Update gnulib to 8f4538a53d64054ae2fc8b86c0f87c418c6176e6

Includes gnulib:0c907f7da13232908f05c415b8cec56024071906 to fix #49930 https://lists.gnu.org/archive/html/bug-guile/2021-08/msg00003.html.
2025-04-29 19:30:36 +02:00 · 2021-08-16 13:23:27 +02:00 · 2021-08-16 13:23:27 +02:00 · b4a80f4239
commit b4a80f4239
parent 5df5555d12
304 changed files with 4264 additions and 3003 deletions
--- a/m4/arpa_inet_h.m4
+++ b/m4/arpa_inet_h.m4
@ -1,4 +1,4 @@
-# arpa_inet_h.m4 serial 14
+# arpa_inet_h.m4 serial 17
 dnl Copyright (C) 2006, 2008-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@ -6,10 +6,10 @@ dnl with or without modifications, as long as this notice is preserved.

 dnl Written by Simon Josefsson and Bruno Haible

-AC_DEFUN([gl_HEADER_ARPA_INET],
+AC_DEFUN_ONCE([gl_ARPA_INET_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.
+  dnl Ensure to expand the default settings once only, before all statements
+  dnl that occur in other macros.
  AC_REQUIRE([gl_ARPA_INET_H_DEFAULTS])

  AC_CHECK_HEADERS_ONCE([arpa/inet.h])
@ -40,17 +40,32 @@ AC_DEFUN([gl_HEADER_ARPA_INET],
    ]], [inet_ntop inet_pton])
 ])

+# gl_ARPA_INET_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_ARPA_INET_MODULE_INDICATOR],
 [
-  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
-  AC_REQUIRE([gl_ARPA_INET_H_DEFAULTS])
+  dnl Ensure to expand the default settings once only.
+  gl_ARPA_INET_H_REQUIRE_DEFAULTS
  gl_MODULE_INDICATOR_SET_VARIABLE([$1])
 ])

+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_ARPA_INET_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_ARPA_INET_H_MODULE_INDICATOR_DEFAULTS], [
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_INET_NTOP])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_INET_PTON])
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_ARPA_INET_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_ARPA_INET_H_DEFAULTS])
+])
+
 AC_DEFUN([gl_ARPA_INET_H_DEFAULTS],
 [
-  GNULIB_INET_NTOP=0;     AC_SUBST([GNULIB_INET_NTOP])
-  GNULIB_INET_PTON=0;     AC_SUBST([GNULIB_INET_PTON])
  dnl Assume proper GNU behavior unless another module says otherwise.
  HAVE_DECL_INET_NTOP=1;  AC_SUBST([HAVE_DECL_INET_NTOP])
  HAVE_DECL_INET_PTON=1;  AC_SUBST([HAVE_DECL_INET_PTON])
--- a/m4/dirent_h.m4
+++ b/m4/dirent_h.m4
@ -1,4 +1,4 @@
-# dirent_h.m4 serial 16
+# dirent_h.m4 serial 19
 dnl Copyright (C) 2008-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@ -6,10 +6,10 @@ dnl with or without modifications, as long as this notice is preserved.

 dnl Written by Bruno Haible.

-AC_DEFUN([gl_DIRENT_H],
+AC_DEFUN_ONCE([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.
+  dnl Ensure to expand the default settings once only, before all statements
+  dnl that occur in other macros.
  AC_REQUIRE([gl_DIRENT_H_DEFAULTS])

  dnl <dirent.h> is always overridden, because of GNULIB_POSIXCHECK.
@ -27,26 +27,41 @@ AC_DEFUN([gl_DIRENT_H],
    ]], [alphasort closedir dirfd fdopendir opendir readdir rewinddir scandir])
 ])

+# gl_DIRENT_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 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])
+  dnl Ensure to expand the default settings once only.
+  gl_DIRENT_H_REQUIRE_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])
 ])

+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_DIRENT_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_DIRENT_H_MODULE_INDICATOR_DEFAULTS], [
+    gl_UNISTD_H_REQUIRE_DEFAULTS dnl for REPLACE_FCHDIR
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_OPENDIR])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_READDIR])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_REWINDDIR])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_CLOSEDIR])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_DIRFD])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FDOPENDIR])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SCANDIR])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ALPHASORT])
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_DIRENT_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_DIRENT_H_DEFAULTS])
+])
+
 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])
--- a/m4/environ.m4
+++ b/m4/environ.m4
@ -1,4 +1,4 @@
-# environ.m4 serial 7
+# environ.m4 serial 8
 dnl Copyright (C) 2001-2004, 2006-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@ -33,7 +33,8 @@ AC_DEFUN([gt_CHECK_VAR_DECL],
    [AC_COMPILE_IFELSE(
       [AC_LANG_PROGRAM(
          [[$1
-            extern struct { int foo; } $2;]],
+            typedef struct { int foo; } foo_t;
+            extern foo_t $2;]],
          [[$2.foo = 1;]])],
       [gt_cv_var=no],
       [gt_cv_var=yes])])
--- a/m4/fcntl_h.m4
+++ b/m4/fcntl_h.m4
@ -1,4 +1,4 @@
-# serial 17
+# serial 20
 # Configure fcntl.h.
 dnl Copyright (C) 2006-2007, 2009-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
@ -7,7 +7,7 @@ dnl with or without modifications, as long as this notice is preserved.

 dnl Written by Paul Eggert.

-AC_DEFUN([gl_FCNTL_H],
+AC_DEFUN_ONCE([gl_FCNTL_H],
 [
  AC_REQUIRE([gl_FCNTL_H_DEFAULTS])
  AC_REQUIRE([gl_FCNTL_O_FLAGS])
@ -26,25 +26,40 @@ AC_DEFUN([gl_FCNTL_H],
    ]], [fcntl openat])
 ])

+# gl_FCNTL_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_FCNTL_MODULE_INDICATOR],
 [
-  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
-  AC_REQUIRE([gl_FCNTL_H_DEFAULTS])
+  dnl Ensure to expand the default settings once only.
+  gl_FCNTL_H_REQUIRE_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])
 ])

+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_FCNTL_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_FCNTL_H_MODULE_INDICATOR_DEFAULTS], [
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_CREAT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FCNTL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_NONBLOCKING])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_OPEN])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_OPENAT])
+    dnl Support Microsoft deprecated alias function names by default.
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_CREAT], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_OPEN], [1])
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_FCNTL_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_FCNTL_H_DEFAULTS])
+])
+
 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])
--- a/m4/flock.m4
+++ b/m4/flock.m4
@ -1,4 +1,4 @@
-# flock.m4 serial 3
+# flock.m4 serial 4
 dnl Copyright (C) 2008-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@ -6,7 +6,7 @@ dnl with or without modifications, as long as this notice is preserved.

 AC_DEFUN([gl_FUNC_FLOCK],
 [
-  AC_REQUIRE([gl_HEADER_SYS_FILE_H_DEFAULTS])
+  AC_REQUIRE([gl_SYS_FILE_H_DEFAULTS])
  AC_CHECK_FUNCS_ONCE([flock])
  if test $ac_cv_func_flock = no; then
    HAVE_FLOCK=0
--- a/m4/fstat.m4
+++ b/m4/fstat.m4
@ -1,4 +1,4 @@
-# fstat.m4 serial 7
+# fstat.m4 serial 8
 dnl Copyright (C) 2011-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@ -34,7 +34,7 @@ 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_SYS_STAT_H])
  AC_REQUIRE([gl_PREREQ_STAT_W32])
  :
 ])
--- a/m4/getaddrinfo.m4
+++ b/m4/getaddrinfo.m4
@ -1,4 +1,4 @@
-# getaddrinfo.m4 serial 33
+# getaddrinfo.m4 serial 34
 dnl Copyright (C) 2004-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@ -6,8 +6,8 @@ dnl with or without modifications, as long as this notice is preserved.

