -1) != -1 || errno != EBADF)
-               result |= 32;
-             dup2 (2, 255);
-             dup2 (2, 256);
-             /* On OS/2 kLIBC, dup2() does not work on a directory fd.  */
-             {
-               int fd = open (".", O_RDONLY);
-               if (fd == -1)
-                 result |= 64;
-               else if (dup2 (fd, fd + 1) == -1)
-                 result |= 128;
-
-               close (fd);
-             }
-             return result;]])
-        ],
-        [gl_cv_func_dup2_works=yes], [gl_cv_func_dup2_works=no],
-        [case "$host_os" in
-           mingw*) # on this platform, dup2 always returns 0 for success
-             gl_cv_func_dup2_works="guessing no" ;;
-           cygwin*) # on cygwin 1.5.x, dup2(1,1) returns 0
-             gl_cv_func_dup2_works="guessing no" ;;
-           aix* | freebsd*)
-                   # on AIX 7.1 and FreeBSD 6.1, dup2 (1,toobig) gives EMFILE,
-                   # not EBADF.
-             gl_cv_func_dup2_works="guessing no" ;;
-           haiku*) # on Haiku alpha 2, dup2(1, 1) resets FD_CLOEXEC.
-             gl_cv_func_dup2_works="guessing no" ;;
-           *-android*) # implemented using dup3(), which fails if oldfd == newfd
-             gl_cv_func_dup2_works="guessing no" ;;
-           os2*) # on OS/2 kLIBC, dup2() does not work on a directory fd.
-             gl_cv_func_dup2_works="guessing no" ;;
-           *) gl_cv_func_dup2_works="guessing yes" ;;
-         esac])
-      ])
-    case "$gl_cv_func_dup2_works" in
-      *yes) ;;
-      *)
-        REPLACE_DUP2=1
-        AC_CHECK_FUNCS([setdtablesize])
-        ;;
-    esac
-  fi
+  AC_CACHE_CHECK([whether dup2 works], [gl_cv_func_dup2_works],
+    [AC_RUN_IFELSE([
+       AC_LANG_PROGRAM(
+         [[#include <errno.h>
+           #include <fcntl.h>
+           #include <limits.h>
+           #include <sys/resource.h>
+           #include <unistd.h>
+           ]GL_MDA_DEFINES[
+           #ifndef RLIM_SAVED_CUR
+           # define RLIM_SAVED_CUR RLIM_INFINITY
+           #endif
+           #ifndef RLIM_SAVED_MAX
+           # define RLIM_SAVED_MAX RLIM_INFINITY
+           #endif
+         ]],
+         [[int result = 0;
+           int bad_fd = INT_MAX;
+           struct rlimit rlim;
+           if (getrlimit (RLIMIT_NOFILE, &rlim) == 0
+               && 0 <= rlim.rlim_cur && rlim.rlim_cur <= INT_MAX
+               && rlim.rlim_cur != RLIM_INFINITY
+               && rlim.rlim_cur != RLIM_SAVED_MAX
+               && rlim.rlim_cur != RLIM_SAVED_CUR)
+             bad_fd = rlim.rlim_cur;
+           #ifdef FD_CLOEXEC
+             if (fcntl (1, F_SETFD, FD_CLOEXEC) == -1)
+               result |= 1;
+           #endif
+           if (dup2 (1, 1) != 1)
+             result |= 2;
+           #ifdef FD_CLOEXEC
+             if (fcntl (1, F_GETFD) != FD_CLOEXEC)
+               result |= 4;
+           #endif
+           close (0);
+           if (dup2 (0, 0) != -1)
+             result |= 8;
+           /* Many gnulib modules require POSIX conformance of EBADF.  */
+           if (dup2 (2, bad_fd) == -1 && errno != EBADF)
+             result |= 16;
+           /* Flush out some cygwin core dumps.  */
+           if (dup2 (2, -1) != -1 || errno != EBADF)
+             result |= 32;
+           dup2 (2, 255);
+           dup2 (2, 256);
+           /* On OS/2 kLIBC, dup2() does not work on a directory fd.  */
+           {
+             int fd = open (".", O_RDONLY);
+             if (fd == -1)
+               result |= 64;
+             else if (dup2 (fd, fd + 1) == -1)
+               result |= 128;
+             close (fd);
+           }
+           return result;]])
+      ],
+      [gl_cv_func_dup2_works=yes], [gl_cv_func_dup2_works=no],
+      [case "$host_os" in
+         mingw*) # on this platform, dup2 always returns 0 for success
+           gl_cv_func_dup2_works="guessing no" ;;
+         cygwin*) # on cygwin 1.5.x, dup2(1,1) returns 0
+           gl_cv_func_dup2_works="guessing no" ;;
+         aix* | freebsd*)
+                 # on AIX 7.1 and FreeBSD 6.1, dup2 (1,toobig) gives EMFILE,
+                 # not EBADF.
+           gl_cv_func_dup2_works="guessing no" ;;
+         haiku*) # on Haiku alpha 2, dup2(1, 1) resets FD_CLOEXEC.
+           gl_cv_func_dup2_works="guessing no" ;;
+         *-android*) # implemented using dup3(), which fails if oldfd == newfd
+           gl_cv_func_dup2_works="guessing no" ;;
+         os2*) # on OS/2 kLIBC, dup2() does not work on a directory fd.
+           gl_cv_func_dup2_works="guessing no" ;;
+         *) gl_cv_func_dup2_works="guessing yes" ;;
+       esac])
+    ])
+  case "$gl_cv_func_dup2_works" in
+    *yes) ;;
+    *)
+      REPLACE_DUP2=1
+      AC_CHECK_FUNCS([setdtablesize])
+      ;;
+  esac
   dnl Replace dup2() for supporting the gnulib-defined fchdir() function,
   dnl to keep fchdir's bookkeeping up-to-date.
   m4_ifdef([gl_FUNC_FCHDIR], [
     gl_TEST_FCHDIR
     if test $HAVE_FCHDIR = 0; then
-      if test $HAVE_DUP2 = 1; then
-        REPLACE_DUP2=1
-      fi
+      REPLACE_DUP2=1
     fi
   ])
 ])
diff --git a/m4/eaccess.m4 b/m4/eaccess.m4
new file mode 100644
index 0000000..7eea8e9
--- /dev/null
+++ b/m4/eaccess.m4
@@ -0,0 +1,12 @@
+# eaccess.m4 serial 2
+dnl Copyright (C) 2003, 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.
+
+AC_DEFUN([gl_FUNC_EACCESS],
+[
+  AC_CHECK_FUNC([eaccess], ,
+    [AC_DEFINE([eaccess], [access],
+       [Define as 'access' if you don't have the eaccess() function.])])
+])
diff --git a/m4/eealloc.m4 b/m4/eealloc.m4
index 2a4b120..236f373 100644
--- a/m4/eealloc.m4
+++ b/m4/eealloc.m4
@@ -1,5 +1,5 @@
 # eealloc.m4 serial 3
-dnl Copyright (C) 2003, 2009-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2003, 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.
diff --git a/m4/environ.m4 b/m4/environ.m4
index c1a6fa3..bab85f1 100644
--- a/m4/environ.m4
+++ b/m4/environ.m4
@@ -1,5 +1,5 @@
 # environ.m4 serial 7
-dnl Copyright (C) 2001-2004, 2006-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2001-2004, 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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/errno_h.m4 b/m4/errno_h.m4
index 2388854..dd4994f 100644
--- a/m4/errno_h.m4
+++ b/m4/errno_h.m4
@@ -1,5 +1,5 @@
 # errno_h.m4 serial 13
-dnl Copyright (C) 2004, 2006, 2008-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2004, 2006, 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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/error.m4 b/m4/error.m4
index 393adb5..60c229d 100644
--- a/m4/error.m4
+++ b/m4/error.m4
@@ -1,6 +1,6 @@
 #serial 14
 
-# Copyright (C) 1996-1998, 2001-2004, 2009-2019 Free Software Foundation, Inc.
+# Copyright (C) 1996-1998, 2001-2004, 2009-2020 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
diff --git a/m4/exponentd.m4 b/m4/exponentd.m4
index 90870df..cca8797 100644
--- a/m4/exponentd.m4
+++ b/m4/exponentd.m4
@@ -1,5 +1,5 @@
 # exponentd.m4 serial 3
-dnl Copyright (C) 2007-2008, 2010-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2007-2008, 2010-2020 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.
diff --git a/m4/extensions.m4 b/m4/extensions.m4
index fd1ce81..44be1d1 100644
--- a/m4/extensions.m4
+++ b/m4/extensions.m4
@@ -1,14 +1,19 @@
-# serial 18  -*- Autoconf -*-
+# serial 21  -*- Autoconf -*-
 # Enable extensions on systems that normally disable them.
 
-# Copyright (C) 2003, 2006-2019 Free Software Foundation, Inc.
+# Copyright (C) 2003, 2006-2020 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.
 
+dnl Define to empty for the benefit of Autoconf 2.69 and earlier, so that
+dnl AC_USE_SYSTEM_EXTENSIONS (below) can be used unchanged from Autoconf 2.70+.
+m4_ifndef([AC_CHECK_INCLUDES_DEFAULT],
+  [AC_DEFUN([AC_CHECK_INCLUDES_DEFAULT], [])])
+
 # This definition of AC_USE_SYSTEM_EXTENSIONS is stolen from git
 # Autoconf.  Perhaps we can remove this once we can assume Autoconf
-# 2.70 or later everywhere, but since Autoconf mutates rapidly
+# is recent-enough everywhere, but since Autoconf mutates rapidly
 # enough in this area it's likely we'll need to redefine
 # AC_USE_SYSTEM_EXTENSIONS for quite some time.
 
@@ -26,36 +31,27 @@
 #      its dependencies. This will ensure that the gl_USE_SYSTEM_EXTENSIONS
 #      invocation occurs in gl_EARLY, not in gl_INIT.
 
+m4_version_prereq([2.70.1], [], [
+
 # AC_USE_SYSTEM_EXTENSIONS
 # ------------------------
 # Enable extensions on systems that normally disable them,
 # typically due to standards-conformance issues.
-#
-# Remember that #undef in AH_VERBATIM gets replaced with #define by
-# AC_DEFINE.  The goal here is to define all known feature-enabling
-# macros, then, if reports of conflicts are made, disable macros that
-# cause problems on some platforms (such as __EXTENSIONS__).
+# We unconditionally define as many of the known feature-enabling
+# as possible, reserving conditional behavior for macros that are
+# known to cause problems on some platforms (such as __EXTENSIONS__).
 AC_DEFUN_ONCE([AC_USE_SYSTEM_EXTENSIONS],
-[AC_BEFORE([$0], [AC_COMPILE_IFELSE])dnl
+[AC_BEFORE([$0], [AC_PREPROC_IFELSE])dnl
+AC_BEFORE([$0], [AC_COMPILE_IFELSE])dnl
+AC_BEFORE([$0], [AC_LINK_IFELSE])dnl
 AC_BEFORE([$0], [AC_RUN_IFELSE])dnl
-
-  AC_CHECK_HEADER([minix/config.h], [MINIX=yes], [MINIX=])
-  if test "$MINIX" = yes; then
-    AC_DEFINE([_POSIX_SOURCE], [1],
-      [Define to 1 if you need to in order for 'stat' and other
-       things to work.])
-    AC_DEFINE([_POSIX_1_SOURCE], [2],
-      [Define to 2 if the system does not provide POSIX.1 features
-       except with this defined.])
-    AC_DEFINE([_MINIX], [1],
-      [Define to 1 if on MINIX.])
-    AC_DEFINE([_NETBSD_SOURCE], [1],
-      [Define to 1 to make NetBSD features available.  MINIX 3 needs this.])
-  fi
-
+AC_BEFORE([$0], [AC_CHECK_INCLUDES_DEFAULT])dnl
+dnl #undef in AH_VERBATIM gets replaced with #define by AC_DEFINE.
 dnl Use a different key than __EXTENSIONS__, as that name broke existing
 dnl configure.ac when using autoheader 2.62.
-  AH_VERBATIM([USE_SYSTEM_EXTENSIONS],
+dnl The macros below are in alphabetical order ignoring leading _ or __
+dnl prefixes.
+AH_VERBATIM([USE_SYSTEM_EXTENSIONS],
 [/* Enable extensions on AIX 3, Interix.  */
 #ifndef _ALL_SOURCE
 # undef _ALL_SOURCE
@@ -64,19 +60,44 @@ dnl configure.ac when using autoheader 2.62.
 #ifndef _DARWIN_C_SOURCE
 # undef _DARWIN_C_SOURCE
 #endif
+/* Enable general extensions on Solaris.  */
+#ifndef __EXTENSIONS__
+# undef __EXTENSIONS__
+#endif
 /* Enable GNU extensions on systems that have them.  */
 #ifndef _GNU_SOURCE
 # undef _GNU_SOURCE
 #endif
-/* Enable NetBSD extensions on NetBSD.  */
+/* Enable X/Open compliant socket functions that do not require linking
+   with -lxnet on HP-UX 11.11.  */
+#ifndef _HPUX_ALT_XOPEN_SOCKET_API
+# undef _HPUX_ALT_XOPEN_SOCKET_API
+#endif
+/* Identify the host operating system as Minix.
+   This macro does not affect the system headers' behavior.
+   A future release of Autoconf may stop defining this macro.  */
+#ifndef _MINIX
+# undef _MINIX
+#endif
+/* Enable general extensions on NetBSD.
+   Enable NetBSD compatibility extensions on Minix.  */
 #ifndef _NETBSD_SOURCE
 # undef _NETBSD_SOURCE
 #endif
-/* Enable OpenBSD extensions on NetBSD.  */
+/* Enable OpenBSD compatibility extensions on NetBSD.
+   Oddly enough, this does nothing on OpenBSD.  */
 #ifndef _OPENBSD_SOURCE
 # undef _OPENBSD_SOURCE
 #endif
-/* Enable threading extensions on Solaris.  */
+/* Define to 1 if needed for POSIX-compatible behavior.  */
+#ifndef _POSIX_SOURCE
+# undef _POSIX_SOURCE
+#endif
+/* Define to 2 if needed for POSIX-compatible behavior.  */
+#ifndef _POSIX_1_SOURCE
+# undef _POSIX_1_SOURCE
+#endif
+/* Enable POSIX-compatible threading on Solaris.  */
 #ifndef _POSIX_PTHREAD_SEMANTICS
 # undef _POSIX_PTHREAD_SEMANTICS
 #endif
@@ -112,22 +133,19 @@ dnl configure.ac when using autoheader 2.62.
 #ifndef _TANDEM_SOURCE
 # undef _TANDEM_SOURCE
 #endif
-/* Enable X/Open extensions if necessary.  HP-UX 11.11 defines
-   mbstate_t only if _XOPEN_SOURCE is defined to 500, regardless of
-   whether compiling with -Ae or -D_HPUX_SOURCE=1.  */
+/* Enable X/Open extensions.  Define to 500 only if necessary
+   to make mbstate_t available.  */
 #ifndef _XOPEN_SOURCE
 # undef _XOPEN_SOURCE
 #endif
-/* Enable X/Open compliant socket functions that do not require linking
-   with -lxnet on HP-UX 11.11.  */
-#ifndef _HPUX_ALT_XOPEN_SOCKET_API
-# undef _HPUX_ALT_XOPEN_SOCKET_API
-#endif
-/* Enable general extensions on Solaris.  */
-#ifndef __EXTENSIONS__
-# undef __EXTENSIONS__
-#endif
-])
+])dnl
+
+  AC_REQUIRE([AC_CHECK_INCLUDES_DEFAULT])dnl
+  _AC_CHECK_HEADER_ONCE([wchar.h])
+  _AC_CHECK_HEADER_ONCE([minix/config.h])
+
+dnl Defining __EXTENSIONS__ may break the system headers on some systems.
+dnl (FIXME: Which ones?)
   AC_CACHE_CHECK([whether it is safe to define __EXTENSIONS__],
     [ac_cv_safe_to_define___extensions__],
     [AC_COMPILE_IFELSE(
@@ -136,11 +154,33 @@ dnl configure.ac when using autoheader 2.62.
           ]AC_INCLUDES_DEFAULT])],
        [ac_cv_safe_to_define___extensions__=yes],
        [ac_cv_safe_to_define___extensions__=no])])
-  test $ac_cv_safe_to_define___extensions__ = yes &&
-    AC_DEFINE([__EXTENSIONS__])
+
+dnl HP-UX 11.11 defines mbstate_t only if _XOPEN_SOURCE is defined to
+dnl 500, regardless of whether compiling with -Ae or -D_HPUX_SOURCE=1.
+dnl But defining _XOPEN_SOURCE may turn *off* extensions on platforms
+dnl not covered by turn-on-extensions macros (notably Dragonfly, Free,
+dnl and OpenBSD, which don't have any equivalent of _NETBSD_SOURCE) so
+dnl it should only be defined when necessary.
+  AC_CACHE_CHECK([whether _XOPEN_SOURCE should be defined],
+    [ac_cv_should_define__xopen_source],
+    [ac_cv_should_define__xopen_source=no
+    AS_IF([test $ac_cv_header_wchar_h = yes],
+      [AC_COMPILE_IFELSE(
+        [AC_LANG_PROGRAM([[
+          #include <wchar.h>
+          mbstate_t x;]])],
+        [],
+        [AC_COMPILE_IFELSE(
+          [AC_LANG_PROGRAM([[
+            #define _XOPEN_SOURCE 500
+            #include <wchar.h>
+            mbstate_t x;]])],
+          [ac_cv_should_define__xopen_source=yes])])])])
+
   AC_DEFINE([_ALL_SOURCE])
   AC_DEFINE([_DARWIN_C_SOURCE])
   AC_DEFINE([_GNU_SOURCE])
+  AC_DEFINE([_HPUX_ALT_XOPEN_SOCKET_API])
   AC_DEFINE([_NETBSD_SOURCE])
   AC_DEFINE([_OPENBSD_SOURCE])
   AC_DEFINE([_POSIX_PTHREAD_SEMANTICS])
@@ -152,24 +192,18 @@ dnl configure.ac when using autoheader 2.62.
   AC_DEFINE([__STDC_WANT_LIB_EXT2__])
   AC_DEFINE([__STDC_WANT_MATH_SPEC_FUNCS__])
   AC_DEFINE([_TANDEM_SOURCE])
-  AC_CACHE_CHECK([whether _XOPEN_SOURCE should be defined],
-    [ac_cv_should_define__xopen_source],
-    [ac_cv_should_define__xopen_source=no
-     AC_COMPILE_IFELSE(
-       [AC_LANG_PROGRAM([[
-          #include <wchar.h>
-          mbstate_t x;]])],
-       [],
-       [AC_COMPILE_IFELSE(
-          [AC_LANG_PROGRAM([[
-             #define _XOPEN_SOURCE 500
-             #include <wchar.h>
-             mbstate_t x;]])],
-          [ac_cv_should_define__xopen_source=yes])])])
-  test $ac_cv_should_define__xopen_source = yes &&
-    AC_DEFINE([_XOPEN_SOURCE], [500])
-  AC_DEFINE([_HPUX_ALT_XOPEN_SOCKET_API])
+  AS_IF([test $ac_cv_header_minix_config_h = yes],
+    [MINIX=yes
+    AC_DEFINE([_MINIX])
+    AC_DEFINE([_POSIX_SOURCE])
+    AC_DEFINE([_POSIX_1_SOURCE], [2])],
+    [MINIX=])
+  AS_IF([test $ac_cv_safe_to_define___extensions__ = yes],
+    [AC_DEFINE([__EXTENSIONS__])])
+  AS_IF([test $ac_cv_should_define__xopen_source = yes],
+    [AC_DEFINE([_XOPEN_SOURCE], [500])])
 ])# AC_USE_SYSTEM_EXTENSIONS
+])
 
 # gl_USE_SYSTEM_EXTENSIONS
 # ------------------------
@@ -177,13 +211,5 @@ dnl configure.ac when using autoheader 2.62.
 # typically due to standards-conformance issues.
 AC_DEFUN_ONCE([gl_USE_SYSTEM_EXTENSIONS],
 [
-  dnl Require this macro before AC_USE_SYSTEM_EXTENSIONS.
-  dnl gnulib does not need it. But if it gets required by third-party macros
-  dnl after AC_USE_SYSTEM_EXTENSIONS is required, autoconf 2.62..2.63 emit a
-  dnl warning: "AC_COMPILE_IFELSE was called before AC_USE_SYSTEM_EXTENSIONS".
-  dnl Note: We can do this only for one of the macros AC_AIX, AC_GNU_SOURCE,
-  dnl AC_MINIX. If people still use AC_AIX or AC_MINIX, they are out of luck.
-  AC_REQUIRE([AC_GNU_SOURCE])
-
   AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
 ])
diff --git a/m4/extern-inline.m4 b/m4/extern-inline.m4
index ec9f221..7f1bb39 100644
--- a/m4/extern-inline.m4
+++ b/m4/extern-inline.m4
@@ -1,6 +1,6 @@
 dnl 'extern inline' a la ISO C99.
 
-dnl Copyright 2012-2019 Free Software Foundation, Inc.
+dnl Copyright 2012-2014 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.
@@ -11,7 +11,7 @@ AC_DEFUN([gl_EXTERN_INLINE],
 [/* Please see the Gnulib manual for how to use these macros.
 
    Suppress extern inline with HP-UX cc, as it appears to be broken; see
-   <https://lists.gnu.org/r/bug-texinfo/2013-02/msg00030.html>.
+   <http://lists.gnu.org/archive/html/bug-texinfo/2013-02/msg00030.html>.
 
    Suppress extern inline with Sun C in standards-conformance mode, as it
    mishandles inline functions that call each other.  E.g., for 'inline void f
@@ -25,32 +25,20 @@ AC_DEFUN([gl_EXTERN_INLINE],
    if isdigit is mistakenly implemented via a static inline function,
    a program containing an extern inline function that calls isdigit
    may not work since the C standard prohibits extern inline functions
-   from calling static functions (ISO C 99 section 6.7.4.(3).
-   This bug is known to occur on:
+   from calling static functions.  This bug is known to occur on:
 
      OS X 10.8 and earlier; see:
-     https://lists.gnu.org/r/bug-gnulib/2012-12/msg00023.html
+     http://lists.gnu.org/archive/html/bug-gnulib/2012-12/msg00023.html
 
      DragonFly; see
      http://muscles.dragonflybsd.org/bulk/bleeding-edge-potential/latest-per-pkg/ah-tty-0.3.12.log
 
      FreeBSD; see:
-     https://lists.gnu.org/r/bug-gnulib/2014-07/msg00104.html
+     http://lists.gnu.org/archive/html/bug-gnulib/2014-07/msg00104.html
 
    OS X 10.9 has a macro __header_inline indicating the bug is fixed for C and
-   for clang but remains for g++; see <https://trac.macports.org/ticket/41033>.
-   Assume DragonFly and FreeBSD will be similar.
-
-   GCC 4.3 and above with -std=c99 or -std=gnu99 implements ISO C99
-   inline semantics, unless -fgnu89-inline is used.  It defines a macro
-   __GNUC_STDC_INLINE__ to indicate this situation or a macro
-   __GNUC_GNU_INLINE__ to indicate the opposite situation.
-   GCC 4.2 with -std=c99 or -std=gnu99 implements the GNU C inline
-   semantics but warns, unless -fgnu89-inline is used:
-     warning: C99 inline functions are not supported; using GNU89
-     warning: to disable this warning use -fgnu89-inline or the gnu_inline function attribute
-   It defines a macro __GNUC_GNU_INLINE__ to indicate this situation.
- */
+   for clang but remains for g++; see <http://trac.macports.org/ticket/41033>.
+   Assume DragonFly and FreeBSD will be similar.  */
 #if (((defined __APPLE__ && defined __MACH__) \
       || defined __DragonFly__ || defined __FreeBSD__) \
      && (defined __header_inline \
@@ -66,7 +54,6 @@ AC_DEFUN([gl_EXTERN_INLINE],
       ? defined __GNUC_STDC_INLINE__ && __GNUC_STDC_INLINE__ \
       : (199901L <= __STDC_VERSION__ \
          && !defined __HP_cc \
-         && !defined __PGI \
          && !(defined __SUNPRO_C && __STDC__))) \
      && !defined _GL_EXTERN_INLINE_STDHEADER_BUG)
 # define _GL_INLINE inline
@@ -87,19 +74,17 @@ AC_DEFUN([gl_EXTERN_INLINE],
 # define _GL_EXTERN_INLINE static _GL_UNUSED
 #endif
 
-/* In GCC 4.6 (inclusive) to 5.1 (exclusive),
-   suppress bogus "no previous prototype for 'FOO'"
-   and "no previous declaration for 'FOO'" diagnostics,
-   when FOO is an inline function in the header; see
-   <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=54113> and
-   <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63877>.  */
-#if __GNUC__ == 4 && 6 <= __GNUC_MINOR__
+#if 4 < __GNUC__ + (6 <= __GNUC_MINOR__)
 # if defined __GNUC_STDC_INLINE__ && __GNUC_STDC_INLINE__
 #  define _GL_INLINE_HEADER_CONST_PRAGMA
 # else
 #  define _GL_INLINE_HEADER_CONST_PRAGMA \
      _Pragma ("GCC diagnostic ignored \"-Wsuggest-attribute=const\"")
 # endif
+  /* Suppress GCC's bogus "no previous prototype for 'FOO'"
+     and "no previous declaration for 'FOO'"  diagnostics,
+     when FOO is an inline function in the header; see
+     <http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54113>.  */
 # define _GL_INLINE_HEADER_BEGIN \
     _Pragma ("GCC diagnostic push") \
     _Pragma ("GCC diagnostic ignored \"-Wmissing-prototypes\"") \
diff --git a/m4/fatal-signal.m4 b/m4/fatal-signal.m4
index 349c1f7..838b291 100644
--- a/m4/fatal-signal.m4
+++ b/m4/fatal-signal.m4
@@ -1,5 +1,5 @@
 # fatal-signal.m4 serial 9
-dnl Copyright (C) 2003-2004, 2006, 2008-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2003-2004, 2006, 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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/fchdir.m4 b/m4/fchdir.m4
new file mode 100644
index 0000000..8e894e0
--- /dev/null
+++ b/m4/fchdir.m4
@@ -0,0 +1,68 @@
+# fchdir.m4 serial 26
+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,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_FUNC_FCHDIR],
+[
+  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
+  AC_REQUIRE([gl_DIRENT_H_DEFAULTS])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+
+  AC_CHECK_DECLS_ONCE([fchdir])
+  if test $ac_cv_have_decl_fchdir = no; then
+    HAVE_DECL_FCHDIR=0
+  fi
+
+  AC_REQUIRE([gl_TEST_FCHDIR])
+  if test $HAVE_FCHDIR = 0; then
+    AC_LIBOBJ([fchdir])
+    gl_PREREQ_FCHDIR
+    AC_DEFINE([REPLACE_FCHDIR], [1],
+      [Define to 1 if gnulib's fchdir() replacement is used.])
+    dnl We must also replace anything that can manipulate a directory fd,
+    dnl to keep our bookkeeping up-to-date.  We don't have to replace
+    dnl fstatat, since no platform has fstatat but lacks fchdir.
+    AC_CACHE_CHECK([whether open can visit directories],
+      [gl_cv_func_open_directory_works],
+      [AC_RUN_IFELSE(
+         [AC_LANG_PROGRAM(
+            [[#include <fcntl.h>
+            ]GL_MDA_DEFINES],
+            [[return open(".", O_RDONLY) < 0;]])],
+         [gl_cv_func_open_directory_works=yes],
+         [gl_cv_func_open_directory_works=no],
+         [case "$host_os" in
+                             # Guess yes on Linux systems.
+            linux-* | linux) gl_cv_func_open_directory_works="guessing yes" ;;
+                             # Guess yes on glibc systems.
+            *-gnu* | gnu*)   gl_cv_func_open_directory_works="guessing yes" ;;
+                             # Guess no on native Windows.
+            mingw*)          gl_cv_func_open_directory_works="guessing no" ;;
+                             # If we don't know, obey --enable-cross-guesses.
+            *)               gl_cv_func_open_directory_works="$gl_cross_guess_normal" ;;
+          esac
+         ])])
+    case "$gl_cv_func_open_directory_works" in
+      *yes) ;;
+      *)
+        AC_DEFINE([REPLACE_OPEN_DIRECTORY], [1], [Define to 1 if open() should
+work around the inability to open a directory.])
+        ;;
+    esac
+  fi
+])
+
+# Determine whether to use the overrides in lib/fchdir.c.
+AC_DEFUN([gl_TEST_FCHDIR],
+[
+  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
+  AC_CHECK_FUNCS_ONCE([fchdir])
+  if test $ac_cv_func_fchdir = no; then
+    HAVE_FCHDIR=0
+  fi
+])
+
+# Prerequisites of lib/fchdir.c.
+AC_DEFUN([gl_PREREQ_FCHDIR], [:])
diff --git a/m4/fcntl-o.m4 b/m4/fcntl-o.m4
index 6ab3387..3ef061d 100644
--- a/m4/fcntl-o.m4
+++ b/m4/fcntl-o.m4
@@ -1,5 +1,5 @@
-# fcntl-o.m4 serial 6
-dnl Copyright (C) 2006, 2009-2019 Free Software Foundation, Inc.
+# fcntl-o.m4 serial 7
+dnl Copyright (C) 2006, 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.
@@ -32,6 +32,7 @@ AC_DEFUN([gl_FCNTL_O_FLAGS],
            # defined sleep(n) _sleep ((n) * 1000)
            #endif
            #include <fcntl.h>
+           ]GL_MDA_DEFINES[
            #ifndef O_NOATIME
             #define O_NOATIME 0
            #endif
diff --git a/m4/fcntl.m4 b/m4/fcntl.m4
index e409e96..547ff40 100644
--- a/m4/fcntl.m4
+++ b/m4/fcntl.m4
@@ -1,5 +1,5 @@
-# fcntl.m4 serial 9
-dnl Copyright (C) 2009-2019 Free Software Foundation, Inc.
+# fcntl.m4 serial 11
+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.
@@ -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
@@ -80,15 +81,29 @@ AC_DEFUN([gl_FUNC_FCNTL],
           behavior does not match POSIX]) ;;
     esac
 
-    dnl Many systems lack F_DUPFD_CLOEXEC
+    dnl Many systems lack F_DUPFD_CLOEXEC.
+    dnl NetBSD 9.0 declares F_DUPFD_CLOEXEC but it works only like F_DUPFD.
     AC_CACHE_CHECK([whether fcntl understands F_DUPFD_CLOEXEC],
       [gl_cv_func_fcntl_f_dupfd_cloexec],
-      [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
-#include <fcntl.h>
-#ifndef F_DUPFD_CLOEXEC
-choke me
-#endif
-         ]])],
+      [AC_RUN_IFELSE(
+         [AC_LANG_SOURCE(
+            [[#include <fcntl.h>
+              #include <unistd.h>
+              int main (int argc, char *argv[])
+              {
+                if (argc == 1)
+                  /* parent process */
+                  {
+                    if (fcntl (1, F_DUPFD_CLOEXEC, 10) < 0)
+                      return 1;
+                    return execl ("./conftest", "./conftest", "child", NULL);
+                  }
+                else
+                  /* child process */
+                  return (fcntl (10, F_GETFL) < 0 ? 0 : 42);
+              }
+            ]])
+         ],
          [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
 #ifdef __linux__
 /* The Linux kernel only added F_DUPFD_CLOEXEC in 2.6.24, so we always replace
@@ -97,12 +112,22 @@ choke me
 #endif
            ]])],
            [gl_cv_func_fcntl_f_dupfd_cloexec=yes],
-           [gl_cv_func_fcntl_f_dupfd_cloexec="needs runtime check"])],
-         [gl_cv_func_fcntl_f_dupfd_cloexec=no])])
-    if test "$gl_cv_func_fcntl_f_dupfd_cloexec" != yes; then
-      gl_REPLACE_FCNTL
-      dnl No witness macro needed for this bug.
-    fi
+           [gl_cv_func_fcntl_f_dupfd_cloexec="needs runtime check"])
+         ],
+         [gl_cv_func_fcntl_f_dupfd_cloexec=no],
+         [case "$host_os" in
+                     # Guess no on NetBSD.
+            netbsd*) gl_cv_func_fcntl_f_dupfd_cloexec="guessing no" ;;
+            *)       gl_cv_func_fcntl_f_dupfd_cloexec="$gl_cross_guess_normal" ;;
+          esac
+         ])
+      ])
+    case "$gl_cv_func_fcntl_f_dupfd_cloexec" in
+      *yes) ;;
+      *)    gl_REPLACE_FCNTL
+            dnl No witness macro needed for this bug.
+            ;;
+    esac
   fi
   dnl Replace fcntl() for supporting the gnulib-defined fchdir() function,
   dnl to keep fchdir's bookkeeping up-to-date.
diff --git a/m4/fcntl_h.m4 b/m4/fcntl_h.m4
index a86fdae..c475357 100644
--- a/m4/fcntl_h.m4
+++ b/m4/fcntl_h.m4
@@ -1,6 +1,6 @@
-# serial 15
+# serial 17
 # Configure fcntl.h.
-dnl Copyright (C) 2006-2007, 2009-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2006-2007, 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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -37,13 +37,18 @@ AC_DEFUN([gl_FCNTL_MODULE_INDICATOR],
 
 AC_DEFUN([gl_FCNTL_H_DEFAULTS],
 [
+  GNULIB_CREAT=0;        AC_SUBST([GNULIB_CREAT])
   GNULIB_FCNTL=0;        AC_SUBST([GNULIB_FCNTL])
   GNULIB_NONBLOCKING=0;  AC_SUBST([GNULIB_NONBLOCKING])
   GNULIB_OPEN=0;         AC_SUBST([GNULIB_OPEN])
   GNULIB_OPENAT=0;       AC_SUBST([GNULIB_OPENAT])
+  dnl Support Microsoft deprecated alias function names by default.
+  GNULIB_MDA_CREAT=1;    AC_SUBST([GNULIB_MDA_CREAT])
+  GNULIB_MDA_OPEN=1;     AC_SUBST([GNULIB_MDA_OPEN])
   dnl Assume proper GNU behavior unless another module says otherwise.
   HAVE_FCNTL=1;          AC_SUBST([HAVE_FCNTL])
   HAVE_OPENAT=1;         AC_SUBST([HAVE_OPENAT])
+  REPLACE_CREAT=0;       AC_SUBST([REPLACE_CREAT])
   REPLACE_FCNTL=0;       AC_SUBST([REPLACE_FCNTL])
   REPLACE_OPEN=0;        AC_SUBST([REPLACE_OPEN])
   REPLACE_OPENAT=0;      AC_SUBST([REPLACE_OPENAT])
diff --git a/m4/fdopendir.m4 b/m4/fdopendir.m4
new file mode 100644
index 0000000..9937a74
--- /dev/null
+++ b/m4/fdopendir.m4
@@ -0,0 +1,67 @@
+# serial 14
+# See if we need to provide fdopendir.
+
+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.
+
+# Written by Eric Blake.
+
+AC_DEFUN([gl_FUNC_FDOPENDIR],
+[
+  AC_REQUIRE([gl_DIRENT_H_DEFAULTS])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+
+  dnl FreeBSD 7.3 has the function, but failed to declare it.
+  AC_CHECK_DECLS([fdopendir], [], [HAVE_DECL_FDOPENDIR=0], [[
+#include <dirent.h>
+    ]])
+  AC_CHECK_FUNCS_ONCE([fdopendir])
+  if test $ac_cv_func_fdopendir = no; then
+    HAVE_FDOPENDIR=0
+  else
+    AC_CACHE_CHECK([whether fdopendir works],
+      [gl_cv_func_fdopendir_works],
+      [AC_RUN_IFELSE(
+         [AC_LANG_PROGRAM([[
+#include <dirent.h>
+#include <fcntl.h>
+#include <unistd.h>
+]GL_MDA_DEFINES[
+#if !HAVE_DECL_FDOPENDIR
+extern
+# ifdef __cplusplus
+"C"
+# endif
+DIR *fdopendir (int);
+#endif
+]],
+            [[int result = 0;
+              int fd = open ("conftest.c", O_RDONLY);
+              if (fd < 0) result |= 1;
+              if (fdopendir (fd)) result |= 2;
+              if (close (fd)) result |= 4;
+              return result;
+            ]])],
+         [gl_cv_func_fdopendir_works=yes],
+         [gl_cv_func_fdopendir_works=no],
+         [case "$host_os" in
+                     # Guess yes on glibc systems.
+            *-gnu*)  gl_cv_func_fdopendir_works="guessing yes" ;;
+                     # Guess yes on musl systems.
+            *-musl*) gl_cv_func_fdopendir_works="guessing yes" ;;
+                     # If we don't know, obey --enable-cross-guesses.
+            *)       gl_cv_func_fdopendir_works="$gl_cross_guess_normal" ;;
+          esac
+         ])])
+    case "$gl_cv_func_fdopendir_works" in
+      *yes) ;;
+      *)
+        REPLACE_FDOPENDIR=1
+        ;;
+    esac
+  fi
+])
diff --git a/m4/fflush.m4 b/m4/fflush.m4
index 2df3b4e..8f63c25 100644
--- a/m4/fflush.m4
+++ b/m4/fflush.m4
@@ -1,6 +1,6 @@
-# fflush.m4 serial 17
+# fflush.m4 serial 18
 
-# Copyright (C) 2007-2019 Free Software Foundation, Inc.
+# Copyright (C) 2007-2020 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.
@@ -38,7 +38,8 @@ AC_DEFUN([gl_FUNC_FFLUSH_STDIN],
 #else /* on Windows with MSVC */
 # include <io.h>
 #endif
-       ]], [[FILE *f = fopen ("conftest.txt", "r");
+       ]GL_MDA_DEFINES],
+       [[FILE *f = fopen ("conftest.txt", "r");
          char buffer[10];
          int fd;
          int c;
@@ -57,7 +58,7 @@ AC_DEFUN([gl_FUNC_FFLUSH_STDIN],
          if (lseek (fd, 0, SEEK_CUR) != 5)
            { fclose (f); return 5; }
          /* Verify behaviour of fflush after ungetc. See
-            <http://www.opengroup.org/austin/aardvark/latest/xshbug3.txt>  */
+            <https://www.opengroup.org/austin/aardvark/latest/xshbug3.txt>  */
          /* Verify behaviour of fflush after a backup ungetc.  This fails on
             mingw.  */
          c = fgetc (f);
diff --git a/m4/filenamecat.m4 b/m4/filenamecat.m4
new file mode 100644
index 0000000..7eff5b9
--- /dev/null
+++ b/m4/filenamecat.m4
@@ -0,0 +1,16 @@
+# filenamecat.m4 serial 11
+dnl Copyright (C) 2002-2006, 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.
+
+AC_DEFUN([gl_FILE_NAME_CONCAT],
+[
+  AC_REQUIRE([gl_FILE_NAME_CONCAT_LGPL])
+])
+
+AC_DEFUN([gl_FILE_NAME_CONCAT_LGPL],
+[
+  dnl Prerequisites of lib/filenamecat-lgpl.c.
+  AC_CHECK_FUNCS_ONCE([mempcpy])
+])
diff --git a/m4/findprog-in.m4 b/m4/findprog-in.m4
new file mode 100644
index 0000000..54ea10e
--- /dev/null
+++ b/m4/findprog-in.m4
@@ -0,0 +1,11 @@
+# findprog-in.m4 serial 1
+dnl Copyright (C) 2003, 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.
+
+AC_DEFUN([gl_FINDPROG_IN],
+[
+  dnl Prerequisites of lib/findprog-in.c.
+  AC_REQUIRE([gl_FUNC_EACCESS])
+])
diff --git a/m4/flexmember.m4 b/m4/flexmember.m4
index 1347068..90f3ddd 100644
--- a/m4/flexmember.m4
+++ b/m4/flexmember.m4
@@ -1,7 +1,7 @@
 # serial 5
 # Check for flexible array member support.
 
-# Copyright (C) 2006, 2009-2019 Free Software Foundation, Inc.
+# Copyright (C) 2006, 2009-2020 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.
@@ -34,12 +34,10 @@ AC_DEFUN([AC_C_FLEXIBLE_ARRAY_MEMBER],
     AC_DEFINE([FLEXIBLE_ARRAY_MEMBER], [],
       [Define to nothing if C supports flexible array members, and to
        1 if it does not.  That way, with a declaration like 'struct s
-       { int n; double d@<:@FLEXIBLE_ARRAY_MEMBER@:>@; };', the struct hack
+       { int n; short d@<:@FLEXIBLE_ARRAY_MEMBER@:>@; };', the struct hack
        can be used with pre-C99 compilers.
-       When computing the size of such an object, don't use 'sizeof (struct s)'
-       as it overestimates the size.  Use 'offsetof (struct s, d)' instead.
-       Don't use 'offsetof (struct s, d@<:@0@:>@)', as this doesn't work with
-       MSVC and with C++ compilers.])
+       Use 'FLEXSIZEOF (struct s, d, N * sizeof (short))' to calculate
+       the size in bytes of such a struct containing an N-element array.])
   else
     AC_DEFINE([FLEXIBLE_ARRAY_MEMBER], [1])
   fi
diff --git a/m4/float_h.m4 b/m4/float_h.m4
index 1cd28a0..3ef0bb7 100644
--- a/m4/float_h.m4
+++ b/m4/float_h.m4
@@ -1,5 +1,5 @@
 # float_h.m4 serial 12
-dnl Copyright (C) 2007, 2009-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/flock.m4 b/m4/flock.m4
index 7197afa..bb48733 100644
--- a/m4/flock.m4
+++ b/m4/flock.m4
@@ -1,5 +1,5 @@
 # flock.m4 serial 3
-dnl Copyright (C) 2008-2019 Free Software Foundation, Inc.
+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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/fnmatch.m4 b/m4/fnmatch.m4
index 75ba55b..2f8e4a8 100644
--- a/m4/fnmatch.m4
+++ b/m4/fnmatch.m4
@@ -1,6 +1,6 @@
-# Check for fnmatch - serial 14.  -*- coding: utf-8 -*-
+# Check for fnmatch - serial 15.  -*- coding: utf-8 -*-
 
-# Copyright (C) 2000-2007, 2009-2019 Free Software Foundation, Inc.
+# Copyright (C) 2000-2007, 2009-2020 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.
@@ -149,7 +149,5 @@ AC_DEFUN([gl_PREREQ_FNMATCH],
 [
   dnl Prerequisites of lib/fnmatch.c.
   AC_REQUIRE([AC_TYPE_MBSTATE_T])
-  AC_CHECK_DECLS([isblank], [], [], [[#include <ctype.h>]])
-  AC_CHECK_FUNCS_ONCE([btowc isblank iswctype mbsrtowcs mempcpy wmemchr wmemcpy wmempcpy])
-  AC_CHECK_HEADERS_ONCE([wctype.h])
+  AC_CHECK_FUNCS_ONCE([mbsrtowcs])
 ])
diff --git a/m4/fnmatch_h.m4 b/m4/fnmatch_h.m4
index fba6f86..a21ec2c 100644
--- a/m4/fnmatch_h.m4
+++ b/m4/fnmatch_h.m4
@@ -1,5 +1,5 @@
 # fnmatch_h.m4 serial 4
-dnl Copyright (C) 2009-2019 Free Software Foundation, Inc.
+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.
diff --git a/m4/fopen.m4 b/m4/fopen.m4
index 8a6e0ea..a5d687a 100644
--- a/m4/fopen.m4
+++ b/m4/fopen.m4
@@ -1,5 +1,5 @@
-# fopen.m4 serial 10
-dnl Copyright (C) 2007-2019 Free Software Foundation, Inc.
+# fopen.m4 serial 12
+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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -58,5 +58,91 @@ changequote([,])dnl
   esac
 ])
 
+AC_DEFUN([gl_FUNC_FOPEN_GNU],
+[
+  AC_REQUIRE([gl_FUNC_FOPEN])
+  AC_CACHE_CHECK([whether fopen supports the mode character 'x'],
+    [gl_cv_func_fopen_mode_x],
+    [rm -f conftest.x
+     AC_RUN_IFELSE(
+       [AC_LANG_SOURCE([[
+#include <stdio.h>
+#include <errno.h>
+int main ()
+{
+  FILE *fp;
+  fp = fopen ("conftest.x", "w");
+  fclose (fp);
+  fp = fopen ("conftest.x", "wx");
+  if (fp != NULL)
+    /* 'x' ignored */
+    return 1;
+  else if (errno == EEXIST)
+    return 0;
+  else
+    /* 'x' rejected */
+    return 2;
+}]])],
+       [gl_cv_func_fopen_mode_x=yes],
+       [gl_cv_func_fopen_mode_x=no],
+       [case "$host_os" in
+          # Guess yes on glibc and musl systems.
+          linux*-gnu* | gnu* | kfreebsd*-gnu | *-musl*)
+            gl_cv_func_fopen_mode_x="guessing yes" ;;
+          # If we don't know, obey --enable-cross-guesses.
+          *)
+            gl_cv_func_fopen_mode_x="$gl_cross_guess_normal" ;;
+        esac
+       ])
+     rm -f conftest.x
+    ])
+  AC_CACHE_CHECK([whether fopen supports the mode character 'e'],
+    [gl_cv_func_fopen_mode_e],
+    [echo foo > conftest.x
+     AC_RUN_IFELSE(
+       [AC_LANG_SOURCE([[
+#include <stdio.h>
+#include <errno.h>
+#include <fcntl.h>
+]GL_MDA_DEFINES[
+int main ()
+{
+  FILE *fp = fopen ("conftest.x", "re");
+  if (fp != NULL)
+    {
+      if (fcntl (fileno (fp), F_GETFD) & FD_CLOEXEC)
+        return 0;
+      else
+        /* 'e' ignored */
+        return 1;
+    }
+  else
+    /* 'e' rejected */
+    return 2;
+}]])],
+       [gl_cv_func_fopen_mode_e=yes],
+       [gl_cv_func_fopen_mode_e=no],
+       [case "$host_os" in
+          # Guess yes on glibc and musl systems.
+          linux*-gnu* | gnu* | kfreebsd*-gnu | *-musl*)
+            gl_cv_func_fopen_mode_e="guessing yes" ;;
+          # Guess no on native Windows.
+          mingw*)
+            gl_cv_func_fopen_mode_e="guessing no" ;;
+          # If we don't know, obey --enable-cross-guesses.
+          *)
+            gl_cv_func_fopen_mode_e="$gl_cross_guess_normal" ;;
+        esac
+       ])
+     rm -f conftest.x
+    ])
+  case "$gl_cv_func_fopen_mode_x" in
+    *no) REPLACE_FOPEN=1 ;;
+  esac
+  case "$gl_cv_func_fopen_mode_e" in
+    *no) REPLACE_FOPEN=1 ;;
+  esac
+])
+
 # Prerequisites of lib/fopen.c.
 AC_DEFUN([gl_PREREQ_FOPEN], [:])
diff --git a/m4/fpurge.m4 b/m4/fpurge.m4
index 6c5b3e9..9a486e0 100644
--- a/m4/fpurge.m4
+++ b/m4/fpurge.m4
@@ -1,5 +1,5 @@
-# fpurge.m4 serial 9
-dnl Copyright (C) 2007, 2009-2019 Free Software Foundation, Inc.
+# fpurge.m4 serial 12
+dnl Copyright (C) 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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -8,6 +8,7 @@ AC_DEFUN([gl_FUNC_FPURGE],
 [
   AC_REQUIRE([gl_STDIO_H_DEFAULTS])
   AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CHECK_HEADERS_ONCE([stdio_ext.h])
   AC_CHECK_FUNCS_ONCE([fpurge])
   AC_CHECK_FUNCS_ONCE([__fpurge])
   AC_CHECK_DECLS([fpurge], , , [[#include <stdio.h>]])
@@ -19,43 +20,43 @@ AC_DEFUN([gl_FUNC_FPURGE],
          [AC_LANG_PROGRAM(
             [[#include <stdio.h>
 ]],
-            [FILE *f = fopen ("conftest.txt", "w+");
-             if (!f)
-               return 1;
-             if (fputc ('a', f) != 'a')
-               { fclose (f); return 2; }
-             rewind (f);
-             if (fgetc (f) != 'a')
-               { fclose (f); return 3; }
-             if (fgetc (f) != EOF)
-               { fclose (f); return 4; }
-             if (fpurge (f) != 0)
-               { fclose (f); return 5; }
-             if (putc ('b', f) != 'b')
-               { fclose (f); return 6; }
-             if (fclose (f) != 0)
-               return 7;
-             if ((f = fopen ("conftest.txt", "r")) == NULL)
-               return 8;
-             if (fgetc (f) != 'a')
-               { fclose (f); return 9; }
-             if (fgetc (f) != 'b')
-               { fclose (f); return 10; }
-             if (fgetc (f) != EOF)
-               { fclose (f); return 11; }
-             if (fclose (f) != 0)
-               return 12;
-             if (remove ("conftest.txt") != 0)
-               return 13;
-             return 0;
-            ])],
+            [[FILE *f = fopen ("conftest.txt", "w+");
+              if (!f)
+                return 1;
+              if (fputc ('a', f) != 'a')
+                { fclose (f); return 2; }
+              rewind (f);
+              if (fgetc (f) != 'a')
+                { fclose (f); return 3; }
+              if (fgetc (f) != EOF)
+                { fclose (f); return 4; }
+              if (fpurge (f) != 0)
+                { fclose (f); return 5; }
+              if (putc ('b', f) != 'b')
+                { fclose (f); return 6; }
+              if (fclose (f) != 0)
+                return 7;
+              if ((f = fopen ("conftest.txt", "r")) == NULL)
+                return 8;
+              if (fgetc (f) != 'a')
+                { fclose (f); return 9; }
+              if (fgetc (f) != 'b')
+                { fclose (f); return 10; }
+              if (fgetc (f) != EOF)
+                { fclose (f); return 11; }
+              if (fclose (f) != 0)
+                return 12;
+              if (remove ("conftest.txt") != 0)
+                return 13;
+              return 0;
+            ]])],
          [gl_cv_func_fpurge_works=yes],
          [gl_cv_func_fpurge_works=no],
          [case "$host_os" in
                      # Guess yes on musl systems.
             *-musl*) gl_cv_func_fpurge_works="guessing yes" ;;
-                     # Guess no otherwise.
-            *)       gl_cv_func_fpurge_works="guessing no" ;;
+                     # Otherwise obey --enable-cross-guesses.
+            *)       gl_cv_func_fpurge_works="$gl_cross_guess_normal" ;;
           esac
          ])
       ])
diff --git a/m4/freading.m4 b/m4/freading.m4
index 33e4d1c..6eb25ab 100644
--- a/m4/freading.m4
+++ b/m4/freading.m4
@@ -1,10 +1,11 @@
-# freading.m4 serial 1
-dnl Copyright (C) 2007, 2009-2019 Free Software Foundation, Inc.
+# freading.m4 serial 2
+dnl Copyright (C) 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,
 dnl with or without modifications, as long as this notice is preserved.
 
 AC_DEFUN([gl_FUNC_FREADING],
 [
+  AC_CHECK_HEADERS_ONCE([stdio_ext.h])
   AC_CHECK_FUNCS_ONCE([__freading])
 ])
diff --git a/m4/free.m4 b/m4/free.m4
new file mode 100644
index 0000000..bf9fc31
--- /dev/null
+++ b/m4/free.m4
@@ -0,0 +1,49 @@
+# free.m4 serial 5
+# Copyright (C) 2003-2005, 2009-2020 Free Software Foundation, Inc.
+# This file is free software; the Free Software Foundation
+# gives unlimited permission to copy and/or distribute it,
+# with or without modifications, as long as this notice is preserved.
+
+# Written by Paul Eggert and Bruno Haible.
+
+AC_DEFUN([gl_FUNC_FREE],
+[
+  AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
+
+  dnl In the next release of POSIX, free must preserve errno.
+  dnl https://www.austingroupbugs.net/view.php?id=385
+  dnl https://sourceware.org/bugzilla/show_bug.cgi?id=17924
+  dnl So far, we know of three platforms that do this:
+  dnl * glibc >= 2.33, thanks to the fix for this bug:
+  dnl   <https://sourceware.org/bugzilla/show_bug.cgi?id=17924>
+  dnl * OpenBSD >= 4.5, thanks to this commit:
+  dnl   <https://cvsweb.openbsd.org/cgi-bin/cvsweb/src/lib/libc/stdlib/malloc.c.diff?r1=1.100&r2=1.101&f=h>
+  dnl * Solaris, because its malloc() implementation is based on brk(),
+  dnl   not mmap(); hence its free() implementation makes no system calls.
+  dnl For other platforms, you can only be sure if they state it in their
+  dnl documentation, or by code inspection of the free() implementation in libc.
+  AC_CACHE_CHECK([whether free is known to preserve errno],
+    [gl_cv_func_free_preserves_errno],
+    [AC_COMPILE_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[#include <stdlib.h>
+          ]],
+          [[#if 2 < __GLIBC__ + (33 <= __GLIBC_MINOR__)
+            #elif defined __OpenBSD__
+            #elif defined __sun
+            #else
+              #error "'free' is not known to preserve errno"
+            #endif
+          ]])],
+       [gl_cv_func_free_preserves_errno=yes],
+       [gl_cv_func_free_preserves_errno=no])
+    ])
+
+  case $gl_cv_func_free_preserves_errno in
+   *yes) ;;
+   *) REPLACE_FREE=1 ;;
+  esac
+])
+
+# Prerequisites of lib/free.c.
+AC_DEFUN([gl_PREREQ_FREE], [:])
diff --git a/m4/fseek.m4 b/m4/fseek.m4
index 2dfeecb..e36508c 100644
--- a/m4/fseek.m4
+++ b/m4/fseek.m4
@@ -1,5 +1,5 @@
 # fseek.m4 serial 4
-dnl Copyright (C) 2007, 2009-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/fseeko.m4 b/m4/fseeko.m4
index 1e2b08d..a64e640 100644
--- a/m4/fseeko.m4
+++ b/m4/fseeko.m4
@@ -1,5 +1,5 @@
-# fseeko.m4 serial 19
-dnl Copyright (C) 2007-2019 Free Software Foundation, Inc.
+# fseeko.m4 serial 20
+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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -17,7 +17,7 @@ AC_DEFUN([gl_FUNC_FSEEKO],
   AC_CACHE_CHECK([for fseeko], [gl_cv_func_fseeko],
     [
       AC_LINK_IFELSE([AC_LANG_PROGRAM([[#include <stdio.h>
-]], [fseeko (stdin, 0, 0);])],
+]], [[fseeko (stdin, 0, 0);]])],
         [gl_cv_func_fseeko=yes], [gl_cv_func_fseeko=no])
     ])
 
diff --git a/m4/fstat.m4 b/m4/fstat.m4
index 2a59c8f..bd8cb79 100644
--- a/m4/fstat.m4
+++ b/m4/fstat.m4
@@ -1,5 +1,5 @@
-# fstat.m4 serial 6
-dnl Copyright (C) 2011-2019 Free Software Foundation, Inc.
+# fstat.m4 serial 7
+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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -35,5 +35,6 @@ AC_DEFUN([gl_FUNC_FSTAT],
 # Prerequisites of lib/fstat.c and lib/stat-w32.c.
 AC_DEFUN([gl_PREREQ_FSTAT], [
   AC_REQUIRE([gl_HEADER_SYS_STAT_H])
+  AC_REQUIRE([gl_PREREQ_STAT_W32])
   :
 ])
diff --git a/m4/fstatat.m4 b/m4/fstatat.m4
new file mode 100644
index 0000000..19583ed
--- /dev/null
+++ b/m4/fstatat.m4
@@ -0,0 +1,65 @@
+# fstatat.m4 serial 4
+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,
+dnl with or without modifications, as long as this notice is preserved.
+
+# Written by Jim Meyering.
+
+# If we have the fstatat function, and it has the bug (in AIX 7.1)
+# that it does not fill in st_size correctly, use the replacement function.
+AC_DEFUN([gl_FUNC_FSTATAT],
+[
+  AC_REQUIRE([gl_SYS_STAT_H_DEFAULTS])
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+  AC_REQUIRE([gl_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK])
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  AC_CHECK_FUNCS_ONCE([fstatat])
+
+  if test $ac_cv_func_fstatat = no; then
+    HAVE_FSTATAT=0
+  else
+    dnl Test for an AIX 7.1 bug; see
+    dnl <https://lists.gnu.org/r/bug-tar/2011-09/msg00015.html>.
+    AC_CACHE_CHECK([whether fstatat (..., 0) works],
+      [gl_cv_func_fstatat_zero_flag],
+      [AC_RUN_IFELSE(
+         [AC_LANG_SOURCE(
+            [[
+              #include <fcntl.h>
+              #include <sys/stat.h>
+              int
+              main (void)
+              {
+                struct stat a;
+                return fstatat (AT_FDCWD, ".", &a, 0) != 0;
+              }
+            ]])],
+         [gl_cv_func_fstatat_zero_flag=yes],
+         [gl_cv_func_fstatat_zero_flag=no],
+         [case "$host_os" in
+            aix*) gl_cv_func_fstatat_zero_flag="guessing no";;
+            *)    gl_cv_func_fstatat_zero_flag="guessing yes";;
+          esac
+         ])
+      ])
+
+    case $gl_cv_func_fstatat_zero_flag+$gl_cv_func_lstat_dereferences_slashed_symlink in
+    *yes+*yes) ;;
+    *) REPLACE_FSTATAT=1 ;;
+    esac
+
+    case $host_os in
+      solaris*)
+        REPLACE_FSTATAT=1 ;;
+    esac
+
+    case $REPLACE_FSTATAT,$gl_cv_func_fstatat_zero_flag in
+      1,*yes)
+         AC_DEFINE([HAVE_WORKING_FSTATAT_ZERO_FLAG], [1],
+           [Define to 1 if fstatat (..., 0) works.
+            For example, it does not work in AIX 7.1.])
+         ;;
+    esac
+  fi
+])
diff --git a/m4/ftell.m4 b/m4/ftell.m4
index 713dd9f..22055d4 100644
--- a/m4/ftell.m4
+++ b/m4/ftell.m4
@@ -1,5 +1,5 @@
 # ftell.m4 serial 3
-dnl Copyright (C) 2007, 2009-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/ftello.m4 b/m4/ftello.m4
index 336a4b5..4c629c0 100644
--- a/m4/ftello.m4
+++ b/m4/ftello.m4
@@ -1,5 +1,5 @@
 # ftello.m4 serial 13
-dnl Copyright (C) 2007-2019 Free Software Foundation, Inc.
+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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/futimens.m4 b/m4/futimens.m4
index b5f4be9..145b8ff 100644
--- a/m4/futimens.m4
+++ b/m4/futimens.m4
@@ -1,7 +1,7 @@
-# serial 8
+# serial 9
 # See if we need to provide futimens replacement.
 
-dnl Copyright (C) 2009-2019 Free Software Foundation, Inc.
+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.
@@ -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/getaddrinfo.m4 b/m4/getaddrinfo.m4
index 59b8571..b932f73 100644
--- a/m4/getaddrinfo.m4
+++ b/m4/getaddrinfo.m4
@@ -1,5 +1,5 @@
-# getaddrinfo.m4 serial 31
-dnl Copyright (C) 2004-2019 Free Software Foundation, Inc.
+# getaddrinfo.m4 serial 33
+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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -8,7 +8,6 @@ AC_DEFUN([gl_GETADDRINFO],
 [
   AC_REQUIRE([gl_HEADER_SYS_SOCKET])dnl for HAVE_SYS_SOCKET_H, HAVE_WINSOCK2_H
   AC_REQUIRE([gl_HEADER_NETDB])dnl for HAVE_NETDB_H
-  AC_MSG_CHECKING([how to do getaddrinfo, freeaddrinfo and getnameinfo])
   GETADDRINFO_LIB=
   gai_saved_LIBS="$LIBS"
 
@@ -55,10 +54,40 @@ AC_DEFUN([gl_GETADDRINFO],
     if test "$gl_cv_w32_getaddrinfo" = "yes"; then
       GETADDRINFO_LIB="-lws2_32"
       LIBS="$gai_saved_LIBS $GETADDRINFO_LIB"
+      dnl Check for correct signature, in particular for a cdecl-compatible
+      dnl calling convention.
+      AC_CACHE_CHECK([for getaddrinfo with POSIX signature],
+        [gl_cv_func_getaddrinfo_posix_signature],
+        [AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
+#include <sys/types.h>
+#ifdef HAVE_SYS_SOCKET_H
+#include <sys/socket.h>
+#endif
+#ifdef HAVE_NETDB_H
+#include <netdb.h>
+#endif
+#ifdef HAVE_WS2TCPIP_H
+#include <ws2tcpip.h>
+#endif
+#include <stddef.h>
+extern
+#ifdef __cplusplus
+"C"
+#endif
+int getaddrinfo (const char *, const char *, const struct addrinfo *, struct addrinfo **);
+]])],
+           [gl_cv_func_getaddrinfo_posix_signature=yes],
+           [gl_cv_func_getaddrinfo_posix_signature=no])
+        ])
+      if test $gl_cv_func_getaddrinfo_posix_signature = no; then
+        REPLACE_GETADDRINFO=1
+      fi
     else
       HAVE_GETADDRINFO=0
     fi
   fi
+  AC_DEFINE_UNQUOTED([HAVE_GETADDRINFO], [$HAVE_GETADDRINFO],
+    [Define to 1 if getaddrinfo exists, or to 0 otherwise.])
 
   # We can't use AC_REPLACE_FUNCS here because gai_strerror may be an
   # inline function declared in ws2tcpip.h, so we need to get that
diff --git a/m4/getcwd-abort-bug.m4 b/m4/getcwd-abort-bug.m4
new file mode 100644
index 0000000..b5cf86e
--- /dev/null
+++ b/m4/getcwd-abort-bug.m4
@@ -0,0 +1,159 @@
+# serial 15
+# Determine whether getcwd aborts when the length of the working directory
+# name is unusually large.  Any length between 4k and 16k trigger the bug
+# when using glibc-2.4.90-9 or older.
+
+# Copyright (C) 2006, 2009-2020 Free Software Foundation, Inc.
+# This file is free software; the Free Software Foundation
+# gives unlimited permission to copy and/or distribute it,
+# with or without modifications, as long as this notice is preserved.
+
+# From Jim Meyering
+
+# gl_FUNC_GETCWD_ABORT_BUG([ACTION-IF-BUGGY[, ACTION-IF-WORKS]])
+AC_DEFUN([gl_FUNC_GETCWD_ABORT_BUG],
+[
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CHECK_DECLS_ONCE([getcwd])
+  AC_CHECK_HEADERS_ONCE([unistd.h])
+  AC_REQUIRE([gl_PATHMAX_SNIPPET_PREREQ])
+
+  gl_CHECK_FUNC_GETPAGESIZE
+  if test $gl_cv_func_getpagesize = yes; then
+    AC_DEFINE_UNQUOTED([HAVE_GETPAGESIZE], [1],
+      [Define to 1 if the system has the 'getpagesize' function.])
+  fi
+
+  AC_CACHE_CHECK([whether getcwd succeeds when 4k < cwd_length < 16k],
+    [gl_cv_func_getcwd_succeeds_beyond_4k],
+    [# Remove any remnants of a previous test.
+     rm -rf confdir-14B---
+     # Arrange for deletion of the temporary directory this test creates.
+     ac_clean_files="$ac_clean_files confdir-14B---"
+     dnl Please keep this in sync with tests/test-getcwd.c.
+     AC_RUN_IFELSE(
+       [AC_LANG_SOURCE(
+          [[
+#include <errno.h>
+#include <stdlib.h>
+#if HAVE_UNISTD_H
+# include <unistd.h>
+#else /* on Windows with MSVC */
+# include <direct.h>
+#endif
+#include <string.h>
+#include <sys/stat.h>
+
+]gl_PATHMAX_SNIPPET[
+]GL_MDA_DEFINES[
+
+#ifndef S_IRWXU
+# define S_IRWXU 0700
+#endif
+
+/* FIXME: skip the run-test altogether on systems without getpagesize.  */
+#if ! HAVE_GETPAGESIZE
+# define getpagesize() 0
+#endif
+
+/* This size is chosen to be larger than PATH_MAX (4k), yet smaller than
+   the 16kB pagesize on ia64 linux.  Those conditions make the code below
+   trigger a bug in glibc's getcwd implementation before 2.4.90-10.  */
+#define TARGET_LEN (5 * 1024)
+
+int
+main ()
+{
+  char *cwd;
+  size_t initial_cwd_len;
+  int fail = 0;
+
+  /* The bug is triggered when PATH_MAX < getpagesize (), so skip
+     this relatively expensive and invasive test if that's not true.  */
+#ifdef PATH_MAX
+  int bug_possible = PATH_MAX < getpagesize ();
+#else
+  int bug_possible = 0;
+#endif
+  if (! bug_possible)
+    return 0;
+
+  cwd = getcwd (NULL, 0);
+  if (cwd == NULL)
+    return 2;
+
+  initial_cwd_len = strlen (cwd);
+  free (cwd);
+
+  if (1)
+    {
+      static char const dir_name[] = "confdir-14B---";
+      size_t desired_depth = ((TARGET_LEN - 1 - initial_cwd_len)
+                              / sizeof dir_name);
+      size_t d;
+      for (d = 0; d < desired_depth; d++)
+        {
+          if (mkdir (dir_name, S_IRWXU) < 0 || chdir (dir_name) < 0)
+            {
+              if (! (errno == ERANGE || errno == ENAMETOOLONG
+                     || errno == ENOENT))
+                fail = 3; /* Unable to construct deep hierarchy.  */
+              break;
+            }
+        }
+
+      /* If libc has the bug in question, this invocation of getcwd
+         results in a failed assertion.  */
+      cwd = getcwd (NULL, 0);
+      if (cwd == NULL)
+        fail = 4; /* getcwd didn't assert, but it failed for a long name
+                     where the answer could have been learned.  */
+      free (cwd);
+
+      /* Call rmdir first, in case the above chdir failed.  */
+      rmdir (dir_name);
+      while (0 < d--)
+        {
+          if (chdir ("..") < 0)
+            {
+              fail = 5;
+              break;
+            }
+          rmdir (dir_name);
+        }
+    }
+
+  return fail;
+}
+          ]])],
+       [gl_cv_func_getcwd_succeeds_beyond_4k=yes],
+       [dnl An abort will provoke an exit code of something like 134 (128 + 6).
+        dnl An exit code of 4 can also occur (in OpenBSD 6.7, NetBSD 5.1 for
+        dnl example): getcwd (NULL, 0) fails rather than returning a string
+        dnl longer than PATH_MAX.  This may be POSIX compliant (in some
+        dnl interpretations of POSIX).  But gnulib's getcwd module wants to
+        dnl provide a non-NULL value in this case.
+        ret=$?
+        if test $ret -ge 128 || test $ret = 4; then
+          gl_cv_func_getcwd_succeeds_beyond_4k=no
+        else
+          gl_cv_func_getcwd_succeeds_beyond_4k=yes
+        fi
+       ],
+       [case "$host_os" in
+                   # Guess yes on musl systems.
+          *-musl*) gl_cv_func_getcwd_succeeds_beyond_4k="guessing yes" ;;
+                   # Guess no otherwise, even on glibc systems.
+          *)       gl_cv_func_getcwd_succeeds_beyond_4k="guessing no"
+        esac
+       ])
+    ])
+  case "$gl_cv_func_getcwd_succeeds_beyond_4k" in
+    *no)
+      $1
+      ;;
+    *)
+      $2
+      ;;
+  esac
+])
diff --git a/m4/getcwd-path-max.m4 b/m4/getcwd-path-max.m4
new file mode 100644
index 0000000..859c7de
--- /dev/null
+++ b/m4/getcwd-path-max.m4
@@ -0,0 +1,236 @@
+# serial 25
+# Check for several getcwd bugs with long file names.
+# If so, arrange to compile the wrapper function.
+
+# This is necessary for at least GNU libc on linux-2.4.19 and 2.4.20.
+# I've heard that this is due to a Linux kernel bug, and that it has
+# been fixed between 2.4.21-pre3 and 2.4.21-pre4.
+
+# Copyright (C) 2003-2007, 2009-2020 Free Software Foundation, Inc.
+# This file is free software; the Free Software Foundation
+# gives unlimited permission to copy and/or distribute it,
+# with or without modifications, as long as this notice is preserved.
+
+# From Jim Meyering
+
+AC_DEFUN([gl_FUNC_GETCWD_PATH_MAX],
+[
+  AC_CHECK_DECLS_ONCE([getcwd])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+  AC_CHECK_HEADERS_ONCE([unistd.h])
+  AC_REQUIRE([gl_PATHMAX_SNIPPET_PREREQ])
+  AC_CACHE_CHECK([whether getcwd handles long file names properly],
+    [gl_cv_func_getcwd_path_max],
+    [# Arrange for deletion of the temporary directory this test creates.
+     ac_clean_files="$ac_clean_files confdir3"
+     dnl Please keep this in sync with tests/test-getcwd.c.
+     AC_RUN_IFELSE(
+       [AC_LANG_SOURCE(
+          [[
+#include <errno.h>
+#include <stdlib.h>
+#if HAVE_UNISTD_H
+# include <unistd.h>
+#else
+# include <direct.h>
+#endif
+#include <string.h>
+#include <limits.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <fcntl.h>
+
+]gl_PATHMAX_SNIPPET[
+
+#ifndef AT_FDCWD
+# define AT_FDCWD 0
+#endif
+#ifdef ENAMETOOLONG
+# define is_ENAMETOOLONG(x) ((x) == ENAMETOOLONG)
+#else
+# define is_ENAMETOOLONG(x) 0
+#endif
+
+/* Use the getcwd function, not any macro.  */
+#undef getcwd
+
+]GL_MDA_DEFINES[
+
+#ifndef S_IRWXU
+# define S_IRWXU 0700
+#endif
+
+/* The length of this name must be 8.  */
+#define DIR_NAME "confdir3"
+#define DIR_NAME_LEN 8
+#define DIR_NAME_SIZE (DIR_NAME_LEN + 1)
+
+/* The length of "../".  */
+#define DOTDOTSLASH_LEN 3
+
+/* Leftover bytes in the buffer, to work around library or OS bugs.  */
+#define BUF_SLOP 20
+
+int
+main ()
+{
+#ifndef PATH_MAX
+  /* The Hurd doesn't define this, so getcwd can't exhibit the bug --
+     at least not on a local file system.  And if we were to start worrying
+     about remote file systems, we'd have to enable the wrapper function
+     all of the time, just to be safe.  That's not worth the cost.  */
+  exit (0);
+#elif ((INT_MAX / (DIR_NAME_SIZE / DOTDOTSLASH_LEN + 1) \
+        - DIR_NAME_SIZE - BUF_SLOP) \
+       <= PATH_MAX)
+  /* FIXME: Assuming there's a system for which this is true,
+     this should be done in a compile test.  */
+  exit (0);
+#else
+  char buf[PATH_MAX * (DIR_NAME_SIZE / DOTDOTSLASH_LEN + 1)
+           + DIR_NAME_SIZE + BUF_SLOP];
+  char *cwd = getcwd (buf, PATH_MAX);
+  size_t initial_cwd_len;
+  size_t cwd_len;
+  int fail = 0;
+  size_t n_chdirs = 0;
+
+  if (cwd == NULL)
+    exit (10);
+
+  cwd_len = initial_cwd_len = strlen (cwd);
+
+  while (1)
+    {
+      size_t dotdot_max = PATH_MAX * (DIR_NAME_SIZE / DOTDOTSLASH_LEN);
+      char *c = NULL;
+
+      cwd_len += DIR_NAME_SIZE;
+      /* If mkdir or chdir fails, it could be that this system cannot create
+         any file with an absolute name longer than PATH_MAX, such as cygwin.
+         If so, leave fail as 0, because the current working directory can't
+         be too long for getcwd if it can't even be created.  On Linux with
+         the 9p file system, mkdir fails with error EINVAL when cwd_len gets
+         too long; ignore this failure because the getcwd() system call
+         produces good results whereas the gnulib substitute calls getdents64
+         which fails with error EPROTO.
+         For other errors, be pessimistic and consider that as a failure,
+         too.  */
+      if (mkdir (DIR_NAME, S_IRWXU) < 0 || chdir (DIR_NAME) < 0)
+        {
+          if (! (errno == ERANGE || is_ENAMETOOLONG (errno)))
+            #ifdef __linux__
+            if (! (errno == EINVAL))
+            #endif
+              fail = 20;
+          break;
+        }
+
+      if (PATH_MAX <= cwd_len && cwd_len < PATH_MAX + DIR_NAME_SIZE)
+        {
+          struct stat sb;
+
+          c = getcwd (buf, PATH_MAX);
+          if (!c && errno == ENOENT)
+            {
+              fail = 11;
+              break;
+            }
+          if (c)
+            {
+              fail = 31;
+              break;
+            }
+          if (! (errno == ERANGE || is_ENAMETOOLONG (errno)))
+            {
+              fail = 21;
+              break;
+            }
+
+          /* Our replacement needs to be able to stat() long ../../paths,
+             so generate a path larger than PATH_MAX to check,
+             avoiding the replacement if we can't stat().  */
+          c = getcwd (buf, cwd_len + 1);
+          if (c && !AT_FDCWD && stat (c, &sb) != 0 && is_ENAMETOOLONG (errno))
+            {
+              fail = 32;
+              break;
+            }
+        }
+
+      if (dotdot_max <= cwd_len - initial_cwd_len)
+        {
+          if (dotdot_max + DIR_NAME_SIZE < cwd_len - initial_cwd_len)
+            break;
+          c = getcwd (buf, cwd_len + 1);
+          if (!c)
+            {
+              if (! (errno == ERANGE || errno == ENOENT
+                     || is_ENAMETOOLONG (errno)))
+                {
+                  fail = 22;
+                  break;
+                }
+              if (AT_FDCWD || errno == ERANGE || errno == ENOENT)
+                {
+                  fail = 12;
+                  break;
+                }
+            }
+        }
+
+      if (c && strlen (c) != cwd_len)
+        {
+          fail = 23;
+          break;
+        }
+      ++n_chdirs;
+    }
+
+  /* Leaving behind such a deep directory is not polite.
+     So clean up here, right away, even though the driving
+     shell script would also clean up.  */
+  {
+    size_t i;
+
+    /* Try rmdir first, in case the chdir failed.  */
+    rmdir (DIR_NAME);
+    for (i = 0; i <= n_chdirs; i++)
+      {
+        if (chdir ("..") < 0)
+          break;
+        if (rmdir (DIR_NAME) != 0)
+          break;
+      }
+  }
+
+  exit (fail);
+#endif
+}
+          ]])],
+       [gl_cv_func_getcwd_path_max=yes],
+       [case $? in
+        10|11|12) gl_cv_func_getcwd_path_max='no, but it is partly working';;
+        31) gl_cv_func_getcwd_path_max='no, it has the AIX bug';;
+        32) gl_cv_func_getcwd_path_max='yes, but with shorter paths';;
+        *) gl_cv_func_getcwd_path_max=no;;
+        esac],
+       [# Cross-compilation guesses:
+        case "$host_os" in
+          aix*) # On AIX, it has the AIX bug.
+            gl_cv_func_getcwd_path_max='guessing no, it has the AIX bug' ;;
+          gnu*) # On Hurd, it is 'yes'.
+            gl_cv_func_getcwd_path_max='guessing yes' ;;
+          linux* | kfreebsd*)
+            # On older Linux+glibc it's 'no, but it is partly working',
+            # on newer Linux+glibc it's 'yes'.
+            # On Linux+musl libc, it's 'no, but it is partly working'.
+            # On kFreeBSD+glibc, it's 'no, but it is partly working'.
+            gl_cv_func_getcwd_path_max='guessing no, but it is partly working' ;;
+          *) # If we don't know, obey --enable-cross-guesses.
+            gl_cv_func_getcwd_path_max="$gl_cross_guess_normal" ;;
+        esac
+       ])
+    ])
+])
diff --git a/m4/getcwd.m4 b/m4/getcwd.m4
new file mode 100644
index 0000000..a646b90
--- /dev/null
+++ b/m4/getcwd.m4
@@ -0,0 +1,166 @@
+# getcwd.m4 - check for working getcwd that is compatible with glibc
+
+# Copyright (C) 2001, 2003-2007, 2009-2020 Free Software Foundation, Inc.
+# This file is free software; the Free Software Foundation
+# gives unlimited permission to copy and/or distribute it,
+# with or without modifications, as long as this notice is preserved.
+
+# Written by Paul Eggert.
+# serial 19
+
+AC_DEFUN([gl_FUNC_GETCWD_NULL],
+  [
+   AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+   AC_CHECK_HEADERS_ONCE([unistd.h])
+   AC_CACHE_CHECK([whether getcwd (NULL, 0) allocates memory for result],
+     [gl_cv_func_getcwd_null],
+     [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
+#	 include <stdlib.h>
+#        if HAVE_UNISTD_H
+#         include <unistd.h>
+#        else /* on Windows with MSVC */
+#         include <direct.h>
+#        endif
+         ]GL_MDA_DEFINES[
+#        ifndef getcwd
+         char *getcwd ();
+#        endif
+]], [[
+#if defined _WIN32 && ! defined __CYGWIN__
+/* mingw cwd does not start with '/', but _getcwd does allocate.
+   However, mingw fails to honor non-zero size.  */
+#else
+           if (chdir ("/") != 0)
+             return 1;
+           else
+             {
+               char *f = getcwd (NULL, 0);
+               if (! f)
+                 return 2;
+               if (f[0] != '/')
+                 { free (f); return 3; }
+               if (f[1] != '\0')
+                 { free (f); return 4; }
+               free (f);
+               return 0;
+             }
+#endif
+         ]])],
+        [gl_cv_func_getcwd_null=yes],
+        [gl_cv_func_getcwd_null=no],
+        [[case "$host_os" in
+                           # Guess yes on glibc systems.
+            *-gnu* | gnu*) gl_cv_func_getcwd_null="guessing yes";;
+                           # Guess yes on musl systems.
+            *-musl*)       gl_cv_func_getcwd_null="guessing yes";;
+                           # Guess yes on Cygwin.
+            cygwin*)       gl_cv_func_getcwd_null="guessing yes";;
+                           # If we don't know, obey --enable-cross-guesses.
+            *)             gl_cv_func_getcwd_null="$gl_cross_guess_normal";;
+          esac
+        ]])])
+])
+
+AC_DEFUN([gl_FUNC_GETCWD_SIGNATURE],
+[
+  AC_CACHE_CHECK([for getcwd with POSIX signature],
+    [gl_cv_func_getcwd_posix_signature],
+    [AC_COMPILE_IFELSE(
+      [AC_LANG_PROGRAM(
+         [[#include <unistd.h>
+         ]GL_MDA_DEFINES],
+         [[extern
+           #ifdef __cplusplus
+           "C"
+           #endif
+           char *getcwd (char *, size_t);
+         ]])
+      ],
+      [gl_cv_func_getcwd_posix_signature=yes],
+      [gl_cv_func_getcwd_posix_signature=no])
+   ])
+])
+
+dnl Guarantee that getcwd will malloc with a NULL first argument.  Assumes
+dnl that either the system getcwd is robust, or that calling code is okay
+dnl with spurious failures when run from a directory with an absolute name
+dnl larger than 4k bytes.
+dnl
+dnl Assumes that getcwd exists; if you are worried about obsolete
+dnl platforms that lacked getcwd(), then you need to use the GPL module.
+AC_DEFUN([gl_FUNC_GETCWD_LGPL],
+[
+  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
+  AC_REQUIRE([gl_FUNC_GETCWD_NULL])
+  AC_REQUIRE([gl_FUNC_GETCWD_SIGNATURE])
+
+  case $gl_cv_func_getcwd_null,$gl_cv_func_getcwd_posix_signature in
+  *yes,yes) ;;
+  *)
+    dnl Minimal replacement lib/getcwd-lgpl.c.
+    REPLACE_GETCWD=1
+    ;;
+  esac
+])
+
+dnl Check for all known getcwd bugs; useful for a program likely to be
+dnl executed from an arbitrary location.
+AC_DEFUN([gl_FUNC_GETCWD],
+[
+  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
+  AC_REQUIRE([gl_FUNC_GETCWD_NULL])
+  AC_REQUIRE([gl_FUNC_GETCWD_SIGNATURE])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+
+  gl_abort_bug=no
+  case "$host_os" in
+    mingw*)
+      gl_cv_func_getcwd_path_max=yes
+      ;;
+    *)
+      gl_FUNC_GETCWD_PATH_MAX
+      case "$gl_cv_func_getcwd_null" in
+        *yes)
+          gl_FUNC_GETCWD_ABORT_BUG([gl_abort_bug=yes])
+          ;;
+      esac
+      ;;
+  esac
+  dnl Define HAVE_MINIMALLY_WORKING_GETCWD and HAVE_PARTLY_WORKING_GETCWD
+  dnl if appropriate.
+  case "$gl_cv_func_getcwd_path_max" in
+    *"no" | *"no, it has the AIX bug") ;;
+    *)
+      AC_DEFINE([HAVE_MINIMALLY_WORKING_GETCWD], [1],
+        [Define to 1 if getcwd minimally works, that is, its result can be
+         trusted when it succeeds.])
+      ;;
+  esac
+  case "$gl_cv_func_getcwd_path_max" in
+    *"no, but it is partly working")
+      AC_DEFINE([HAVE_PARTLY_WORKING_GETCWD], [1],
+        [Define to 1 if getcwd works, except it sometimes fails when it
+         shouldn't, setting errno to ERANGE, ENAMETOOLONG, or ENOENT.])
+      ;;
+    *"yes, but with shorter paths")
+      AC_DEFINE([HAVE_GETCWD_SHORTER], [1],
+        [Define to 1 if getcwd works, but with shorter paths
+         than is generally tested with the replacement.])
+      ;;
+  esac
+
+  if { case "$gl_cv_func_getcwd_null" in *yes) false;; *) true;; esac; } \
+     || test $gl_cv_func_getcwd_posix_signature != yes \
+     || { case "$gl_cv_func_getcwd_path_max" in *yes*) false;; *) true;; esac; } \
+     || test $gl_abort_bug = yes; then
+    REPLACE_GETCWD=1
+  fi
+])
+
+# Prerequisites of lib/getcwd.c, when full replacement is in effect.
+AC_DEFUN([gl_PREREQ_GETCWD],
+[
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+  AC_REQUIRE([gl_CHECK_TYPE_STRUCT_DIRENT_D_INO])
+  :
+])
diff --git a/m4/getdelim.m4 b/m4/getdelim.m4
index e77c379..ac3917b 100644
--- a/m4/getdelim.m4
+++ b/m4/getdelim.m4
@@ -1,6 +1,6 @@
-# getdelim.m4 serial 13
+# getdelim.m4 serial 15
 
-dnl Copyright (C) 2005-2007, 2009-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2005-2007, 2009-2020 Free Software Foundation, Inc.
 dnl
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -42,6 +42,7 @@ AC_DEFUN([gl_FUNC_GETDELIM],
         int len = getdelim (&line, &siz, '\n', in);
         if (!(len == 4 && line && strcmp (line, "foo\n") == 0))
           { free (line); fclose (in); return 2; }
+        free (line);
       }
       {
         /* Test result for a NULL buffer and a non-zero size.
@@ -72,7 +73,7 @@ AC_DEFUN([gl_FUNC_GETDELIM],
             [gl_cv_func_working_getdelim="guessing yes"],
             [case "$host_os" in
                *-musl*) gl_cv_func_working_getdelim="guessing yes" ;;
-               *)       gl_cv_func_working_getdelim="guessing no" ;;
+               *)       gl_cv_func_working_getdelim="$gl_cross_guess_normal" ;;
              esac
             ])
          ])
diff --git a/m4/getdtablesize.m4 b/m4/getdtablesize.m4
index 96aa241..af32864 100644
--- a/m4/getdtablesize.m4
+++ b/m4/getdtablesize.m4
@@ -1,5 +1,5 @@
-# getdtablesize.m4 serial 7
-dnl Copyright (C) 2008-2019 Free Software Foundation, Inc.
+# 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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -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/getgroups.m4 b/m4/getgroups.m4
index c93447b..e344162 100644
--- a/m4/getgroups.m4
+++ b/m4/getgroups.m4
@@ -1,16 +1,14 @@
-# serial 22
+# serial 24
 
 dnl From Jim Meyering.
 dnl A wrapper around AC_FUNC_GETGROUPS.
 