 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_REQUIRE([gl_SYS_SOCKET_H])dnl for HAVE_SYS_SOCKET_H, HAVE_WINSOCK2_H
+  AC_REQUIRE([gl_NETDB_H])dnl for HAVE_NETDB_H
  GETADDRINFO_LIB=
  gai_saved_LIBS="$LIBS"

@ -156,13 +156,13 @@ const char *gai_strerror(int);]])],
 # Prerequisites of lib/netdb.in.h and lib/getaddrinfo.c.
 AC_DEFUN([gl_PREREQ_GETADDRINFO], [
  AC_REQUIRE([gl_NETDB_H_DEFAULTS])
-  AC_REQUIRE([gl_HEADER_SYS_SOCKET])dnl for HAVE_SYS_SOCKET_H, HAVE_WINSOCK2_H
+  AC_REQUIRE([gl_SYS_SOCKET_H])dnl for HAVE_SYS_SOCKET_H, HAVE_WINSOCK2_H
  AC_REQUIRE([gl_HOSTENT]) dnl for HOSTENT_LIB
  AC_REQUIRE([gl_SERVENT]) dnl for SERVENT_LIB
  AC_REQUIRE([gl_FUNC_INET_NTOP]) dnl for INET_NTOP_LIB
  AC_REQUIRE([AC_C_RESTRICT])
  AC_REQUIRE([gl_SOCKET_FAMILIES])
-  AC_REQUIRE([gl_HEADER_SYS_SOCKET])
+  AC_REQUIRE([gl_SYS_SOCKET_H])
  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])

  dnl Including sys/socket.h is wrong for Windows, but Windows does not
--- a/m4/gnulib-common.m4
+++ b/m4/gnulib-common.m4
@ -1,4 +1,4 @@
-# gnulib-common.m4 serial 63
+# gnulib-common.m4 serial 67
 dnl Copyright (C) 2007-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@ -85,12 +85,12 @@ AC_DEFUN([gl_COMMON_BODY], [
 # 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)
+# define _GL_ATTR_malloc _GL_GNUC_PREREQ (3, 0)
 # 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)
@ -103,6 +103,12 @@ AC_DEFUN([gl_COMMON_BODY], [
 # define _GL_ATTR_warn_unused_result _GL_GNUC_PREREQ (3, 4)
 #endif

+#ifdef __has_c_attribute
+# define _GL_HAS_C_ATTRIBUTE(attr) __has_c_attribute (__##attr##__)
+#else
+# define _GL_HAS_C_ATTRIBUTE(attr) 0
+#endif
+
 ]dnl There is no _GL_ATTRIBUTE_ALIGNED; use stdalign's _Alignas instead.
 [
 #if _GL_HAS_ATTRIBUTE (alloc_size)
@ -142,7 +148,20 @@ AC_DEFUN([gl_COMMON_BODY], [
 # define _GL_ATTRIBUTE_CONST
 #endif

-#if 201710L < __STDC_VERSION__
+/* _GL_ATTRIBUTE_DEALLOC (F, I) is for functions returning pointers
+   that can be freed by passing them as the Ith argument to the
+   function F.  _GL_ATTRIBUTE_DEALLOC_FREE is for functions that
+   return pointers that can be freed via 'free'; it can be used
+   only after including stdlib.h.  These macros cannot be used on
+   inline functions.  */
+#if _GL_GNUC_PREREQ (11, 0)
+# define _GL_ATTRIBUTE_DEALLOC(f, i) __attribute__ ((__malloc__ (f, i)))
+#else
+# define _GL_ATTRIBUTE_DEALLOC(f, i)
+#endif
+#define _GL_ATTRIBUTE_DEALLOC_FREE _GL_ATTRIBUTE_DEALLOC (free, 1)
+
+#if _GL_HAS_C_ATTRIBUTE (deprecated)
 # define _GL_ATTRIBUTE_DEPRECATED [[__deprecated__]]
 #elif _GL_HAS_ATTRIBUTE (deprecated)
 # define _GL_ATTRIBUTE_DEPRECATED __attribute__ ((__deprecated__))
@ -168,7 +187,7 @@ AC_DEFUN([gl_COMMON_BODY], [
 #endif

 /* FALLTHROUGH is special, because it always expands to something.  */
-#if 201710L < __STDC_VERSION__
+#if _GL_HAS_C_ATTRIBUTE (fallthrough)
 # define _GL_ATTRIBUTE_FALLTHROUGH [[__fallthrough__]]
 #elif _GL_HAS_ATTRIBUTE (fallthrough)
 # define _GL_ATTRIBUTE_FALLTHROUGH __attribute__ ((__fallthrough__))
@ -188,6 +207,12 @@ AC_DEFUN([gl_COMMON_BODY], [
 # define _GL_ATTRIBUTE_LEAF
 #endif

+#if _GL_HAS_ATTRIBUTE (malloc)
+# define _GL_ATTRIBUTE_MALLOC __attribute__ ((__malloc__))
+#else
+# define _GL_ATTRIBUTE_MALLOC
+#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__))
@ -195,24 +220,15 @@ AC_DEFUN([gl_COMMON_BODY], [
 # define _GL_ATTRIBUTE_MAY_ALIAS
 #endif

-#if 201710L < __STDC_VERSION__
+#if _GL_HAS_C_ATTRIBUTE (maybe_unused)
 # 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
+# define _GL_ATTRIBUTE_MAYBE_UNUSED _GL_ATTRIBUTE_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
-#endif
-
-#if 201710L < __STDC_VERSION__
+#if _GL_HAS_C_ATTRIBUTE (nodiscard)
 # define _GL_ATTRIBUTE_NODISCARD [[__nodiscard__]]
 #elif _GL_HAS_ATTRIBUTE (warn_unused_result)
 # define _GL_ATTRIBUTE_NODISCARD __attribute__ ((__warn_unused_result__))
@ -270,11 +286,19 @@ AC_DEFUN([gl_COMMON_BODY], [
 # define _GL_ATTRIBUTE_SENTINEL(pos)
 #endif

+#if _GL_HAS_ATTRIBUTE (unused)
+# define _GL_ATTRIBUTE_UNUSED __attribute__ ((__unused__))
+#else
+# define _GL_ATTRIBUTE_UNUSED
+#endif
+/* Earlier spellings of this macro.  */
+#define _GL_UNUSED _GL_ATTRIBUTE_UNUSED
+
 ]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
+# define _GL_UNUSED_LABEL _GL_ATTRIBUTE_UNUSED
 #else
 # define _GL_UNUSED_LABEL
 #endif
@ -357,6 +381,16 @@ AC_DEFUN([gl_COMMON_BODY], [
  export LIBC_FATAL_STDERR_
 ])

+# gl_MODULE_INDICATOR_INIT_VARIABLE([variablename])
+# gl_MODULE_INDICATOR_INIT_VARIABLE([variablename], [initialvalue])
+# initializes the shell variable that indicates the presence of the given module
+# as a C preprocessor expression.
+AC_DEFUN([gl_MODULE_INDICATOR_INIT_VARIABLE],
+[
+  GL_MODULE_INDICATOR_PREFIX[]_[$1]=m4_if([$2], , [0], [$2])
+  AC_SUBST(GL_MODULE_INDICATOR_PREFIX[]_[$1])
+])
+
 # gl_MODULE_INDICATOR_CONDITION
 # expands to a C preprocessor expression that evaluates to 1 or 0, depending
 # whether a gnulib module that has been requested shall be considered present
@ -369,9 +403,9 @@ m4_define([gl_MODULE_INDICATOR_CONDITION], [1])
 AC_DEFUN([gl_MODULE_INDICATOR_SET_VARIABLE],
 [
  gl_MODULE_INDICATOR_SET_VARIABLE_AUX(
-    [GNULIB_[]m4_translit([[$1]],
-                          [abcdefghijklmnopqrstuvwxyz./-],
-                          [ABCDEFGHIJKLMNOPQRSTUVWXYZ___])],
+    [GL_MODULE_INDICATOR_PREFIX[]_GNULIB_[]m4_translit([[$1]],
+                                                       [abcdefghijklmnopqrstuvwxyz./-],
+                                                       [ABCDEFGHIJKLMNOPQRSTUVWXYZ___])],
    [gl_MODULE_INDICATOR_CONDITION])
 ])

@ -656,6 +690,72 @@ AC_DEFUN([gl_CACHE_VAL_SILENT],
  ])
 ])