-# Copyright (C) 1996-1997, 1999-2004, 2008-2019 Free Software Foundation, Inc.
+# Copyright (C) 1996-1997, 1999-2004, 2008-2020 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.
 
-m4_version_prereq([2.70], [] ,[
-
 # This is taken from the following Autoconf patch:
 # https://git.savannah.gnu.org/gitweb/?p=autoconf.git;a=commitdiff;h=7fbb553727ed7e0e689a17594b58559ecf3ea6e9
 AC_DEFUN([AC_FUNC_GETGROUPS],
@@ -44,8 +42,8 @@ AC_DEFUN([AC_FUNC_GETGROUPS],
             *-gnu* | gnu*) ac_cv_func_getgroups_works="guessing yes" ;;
                            # Guess yes on musl systems.
             *-musl*)       ac_cv_func_getgroups_works="guessing yes" ;;
-                           # If we don't know, assume the worst.
-            *)             ac_cv_func_getgroups_works="guessing no" ;;
+                           # If we don't know, obey --enable-cross-guesses.
+            *)             ac_cv_func_getgroups_works="$gl_cross_guess_normal" ;;
           esac
          ])
       ])
@@ -61,8 +59,6 @@ AC_DEFUN([AC_FUNC_GETGROUPS],
   LIBS=$ac_save_LIBS
 ])# AC_FUNC_GETGROUPS
 
-])
-
 AC_DEFUN([gl_FUNC_GETGROUPS],
 [
   AC_REQUIRE([AC_TYPE_GETGROUPS])
@@ -83,7 +79,8 @@ AC_DEFUN([gl_FUNC_GETGROUPS],
       AC_DEFINE([GETGROUPS_ZERO_BUG], [1], [Define this to 1 if
         getgroups(0,NULL) does not return the number of groups.])
     else
-      dnl Detect FreeBSD bug; POSIX requires getgroups(-1,ptr) to fail.
+      dnl Detect Mac OS X and FreeBSD bug; POSIX requires getgroups(-1,ptr)
+      dnl to fail.
       AC_CACHE_CHECK([whether getgroups handles negative values],
         [gl_cv_func_getgroups_works],
         [AC_RUN_IFELSE([AC_LANG_PROGRAM([AC_INCLUDES_DEFAULT],
@@ -99,8 +96,8 @@ AC_DEFUN([gl_FUNC_GETGROUPS],
              *-gnu* | gnu*) gl_cv_func_getgroups_works="guessing yes" ;;
                             # Guess yes on musl systems.
              *-musl*)       gl_cv_func_getgroups_works="guessing yes" ;;
-                            # If we don't know, assume the worst.
-             *)             gl_cv_func_getgroups_works="guessing no" ;;
+                            # If we don't know, obey --enable-cross-guesses.
+             *)             gl_cv_func_getgroups_works="$gl_cross_guess_normal" ;;
            esac
           ])])
       case "$gl_cv_func_getgroups_works" in
diff --git a/m4/getline.m4 b/m4/getline.m4
index 32f771c..0609f1d 100644
--- a/m4/getline.m4
+++ b/m4/getline.m4
@@ -1,6 +1,6 @@
-# getline.m4 serial 29
+# getline.m4 serial 30
 
-dnl Copyright (C) 1998-2003, 2005-2007, 2009-2019 Free Software Foundation,
+dnl Copyright (C) 1998-2003, 2005-2007, 2009-2020 Free Software Foundation,
 dnl Inc.
 dnl
 dnl This file is free software; the Free Software Foundation
@@ -80,7 +80,7 @@ AC_DEFUN([gl_FUNC_GETLINE],
             [am_cv_func_working_getline="guessing yes"],
             [case "$host_os" in
                *-musl*) am_cv_func_working_getline="guessing yes" ;;
-               *)       am_cv_func_working_getline="guessing no" ;;
+               *)       am_cv_func_working_getline="$gl_cross_guess_normal" ;;
              esac
             ])
          ])
diff --git a/m4/getopt.m4 b/m4/getopt.m4
index 5991bf8..595483d 100644
--- a/m4/getopt.m4
+++ b/m4/getopt.m4
@@ -1,5 +1,5 @@
-# getopt.m4 serial 46
-dnl Copyright (C) 2002-2006, 2008-2019 Free Software Foundation, Inc.
+# getopt.m4 serial 47
+dnl Copyright (C) 2002-2006, 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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -302,8 +302,10 @@ dnl is ambiguous with environment values that contain newlines.
            ]])],
         [gl_cv_func_getopt_gnu=yes],
         [gl_cv_func_getopt_gnu=no],
-        [dnl Cross compiling. Assume the worst, even on glibc platforms.
-         gl_cv_func_getopt_gnu="guessing no"
+        [dnl Cross compiling.
+         dnl Assume the worst, even on glibc platforms.
+         dnl But obey --enable-cross-guesses.
+         gl_cv_func_getopt_gnu="$gl_cross_guess_normal"
         ])
        case $gl_had_POSIXLY_CORRECT in
          exported) ;;
diff --git a/m4/getpagesize.m4 b/m4/getpagesize.m4
new file mode 100644
index 0000000..8f0f046
--- /dev/null
+++ b/m4/getpagesize.m4
@@ -0,0 +1,49 @@
+# getpagesize.m4 serial 10
+dnl Copyright (C) 2002, 2004-2005, 2007, 2009-2020 Free Software Foundation,
+dnl 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_FUNC_GETPAGESIZE],
+[
+  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  gl_CHECK_FUNC_GETPAGESIZE
+  if test $gl_cv_func_getpagesize = no; then
+    HAVE_GETPAGESIZE=0
+    AC_CHECK_HEADERS([OS.h])
+    if test $ac_cv_header_OS_h = yes; then
+      HAVE_OS_H=1
+    fi
+    AC_CHECK_HEADERS([sys/param.h])
+    if test $ac_cv_header_sys_param_h = yes; then
+      HAVE_SYS_PARAM_H=1
+    fi
+  fi
+  case "$host_os" in
+    mingw*)
+      REPLACE_GETPAGESIZE=1
+      ;;
+  esac
+  dnl Also check whether it's declared.
+  dnl mingw has getpagesize() in libgcc.a but doesn't declare it.
+  AC_CHECK_DECL([getpagesize], , [HAVE_DECL_GETPAGESIZE=0])
+])
+
+dnl Tests whether the function getpagesize() exists.
+dnl Sets gl_cv_func_getpagesize.
+AC_DEFUN([gl_CHECK_FUNC_GETPAGESIZE],
+[
+  dnl We can't use AC_CHECK_FUNC here, because getpagesize() is defined as a
+  dnl static inline function when compiling for Android 4.4 or older.
+  AC_CACHE_CHECK([for getpagesize], [gl_cv_func_getpagesize],
+    [AC_LINK_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[#include <unistd.h>]],
+          [[return getpagesize();]])
+       ],
+       [gl_cv_func_getpagesize=yes],
+       [gl_cv_func_getpagesize=no])
+    ])
+])
diff --git a/m4/getpass.m4 b/m4/getpass.m4
index e4448af..a2262c4 100644
--- a/m4/getpass.m4
+++ b/m4/getpass.m4
@@ -1,5 +1,5 @@
 # getpass.m4 serial 16
-dnl Copyright (C) 2002-2003, 2005-2006, 2009-2019 Free Software Foundation,
+dnl Copyright (C) 2002-2003, 2005-2006, 2009-2020 Free Software Foundation,
 dnl Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
diff --git a/m4/getprogname.m4 b/m4/getprogname.m4
index 4a96d06..6baefc9 100644
--- a/m4/getprogname.m4
+++ b/m4/getprogname.m4
@@ -1,6 +1,6 @@
 # getprogname.m4 - check for getprogname or replacements for it
 
-# Copyright (C) 2016-2019 Free Software Foundation, Inc.
+# Copyright (C) 2016-2020 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.
diff --git a/m4/getrandom.m4 b/m4/getrandom.m4
new file mode 100644
index 0000000..d6da71a
--- /dev/null
+++ b/m4/getrandom.m4
@@ -0,0 +1,68 @@
+# getrandom.m4 serial 8
+dnl Copyright 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_FUNC_GETRANDOM],
+[
+  AC_REQUIRE([gl_SYS_RANDOM_H_DEFAULTS])
+  AC_CHECK_FUNCS_ONCE([getrandom])
+  if test "$ac_cv_func_getrandom" != yes; then
+    HAVE_GETRANDOM=0
+  else
+    dnl On Solaris 11.4 the return type is 'int', not 'ssize_t'.
+    AC_CACHE_CHECK([whether getrandom is compatible with its GNU+BSD signature],
+      [gl_cv_func_getrandom_ok],
+      [AC_COMPILE_IFELSE(
+         [AC_LANG_PROGRAM(
+            [[/* Additional includes are needed before <sys/random.h> on uClibc
+                 and Mac OS X.  */
+              #include <sys/types.h>
+              #include <stdlib.h>
+              #include <sys/random.h>
+              ssize_t getrandom (void *, size_t, unsigned int);
+            ]],
+            [[]])
+         ],
+         [gl_cv_func_getrandom_ok=yes],
+         [gl_cv_func_getrandom_ok=no])
+      ])
+    if test $gl_cv_func_getrandom_ok = no; then
+      REPLACE_GETRANDOM=1
+    fi
+  fi
+
+  case "$host_os" in
+    mingw*)
+      AC_CHECK_HEADERS([bcrypt.h], [], [],
+        [[#include <windows.h>
+        ]])
+      AC_CACHE_CHECK([whether the bcrypt library is guaranteed to be present],
+        [gl_cv_lib_assume_bcrypt],
+        [AC_COMPILE_IFELSE(
+           [AC_LANG_PROGRAM(
+              [[#include <windows.h>]],
+              [[#if !(_WIN32_WINNT >= _WIN32_WINNT_WIN7)
+                  cannot assume it
+                #endif
+              ]])
+           ],
+           [gl_cv_lib_assume_bcrypt=yes],
+           [gl_cv_lib_assume_bcrypt=no])
+        ])
+      if test $gl_cv_lib_assume_bcrypt = yes; then
+        AC_DEFINE([HAVE_LIB_BCRYPT], [1],
+          [Define to 1 if the bcrypt library is guaranteed to be present.])
+        LIB_GETRANDOM='-lbcrypt'
+      else
+        LIB_GETRANDOM='-ladvapi32'
+      fi
+      ;;
+    *)
+      LIB_GETRANDOM= ;;
+  esac
+  AC_SUBST([LIB_GETRANDOM])
+])
diff --git a/m4/gettext.m4 b/m4/gettext.m4
index c9ae1f7..be247bf 100644
--- a/m4/gettext.m4
+++ b/m4/gettext.m4
@@ -1,5 +1,5 @@
-# gettext.m4 serial 60 (gettext-0.17)
-dnl Copyright (C) 1995-2007 Free Software Foundation, Inc.
+# gettext.m4 serial 66 (gettext-0.18.2)
+dnl Copyright (C) 1995-2014 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.
@@ -15,7 +15,7 @@ dnl They are *not* in the public domain.
 
 dnl Authors:
 dnl   Ulrich Drepper <drepper@cygnus.com>, 1995-2000.
-dnl   Bruno Haible <haible@clisp.cons.org>, 2000-2006.
+dnl   Bruno Haible <haible@clisp.cons.org>, 2000-2006, 2008-2010.
 
 dnl Macro to add for using GNU gettext.
 
@@ -35,7 +35,7 @@ dnl    will be ignored.  If NEEDSYMBOL is specified and is
 dnl    'need-formatstring-macros', then GNU gettext implementations that don't
 dnl    support the ISO C 99 <inttypes.h> formatstring macros will be ignored.
 dnl INTLDIR is used to find the intl libraries.  If empty,
-dnl    the value `$(top_builddir)/intl/' is used.
+dnl    the value '$(top_builddir)/intl/' is used.
 dnl
 dnl The result of the configuration is one of three cases:
 dnl 1) GNU gettext, as included in the intl subdirectory, will be compiled
@@ -60,6 +60,8 @@ AC_DEFUN([AM_GNU_GETTEXT],
   ifelse([$1], [], , [ifelse([$1], [external], , [ifelse([$1], [no-libtool], , [ifelse([$1], [use-libtool], ,
     [errprint([ERROR: invalid first argument to AM_GNU_GETTEXT
 ])])])])])
+  ifelse(ifelse([$1], [], [old])[]ifelse([$1], [no-libtool], [old]), [old],
+    [AC_DIAGNOSE([obsolete], [Use of AM_GNU_GETTEXT without [external] argument is deprecated.])])
   ifelse([$2], [], , [ifelse([$2], [need-ngettext], , [ifelse([$2], [need-formatstring-macros], ,
     [errprint([ERROR: invalid second argument to AM_GNU_GETTEXT
 ])])])])
@@ -95,7 +97,7 @@ AC_DEFUN([AM_GNU_GETTEXT],
     AC_REQUIRE([AM_ICONV_LINKFLAGS_BODY])
   ])
 
-  dnl Sometimes, on MacOS X, libintl requires linking with CoreFoundation.
+  dnl Sometimes, on Mac OS X, libintl requires linking with CoreFoundation.
   gt_INTL_MACOSX
 
   dnl Set USE_NLS.
@@ -123,11 +125,11 @@ AC_DEFUN([AM_GNU_GETTEXT],
     gt_use_preinstalled_gnugettext=no
     ifelse(gt_included_intl, yes, [
       AC_MSG_CHECKING([whether included gettext is requested])
-      AC_ARG_WITH(included-gettext,
+      AC_ARG_WITH([included-gettext],
         [  --with-included-gettext use the GNU gettext library included here],
         nls_cv_force_use_gnu_gettext=$withval,
         nls_cv_force_use_gnu_gettext=no)
-      AC_MSG_RESULT($nls_cv_force_use_gnu_gettext)
+      AC_MSG_RESULT([$nls_cv_force_use_gnu_gettext])
 
       nls_cv_use_gnu_gettext="$nls_cv_force_use_gnu_gettext"
       if test "$nls_cv_force_use_gnu_gettext" != "yes"; then
@@ -155,12 +157,18 @@ changequote([,])dnl
         fi
 
         AC_CACHE_CHECK([for GNU gettext in libc], [$gt_func_gnugettext_libc],
-         [AC_TRY_LINK([#include <libintl.h>
+         [AC_LINK_IFELSE(
+            [AC_LANG_PROGRAM(
+               [[
+#include <libintl.h>
 $gt_revision_test_code
 extern int _nl_msg_cat_cntr;
-extern int *_nl_domain_bindings;],
-            [bindtextdomain ("", "");
-return * gettext ("")$gt_expression_test_code + _nl_msg_cat_cntr + *_nl_domain_bindings],
+extern int *_nl_domain_bindings;
+               ]],
+               [[
+bindtextdomain ("", "");
+return * gettext ("")$gt_expression_test_code + _nl_msg_cat_cntr + *_nl_domain_bindings
+               ]])],
             [eval "$gt_func_gnugettext_libc=yes"],
             [eval "$gt_func_gnugettext_libc=no"])])
 
@@ -181,35 +189,47 @@ return * gettext ("")$gt_expression_test_code + _nl_msg_cat_cntr + *_nl_domain_b
             gt_save_LIBS="$LIBS"
             LIBS="$LIBS $LIBINTL"
             dnl Now see whether libintl exists and does not depend on libiconv.
-            AC_TRY_LINK([#include <libintl.h>
+            AC_LINK_IFELSE(
+              [AC_LANG_PROGRAM(
+                 [[
+#include <libintl.h>
 $gt_revision_test_code
 extern int _nl_msg_cat_cntr;
 extern
 #ifdef __cplusplus
 "C"
 #endif
-const char *_nl_expand_alias (const char *);],
-              [bindtextdomain ("", "");
-return * gettext ("")$gt_expression_test_code + _nl_msg_cat_cntr + *_nl_expand_alias ("")],
+const char *_nl_expand_alias (const char *);
+                 ]],
+                 [[
+bindtextdomain ("", "");
+return * gettext ("")$gt_expression_test_code + _nl_msg_cat_cntr + *_nl_expand_alias ("")
+                 ]])],
               [eval "$gt_func_gnugettext_libintl=yes"],
               [eval "$gt_func_gnugettext_libintl=no"])
             dnl Now see whether libintl exists and depends on libiconv.
             if { eval "gt_val=\$$gt_func_gnugettext_libintl"; test "$gt_val" != yes; } && test -n "$LIBICONV"; then
               LIBS="$LIBS $LIBICONV"
-              AC_TRY_LINK([#include <libintl.h>
+              AC_LINK_IFELSE(
+                [AC_LANG_PROGRAM(
+                   [[
+#include <libintl.h>
 $gt_revision_test_code
 extern int _nl_msg_cat_cntr;
 extern
 #ifdef __cplusplus
 "C"
 #endif
-const char *_nl_expand_alias (const char *);],
-                [bindtextdomain ("", "");
-return * gettext ("")$gt_expression_test_code + _nl_msg_cat_cntr + *_nl_expand_alias ("")],
-               [LIBINTL="$LIBINTL $LIBICONV"
-                LTLIBINTL="$LTLIBINTL $LTLIBICONV"
-                eval "$gt_func_gnugettext_libintl=yes"
-               ])
+const char *_nl_expand_alias (const char *);
+                   ]],
+                   [[
+bindtextdomain ("", "");
+return * gettext ("")$gt_expression_test_code + _nl_msg_cat_cntr + *_nl_expand_alias ("")
+                   ]])],
+                [LIBINTL="$LIBINTL $LIBICONV"
+                 LTLIBINTL="$LTLIBINTL $LTLIBICONV"
+                 eval "$gt_func_gnugettext_libintl=yes"
+                ])
             fi
             CPPFLAGS="$gt_save_CPPFLAGS"
             LIBS="$gt_save_LIBS"])
@@ -267,7 +287,7 @@ return * gettext ("")$gt_expression_test_code + _nl_msg_cat_cntr + *_nl_expand_a
 
     if test "$gt_use_preinstalled_gnugettext" = "yes" \
        || test "$nls_cv_use_gnu_gettext" = "yes"; then
-      AC_DEFINE(ENABLE_NLS, 1,
+      AC_DEFINE([ENABLE_NLS], [1],
         [Define to 1 if translation of program messages to the user's native language
    is requested.])
     else
@@ -301,9 +321,9 @@ return * gettext ("")$gt_expression_test_code + _nl_msg_cat_cntr + *_nl_expand_a
       fi
 
       dnl For backward compatibility. Some packages may be using this.
-      AC_DEFINE(HAVE_GETTEXT, 1,
+      AC_DEFINE([HAVE_GETTEXT], [1],
        [Define if the GNU gettext() function is already present or preinstalled.])
-      AC_DEFINE(HAVE_DCGETTEXT, 1,
+      AC_DEFINE([HAVE_DCGETTEXT], [1],
        [Define if the GNU dcgettext() function is already present or preinstalled.])
     fi
 
@@ -319,9 +339,9 @@ return * gettext ("")$gt_expression_test_code + _nl_msg_cat_cntr + *_nl_expand_a
     fi
 
     dnl Make all variables we use known to autoconf.
-    AC_SUBST(BUILD_INCLUDED_LIBINTL)
-    AC_SUBST(USE_INCLUDED_LIBINTL)
-    AC_SUBST(CATOBJEXT)
+    AC_SUBST([BUILD_INCLUDED_LIBINTL])
+    AC_SUBST([USE_INCLUDED_LIBINTL])
+    AC_SUBST([CATOBJEXT])
 
     dnl For backward compatibility. Some configure.ins may be using this.
     nls_cv_header_intl=
@@ -329,36 +349,36 @@ return * gettext ("")$gt_expression_test_code + _nl_msg_cat_cntr + *_nl_expand_a
 
     dnl For backward compatibility. Some Makefiles may be using this.
     DATADIRNAME=share
-    AC_SUBST(DATADIRNAME)
+    AC_SUBST([DATADIRNAME])
 
     dnl For backward compatibility. Some Makefiles may be using this.
     INSTOBJEXT=.mo
-    AC_SUBST(INSTOBJEXT)
+    AC_SUBST([INSTOBJEXT])
 
     dnl For backward compatibility. Some Makefiles may be using this.
     GENCAT=gencat
-    AC_SUBST(GENCAT)
+    AC_SUBST([GENCAT])
 
     dnl For backward compatibility. Some Makefiles may be using this.
     INTLOBJS=
     if test "$USE_INCLUDED_LIBINTL" = yes; then
       INTLOBJS="\$(GETTOBJS)"
     fi
-    AC_SUBST(INTLOBJS)
+    AC_SUBST([INTLOBJS])
 
     dnl Enable libtool support if the surrounding package wishes it.
     INTL_LIBTOOL_SUFFIX_PREFIX=gt_libtool_suffix_prefix
-    AC_SUBST(INTL_LIBTOOL_SUFFIX_PREFIX)
+    AC_SUBST([INTL_LIBTOOL_SUFFIX_PREFIX])
   ])
 
   dnl For backward compatibility. Some Makefiles may be using this.
   INTLLIBS="$LIBINTL"
-  AC_SUBST(INTLLIBS)
+  AC_SUBST([INTLLIBS])
 
   dnl Make all documented variables known to autoconf.
-  AC_SUBST(LIBINTL)
-  AC_SUBST(LTLIBINTL)
-  AC_SUBST(POSUB)
+  AC_SUBST([LIBINTL])
+  AC_SUBST([LTLIBINTL])
+  AC_SUBST([POSUB])
 ])
 
 
diff --git a/m4/gettime.m4 b/m4/gettime.m4
index 60d8ea1..e65455a 100644
--- a/m4/gettime.m4
+++ b/m4/gettime.m4
@@ -1,5 +1,5 @@
 # gettime.m4 serial 9
-dnl Copyright (C) 2002, 2004-2006, 2009-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2002, 2004-2006, 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.
diff --git a/m4/gettimeofday.m4 b/m4/gettimeofday.m4
index 5e2ef6f..578ed49 100644
--- a/m4/gettimeofday.m4
+++ b/m4/gettimeofday.m4
@@ -1,6 +1,6 @@
-# serial 26
+# serial 28
 
-# Copyright (C) 2001-2003, 2005, 2007, 2009-2019 Free Software Foundation, Inc.
+# Copyright (C) 2001-2003, 2005, 2007, 2009-2020 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.
@@ -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 "$host_os" in
-                       # Guess all is fine on glibc systems.
-        *-gnu* | gnu*) gl_cv_func_gettimeofday_clobber="guessing no" ;;
-                       # Guess all is fine on musl systems.
-        *-musl*)       gl_cv_func_gettimeofday_clobber="guessing no" ;;
-                       # Guess no on native Windows.
-        mingw*)        gl_cv_func_gettimeofday_clobber="guessing no" ;;
-                       # If we don't know, assume the worst.
-        *)             gl_cv_func_gettimeofday_clobber="guessing yes" ;;
-      esac
-     ])])
-
- case "$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/gl-openssl.m4 b/m4/gl-openssl.m4
index b93216e..e950904 100644
--- a/m4/gl-openssl.m4
+++ b/m4/gl-openssl.m4
@@ -1,5 +1,5 @@
-# gl-openssl.m4 serial 3
-dnl Copyright (C) 2013-2019 Free Software Foundation, Inc.
+# gl-openssl.m4 serial 5
+dnl Copyright (C) 2013-2020 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.
@@ -21,7 +21,9 @@ AC_DEFUN([gl_CRYPTO_CHECK],
   AC_ARG_WITH([openssl],
     [AS_HELP_STRING([--with-openssl],
       [use libcrypto hash routines. Valid ARGs are:
-       'yes', 'no', 'auto' => use if available,
+       'yes', 'no',
+       'auto' => use if any version available,
+       'auto-gpl-compat' => use if gpl compatible version available,
        'optional' => use if available and warn if not available;
        default is ']gl_CRYPTO_CHECK_DEFAULT['.
        Note also --with-linux-crypto, which will enable
@@ -29,19 +31,30 @@ AC_DEFUN([gl_CRYPTO_CHECK],
     [],
     [with_openssl=$with_openssl_default])
 
-  if test "x$1" = xMD5; then
-    ALG_header=md5.h
-  else
-    ALG_header=sha.h
-  fi
-
   AC_SUBST([LIB_CRYPTO])
   if test "x$with_openssl" != xno; then
-    AC_CHECK_LIB([crypto], [$1],
-      [AC_CHECK_HEADERS([openssl/$ALG_header],
-         [LIB_CRYPTO=-lcrypto
-          AC_DEFINE([HAVE_OPENSSL_$1], [1],
-            [Define to 1 if libcrypto is used for $1.])])])
+    if test "x$with_openssl" = xauto-gpl-compat; then
+      AC_CACHE_CHECK([whether openssl is GPL compatible],
+                     [gl_cv_openssl_gpl_compat],
+        [AC_COMPILE_IFELSE(
+           [AC_LANG_PROGRAM([[
+                #include <openssl/opensslv.h>
+                #if OPENSSL_VERSION_MAJOR < 3
+                  #error "openssl >= version 3 not found"
+                #endif
+              ]])],
+           [gl_cv_openssl_gpl_compat=yes],
+           [gl_cv_openssl_gpl_compat=no])])
+    fi
+    if test "x$with_openssl" != xauto-gpl-compat ||
+       test "x$gl_cv_openssl_gpl_compat" = xyes; then
+      AC_CHECK_LIB([crypto], [$1],
+        [AC_CHECK_HEADERS(
+           m4_if([$1], [MD5], [openssl/md5.h], [openssl/sha.h]),
+           [LIB_CRYPTO=-lcrypto
+            AC_DEFINE([HAVE_OPENSSL_$1], [1],
+              [Define to 1 if libcrypto is used for $1.])])])
+    fi
     if test "x$LIB_CRYPTO" = x; then
       if test "x$with_openssl" = xyes; then
         AC_MSG_ERROR([openssl development library not found for $1])
diff --git a/m4/glibc21.m4 b/m4/glibc21.m4
deleted file mode 100644
index 0ab0f23..0000000
--- a/m4/glibc21.m4
+++ /dev/null
@@ -1,34 +0,0 @@
-# glibc21.m4 serial 5
-dnl Copyright (C) 2000-2002, 2004, 2008, 2010-2019 Free Software Foundation,
-dnl Inc.
-dnl This file is free software; the Free Software Foundation
-dnl gives unlimited permission to copy and/or distribute it,
-dnl with or without modifications, as long as this notice is preserved.
-
-# Test for the GNU C Library, version 2.1 or newer, or uClibc.
-# From Bruno Haible.
-
-AC_DEFUN([gl_GLIBC21],
-  [
-    AC_CACHE_CHECK([whether we are using the GNU C Library >= 2.1 or uClibc],
-      [ac_cv_gnu_library_2_1],
-      [AC_EGREP_CPP([Lucky],
-        [
-#include <features.h>
-#ifdef __GNU_LIBRARY__
- #if (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 1) || (__GLIBC__ > 2)
-  Lucky GNU user
- #endif
-#endif
-#ifdef __UCLIBC__
- Lucky user
-#endif
-        ],
-        [ac_cv_gnu_library_2_1=yes],
-        [ac_cv_gnu_library_2_1=no])
-      ]
-    )
-    AC_SUBST([GLIBC21])
-    GLIBC21="$ac_cv_gnu_library_2_1"
-  ]
-)
diff --git a/m4/gnulib-common.m4 b/m4/gnulib-common.m4
index 57b94ed..2c0ae9b 100644
--- a/m4/gnulib-common.m4
+++ b/m4/gnulib-common.m4
@@ -1,5 +1,5 @@
-# gnulib-common.m4 serial 44
-dnl Copyright (C) 2007-2019 Free Software Foundation, Inc.
+# gnulib-common.m4 serial 63
+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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -12,20 +12,40 @@ AC_DEFUN([gl_COMMON], [
   dnl Use AC_REQUIRE here, so that the code is expanded once only.
   AC_REQUIRE([gl_00GNULIB])
   AC_REQUIRE([gl_COMMON_BODY])
+  AC_REQUIRE([gl_ZZGNULIB])
 ])
 AC_DEFUN([gl_COMMON_BODY], [
+  AH_VERBATIM([_GL_GNUC_PREREQ],
+[/* True if the compiler says it groks GNU C version MAJOR.MINOR.  */
+#if defined __GNUC__ && defined __GNUC_MINOR__
+# define _GL_GNUC_PREREQ(major, minor) \
+    ((major) < __GNUC__ + ((minor) <= __GNUC_MINOR__))
+#else
+# define _GL_GNUC_PREREQ(major, minor) 0
+#endif
+])
   AH_VERBATIM([_Noreturn],
 [/* The _Noreturn keyword of C11.  */
 #ifndef _Noreturn
 # if (defined __cplusplus \
       && ((201103 <= __cplusplus && !(__GNUC__ == 4 && __GNUC_MINOR__ == 7)) \
-          || (defined _MSC_VER && 1900 <= _MSC_VER)))
+          || (defined _MSC_VER && 1900 <= _MSC_VER)) \
+      && 0)
+    /* [[noreturn]] is not practically usable, because with it the syntax
+         extern _Noreturn void func (...);
+       would not be valid; such a declaration would only be valid with 'extern'
+       and '_Noreturn' swapped, or without the 'extern' keyword.  However, some
+       AIX system header files and several gnulib header files use precisely
+       this syntax with 'extern'.  */
 #  define _Noreturn [[noreturn]]
 # elif ((!defined __cplusplus || defined __clang__) \
         && (201112 <= (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0)  \
-            || 4 < __GNUC__ + (7 <= __GNUC_MINOR__)))
+            || _GL_GNUC_PREREQ (4, 7) \
+            || (defined __apple_build_version__ \
+                ? 6000000 <= __apple_build_version__ \
+                : 3 < __clang_major__ + (5 <= __clang_minor__))))
    /* _Noreturn works as-is.  */
-# elif 2 < __GNUC__ + (8 <= __GNUC_MINOR__) || 0x5110 <= __SUNPRO_C
+# elif _GL_GNUC_PREREQ (2, 8) || defined __clang__ || 0x5110 <= __SUNPRO_C
 #  define _Noreturn __attribute__ ((__noreturn__))
 # elif 1200 <= (defined _MSC_VER ? _MSC_VER : 0)
 #  define _Noreturn __declspec (noreturn)
@@ -44,48 +64,216 @@ AC_DEFUN([gl_COMMON_BODY], [
 #if defined __APPLE__ && defined __MACH__ && __APPLE_CC__ >= 5465 && !defined __cplusplus && __STDC_VERSION__ >= 199901L && !defined __GNUC_STDC_INLINE__
 # define __GNUC_STDC_INLINE__ 1
 #endif])
-  AH_VERBATIM([unused_parameter],
-[/* Define as a marker that can be attached to declarations that might not
-    be used.  This helps to reduce warnings, such as from
-    GCC -Wunused-parameter.  */
-#if __GNUC__ >= 3 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 7)
-# define _GL_UNUSED __attribute__ ((__unused__))
+  AH_VERBATIM([attribute],
+[/* Attributes.  */
+#ifdef __has_attribute
+# define _GL_HAS_ATTRIBUTE(attr) __has_attribute (__##attr##__)
 #else
-# define _GL_UNUSED
+# define _GL_HAS_ATTRIBUTE(attr) _GL_ATTR_##attr
+# define _GL_ATTR_alloc_size _GL_GNUC_PREREQ (4, 3)
+# define _GL_ATTR_always_inline _GL_GNUC_PREREQ (3, 2)
+# define _GL_ATTR_artificial _GL_GNUC_PREREQ (4, 3)
+# define _GL_ATTR_cold _GL_GNUC_PREREQ (4, 3)
+# define _GL_ATTR_const _GL_GNUC_PREREQ (2, 95)
+# define _GL_ATTR_deprecated _GL_GNUC_PREREQ (3, 1)
+# define _GL_ATTR_diagnose_if 0
+# define _GL_ATTR_error _GL_GNUC_PREREQ (4, 3)
+# define _GL_ATTR_externally_visible _GL_GNUC_PREREQ (4, 1)
+# define _GL_ATTR_fallthrough _GL_GNUC_PREREQ (7, 0)
+# define _GL_ATTR_format _GL_GNUC_PREREQ (2, 7)
+# define _GL_ATTR_leaf _GL_GNUC_PREREQ (4, 6)
+# ifdef _ICC
+#  define _GL_ATTR_may_alias 0
+# else
+#  define _GL_ATTR_may_alias _GL_GNUC_PREREQ (3, 3)
+# endif
+# define _GL_ATTR_malloc _GL_GNUC_PREREQ (3, 0)
+# define _GL_ATTR_noinline _GL_GNUC_PREREQ (3, 1)
+# define _GL_ATTR_nonnull _GL_GNUC_PREREQ (3, 3)
+# define _GL_ATTR_nonstring _GL_GNUC_PREREQ (8, 0)
+# define _GL_ATTR_nothrow _GL_GNUC_PREREQ (3, 3)
+# define _GL_ATTR_packed _GL_GNUC_PREREQ (2, 7)
+# define _GL_ATTR_pure _GL_GNUC_PREREQ (2, 96)
+# define _GL_ATTR_returns_nonnull _GL_GNUC_PREREQ (4, 9)
+# define _GL_ATTR_sentinel _GL_GNUC_PREREQ (4, 0)
+# define _GL_ATTR_unused _GL_GNUC_PREREQ (2, 7)
+# define _GL_ATTR_warn_unused_result _GL_GNUC_PREREQ (3, 4)
 #endif
-/* The name _UNUSED_PARAMETER_ is an earlier spelling, although the name
-   is a misnomer outside of parameter lists.  */
-#define _UNUSED_PARAMETER_ _GL_UNUSED
-
-/* gcc supports the "unused" attribute on possibly unused labels, and
-   g++ has since version 4.5.  Note to support C++ as well as C,
-   _GL_UNUSED_LABEL should be used with a trailing ;  */
-#if !defined __cplusplus || __GNUC__ > 4 \
-    || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)
-# define _GL_UNUSED_LABEL _GL_UNUSED
+
+]dnl There is no _GL_ATTRIBUTE_ALIGNED; use stdalign's _Alignas instead.
+[
+#if _GL_HAS_ATTRIBUTE (alloc_size)
+# define _GL_ATTRIBUTE_ALLOC_SIZE(args) __attribute__ ((__alloc_size__ args))
 #else
-# define _GL_UNUSED_LABEL
+# define _GL_ATTRIBUTE_ALLOC_SIZE(args)
 #endif
 
-/* The __pure__ attribute was added in gcc 2.96.  */
-#if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 96)
-# define _GL_ATTRIBUTE_PURE __attribute__ ((__pure__))
+#if _GL_HAS_ATTRIBUTE (always_inline)
+# define _GL_ATTRIBUTE_ALWAYS_INLINE __attribute__ ((__always_inline__))
+#else
+# define _GL_ATTRIBUTE_ALWAYS_INLINE
+#endif
+
+#if _GL_HAS_ATTRIBUTE (artificial)
+# define _GL_ATTRIBUTE_ARTIFICIAL __attribute__ ((__artificial__))
+#else
+# define _GL_ATTRIBUTE_ARTIFICIAL
+#endif
+
+/* Avoid __attribute__ ((cold)) on MinGW; see thread starting at
+   <https://lists.gnu.org/r/emacs-devel/2019-04/msg01152.html>.
+   Also, Oracle Studio 12.6 requires 'cold' not '__cold__'.  */
+#if _GL_HAS_ATTRIBUTE (cold) && !defined __MINGW32__
+# ifndef __SUNPRO_C
+#  define _GL_ATTRIBUTE_COLD __attribute__ ((__cold__))
+# else
+#  define _GL_ATTRIBUTE_COLD __attribute__ ((cold))
+# endif
 #else
-# define _GL_ATTRIBUTE_PURE /* empty */
+# define _GL_ATTRIBUTE_COLD
 #endif
 
-/* The __const__ attribute was added in gcc 2.95.  */
-#if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 95)
+#if _GL_HAS_ATTRIBUTE (const)
 # define _GL_ATTRIBUTE_CONST __attribute__ ((__const__))
 #else
-# define _GL_ATTRIBUTE_CONST /* empty */
+# define _GL_ATTRIBUTE_CONST
+#endif
+
+#if 201710L < __STDC_VERSION__
+# define _GL_ATTRIBUTE_DEPRECATED [[__deprecated__]]
+#elif _GL_HAS_ATTRIBUTE (deprecated)
+# define _GL_ATTRIBUTE_DEPRECATED __attribute__ ((__deprecated__))
+#else
+# define _GL_ATTRIBUTE_DEPRECATED
+#endif
+
+#if _GL_HAS_ATTRIBUTE (error)
+# define _GL_ATTRIBUTE_ERROR(msg) __attribute__ ((__error__ (msg)))
+# define _GL_ATTRIBUTE_WARNING(msg) __attribute__ ((__warning__ (msg)))
+#elif _GL_HAS_ATTRIBUTE (diagnose_if)
+# define _GL_ATTRIBUTE_ERROR(msg) __attribute__ ((__diagnose_if__ (1, msg, "error")))
+# define _GL_ATTRIBUTE_WARNING(msg) __attribute__ ((__diagnose_if__ (1, msg, "warning")))
+#else
+# define _GL_ATTRIBUTE_ERROR(msg)
+# define _GL_ATTRIBUTE_WARNING(msg)
+#endif
+
+#if _GL_HAS_ATTRIBUTE (externally_visible)
+# define _GL_ATTRIBUTE_EXTERNALLY_VISIBLE __attribute__ ((externally_visible))
+#else
+# define _GL_ATTRIBUTE_EXTERNALLY_VISIBLE
+#endif
+
+/* FALLTHROUGH is special, because it always expands to something.  */
+#if 201710L < __STDC_VERSION__
+# define _GL_ATTRIBUTE_FALLTHROUGH [[__fallthrough__]]
+#elif _GL_HAS_ATTRIBUTE (fallthrough)
+# define _GL_ATTRIBUTE_FALLTHROUGH __attribute__ ((__fallthrough__))
+#else
+# define _GL_ATTRIBUTE_FALLTHROUGH ((void) 0)
+#endif
+
+#if _GL_HAS_ATTRIBUTE (format)
+# define _GL_ATTRIBUTE_FORMAT(spec) __attribute__ ((__format__ spec))
+#else
+# define _GL_ATTRIBUTE_FORMAT(spec)
+#endif
+
+#if _GL_HAS_ATTRIBUTE (leaf)
+# define _GL_ATTRIBUTE_LEAF __attribute__ ((__leaf__))
+#else
+# define _GL_ATTRIBUTE_LEAF
+#endif
+
+/* Oracle Studio 12.6 mishandles may_alias despite __has_attribute OK.  */
+#if _GL_HAS_ATTRIBUTE (may_alias) && !defined __SUNPRO_C
+# define _GL_ATTRIBUTE_MAY_ALIAS __attribute__ ((__may_alias__))
+#else
+# define _GL_ATTRIBUTE_MAY_ALIAS
 #endif
 
-/* The __malloc__ attribute was added in gcc 3.  */
-#if 3 <= __GNUC__
+#if 201710L < __STDC_VERSION__
+# define _GL_ATTRIBUTE_MAYBE_UNUSED [[__maybe_unused__]]
+#elif _GL_HAS_ATTRIBUTE (unused)
+# define _GL_ATTRIBUTE_MAYBE_UNUSED __attribute__ ((__unused__))
+#else
+# define _GL_ATTRIBUTE_MAYBE_UNUSED
+#endif
+/* Earlier spellings of this macro.  */
+#define _GL_UNUSED _GL_ATTRIBUTE_MAYBE_UNUSED
+#define _UNUSED_PARAMETER_ _GL_ATTRIBUTE_MAYBE_UNUSED
+
+#if _GL_HAS_ATTRIBUTE (malloc)
 # define _GL_ATTRIBUTE_MALLOC __attribute__ ((__malloc__))
 #else
-# define _GL_ATTRIBUTE_MALLOC /* empty */
+# define _GL_ATTRIBUTE_MALLOC
+#endif
+
+#if 201710L < __STDC_VERSION__
+# define _GL_ATTRIBUTE_NODISCARD [[__nodiscard__]]
+#elif _GL_HAS_ATTRIBUTE (warn_unused_result)
+# define _GL_ATTRIBUTE_NODISCARD __attribute__ ((__warn_unused_result__))
+#else
+# define _GL_ATTRIBUTE_NODISCARD
+#endif
+
+#if _GL_HAS_ATTRIBUTE (noinline)
+# define _GL_ATTRIBUTE_NOINLINE __attribute__ ((__noinline__))
+#else
+# define _GL_ATTRIBUTE_NOINLINE
+#endif
+
+#if _GL_HAS_ATTRIBUTE (nonnull)
+# define _GL_ATTRIBUTE_NONNULL(args) __attribute__ ((__nonnull__ args))
+#else
+# define _GL_ATTRIBUTE_NONNULL(args)
+#endif
+
+#if _GL_HAS_ATTRIBUTE (nonstring)
+# define _GL_ATTRIBUTE_NONSTRING __attribute__ ((__nonstring__))
+#else
+# define _GL_ATTRIBUTE_NONSTRING
+#endif
+
+/* There is no _GL_ATTRIBUTE_NORETURN; use _Noreturn instead.  */
+
+#if _GL_HAS_ATTRIBUTE (nothrow) && !defined __cplusplus
+# define _GL_ATTRIBUTE_NOTHROW __attribute__ ((__nothrow__))
+#else
+# define _GL_ATTRIBUTE_NOTHROW
+#endif
+
+#if _GL_HAS_ATTRIBUTE (packed)
+# define _GL_ATTRIBUTE_PACKED __attribute__ ((__packed__))
+#else
+# define _GL_ATTRIBUTE_PACKED
+#endif
+
+#if _GL_HAS_ATTRIBUTE (pure)
+# define _GL_ATTRIBUTE_PURE __attribute__ ((__pure__))
+#else
+# define _GL_ATTRIBUTE_PURE
+#endif
+
+#if _GL_HAS_ATTRIBUTE (returns_nonnull)
+# define _GL_ATTRIBUTE_RETURNS_NONNULL __attribute__ ((__returns_nonnull__))
+#else
+# define _GL_ATTRIBUTE_RETURNS_NONNULL
+#endif
+
+#if _GL_HAS_ATTRIBUTE (sentinel)
+# define _GL_ATTRIBUTE_SENTINEL(pos) __attribute__ ((__sentinel__ pos))
+#else
+# define _GL_ATTRIBUTE_SENTINEL(pos)
+#endif
+
+]dnl There is no _GL_ATTRIBUTE_VISIBILITY; see m4/visibility.m4 instead.
+[
+/* To support C++ as well as C, use _GL_UNUSED_LABEL with trailing ';'.  */
+#if !defined __cplusplus || _GL_GNUC_PREREQ (4, 5)
+# define _GL_UNUSED_LABEL _GL_ATTRIBUTE_MAYBE_UNUSED
+#else
+# define _GL_UNUSED_LABEL
 #endif
 ])
   AH_VERBATIM([async_safe],
@@ -94,7 +282,7 @@ AC_DEFUN([gl_COMMON_BODY], [
    invoked from such signal handlers.  Such functions have some restrictions:
      * All functions that it calls should be marked _GL_ASYNC_SAFE as well,
        or should be listed as async-signal-safe in POSIX
-       <http://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html#tag_15_04>
+       <https://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html#tag_15_04>
        section 2.4.3.  Note that malloc(), sprintf(), and fwrite(), in
        particular, are NOT async-signal-safe.
      * All memory locations (variables and struct fields) that these functions
@@ -115,6 +303,49 @@ AC_DEFUN([gl_COMMON_BODY], [
        errno.  */
 #define _GL_ASYNC_SAFE
 ])
+  AH_VERBATIM([micro_optimizations],
+[/* _GL_CMP (n1, n2) performs a three-valued comparison on n1 vs. n2, where
+   n1 and n2 are expressions without side effects, that evaluate to real
+   numbers (excluding NaN).
+   It returns
+     1  if n1 > n2
+     0  if n1 == n2
+     -1 if n1 < n2
+   The naïve code   (n1 > n2 ? 1 : n1 < n2 ? -1 : 0)  produces a conditional
+   jump with nearly all GCC versions up to GCC 10.
+   This variant     (n1 < n2 ? -1 : n1 > n2)  produces a conditional with many
+   GCC versions up to GCC 9.
+   The better code  (n1 > n2) - (n1 < n2)  from Hacker's Delight § 2-9
+   avoids conditional jumps in all GCC versions >= 3.4.  */
+#define _GL_CMP(n1, n2) (((n1) > (n2)) - ((n1) < (n2)))
+])
+  dnl Hint which direction to take regarding cross-compilation guesses:
+  dnl When a user installs a program on a platform they are not intimately
+  dnl familiar with, --enable-cross-guesses=conservative is the appropriate
+  dnl choice.  It implements the "If we don't know, assume the worst" principle.
+  dnl However, when an operating system developer (on a platform which is not
+  dnl yet known to gnulib) builds packages for their platform, they want to
+  dnl expose, not hide, possible platform bugs; in this case,
+  dnl --enable-cross-guesses=risky is the appropriate choice.
+  dnl Sets the variables
+  dnl gl_cross_guess_normal    (to be used when 'yes' is good and 'no' is bad),
+  dnl gl_cross_guess_inverted  (to be used when 'no' is good and 'yes' is bad).
+  AC_ARG_ENABLE([cross-guesses],
+    [AS_HELP_STRING([--enable-cross-guesses={conservative|risky}],
+       [specify policy for cross-compilation guesses])],
+    [if test "x$enableval" != xconservative && test "x$enableval" != xrisky; then
+       AC_MSG_WARN([invalid argument supplied to --enable-cross-guesses])
+       enableval=conservative
+     fi
+     gl_cross_guesses="$enableval"],
+    [gl_cross_guesses=conservative])
+  if test $gl_cross_guesses = risky; then
+    gl_cross_guess_normal="guessing yes"
+    gl_cross_guess_inverted="guessing no"
+  else
+    gl_cross_guess_normal="guessing no"
+    gl_cross_guess_inverted="guessing yes"
+  fi
   dnl Preparation for running test programs:
   dnl Tell glibc to write diagnostics from -D_FORTIFY_SOURCE=2 to stderr, not
   dnl to /dev/tty, so they can be redirected to log files.  Such diagnostics
@@ -249,34 +480,20 @@ 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.
-# This is like AC_PROG_CC_C99, except that
-# - AC_PROG_CC_C99 does not mix well with AC_PROG_CC_STDC
-#   <https://lists.gnu.org/r/bug-gnulib/2011-09/msg00367.html>,
-#   but many more packages use AC_PROG_CC_STDC than AC_PROG_CC_C99
-#   <https://lists.gnu.org/r/bug-gnulib/2011-09/msg00441.html>.
-# Remaining problems:
-# - When AC_PROG_CC_STDC is invoked twice, it adds the C99 enabling options
-#   to CC twice
-#   <https://lists.gnu.org/r/bug-gnulib/2011-09/msg00431.html>.
-# - AC_PROG_CC_STDC is likely to change now that C11 is an ISO standard.
 AC_DEFUN([gl_PROG_CC_C99],
 [
-  dnl Change that version number to the minimum Autoconf version that supports
-  dnl mixing AC_PROG_CC_C99 calls with AC_PROG_CC_STDC calls.
-  m4_version_prereq([9.0],
-    [AC_REQUIRE([AC_PROG_CC_C99])],
-    [AC_REQUIRE([AC_PROG_CC_STDC])])
+  dnl Just use AC_PROG_CC_C99.
+  dnl When AC_PROG_CC_C99 and AC_PROG_CC_STDC are used together, the substituted
+  dnl value of CC will contain the C99 enabling options twice. But this is only
+  dnl a cosmetic problem.
+  dnl With Autoconf >= 2.70, use AC_PROG_CC since it implies AC_PROG_CC_C99;
+  dnl this avoids a "warning: The macro `AC_PROG_CC_C99' is obsolete."
+  m4_version_prereq([2.70],
+    [AC_REQUIRE([AC_PROG_CC])],
+    [AC_REQUIRE([AC_PROG_CC_C99])])
 ])
 
 # gl_PROG_AR_RANLIB
@@ -350,16 +567,16 @@ Amsterdam
 ])
 
 # AC_C_RESTRICT
-# This definition is copied from post-2.69 Autoconf and overrides the
-# AC_C_RESTRICT macro from autoconf 2.60..2.69.  It can be removed
-# once autoconf >= 2.70 can be assumed.  It's painful to check version
-# numbers, and in practice this macro is more up-to-date than Autoconf
-# is, so override Autoconf unconditionally.
+# This definition is copied from post-2.70 Autoconf and overrides the
+# AC_C_RESTRICT macro from autoconf 2.60..2.70.
+m4_version_prereq([2.70.1], [], [
 AC_DEFUN([AC_C_RESTRICT],
 [AC_CACHE_CHECK([for C/C++ restrict keyword], [ac_cv_c_restrict],
   [ac_cv_c_restrict=no
-   # The order here caters to the fact that C++ does not require restrict.
-   for ac_kw in __restrict __restrict__ _Restrict restrict; do
+   # Put '__restrict__' first, to avoid problems with glibc and non-GCC; see:
+   # https://lists.gnu.org/archive/html/bug-autoconf/2016-02/msg00006.html
+   # Put 'restrict' last, because C++ lacks it.
+   for ac_kw in __restrict__ __restrict _Restrict restrict; do
      AC_COMPILE_IFELSE(
       [AC_LANG_PROGRAM(
          [[typedef int *int_ptr;
@@ -379,14 +596,15 @@ AC_DEFUN([AC_C_RESTRICT],
  AH_VERBATIM([restrict],
 [/* Define to the equivalent of the C99 'restrict' keyword, or to
    nothing if this is not supported.  Do not define if restrict is
-   supported directly.  */
+   supported only directly.  */
 #undef restrict
-/* Work around a bug in Sun C++: it does not support _Restrict or
-   __restrict__, even though the corresponding Sun C compiler ends up with
-   "#define restrict _Restrict" or "#define restrict __restrict__" in the
-   previous line.  Perhaps some future version of Sun C++ will work with
-   restrict; if so, hopefully it defines __RESTRICT like Sun C does.  */
-#if defined __SUNPRO_CC && !defined __RESTRICT
+/* Work around a bug in older versions of Sun C++, which did not
+   #define __restrict__ or support _Restrict or __restrict__
+   even though the corresponding Sun C compiler ended up with
+   "#define restrict _Restrict" or "#define restrict __restrict__"
+   in the previous line.  This workaround can be removed once
+   we assume Oracle Developer Studio 12.5 (2016) or later.  */
+#if defined __SUNPRO_CC && !defined __RESTRICT && !defined __restrict__
 # define _Restrict
 # define __restrict__
 #endif])
@@ -396,6 +614,7 @@ AC_DEFUN([AC_C_RESTRICT],
    *)  AC_DEFINE_UNQUOTED([restrict], [$ac_cv_c_restrict]) ;;
  esac
 ])# AC_C_RESTRICT
+])
 
 # gl_BIGENDIAN
 # is like AC_C_BIGENDIAN, except that it can be AC_REQUIREd.
@@ -406,6 +625,22 @@ AC_DEFUN([gl_BIGENDIAN],
   AC_C_BIGENDIAN
 ])
 
+# A temporary file descriptor.
+# Must be less than 10, because dash 0.5.8 does not support redirections
+# with multi-digit file descriptors.
+m4_define([GL_TMP_FD], 9)
+
+# gl_SILENT(command)
+# executes command, but without the normal configure output.
+# This is useful when you want to invoke AC_CACHE_CHECK (or AC_CHECK_FUNC etc.)
+# inside another AC_CACHE_CHECK.
+AC_DEFUN([gl_SILENT],
+[
+  exec GL_TMP_FD>&AS_MESSAGE_FD AS_MESSAGE_FD>/dev/null
+  $1
+  exec AS_MESSAGE_FD>&GL_TMP_FD GL_TMP_FD>&-
+])
+
 # gl_CACHE_VAL_SILENT(cache-id, command-to-set-it)
 # is like AC_CACHE_VAL(cache-id, command-to-set-it), except that it does not
 # output a spurious "(cached)" mark in the midst of other configure output.
@@ -413,12 +648,77 @@ AC_DEFUN([gl_BIGENDIAN],
 # by an AC_MSG_CHECKING/AC_MSG_RESULT pair.
 AC_DEFUN([gl_CACHE_VAL_SILENT],
 [
-  saved_as_echo_n="$as_echo_n"
-  as_echo_n=':'
-  AC_CACHE_VAL([$1], [$2])
-  as_echo_n="$saved_as_echo_n"
+  gl_SILENT([
+    AC_CACHE_VAL([$1], [$2])
+  ])
 ])
 
-# 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/gnulib-comp.m4 b/m4/gnulib-comp.m4
index 870e706..6032dcd 100644
--- a/m4/gnulib-comp.m4
+++ b/m4/gnulib-comp.m4
@@ -1,5 +1,5 @@
 # DO NOT EDIT! GENERATED AUTOMATICALLY!
-# Copyright (C) 2002-2019 Free Software Foundation, Inc.
+# Copyright (C) 2002-2020 Free Software Foundation, Inc.
 #
 # This file is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -45,14 +45,20 @@ AC_DEFUN([gl_EARLY],
   AC_REQUIRE([AM_PROG_CC_C_O])
   # Code from module absolute-header:
   # Code from module accept:
+  # Code from module access:
   # Code from module alloca:
   # Code from module alloca-opt:
   # Code from module announce-gen:
   # Code from module arpa_inet:
   # Code from module array-mergesort:
+  # Code from module assure:
+  # Code from module at-internal:
+  # Code from module attribute:
   # Code from module base32:
+  # Code from module basename-lgpl:
   # Code from module binary-io:
   # Code from module bind:
+  # Code from module bitrotate:
   # Code from module btowc:
   # Code from module builtin-expect:
   # Code from module byteswap:
@@ -61,9 +67,14 @@ AC_DEFUN([gl_EARLY],
   # Code from module c-strcaseeq:
   # Code from module c-strcasestr:
   # Code from module c99:
+  # Code from module canonicalize:
+  # Code from module chdir:
+  # Code from module chdir-long:
   # Code from module clock-time:
   # Code from module cloexec:
   # Code from module close:
+  # Code from module closedir:
+  # Code from module concat-filename:
   # Code from module connect:
   # Code from module crypto/af_alg:
   # Code from module crypto/md2:
@@ -76,10 +87,14 @@ AC_DEFUN([gl_EARLY],
   # Code from module crypto/sha256-buffer:
   # Code from module crypto/sha512:
   # Code from module crypto/sha512-buffer:
+  # Code from module ctype:
+  # Code from module d-ino:
+  # Code from module dirent:
+  # Code from module dirfd:
   # Code from module dirname:
   # Code from module dirname-lgpl:
-  # Code from module dosname:
   # Code from module double-slash-root:
+  # Code from module dup:
   # Code from module dup2:
   # Code from module environ:
   # Code from module errno:
@@ -88,30 +103,41 @@ AC_DEFUN([gl_EARLY],
   # Code from module extensions:
   # Code from module extern-inline:
   # Code from module fatal-signal:
+  # Code from module fchdir:
   # Code from module fcntl:
   # Code from module fcntl-h:
   # Code from module fd-hook:
   # Code from module fd-safer-flag:
+  # Code from module fdopendir:
   # Code from module fflush:
-  AC_REQUIRE([AC_FUNC_FSEEKO])
+  AC_REQUIRE([gl_SET_LARGEFILE_SOURCE])
+  # Code from module file-set:
   # Code from module filename:
+  # Code from module filenamecat-lgpl:
+  # Code from module findprog-in:
   # Code from module flexmember:
   # Code from module float:
   # Code from module flock:
   # Code from module fnmatch:
+  # Code from module fnmatch-gnu:
   # Code from module fnmatch-h:
   # Code from module fopen:
+  # Code from module fopen-gnu:
   # Code from module fpurge:
   # Code from module freading:
+  # Code from module free-posix:
   # Code from module fseek:
   # Code from module fseeko:
-  AC_REQUIRE([AC_FUNC_FSEEKO])
+  AC_REQUIRE([gl_SET_LARGEFILE_SOURCE])
   # Code from module fstat:
+  # Code from module fstatat:
   # Code from module ftell:
   # Code from module ftello:
-  AC_REQUIRE([AC_FUNC_FSEEKO])
+  AC_REQUIRE([gl_SET_LARGEFILE_SOURCE])
   # Code from module futimens:
   # Code from module getaddrinfo:
+  # Code from module getcwd:
+  # Code from module getcwd-lgpl:
   # Code from module getdelim:
   # Code from module getdtablesize:
   # Code from module getgroups:
@@ -122,6 +148,7 @@ AC_DEFUN([gl_EARLY],
   # Code from module getpass-gnu:
   # Code from module getpeername:
   # Code from module getprogname:
+  # Code from module getrandom:
   # Code from module getsockname:
   # Code from module gettext-h:
   # Code from module gettime:
@@ -133,10 +160,14 @@ AC_DEFUN([gl_EARLY],
   # Code from module gperf:
   # Code from module group-member:
   # Code from module hard-locale:
+  # Code from module hash:
+  # Code from module hash-pjw:
+  # Code from module hash-triple-simple:
   # Code from module havelib:
   # Code from module hostent:
   # Code from module iconv:
   # Code from module iconv-h:
+  # Code from module idx:
   # Code from module include_next:
   # Code from module inet_ntop:
   # Code from module inline:
@@ -144,7 +175,10 @@ AC_DEFUN([gl_EARLY],
   # Code from module inttypes:
   # Code from module inttypes-incomplete:
   # Code from module ioctl:
+  # Code from module isblank:
   # Code from module iswblank:
+  # Code from module iswdigit:
+  # Code from module iswxdigit:
   # Code from module langinfo:
   # Code from module largefile:
   AC_REQUIRE([AC_SYS_LARGEFILE])
@@ -156,7 +190,6 @@ AC_DEFUN([gl_EARLY],
   # Code from module localcharset:
   # Code from module locale:
   # Code from module localeconv:
-  # Code from module localtime-buffer:
   # Code from module lock:
   # Code from module lseek:
   # Code from module lstat:
@@ -170,6 +203,7 @@ AC_DEFUN([gl_EARLY],
   # Code from module mbsrtowcs:
   # Code from module mbtowc:
   # Code from module memchr:
+  # Code from module mempcpy:
   # Code from module memrchr:
   # Code from module minmax:
   # Code from module mkdir:
@@ -186,12 +220,17 @@ AC_DEFUN([gl_EARLY],
   # Code from module nl_langinfo:
   # Code from module nocrash:
   # Code from module open:
+  # Code from module openat:
+  # Code from module openat-die:
+  # Code from module openat-h:
+  # Code from module opendir:
   # Code from module pathmax:
   # Code from module pipe-posix:
   # Code from module pipe2:
   # Code from module pipe2-safer:
   # Code from module posix_spawn:
   # Code from module posix_spawn-internal:
+  # Code from module posix_spawn_file_actions_addchdir:
   # Code from module posix_spawn_file_actions_addclose:
   # Code from module posix_spawn_file_actions_adddup2:
   # Code from module posix_spawn_file_actions_addopen:
@@ -200,6 +239,7 @@ AC_DEFUN([gl_EARLY],
   # Code from module posix_spawnattr_destroy:
   # Code from module posix_spawnattr_init:
   # Code from module posix_spawnattr_setflags:
+  # Code from module posix_spawnattr_setpgroup:
   # Code from module posix_spawnattr_setsigmask:
   # Code from module posix_spawnp:
   # Code from module quote:
@@ -207,13 +247,21 @@ AC_DEFUN([gl_EARLY],
   # Code from module quotearg-simple:
   # Code from module raise:
   # Code from module rawmemchr:
+  # Code from module readdir:
+  # Code from module readlink:
+  # Code from module realloc-posix:
   # Code from module recv:
   # Code from module regex:
+  # Code from module rewinddir:
+  # Code from module same-inode:
+  # Code from module save-cwd:
   # Code from module sched:
+  # Code from module scratch_buffer:
   # Code from module secure_getenv:
   # Code from module select:
   # Code from module send:
   # Code from module servent:
+  # Code from module setlocale-null:
   # Code from module setsockopt:
   # Code from module sh-filename:
   # Code from module sigaction:
@@ -243,6 +291,7 @@ AC_DEFUN([gl_EARLY],
   # Code from module stdint:
   # Code from module stdio:
   # Code from module stdlib:
+  # Code from module stpcpy:
   # Code from module strcase:
   # Code from module strchrnul:
   # Code from module strdup-posix:
@@ -263,6 +312,7 @@ AC_DEFUN([gl_EARLY],
   # Code from module symlink:
   # Code from module sys_file:
   # Code from module sys_ioctl:
+  # Code from module sys_random:
   # Code from module sys_select:
   # Code from module sys_socket:
   # Code from module sys_stat:
@@ -271,6 +321,7 @@ AC_DEFUN([gl_EARLY],
   # Code from module sys_uio:
   # Code from module sys_wait:
   # Code from module tempname:
+  # Code from module thread-optim:
   # Code from module threadlib:
   gl_THREADLIB_EARLY
   # Code from module time:
@@ -318,10 +369,18 @@ AC_DEFUN([gl_EARLY],
   # Code from module vsnprintf:
   # Code from module wait-process:
   # Code from module waitpid:
+  # Code from module warnings:
   # Code from module wchar:
   # Code from module wcrtomb:
   # Code from module wctype-h:
   # Code from module wcwidth:
+  # Code from module windows-mutex:
+  # Code from module windows-once:
+  # Code from module windows-recmutex:
+  # Code from module windows-rwlock:
+  # Code from module windows-spawn:
+  # Code from module wmemchr:
+  # Code from module wmempcpy:
   # Code from module write:
   # Code from module xalloc:
   # Code from module xalloc-die:
@@ -352,9 +411,15 @@ AC_DEFUN([gl_INIT],
     AC_LIBOBJ([accept])
   fi
   gl_SYS_SOCKET_MODULE_INDICATOR([accept])
+  gl_FUNC_ACCESS
+  if test $REPLACE_ACCESS = 1; then
+    AC_LIBOBJ([access])
+  fi
+  gl_UNISTD_MODULE_INDICATOR([access])
   gl_FUNC_ALLOCA
   gl_HEADER_ARPA_INET
   AC_PROG_MKDIR_P
+  AC_REQUIRE([AC_CANONICAL_HOST])
   gl_FUNC_BASE32
   AC_REQUIRE([gl_HEADER_SYS_SOCKET])
   if test "$ac_cv_header_winsock2_h" = yes; then
@@ -369,6 +434,16 @@ AC_DEFUN([gl_INIT],
   gl_WCHAR_MODULE_INDICATOR([btowc])
   gl___BUILTIN_EXPECT
   gl_BYTESWAP
+  gl_FUNC_CANONICALIZE_FILENAME_MODE
+  gl_MODULE_INDICATOR([canonicalize])
+  gl_MODULE_INDICATOR_FOR_TESTS([canonicalize])
+  gl_STDLIB_MODULE_INDICATOR([canonicalize_file_name])
+  gl_UNISTD_MODULE_INDICATOR([chdir])
+  gl_FUNC_CHDIR_LONG
+  if test $gl_cv_have_unlimited_file_name_length = no; then
+    AC_LIBOBJ([chdir-long])
+    gl_PREREQ_CHDIR_LONG
+  fi
   gl_CLOCK_TIME
   gl_MODULE_INDICATOR_FOR_TESTS([cloexec])
   gl_FUNC_CLOSE
@@ -376,27 +451,52 @@ AC_DEFUN([gl_INIT],
     AC_LIBOBJ([close])
   fi
   gl_UNISTD_MODULE_INDICATOR([close])
+  gl_FUNC_CLOSEDIR
+  if test $HAVE_CLOSEDIR = 0 || test $REPLACE_CLOSEDIR = 1; then
+    AC_LIBOBJ([closedir])
+  fi
+  gl_DIRENT_MODULE_INDICATOR([closedir])
   AC_REQUIRE([gl_HEADER_SYS_SOCKET])
   if test "$ac_cv_header_winsock2_h" = yes; then
     AC_LIBOBJ([connect])
   fi
   gl_SYS_SOCKET_MODULE_INDICATOR([connect])
   gl_AF_ALG
+  AC_REQUIRE([AC_C_RESTRICT])
+  AC_REQUIRE([AC_C_RESTRICT])
   gl_MD4
   AC_DEFINE([GL_COMPILE_CRYPTO_STREAM], 1, [Compile Gnulib crypto stream ops.])
+  AC_REQUIRE([AC_C_RESTRICT])
   gl_MD5
   AC_DEFINE([GL_COMPILE_CRYPTO_STREAM], 1, [Compile Gnulib crypto stream ops.])
+  AC_REQUIRE([AC_C_RESTRICT])
   gl_SHA1
   AC_DEFINE([GL_COMPILE_CRYPTO_STREAM], 1, [Compile Gnulib crypto stream ops.])
+  AC_REQUIRE([AC_C_RESTRICT])
   gl_SHA256
   AC_DEFINE([GL_COMPILE_CRYPTO_STREAM], 1, [Compile Gnulib crypto stream ops.])
+  AC_REQUIRE([AC_C_RESTRICT])
   gl_SHA512
-  gl_DIRNAME
+  gl_CTYPE_H
+  gl_CHECK_TYPE_STRUCT_DIRENT_D_INO
+  gl_DIRENT_H
+  gl_FUNC_DIRFD
+  if test $ac_cv_func_dirfd = no && test $gl_cv_func_dirfd_macro = no \
+     || test $REPLACE_DIRFD = 1; then
+    AC_LIBOBJ([dirfd])
+    gl_PREREQ_DIRFD
+  fi
+  gl_DIRENT_MODULE_INDICATOR([dirfd])
   gl_MODULE_INDICATOR([dirname])
-  gl_DIRNAME_LGPL
   gl_DOUBLE_SLASH_ROOT
+  gl_FUNC_DUP
+  if test $REPLACE_DUP = 1; then
+    AC_LIBOBJ([dup])
+    gl_PREREQ_DUP
+  fi
+  gl_UNISTD_MODULE_INDICATOR([dup])
   gl_FUNC_DUP2
-  if test $HAVE_DUP2 = 0 || test $REPLACE_DUP2 = 1; then
+  if test $REPLACE_DUP2 = 1; then
     AC_LIBOBJ([dup2])
     gl_PREREQ_DUP2
   fi
@@ -414,6 +514,8 @@ AC_DEFUN([gl_INIT],
      AM_][XGETTEXT_OPTION([--flag=error_at_line:5:c-format])])
   AC_REQUIRE([gl_EXTERN_INLINE])
   gl_FATAL_SIGNAL
+  gl_FUNC_FCHDIR
+  gl_UNISTD_MODULE_INDICATOR([fchdir])
   gl_FUNC_FCNTL
   if test $HAVE_FCNTL = 0 || test $REPLACE_FCNTL = 1; then
     AC_LIBOBJ([fcntl])
@@ -421,6 +523,12 @@ AC_DEFUN([gl_INIT],
   gl_FCNTL_MODULE_INDICATOR([fcntl])
   gl_FCNTL_H
   gl_MODULE_INDICATOR([fd-safer-flag])
+  gl_FUNC_FDOPENDIR
+  if test $HAVE_FDOPENDIR = 0 || test $REPLACE_FDOPENDIR = 1; then
+    AC_LIBOBJ([fdopendir])
+  fi
+  gl_DIRENT_MODULE_INDICATOR([fdopendir])
+  gl_MODULE_INDICATOR([fdopendir])
   gl_FUNC_FFLUSH
   if test $REPLACE_FFLUSH = 1; then
     AC_LIBOBJ([fflush])
@@ -428,6 +536,8 @@ AC_DEFUN([gl_INIT],
   fi
   gl_MODULE_INDICATOR([fflush])
   gl_STDIO_MODULE_INDICATOR([fflush])
+  gl_FILE_NAME_CONCAT_LGPL
+  gl_FINDPROG_IN
   AC_C_FLEXIBLE_ARRAY_MEMBER
   gl_FLOAT_H
   if test $REPLACE_FLOAT_LDBL = 1; then
@@ -448,6 +558,12 @@ AC_DEFUN([gl_INIT],
     gl_PREREQ_FNMATCH
   fi
   gl_FNMATCH_MODULE_INDICATOR([fnmatch])
+  gl_FUNC_FNMATCH_GNU
+  if test $HAVE_FNMATCH = 0 || test $REPLACE_FNMATCH = 1; then
+    AC_LIBOBJ([fnmatch])
+    gl_PREREQ_FNMATCH
+  fi
+  gl_MODULE_INDICATOR([fnmatch-gnu])
   gl_FNMATCH_H
   gl_FUNC_FOPEN
   if test $REPLACE_FOPEN = 1; then
@@ -455,12 +571,24 @@ AC_DEFUN([gl_INIT],
     gl_PREREQ_FOPEN
   fi
   gl_STDIO_MODULE_INDICATOR([fopen])
+  gl_FUNC_FOPEN_GNU
+  if test $REPLACE_FOPEN = 1; then
+    AC_LIBOBJ([fopen])
+    gl_PREREQ_FOPEN
+  fi
+  gl_MODULE_INDICATOR([fopen-gnu])
   gl_FUNC_FPURGE
   if test $HAVE_FPURGE = 0 || test $REPLACE_FPURGE = 1; then
     AC_LIBOBJ([fpurge])
   fi
   gl_STDIO_MODULE_INDICATOR([fpurge])
   gl_FUNC_FREADING
+  gl_FUNC_FREE
+  if test $REPLACE_FREE = 1; then
+    AC_LIBOBJ([free])
+    gl_PREREQ_FREE
+  fi
+  gl_STDLIB_MODULE_INDICATOR([free-posix])
   gl_FUNC_FSEEK
   if test $REPLACE_FSEEK = 1; then
     AC_LIBOBJ([fseek])
@@ -483,6 +611,11 @@ AC_DEFUN([gl_INIT],
     gl_PREREQ_FSTAT
   fi
   gl_SYS_STAT_MODULE_INDICATOR([fstat])
+  gl_FUNC_FSTATAT
+  if test $HAVE_FSTATAT = 0 || test $REPLACE_FSTATAT = 1; then
+    AC_LIBOBJ([fstatat])
+  fi
+  gl_SYS_STAT_MODULE_INDICATOR([fstatat])
   gl_FUNC_FTELL
   if test $REPLACE_FTELL = 1; then
     AC_LIBOBJ([ftell])
@@ -500,13 +633,25 @@ AC_DEFUN([gl_INIT],
   fi
   gl_SYS_STAT_MODULE_INDICATOR([futimens])
   gl_GETADDRINFO
-  if test $HAVE_GETADDRINFO = 0; then
+  if test $HAVE_GETADDRINFO = 0 || test $REPLACE_GETADDRINFO = 1; then
     AC_LIBOBJ([getaddrinfo])
   fi
   if test $HAVE_DECL_GAI_STRERROR = 0 || test $REPLACE_GAI_STRERROR = 1; then
     AC_LIBOBJ([gai_strerror])
   fi
   gl_NETDB_MODULE_INDICATOR([getaddrinfo])
+  gl_FUNC_GETCWD
+  if test $REPLACE_GETCWD = 1; then
+    AC_LIBOBJ([getcwd])
+    gl_PREREQ_GETCWD
+  fi
+  gl_MODULE_INDICATOR([getcwd])
+  gl_UNISTD_MODULE_INDICATOR([getcwd])
+  gl_FUNC_GETCWD_LGPL
+  if test $REPLACE_GETCWD = 1; then
+    AC_LIBOBJ([getcwd-lgpl])
+  fi
+  gl_UNISTD_MODULE_INDICATOR([getcwd])
   gl_FUNC_GETDELIM
   if test $HAVE_GETDELIM = 0 || test $REPLACE_GETDELIM = 1; then
     AC_LIBOBJ([getdelim])
@@ -542,6 +687,7 @@ AC_DEFUN([gl_INIT],
     GNULIB_GL_UNISTD_H_GETOPT=1
   fi
   AC_SUBST([GNULIB_GL_UNISTD_H_GETOPT])
+  gl_UNISTD_MODULE_INDICATOR([getopt-posix])
   gl_FUNC_GETPASS
   if test $HAVE_GETPASS = 0 || test $REPLACE_GETPASS = 1; then
     AC_LIBOBJ([getpass])
@@ -560,6 +706,12 @@ AC_DEFUN([gl_INIT],
   fi
   gl_SYS_SOCKET_MODULE_INDICATOR([getpeername])
   gl_FUNC_GETPROGNAME
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  gl_FUNC_GETRANDOM
+  if test $HAVE_GETRANDOM = 0 || test $REPLACE_GETRANDOM = 1; then
+    AC_LIBOBJ([getrandom])
+  fi
+  gl_SYS_RANDOM_MODULE_INDICATOR([getrandom])
   AC_REQUIRE([gl_HEADER_SYS_SOCKET])
   if test "$ac_cv_header_winsock2_h" = yes; then
     AC_LIBOBJ([getsockname])
@@ -590,6 +742,10 @@ AC_DEFUN([gl_INIT],
     gl_PREREQ_GROUP_MEMBER
   fi
   gl_UNISTD_MODULE_INDICATOR([group-member])
+  AC_REQUIRE([gl_FUNC_SETLOCALE_NULL])
+  LIB_HARD_LOCALE="$LIB_SETLOCALE_NULL"
+  AC_SUBST([LIB_HARD_LOCALE])
+  AC_DEFUN([gl_HAVE_MODULE_HAVELIB])
   gl_HOSTENT
   AM_ICONV
   m4_ifdef([gl_ICONV_MODULE_INDICATOR],
@@ -609,6 +765,12 @@ AC_DEFUN([gl_INIT],
     AC_LIBOBJ([ioctl])
   fi
   gl_SYS_IOCTL_MODULE_INDICATOR([ioctl])
+  gl_FUNC_ISBLANK
+  if test $HAVE_ISBLANK = 0; then
+    AC_LIBOBJ([isblank])
+  fi
+  gl_MODULE_INDICATOR([isblank])
+  gl_CTYPE_MODULE_INDICATOR([isblank])
   gl_FUNC_ISWBLANK
   if test $HAVE_ISWCNTRL = 0 || test $REPLACE_ISWCNTRL = 1; then
     :
@@ -618,6 +780,24 @@ AC_DEFUN([gl_INIT],
     fi
   fi
   gl_WCTYPE_MODULE_INDICATOR([iswblank])
+  gl_FUNC_ISWDIGIT
+  if test $HAVE_ISWCNTRL = 0 || test $REPLACE_ISWCNTRL = 1; then
+    :
+  else
+    if test $REPLACE_ISWDIGIT = 1; then
+      AC_LIBOBJ([iswdigit])
+    fi
+  fi
+  gl_WCTYPE_MODULE_INDICATOR([iswdigit])
+  gl_FUNC_ISWXDIGIT
+  if test $HAVE_ISWCNTRL = 0 || test $REPLACE_ISWCNTRL = 1; then
+    :
+  else
+    if test $REPLACE_ISWXDIGIT = 1; then
+      AC_LIBOBJ([iswxdigit])
+    fi
+  fi
+  gl_WCTYPE_MODULE_INDICATOR([iswxdigit])
   gl_LANGINFO_H
   AC_REQUIRE([gl_LARGEFILE])
   gl___INLINE
@@ -644,8 +824,6 @@ AC_DEFUN([gl_INIT],
     gl_PREREQ_LOCALECONV
   fi
   gl_LOCALE_MODULE_INDICATOR([localeconv])
-  AC_REQUIRE([gl_LOCALTIME_BUFFER_DEFAULTS])
-  AC_LIBOBJ([localtime-buffer])
   gl_LOCK
   gl_MODULE_INDICATOR([lock])
   gl_FUNC_LSEEK
@@ -674,6 +852,11 @@ AC_DEFUN([gl_INIT],
   gl_FUNC_MBRTOWC
   if test $HAVE_MBRTOWC = 0 || test $REPLACE_MBRTOWC = 1; then
     AC_LIBOBJ([mbrtowc])
+    if test $REPLACE_MBSTATE_T = 1; then
+      AC_LIBOBJ([lc-charset-dispatch])
+      AC_LIBOBJ([mbtowc-lock])
+      gl_PREREQ_MBTOWC_LOCK
+    fi
     gl_PREREQ_MBRTOWC
   fi
   gl_WCHAR_MODULE_INDICATOR([mbrtowc])
@@ -697,11 +880,17 @@ AC_DEFUN([gl_INIT],
   fi
   gl_STDLIB_MODULE_INDICATOR([mbtowc])
   gl_FUNC_MEMCHR
-  if test $HAVE_MEMCHR = 0 || test $REPLACE_MEMCHR = 1; then
+  if test $REPLACE_MEMCHR = 1; then
     AC_LIBOBJ([memchr])
     gl_PREREQ_MEMCHR
   fi
   gl_STRING_MODULE_INDICATOR([memchr])
+  gl_FUNC_MEMPCPY
+  if test $HAVE_MEMPCPY = 0; then
+    AC_LIBOBJ([mempcpy])
+    gl_PREREQ_MEMPCPY
+  fi
+  gl_STRING_MODULE_INDICATOR([mempcpy])
   gl_FUNC_MEMRCHR
   if test $ac_cv_func_memrchr = no; then
     AC_LIBOBJ([memrchr])
@@ -713,6 +902,7 @@ AC_DEFUN([gl_INIT],
   if test $REPLACE_MKDIR = 1; then
     AC_LIBOBJ([mkdir])
   fi
+  gl_SYS_STAT_MODULE_INDICATOR([mkdir])
   gl_FUNC_MKOSTEMP
   if test $HAVE_MKOSTEMP = 0; then
     AC_LIBOBJ([mkostemp])
@@ -760,6 +950,10 @@ AC_DEFUN([gl_INIT],
   if test $HAVE_NL_LANGINFO = 0 || test $REPLACE_NL_LANGINFO = 1; then
     AC_LIBOBJ([nl_langinfo])
   fi
+  if test $REPLACE_NL_LANGINFO = 1 && test $NL_LANGINFO_MTSAFE = 0; then
+    AC_LIBOBJ([nl_langinfo-lock])
+    gl_PREREQ_NL_LANGINFO_LOCK
+  fi
   gl_LANGINFO_MODULE_INDICATOR([nl_langinfo])
   gl_FUNC_OPEN
   if test $REPLACE_OPEN = 1; then
@@ -767,6 +961,18 @@ AC_DEFUN([gl_INIT],
     gl_PREREQ_OPEN
   fi
   gl_FCNTL_MODULE_INDICATOR([open])
+  gl_FUNC_OPENAT
+  if test $HAVE_OPENAT = 0 || test $REPLACE_OPENAT = 1; then
+    AC_LIBOBJ([openat])
+    gl_PREREQ_OPENAT
+  fi
+  gl_MODULE_INDICATOR([openat]) dnl for lib/getcwd.c
+  gl_FCNTL_MODULE_INDICATOR([openat])
+  gl_FUNC_OPENDIR
+  if test $HAVE_OPENDIR = 0 || test $REPLACE_OPENDIR = 1; then
+    AC_LIBOBJ([opendir])
+  fi
+  gl_DIRENT_MODULE_INDICATOR([opendir])
   gl_PATHMAX
   gl_FUNC_PIPE
   if test $HAVE_PIPE = 0; then
@@ -779,10 +985,18 @@ AC_DEFUN([gl_INIT],
   gl_POSIX_SPAWN
   if test $HAVE_POSIX_SPAWN = 0 || test $REPLACE_POSIX_SPAWN = 1; then
     AC_LIBOBJ([spawn])
+  fi
+  gl_SPAWN_MODULE_INDICATOR([posix_spawn])
+  gl_POSIX_SPAWN
+  if test $HAVE_POSIX_SPAWN = 0 || test $REPLACE_POSIX_SPAWN = 1; then
     AC_LIBOBJ([spawni])
     gl_PREREQ_POSIX_SPAWN_INTERNAL
   fi
-  gl_SPAWN_MODULE_INDICATOR([posix_spawn])
+  gl_FUNC_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR
+  if test $HAVE_POSIX_SPAWN = 0 || test $REPLACE_POSIX_SPAWN = 1 || test $HAVE_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR = 0 || test $REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR = 1; then
+    AC_LIBOBJ([spawn_faction_addchdir])
+  fi
+  gl_SPAWN_MODULE_INDICATOR([posix_spawn_file_actions_addchdir])
   gl_FUNC_POSIX_SPAWN_FILE_ACTIONS_ADDCLOSE
   if test $HAVE_POSIX_SPAWN = 0 || test $REPLACE_POSIX_SPAWN = 1 || test $REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDCLOSE = 1; then
     AC_LIBOBJ([spawn_faction_addclose])
@@ -825,14 +1039,17 @@ AC_DEFUN([gl_INIT],
   gl_SPAWN_MODULE_INDICATOR([posix_spawnattr_setflags])
   gl_POSIX_SPAWN
   if test $HAVE_POSIX_SPAWN = 0 || test $REPLACE_POSIX_SPAWN = 1; then
+    AC_LIBOBJ([spawnattr_setpgroup])
+  fi
+  gl_SPAWN_MODULE_INDICATOR([posix_spawnattr_setpgroup])
+  gl_POSIX_SPAWN
+  if test $HAVE_POSIX_SPAWN = 0 || test $REPLACE_POSIX_SPAWN = 1; then
     AC_LIBOBJ([spawnattr_setsigmask])
   fi
   gl_SPAWN_MODULE_INDICATOR([posix_spawnattr_setsigmask])
   gl_POSIX_SPAWN
   if test $HAVE_POSIX_SPAWN = 0 || test $REPLACE_POSIX_SPAWN = 1; then
     AC_LIBOBJ([spawnp])
-    AC_LIBOBJ([spawni])
-    gl_PREREQ_POSIX_SPAWN_INTERNAL
   fi
   gl_SPAWN_MODULE_INDICATOR([posix_spawnp])
   gl_QUOTE
@@ -849,6 +1066,22 @@ AC_DEFUN([gl_INIT],
     gl_PREREQ_RAWMEMCHR
   fi
   gl_STRING_MODULE_INDICATOR([rawmemchr])
+  gl_FUNC_READDIR
+  if test $HAVE_READDIR = 0; then
+    AC_LIBOBJ([readdir])
+  fi
+  gl_DIRENT_MODULE_INDICATOR([readdir])
+  gl_FUNC_READLINK
+  if test $HAVE_READLINK = 0 || test $REPLACE_READLINK = 1; then
+    AC_LIBOBJ([readlink])
+    gl_PREREQ_READLINK
+  fi
+  gl_UNISTD_MODULE_INDICATOR([readlink])
+  gl_FUNC_REALLOC_POSIX
+  if test $REPLACE_REALLOC = 1; then
+    AC_LIBOBJ([realloc])
+  fi
+  gl_STDLIB_MODULE_INDICATOR([realloc-posix])
   AC_REQUIRE([gl_HEADER_SYS_SOCKET])
   if test "$ac_cv_header_winsock2_h" = yes; then
     AC_LIBOBJ([recv])
@@ -859,6 +1092,12 @@ AC_DEFUN([gl_INIT],
     AC_LIBOBJ([regex])
     gl_PREREQ_REGEX
   fi
+  gl_FUNC_REWINDDIR
+  if test $HAVE_REWINDDIR = 0; then
+    AC_LIBOBJ([rewinddir])
+  fi
+  gl_DIRENT_MODULE_INDICATOR([rewinddir])
+  gl_SAVE_CWD
   gl_SCHED_H
   gl_FUNC_SECURE_GETENV
   if test $HAVE_SECURE_GETENV = 0; then
@@ -877,6 +1116,12 @@ AC_DEFUN([gl_INIT],
   fi
   gl_SYS_SOCKET_MODULE_INDICATOR([send])
   gl_SERVENT
+  gl_FUNC_SETLOCALE_NULL
+  if test $SETLOCALE_NULL_ALL_MTSAFE = 0 || test $SETLOCALE_NULL_ONE_MTSAFE = 0; then
+    AC_LIBOBJ([setlocale-lock])
+    gl_PREREQ_SETLOCALE_LOCK
+  fi
+  gl_LOCALE_MODULE_INDICATOR([setlocale_null])
   AC_REQUIRE([gl_HEADER_SYS_SOCKET])
   if test "$ac_cv_header_winsock2_h" = yes; then
     AC_LIBOBJ([setsockopt])
@@ -932,6 +1177,12 @@ AC_DEFUN([gl_INIT],
   gl_TYPE_SOCKLEN_T
   gl_SPAWN_H
   gl_SPAWN_PIPE
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  case "$host_os" in
+    os2*)
+      AC_LIBOBJ([os2-spawn])
+      ;;
+  esac
   gt_TYPE_SSIZE_T
   gl_FUNC_STAT
   if test $REPLACE_STAT = 1; then
@@ -952,6 +1203,12 @@ AC_DEFUN([gl_INIT],
   gl_STDINT_H
   gl_STDIO_H
   gl_STDLIB_H
+  gl_FUNC_STPCPY
+  if test $HAVE_STPCPY = 0; then
+    AC_LIBOBJ([stpcpy])
+    gl_PREREQ_STPCPY
+  fi
+  gl_STRING_MODULE_INDICATOR([stpcpy])
   gl_STRCASE
   if test $HAVE_STRCASECMP = 0; then
     AC_LIBOBJ([strcasecmp])
@@ -968,7 +1225,7 @@ AC_DEFUN([gl_INIT],
   fi
   gl_STRING_MODULE_INDICATOR([strchrnul])
   gl_FUNC_STRDUP_POSIX
-  if test $ac_cv_func_strdup = no || test $REPLACE_STRDUP = 1; then
+  if test $REPLACE_STRDUP = 1; then
     AC_LIBOBJ([strdup])
     gl_PREREQ_STRDUP
   fi
@@ -1043,6 +1300,8 @@ AC_DEFUN([gl_INIT],
   AC_PROG_MKDIR_P
   gl_SYS_IOCTL_H
   AC_PROG_MKDIR_P
+  gl_HEADER_SYS_RANDOM
+  AC_PROG_MKDIR_P
   AC_REQUIRE([gl_HEADER_SYS_SELECT])
   AC_PROG_MKDIR_P
   AC_REQUIRE([gl_HEADER_SYS_SOCKET])
@@ -1058,7 +1317,9 @@ AC_DEFUN([gl_INIT],
   gl_SYS_WAIT_H
   AC_PROG_MKDIR_P
   gl_FUNC_GEN_TEMPNAME
-  gl_THREADLIB
+  gl_MODULE_INDICATOR([tempname])
+  AC_CHECK_HEADERS([sys/single_threaded.h])
+  AC_REQUIRE([gl_THREADLIB])
   gl_HEADER_TIME_H
   gl_TIME_R
   if test $HAVE_LOCALTIME_R = 0 || test $REPLACE_LOCALTIME_R = 1; then
@@ -1114,6 +1375,7 @@ AC_DEFUN([gl_INIT],
   gl_UTIME_MODULE_INDICATOR([utime])
   gl_UTIME_H
   gl_UTIMENS
+  AC_REQUIRE([AC_C_RESTRICT])
   gl_FUNC_VASNPRINTF
   gl_FUNC_VASPRINTF
   gl_STDIO_MODULE_INDICATOR([vasprintf])
@@ -1142,6 +1404,46 @@ AC_DEFUN([gl_INIT],
     gl_PREREQ_WCWIDTH
   fi
   gl_WCHAR_MODULE_INDICATOR([wcwidth])
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  case "$host_os" in
+    mingw*)
+      AC_LIBOBJ([windows-mutex])
+      ;;
+  esac
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  case "$host_os" in
+    mingw*)
+      AC_LIBOBJ([windows-once])
+      ;;
+  esac
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  case "$host_os" in
+    mingw*)
+      AC_LIBOBJ([windows-recmutex])
+      ;;
+  esac
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  case "$host_os" in
+    mingw*)
+      AC_LIBOBJ([windows-rwlock])
+      ;;
+  esac
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  case "$host_os" in
+    mingw*)
+      AC_LIBOBJ([windows-spawn])
+      ;;
+  esac
+  gl_FUNC_WMEMCHR
+  if test $HAVE_WMEMCHR = 0; then
+    AC_LIBOBJ([wmemchr])
+  fi
+  gl_WCHAR_MODULE_INDICATOR([wmemchr])
+  gl_FUNC_WMEMPCPY
+  if test $HAVE_WMEMPCPY = 0; then
+    AC_LIBOBJ([wmempcpy])
+  fi
+  gl_WCHAR_MODULE_INDICATOR([wmempcpy])
   gl_FUNC_WRITE
   if test $REPLACE_WRITE = 1; then
     AC_LIBOBJ([write])
@@ -1149,7 +1451,8 @@ AC_DEFUN([gl_INIT],
   fi
   gl_UNISTD_MODULE_INDICATOR([write])
   gl_XALLOC
-  AC_LIBOBJ([xmemdup0])
+  gl_MODULE_INDICATOR([xalloc])
+  gl_MODULE_INDICATOR([xalloc-die])
   gl_XSIZE
   gl_XSTRNDUP
   # End of code from modules
@@ -1191,7 +1494,7 @@ AC_DEFUN([gl_INIT],
   m4_pushdef([gltests_LIBSOURCES_LIST], [])
   m4_pushdef([gltests_LIBSOURCES_DIR], [])
   gl_COMMON
-  gl_source_base='tests'
+  gl_source_base='lib/tests'
 changequote(,)dnl
   gltests_WITNESS=IN_`echo "${PACKAGE-$PACKAGE_TARNAME}" | LC_ALL=C tr abcdefghijklmnopqrstuvwxyz ABCDEFGHIJKLMNOPQRSTUVWXYZ | LC_ALL=C sed -e 's/[^A-Z0-9_]/_/g'`_GNULIB_TESTS
 changequote([, ])dnl
@@ -1283,7 +1586,7 @@ AC_DEFUN([gltests_REPLACE_FUNCS], [
 AC_DEFUN([gltests_LIBSOURCES], [
   m4_foreach([_gl_NAME], [$1], [
     m4_if(_gl_NAME, [alloca.c], [], [
-      m4_define([gltests_LIBSOURCES_DIR], [tests])
+      m4_define([gltests_LIBSOURCES_DIR], [lib/tests])
       m4_append([gltests_LIBSOURCES_LIST], _gl_NAME, [ ])
     ])
   ])
@@ -1302,6 +1605,7 @@ AC_DEFUN([gl_FILE_LIST], [
   build-aux/vc-list-files
   lib/_Noreturn.h
   lib/accept.c
+  lib/access.c
   lib/af_alg.c
   lib/af_alg.h
   lib/alloca.c
@@ -1311,13 +1615,19 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/array-mergesort.h
   lib/asnprintf.c
   lib/asprintf.c
+  lib/assure.h
+  lib/at-func.c
+  lib/attribute.h
   lib/base32.c
   lib/base32.h
   lib/basename-lgpl.c
+  lib/basename-lgpl.h
   lib/basename.c
   lib/binary-io.c
   lib/binary-io.h
   lib/bind.c
+  lib/bitrotate.c
+  lib/bitrotate.h
   lib/btowc.c
   lib/byteswap.in.h
   lib/c++defs.h
@@ -1329,17 +1639,28 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/c-strcasestr.c
   lib/c-strcasestr.h
   lib/c-strncasecmp.c
+  lib/canonicalize.c
+  lib/canonicalize.h
   lib/cdefs.h
+  lib/chdir-long.c
+  lib/chdir-long.h
   lib/cloexec.c
   lib/cloexec.h
   lib/close.c
+  lib/closedir.c
+  lib/concat-filename.c
+  lib/concat-filename.h
   lib/connect.c
+  lib/ctype.in.h
+  lib/dirent-private.h
+  lib/dirent.in.h
+  lib/dirfd.c
   lib/dirname-lgpl.c
   lib/dirname.c
   lib/dirname.h
-  lib/dosname.h
   lib/dup-safer-flag.c
   lib/dup-safer.c
+  lib/dup.c
   lib/dup2.c
   lib/errno.in.h
   lib/error.c
@@ -1348,14 +1669,22 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/exitfail.h
   lib/fatal-signal.c
   lib/fatal-signal.h
+  lib/fchdir.c
   lib/fcntl.c
   lib/fcntl.in.h
   lib/fd-hook.c
   lib/fd-hook.h
   lib/fd-safer-flag.c
   lib/fd-safer.c
+  lib/fdopendir.c
   lib/fflush.c
+  lib/file-set.c
+  lib/file-set.h
   lib/filename.h
+  lib/filenamecat-lgpl.c
+  lib/filenamecat.h
+  lib/findprog-in.c
+  lib/findprog.h
   lib/flexmember.h
   lib/float+.h
   lib/float.c
@@ -1368,14 +1697,18 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/fpurge.c
   lib/freading.c
   lib/freading.h
+  lib/free.c
   lib/fseek.c
   lib/fseeko.c
   lib/fstat.c
+  lib/fstatat.c
   lib/ftell.c
   lib/ftello.c
   lib/futimens.c
   lib/gai_strerror.c
   lib/getaddrinfo.c
+  lib/getcwd-lgpl.c
+  lib/getcwd.c
   lib/getdelim.c
   lib/getdtablesize.c
   lib/getgroups.c
@@ -1394,6 +1727,7 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/getpeername.c
   lib/getprogname.c
   lib/getprogname.h
+  lib/getrandom.c
   lib/getsockname.c
   lib/gettext.h
   lib/gettime.c
@@ -1405,14 +1739,26 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/group-member.c
   lib/hard-locale.c
   lib/hard-locale.h
+  lib/hash-pjw.c
+  lib/hash-pjw.h
+  lib/hash-triple-simple.c
+  lib/hash-triple.h
+  lib/hash.c
+  lib/hash.h
   lib/iconv.in.h
+  lib/idx.h
   lib/inet_ntop.c
   lib/intprops.h
   lib/inttypes.in.h
   lib/ioctl.c
+  lib/isblank.c
   lib/iswblank.c
+  lib/iswdigit.c
+  lib/iswxdigit.c
   lib/itold.c
   lib/langinfo.in.h
+  lib/lc-charset-dispatch.c
+  lib/lc-charset-dispatch.h
   lib/libc-config.h
   lib/libunistring.valgrind
   lib/limits.in.h
@@ -1422,23 +1768,30 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/localcharset.h
   lib/locale.in.h
   lib/localeconv.c
-  lib/localtime-buffer.c
-  lib/localtime-buffer.h
   lib/lseek.c
   lib/lstat.c
   lib/malloc.c
+  lib/malloc/scratch_buffer.h
+  lib/malloc/scratch_buffer_dupfree.c
+  lib/malloc/scratch_buffer_grow.c
+  lib/malloc/scratch_buffer_grow_preserve.c
+  lib/malloc/scratch_buffer_set_array_size.c
   lib/malloca.c
   lib/malloca.h
   lib/mbchar.c
   lib/mbchar.h
   lib/mbiter.c
   lib/mbiter.h
+  lib/mbrtowc-impl-utf8.h
+  lib/mbrtowc-impl.h
   lib/mbrtowc.c
   lib/mbsinit.c
   lib/mbsrtowcs-impl.h
   lib/mbsrtowcs-state.c
   lib/mbsrtowcs.c
   lib/mbtowc-impl.h
+  lib/mbtowc-lock.c
+  lib/mbtowc-lock.h
   lib/mbtowc.c
   lib/md2.c
   lib/md2.h
@@ -1448,6 +1801,7 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/md5.h
   lib/memchr.c
   lib/memchr.valgrind
+  lib/mempcpy.c
   lib/memrchr.c
   lib/minmax.h
   lib/mkdir.c
@@ -1462,8 +1816,17 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/nanosleep.c
   lib/netdb.in.h
   lib/netinet_in.in.h
+  lib/nl_langinfo-lock.c
   lib/nl_langinfo.c
   lib/open.c
+  lib/openat-die.c
+  lib/openat-priv.h
+  lib/openat-proc.c
+  lib/openat.c
+  lib/openat.h
+  lib/opendir.c
+  lib/os2-spawn.c
+  lib/os2-spawn.h
   lib/pathmax.h
   lib/pipe-safer.c
   lib/pipe.c
@@ -1479,6 +1842,9 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/raise.c
   lib/rawmemchr.c
   lib/rawmemchr.valgrind
+  lib/readdir.c
+  lib/readlink.c
+  lib/realloc.c
   lib/recv.c
   lib/regcomp.c
   lib/regex.c
@@ -1486,10 +1852,18 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/regex_internal.c
   lib/regex_internal.h
   lib/regexec.c
+  lib/rewinddir.c
+  lib/same-inode.h
+  lib/save-cwd.c
+  lib/save-cwd.h
   lib/sched.in.h
+  lib/scratch_buffer.h
   lib/secure_getenv.c
   lib/select.c
   lib/send.c
+  lib/setlocale-lock.c
+  lib/setlocale_null.c
+  lib/setlocale_null.h
   lib/setsockopt.c
   lib/sha1.c
   lib/sha1.h
@@ -1511,6 +1885,7 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/spawn-pipe.h
   lib/spawn.c
   lib/spawn.in.h
+  lib/spawn_faction_addchdir.c
   lib/spawn_faction_addclose.c
   lib/spawn_faction_adddup2.c
   lib/spawn_faction_addopen.c
@@ -1520,6 +1895,7 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/spawnattr_destroy.c
   lib/spawnattr_init.c
   lib/spawnattr_setflags.c
+  lib/spawnattr_setpgroup.c
   lib/spawnattr_setsigmask.c
   lib/spawni.c
   lib/spawnp.c
@@ -1536,6 +1912,7 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/stdio-write.c
   lib/stdio.in.h
   lib/stdlib.in.h
+  lib/stpcpy.c
   lib/str-two-way.h
   lib/strcasecmp.c
   lib/strchrnul.c
@@ -1563,6 +1940,7 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/sys-limits.h
   lib/sys_file.in.h
   lib/sys_ioctl.in.h
+  lib/sys_random.in.h
   lib/sys_select.in.h
   lib/sys_socket.c
   lib/sys_socket.in.h
@@ -1573,6 +1951,7 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/sys_wait.in.h
   lib/tempname.c
   lib/tempname.h
+  lib/thread-optim.h
   lib/time.in.h
   lib/time_r.c
   lib/timegm.c
@@ -1642,7 +2021,6 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/verify.h
   lib/vsnprintf.c
   lib/w32sock.h
-  lib/w32spawn.h
   lib/wait-process.c
   lib/wait-process.h
   lib/waitpid.c
@@ -1652,6 +2030,20 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/wctype-h.c
   lib/wctype.in.h
   lib/wcwidth.c
+  lib/windows-initguard.h
+  lib/windows-mutex.c
+  lib/windows-mutex.h
+  lib/windows-once.c
+  lib/windows-once.h
+  lib/windows-recmutex.c
+  lib/windows-recmutex.h
+  lib/windows-rwlock.c
+  lib/windows-rwlock.h
+  lib/windows-spawn.c
+  lib/windows-spawn.h
+  lib/wmemchr-impl.h
+  lib/wmemchr.c
+  lib/wmempcpy.c
   lib/write.c
   lib/xalloc-die.c
   lib/xalloc-oversized.h
@@ -1666,6 +2058,7 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/00gnulib.m4
   m4/__inline.m4
   m4/absolute-header.m4
+  m4/access.m4
   m4/af_alg.m4
   m4/alloca.m4
   m4/arpa_inet_h.m4
@@ -1674,12 +2067,20 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/btowc.m4
   m4/builtin-expect.m4
   m4/byteswap.m4
+  m4/canonicalize.m4
+  m4/chdir-long.m4
   m4/clock_time.m4
   m4/close.m4
+  m4/closedir.m4
   m4/codeset.m4
-  m4/dirname.m4
+  m4/ctype.m4
+  m4/d-ino.m4
+  m4/dirent_h.m4
+  m4/dirfd.m4
   m4/double-slash-root.m4
+  m4/dup.m4
   m4/dup2.m4
+  m4/eaccess.m4
   m4/eealloc.m4
   m4/environ.m4
   m4/errno_h.m4
@@ -1688,10 +2089,14 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/extensions.m4
   m4/extern-inline.m4
   m4/fatal-signal.m4
+  m4/fchdir.m4
   m4/fcntl-o.m4
   m4/fcntl.m4
   m4/fcntl_h.m4
+  m4/fdopendir.m4
   m4/fflush.m4
+  m4/filenamecat.m4
+  m4/findprog-in.m4
   m4/flexmember.m4
   m4/float_h.m4
   m4/flock.m4
@@ -1700,24 +2105,30 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/fopen.m4
   m4/fpurge.m4
   m4/freading.m4
+  m4/free.m4
   m4/fseek.m4
   m4/fseeko.m4
   m4/fstat.m4
+  m4/fstatat.m4
   m4/ftell.m4
   m4/ftello.m4
   m4/futimens.m4
   m4/getaddrinfo.m4
+  m4/getcwd-abort-bug.m4
+  m4/getcwd-path-max.m4
+  m4/getcwd.m4
   m4/getdelim.m4
   m4/getdtablesize.m4
   m4/getgroups.m4
   m4/getline.m4
   m4/getopt.m4
+  m4/getpagesize.m4
   m4/getpass.m4
   m4/getprogname.m4
+  m4/getrandom.m4
   m4/gettime.m4
   m4/gettimeofday.m4
   m4/gl-openssl.m4
-  m4/glibc21.m4
   m4/gnulib-common.m4
   m4/group-member.m4
   m4/host-cpu-c-abi.m4
@@ -1728,11 +2139,13 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/inet_ntop.m4
   m4/inline.m4
   m4/intmax_t.m4
-  m4/inttypes-pri.m4
   m4/inttypes.m4
   m4/inttypes_h.m4
   m4/ioctl.m4
+  m4/isblank.m4
   m4/iswblank.m4
+  m4/iswdigit.m4
+  m4/iswxdigit.m4
   m4/langinfo_h.m4
   m4/largefile.m4
   m4/lib-ld.m4
@@ -1749,9 +2162,7 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/locale-zh.m4
   m4/locale_h.m4
   m4/localeconv.m4
-  m4/localtime-buffer.m4
   m4/lock.m4
-  m4/longlong.m4
   m4/lseek.m4
   m4/lstat.m4
   m4/malloc.m4
@@ -1767,6 +2178,7 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/md4.m4
   m4/md5.m4
   m4/memchr.m4
+  m4/mempcpy.m4
   m4/memrchr.m4
   m4/minmax.m4
   m4/mkdir.m4
@@ -1785,22 +2197,33 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/nocrash.m4
   m4/off_t.m4
   m4/open-cloexec.m4
+  m4/open-slash.m4
   m4/open.m4
+  m4/openat.m4
+  m4/opendir.m4
   m4/pathmax.m4
+  m4/pid_t.m4
   m4/pipe.m4
   m4/pipe2.m4
   m4/posix_spawn.m4
+  m4/posix_spawn_faction_addchdir.m4
   m4/printf.m4
   m4/pthread_rwlock_rdlock.m4
   m4/quote.m4
   m4/quotearg.m4
   m4/raise.m4
   m4/rawmemchr.m4
+  m4/readdir.m4
+  m4/readlink.m4
+  m4/realloc.m4
   m4/regex.m4
+  m4/rewinddir.m4
+  m4/save-cwd.m4
   m4/sched_h.m4
   m4/secure_getenv.m4
   m4/select.m4
   m4/servent.m4
+  m4/setlocale_null.m4
   m4/sh-filename.m4
   m4/sha1.m4
   m4/sha256.m4
@@ -1829,6 +2252,7 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/stdint_h.m4
   m4/stdio_h.m4
   m4/stdlib_h.m4
+  m4/stpcpy.m4
   m4/strcase.m4
   m4/strchrnul.m4
   m4/strdup.m4
@@ -1846,6 +2270,7 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/symlink.m4
   m4/sys_file_h.m4
   m4/sys_ioctl_h.m4
+  m4/sys_random_h.m4
   m4/sys_select_h.m4
   m4/sys_socket_h.m4
   m4/sys_stat_h.m4
@@ -1871,20 +2296,25 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/utimes.m4
   m4/vasnprintf.m4
   m4/vasprintf.m4
+  m4/visibility.m4
   m4/vsnprintf.m4
   m4/wait-process.m4
   m4/waitpid.m4
   m4/warn-on-use.m4
+  m4/warnings.m4
   m4/wchar_h.m4
   m4/wchar_t.m4
   m4/wcrtomb.m4
   m4/wctype_h.m4
   m4/wcwidth.m4
   m4/wint_t.m4
+  m4/wmemchr.m4
+  m4/wmempcpy.m4
   m4/write.m4
   m4/xalloc.m4
   m4/xsize.m4
   m4/xstrndup.m4
+  m4/zzgnulib.m4
   top/GNUmakefile
   top/maint.mk
 ])
diff --git a/m4/group-member.m4 b/m4/group-member.m4
index 77d389d..ad7368c 100644
--- a/m4/group-member.m4
+++ b/m4/group-member.m4
@@ -1,6 +1,6 @@
 # serial 14
 
-# Copyright (C) 1999-2001, 2003-2007, 2009-2019 Free Software Foundation, Inc.
+# Copyright (C) 1999-2001, 2003-2007, 2009-2020 Free Software Foundation, Inc.
 
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
diff --git a/m4/host-cpu-c-abi.m4 b/m4/host-cpu-c-abi.m4
index 4407296..6db2aa2 100644
--- a/m4/host-cpu-c-abi.m4
+++ b/m4/host-cpu-c-abi.m4
@@ -1,5 +1,5 @@
-# host-cpu-c-abi.m4 serial 11
-dnl Copyright (C) 2002-2019 Free Software Foundation, Inc.
+# host-cpu-c-abi.m4 serial 13
+dnl Copyright (C) 2002-2020 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.
@@ -55,7 +55,7 @@ AC_DEFUN([gl_HOST_CPU_C_ABI],
     [case "$host_cpu" in
 
 changequote(,)dnl
-       i[4567]86 )
+       i[34567]86 )
 changequote([,])dnl
          gl_cv_host_cpu_c_abi=i386
          ;;
@@ -457,7 +457,8 @@ EOF
 
 
 dnl Sets the HOST_CPU_C_ABI_32BIT variable to 'yes' if the C language ABI
-dnl (application binary interface) is a 32-bit one, or to 'no' otherwise.
+dnl (application binary interface) is a 32-bit one, to 'no' if it is a 64-bit
+dnl one, or to 'unknown' if unknown.
 dnl This is a simplified variant of gl_HOST_CPU_C_ABI.
 AC_DEFUN([gl_HOST_CPU_C_ABI_32BIT],
 [
@@ -467,14 +468,44 @@ AC_DEFUN([gl_HOST_CPU_C_ABI_32BIT],
        case "$gl_cv_host_cpu_c_abi" in
          i386 | x86_64-x32 | arm | armhf | arm64-ilp32 | hppa | ia64-ilp32 | mips | mipsn32 | powerpc | riscv*-ilp32* | s390 | sparc)
            gl_cv_host_cpu_c_abi_32bit=yes ;;
-         *)
+         x86_64 | alpha | arm64 | hppa64 | ia64 | mips64 | powerpc64 | powerpc64-elfv2 | riscv*-lp64* | s390x | sparc64 )
            gl_cv_host_cpu_c_abi_32bit=no ;;
+         *)
+           gl_cv_host_cpu_c_abi_32bit=unknown ;;
        esac
      else
        case "$host_cpu" in
 
+         # CPUs that only support a 32-bit ABI.
+         arc \
+         | bfin \
+         | cris* \
+         | csky \
+         | epiphany \
+         | ft32 \
+         | h8300 \
+         | m68k \
+         | microblaze | microblazeel \
+         | nds32 | nds32le | nds32be \
+         | nios2 | nios2eb | nios2el \
+         | or1k* \
+         | or32 \
+         | sh | sh[1234] | sh[1234]e[lb] \
+         | tic6x \
+         | xtensa* )
+           gl_cv_host_cpu_c_abi_32bit=yes
+           ;;
+
+         # CPUs that only support a 64-bit ABI.
 changequote(,)dnl
-         i[4567]86 )
+         alpha | alphaev[4-8] | alphaev56 | alphapca5[67] | alphaev6[78] \
+         | mmix )
+changequote([,])dnl
+           gl_cv_host_cpu_c_abi_32bit=no
+           ;;
+
+changequote(,)dnl
+         i[34567]86 )
 changequote([,])dnl
            gl_cv_host_cpu_c_abi_32bit=yes
            ;;
@@ -634,7 +665,7 @@ changequote([,])dnl
            ;;
 
          *)
-           gl_cv_host_cpu_c_abi_32bit=no
+           gl_cv_host_cpu_c_abi_32bit=unknown
            ;;
        esac
      fi
diff --git a/m4/hostent.m4 b/m4/hostent.m4
index d3ee30c..2860452 100644
--- a/m4/hostent.m4
+++ b/m4/hostent.m4
@@ -1,5 +1,5 @@
 # hostent.m4 serial 3
-dnl Copyright (C) 2008, 2010-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2008, 2010-2020 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.
diff --git a/m4/iconv.m4 b/m4/iconv.m4
index a285e9d..f8a536b 100644
--- a/m4/iconv.m4
+++ b/m4/iconv.m4
@@ -1,5 +1,5 @@
-# iconv.m4 serial 21
-dnl Copyright (C) 2000-2002, 2007-2014, 2016-2019 Free Software Foundation,
+# iconv.m4 serial 23
+dnl Copyright (C) 2000-2002, 2007-2014, 2016-2020 Free Software Foundation,
 dnl Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -7,6 +7,12 @@ dnl with or without modifications, as long as this notice is preserved.
 
 dnl From Bruno Haible.
 
+AC_PREREQ([2.64])
+
+dnl Note: AM_ICONV is documented in the GNU gettext manual
+dnl <https://www.gnu.org/software/gettext/manual/html_node/AM_005fICONV.html>.
+dnl Don't make changes that are incompatible with that documentation!
+
 AC_DEFUN([AM_ICONV_LINKFLAGS_BODY],
 [
   dnl Prerequisites of AC_LIB_LINKFLAGS_BODY.
@@ -225,8 +231,7 @@ AC_DEFUN([AM_ICONV_LINK],
   AC_SUBST([LTLIBICONV])
 ])
 
-dnl Define AM_ICONV using AC_DEFUN_ONCE for Autoconf >= 2.64, in order to
-dnl avoid warnings like
+dnl Define AM_ICONV using AC_DEFUN_ONCE, in order to avoid warnings like
 dnl "warning: AC_REQUIRE: `AM_ICONV' was expanded before it was required".
 dnl This is tricky because of the way 'aclocal' is implemented:
 dnl - It requires defining an auxiliary macro whose name ends in AC_DEFUN.
@@ -234,54 +239,43 @@ dnl   Otherwise aclocal's initial scan pass would miss the macro definition.
 dnl - It requires a line break inside the AC_DEFUN_ONCE and AC_DEFUN expansions.
 dnl   Otherwise aclocal would emit many "Use of uninitialized value $1"
 dnl   warnings.
-m4_define([gl_iconv_AC_DEFUN],
-  m4_version_prereq([2.64],
-    [[AC_DEFUN_ONCE(
-        [$1], [$2])]],
-    [m4_ifdef([gl_00GNULIB],
-       [[AC_DEFUN_ONCE(
-           [$1], [$2])]],
-       [[AC_DEFUN(
-           [$1], [$2])]])]))
-gl_iconv_AC_DEFUN([AM_ICONV],
+AC_DEFUN_ONCE([AM_ICONV],
 [
   AM_ICONV_LINK
   if test "$am_cv_func_iconv" = yes; then
-    AC_MSG_CHECKING([for iconv declaration])
-    AC_CACHE_VAL([am_cv_proto_iconv], [
-      AC_COMPILE_IFELSE(
-        [AC_LANG_PROGRAM(
-           [[
+    AC_CACHE_CHECK([whether iconv is compatible with its POSIX signature],
+      [gl_cv_iconv_nonconst],
+      [AC_COMPILE_IFELSE(
+         [AC_LANG_PROGRAM(
+            [[
 #include <stdlib.h>
 #include <iconv.h>
 extern
 #ifdef __cplusplus
 "C"
 #endif
-#if defined(__STDC__) || defined(_MSC_VER) || defined(__cplusplus)
 size_t iconv (iconv_t cd, char * *inbuf, size_t *inbytesleft, char * *outbuf, size_t *outbytesleft);
-#else
-size_t iconv();
-#endif
-           ]],
-           [[]])],
-        [am_cv_proto_iconv_arg1=""],
-        [am_cv_proto_iconv_arg1="const"])
-      am_cv_proto_iconv="extern size_t iconv (iconv_t cd, $am_cv_proto_iconv_arg1 char * *inbuf, size_t *inbytesleft, char * *outbuf, size_t *outbytesleft);"])
-    am_cv_proto_iconv=`echo "[$]am_cv_proto_iconv" | tr -s ' ' | sed -e 's/( /(/'`
-    AC_MSG_RESULT([
-         $am_cv_proto_iconv])
+            ]],
+            [[]])],
+         [gl_cv_iconv_nonconst=yes],
+         [gl_cv_iconv_nonconst=no])
+      ])
   else
     dnl When compiling GNU libiconv on a system that does not have iconv yet,
     dnl pick the POSIX compliant declaration without 'const'.
-    am_cv_proto_iconv_arg1=""
+    gl_cv_iconv_nonconst=yes
+  fi
+  if test $gl_cv_iconv_nonconst = yes; then
+    iconv_arg1=""
+  else
+    iconv_arg1="const"
   fi
-  AC_DEFINE_UNQUOTED([ICONV_CONST], [$am_cv_proto_iconv_arg1],
+  AC_DEFINE_UNQUOTED([ICONV_CONST], [$iconv_arg1],
     [Define as const if the declaration of iconv() needs const.])
   dnl Also substitute ICONV_CONST in the gnulib generated <iconv.h>.
   m4_ifdef([gl_ICONV_H_DEFAULTS],
     [AC_REQUIRE([gl_ICONV_H_DEFAULTS])
-     if test -n "$am_cv_proto_iconv_arg1"; then
+     if test $gl_cv_iconv_nonconst != yes; then
        ICONV_CONST="const"
      fi
     ])
diff --git a/m4/iconv_h.m4 b/m4/iconv_h.m4
index abd3fa7..23d41c9 100644
--- a/m4/iconv_h.m4
+++ b/m4/iconv_h.m4
@@ -1,5 +1,5 @@
-# iconv_h.m4 serial 11
-dnl Copyright (C) 2007-2019 Free Software Foundation, Inc.
+# iconv_h.m4 serial 12
+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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -17,6 +17,8 @@ AC_DEFUN([gl_ICONV_H],
   dnl guaranteed by C89.
   gl_WARN_ON_USE_PREPARE([[#include <iconv.h>
     ]], [iconv iconv_open])
+
+  AC_REQUIRE([AC_C_RESTRICT])
 ])
 
 dnl Unconditionally enables the replacement of <iconv.h>.
diff --git a/m4/include_next.m4 b/m4/include_next.m4
index 86eb2c9..9221d9f 100644
--- a/m4/include_next.m4
+++ b/m4/include_next.m4
@@ -1,5 +1,5 @@
-# include_next.m4 serial 24
-dnl Copyright (C) 2006-2019 Free Software Foundation, Inc.
+# include_next.m4 serial 26
+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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -106,19 +106,21 @@ dnl We intentionally avoid using AC_LANG_SOURCE here.
   AC_SUBST([INCLUDE_NEXT])
   AC_SUBST([INCLUDE_NEXT_AS_FIRST_DIRECTIVE])
   AC_SUBST([PRAGMA_SYSTEM_HEADER])
-  AC_CACHE_CHECK([whether system header files limit the line length],
-    [gl_cv_pragma_columns],
-    [dnl HP NonStop systems, which define __TANDEM, have this misfeature.
-     AC_EGREP_CPP([choke me],
+
+  dnl HP NonStop systems, which define __TANDEM, limit the line length
+  dnl after including some system header files.
+  AC_CACHE_CHECK([whether source code line length is unlimited],
+    [gl_cv_source_line_length_unlimited],
+    [AC_EGREP_CPP([choke me],
        [
 #ifdef __TANDEM
 choke me
 #endif
        ],
-       [gl_cv_pragma_columns=yes],
-       [gl_cv_pragma_columns=no])
+       [gl_cv_source_line_length_unlimited=no],
+       [gl_cv_source_line_length_unlimited=yes])
     ])
-  if test $gl_cv_pragma_columns = yes; then
+  if test $gl_cv_source_line_length_unlimited = no; then
     PRAGMA_COLUMNS="#pragma COLUMNS 10000"
   else
     PRAGMA_COLUMNS=
@@ -176,42 +178,40 @@ 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/inet_ntop.m4 b/m4/inet_ntop.m4
index 3804e88..39a6a9b 100644
--- a/m4/inet_ntop.m4
+++ b/m4/inet_ntop.m4
@@ -1,5 +1,5 @@
-# inet_ntop.m4 serial 20
-dnl Copyright (C) 2005-2006, 2008-2019 Free Software Foundation, Inc.
+# inet_ntop.m4 serial 21
+dnl Copyright (C) 2005-2006, 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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -24,15 +24,16 @@ AC_DEFUN([gl_FUNC_INET_NTOP],
   INET_NTOP_LIB=
   gl_PREREQ_SYS_H_WINSOCK2
   if test $HAVE_WINSOCK2_H = 1; then
+    dnl It needs to be overridden, because the stdcall calling convention
+    dnl is not compliant with POSIX.  Set REPLACE_INET_NTOP in order to avoid
+    dnl a name conflict at the linker level, even though the header file
+    dnl <ws2tcpip.h> declares inet_ntop only if _WIN32_WINNT >= 0x0600.
+    REPLACE_INET_NTOP=1
     AC_CHECK_DECLS([inet_ntop],,, [[#include <ws2tcpip.h>]])
     if test $ac_cv_have_decl_inet_ntop = yes; then
-      dnl It needs to be overridden, because the stdcall calling convention
-      dnl is not compliant with POSIX.
-      REPLACE_INET_NTOP=1
       INET_NTOP_LIB="-lws2_32"
     else
       HAVE_DECL_INET_NTOP=0
-      HAVE_INET_NTOP=0
     fi
   else
     gl_save_LIBS=$LIBS
diff --git a/m4/inline.m4 b/m4/inline.m4
index 525b7e0..0a7cd8b 100644
--- a/m4/inline.m4
+++ b/m4/inline.m4
@@ -1,5 +1,5 @@
 # inline.m4 serial 4
-dnl Copyright (C) 2006, 2009-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2006, 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.
diff --git a/m4/intlmacosx.m4 b/m4/intlmacosx.m4
index d3f0d90..8a045f6 100644
--- a/m4/intlmacosx.m4
+++ b/m4/intlmacosx.m4
@@ -1,5 +1,5 @@
-# intlmacosx.m4 serial 1 (gettext-0.17)
-dnl Copyright (C) 2004-2007 Free Software Foundation, Inc.
+# intlmacosx.m4 serial 5 (gettext-0.18.2)
+dnl Copyright (C) 2004-2014 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.
@@ -13,35 +13,40 @@ dnl by the GNU Library General Public License, and the rest of the GNU
 dnl gettext package package is covered by the GNU General Public License.
 dnl They are *not* in the public domain.
 
-dnl Checks for special options needed on MacOS X.
+dnl Checks for special options needed on Mac OS X.
 dnl Defines INTL_MACOSX_LIBS.
 AC_DEFUN([gt_INTL_MACOSX],
 [
-  dnl Check for API introduced in MacOS X 10.2.
+  dnl Check for API introduced in Mac OS X 10.2.
   AC_CACHE_CHECK([for CFPreferencesCopyAppValue],
-    gt_cv_func_CFPreferencesCopyAppValue,
+    [gt_cv_func_CFPreferencesCopyAppValue],
     [gt_save_LIBS="$LIBS"
      LIBS="$LIBS -Wl,-framework -Wl,CoreFoundation"
-     AC_TRY_LINK([#include <CoreFoundation/CFPreferences.h>],
-       [CFPreferencesCopyAppValue(NULL, NULL)],
+     AC_LINK_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[#include <CoreFoundation/CFPreferences.h>]],
+          [[CFPreferencesCopyAppValue(NULL, NULL)]])],
        [gt_cv_func_CFPreferencesCopyAppValue=yes],
        [gt_cv_func_CFPreferencesCopyAppValue=no])
      LIBS="$gt_save_LIBS"])
   if test $gt_cv_func_CFPreferencesCopyAppValue = yes; then
-    AC_DEFINE([HAVE_CFPREFERENCESCOPYAPPVALUE], 1,
-      [Define to 1 if you have the MacOS X function CFPreferencesCopyAppValue in the CoreFoundation framework.])
+    AC_DEFINE([HAVE_CFPREFERENCESCOPYAPPVALUE], [1],
+      [Define to 1 if you have the Mac OS X function CFPreferencesCopyAppValue in the CoreFoundation framework.])
   fi
-  dnl Check for API introduced in MacOS X 10.3.
-  AC_CACHE_CHECK([for CFLocaleCopyCurrent], gt_cv_func_CFLocaleCopyCurrent,
+  dnl Check for API introduced in Mac OS X 10.3.
+  AC_CACHE_CHECK([for CFLocaleCopyCurrent], [gt_cv_func_CFLocaleCopyCurrent],
     [gt_save_LIBS="$LIBS"
      LIBS="$LIBS -Wl,-framework -Wl,CoreFoundation"
-     AC_TRY_LINK([#include <CoreFoundation/CFLocale.h>], [CFLocaleCopyCurrent();],
+     AC_LINK_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[#include <CoreFoundation/CFLocale.h>]],
+          [[CFLocaleCopyCurrent();]])],
        [gt_cv_func_CFLocaleCopyCurrent=yes],
        [gt_cv_func_CFLocaleCopyCurrent=no])
      LIBS="$gt_save_LIBS"])
   if test $gt_cv_func_CFLocaleCopyCurrent = yes; then
-    AC_DEFINE([HAVE_CFLOCALECOPYCURRENT], 1,
-      [Define to 1 if you have the MacOS X function CFLocaleCopyCurrent in the CoreFoundation framework.])
+    AC_DEFINE([HAVE_CFLOCALECOPYCURRENT], [1],
+      [Define to 1 if you have the Mac OS X function CFLocaleCopyCurrent in the CoreFoundation framework.])
   fi
   INTL_MACOSX_LIBS=
   if test $gt_cv_func_CFPreferencesCopyAppValue = yes || test $gt_cv_func_CFLocaleCopyCurrent = yes; then
diff --git a/m4/intmax_t.m4 b/m4/intmax_t.m4
index 5ded16e..72fc8a9 100644
--- a/m4/intmax_t.m4
+++ b/m4/intmax_t.m4
@@ -1,5 +1,5 @@
-# intmax_t.m4 serial 8
-dnl Copyright (C) 1997-2004, 2006-2007, 2009-2019 Free Software Foundation,
+# intmax_t.m4 serial 9
+dnl Copyright (C) 1997-2004, 2006-2007, 2009-2020 Free Software Foundation,
 dnl Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -19,11 +19,7 @@ AC_DEFUN([gl_AC_TYPE_INTMAX_T],
   AC_REQUIRE([gl_AC_HEADER_INTTYPES_H])
   AC_REQUIRE([gl_AC_HEADER_STDINT_H])
   if test $gl_cv_header_inttypes_h = no && test $gl_cv_header_stdint_h = no; then
-    AC_REQUIRE([AC_TYPE_LONG_LONG_INT])
-    test $ac_cv_type_long_long_int = yes \
-      && ac_type='long long' \
-      || ac_type='long'
-    AC_DEFINE_UNQUOTED([intmax_t], [$ac_type],
+    AC_DEFINE_UNQUOTED([intmax_t], [long long],
      [Define to long or long long if <inttypes.h> and <stdint.h> don't define.])
   else
     AC_DEFINE([HAVE_INTMAX_T], [1],
@@ -57,11 +53,7 @@ AC_DEFUN([gt_AC_TYPE_INTMAX_T],
     AC_DEFINE([HAVE_INTMAX_T], [1],
       [Define if you have the 'intmax_t' type in <stdint.h> or <inttypes.h>.])
   else
-    AC_REQUIRE([AC_TYPE_LONG_LONG_INT])
-    test $ac_cv_type_long_long_int = yes \
-      && ac_type='long long' \
-      || ac_type='long'
-    AC_DEFINE_UNQUOTED([intmax_t], [$ac_type],
+    AC_DEFINE_UNQUOTED([intmax_t], [long long],
      [Define to long or long long if <stdint.h> and <inttypes.h> don't define.])
   fi
 ])
diff --git a/m4/inttypes-pri.m4 b/m4/inttypes-pri.m4
deleted file mode 100644
index 38fe118..0000000
--- a/m4/inttypes-pri.m4
+++ /dev/null
@@ -1,42 +0,0 @@
-# inttypes-pri.m4 serial 7 (gettext-0.18.2)
-dnl Copyright (C) 1997-2002, 2006, 2008-2019 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 From Bruno Haible.
-
-AC_PREREQ([2.53])
-
-# Define PRI_MACROS_BROKEN if <inttypes.h> exists and defines the PRI*
-# macros to non-string values.  This is the case on AIX 4.3.3.
-
-AC_DEFUN([gt_INTTYPES_PRI],
-[
-  AC_CHECK_HEADERS([inttypes.h])
-  if test $ac_cv_header_inttypes_h = yes; then
-    AC_CACHE_CHECK([whether the inttypes.h PRIxNN macros are broken],
-      [gt_cv_inttypes_pri_broken],
-      [
-        AC_COMPILE_IFELSE(
-          [AC_LANG_PROGRAM(
-             [[
-#include <inttypes.h>
-#ifdef PRId32
-char *p = PRId32;
-#endif
-             ]],
-             [[]])],
-          [gt_cv_inttypes_pri_broken=no],
-          [gt_cv_inttypes_pri_broken=yes])
-      ])
-  fi
-  if test "$gt_cv_inttypes_pri_broken" = yes; then
-    AC_DEFINE_UNQUOTED([PRI_MACROS_BROKEN], [1],
-      [Define if <inttypes.h> exists and defines unusable PRI* macros.])
-    PRI_MACROS_BROKEN=1
-  else
-    PRI_MACROS_BROKEN=0
-  fi
-  AC_SUBST([PRI_MACROS_BROKEN])
-])
diff --git a/m4/inttypes.m4 b/m4/inttypes.m4
index c58a1be..84b1654 100644
--- a/m4/inttypes.m4
+++ b/m4/inttypes.m4
@@ -1,5 +1,5 @@
-# inttypes.m4 serial 27
-dnl Copyright (C) 2006-2019 Free Software Foundation, Inc.
+# inttypes.m4 serial 32
+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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -28,17 +28,26 @@ AC_DEFUN_ONCE([gl_INTTYPES_INCOMPLETE],
   dnl corresponding gnulib module is not in use.
   gl_WARN_ON_USE_PREPARE([[#include <inttypes.h>
     ]], [imaxabs imaxdiv strtoimax strtoumax])
+
+  AC_REQUIRE([AC_C_RESTRICT])
 ])
 
 # Ensure that the PRI* and SCN* macros are defined appropriately.
 AC_DEFUN([gl_INTTYPES_PRI_SCN],
 [
-  AC_REQUIRE([gt_INTTYPES_PRI])
-
   PRIPTR_PREFIX=
   if test -n "$STDINT_H"; then
-    dnl Using the gnulib <stdint.h>. It always defines intptr_t to 'long'.
-    PRIPTR_PREFIX='"l"'
+    dnl Using the gnulib <stdint.h>. It defines intptr_t to 'long' or
+    dnl 'long long', depending on _WIN64.
+    AC_COMPILE_IFELSE(
+      [AC_LANG_PROGRAM([[
+         #ifdef _WIN64
+         LLP64
+         #endif
+         ]])
+      ],
+      [PRIPTR_PREFIX='"l"'],
+      [PRIPTR_PREFIX='"ll"'])
   else
     dnl Using the system's <stdint.h>.
     for glpfx in '' l ll I64; do
@@ -113,10 +122,8 @@ AC_DEFUN([gl_INTTYPES_CHECK_LONG_LONG_INT_CONDITION],
 
             #if $2
              #define CONDITION ($3)
-            #elif HAVE_LONG_LONG_INT
-             #define CONDITION ($4)
             #else
-             #define CONDITION 0
+             #define CONDITION ($4)
             #endif
             int test[CONDITION ? 1 : -1];]])],
        [gl_cv_test_$1=yes],
@@ -152,7 +159,6 @@ AC_DEFUN([gl_INTTYPES_H_DEFAULTS],
   REPLACE_STRTOUMAX=0;   AC_SUBST([REPLACE_STRTOUMAX])
   INT32_MAX_LT_INTMAX_MAX=1;  AC_SUBST([INT32_MAX_LT_INTMAX_MAX])
   INT64_MAX_EQ_LONG_MAX='defined _LP64';  AC_SUBST([INT64_MAX_EQ_LONG_MAX])
-  PRI_MACROS_BROKEN=0;   AC_SUBST([PRI_MACROS_BROKEN])
   PRIPTR_PREFIX=__PRIPTR_PREFIX;  AC_SUBST([PRIPTR_PREFIX])
   UINT32_MAX_LT_UINTMAX_MAX=1;  AC_SUBST([UINT32_MAX_LT_UINTMAX_MAX])
   UINT64_MAX_EQ_ULONG_MAX='defined _LP64';  AC_SUBST([UINT64_MAX_EQ_ULONG_MAX])
diff --git a/m4/inttypes_h.m4 b/m4/inttypes_h.m4
index d20422a..ebb5320 100644
--- a/m4/inttypes_h.m4
+++ b/m4/inttypes_h.m4
@@ -1,5 +1,5 @@
 # inttypes_h.m4 serial 10
-dnl Copyright (C) 1997-2004, 2006, 2008-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 1997-2004, 2006, 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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/ioctl.m4 b/m4/ioctl.m4
index 2d00611..263aaae 100644
--- a/m4/ioctl.m4
+++ b/m4/ioctl.m4
@@ -1,5 +1,5 @@
 # ioctl.m4 serial 5
-dnl Copyright (C) 2008-2019 Free Software Foundation, Inc.
+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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/isblank.m4 b/m4/isblank.m4
new file mode 100644
index 0000000..5e1b783
--- /dev/null
+++ b/m4/isblank.m4
@@ -0,0 +1,17 @@
+# isblank.m4 serial 3
+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.
+
+AC_DEFUN([gl_FUNC_ISBLANK],
+[
+  dnl Persuade glibc <ctype.h> to declare isblank().
+  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
+
+  AC_REQUIRE([gl_CTYPE_H_DEFAULTS])
+  AC_CHECK_FUNCS_ONCE([isblank])
+  if test $ac_cv_func_isblank = no; then
+    HAVE_ISBLANK=0
+  fi
+])
diff --git a/m4/iswblank.m4 b/m4/iswblank.m4
index ad216cc..dd6ed94 100644
--- a/m4/iswblank.m4
+++ b/m4/iswblank.m4
@@ -1,5 +1,5 @@
-# iswblank.m4 serial 4
-dnl Copyright (C) 2011-2019 Free Software Foundation, Inc.
+# iswblank.m4 serial 5
+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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -12,16 +12,9 @@ AC_DEFUN([gl_FUNC_ISWBLANK],
   AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
   AC_CHECK_FUNCS_ONCE([iswblank])
   AC_CHECK_DECLS([iswblank], , , [[
-/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
-   <wchar.h>.
-   BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be included
-   before <wchar.h>.  */
-#include <stddef.h>
-#include <stdio.h>
-#include <time.h>
-#include <wchar.h>
-#include <wctype.h>
-]])
+    #include <wchar.h>
+    #include <wctype.h>
+  ]])
   if test $ac_cv_func_iswblank = no; then
     HAVE_ISWBLANK=0
     if test $ac_cv_have_decl_iswblank = yes; then
diff --git a/m4/iswdigit.m4 b/m4/iswdigit.m4
new file mode 100644
index 0000000..4ad6a42
--- /dev/null
+++ b/m4/iswdigit.m4
@@ -0,0 +1,115 @@
+# iswdigit.m4 serial 2
+dnl Copyright (C) 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_FUNC_ISWDIGIT],
+[
+  AC_REQUIRE([gl_WCTYPE_H_DEFAULTS])
+  AC_REQUIRE([gl_WCTYPE_H])
+  AC_REQUIRE([gt_LOCALE_FR])
+  AC_REQUIRE([gt_LOCALE_JA])
+  AC_REQUIRE([gt_LOCALE_FR_UTF8])
+  AC_REQUIRE([gt_LOCALE_ZH_CN])
+
+  if test $HAVE_ISWCNTRL = 0 || test $REPLACE_ISWCNTRL = 1; then
+    dnl <wctype.h> redefines iswdigit already.
+    REPLACE_ISWDIGIT="$REPLACE_ISWCNTRL"
+  else
+    AC_CACHE_CHECK([whether iswdigit is ISO C compliant],
+      [gl_cv_func_iswdigit_works],
+      [
+       dnl Initial guess, used when cross-compiling or when no suitable locale
+       dnl is present.
+changequote(,)dnl
+       case "$host_os" in
+         # Guess no on FreeBSD, NetBSD, Solaris, native Windows.
+         freebsd* | dragonfly* | netbsd* | solaris* | mingw*)
+           gl_cv_func_iswdigit_works="guessing no" ;;
+         # Guess yes otherwise.
+         *) gl_cv_func_iswdigit_works="guessing yes" ;;
+       esac
+changequote([,])dnl
+       if test $LOCALE_FR != none || test $LOCALE_JA != none || test $LOCALE_FR_UTF8 != none || test $LOCALE_ZH_CN != none; then
+         AC_RUN_IFELSE(
+           [AC_LANG_SOURCE([[
+#include <locale.h>
+#include <stdlib.h>
+#include <string.h>
+#include <wchar.h>
+#include <wctype.h>
+
+/* Returns the value of iswdigit for the multibyte character s[0..n-1].  */
+static int
+for_character (const char *s, size_t n)
+{
+  mbstate_t state;
+  wchar_t wc;
+  size_t ret;
+
+  memset (&state, '\0', sizeof (mbstate_t));
+  wc = (wchar_t) 0xBADFACE;
+  ret = mbrtowc (&wc, s, n, &state);
+  if (ret != n)
+    abort ();
+
+  return iswdigit (wc);
+}
+
+int
+main (int argc, char *argv[])
+{
+  int is;
+  int result = 0;
+
+  if (setlocale (LC_ALL, "$LOCALE_FR") != NULL)
+    {
+      /* This fails on mingw, MSVC 14.  */
+      /* U+00B2 SUPERSCRIPT TWO */
+      is = for_character ("\262", 1);
+      if (!(is == 0))
+        result |= 1;
+    }
+  if (setlocale (LC_ALL, "$LOCALE_JA") != NULL)
+    {
+      /* This fails on NetBSD 8.0.  */
+      /* U+FF11 FULLWIDTH DIGIT ONE */
+      is = for_character ("\243\261", 2);
+      if (!(is == 0))
+        result |= 2;
+    }
+  if (setlocale (LC_ALL, "$LOCALE_FR_UTF8") != NULL)
+    {
+      /* This fails on FreeBSD 12, NetBSD 8.0, MSVC 14.  */
+      /* U+0663 ARABIC-INDIC DIGIT THREE */
+      is = for_character ("\331\243", 2);
+      if (!(is == 0))
+        result |= 4;
+      /* This fails on FreeBSD 12, NetBSD 8.0, MSVC 14.  */
+      /* U+FF11 FULLWIDTH DIGIT ONE */
+      is = for_character ("\357\274\221", 3);
+      if (!(is == 0))
+        result |= 8;
+    }
+  if (setlocale (LC_ALL, "$LOCALE_ZH_CN") != NULL)
+    {
+      /* This fails on NetBSD 8.0, Solaris 10, Solaris 11.4.  */
+      /* U+FF11 FULLWIDTH DIGIT ONE */
+      is = for_character ("\243\261", 2);
+      if (!(is == 0))
+        result |= 16;
+    }
+  return result;
+}]])],
+           [gl_cv_func_iswdigit_works=yes],
+           [gl_cv_func_iswdigit_works=no],
+           [:])
+       fi
+      ])
+    case "$gl_cv_func_iswdigit_works" in
+      *yes) ;;
+      *) REPLACE_ISWDIGIT=1 ;;
+    esac
+  fi
+])
diff --git a/m4/iswxdigit.m4 b/m4/iswxdigit.m4
new file mode 100644
index 0000000..c63e81e
--- /dev/null
+++ b/m4/iswxdigit.m4
@@ -0,0 +1,106 @@
+# iswxdigit.m4 serial 2
+dnl Copyright (C) 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_FUNC_ISWXDIGIT],
+[
+  AC_REQUIRE([gl_WCTYPE_H_DEFAULTS])
+  AC_REQUIRE([gl_WCTYPE_H])
+  AC_REQUIRE([gt_LOCALE_JA])
+  AC_REQUIRE([gt_LOCALE_FR_UTF8])
+  AC_REQUIRE([gt_LOCALE_ZH_CN])
+
+  if test $HAVE_ISWCNTRL = 0 || test $REPLACE_ISWCNTRL = 1; then
+    dnl <wctype.h> redefines iswxdigit already.
+    REPLACE_ISWXDIGIT="$REPLACE_ISWCNTRL"
+  else
+    AC_CACHE_CHECK([whether iswxdigit is ISO C compliant],
+      [gl_cv_func_iswxdigit_works],
+      [
+       dnl Initial guess, used when cross-compiling or when no suitable locale
+       dnl is present.
+changequote(,)dnl
+       case "$host_os" in
+         # Guess no on FreeBSD, NetBSD, Solaris, native Windows.
+         freebsd* | dragonfly* | netbsd* | solaris* | mingw*)
+           gl_cv_func_iswxdigit_works="guessing no" ;;
+         # Guess yes otherwise.
+         *) gl_cv_func_iswxdigit_works="guessing yes" ;;
+       esac
+changequote([,])dnl
+       if test $LOCALE_JA != none || test $LOCALE_FR_UTF8 != none || test $LOCALE_ZH_CN != none; then
+         AC_RUN_IFELSE(
+           [AC_LANG_SOURCE([[
+#include <locale.h>
+#include <stdlib.h>
+#include <string.h>
+#include <wchar.h>
+#include <wctype.h>
+
+/* Returns the value of iswxdigit for the multibyte character s[0..n-1].  */
+static int
+for_character (const char *s, size_t n)
+{
+  mbstate_t state;
+  wchar_t wc;
+  size_t ret;
+
+  memset (&state, '\0', sizeof (mbstate_t));
+  wc = (wchar_t) 0xBADFACE;
+  ret = mbrtowc (&wc, s, n, &state);
+  if (ret != n)
+    abort ();
+
+  return iswxdigit (wc);
+}
+
+int
+main (int argc, char *argv[])
+{
+  int is;
+  int result = 0;
+
+  if (setlocale (LC_ALL, "$LOCALE_JA") != NULL)
+    {
+      /* This fails on NetBSD 8.0.  */
+      /* U+FF21 FULLWIDTH LATIN CAPITAL LETTER A */
+      is = for_character ("\243\301", 2);
+      if (!(is == 0))
+        result |= 1;
+    }
+  if (setlocale (LC_ALL, "$LOCALE_FR_UTF8") != NULL)
+    {
+      /* This fails on FreeBSD 12.  */
+      /* U+0663 ARABIC-INDIC DIGIT THREE */
+      is = for_character ("\331\243", 2);
+      if (!(is == 0))
+        result |= 2;
+      /* This fails on MSVC 14.  */
+      /* U+FF21 FULLWIDTH LATIN CAPITAL LETTER A */
+      is = for_character ("\357\274\241", 3);
+      if (!(is == 0))
+        result |= 4;
+    }
+  if (setlocale (LC_ALL, "$LOCALE_ZH_CN") != NULL)
+    {
+      /* This fails on Solaris 10, Solaris 11.4.  */
+      /* U+FF11 FULLWIDTH DIGIT ONE */
+      is = for_character ("\243\261", 2);
+      if (!(is == 0))
+        result |= 8;
+    }
+  return result;
+}]])],
+           [gl_cv_func_iswxdigit_works=yes],
+           [gl_cv_func_iswxdigit_works=no],
+           [:])
+       fi
+      ])
+    case "$gl_cv_func_iswxdigit_works" in
+      *yes) ;;
+      *) REPLACE_ISWXDIGIT=1 ;;
+    esac
+  fi
+])
diff --git a/m4/langinfo_h.m4 b/m4/langinfo_h.m4
index 76385d8..9d5e16e 100644
--- a/m4/langinfo_h.m4
+++ b/m4/langinfo_h.m4
@@ -1,5 +1,5 @@
-# langinfo_h.m4 serial 8
-dnl Copyright (C) 2009-2019 Free Software Foundation, Inc.
+# langinfo_h.m4 serial 9
+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.
@@ -23,8 +23,10 @@ AC_DEFUN([gl_LANGINFO_H],
   AC_CHECK_HEADERS_ONCE([langinfo.h])
   if test $ac_cv_header_langinfo_h = yes; then
     HAVE_LANGINFO_H=1
-    dnl Determine what <langinfo.h> defines. CODESET and ERA etc. are missing
-    dnl on OpenBSD 3.8. T_FMT_AMPM and YESEXPR, NOEXPR are missing on IRIX 5.3.
+    dnl Determine what <langinfo.h> defines.
+    dnl CODESET is missing on OpenBSD 3.8.
+    dnl ERA etc. are missing on OpenBSD 6.7.
+    dnl T_FMT_AMPM and YESEXPR, NOEXPR are missing on IRIX 5.3.
     dnl ALTMON_* are missing on glibc 2.26 and many other systems.
     AC_CACHE_CHECK([whether langinfo.h defines CODESET],
       [gl_cv_header_langinfo_codeset],
diff --git a/m4/largefile.m4 b/m4/largefile.m4
index 1938188..c4cc835 100644
--- a/m4/largefile.m4
+++ b/m4/largefile.m4
@@ -1,24 +1,41 @@
 # Enable large files on systems where this is not the default.
+# Enable support for files on Linux file systems with 64-bit inode numbers.
 
-# Copyright 1992-1996, 1998-2019 Free Software Foundation, Inc.
+# Copyright 1992-1996, 1998-2020 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.
 
+# The following macro works around a problem in Autoconf's AC_FUNC_FSEEKO:
+# It does not set _LARGEFILE_SOURCE=1 on HP-UX/ia64 32-bit, although this
+# setting of _LARGEFILE_SOURCE is needed so that <stdio.h> declares fseeko
+# and ftello in C++ mode as well.
+AC_DEFUN([gl_SET_LARGEFILE_SOURCE],
+[
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  AC_FUNC_FSEEKO
+  case "$host_os" in
+    hpux*)
+      AC_DEFINE([_LARGEFILE_SOURCE], [1],
+        [Define to 1 to make fseeko visible on some hosts (e.g. glibc 2.2).])
+      ;;
+  esac
+])
+
 # The following implementation works around a problem in autoconf <= 2.69;
 # AC_SYS_LARGEFILE does not configure for large inodes on Mac OS X 10.5,
 # or configures them incorrectly in some cases.
-m4_version_prereq([2.70], [] ,[
+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 << 62) - 1 + ((off_t) 1 << 62))
+#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
@@ -37,7 +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])
   $3=unknown
@@ -56,7 +73,10 @@ rm -rf conftest*[]dnl
 # By default, many hosts won't let programs access large files;
 # one must use special compiler options to get large-file access to work.
 # For more details about this brain damage please see:
-# http://www.unix-systems.org/version2/whatsnew/lfs20mar.html
+# http://www.unix.org/version2/whatsnew/lfs20mar.html
+# Additionally, on Linux file systems with 64-bit inodes a file that happens
+# to have a 64-bit inode number cannot be accessed by 32-bit applications on
+# Linux x86/x86_64.  This can occur with file systems such as XFS and NFS.
 AC_DEFUN([AC_SYS_LARGEFILE],
 [AC_ARG_ENABLE(largefile,
                [  --disable-largefile     omit support for large files])
@@ -93,9 +113,6 @@ if test "$enable_largefile" != no; then
       [Define for large files, on AIX-style hosts.],
       [_AC_SYS_LARGEFILE_TEST_INCLUDES])
   fi
-
-  AC_DEFINE([_DARWIN_USE_64_BIT_INODE], [1],
-    [Enable large inode numbers on Mac OS X 10.5.])
 fi
 ])# AC_SYS_LARGEFILE
 ])# m4_version_prereq 2.70
diff --git a/m4/lib-ld.m4 b/m4/lib-ld.m4
index a187196..98c348f 100644
--- a/m4/lib-ld.m4
+++ b/m4/lib-ld.m4
@@ -1,5 +1,5 @@
 # lib-ld.m4 serial 9
-dnl Copyright (C) 1996-2003, 2009-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 1996-2003, 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.
diff --git a/m4/lib-link.m4 b/m4/lib-link.m4
index 0ff1073..5ce1aa2 100644
--- a/m4/lib-link.m4
+++ b/m4/lib-link.m4
@@ -1,5 +1,5 @@
-# lib-link.m4 serial 28
-dnl Copyright (C) 2001-2019 Free Software Foundation, Inc.
+# lib-link.m4 serial 32
+dnl Copyright (C) 2001-2020 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.
@@ -192,6 +192,8 @@ AC_DEFUN([AC_LIB_LINKFLAGS_BODY],
   AC_LIB_WITH_FINAL_PREFIX([
     eval additional_includedir=\"$includedir\"
     eval additional_libdir=\"$libdir\"
+    eval additional_libdir2=\"$exec_prefix/$acl_libdirstem2\"
+    eval additional_libdir3=\"$exec_prefix/$acl_libdirstem3\"
   ])
   AC_ARG_WITH(PACK[-prefix],
 [[  --with-]]PACK[[-prefix[=DIR]  search for ]PACKLIBS[ in DIR/include and DIR/lib
@@ -204,17 +206,23 @@ AC_DEFUN([AC_LIB_LINKFLAGS_BODY],
         AC_LIB_WITH_FINAL_PREFIX([
           eval additional_includedir=\"$includedir\"
           eval additional_libdir=\"$libdir\"
+          eval additional_libdir2=\"$exec_prefix/$acl_libdirstem2\"
+          eval additional_libdir3=\"$exec_prefix/$acl_libdirstem3\"
         ])
       else
         additional_includedir="$withval/include"
         additional_libdir="$withval/$acl_libdirstem"
-        if test "$acl_libdirstem2" != "$acl_libdirstem" \
-           && test ! -d "$withval/$acl_libdirstem"; then
-          additional_libdir="$withval/$acl_libdirstem2"
-        fi
+        additional_libdir2="$withval/$acl_libdirstem2"
+        additional_libdir3="$withval/$acl_libdirstem3"
       fi
     fi
 ])
+  if test "X$additional_libdir2" = "X$additional_libdir"; then
+    additional_libdir2=
+  fi
+  if test "X$additional_libdir3" = "X$additional_libdir"; then
+    additional_libdir3=
+  fi
   dnl Search the library and its dependencies in $additional_libdir and
   dnl $LDFLAGS. Using breadth-first-seach.
   LIB[]NAME=
@@ -270,48 +278,54 @@ AC_DEFUN([AC_LIB_LINKFLAGS_BODY],
             shrext=
           fi
           if test $use_additional = yes; then
-            dir="$additional_libdir"
-            dnl The same code as in the loop below:
-            dnl First look for a shared library.
-            if test -n "$acl_shlibext"; then
-              if test -f "$dir/$libname$shrext"; then
-                found_dir="$dir"
-                found_so="$dir/$libname$shrext"
-              else
-                if test "$acl_library_names_spec" = '$libname$shrext$versuffix'; then
-                  ver=`(cd "$dir" && \
-                        for f in "$libname$shrext".*; do echo "$f"; done \
-                        | sed -e "s,^$libname$shrext\\\\.,," \
-                        | sort -t '.' -n -r -k1,1 -k2,2 -k3,3 -k4,4 -k5,5 \
-                        | sed 1q ) 2>/dev/null`
-                  if test -n "$ver" && test -f "$dir/$libname$shrext.$ver"; then
-                    found_dir="$dir"
-                    found_so="$dir/$libname$shrext.$ver"
+            for additional_libdir_variable in additional_libdir additional_libdir2 additional_libdir3; do
+              if test "X$found_dir" = "X"; then
+                eval dir=\$$additional_libdir_variable
+                if test -n "$dir"; then
+                  dnl The same code as in the loop below:
+                  dnl First look for a shared library.
+                  if test -n "$acl_shlibext"; then
+                    if test -f "$dir/$libname$shrext" && acl_is_expected_elfclass < "$dir/$libname$shrext"; then
+                      found_dir="$dir"
+                      found_so="$dir/$libname$shrext"
+                    else
+                      if test "$acl_library_names_spec" = '$libname$shrext$versuffix'; then
+                        ver=`(cd "$dir" && \
+                              for f in "$libname$shrext".*; do echo "$f"; done \
+                              | sed -e "s,^$libname$shrext\\\\.,," \
+                              | sort -t '.' -n -r -k1,1 -k2,2 -k3,3 -k4,4 -k5,5 \
+                              | sed 1q ) 2>/dev/null`
+                        if test -n "$ver" && test -f "$dir/$libname$shrext.$ver" && acl_is_expected_elfclass < "$dir/$libname$shrext.$ver"; then
+                          found_dir="$dir"
+                          found_so="$dir/$libname$shrext.$ver"
+                        fi
+                      else
+                        eval library_names=\"$acl_library_names_spec\"
+                        for f in $library_names; do
+                          if test -f "$dir/$f" && acl_is_expected_elfclass < "$dir/$f"; then
+                            found_dir="$dir"
+                            found_so="$dir/$f"
+                            break
+                          fi
+                        done
+                      fi
+                    fi
                   fi
-                else
-                  eval library_names=\"$acl_library_names_spec\"
-                  for f in $library_names; do
-                    if test -f "$dir/$f"; then
+                  dnl Then look for a static library.
+                  if test "X$found_dir" = "X"; then
+                    if test -f "$dir/$libname.$acl_libext" && ${AR-ar} -p "$dir/$libname.$acl_libext" | acl_is_expected_elfclass; then
                       found_dir="$dir"
-                      found_so="$dir/$f"
-                      break
+                      found_a="$dir/$libname.$acl_libext"
                     fi
-                  done
+                  fi
+                  if test "X$found_dir" != "X"; then
+                    if test -f "$dir/$libname.la"; then
+                      found_la="$dir/$libname.la"
+                    fi
+                  fi
                 fi
               fi
-            fi
-            dnl Then look for a static library.
-            if test "X$found_dir" = "X"; then
-              if test -f "$dir/$libname.$acl_libext"; then
-                found_dir="$dir"
-                found_a="$dir/$libname.$acl_libext"
-              fi
-            fi
-            if test "X$found_dir" != "X"; then
-              if test -f "$dir/$libname.la"; then
-                found_la="$dir/$libname.la"
-              fi
-            fi
+            done
           fi
           if test "X$found_dir" = "X"; then
             for x in $LDFLAGS $LTLIB[]NAME; do
@@ -321,7 +335,7 @@ AC_DEFUN([AC_LIB_LINKFLAGS_BODY],
                   dir=`echo "X$x" | sed -e 's/^X-L//'`
                   dnl First look for a shared library.
                   if test -n "$acl_shlibext"; then
-                    if test -f "$dir/$libname$shrext"; then
+                    if test -f "$dir/$libname$shrext" && acl_is_expected_elfclass < "$dir/$libname$shrext"; then
                       found_dir="$dir"
                       found_so="$dir/$libname$shrext"
                     else
@@ -331,14 +345,14 @@ AC_DEFUN([AC_LIB_LINKFLAGS_BODY],
                               | sed -e "s,^$libname$shrext\\\\.,," \
                               | sort -t '.' -n -r -k1,1 -k2,2 -k3,3 -k4,4 -k5,5 \
                               | sed 1q ) 2>/dev/null`
-                        if test -n "$ver" && test -f "$dir/$libname$shrext.$ver"; then
+                        if test -n "$ver" && test -f "$dir/$libname$shrext.$ver" && acl_is_expected_elfclass < "$dir/$libname$shrext.$ver"; then
                           found_dir="$dir"
                           found_so="$dir/$libname$shrext.$ver"
                         fi
                       else
                         eval library_names=\"$acl_library_names_spec\"
                         for f in $library_names; do
-                          if test -f "$dir/$f"; then
+                          if test -f "$dir/$f" && acl_is_expected_elfclass < "$dir/$f"; then
                             found_dir="$dir"
                             found_so="$dir/$f"
                             break
@@ -349,7 +363,7 @@ AC_DEFUN([AC_LIB_LINKFLAGS_BODY],
                   fi
                   dnl Then look for a static library.
                   if test "X$found_dir" = "X"; then
-                    if test -f "$dir/$libname.$acl_libext"; then
+                    if test -f "$dir/$libname.$acl_libext" && ${AR-ar} -p "$dir/$libname.$acl_libext" | acl_is_expected_elfclass; then
                       found_dir="$dir"
                       found_a="$dir/$libname.$acl_libext"
                     fi
@@ -375,7 +389,8 @@ AC_DEFUN([AC_LIB_LINKFLAGS_BODY],
               dnl standard /usr/lib.
               if test "$enable_rpath" = no \
                  || test "X$found_dir" = "X/usr/$acl_libdirstem" \
-                 || test "X$found_dir" = "X/usr/$acl_libdirstem2"; then
+                 || test "X$found_dir" = "X/usr/$acl_libdirstem2" \
+                 || test "X$found_dir" = "X/usr/$acl_libdirstem3"; then
                 dnl No hardcoding is needed.
                 LIB[]NAME="${LIB[]NAME}${LIB[]NAME:+ }$found_so"
               else
@@ -475,6 +490,13 @@ AC_DEFUN([AC_LIB_LINKFLAGS_BODY],
                 fi
                 additional_includedir="$basedir/include"
                 ;;
+              */$acl_libdirstem3 | */$acl_libdirstem3/)
+                basedir=`echo "X$found_dir" | sed -e 's,^X,,' -e "s,/$acl_libdirstem3/"'*$,,'`
+                if test "$name" = '$1'; then
+                  LIB[]NAME[]_PREFIX="$basedir"
+                fi
+                additional_includedir="$basedir/include"
+                ;;
             esac
             if test "X$additional_includedir" != "X"; then
               dnl Potentially add $additional_includedir to $INCNAME.
@@ -525,19 +547,21 @@ AC_DEFUN([AC_LIB_LINKFLAGS_BODY],
               for dep in $dependency_libs; do
                 case "$dep" in
                   -L*)
-                    additional_libdir=`echo "X$dep" | sed -e 's/^X-L//'`
-                    dnl Potentially add $additional_libdir to $LIBNAME and $LTLIBNAME.
+                    dependency_libdir=`echo "X$dep" | sed -e 's/^X-L//'`
+                    dnl Potentially add $dependency_libdir to $LIBNAME and $LTLIBNAME.
                     dnl But don't add it
                     dnl   1. if it's the standard /usr/lib,
                     dnl   2. if it's /usr/local/lib and we are using GCC on Linux,
                     dnl   3. if it's already present in $LDFLAGS or the already
                     dnl      constructed $LIBNAME,
                     dnl   4. if it doesn't exist as a directory.
-                    if test "X$additional_libdir" != "X/usr/$acl_libdirstem" \
-                       && test "X$additional_libdir" != "X/usr/$acl_libdirstem2"; then
+                    if test "X$dependency_libdir" != "X/usr/$acl_libdirstem" \
+                       && test "X$dependency_libdir" != "X/usr/$acl_libdirstem2" \
+                       && test "X$dependency_libdir" != "X/usr/$acl_libdirstem3"; then
                       haveit=
-                      if test "X$additional_libdir" = "X/usr/local/$acl_libdirstem" \
-                         || test "X$additional_libdir" = "X/usr/local/$acl_libdirstem2"; then
+                      if test "X$dependency_libdir" = "X/usr/local/$acl_libdirstem" \
+                         || test "X$dependency_libdir" = "X/usr/local/$acl_libdirstem2" \
+                         || test "X$dependency_libdir" = "X/usr/local/$acl_libdirstem3"; then
                         if test -n "$GCC"; then
                           case $host_os in
                             linux* | gnu* | k*bsd*-gnu) haveit=yes;;
@@ -548,29 +572,29 @@ AC_DEFUN([AC_LIB_LINKFLAGS_BODY],
                         haveit=
                         for x in $LDFLAGS $LIB[]NAME; do
                           AC_LIB_WITH_FINAL_PREFIX([eval x=\"$x\"])
-                          if test "X$x" = "X-L$additional_libdir"; then
+                          if test "X$x" = "X-L$dependency_libdir"; then
                             haveit=yes
                             break
                           fi
                         done
                         if test -z "$haveit"; then
-                          if test -d "$additional_libdir"; then
-                            dnl Really add $additional_libdir to $LIBNAME.
-                            LIB[]NAME="${LIB[]NAME}${LIB[]NAME:+ }-L$additional_libdir"
+                          if test -d "$dependency_libdir"; then
+                            dnl Really add $dependency_libdir to $LIBNAME.
+                            LIB[]NAME="${LIB[]NAME}${LIB[]NAME:+ }-L$dependency_libdir"
                           fi
                         fi
                         haveit=
                         for x in $LDFLAGS $LTLIB[]NAME; do
                           AC_LIB_WITH_FINAL_PREFIX([eval x=\"$x\"])
-                          if test "X$x" = "X-L$additional_libdir"; then
+                          if test "X$x" = "X-L$dependency_libdir"; then
                             haveit=yes
                             break
                           fi
                         done
                         if test -z "$haveit"; then
-                          if test -d "$additional_libdir"; then
-                            dnl Really add $additional_libdir to $LTLIBNAME.
-                            LTLIB[]NAME="${LTLIB[]NAME}${LTLIB[]NAME:+ }-L$additional_libdir"
+                          if test -d "$dependency_libdir"; then
+                            dnl Really add $dependency_libdir to $LTLIBNAME.
+                            LTLIB[]NAME="${LTLIB[]NAME}${LTLIB[]NAME:+ }-L$dependency_libdir"
                           fi
                         fi
                       fi
@@ -607,7 +631,20 @@ AC_DEFUN([AC_LIB_LINKFLAGS_BODY],
                     ;;
                   -l*)
                     dnl Handle this in the next round.
-                    names_next_round="$names_next_round "`echo "X$dep" | sed -e 's/^X-l//'`
+                    dnl But on GNU systems, ignore -lc options, because
+                    dnl   - linking with libc is the default anyway,
+                    dnl   - linking with libc.a may produce an error
+                    dnl     "/usr/bin/ld: dynamic STT_GNU_IFUNC symbol `strcmp' with pointer equality in `/usr/lib/libc.a(strcmp.o)' can not be used when making an executable; recompile with -fPIE and relink with -pie"
+                    dnl     or may produce an executable that always crashes, see
+                    dnl     <https://lists.gnu.org/archive/html/grep-devel/2020-09/msg00052.html>.
+                    dep=`echo "X$dep" | sed -e 's/^X-l//'`
+                    if test "X$dep" != Xc \
+                       || case $host_os in
+                            linux* | gnu* | k*bsd*-gnu) false ;;
+                            *)                          true ;;
+                          esac; then
+                      names_next_round="$names_next_round $dep"
+                    fi
                     ;;
                   *.la)
                     dnl Handle this in the next round. Throw away the .la's
@@ -718,7 +755,8 @@ AC_DEFUN([AC_LIB_LINKFLAGS_FROM_LIBS],
           dir="$next"
           dnl No need to hardcode the standard /usr/lib.
           if test "X$dir" != "X/usr/$acl_libdirstem" \
-             && test "X$dir" != "X/usr/$acl_libdirstem2"; then
+             && test "X$dir" != "X/usr/$acl_libdirstem2" \
+             && test "X$dir" != "X/usr/$acl_libdirstem3"; then
             rpathdirs="$rpathdirs $dir"
           fi
           next=
@@ -728,7 +766,8 @@ AC_DEFUN([AC_LIB_LINKFLAGS_FROM_LIBS],
             -L*) dir=`echo "X$opt" | sed -e 's,^X-L,,'`
                  dnl No need to hardcode the standard /usr/lib.
                  if test "X$dir" != "X/usr/$acl_libdirstem" \
-                    && test "X$dir" != "X/usr/$acl_libdirstem2"; then
+                    && test "X$dir" != "X/usr/$acl_libdirstem2" \
+                    && test "X$dir" != "X/usr/$acl_libdirstem3"; then
                    rpathdirs="$rpathdirs $dir"
                  fi
                  next= ;;
diff --git a/m4/lib-prefix.m4 b/m4/lib-prefix.m4
index 8adb17b..2bcdfdf 100644
--- a/m4/lib-prefix.m4
+++ b/m4/lib-prefix.m4
@@ -1,5 +1,5 @@
-# lib-prefix.m4 serial 14
-dnl Copyright (C) 2001-2005, 2008-2019 Free Software Foundation, Inc.
+# lib-prefix.m4 serial 19
+dnl Copyright (C) 2001-2005, 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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -147,21 +147,24 @@ AC_DEFUN([AC_LIB_WITH_FINAL_PREFIX],
 ])
 
 dnl AC_LIB_PREPARE_MULTILIB creates
-dnl - a variable acl_libdirstem, containing the basename of the libdir, either
-dnl   "lib" or "lib64" or "lib/64",
-dnl - a variable acl_libdirstem2, as a secondary possible value for
-dnl   acl_libdirstem, either the same as acl_libdirstem or "lib/sparcv9" or
-dnl   "lib/amd64".
+dnl - a function acl_is_expected_elfclass, that tests whether standard input
+dn;   has a 32-bit or 64-bit ELF header, depending on the host CPU ABI,
+dnl - 3 variables acl_libdirstem, acl_libdirstem2, acl_libdirstem3, containing
+dnl   the basename of the libdir to try in turn, either "lib" or "lib64" or
+dnl   "lib/64" or "lib32" or "lib/sparcv9" or "lib/amd64" or similar.
 AC_DEFUN([AC_LIB_PREPARE_MULTILIB],
 [
-  dnl There is no formal standard regarding lib and lib64.
-  dnl On glibc systems, the current practice is that on a system supporting
+  dnl There is no formal standard regarding lib, lib32, and lib64.
+  dnl On most glibc systems, the current practice is that on a system supporting
   dnl 32-bit and 64-bit instruction sets or ABIs, 64-bit libraries go under
-  dnl $prefix/lib64 and 32-bit libraries go under $prefix/lib. We determine
-  dnl the compiler's default mode by looking at the compiler's library search
-  dnl path. If at least one of its elements ends in /lib64 or points to a
-  dnl directory whose absolute pathname ends in /lib64, we assume a 64-bit ABI.
-  dnl Otherwise we use the default, namely "lib".
+  dnl $prefix/lib64 and 32-bit libraries go under $prefix/lib. However, on
+  dnl Arch Linux based distributions, it's the opposite: 32-bit libraries go
+  dnl under $prefix/lib32 and 64-bit libraries go under $prefix/lib.
+  dnl We determine the compiler's default mode by looking at the compiler's
+  dnl library search path. If at least one of its elements ends in /lib64 or
+  dnl points to a directory whose absolute pathname ends in /lib64, we use that
+  dnl for 64-bit ABIs. Similarly for 32-bit ABIs. Otherwise we use the default,
+  dnl namely "lib".
   dnl On Solaris systems, the current practice is that on a system supporting
   dnl 32-bit and 64-bit instruction sets or ABIs, 64-bit libraries go under
   dnl $prefix/lib/64 (which is a symlink to either $prefix/lib/sparcv9 or
@@ -169,27 +172,75 @@ AC_DEFUN([AC_LIB_PREPARE_MULTILIB],
   AC_REQUIRE([AC_CANONICAL_HOST])
   AC_REQUIRE([gl_HOST_CPU_C_ABI_32BIT])
 