+# gl_CC_ALLOW_WARNINGS
+# sets and substitutes a variable GL_CFLAG_ALLOW_WARNINGS, to a $(CC) option
+# that reverts a preceding '-Werror' option, if available.
+# This is expected to be '-Wno-error' on gcc, clang (except clang/MSVC), xlclang
+# and empty otherwise.
+AC_DEFUN([gl_CC_ALLOW_WARNINGS],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_CACHE_CHECK([for C compiler option to allow warnings],
+    [gl_cv_cc_wallow],
+    [rm -f conftest*
+     echo 'int dummy;' > conftest.c
+     AC_TRY_COMMAND([${CC-cc} $CFLAGS $CPPFLAGS -c conftest.c 2>conftest1.err]) >/dev/null
+     AC_TRY_COMMAND([${CC-cc} $CFLAGS $CPPFLAGS -Wno-error -c conftest.c 2>conftest2.err]) >/dev/null
+     dnl Test the number of error output lines, because AIX xlc accepts the
+     dnl option '-Wno-error', just to produce a warning
+     dnl "Option -Wno-error was incorrectly specified. The option will be ignored."
+     dnl afterwards.
+     if test $? = 0 && test `wc -l < conftest1.err` = `wc -l < conftest2.err`; then
+       gl_cv_cc_wallow='-Wno-error'
+     else
+       gl_cv_cc_wallow=none
+     fi
+     rm -f conftest*
+    ])
+  case "$gl_cv_cc_wallow" in
+    none) GL_CFLAG_ALLOW_WARNINGS='' ;;
+    *)    GL_CFLAG_ALLOW_WARNINGS="$gl_cv_cc_wallow" ;;
+  esac
+  AC_SUBST([GL_CFLAG_ALLOW_WARNINGS])
+])
+
+# gl_CXX_ALLOW_WARNINGS
+# sets and substitutes a variable GL_CXXFLAG_ALLOW_WARNINGS, to a $(CC) option
+# that reverts a preceding '-Werror' option, if available.
+AC_DEFUN([gl_CXX_ALLOW_WARNINGS],
+[
+  dnl Requires AC_PROG_CXX or gl_PROG_ANSI_CXX.
+  if test -n "$CXX" && test "$CXX" != no; then
+    AC_CACHE_CHECK([for C++ compiler option to allow warnings],
+      [gl_cv_cxx_wallow],
+      [rm -f conftest*
+       echo 'int dummy;' > conftest.cc
+       AC_TRY_COMMAND([${CXX-c++} $CXXFLAGS $CPPFLAGS -c conftest.cc 2>conftest1.err]) >/dev/null
+       AC_TRY_COMMAND([${CXX-c++} $CXXFLAGS $CPPFLAGS -Wno-error -c conftest.cc 2>conftest2.err]) >/dev/null
+       dnl Test the number of error output lines, because AIX xlC accepts the
+       dnl option '-Wno-error', just to produce a warning
+       dnl "Option -Wno-error was incorrectly specified. The option will be ignored."
+       dnl afterwards.
+       if test $? = 0 && test `wc -l < conftest1.err` = `wc -l < conftest2.err`; then
+         gl_cv_cxx_wallow='-Wno-error'
+       else
+         gl_cv_cxx_wallow=none
+       fi
+       rm -f conftest*
+      ])
+    case "$gl_cv_cxx_wallow" in
+      none) GL_CXXFLAG_ALLOW_WARNINGS='' ;;
+      *)    GL_CXXFLAG_ALLOW_WARNINGS="$gl_cv_cxx_wallow" ;;
+    esac
+  else
+    GL_CXXFLAG_ALLOW_WARNINGS=''
+  fi
+  AC_SUBST([GL_CXXFLAG_ALLOW_WARNINGS])
+])
+
 dnl Expands to some code for use in .c programs that, on native Windows, defines
 dnl the Microsoft deprecated alias function names to the underscore-prefixed
 dnl actual function names. With this macro, these function names are available
--- a/m4/gnulib-comp.m4
+++ b/m4/gnulib-comp.m4
@ -142,6 +142,7 @@ AC_DEFUN([gl_EARLY],
  # Code from module langinfo:
  # Code from module largefile:
  AC_REQUIRE([AC_SYS_LARGEFILE])
+  AC_REQUIRE([gl_YEAR2038_EARLY])
  # Code from module ldexp:
  # Code from module lib-symbol-versions:
  # Code from module lib-symbol-visibility:
@ -281,9 +282,11 @@ AC_DEFUN([gl_INIT],
  m4_pushdef([AC_LIBSOURCES], m4_defn([gl_LIBSOURCES]))
  m4_pushdef([gl_LIBSOURCES_LIST], [])
  m4_pushdef([gl_LIBSOURCES_DIR], [])
+  m4_pushdef([GL_MACRO_PREFIX], [gl])
+  m4_pushdef([GL_MODULE_INDICATOR_PREFIX], [GL])
  gl_COMMON
  gl_source_base='lib'
-  AC_REQUIRE([gl_HEADER_SYS_SOCKET])
+  AC_REQUIRE([gl_SYS_SOCKET_H])
  if test "$ac_cv_header_winsock2_h" = yes; then
    AC_LIBOBJ([accept])
  fi
@ -291,9 +294,10 @@ AC_DEFUN([gl_INIT],
  gl_FUNC_ACCEPT4
  gl_SYS_SOCKET_MODULE_INDICATOR([accept4])
  gl_FUNC_ALLOCA
-  gl_HEADER_ARPA_INET
+  gl_ARPA_INET_H
+  gl_ARPA_INET_H_REQUIRE_DEFAULTS
  AC_PROG_MKDIR_P
-  AC_REQUIRE([gl_HEADER_SYS_SOCKET])
+  AC_REQUIRE([gl_SYS_SOCKET_H])
  if test "$ac_cv_header_winsock2_h" = yes; then
    AC_LIBOBJ([bind])
  fi
@ -317,7 +321,7 @@ AC_DEFUN([gl_INIT],
    AC_LIBOBJ([close])
  fi
  gl_UNISTD_MODULE_INDICATOR([close])
-  AC_REQUIRE([gl_HEADER_SYS_SOCKET])
+  AC_REQUIRE([gl_SYS_SOCKET_H])
  if test "$ac_cv_header_winsock2_h" = yes; then
    AC_LIBOBJ([connect])
  fi
@ -328,6 +332,7 @@ AC_DEFUN([gl_INIT],
  fi
  gl_MATH_MODULE_INDICATOR([copysign])
  gl_DIRENT_H
+  gl_DIRENT_H_REQUIRE_DEFAULTS
  gl_FUNC_DIRFD
  if test $ac_cv_func_dirfd = no && test $gl_cv_func_dirfd_macro = no \
     || test $REPLACE_DIRFD = 1; then
@ -347,6 +352,7 @@ AC_DEFUN([gl_INIT],
  gl_HEADER_ERRNO_H
  AC_REQUIRE([gl_EXTERN_INLINE])
  gl_FCNTL_H
+  gl_FCNTL_H_REQUIRE_DEFAULTS
  AC_C_FLEXIBLE_ARRAY_MEMBER
  gl_FLOAT_H
  if test $REPLACE_FLOAT_LDBL = 1; then
@ -360,7 +366,7 @@ AC_DEFUN([gl_INIT],
    AC_LIBOBJ([flock])
    gl_PREREQ_FLOCK
  fi
-  gl_HEADER_SYS_FILE_MODULE_INDICATOR([flock])
+  gl_SYS_FILE_MODULE_INDICATOR([flock])
  AC_REQUIRE([gl_FUNC_FLOOR])
  if test $REPLACE_FLOOR = 1; then
    AC_LIBOBJ([floor])
@ -409,17 +415,17 @@ AC_DEFUN([gl_INIT],
  fi
  gl_UNISTD_MODULE_INDICATOR([getlogin])
  AC_REQUIRE([gl_LIB_GETLOGIN])
-  AC_REQUIRE([gl_HEADER_SYS_SOCKET])
+  AC_REQUIRE([gl_SYS_SOCKET_H])
  if test "$ac_cv_header_winsock2_h" = yes; then
    AC_LIBOBJ([getpeername])
  fi
  gl_SYS_SOCKET_MODULE_INDICATOR([getpeername])
-  AC_REQUIRE([gl_HEADER_SYS_SOCKET])
+  AC_REQUIRE([gl_SYS_SOCKET_H])
  if test "$ac_cv_header_winsock2_h" = yes; then
    AC_LIBOBJ([getsockname])
  fi
  gl_SYS_SOCKET_MODULE_INDICATOR([getsockname])
-  AC_REQUIRE([gl_HEADER_SYS_SOCKET])
+  AC_REQUIRE([gl_SYS_SOCKET_H])
  if test "$ac_cv_header_winsock2_h" = yes; then
    AC_LIBOBJ([getsockopt])
  fi
@ -439,6 +445,7 @@ AC_DEFUN([gl_INIT],
  m4_ifdef([gl_ICONV_MODULE_INDICATOR],
    [gl_ICONV_MODULE_INDICATOR([iconv])])
  gl_ICONV_H
+  gl_ICONV_H_REQUIRE_DEFAULTS
  gl_FUNC_ICONV_OPEN
  if test $REPLACE_ICONV_OPEN = 1; then
    AC_LIBOBJ([iconv_open])
@ -461,6 +468,7 @@ AC_DEFUN([gl_INIT],
  fi
  gl_ARPA_INET_MODULE_INDICATOR([inet_pton])
  gl_INTTYPES_INCOMPLETE
+  gl_INTTYPES_H_REQUIRE_DEFAULTS