-  case "$host_os" in
-    solaris*)
-      AC_CACHE_CHECK([for 64-bit host], [gl_cv_solaris_64bit],
-        [AC_COMPILE_IFELSE(
-           [AC_LANG_SOURCE(
-              [[#ifdef _LP64
-                 int ok;
-                #else
-                 error fail
-                #endif
-              ]])],
-           [gl_cv_solaris_64bit=yes],
-           [gl_cv_solaris_64bit=no])
-        ]);;
-  esac
+  AC_CACHE_CHECK([for ELF binary format], [gl_cv_elf],
+    [AC_EGREP_CPP([Extensible Linking Format],
+       [#ifdef __ELF__
+        Extensible Linking Format
+        #endif
+       ],
+       [gl_cv_elf=yes],
+       [gl_cv_elf=no])
+    ])
+  if test $gl_cv_elf = yes; then
+    # Extract the ELF class of a file (5th byte) in decimal.
+    # Cf. https://en.wikipedia.org/wiki/Executable_and_Linkable_Format#File_header
+    if od -A x < /dev/null >/dev/null 2>/dev/null; then
+      # Use POSIX od.
+      func_elfclass ()
+      {
+        od -A n -t d1 -j 4 -N 1
+      }
+    else
+      # Use BSD hexdump.
+      func_elfclass ()
+      {
+        dd bs=1 count=1 skip=4 2>/dev/null | hexdump -e '1/1 "%3d "'
+        echo
+      }
+    fi
+    # Use 'expr', not 'test', to compare the values of func_elfclass, because on
+    # Solaris 11 OpenIndiana and Solaris 11 OmniOS, the result is 001 or 002,
+    # not 1 or 2.
+changequote(,)dnl
+    case $HOST_CPU_C_ABI_32BIT in
+      yes)
+        # 32-bit ABI.
+        acl_is_expected_elfclass ()
+        {
+          expr "`func_elfclass | sed -e 's/[ 	]//g'`" = 1 > /dev/null
+        }
+        ;;
+      no)
+        # 64-bit ABI.
+        acl_is_expected_elfclass ()
+        {
+          expr "`func_elfclass | sed -e 's/[ 	]//g'`" = 2 > /dev/null
+        }
+        ;;
+      *)
+        # Unknown.
+        acl_is_expected_elfclass ()
+        {
+          :
+        }
+        ;;
+    esac
+changequote([,])dnl
+  else
+    acl_is_expected_elfclass ()
+    {
+      :
+    }
+  fi
 
   dnl Allow the user to override the result by setting acl_cv_libdirstems.
   AC_CACHE_CHECK([for the common suffixes of directories in the library search path],
     [acl_cv_libdirstems],
-    [acl_libdirstem=lib
+    [dnl Try 'lib' first, because that's the default for libdir in GNU, see
+     dnl <https://www.gnu.org/prep/standards/html_node/Directory-Variables.html>.
+     acl_libdirstem=lib
      acl_libdirstem2=
+     acl_libdirstem3=
      case "$host_os" in
        solaris*)
          dnl See Solaris 10 Software Developer Collection > Solaris 64-bit Developer's Guide > The Development Environment
@@ -197,53 +248,76 @@ AC_DEFUN([AC_LIB_PREPARE_MULTILIB],
          dnl "Portable Makefiles should refer to any library directories using the 64 symbolic link."
          dnl But we want to recognize the sparcv9 or amd64 subdirectory also if the
          dnl symlink is missing, so we set acl_libdirstem2 too.
-         if test $gl_cv_solaris_64bit = yes; then
-           acl_libdirstem=lib/64
+         if test $HOST_CPU_C_ABI_32BIT = no; then
+           acl_libdirstem2=lib/64
            case "$host_cpu" in
-             sparc*)        acl_libdirstem2=lib/sparcv9 ;;
-             i*86 | x86_64) acl_libdirstem2=lib/amd64 ;;
+             sparc*)        acl_libdirstem3=lib/sparcv9 ;;
+             i*86 | x86_64) acl_libdirstem3=lib/amd64 ;;
            esac
          fi
          ;;
        *)
          dnl If $CC generates code for a 32-bit ABI, the libraries are
-         dnl surely under $prefix/lib, not $prefix/lib64.
-         if test "$HOST_CPU_C_ABI_32BIT" != yes; then
-           dnl The result is a property of the system. However, non-system
-           dnl compilers sometimes have odd library search paths. Therefore
-           dnl prefer asking /usr/bin/gcc, if available, rather than $CC.
-           searchpath=`(if test -f /usr/bin/gcc \
-                           && LC_ALL=C /usr/bin/gcc -print-search-dirs >/dev/null 2>/dev/null; then \
-                          LC_ALL=C /usr/bin/gcc -print-search-dirs; \
-                        else \
-                          LC_ALL=C $CC -print-search-dirs; \
-                        fi) 2>/dev/null \
-                       | sed -n -e 's,^libraries: ,,p' | sed -e 's,^=,,'`
-           if test -n "$searchpath"; then
-             acl_save_IFS="${IFS= 	}"; IFS=":"
-             for searchdir in $searchpath; do
-               if test -d "$searchdir"; then
-                 case "$searchdir" in
-                   */lib64/ | */lib64 ) acl_libdirstem=lib64 ;;
-                   */../ | */.. )
-                     # Better ignore directories of this form. They are misleading.
-                     ;;
-                   *) searchdir=`cd "$searchdir" && pwd`
-                      case "$searchdir" in
-                        */lib64 ) acl_libdirstem=lib64 ;;
-                      esac ;;
-                 esac
-               fi
-             done
-             IFS="$acl_save_IFS"
+         dnl surely under $prefix/lib or $prefix/lib32, not $prefix/lib64.
+         dnl Similarly, if $CC generates code for a 64-bit ABI, the libraries
+         dnl are surely under $prefix/lib or $prefix/lib64, not $prefix/lib32.
+         dnl Find the compiler's search path. However, non-system compilers
+         dnl sometimes have odd library search paths. But we can't simply invoke
+         dnl '/usr/bin/gcc -print-search-dirs' because that would not take into
+         dnl account the -m32/-m31 or -m64 options from the $CC or $CFLAGS.
+         searchpath=`(LC_ALL=C $CC $CPPFLAGS $CFLAGS -print-search-dirs) 2>/dev/null \
+                     | sed -n -e 's,^libraries: ,,p' | sed -e 's,^=,,'`
+         if test $HOST_CPU_C_ABI_32BIT != no; then
+           # 32-bit or unknown ABI.
+           if test -d /usr/lib32; then
+             acl_libdirstem2=lib32
+           fi
+         fi
+         if test $HOST_CPU_C_ABI_32BIT != yes; then
+           # 64-bit or unknown ABI.
+           if test -d /usr/lib64; then
+             acl_libdirstem3=lib64
+           fi
+         fi
+         if test -n "$searchpath"; then
+           acl_save_IFS="${IFS= 	}"; IFS=":"
+           for searchdir in $searchpath; do
+             if test -d "$searchdir"; then
+               case "$searchdir" in
+                 */lib32/ | */lib32 ) acl_libdirstem2=lib32 ;;
+                 */lib64/ | */lib64 ) acl_libdirstem3=lib64 ;;
+                 */../ | */.. )
+                   # Better ignore directories of this form. They are misleading.
+                   ;;
+                 *) searchdir=`cd "$searchdir" && pwd`
+                    case "$searchdir" in
+                      */lib32 ) acl_libdirstem2=lib32 ;;
+                      */lib64 ) acl_libdirstem3=lib64 ;;
+                    esac ;;
+               esac
+             fi
+           done
+           IFS="$acl_save_IFS"
+           if test $HOST_CPU_C_ABI_32BIT = yes; then
+             # 32-bit ABI.
+             acl_libdirstem3=
+           fi
+           if test $HOST_CPU_C_ABI_32BIT = no; then
+             # 64-bit ABI.
+             acl_libdirstem2=
            fi
          fi
          ;;
      esac
      test -n "$acl_libdirstem2" || acl_libdirstem2="$acl_libdirstem"
-     acl_cv_libdirstems="$acl_libdirstem,$acl_libdirstem2"
+     test -n "$acl_libdirstem3" || acl_libdirstem3="$acl_libdirstem"
+     acl_cv_libdirstems="$acl_libdirstem,$acl_libdirstem2,$acl_libdirstem3"
     ])
-  # Decompose acl_cv_libdirstems into acl_libdirstem and acl_libdirstem2.
+  dnl Decompose acl_cv_libdirstems into acl_libdirstem, acl_libdirstem2, and
+  dnl acl_libdirstem3.
+changequote(,)dnl
   acl_libdirstem=`echo "$acl_cv_libdirstems" | sed -e 's/,.*//'`
-  acl_libdirstem2=`echo "$acl_cv_libdirstems" | sed -e '/,/s/.*,//'`
+  acl_libdirstem2=`echo "$acl_cv_libdirstems" | sed -e 's/^[^,]*,//' -e 's/,.*//'`
+  acl_libdirstem3=`echo "$acl_cv_libdirstems" | sed -e 's/^[^,]*,[^,]*,//' -e 's/,.*//'`
+changequote([,])dnl
 ])
diff --git a/m4/libunistring-base.m4 b/m4/libunistring-base.m4
index 829e71c..268ec5f 100644
--- a/m4/libunistring-base.m4
+++ b/m4/libunistring-base.m4
@@ -1,5 +1,5 @@
 # libunistring-base.m4 serial 5
-dnl Copyright (C) 2010-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2010-2020 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.
diff --git a/m4/libunistring-optional.m4 b/m4/libunistring-optional.m4
index 574b01a..f1a24c0 100644
--- a/m4/libunistring-optional.m4
+++ b/m4/libunistring-optional.m4
@@ -1,5 +1,5 @@
 # libunistring-optional.m4 serial 1
-dnl Copyright (C) 2010-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2010-2020 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.
diff --git a/m4/libunistring.m4 b/m4/libunistring.m4
index 23a6918..a0c36e3 100644
--- a/m4/libunistring.m4
+++ b/m4/libunistring.m4
@@ -1,9 +1,11 @@
-# libunistring.m4 serial 11
-dnl Copyright (C) 2009-2019 Free Software Foundation, Inc.
+# libunistring.m4 serial 12
+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.
 
+AC_PREREQ([2.64])
+
 dnl gl_LIBUNISTRING
 dnl Searches for an installed libunistring.
 dnl If found, it sets and AC_SUBSTs HAVE_LIBUNISTRING=yes and the LIBUNISTRING
@@ -12,8 +14,8 @@ dnl augments the CPPFLAGS variable, and #defines HAVE_LIBUNISTRING to 1.
 dnl Otherwise, it sets and AC_SUBSTs HAVE_LIBUNISTRING=no and LIBUNISTRING and
 dnl LTLIBUNISTRING to empty.
 
-dnl Define gl_LIBUNISTRING using AC_DEFUN_ONCE for Autoconf >= 2.64, in order
-dnl to avoid warnings like
+dnl Define gl_LIBUNISTRING using AC_DEFUN_ONCE, in order dnl to avoid warnings
+dnl like
 dnl "warning: AC_REQUIRE: `gl_LIBUNISTRING' was expanded before it was required".
 dnl This is tricky because of the way 'aclocal' is implemented:
 dnl - It requires defining an auxiliary macro whose name ends in AC_DEFUN.
@@ -21,16 +23,7 @@ dnl   Otherwise aclocal's initial scan pass would miss the macro definition.
 dnl - It requires a line break inside the AC_DEFUN_ONCE and AC_DEFUN expansions.
 dnl   Otherwise aclocal would emit many "Use of uninitialized value $1"
 dnl   warnings.
-m4_define([gl_libunistring_AC_DEFUN],
-  m4_version_prereq([2.64],
-    [[AC_DEFUN_ONCE(
-        [$1], [$2])]],
-    [m4_ifdef([gl_00GNULIB],
-       [[AC_DEFUN_ONCE(
-           [$1], [$2])]],
-       [[AC_DEFUN(
-           [$1], [$2])]])]))
-gl_libunistring_AC_DEFUN([gl_LIBUNISTRING],
+AC_DEFUN_ONCE([gl_LIBUNISTRING],
 [
   AC_BEFORE([$0], [gl_LIBUNISTRING_MODULE])
   AC_BEFORE([$0], [gl_LIBUNISTRING_LIBHEADER])
diff --git a/m4/limits-h.m4 b/m4/limits-h.m4
index 68f724c..0b4f092 100644
--- a/m4/limits-h.m4
+++ b/m4/limits-h.m4
@@ -1,6 +1,6 @@
 dnl Check whether limits.h has needed features.
 
-dnl Copyright 2016-2019 Free Software Foundation, Inc.
+dnl Copyright 2016-2020 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.
diff --git a/m4/link.m4 b/m4/link.m4
index a6d77b8..0d1de80 100644
--- a/m4/link.m4
+++ b/m4/link.m4
@@ -1,5 +1,5 @@
-# link.m4 serial 10
-dnl Copyright (C) 2009-2019 Free Software Foundation, Inc.
+# link.m4 serial 11
+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.
@@ -43,8 +43,8 @@ AC_DEFUN([gl_FUNC_LINK],
             linux-* | linux) gl_cv_func_link_works="guessing yes" ;;
                              # Guess yes on glibc systems.
             *-gnu* | gnu*)   gl_cv_func_link_works="guessing yes" ;;
-                             # If we don't know, assume the worst.
-            *)               gl_cv_func_link_works="guessing no" ;;
+                             # If we don't know, obey --enable-cross-guesses.
+            *)               gl_cv_func_link_works="$gl_cross_guess_normal" ;;
           esac
          ])
        rm -f conftest.a conftest.b conftest.lnk])
diff --git a/m4/localcharset.m4 b/m4/localcharset.m4
index 2a7f82d..9d21c4f 100644
--- a/m4/localcharset.m4
+++ b/m4/localcharset.m4
@@ -1,5 +1,5 @@
 # localcharset.m4 serial 8
-dnl Copyright (C) 2002, 2004, 2006, 2009-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2002, 2004, 2006, 2009-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/locale-fr.m4 b/m4/locale-fr.m4
index cfa068d..406951f 100644
--- a/m4/locale-fr.m4
+++ b/m4/locale-fr.m4
@@ -1,5 +1,5 @@
-# locale-fr.m4 serial 19
-dnl Copyright (C) 2003, 2005-2019 Free Software Foundation, Inc.
+# locale-fr.m4 serial 20
+dnl Copyright (C) 2003, 2005-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
@@ -12,8 +12,7 @@ AC_DEFUN([gt_LOCALE_FR],
   AC_REQUIRE([AC_CANONICAL_HOST])
   AC_REQUIRE([AM_LANGINFO_CODESET])
   AC_CACHE_CHECK([for a traditional french locale], [gt_cv_locale_fr], [
-    AC_LANG_CONFTEST([AC_LANG_SOURCE([
-changequote(,)dnl
+    AC_LANG_CONFTEST([AC_LANG_SOURCE([[
 #include <locale.h>
 #include <time.h>
 #if HAVE_LANGINFO_CODESET
@@ -78,8 +77,7 @@ int main () {
   return 0;
 #endif
 }
-changequote([,])dnl
-      ])])
+      ]])])
     if AC_TRY_EVAL([ac_link]) && test -s conftest$ac_exeext; then
       case "$host_os" in
         # Handle native Windows specially, because there setlocale() interprets
@@ -143,8 +141,7 @@ AC_DEFUN([gt_LOCALE_FR_UTF8],
 [
   AC_REQUIRE([AM_LANGINFO_CODESET])
   AC_CACHE_CHECK([for a french Unicode locale], [gt_cv_locale_fr_utf8], [
-    AC_LANG_CONFTEST([AC_LANG_SOURCE([
-changequote(,)dnl
+    AC_LANG_CONFTEST([AC_LANG_SOURCE([[
 #include <locale.h>
 #include <time.h>
 #if HAVE_LANGINFO_CODESET
@@ -206,8 +203,7 @@ int main () {
 #endif
   return 0;
 }
-changequote([,])dnl
-      ])])
+      ]])])
     if AC_TRY_EVAL([ac_link]) && test -s conftest$ac_exeext; then
       case "$host_os" in
         # Handle native Windows specially, because there setlocale() interprets
diff --git a/m4/locale-ja.m4 b/m4/locale-ja.m4
index 487f68b..31e95b8 100644
--- a/m4/locale-ja.m4
+++ b/m4/locale-ja.m4
@@ -1,5 +1,5 @@
-# locale-ja.m4 serial 14
-dnl Copyright (C) 2003, 2005-2019 Free Software Foundation, Inc.
+# locale-ja.m4 serial 15
+dnl Copyright (C) 2003, 2005-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
@@ -12,8 +12,7 @@ AC_DEFUN([gt_LOCALE_JA],
   AC_REQUIRE([AC_CANONICAL_HOST])
   AC_REQUIRE([AM_LANGINFO_CODESET])
   AC_CACHE_CHECK([for a traditional japanese locale], [gt_cv_locale_ja], [
-    AC_LANG_CONFTEST([AC_LANG_SOURCE([
-changequote(,)dnl
+    AC_LANG_CONFTEST([AC_LANG_SOURCE([[
 #include <locale.h>
 #include <time.h>
 #if HAVE_LANGINFO_CODESET
@@ -82,8 +81,7 @@ int main ()
   return 0;
 #endif
 }
-changequote([,])dnl
-      ])])
+      ]])])
     if AC_TRY_EVAL([ac_link]) && test -s conftest$ac_exeext; then
       case "$host_os" in
         # Handle native Windows specially, because there setlocale() interprets
diff --git a/m4/locale-zh.m4 b/m4/locale-zh.m4
index 8b81326..c60883c 100644
--- a/m4/locale-zh.m4
+++ b/m4/locale-zh.m4
@@ -1,5 +1,5 @@
-# locale-zh.m4 serial 14
-dnl Copyright (C) 2003, 2005-2019 Free Software Foundation, Inc.
+# locale-zh.m4 serial 15
+dnl Copyright (C) 2003, 2005-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
@@ -12,8 +12,7 @@ AC_DEFUN([gt_LOCALE_ZH_CN],
   AC_REQUIRE([AC_CANONICAL_HOST])
   AC_REQUIRE([AM_LANGINFO_CODESET])
   AC_CACHE_CHECK([for a transitional chinese locale], [gt_cv_locale_zh_CN], [
-    AC_LANG_CONFTEST([AC_LANG_SOURCE([
-changequote(,)dnl
+    AC_LANG_CONFTEST([AC_LANG_SOURCE([[
 #include <locale.h>
 #include <stdlib.h>
 #include <time.h>
@@ -83,8 +82,7 @@ int main ()
   return 0;
 #endif
 }
-changequote([,])dnl
-      ])])
+      ]])])
     if AC_TRY_EVAL([ac_link]) && test -s conftest$ac_exeext; then
       case "$host_os" in
         # Handle native Windows specially, because there setlocale() interprets
diff --git a/m4/locale_h.m4 b/m4/locale_h.m4
index d28ba0c..32494cf 100644
--- a/m4/locale_h.m4
+++ b/m4/locale_h.m4
@@ -1,5 +1,5 @@
-# locale_h.m4 serial 21
-dnl Copyright (C) 2007, 2009-2019 Free Software Foundation, Inc.
+# locale_h.m4 serial 24
+dnl Copyright (C) 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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -17,6 +17,8 @@ AC_DEFUN([gl_LOCALE_H],
   dnl If <stddef.h> is replaced, then <locale.h> must also be replaced.
   AC_REQUIRE([gl_STDDEF_H])
 
+  AC_REQUIRE([gl_LOCALE_T])
+
   dnl Solaris 11.0 defines the int_p_*, int_n_* members of 'struct lconv'
   dnl only if _LCONV_C99 is defined.
   AC_REQUIRE([AC_CANONICAL_HOST])
@@ -37,34 +39,6 @@ AC_DEFUN([gl_LOCALE_H],
        [gl_cv_header_locale_h_posix2001=yes],
        [gl_cv_header_locale_h_posix2001=no])])
 
-  dnl Check for <xlocale.h>.
-  AC_CHECK_HEADERS_ONCE([xlocale.h])
-  if test $ac_cv_header_xlocale_h = yes; then
-    HAVE_XLOCALE_H=1
-    dnl Check whether use of locale_t requires inclusion of <xlocale.h>,
-    dnl e.g. on Mac OS X 10.5. If <locale.h> does not define locale_t by
-    dnl itself, we assume that <xlocale.h> will do so.
-    AC_CACHE_CHECK([whether locale.h defines locale_t],
-      [gl_cv_header_locale_has_locale_t],
-      [AC_COMPILE_IFELSE(
-         [AC_LANG_PROGRAM(
-            [[#include <locale.h>
-              locale_t x;]],
-            [[]])],
-         [gl_cv_header_locale_has_locale_t=yes],
-         [gl_cv_header_locale_has_locale_t=no])
-      ])
-    if test $gl_cv_header_locale_has_locale_t = yes; then
-      gl_cv_header_locale_h_needs_xlocale_h=no
-    else
-      gl_cv_header_locale_h_needs_xlocale_h=yes
-    fi
-  else
-    HAVE_XLOCALE_H=0
-    gl_cv_header_locale_h_needs_xlocale_h=no
-  fi
-  AC_SUBST([HAVE_XLOCALE_H])
-
   dnl Check whether 'struct lconv' is complete.
   dnl Bionic libc's 'struct lconv' is just a dummy.
   dnl On OpenBSD 4.9, HP-UX 11, IRIX 6.5, OSF/1 5.1, Solaris 9, Cygwin 1.5.x,
@@ -82,7 +56,20 @@ AC_DEFUN([gl_LOCALE_H],
        [gl_cv_sys_struct_lconv_ok=no])
     ])
   if test $gl_cv_sys_struct_lconv_ok = no; then
-    REPLACE_STRUCT_LCONV=1
+    dnl On native Windows with MSVC, merely define these member names as macros.
+    dnl This avoids trouble in C++ mode.
+    case "$host_os" in
+      mingw*)
+        AC_EGREP_CPP([Special], [
+#ifdef _MSC_VER
+ Special
+#endif
+          ],
+          [],
+          [REPLACE_STRUCT_LCONV=1])
+        ;;
+      *) REPLACE_STRUCT_LCONV=1 ;;
+    esac
   fi
 
   dnl <locale.h> is always overridden, because of GNULIB_POSIXCHECK.
@@ -99,6 +86,49 @@ AC_DEFUN([gl_LOCALE_H],
     [setlocale newlocale duplocale freelocale])
 ])
 
+dnl Checks to determine whether the system has the locale_t type,
+dnl and how to obtain it.
+AC_DEFUN([gl_LOCALE_T],
+[
+  dnl Persuade glibc and Solaris <locale.h> to define locale_t.
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+
+  dnl Check whether use of locale_t requires inclusion of <xlocale.h>,
+  dnl e.g. on Mac OS X 10.5. If <locale.h> does not define locale_t by
+  dnl itself, we assume that <xlocale.h> will do so.
+  AC_CACHE_CHECK([whether locale.h defines locale_t],
+    [gl_cv_header_locale_has_locale_t],
+    [AC_COMPILE_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[#include <locale.h>
+            locale_t x;]],
+          [[]])],
+       [gl_cv_header_locale_has_locale_t=yes],
+       [gl_cv_header_locale_has_locale_t=no])
+    ])
+
+  dnl Check for <xlocale.h>.
+  AC_CHECK_HEADERS_ONCE([xlocale.h])
+  if test $ac_cv_header_xlocale_h = yes; then
+    HAVE_XLOCALE_H=1
+    if test $gl_cv_header_locale_has_locale_t = yes; then
+      gl_cv_header_locale_h_needs_xlocale_h=no
+    else
+      gl_cv_header_locale_h_needs_xlocale_h=yes
+    fi
+    HAVE_LOCALE_T=1
+  else
+    HAVE_XLOCALE_H=0
+    gl_cv_header_locale_h_needs_xlocale_h=no
+    if test $gl_cv_header_locale_has_locale_t = yes; then
+      HAVE_LOCALE_T=1
+    else
+      HAVE_LOCALE_T=0
+    fi
+  fi
+  AC_SUBST([HAVE_XLOCALE_H])
+])
+
 AC_DEFUN([gl_LOCALE_MODULE_INDICATOR],
 [
   dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
@@ -110,10 +140,11 @@ AC_DEFUN([gl_LOCALE_MODULE_INDICATOR],
 
 AC_DEFUN([gl_LOCALE_H_DEFAULTS],
 [
-  GNULIB_LOCALECONV=0; AC_SUBST([GNULIB_LOCALECONV])
-  GNULIB_SETLOCALE=0;  AC_SUBST([GNULIB_SETLOCALE])
-  GNULIB_DUPLOCALE=0;  AC_SUBST([GNULIB_DUPLOCALE])
-  GNULIB_LOCALENAME=0; AC_SUBST([GNULIB_LOCALENAME])
+  GNULIB_LOCALECONV=0;     AC_SUBST([GNULIB_LOCALECONV])
+  GNULIB_SETLOCALE=0;      AC_SUBST([GNULIB_SETLOCALE])
+  GNULIB_SETLOCALE_NULL=0; AC_SUBST([GNULIB_SETLOCALE_NULL])
+  GNULIB_DUPLOCALE=0;      AC_SUBST([GNULIB_DUPLOCALE])
+  GNULIB_LOCALENAME=0;     AC_SUBST([GNULIB_LOCALENAME])
   dnl Assume proper GNU behavior unless another module says otherwise.
   HAVE_NEWLOCALE=1;       AC_SUBST([HAVE_NEWLOCALE])
   HAVE_DUPLOCALE=1;       AC_SUBST([HAVE_DUPLOCALE])
diff --git a/m4/localeconv.m4 b/m4/localeconv.m4
index 9bb78f0..a926224 100644
--- a/m4/localeconv.m4
+++ b/m4/localeconv.m4
@@ -1,5 +1,5 @@
 # localeconv.m4 serial 1
-dnl Copyright (C) 2012-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2012-2020 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.
diff --git a/m4/localtime-buffer.m4 b/m4/localtime-buffer.m4
deleted file mode 100644
index 6d99828..0000000
--- a/m4/localtime-buffer.m4
+++ /dev/null
@@ -1,21 +0,0 @@
-# localtime-buffer.m4 serial 1
-dnl Copyright (C) 2017-2019 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/m4/lock.m4 b/m4/lock.m4
index 93b76fa..1c39591 100644
--- a/m4/lock.m4
+++ b/m4/lock.m4
@@ -1,5 +1,5 @@
 # lock.m4 serial 14
-dnl Copyright (C) 2005-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2005-2020 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.
diff --git a/m4/longlong.m4 b/m4/longlong.m4
deleted file mode 100644
index 08d0e36..0000000
--- a/m4/longlong.m4
+++ /dev/null
@@ -1,113 +0,0 @@
-# longlong.m4 serial 18
-dnl Copyright (C) 1999-2007, 2009-2019 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 From Paul Eggert.
-
-AC_PREREQ([2.62])
-
-# Define HAVE_LONG_LONG_INT if 'long long int' works.
-# This can be faster than what's in Autoconf 2.62 through 2.68.
-
-# Note: If the type 'long long int' exists but is only 32 bits large
-# (as on some very old compilers), HAVE_LONG_LONG_INT will not be
-# defined. In this case you can treat 'long long int' like 'long int'.
-
-AC_DEFUN([AC_TYPE_LONG_LONG_INT],
-[
-  AC_REQUIRE([AC_TYPE_UNSIGNED_LONG_LONG_INT])
-  AC_CACHE_CHECK([for long long int], [ac_cv_type_long_long_int],
-     [ac_cv_type_long_long_int=yes
-      if test "x${ac_cv_prog_cc_c99-no}" = xno; then
-        ac_cv_type_long_long_int=$ac_cv_type_unsigned_long_long_int
-        if test $ac_cv_type_long_long_int = yes; then
-          dnl Catch a bug in Tandem NonStop Kernel (OSS) cc -O circa 2004.
-          dnl If cross compiling, assume the bug is not important, since
-          dnl nobody cross compiles for this platform as far as we know.
-          AC_RUN_IFELSE(
-            [AC_LANG_PROGRAM(
-               [[@%:@include <limits.h>
-                 @%:@ifndef LLONG_MAX
-                 @%:@ define HALF \
-                          (1LL << (sizeof (long long int) * CHAR_BIT - 2))
-                 @%:@ define LLONG_MAX (HALF - 1 + HALF)
-                 @%:@endif]],
-               [[long long int n = 1;
-                 int i;
-                 for (i = 0; ; i++)
-                   {
-                     long long int m = n << i;
-                     if (m >> i != n)
-                       return 1;
-                     if (LLONG_MAX / 2 < m)
-                       break;
-                   }
-                 return 0;]])],
-            [],
-            [ac_cv_type_long_long_int=no],
-            [:])
-        fi
-      fi])
-  if test $ac_cv_type_long_long_int = yes; then
-    AC_DEFINE([HAVE_LONG_LONG_INT], [1],
-      [Define to 1 if the system has the type 'long long int'.])
-  fi
-])
-
-# Define HAVE_UNSIGNED_LONG_LONG_INT if 'unsigned long long int' works.
-# This can be faster than what's in Autoconf 2.62 through 2.68.
-
-# Note: If the type 'unsigned long long int' exists but is only 32 bits
-# large (as on some very old compilers), AC_TYPE_UNSIGNED_LONG_LONG_INT
-# will not be defined. In this case you can treat 'unsigned long long int'
-# like 'unsigned long int'.
-
-AC_DEFUN([AC_TYPE_UNSIGNED_LONG_LONG_INT],
-[
-  AC_CACHE_CHECK([for unsigned long long int],
-    [ac_cv_type_unsigned_long_long_int],
-    [ac_cv_type_unsigned_long_long_int=yes
-     if test "x${ac_cv_prog_cc_c99-no}" = xno; then
-       AC_LINK_IFELSE(
-         [_AC_TYPE_LONG_LONG_SNIPPET],
-         [],
-         [ac_cv_type_unsigned_long_long_int=no])
-     fi])
-  if test $ac_cv_type_unsigned_long_long_int = yes; then
-    AC_DEFINE([HAVE_UNSIGNED_LONG_LONG_INT], [1],
-      [Define to 1 if the system has the type 'unsigned long long int'.])
-  fi
-])
-
-# Expands to a C program that can be used to test for simultaneous support
-# of 'long long' and 'unsigned long long'. We don't want to say that
-# 'long long' is available if 'unsigned long long' is not, or vice versa,
-# because too many programs rely on the symmetry between signed and unsigned
-# integer types (excluding 'bool').
-AC_DEFUN([_AC_TYPE_LONG_LONG_SNIPPET],
-[
-  AC_LANG_PROGRAM(
-    [[/* For now, do not test the preprocessor; as of 2007 there are too many
-         implementations with broken preprocessors.  Perhaps this can
-         be revisited in 2012.  In the meantime, code should not expect
-         #if to work with literals wider than 32 bits.  */
-      /* Test literals.  */
-      long long int ll = 9223372036854775807ll;
-      long long int nll = -9223372036854775807LL;
-      unsigned long long int ull = 18446744073709551615ULL;
-      /* Test constant expressions.   */
-      typedef int a[((-9223372036854775807LL < 0 && 0 < 9223372036854775807ll)
-                     ? 1 : -1)];
-      typedef int b[(18446744073709551615ULL <= (unsigned long long int) -1
-                     ? 1 : -1)];
-      int i = 63;]],
-    [[/* Test availability of runtime routines for shift and division.  */
-      long long int llmax = 9223372036854775807ll;
-      unsigned long long int ullmax = 18446744073709551615ull;
-      return ((ll << 63) | (ll >> 63) | (ll < i) | (ll > i)
-              | (llmax / ll) | (llmax % ll)
-              | (ull << 63) | (ull >> 63) | (ull << i) | (ull >> i)
-              | (ullmax / ull) | (ullmax % ull));]])
-])
diff --git a/m4/lseek.m4 b/m4/lseek.m4
index d55ec2a..472a1cb 100644
--- a/m4/lseek.m4
+++ b/m4/lseek.m4
@@ -1,5 +1,5 @@
-# lseek.m4 serial 10
-dnl Copyright (C) 2007, 2009-2019 Free Software Foundation, Inc.
+# lseek.m4 serial 11
+dnl Copyright (C) 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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -32,7 +32,8 @@ AC_DEFUN([gl_FUNC_LSEEK],
 #else /* on Windows with MSVC */
 # include <io.h>
 #endif
-]], [[
+]GL_MDA_DEFINES],
+[[
   /* Exit with success only if stdin is seekable.  */
   return lseek (0, (off_t)0, SEEK_CUR) < 0;
 ]])],
diff --git a/m4/lstat.m4 b/m4/lstat.m4
index ace1638..3c2b214 100644
--- a/m4/lstat.m4
+++ b/m4/lstat.m4
@@ -1,6 +1,6 @@
-# serial 32
+# serial 33
 
-# Copyright (C) 1997-2001, 2003-2019 Free Software Foundation, Inc.
+# Copyright (C) 1997-2001, 2003-2020 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -63,8 +63,8 @@ AC_DEFUN([gl_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK],
             # Guess no on native Windows.
             gl_cv_func_lstat_dereferences_slashed_symlink="guessing no" ;;
           *)
-            # If we don't know, assume the worst.
-            gl_cv_func_lstat_dereferences_slashed_symlink="guessing no" ;;
+            # If we don't know, obey --enable-cross-guesses.
+            gl_cv_func_lstat_dereferences_slashed_symlink="$gl_cross_guess_normal" ;;
         esac
        ])
      rm -f conftest.sym conftest.file
diff --git a/m4/malloc.m4 b/m4/malloc.m4
index c469c45..3823566 100644
--- a/m4/malloc.m4
+++ b/m4/malloc.m4
@@ -1,27 +1,19 @@
-# malloc.m4 serial 19
-dnl Copyright (C) 2007, 2009-2019 Free Software Foundation, Inc.
+# malloc.m4 serial 21
+dnl Copyright (C) 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,
 dnl with or without modifications, as long as this notice is preserved.
 
-m4_version_prereq([2.70], [] ,[
-
 # This is adapted with modifications from upstream Autoconf here:
 # https://git.savannah.gnu.org/cgit/autoconf.git/commit/?id=04be2b7a29d65d9a08e64e8e56e594c91749598c
 AC_DEFUN([_AC_FUNC_MALLOC_IF],
 [
-  AC_REQUIRE([AC_HEADER_STDC])dnl
   AC_REQUIRE([AC_CANONICAL_HOST])dnl for cross-compiles
-  AC_CHECK_HEADERS([stdlib.h])
   AC_CACHE_CHECK([for GNU libc compatible malloc],
     [ac_cv_func_malloc_0_nonnull],
     [AC_RUN_IFELSE(
        [AC_LANG_PROGRAM(
-          [[#if defined STDC_HEADERS || defined HAVE_STDLIB_H
-            # include <stdlib.h>
-            #else
-            char *malloc ();
-            #endif
+          [[#include <stdlib.h>
           ]],
           [[char *p = malloc (0);
             int result = !p;
@@ -35,8 +27,8 @@ AC_DEFUN([_AC_FUNC_MALLOC_IF],
           *-gnu* | gnu* | *-musl* | freebsd* | netbsd* | openbsd* \
           | hpux* | solaris* | cygwin* | mingw*)
             ac_cv_func_malloc_0_nonnull="guessing yes" ;;
-          # If we don't know, assume the worst.
-          *) ac_cv_func_malloc_0_nonnull="guessing no" ;;
+          # If we don't know, obey --enable-cross-guesses.
+          *) ac_cv_func_malloc_0_nonnull="$gl_cross_guess_normal" ;;
         esac
        ])
     ])
@@ -50,8 +42,6 @@ AC_DEFUN([_AC_FUNC_MALLOC_IF],
   esac
 ])# _AC_FUNC_MALLOC_IF
 
-])
-
 # gl_FUNC_MALLOC_GNU
 # ------------------
 # Test whether 'malloc (0)' is handled like in GNU libc, and replace malloc if
diff --git a/m4/malloca.m4 b/m4/malloca.m4
index 820f40a..930199d 100644
--- a/m4/malloca.m4
+++ b/m4/malloca.m4
@@ -1,5 +1,5 @@
-# malloca.m4 serial 1
-dnl Copyright (C) 2003-2004, 2006-2007, 2009-2019 Free Software Foundation,
+# malloca.m4 serial 2
+dnl Copyright (C) 2003-2004, 2006-2007, 2009-2020 Free Software Foundation,
 dnl Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -11,5 +11,4 @@ AC_DEFUN([gl_MALLOCA],
   dnl @ALLOCA@ and @LTALLOCA@.
   dnl gl_FUNC_ALLOCA   dnl Already brought in by the module dependencies.
   AC_REQUIRE([gl_EEMALLOC])
-  AC_REQUIRE([AC_TYPE_LONG_LONG_INT])
 ])
diff --git a/m4/mbchar.m4 b/m4/mbchar.m4
index 3d16342..5e3efa6 100644
--- a/m4/mbchar.m4
+++ b/m4/mbchar.m4
@@ -1,5 +1,5 @@
 # mbchar.m4 serial 9
-dnl Copyright (C) 2005-2007, 2009-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/mbiter.m4 b/m4/mbiter.m4
index 58889fe..e6b49a9 100644
--- a/m4/mbiter.m4
+++ b/m4/mbiter.m4
@@ -1,5 +1,5 @@
 # mbiter.m4 serial 7
-dnl Copyright (C) 2005, 2008-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2005, 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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/mbrtowc.m4 b/m4/mbrtowc.m4
index 4811af5..ad31a7b 100644
--- a/m4/mbrtowc.m4
+++ b/m4/mbrtowc.m4
@@ -1,5 +1,5 @@
-# mbrtowc.m4 serial 31  -*- coding: utf-8 -*-
-dnl Copyright (C) 2001-2002, 2004-2005, 2008-2019 Free Software Foundation,
+# mbrtowc.m4 serial 38  -*- coding: utf-8 -*-
+dnl Copyright (C) 2001-2002, 2004-2005, 2008-2020 Free Software Foundation,
 dnl Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -8,6 +8,8 @@ dnl with or without modifications, as long as this notice is preserved.
 AC_DEFUN([gl_FUNC_MBRTOWC],
 [
   AC_REQUIRE([gl_WCHAR_H_DEFAULTS])
+  AC_REQUIRE([gl_PTHREADLIB])
+  AC_CHECK_HEADERS_ONCE([threads.h])
 
   AC_REQUIRE([AC_TYPE_MBSTATE_T])
   gl_MBSTATE_T_BROKEN
@@ -16,15 +18,8 @@ AC_DEFUN([gl_FUNC_MBRTOWC],
   if test $ac_cv_func_mbrtowc = no; then
     HAVE_MBRTOWC=0
     AC_CHECK_DECLS([mbrtowc],,, [[
-/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
-   <wchar.h>.
-   BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be
-   included before <wchar.h>.  */
-#include <stddef.h>
-#include <stdio.h>
-#include <time.h>
-#include <wchar.h>
-]])
+      #include <wchar.h>
+    ]])
     if test $ac_cv_have_decl_mbrtowc = yes; then
       dnl On Minix 3.1.8, the system's <wchar.h> declares mbrtowc() although
       dnl it does not have the function. Avoid a collision with gnulib's
@@ -39,6 +34,7 @@ AC_DEFUN([gl_FUNC_MBRTOWC],
       gl_MBRTOWC_NULL_ARG2
       gl_MBRTOWC_RETVAL
       gl_MBRTOWC_NUL_RETVAL
+      gl_MBRTOWC_STORES_INCOMPLETE
       gl_MBRTOWC_EMPTY_INPUT
       gl_MBRTOWC_C_LOCALE
       case "$gl_cv_func_mbrtowc_null_arg1" in
@@ -69,6 +65,13 @@ AC_DEFUN([gl_FUNC_MBRTOWC],
            REPLACE_MBRTOWC=1
            ;;
       esac
+      case "$gl_cv_func_mbrtowc_stores_incomplete" in
+        *no) ;;
+        *) AC_DEFINE([MBRTOWC_STORES_INCOMPLETE_BUG], [1],
+             [Define if the mbrtowc function stores a wide character when reporting incomplete input.])
+           REPLACE_MBRTOWC=1
+           ;;
+      esac
       case "$gl_cv_func_mbrtowc_empty_input" in
         *yes) ;;
         *) AC_DEFINE([MBRTOWC_EMPTY_INPUT_BUG], [1],
@@ -77,15 +80,32 @@ AC_DEFUN([gl_FUNC_MBRTOWC],
            REPLACE_MBRTOWC=1
            ;;
       esac
-      case $gl_cv_C_locale_sans_EILSEQ in
+      case "$gl_cv_func_mbrtowc_C_locale_sans_EILSEQ" in
         *yes) ;;
-        *) AC_DEFINE([C_LOCALE_MAYBE_EILSEQ], [1],
-             [Define to 1 if the C locale may have encoding errors.])
+        *) AC_DEFINE([MBRTOWC_IN_C_LOCALE_MAYBE_EILSEQ], [1],
+             [Define if the mbrtowc function may signal encoding errors in the C locale.])
            REPLACE_MBRTOWC=1
            ;;
       esac
     fi
   fi
+  if test $REPLACE_MBSTATE_T = 1; then
+    case "$host_os" in
+      mingw*) LIB_MBRTOWC= ;;
+      *)
+        gl_WEAK_SYMBOLS
+        case "$gl_cv_have_weak" in
+          *yes) LIB_MBRTOWC= ;;
+          *)    LIB_MBRTOWC="$LIBPTHREAD" ;;
+        esac
+        ;;
+    esac
+  else
+    LIB_MBRTOWC=
+  fi
+  dnl LIB_MBRTOWC is expected to be '-pthread' or '-lpthread' on AIX
+  dnl with gcc or xlc, and empty otherwise.
+  AC_SUBST([LIB_MBRTOWC])
 ])
 
 dnl Test whether mbsinit() and mbrtowc() need to be overridden in a way that
@@ -97,11 +117,19 @@ dnl avoid inconsistencies.
 AC_DEFUN([gl_MBSTATE_T_BROKEN],
 [
   AC_REQUIRE([gl_WCHAR_H_DEFAULTS])
+  AC_REQUIRE([AC_CANONICAL_HOST])
 
   AC_REQUIRE([AC_TYPE_MBSTATE_T])
   AC_CHECK_FUNCS_ONCE([mbsinit])
   AC_CHECK_FUNCS_ONCE([mbrtowc])
-  if test $ac_cv_func_mbsinit = yes && test $ac_cv_func_mbrtowc = yes; then
+  dnl On native Windows, we know exactly how mbsinit() behaves and don't need
+  dnl to override it, even if - like on MSVC - mbsinit() is only defined as
+  dnl an inline function, not as a global function.
+  if case "$host_os" in
+       mingw*) true ;;
+       *) test $ac_cv_func_mbsinit = yes ;;
+     esac \
+    && test $ac_cv_func_mbrtowc = yes; then
     gl_MBRTOWC_INCOMPLETE_STATE
     gl_MBRTOWC_SANITYCHECK
     REPLACE_MBSTATE_T=0
@@ -126,6 +154,7 @@ AC_DEFUN([gl_MBRTOWC_INCOMPLETE_STATE],
 [
   AC_REQUIRE([AC_PROG_CC])
   AC_REQUIRE([gt_LOCALE_JA])
+  AC_REQUIRE([gt_LOCALE_FR_UTF8])
   AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
   AC_CACHE_CHECK([whether mbrtowc handles incomplete characters],
     [gl_cv_func_mbrtowc_incomplete_state],
@@ -145,13 +174,6 @@ changequote([,])dnl
           [AC_LANG_SOURCE([[
 #include <locale.h>
 #include <string.h>
-/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
-   <wchar.h>.
-   BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be
-   included before <wchar.h>.  */
-#include <stddef.h>
-#include <stdio.h>
-#include <time.h>
 #include <wchar.h>
 int main ()
 {
@@ -171,6 +193,32 @@ int main ()
           [gl_cv_func_mbrtowc_incomplete_state=yes],
           [gl_cv_func_mbrtowc_incomplete_state=no],
           [:])
+      else
+        if test $LOCALE_FR_UTF8 != none; then
+          AC_RUN_IFELSE(
+            [AC_LANG_SOURCE([[
+#include <locale.h>
+#include <string.h>
+#include <wchar.h>
+int main ()
+{
+  if (setlocale (LC_ALL, "$LOCALE_FR_UTF8") != NULL)
+    {
+      const char input[] = "B\303\274\303\237er"; /* "Büßer" */
+      mbstate_t state;
+      wchar_t wc;
+
+      memset (&state, '\0', sizeof (mbstate_t));
+      if (mbrtowc (&wc, input + 1, 1, &state) == (size_t)(-2))
+        if (mbsinit (&state))
+          return 2;
+    }
+  return 0;
+}]])],
+          [gl_cv_func_mbrtowc_incomplete_state=yes],
+          [gl_cv_func_mbrtowc_incomplete_state=no],
+          [:])
+        fi
       fi
     ])
 ])
@@ -202,13 +250,6 @@ changequote([,])dnl
 #include <locale.h>
 #include <stdlib.h>
 #include <string.h>
-/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
-   <wchar.h>.
-   BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be
-   included before <wchar.h>.  */
-#include <stddef.h>
-#include <stdio.h>
-#include <time.h>
 #include <wchar.h>
 int main ()
 {
@@ -262,13 +303,6 @@ changequote([,])dnl
 #include <locale.h>
 #include <stdlib.h>
 #include <string.h>
-/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
-   <wchar.h>.
-   BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be
-   included before <wchar.h>.  */
-#include <stddef.h>
-#include <stdio.h>
-#include <time.h>
 #include <wchar.h>
 int main ()
 {
@@ -331,13 +365,6 @@ changequote([,])dnl
           [AC_LANG_SOURCE([[
 #include <locale.h>
 #include <string.h>
-/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
-   <wchar.h>.
-   BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be
-   included before <wchar.h>.  */
-#include <stddef.h>
-#include <stdio.h>
-#include <time.h>
 #include <wchar.h>
 int main ()
 {
@@ -393,13 +420,6 @@ changequote([,])dnl
           [AC_LANG_SOURCE([[
 #include <locale.h>
 #include <string.h>
-/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
-   <wchar.h>.
-   BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be
-   included before <wchar.h>.  */
-#include <stddef.h>
-#include <stdio.h>
-#include <time.h>
 #include <wchar.h>
 int main ()
 {
@@ -521,13 +541,6 @@ changequote([,])dnl
           [AC_LANG_SOURCE([[
 #include <locale.h>
 #include <string.h>
-/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
-   <wchar.h>.
-   BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be
-   included before <wchar.h>.  */
-#include <stddef.h>
-#include <stdio.h>
-#include <time.h>
 #include <wchar.h>
 int main ()
 {
@@ -550,6 +563,112 @@ int main ()
     ])
 ])
 
+dnl Test whether mbrtowc stores a wide character when reporting incomplete
+dnl input.
+
+AC_DEFUN([gl_MBRTOWC_STORES_INCOMPLETE],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CACHE_CHECK([whether mbrtowc stores incomplete characters],
+    [gl_cv_func_mbrtowc_stores_incomplete],
+    [
+     dnl Initial guess, used when cross-compiling or when no suitable locale
+     dnl is present.
+changequote(,)dnl
+     case "$host_os" in
+               # Guess yes on native Windows.
+       mingw*) gl_cv_func_mbrtowc_stores_incomplete="guessing yes" ;;
+       *)      gl_cv_func_mbrtowc_stores_incomplete="guessing no" ;;
+     esac
+changequote([,])dnl
+     case "$host_os" in
+       mingw*)
+         AC_RUN_IFELSE(
+           [AC_LANG_SOURCE([[
+#include <locale.h>
+#include <string.h>
+#include <wchar.h>
+int main ()
+{
+  int result = 0;
+  if (setlocale (LC_ALL, "French_France.65001") != NULL)
+    {
+      wchar_t wc = (wchar_t) 0xBADFACE;
+      mbstate_t state;
+
+      memset (&state, '\0', sizeof (mbstate_t));
+      if (mbrtowc (&wc, "\303", 1, &state) == (size_t)(-2)
+          && wc != (wchar_t) 0xBADFACE)
+        result |= 1;
+    }
+  if (setlocale (LC_ALL, "Japanese_Japan.932") != NULL)
+    {
+      wchar_t wc = (wchar_t) 0xBADFACE;
+      mbstate_t state;
+
+      memset (&state, '\0', sizeof (mbstate_t));
+      if (mbrtowc (&wc, "\226", 1, &state) == (size_t)(-2)
+          && wc != (wchar_t) 0xBADFACE)
+        result |= 2;
+    }
+  if (setlocale (LC_ALL, "Chinese_Taiwan.950") != NULL)
+    {
+      wchar_t wc = (wchar_t) 0xBADFACE;
+      mbstate_t state;
+
+      memset (&state, '\0', sizeof (mbstate_t));
+      if (mbrtowc (&wc, "\245", 1, &state) == (size_t)(-2)
+          && wc != (wchar_t) 0xBADFACE)
+        result |= 4;
+    }
+  if (setlocale (LC_ALL, "Chinese_China.936") != NULL)
+    {
+      wchar_t wc = (wchar_t) 0xBADFACE;
+      mbstate_t state;
+
+      memset (&state, '\0', sizeof (mbstate_t));
+      if (mbrtowc (&wc, "\261", 1, &state) == (size_t)(-2)
+          && wc != (wchar_t) 0xBADFACE)
+        result |= 8;
+    }
+  return result;
+}]])],
+           [gl_cv_func_mbrtowc_stores_incomplete=no],
+           [gl_cv_func_mbrtowc_stores_incomplete=yes],
+           [:])
+         ;;
+       *)
+         AC_REQUIRE([gt_LOCALE_FR_UTF8])
+         if test $LOCALE_FR_UTF8 != none; then
+           AC_RUN_IFELSE(
+             [AC_LANG_SOURCE([[
+#include <locale.h>
+#include <string.h>
+#include <wchar.h>
+int main ()
+{
+  if (setlocale (LC_ALL, "$LOCALE_FR_UTF8") != NULL)
+    {
+      wchar_t wc = (wchar_t) 0xBADFACE;
+      mbstate_t state;
+
+      memset (&state, '\0', sizeof (mbstate_t));
+      if (mbrtowc (&wc, "\303", 1, &state) == (size_t)(-2)
+          && wc != (wchar_t) 0xBADFACE)
+        return 1;
+    }
+  return 0;
+}]])],
+             [gl_cv_func_mbrtowc_stores_incomplete=no],
+             [gl_cv_func_mbrtowc_stores_incomplete=yes],
+             [:])
+         fi
+         ;;
+     esac
+    ])
+])
+
 dnl Test whether mbrtowc returns the correct value on empty input.
 
 AC_DEFUN([gl_MBRTOWC_EMPTY_INPUT],
@@ -595,11 +714,11 @@ AC_DEFUN([gl_MBRTOWC_C_LOCALE],
 [
   AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
   AC_CACHE_CHECK([whether the C locale is free of encoding errors],
-    [gl_cv_C_locale_sans_EILSEQ],
+    [gl_cv_func_mbrtowc_C_locale_sans_EILSEQ],
     [
      dnl Initial guess, used when cross-compiling or when no suitable locale
      dnl is present.
-     gl_cv_C_locale_sans_EILSEQ="guessing no"
+     gl_cv_func_mbrtowc_C_locale_sans_EILSEQ="$gl_cross_guess_normal"
 
      AC_RUN_IFELSE(
        [AC_LANG_PROGRAM(
@@ -622,22 +741,28 @@ AC_DEFUN([gl_MBRTOWC_C_LOCALE],
               }
             return 0;
           ]])],
-      [gl_cv_C_locale_sans_EILSEQ=yes],
-      [gl_cv_C_locale_sans_EILSEQ=no],
+      [gl_cv_func_mbrtowc_C_locale_sans_EILSEQ=yes],
+      [gl_cv_func_mbrtowc_C_locale_sans_EILSEQ=no],
       [case "$host_os" in
                  # Guess yes on native Windows.
-         mingw*) gl_cv_C_locale_sans_EILSEQ="guessing yes" ;;
+         mingw*) gl_cv_func_mbrtowc_C_locale_sans_EILSEQ="guessing yes" ;;
        esac
       ])
     ])
 ])
 
-# Prerequisites of lib/mbrtowc.c.
+# Prerequisites of lib/mbrtowc.c and lib/lc-charset-dispatch.c.
 AC_DEFUN([gl_PREREQ_MBRTOWC], [
   AC_REQUIRE([AC_C_INLINE])
   :
 ])
 
+# Prerequisites of lib/mbtowc-lock.c.
+AC_DEFUN([gl_PREREQ_MBTOWC_LOCK],
+[
+  gl_VISIBILITY
+])
+
 
 dnl From Paul Eggert
 
@@ -650,14 +775,7 @@ AC_DEFUN([AC_FUNC_MBRTOWC],
     [gl_cv_func_mbrtowc],
     [AC_LINK_IFELSE(
        [AC_LANG_PROGRAM(
-            [[/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be
-                 included before <wchar.h>.
-                 BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h>
-                 must be included before <wchar.h>.  */
-              #include <stddef.h>
-              #include <stdio.h>
-              #include <time.h>
-              #include <wchar.h>]],
+            [[#include <wchar.h>]],
             [[wchar_t wc;
               char const s[] = "";
               size_t n = 1;
diff --git a/m4/mbsinit.m4 b/m4/mbsinit.m4
index e2f45e7..f446659 100644
--- a/m4/mbsinit.m4
+++ b/m4/mbsinit.m4
@@ -1,5 +1,5 @@
-# mbsinit.m4 serial 8
-dnl Copyright (C) 2008, 2010-2019 Free Software Foundation, Inc.
+# mbsinit.m4 serial 9
+dnl Copyright (C) 2008, 2010-2020 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.
@@ -16,15 +16,8 @@ AC_DEFUN([gl_FUNC_MBSINIT],
   if test $ac_cv_func_mbsinit = no; then
     HAVE_MBSINIT=0
     AC_CHECK_DECLS([mbsinit],,, [[
-/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
-   <wchar.h>.
-   BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be
-   included before <wchar.h>.  */
-#include <stddef.h>
-#include <stdio.h>
-#include <time.h>
-#include <wchar.h>
-]])
+      #include <wchar.h>
+    ]])
     if test $ac_cv_have_decl_mbsinit = yes; then
       dnl On Minix 3.1.8, the system's <wchar.h> declares mbsinit() although
       dnl it does not have the function. Avoid a collision with gnulib's
diff --git a/m4/mbsrtowcs.m4 b/m4/mbsrtowcs.m4
index cbdde2c..5a558c3 100644
--- a/m4/mbsrtowcs.m4
+++ b/m4/mbsrtowcs.m4
@@ -1,5 +1,5 @@
-# mbsrtowcs.m4 serial 13
-dnl Copyright (C) 2008-2019 Free Software Foundation, Inc.
+# mbsrtowcs.m4 serial 14
+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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -15,15 +15,8 @@ AC_DEFUN([gl_FUNC_MBSRTOWCS],
   if test $ac_cv_func_mbsrtowcs = no; then
     HAVE_MBSRTOWCS=0
     AC_CHECK_DECLS([mbsrtowcs],,, [[
-/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
-   <wchar.h>.
-   BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be
-   included before <wchar.h>.  */
-#include <stddef.h>
-#include <stdio.h>
-#include <time.h>
-#include <wchar.h>
-]])
+      #include <wchar.h>
+    ]])
     if test $ac_cv_have_decl_mbsrtowcs = yes; then
       dnl On Minix 3.1.8, the system's <wchar.h> declares mbsrtowcs() although
       dnl it does not have the function. Avoid a collision with gnulib's
@@ -72,13 +65,6 @@ changequote([,])dnl
           [AC_LANG_SOURCE([[
 #include <locale.h>
 #include <string.h>
-/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
-   <wchar.h>.
-   BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be
-   included before <wchar.h>.  */
-#include <stddef.h>
-#include <stdio.h>
-#include <time.h>
 #include <wchar.h>
 int main ()
 {
diff --git a/m4/mbstate_t.m4 b/m4/mbstate_t.m4
index f669753..226f122 100644
--- a/m4/mbstate_t.m4
+++ b/m4/mbstate_t.m4
@@ -1,5 +1,5 @@
-# mbstate_t.m4 serial 13
-dnl Copyright (C) 2000-2002, 2008-2019 Free Software Foundation, Inc.
+# mbstate_t.m4 serial 14
+dnl Copyright (C) 2000-2002, 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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -20,14 +20,7 @@ AC_DEFUN([AC_TYPE_MBSTATE_T],
      [AC_COMPILE_IFELSE(
         [AC_LANG_PROGRAM(
            [AC_INCLUDES_DEFAULT[
-/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
-   <wchar.h>.
-   BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be
-   included before <wchar.h>.  */
-#include <stddef.h>
-#include <stdio.h>
-#include <time.h>
-#include <wchar.h>]],
+             #include <wchar.h>]],
            [[mbstate_t x; return sizeof x;]])],
         [ac_cv_type_mbstate_t=yes],
         [ac_cv_type_mbstate_t=no])])
diff --git a/m4/mbtowc.m4 b/m4/mbtowc.m4
index 5a4b92e..befcffa 100644
--- a/m4/mbtowc.m4
+++ b/m4/mbtowc.m4
@@ -1,5 +1,5 @@
 # mbtowc.m4 serial 3
-dnl Copyright (C) 2011-2019 Free Software Foundation, Inc.
+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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/md4.m4 b/m4/md4.m4
index 1b7385d..519095c 100644
--- a/m4/md4.m4
+++ b/m4/md4.m4
@@ -1,5 +1,5 @@
 # md4.m4 serial 7
-dnl Copyright (C) 2002-2006, 2008-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2002-2006, 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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/md5.m4 b/m4/md5.m4
index 59140f5..ca213ed 100644
--- a/m4/md5.m4
+++ b/m4/md5.m4
@@ -1,5 +1,5 @@
 # md5.m4 serial 14
-dnl Copyright (C) 2002-2006, 2008-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2002-2006, 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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/memchr.m4 b/m4/memchr.m4
index 0be394d..888d2b2 100644
--- a/m4/memchr.m4
+++ b/m4/memchr.m4
@@ -1,5 +1,5 @@
-# memchr.m4 serial 14
-dnl Copyright (C) 2002-2004, 2009-2019 Free Software Foundation, Inc.
+# memchr.m4 serial 17
+dnl Copyright (C) 2002-2004, 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.
@@ -14,26 +14,17 @@ AC_DEFUN_ONCE([gl_FUNC_MEMCHR],
   AC_CHECK_FUNCS_ONCE([mprotect])
 
   AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
-  m4_ifdef([gl_FUNC_MEMCHR_OBSOLETE], [
-    dnl These days, we assume memchr is present.  But if support for old
-    dnl platforms is desired:
-    AC_CHECK_FUNCS_ONCE([memchr])
-    if test $ac_cv_func_memchr = no; then
-      HAVE_MEMCHR=0
-    fi
-  ])
-  if test $HAVE_MEMCHR = 1; then
-    # Detect platform-specific bugs in some versions of glibc:
-    # memchr should not dereference anything with length 0
-    #   https://bugzilla.redhat.com/show_bug.cgi?id=499689
-    # memchr should not dereference overestimated length after a match
-    #   https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=521737
-    #   https://sourceware.org/bugzilla/show_bug.cgi?id=10162
-    # memchr should cast the second argument to 'unsigned char'.
-    #   This bug exists in Android 4.3.
-    # Assume that memchr works on platforms that lack mprotect.
-    AC_CACHE_CHECK([whether memchr works], [gl_cv_func_memchr_works],
-      [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
+  # Detect platform-specific bugs in some versions of glibc:
+  # memchr should not dereference anything with length 0
+  #   https://bugzilla.redhat.com/show_bug.cgi?id=499689
+  # memchr should not dereference overestimated length after a match
+  #   https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=521737
+  #   https://sourceware.org/bugzilla/show_bug.cgi?id=10162
+  # memchr should cast the second argument to 'unsigned char'.
+  #   This bug exists in Android 4.3.
+  # Assume that memchr works on platforms that lack mprotect.
+  AC_CACHE_CHECK([whether memchr works], [gl_cv_func_memchr_works],
+    [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
 #include <string.h>
 #if HAVE_SYS_MMAN_H
 # include <fcntl.h>
@@ -68,6 +59,7 @@ AC_DEFUN_ONCE([gl_FUNC_MEMCHR],
 #endif
   if (fence)
     {
+      /* Test against bugs on glibc systems.  */
       if (memchr (fence, 0, 0))
         result |= 1;
       strcpy (fence - 9, "12345678");
@@ -75,6 +67,9 @@ AC_DEFUN_ONCE([gl_FUNC_MEMCHR],
         result |= 2;
       if (memchr (fence - 1, 0, 3) != fence - 1)
         result |= 4;
+      /* Test against bug on AIX 7.2.  */
+      if (memchr (fence - 4, '6', 16) != fence - 4)
+        result |= 8;
     }
   /* Test against bug on Android 4.3.  */
   {
@@ -83,27 +78,26 @@ AC_DEFUN_ONCE([gl_FUNC_MEMCHR],
     input[1] = 'b';
     input[2] = 'c';
     if (memchr (input, 0x789abc00 | 'b', 3) != input + 1)
-      result |= 8;
+      result |= 16;
   }
   return result;
 ]])],
-         [gl_cv_func_memchr_works=yes],
-         [gl_cv_func_memchr_works=no],
-         [case "$host_os" in
-                             # Guess no on Android.
-            linux*-android*) gl_cv_func_memchr_works="guessing no" ;;
-                             # Guess yes on native Windows.
-            mingw*)          gl_cv_func_memchr_works="guessing yes" ;;
-                             # Be pessimistic for now.
-            *)               gl_cv_func_memchr_works="guessing no" ;;
-          esac
-         ])
-      ])
-    case "$gl_cv_func_memchr_works" in
-      *yes) ;;
-      *) REPLACE_MEMCHR=1 ;;
-    esac
-  fi
+       [gl_cv_func_memchr_works=yes],
+       [gl_cv_func_memchr_works=no],
+       [case "$host_os" in
+                           # Guess no on Android.
+          linux*-android*) gl_cv_func_memchr_works="guessing no" ;;
+                           # Guess yes on native Windows.
+          mingw*)          gl_cv_func_memchr_works="guessing yes" ;;
+                           # If we don't know, obey --enable-cross-guesses.
+          *)               gl_cv_func_memchr_works="$gl_cross_guess_normal" ;;
+        esac
+       ])
+    ])
+  case "$gl_cv_func_memchr_works" in
+    *yes) ;;
+    *) REPLACE_MEMCHR=1 ;;
+  esac
 ])
 
 # Prerequisites of lib/memchr.c.
diff --git a/m4/mempcpy.m4 b/m4/mempcpy.m4
new file mode 100644
index 0000000..899f12a
--- /dev/null
+++ b/m4/mempcpy.m4
@@ -0,0 +1,26 @@
+# mempcpy.m4 serial 11
+dnl Copyright (C) 2003-2004, 2006-2007, 2009-2020 Free Software Foundation,
+dnl 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_FUNC_MEMPCPY],
+[
+  dnl Persuade glibc <string.h> to declare mempcpy().
+  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
+
+  dnl The mempcpy() declaration in lib/string.in.h uses 'restrict'.
+  AC_REQUIRE([AC_C_RESTRICT])
+
+  AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
+  AC_CHECK_FUNCS([mempcpy])
+  if test $ac_cv_func_mempcpy = no; then
+    HAVE_MEMPCPY=0
+  fi
+])
+
+# Prerequisites of lib/mempcpy.c.
+AC_DEFUN([gl_PREREQ_MEMPCPY], [
+  :
+])
diff --git a/m4/memrchr.m4 b/m4/memrchr.m4
index e907590..95990ed 100644
--- a/m4/memrchr.m4
+++ b/m4/memrchr.m4
@@ -1,5 +1,5 @@
 # memrchr.m4 serial 10
-dnl Copyright (C) 2002-2003, 2005-2007, 2009-2019 Free Software Foundation,
+dnl Copyright (C) 2002-2003, 2005-2007, 2009-2020 Free Software Foundation,
 dnl Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
diff --git a/m4/minmax.m4 b/m4/minmax.m4
index 1e0d30b..e5b28b0 100644
--- a/m4/minmax.m4
+++ b/m4/minmax.m4
@@ -1,5 +1,5 @@
 # minmax.m4 serial 4
-dnl Copyright (C) 2005, 2009-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2005, 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.
diff --git a/m4/mkdir.m4 b/m4/mkdir.m4
index 366a3cd..bd9e088 100644
--- a/m4/mkdir.m4
+++ b/m4/mkdir.m4
@@ -1,6 +1,6 @@
-# serial 15
+# serial 17
 
-# Copyright (C) 2001, 2003-2004, 2006, 2008-2019 Free Software Foundation, Inc.
+# Copyright (C) 2001, 2003-2004, 2006, 2008-2020 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.
@@ -16,33 +16,34 @@ AC_DEFUN([gl_FUNC_MKDIR],
   AC_CACHE_CHECK([whether mkdir handles trailing slash],
     [gl_cv_func_mkdir_trailing_slash_works],
     [rm -rf conftest.dir
-      AC_RUN_IFELSE([AC_LANG_PROGRAM([[
-#       include <sys/types.h>
-#       include <sys/stat.h>
-]], [return mkdir ("conftest.dir/", 0700);])],
-      [gl_cv_func_mkdir_trailing_slash_works=yes],
-      [gl_cv_func_mkdir_trailing_slash_works=no],
-      [case "$host_os" in
-                          # Guess yes on Linux systems.
-         linux-* | linux) gl_cv_func_mkdir_trailing_slash_works="guessing yes" ;;
-                          # Guess yes on glibc systems.
-         *-gnu* | gnu*)   gl_cv_func_mkdir_trailing_slash_works="guessing yes" ;;
-                          # Guess yes on MSVC, no on mingw.
-         mingw*)          AC_EGREP_CPP([Known], [
+     AC_RUN_IFELSE(
+       [AC_LANG_PROGRAM([[
+          #include <sys/types.h>
+          #include <sys/stat.h>
+          ]GL_MDA_DEFINES],
+          [[return mkdir ("conftest.dir/", 0700);]])],
+       [gl_cv_func_mkdir_trailing_slash_works=yes],
+       [gl_cv_func_mkdir_trailing_slash_works=no],
+       [case "$host_os" in
+                           # Guess yes on Linux systems.
+          linux-* | linux) gl_cv_func_mkdir_trailing_slash_works="guessing yes" ;;
+                           # Guess yes on glibc systems.
+          *-gnu* | gnu*)   gl_cv_func_mkdir_trailing_slash_works="guessing yes" ;;
+                           # Guess yes on MSVC, no on mingw.
+          mingw*)          AC_EGREP_CPP([Known], [
 #ifdef _MSC_VER
  Known
 #endif
-                            ],
-                            [gl_cv_func_mkdir_trailing_slash_works="guessing yes"],
-                            [gl_cv_func_mkdir_trailing_slash_works="guessing no"])
-                          ;;
-                          # If we don't know, assume the worst.
-         *)               gl_cv_func_mkdir_trailing_slash_works="guessing no" ;;
-       esac
-      ])
-    rm -rf conftest.dir
-    ]
-  )
+                             ],
+                             [gl_cv_func_mkdir_trailing_slash_works="guessing yes"],
+                             [gl_cv_func_mkdir_trailing_slash_works="guessing no"])
+                           ;;
+                           # If we don't know, obey --enable-cross-guesses.
+          *)               gl_cv_func_mkdir_trailing_slash_works="$gl_cross_guess_normal" ;;
+        esac
+       ])
+     rm -rf conftest.dir
+    ])
   case "$gl_cv_func_mkdir_trailing_slash_works" in
     *yes) ;;
     *)
@@ -53,24 +54,26 @@ AC_DEFUN([gl_FUNC_MKDIR],
   AC_CACHE_CHECK([whether mkdir handles trailing dot],
     [gl_cv_func_mkdir_trailing_dot_works],
     [rm -rf conftest.dir
-      AC_RUN_IFELSE([AC_LANG_PROGRAM([[
-#       include <sys/types.h>
-#       include <sys/stat.h>
-]], [return !mkdir ("conftest.dir/./", 0700);])],
-      [gl_cv_func_mkdir_trailing_dot_works=yes],
-      [gl_cv_func_mkdir_trailing_dot_works=no],
-      [case "$host_os" in
-                        # Guess yes on glibc systems.
-         *-gnu* | gnu*) gl_cv_func_mkdir_trailing_dot_works="guessing yes" ;;
-                        # Guess yes on musl systems.
-         *-musl*)       gl_cv_func_mkdir_trailing_dot_works="guessing yes" ;;
-                        # Guess no on native Windows.
-         mingw*)        gl_cv_func_mkdir_trailing_dot_works="guessing no" ;;
-                        # If we don't know, assume the worst.
-         *)             gl_cv_func_mkdir_trailing_dot_works="guessing no" ;;
-       esac
-      ])
-    rm -rf conftest.dir
+     AC_RUN_IFELSE(
+       [AC_LANG_PROGRAM([[
+          #include <sys/types.h>
+          #include <sys/stat.h>
+          ]GL_MDA_DEFINES],
+          [[return !mkdir ("conftest.dir/./", 0700);]])],
+       [gl_cv_func_mkdir_trailing_dot_works=yes],
+       [gl_cv_func_mkdir_trailing_dot_works=no],
+       [case "$host_os" in
+                         # Guess yes on glibc systems.
+          *-gnu* | gnu*) gl_cv_func_mkdir_trailing_dot_works="guessing yes" ;;
+                         # Guess yes on musl systems.
+          *-musl*)       gl_cv_func_mkdir_trailing_dot_works="guessing yes" ;;
+                         # Guess no on native Windows.
+          mingw*)        gl_cv_func_mkdir_trailing_dot_works="guessing no" ;;
+                         # If we don't know, obey --enable-cross-guesses.
+          *)             gl_cv_func_mkdir_trailing_dot_works="$gl_cross_guess_normal" ;;
+        esac
+       ])
+     rm -rf conftest.dir
     ]
   )
   case "$gl_cv_func_mkdir_trailing_dot_works" in
diff --git a/m4/mkostemp.m4 b/m4/mkostemp.m4
index 56f566c..3e5b555 100644
--- a/m4/mkostemp.m4
+++ b/m4/mkostemp.m4
@@ -1,5 +1,5 @@
 # mkostemp.m4 serial 2
-dnl Copyright (C) 2009-2019 Free Software Foundation, Inc.
+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.
diff --git a/m4/mkstemp.m4 b/m4/mkstemp.m4
index 1b15c2e..392f97c 100644
--- a/m4/mkstemp.m4
+++ b/m4/mkstemp.m4
@@ -1,6 +1,6 @@
-#serial 26
+#serial 28
 
-# Copyright (C) 2001, 2003-2007, 2009-2019 Free Software Foundation, Inc.
+# Copyright (C) 2001, 2003-2007, 2009-2020 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.
@@ -26,7 +26,8 @@ AC_DEFUN([gl_FUNC_MKSTEMP],
         mkdir conftest.mkstemp
         AC_RUN_IFELSE(
           [AC_LANG_PROGRAM(
-            [AC_INCLUDES_DEFAULT],
+            [AC_INCLUDES_DEFAULT
+             GL_MDA_DEFINES],
             [[int result = 0;
               int i;
               off_t large = (off_t) 4294967295u;
@@ -63,8 +64,8 @@ AC_DEFUN([gl_FUNC_MKSTEMP],
              *-musl*)       gl_cv_func_working_mkstemp="guessing yes" ;;
                             # Guess no on native Windows.
              mingw*)        gl_cv_func_working_mkstemp="guessing no" ;;
-                            # If we don't know, assume the worst.
-             *)             gl_cv_func_working_mkstemp="guessing no" ;;
+                            # If we don't know, obey --enable-cross-guesses.
+             *)             gl_cv_func_working_mkstemp="$gl_cross_guess_normal" ;;
            esac
           ])
         rm -rf conftest.mkstemp
diff --git a/m4/mktime.m4 b/m4/mktime.m4
index a86e1ee..4e7e423 100644
--- a/m4/mktime.m4
+++ b/m4/mktime.m4
@@ -1,5 +1,5 @@
-# serial 30
-dnl Copyright (C) 2002-2003, 2005-2007, 2009-2019 Free Software Foundation,
+# 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
 dnl gives unlimited permission to copy and/or distribute it,
@@ -31,17 +31,16 @@ 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])
-  if test $APPLE_UNIVERSAL_BUILD = 1; then
-    # A universal build on Apple Mac OS X platforms.
-    # The test result would be 'yes' in 32-bit mode and 'no' in 64-bit mode.
-    # But we need a configuration result that is valid in both modes.
-    gl_cv_func_working_mktime=no
-  fi
   AC_CACHE_CHECK([for working mktime], [gl_cv_func_working_mktime],
-    [AC_RUN_IFELSE(
-       [AC_LANG_SOURCE(
+    [if test $APPLE_UNIVERSAL_BUILD = 1; then
+       # A universal build on Apple Mac OS X platforms.
+       # The test result would be 'yes' in 32-bit mode and 'no' in 64-bit mode.
+       # But we need a configuration result that is valid in both modes.
+       gl_cv_func_working_mktime="guessing no"
+     else
+       AC_RUN_IFELSE(
+         [AC_LANG_SOURCE(
 [[/* Test program from Paul Eggert and Tony Leneis.  */
 #include <limits.h>
 #include <stdlib.h>
@@ -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;
 
@@ -242,14 +240,15 @@ main ()
     result |= 64;
   return result;
 }]])],
-       [gl_cv_func_working_mktime=yes],
-       [gl_cv_func_working_mktime=no],
-       [case "$host_os" in
-                  # Guess no on native Windows.
-          mingw*) gl_cv_func_working_mktime="guessing no" ;;
-          *)      gl_cv_func_working_mktime="guessing no" ;;
-        esac
-       ])
+         [gl_cv_func_working_mktime=yes],
+         [gl_cv_func_working_mktime=no],
+         [case "$host_os" in
+                    # Guess no on native Windows.
+            mingw*) gl_cv_func_working_mktime="guessing no" ;;
+            *)      gl_cv_func_working_mktime="$gl_cross_guess_normal" ;;
+          esac
+         ])
+     fi
     ])
 ])
 
diff --git a/m4/mmap-anon.m4 b/m4/mmap-anon.m4
index 50c3808..2995ad5 100644
--- a/m4/mmap-anon.m4
+++ b/m4/mmap-anon.m4
@@ -1,5 +1,5 @@
-# mmap-anon.m4 serial 10
-dnl Copyright (C) 2005, 2007, 2009-2019 Free Software Foundation, Inc.
+# mmap-anon.m4 serial 11
+dnl Copyright (C) 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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -9,7 +9,7 @@ dnl with or without modifications, as long as this notice is preserved.
 # - On Linux, AIX, OSF/1, Solaris, Cygwin, Interix, Haiku, both MAP_ANONYMOUS
 #   and MAP_ANON exist and have the same value.
 # - On HP-UX, only MAP_ANONYMOUS exists.
-# - On Mac OS X, FreeBSD, NetBSD, OpenBSD, only MAP_ANON exists.
+# - On Mac OS X, FreeBSD, NetBSD, OpenBSD, Minix, only MAP_ANON exists.
 # - On IRIX, neither exists, and a file descriptor opened to /dev/zero must be
 #   used.
 
diff --git a/m4/mode_t.m4 b/m4/mode_t.m4
index ba840dc..f190951 100644
--- a/m4/mode_t.m4
+++ b/m4/mode_t.m4
@@ -1,5 +1,5 @@
 # mode_t.m4 serial 2
-dnl Copyright (C) 2009-2019 Free Software Foundation, Inc.
+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.
diff --git a/m4/msvc-inval.m4 b/m4/msvc-inval.m4
index 4b95876..dcf398d 100644
--- a/m4/msvc-inval.m4
+++ b/m4/msvc-inval.m4
@@ -1,5 +1,5 @@
 # msvc-inval.m4 serial 1
-dnl Copyright (C) 2011-2019 Free Software Foundation, Inc.
+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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/msvc-nothrow.m4 b/m4/msvc-nothrow.m4
index 7e73b40..13198d8 100644
--- a/m4/msvc-nothrow.m4
+++ b/m4/msvc-nothrow.m4
@@ -1,5 +1,5 @@
 # msvc-nothrow.m4 serial 1
-dnl Copyright (C) 2011-2019 Free Software Foundation, Inc.
+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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/multiarch.m4 b/m4/multiarch.m4
index d48316e..2c61afb 100644
--- a/m4/multiarch.m4
+++ b/m4/multiarch.m4
@@ -1,5 +1,5 @@
-# multiarch.m4 serial 7
-dnl Copyright (C) 2008-2019 Free Software Foundation, Inc.
+# multiarch.m4 serial 9
+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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -21,37 +21,40 @@ dnl with or without modifications, as long as this notice is preserved.
 AC_DEFUN_ONCE([gl_MULTIARCH],
 [
   dnl Code similar to autoconf-2.63 AC_C_BIGENDIAN.
-  gl_cv_c_multiarch=no
-  AC_COMPILE_IFELSE(
-    [AC_LANG_SOURCE(
-      [[#ifndef __APPLE_CC__
-         not a universal capable compiler
-        #endif
-        typedef int dummy;
-      ]])],
-    [
-     dnl Check for potential -arch flags.  It is not universal unless
-     dnl there are at least two -arch flags with different values.
-     arch=
-     prev=
-     for word in ${CC} ${CFLAGS} ${CPPFLAGS} ${LDFLAGS}; do
-       if test -n "$prev"; then
-         case $word in
-           i?86 | x86_64 | ppc | ppc64)
-             if test -z "$arch" || test "$arch" = "$word"; then
-               arch="$word"
-             else
-               gl_cv_c_multiarch=yes
-             fi
-             ;;
-         esac
-         prev=
-       else
-         if test "x$word" = "x-arch"; then
-           prev=arch
-         fi
-       fi
-     done
+  AC_CACHE_CHECK([whether the compiler produces multi-arch binaries],
+    [gl_cv_c_multiarch],
+    [gl_cv_c_multiarch=no
+     AC_COMPILE_IFELSE(
+       [AC_LANG_SOURCE(
+         [[#ifndef __APPLE_CC__
+            not a universal capable compiler
+           #endif
+           typedef int dummy;
+         ]])],
+       [
+        dnl Check for potential -arch flags.  It is not universal unless
+        dnl there are at least two -arch flags with different values.
+        arch=
+        prev=
+        for word in ${CC} ${CFLAGS} ${CPPFLAGS} ${LDFLAGS}; do
+          if test -n "$prev"; then
+            case $word in
+              i?86 | x86_64 | ppc | ppc64 | arm | arm64)
+                if test -z "$arch" || test "$arch" = "$word"; then
+                  arch="$word"
+                else
+                  gl_cv_c_multiarch=yes
+                fi
+                ;;
+            esac
+            prev=
+          else
+            if test "x$word" = "x-arch"; then
+              prev=arch
+            fi
+          fi
+        done
+       ])
     ])
   if test $gl_cv_c_multiarch = yes; then
     APPLE_UNIVERSAL_BUILD=1
diff --git a/m4/nanosleep.m4 b/m4/nanosleep.m4
index 971aae3..1fb13ed 100644
--- a/m4/nanosleep.m4
+++ b/m4/nanosleep.m4
@@ -1,11 +1,11 @@
-# serial 38
+# serial 39
 
 dnl From Jim Meyering.
 dnl Check for the nanosleep function.
 dnl If not found, use the supplied replacement.
 dnl
 
-# Copyright (C) 1999-2001, 2003-2019 Free Software Foundation, Inc.
+# Copyright (C) 1999-2001, 2003-2020 Free Software Foundation, Inc.
 
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -119,8 +119,8 @@ AC_DEFUN([gl_FUNC_NANOSLEEP],
             gl_cv_func_nanosleep='guessing no (mishandles large arguments)' ;;
           mingw*) # Guess no on native Windows.
             gl_cv_func_nanosleep='guessing no' ;;
-          *)      # If we don't know, assume the worst.
-            gl_cv_func_nanosleep='guessing no' ;;
+          *)      # If we don't know, obey --enable-cross-guesses.
+            gl_cv_func_nanosleep="$gl_cross_guess_normal" ;;
         esac
        ])
     ])
diff --git a/m4/netdb_h.m4 b/m4/netdb_h.m4
index 498c566..143a2c8 100644
--- a/m4/netdb_h.m4
+++ b/m4/netdb_h.m4
@@ -1,5 +1,5 @@
-# netdb_h.m4 serial 11
-dnl Copyright (C) 2008-2019 Free Software Foundation, Inc.
+# netdb_h.m4 serial 12
+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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -40,4 +40,5 @@ AC_DEFUN([gl_NETDB_H_DEFAULTS],
   HAVE_DECL_GETADDRINFO=1;  AC_SUBST([HAVE_DECL_GETADDRINFO])
   HAVE_DECL_GETNAMEINFO=1;  AC_SUBST([HAVE_DECL_GETNAMEINFO])
   REPLACE_GAI_STRERROR=0;   AC_SUBST([REPLACE_GAI_STRERROR])
+  REPLACE_GETADDRINFO=0;    AC_SUBST([REPLACE_GETADDRINFO])
 ])
diff --git a/m4/netinet_in_h.m4 b/m4/netinet_in_h.m4
index 0f96cae..df9f383 100644
--- a/m4/netinet_in_h.m4
+++ b/m4/netinet_in_h.m4
@@ -1,5 +1,5 @@
 # netinet_in_h.m4 serial 5
-dnl Copyright (C) 2006-2019 Free Software Foundation, Inc.
+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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/nl_langinfo.m4 b/m4/nl_langinfo.m4
index 66eee41..342afd2 100644
--- a/m4/nl_langinfo.m4
+++ b/m4/nl_langinfo.m4
@@ -1,5 +1,5 @@
-# nl_langinfo.m4 serial 6
-dnl Copyright (C) 2009-2019 Free Software Foundation, Inc.
+# nl_langinfo.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.
@@ -9,7 +9,10 @@ AC_DEFUN([gl_FUNC_NL_LANGINFO],
   AC_REQUIRE([gl_LANGINFO_H_DEFAULTS])
   AC_REQUIRE([gl_LANGINFO_H])
   AC_CHECK_FUNCS_ONCE([nl_langinfo])
-  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  AC_REQUIRE([gl_FUNC_SETLOCALE_NULL])
+  AC_REQUIRE([gl_PTHREADLIB])
+  AC_CHECK_HEADERS_ONCE([threads.h])
   if test $ac_cv_func_nl_langinfo = yes; then
     # On Irix 6.5, YESEXPR is defined, but nl_langinfo(YESEXPR) is broken.
     AC_CACHE_CHECK([whether YESEXPR works],
@@ -36,11 +39,19 @@ AC_DEFUN([gl_FUNC_NL_LANGINFO],
     AC_DEFINE_UNQUOTED([FUNC_NL_LANGINFO_YESEXPR_WORKS],
       [$FUNC_NL_LANGINFO_YESEXPR_WORKS],
       [Define to 1 if nl_langinfo (YESEXPR) returns a non-empty string.])
+    # On Solaris 10 and Solaris 11.3, nl_langinfo is not multithread-safe.
+    case "$host_os" in
+      solaris*) NL_LANGINFO_MTSAFE=0 ;;
+      *)        NL_LANGINFO_MTSAFE=1 ;;
+    esac
+    AC_DEFINE_UNQUOTED([NL_LANGINFO_MTSAFE], [$NL_LANGINFO_MTSAFE],
+      [Define to 1 if nl_langinfo is multithread-safe.])
     if test $HAVE_LANGINFO_CODESET = 1 \
        && test $HAVE_LANGINFO_T_FMT_AMPM = 1 \
        && test $HAVE_LANGINFO_ALTMON = 1 \
        && test $HAVE_LANGINFO_ERA = 1 \
-       && test $FUNC_NL_LANGINFO_YESEXPR_WORKS = 1; then
+       && test $FUNC_NL_LANGINFO_YESEXPR_WORKS = 1 \
+       && test $NL_LANGINFO_MTSAFE = 1; then
       :
     else
       REPLACE_NL_LANGINFO=1
@@ -50,4 +61,17 @@ AC_DEFUN([gl_FUNC_NL_LANGINFO],
   else
     HAVE_NL_LANGINFO=0
   fi
+  if test $HAVE_NL_LANGINFO = 0 || test $HAVE_LANGINFO_CODESET = 0; then
+    LIB_NL_LANGINFO="$LIB_SETLOCALE_NULL"
+  else
+    LIB_NL_LANGINFO=
+  fi
+  dnl LIB_NL_LANGINFO is expected to be empty everywhere.
+  AC_SUBST([LIB_NL_LANGINFO])
+])
+
+# Prerequisites of lib/nl_langinfo-lock.c.
+AC_DEFUN([gl_PREREQ_NL_LANGINFO_LOCK],
+[
+  gl_VISIBILITY
 ])
diff --git a/m4/nls.m4 b/m4/nls.m4
index 7967cc2..53cdc8b 100644
--- a/m4/nls.m4
+++ b/m4/nls.m4
@@ -1,5 +1,6 @@
-# nls.m4 serial 3 (gettext-0.15)
-dnl Copyright (C) 1995-2003, 2005-2006 Free Software Foundation, Inc.
+# nls.m4 serial 5 (gettext-0.18)
+dnl Copyright (C) 1995-2003, 2005-2006, 2008-2014 Free Software Foundation,
+dnl 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.
@@ -17,15 +18,15 @@ dnl Authors:
 dnl   Ulrich Drepper <drepper@cygnus.com>, 1995-2000.
 dnl   Bruno Haible <haible@clisp.cons.org>, 2000-2003.
 
-AC_PREREQ(2.50)
+AC_PREREQ([2.50])
 
 AC_DEFUN([AM_NLS],
 [
   AC_MSG_CHECKING([whether NLS is requested])
   dnl Default is enabled NLS
-  AC_ARG_ENABLE(nls,
+  AC_ARG_ENABLE([nls],
     [  --disable-nls           do not use Native Language Support],
     USE_NLS=$enableval, USE_NLS=yes)
-  AC_MSG_RESULT($USE_NLS)
-  AC_SUBST(USE_NLS)
+  AC_MSG_RESULT([$USE_NLS])
+  AC_SUBST([USE_NLS])
 ])
diff --git a/m4/nocrash.m4 b/m4/nocrash.m4
index 4d9f022..637a0ea 100644
--- a/m4/nocrash.m4
+++ b/m4/nocrash.m4
@@ -1,5 +1,5 @@
 # nocrash.m4 serial 5
-dnl Copyright (C) 2005, 2009-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2005, 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.
@@ -53,7 +53,7 @@ nocrash_init (void)
   /* Allocate a port on which the thread shall listen for exceptions.  */
   if (mach_port_allocate (self, MACH_PORT_RIGHT_RECEIVE, &our_exception_port)
       == KERN_SUCCESS) {
-    /* See http://web.mit.edu/darwin/src/modules/xnu/osfmk/man/mach_port_insert_right.html.  */
+    /* See https://web.mit.edu/darwin/src/modules/xnu/osfmk/man/mach_port_insert_right.html.  */
     if (mach_port_insert_right (self, our_exception_port, our_exception_port,
                                 MACH_MSG_TYPE_MAKE_SEND)
         == KERN_SUCCESS) {
@@ -72,7 +72,7 @@ nocrash_init (void)
            for a particular thread.  This has the effect that when our exception
            port gets the message, the thread specific exception port has already
            been asked, and we don't need to bother about it.
-           See http://web.mit.edu/darwin/src/modules/xnu/osfmk/man/task_set_exception_ports.html.  */
+           See https://web.mit.edu/darwin/src/modules/xnu/osfmk/man/task_set_exception_ports.html.  */
         task_set_exception_ports (self, mask, our_exception_port,
                                   EXCEPTION_DEFAULT, MACHINE_THREAD_STATE);
       }
diff --git a/m4/off_t.m4 b/m4/off_t.m4
index 711a2d4..6e19af8 100644
--- a/m4/off_t.m4
+++ b/m4/off_t.m4
@@ -1,5 +1,5 @@
 # off_t.m4 serial 1
-dnl Copyright (C) 2012-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2012-2020 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.
diff --git a/m4/open-cloexec.m4 b/m4/open-cloexec.m4
index 52498d9..11652d5 100644
--- a/m4/open-cloexec.m4
+++ b/m4/open-cloexec.m4
@@ -1,6 +1,6 @@
 # Test whether O_CLOEXEC is defined.
 
-dnl Copyright 2017-2019 Free Software Foundation, Inc.
+dnl Copyright 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.
diff --git a/m4/open-slash.m4 b/m4/open-slash.m4
new file mode 100644
index 0000000..5d84f2b
--- /dev/null
+++ b/m4/open-slash.m4
@@ -0,0 +1,60 @@
+# 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,
+dnl with or without modifications, as long as this notice is preserved.
+
+dnl Tests whether open() and creat() recognize a trailing slash.
+dnl Sets gl_cv_func_open_slash.
+AC_DEFUN([gl_OPEN_TRAILING_SLASH_BUG],
+[
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  dnl open("foo/") should not create a file when the file name has a
+  dnl trailing slash.  FreeBSD only has the problem on symlinks.
+  AC_CHECK_FUNCS_ONCE([lstat])
+  AC_CACHE_CHECK([whether open recognizes a trailing slash],
+    [gl_cv_func_open_slash],
+    [# Assume that if we have lstat, we can also check symlinks.
+     if test $ac_cv_func_lstat = yes; then
+       touch conftest.tmp
+       ln -s conftest.tmp conftest.lnk
+     fi
+     AC_RUN_IFELSE(
+       [AC_LANG_SOURCE([[
+#include <fcntl.h>
+#if HAVE_UNISTD_H
+# include <unistd.h>
+#endif
+]GL_MDA_DEFINES[
+int main ()
+{
+  int result = 0;
+#if HAVE_LSTAT
+  if (open ("conftest.lnk/", O_RDONLY) != -1)
+    result |= 1;
+#endif
+  if (open ("conftest.sl/", O_CREAT, 0600) >= 0)
+    result |= 2;
+  return result;
+}]])],
+       [gl_cv_func_open_slash=yes],
+       [gl_cv_func_open_slash=no],
+       [
+changequote(,)dnl
+        case "$host_os" in
+          freebsd* | aix* | hpux* | solaris2.[0-9] | solaris2.[0-9].*)
+            gl_cv_func_open_slash="guessing no" ;;
+          *)
+            gl_cv_func_open_slash="guessing yes" ;;
+        esac
+changequote([,])dnl
+       ])
+     rm -f conftest.sl conftest.tmp conftest.lnk
+    ])
+  case "$gl_cv_func_open_slash" in
+    *no)
+      AC_DEFINE([OPEN_TRAILING_SLASH_BUG], [1],
+        [Define to 1 if open() fails to recognize a trailing slash.])
+      ;;
+  esac
+])
diff --git a/m4/open.m4 b/m4/open.m4
index 5d73f4d..552eedf 100644
--- a/m4/open.m4
+++ b/m4/open.m4
@@ -1,5 +1,5 @@
 # open.m4 serial 15
-dnl Copyright (C) 2007-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2007-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
@@ -19,48 +19,9 @@ AC_DEFUN([gl_FUNC_OPEN],
       if test "$gl_cv_macro_O_CLOEXEC" != yes; then
         REPLACE_OPEN=1
       fi
-      AC_CACHE_CHECK([whether open recognizes a trailing slash],
-        [gl_cv_func_open_slash],
-        [# Assume that if we have lstat, we can also check symlinks.
-          if test $ac_cv_func_lstat = yes; then
-            touch conftest.tmp
-            ln -s conftest.tmp conftest.lnk
-          fi
-          AC_RUN_IFELSE(
-            [AC_LANG_SOURCE([[
-#include <fcntl.h>
-#if HAVE_UNISTD_H
-# include <unistd.h>
-#endif
-int main ()
-{
-  int result = 0;
-#if HAVE_LSTAT
-  if (open ("conftest.lnk/", O_RDONLY) != -1)
-    result |= 1;
-#endif
-  if (open ("conftest.sl/", O_CREAT, 0600) >= 0)
-    result |= 2;
-  return result;
-}]])],
-            [gl_cv_func_open_slash=yes],
-            [gl_cv_func_open_slash=no],
-            [
-changequote(,)dnl
-             case "$host_os" in
-               freebsd* | aix* | hpux* | solaris2.[0-9] | solaris2.[0-9].*)
-                 gl_cv_func_open_slash="guessing no" ;;
-               *)
-                 gl_cv_func_open_slash="guessing yes" ;;
-             esac
-changequote([,])dnl
-            ])
-          rm -f conftest.sl conftest.tmp conftest.lnk
-        ])
+      gl_OPEN_TRAILING_SLASH_BUG
       case "$gl_cv_func_open_slash" in
         *no)
-          AC_DEFINE([OPEN_TRAILING_SLASH_BUG], [1],
-            [Define to 1 if open() fails to recognize a trailing slash.])
           REPLACE_OPEN=1
           ;;
       esac
diff --git a/m4/openat.m4 b/m4/openat.m4
new file mode 100644
index 0000000..cf9f717
--- /dev/null
+++ b/m4/openat.m4
@@ -0,0 +1,38 @@
+# serial 46
+# See if we need to use our replacement for Solaris' openat et al functions.
+
+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,
+dnl with or without modifications, as long as this notice is preserved.
+
+# Written by Jim Meyering.
+
+AC_DEFUN([gl_FUNC_OPENAT],
+[
+  AC_REQUIRE([gl_FCNTL_H_DEFAULTS])
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+  AC_CHECK_FUNCS_ONCE([openat])
+  AC_REQUIRE([gl_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK])
+  AC_REQUIRE([gl_PREPROC_O_CLOEXEC])
+  case $ac_cv_func_openat+$gl_cv_func_lstat_dereferences_slashed_symlink+$gl_cv_macro_O_CLOEXEC in
+  yes+*yes+yes)
+    ;;
+  yes+*)
+    # Solaris 10 lacks O_CLOEXEC.
+    # Solaris 9 has *at functions, but uniformly mishandles trailing
+    # slash in all of them.
+    REPLACE_OPENAT=1
+    ;;
+  *)
+    HAVE_OPENAT=0
+    ;;
+  esac
+])
+
+# Prerequisites of lib/openat.c.
+AC_DEFUN([gl_PREREQ_OPENAT],
+[
+  AC_REQUIRE([gl_PROMOTED_TYPE_MODE_T])
+  :
+])
diff --git a/m4/opendir.m4 b/m4/opendir.m4
new file mode 100644
index 0000000..fd3c1ec
--- /dev/null
+++ b/m4/opendir.m4
@@ -0,0 +1,32 @@
+# opendir.m4 serial 5
+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,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_FUNC_OPENDIR],
+[
+  AC_REQUIRE([gl_DIRENT_H_DEFAULTS])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+
+  AC_CHECK_FUNCS([opendir])
+  if test $ac_cv_func_opendir = no; then
+    HAVE_OPENDIR=0
+  fi
+  dnl Replace opendir() for supporting the gnulib-defined fchdir() function,
+  dnl to keep fchdir's bookkeeping up-to-date.
+  m4_ifdef([gl_FUNC_FCHDIR], [
+    gl_TEST_FCHDIR
+    if test $HAVE_FCHDIR = 0; then
+      if test $HAVE_OPENDIR = 1; then
+        REPLACE_OPENDIR=1
+      fi
+    fi
+  ])
+  dnl Replace opendir() on OS/2 kLIBC to support dirfd() function replaced
+  dnl by gnulib.
+  case $host_os,$HAVE_OPENDIR in
+    os2*,1)
+      REPLACE_OPENDIR=1;;
+  esac
+])
diff --git a/m4/pathmax.m4 b/m4/pathmax.m4
index 0770aca..bb4fdeb 100644
--- a/m4/pathmax.m4
+++ b/m4/pathmax.m4
@@ -1,5 +1,5 @@
 # pathmax.m4 serial 11
-dnl Copyright (C) 2002-2003, 2005-2006, 2009-2019 Free Software Foundation,
+dnl Copyright (C) 2002-2003, 2005-2006, 2009-2020 Free Software Foundation,
 dnl Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
diff --git a/m4/pipe.m4 b/m4/pipe.m4
index 199cfef..6b1fa2f 100644
--- a/m4/pipe.m4
+++ b/m4/pipe.m4
@@ -1,5 +1,5 @@
 # pipe.m4 serial 2
-dnl Copyright (C) 2010-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2010-2020 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.
diff --git a/m4/pipe2.m4 b/m4/pipe2.m4
index 03008eb..d36821e 100644
--- a/m4/pipe2.m4
+++ b/m4/pipe2.m4
@@ -1,5 +1,5 @@
 # pipe2.m4 serial 2
-dnl Copyright (C) 2009-2019 Free Software Foundation, Inc.
+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.
diff --git a/m4/po.m4 b/m4/po.m4
index 0734762..84659ea 100644
--- a/m4/po.m4
+++ b/m4/po.m4
@@ -1,5 +1,5 @@
-# po.m4 serial 15 (gettext-0.17)
-dnl Copyright (C) 1995-2007 Free Software Foundation, Inc.
+# po.m4 serial 22 (gettext-0.19)
+dnl Copyright (C) 1995-2014 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.
@@ -17,19 +17,20 @@ dnl Authors:
 dnl   Ulrich Drepper <drepper@cygnus.com>, 1995-2000.
 dnl   Bruno Haible <haible@clisp.cons.org>, 2000-2003.
 
-AC_PREREQ(2.50)
+AC_PREREQ([2.60])
 
 dnl Checks for all prerequisites of the po subdirectory.
 AC_DEFUN([AM_PO_SUBDIRS],
 [
   AC_REQUIRE([AC_PROG_MAKE_SET])dnl
   AC_REQUIRE([AC_PROG_INSTALL])dnl
-  AC_REQUIRE([AM_PROG_MKDIR_P])dnl defined by automake
+  AC_REQUIRE([AC_PROG_MKDIR_P])dnl
+  AC_REQUIRE([AC_PROG_SED])dnl
   AC_REQUIRE([AM_NLS])dnl
 
   dnl Release version of the gettext macros. This is used to ensure that
   dnl the gettext macros and po/Makefile.in.in are in sync.
-  AC_SUBST([GETTEXT_MACRO_VERSION], [0.17])
+  AC_SUBST([GETTEXT_MACRO_VERSION], [0.19])
 
   dnl Perform the following tests also if --disable-nls has been given,
   dnl because they are needed for "make dist" to work.
@@ -41,7 +42,7 @@ AC_DEFUN([AM_PO_SUBDIRS],
     [$ac_dir/$ac_word --statistics /dev/null >&]AS_MESSAGE_LOG_FD[ 2>&1 &&
      (if $ac_dir/$ac_word --statistics /dev/null 2>&1 >/dev/null | grep usage >/dev/null; then exit 1; else exit 0; fi)],
     :)
-  AC_PATH_PROG(GMSGFMT, gmsgfmt, $MSGFMT)
+  AC_PATH_PROG([GMSGFMT], [gmsgfmt], [$MSGFMT])
 
   dnl Test whether it is GNU msgfmt >= 0.15.
 changequote(,)dnl
@@ -102,7 +103,7 @@ changequote([,])dnl
       case "$ac_file" in */Makefile.in)
         # Adjust a relative srcdir.
         ac_dir=`echo "$ac_file"|sed 's%/[^/][^/]*$%%'`
-        ac_dir_suffix="/`echo "$ac_dir"|sed 's%^\./%%'`"
+        ac_dir_suffix=/`echo "$ac_dir"|sed 's%^\./%%'`
         ac_dots=`echo "$ac_dir_suffix"|sed 's%/[^/]*%../%g'`
         # In autoconf-2.13 it is called $ac_given_srcdir.
         # In autoconf-2.50 it is called $srcdir.
@@ -118,7 +119,8 @@ changequote([,])dnl
         if test -f "$ac_given_srcdir/$ac_dir/POTFILES.in"; then
           rm -f "$ac_dir/POTFILES"
           test -n "$as_me" && echo "$as_me: creating $ac_dir/POTFILES" || echo "creating $ac_dir/POTFILES"
-          cat "$ac_given_srcdir/$ac_dir/POTFILES.in" | sed -e "/^#/d" -e "/^[ 	]*\$/d" -e "s,.*,     $top_srcdir/& \\\\," | sed -e "\$s/\(.*\) \\\\/\1/" > "$ac_dir/POTFILES"
+          gt_tab=`printf '\t'`
+          cat "$ac_given_srcdir/$ac_dir/POTFILES.in" | sed -e "/^#/d" -e "/^[ ${gt_tab}]*\$/d" -e "s,.*,     $top_srcdir/& \\\\," | sed -e "\$s/\(.*\) \\\\/\1/" > "$ac_dir/POTFILES"
           POMAKEFILEDEPS="POTFILES.in"
           # ALL_LINGUAS, POFILES, UPDATEPOFILES, DUMMYPOFILES, GMOFILES depend
           # on $ac_dir but don't depend on user-specified configuration
@@ -129,12 +131,12 @@ changequote([,])dnl
               test -n "$as_me" && echo "$as_me: setting ALL_LINGUAS in configure.in is obsolete" || echo "setting ALL_LINGUAS in configure.in is obsolete"
             fi
             ALL_LINGUAS_=`sed -e "/^#/d" -e "s/#.*//" "$ac_given_srcdir/$ac_dir/LINGUAS"`
-            # Hide the ALL_LINGUAS assigment from automake < 1.5.
+            # Hide the ALL_LINGUAS assignment from automake < 1.5.
             eval 'ALL_LINGUAS''=$ALL_LINGUAS_'
             POMAKEFILEDEPS="$POMAKEFILEDEPS LINGUAS"
           else
             # The set of available languages was given in configure.in.
-            # Hide the ALL_LINGUAS assigment from automake < 1.5.
+            # Hide the ALL_LINGUAS assignment from automake < 1.5.
             eval 'ALL_LINGUAS''=$OBSOLETE_ALL_LINGUAS'
           fi
           # Compute POFILES
@@ -226,7 +228,7 @@ AC_DEFUN([AM_POSTPROCESS_PO_MAKEFILE],
 changequote(,)dnl
   # Adjust a relative srcdir.
   ac_dir=`echo "$ac_file"|sed 's%/[^/][^/]*$%%'`
-  ac_dir_suffix="/`echo "$ac_dir"|sed 's%^\./%%'`"
+  ac_dir_suffix=/`echo "$ac_dir"|sed 's%^\./%%'`
   ac_dots=`echo "$ac_dir_suffix"|sed 's%/[^/]*%../%g'`
   # In autoconf-2.13 it is called $ac_given_srcdir.
   # In autoconf-2.50 it is called $srcdir.
@@ -254,6 +256,7 @@ EOT
   fi
 
   # A sed script that extracts the value of VARIABLE from a Makefile.
+  tab=`printf '\t'`
   sed_x_variable='
 # Test if the hold space is empty.
 x
@@ -261,9 +264,9 @@ s/P/P/
 x
 ta
 # Yes it was empty. Look if we have the expected variable definition.
-/^[	 ]*VARIABLE[	 ]*=/{
+/^['"${tab}"' ]*VARIABLE['"${tab}"' ]*=/{
   # Seen the first line of the variable definition.
-  s/^[	 ]*VARIABLE[	 ]*=//
+  s/^['"${tab}"' ]*VARIABLE['"${tab}"' ]*=//
   ba
 }
 bd
@@ -315,7 +318,7 @@ changequote([,])dnl
     sed_x_LINGUAS=`$gt_echo "$sed_x_variable" | sed -e '/^ *#/d' -e 's/VARIABLE/LINGUAS/g'`
     ALL_LINGUAS_=`sed -n -e "$sed_x_LINGUAS" < "$ac_file"`
   fi
-  # Hide the ALL_LINGUAS assigment from automake < 1.5.
+  # Hide the ALL_LINGUAS assignment from automake < 1.5.
   eval 'ALL_LINGUAS''=$ALL_LINGUAS_'
   # Compute POFILES
   # as      $(foreach lang, $(ALL_LINGUAS), $(srcdir)/$(lang).po)
@@ -405,14 +408,15 @@ changequote([,])dnl
   fi
 
   sed -e "s|@POTFILES_DEPS@|$POTFILES_DEPS|g" -e "s|@POFILES@|$POFILES|g" -e "s|@UPDATEPOFILES@|$UPDATEPOFILES|g" -e "s|@DUMMYPOFILES@|$DUMMYPOFILES|g" -e "s|@GMOFILES@|$GMOFILES|g" -e "s|@PROPERTIESFILES@|$PROPERTIESFILES|g" -e "s|@CLASSFILES@|$CLASSFILES|g" -e "s|@QMFILES@|$QMFILES|g" -e "s|@MSGFILES@|$MSGFILES|g" -e "s|@RESOURCESDLLFILES@|$RESOURCESDLLFILES|g" -e "s|@CATALOGS@|$CATALOGS|g" -e "s|@JAVACATALOGS@|$JAVACATALOGS|g" -e "s|@QTCATALOGS@|$QTCATALOGS|g" -e "s|@TCLCATALOGS@|$TCLCATALOGS|g" -e "s|@CSHARPCATALOGS@|$CSHARPCATALOGS|g" -e 's,^#distdir:,distdir:,' < "$ac_file" > "$ac_file.tmp"
+  tab=`printf '\t'`
   if grep -l '@TCLCATALOGS@' "$ac_file" > /dev/null; then
     # Add dependencies that cannot be formulated as a simple suffix rule.
     for lang in $ALL_LINGUAS; do
       frobbedlang=`echo $lang | sed -e 's/\..*$//' -e 'y/ABCDEFGHIJKLMNOPQRSTUVWXYZ/abcdefghijklmnopqrstuvwxyz/'`
       cat >> "$ac_file.tmp" <<EOF
 $frobbedlang.msg: $lang.po
-	@echo "\$(MSGFMT) -c --tcl -d \$(srcdir) -l $lang $srcdirpre$lang.po"; \
-	\$(MSGFMT) -c --tcl -d "\$(srcdir)" -l $lang $srcdirpre$lang.po || { rm -f "\$(srcdir)/$frobbedlang.msg"; exit 1; }
+${tab}@echo "\$(MSGFMT) -c --tcl -d \$(srcdir) -l $lang $srcdirpre$lang.po"; \
+${tab}\$(MSGFMT) -c --tcl -d "\$(srcdir)" -l $lang $srcdirpre$lang.po || { rm -f "\$(srcdir)/$frobbedlang.msg"; exit 1; }
 EOF
     done
   fi
@@ -422,8 +426,8 @@ EOF
       frobbedlang=`echo $lang | sed -e 's/_/-/g' -e 's/^sr-CS/sr-SP/' -e 's/@latin$/-Latn/' -e 's/@cyrillic$/-Cyrl/' -e 's/^sr-SP$/sr-SP-Latn/' -e 's/^uz-UZ$/uz-UZ-Latn/'`
       cat >> "$ac_file.tmp" <<EOF
 $frobbedlang/\$(DOMAIN).resources.dll: $lang.po
-	@echo "\$(MSGFMT) -c --csharp -d \$(srcdir) -l $lang $srcdirpre$lang.po -r \$(DOMAIN)"; \
-	\$(MSGFMT) -c --csharp -d "\$(srcdir)" -l $lang $srcdirpre$lang.po -r "\$(DOMAIN)" || { rm -f "\$(srcdir)/$frobbedlang.msg"; exit 1; }
+${tab}@echo "\$(MSGFMT) -c --csharp -d \$(srcdir) -l $lang $srcdirpre$lang.po -r \$(DOMAIN)"; \
+${tab}\$(MSGFMT) -c --csharp -d "\$(srcdir)" -l $lang $srcdirpre$lang.po -r "\$(DOMAIN)" || { rm -f "\$(srcdir)/$frobbedlang.msg"; exit 1; }
 EOF
     done
   fi
diff --git a/m4/posix_spawn.m4 b/m4/posix_spawn.m4
index d50dcc9..59e56fc 100644
--- a/m4/posix_spawn.m4
+++ b/m4/posix_spawn.m4
@@ -1,5 +1,5 @@
-# posix_spawn.m4 serial 16
-dnl Copyright (C) 2008-2019 Free Software Foundation, Inc.
+# posix_spawn.m4 serial 19
+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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -42,43 +42,64 @@ AC_DEFUN([gl_POSIX_SPAWN_BODY],
          REPLACE_POSIX_SPAWN=1
        fi
       ])
+    m4_ifdef([gl_FUNC_POSIX_SPAWN_FILE_ACTIONS_ADDFCHDIR],
+      [dnl Module 'posix_spawn_file_actions_addfchdir' is present.
+       AC_CHECK_FUNCS_ONCE([posix_spawn_file_actions_addfchdir_np])
+       if test $ac_cv_func_posix_spawn_file_actions_addfchdir_np = no; then
+         dnl In order to implement the posix_spawn_file_actions_addfchdir
+         dnl function, we need to replace the entire posix_spawn facility.
+         REPLACE_POSIX_SPAWN=1
+       fi
+      ])
     if test $REPLACE_POSIX_SPAWN = 0; then
       gl_POSIX_SPAWN_WORKS
       case "$gl_cv_func_posix_spawn_works" in
-        *yes)
-          dnl Assume that these functions are available if POSIX_SPAWN_SETSCHEDULER
-          dnl evaluates to nonzero.
-          dnl AC_CHECK_FUNCS_ONCE([posix_spawnattr_getschedpolicy])
-          dnl AC_CHECK_FUNCS_ONCE([posix_spawnattr_setschedpolicy])
-          AC_CACHE_CHECK([whether posix_spawnattr_setschedpolicy is supported],
-            [gl_cv_func_spawnattr_setschedpolicy],
-            [AC_EGREP_CPP([POSIX scheduling supported], [
+        *yes) ;;
+        *) REPLACE_POSIX_SPAWN=1 ;;
+      esac
+    fi
+    if test $REPLACE_POSIX_SPAWN = 0; then
+      gl_POSIX_SPAWN_SECURE
+      case "$gl_cv_func_posix_spawn_secure_exec" in
+        *yes) ;;
+        *) REPLACE_POSIX_SPAWN=1 ;;
+      esac
+      case "$gl_cv_func_posix_spawnp_secure_exec" in
+        *yes) ;;
+        *) REPLACE_POSIX_SPAWN=1 ;;
+      esac
+    fi
+    if test $REPLACE_POSIX_SPAWN = 0; then
+      dnl Assume that these functions are available if POSIX_SPAWN_SETSCHEDULER
+      dnl evaluates to nonzero.
+      dnl AC_CHECK_FUNCS_ONCE([posix_spawnattr_getschedpolicy])
+      dnl AC_CHECK_FUNCS_ONCE([posix_spawnattr_setschedpolicy])
+      AC_CACHE_CHECK([whether posix_spawnattr_setschedpolicy is supported],
+        [gl_cv_func_spawnattr_setschedpolicy],
+        [AC_EGREP_CPP([POSIX scheduling supported], [
 #include <spawn.h>
 #if POSIX_SPAWN_SETSCHEDULER
  POSIX scheduling supported
 #endif
 ],
-               [gl_cv_func_spawnattr_setschedpolicy=yes],
-               [gl_cv_func_spawnattr_setschedpolicy=no])
-            ])
-          dnl Assume that these functions are available if POSIX_SPAWN_SETSCHEDPARAM
-          dnl evaluates to nonzero.
-          dnl AC_CHECK_FUNCS_ONCE([posix_spawnattr_getschedparam])
-          dnl AC_CHECK_FUNCS_ONCE([posix_spawnattr_setschedparam])
-          AC_CACHE_CHECK([whether posix_spawnattr_setschedparam is supported],
-            [gl_cv_func_spawnattr_setschedparam],
-            [AC_EGREP_CPP([POSIX scheduling supported], [
+           [gl_cv_func_spawnattr_setschedpolicy=yes],
+           [gl_cv_func_spawnattr_setschedpolicy=no])
+        ])
+      dnl Assume that these functions are available if POSIX_SPAWN_SETSCHEDPARAM
+      dnl evaluates to nonzero.
+      dnl AC_CHECK_FUNCS_ONCE([posix_spawnattr_getschedparam])
+      dnl AC_CHECK_FUNCS_ONCE([posix_spawnattr_setschedparam])
+      AC_CACHE_CHECK([whether posix_spawnattr_setschedparam is supported],
+        [gl_cv_func_spawnattr_setschedparam],
+        [AC_EGREP_CPP([POSIX scheduling supported], [
 #include <spawn.h>
 #if POSIX_SPAWN_SETSCHEDPARAM
  POSIX scheduling supported
 #endif
 ],
-               [gl_cv_func_spawnattr_setschedparam=yes],
-               [gl_cv_func_spawnattr_setschedparam=no])
-            ])
-          ;;
-        *) REPLACE_POSIX_SPAWN=1 ;;
-      esac
+           [gl_cv_func_spawnattr_setschedparam=yes],
+           [gl_cv_func_spawnattr_setschedparam=no])
+        ])
     fi
   fi
   if test $ac_cv_func_posix_spawn != yes || test $REPLACE_POSIX_SPAWN = 1; then
@@ -114,6 +135,7 @@ AC_DEFUN([gl_POSIX_SPAWN_WORKS],
 #include <unistd.h>
 #include <sys/types.h>
 #include <sys/wait.h>
+]GL_MDA_DEFINES[
 
 extern char **environ;
 
@@ -257,6 +279,7 @@ main ()
 #include <unistd.h>
 #include <sys/types.h>
 #include <sys/wait.h>
+]GL_MDA_DEFINES[
 
 extern char **environ;
 
@@ -406,6 +429,113 @@ main (int argc, char *argv[])
     ])
 ])
 
+dnl Test whether posix_spawn and posix_spawnp are secure.
+AC_DEFUN([gl_POSIX_SPAWN_SECURE],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  dnl On many platforms, posix_spawn or posix_spawnp allow executing a
+  dnl script without a '#!' marker as a shell script. This is unsecure.
+  AC_CACHE_CHECK([whether posix_spawn rejects scripts without shebang],
+    [gl_cv_func_posix_spawn_secure_exec],
+    [echo ':' > conftest.scr
+     chmod a+x conftest.scr
+     AC_RUN_IFELSE([AC_LANG_SOURCE([[
+       #include <errno.h>
+       #include <spawn.h>
+       #include <stddef.h>
+       #include <sys/types.h>
+       #include <sys/wait.h>
+       int
+       main ()
+       {
+         const char *prog_path = "./conftest.scr";
+         const char *prog_argv[2] = { prog_path, NULL };
+         const char *environment[2] = { "PATH=.", NULL };
+         pid_t child;
+         int status;
+         int err = posix_spawn (&child, prog_path, NULL, NULL,
+                                (char **) prog_argv, (char **) environment);
+         if (err == ENOEXEC)
+           return 0;
+         if (err != 0)
+           return 1;
+         status = 0;
+         while (waitpid (child, &status, 0) != child)
+           ;
+         if (!WIFEXITED (status))
+           return 2;
+         if (WEXITSTATUS (status) != 127)
+           return 3;
+         return 0;
+       }
+       ]])],
+       [gl_cv_func_posix_spawn_secure_exec=yes],
+       [gl_cv_func_posix_spawn_secure_exec=no],
+       [case "$host_os" in
+          # Guess no on GNU/Hurd.
+          gnu*)
+            gl_cv_func_posix_spawn_secure_exec="guessing no" ;;
+          # Guess yes on all other platforms.
+          *)
+            gl_cv_func_posix_spawn_secure_exec="guessing yes" ;;
+        esac
+       ])
+     rm -f conftest.scr
+    ])
+  AC_CACHE_CHECK([whether posix_spawnp rejects scripts without shebang],
+    [gl_cv_func_posix_spawnp_secure_exec],
+    [echo ':' > conftest.scr
+     chmod a+x conftest.scr
+     AC_RUN_IFELSE([AC_LANG_SOURCE([[
+       #include <errno.h>
+       #include <spawn.h>
+       #include <stddef.h>
+       #include <sys/types.h>
+       #include <sys/wait.h>
+       int
+       main ()
+       {
+         const char *prog_path = "./conftest.scr";
+         const char *prog_argv[2] = { prog_path, NULL };
+         const char *environment[2] = { "PATH=.", NULL };
+         pid_t child;
+         int status;
+         int err = posix_spawnp (&child, prog_path, NULL, NULL,
+                                 (char **) prog_argv, (char **) environment);
+         if (err == ENOEXEC)
+           return 0;
+         if (err != 0)
+           return 1;
+         status = 0;
+         while (waitpid (child, &status, 0) != child)
+           ;
+         if (!WIFEXITED (status))
+           return 2;
+         if (WEXITSTATUS (status) != 127)
+           return 3;
+         return 0;
+       }
+       ]])],
+       [gl_cv_func_posix_spawnp_secure_exec=yes],
+       [gl_cv_func_posix_spawnp_secure_exec=no],
+       [case "$host_os" in
+          # Guess yes on glibc systems (glibc >= 2.15 actually) except GNU/Hurd,
+          # musl libc, NetBSD.
+          *-gnu* | *-musl* | netbsd*)
+            gl_cv_func_posix_spawnp_secure_exec="guessing yes" ;;
+          # Guess no on GNU/Hurd, macOS, FreeBSD, OpenBSD, AIX, Solaris, Cygwin.
+          gnu* | darwin* | freebsd* | dragonfly* | openbsd* | aix* | solaris* | cygwin*)
+            gl_cv_func_posix_spawnp_secure_exec="guessing no" ;;
+          # If we don't know, obey --enable-cross-guesses.
+          *)
+            gl_cv_func_posix_spawnp_secure_exec="$gl_cross_guess_normal" ;;
+        esac
+       ])
+     rm -f conftest.scr
+    ])
+])
+
 # Prerequisites of lib/spawni.c.
 AC_DEFUN([gl_PREREQ_POSIX_SPAWN_INTERNAL],
 [
diff --git a/m4/posix_spawn_faction_addchdir.m4 b/m4/posix_spawn_faction_addchdir.m4
new file mode 100644
index 0000000..1ce7153
--- /dev/null
+++ b/m4/posix_spawn_faction_addchdir.m4
@@ -0,0 +1,20 @@
+# posix_spawn_faction_addchdir.m4 serial 1
+dnl Copyright (C) 2018-2020 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_FUNC_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR],
+[
+  AC_REQUIRE([gl_SPAWN_H_DEFAULTS])
+  AC_REQUIRE([AC_PROG_CC])
+  gl_POSIX_SPAWN
+  AC_CHECK_FUNCS_ONCE([posix_spawn_file_actions_addchdir posix_spawn_file_actions_addchdir_np])
+  if test $ac_cv_func_posix_spawn_file_actions_addchdir = yes; then
+    dnl This function is not yet standardized. Therefore override the
+    dnl system's implementation always.
+    REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR=1
+  else
+    HAVE_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR=0
+  fi
+])
diff --git a/m4/printf.m4 b/m4/printf.m4
index 6d2280e..95f7d9f 100644
--- a/m4/printf.m4
+++ b/m4/printf.m4
@@ -1,5 +1,5 @@
-# printf.m4 serial 61
-dnl Copyright (C) 2003, 2007-2019 Free Software Foundation, Inc.
+# printf.m4 serial 71
+dnl Copyright (C) 2003, 2007-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
@@ -93,8 +93,8 @@ changequote([,])dnl
                                    [gl_cv_func_printf_sizes_c99="guessing yes"],
                                    [gl_cv_func_printf_sizes_c99="guessing no"])
                                  ;;
-                                 # If we don't know, assume the worst.
-           *)                    gl_cv_func_printf_sizes_c99="guessing no";;
+                                 # If we don't know, obey --enable-cross-guesses.
+           *)                    gl_cv_func_printf_sizes_c99="$gl_cross_guess_normal";;
          esac
         ])
     ])
@@ -257,6 +257,9 @@ changequote(,)dnl
            netbsd[1-2]* | netbsdelf[1-2]* | netbsdaout[1-2]* | netbsdcoff[1-2]*)
                                  gl_cv_func_printf_infinite="guessing no";;
            netbsd*)              gl_cv_func_printf_infinite="guessing yes";;
+                                 # Guess yes on OpenBSD >= 6.0.
+           openbsd[1-5].*)       gl_cv_func_printf_infinite="guessing no";;
+           openbsd*)             gl_cv_func_printf_infinite="guessing yes";;
                                  # Guess yes on BeOS.
            beos*)                gl_cv_func_printf_infinite="guessing yes";;
                                  # Guess no on Android.
@@ -271,8 +274,8 @@ changequote([,])dnl
                                    [gl_cv_func_printf_infinite="guessing yes"],
                                    [gl_cv_func_printf_infinite="guessing no"])
                                  ;;
-                                 # If we don't know, assume the worst.
-           *)                    gl_cv_func_printf_infinite="guessing no";;
+                                 # If we don't know, obey --enable-cross-guesses.
+           *)                    gl_cv_func_printf_infinite="$gl_cross_guess_normal";;
          esac
         ])
     ])
@@ -469,6 +472,9 @@ changequote(,)dnl
                                          # Guess yes on HP-UX >= 11.
                    hpux[7-9]* | hpux10*) gl_cv_func_printf_infinite_long_double="guessing no";;
                    hpux*)                gl_cv_func_printf_infinite_long_double="guessing yes";;
+                                         # Guess yes on OpenBSD >= 6.0.
+                   openbsd[1-5].*)       gl_cv_func_printf_infinite_long_double="guessing no";;
+                   openbsd*)             gl_cv_func_printf_infinite_long_double="guessing yes";;
                                          # Guess no on Android.
                    linux*-android*)      gl_cv_func_printf_infinite_long_double="guessing no";;
 changequote([,])dnl
@@ -481,8 +487,8 @@ changequote([,])dnl
                                            [gl_cv_func_printf_infinite_long_double="guessing yes"],
                                            [gl_cv_func_printf_infinite_long_double="guessing no"])
                                          ;;
-                                         # If we don't know, assume the worst.
-                   *)                    gl_cv_func_printf_infinite_long_double="guessing no";;
+                                         # If we don't know, obey --enable-cross-guesses.
+                   *)                    gl_cv_func_printf_infinite_long_double="$gl_cross_guess_normal";;
                  esac
                  ;;
              esac
@@ -587,8 +593,8 @@ int main ()
            linux*-android*)      gl_cv_func_printf_directive_a="guessing no";;
                                  # Guess no on native Windows.
            mingw*)               gl_cv_func_printf_directive_a="guessing no";;
-                                 # If we don't know, assume the worst.
-           *)                    gl_cv_func_printf_directive_a="guessing no";;
+                                 # If we don't know, obey --enable-cross-guesses.
+           *)                    gl_cv_func_printf_directive_a="$gl_cross_guess_normal";;
          esac
         ])
     ])
@@ -641,6 +647,9 @@ changequote(,)dnl
                                  # Guess yes on Mac OS X >= 10.3.
            darwin[1-6].*)        gl_cv_func_printf_directive_f="guessing no";;
            darwin*)              gl_cv_func_printf_directive_f="guessing yes";;
+                                 # Guess yes on OpenBSD >= 6.0.
+           openbsd[1-5].*)       gl_cv_func_printf_directive_f="guessing no";;
+           openbsd*)             gl_cv_func_printf_directive_f="guessing yes";;
                                  # Guess yes on Solaris >= 2.10.
            solaris2.[1-9][0-9]*) gl_cv_func_printf_directive_f="guessing yes";;
            solaris*)             gl_cv_func_printf_directive_f="guessing no";;
@@ -656,8 +665,8 @@ changequote([,])dnl
                                    [gl_cv_func_printf_directive_f="guessing yes"],
                                    [gl_cv_func_printf_directive_f="guessing no"])
                                  ;;
-                                 # If we don't know, assume the worst.
-           *)                    gl_cv_func_printf_directive_f="guessing no";;
+                                 # If we don't know, obey --enable-cross-guesses.
+           *)                    gl_cv_func_printf_directive_f="$gl_cross_guess_normal";;
          esac
         ])
     ])
@@ -680,7 +689,10 @@ AC_DEFUN([gl_PRINTF_DIRECTIVE_N],
 #include <stdlib.h>
 #include <string.h>
 #ifdef _MSC_VER
-/* See page about "Parameter Validation" on msdn.microsoft.com.  */
+#include <inttypes.h>
+/* See page about "Parameter Validation" on msdn.microsoft.com.
+   <https://docs.microsoft.com/en-us/cpp/c-runtime-library/parameter-validation>
+   <https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/set-invalid-parameter-handler-set-thread-local-invalid-parameter-handler>  */
 static void cdecl
 invalid_parameter_handler (const wchar_t *expression,
                            const wchar_t *function,
@@ -711,6 +723,16 @@ int main ()
         [gl_cv_func_printf_directive_n=yes],
         [gl_cv_func_printf_directive_n=no],
         [case "$host_os" in
+                            # Guess no on glibc when _FORTIFY_SOURCE >= 2.
+           *-gnu* | gnu*)   AC_COMPILE_IFELSE(
+                              [AC_LANG_SOURCE(
+                                 [[#if _FORTIFY_SOURCE >= 2
+                                    error fail
+                                   #endif
+                                 ]])],
+                              [gl_cv_func_printf_directive_n="guessing yes"],
+                              [gl_cv_func_printf_directive_n="guessing no"])
+                            ;;
                             # Guess no on Android.
            linux*-android*) gl_cv_func_printf_directive_n="guessing no";;
                             # Guess no on native Windows.
@@ -737,13 +759,7 @@ AC_DEFUN([gl_PRINTF_DIRECTIVE_LS],
     [
       AC_RUN_IFELSE(
         [AC_LANG_SOURCE([[
-/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
-   <wchar.h>.
-   BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be
-   included before <wchar.h>.  */
-#include <stddef.h>
 #include <stdio.h>
-#include <time.h>
 #include <wchar.h>
 #include <string.h>
 int main ()
@@ -791,7 +807,9 @@ int main ()
         [
 changequote(,)dnl
          case "$host_os" in
-           openbsd*)        gl_cv_func_printf_directive_ls="guessing no";;
+                            # Guess yes on OpenBSD >= 6.0.
+           openbsd[1-5].*)  gl_cv_func_printf_directive_ls="guessing no";;
+           openbsd*)        gl_cv_func_printf_directive_ls="guessing yes";;
            irix*)           gl_cv_func_printf_directive_ls="guessing no";;
            solaris*)        gl_cv_func_printf_directive_ls="guessing no";;
            cygwin*)         gl_cv_func_printf_directive_ls="guessing no";;
@@ -978,8 +996,8 @@ changequote(,)dnl
            linux*-android*) gl_cv_func_printf_flag_zero="guessing no";;
                             # Guess no on native Windows.
            mingw*)          gl_cv_func_printf_flag_zero="guessing no";;
-                            # If we don't know, assume the worst.
-           *)               gl_cv_func_printf_flag_zero="guessing no";;
+                            # If we don't know, obey --enable-cross-guesses.
+           *)               gl_cv_func_printf_flag_zero="$gl_cross_guess_normal";;
          esac
 changequote([,])dnl
         ])
@@ -1059,9 +1077,8 @@ AC_DEFUN([gl_PRINTF_ENOMEM],
       gl_cv_func_printf_enomem="guessing no"
       if test "$cross_compiling" = no; then
         if test $APPLE_UNIVERSAL_BUILD = 0; then
-          AC_LANG_CONFTEST([AC_LANG_SOURCE([
+          AC_LANG_CONFTEST([AC_LANG_SOURCE([[
 ]GL_NOCRASH[
-changequote(,)dnl
 #include <stdio.h>
 #include <sys/types.h>
 #include <sys/time.h>
@@ -1106,8 +1123,7 @@ int main()
   ret = printf ("%.5000000f", 1.0);
   return !(ret == 5000002 || (ret < 0 && errno == ENOMEM));
 }
-changequote([,])dnl
-          ])])
+          ]])])
           if AC_TRY_EVAL([ac_link]) && test -s conftest$ac_exeext; then
             (./conftest 2>&AS_MESSAGE_LOG_FD
              result=$?
@@ -1156,8 +1172,8 @@ changequote(,)dnl
           haiku*)          gl_cv_func_printf_enomem="guessing yes";;
                            # Guess no on Android.
           linux*-android*) gl_cv_func_printf_enomem="guessing no";;
-                           # If we don't know, assume the worst.
-          *)               gl_cv_func_printf_enomem="guessing no";;
+                           # If we don't know, obey --enable-cross-guesses.
+          *)               gl_cv_func_printf_enomem="$gl_cross_guess_normal";;
         esac
 changequote([,])dnl
       fi
@@ -1176,7 +1192,7 @@ dnl Test whether the string produced by the snprintf function is always NUL
 dnl terminated. (ISO C99, POSIX:2001)
 dnl Result is gl_cv_func_snprintf_truncation_c99.
 
-AC_DEFUN([gl_SNPRINTF_TRUNCATION_C99],
+AC_DEFUN_ONCE([gl_SNPRINTF_TRUNCATION_C99],
 [
   AC_REQUIRE([AC_PROG_CC])
   AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
@@ -1255,8 +1271,8 @@ changequote(,)dnl
            linux*-android*)      gl_cv_func_snprintf_truncation_c99="guessing yes";;
                                  # Guess no on native Windows.
            mingw*)               gl_cv_func_snprintf_truncation_c99="guessing no";;
-                                 # If we don't know, assume the worst.
-           *)                    gl_cv_func_snprintf_truncation_c99="guessing no";;
+                                 # If we don't know, obey --enable-cross-guesses.
+           *)                    gl_cv_func_snprintf_truncation_c99="$gl_cross_guess_normal";;
          esac
 changequote([,])dnl
         ])
@@ -1358,8 +1374,8 @@ changequote([,])dnl
                                    [gl_cv_func_snprintf_retval_c99="guessing yes"],
                                    [gl_cv_func_snprintf_retval_c99="guessing no"])
                                  ;;
-                                 # If we don't know, assume the worst.
-           *)                    gl_cv_func_snprintf_retval_c99="guessing no";;
+                                 # If we don't know, obey --enable-cross-guesses.
+           *)                    gl_cv_func_snprintf_retval_c99="$gl_cross_guess_normal";;
          esac
         ])
     ])
@@ -1412,10 +1428,18 @@ int main ()
         [gl_cv_func_snprintf_directive_n=yes],
         [gl_cv_func_snprintf_directive_n=no],
         [
-changequote(,)dnl
          case "$host_os" in
-                                 # Guess yes on glibc systems.
-           *-gnu* | gnu*)        gl_cv_func_snprintf_directive_n="guessing yes";;
+                                 # Guess no on glibc when _FORTIFY_SOURCE >= 2.
+           *-gnu* | gnu*)        AC_COMPILE_IFELSE(
+                                   [AC_LANG_SOURCE(
+                                      [[#if _FORTIFY_SOURCE >= 2
+                                         error fail
+                                        #endif
+                                      ]])],
+                                   [gl_cv_func_snprintf_directive_n="guessing yes"],
+                                   [gl_cv_func_snprintf_directive_n="guessing no"])
+                                 ;;
+changequote(,)dnl
                                  # Guess yes on musl systems.
            *-musl*)              gl_cv_func_snprintf_directive_n="guessing yes";;
                                  # Guess yes on FreeBSD >= 5.
@@ -1446,10 +1470,10 @@ changequote(,)dnl
            linux*-android*)      gl_cv_func_snprintf_directive_n="guessing no";;
                                  # Guess no on native Windows.
            mingw*)               gl_cv_func_snprintf_directive_n="guessing no";;
-                                 # If we don't know, assume the worst.
-           *)                    gl_cv_func_snprintf_directive_n="guessing no";;
-         esac
+                                 # If we don't know, obey --enable-cross-guesses.
+           *)                    gl_cv_func_snprintf_directive_n="$gl_cross_guess_normal";;
 changequote([,])dnl
+         esac
         ])
     ])
 ])
@@ -1601,8 +1625,8 @@ changequote(,)dnl
            linux*-android*)      gl_cv_func_vsnprintf_zerosize_c99="guessing yes";;
                                  # Guess yes on native Windows.
            mingw* | pw*)         gl_cv_func_vsnprintf_zerosize_c99="guessing yes";;
-                                 # If we don't know, assume the worst.
-           *)                    gl_cv_func_vsnprintf_zerosize_c99="guessing no";;
+                                 # If we don't know, obey --enable-cross-guesses.
+           *)                    gl_cv_func_vsnprintf_zerosize_c99="$gl_cross_guess_normal";;
          esac
 changequote([,])dnl
         ])
@@ -1659,8 +1683,10 @@ dnl                                  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15
 dnl   glibc 2.5                      .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
 dnl   glibc 2.3.6                    .  .  .  .  #  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
 dnl   FreeBSD 5.4, 6.1               .  .  .  .  #  .  .  .  .  .  .  #  .  #  .  .  .  .  .  .
+dnl   Mac OS X 10.13.5               .  .  .  #  #  .  #  .  .  .  .  .  .  .  .  .  .  #  .  .
 dnl   Mac OS X 10.5.8                .  .  .  #  #  .  .  .  .  .  .  #  .  .  .  .  .  .  .  .
 dnl   Mac OS X 10.3.9                .  .  .  .  #  .  .  .  .  .  .  #  .  #  .  .  .  .  .  .
+dnl   OpenBSD 6.0, 6.7               .  .  .  .  #  .  .  .  .  .  .  .  .  #  .  .  .  .  .  .
 dnl   OpenBSD 3.9, 4.0               .  .  #  #  #  #  .  #  .  #  .  #  .  #  .  .  .  .  .  .
 dnl   Cygwin 1.7.0 (2009)            .  .  .  #  .  .  .  ?  .  .  .  .  .  ?  .  .  .  .  .  .
 dnl   Cygwin 1.5.25 (2008)           .  .  .  #  #  .  .  #  .  .  .  .  .  #  .  .  .  .  .  .
@@ -1680,6 +1706,7 @@ dnl   HP-UX 10.20                    #  .  #  .  #  #  .  ?  .  .  #  #  .  .  .
 dnl   IRIX 6.5                       #  .  #  #  #  #  .  #  .  .  .  #  .  .  .  .  #  .  .  .
 dnl   OSF/1 5.1                      #  .  #  #  #  #  .  .  .  .  .  #  .  .  .  .  #  .  .  #
 dnl   OSF/1 4.0d                     #  .  #  #  #  #  .  .  .  .  .  #  .  .  #  #  #  #  #  #
+dnl   NetBSD 9.0                     .  .  .  .  #  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
 dnl   NetBSD 5.0                     .  .  .  #  #  .  .  .  .  .  .  #  .  #  .  .  .  .  .  .
 dnl   NetBSD 4.0                     .  ?  ?  ?  ?  ?  .  ?  .  ?  ?  ?  ?  ?  .  .  .  ?  ?  ?
 dnl   NetBSD 3.0                     .  .  .  .  #  #  .  ?  #  #  ?  #  .  #  .  .  .  .  .  .
diff --git a/m4/pthread_rwlock_rdlock.m4 b/m4/pthread_rwlock_rdlock.m4
index 3c1d645..049af50 100644
--- a/m4/pthread_rwlock_rdlock.m4
+++ b/m4/pthread_rwlock_rdlock.m4
@@ -1,5 +1,5 @@
-# pthread_rwlock_rdlock.m4 serial 2
-dnl Copyright (C) 2017-2019 Free Software Foundation, Inc.
+# pthread_rwlock_rdlock.m4 serial 4
+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.
@@ -26,14 +26,16 @@ dnl
 dnl POSIX:2017 makes this requirement only for implementations that support TPS
 dnl (Thread Priority Scheduling) and only for the scheduling policies SCHED_FIFO
 dnl and SCHED_RR, see
-dnl http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_rwlock_rdlock.html
+dnl https://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_rwlock_rdlock.html
 dnl but this test verifies the guarantee regardless of TPS and regardless of
 dnl scheduling policy.
-dnl Glibc currently does not provide this guarantee, see
+dnl Glibc does not provide this guarantee (and never will on Linux), see
 dnl https://sourceware.org/bugzilla/show_bug.cgi?id=13701
+dnl https://bugzilla.redhat.com/show_bug.cgi?id=1410052
 AC_DEFUN([gl_PTHREAD_RWLOCK_RDLOCK_PREFER_WRITER],
 [
   AC_REQUIRE([gl_THREADLIB_EARLY])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
   AC_CACHE_CHECK([whether pthread_rwlock_rdlock prefers a writer to a reader],
     [gl_cv_pthread_rwlock_rdlock_prefer_writer],
     [save_LIBS="$LIBS"
@@ -153,7 +155,25 @@ main ()
 ]])],
        [gl_cv_pthread_rwlock_rdlock_prefer_writer=yes],
        [gl_cv_pthread_rwlock_rdlock_prefer_writer=no],
-       [gl_cv_pthread_rwlock_rdlock_prefer_writer="guessing yes"])
+       [case "$host_os" in
+                         # Guess no on glibc systems.
+          *-gnu* | gnu*) gl_cv_pthread_rwlock_rdlock_prefer_writer="guessing no" ;;
+                         # Guess no on musl systems.
+          *-musl*)       gl_cv_pthread_rwlock_rdlock_prefer_writer="guessing no" ;;
+                         # Guess no on bionic systems.
+          *-android*)    gl_cv_pthread_rwlock_rdlock_prefer_writer="guessing no" ;;
+                         # Guess yes on native Windows with the mingw-w64 winpthreads library.
+                         # Guess no on native Windows with the gnulib windows-rwlock module.
+          mingw*)        if test "$gl_use_threads" = yes || test "$gl_use_threads" = posix; then
+                           gl_cv_pthread_rwlock_rdlock_prefer_writer="guessing yes"
+                         else
+                           gl_cv_pthread_rwlock_rdlock_prefer_writer="guessing no"
+                         fi
+                         ;;
+                         # If we don't know, obey --enable-cross-guesses.
+          *)             gl_cv_pthread_rwlock_rdlock_prefer_writer="$gl_cross_guess_normal" ;;
+         esac
+       ])
      LIBS="$save_LIBS"
     ])
   case "$gl_cv_pthread_rwlock_rdlock_prefer_writer" in
diff --git a/m4/quote.m4 b/m4/quote.m4
index feaa735..9efab95 100644
--- a/m4/quote.m4
+++ b/m4/quote.m4
@@ -1,5 +1,5 @@
 # quote.m4 serial 6
-dnl Copyright (C) 2002-2003, 2005-2006, 2009-2019 Free Software Foundation,
+dnl Copyright (C) 2002-2003, 2005-2006, 2009-2020 Free Software Foundation,
 dnl Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
diff --git a/m4/quotearg.m4 b/m4/quotearg.m4
index c478f50..4038711 100644
--- a/m4/quotearg.m4
+++ b/m4/quotearg.m4
@@ -1,10 +1,11 @@
-# quotearg.m4 serial 9
-dnl Copyright (C) 2002, 2004-2019 Free Software Foundation, Inc.
+# quotearg.m4 serial 10
+dnl Copyright (C) 2002, 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,
 dnl with or without modifications, as long as this notice is preserved.
 
 AC_DEFUN([gl_QUOTEARG],
 [
+  AC_REQUIRE([AC_C_RESTRICT])
   :
 ])
diff --git a/m4/raise.m4 b/m4/raise.m4
index f7661e6..5b61b65 100644
--- a/m4/raise.m4
+++ b/m4/raise.m4
@@ -1,5 +1,5 @@
 # raise.m4 serial 4
-dnl Copyright (C) 2011-2019 Free Software Foundation, Inc.
+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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/rawmemchr.m4 b/m4/rawmemchr.m4
index 03a8804..c5bf041 100644
--- a/m4/rawmemchr.m4
+++ b/m4/rawmemchr.m4
@@ -1,5 +1,5 @@
 # rawmemchr.m4 serial 2
-dnl Copyright (C) 2003, 2007-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2003, 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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/readdir.m4 b/m4/readdir.m4
new file mode 100644
index 0000000..ca4e741
--- /dev/null
+++ b/m4/readdir.m4
@@ -0,0 +1,15 @@
+# readdir.m4 serial 1
+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,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_FUNC_READDIR],
+[
+  AC_REQUIRE([gl_DIRENT_H_DEFAULTS])
+
+  AC_CHECK_FUNCS([readdir])
+  if test $ac_cv_func_readdir = no; then
+    HAVE_READDIR=0
+  fi
+])
diff --git a/m4/readlink.m4 b/m4/readlink.m4
new file mode 100644
index 0000000..c7f436a
--- /dev/null
+++ b/m4/readlink.m4
@@ -0,0 +1,114 @@
+# readlink.m4 serial 16
+dnl Copyright (C) 2003, 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,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_FUNC_READLINK],
+[
+  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CHECK_FUNCS_ONCE([readlink])
+  if test $ac_cv_func_readlink = no; then
+    HAVE_READLINK=0
+  else
+    AC_CACHE_CHECK([whether readlink signature is correct],
+      [gl_cv_decl_readlink_works],
+      [AC_COMPILE_IFELSE(
+         [AC_LANG_PROGRAM(
+           [[#include <unistd.h>
+      /* Cause compilation failure if original declaration has wrong type.  */
+      ssize_t readlink (const char *, char *, size_t);]])],
+         [gl_cv_decl_readlink_works=yes], [gl_cv_decl_readlink_works=no])])
+    dnl Solaris 9 ignores trailing slash.
+    dnl FreeBSD 7.2 dereferences only one level of links with trailing slash.
+    AC_CACHE_CHECK([whether readlink handles trailing slash correctly],
+      [gl_cv_func_readlink_trailing_slash],
+      [# We have readlink, so assume ln -s works.
+       ln -s conftest.no-such conftest.link
+       ln -s conftest.link conftest.lnk2
+       AC_RUN_IFELSE(
+         [AC_LANG_PROGRAM(
+           [[#include <unistd.h>
+]], [[char buf[20];
+      return readlink ("conftest.lnk2/", buf, sizeof buf) != -1;]])],
+         [gl_cv_func_readlink_trailing_slash=yes],
+         [gl_cv_func_readlink_trailing_slash=no],
+         [case "$host_os" in
+            # Guess yes on Linux or glibc systems.
+            linux-* | linux | *-gnu* | gnu*)
+              gl_cv_func_readlink_trailing_slash="guessing yes" ;;
+            # Guess no on AIX or HP-UX.
+            aix* | hpux*)
+              gl_cv_func_readlink_trailing_slash="guessing no" ;;
+            # If we don't know, obey --enable-cross-guesses.
+            *)
+              gl_cv_func_readlink_trailing_slash="$gl_cross_guess_normal" ;;
+          esac
+         ])
+      rm -f conftest.link conftest.lnk2])
+    case "$gl_cv_func_readlink_trailing_slash" in
+      *yes)
+        if test "$gl_cv_decl_readlink_works" != yes; then
+          REPLACE_READLINK=1
+        fi
+        ;;
+      *)
+        AC_DEFINE([READLINK_TRAILING_SLASH_BUG], [1], [Define to 1 if readlink
+          fails to recognize a trailing slash.])
+        REPLACE_READLINK=1
+        ;;
+    esac
+
+    AC_CACHE_CHECK([whether readlink truncates results correctly],
+      [gl_cv_func_readlink_truncate],
+      [# We have readlink, so assume ln -s works.
+       ln -s ab conftest.link
+       AC_RUN_IFELSE(
+         [AC_LANG_PROGRAM(
+           [[#include <unistd.h>
+]], [[char c;
+      return readlink ("conftest.link", &c, 1) != 1;]])],
+         [gl_cv_func_readlink_truncate=yes],
+         [gl_cv_func_readlink_truncate=no],
+         [case "$host_os" in
+            # Guess yes on Linux or glibc systems.
+            linux-* | linux | *-gnu* | gnu*)
+              gl_cv_func_readlink_truncate="guessing yes" ;;
+            # Guess no on AIX or HP-UX.
+            aix* | hpux*)
+              gl_cv_func_readlink_truncate="guessing no" ;;
+            # If we don't know, obey --enable-cross-guesses.
+            *)
+              gl_cv_func_readlink_truncate="$gl_cross_guess_normal" ;;
+          esac
+         ])
+      rm -f conftest.link conftest.lnk2])
+    case $gl_cv_func_readlink_truncate in
+      *yes)
+        if test "$gl_cv_decl_readlink_works" != yes; then
+          REPLACE_READLINK=1
+        fi
+        ;;
+      *)
+        AC_DEFINE([READLINK_TRUNCATE_BUG], [1], [Define to 1 if readlink
+          sets errno instead of truncating a too-long link.])
+        REPLACE_READLINK=1
+        ;;
+    esac
+  fi
+])
+
+# Like gl_FUNC_READLINK, except prepare for separate compilation
+# (no REPLACE_READLINK, no AC_LIBOBJ).
+AC_DEFUN([gl_FUNC_READLINK_SEPARATE],
+[
+  AC_CHECK_FUNCS_ONCE([readlink])
+  gl_PREREQ_READLINK
+])
+
+# Prerequisites of lib/readlink.c.
+AC_DEFUN([gl_PREREQ_READLINK],
+[
+  :
+])
diff --git a/m4/realloc.m4 b/m4/realloc.m4
new file mode 100644
index 0000000..53967f4
--- /dev/null
+++ b/m4/realloc.m4
@@ -0,0 +1,76 @@
+# realloc.m4 serial 19
+dnl Copyright (C) 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,
+dnl with or without modifications, as long as this notice is preserved.
+
+# This is adapted with modifications from upstream Autoconf here:
+# https://git.savannah.gnu.org/cgit/autoconf.git/commit/?id=04be2b7a29d65d9a08e64e8e56e594c91749598c
+AC_DEFUN([_AC_FUNC_REALLOC_IF],
+[
+  AC_REQUIRE([AC_CANONICAL_HOST])dnl for cross-compiles
+  AC_CACHE_CHECK([for GNU libc compatible realloc],
+    [ac_cv_func_realloc_0_nonnull],
+    [AC_RUN_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[#include <stdlib.h>
+          ]],
+          [[char *p = realloc (0, 0);
+            int result = !p;
+            free (p);
+            return result;]])
+       ],
+       [ac_cv_func_realloc_0_nonnull=yes],
+       [ac_cv_func_realloc_0_nonnull=no],
+       [case "$host_os" in
+          # Guess yes on platforms where we know the result.
+          *-gnu* | gnu* | *-musl* | freebsd* | netbsd* | openbsd* \
+          | hpux* | solaris* | cygwin* | mingw*)
+            ac_cv_func_realloc_0_nonnull="guessing yes" ;;
+          # If we don't know, obey --enable-cross-guesses.
+          *) ac_cv_func_realloc_0_nonnull="$gl_cross_guess_normal" ;;
+        esac
+       ])
+    ])
+  case "$ac_cv_func_realloc_0_nonnull" in
+    *yes)
+      $1
+      ;;
+    *)
+      $2
+      ;;
+  esac
+])# AC_FUNC_REALLOC
+
+# gl_FUNC_REALLOC_GNU
+# -------------------
+# Test whether 'realloc (0, 0)' is handled like in GNU libc, and replace
+# realloc if it is not.
+AC_DEFUN([gl_FUNC_REALLOC_GNU],
+[
+  AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
+  dnl _AC_FUNC_REALLOC_IF is defined in Autoconf.
+  _AC_FUNC_REALLOC_IF(
+    [AC_DEFINE([HAVE_REALLOC_GNU], [1],
+               [Define to 1 if your system has a GNU libc compatible 'realloc'
+                function, and to 0 otherwise.])],
+    [AC_DEFINE([HAVE_REALLOC_GNU], [0])
+     REPLACE_REALLOC=1
+    ])
+])# gl_FUNC_REALLOC_GNU
+
+# gl_FUNC_REALLOC_POSIX
+# ---------------------
+# Test whether 'realloc' is POSIX compliant (sets errno to ENOMEM when it
+# fails), and replace realloc if it is not.
+AC_DEFUN([gl_FUNC_REALLOC_POSIX],
+[
+  AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
+  AC_REQUIRE([gl_CHECK_MALLOC_POSIX])
+  if test $gl_cv_func_malloc_posix = yes; then
+    AC_DEFINE([HAVE_REALLOC_POSIX], [1],
+      [Define if the 'realloc' function is POSIX compliant.])
+  else
+    REPLACE_REALLOC=1
+  fi
+])
diff --git a/m4/regex.m4 b/m4/regex.m4
index 35119c5..effe100 100644
--- a/m4/regex.m4
+++ b/m4/regex.m4
@@ -1,6 +1,6 @@
-# serial 68
+# serial 71
 
-# Copyright (C) 1996-2001, 2003-2019 Free Software Foundation, Inc.
+# Copyright (C) 1996-2001, 2003-2020 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -90,11 +90,14 @@ AC_DEFUN([gl_REGEX],
                   s = re_compile_pattern (pat, sizeof pat - 1, &regex);
                   if (s)
                     result |= 1;
-                  else if (re_search (&regex, data, sizeof data - 1,
-                                      0, sizeof data - 1, &regs)
-                           != -1)
-                    result |= 1;
-                  regfree (&regex);
+                  else
+                    {
+                      if (re_search (&regex, data, sizeof data - 1,
+                                     0, sizeof data - 1, &regs)
+                          != -1)
+                        result |= 1;
+                      regfree (&regex);
+                    }
                 }
 
                 {
@@ -125,8 +128,8 @@ AC_DEFUN([gl_REGEX],
                                      0, sizeof data - 1, 0);
                       if (i != 0 && i != 21)
                         result |= 1;
+                      regfree (&regex);
                     }
-                  regfree (&regex);
                 }
 
                 if (! setlocale (LC_ALL, "C"))
@@ -139,9 +142,13 @@ AC_DEFUN([gl_REGEX],
             s = re_compile_pattern ("a[^x]b", 6, &regex);
             if (s)
               result |= 2;
-            /* This should fail, but succeeds for glibc-2.5.  */
-            else if (re_search (&regex, "a\nb", 3, 0, 3, &regs) != -1)
-              result |= 2;
+            else
+              {
+                /* This should fail, but succeeds for glibc-2.5.  */
+                if (re_search (&regex, "a\nb", 3, 0, 3, &regs) != -1)
+                  result |= 2;
+                regfree (&regex);
+              }
 
             /* This regular expression is from Spencer ere test number 75
                in grep-2.3.  */
@@ -153,7 +160,10 @@ AC_DEFUN([gl_REGEX],
             s = re_compile_pattern ("a[[:@:>@:]]b\n", 11, &regex);
             /* This should fail with _Invalid character class name_ error.  */
             if (!s)
-              result |= 4;
+              {
+                result |= 4;
+                regfree (&regex);
+              }
 
             /* Ensure that [b-a] is diagnosed as invalid, when
                using RE_NO_EMPTY_RANGES. */
@@ -161,13 +171,18 @@ AC_DEFUN([gl_REGEX],
             memset (&regex, 0, sizeof regex);
             s = re_compile_pattern ("a[b-a]", 6, &regex);
             if (s == 0)
-              result |= 8;
+              {
+                result |= 8;
+                regfree (&regex);
+              }
 
             /* This should succeed, but does not for glibc-2.1.3.  */
             memset (&regex, 0, sizeof regex);
             s = re_compile_pattern ("{1", 2, &regex);
             if (s)
               result |= 8;
+            else
+              regfree (&regex);
 
             /* The following example is derived from a problem report
                against gawk from Jorge Stolfi <stolfi@ic.unicamp.br>.  */
@@ -175,17 +190,35 @@ AC_DEFUN([gl_REGEX],
             s = re_compile_pattern ("[an\371]*n", 7, &regex);
             if (s)
               result |= 8;
-            /* This should match, but does not for glibc-2.2.1.  */
-            else if (re_match (&regex, "an", 2, 0, &regs) != 2)
-              result |= 8;
+            else
+              {
+                /* This should match, but does not for glibc-2.2.1.  */
+                if (re_match (&regex, "an", 2, 0, &regs) != 2)
+                  result |= 8;
+                else
+                  {
+                    free (regs.start);
+                    free (regs.end);
+                  }
+                regfree (&regex);
+              }
 
             memset (&regex, 0, sizeof regex);
             s = re_compile_pattern ("x", 1, &regex);
             if (s)
               result |= 8;
-            /* glibc-2.2.93 does not work with a negative RANGE argument.  */
-            else if (re_search (&regex, "wxy", 3, 2, -2, &regs) != 1)
-              result |= 8;
+            else
+              {
+                /* glibc-2.2.93 does not work with a negative RANGE argument.  */
+                if (re_search (&regex, "wxy", 3, 2, -2, &regs) != 1)
+                  result |= 8;
+                else
+                  {
+                    free (regs.start);
+                    free (regs.end);
+                  }
+                regfree (&regex);
+              }
 
             /* The version of regex.c in older versions of gnulib
                ignored RE_ICASE.  Detect that problem too.  */
@@ -194,8 +227,17 @@ AC_DEFUN([gl_REGEX],
             s = re_compile_pattern ("x", 1, &regex);
             if (s)
               result |= 16;
-            else if (re_search (&regex, "WXY", 3, 0, 3, &regs) < 0)
-              result |= 16;
+            else
+              {
+                if (re_search (&regex, "WXY", 3, 0, 3, &regs) < 0)
+                  result |= 16;
+                else
+                  {
+                    free (regs.start);
+                    free (regs.end);
+                  }
+                regfree (&regex);
+              }
 
             /* Catch a bug reported by Vin Shelton in
                https://lists.gnu.org/r/bug-coreutils/2007-06/msg00089.html
@@ -207,6 +249,8 @@ AC_DEFUN([gl_REGEX],
             s = re_compile_pattern ("[[:alnum:]_-]\\\\+$", 16, &regex);
             if (s)
               result |= 32;
+            else
+              regfree (&regex);
 
             /* REG_STARTEND was added to glibc on 2004-01-15.
                Reject older versions.  */
@@ -221,8 +265,14 @@ AC_DEFUN([gl_REGEX],
             re_set_syntax (RE_SYNTAX_POSIX_EGREP);
             memset (&regex, 0, sizeof regex);
             s = re_compile_pattern ("0|()0|\\1|0", 10, &regex);
-            if (!s || strcmp (s, "Invalid back reference"))
+            if (!s)
               result |= 64;
+            else
+              {
+                if (strcmp (s, "Invalid back reference"))
+                  result |= 64;
+                regfree (&regex);
+              }
 
 #if 0
             /* It would be nice to reject hosts whose regoff_t values are too
@@ -243,8 +293,8 @@ AC_DEFUN([gl_REGEX],
         [case "$host_os" in
                    # Guess no on native Windows.
            mingw*) gl_cv_func_re_compile_pattern_working="guessing no" ;;
-                   # Otherwise, assume it is not working.
-           *)      gl_cv_func_re_compile_pattern_working="guessing no" ;;
+                   # Otherwise obey --enable-cross-guesses.
+           *)      gl_cv_func_re_compile_pattern_working="$gl_cross_guess_normal" ;;
          esac
         ])
       ])
@@ -304,7 +354,6 @@ AC_DEFUN([gl_PREREQ_REGEX],
   AC_REQUIRE([AC_C_RESTRICT])
   AC_REQUIRE([AC_TYPE_MBSTATE_T])
   AC_REQUIRE([gl_EEMALLOC])
-  AC_REQUIRE([gl_GLIBC21])
   AC_CHECK_HEADERS([libintl.h])
   AC_CHECK_FUNCS_ONCE([isblank iswctype])
   AC_CHECK_DECLS([isblank], [], [], [[#include <ctype.h>]])
diff --git a/m4/rewinddir.m4 b/m4/rewinddir.m4
new file mode 100644
index 0000000..51f476b
--- /dev/null
+++ b/m4/rewinddir.m4
@@ -0,0 +1,15 @@
+# rewinddir.m4 serial 1
+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,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_FUNC_REWINDDIR],
+[
+  AC_REQUIRE([gl_DIRENT_H_DEFAULTS])
+
+  AC_CHECK_FUNCS([rewinddir])
+  if test $ac_cv_func_rewinddir = no; then
+    HAVE_REWINDDIR=0
+  fi
+])
diff --git a/m4/save-cwd.m4 b/m4/save-cwd.m4
new file mode 100644
index 0000000..a401b1f
--- /dev/null
+++ b/m4/save-cwd.m4
@@ -0,0 +1,11 @@
+# serial 10
+dnl Copyright (C) 2002-2006, 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 Prerequisites for lib/save-cwd.c.
+AC_DEFUN([gl_SAVE_CWD],
+[
+  AC_CHECK_FUNCS_ONCE([fchdir])
+])
diff --git a/m4/sched_h.m4 b/m4/sched_h.m4
index c7a1d97..af0c43d 100644
--- a/m4/sched_h.m4
+++ b/m4/sched_h.m4
@@ -1,5 +1,5 @@
-# sched_h.m4 serial 11
-dnl Copyright (C) 2008-2019 Free Software Foundation, Inc.
+# sched_h.m4 serial 12
+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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -8,68 +8,84 @@ dnl Written by Bruno Haible.
 