  gl_ISFINITE
  if test $REPLACE_ISFINITE = 1; then
    AC_LIBOBJ([isfinite])
@ -501,6 +509,7 @@ AC_DEFUN([gl_INIT],
  fi
  gl_MATH_MODULE_INDICATOR([isnanl])
  gl_LANGINFO_H
+  gl_LANGINFO_H_REQUIRE_DEFAULTS
  AC_REQUIRE([gl_LARGEFILE])
  gl_FUNC_LDEXP
  gl_LD_VERSION_SCRIPT
@ -512,7 +521,7 @@ AC_DEFUN([gl_INIT],
    AC_LIBOBJ([link])
  fi
  gl_UNISTD_MODULE_INDICATOR([link])
-  AC_REQUIRE([gl_HEADER_SYS_SOCKET])
+  AC_REQUIRE([gl_SYS_SOCKET_H])
  if test "$ac_cv_header_winsock2_h" = yes; then
    AC_LIBOBJ([listen])
  fi
@ -522,6 +531,7 @@ AC_DEFUN([gl_INIT],
  LOCALCHARSET_TESTS_ENVIRONMENT=
  AC_SUBST([LOCALCHARSET_TESTS_ENVIRONMENT])
  gl_LOCALE_H
+  gl_LOCALE_H_REQUIRE_DEFAULTS
  gl_FUNC_LOG1P
  if test $HAVE_LOG1P = 0 || test $REPLACE_LOG1P = 1; then
    AC_LIBOBJ([log1p])
@ -541,15 +551,14 @@ AC_DEFUN([gl_INIT],
  if test $REPLACE_MALLOC = 1; then
    AC_LIBOBJ([malloc])
  fi
-  gl_MODULE_INDICATOR([malloc-gnu])
-  gl_FUNC_MALLOC_POSIX
+  AC_REQUIRE([gl_FUNC_MALLOC_POSIX])
  if test $REPLACE_MALLOC = 1; then
    AC_LIBOBJ([malloc])
  fi
  gl_STDLIB_MODULE_INDICATOR([malloc-posix])
-  gl_MODULE_INDICATOR([malloc-posix])
  gl_MALLOCA
  gl_MATH_H
+  gl_MATH_H_REQUIRE_DEFAULTS
  gl_MINMAX
  gl_FUNC_MKDIR
  if test $REPLACE_MKDIR = 1; then
@ -573,7 +582,8 @@ AC_DEFUN([gl_INIT],
  fi
  gl_MODULE_INDICATOR([msvc-nothrow])
  gl_MULTIARCH
-  gl_HEADER_NETDB
+  gl_NETDB_H
+  gl_NETDB_H_REQUIRE_DEFAULTS
  gl_HEADER_NETINET_IN
  AC_PROG_MKDIR_P
  gl_FUNC_NL_LANGINFO
@ -607,6 +617,7 @@ AC_DEFUN([gl_INIT],
  fi
  gl_POLL_MODULE_INDICATOR([poll])
  gl_POLL_H
+  gl_POLL_H_REQUIRE_DEFAULTS
  gl_FUNC_PUTENV
  if test $REPLACE_PUTENV = 1; then
    AC_LIBOBJ([putenv])
@ -625,12 +636,12 @@ AC_DEFUN([gl_INIT],
    gl_PREREQ_READLINK
  fi
  gl_UNISTD_MODULE_INDICATOR([readlink])
-  AC_REQUIRE([gl_HEADER_SYS_SOCKET])
+  AC_REQUIRE([gl_SYS_SOCKET_H])
  if test "$ac_cv_header_winsock2_h" = yes; then
    AC_LIBOBJ([recv])
  fi
  gl_SYS_SOCKET_MODULE_INDICATOR([recv])
-  AC_REQUIRE([gl_HEADER_SYS_SOCKET])
+  AC_REQUIRE([gl_SYS_SOCKET_H])
  if test "$ac_cv_header_winsock2_h" = yes; then
    AC_LIBOBJ([recvfrom])
  fi
@ -657,12 +668,12 @@ AC_DEFUN([gl_INIT],
    AC_LIBOBJ([select])
  fi
  gl_SYS_SELECT_MODULE_INDICATOR([select])
-  AC_REQUIRE([gl_HEADER_SYS_SOCKET])
+  AC_REQUIRE([gl_SYS_SOCKET_H])
  if test "$ac_cv_header_winsock2_h" = yes; then
    AC_LIBOBJ([send])
  fi
  gl_SYS_SOCKET_MODULE_INDICATOR([send])
-  AC_REQUIRE([gl_HEADER_SYS_SOCKET])
+  AC_REQUIRE([gl_SYS_SOCKET_H])
  if test "$ac_cv_header_winsock2_h" = yes; then
    AC_LIBOBJ([sendto])
  fi
@ -672,25 +683,26 @@ AC_DEFUN([gl_INIT],
    AC_LIBOBJ([setenv])
  fi
  gl_STDLIB_MODULE_INDICATOR([setenv])
-  AC_REQUIRE([gl_HEADER_SYS_SOCKET])
+  AC_REQUIRE([gl_SYS_SOCKET_H])
  if test "$ac_cv_header_winsock2_h" = yes; then
    AC_LIBOBJ([setsockopt])
  fi
  gl_SYS_SOCKET_MODULE_INDICATOR([setsockopt])
-  AC_REQUIRE([gl_HEADER_SYS_SOCKET])
+  AC_REQUIRE([gl_SYS_SOCKET_H])
  if test "$ac_cv_header_winsock2_h" = yes; then
    AC_LIBOBJ([shutdown])
  fi
  gl_SYS_SOCKET_MODULE_INDICATOR([shutdown])
  gl_SIGNAL_H
-  AC_REQUIRE([gl_HEADER_SYS_SOCKET])
+  gl_SIGNAL_H_REQUIRE_DEFAULTS
+  AC_REQUIRE([gl_SYS_SOCKET_H])
  if test "$ac_cv_header_winsock2_h" = yes; then
    AC_LIBOBJ([socket])
  fi
  # When this module is used, sockets may actually occur as file descriptors,
  # hence it is worth warning if the modules 'close' and 'ioctl' are not used.
-  m4_ifdef([gl_UNISTD_H_DEFAULTS], [AC_REQUIRE([gl_UNISTD_H_DEFAULTS])])
-  m4_ifdef([gl_SYS_IOCTL_H_DEFAULTS], [AC_REQUIRE([gl_SYS_IOCTL_H_DEFAULTS])])
+  m4_ifdef([gl_UNISTD_H_DEFAULTS], [gl_UNISTD_H_REQUIRE_DEFAULTS])
+  m4_ifdef([gl_SYS_IOCTL_H_DEFAULTS], [gl_SYS_IOCTL_H_REQUIRE_DEFAULTS])
  AC_REQUIRE([gl_PREREQ_SYS_H_WINSOCK2])
  if test "$ac_cv_header_winsock2_h" = yes; then
    UNISTD_H_HAVE_WINSOCK2_H_AND_USE_SOCKETS=1
@ -705,31 +717,67 @@ AC_DEFUN([gl_INIT],
  gl_STDALIGN_H
  AM_STDBOOL_H
  gl_STDDEF_H
+  gl_STDDEF_H_REQUIRE_DEFAULTS
  gl_STDINT_H
  gl_STDIO_H
+  gl_STDIO_H_REQUIRE_DEFAULTS
+  dnl No need to create extra modules for these functions. Everyone who uses
+  dnl <stdio.h> likely needs them.
+  gl_STDIO_MODULE_INDICATOR([fscanf])
+  gl_MODULE_INDICATOR([fscanf])
+  gl_STDIO_MODULE_INDICATOR([scanf])
+  gl_MODULE_INDICATOR([scanf])
+  gl_STDIO_MODULE_INDICATOR([fgetc])
+  gl_STDIO_MODULE_INDICATOR([getc])
+  gl_STDIO_MODULE_INDICATOR([getchar])
+  gl_STDIO_MODULE_INDICATOR([fgets])
+  gl_STDIO_MODULE_INDICATOR([fread])
+  dnl No need to create extra modules for these functions. Everyone who uses
+  dnl <stdio.h> likely needs them.
+  gl_STDIO_MODULE_INDICATOR([fprintf])
+  gl_STDIO_MODULE_INDICATOR([printf])
+  gl_STDIO_MODULE_INDICATOR([vfprintf])
+  gl_STDIO_MODULE_INDICATOR([vprintf])
+  gl_STDIO_MODULE_INDICATOR([fputc])
+  gl_STDIO_MODULE_INDICATOR([putc])
+  gl_STDIO_MODULE_INDICATOR([putchar])
+  gl_STDIO_MODULE_INDICATOR([fputs])
+  gl_STDIO_MODULE_INDICATOR([puts])
+  gl_STDIO_MODULE_INDICATOR([fwrite])
  gl_STDLIB_H
+  gl_STDLIB_H_REQUIRE_DEFAULTS
  if test $gl_cond_libtool = false; then
    gl_ltlibdeps="$gl_ltlibdeps $LTLIBICONV"
    gl_libdeps="$gl_libdeps $LIBICONV"
  fi
-  gl_HEADER_STRING_H
-  gl_HEADER_SYS_FILE_H
+  gl_STRING_H
+  gl_STRING_H_REQUIRE_DEFAULTS
+  gl_SYS_FILE_H
+  gl_SYS_FILE_H_REQUIRE_DEFAULTS
  AC_PROG_MKDIR_P
-  AC_REQUIRE([gl_HEADER_SYS_SELECT])
+  gl_SYS_SELECT_H
+  gl_SYS_SELECT_H_REQUIRE_DEFAULTS
  AC_PROG_MKDIR_P
-  AC_REQUIRE([gl_HEADER_SYS_SOCKET])
+  gl_SYS_SOCKET_H
+  gl_SYS_SOCKET_H_REQUIRE_DEFAULTS
  AC_PROG_MKDIR_P
-  gl_HEADER_SYS_STAT_H
+  gl_SYS_STAT_H
+  gl_SYS_STAT_H_REQUIRE_DEFAULTS
  AC_PROG_MKDIR_P
-  gl_HEADER_SYS_TIME_H
+  gl_SYS_TIME_H
+  gl_SYS_TIME_H_REQUIRE_DEFAULTS
  AC_PROG_MKDIR_P
  gl_SYS_TIMES_H
+  gl_SYS_TIMES_H_REQUIRE_DEFAULTS
  AC_PROG_MKDIR_P
  gl_SYS_TYPES_H
+  gl_SYS_TYPES_H_REQUIRE_DEFAULTS
  AC_PROG_MKDIR_P
-  gl_HEADER_SYS_UIO
+  gl_SYS_UIO_H
+  gl_SYS_UIO_H_REQUIRE_DEFAULTS
  AC_PROG_MKDIR_P
-  gl_HEADER_TIME_H
+  gl_TIME_H
+  gl_TIME_H_REQUIRE_DEFAULTS
  gl_TIME_RZ
  if test $HAVE_TIMEZONE_T = 0; then
    AC_LIBOBJ([time_rz])
@ -746,9 +794,11 @@ AC_DEFUN([gl_INIT],