 AC_DEFUN([gl_SCHED_H],
 [
+  dnl Use AC_REQUIRE here, so that the default behavior below is expanded
+  dnl once only, before all statements that occur in other macros.
+  AC_REQUIRE([gl_SCHED_H_DEFAULTS])
+
   AC_REQUIRE([AC_CANONICAL_HOST])
+
   AC_CHECK_HEADERS_ONCE([sys/cdefs.h])
-  AC_COMPILE_IFELSE(
-    [AC_LANG_PROGRAM([[
-       #include <sched.h>
-       struct sched_param a;
-       int b[] = { SCHED_FIFO, SCHED_RR, SCHED_OTHER };
-       pid_t t1;
-     ]])],
-    [SCHED_H=''],
-    [SCHED_H='sched.h'
-     AC_CHECK_HEADERS([sched.h], [], [],
-       [[#if HAVE_SYS_CDEFS_H
-          #include <sys/cdefs.h>
-         #endif
-       ]])
-     gl_NEXT_HEADERS([sched.h])
+  AC_CHECK_HEADERS([sched.h], [], [],
+    [[#if HAVE_SYS_CDEFS_H
+       #include <sys/cdefs.h>
+      #endif
+    ]])
+  gl_NEXT_HEADERS([sched.h])
+
+  if test "$ac_cv_header_sched_h" = yes; then
+    HAVE_SCHED_H=1
+  else
+    HAVE_SCHED_H=0
+  fi
+  AC_SUBST([HAVE_SCHED_H])
 
-     if test "$ac_cv_header_sched_h" = yes; then
-       HAVE_SCHED_H=1
-     else
-       HAVE_SCHED_H=0
-     fi
-     AC_SUBST([HAVE_SCHED_H])
+  if test "$HAVE_SCHED_H" = 1; then
+    AC_CHECK_TYPE([struct sched_param],
+      [HAVE_STRUCT_SCHED_PARAM=1], [HAVE_STRUCT_SCHED_PARAM=0],
+      [[#if HAVE_SYS_CDEFS_H
+         #include <sys/cdefs.h>
+        #endif
+        #include <sched.h>
+      ]])
+  else
+    HAVE_STRUCT_SCHED_PARAM=0
+    case "$host_os" in
+      os2*)
+        dnl On OS/2 kLIBC, struct sched_param is in spawn.h.
+        AC_CHECK_TYPE([struct sched_param],
+          [HAVE_STRUCT_SCHED_PARAM=1], [],
+          [#include <spawn.h>])
+        ;;
+      vms)
+        dnl On OpenVMS 7.2 or newer, struct sched_param is in pthread.h.
+        AC_CHECK_TYPE([struct sched_param],
+          [HAVE_STRUCT_SCHED_PARAM=1], [],
+          [#include <pthread.h>])
+        ;;
+    esac
+  fi
+  AC_SUBST([HAVE_STRUCT_SCHED_PARAM])
 
-     if test "$HAVE_SCHED_H" = 1; then
-       AC_CHECK_TYPE([struct sched_param],
-         [HAVE_STRUCT_SCHED_PARAM=1], [HAVE_STRUCT_SCHED_PARAM=0],
-         [[#if HAVE_SYS_CDEFS_H
-            #include <sys/cdefs.h>
-           #endif
-           #include <sched.h>
-         ]])
-     else
-       HAVE_STRUCT_SCHED_PARAM=0
-       case "$host_os" in
-         os2*)
-           dnl On OS/2 kLIBC, struct sched_param is in spawn.h.
-           AC_CHECK_TYPE([struct sched_param],
-             [HAVE_STRUCT_SCHED_PARAM=1], [],
-             [#include <spawn.h>])
-           ;;
-         vms)
-           dnl On OpenVMS 7.2 or newer, struct sched_param is in pthread.h.
-           AC_CHECK_TYPE([struct sched_param],
-             [HAVE_STRUCT_SCHED_PARAM=1], [],
-             [#include <pthread.h>])
-           ;;
-       esac
-     fi
-     AC_SUBST([HAVE_STRUCT_SCHED_PARAM])
+  if test "$ac_cv_header_sys_cdefs_h" = yes; then
+    HAVE_SYS_CDEFS_H=1
+  else
+    HAVE_SYS_CDEFS_H=0
+  fi
+  AC_SUBST([HAVE_SYS_CDEFS_H])
 
-     if test "$ac_cv_header_sys_cdefs_h" = yes; then
-       HAVE_SYS_CDEFS_H=1
-     else
-       HAVE_SYS_CDEFS_H=0
-     fi
-     AC_SUBST([HAVE_SYS_CDEFS_H])
+  dnl Ensure the type pid_t gets defined.
+  AC_REQUIRE([AC_TYPE_PID_T])
+
+  dnl Check for declarations of anything we want to poison if the
+  dnl corresponding gnulib module is not in use, if it is not common
+  dnl enough to be declared everywhere.
+  gl_WARN_ON_USE_PREPARE([[#include <sched.h>
+    ]], [sched_yield])
+])
 
-     dnl Ensure the type pid_t gets defined.
-     AC_REQUIRE([AC_TYPE_PID_T])
-    ])
-  AC_SUBST([SCHED_H])
-  AM_CONDITIONAL([GL_GENERATE_SCHED_H], [test -n "$SCHED_H"])
+AC_DEFUN([gl_SCHED_MODULE_INDICATOR],
+[
+  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
+  AC_REQUIRE([gl_SCHED_H_DEFAULTS])
+  gl_MODULE_INDICATOR_SET_VARIABLE([$1])
+  dnl Define it also as a C macro, for the benefit of the unit tests.
+  gl_MODULE_INDICATOR_FOR_TESTS([$1])
+])
+
+AC_DEFUN([gl_SCHED_H_DEFAULTS],
+[
+  GNULIB_SCHED_YIELD=0;  AC_SUBST([GNULIB_SCHED_YIELD])
+  dnl Assume proper GNU behavior unless another module says otherwise.
+  HAVE_SCHED_YIELD=1;    AC_SUBST([HAVE_SCHED_YIELD])
+  REPLACE_SCHED_YIELD=0; AC_SUBST([REPLACE_SCHED_YIELD])
 ])
diff --git a/m4/secure_getenv.m4 b/m4/secure_getenv.m4
index ef3788d..29e2f53 100644
--- a/m4/secure_getenv.m4
+++ b/m4/secure_getenv.m4
@@ -1,5 +1,5 @@
 # Look up an environment variable more securely.
-dnl Copyright 2013-2019 Free Software Foundation, Inc.
+dnl Copyright 2013-2020 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.
diff --git a/m4/select.m4 b/m4/select.m4
index 531c817..90d2bb9 100644
--- a/m4/select.m4
+++ b/m4/select.m4
@@ -1,5 +1,5 @@
-# select.m4 serial 10
-dnl Copyright (C) 2009-2019 Free Software Foundation, Inc.
+# select.m4 serial 12
+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.
@@ -60,7 +60,8 @@ changequote([,])dnl
 #endif
 #include <unistd.h>
 #include <errno.h>
-]],[[
+]GL_MDA_DEFINES],
+[[
   fd_set set;
   dup2(0, 16);
   FD_ZERO(&set);
@@ -78,8 +79,8 @@ changequote([,])dnl
             linux-* | linux) gl_cv_func_select_detects_ebadf="guessing yes" ;;
                              # Guess yes on glibc systems.
             *-gnu* | gnu*)   gl_cv_func_select_detects_ebadf="guessing yes" ;;
-                             # If we don't know, assume the worst.
-            *)               gl_cv_func_select_detects_ebadf="guessing no" ;;
+                             # If we don't know, obey --enable-cross-guesses.
+            *)               gl_cv_func_select_detects_ebadf="$gl_cross_guess_normal" ;;
            esac
           ])
       ])
diff --git a/m4/servent.m4 b/m4/servent.m4
index 477b594..2041c7e 100644
--- a/m4/servent.m4
+++ b/m4/servent.m4
@@ -1,5 +1,5 @@
 # servent.m4 serial 3
-dnl Copyright (C) 2008, 2010-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2008, 2010-2020 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.
diff --git a/m4/setlocale_null.m4 b/m4/setlocale_null.m4
new file mode 100644
index 0000000..fc1e3e1
--- /dev/null
+++ b/m4/setlocale_null.m4
@@ -0,0 +1,98 @@
+# setlocale_null.m4 serial 4
+dnl Copyright (C) 2019-2020 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_FUNC_SETLOCALE_NULL],
+[
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  AC_REQUIRE([gl_PTHREADLIB])
+  AC_CHECK_HEADERS_ONCE([threads.h])
+
+  AC_CACHE_CHECK([whether setlocale (LC_ALL, NULL) is multithread-safe],
+    [gl_cv_func_setlocale_null_all_mtsafe],
+    [case "$host_os" in
+       # Guess no on musl libc, macOS, FreeBSD, NetBSD, OpenBSD, AIX, Haiku, Cygwin.
+       *-musl* | darwin* | freebsd* | netbsd* | openbsd* | aix* | haiku* | cygwin*)
+         gl_cv_func_setlocale_null_all_mtsafe=no ;;
+       # Guess yes on glibc, HP-UX, IRIX, Solaris, native Windows.
+       *-gnu* | gnu* | hpux* | irix* | solaris* | mingw*)
+         gl_cv_func_setlocale_null_all_mtsafe=yes ;;
+       # If we don't know, obey --enable-cross-guesses.
+       *)
+         gl_cv_func_setlocale_null_all_mtsafe="$gl_cross_guess_normal" ;;
+     esac
+    ])
+  dnl On platforms without multithreading, there is no issue.
+  case "$host_os" in
+    mingw*) ;;
+    *)
+      if test $gl_pthread_api = no && test $ac_cv_header_threads_h = no; then
+        gl_cv_func_setlocale_null_all_mtsafe="trivially yes"
+      fi
+      ;;
+  esac
+  case "$gl_cv_func_setlocale_null_all_mtsafe" in
+    *yes) SETLOCALE_NULL_ALL_MTSAFE=1 ;;
+    *)    SETLOCALE_NULL_ALL_MTSAFE=0 ;;
+  esac
+  AC_DEFINE_UNQUOTED([SETLOCALE_NULL_ALL_MTSAFE], [$SETLOCALE_NULL_ALL_MTSAFE],
+    [Define to 1 if setlocale (LC_ALL, NULL) is multithread-safe.])
+
+  dnl This is about a single category (not LC_ALL).
+  AC_CACHE_CHECK([whether setlocale (category, NULL) is multithread-safe],
+    [gl_cv_func_setlocale_null_one_mtsafe],
+    [case "$host_os" in
+       # Guess no on OpenBSD, AIX.
+       openbsd* | aix*)
+         gl_cv_func_setlocale_null_one_mtsafe=no ;;
+       # Guess yes on glibc, musl libc, macOS, FreeBSD, NetBSD, HP-UX, IRIX, Solaris, Haiku, Cygwin, native Windows.
+       *-gnu* | gnu* | *-musl* | darwin* | freebsd* | netbsd* | hpux* | irix* | solaris* | haiku* | cygwin* | mingw*)
+         gl_cv_func_setlocale_null_one_mtsafe=yes ;;
+       # If we don't know, obey --enable-cross-guesses.
+       *)
+         gl_cv_func_setlocale_null_one_mtsafe="$gl_cross_guess_normal" ;;
+     esac
+    ])
+  dnl On platforms without multithreading, there is no issue.
+  case "$host_os" in
+    mingw*) ;;
+    *)
+      if test $gl_pthread_api = no && test $ac_cv_header_threads_h = no; then
+        gl_cv_func_setlocale_null_one_mtsafe="trivially yes"
+      fi
+      ;;
+  esac
+  case "$gl_cv_func_setlocale_null_one_mtsafe" in
+    *yes) SETLOCALE_NULL_ONE_MTSAFE=1 ;;
+    *)    SETLOCALE_NULL_ONE_MTSAFE=0 ;;
+  esac
+  AC_DEFINE_UNQUOTED([SETLOCALE_NULL_ONE_MTSAFE], [$SETLOCALE_NULL_ONE_MTSAFE],
+    [Define to 1 if setlocale (category, NULL) is multithread-safe.])
+
+  dnl Determine link dependencies of lib/setlocale_null.c and lib/setlocale-lock.c.
+  if test $SETLOCALE_NULL_ALL_MTSAFE = 0 || test $SETLOCALE_NULL_ONE_MTSAFE = 0; then
+    case "$host_os" in
+      mingw*) LIB_SETLOCALE_NULL= ;;
+      *)
+        gl_WEAK_SYMBOLS
+        case "$gl_cv_have_weak" in
+          *yes) LIB_SETLOCALE_NULL= ;;
+          *)    LIB_SETLOCALE_NULL="$LIBPTHREAD" ;;
+        esac
+        ;;
+    esac
+  else
+    LIB_SETLOCALE_NULL=
+  fi
+  dnl LIB_SETLOCALE_NULL is expected to be '-pthread' or '-lpthread' on AIX
+  dnl with gcc or xlc, and empty otherwise.
+  AC_SUBST([LIB_SETLOCALE_NULL])
+])
+
+# Prerequisites of lib/setlocale-lock.c.
+AC_DEFUN([gl_PREREQ_SETLOCALE_LOCK],
+[
+  gl_VISIBILITY
+])
diff --git a/m4/sh-filename.m4 b/m4/sh-filename.m4
index dc5f26d..63bbd67 100644
--- a/m4/sh-filename.m4
+++ b/m4/sh-filename.m4
@@ -1,5 +1,5 @@
-# sh-filename.m4 serial 2
-dnl Copyright (C) 2018-2019 Free Software Foundation, Inc.
+# sh-filename.m4 serial 3
+dnl Copyright (C) 2018-2020 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.
@@ -10,8 +10,10 @@ AC_DEFUN([gl_SH_FILENAME],
 [
   AH_VERBATIM([SH_FILENAME],
 [/* File name of the Bourne shell.  */
-#if defined __CYGWIN__ || defined __ANDROID__
+#if (defined _WIN32 && !defined __CYGWIN__) || defined __CYGWIN__ || defined __ANDROID__
 /* Omit the directory part because
+   - For native Windows programs in a Cygwin environment, the Cygwin mounts
+     are not visible.
    - For 32-bit Cygwin programs in a 64-bit Cygwin environment, the Cygwin
      mounts are not visible.
    - On Android, /bin/sh does not exist. It's /system/bin/sh instead.  */
diff --git a/m4/sha1.m4 b/m4/sha1.m4
index bb74fc7..35e3f75 100644
--- a/m4/sha1.m4
+++ b/m4/sha1.m4
@@ -1,5 +1,5 @@
 # sha1.m4 serial 12
-dnl Copyright (C) 2002-2006, 2008-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2002-2006, 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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/sha256.m4 b/m4/sha256.m4
index 929583d..85ff1d5 100644
--- a/m4/sha256.m4
+++ b/m4/sha256.m4
@@ -1,5 +1,5 @@
 # sha256.m4 serial 8
-dnl Copyright (C) 2005, 2008-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2005, 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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/sha512.m4 b/m4/sha512.m4
index d5f5594..fe1592a 100644
--- a/m4/sha512.m4
+++ b/m4/sha512.m4
@@ -1,5 +1,5 @@
 # sha512.m4 serial 9
-dnl Copyright (C) 2005-2006, 2008-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2005-2006, 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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/sig_atomic_t.m4 b/m4/sig_atomic_t.m4
index 2a31575..d695caa 100644
--- a/m4/sig_atomic_t.m4
+++ b/m4/sig_atomic_t.m4
@@ -1,5 +1,5 @@
 # sig_atomic_t.m4 serial 3
-dnl Copyright (C) 2003, 2009-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2003, 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.
diff --git a/m4/sigaction.m4 b/m4/sigaction.m4
index 6117d1b..9a2d201 100644
--- a/m4/sigaction.m4
+++ b/m4/sigaction.m4
@@ -1,5 +1,5 @@
 # sigaction.m4 serial 7
-dnl Copyright (C) 2008-2019 Free Software Foundation, Inc.
+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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/signal_h.m4 b/m4/signal_h.m4
index 3acec64..b262980 100644
--- a/m4/signal_h.m4
+++ b/m4/signal_h.m4
@@ -1,5 +1,5 @@
-# signal_h.m4 serial 18
-dnl Copyright (C) 2007-2019 Free Software Foundation, Inc.
+# signal_h.m4 serial 19
+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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -34,6 +34,8 @@ AC_DEFUN([gl_SIGNAL_H],
     ]], [pthread_sigmask sigaction
     sigaddset sigdelset sigemptyset sigfillset sigismember
     sigpending sigprocmask])
+
+  AC_REQUIRE([AC_C_RESTRICT])
 ])
 
 AC_DEFUN([gl_CHECK_TYPE_SIGSET_T],
diff --git a/m4/signalblocking.m4 b/m4/signalblocking.m4
index d722f65..b7cff8d 100644
--- a/m4/signalblocking.m4
+++ b/m4/signalblocking.m4
@@ -1,5 +1,5 @@
-# signalblocking.m4 serial 14
-dnl Copyright (C) 2001-2002, 2006-2019 Free Software Foundation, Inc.
+# signalblocking.m4 serial 17
+dnl Copyright (C) 2001-2002, 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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -13,11 +13,9 @@ AC_DEFUN([gl_SIGNALBLOCKING],
 [
   AC_REQUIRE([gl_SIGNAL_H_DEFAULTS])
   AC_REQUIRE([gl_CHECK_TYPE_SIGSET_T])
-  if test $gl_cv_type_sigset_t = yes; then
-    AC_CHECK_FUNC([sigprocmask], [gl_cv_func_sigprocmask=1])
-  fi
-  if test -z "$gl_cv_func_sigprocmask"; then
-    HAVE_POSIX_SIGNALBLOCKING=0
+  HAVE_POSIX_SIGNALBLOCKING=0
+  if test "$gl_cv_type_sigset_t" = yes; then
+    AC_CHECK_FUNC([sigprocmask], [HAVE_POSIX_SIGNALBLOCKING=1])
   fi
 ])
 
diff --git a/m4/sigpipe.m4 b/m4/sigpipe.m4
index 0d8128c..dfbf4e0 100644
--- a/m4/sigpipe.m4
+++ b/m4/sigpipe.m4
@@ -1,5 +1,5 @@
 # sigpipe.m4 serial 2
-dnl Copyright (C) 2008-2019 Free Software Foundation, Inc.
+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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/size_max.m4 b/m4/size_max.m4
index ab79052..6ebb93f 100644
--- a/m4/size_max.m4
+++ b/m4/size_max.m4
@@ -1,5 +1,5 @@
-# size_max.m4 serial 11
-dnl Copyright (C) 2003, 2005-2006, 2008-2019 Free Software Foundation, Inc.
+# size_max.m4 serial 12
+dnl Copyright (C) 2003, 2005-2006, 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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -13,7 +13,7 @@ AC_DEFUN([gl_SIZE_MAX],
   AC_CHECK_HEADERS([stdint.h])
   dnl First test whether the system already has SIZE_MAX.
   AC_CACHE_CHECK([for SIZE_MAX], [gl_cv_size_max], [
-    gl_cv_size_max=
+    gl_cv_size_max=no
     AC_EGREP_CPP([Found it], [
 #include <limits.h>
 #if HAVE_STDINT_H
@@ -23,7 +23,7 @@ AC_DEFUN([gl_SIZE_MAX],
 Found it
 #endif
 ], [gl_cv_size_max=yes])
-    if test -z "$gl_cv_size_max"; then
+    if test $gl_cv_size_max != yes; then
       dnl Define it ourselves. Here we assume that the type 'size_t' is not wider
       dnl than the type 'unsigned long'. Try hard to find a definition that can
       dnl be used in a preprocessor #if, i.e. doesn't contain a cast.
diff --git a/m4/snprintf.m4 b/m4/snprintf.m4
index 6fd566d..126039d 100644
--- a/m4/snprintf.m4
+++ b/m4/snprintf.m4
@@ -1,5 +1,5 @@
 # snprintf.m4 serial 7
-dnl Copyright (C) 2002-2004, 2007-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2002-2004, 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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/socketlib.m4 b/m4/socketlib.m4
index 90ba20c..48dd7d6 100644
--- a/m4/socketlib.m4
+++ b/m4/socketlib.m4
@@ -1,5 +1,5 @@
-# socketlib.m4 serial 2
-dnl Copyright (C) 2008-2019 Free Software Foundation, Inc.
+# socketlib.m4 serial 3
+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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -14,21 +14,27 @@ AC_DEFUN([gl_SOCKETLIB],
   LIBSOCKET=
   if test $HAVE_WINSOCK2_H = 1; then
     dnl Native Windows API (not Cygwin).
-    AC_CACHE_CHECK([if we need to call WSAStartup in winsock2.h and -lws2_32],
-                   [gl_cv_func_wsastartup], [
-      gl_save_LIBS="$LIBS"
-      LIBS="$LIBS -lws2_32"
-      AC_LINK_IFELSE([AC_LANG_PROGRAM([[
+    dnl If the function WSAStartup exists (declared in <winsock2.h> and
+    dnl defined through -lws2_32), we need to call it.
+    AC_CACHE_CHECK([for WSAStartup],
+      [gl_cv_func_wsastartup], [
+       gl_save_LIBS="$LIBS"
+       LIBS="$LIBS -lws2_32"
+       AC_LINK_IFELSE(
+         [AC_LANG_PROGRAM([[
 #ifdef HAVE_WINSOCK2_H
 # include <winsock2.h>
 #endif]], [[
-          WORD wVersionRequested = MAKEWORD(1, 1);
-          WSADATA wsaData;
-          int err = WSAStartup(wVersionRequested, &wsaData);
-          WSACleanup ();]])],
-        gl_cv_func_wsastartup=yes, gl_cv_func_wsastartup=no)
-      LIBS="$gl_save_LIBS"
-    ])
+            WORD wVersionRequested = MAKEWORD(1, 1);
+            WSADATA wsaData;
+            int err = WSAStartup(wVersionRequested, &wsaData);
+            WSACleanup ();
+            ]])
+         ],
+         [gl_cv_func_wsastartup=yes],
+         [gl_cv_func_wsastartup=no])
+       LIBS="$gl_save_LIBS"
+      ])
     if test "$gl_cv_func_wsastartup" = "yes"; then
       AC_DEFINE([WINDOWS_SOCKETS], [1], [Define if WSAStartup is needed.])
       LIBSOCKET='-lws2_32'
diff --git a/m4/sockets.m4 b/m4/sockets.m4
index 06d3b9d..7e53ef2 100644
--- a/m4/sockets.m4
+++ b/m4/sockets.m4
@@ -1,5 +1,5 @@
 # sockets.m4 serial 7
-dnl Copyright (C) 2008-2019 Free Software Foundation, Inc.
+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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/socklen.m4 b/m4/socklen.m4
index deb5135..251960b 100644
--- a/m4/socklen.m4
+++ b/m4/socklen.m4
@@ -1,5 +1,5 @@
 # socklen.m4 serial 11
-dnl Copyright (C) 2005-2007, 2009-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/sockpfaf.m4 b/m4/sockpfaf.m4
index 7b32982..495a355 100644
--- a/m4/sockpfaf.m4
+++ b/m4/sockpfaf.m4
@@ -1,5 +1,5 @@
 # sockpfaf.m4 serial 9
-dnl Copyright (C) 2004, 2006, 2009-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2004, 2006, 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.
diff --git a/m4/spawn-pipe.m4 b/m4/spawn-pipe.m4
index 40edebd..471f91d 100644
--- a/m4/spawn-pipe.m4
+++ b/m4/spawn-pipe.m4
@@ -1,5 +1,5 @@
 # spawn-pipe.m4 serial 2
-dnl Copyright (C) 2004, 2008-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2004, 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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/spawn_h.m4 b/m4/spawn_h.m4
index 561caa7..781f9f4 100644
--- a/m4/spawn_h.m4
+++ b/m4/spawn_h.m4
@@ -1,5 +1,5 @@
-# spawn_h.m4 serial 17
-dnl Copyright (C) 2008-2019 Free Software Foundation, Inc.
+# spawn_h.m4 serial 18
+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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -53,7 +53,8 @@ AC_DEFUN([gl_SPAWN_H],
     posix_spawnattr_getschedparam posix_spawnattr_setschedparam
     posix_spawn_file_actions_init posix_spawn_file_actions_destroy
     posix_spawn_file_actions_addopen posix_spawn_file_actions_addclose
-    posix_spawn_file_actions_adddup2 posix_spawn_file_actions_addchdir])
+    posix_spawn_file_actions_adddup2 posix_spawn_file_actions_addchdir
+    posix_spawn_file_actions_addfchdir])
 ])
 
 dnl Checks whether the system has the functions posix_spawn.
@@ -89,28 +90,29 @@ AC_DEFUN([gl_SPAWN_MODULE_INDICATOR],
 
 AC_DEFUN([gl_SPAWN_H_DEFAULTS],
 [
-  GNULIB_POSIX_SPAWN=0;                       AC_SUBST([GNULIB_POSIX_SPAWN])
-  GNULIB_POSIX_SPAWNP=0;                      AC_SUBST([GNULIB_POSIX_SPAWNP])
-  GNULIB_POSIX_SPAWN_FILE_ACTIONS_INIT=0;     AC_SUBST([GNULIB_POSIX_SPAWN_FILE_ACTIONS_INIT])
-  GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR=0; AC_SUBST([GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR])
-  GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDCLOSE=0; AC_SUBST([GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDCLOSE])
-  GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDDUP2=0;  AC_SUBST([GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDDUP2])
-  GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN=0;  AC_SUBST([GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN])
-  GNULIB_POSIX_SPAWN_FILE_ACTIONS_DESTROY=0;  AC_SUBST([GNULIB_POSIX_SPAWN_FILE_ACTIONS_DESTROY])
-  GNULIB_POSIX_SPAWNATTR_INIT=0;              AC_SUBST([GNULIB_POSIX_SPAWNATTR_INIT])
-  GNULIB_POSIX_SPAWNATTR_GETFLAGS=0;          AC_SUBST([GNULIB_POSIX_SPAWNATTR_GETFLAGS])
-  GNULIB_POSIX_SPAWNATTR_SETFLAGS=0;          AC_SUBST([GNULIB_POSIX_SPAWNATTR_SETFLAGS])
-  GNULIB_POSIX_SPAWNATTR_GETPGROUP=0;         AC_SUBST([GNULIB_POSIX_SPAWNATTR_GETPGROUP])
-  GNULIB_POSIX_SPAWNATTR_SETPGROUP=0;         AC_SUBST([GNULIB_POSIX_SPAWNATTR_SETPGROUP])
-  GNULIB_POSIX_SPAWNATTR_GETSCHEDPARAM=0;     AC_SUBST([GNULIB_POSIX_SPAWNATTR_GETSCHEDPARAM])
-  GNULIB_POSIX_SPAWNATTR_SETSCHEDPARAM=0;     AC_SUBST([GNULIB_POSIX_SPAWNATTR_SETSCHEDPARAM])
-  GNULIB_POSIX_SPAWNATTR_GETSCHEDPOLICY=0;    AC_SUBST([GNULIB_POSIX_SPAWNATTR_GETSCHEDPOLICY])
-  GNULIB_POSIX_SPAWNATTR_SETSCHEDPOLICY=0;    AC_SUBST([GNULIB_POSIX_SPAWNATTR_SETSCHEDPOLICY])
-  GNULIB_POSIX_SPAWNATTR_GETSIGDEFAULT=0;     AC_SUBST([GNULIB_POSIX_SPAWNATTR_GETSIGDEFAULT])
-  GNULIB_POSIX_SPAWNATTR_SETSIGDEFAULT=0;     AC_SUBST([GNULIB_POSIX_SPAWNATTR_SETSIGDEFAULT])
-  GNULIB_POSIX_SPAWNATTR_GETSIGMASK=0;        AC_SUBST([GNULIB_POSIX_SPAWNATTR_GETSIGMASK])
-  GNULIB_POSIX_SPAWNATTR_SETSIGMASK=0;        AC_SUBST([GNULIB_POSIX_SPAWNATTR_SETSIGMASK])
-  GNULIB_POSIX_SPAWNATTR_DESTROY=0;           AC_SUBST([GNULIB_POSIX_SPAWNATTR_DESTROY])
+  GNULIB_POSIX_SPAWN=0;                        AC_SUBST([GNULIB_POSIX_SPAWN])
+  GNULIB_POSIX_SPAWNP=0;                       AC_SUBST([GNULIB_POSIX_SPAWNP])
+  GNULIB_POSIX_SPAWN_FILE_ACTIONS_INIT=0;      AC_SUBST([GNULIB_POSIX_SPAWN_FILE_ACTIONS_INIT])
+  GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR=0;  AC_SUBST([GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR])
+  GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDCLOSE=0;  AC_SUBST([GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDCLOSE])
+  GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDDUP2=0;   AC_SUBST([GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDDUP2])
+  GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDFCHDIR=0; AC_SUBST([GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDFCHDIR])
+  GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN=0;   AC_SUBST([GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN])
+  GNULIB_POSIX_SPAWN_FILE_ACTIONS_DESTROY=0;   AC_SUBST([GNULIB_POSIX_SPAWN_FILE_ACTIONS_DESTROY])
+  GNULIB_POSIX_SPAWNATTR_INIT=0;               AC_SUBST([GNULIB_POSIX_SPAWNATTR_INIT])
+  GNULIB_POSIX_SPAWNATTR_GETFLAGS=0;           AC_SUBST([GNULIB_POSIX_SPAWNATTR_GETFLAGS])
+  GNULIB_POSIX_SPAWNATTR_SETFLAGS=0;           AC_SUBST([GNULIB_POSIX_SPAWNATTR_SETFLAGS])
+  GNULIB_POSIX_SPAWNATTR_GETPGROUP=0;          AC_SUBST([GNULIB_POSIX_SPAWNATTR_GETPGROUP])
+  GNULIB_POSIX_SPAWNATTR_SETPGROUP=0;          AC_SUBST([GNULIB_POSIX_SPAWNATTR_SETPGROUP])
+  GNULIB_POSIX_SPAWNATTR_GETSCHEDPARAM=0;      AC_SUBST([GNULIB_POSIX_SPAWNATTR_GETSCHEDPARAM])
+  GNULIB_POSIX_SPAWNATTR_SETSCHEDPARAM=0;      AC_SUBST([GNULIB_POSIX_SPAWNATTR_SETSCHEDPARAM])
+  GNULIB_POSIX_SPAWNATTR_GETSCHEDPOLICY=0;     AC_SUBST([GNULIB_POSIX_SPAWNATTR_GETSCHEDPOLICY])
+  GNULIB_POSIX_SPAWNATTR_SETSCHEDPOLICY=0;     AC_SUBST([GNULIB_POSIX_SPAWNATTR_SETSCHEDPOLICY])
+  GNULIB_POSIX_SPAWNATTR_GETSIGDEFAULT=0;      AC_SUBST([GNULIB_POSIX_SPAWNATTR_GETSIGDEFAULT])
+  GNULIB_POSIX_SPAWNATTR_SETSIGDEFAULT=0;      AC_SUBST([GNULIB_POSIX_SPAWNATTR_SETSIGDEFAULT])
+  GNULIB_POSIX_SPAWNATTR_GETSIGMASK=0;         AC_SUBST([GNULIB_POSIX_SPAWNATTR_GETSIGMASK])
+  GNULIB_POSIX_SPAWNATTR_SETSIGMASK=0;         AC_SUBST([GNULIB_POSIX_SPAWNATTR_SETSIGMASK])
+  GNULIB_POSIX_SPAWNATTR_DESTROY=0;            AC_SUBST([GNULIB_POSIX_SPAWNATTR_DESTROY])
   dnl Assume proper GNU behavior unless another module says otherwise.
   HAVE_POSIX_SPAWN=1;        AC_SUBST([HAVE_POSIX_SPAWN])
   HAVE_POSIX_SPAWNATTR_T=1;  AC_SUBST([HAVE_POSIX_SPAWNATTR_T])
@@ -118,6 +120,8 @@ AC_DEFUN([gl_SPAWN_H_DEFAULTS],
                              AC_SUBST([HAVE_POSIX_SPAWN_FILE_ACTIONS_T])
   HAVE_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR=1;
                              AC_SUBST([HAVE_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR])
+  HAVE_POSIX_SPAWN_FILE_ACTIONS_ADDFCHDIR=1;
+                             AC_SUBST([HAVE_POSIX_SPAWN_FILE_ACTIONS_ADDFCHDIR])
   REPLACE_POSIX_SPAWN=0;     AC_SUBST([REPLACE_POSIX_SPAWN])
   REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR=0;
                              AC_SUBST([REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR])
@@ -125,6 +129,8 @@ AC_DEFUN([gl_SPAWN_H_DEFAULTS],
                              AC_SUBST([REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDCLOSE])
   REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDDUP2=0;
                              AC_SUBST([REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDDUP2])
+  REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDFCHDIR=0;
+                             AC_SUBST([REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDFCHDIR])
   REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN=0;
                              AC_SUBST([REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN])
 ])
diff --git a/m4/ssize_t.m4 b/m4/ssize_t.m4
index 38bcee1..6c0a588 100644
--- a/m4/ssize_t.m4
+++ b/m4/ssize_t.m4
@@ -1,5 +1,5 @@
 # ssize_t.m4 serial 5 (gettext-0.18.2)
-dnl Copyright (C) 2001-2003, 2006, 2010-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2001-2003, 2006, 2010-2020 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.
diff --git a/m4/stat-time.m4 b/m4/stat-time.m4
index 1685788..0ac3f72 100644
--- a/m4/stat-time.m4
+++ b/m4/stat-time.m4
@@ -1,6 +1,6 @@
 # Checks for stat-related time functions.
 
-# Copyright (C) 1998-1999, 2001, 2003, 2005-2007, 2009-2019 Free Software
+# Copyright (C) 1998-1999, 2001, 2003, 2005-2007, 2009-2020 Free Software
 # Foundation, Inc.
 
 # This file is free software; the Free Software Foundation
diff --git a/m4/stat.m4 b/m4/stat.m4
index 60040d1..db2038f 100644
--- a/m4/stat.m4
+++ b/m4/stat.m4
@@ -1,6 +1,6 @@
-# serial 15
+# serial 17
 
-# Copyright (C) 2009-2019 Free Software Foundation, Inc.
+# Copyright (C) 2009-2020 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -47,8 +47,8 @@ AC_DEFUN([gl_FUNC_STAT],
               linux-* | linux) gl_cv_func_stat_file_slash="guessing yes" ;;
                                # Guess yes on glibc systems.
               *-gnu* | gnu*)   gl_cv_func_stat_file_slash="guessing yes" ;;
-                               # If we don't know, assume the worst.
-              *)               gl_cv_func_stat_file_slash="guessing no" ;;
+                               # If we don't know, obey --enable-cross-guesses.
+              *)               gl_cv_func_stat_file_slash="$gl_cross_guess_normal" ;;
             esac
            ])
          rm -f conftest.tmp conftest.lnk])
@@ -70,5 +70,16 @@ AC_DEFUN([gl_FUNC_STAT],
 # Prerequisites of lib/stat.c and lib/stat-w32.c.
 AC_DEFUN([gl_PREREQ_STAT], [
   AC_REQUIRE([gl_HEADER_SYS_STAT_H])
+  AC_REQUIRE([gl_PREREQ_STAT_W32])
   :
 ])
+
+# Prerequisites of lib/stat-w32.c.
+AC_DEFUN([gl_PREREQ_STAT_W32], [
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  case "$host_os" in
+    mingw*)
+      AC_CHECK_HEADERS([sdkddkver.h])
+      ;;
+  esac
+])
diff --git a/m4/std-gnu11.m4 b/m4/std-gnu11.m4
deleted file mode 100644
index 23e7f75..0000000
--- a/m4/std-gnu11.m4
+++ /dev/null
@@ -1,824 +0,0 @@
-# Prefer GNU C11 and C++11 to earlier versions.  -*- coding: utf-8 -*-
-
-# This implementation is taken from GNU Autoconf lib/autoconf/c.m4
-# commit 017d5ddd82854911f0119691d91ea8a1438824d6
-# dated Sun Apr 3 13:57:17 2016 -0700
-# This implementation will be obsolete once we can assume Autoconf 2.70
-# or later is installed everywhere a Gnulib program might be developed.
-
-
-# Copyright (C) 2001-2019 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 3 of the License, 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 David MacKenzie, with help from
-# Akim Demaille, Paul Eggert,
-# François Pinard, Karl Berry, Richard Pixley, Ian Lance Taylor,
-# Roland McGrath, Noah Friedman, david d zuhn, and many others.
-
-
-# AC_PROG_CC([COMPILER ...])
-# --------------------------
-# COMPILER ... is a space separated list of C compilers to search for.
-# This just gives the user an opportunity to specify an alternative
-# search list for the C compiler.
-AC_DEFUN_ONCE([AC_PROG_CC],
-[AC_LANG_PUSH(C)dnl
-AC_ARG_VAR([CC],     [C compiler command])dnl
-AC_ARG_VAR([CFLAGS], [C compiler flags])dnl
-_AC_ARG_VAR_LDFLAGS()dnl
-_AC_ARG_VAR_LIBS()dnl
-_AC_ARG_VAR_CPPFLAGS()dnl
-m4_ifval([$1],
-      [AC_CHECK_TOOLS(CC, [$1])],
-[AC_CHECK_TOOL(CC, gcc)
-if test -z "$CC"; then
-  dnl Here we want:
-  dnl	AC_CHECK_TOOL(CC, cc)
-  dnl but without the check for a tool without the prefix.
-  dnl Until the check is removed from there, copy the code:
-  if test -n "$ac_tool_prefix"; then
-    AC_CHECK_PROG(CC, [${ac_tool_prefix}cc], [${ac_tool_prefix}cc])
-  fi
-fi
-if test -z "$CC"; then
-  AC_CHECK_PROG(CC, cc, cc, , , /usr/ucb/cc)
-fi
-if test -z "$CC"; then
-  AC_CHECK_TOOLS(CC, cl.exe)
-fi
-if test -z "$CC"; then
-  AC_CHECK_TOOL(CC, clang)
-fi
-])
-
-test -z "$CC" && AC_MSG_FAILURE([no acceptable C compiler found in \$PATH])
-
-# Provide some information about the compiler.
-_AS_ECHO_LOG([checking for _AC_LANG compiler version])
-set X $ac_compile
-ac_compiler=$[2]
-for ac_option in --version -v -V -qversion -version; do
-  m4_ifdef([_AC_DO_LIMIT],[_AC_DO_LIMIT],[_AC_DO])([$ac_compiler $ac_option >&AS_MESSAGE_LOG_FD])
-done
-
-m4_expand_once([_AC_COMPILER_EXEEXT])[]dnl
-m4_expand_once([_AC_COMPILER_OBJEXT])[]dnl
-_AC_LANG_COMPILER_GNU
-if test $ac_compiler_gnu = yes; then
-  GCC=yes
-else
-  GCC=
-fi
-_AC_PROG_CC_G
-dnl
-dnl Set ac_prog_cc_stdc to the supported C version.
-dnl Also set the documented variable ac_cv_prog_cc_stdc;
-dnl its name was chosen when it was cached, but it is no longer cached.
-_AC_PROG_CC_C11([ac_prog_cc_stdc=c11
-		 ac_cv_prog_cc_stdc=$ac_cv_prog_cc_c11],
-  [_AC_PROG_CC_C99([ac_prog_cc_stdc=c99
-		    ac_cv_prog_cc_stdc=$ac_cv_prog_cc_c99],
-     [_AC_PROG_CC_C89([ac_prog_cc_stdc=c89
-		       ac_cv_prog_cc_stdc=$ac_cv_prog_cc_c89],
-		      [ac_prog_cc_stdc=no
-		       ac_cv_prog_cc_stdc=no])])])
-dnl
-AC_LANG_POP(C)dnl
-])# AC_PROG_CC
-
-
-
-# AC_PROG_CXX([LIST-OF-COMPILERS])
-# --------------------------------
-# LIST-OF-COMPILERS is a space separated list of C++ compilers to search
-# for (if not specified, a default list is used).  This just gives the
-# user an opportunity to specify an alternative search list for the C++
-# compiler.
-# aCC	HP-UX C++ compiler much better than `CC', so test before.
-# FCC   Fujitsu C++ compiler
-# KCC	KAI C++ compiler
-# RCC	Rational C++
-# xlC_r	AIX C Set++ (with support for reentrant code)
-# xlC	AIX C Set++
-AC_DEFUN([AC_PROG_CXX],
-[AC_LANG_PUSH(C++)dnl
-AC_ARG_VAR([CXX],      [C++ compiler command])dnl
-AC_ARG_VAR([CXXFLAGS], [C++ compiler flags])dnl
-_AC_ARG_VAR_LDFLAGS()dnl
-_AC_ARG_VAR_LIBS()dnl
-_AC_ARG_VAR_CPPFLAGS()dnl
-_AC_ARG_VAR_PRECIOUS([CCC])dnl
-if test -z "$CXX"; then
-  if test -n "$CCC"; then
-    CXX=$CCC
-  else
-    AC_CHECK_TOOLS(CXX,
-		   [m4_default([$1],
-			       [g++ c++ gpp aCC CC cxx cc++ cl.exe FCC KCC RCC xlC_r xlC clang++])],
-		   g++)
-  fi
-fi
-# Provide some information about the compiler.
-_AS_ECHO_LOG([checking for _AC_LANG compiler version])
-set X $ac_compile
-ac_compiler=$[2]
-for ac_option in --version -v -V -qversion; do
-  m4_ifdef([_AC_DO_LIMIT],[_AC_DO_LIMIT],[_AC_DO])([$ac_compiler $ac_option >&AS_MESSAGE_LOG_FD])
-done
-
-m4_expand_once([_AC_COMPILER_EXEEXT])[]dnl
-m4_expand_once([_AC_COMPILER_OBJEXT])[]dnl
-_AC_LANG_COMPILER_GNU
-if test $ac_compiler_gnu = yes; then
-  GXX=yes
-else
-  GXX=
-fi
-_AC_PROG_CXX_G
-_AC_PROG_CXX_CXX11([ac_prog_cxx_stdcxx=cxx11
-		    ac_cv_prog_cxx_stdcxx=$ac_cv_prog_cxx_cxx11
-		    ac_cv_prog_cxx_cxx98=$ac_cv_prog_cxx_cxx11],
-   [_AC_PROG_CXX_CXX98([ac_prog_cxx_stdcxx=cxx98
-		        ac_cv_prog_cxx_stdcxx=$ac_cv_prog_cxx_cxx98],
-		       [ac_prog_cxx_stdcxx=no
-		        ac_cv_prog_cxx_stdcxx=no])])
-AC_LANG_POP(C++)dnl
-])# AC_PROG_CXX
-
-
-# _AC_C_STD_TRY(STANDARD, TEST-PROLOGUE, TEST-BODY, OPTION-LIST,
-#		ACTION-IF-AVAILABLE, ACTION-IF-UNAVAILABLE)
-# --------------------------------------------------------------
-# Check whether the C compiler accepts features of STANDARD (e.g `c89', `c99')
-# by trying to compile a program of TEST-PROLOGUE and TEST-BODY.  If this fails,
-# try again with each compiler option in the space-separated OPTION-LIST; if one
-# helps, append it to CC.  If eventually successful, run ACTION-IF-AVAILABLE,
-# else ACTION-IF-UNAVAILABLE.
-AC_DEFUN([_AC_C_STD_TRY],
-[AC_MSG_CHECKING([for $CC option to enable ]m4_translit($1, [c], [C])[ features])
-AC_CACHE_VAL(ac_cv_prog_cc_$1,
-[ac_cv_prog_cc_$1=no
-ac_save_CC=$CC
-AC_LANG_CONFTEST([AC_LANG_PROGRAM([$2], [$3])])
-for ac_arg in '' $4
-do
-  CC="$ac_save_CC $ac_arg"
-  _AC_COMPILE_IFELSE([], [ac_cv_prog_cc_$1=$ac_arg])
-  test "x$ac_cv_prog_cc_$1" != "xno" && break
-done
-rm -f conftest.$ac_ext
-CC=$ac_save_CC
-])# AC_CACHE_VAL
-ac_prog_cc_stdc_options=
-case "x$ac_cv_prog_cc_$1" in
-  x)
-    AC_MSG_RESULT([none needed]) ;;
-  xno)
-    AC_MSG_RESULT([unsupported]) ;;
-  *)
-    ac_prog_cc_stdc_options=" $ac_cv_prog_cc_$1"
-    CC=$CC$ac_prog_cc_stdc_options
-    AC_MSG_RESULT([$ac_cv_prog_cc_$1]) ;;
-esac
-AS_IF([test "x$ac_cv_prog_cc_$1" != xno], [$5], [$6])
-])# _AC_C_STD_TRY
-
-# _AC_C_C99_TEST_HEADER
-# ---------------------
-# A C header suitable for testing for C99.
-AC_DEFUN([_AC_C_C99_TEST_HEADER],
-[[#include <stdarg.h>
-#include <stdbool.h>
-#include <stddef.h>
-#include <stdlib.h>
-#include <wchar.h>
-#include <stdio.h>
-
-// Check varargs macros.  These examples are taken from C99 6.10.3.5.
-#define debug(...) fprintf (stderr, __VA_ARGS__)
-#define showlist(...) puts (#__VA_ARGS__)
-#define report(test,...) ((test) ? puts (#test) : printf (__VA_ARGS__))
-static void
-test_varargs_macros (void)
-{
-  int x = 1234;
-  int y = 5678;
-  debug ("Flag");
-  debug ("X = %d\n", x);
-  showlist (The first, second, and third items.);
-  report (x>y, "x is %d but y is %d", x, y);
-}
-
-// Check long long types.
-#define BIG64 18446744073709551615ull
-#define BIG32 4294967295ul
-#define BIG_OK (BIG64 / BIG32 == 4294967297ull && BIG64 % BIG32 == 0)
-#if !BIG_OK
-  your preprocessor is broken;
-#endif
-#if BIG_OK
-#else
-  your preprocessor is broken;
-#endif
-static long long int bignum = -9223372036854775807LL;
-static unsigned long long int ubignum = BIG64;
-
-struct incomplete_array
-{
-  int datasize;
-  double data[];
-};
-
-struct named_init {
-  int number;
-  const wchar_t *name;
-  double average;
-};
-
-typedef const char *ccp;
-
-static inline int
-test_restrict (ccp restrict text)
-{
-  // See if C++-style comments work.
-  // Iterate through items via the restricted pointer.
-  // Also check for declarations in for loops.
-  for (unsigned int i = 0; *(text+i) != '\0'; ++i)
-    continue;
-  return 0;
-}
-
-// Check varargs and va_copy.
-static bool
-test_varargs (const char *format, ...)
-{
-  va_list args;
-  va_start (args, format);
-  va_list args_copy;
-  va_copy (args_copy, args);
-
-  const char *str = "";
-  int number = 0;
-  float fnumber = 0;
-
-  while (*format)
-    {
-      switch (*format++)
-	{
-	case 's': // string
-	  str = va_arg (args_copy, const char *);
-	  break;
-	case 'd': // int
-	  number = va_arg (args_copy, int);
-	  break;
-	case 'f': // float
-	  fnumber = va_arg (args_copy, double);
-	  break;
-	default:
-	  break;
-	}
-    }
-  va_end (args_copy);
-  va_end (args);
-
-  return *str && number && fnumber;
-}]])# _AC_C_C99_TEST_HEADER
-
-# _AC_C_C99_TEST_BODY
-# -------------------
-# A C body suitable for testing for C99, assuming the corresponding header.
-AC_DEFUN([_AC_C_C99_TEST_BODY],
-[[
-  // Check bool.
-  _Bool success = false;
-
-  // Check restrict.
-  if (test_restrict ("String literal") == 0)
-    success = true;
-  char *restrict newvar = "Another string";
-
-  // Check varargs.
-  success &= test_varargs ("s, d' f .", "string", 65, 34.234);
-  test_varargs_macros ();
-
-  // Check flexible array members.
-  struct incomplete_array *ia =
-    malloc (sizeof (struct incomplete_array) + (sizeof (double) * 10));
-  ia->datasize = 10;
-  for (int i = 0; i < ia->datasize; ++i)
-    ia->data[i] = i * 1.234;
-
-  // Check named initializers.
-  struct named_init ni = {
-    .number = 34,
-    .name = L"Test wide string",
-    .average = 543.34343,
-  };
-
-  ni.number = 58;
-
-  int dynamic_array[ni.number];
-  dynamic_array[ni.number - 1] = 543;
-
-  // work around unused variable warnings
-  return (!success || bignum == 0LL || ubignum == 0uLL || newvar[0] == 'x'
-	  || dynamic_array[ni.number - 1] != 543);
-]])
-
-# _AC_PROG_CC_C99 ([ACTION-IF-AVAILABLE], [ACTION-IF-UNAVAILABLE])
-# ----------------------------------------------------------------
-# If the C compiler is not in ISO C99 mode by default, try to add an
-# option to output variable CC to make it so.  This macro tries
-# various options that select ISO C99 on some system or another.  It
-# considers the compiler to be in ISO C99 mode if it handles _Bool,
-# // comments, flexible array members, inline, long long int, mixed
-# code and declarations, named initialization of structs, restrict,
-# va_copy, varargs macros, variable declarations in for loops and
-# variable length arrays.
-AC_DEFUN([_AC_PROG_CC_C99],
-[_AC_C_STD_TRY([c99],
-[_AC_C_C99_TEST_HEADER],
-[_AC_C_C99_TEST_BODY],
-dnl Try
-dnl GCC		-std=gnu99 (unused restrictive modes: -std=c99 -std=iso9899:1999)
-dnl IBM XL C	-qlanglvl=extc1x (V12.1; does not pass C11 test)
-dnl IBM XL C	-qlanglvl=extc99
-dnl		(pre-V12.1; unused restrictive mode: -qlanglvl=stdc99)
-dnl HP cc	-AC99
-dnl Intel ICC	-std=c99, -c99 (deprecated)
-dnl IRIX	-c99
-dnl Solaris	-D_STDC_C99=
-dnl		cc's -xc99 option uses linker magic to define the external
-dnl		symbol __xpg4 as if by "int __xpg4 = 1;", which enables C99
-dnl		behavior for C library functions.  This is not wanted here,
-dnl		because it means that a single module compiled with -xc99
-dnl		alters C runtime behavior for the entire program, not for
-dnl		just the module.  Instead, define the (private) symbol
-dnl		_STDC_C99, which suppresses a bogus failure in <stdbool.h>.
-dnl		The resulting compiler passes the test case here, and that's
-dnl		good enough.  For more, please see the thread starting at:
-dnl            https://lists.gnu.org/r/autoconf/2010-12/msg00059.html
-dnl Tru64	-c99
-dnl with extended modes being tried first.
-[[-std=gnu99 -std=c99 -c99 -AC99 -D_STDC_C99= -qlanglvl=extc1x -qlanglvl=extc99]], [$1], [$2])[]dnl
-])# _AC_PROG_CC_C99
-
-
-# _AC_PROG_CC_C11 ([ACTION-IF-AVAILABLE], [ACTION-IF-UNAVAILABLE])
-# ----------------------------------------------------------------
-# If the C compiler is not in ISO C11 mode by default, try to add an
-# option to output variable CC to make it so.  This macro tries
-# various options that select ISO C11 on some system or another.  It
-# considers the compiler to be in ISO C11 mode if it handles _Alignas,
-# _Alignof, _Noreturn, _Static_assert, UTF-8 string literals,
-# duplicate typedefs, and anonymous structures and unions.
-AC_DEFUN([_AC_PROG_CC_C11],
-[_AC_C_STD_TRY([c11],
-[_AC_C_C99_TEST_HEADER[
-// Check _Alignas.
-char _Alignas (double) aligned_as_double;
-char _Alignas (0) no_special_alignment;
-extern char aligned_as_int;
-char _Alignas (0) _Alignas (int) aligned_as_int;
-
-// Check _Alignof.
-enum
-{
-  int_alignment = _Alignof (int),
-  int_array_alignment = _Alignof (int[100]),
-  char_alignment = _Alignof (char)
-};
-_Static_assert (0 < -_Alignof (int), "_Alignof is signed");
-
-// Check _Noreturn.
-int _Noreturn does_not_return (void) { for (;;) continue; }
-
-// Check _Static_assert.
-struct test_static_assert
-{
-  int x;
-  _Static_assert (sizeof (int) <= sizeof (long int),
-                  "_Static_assert does not work in struct");
-  long int y;
-};
-
-// Check UTF-8 literals.
-#define u8 syntax error!
-char const utf8_literal[] = u8"happens to be ASCII" "another string";
-
-// Check duplicate typedefs.
-typedef long *long_ptr;
-typedef long int *long_ptr;
-typedef long_ptr long_ptr;
-
-// Anonymous structures and unions -- taken from C11 6.7.2.1 Example 1.
-struct anonymous
-{
-  union {
-    struct { int i; int j; };
-    struct { int k; long int l; } w;
-  };
-  int m;
-} v1;
-]],
-[_AC_C_C99_TEST_BODY[
-  v1.i = 2;
-  v1.w.k = 5;
-  _Static_assert ((offsetof (struct anonymous, i)
-		   == offsetof (struct anonymous, w.k)),
-		  "Anonymous union alignment botch");
-]],
-dnl Try
-dnl GCC		-std=gnu11 (unused restrictive mode: -std=c11)
-dnl with extended modes being tried first.
-dnl
-dnl Do not try -qlanglvl=extc1x, because IBM XL C V12.1 (the latest version as
-dnl of September 2012) does not pass the C11 test.  For now, try extc1x when
-dnl compiling the C99 test instead, since it enables _Static_assert and
-dnl _Noreturn, which is a win.  If -qlanglvl=extc11 or -qlanglvl=extc1x passes
-dnl the C11 test in some future version of IBM XL C, we'll add it here,
-dnl preferably extc11.
-[[-std=gnu11]], [$1], [$2])[]dnl
-])# _AC_PROG_CC_C11
-
-
-# AC_PROG_CC_C89
-# --------------
-# Do not use AU_ALIAS here and in AC_PROG_CC_C99 and AC_PROG_CC_STDC,
-# as that'd be incompatible with how Automake redefines AC_PROG_CC.  See
-# <https://lists.gnu.org/r/autoconf/2012-10/msg00048.html>.
-AU_DEFUN([AC_PROG_CC_C89],
-  [AC_REQUIRE([AC_PROG_CC])],
-  [$0 is obsolete; use AC_PROG_CC]
-)
-
-# AC_PROG_CC_C99
-# --------------
-AU_DEFUN([AC_PROG_CC_C99],
-  [AC_REQUIRE([AC_PROG_CC])],
-  [$0 is obsolete; use AC_PROG_CC]
-)
-
-# AC_PROG_CC_STDC
-# ---------------
-AU_DEFUN([AC_PROG_CC_STDC],
-  [AC_REQUIRE([AC_PROG_CC])],
-  [$0 is obsolete; use AC_PROG_CC]
-)
-
-
-# AC_C_PROTOTYPES
-# ---------------
-# Check if the C compiler supports prototypes, included if it needs
-# options.
-AC_DEFUN([AC_C_PROTOTYPES],
-[AC_REQUIRE([AC_PROG_CC])dnl
-if test "$ac_prog_cc_stdc" != no; then
-  AC_DEFINE(PROTOTYPES, 1,
-	    [Define to 1 if the C compiler supports function prototypes.])
-  AC_DEFINE(__PROTOTYPES, 1,
-	    [Define like PROTOTYPES; this can be used by system headers.])
-fi
-])# AC_C_PROTOTYPES
-
-
-# _AC_CXX_STD_TRY(STANDARD, TEST-PROLOGUE, TEST-BODY, OPTION-LIST,
-#		  ACTION-IF-AVAILABLE, ACTION-IF-UNAVAILABLE)
-# ----------------------------------------------------------------
-# Check whether the C++ compiler accepts features of STANDARD (e.g
-# `cxx98', `cxx11') by trying to compile a program of TEST-PROLOGUE
-# and TEST-BODY.  If this fails, try again with each compiler option
-# in the space-separated OPTION-LIST; if one helps, append it to CXX.
-# If eventually successful, run ACTION-IF-AVAILABLE, else
-# ACTION-IF-UNAVAILABLE.
-AC_DEFUN([_AC_CXX_STD_TRY],
-[AC_MSG_CHECKING([for $CXX option to enable ]m4_translit(m4_translit($1, [x], [+]), [a-z], [A-Z])[ features])
-AC_LANG_PUSH(C++)dnl
-AC_CACHE_VAL(ac_cv_prog_cxx_$1,
-[ac_cv_prog_cxx_$1=no
-ac_save_CXX=$CXX
-AC_LANG_CONFTEST([AC_LANG_PROGRAM([$2], [$3])])
-for ac_arg in '' $4
-do
-  CXX="$ac_save_CXX $ac_arg"
-  _AC_COMPILE_IFELSE([], [ac_cv_prog_cxx_$1=$ac_arg])
-  test "x$ac_cv_prog_cxx_$1" != "xno" && break
-done
-rm -f conftest.$ac_ext
-CXX=$ac_save_CXX
-])# AC_CACHE_VAL
-ac_prog_cxx_stdcxx_options=
-case "x$ac_cv_prog_cxx_$1" in
-  x)
-    AC_MSG_RESULT([none needed]) ;;
-  xno)
-    AC_MSG_RESULT([unsupported]) ;;
-  *)
-    ac_prog_cxx_stdcxx_options=" $ac_cv_prog_cxx_$1"
-    CXX=$CXX$ac_prog_cxx_stdcxx_options
-    AC_MSG_RESULT([$ac_cv_prog_cxx_$1]) ;;
-esac
-AC_LANG_POP(C++)dnl
-AS_IF([test "x$ac_cv_prog_cxx_$1" != xno], [$5], [$6])
-])# _AC_CXX_STD_TRY
-
-# _AC_CXX_CXX98_TEST_HEADER
-# -------------------------
-# A C++ header suitable for testing for CXX98.
-AC_DEFUN([_AC_CXX_CXX98_TEST_HEADER],
-[[
-#include <algorithm>
-#include <cstdlib>
-#include <fstream>
-#include <iomanip>
-#include <iostream>
-#include <list>
-#include <map>
-#include <set>
-#include <sstream>
-#include <stdexcept>
-#include <string>
-#include <utility>
-#include <vector>
-
-namespace test {
-  typedef std::vector<std::string> string_vec;
-  typedef std::pair<int,bool> map_value;
-  typedef std::map<std::string,map_value> map_type;
-  typedef std::set<int> set_type;
-
-  template<typename T>
-  class printer {
-  public:
-    printer(std::ostringstream& os): os(os) {}
-    void operator() (T elem) { os << elem << std::endl; }
-  private:
-    std::ostringstream& os;
-  };
-}
-]])# _AC_CXX_CXX98_TEST_HEADER
-
-# _AC_CXX_CXX98_TEST_BODY
-# -----------------------
-# A C++ body suitable for testing for CXX98, assuming the corresponding header.
-AC_DEFUN([_AC_CXX_CXX98_TEST_BODY],
-[[
-
-try {
-  // Basic string.
-  std::string teststr("ASCII text");
-  teststr += " string";
-
-  // Simple vector.
-  test::string_vec testvec;
-  testvec.push_back(teststr);
-  testvec.push_back("foo");
-  testvec.push_back("bar");
-  if (testvec.size() != 3) {
-    throw std::runtime_error("vector size is not 1");
-  }
-
-  // Dump vector into stringstream and obtain string.
-  std::ostringstream os;
-  for (test::string_vec::const_iterator i = testvec.begin();
-       i != testvec.end(); ++i) {
-    if (i + 1 != testvec.end()) {
-      os << teststr << '\n';
-    }
-  }
-  // Check algorithms work.
-  std::for_each(testvec.begin(), testvec.end(), test::printer<std::string>(os));
-  std::string os_out = os.str();
-
-  // Test pair and map.
-  test::map_type testmap;
-  testmap.insert(std::make_pair(std::string("key"),
-                                std::make_pair(53,false)));
-
-  // Test set.
-  int values[] = {9, 7, 13, 15, 4, 18, 12, 10, 5, 3, 14, 19, 17, 8, 6, 20, 16, 2, 11, 1};
-  test::set_type testset(values, values + sizeof(values)/sizeof(values[0]));
-  std::list<int> testlist(testset.begin(), testset.end());
-  std::copy(testset.begin(), testset.end(), std::back_inserter(testlist));
-} catch (const std::exception& e) {
-  std::cerr << "Caught exception: " << e.what() << std::endl;
-
-  // Test fstream
-  std::ofstream of("test.txt");
-  of << "Test ASCII text\n" << std::flush;
-  of << "N= " << std::hex << std::setw(8) << std::left << 534 << std::endl;
-  of.close();
-}
-std::exit(0);
-]])
-
-# _AC_CXX_CXX11_TEST_HEADER
-# -------------------------
-# A C++ header suitable for testing for CXX11.
-AC_DEFUN([_AC_CXX_CXX11_TEST_HEADER],
-[[
-#include <deque>
-#include <functional>
-#include <memory>
-#include <tuple>
-#include <array>
-#include <regex>
-#include <iostream>
-
-namespace cxx11test
-{
-  typedef std::shared_ptr<std::string> sptr;
-  typedef std::weak_ptr<std::string> wptr;
-
-  typedef std::tuple<std::string,int,double> tp;
-  typedef std::array<int, 20> int_array;
-
-  constexpr int get_val() { return 20; }
-
-  struct testinit
-  {
-    int i;
-    double d;
-  };
-
-  class delegate  {
-  public:
-    delegate(int n) : n(n) {}
-    delegate(): delegate(2354) {}
-
-    virtual int getval() { return this->n; };
-  protected:
-    int n;
-  };
-
-  class overridden : public delegate {
-  public:
-    overridden(int n): delegate(n) {}
-    virtual int getval() override final { return this->n * 2; }
-  };
-
-  class nocopy {
-  public:
-    nocopy(int i): i(i) {}
-    nocopy() = default;
-    nocopy(const nocopy&) = delete;
-    nocopy & operator=(const nocopy&) = delete;
-  private:
-    int i;
-  };
-}
-]])# _AC_CXX_CXX11_TEST_HEADER
-
-# _AC_CXX_CXX11_TEST_BODY
-# -----------------------
-# A C++ body suitable for testing for CXX11, assuming the corresponding header.
-AC_DEFUN([_AC_CXX_CXX11_TEST_BODY],
-[[
-{
-  // Test auto and decltype
-  std::deque<int> d;
-  d.push_front(43);
-  d.push_front(484);
-  d.push_front(3);
-  d.push_front(844);
-  int total = 0;
-  for (auto i = d.begin(); i != d.end(); ++i) { total += *i; }
-
-  auto a1 = 6538;
-  auto a2 = 48573953.4;
-  auto a3 = "String literal";
-
-  decltype(a2) a4 = 34895.034;
-}
-{
-  // Test constexpr
-  short sa[cxx11test::get_val()] = { 0 };
-}
-{
-  // Test initializer lists
-  cxx11test::testinit il = { 4323, 435234.23544 };
-}
-{
-  // Test range-based for and lambda
-  cxx11test::int_array array = {9, 7, 13, 15, 4, 18, 12, 10, 5, 3, 14, 19, 17, 8, 6, 20, 16, 2, 11, 1};
-  for (int &x : array) { x += 23; }
-  std::for_each(array.begin(), array.end(), [](int v1){ std::cout << v1; });
-}
-{
-  using cxx11test::sptr;
-  using cxx11test::wptr;
-
-  sptr sp(new std::string("ASCII string"));
-  wptr wp(sp);
-  sptr sp2(wp);
-}
-{
-  cxx11test::tp tuple("test", 54, 45.53434);
-  double d = std::get<2>(tuple);
-  std::string s;
-  int i;
-  std::tie(s,i,d) = tuple;
-}
-{
-  static std::regex filename_regex("^_?([a-z0-9_.]+-)+[a-z0-9]+$");
-  std::string testmatch("Test if this string matches");
-  bool match = std::regex_search(testmatch, filename_regex);
-}
-{
-  cxx11test::int_array array = {9, 7, 13, 15, 4, 18, 12, 10, 5, 3, 14, 19, 17, 8, 6, 20, 16, 2, 11, 1};
-  cxx11test::int_array::size_type size = array.size();
-}
-{
-  // Test constructor delegation
-  cxx11test::delegate d1;
-  cxx11test::delegate d2();
-  cxx11test::delegate d3(45);
-}
-{
-  // Test override and final
-  cxx11test::overridden o1(55464);
-}
-{
-  // Test nullptr
-  char *c = nullptr;
-}
-{
-  // Test template brackets
-  std::vector<std::pair<int,char*>> v1;
-}
-{
-  // Unicode literals
-  char const *utf8 = u8"UTF-8 string \u2500";
-  char16_t const *utf16 = u"UTF-8 string \u2500";
-  char32_t const *utf32 = U"UTF-32 string \u2500";
-}
-]])
-
-# _AC_PROG_CXX_CXX98 ([ACTION-IF-AVAILABLE], [ACTION-IF-UNAVAILABLE])
-# -------------------------------------------------------------------
-
-# If the C++ compiler is not in ISO C++98 mode by default, try to add
-# an option to output variable CXX to make it so.  This macro tries
-# various options that select ISO C++98 on some system or another.  It
-# considers the compiler to be in ISO C++98 mode if it handles basic
-# features of the std namespace including: string, containers (list,
-# map, set, vector), streams (fstreams, iostreams, stringstreams,
-# iomanip), pair, exceptions and algorithms.
-
-
-AC_DEFUN([_AC_PROG_CXX_CXX98],
-[_AC_CXX_STD_TRY([cxx98],
-[_AC_CXX_CXX98_TEST_HEADER],
-[_AC_CXX_CXX98_TEST_BODY],
-dnl Try
-dnl GCC		-std=gnu++98 (unused restrictive mode: -std=c++98)
-dnl IBM XL C	-qlanglvl=extended
-dnl HP aC++	-AA
-dnl Intel ICC	-std=gnu++98
-dnl Solaris	N/A (default)
-dnl Tru64	N/A (default, but -std gnu could be used)
-dnl with extended modes being tried first.
-[[-std=gnu++98 -std=c++98 -qlanglvl=extended -AA]], [$1], [$2])[]dnl
-])# _AC_PROG_CXX_CXX98
-
-# _AC_PROG_CXX_CXX11 ([ACTION-IF-AVAILABLE], [ACTION-IF-UNAVAILABLE])
-# -------------------------------------------------------------------
-# If the C++ compiler is not in ISO CXX11 mode by default, try to add
-# an option to output variable CXX to make it so.  This macro tries
-# various options that select ISO C++11 on some system or another.  It
-# considers the compiler to be in ISO C++11 mode if it handles all the
-# tests from the C++98 checks, plus the following: Language features
-# (auto, constexpr, decltype, default/deleted constructors, delegate
-# constructors, final, initializer lists, lambda functions, nullptr,
-# override, range-based for loops, template brackets without spaces,
-# unicode literals) and library features (array, memory (shared_ptr,
-# weak_ptr), regex and tuple types).
-AC_DEFUN([_AC_PROG_CXX_CXX11],
-[_AC_CXX_STD_TRY([cxx11],
-[_AC_CXX_CXX11_TEST_HEADER
-_AC_CXX_CXX98_TEST_HEADER],
-[_AC_CXX_CXX11_TEST_BODY
-_AC_CXX_CXX98_TEST_BODY],
-dnl Try
-dnl GCC		-std=gnu++11 (unused restrictive mode: -std=c++11) [and 0x variants]
-dnl IBM XL C	-qlanglvl=extended0x
-dnl		(pre-V12.1; unused restrictive mode: -qlanglvl=stdcxx11)
-dnl HP aC++	-AA
-dnl Intel ICC	-std=c++11 -std=c++0x
-dnl Solaris	N/A (no support)
-dnl Tru64	N/A (no support)
-dnl with extended modes being tried first.
-[[-std=gnu++11 -std=c++11 -std=gnu++0x -std=c++0x -qlanglvl=extended0x -AA]], [$1], [$2])[]dnl
-])# _AC_PROG_CXX_CXX11
diff --git a/m4/stdalign.m4 b/m4/stdalign.m4
index 601fd21..dcf778e 100644
--- a/m4/stdalign.m4
+++ b/m4/stdalign.m4
@@ -1,6 +1,6 @@
 # Check for stdalign.h that conforms to C11.
 
-dnl Copyright 2011-2019 Free Software Foundation, Inc.
+dnl Copyright 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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/stdbool.m4 b/m4/stdbool.m4
index acb8522..6bb087e 100644
--- a/m4/stdbool.m4
+++ b/m4/stdbool.m4
@@ -1,22 +1,36 @@
 # Check for stdbool.h that conforms to C99.
 
-dnl Copyright (C) 2002-2006, 2009-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2002-2006, 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.
 
-#serial 7
+#serial 8
 
 # Prepare for substituting <stdbool.h> if it is not supported.
 
 AC_DEFUN([AM_STDBOOL_H],
 [
   AC_REQUIRE([AC_CHECK_HEADER_STDBOOL])
+  AC_REQUIRE([AC_CANONICAL_HOST])
 
-  # Define two additional variables used in the Makefile substitution.
-
+  dnl On some platforms, <stdbool.h> does not exist or does not conform to C99.
+  dnl On Solaris 10 with CC=cc CXX=CC, <stdbool.h> exists but is not usable
+  dnl in C++ mode (and no <cstdbool> exists). In this case, we use our
+  dnl replacement, also in C mode (for binary compatibility between C and C++).
   if test "$ac_cv_header_stdbool_h" = yes; then
-    STDBOOL_H=''
+    case "$host_os" in
+      solaris*)
+        if test -z "$GCC"; then
+          STDBOOL_H='stdbool.h'
+        else
+          STDBOOL_H=''
+        fi
+        ;;
+      *)
+        STDBOOL_H=''
+        ;;
+    esac
   else
     STDBOOL_H='stdbool.h'
   fi
diff --git a/m4/stddef_h.m4 b/m4/stddef_h.m4
index 979e3cf..d8bc8ff 100644
--- a/m4/stddef_h.m4
+++ b/m4/stddef_h.m4
@@ -1,6 +1,6 @@
 dnl A placeholder for <stddef.h>, for platforms that have issues.
-# stddef_h.m4 serial 6
-dnl Copyright (C) 2009-2019 Free Software Foundation, Inc.
+# stddef_h.m4 serial 7
+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.
@@ -19,7 +19,7 @@ AC_DEFUN([gl_STDDEF_H],
        [AC_LANG_PROGRAM(
           [[#include <stddef.h>
             unsigned int s = sizeof (max_align_t);
-            #if defined __GNUC__ || defined __IBM__ALIGNOF__
+            #if defined __GNUC__ || defined __clang__ || defined __IBM__ALIGNOF__
             int check1[2 * (__alignof__ (double) <= __alignof__ (max_align_t)) - 1];
             int check2[2 * (__alignof__ (long double) <= __alignof__ (max_align_t)) - 1];
             #endif
diff --git a/m4/stdint.m4 b/m4/stdint.m4
index 11d8e8e..adaea3e 100644
--- a/m4/stdint.m4
+++ b/m4/stdint.m4
@@ -1,5 +1,5 @@
-# stdint.m4 serial 53
-dnl Copyright (C) 2001-2019 Free Software Foundation, Inc.
+# stdint.m4 serial 58
+dnl Copyright (C) 2001-2020 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.
@@ -17,21 +17,12 @@ AC_DEFUN_ONCE([gl_STDINT_H],
   AC_REQUIRE([gl_LIMITS_H])
   AC_REQUIRE([gt_TYPE_WINT_T])
 
-  dnl Check for long long int and unsigned long long int.
-  AC_REQUIRE([AC_TYPE_LONG_LONG_INT])
-  if test $ac_cv_type_long_long_int = yes; then
-    HAVE_LONG_LONG_INT=1
-  else
-    HAVE_LONG_LONG_INT=0
-  fi
-  AC_SUBST([HAVE_LONG_LONG_INT])
-  AC_REQUIRE([AC_TYPE_UNSIGNED_LONG_LONG_INT])
-  if test $ac_cv_type_unsigned_long_long_int = yes; then
-    HAVE_UNSIGNED_LONG_LONG_INT=1
-  else
-    HAVE_UNSIGNED_LONG_LONG_INT=0
-  fi
-  AC_SUBST([HAVE_UNSIGNED_LONG_LONG_INT])
+  dnl For backward compatibility. Some packages may still be testing these
+  dnl macros.
+  AC_DEFINE([HAVE_LONG_LONG_INT], [1],
+    [Define to 1 if the system has the type 'long long int'.])
+  AC_DEFINE([HAVE_UNSIGNED_LONG_LONG_INT], [1],
+    [Define to 1 if the system has the type 'unsigned long long int'.])
 
   dnl Check for <wchar.h>, in the same way as gl_WCHAR_H does.
   AC_CHECK_HEADERS_ONCE([wchar.h])
@@ -43,7 +34,7 @@ AC_DEFUN_ONCE([gl_STDINT_H],
   AC_SUBST([HAVE_WCHAR_H])
 
   dnl Check for <inttypes.h>.
-  dnl AC_INCLUDES_DEFAULT defines $ac_cv_header_inttypes_h.
+  AC_CHECK_HEADERS_ONCE([inttypes.h])
   if test $ac_cv_header_inttypes_h = yes; then
     HAVE_INTTYPES_H=1
   else
@@ -52,7 +43,7 @@ AC_DEFUN_ONCE([gl_STDINT_H],
   AC_SUBST([HAVE_INTTYPES_H])
 
   dnl Check for <sys/types.h>.
-  dnl AC_INCLUDES_DEFAULT defines $ac_cv_header_sys_types_h.
+  AC_CHECK_HEADERS_ONCE([sys/types.h])
   if test $ac_cv_header_sys_types_h = yes; then
     HAVE_SYS_TYPES_H=1
   else
@@ -161,7 +152,7 @@ uintmax_t j = UINTMAX_MAX;
 /* Check that SIZE_MAX has the correct type, if possible.  */
 #if 201112 <= __STDC_VERSION__
 int k = _Generic (SIZE_MAX, size_t: 0);
-#elif (2 <= __GNUC__ || defined __IBM__TYPEOF__ \
+#elif (2 <= __GNUC__ || 4 <= __clang_major__ || defined __IBM__TYPEOF__ \
        || (0x5110 <= __SUNPRO_C && !__STDC__))
 extern size_t k;
 extern __typeof__ (SIZE_MAX) k;
@@ -311,9 +302,10 @@ static const char *macro_values[] =
       HAVE_C99_STDINT_H=1
       dnl Now see whether the system <stdint.h> works without
       dnl __STDC_CONSTANT_MACROS/__STDC_LIMIT_MACROS defined.
-      AC_CACHE_CHECK([whether stdint.h predates C++11],
-        [gl_cv_header_stdint_predates_cxx11_h],
-        [gl_cv_header_stdint_predates_cxx11_h=yes
+      dnl If not, there would be problems when stdint.h is included from C++.
+      AC_CACHE_CHECK([whether stdint.h works without ISO C predefines],
+        [gl_cv_header_stdint_without_STDC_macros],
+        [gl_cv_header_stdint_without_STDC_macros=no
          AC_COMPILE_IFELSE([
            AC_LANG_PROGRAM([[
 #define _GL_JUST_INCLUDE_SYSTEM_STDINT_H 1 /* work if build isn't clean */
@@ -324,13 +316,14 @@ gl_STDINT_INCLUDES
 intmax_t im = INTMAX_MAX;
 int32_t i32 = INT32_C (0x7fffffff);
            ]])],
-           [gl_cv_header_stdint_predates_cxx11_h=no])])
+           [gl_cv_header_stdint_without_STDC_macros=yes])
+        ])
 
-      if test "$gl_cv_header_stdint_predates_cxx11_h" = yes; then
+      if test $gl_cv_header_stdint_without_STDC_macros = no; then
         AC_DEFINE([__STDC_CONSTANT_MACROS], [1],
-                  [Define to 1 if the system <stdint.h> predates C++11.])
+          [Define to 1 if the system <stdint.h> predates C++11.])
         AC_DEFINE([__STDC_LIMIT_MACROS], [1],
-                  [Define to 1 if the system <stdint.h> predates C++11.])
+          [Define to 1 if the system <stdint.h> predates C++11.])
       fi
       AC_CACHE_CHECK([whether stdint.h has UINTMAX_WIDTH etc.],
         [gl_cv_header_stdint_width],
@@ -500,13 +493,9 @@ AC_DEFUN([gl_INTEGER_TYPE_SUFFIX],
 dnl gl_STDINT_INCLUDES
 AC_DEFUN([gl_STDINT_INCLUDES],
 [[
-  /* BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be
-     included before <wchar.h>.  */
   #include <stddef.h>
   #include <signal.h>
   #if HAVE_WCHAR_H
-  # include <stdio.h>
-  # include <time.h>
   # include <wchar.h>
   #endif
 ]])
diff --git a/m4/stdint_h.m4 b/m4/stdint_h.m4
index 6d5f1af..9df9e04 100644
--- a/m4/stdint_h.m4
+++ b/m4/stdint_h.m4
@@ -1,5 +1,5 @@
 # stdint_h.m4 serial 9
-dnl Copyright (C) 1997-2004, 2006, 2008-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 1997-2004, 2006, 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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/stdio_h.m4 b/m4/stdio_h.m4
index 6c9c104..54026c3 100644
--- a/m4/stdio_h.m4
+++ b/m4/stdio_h.m4
@@ -1,5 +1,5 @@
-# stdio_h.m4 serial 49
-dnl Copyright (C) 2007-2019 Free Software Foundation, Inc.
+# stdio_h.m4 serial 52
+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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -107,6 +107,13 @@ AC_DEFUN([gl_STDIO_H],
   gl_WARN_ON_USE_PREPARE([[#include <stdio.h>
     ]], [dprintf fpurge fseeko ftello getdelim getline gets pclose popen
     renameat snprintf tmpfile vdprintf vsnprintf])
+
+  AC_REQUIRE([AC_C_RESTRICT])
+
+  AC_CHECK_DECLS_ONCE([fcloseall])
+  if test $ac_cv_have_decl_fcloseall = no; then
+    HAVE_DECL_FCLOSEALL=0
+  fi
 ])
 
 AC_DEFUN([gl_STDIO_MODULE_INDICATOR],
@@ -173,7 +180,15 @@ AC_DEFUN([gl_STDIO_H_DEFAULTS],
   GNULIB_VPRINTF_POSIX=0;        AC_SUBST([GNULIB_VPRINTF_POSIX])
   GNULIB_VSNPRINTF=0;            AC_SUBST([GNULIB_VSNPRINTF])
   GNULIB_VSPRINTF_POSIX=0;       AC_SUBST([GNULIB_VSPRINTF_POSIX])
+  dnl Support Microsoft deprecated alias function names by default.
+  GNULIB_MDA_FCLOSEALL=1;        AC_SUBST([GNULIB_MDA_FCLOSEALL])
+  GNULIB_MDA_FDOPEN=1;           AC_SUBST([GNULIB_MDA_FDOPEN])
+  GNULIB_MDA_FILENO=1;           AC_SUBST([GNULIB_MDA_FILENO])
+  GNULIB_MDA_GETW=1;             AC_SUBST([GNULIB_MDA_GETW])
+  GNULIB_MDA_PUTW=1;             AC_SUBST([GNULIB_MDA_PUTW])
+  GNULIB_MDA_TEMPNAM=1;          AC_SUBST([GNULIB_MDA_TEMPNAM])
   dnl Assume proper GNU behavior unless another module says otherwise.
+  HAVE_DECL_FCLOSEALL=1;         AC_SUBST([HAVE_DECL_FCLOSEALL])
   HAVE_DECL_FPURGE=1;            AC_SUBST([HAVE_DECL_FPURGE])
   HAVE_DECL_FSEEKO=1;            AC_SUBST([HAVE_DECL_FSEEKO])
   HAVE_DECL_FTELLO=1;            AC_SUBST([HAVE_DECL_FTELLO])
diff --git a/m4/stdlib_h.m4 b/m4/stdlib_h.m4
index 6121602..49d4eba 100644
--- a/m4/stdlib_h.m4
+++ b/m4/stdlib_h.m4
@@ -1,5 +1,5 @@
-# stdlib_h.m4 serial 48
-dnl Copyright (C) 2007-2019 Free Software Foundation, Inc.
+# stdlib_h.m4 serial 55
+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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -22,11 +22,28 @@ AC_DEFUN([gl_STDLIB_H],
 #if HAVE_RANDOM_H
 # include <random.h>
 #endif
-    ]], [_Exit atoll canonicalize_file_name getloadavg getsubopt grantpt
+    ]], [_Exit aligned_alloc atoll canonicalize_file_name free
+    getloadavg getsubopt grantpt
     initstate initstate_r mbtowc mkdtemp mkostemp mkostemps mkstemp mkstemps
-    posix_openpt ptsname ptsname_r qsort_r random random_r reallocarray
-    realpath rpmatch secure_getenv setenv setstate setstate_r srandom
-    srandom_r strtod strtold strtoll strtoull unlockpt unsetenv])
+    posix_memalign posix_openpt ptsname ptsname_r qsort_r
+    random random_r reallocarray realpath rpmatch secure_getenv setenv
+    setstate setstate_r srandom srandom_r
+    strtod strtold strtoll strtoull unlockpt unsetenv])
+
+  AC_REQUIRE([AC_C_RESTRICT])
+
+  AC_CHECK_DECLS_ONCE([ecvt])
+  if test $ac_cv_have_decl_ecvt = no; then
+    HAVE_DECL_ECVT=0
+  fi
+  AC_CHECK_DECLS_ONCE([fcvt])
+  if test $ac_cv_have_decl_fcvt = no; then
+    HAVE_DECL_FCVT=0
+  fi
+  AC_CHECK_DECLS_ONCE([gcvt])
+  if test $ac_cv_have_decl_gcvt = no; then
+    HAVE_DECL_GCVT=0
+  fi
 ])
 
 AC_DEFUN([gl_STDLIB_MODULE_INDICATOR],
@@ -41,9 +58,11 @@ AC_DEFUN([gl_STDLIB_MODULE_INDICATOR],
 AC_DEFUN([gl_STDLIB_H_DEFAULTS],
 [
   GNULIB__EXIT=0;         AC_SUBST([GNULIB__EXIT])
+  GNULIB_ALIGNED_ALLOC=0; AC_SUBST([GNULIB_ALIGNED_ALLOC])
   GNULIB_ATOLL=0;         AC_SUBST([GNULIB_ATOLL])
   GNULIB_CALLOC_POSIX=0;  AC_SUBST([GNULIB_CALLOC_POSIX])
   GNULIB_CANONICALIZE_FILE_NAME=0;  AC_SUBST([GNULIB_CANONICALIZE_FILE_NAME])
+  GNULIB_FREE_POSIX=0;    AC_SUBST([GNULIB_FREE_POSIX])
   GNULIB_GETLOADAVG=0;    AC_SUBST([GNULIB_GETLOADAVG])
   GNULIB_GETSUBOPT=0;     AC_SUBST([GNULIB_GETSUBOPT])
   GNULIB_GRANTPT=0;       AC_SUBST([GNULIB_GRANTPT])
@@ -54,6 +73,7 @@ AC_DEFUN([gl_STDLIB_H_DEFAULTS],
   GNULIB_MKOSTEMPS=0;     AC_SUBST([GNULIB_MKOSTEMPS])
   GNULIB_MKSTEMP=0;       AC_SUBST([GNULIB_MKSTEMP])
   GNULIB_MKSTEMPS=0;      AC_SUBST([GNULIB_MKSTEMPS])
+  GNULIB_POSIX_MEMALIGN=0;AC_SUBST([GNULIB_POSIX_MEMALIGN])
   GNULIB_POSIX_OPENPT=0;  AC_SUBST([GNULIB_POSIX_OPENPT])
   GNULIB_PTSNAME=0;       AC_SUBST([GNULIB_PTSNAME])
   GNULIB_PTSNAME_R=0;     AC_SUBST([GNULIB_PTSNAME_R])
@@ -75,10 +95,20 @@ AC_DEFUN([gl_STDLIB_H_DEFAULTS],
   GNULIB_UNLOCKPT=0;      AC_SUBST([GNULIB_UNLOCKPT])
   GNULIB_UNSETENV=0;      AC_SUBST([GNULIB_UNSETENV])
   GNULIB_WCTOMB=0;        AC_SUBST([GNULIB_WCTOMB])
+  dnl Support Microsoft deprecated alias function names by default.
+  GNULIB_MDA_ECVT=1;      AC_SUBST([GNULIB_MDA_ECVT])
+  GNULIB_MDA_FCVT=1;      AC_SUBST([GNULIB_MDA_FCVT])
+  GNULIB_MDA_GCVT=1;      AC_SUBST([GNULIB_MDA_GCVT])
+  GNULIB_MDA_MKTEMP=1;    AC_SUBST([GNULIB_MDA_MKTEMP])
+  GNULIB_MDA_PUTENV=1;    AC_SUBST([GNULIB_MDA_PUTENV])
   dnl Assume proper GNU behavior unless another module says otherwise.
   HAVE__EXIT=1;              AC_SUBST([HAVE__EXIT])
+  HAVE_ALIGNED_ALLOC=1;      AC_SUBST([HAVE_ALIGNED_ALLOC])
   HAVE_ATOLL=1;              AC_SUBST([HAVE_ATOLL])
   HAVE_CANONICALIZE_FILE_NAME=1;  AC_SUBST([HAVE_CANONICALIZE_FILE_NAME])
+  HAVE_DECL_ECVT=1;          AC_SUBST([HAVE_DECL_ECVT])
+  HAVE_DECL_FCVT=1;          AC_SUBST([HAVE_DECL_FCVT])
+  HAVE_DECL_GCVT=1;          AC_SUBST([HAVE_DECL_GCVT])
   HAVE_DECL_GETLOADAVG=1;    AC_SUBST([HAVE_DECL_GETLOADAVG])
   HAVE_GETSUBOPT=1;          AC_SUBST([HAVE_GETSUBOPT])
   HAVE_GRANTPT=1;            AC_SUBST([HAVE_GRANTPT])
@@ -90,6 +120,7 @@ AC_DEFUN([gl_STDLIB_H_DEFAULTS],
   HAVE_MKOSTEMPS=1;          AC_SUBST([HAVE_MKOSTEMPS])
   HAVE_MKSTEMP=1;            AC_SUBST([HAVE_MKSTEMP])
   HAVE_MKSTEMPS=1;           AC_SUBST([HAVE_MKSTEMPS])
+  HAVE_POSIX_MEMALIGN=1;     AC_SUBST([HAVE_POSIX_MEMALIGN])
   HAVE_POSIX_OPENPT=1;       AC_SUBST([HAVE_POSIX_OPENPT])
   HAVE_PTSNAME=1;            AC_SUBST([HAVE_PTSNAME])
   HAVE_PTSNAME_R=1;          AC_SUBST([HAVE_PTSNAME_R])
@@ -113,12 +144,15 @@ AC_DEFUN([gl_STDLIB_H_DEFAULTS],
   HAVE_SYS_LOADAVG_H=0;      AC_SUBST([HAVE_SYS_LOADAVG_H])
   HAVE_UNLOCKPT=1;           AC_SUBST([HAVE_UNLOCKPT])
   HAVE_DECL_UNSETENV=1;      AC_SUBST([HAVE_DECL_UNSETENV])
+  REPLACE_ALIGNED_ALLOC=0;   AC_SUBST([REPLACE_ALIGNED_ALLOC])
   REPLACE_CALLOC=0;          AC_SUBST([REPLACE_CALLOC])
   REPLACE_CANONICALIZE_FILE_NAME=0;  AC_SUBST([REPLACE_CANONICALIZE_FILE_NAME])
+  REPLACE_FREE=0;            AC_SUBST([REPLACE_FREE])
   REPLACE_INITSTATE=0;       AC_SUBST([REPLACE_INITSTATE])
   REPLACE_MALLOC=0;          AC_SUBST([REPLACE_MALLOC])
   REPLACE_MBTOWC=0;          AC_SUBST([REPLACE_MBTOWC])
   REPLACE_MKSTEMP=0;         AC_SUBST([REPLACE_MKSTEMP])
+  REPLACE_POSIX_MEMALIGN=0;  AC_SUBST([REPLACE_POSIX_MEMALIGN])
   REPLACE_PTSNAME=0;         AC_SUBST([REPLACE_PTSNAME])
   REPLACE_PTSNAME_R=0;       AC_SUBST([REPLACE_PTSNAME_R])
   REPLACE_PUTENV=0;          AC_SUBST([REPLACE_PUTENV])
diff --git a/m4/stpcpy.m4 b/m4/stpcpy.m4
new file mode 100644
index 0000000..0f0fa9e
--- /dev/null
+++ b/m4/stpcpy.m4
@@ -0,0 +1,25 @@
+# stpcpy.m4 serial 8
+dnl Copyright (C) 2002, 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,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_FUNC_STPCPY],
+[
+  dnl Persuade glibc <string.h> to declare stpcpy().
+  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
+
+  dnl The stpcpy() declaration in lib/string.in.h uses 'restrict'.
+  AC_REQUIRE([AC_C_RESTRICT])
+
+  AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
+  AC_CHECK_FUNCS([stpcpy])
+  if test $ac_cv_func_stpcpy = no; then
+    HAVE_STPCPY=0
+  fi
+])
+
+# Prerequisites of lib/stpcpy.c.
+AC_DEFUN([gl_PREREQ_STPCPY], [
+  :
+])
diff --git a/m4/strcase.m4 b/m4/strcase.m4
index 9baef78..21d80c8 100644
--- a/m4/strcase.m4
+++ b/m4/strcase.m4
@@ -1,5 +1,5 @@
 # strcase.m4 serial 11
-dnl Copyright (C) 2002, 2005-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2002, 2005-2020 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.
diff --git a/m4/strchrnul.m4 b/m4/strchrnul.m4
index 93cf112..a18f093 100644
--- a/m4/strchrnul.m4
+++ b/m4/strchrnul.m4
@@ -1,5 +1,5 @@
 # strchrnul.m4 serial 9
-dnl Copyright (C) 2003, 2007, 2009-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2003, 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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/strdup.m4 b/m4/strdup.m4
index 82d7420..6340209 100644
--- a/m4/strdup.m4
+++ b/m4/strdup.m4
@@ -1,6 +1,6 @@
-# strdup.m4 serial 13
+# strdup.m4 serial 14
 
-dnl Copyright (C) 2002-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2002-2020 Free Software Foundation, Inc.
 