  fi
  gl_MATH_MODULE_INDICATOR([trunc])
  gl_UNISTD_H
+  gl_UNISTD_H_REQUIRE_DEFAULTS
  gl_FUNC_VSNPRINTF
  gl_STDIO_MODULE_INDICATOR([vsnprintf])
  gl_WCHAR_H
+  gl_WCHAR_H_REQUIRE_DEFAULTS
  gl_FUNC_WRITE
  if test $REPLACE_WRITE = 1; then
    AC_LIBOBJ([write])
@ -771,7 +821,6 @@ AC_DEFUN([gl_INIT],
  gl_gnulib_enabled_be453cec5eecf5731a274f2de7f2db36=false
  gl_gnulib_enabled_30838f5439487421042f2225bed3af76=false
  gl_gnulib_enabled_hostent=false
-  gl_gnulib_enabled_idx=false
  gl_gnulib_enabled_b1df7117b479d2da59d76deba468ee21=false
  gl_gnulib_enabled_3f0e593033d1fc2c127581960f641b66=false
  gl_gnulib_enabled_dbdf22868a5367f28bf18e0013ac6f8f=false
@ -880,7 +929,9 @@ AC_SUBST([LTALLOCA])
  func_gl_gnulib_m4code_dynarray ()
  {
    if ! $gl_gnulib_enabled_dynarray; then
+      AC_PROG_MKDIR_P
      gl_gnulib_enabled_dynarray=true
+      func_gl_gnulib_m4code_37f71b604aa9c54446783d80f42fe547
      func_gl_gnulib_m4code_21ee726a3540c09237a8e70c0baf7467
    fi
  }
@ -963,12 +1014,6 @@ AC_SUBST([LTALLOCA])
      gl_gnulib_enabled_hostent=true
    fi
  }
-  func_gl_gnulib_m4code_idx ()
-  {
-    if ! $gl_gnulib_enabled_idx; then
-      gl_gnulib_enabled_idx=true
-    fi
-  }
  func_gl_gnulib_m4code_b1df7117b479d2da59d76deba468ee21 ()
  {
    if ! $gl_gnulib_enabled_b1df7117b479d2da59d76deba468ee21; then
@ -1181,7 +1226,6 @@ AC_SUBST([LTALLOCA])
        AC_LIBOBJ([realloc])
      fi
      gl_STDLIB_MODULE_INDICATOR([realloc-posix])
-      gl_MODULE_INDICATOR([realloc-posix])
      gl_gnulib_enabled_61bcaca76b3e6f9ae55d57a1c3193bc4=true
    fi
  }
@ -1205,7 +1249,9 @@ AC_SUBST([LTALLOCA])
  func_gl_gnulib_m4code_scratch_buffer ()
  {
    if ! $gl_gnulib_enabled_scratch_buffer; then
+      AC_PROG_MKDIR_P
      gl_gnulib_enabled_scratch_buffer=true
+      func_gl_gnulib_m4code_37f71b604aa9c54446783d80f42fe547
      func_gl_gnulib_m4code_21ee726a3540c09237a8e70c0baf7467
      func_gl_gnulib_m4code_61bcaca76b3e6f9ae55d57a1c3193bc4
    fi
@ -1319,7 +1365,8 @@ AC_SUBST([LTALLOCA])
  func_gl_gnulib_m4code_sys_random ()
  {
    if ! $gl_gnulib_enabled_sys_random; then
-      gl_HEADER_SYS_RANDOM
+      gl_SYS_RANDOM_H
+      gl_SYS_RANDOM_H_REQUIRE_DEFAULTS
      AC_PROG_MKDIR_P
      gl_gnulib_enabled_sys_random=true
    fi
@ -1416,6 +1463,7 @@ AC_SUBST([LTALLOCA])
  {
    if ! $gl_gnulib_enabled_3dcce957eadc896e63ab5f137947b410; then
      gl_WCTYPE_H
+      gl_WCTYPE_H_REQUIRE_DEFAULTS
      gl_gnulib_enabled_3dcce957eadc896e63ab5f137947b410=true
    fi
  }
@ -1430,9 +1478,6 @@ AC_SUBST([LTALLOCA])
  if test $HAVE_CANONICALIZE_FILE_NAME = 0 || test $REPLACE_CANONICALIZE_FILE_NAME = 1; then
    func_gl_gnulib_m4code_925677f0343de64b89a9f0c790b4104c
  fi
-  if test $HAVE_CANONICALIZE_FILE_NAME = 0 || test $REPLACE_CANONICALIZE_FILE_NAME = 1; then
-    func_gl_gnulib_m4code_idx
-  fi
  if test $HAVE_CANONICALIZE_FILE_NAME = 0 || test $REPLACE_CANONICALIZE_FILE_NAME = 1; then
    func_gl_gnulib_m4code_21ee726a3540c09237a8e70c0baf7467
  fi
@ -1583,9 +1628,6 @@ AC_SUBST([LTALLOCA])
  if test "$ac_cv_header_winsock2_h" = yes; then
    func_gl_gnulib_m4code_sockets
  fi
-  if test $HAVE_TIMEZONE_T = 0; then
-    func_gl_gnulib_m4code_idx
-  fi
  if test $HAVE_TIMEZONE_T = 0; then
    func_gl_gnulib_m4code_time_r
  fi
@ -1621,7 +1663,6 @@ AC_SUBST([LTALLOCA])
  AM_CONDITIONAL([gl_GNULIB_ENABLED_be453cec5eecf5731a274f2de7f2db36], [$gl_gnulib_enabled_be453cec5eecf5731a274f2de7f2db36])
  AM_CONDITIONAL([gl_GNULIB_ENABLED_30838f5439487421042f2225bed3af76], [$gl_gnulib_enabled_30838f5439487421042f2225bed3af76])
  AM_CONDITIONAL([gl_GNULIB_ENABLED_hostent], [$gl_gnulib_enabled_hostent])
-  AM_CONDITIONAL([gl_GNULIB_ENABLED_idx], [$gl_gnulib_enabled_idx])
  AM_CONDITIONAL([gl_GNULIB_ENABLED_b1df7117b479d2da59d76deba468ee21], [$gl_gnulib_enabled_b1df7117b479d2da59d76deba468ee21])
  AM_CONDITIONAL([gl_GNULIB_ENABLED_3f0e593033d1fc2c127581960f641b66], [$gl_gnulib_enabled_3f0e593033d1fc2c127581960f641b66])
  AM_CONDITIONAL([gl_GNULIB_ENABLED_dbdf22868a5367f28bf18e0013ac6f8f], [$gl_gnulib_enabled_dbdf22868a5367f28bf18e0013ac6f8f])
@ -1673,6 +1714,8 @@ AC_SUBST([LTALLOCA])
      m4_if(m4_sysval, [0], [],
        [AC_FATAL([expected source file, required through AC_LIBSOURCES, not found])])
  ])
+  m4_popdef([GL_MODULE_INDICATOR_PREFIX])
+  m4_popdef([GL_MACRO_PREFIX])
  m4_popdef([gl_LIBSOURCES_DIR])
  m4_popdef([gl_LIBSOURCES_LIST])
  m4_popdef([AC_LIBSOURCES])
@ -1699,6 +1742,8 @@ AC_SUBST([LTALLOCA])
  m4_pushdef([AC_LIBSOURCES], m4_defn([gltests_LIBSOURCES]))
  m4_pushdef([gltests_LIBSOURCES_LIST], [])
  m4_pushdef([gltests_LIBSOURCES_DIR], [])
+  m4_pushdef([GL_MACRO_PREFIX], [gltests])
+  m4_pushdef([GL_MODULE_INDICATOR_PREFIX], [GL])
  gl_COMMON
  gl_source_base='tests'
 changequote(,)dnl
@ -1720,6 +1765,8 @@ changequote([, ])dnl
      m4_if(m4_sysval, [0], [],
        [AC_FATAL([expected source file, required through AC_LIBSOURCES, not found])])
  ])
+  m4_popdef([GL_MODULE_INDICATOR_PREFIX])
+  m4_popdef([GL_MACRO_PREFIX])
  m4_popdef([gltests_LIBSOURCES_DIR])
  m4_popdef([gltests_LIBSOURCES_LIST])
  m4_popdef([AC_LIBSOURCES])
@ -2265,6 +2312,7 @@ AC_DEFUN([gl_FILE_LIST], [
  m4/wint_t.m4
  m4/write.m4
  m4/xsize.m4
+  m4/year2038.m4
  m4/zzgnulib.m4
  top/GNUmakefile
  top/maint.mk
--- a/m4/hostent.m4
+++ b/m4/hostent.m4
@ -1,4 +1,4 @@
-# hostent.m4 serial 3
+# hostent.m4 serial 4
 dnl Copyright (C) 2008, 2010-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@ -13,7 +13,7 @@ AC_DEFUN([gl_HOSTENT],
  dnl - On BeOS, they are in libnet.
  dnl - On native Windows, they are in ws2_32.dll.
  dnl - Otherwise they are in libc.
-  AC_REQUIRE([gl_HEADER_SYS_SOCKET])dnl for HAVE_SYS_SOCKET_H, HAVE_WINSOCK2_H
+  AC_REQUIRE([gl_SYS_SOCKET_H])dnl for HAVE_SYS_SOCKET_H, HAVE_WINSOCK2_H
  HOSTENT_LIB=
  gl_saved_libs="$LIBS"
  AC_SEARCH_LIBS([gethostbyname], [nsl network net],
--- a/m4/iconv_h.m4
+++ b/m4/iconv_h.m4
@ -1,10 +1,10 @@
-# iconv_h.m4 serial 12
+# iconv_h.m4 serial 15
 dnl Copyright (C) 2007-2021 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_ICONV_H],
+AC_DEFUN_ONCE([gl_ICONV_H],
 [
  AC_REQUIRE([gl_ICONV_H_DEFAULTS])