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -9,7 +9,6 @@ dnl with or without modifications, as long as this notice is preserved.
 AC_DEFUN([gl_FUNC_STRDUP],
 [
   AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
-  AC_CHECK_FUNCS_ONCE([strdup])
   AC_CHECK_DECLS_ONCE([strdup])
   if test $ac_cv_have_decl_strdup = no; then
     HAVE_DECL_STRDUP=0
@@ -20,11 +19,8 @@ AC_DEFUN([gl_FUNC_STRDUP_POSIX],
 [
   AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
   AC_REQUIRE([gl_CHECK_MALLOC_POSIX])
-  AC_CHECK_FUNCS_ONCE([strdup])
-  if test $ac_cv_func_strdup = yes; then
-    if test $gl_cv_func_malloc_posix != yes; then
-      REPLACE_STRDUP=1
-    fi
+  if test $gl_cv_func_malloc_posix != yes; then
+    REPLACE_STRDUP=1
   fi
   AC_CHECK_DECLS_ONCE([strdup])
   if test $ac_cv_have_decl_strdup = no; then
diff --git a/m4/strerror.m4 b/m4/strerror.m4
index 2c90f31..fd84ce8 100644
--- a/m4/strerror.m4
+++ b/m4/strerror.m4
@@ -1,5 +1,5 @@
-# strerror.m4 serial 20
-dnl Copyright (C) 2002, 2007-2019 Free Software Foundation, Inc.
+# strerror.m4 serial 21
+dnl Copyright (C) 2002, 2007-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
@@ -28,8 +28,8 @@ AC_DEFUN([gl_FUNC_STRERROR],
            *-gnu* | gnu*) gl_cv_func_working_strerror="guessing yes" ;;
                           # Guess yes on musl systems.
            *-musl*)       gl_cv_func_working_strerror="guessing yes" ;;
-                          # If we don't know, assume the worst.
-           *)             gl_cv_func_working_strerror="guessing no" ;;
+                          # If we don't know, obey --enable-cross-guesses.
+           *)             gl_cv_func_working_strerror="$gl_cross_guess_normal" ;;
          esac
         ])
     ])
@@ -86,8 +86,8 @@ AC_DEFUN([gl_FUNC_STRERROR_0],
          *-musl*)       gl_cv_func_strerror_0_works="guessing yes" ;;
                         # Guess yes on native Windows.
          mingw*)        gl_cv_func_strerror_0_works="guessing yes" ;;
-                        # If we don't know, assume the worst.
-         *)             gl_cv_func_strerror_0_works="guessing no" ;;
+                        # If we don't know, obey --enable-cross-guesses.
+         *)             gl_cv_func_strerror_0_works="$gl_cross_guess_normal" ;;
        esac
       ])
   ])
diff --git a/m4/strerror_r.m4 b/m4/strerror_r.m4
index dafc46d..d431f23 100644
--- a/m4/strerror_r.m4
+++ b/m4/strerror_r.m4
@@ -1,5 +1,5 @@
-# strerror_r.m4 serial 19
-dnl Copyright (C) 2002, 2007-2019 Free Software Foundation, Inc.
+# strerror_r.m4 serial 20
+dnl Copyright (C) 2002, 2007-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
@@ -163,7 +163,7 @@ changequote([,])dnl
                [gl_cv_func_strerror_r_works=no],
                [dnl Guess no on all platforms that have __xpg_strerror_r,
                 dnl at least until fixed glibc and cygwin are more common.
-                gl_cv_func_strerror_r_works="guessing no"
+                gl_cv_func_strerror_r_works="$gl_cross_guess_normal"
                ])
             ])
         fi
diff --git a/m4/string_h.m4 b/m4/string_h.m4
index 0c0e3a7..3d41c63 100644
--- a/m4/string_h.m4
+++ b/m4/string_h.m4
@@ -1,11 +1,11 @@
 # Configure a GNU-like replacement for <string.h>.
 
-# Copyright (C) 2007-2019 Free Software Foundation, Inc.
+# Copyright (C) 2007-2020 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.
 
-# serial 22
+# serial 28
 
 # Written by Paul Eggert.
 
@@ -18,7 +18,6 @@ AC_DEFUN([gl_HEADER_STRING_H],
 
 AC_DEFUN([gl_HEADER_STRING_H_BODY],
 [
-  AC_REQUIRE([AC_C_RESTRICT])
   AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
   gl_NEXT_HEADERS([string.h])
 
@@ -29,7 +28,9 @@ AC_DEFUN([gl_HEADER_STRING_H_BODY],
     ]],
     [ffsl ffsll memmem mempcpy memrchr rawmemchr stpcpy stpncpy strchrnul
      strdup strncat strndup strnlen strpbrk strsep strcasestr strtok_r
-     strerror_r strsignal strverscmp])
+     strerror_r strerrorname_np sigabbrev_np sigdescr_np strsignal strverscmp])
+
+  AC_REQUIRE([AC_C_RESTRICT])
 ])
 
 AC_DEFUN([gl_STRING_MODULE_INDICATOR],
@@ -43,50 +44,55 @@ AC_DEFUN([gl_STRING_MODULE_INDICATOR],
 
 AC_DEFUN([gl_HEADER_STRING_H_DEFAULTS],
 [
-  GNULIB_EXPLICIT_BZERO=0; AC_SUBST([GNULIB_EXPLICIT_BZERO])
-  GNULIB_FFSL=0;        AC_SUBST([GNULIB_FFSL])
-  GNULIB_FFSLL=0;       AC_SUBST([GNULIB_FFSLL])
-  GNULIB_MEMCHR=0;      AC_SUBST([GNULIB_MEMCHR])
-  GNULIB_MEMMEM=0;      AC_SUBST([GNULIB_MEMMEM])
-  GNULIB_MEMPCPY=0;     AC_SUBST([GNULIB_MEMPCPY])
-  GNULIB_MEMRCHR=0;     AC_SUBST([GNULIB_MEMRCHR])
-  GNULIB_RAWMEMCHR=0;   AC_SUBST([GNULIB_RAWMEMCHR])
-  GNULIB_STPCPY=0;      AC_SUBST([GNULIB_STPCPY])
-  GNULIB_STPNCPY=0;     AC_SUBST([GNULIB_STPNCPY])
-  GNULIB_STRCHRNUL=0;   AC_SUBST([GNULIB_STRCHRNUL])
-  GNULIB_STRDUP=0;      AC_SUBST([GNULIB_STRDUP])
-  GNULIB_STRNCAT=0;     AC_SUBST([GNULIB_STRNCAT])
-  GNULIB_STRNDUP=0;     AC_SUBST([GNULIB_STRNDUP])
-  GNULIB_STRNLEN=0;     AC_SUBST([GNULIB_STRNLEN])
-  GNULIB_STRPBRK=0;     AC_SUBST([GNULIB_STRPBRK])
-  GNULIB_STRSEP=0;      AC_SUBST([GNULIB_STRSEP])
-  GNULIB_STRSTR=0;      AC_SUBST([GNULIB_STRSTR])
-  GNULIB_STRCASESTR=0;  AC_SUBST([GNULIB_STRCASESTR])
-  GNULIB_STRTOK_R=0;    AC_SUBST([GNULIB_STRTOK_R])
-  GNULIB_MBSLEN=0;      AC_SUBST([GNULIB_MBSLEN])
-  GNULIB_MBSNLEN=0;     AC_SUBST([GNULIB_MBSNLEN])
-  GNULIB_MBSCHR=0;      AC_SUBST([GNULIB_MBSCHR])
-  GNULIB_MBSRCHR=0;     AC_SUBST([GNULIB_MBSRCHR])
-  GNULIB_MBSSTR=0;      AC_SUBST([GNULIB_MBSSTR])
-  GNULIB_MBSCASECMP=0;  AC_SUBST([GNULIB_MBSCASECMP])
-  GNULIB_MBSNCASECMP=0; AC_SUBST([GNULIB_MBSNCASECMP])
-  GNULIB_MBSPCASECMP=0; AC_SUBST([GNULIB_MBSPCASECMP])
-  GNULIB_MBSCASESTR=0;  AC_SUBST([GNULIB_MBSCASESTR])
-  GNULIB_MBSCSPN=0;     AC_SUBST([GNULIB_MBSCSPN])
-  GNULIB_MBSPBRK=0;     AC_SUBST([GNULIB_MBSPBRK])
-  GNULIB_MBSSPN=0;      AC_SUBST([GNULIB_MBSSPN])
-  GNULIB_MBSSEP=0;      AC_SUBST([GNULIB_MBSSEP])
-  GNULIB_MBSTOK_R=0;    AC_SUBST([GNULIB_MBSTOK_R])
-  GNULIB_STRERROR=0;    AC_SUBST([GNULIB_STRERROR])
-  GNULIB_STRERROR_R=0;  AC_SUBST([GNULIB_STRERROR_R])
-  GNULIB_STRSIGNAL=0;   AC_SUBST([GNULIB_STRSIGNAL])
-  GNULIB_STRVERSCMP=0;  AC_SUBST([GNULIB_STRVERSCMP])
-  HAVE_MBSLEN=0;        AC_SUBST([HAVE_MBSLEN])
+  GNULIB_EXPLICIT_BZERO=0;   AC_SUBST([GNULIB_EXPLICIT_BZERO])
+  GNULIB_FFSL=0;             AC_SUBST([GNULIB_FFSL])
+  GNULIB_FFSLL=0;            AC_SUBST([GNULIB_FFSLL])
+  GNULIB_MEMCHR=0;           AC_SUBST([GNULIB_MEMCHR])
+  GNULIB_MEMMEM=0;           AC_SUBST([GNULIB_MEMMEM])
+  GNULIB_MEMPCPY=0;          AC_SUBST([GNULIB_MEMPCPY])
+  GNULIB_MEMRCHR=0;          AC_SUBST([GNULIB_MEMRCHR])
+  GNULIB_RAWMEMCHR=0;        AC_SUBST([GNULIB_RAWMEMCHR])
+  GNULIB_STPCPY=0;           AC_SUBST([GNULIB_STPCPY])
+  GNULIB_STPNCPY=0;          AC_SUBST([GNULIB_STPNCPY])
+  GNULIB_STRCHRNUL=0;        AC_SUBST([GNULIB_STRCHRNUL])
+  GNULIB_STRDUP=0;           AC_SUBST([GNULIB_STRDUP])
+  GNULIB_STRNCAT=0;          AC_SUBST([GNULIB_STRNCAT])
+  GNULIB_STRNDUP=0;          AC_SUBST([GNULIB_STRNDUP])
+  GNULIB_STRNLEN=0;          AC_SUBST([GNULIB_STRNLEN])
+  GNULIB_STRPBRK=0;          AC_SUBST([GNULIB_STRPBRK])
+  GNULIB_STRSEP=0;           AC_SUBST([GNULIB_STRSEP])
+  GNULIB_STRSTR=0;           AC_SUBST([GNULIB_STRSTR])
+  GNULIB_STRCASESTR=0;       AC_SUBST([GNULIB_STRCASESTR])
+  GNULIB_STRTOK_R=0;         AC_SUBST([GNULIB_STRTOK_R])
+  GNULIB_MBSLEN=0;           AC_SUBST([GNULIB_MBSLEN])
+  GNULIB_MBSNLEN=0;          AC_SUBST([GNULIB_MBSNLEN])
+  GNULIB_MBSCHR=0;           AC_SUBST([GNULIB_MBSCHR])
+  GNULIB_MBSRCHR=0;          AC_SUBST([GNULIB_MBSRCHR])
+  GNULIB_MBSSTR=0;           AC_SUBST([GNULIB_MBSSTR])
+  GNULIB_MBSCASECMP=0;       AC_SUBST([GNULIB_MBSCASECMP])
+  GNULIB_MBSNCASECMP=0;      AC_SUBST([GNULIB_MBSNCASECMP])
+  GNULIB_MBSPCASECMP=0;      AC_SUBST([GNULIB_MBSPCASECMP])
+  GNULIB_MBSCASESTR=0;       AC_SUBST([GNULIB_MBSCASESTR])
+  GNULIB_MBSCSPN=0;          AC_SUBST([GNULIB_MBSCSPN])
+  GNULIB_MBSPBRK=0;          AC_SUBST([GNULIB_MBSPBRK])
+  GNULIB_MBSSPN=0;           AC_SUBST([GNULIB_MBSSPN])
+  GNULIB_MBSSEP=0;           AC_SUBST([GNULIB_MBSSEP])
+  GNULIB_MBSTOK_R=0;         AC_SUBST([GNULIB_MBSTOK_R])
+  GNULIB_STRERROR=0;         AC_SUBST([GNULIB_STRERROR])
+  GNULIB_STRERROR_R=0;       AC_SUBST([GNULIB_STRERROR_R])
+  GNULIB_STRERRORNAME_NP=0;  AC_SUBST([GNULIB_STRERRORNAME_NP])
+  GNULIB_SIGABBREV_NP=0;     AC_SUBST([GNULIB_SIGABBREV_NP])
+  GNULIB_SIGDESCR_NP=0;      AC_SUBST([GNULIB_SIGDESCR_NP])
+  GNULIB_STRSIGNAL=0;        AC_SUBST([GNULIB_STRSIGNAL])
+  GNULIB_STRVERSCMP=0;       AC_SUBST([GNULIB_STRVERSCMP])
+  HAVE_MBSLEN=0;             AC_SUBST([HAVE_MBSLEN])
+  dnl Support Microsoft deprecated alias function names by default.
+  GNULIB_MDA_MEMCCPY=1;      AC_SUBST([GNULIB_MDA_MEMCCPY])
+  GNULIB_MDA_STRDUP=1;       AC_SUBST([GNULIB_MDA_STRDUP])
   dnl Assume proper GNU behavior unless another module says otherwise.
   HAVE_EXPLICIT_BZERO=1;        AC_SUBST([HAVE_EXPLICIT_BZERO])
   HAVE_FFSL=1;                  AC_SUBST([HAVE_FFSL])
   HAVE_FFSLL=1;                 AC_SUBST([HAVE_FFSLL])
-  HAVE_MEMCHR=1;                AC_SUBST([HAVE_MEMCHR])
   HAVE_DECL_MEMMEM=1;           AC_SUBST([HAVE_DECL_MEMMEM])
   HAVE_MEMPCPY=1;               AC_SUBST([HAVE_MEMPCPY])
   HAVE_DECL_MEMRCHR=1;          AC_SUBST([HAVE_DECL_MEMRCHR])
@@ -102,6 +108,9 @@ AC_DEFUN([gl_HEADER_STRING_H_DEFAULTS],
   HAVE_STRCASESTR=1;            AC_SUBST([HAVE_STRCASESTR])
   HAVE_DECL_STRTOK_R=1;         AC_SUBST([HAVE_DECL_STRTOK_R])
   HAVE_DECL_STRERROR_R=1;       AC_SUBST([HAVE_DECL_STRERROR_R])
+  HAVE_STRERRORNAME_NP=1;       AC_SUBST([HAVE_STRERRORNAME_NP])
+  HAVE_SIGABBREV_NP=1;          AC_SUBST([HAVE_SIGABBREV_NP])
+  HAVE_SIGDESCR_NP=1;           AC_SUBST([HAVE_SIGDESCR_NP])
   HAVE_DECL_STRSIGNAL=1;        AC_SUBST([HAVE_DECL_STRSIGNAL])
   HAVE_STRVERSCMP=1;            AC_SUBST([HAVE_STRVERSCMP])
   REPLACE_MEMCHR=0;             AC_SUBST([REPLACE_MEMCHR])
@@ -117,6 +126,7 @@ AC_DEFUN([gl_HEADER_STRING_H_DEFAULTS],
   REPLACE_STRTOK_R=0;           AC_SUBST([REPLACE_STRTOK_R])
   REPLACE_STRERROR=0;           AC_SUBST([REPLACE_STRERROR])
   REPLACE_STRERROR_R=0;         AC_SUBST([REPLACE_STRERROR_R])
+  REPLACE_STRERRORNAME_NP=0;    AC_SUBST([REPLACE_STRERRORNAME_NP])
   REPLACE_STRSIGNAL=0;          AC_SUBST([REPLACE_STRSIGNAL])
   UNDEFINE_STRTOK_R=0;          AC_SUBST([UNDEFINE_STRTOK_R])
 ])
diff --git a/m4/strings_h.m4 b/m4/strings_h.m4
index 76128cf..4aadca0 100644
--- a/m4/strings_h.m4
+++ b/m4/strings_h.m4
@@ -1,7 +1,7 @@
 # Configure a replacement for <strings.h>.
 # serial 6
 
-# Copyright (C) 2007, 2009-2019 Free Software Foundation, Inc.
+# Copyright (C) 2007, 2009-2020 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.
diff --git a/m4/strndup.m4 b/m4/strndup.m4
index 325af5d..006a31a 100644
--- a/m4/strndup.m4
+++ b/m4/strndup.m4
@@ -1,5 +1,5 @@
 # strndup.m4 serial 22
-dnl Copyright (C) 2002-2003, 2005-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2002-2003, 2005-2020 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.
diff --git a/m4/strnlen.m4 b/m4/strnlen.m4
index c283c3e..71b8e1b 100644
--- a/m4/strnlen.m4
+++ b/m4/strnlen.m4
@@ -1,5 +1,5 @@
 # strnlen.m4 serial 13
-dnl Copyright (C) 2002-2003, 2005-2007, 2009-2019 Free Software Foundation,
+dnl Copyright (C) 2002-2003, 2005-2007, 2009-2020 Free Software Foundation,
 dnl Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
diff --git a/m4/strpbrk.m4 b/m4/strpbrk.m4
index fa71f1b..7e74337 100644
--- a/m4/strpbrk.m4
+++ b/m4/strpbrk.m4
@@ -1,5 +1,5 @@
 # strpbrk.m4 serial 6
-dnl Copyright (C) 2002-2003, 2007, 2009-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2002-2003, 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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/strptime.m4 b/m4/strptime.m4
index 40d9de1..d4b9290 100644
--- a/m4/strptime.m4
+++ b/m4/strptime.m4
@@ -1,5 +1,5 @@
 # strptime.m4 serial 7
-dnl Copyright (C) 2007, 2009-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/strtok_r.m4 b/m4/strtok_r.m4
index e80daae..2da132c 100644
--- a/m4/strtok_r.m4
+++ b/m4/strtok_r.m4
@@ -1,5 +1,5 @@
 # strtok_r.m4 serial 15
-dnl Copyright (C) 2002-2004, 2006-2007, 2009-2019 Free Software Foundation,
+dnl Copyright (C) 2002-2004, 2006-2007, 2009-2020 Free Software Foundation,
 dnl Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
diff --git a/m4/strtol.m4 b/m4/strtol.m4
index 3ba3b55..eb19ffe 100644
--- a/m4/strtol.m4
+++ b/m4/strtol.m4
@@ -1,5 +1,5 @@
 # strtol.m4 serial 6
-dnl Copyright (C) 2002-2003, 2006, 2009-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2002-2003, 2006, 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.
diff --git a/m4/strtoll.m4 b/m4/strtoll.m4
index 3ba7e22..edcde3b 100644
--- a/m4/strtoll.m4
+++ b/m4/strtoll.m4
@@ -1,5 +1,5 @@
-# strtoll.m4 serial 7
-dnl Copyright (C) 2002, 2004, 2006, 2008-2019 Free Software Foundation, Inc.
+# strtoll.m4 serial 8
+dnl Copyright (C) 2002, 2004, 2006, 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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -7,14 +7,9 @@ dnl with or without modifications, as long as this notice is preserved.
 AC_DEFUN([gl_FUNC_STRTOLL],
 [
   AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
-  dnl We don't need (and can't compile) the replacement strtoll
-  dnl unless the type 'long long int' exists.
-  AC_REQUIRE([AC_TYPE_LONG_LONG_INT])
-  if test "$ac_cv_type_long_long_int" = yes; then
-    AC_CHECK_FUNCS([strtoll])
-    if test $ac_cv_func_strtoll = no; then
-      HAVE_STRTOLL=0
-    fi
+  AC_CHECK_FUNCS([strtoll])
+  if test $ac_cv_func_strtoll = no; then
+    HAVE_STRTOLL=0
   fi
 ])
 
diff --git a/m4/symlink.m4 b/m4/symlink.m4
index 508e94d..9cfdf93 100644
--- a/m4/symlink.m4
+++ b/m4/symlink.m4
@@ -1,7 +1,7 @@
-# serial 8
+# serial 9
 # See if we need to provide symlink replacement.
 
-dnl Copyright (C) 2009-2019 Free Software Foundation, Inc.
+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.
@@ -40,8 +40,8 @@ AC_DEFUN([gl_FUNC_SYMLINK],
             linux-* | linux) gl_cv_func_symlink_works="guessing yes" ;;
                              # Guess yes on glibc systems.
             *-gnu* | gnu*)   gl_cv_func_symlink_works="guessing yes" ;;
-                             # If we don't know, assume the worst.
-            *)               gl_cv_func_symlink_works="guessing no" ;;
+                             # If we don't know, obey --enable-cross-guesses.
+            *)               gl_cv_func_symlink_works="$gl_cross_guess_normal" ;;
           esac
          ])
       rm -f conftest.f conftest.link conftest.lnk2])
diff --git a/m4/sys_file_h.m4 b/m4/sys_file_h.m4
index e30d45e..045e01b 100644
--- a/m4/sys_file_h.m4
+++ b/m4/sys_file_h.m4
@@ -1,7 +1,7 @@
 # Configure a replacement for <sys/file.h>.
 # serial 6
 
-# Copyright (C) 2008-2019 Free Software Foundation, Inc.
+# Copyright (C) 2008-2020 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.
diff --git a/m4/sys_ioctl_h.m4 b/m4/sys_ioctl_h.m4
index 5400421..98d24e8 100644
--- a/m4/sys_ioctl_h.m4
+++ b/m4/sys_ioctl_h.m4
@@ -1,5 +1,5 @@
-# sys_ioctl_h.m4 serial 10
-dnl Copyright (C) 2008-2019 Free Software Foundation, Inc.
+# sys_ioctl_h.m4 serial 12
+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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -22,8 +22,8 @@ AC_DEFUN([gl_SYS_IOCTL_H],
       [dnl We cannot use AC_CHECK_DECL because it produces its own messages.
        AC_COMPILE_IFELSE(
          [AC_LANG_PROGRAM(
-            [AC_INCLUDES_DEFAULT([#include <sys/ioctl.h>])],
-            [(void) ioctl;])],
+            [[#include <sys/ioctl.h>]],
+            [[(void) ioctl;]])],
          [gl_cv_decl_ioctl_in_sys_ioctl_h=yes],
          [gl_cv_decl_ioctl_in_sys_ioctl_h=no])
       ])
diff --git a/m4/sys_random_h.m4 b/m4/sys_random_h.m4
new file mode 100644
index 0000000..8c5d537
--- /dev/null
+++ b/m4/sys_random_h.m4
@@ -0,0 +1,53 @@
+# sys_random_h.m4 serial 5
+dnl Copyright (C) 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_HEADER_SYS_RANDOM],
+[
+  AC_REQUIRE([gl_SYS_RANDOM_H_DEFAULTS])
+  dnl <sys/random.h> is always overridden, because of GNULIB_POSIXCHECK.
+  gl_CHECK_NEXT_HEADERS([sys/random.h])
+  if test $ac_cv_header_sys_random_h = yes; then
+    HAVE_SYS_RANDOM_H=1
+  else
+    HAVE_SYS_RANDOM_H=0
+  fi
+  AC_SUBST([HAVE_SYS_RANDOM_H])
+
+  m4_ifdef([gl_UNISTD_H_DEFAULTS], [AC_REQUIRE([gl_UNISTD_H_DEFAULTS])])
+  if test $ac_cv_header_sys_random_h = yes; then
+    UNISTD_H_HAVE_SYS_RANDOM_H=1
+  fi
+
+  dnl Check for declarations of anything we want to poison if the
+  dnl corresponding gnulib module is not in use.
+  gl_WARN_ON_USE_PREPARE([[
+#if HAVE_SYS_RANDOM_H
+/* Additional includes are needed before <sys/random.h> on uClibc
+   and Mac OS X.  */
+# include <sys/types.h>
+# include <stdlib.h>
+# include <sys/random.h>
+#endif
+    ]],
+    [getrandom])
+])
+
+AC_DEFUN([gl_SYS_RANDOM_MODULE_INDICATOR],
+[
+  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
+  AC_REQUIRE([gl_SYS_RANDOM_H_DEFAULTS])
+  gl_MODULE_INDICATOR_SET_VARIABLE([$1])
+  dnl Define it also as a C macro, for the benefit of the unit tests.
+  gl_MODULE_INDICATOR_FOR_TESTS([$1])
+])
+
+AC_DEFUN([gl_SYS_RANDOM_H_DEFAULTS],
+[
+  GNULIB_GETRANDOM=0;     AC_SUBST([GNULIB_GETRANDOM])
+  dnl Assume proper GNU behavior unless another module says otherwise.
+  HAVE_GETRANDOM=1;       AC_SUBST([HAVE_GETRANDOM])
+  REPLACE_GETRANDOM=0;    AC_SUBST([REPLACE_GETRANDOM])
+])
diff --git a/m4/sys_select_h.m4 b/m4/sys_select_h.m4
index 918212a..fa19bb6 100644
--- a/m4/sys_select_h.m4
+++ b/m4/sys_select_h.m4
@@ -1,5 +1,5 @@
 # sys_select_h.m4 serial 20
-dnl Copyright (C) 2006-2019 Free Software Foundation, Inc.
+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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/sys_socket_h.m4 b/m4/sys_socket_h.m4
index 1ea7b0b..bf902f0 100644
--- a/m4/sys_socket_h.m4
+++ b/m4/sys_socket_h.m4
@@ -1,5 +1,5 @@
-# sys_socket_h.m4 serial 23
-dnl Copyright (C) 2005-2019 Free Software Foundation, Inc.
+# sys_socket_h.m4 serial 25
+dnl Copyright (C) 2005-2020 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.
@@ -95,6 +95,8 @@ AC_DEFUN([gl_HEADER_SYS_SOCKET],
 #include <sys/socket.h>
     ]], [socket connect accept bind getpeername getsockname getsockopt
     listen recv send recvfrom sendto setsockopt shutdown accept4])
+
+  AC_REQUIRE([AC_C_RESTRICT])
 ])
 
 AC_DEFUN([gl_PREREQ_SYS_H_SOCKET],
@@ -104,17 +106,11 @@ AC_DEFUN([gl_PREREQ_SYS_H_SOCKET],
   gl_CHECK_NEXT_HEADERS([sys/socket.h])
   if test $ac_cv_header_sys_socket_h = yes; then
     HAVE_SYS_SOCKET_H=1
-    HAVE_WS2TCPIP_H=0
   else
     HAVE_SYS_SOCKET_H=0
-    if test $ac_cv_header_ws2tcpip_h = yes; then
-      HAVE_WS2TCPIP_H=1
-    else
-      HAVE_WS2TCPIP_H=0
-    fi
   fi
   AC_SUBST([HAVE_SYS_SOCKET_H])
-  AC_SUBST([HAVE_WS2TCPIP_H])
+  gl_PREREQ_SYS_H_WS2TCPIP
 ])
 
 # Common prerequisites of the <sys/socket.h> replacement and of the
@@ -142,6 +138,24 @@ AC_DEFUN([gl_PREREQ_SYS_H_WINSOCK2],
   AC_SUBST([HAVE_WINSOCK2_H])
 ])
 
+# Common prerequisites of the <sys/socket.h> replacement and of the
+# <arpa/inet.h> replacement.
+# Sets and substitutes HAVE_WS2TCPIP_H.
+AC_DEFUN([gl_PREREQ_SYS_H_WS2TCPIP],
+[
+  AC_REQUIRE([gl_CHECK_SOCKET_HEADERS])
+  if test $ac_cv_header_sys_socket_h = yes; then
+    HAVE_WS2TCPIP_H=0
+  else
+    if test $ac_cv_header_ws2tcpip_h = yes; then
+      HAVE_WS2TCPIP_H=1
+    else
+      HAVE_WS2TCPIP_H=0
+    fi
+  fi
+  AC_SUBST([HAVE_WS2TCPIP_H])
+])
+
 AC_DEFUN([gl_SYS_SOCKET_MODULE_INDICATOR],
 [
   dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
diff --git a/m4/sys_stat_h.m4 b/m4/sys_stat_h.m4
index 361ac3f..14b72db 100644
--- a/m4/sys_stat_h.m4
+++ b/m4/sys_stat_h.m4
@@ -1,5 +1,5 @@
-# sys_stat_h.m4 serial 31   -*- Autoconf -*-
-dnl Copyright (C) 2006-2019 Free Software Foundation, Inc.
+# sys_stat_h.m4 serial 36   -*- Autoconf -*-
+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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -46,9 +46,11 @@ AC_DEFUN([gl_HEADER_SYS_STAT_H],
   dnl Check for declarations of anything we want to poison if the
   dnl corresponding gnulib module is not in use.
   gl_WARN_ON_USE_PREPARE([[#include <sys/stat.h>
-    ]], [fchmodat fstat fstatat futimens lchmod lstat mkdirat mkfifo mkfifoat
-    mknod mknodat stat utimensat])
-]) # gl_HEADER_SYS_STAT_H
+    ]], [fchmodat fstat fstatat futimens getumask lchmod lstat
+    mkdirat mkfifo mkfifoat mknod mknodat stat utimensat])
+
+  AC_REQUIRE([AC_C_RESTRICT])
+])
 
 AC_DEFUN([gl_SYS_STAT_MODULE_INDICATOR],
 [
@@ -66,8 +68,10 @@ AC_DEFUN([gl_SYS_STAT_H_DEFAULTS],
   GNULIB_FSTAT=0;       AC_SUBST([GNULIB_FSTAT])
   GNULIB_FSTATAT=0;     AC_SUBST([GNULIB_FSTATAT])
   GNULIB_FUTIMENS=0;    AC_SUBST([GNULIB_FUTIMENS])
+  GNULIB_GETUMASK=0;    AC_SUBST([GNULIB_GETUMASK])
   GNULIB_LCHMOD=0;      AC_SUBST([GNULIB_LCHMOD])
   GNULIB_LSTAT=0;       AC_SUBST([GNULIB_LSTAT])
+  GNULIB_MKDIR=0;       AC_SUBST([GNULIB_MKDIR])
   GNULIB_MKDIRAT=0;     AC_SUBST([GNULIB_MKDIRAT])
   GNULIB_MKFIFO=0;      AC_SUBST([GNULIB_MKFIFO])
   GNULIB_MKFIFOAT=0;    AC_SUBST([GNULIB_MKFIFOAT])
@@ -76,10 +80,15 @@ AC_DEFUN([gl_SYS_STAT_H_DEFAULTS],
   GNULIB_STAT=0;        AC_SUBST([GNULIB_STAT])
   GNULIB_UTIMENSAT=0;   AC_SUBST([GNULIB_UTIMENSAT])
   GNULIB_OVERRIDES_STRUCT_STAT=0; AC_SUBST([GNULIB_OVERRIDES_STRUCT_STAT])
+  dnl Support Microsoft deprecated alias function names by default.
+  GNULIB_MDA_CHMOD=1;   AC_SUBST([GNULIB_MDA_CHMOD])
+  GNULIB_MDA_MKDIR=1;   AC_SUBST([GNULIB_MDA_MKDIR])
+  GNULIB_MDA_UMASK=1;   AC_SUBST([GNULIB_MDA_UMASK])
   dnl Assume proper GNU behavior unless another module says otherwise.
   HAVE_FCHMODAT=1;      AC_SUBST([HAVE_FCHMODAT])
   HAVE_FSTATAT=1;       AC_SUBST([HAVE_FSTATAT])
   HAVE_FUTIMENS=1;      AC_SUBST([HAVE_FUTIMENS])
+  HAVE_GETUMASK=1;      AC_SUBST([HAVE_GETUMASK])
   HAVE_LCHMOD=1;        AC_SUBST([HAVE_LCHMOD])
   HAVE_LSTAT=1;         AC_SUBST([HAVE_LSTAT])
   HAVE_MKDIRAT=1;       AC_SUBST([HAVE_MKDIRAT])
@@ -88,6 +97,7 @@ AC_DEFUN([gl_SYS_STAT_H_DEFAULTS],
   HAVE_MKNOD=1;         AC_SUBST([HAVE_MKNOD])
   HAVE_MKNODAT=1;       AC_SUBST([HAVE_MKNODAT])
   HAVE_UTIMENSAT=1;     AC_SUBST([HAVE_UTIMENSAT])
+  REPLACE_FCHMODAT=0;   AC_SUBST([REPLACE_FCHMODAT])
   REPLACE_FSTAT=0;      AC_SUBST([REPLACE_FSTAT])
   REPLACE_FSTATAT=0;    AC_SUBST([REPLACE_FSTATAT])
   REPLACE_FUTIMENS=0;   AC_SUBST([REPLACE_FUTIMENS])
diff --git a/m4/sys_time_h.m4 b/m4/sys_time_h.m4
index 3d9233a..8fc8599 100644
--- a/m4/sys_time_h.m4
+++ b/m4/sys_time_h.m4
@@ -1,7 +1,7 @@
 # Configure a replacement for <sys/time.h>.
 # serial 9
 
-# Copyright (C) 2007, 2009-2019 Free Software Foundation, Inc.
+# Copyright (C) 2007, 2009-2020 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.
diff --git a/m4/sys_types_h.m4 b/m4/sys_types_h.m4
index be06559..c3a691b 100644
--- a/m4/sys_types_h.m4
+++ b/m4/sys_types_h.m4
@@ -1,5 +1,5 @@
-# sys_types_h.m4 serial 9
-dnl Copyright (C) 2011-2019 Free Software Foundation, Inc.
+# sys_types_h.m4 serial 11
+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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -36,25 +36,23 @@ AC_DEFUN([gl_SYS_TYPES_H_DEFAULTS],
 
 # This works around a buggy version in autoconf <= 2.69.
 # See <https://lists.gnu.org/r/autoconf/2016-08/msg00014.html>
+# The 2.70 version isn't quoted properly, so override it too.
 
-m4_version_prereq([2.70], [], [
-
-# This is taken from the following Autoconf patch:
-# https://git.savannah.gnu.org/cgit/autoconf.git/commit/?id=e17a30e987d7ee695fb4294a82d987ec3dc9b974
+m4_version_prereq([2.70.1], [], [
 
 m4_undefine([AC_HEADER_MAJOR])
 AC_DEFUN([AC_HEADER_MAJOR],
 [AC_CHECK_HEADERS_ONCE([sys/types.h])
 AC_CHECK_HEADER([sys/mkdev.h],
-  [AC_DEFINE([MAJOR_IN_MKDEV], [1],
-    [Define to 1 if `major', `minor', and `makedev' are declared in
-     <mkdev.h>.])])
+                [AC_DEFINE([MAJOR_IN_MKDEV], [1],
+                           [Define to 1 if `major', `minor', and `makedev' are
+                            declared in <mkdev.h>.])])
 if test $ac_cv_header_sys_mkdev_h = no; then
   AC_CHECK_HEADER([sys/sysmacros.h],
-    [AC_DEFINE([MAJOR_IN_SYSMACROS], [1],
-      [Define to 1 if `major', `minor', and `makedev' are declared in
-       <sysmacros.h>.])])
+                  [AC_DEFINE([MAJOR_IN_SYSMACROS], [1],
+                             [Define to 1 if `major', `minor', and `makedev'
+                              are declared in <sysmacros.h>.])])
 fi
-])
+])# AC_HEADER_MAJOR
 
 ])
diff --git a/m4/sys_uio_h.m4 b/m4/sys_uio_h.m4
index 8b8ba6d..a255dea 100644
--- a/m4/sys_uio_h.m4
+++ b/m4/sys_uio_h.m4
@@ -1,5 +1,5 @@
 # sys_uio_h.m4 serial 1
-dnl Copyright (C) 2011-2019 Free Software Foundation, Inc.
+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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/sys_wait_h.m4 b/m4/sys_wait_h.m4
index 6532959..8596d13 100644
--- a/m4/sys_wait_h.m4
+++ b/m4/sys_wait_h.m4
@@ -1,5 +1,5 @@
 # sys_wait_h.m4 serial 6
-dnl Copyright (C) 2008-2019 Free Software Foundation, Inc.
+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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/tempname.m4 b/m4/tempname.m4
index 664a632..da439f0 100644
--- a/m4/tempname.m4
+++ b/m4/tempname.m4
@@ -1,6 +1,6 @@
 #serial 5
 
-# Copyright (C) 2006-2007, 2009-2019 Free Software Foundation, Inc.
+# Copyright (C) 2006-2007, 2009-2020 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.
diff --git a/m4/threadlib.m4 b/m4/threadlib.m4
index bfc3bac..e03c34f 100644
--- a/m4/threadlib.m4
+++ b/m4/threadlib.m4
@@ -1,5 +1,5 @@
-# threadlib.m4 serial 16
-dnl Copyright (C) 2005-2019 Free Software Foundation, Inc.
+# threadlib.m4 serial 29
+dnl Copyright (C) 2005-2020 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.
@@ -8,6 +8,344 @@ dnl From Bruno Haible.
 
 AC_PREREQ([2.60])
 
+dnl The general structure of the multithreading modules in gnulib is that we
+dnl have three set of modules:
+dnl
+dnl   * POSIX API:
+dnl     pthread, which combines
+dnl       pthread-h
+dnl       pthread-thread
+dnl       pthread-once
+dnl       pthread-mutex
+dnl       pthread-rwlock
+dnl       pthread-cond
+dnl       pthread-tss
+dnl       pthread-spin
+dnl     sched_yield
+dnl
+dnl   * ISO C API:
+dnl     threads, which combines
+dnl       threads-h
+dnl       thrd
+dnl       mtx
+dnl       cnd
+dnl       tss
+dnl
+dnl   * Gnulib API, with an implementation that can be chosen at configure
+dnl     time through the option --enable-threads=...
+dnl       thread
+dnl       lock
+dnl       cond
+dnl       tls
+dnl       yield
+dnl
+dnl They are independent, except for the fact that
+dnl   - the implementation of the ISO C API may use the POSIX (or some other
+dnl     platform dependent) API,
+dnl   - the implementation of the Gnulib API may use the POSIX or ISO C or
+dnl     some other platform dependent API, depending on the --enable-threads
+dnl     option.
+dnl
+dnl This file contains macros for all of these APIs!
+
+dnl ============================================================================
+dnl Macros for all thread APIs
+
+AC_DEFUN([gl_ANYTHREADLIB_EARLY],
+[
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  if test -z "$gl_anythreadlib_early_done"; then
+    case "$host_os" in
+      osf*)
+        # On OSF/1, the compiler needs the flag -D_REENTRANT so that it
+        # groks <pthread.h>. cc also understands the flag -pthread, but
+        # we don't use it because 1. gcc-2.95 doesn't understand -pthread,
+        # 2. putting a flag into CPPFLAGS that has an effect on the linker
+        # causes the AC_LINK_IFELSE test below to succeed unexpectedly,
+        # leading to wrong values of LIBTHREAD and LTLIBTHREAD.
+        CPPFLAGS="$CPPFLAGS -D_REENTRANT"
+        ;;
+    esac
+    # Some systems optimize for single-threaded programs by default, and
+    # need special flags to disable these optimizations. For example, the
+    # definition of 'errno' in <errno.h>.
+    case "$host_os" in
+      aix* | freebsd*) CPPFLAGS="$CPPFLAGS -D_THREAD_SAFE" ;;
+      solaris*) CPPFLAGS="$CPPFLAGS -D_REENTRANT" ;;
+    esac
+    gl_anythreadlib_early_done=done
+  fi
+])
+
+dnl Checks whether the compiler and linker support weak declarations of symbols.
+
+AC_DEFUN([gl_WEAK_SYMBOLS],
+[
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  AC_CACHE_CHECK([whether imported symbols can be declared weak],
+    [gl_cv_have_weak],
+    [gl_cv_have_weak=no
+     dnl First, test whether the compiler accepts it syntactically.
+     AC_LINK_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[extern void xyzzy ();
+#pragma weak xyzzy]],
+          [[xyzzy();]])],
+       [gl_cv_have_weak=maybe])
+     if test $gl_cv_have_weak = maybe; then
+       dnl Second, test whether it actually works. On Cygwin 1.7.2, with
+       dnl gcc 4.3, symbols declared weak always evaluate to the address 0.
+       AC_RUN_IFELSE(
+         [AC_LANG_SOURCE([[
+#include <stdio.h>
+#pragma weak fputs
+int main ()
+{
+  return (fputs == NULL);
+}]])],
+         [gl_cv_have_weak=yes],
+         [gl_cv_have_weak=no],
+         [dnl When cross-compiling, assume that only ELF platforms support
+          dnl weak symbols.
+          AC_EGREP_CPP([Extensible Linking Format],
+            [#ifdef __ELF__
+             Extensible Linking Format
+             #endif
+            ],
+            [gl_cv_have_weak="guessing yes"],
+            [gl_cv_have_weak="guessing no"])
+         ])
+     fi
+     dnl But when linking statically, weak symbols don't work.
+     case " $LDFLAGS " in
+       *" -static "*) gl_cv_have_weak=no ;;
+     esac
+     dnl Test for a bug in FreeBSD 11: A link error occurs when using a weak
+     dnl symbol and linking against a shared library that has a dependency on
+     dnl the shared library that defines the symbol.
+     case "$gl_cv_have_weak" in
+       *yes)
+         case "$host_os" in
+           freebsd* | dragonfly*)
+             : > conftest1.c
+             $CC $CPPFLAGS $CFLAGS $LDFLAGS -fPIC -shared -o libempty.so conftest1.c -lpthread >&AS_MESSAGE_LOG_FD 2>&1
+             cat <<EOF > conftest2.c
+#include <pthread.h>
+#pragma weak pthread_mutexattr_gettype
+int main ()
+{
+  return (pthread_mutexattr_gettype != NULL);
+}
+EOF
+             $CC $CPPFLAGS $CFLAGS $LDFLAGS -o conftest conftest2.c libempty.so >&AS_MESSAGE_LOG_FD 2>&1 \
+               || gl_cv_have_weak=no
+             rm -f conftest1.c libempty.so conftest2.c conftest
+             ;;
+         esac
+         ;;
+     esac
+    ])
+  case "$gl_cv_have_weak" in
+    *yes)
+      AC_DEFINE([HAVE_WEAK_SYMBOLS], [1],
+        [Define to 1 if the compiler and linker support weak declarations of symbols.])
+      ;;
+  esac
+])
+
+dnl ============================================================================
+dnl Macros for the POSIX API
+
+dnl gl_PTHREADLIB
+dnl -------------
+dnl Tests for the libraries needs for using the POSIX threads API.
+dnl Sets the variable LIBPTHREAD to the linker options for use in a Makefile.
+dnl Sets the variable LIBPMULTITHREAD, for programs that really need
+dnl multithread functionality. The difference between LIBPTHREAD and
+dnl LIBPMULTITHREAD is that on platforms supporting weak symbols, typically
+dnl LIBPTHREAD is empty whereas LIBPMULTITHREAD is not.
+dnl Sets the variable LIB_SCHED_YIELD to the linker options needed to use the
+dnl sched_yield() function.
+dnl Adds to CPPFLAGS the flag -D_REENTRANT or -D_THREAD_SAFE if needed for
+dnl multithread-safe programs.
+dnl Defines the C macro HAVE_PTHREAD_API if (at least parts of) the POSIX
+dnl threads API is available.
+
+dnl The guts of gl_PTHREADLIB. Needs to be expanded only once.
+
+AC_DEFUN([gl_PTHREADLIB_BODY],
+[
+  AC_REQUIRE([gl_ANYTHREADLIB_EARLY])
+  if test -z "$gl_pthreadlib_body_done"; then
+    gl_pthread_api=no
+    LIBPTHREAD=
+    LIBPMULTITHREAD=
+    # On OSF/1, the compiler needs the flag -pthread or -D_REENTRANT so that
+    # it groks <pthread.h>. It's added above, in gl_ANYTHREADLIB_EARLY.
+    AC_CHECK_HEADER([pthread.h],
+      [gl_have_pthread_h=yes], [gl_have_pthread_h=no])
+    if test "$gl_have_pthread_h" = yes; then
+      # Other possible tests:
+      #   -lpthreads (FSU threads, PCthreads)
+      #   -lgthreads
+      # Test whether both pthread_mutex_lock and pthread_mutexattr_init exist
+      # in libc. IRIX 6.5 has the first one in both libc and libpthread, but
+      # the second one only in libpthread, and lock.c needs it.
+      #
+      # If -pthread works, prefer it to -lpthread, since Ubuntu 14.04
+      # needs -pthread for some reason.  See:
+      # https://lists.gnu.org/r/bug-gnulib/2014-09/msg00023.html
+      save_LIBS=$LIBS
+      for gl_pthread in '' '-pthread'; do
+        LIBS="$LIBS $gl_pthread"
+        AC_LINK_IFELSE(
+          [AC_LANG_PROGRAM(
+             [[#include <pthread.h>
+               pthread_mutex_t m;
+               pthread_mutexattr_t ma;
+             ]],
+             [[pthread_mutex_lock (&m);
+               pthread_mutexattr_init (&ma);]])],
+          [gl_pthread_api=yes
+           LIBPTHREAD=$gl_pthread
+           LIBPMULTITHREAD=$gl_pthread])
+        LIBS=$save_LIBS
+        test $gl_pthread_api = yes && break
+      done
+
+      # Test for libpthread by looking for pthread_kill. (Not pthread_self,
+      # since it is defined as a macro on OSF/1.)
+      if test $gl_pthread_api = yes && test -z "$LIBPTHREAD"; then
+        # The program links fine without libpthread. But it may actually
+        # need to link with libpthread in order to create multiple threads.
+        AC_CHECK_LIB([pthread], [pthread_kill],
+          [LIBPMULTITHREAD=-lpthread
+           # On Solaris and HP-UX, most pthread functions exist also in libc.
+           # Therefore pthread_in_use() needs to actually try to create a
+           # thread: pthread_create from libc will fail, whereas
+           # pthread_create will actually create a thread.
+           # On Solaris 10 or newer, this test is no longer needed, because
+           # libc contains the fully functional pthread functions.
+           case "$host_os" in
+             solaris | solaris2.[1-9] | solaris2.[1-9].* | hpux*)
+               AC_DEFINE([PTHREAD_IN_USE_DETECTION_HARD], [1],
+                 [Define if the pthread_in_use() detection is hard.])
+           esac
+          ])
+      elif test $gl_pthread_api != yes; then
+        # Some library is needed. Try libpthread and libc_r.
+        AC_CHECK_LIB([pthread], [pthread_kill],
+          [gl_pthread_api=yes
+           LIBPTHREAD=-lpthread
+           LIBPMULTITHREAD=-lpthread])
+        if test $gl_pthread_api != yes; then
+          # For FreeBSD 4.
+          AC_CHECK_LIB([c_r], [pthread_kill],
+            [gl_pthread_api=yes
+             LIBPTHREAD=-lc_r
+             LIBPMULTITHREAD=-lc_r])
+        fi
+      fi
+    fi
+    AC_MSG_CHECKING([whether POSIX threads API is available])
+    AC_MSG_RESULT([$gl_pthread_api])
+    AC_SUBST([LIBPTHREAD])
+    AC_SUBST([LIBPMULTITHREAD])
+    if test $gl_pthread_api = yes; then
+      AC_DEFINE([HAVE_PTHREAD_API], [1],
+        [Define if you have the <pthread.h> header and the POSIX threads API.])
+    fi
+
+    dnl On some systems, sched_yield is in librt, rather than in libpthread.
+    AC_LINK_IFELSE(
+      [AC_LANG_PROGRAM(
+         [[#include <sched.h>]],
+         [[sched_yield ();]])],
+      [LIB_SCHED_YIELD=
+      ],
+      [dnl Solaris 7...10 has sched_yield in librt, not in libpthread or libc.
+       AC_CHECK_LIB([rt], [sched_yield], [LIB_SCHED_YIELD=-lrt],
+         [dnl Solaris 2.5.1, 2.6 has sched_yield in libposix4, not librt.
+          AC_CHECK_LIB([posix4], [sched_yield], [LIB_SCHED_YIELD=-lposix4])])
+      ])
+    AC_SUBST([LIB_SCHED_YIELD])
+
+    gl_pthreadlib_body_done=done
+  fi
+])
+
+AC_DEFUN([gl_PTHREADLIB],
+[
+  AC_REQUIRE([gl_ANYTHREADLIB_EARLY])
+  gl_PTHREADLIB_BODY
+])
+
+dnl ============================================================================
+dnl Macros for the ISO C API
+
+dnl gl_STDTHREADLIB
+dnl ---------------
+dnl Tests for the libraries needs for using the ISO C threads API.
+dnl Sets the variable LIBSTDTHREAD to the linker options for use in a Makefile.
+dnl Adds to CPPFLAGS the flag -D_REENTRANT or -D_THREAD_SAFE if needed for
+dnl multithread-safe programs.
+dnl Defines the C macro HAVE_THREADS_H if (at least parts of) the ISO C threads
+dnl API is available.
+
+dnl The guts of gl_STDTHREADLIB. Needs to be expanded only once.
+
+AC_DEFUN([gl_STDTHREADLIB_BODY],
+[
+  AC_REQUIRE([gl_ANYTHREADLIB_EARLY])
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  if test -z "$gl_stdthreadlib_body_done"; then
+    AC_CHECK_HEADERS_ONCE([threads.h])
+
+    case "$host_os" in
+      mingw*)
+        LIBSTDTHREAD=
+        ;;
+      *)
+        gl_PTHREADLIB_BODY
+        if test $ac_cv_header_threads_h = yes; then
+          dnl glibc >= 2.29 has thrd_create in libpthread.
+          dnl FreeBSD >= 10 has thrd_create in libstdthreads; this library depends
+          dnl on libpthread (for the symbol 'pthread_mutexattr_gettype').
+          dnl AIX >= 7.1 and Solaris >= 11.4 have thrd_create in libc.
+          AC_CHECK_FUNCS([thrd_create])
+          if test $ac_cv_func_thrd_create = yes; then
+            LIBSTDTHREAD=
+          else
+            AC_CHECK_LIB([stdthreads], [thrd_create], [
+              LIBSTDTHREAD='-lstdthreads -lpthread'
+            ], [
+              dnl Guess that thrd_create is in libpthread.
+              LIBSTDTHREAD="$LIBPMULTITHREAD"
+            ])
+          fi
+        else
+          dnl Libraries needed by thrd.c, mtx.c, cnd.c, tss.c.
+          LIBSTDTHREAD="$LIBPMULTITHREAD $LIB_SCHED_YIELD"
+        fi
+        ;;
+    esac
+    AC_SUBST([LIBSTDTHREAD])
+
+    AC_MSG_CHECKING([whether ISO C threads API is available])
+    AC_MSG_RESULT([$ac_cv_header_threads_h])
+    gl_stdthreadlib_body_done=done
+  fi
+])
+
+AC_DEFUN([gl_STDTHREADLIB],
+[
+  AC_REQUIRE([gl_ANYTHREADLIB_EARLY])
+  gl_STDTHREADLIB_BODY
+])
+
+dnl ============================================================================
+dnl Macros for the Gnulib API
+
 dnl gl_THREADLIB
 dnl ------------
 dnl Tests for a multithreading library to be used.
@@ -16,8 +354,13 @@ dnl (it must be placed before the invocation of gl_THREADLIB_EARLY!), then the
 dnl default is 'no', otherwise it is system dependent. In both cases, the user
 dnl can change the choice through the options --enable-threads=choice or
 dnl --disable-threads.
-dnl Defines at most one of the macros USE_POSIX_THREADS, USE_SOLARIS_THREADS,
-dnl USE_PTH_THREADS, USE_WINDOWS_THREADS
+dnl Defines at most one of the macros USE_ISOC_THREADS, USE_POSIX_THREADS,
+dnl USE_ISOC_AND_POSIX_THREADS, USE_WINDOWS_THREADS.
+dnl The choice --enable-threads=isoc+posix is available only on platforms that
+dnl have both the ISO C and the POSIX threads APIs. It has the effect of using
+dnl the ISO C API for most things and the POSIX API only for creating and
+dnl controlling threads (because there is no equivalent to pthread_atfork in
+dnl the ISO C API).
 dnl Sets the variables LIBTHREAD and LTLIBTHREAD to the linker options for use
 dnl in a Makefile (LIBTHREAD for use without libtool, LTLIBTHREAD for use with
 dnl libtool).
@@ -27,6 +370,9 @@ dnl between LIBTHREAD and LIBMULTITHREAD is that on platforms supporting weak
 dnl symbols, typically LIBTHREAD is empty whereas LIBMULTITHREAD is not.
 dnl Adds to CPPFLAGS the flag -D_REENTRANT or -D_THREAD_SAFE if needed for
 dnl multithread-safe programs.
+dnl Since support for GNU pth was removed, $LTLIBTHREAD and $LIBTHREAD have the
+dnl same value, and similarly $LTLIBMULTITHREAD and $LIBMULTITHREAD have the
+dnl same value. Only system libraries are needed.
 
 AC_DEFUN([gl_THREADLIB_EARLY],
 [
@@ -50,9 +396,10 @@ AC_DEFUN([gl_THREADLIB_EARLY_BODY],
   m4_ifdef([gl_THREADLIB_DEFAULT_NO],
     [m4_divert_text([DEFAULTS], [gl_use_threads_default=no])],
     [m4_divert_text([DEFAULTS], [gl_use_threads_default=])])
+  m4_divert_text([DEFAULTS], [gl_use_winpthreads_default=])
   AC_ARG_ENABLE([threads],
-AC_HELP_STRING([--enable-threads={posix|solaris|pth|windows}], [specify multithreading API])m4_ifdef([gl_THREADLIB_DEFAULT_NO], [], [
-AC_HELP_STRING([--disable-threads], [build without multithread safety])]),
+AS_HELP_STRING([--enable-threads={isoc|posix|isoc+posix|windows}], [specify multithreading API])m4_ifdef([gl_THREADLIB_DEFAULT_NO], [], [
+AS_HELP_STRING([--disable-threads], [build without multithread safety])]),
     [gl_use_threads=$enableval],
     [if test -n "$gl_use_threads_default"; then
        gl_use_threads="$gl_use_threads_default"
@@ -62,41 +409,35 @@ changequote(,)dnl
          dnl Disable multithreading by default on OSF/1, because it interferes
          dnl with fork()/exec(): When msgexec is linked with -lpthread, its
          dnl child process gets an endless segmentation fault inside execvp().
+         osf*) gl_use_threads=no ;;
          dnl Disable multithreading by default on Cygwin 1.5.x, because it has
          dnl bugs that lead to endless loops or crashes. See
          dnl <https://cygwin.com/ml/cygwin/2009-08/msg00283.html>.
-         osf*) gl_use_threads=no ;;
          cygwin*)
                case `uname -r` in
                  1.[0-5].*) gl_use_threads=no ;;
                  *)         gl_use_threads=yes ;;
                esac
                ;;
+         dnl Obey gl_AVOID_WINPTHREAD on mingw.
+         mingw*)
+               case "$gl_use_winpthreads_default" in
+                 yes) gl_use_threads=posix ;;
+                 no)  gl_use_threads=windows ;;
+                 *)   gl_use_threads=yes ;;
+               esac
+               ;;
          *)    gl_use_threads=yes ;;
        esac
 changequote([,])dnl
      fi
     ])
-  if test "$gl_use_threads" = yes || test "$gl_use_threads" = posix; then
-    # For using <pthread.h>:
-    case "$host_os" in
-      osf*)
-        # On OSF/1, the compiler needs the flag -D_REENTRANT so that it
-        # groks <pthread.h>. cc also understands the flag -pthread, but
-        # we don't use it because 1. gcc-2.95 doesn't understand -pthread,
-        # 2. putting a flag into CPPFLAGS that has an effect on the linker
-        # causes the AC_LINK_IFELSE test below to succeed unexpectedly,
-        # leading to wrong values of LIBTHREAD and LTLIBTHREAD.
-        CPPFLAGS="$CPPFLAGS -D_REENTRANT"
-        ;;
-    esac
-    # Some systems optimize for single-threaded programs by default, and
-    # need special flags to disable these optimizations. For example, the
-    # definition of 'errno' in <errno.h>.
-    case "$host_os" in
-      aix* | freebsd*) CPPFLAGS="$CPPFLAGS -D_THREAD_SAFE" ;;
-      solaris*) CPPFLAGS="$CPPFLAGS -D_REENTRANT" ;;
-    esac
+  if test "$gl_use_threads" = yes \
+     || test "$gl_use_threads" = isoc \
+     || test "$gl_use_threads" = posix \
+     || test "$gl_use_threads" = isoc+posix; then
+    # For using <threads.h> or <pthread.h>:
+    gl_ANYTHREADLIB_EARLY
   fi
 ])
 
@@ -112,114 +453,31 @@ AC_DEFUN([gl_THREADLIB_BODY],
   LTLIBMULTITHREAD=
   if test "$gl_use_threads" != no; then
     dnl Check whether the compiler and linker support weak declarations.
-    AC_CACHE_CHECK([whether imported symbols can be declared weak],
-      [gl_cv_have_weak],
-      [gl_cv_have_weak=no
-       dnl First, test whether the compiler accepts it syntactically.
-       AC_LINK_IFELSE(
-         [AC_LANG_PROGRAM(
-            [[extern void xyzzy ();
-#pragma weak xyzzy]],
-            [[xyzzy();]])],
-         [gl_cv_have_weak=maybe])
-       if test $gl_cv_have_weak = maybe; then
-         dnl Second, test whether it actually works. On Cygwin 1.7.2, with
-         dnl gcc 4.3, symbols declared weak always evaluate to the address 0.
-         AC_RUN_IFELSE(
-           [AC_LANG_SOURCE([[
-#include <stdio.h>
-#pragma weak fputs
-int main ()
-{
-  return (fputs == NULL);
-}]])],
-           [gl_cv_have_weak=yes],
-           [gl_cv_have_weak=no],
-           [dnl When cross-compiling, assume that only ELF platforms support
-            dnl weak symbols.
-            AC_EGREP_CPP([Extensible Linking Format],
-              [#ifdef __ELF__
-               Extensible Linking Format
-               #endif
-              ],
-              [gl_cv_have_weak="guessing yes"],
-              [gl_cv_have_weak="guessing no"])
-           ])
-       fi
-       dnl But when linking statically, weak symbols don't work.
-       case " $LDFLAGS " in
-         *" -static "*) gl_cv_have_weak=no ;;
-       esac
-      ])
-    if test "$gl_use_threads" = yes || test "$gl_use_threads" = posix; then
-      # On OSF/1, the compiler needs the flag -pthread or -D_REENTRANT so that
-      # it groks <pthread.h>. It's added above, in gl_THREADLIB_EARLY_BODY.
-      AC_CHECK_HEADER([pthread.h],
-        [gl_have_pthread_h=yes], [gl_have_pthread_h=no])
-      if test "$gl_have_pthread_h" = yes; then
-        # Other possible tests:
-        #   -lpthreads (FSU threads, PCthreads)
-        #   -lgthreads
-        gl_have_pthread=
-        # Test whether both pthread_mutex_lock and pthread_mutexattr_init exist
-        # in libc. IRIX 6.5 has the first one in both libc and libpthread, but
-        # the second one only in libpthread, and lock.c needs it.
-        #
-        # If -pthread works, prefer it to -lpthread, since Ubuntu 14.04
-        # needs -pthread for some reason.  See:
-        # https://lists.gnu.org/r/bug-gnulib/2014-09/msg00023.html
-        save_LIBS=$LIBS
-        for gl_pthread in '' '-pthread'; do
-          LIBS="$LIBS $gl_pthread"
-          AC_LINK_IFELSE(
-            [AC_LANG_PROGRAM(
-               [[#include <pthread.h>
-                 pthread_mutex_t m;
-                 pthread_mutexattr_t ma;
-               ]],
-               [[pthread_mutex_lock (&m);
-                 pthread_mutexattr_init (&ma);]])],
-            [gl_have_pthread=yes
-             LIBTHREAD=$gl_pthread LTLIBTHREAD=$gl_pthread
-             LIBMULTITHREAD=$gl_pthread LTLIBMULTITHREAD=$gl_pthread])
-          LIBS=$save_LIBS
-          test -n "$gl_have_pthread" && break
-        done
-
-        # Test for libpthread by looking for pthread_kill. (Not pthread_self,
-        # since it is defined as a macro on OSF/1.)
-        if test -n "$gl_have_pthread" && test -z "$LIBTHREAD"; then
-          # The program links fine without libpthread. But it may actually
-          # need to link with libpthread in order to create multiple threads.
-          AC_CHECK_LIB([pthread], [pthread_kill],
-            [LIBMULTITHREAD=-lpthread LTLIBMULTITHREAD=-lpthread
-             # On Solaris and HP-UX, most pthread functions exist also in libc.
-             # Therefore pthread_in_use() needs to actually try to create a
-             # thread: pthread_create from libc will fail, whereas
-             # pthread_create will actually create a thread.
-             # On Solaris 10 or newer, this test is no longer needed, because
-             # libc contains the fully functional pthread functions.
-             case "$host_os" in
-               solaris | solaris2.[1-9] | solaris2.[1-9].* | hpux*)
-                 AC_DEFINE([PTHREAD_IN_USE_DETECTION_HARD], [1],
-                   [Define if the pthread_in_use() detection is hard.])
-             esac
-            ])
-        elif test -z "$gl_have_pthread"; then
-          # Some library is needed. Try libpthread and libc_r.
-          AC_CHECK_LIB([pthread], [pthread_kill],
-            [gl_have_pthread=yes
-             LIBTHREAD=-lpthread LTLIBTHREAD=-lpthread
-             LIBMULTITHREAD=-lpthread LTLIBMULTITHREAD=-lpthread])
-          if test -z "$gl_have_pthread"; then
-            # For FreeBSD 4.
-            AC_CHECK_LIB([c_r], [pthread_kill],
-              [gl_have_pthread=yes
-               LIBTHREAD=-lc_r LTLIBTHREAD=-lc_r
-               LIBMULTITHREAD=-lc_r LTLIBMULTITHREAD=-lc_r])
-          fi
-        fi
-        if test -n "$gl_have_pthread"; then
+    gl_WEAK_SYMBOLS
+    if case "$gl_cv_have_weak" in *yes) true;; *) false;; esac; then
+      dnl If we use weak symbols to implement pthread_in_use / pth_in_use /
+      dnl thread_in_use, we also need to test whether the ISO C 11 thrd_create
+      dnl facility is in use.
+      AC_CHECK_HEADERS_ONCE([threads.h])
+      :
+    fi
+    if test "$gl_use_threads" = isoc || test "$gl_use_threads" = isoc+posix; then
+      AC_CHECK_HEADERS_ONCE([threads.h])
+      gl_have_isoc_threads="$ac_cv_header_threads_h"
+    fi
+    if test "$gl_use_threads" = yes \
+       || test "$gl_use_threads" = posix \
+       || test "$gl_use_threads" = isoc+posix; then
+      gl_PTHREADLIB_BODY
+      LIBTHREAD=$LIBPTHREAD LTLIBTHREAD=$LIBPTHREAD
+      LIBMULTITHREAD=$LIBPMULTITHREAD LTLIBMULTITHREAD=$LIBPMULTITHREAD
+      if test $gl_pthread_api = yes; then
+        if test "$gl_use_threads" = isoc+posix && test "$gl_have_isoc_threads" = yes; then
+          gl_threads_api='isoc+posix'
+          AC_DEFINE([USE_ISOC_AND_POSIX_THREADS], [1],
+            [Define if the combination of the ISO C and POSIX multithreading APIs can be used.])
+          LIBTHREAD= LTLIBTHREAD=
+        else
           gl_threads_api=posix
           AC_DEFINE([USE_POSIX_THREADS], [1],
             [Define if the POSIX multithreading library can be used.])
@@ -227,75 +485,34 @@ int main ()
             if case "$gl_cv_have_weak" in *yes) true;; *) false;; esac; then
               AC_DEFINE([USE_POSIX_THREADS_WEAK], [1],
                 [Define if references to the POSIX multithreading library should be made weak.])
-              LIBTHREAD=
-              LTLIBTHREAD=
+              LIBTHREAD= LTLIBTHREAD=
+            else
+              case "$host_os" in
+                freebsd* | dragonfly*)
+                  if test "x$LIBTHREAD" != "x$LIBMULTITHREAD"; then
+                    dnl If weak symbols can't tell whether pthread_create(), pthread_key_create()
+                    dnl etc. will succeed, we need a runtime test.
+                    AC_DEFINE([PTHREAD_IN_USE_DETECTION_HARD], [1],
+                      [Define if the pthread_in_use() detection is hard.])
+                  fi
+                  ;;
+              esac
             fi
           fi
         fi
       fi
     fi
-    if test -z "$gl_have_pthread"; then
-      if test "$gl_use_threads" = yes || test "$gl_use_threads" = solaris; then
-        gl_have_solaristhread=
-        gl_save_LIBS="$LIBS"
-        LIBS="$LIBS -lthread"
-        AC_LINK_IFELSE(
-          [AC_LANG_PROGRAM(
-             [[
-#include <thread.h>
-#include <synch.h>
-             ]],
-             [[thr_self();]])],
-          [gl_have_solaristhread=yes])
-        LIBS="$gl_save_LIBS"
-        if test -n "$gl_have_solaristhread"; then
-          gl_threads_api=solaris
-          LIBTHREAD=-lthread
-          LTLIBTHREAD=-lthread
-          LIBMULTITHREAD="$LIBTHREAD"
-          LTLIBMULTITHREAD="$LTLIBTHREAD"
-          AC_DEFINE([USE_SOLARIS_THREADS], [1],
-            [Define if the old Solaris multithreading library can be used.])
-          if case "$gl_cv_have_weak" in *yes) true;; *) false;; esac; then
-            AC_DEFINE([USE_SOLARIS_THREADS_WEAK], [1],
-              [Define if references to the old Solaris multithreading library should be made weak.])
-            LIBTHREAD=
-            LTLIBTHREAD=
-          fi
-        fi
-      fi
-    fi
-    if test "$gl_use_threads" = pth; then
-      gl_save_CPPFLAGS="$CPPFLAGS"
-      AC_LIB_LINKFLAGS([pth])
-      gl_have_pth=
-      gl_save_LIBS="$LIBS"
-      LIBS="$LIBS $LIBPTH"
-      AC_LINK_IFELSE(
-        [AC_LANG_PROGRAM([[#include <pth.h>]], [[pth_self();]])],
-        [gl_have_pth=yes])
-      LIBS="$gl_save_LIBS"
-      if test -n "$gl_have_pth"; then
-        gl_threads_api=pth
-        LIBTHREAD="$LIBPTH"
-        LTLIBTHREAD="$LTLIBPTH"
-        LIBMULTITHREAD="$LIBTHREAD"
-        LTLIBMULTITHREAD="$LTLIBTHREAD"
-        AC_DEFINE([USE_PTH_THREADS], [1],
-          [Define if the GNU Pth multithreading library can be used.])
-        if test -n "$LIBMULTITHREAD" || test -n "$LTLIBMULTITHREAD"; then
-          if case "$gl_cv_have_weak" in *yes) true;; *) false;; esac; then
-            AC_DEFINE([USE_PTH_THREADS_WEAK], [1],
-              [Define if references to the GNU Pth multithreading library should be made weak.])
-            LIBTHREAD=
-            LTLIBTHREAD=
-          fi
-        fi
-      else
-        CPPFLAGS="$gl_save_CPPFLAGS"
+    if test $gl_threads_api = none; then
+      if test "$gl_use_threads" = isoc && test "$gl_have_isoc_threads" = yes; then
+        gl_STDTHREADLIB_BODY
+        LIBTHREAD=$LIBSTDTHREAD LTLIBTHREAD=$LIBSTDTHREAD
+        LIBMULTITHREAD=$LIBSTDTHREAD LTLIBMULTITHREAD=$LIBSTDTHREAD
+        gl_threads_api=isoc
+        AC_DEFINE([USE_ISOC_THREADS], [1],
+          [Define if the ISO C multithreading library can be used.])
       fi
     fi
-    if test -z "$gl_have_pthread"; then
+    if test $gl_threads_api = none; then
       case "$gl_use_threads" in
         yes | windows | win32) # The 'win32' is for backward compatibility.
           if { case "$host_os" in
@@ -337,6 +554,21 @@ AC_DEFUN([gl_DISABLE_THREADS], [
 ])
 
 
+dnl gl_AVOID_WINPTHREAD
+dnl -------------------
+dnl Sets the gl_THREADLIB default so that on mingw, a dependency to the
+dnl libwinpthread DLL (mingw-w64 winpthreads library) is avoided.
+dnl The user can still override it at installation time, by using the
+dnl configure option '--enable-threads'.
+
+AC_DEFUN([gl_AVOID_WINPTHREAD], [
+  m4_divert_text([INIT_PREPARE], [gl_use_winpthreads_default=no])
+])
+
+
+dnl ============================================================================
+
+
 dnl Survey of platforms:
 dnl
 dnl Platform           Available  Compiler    Supports   test-lock
@@ -366,7 +598,6 @@ dnl
 dnl Mac OS X 10.[123]  posix      -lpthread       Y      OK
 dnl
 dnl Solaris 7,8,9      posix      -lpthread       Y      Sol 7,8: 0.0; Sol 9: OK
-dnl                    solaris    -lthread        Y      Sol 7,8: 0.0; Sol 9: OK
 dnl
 dnl HP-UX 11           posix      -lpthread       N (cc) OK
 dnl                                               Y (gcc)
@@ -380,8 +611,6 @@ dnl                               -lpthread (gcc) Y
 dnl
 dnl Cygwin             posix      -lpthread       Y      OK
 dnl
-dnl Any of the above   pth        -lpth                  0.0
-dnl
 dnl Mingw              windows                    N      OK
 dnl
 dnl BeOS 5             --
diff --git a/m4/time_h.m4 b/m4/time_h.m4
index f08f29b..0c38ac8 100644
--- a/m4/time_h.m4
+++ b/m4/time_h.m4
@@ -1,8 +1,8 @@
 # Configure a more-standard replacement for <time.h>.
 
-# Copyright (C) 2000-2001, 2003-2007, 2009-2019 Free Software Foundation, Inc.
+# Copyright (C) 2000-2001, 2003-2007, 2009-2020 Free Software Foundation, Inc.
 
-# serial 11
+# serial 13
 
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -19,10 +19,12 @@ AC_DEFUN([gl_HEADER_TIME_H],
 
 AC_DEFUN([gl_HEADER_TIME_H_BODY],
 [
-  AC_REQUIRE([AC_C_RESTRICT])
   AC_REQUIRE([gl_HEADER_TIME_H_DEFAULTS])
+
   gl_NEXT_HEADERS([time.h])
   AC_REQUIRE([gl_CHECK_TYPE_STRUCT_TIMESPEC])
+
+  AC_REQUIRE([AC_C_RESTRICT])
 ])
 
 dnl Check whether 'struct timespec' is declared
@@ -114,12 +116,13 @@ AC_DEFUN([gl_HEADER_TIME_H_DEFAULTS],
   GNULIB_TIME_R=0;                       AC_SUBST([GNULIB_TIME_R])
   GNULIB_TIME_RZ=0;                      AC_SUBST([GNULIB_TIME_RZ])
   GNULIB_TZSET=0;                        AC_SUBST([GNULIB_TZSET])
+  dnl Support Microsoft deprecated alias function names by default.
+  GNULIB_MDA_TZSET=1;                    AC_SUBST([GNULIB_MDA_TZSET])
   dnl Assume proper GNU behavior unless another module says otherwise.
   HAVE_DECL_LOCALTIME_R=1;               AC_SUBST([HAVE_DECL_LOCALTIME_R])
   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/time_r.m4 b/m4/time_r.m4
index 5caeca7..0e86d44 100644
--- a/m4/time_r.m4
+++ b/m4/time_r.m4
@@ -1,6 +1,6 @@
 dnl Reentrant time functions: localtime_r, gmtime_r.
 
-dnl Copyright (C) 2003, 2006-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2003, 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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -17,7 +17,15 @@ AC_DEFUN([gl_TIME_R],
 
   dnl Some systems don't declare localtime_r() and gmtime_r() if _REENTRANT is
   dnl not defined.
-  AC_CHECK_DECLS([localtime_r], [], [], [[#include <time.h>]])
+  AC_CHECK_DECLS([localtime_r], [], [],
+    [[/* mingw's <time.h> provides the functions asctime_r, ctime_r,
+         gmtime_r, localtime_r only if <unistd.h> or <pthread.h> has
+         been included before.  */
+      #if defined __MINGW32__
+      # include <unistd.h>
+      #endif
+      #include <time.h>
+    ]])
   if test $ac_cv_have_decl_localtime_r = no; then
     HAVE_DECL_LOCALTIME_R=0
   fi
@@ -29,7 +37,14 @@ AC_DEFUN([gl_TIME_R],
       [gl_cv_time_r_posix],
       [AC_COMPILE_IFELSE(
          [AC_LANG_PROGRAM(
-            [[#include <time.h>]],
+            [[/* mingw's <time.h> provides the functions asctime_r, ctime_r,
+                 gmtime_r, localtime_r only if <unistd.h> or <pthread.h> has
+                 been included before.  */
+              #if defined __MINGW32__
+              # include <unistd.h>
+              #endif
+              #include <time.h>
+            ]],
             [[/* We don't need to append 'restrict's to the argument types,
                  even though the POSIX signature has the 'restrict's,
                  since C99 says they can't affect type compatibility.  */
@@ -49,6 +64,32 @@ AC_DEFUN([gl_TIME_R],
     fi
   else
     HAVE_LOCALTIME_R=0
+    dnl On mingw, localtime_r() is defined as an inline function; use through a
+    dnl direct function call works but the use as a function pointer leads to a
+    dnl link error.
+    AC_CACHE_CHECK([whether localtime_r exists as an inline function],
+      [gl_cv_func_localtime_r_inline],
+      [AC_LINK_IFELSE(
+         [AC_LANG_PROGRAM(
+            [[/* mingw's <time.h> provides the functions asctime_r, ctime_r,
+                 gmtime_r, localtime_r only if <unistd.h> or <pthread.h> has
+                 been included before.  */
+              #if defined __MINGW32__
+              # include <unistd.h>
+              #endif
+              #include <time.h>
+            ]],
+            [[time_t a;
+              struct tm r;
+              localtime_r (&a, &r);
+            ]])
+         ],
+         [gl_cv_func_localtime_r_inline=yes],
+         [gl_cv_func_localtime_r_inline=no])
+      ])
+    if test $gl_cv_func_localtime_r_inline = yes; then
+      REPLACE_LOCALTIME_R=1
+    fi
   fi
 ])
 
diff --git a/m4/timegm.m4 b/m4/timegm.m4
index d9d40de..67c0c3b 100644
--- a/m4/timegm.m4
+++ b/m4/timegm.m4
@@ -1,5 +1,5 @@
 # timegm.m4 serial 12
-dnl Copyright (C) 2003, 2007, 2009-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2003, 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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/timespec.m4 b/m4/timespec.m4
index 3db9943..e71628d 100644
--- a/m4/timespec.m4
+++ b/m4/timespec.m4
@@ -1,6 +1,6 @@
 #serial 15
 
-# Copyright (C) 2000-2001, 2003-2007, 2009-2019 Free Software Foundation, Inc.
+# Copyright (C) 2000-2001, 2003-2007, 2009-2020 Free Software Foundation, Inc.
 
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
diff --git a/m4/tm_gmtoff.m4 b/m4/tm_gmtoff.m4
index 31b841f..41517d8 100644
--- a/m4/tm_gmtoff.m4
+++ b/m4/tm_gmtoff.m4
@@ -1,5 +1,5 @@
 # tm_gmtoff.m4 serial 3
-dnl Copyright (C) 2002, 2009-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2002, 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.
diff --git a/m4/tmpdir.m4 b/m4/tmpdir.m4
index 551ce09..ad15a03 100644
--- a/m4/tmpdir.m4
+++ b/m4/tmpdir.m4
@@ -1,5 +1,5 @@
 # tmpdir.m4 serial 4
-dnl Copyright (C) 2001-2002, 2006, 2009-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2001-2002, 2006, 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.
diff --git a/m4/unistd-safer.m4 b/m4/unistd-safer.m4
index 5e2a1be..65dfdf2 100644
--- a/m4/unistd-safer.m4
+++ b/m4/unistd-safer.m4
@@ -1,5 +1,5 @@
 #serial 9
-dnl Copyright (C) 2002, 2005-2006, 2009-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2002, 2005-2006, 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.
diff --git a/m4/unistd_h.m4 b/m4/unistd_h.m4
index a04055d..f0db575 100644
--- a/m4/unistd_h.m4
+++ b/m4/unistd_h.m4
@@ -1,5 +1,5 @@
-# unistd_h.m4 serial 74
-dnl Copyright (C) 2006-2019 Free Software Foundation, Inc.
+# unistd_h.m4 serial 85
+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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -41,13 +41,22 @@ AC_DEFUN([gl_UNISTD_H],
 #  include <io.h>
 # endif
 #endif
-    ]], [chdir chown dup dup2 dup3 environ euidaccess faccessat fchdir fchownat
-    fdatasync fsync ftruncate getcwd getdomainname getdtablesize getgroups
-    gethostname getlogin getlogin_r getpagesize getpass
+    ]], [access chdir chown copy_file_range dup dup2 dup3 environ euidaccess
+    execl execle execlp execv execve execvp execvpe
+    faccessat fchdir
+    fchownat fdatasync fsync ftruncate getcwd getdomainname getdtablesize
+    getentropy getgroups gethostname getlogin getlogin_r getpagesize getpass
     getusershell setusershell endusershell
     group_member isatty lchown link linkat lseek pipe pipe2 pread pwrite
     readlink readlinkat rmdir sethostname sleep symlink symlinkat
     truncate ttyname_r unlink unlinkat usleep])
+
+  AC_REQUIRE([AC_C_RESTRICT])
+
+  AC_CHECK_DECLS_ONCE([execvpe])
+  if test $ac_cv_have_decl_execvpe = no; then
+    HAVE_DECL_EXECVPE=0
+  fi
 ])
 
 AC_DEFUN([gl_UNISTD_MODULE_INDICATOR],
@@ -61,14 +70,23 @@ AC_DEFUN([gl_UNISTD_MODULE_INDICATOR],
 
 AC_DEFUN([gl_UNISTD_H_DEFAULTS],
 [
+  GNULIB_ACCESS=0;               AC_SUBST([GNULIB_ACCESS])
   GNULIB_CHDIR=0;                AC_SUBST([GNULIB_CHDIR])
   GNULIB_CHOWN=0;                AC_SUBST([GNULIB_CHOWN])
   GNULIB_CLOSE=0;                AC_SUBST([GNULIB_CLOSE])
+  GNULIB_COPY_FILE_RANGE=0;      AC_SUBST([GNULIB_COPY_FILE_RANGE])
   GNULIB_DUP=0;                  AC_SUBST([GNULIB_DUP])
   GNULIB_DUP2=0;                 AC_SUBST([GNULIB_DUP2])
   GNULIB_DUP3=0;                 AC_SUBST([GNULIB_DUP3])
   GNULIB_ENVIRON=0;              AC_SUBST([GNULIB_ENVIRON])
   GNULIB_EUIDACCESS=0;           AC_SUBST([GNULIB_EUIDACCESS])
+  GNULIB_EXECL=0;                AC_SUBST([GNULIB_EXECL])
+  GNULIB_EXECLE=0;               AC_SUBST([GNULIB_EXECLE])
+  GNULIB_EXECLP=0;               AC_SUBST([GNULIB_EXECLP])
+  GNULIB_EXECV=0;                AC_SUBST([GNULIB_EXECV])
+  GNULIB_EXECVE=0;               AC_SUBST([GNULIB_EXECVE])
+  GNULIB_EXECVP=0;               AC_SUBST([GNULIB_EXECVP])
+  GNULIB_EXECVPE=0;              AC_SUBST([GNULIB_EXECVPE])
   GNULIB_FACCESSAT=0;            AC_SUBST([GNULIB_FACCESSAT])
   GNULIB_FCHDIR=0;               AC_SUBST([GNULIB_FCHDIR])
   GNULIB_FCHOWNAT=0;             AC_SUBST([GNULIB_FCHOWNAT])
@@ -78,10 +96,12 @@ AC_DEFUN([gl_UNISTD_H_DEFAULTS],
   GNULIB_GETCWD=0;               AC_SUBST([GNULIB_GETCWD])
   GNULIB_GETDOMAINNAME=0;        AC_SUBST([GNULIB_GETDOMAINNAME])
   GNULIB_GETDTABLESIZE=0;        AC_SUBST([GNULIB_GETDTABLESIZE])
+  GNULIB_GETENTROPY=0;           AC_SUBST([GNULIB_GETENTROPY])
   GNULIB_GETGROUPS=0;            AC_SUBST([GNULIB_GETGROUPS])
   GNULIB_GETHOSTNAME=0;          AC_SUBST([GNULIB_GETHOSTNAME])
   GNULIB_GETLOGIN=0;             AC_SUBST([GNULIB_GETLOGIN])
   GNULIB_GETLOGIN_R=0;           AC_SUBST([GNULIB_GETLOGIN_R])
+  GNULIB_GETOPT_POSIX=0;         AC_SUBST([GNULIB_GETOPT_POSIX])
   GNULIB_GETPAGESIZE=0;          AC_SUBST([GNULIB_GETPAGESIZE])
   GNULIB_GETPASS=0;              AC_SUBST([GNULIB_GETPASS])
   GNULIB_GETUSERSHELL=0;         AC_SUBST([GNULIB_GETUSERSHELL])
@@ -111,11 +131,34 @@ AC_DEFUN([gl_UNISTD_H_DEFAULTS],
   GNULIB_UNLINKAT=0;             AC_SUBST([GNULIB_UNLINKAT])
   GNULIB_USLEEP=0;               AC_SUBST([GNULIB_USLEEP])
   GNULIB_WRITE=0;                AC_SUBST([GNULIB_WRITE])
+  dnl Support Microsoft deprecated alias function names by default.
+  GNULIB_MDA_ACCESS=1;           AC_SUBST([GNULIB_MDA_ACCESS])
+  GNULIB_MDA_CHDIR=1;            AC_SUBST([GNULIB_MDA_CHDIR])
+  GNULIB_MDA_CLOSE=1;            AC_SUBST([GNULIB_MDA_CLOSE])
+  GNULIB_MDA_DUP=1;              AC_SUBST([GNULIB_MDA_DUP])
+  GNULIB_MDA_DUP2=1;             AC_SUBST([GNULIB_MDA_DUP2])
+  GNULIB_MDA_EXECL=1;            AC_SUBST([GNULIB_MDA_EXECL])
+  GNULIB_MDA_EXECLE=1;           AC_SUBST([GNULIB_MDA_EXECLE])
+  GNULIB_MDA_EXECLP=1;           AC_SUBST([GNULIB_MDA_EXECLP])
+  GNULIB_MDA_EXECV=1;            AC_SUBST([GNULIB_MDA_EXECV])
+  GNULIB_MDA_EXECVE=1;           AC_SUBST([GNULIB_MDA_EXECVE])
+  GNULIB_MDA_EXECVP=1;           AC_SUBST([GNULIB_MDA_EXECVP])
+  GNULIB_MDA_EXECVPE=1;          AC_SUBST([GNULIB_MDA_EXECVPE])
+  GNULIB_MDA_GETCWD=1;           AC_SUBST([GNULIB_MDA_GETCWD])
+  GNULIB_MDA_GETPID=1;           AC_SUBST([GNULIB_MDA_GETPID])
+  GNULIB_MDA_ISATTY=1;           AC_SUBST([GNULIB_MDA_ISATTY])
+  GNULIB_MDA_LSEEK=1;            AC_SUBST([GNULIB_MDA_LSEEK])
+  GNULIB_MDA_READ=1;             AC_SUBST([GNULIB_MDA_READ])
+  GNULIB_MDA_RMDIR=1;            AC_SUBST([GNULIB_MDA_RMDIR])
+  GNULIB_MDA_SWAB=1;             AC_SUBST([GNULIB_MDA_SWAB])
+  GNULIB_MDA_UNLINK=1;           AC_SUBST([GNULIB_MDA_UNLINK])
+  GNULIB_MDA_WRITE=1;            AC_SUBST([GNULIB_MDA_WRITE])
   dnl Assume proper GNU behavior unless another module says otherwise.
   HAVE_CHOWN=1;           AC_SUBST([HAVE_CHOWN])
-  HAVE_DUP2=1;            AC_SUBST([HAVE_DUP2])
+  HAVE_COPY_FILE_RANGE=1; AC_SUBST([HAVE_COPY_FILE_RANGE])
   HAVE_DUP3=1;            AC_SUBST([HAVE_DUP3])
   HAVE_EUIDACCESS=1;      AC_SUBST([HAVE_EUIDACCESS])
+  HAVE_EXECVPE=1;         AC_SUBST([HAVE_EXECVPE])
   HAVE_FACCESSAT=1;       AC_SUBST([HAVE_FACCESSAT])
   HAVE_FCHDIR=1;          AC_SUBST([HAVE_FCHDIR])
   HAVE_FCHOWNAT=1;        AC_SUBST([HAVE_FCHOWNAT])
@@ -123,6 +166,7 @@ AC_DEFUN([gl_UNISTD_H_DEFAULTS],
   HAVE_FSYNC=1;           AC_SUBST([HAVE_FSYNC])
   HAVE_FTRUNCATE=1;       AC_SUBST([HAVE_FTRUNCATE])
   HAVE_GETDTABLESIZE=1;   AC_SUBST([HAVE_GETDTABLESIZE])
+  HAVE_GETENTROPY=1;      AC_SUBST([HAVE_GETENTROPY])
   HAVE_GETGROUPS=1;       AC_SUBST([HAVE_GETGROUPS])
   HAVE_GETHOSTNAME=1;     AC_SUBST([HAVE_GETHOSTNAME])
   HAVE_GETLOGIN=1;        AC_SUBST([HAVE_GETLOGIN])
@@ -145,6 +189,7 @@ AC_DEFUN([gl_UNISTD_H_DEFAULTS],
   HAVE_UNLINKAT=1;        AC_SUBST([HAVE_UNLINKAT])
   HAVE_USLEEP=1;          AC_SUBST([HAVE_USLEEP])
   HAVE_DECL_ENVIRON=1;    AC_SUBST([HAVE_DECL_ENVIRON])
+  HAVE_DECL_EXECVPE=1;    AC_SUBST([HAVE_DECL_EXECVPE])
   HAVE_DECL_FCHDIR=1;     AC_SUBST([HAVE_DECL_FCHDIR])
   HAVE_DECL_FDATASYNC=1;  AC_SUBST([HAVE_DECL_FDATASYNC])
   HAVE_DECL_GETDOMAINNAME=1; AC_SUBST([HAVE_DECL_GETDOMAINNAME])
@@ -157,10 +202,18 @@ AC_DEFUN([gl_UNISTD_H_DEFAULTS],
   HAVE_DECL_TTYNAME_R=1;  AC_SUBST([HAVE_DECL_TTYNAME_R])
   HAVE_OS_H=0;            AC_SUBST([HAVE_OS_H])
   HAVE_SYS_PARAM_H=0;     AC_SUBST([HAVE_SYS_PARAM_H])
+  REPLACE_ACCESS=0;       AC_SUBST([REPLACE_ACCESS])
   REPLACE_CHOWN=0;        AC_SUBST([REPLACE_CHOWN])
   REPLACE_CLOSE=0;        AC_SUBST([REPLACE_CLOSE])
   REPLACE_DUP=0;          AC_SUBST([REPLACE_DUP])
   REPLACE_DUP2=0;         AC_SUBST([REPLACE_DUP2])
+  REPLACE_EXECL=0;        AC_SUBST([REPLACE_EXECL])
+  REPLACE_EXECLE=0;       AC_SUBST([REPLACE_EXECLE])
+  REPLACE_EXECLP=0;       AC_SUBST([REPLACE_EXECLP])
+  REPLACE_EXECV=0;        AC_SUBST([REPLACE_EXECV])
+  REPLACE_EXECVE=0;       AC_SUBST([REPLACE_EXECVE])
+  REPLACE_EXECVP=0;       AC_SUBST([REPLACE_EXECVP])
+  REPLACE_EXECVPE=0;      AC_SUBST([REPLACE_EXECVPE])
   REPLACE_FACCESSAT=0;    AC_SUBST([REPLACE_FACCESSAT])
   REPLACE_FCHOWNAT=0;     AC_SUBST([REPLACE_FCHOWNAT])
   REPLACE_FTRUNCATE=0;    AC_SUBST([REPLACE_FTRUNCATE])
@@ -191,6 +244,7 @@ AC_DEFUN([gl_UNISTD_H_DEFAULTS],
   REPLACE_UNLINKAT=0;     AC_SUBST([REPLACE_UNLINKAT])
   REPLACE_USLEEP=0;       AC_SUBST([REPLACE_USLEEP])
   REPLACE_WRITE=0;        AC_SUBST([REPLACE_WRITE])
+  UNISTD_H_HAVE_SYS_RANDOM_H=0; AC_SUBST([UNISTD_H_HAVE_SYS_RANDOM_H])
   UNISTD_H_HAVE_WINSOCK2_H=0; AC_SUBST([UNISTD_H_HAVE_WINSOCK2_H])
   UNISTD_H_HAVE_WINSOCK2_H_AND_USE_SOCKETS=0;
                            AC_SUBST([UNISTD_H_HAVE_WINSOCK2_H_AND_USE_SOCKETS])
diff --git a/m4/unlink.m4 b/m4/unlink.m4
index 69fd1af..69d8ba5 100644
--- a/m4/unlink.m4
+++ b/m4/unlink.m4
@@ -1,5 +1,5 @@
-# unlink.m4 serial 13
-dnl Copyright (C) 2009-2019 Free Software Foundation, Inc.
+# unlink.m4 serial 15
+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.
@@ -26,7 +26,7 @@ AC_DEFUN([gl_FUNC_UNLINK],
            # include <io.h>
            #endif
            #include <errno.h>
-         ]],
+         ]GL_MDA_DEFINES],
          [[int result = 0;
            if (!unlink ("conftest.file/"))
              result |= 1;
@@ -49,8 +49,8 @@ AC_DEFUN([gl_FUNC_UNLINK],
          *-gnu*)          gl_cv_func_unlink_honors_slashes="guessing yes" ;;
                           # Guess no on native Windows.
          mingw*)          gl_cv_func_unlink_honors_slashes="guessing no" ;;
-                          # If we don't know, assume the worst.
-         *)               gl_cv_func_unlink_honors_slashes="guessing no" ;;
+                          # If we don't know, obey --enable-cross-guesses.
+         *)               gl_cv_func_unlink_honors_slashes="$gl_cross_guess_normal" ;;
        esac
       ])
      rm -f conftest.file conftest.lnk])
@@ -98,6 +98,7 @@ AC_DEFUN([gl_FUNC_UNLINK],
                 # include <direct.h>
                 # include <io.h>
                 #endif
+                ]GL_MDA_DEFINES[
                 int main ()
                 {
                   int result = 0;
@@ -110,8 +111,8 @@ AC_DEFUN([gl_FUNC_UNLINK],
               ]])],
              [gl_cv_func_unlink_parent_fails=yes],
              [gl_cv_func_unlink_parent_fails=no],
-             [# If we don't know, assume the worst.
-              gl_cv_func_unlink_parent_fails="guessing no"
+             [# If we don't know, obey --enable-cross-guesses.
+              gl_cv_func_unlink_parent_fails="$gl_cross_guess_normal"
              ])
            unset GL_SUBDIR_FOR_UNLINK
            rm -rf "$tmp"
diff --git a/m4/unlocked-io.m4 b/m4/unlocked-io.m4
index ea55a1a..38658e6 100644
--- a/m4/unlocked-io.m4
+++ b/m4/unlocked-io.m4
@@ -1,6 +1,6 @@
 # unlocked-io.m4 serial 15
 
-# Copyright (C) 1998-2006, 2009-2019 Free Software Foundation, Inc.
+# Copyright (C) 1998-2006, 2009-2020 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
diff --git a/m4/utime.m4 b/m4/utime.m4
index ddd4ee1..3d2e13c 100644
--- a/m4/utime.m4
+++ b/m4/utime.m4
@@ -1,5 +1,5 @@
-# utime.m4 serial 1
-dnl Copyright (C) 2017-2019 Free Software Foundation, Inc.
+# utime.m4 serial 3
+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.
@@ -8,18 +8,68 @@ AC_DEFUN([gl_FUNC_UTIME],
 [
   AC_REQUIRE([gl_UTIME_H_DEFAULTS])
   AC_REQUIRE([AC_CANONICAL_HOST])
-  AC_CHECK_FUNCS_ONCE([utime])
-  if test $ac_cv_func_utime = no; then
-    HAVE_UTIME=0
-  else
-    case "$host_os" in
-      mingw*)
-        dnl On this platform, the original utime() or _utime() produces
-        dnl timestamps that are affected by the time zone.
-        REPLACE_UTIME=1
-        ;;
-    esac
-  fi
+  AC_CHECK_FUNCS_ONCE([lstat])
+  case "$host_os" in
+    mingw*)
+      dnl On this platform, the original utime() or _utime() produces
+      dnl timestamps that are affected by the time zone.
+      dnl Use the function name 'rpl_utime' always, in order to avoid a
+      dnl possible conflict with the function name 'utime' from oldnames.lib
+      dnl (MSVC) or liboldnames.a (mingw).
+      REPLACE_UTIME=1
+      ;;
+    *)
+      AC_CHECK_FUNCS([utime])
+      if test $ac_cv_func_utime = no; then
+        HAVE_UTIME=0
+      else
+        dnl On macOS 10.13, utime("link-to-file/", NULL) mistakenly succeeds.
+        AC_CACHE_CHECK([whether utime handles trailing slashes on files],
+          [gl_cv_func_utime_file_slash],
+          [touch conftest.tmp
+           # Assume that if we have lstat, we can also check symlinks.
+           if test $ac_cv_func_lstat = yes; then
+             ln -s conftest.tmp conftest.lnk
+           fi
+           AC_RUN_IFELSE(
+             [AC_LANG_PROGRAM(
+               [[#include <stddef.h>
+                 #include <time.h>
+               ]],
+               [[int result = 0;
+                 if (!utime ("conftest.tmp/", NULL))
+                   result |= 1;
+                 #if HAVE_LSTAT
+                 if (!utime ("conftest.lnk/", NULL))
+                   result |= 2;
+                 #endif
+                 return result;
+               ]])],
+             [gl_cv_func_utime_file_slash=yes],
+             [gl_cv_func_utime_file_slash=no],
+             [case "$host_os" in
+                                 # Guess yes on Linux systems.
+                linux-* | linux) gl_cv_func_utime_file_slash="guessing yes" ;;
+                                 # Guess yes on glibc systems.
+                *-gnu* | gnu*)   gl_cv_func_utime_file_slash="guessing yes" ;;
+                                 # Guess no on macOS.
+                darwin*)         gl_cv_func_utime_file_slash="guessing no" ;;
+                                 # If we don't know, obey --enable-cross-guesses.
+                *)               gl_cv_func_utime_file_slash="$gl_cross_guess_normal" ;;
+              esac
+             ])
+           rm -f conftest.tmp conftest.lnk
+          ])
+        case $gl_cv_func_stat_file_slash in
+          *no)
+            REPLACE_UTIME=1
+            AC_DEFINE([REPLACE_FUNC_UTIME_FILE], [1],
+              [Define to 1 if utime needs help when passed a file name with a trailing slash])
+            ;;
+        esac
+      fi
+      ;;
+  esac
 ])
 
 # Prerequisites of lib/utime.c.
diff --git a/m4/utime_h.m4 b/m4/utime_h.m4
index b0950d0..b715a53 100644
--- a/m4/utime_h.m4
+++ b/m4/utime_h.m4
@@ -1,5 +1,5 @@
-# utime_h.m4 serial 3
-dnl Copyright (C) 2017-2019 Free Software Foundation, Inc.
+# utime_h.m4 serial 5
+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.
@@ -21,28 +21,6 @@ AC_DEFUN([gl_UTIME_H],
   fi
   AC_SUBST([HAVE_UTIME_H])
 
-  m4_ifdef([gl_POSIXCHECK],
-    [UTIME_H=utime.h],
-    [UTIME_H=''
-     if m4_ifdef([gl_ANSI_CXX], [test "$CXX" != no], [false]); then
-       dnl Override <utime.h> always, to support the C++ GNULIB_NAMESPACE.
-       UTIME_H=utime.h
-     else
-       if test $ac_cv_header_utime_h != yes; then
-         dnl Provide a substitute <utime.h> file.
-         UTIME_H=utime.h
-       else
-         case "$host_os" in
-           mingw*) dnl Need special handling of 'struct utimbuf'.
-             UTIME_H=utime.h
-             ;;
-         esac
-       fi
-     fi
-    ])
-  AC_SUBST([UTIME_H])
-  AM_CONDITIONAL([GL_GENERATE_UTIME_H], [test -n "$UTIME_H"])
-
   dnl Check for declarations of anything we want to poison if the
   dnl corresponding gnulib module is not in use.
   gl_WARN_ON_USE_PREPARE([[#include <utime.h>
@@ -62,6 +40,8 @@ AC_DEFUN([gl_UTIME_MODULE_INDICATOR],
 AC_DEFUN([gl_UTIME_H_DEFAULTS],
 [
   GNULIB_UTIME=0;            AC_SUBST([GNULIB_UTIME])
+  dnl Support Microsoft deprecated alias function names by default.
+  GNULIB_MDA_UTIME=1;        AC_SUBST([GNULIB_MDA_UTIME])
   dnl Assume POSIX behavior unless another module says otherwise.
   HAVE_UTIME=1;              AC_SUBST([HAVE_UTIME])
   REPLACE_UTIME=0;           AC_SUBST([REPLACE_UTIME])
diff --git a/m4/utimens.m4 b/m4/utimens.m4
index dda86b0..3d31085 100644
--- a/m4/utimens.m4
+++ b/m4/utimens.m4
@@ -1,9 +1,9 @@
-dnl Copyright (C) 2003-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2003-2020 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 serial 9
+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;
         ]])],
@@ -35,8 +36,8 @@ AC_DEFUN([gl_UTIMENS],
            linux-* | linux) gl_cv_func_futimesat_works="guessing yes" ;;
                             # Guess yes on glibc systems.
            *-gnu*)          gl_cv_func_futimesat_works="guessing yes" ;;
-                            # If we don't know, assume the worst.
-           *)               gl_cv_func_futimesat_works="guessing no" ;;
+                            # If we don't know, obey --enable-cross-guesses.
+           *)               gl_cv_func_futimesat_works="$gl_cross_guess_normal" ;;
          esac
         ])
       rm -f conftest.file])
diff --git a/m4/utimes.m4 b/m4/utimes.m4
index 5806d8f..877bfd2 100644
--- a/m4/utimes.m4
+++ b/m4/utimes.m4
@@ -1,7 +1,7 @@
 # Detect some bugs in glibc's implementation of utimes.
-# serial 6
+# serial 8
 
-dnl Copyright (C) 2003-2005, 2009-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2003-2005, 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.
@@ -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)
@@ -147,7 +148,7 @@ main ()
           *-musl*) gl_cv_func_working_utimes="guessing yes" ;;
                    # Guess no on native Windows.
           mingw*)  gl_cv_func_working_utimes="guessing no" ;;
-          *)       gl_cv_func_working_utimes="guessing no" ;;
+          *)       gl_cv_func_working_utimes="$gl_cross_guess_normal" ;;
         esac
        ])
     ])
diff --git a/m4/vasnprintf.m4 b/m4/vasnprintf.m4
index b763a3d..43f070e 100644
--- a/m4/vasnprintf.m4
+++ b/m4/vasnprintf.m4
@@ -1,5 +1,5 @@
-# vasnprintf.m4 serial 36
-dnl Copyright (C) 2002-2004, 2006-2019 Free Software Foundation, Inc.
+# vasnprintf.m4 serial 38
+dnl Copyright (C) 2002-2004, 2006-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
@@ -32,7 +32,6 @@ AC_DEFUN([gl_REPLACE_VASNPRINTF],
 # Prerequisites of lib/printf-args.h, lib/printf-args.c.
 AC_DEFUN([gl_PREREQ_PRINTF_ARGS],
 [
-  AC_REQUIRE([AC_TYPE_LONG_LONG_INT])
   AC_REQUIRE([gt_TYPE_WCHAR_T])
   AC_REQUIRE([gt_TYPE_WINT_T])
 ])
@@ -41,7 +40,6 @@ AC_DEFUN([gl_PREREQ_PRINTF_ARGS],
 AC_DEFUN([gl_PREREQ_PRINTF_PARSE],
 [
   AC_REQUIRE([gl_FEATURES_H])
-  AC_REQUIRE([AC_TYPE_LONG_LONG_INT])
   AC_REQUIRE([gt_TYPE_WCHAR_T])
   AC_REQUIRE([gt_TYPE_WINT_T])
   AC_REQUIRE([AC_TYPE_SIZE_T])
@@ -56,7 +54,6 @@ AC_DEFUN([gl_PREREQ_PRINTF_PARSE],
 AC_DEFUN_ONCE([gl_PREREQ_VASNPRINTF],
 [
   AC_REQUIRE([AC_FUNC_ALLOCA])
-  AC_REQUIRE([AC_TYPE_LONG_LONG_INT])
   AC_REQUIRE([gt_TYPE_WCHAR_T])
   AC_REQUIRE([gt_TYPE_WINT_T])
   AC_CHECK_FUNCS([snprintf strnlen wcslen wcsnlen mbrtowc wcrtomb])
@@ -77,6 +74,16 @@ AC_DEFUN_ONCE([gl_PREREQ_VASNPRINTF],
          if the buffer had been large enough.])
       ;;
   esac
+  dnl Additionally, the use of %n can be eliminated by assuming that snprintf
+  dnl always produces NUL-terminated strings (no truncation).
+  AC_REQUIRE([gl_SNPRINTF_TRUNCATION_C99])
+  case "$gl_cv_func_snprintf_truncation_c99" in
+    *yes)
+      AC_DEFINE([HAVE_SNPRINTF_TRUNCATION_C99], [1],
+        [Define if the string produced by the snprintf function is always NUL
+         terminated.])
+      ;;
+  esac
 ])
 
 # Extra prerequisites of lib/vasnprintf.c for supporting 'long double'
diff --git a/m4/vasprintf.m4 b/m4/vasprintf.m4
index cd96229..299f46d 100644
--- a/m4/vasprintf.m4
+++ b/m4/vasprintf.m4
@@ -1,5 +1,5 @@
 # vasprintf.m4 serial 6
-dnl Copyright (C) 2002-2003, 2006-2007, 2009-2019 Free Software Foundation,
+dnl Copyright (C) 2002-2003, 2006-2007, 2009-2020 Free Software Foundation,
 dnl Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
diff --git a/m4/visibility.m4 b/m4/visibility.m4
new file mode 100644
index 0000000..9f493ba
--- /dev/null
+++ b/m4/visibility.m4
@@ -0,0 +1,77 @@
+# visibility.m4 serial 6
+dnl Copyright (C) 2005, 2008, 2010-2020 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 From Bruno Haible.
+
+dnl Tests whether the compiler supports the command-line option
+dnl -fvisibility=hidden and the function and variable attributes
+dnl __attribute__((__visibility__("hidden"))) and
+dnl __attribute__((__visibility__("default"))).
+dnl Does *not* test for __visibility__("protected") - which has tricky
+dnl semantics (see the 'vismain' test in glibc) and does not exist e.g. on
+dnl Mac OS X.
+dnl Does *not* test for __visibility__("internal") - which has processor
+dnl dependent semantics.
+dnl Does *not* test for #pragma GCC visibility push(hidden) - which is
+dnl "really only recommended for legacy code".
+dnl Set the variable CFLAG_VISIBILITY.
+dnl Defines and sets the variable HAVE_VISIBILITY.
+
+AC_DEFUN([gl_VISIBILITY],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  CFLAG_VISIBILITY=
+  HAVE_VISIBILITY=0
+  if test -n "$GCC"; then
+    dnl First, check whether -Werror can be added to the command line, or
+    dnl whether it leads to an error because of some other option that the
+    dnl user has put into $CC $CFLAGS $CPPFLAGS.
+    AC_CACHE_CHECK([whether the -Werror option is usable],
+      [gl_cv_cc_vis_werror],
+      [gl_save_CFLAGS="$CFLAGS"
+       CFLAGS="$CFLAGS -Werror"
+       AC_COMPILE_IFELSE(
+         [AC_LANG_PROGRAM([[]], [[]])],
+         [gl_cv_cc_vis_werror=yes],
+         [gl_cv_cc_vis_werror=no])
+       CFLAGS="$gl_save_CFLAGS"
+      ])
+    dnl Now check whether visibility declarations are supported.
+    AC_CACHE_CHECK([for simple visibility declarations],
+      [gl_cv_cc_visibility],
+      [gl_save_CFLAGS="$CFLAGS"
+       CFLAGS="$CFLAGS -fvisibility=hidden"
+       dnl We use the option -Werror and a function dummyfunc, because on some
+       dnl platforms (Cygwin 1.7) the use of -fvisibility triggers a warning
+       dnl "visibility attribute not supported in this configuration; ignored"
+       dnl at the first function definition in every compilation unit, and we
+       dnl don't want to use the option in this case.
+       if test $gl_cv_cc_vis_werror = yes; then
+         CFLAGS="$CFLAGS -Werror"
+       fi
+       AC_COMPILE_IFELSE(
+         [AC_LANG_PROGRAM(
+            [[extern __attribute__((__visibility__("hidden"))) int hiddenvar;
+              extern __attribute__((__visibility__("default"))) int exportedvar;
+              extern __attribute__((__visibility__("hidden"))) int hiddenfunc (void);
+              extern __attribute__((__visibility__("default"))) int exportedfunc (void);
+              void dummyfunc (void) {}
+            ]],
+            [[]])],
+         [gl_cv_cc_visibility=yes],
+         [gl_cv_cc_visibility=no])
+       CFLAGS="$gl_save_CFLAGS"
+      ])
+    if test $gl_cv_cc_visibility = yes; then
+      CFLAG_VISIBILITY="-fvisibility=hidden"
+      HAVE_VISIBILITY=1
+    fi
+  fi
+  AC_SUBST([CFLAG_VISIBILITY])
+  AC_SUBST([HAVE_VISIBILITY])
+  AC_DEFINE_UNQUOTED([HAVE_VISIBILITY], [$HAVE_VISIBILITY],
+    [Define to 1 or 0, depending whether the compiler supports simple visibility declarations.])
+])
diff --git a/m4/vsnprintf.m4 b/m4/vsnprintf.m4
index 739c904..065d234 100644
--- a/m4/vsnprintf.m4
+++ b/m4/vsnprintf.m4
@@ -1,5 +1,5 @@
 # vsnprintf.m4 serial 7
-dnl Copyright (C) 2002-2004, 2007-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2002-2004, 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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/wait-process.m4 b/m4/wait-process.m4
index 8d579eb..44108a4 100644
--- a/m4/wait-process.m4
+++ b/m4/wait-process.m4
@@ -1,5 +1,5 @@
 # wait-process.m4 serial 6
-dnl Copyright (C) 2003, 2008-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2003, 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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/waitpid.m4 b/m4/waitpid.m4
index ead350c..e1d6bed 100644
--- a/m4/waitpid.m4
+++ b/m4/waitpid.m4
@@ -1,5 +1,5 @@
 # waitpid.m4 serial 2
-dnl Copyright (C) 2010-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2010-2020 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.
diff --git a/m4/warn-on-use.m4 b/m4/warn-on-use.m4
index 7ebe2d3..1d2bcdf 100644
--- a/m4/warn-on-use.m4
+++ b/m4/warn-on-use.m4
@@ -1,5 +1,5 @@
-# warn-on-use.m4 serial 6
-dnl Copyright (C) 2010-2019 Free Software Foundation, Inc.
+# warn-on-use.m4 serial 9
+dnl Copyright (C) 2010-2020 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.
@@ -30,17 +30,15 @@ AC_DEFUN([gl_WARN_ON_USE_PREPARE],
        [AH_TEMPLATE([HAVE_RAW_DECL_]AS_TR_CPP(m4_defn([gl_decl])),
          [Define to 1 if ]m4_defn([gl_decl])[ is declared even after
           undefining macros.])])dnl
-dnl FIXME: gl_Symbol must be used unquoted until we can assume
-dnl autoconf 2.64 or newer.
      for gl_func in m4_flatten([$2]); do
        AS_VAR_PUSHDEF([gl_Symbol], [gl_cv_have_raw_decl_$gl_func])dnl
        AC_CACHE_CHECK([whether $gl_func is declared without a macro],
-         gl_Symbol,
+         [gl_Symbol],
          [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([$1],
-[@%:@undef $gl_func
-  (void) $gl_func;])],
-           [AS_VAR_SET(gl_Symbol, [yes])], [AS_VAR_SET(gl_Symbol, [no])])])
-       AS_VAR_IF(gl_Symbol, [yes],
+[[#undef $gl_func
+  (void) $gl_func;]])],
+           [AS_VAR_SET([gl_Symbol], [yes])], [AS_VAR_SET([gl_Symbol], [no])])])
+       AS_VAR_IF([gl_Symbol], [yes],
          [AC_DEFINE_UNQUOTED(AS_TR_CPP([HAVE_RAW_DECL_$gl_func]), [1])
           dnl shortcut - if the raw declaration exists, then set a cache
           dnl variable to allow skipping any later AC_CHECK_DECL efforts
diff --git a/m4/warnings.m4 b/m4/warnings.m4
new file mode 100644
index 0000000..d4e4b07
--- /dev/null
+++ b/m4/warnings.m4
@@ -0,0 +1,110 @@
+# 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,
+dnl with or without modifications, as long as this notice is preserved.
+
+dnl From Simon Josefsson
+
+# gl_AS_VAR_APPEND(VAR, VALUE)
+# ----------------------------
+# Provide the functionality of AS_VAR_APPEND if Autoconf does not have it.
+m4_ifdef([AS_VAR_APPEND],
+[m4_copy([AS_VAR_APPEND], [gl_AS_VAR_APPEND])],
+[m4_define([gl_AS_VAR_APPEND],
+[AS_VAR_SET([$1], [AS_VAR_GET([$1])$2])])])
+
+
+# gl_COMPILER_OPTION_IF(OPTION, [IF-SUPPORTED], [IF-NOT-SUPPORTED],
+#                       [PROGRAM = AC_LANG_PROGRAM()])
+# -----------------------------------------------------------------
+# Check if the compiler supports OPTION when compiling PROGRAM.
+#
+# The effects of this macro depend on the current language (_AC_LANG).
+AC_DEFUN([gl_COMPILER_OPTION_IF],
+[
+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],
+  [m4_pushdef([gl_Positive], m4_bpatsubst([$1], [^-Wno-], [-W]))],
+  [gl_positive="$1"
+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 $1], [gl_Warn], [
+  gl_save_compiler_FLAGS="$gl_Flags"
+  gl_AS_VAR_APPEND(m4_defn([gl_Flags]),
+    [" $gl_unknown_warnings_are_errors ]m4_defn([gl_Positive])["])
+  AC_LINK_IFELSE([m4_default([$4], [AC_LANG_PROGRAM([[]])])],
+                 [AS_VAR_SET([gl_Warn], [yes])],
+                 [AS_VAR_SET([gl_Warn], [no])])
+  gl_Flags="$gl_save_compiler_FLAGS"
+])
+AS_VAR_IF(gl_Warn, [yes], [$2], [$3])
+m4_popdef([gl_Positive])dnl
+AS_VAR_POPDEF([gl_Flags])dnl
+AS_VAR_POPDEF([gl_Warn])dnl
+])
+
+# gl_UNKNOWN_WARNINGS_ARE_ERRORS
+# ------------------------------
+# Clang doesn't complain about unknown warning options unless one also
+# specifies -Wunknown-warning-option -Werror.  Detect this.
+#
+# The effects of this macro depend on the current language (_AC_LANG).
+AC_DEFUN([gl_UNKNOWN_WARNINGS_ARE_ERRORS],
+[_AC_LANG_DISPATCH([$0], _AC_LANG, $@)])
+
+# Specialization for _AC_LANG = C. This macro can be AC_REQUIREd.
+AC_DEFUN([gl_UNKNOWN_WARNINGS_ARE_ERRORS(C)],
+[
+  AC_LANG_PUSH([C])
+  gl_UNKNOWN_WARNINGS_ARE_ERRORS_IMPL
+  AC_LANG_POP([C])
+])
+
+# Specialization for _AC_LANG = C++. This macro can be AC_REQUIREd.
+AC_DEFUN([gl_UNKNOWN_WARNINGS_ARE_ERRORS(C++)],
+[
+  AC_LANG_PUSH([C++])
+  gl_UNKNOWN_WARNINGS_ARE_ERRORS_IMPL
+  AC_LANG_POP([C++])
+])
+
+# Specialization for _AC_LANG = Objective C. This macro can be AC_REQUIREd.
+AC_DEFUN([gl_UNKNOWN_WARNINGS_ARE_ERRORS(Objective C)],
+[
+  AC_LANG_PUSH([Objective C])
+  gl_UNKNOWN_WARNINGS_ARE_ERRORS_IMPL
+  AC_LANG_POP([Objective C])
+])
+
+AC_DEFUN([gl_UNKNOWN_WARNINGS_ARE_ERRORS_IMPL],
+[gl_COMPILER_OPTION_IF([-Werror -Wunknown-warning-option],
+   [gl_unknown_warnings_are_errors='-Wunknown-warning-option -Werror'],
+   [gl_unknown_warnings_are_errors=])])
+
+# gl_WARN_ADD(OPTION, [VARIABLE = WARN_CFLAGS/WARN_CXXFLAGS],
+#             [PROGRAM = AC_LANG_PROGRAM()])
+# -----------------------------------------------------------
+# Adds parameter to WARN_CFLAGS/WARN_CXXFLAGS if the compiler supports it
+# when compiling PROGRAM.  For example, gl_WARN_ADD([-Wparentheses]).
+#
+# If VARIABLE is a variable name, AC_SUBST it.
+#
+# The effects of this macro depend on the current language (_AC_LANG).
+AC_DEFUN([gl_WARN_ADD],
+[AC_REQUIRE([gl_UNKNOWN_WARNINGS_ARE_ERRORS(]_AC_LANG[)])
+gl_COMPILER_OPTION_IF([$1],
+  [gl_AS_VAR_APPEND(m4_if([$2], [], [[WARN_]_AC_LANG_PREFIX[FLAGS]], [[$2]]), [" $1"])],
+  [],
+  [$3])
+m4_ifval([$2],
+         [AS_LITERAL_IF([$2], [AC_SUBST([$2])])],
+         [AC_SUBST([WARN_]_AC_LANG_PREFIX[FLAGS])])dnl
+])
+
+# Local Variables:
+# mode: autoconf
+# End:
diff --git a/m4/wchar_h.m4 b/m4/wchar_h.m4
index cd20e7a..68441d2 100644
--- a/m4/wchar_h.m4
+++ b/m4/wchar_h.m4
@@ -1,13 +1,13 @@
 dnl A placeholder for ISO C99 <wchar.h>, for platforms that have issues.
 
-dnl Copyright (C) 2007-2019 Free Software Foundation, Inc.
+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,
 dnl with or without modifications, as long as this notice is preserved.
 
 dnl Written by Eric Blake.
 
-# wchar_h.m4 serial 43
+# wchar_h.m4 serial 50
 
 AC_DEFUN([gl_WCHAR_H],
 [
@@ -40,23 +40,24 @@ AC_DEFUN([gl_WCHAR_H],
   dnl Check for declarations of anything we want to poison if the
   dnl corresponding gnulib module is not in use.
   gl_WARN_ON_USE_PREPARE([[
-/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
-   <wchar.h>.
-   BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be
-   included before <wchar.h>.  */
-#if !(defined __GLIBC__ && !defined __UCLIBC__)
-# include <stddef.h>
-# include <stdio.h>
-# include <time.h>
-#endif
-#include <wchar.h>
+      #include <wchar.h>
     ]],
     [btowc wctob mbsinit mbrtowc mbrlen mbsrtowcs mbsnrtowcs wcrtomb
-     wcsrtombs wcsnrtombs wcwidth wmemchr wmemcmp wmemcpy wmemmove wmemset
+     wcsrtombs wcsnrtombs wcwidth
+     wmemchr wmemcmp wmemcpy wmemmove wmempcpy wmemset
      wcslen wcsnlen wcscpy wcpcpy wcsncpy wcpncpy wcscat wcsncat wcscmp
      wcsncmp wcscasecmp wcsncasecmp wcscoll wcsxfrm wcsdup wcschr wcsrchr
      wcscspn wcsspn wcspbrk wcsstr wcstok wcswidth wcsftime
     ])
+
+  AC_REQUIRE([AC_C_RESTRICT])
+
+  AC_CHECK_DECLS([wcsdup], [], [], [[
+      #include <wchar.h>
+    ]])
+  if test $ac_cv_have_decl_wcsdup = no; then
+    HAVE_DECL_WCSDUP=0
+  fi
 ])
 
 dnl Check whether <wchar.h> is usable at all.
@@ -67,56 +68,49 @@ AC_DEFUN([gl_WCHAR_H_INLINE_OK],
   dnl and <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42440>. In summary,
   dnl glibc version 2.5 or older, together with gcc version 4.3 or newer and
   dnl the option -std=c99 or -std=gnu99, leads to a broken <wchar.h>.
+  AC_REQUIRE([AC_CANONICAL_HOST])
   AC_CACHE_CHECK([whether <wchar.h> uses 'inline' correctly],
     [gl_cv_header_wchar_h_correct_inline],
     [gl_cv_header_wchar_h_correct_inline=yes
-     AC_LANG_CONFTEST([
-       AC_LANG_SOURCE([[#define wcstod renamed_wcstod
-/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
-   <wchar.h>.
-   BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be
-   included before <wchar.h>.  */
-#include <stddef.h>
-#include <stdio.h>
-#include <time.h>
-#include <wchar.h>
-extern int zero (void);
-int main () { return zero(); }
-]])])
-     dnl Do not rename the object file from conftest.$ac_objext to
-     dnl conftest1.$ac_objext, as this will cause the link to fail on
-     dnl z/OS when using the XPLINK object format (due to duplicate
-     dnl CSECT names). Instead, temporarily redefine $ac_compile so
-     dnl that the object file has the latter name from the start.
-     save_ac_compile="$ac_compile"
-     ac_compile=`echo "$save_ac_compile" | sed s/conftest/conftest1/`
-     if echo '#include "conftest.c"' >conftest1.c &&
-        AC_TRY_EVAL([ac_compile]); then
-       AC_LANG_CONFTEST([
-         AC_LANG_SOURCE([[#define wcstod renamed_wcstod
-/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
-   <wchar.h>.
-   BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be
-   included before <wchar.h>.  */
-#include <stddef.h>
-#include <stdio.h>
-#include <time.h>
-#include <wchar.h>
-int zero (void) { return 0; }
-]])])
-       dnl See note above about renaming object files.
-       ac_compile=`echo "$save_ac_compile" | sed s/conftest/conftest2/`
-       if echo '#include "conftest.c"' >conftest2.c &&
-          AC_TRY_EVAL([ac_compile]); then
-         if $CC -o conftest$ac_exeext $CFLAGS $LDFLAGS conftest1.$ac_objext conftest2.$ac_objext $LIBS >&AS_MESSAGE_LOG_FD 2>&1; then
-           :
-         else
-           gl_cv_header_wchar_h_correct_inline=no
+     case "$host_os" in
+       *-gnu* | gnu*)
+         AC_LANG_CONFTEST([
+           AC_LANG_SOURCE([[
+             #define wcstod renamed_wcstod
+             #include <wchar.h>
+             extern int zero (void);
+             int main () { return zero(); }
+           ]])])
+         dnl Do not rename the object file from conftest.$ac_objext to
+         dnl conftest1.$ac_objext, as this will cause the link to fail on
+         dnl z/OS when using the XPLINK object format (due to duplicate
+         dnl CSECT names). Instead, temporarily redefine $ac_compile so
+         dnl that the object file has the latter name from the start.
+         save_ac_compile="$ac_compile"
+         ac_compile=`echo "$save_ac_compile" | sed s/conftest/conftest1/`
+         if echo '#include "conftest.c"' >conftest1.c \
+            && AC_TRY_EVAL([ac_compile]); then
+           AC_LANG_CONFTEST([
+             AC_LANG_SOURCE([[
+               #define wcstod renamed_wcstod
+               #include <wchar.h>
+               int zero (void) { return 0; }
+             ]])])
+           dnl See note above about renaming object files.
+           ac_compile=`echo "$save_ac_compile" | sed s/conftest/conftest2/`
+           if echo '#include "conftest.c"' >conftest2.c \
+              && AC_TRY_EVAL([ac_compile]); then
+             if $CC -o conftest$ac_exeext $CFLAGS $LDFLAGS conftest1.$ac_objext conftest2.$ac_objext $LIBS >&AS_MESSAGE_LOG_FD 2>&1; then
+               :
+             else
+               gl_cv_header_wchar_h_correct_inline=no
+             fi
+           fi
          fi
-       fi
-     fi
-     ac_compile="$save_ac_compile"
-     rm -f conftest[12].c conftest[12].$ac_objext conftest$ac_exeext
+         ac_compile="$save_ac_compile"
+         rm -f conftest[12].c conftest[12].$ac_objext conftest$ac_exeext
+         ;;
+     esac
     ])
   if test $gl_cv_header_wchar_h_correct_inline = no; then
     AC_MSG_ERROR([<wchar.h> cannot be used with this compiler ($CC $CFLAGS $CPPFLAGS).
@@ -157,6 +151,7 @@ AC_DEFUN([gl_WCHAR_H_DEFAULTS],
   GNULIB_WMEMCMP=0;     AC_SUBST([GNULIB_WMEMCMP])
   GNULIB_WMEMCPY=0;     AC_SUBST([GNULIB_WMEMCPY])
   GNULIB_WMEMMOVE=0;    AC_SUBST([GNULIB_WMEMMOVE])
+  GNULIB_WMEMPCPY=0;    AC_SUBST([GNULIB_WMEMPCPY])
   GNULIB_WMEMSET=0;     AC_SUBST([GNULIB_WMEMSET])
   GNULIB_WCSLEN=0;      AC_SUBST([GNULIB_WCSLEN])
   GNULIB_WCSNLEN=0;     AC_SUBST([GNULIB_WCSNLEN])
@@ -182,6 +177,8 @@ AC_DEFUN([gl_WCHAR_H_DEFAULTS],
   GNULIB_WCSTOK=0;      AC_SUBST([GNULIB_WCSTOK])
   GNULIB_WCSWIDTH=0;    AC_SUBST([GNULIB_WCSWIDTH])
   GNULIB_WCSFTIME=0;    AC_SUBST([GNULIB_WCSFTIME])
+  dnl Support Microsoft deprecated alias function names by default.
+  GNULIB_MDA_WCSDUP=1;  AC_SUBST([GNULIB_MDA_WCSDUP])
   dnl Assume proper GNU behavior unless another module says otherwise.
   HAVE_BTOWC=1;         AC_SUBST([HAVE_BTOWC])
   HAVE_MBSINIT=1;       AC_SUBST([HAVE_MBSINIT])
@@ -196,6 +193,7 @@ AC_DEFUN([gl_WCHAR_H_DEFAULTS],
   HAVE_WMEMCMP=1;       AC_SUBST([HAVE_WMEMCMP])
   HAVE_WMEMCPY=1;       AC_SUBST([HAVE_WMEMCPY])
   HAVE_WMEMMOVE=1;      AC_SUBST([HAVE_WMEMMOVE])
+  HAVE_WMEMPCPY=1;      AC_SUBST([HAVE_WMEMPCPY])
   HAVE_WMEMSET=1;       AC_SUBST([HAVE_WMEMSET])
   HAVE_WCSLEN=1;        AC_SUBST([HAVE_WCSLEN])
   HAVE_WCSNLEN=1;       AC_SUBST([HAVE_WCSNLEN])
@@ -222,6 +220,7 @@ AC_DEFUN([gl_WCHAR_H_DEFAULTS],
   HAVE_WCSWIDTH=1;      AC_SUBST([HAVE_WCSWIDTH])
   HAVE_WCSFTIME=1;      AC_SUBST([HAVE_WCSFTIME])
   HAVE_DECL_WCTOB=1;    AC_SUBST([HAVE_DECL_WCTOB])
+  HAVE_DECL_WCSDUP=1;   AC_SUBST([HAVE_DECL_WCSDUP])
   HAVE_DECL_WCWIDTH=1;  AC_SUBST([HAVE_DECL_WCWIDTH])
   REPLACE_MBSTATE_T=0;  AC_SUBST([REPLACE_MBSTATE_T])
   REPLACE_BTOWC=0;      AC_SUBST([REPLACE_BTOWC])
@@ -237,4 +236,5 @@ AC_DEFUN([gl_WCHAR_H_DEFAULTS],
   REPLACE_WCWIDTH=0;    AC_SUBST([REPLACE_WCWIDTH])
   REPLACE_WCSWIDTH=0;   AC_SUBST([REPLACE_WCSWIDTH])
   REPLACE_WCSFTIME=0;   AC_SUBST([REPLACE_WCSFTIME])
+  REPLACE_WCSTOK=0;     AC_SUBST([REPLACE_WCSTOK])
 ])
diff --git a/m4/wchar_t.m4 b/m4/wchar_t.m4
index 5db5815..e48d464 100644
--- a/m4/wchar_t.m4
+++ b/m4/wchar_t.m4
@@ -1,5 +1,5 @@
 # wchar_t.m4 serial 4 (gettext-0.18.2)
-dnl Copyright (C) 2002-2003, 2008-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2002-2003, 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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/wcrtomb.m4 b/m4/wcrtomb.m4
index fec22f3..71c48f1 100644
--- a/m4/wcrtomb.m4
+++ b/m4/wcrtomb.m4
@@ -1,5 +1,5 @@
-# wcrtomb.m4 serial 14
-dnl Copyright (C) 2008-2019 Free Software Foundation, Inc.
+# wcrtomb.m4 serial 17
+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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -15,15 +15,8 @@ AC_DEFUN([gl_FUNC_WCRTOMB],
   if test $ac_cv_func_wcrtomb = no; then
     HAVE_WCRTOMB=0
     AC_CHECK_DECLS([wcrtomb],,, [[
-/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
-   <wchar.h>.
-   BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be
-   included before <wchar.h>.  */
-#include <stddef.h>
-#include <stdio.h>
-#include <time.h>
-#include <wchar.h>
-]])
+      #include <wchar.h>
+    ]])
     if test $ac_cv_have_decl_wcrtomb = yes; then
       dnl On Minix 3.1.8, the system's <wchar.h> declares wcrtomb() although
       dnl it does not have the function. Avoid a collision with gnulib's
@@ -31,9 +24,11 @@ AC_DEFUN([gl_FUNC_WCRTOMB],
       REPLACE_WCRTOMB=1
     fi
   else
-    if test $REPLACE_MBSTATE_T = 1; then
-      REPLACE_WCRTOMB=1
-    fi
+    dnl We don't actually need to override wcrtomb when redefining the semantics
+    dnl of the mbstate_t type. Tested on 32-bit AIX.
+    dnl if test $REPLACE_MBSTATE_T = 1; then
+    dnl   REPLACE_WCRTOMB=1
+    dnl fi
     if test $REPLACE_WCRTOMB = 0; then
       dnl On Android 4.3, wcrtomb produces wrong characters in the C locale.
       dnl On AIX 4.3, OSF/1 5.1 and Solaris <= 11.3, wcrtomb (NULL, 0, NULL)
@@ -50,12 +45,6 @@ AC_DEFUN([gl_FUNC_WCRTOMB],
            [AC_LANG_SOURCE([[
 #include <string.h>
 #include <stdlib.h>
-/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
-   <wchar.h>.
-   BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be
-   included before <wchar.h>.  */
-#include <stddef.h>
-#include <stdio.h>
 #include <wchar.h>
 int main ()
 {
@@ -79,7 +68,9 @@ int main ()
         ])
       case "$gl_cv_func_wcrtomb_works" in
         *yes) ;;
-        *) REPLACE_WCRTOMB=1 ;;
+        *) AC_DEFINE([WCRTOMB_C_LOCALE_BUG], [1],
+             [Define if the wcrtomb function does not work in the C locale.])
+           REPLACE_WCRTOMB=1 ;;
       esac
     fi
     if test $REPLACE_WCRTOMB = 0; then
@@ -90,12 +81,10 @@ int main ()
           dnl is present.
 changequote(,)dnl
           case "$host_os" in
-                                     # Guess no on AIX 4, OSF/1 and Solaris.
-            aix4* | osf* | solaris*) gl_cv_func_wcrtomb_retval="guessing no" ;;
-                                     # Guess yes on native Windows.
-            mingw*)                  gl_cv_func_wcrtomb_retval="guessing yes" ;;
-                                     # Guess yes otherwise.
-            *)                       gl_cv_func_wcrtomb_retval="guessing yes" ;;
+            # Guess no on AIX 4, OSF/1, Solaris, native Windows.
+            aix4* | osf* | solaris* | mingw*) gl_cv_func_wcrtomb_retval="guessing no" ;;
+            # Guess yes otherwise.
+            *)                                gl_cv_func_wcrtomb_retval="guessing yes" ;;
           esac
 changequote([,])dnl
           if test $LOCALE_FR != none || test $LOCALE_FR_UTF8 != none || test $LOCALE_JA != none || test $LOCALE_ZH_CN != none; then
@@ -103,14 +92,8 @@ changequote([,])dnl
               [AC_LANG_SOURCE([[
 #include <locale.h>
 #include <string.h>
-/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
-   <wchar.h>.
-   BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be
-   included before <wchar.h>.  */
-#include <stddef.h>
-#include <stdio.h>
-#include <time.h>
 #include <wchar.h>
+#include <stdlib.h>
 int main ()
 {
   int result = 0;
@@ -123,6 +106,12 @@ int main ()
     {
       if (wcrtomb (NULL, 0, NULL) != 1)
         result |= 2;
+      {
+        wchar_t wc = (wchar_t) 0xBADFACE;
+        if (mbtowc (&wc, "\303\274", 2) == 2)
+          if (wcrtomb (NULL, wc, NULL) != 1)
+            result |= 2;
+      }
     }
   if (setlocale (LC_ALL, "$LOCALE_JA") != NULL)
     {
@@ -143,7 +132,9 @@ int main ()
         ])
       case "$gl_cv_func_wcrtomb_retval" in
         *yes) ;;
-        *) REPLACE_WCRTOMB=1 ;;
+        *) AC_DEFINE([WCRTOMB_RETVAL_BUG], [1],
+             [Define if the wcrtomb function has an incorrect return value.])
+           REPLACE_WCRTOMB=1 ;;
       esac
     fi
   fi
diff --git a/m4/wctype_h.m4 b/m4/wctype_h.m4
index 6903d75..5f18978 100644
--- a/m4/wctype_h.m4
+++ b/m4/wctype_h.m4
@@ -1,8 +1,8 @@
-# wctype_h.m4 serial 21
+# wctype_h.m4 serial 26
 
 dnl A placeholder for ISO C99 <wctype.h>, for platforms that lack it.
 
-dnl Copyright (C) 2006-2019 Free Software Foundation, Inc.
+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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -41,13 +41,6 @@ AC_DEFUN([gl_WCTYPE_H],
         [
           AC_RUN_IFELSE(
             [AC_LANG_SOURCE([[
-               /* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be
-                  included before <wchar.h>.
-                  BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h>
-                  must be included before <wchar.h>.  */
-               #include <stddef.h>
-               #include <stdio.h>
-               #include <time.h>
                #include <wchar.h>
                #include <wctype.h>
                int main () { return iswprint ('x') == 0; }
@@ -57,7 +50,7 @@ AC_DEFUN([gl_WCTYPE_H],
              AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <stdlib.h>
                           #if __GNU_LIBRARY__ == 1
                           Linux libc5 i18n is broken.
-                          #endif]], [])],
+                          #endif]], [[]])],
               [gl_cv_func_iswcntrl_works="guessing yes"],
               [gl_cv_func_iswcntrl_works="guessing no"])
             ])
@@ -69,10 +62,14 @@ AC_DEFUN([gl_WCTYPE_H],
   fi
   AC_SUBST([HAVE_WCTYPE_H])
 
-  case "$gl_cv_func_iswcntrl_works" in
-    *yes) REPLACE_ISWCNTRL=0 ;;
-    *)    REPLACE_ISWCNTRL=1 ;;
-  esac
+  if test $GNULIB_OVERRIDES_WINT_T = 1; then
+    REPLACE_ISWCNTRL=1
+  else
+    case "$gl_cv_func_iswcntrl_works" in
+      *yes) REPLACE_ISWCNTRL=0 ;;
+      *)    REPLACE_ISWCNTRL=1 ;;
+    esac
+  fi
   AC_SUBST([REPLACE_ISWCNTRL])
 
   if test $HAVE_ISWCNTRL = 0 || test $REPLACE_ISWCNTRL = 1; then
@@ -88,14 +85,7 @@ AC_DEFUN([gl_WCTYPE_H],
       REPLACE_TOWLOWER=0
     else
       AC_CHECK_DECLS([towlower],,,
-        [[/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be
-             included before <wchar.h>.
-             BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h>
-             must be included before <wchar.h>.  */
-          #include <stddef.h>
-          #include <stdio.h>
-          #include <time.h>
-          #include <wchar.h>
+        [[#include <wchar.h>
           #if HAVE_WCTYPE_H
           # include <wctype.h>
           #endif
@@ -124,14 +114,7 @@ AC_DEFUN([gl_WCTYPE_H],
   AC_CACHE_CHECK([for wctype_t], [gl_cv_type_wctype_t],
     [AC_COMPILE_IFELSE(
        [AC_LANG_PROGRAM(
-          [[/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be
-               included before <wchar.h>.
-               BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h>
-               must be included before <wchar.h>.  */
-            #include <stddef.h>
-            #include <stdio.h>
-            #include <time.h>
-            #include <wchar.h>
+          [[#include <wchar.h>
             #if HAVE_WCTYPE_H
             # include <wctype.h>
             #endif
@@ -150,14 +133,7 @@ AC_DEFUN([gl_WCTYPE_H],
   AC_CACHE_CHECK([for wctrans_t], [gl_cv_type_wctrans_t],
     [AC_COMPILE_IFELSE(
        [AC_LANG_PROGRAM(
-          [[/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be
-               included before <wchar.h>.
-               BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h>
-               must be included before <wchar.h>.  */
-            #include <stddef.h>
-            #include <stdio.h>
-            #include <time.h>
-            #include <wchar.h>
+          [[#include <wchar.h>
             #include <wctype.h>
             wctrans_t a;
           ]],
@@ -172,14 +148,7 @@ AC_DEFUN([gl_WCTYPE_H],
   dnl Check for declarations of anything we want to poison if the
   dnl corresponding gnulib module is not in use.
   gl_WARN_ON_USE_PREPARE([[
-/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
-   <wchar.h>.
-   BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be
-   included before <wchar.h>.  */
 #if !(defined __GLIBC__ && !defined __UCLIBC__)
-# include <stddef.h>
-# include <stdio.h>
-# include <time.h>
 # include <wchar.h>
 #endif
 #include <wctype.h>
@@ -200,6 +169,8 @@ AC_DEFUN([gl_WCTYPE_MODULE_INDICATOR],
 AC_DEFUN([gl_WCTYPE_H_DEFAULTS],
 [
   GNULIB_ISWBLANK=0;    AC_SUBST([GNULIB_ISWBLANK])
+  GNULIB_ISWDIGIT=0;    AC_SUBST([GNULIB_ISWDIGIT])
+  GNULIB_ISWXDIGIT=0;   AC_SUBST([GNULIB_ISWXDIGIT])
   GNULIB_WCTYPE=0;      AC_SUBST([GNULIB_WCTYPE])
   GNULIB_ISWCTYPE=0;    AC_SUBST([GNULIB_ISWCTYPE])
   GNULIB_WCTRANS=0;     AC_SUBST([GNULIB_WCTRANS])
@@ -209,4 +180,6 @@ AC_DEFUN([gl_WCTYPE_H_DEFAULTS],
   HAVE_WCTYPE_T=1;      AC_SUBST([HAVE_WCTYPE_T])
   HAVE_WCTRANS_T=1;     AC_SUBST([HAVE_WCTRANS_T])
   REPLACE_ISWBLANK=0;   AC_SUBST([REPLACE_ISWBLANK])
+  REPLACE_ISWDIGIT=0;   AC_SUBST([REPLACE_ISWDIGIT])
+  REPLACE_ISWXDIGIT=0;  AC_SUBST([REPLACE_ISWXDIGIT])
 ])
diff --git a/m4/wcwidth.m4 b/m4/wcwidth.m4
index 3952fd2..4c28519 100644
--- a/m4/wcwidth.m4
+++ b/m4/wcwidth.m4
@@ -1,5 +1,5 @@
-# wcwidth.m4 serial 28
-dnl Copyright (C) 2006-2019 Free Software Foundation, Inc.
+# wcwidth.m4 serial 33
+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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -19,17 +19,8 @@ AC_DEFUN([gl_FUNC_WCWIDTH],
   AC_CHECK_FUNCS_ONCE([wcwidth])
 
   AC_CHECK_DECLS([wcwidth], [], [], [[
-/* AIX 3.2.5 declares wcwidth in <string.h>. */
-#include <string.h>
-/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
-   <wchar.h>.
-   BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be included
-   before <wchar.h>.  */
-#include <stddef.h>
-#include <stdio.h>
-#include <time.h>
-#include <wchar.h>
-]])
+    #include <wchar.h>
+  ]])
   if test $ac_cv_have_decl_wcwidth != yes; then
     HAVE_DECL_WCWIDTH=0
   fi
@@ -50,25 +41,18 @@ AC_DEFUN([gl_FUNC_WCWIDTH],
   if test $ac_cv_func_wcwidth = yes || test $gl_cv_func_wcwidth_macro = yes; then
     HAVE_WCWIDTH=1
     dnl On Mac OS X 10.3, wcwidth(0x0301) (COMBINING ACUTE ACCENT) returns 1.
-    dnl On OpenBSD 5.0, wcwidth(0x05B0) (HEBREW POINT SHEVA) returns 1.
-    dnl On OSF/1 5.1, wcwidth(0x200B) (ZERO WIDTH SPACE) returns 1.
+    dnl On NetBSD 9.0, OpenBSD 5.0, wcwidth(0x05B0) (HEBREW POINT SHEVA) returns 1.
+    dnl On NetBSD 9.0, OSF/1 5.1, wcwidth(0x200B) (ZERO WIDTH SPACE) returns 1.
     dnl On OpenBSD 5.8, wcwidth(0xFF1A) (FULLWIDTH COLON) returns 0.
     dnl This leads to bugs in 'ls' (coreutils).
+    dnl On Solaris 11.4, wcwidth(0x2202) (PARTIAL DIFFERENTIAL) returns 2,
+    dnl even in Western locales.
     AC_CACHE_CHECK([whether wcwidth works reasonably in UTF-8 locales],
       [gl_cv_func_wcwidth_works],
       [
         AC_RUN_IFELSE(
           [AC_LANG_SOURCE([[
 #include <locale.h>
-/* AIX 3.2.5 declares wcwidth in <string.h>. */
-#include <string.h>
-/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
-   <wchar.h>.
-   BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be included
-   before <wchar.h>.  */
-#include <stddef.h>
-#include <stdio.h>
-#include <time.h>
 #include <wchar.h>
 #if !HAVE_DECL_WCWIDTH
 extern
@@ -80,7 +64,7 @@ int wcwidth (int);
 int main ()
 {
   int result = 0;
-  if (setlocale (LC_ALL, "fr_FR.UTF-8") != NULL)
+  if (setlocale (LC_ALL, "en_US.UTF-8") != NULL)
     {
       if (wcwidth (0x0301) > 0)
         result |= 1;
@@ -90,6 +74,8 @@ int main ()
         result |= 4;
       if (wcwidth (0xFF1A) == 0)
         result |= 8;
+      if (wcwidth (0x2202) > 1)
+        result |= 16;
     }
   return result;
 }]])],
@@ -104,7 +90,7 @@ changequote(,)dnl
              *-musl*)       gl_cv_func_wcwidth_works="guessing yes";;
                             # Guess yes on AIX 7 systems.
              aix[7-9]*)     gl_cv_func_wcwidth_works="guessing yes";;
-             *)             gl_cv_func_wcwidth_works="guessing no";;
+             *)             gl_cv_func_wcwidth_works="$gl_cross_guess_normal";;
            esac
 changequote([,])dnl
           ])
diff --git a/m4/wget.m4 b/m4/wget.m4
index b906642..5605bc5 100644
--- a/m4/wget.m4
+++ b/m4/wget.m4
@@ -1,5 +1,5 @@
 dnl Wget-specific Autoconf macros.
-dnl Copyright (C) 1995-2011, 2018-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 1995-2011, 2018-2020 Free Software Foundation, Inc.
 
 dnl This program is free software; you can redistribute it and/or modify
 dnl it under the terms of the GNU General Public License as published by
@@ -97,7 +97,7 @@ AC_DEFUN([MEMBER_SIN6_SCOPE_ID],[
 
 AC_DEFUN([PROTO_INET6],[
   AC_CACHE_CHECK([for INET6 protocol support], [wget_cv_proto_inet6],[
-    AC_TRY_CPP([
+    AC_PREPROC_IFELSE([AC_LANG_SOURCE([[
 #include <sys/types.h>
 #ifdef HAVE_SYS_SOCKET_H
 #include <sys/socket.h>
@@ -117,7 +117,7 @@ AC_DEFUN([PROTO_INET6],[
 #ifndef AF_INET6
 #error Missing AF_INET6
 #endif
-    ],[
+    ]])],[
       wget_cv_proto_inet6=yes
     ],[
       wget_cv_proto_inet6=no
diff --git a/m4/wget_manywarnings.m4 b/m4/wget_manywarnings.m4
new file mode 100644
index 0000000..9bc5ee5
--- /dev/null
+++ b/m4/wget_manywarnings.m4
@@ -0,0 +1,92 @@
+# wget_manywarnings.m4 serial 1
+dnl Copyright (C) 2016-2020 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 From Tim Ruehsen
+
+# wget_WORD_SET(RESULT, SET, WORDS)
+# --------------------------------------------------
+# Add each word in WORDS to SET if not already there and store in RESULT.
+# Words separated by whitespace.
+AC_DEFUN([wget_WORD_SET], [
+  ret=$2
+  words=" $2 "
+  for word in $3; do
+    if test "${words#*" $word "}" = "$words"; then ret="$ret $word"; fi
+  done
+  $1=$ret
+])
+
+# wget_WORD_REMOVE(RESULT, SET, WORDS)
+# --------------------------------------------------
+# Remove each word in WORDS from SET and store in RESULT.
+# Words separated by whitespace.
+AC_DEFUN([wget_WORD_REMOVE], [
+  ret=
+  words=" $3 "
+  for word in $2; do
+     if test "${words#*" $word "}" = "$words"; then ret="$ret $word"; fi
+  done
+  $1=$ret
+])
+
+# wget_MANYWARNINGS(VARIABLE, LANGUAGE)
+# -----------------------------
+# Add LANGUAGE related GCC warnings to VARIABLE.
+# This only works for gcc >= 4.3.
+AC_DEFUN([wget_MANYWARNINGS], [
+  #
+  # check if manywarnings is requested
+  #
+  AC_ARG_ENABLE([manywarnings],
+    [AS_HELP_STRING([--enable-manywarnings], [Turn on extra compiler warnings (for developers)])],
+    [case $enableval in
+       yes|no) ;;
+       *) AC_MSG_ERROR([Bad value $enableval for --enable-manywarnings option]) ;;
+     esac
+       wget_manywarnings=$enableval
+    ], [
+      test -f .manywarnings && wget_manywarnings=yes || wget_manywarnings=no
+    ]
+  )
+
+  $1=""
+
+  if test "$wget_manywarnings" = yes; then
+    # AC_PROG_CC sets $GCC to 'yes' if compiler is gcc
+    # AC_REQUIRE([AC_PROG_CC])
+
+    case $CC in
+      *gcc*) CCNAME="gcc";;
+      *clang*) CCNAME="clang";;
+    esac
+
+    if test "$CCNAME" = "gcc"; then
+      test -n "$2" && wget_LANGUAGE=$2 || wget_LANGUAGE=C
+
+      # add -Wall -Wextra to reduce number of warn flags
+      wget_WORD_SET([wget_WARN_CFLAGS], [$CFLAGS], ["-Wall -Wextra -Wformat=2"])
+
+      # collect all disabled warn flags in $WARN_CFLAGS
+      wget_WARN_CFLAGS=$wget_WARN_CFLAGS" "$($CC $wget_WARN_CFLAGS -Q --help=warning,$wget_LANGUAGE|\
+        awk '{ if (([$]2 == "[[disabled]]" || [$]2 == "")\
+          && [$]1!~/=/ && [$]1~/^-W/ && [$]1!~/</ && [$]1!="-Wall") print [$]1 }')
+
+      GCC_VERSION=$($CC -dumpversion | cut -f1 -d.)
+      if test $GCC_VERSION -ge 6; then
+        wget_WARN_CFLAGS=$wget_WARN_CFLAGS" -Warray-bounds=2 -Wnormalized=nfc -Wshift-overflow=2 -Wunused-const-variable=2"
+      fi
+      if test $GCC_VERSION -ge 7; then
+        wget_WARN_CFLAGS=$wget_WARN_CFLAGS" -Wformat-overflow=2 -Wformat-truncation=1 -Wstringop-overflow=2"
+      fi
+
+    elif test "$CCNAME" = "clang"; then
+      # set all warn flags on
+      wget_WORD_SET([wget_WARN_CFLAGS], [$CFLAGS], ["-Weverything"])
+    fi
+
+    $1=$wget_WARN_CFLAGS
+  fi
+])
diff --git a/m4/wint_t.m4 b/m4/wint_t.m4
index 61e8a23..16618e8 100644
--- a/m4/wint_t.m4
+++ b/m4/wint_t.m4
@@ -1,5 +1,5 @@
-# wint_t.m4 serial 7
-dnl Copyright (C) 2003, 2007-2019 Free Software Foundation, Inc.
+# wint_t.m4 serial 10
+dnl Copyright (C) 2003, 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,
 dnl with or without modifications, as long as this notice is preserved.
@@ -14,15 +14,7 @@ AC_DEFUN([gt_TYPE_WINT_T],
   AC_CACHE_CHECK([for wint_t], [gt_cv_c_wint_t],
     [AC_COMPILE_IFELSE(
        [AC_LANG_PROGRAM(
-          [[
-/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
-   <wchar.h>.
-   BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be included
-   before <wchar.h>.  */
-#include <stddef.h>
-#include <stdio.h>
-#include <time.h>
-#include <wchar.h>
+          [[#include <wchar.h>
             wint_t foo = (wchar_t)'\0';]],
           [[]])],
        [gt_cv_c_wint_t=yes],
@@ -32,25 +24,16 @@ AC_DEFUN([gt_TYPE_WINT_T],
 
     dnl Determine whether gnulib's <wchar.h> or <wctype.h> would, if present,
     dnl override 'wint_t'.
-    AC_CACHE_CHECK([whether wint_t is too small],
-      [gl_cv_type_wint_t_too_small],
+    AC_CACHE_CHECK([whether wint_t is large enough],
+      [gl_cv_type_wint_t_large_enough],
       [AC_COMPILE_IFELSE(
-           [AC_LANG_PROGRAM([[
-/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
-   <wchar.h>.
-   BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be
-   included before <wchar.h>.  */
-#if !(defined __GLIBC__ && !defined __UCLIBC__)
-# include <stddef.h>
-# include <stdio.h>
-# include <time.h>
-#endif
-#include <wchar.h>
+         [AC_LANG_PROGRAM(
+            [[#include <wchar.h>
               int verify[sizeof (wint_t) < sizeof (int) ? -1 : 1];
-              ]])],
-           [gl_cv_type_wint_t_too_small=no],
-           [gl_cv_type_wint_t_too_small=yes])])
-    if test $gl_cv_type_wint_t_too_small = yes; then
+            ]])],
+         [gl_cv_type_wint_t_large_enough=yes],
+         [gl_cv_type_wint_t_large_enough=no])])
+    if test $gl_cv_type_wint_t_large_enough = no; then
       GNULIB_OVERRIDES_WINT_T=1
     else
       GNULIB_OVERRIDES_WINT_T=0
diff --git a/m4/wmemchr.m4 b/m4/wmemchr.m4
new file mode 100644
index 0000000..79dc6ab
--- /dev/null
+++ b/m4/wmemchr.m4
@@ -0,0 +1,25 @@
+# wmemchr.m4 serial 5
+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,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_FUNC_WMEMCHR],
+[
+  AC_REQUIRE([gl_WCHAR_H_DEFAULTS])
+  dnl We cannot use AC_CHECK_FUNCS here, because the MSVC 9 header files
+  dnl provide this function as an inline function definition.
+  AC_CACHE_CHECK([for wmemchr], [gl_cv_func_wmemchr],
+    [AC_LINK_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[#include <wchar.h>
+          ]],
+          [[return ! wmemchr ((const wchar_t *) 0, (wchar_t) ' ', 0);]])
+       ],
+       [gl_cv_func_wmemchr=yes],
+       [gl_cv_func_wmemchr=no])
+    ])
+  if test $gl_cv_func_wmemchr = no; then
+    HAVE_WMEMCHR=0
+  fi
+])
diff --git a/m4/wmempcpy.m4 b/m4/wmempcpy.m4
new file mode 100644
index 0000000..1795fc8
--- /dev/null
+++ b/m4/wmempcpy.m4
@@ -0,0 +1,21 @@
+# wmempcpy.m4 serial 1
+dnl Copyright (C) 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_FUNC_WMEMPCPY],
+[
+  AC_REQUIRE([gl_WCHAR_H_DEFAULTS])
+
+  dnl Persuade glibc <wchar.h> to declare wmempcpy().
+  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
+
+  dnl The wmempcpy() declaration in lib/wchar.in.h uses 'restrict'.
+  AC_REQUIRE([AC_C_RESTRICT])
+
+  AC_CHECK_FUNCS_ONCE([wmempcpy])
+  if test $ac_cv_func_wmempcpy = no; then
+    HAVE_WMEMPCPY=0
+  fi
+])
diff --git a/m4/write.m4 b/m4/write.m4
index 34cb42e..2727baf 100644
--- a/m4/write.m4
+++ b/m4/write.m4
@@ -1,5 +1,5 @@
 # write.m4 serial 6
-dnl Copyright (C) 2008-2019 Free Software Foundation, Inc.
+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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/xalloc.m4 b/m4/xalloc.m4
index dfff943..a556870 100644
--- a/m4/xalloc.m4
+++ b/m4/xalloc.m4
@@ -1,5 +1,5 @@
 # xalloc.m4 serial 18
-dnl Copyright (C) 2002-2006, 2009-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2002-2006, 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.
diff --git a/m4/xsize.m4 b/m4/xsize.m4
index f2898ba..978f99a 100644
--- a/m4/xsize.m4
+++ b/m4/xsize.m4
@@ -1,5 +1,5 @@
 # xsize.m4 serial 5
-dnl Copyright (C) 2003-2004, 2008-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2003-2004, 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,
 dnl with or without modifications, as long as this notice is preserved.
diff --git a/m4/xstrndup.m4 b/m4/xstrndup.m4
index 32dc51b..3846f91 100644
--- a/m4/xstrndup.m4
+++ b/m4/xstrndup.m4
@@ -1,5 +1,5 @@
 # xstrndup.m4 serial 2
-dnl Copyright (C) 2003, 2009-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2003, 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.
diff --git a/m4/zzgnulib.m4 b/m4/zzgnulib.m4
new file mode 100644
index 0000000..98fa68f
--- /dev/null
+++ b/m4/zzgnulib.m4
@@ -0,0 +1,23 @@
+# zzgnulib.m4 serial 1
+dnl Copyright (C) 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 after all other
+dnl package- or gnulib-provided .m4 files - at least for those packages
+dnl that redefine AC_PROG_CC.
+
+dnl Redefine AC_PROG_CC so that it ends with invocations of gl_COMPILER_CLANG
+dnl and gl_COMPILER_PREPARE_CHECK_DECL.
+m4_define([AC_PROG_CC],
+  m4_defn([AC_PROG_CC])[
+gl_COMPILER_CLANG
+gl_COMPILER_PREPARE_CHECK_DECL
+])
+
+# gl_ZZGNULIB
+# -----------
+# Witness macro that this file has been included.  Needed to force
+# Automake to include this file after all other gnulib .m4 files.
+AC_DEFUN([gl_ZZGNULIB])