@ -24,22 +24,37 @@ AC_DEFUN([gl_ICONV_H],
 dnl Unconditionally enables the replacement of <iconv.h>.
 AC_DEFUN([gl_REPLACE_ICONV_H],
 [
-  AC_REQUIRE([gl_ICONV_H_DEFAULTS])
+  gl_ICONV_H_REQUIRE_DEFAULTS
  ICONV_H='iconv.h'
  AM_CONDITIONAL([GL_GENERATE_ICONV_H], [test -n "$ICONV_H"])
 ])

+# gl_ICONV_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_ICONV_MODULE_INDICATOR],
 [
-  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
-  AC_REQUIRE([gl_ICONV_H_DEFAULTS])
+  dnl Ensure to expand the default settings once only.
+  gl_ICONV_H_REQUIRE_DEFAULTS
  gl_MODULE_INDICATOR_SET_VARIABLE([$1])
 ])

+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_ICONV_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_ICONV_H_MODULE_INDICATOR_DEFAULTS], [
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ICONV])
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_ICONV_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_ICONV_H_DEFAULTS])
+])
+
 AC_DEFUN([gl_ICONV_H_DEFAULTS],
 [
  m4_ifdef([gl_ANSI_CXX], [AC_REQUIRE([gl_ANSI_CXX])])
-  GNULIB_ICONV=0;       AC_SUBST([GNULIB_ICONV])
  dnl Assume proper GNU behavior unless another module says otherwise.
  ICONV_CONST=;         AC_SUBST([ICONV_CONST])
  REPLACE_ICONV=0;      AC_SUBST([REPLACE_ICONV])
--- a/m4/inttypes.m4
+++ b/m4/inttypes.m4
@ -1,4 +1,4 @@
-# inttypes.m4 serial 32
+# inttypes.m4 serial 35
 dnl Copyright (C) 2006-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@ -7,7 +7,7 @@ dnl with or without modifications, as long as this notice is preserved.
 dnl From Derek Price, Bruno Haible.
 dnl Test whether <inttypes.h> is supported or must be substituted.

-AC_DEFUN([gl_INTTYPES_H],
+AC_DEFUN_ONCE([gl_INTTYPES_H],
 [
  AC_REQUIRE([gl_INTTYPES_INCOMPLETE])
  gl_INTTYPES_PRI_SCN
@ -136,19 +136,34 @@ AC_DEFUN([gl_INTTYPES_CHECK_LONG_LONG_INT_CONDITION],
  AC_SUBST([$1])
 ])

+# gl_INTTYPES_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_INTTYPES_MODULE_INDICATOR],
 [
-  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
-  AC_REQUIRE([gl_INTTYPES_H_DEFAULTS])
+  dnl Ensure to expand the default settings once only.
+  gl_INTTYPES_H_REQUIRE_DEFAULTS
  gl_MODULE_INDICATOR_SET_VARIABLE([$1])
 ])

+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_INTTYPES_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_INTTYPES_H_MODULE_INDICATOR_DEFAULTS], [
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_IMAXABS])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_IMAXDIV])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRTOIMAX])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRTOUMAX])
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_INTTYPES_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_INTTYPES_H_DEFAULTS])
+])
+
 AC_DEFUN([gl_INTTYPES_H_DEFAULTS],
 [
-  GNULIB_IMAXABS=0;      AC_SUBST([GNULIB_IMAXABS])
-  GNULIB_IMAXDIV=0;      AC_SUBST([GNULIB_IMAXDIV])
-  GNULIB_STRTOIMAX=0;    AC_SUBST([GNULIB_STRTOIMAX])
-  GNULIB_STRTOUMAX=0;    AC_SUBST([GNULIB_STRTOUMAX])
  dnl Assume proper GNU behavior unless another module says otherwise.
  HAVE_DECL_IMAXABS=1;   AC_SUBST([HAVE_DECL_IMAXABS])
  HAVE_DECL_IMAXDIV=1;   AC_SUBST([HAVE_DECL_IMAXDIV])
--- a/m4/langinfo_h.m4
+++ b/m4/langinfo_h.m4
@ -1,10 +1,10 @@
-# langinfo_h.m4 serial 9
+# langinfo_h.m4 serial 12
 dnl Copyright (C) 2009-2021 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_LANGINFO_H],
+AC_DEFUN_ONCE([gl_LANGINFO_H],
 [
  AC_REQUIRE([gl_LANGINFO_H_DEFAULTS])

@ -104,18 +104,33 @@ int a = YESEXPR;
    ]], [nl_langinfo])
 ])

+# gl_LANGINFO_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_LANGINFO_MODULE_INDICATOR],
 [
-  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
-  AC_REQUIRE([gl_LANGINFO_H_DEFAULTS])
+  dnl Ensure to expand the default settings once only.
+  gl_LANGINFO_H_REQUIRE_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])
 ])

+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_LANGINFO_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_LANGINFO_H_MODULE_INDICATOR_DEFAULTS], [
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_NL_LANGINFO])
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_LANGINFO_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_LANGINFO_H_DEFAULTS])
+])
+
 AC_DEFUN([gl_LANGINFO_H_DEFAULTS],
 [
-  GNULIB_NL_LANGINFO=0;  AC_SUBST([GNULIB_NL_LANGINFO])
  dnl Assume proper GNU behavior unless another module says otherwise.
  HAVE_NL_LANGINFO=1;    AC_SUBST([HAVE_NL_LANGINFO])
  REPLACE_NL_LANGINFO=0; AC_SUBST([REPLACE_NL_LANGINFO])
--- a/m4/largefile.m4
+++ b/m4/largefile.m4
@ -22,7 +22,8 @@ AC_DEFUN([gl_SET_LARGEFILE_SOURCE],
  esac
 ])

-# The following implementation works around a problem in autoconf <= 2.69;
+# Work around a problem in Autoconf through at least 2.71 on glibc 2.34+
+# with _TIME_BITS.  Also, work 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], [], [
@ -40,6 +41,7 @@ m4_define([_AC_SYS_LARGEFILE_TEST_INCLUDES],
                       && LARGE_OFF_T % 2147483647 == 1)
                      ? 1 : -1]];[]dnl
 ])
+])# m4_version_prereq 2.70


 # _AC_SYS_LARGEFILE_MACRO_VALUE(C-MACRO, VALUE,
@ -54,7 +56,8 @@ 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([#undef $1
+#define $1 $2
 $5], [$6])],
    [$3=$2; break])
  $3=unknown
@ -80,9 +83,8 @@ rm -rf conftest*[]dnl
 AC_DEFUN([AC_SYS_LARGEFILE],
 [AC_ARG_ENABLE(largefile,
               [  --disable-largefile     omit support for large files])
-if test "$enable_largefile" != no; then
-
-  AC_CACHE_CHECK([for special C compiler options needed for large files],
+AS_IF([test "$enable_largefile" != no],
+ [AC_CACHE_CHECK([for special C compiler options needed for large files],
    ac_cv_sys_largefile_CC,
    [ac_cv_sys_largefile_CC=no
     if test "$GCC" != yes; then
@ -107,15 +109,15 @@ if test "$enable_largefile" != no; then
    ac_cv_sys_file_offset_bits,
    [Number of bits in a file offset, on hosts where this is settable.],
    [_AC_SYS_LARGEFILE_TEST_INCLUDES])
-  if test $ac_cv_sys_file_offset_bits = unknown; then
-    _AC_SYS_LARGEFILE_MACRO_VALUE(_LARGE_FILES, 1,
-      ac_cv_sys_large_files,
-      [Define for large files, on AIX-style hosts.],
-      [_AC_SYS_LARGEFILE_TEST_INCLUDES])
-  fi
-fi
+  AS_CASE([$ac_cv_sys_file_offset_bits],
+    [unknown],
+      [_AC_SYS_LARGEFILE_MACRO_VALUE([_LARGE_FILES], [1],
+         [ac_cv_sys_large_files],
+         [Define for large files, on AIX-style hosts.],
+         [_AC_SYS_LARGEFILE_TEST_INCLUDES])],
+    [64],
+      [gl_YEAR2038_BODY([])])])
 ])# AC_SYS_LARGEFILE
-])# m4_version_prereq 2.70

 # Enable large files on systems where this is implemented by Gnulib, not by the
 # system headers.
--- a/m4/limits-h.m4
+++ b/m4/limits-h.m4
@ -11,7 +11,7 @@ AC_DEFUN_ONCE([gl_LIMITS_H],
 [
  gl_CHECK_NEXT_HEADERS([limits.h])

-  AC_CACHE_CHECK([whether limits.h has LLONG_MAX, WORD_BIT, ULLONG_WIDTH etc.],
+  AC_CACHE_CHECK([whether limits.h has WORD_BIT, BOOL_WIDTH etc.],
    [gl_cv_header_limits_width],
    [AC_COMPILE_IFELSE(
       [AC_LANG_PROGRAM(
@ -22,6 +22,7 @@ AC_DEFUN_ONCE([gl_LIMITS_H],
            long long llm = LLONG_MAX;
            int wb = WORD_BIT;
            int ullw = ULLONG_WIDTH;
+            int bw = BOOL_WIDTH;
          ]])],
       [gl_cv_header_limits_width=yes],
       [gl_cv_header_limits_width=no])])
--- a/m4/locale_h.m4
+++ b/m4/locale_h.m4
@ -1,13 +1,13 @@
-# locale_h.m4 serial 25
+# locale_h.m4 serial 28
 dnl Copyright (C) 2007, 2009-2021 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_LOCALE_H],
+AC_DEFUN_ONCE([gl_LOCALE_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.
+  dnl Ensure to expand the default settings once only, before all statements
+  dnl that occur in other macros.
  AC_REQUIRE([gl_LOCALE_H_DEFAULTS])

  dnl Persuade glibc <locale.h> to define locale_t and the int_p_*, int_n_*
@ -129,22 +129,37 @@ AC_DEFUN([gl_LOCALE_T],
  AC_SUBST([HAVE_XLOCALE_H])
 ])

+# gl_LOCALE_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_LOCALE_MODULE_INDICATOR],
 [
-  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
-  AC_REQUIRE([gl_LOCALE_H_DEFAULTS])
+  dnl Ensure to expand the default settings once only.
+  gl_LOCALE_H_REQUIRE_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])
 ])

+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_LOCALE_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_LOCALE_H_MODULE_INDICATOR_DEFAULTS], [
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LOCALECONV])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SETLOCALE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SETLOCALE_NULL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_DUPLOCALE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LOCALENAME])
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_LOCALE_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_LOCALE_H_DEFAULTS])
+])
+
 AC_DEFUN([gl_LOCALE_H_DEFAULTS],
 [
-  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])
--- a/m4/malloc.m4
+++ b/m4/malloc.m4
@ -1,21 +1,21 @@
-# malloc.m4 serial 22
+# malloc.m4 serial 27
 dnl Copyright (C) 2007, 2009-2021 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
+# https://git.savannah.gnu.org/cgit/autoconf.git/tree/lib/autoconf/functions.m4?id=v2.70#n949
 AC_DEFUN([_AC_FUNC_MALLOC_IF],
 [
  AC_REQUIRE([AC_CANONICAL_HOST])dnl for cross-compiles
-  AC_CACHE_CHECK([for GNU libc compatible malloc],
+  AC_CACHE_CHECK([whether malloc (0) returns nonnull],
    [ac_cv_func_malloc_0_nonnull],
    [AC_RUN_IFELSE(
       [AC_LANG_PROGRAM(
          [[#include <stdlib.h>
          ]],
-          [[char *p = malloc (0);
+          [[void *p = malloc (0);
            int result = !p;
            free (p);
            return result;]])
@ -24,75 +24,151 @@ AC_DEFUN([_AC_FUNC_MALLOC_IF],
       [ac_cv_func_malloc_0_nonnull=no],
       [case "$host_os" in
          # Guess yes on platforms where we know the result.
-          *-gnu* | gnu* | *-musl* | freebsd* | midnightbsd* | netbsd* | openbsd* \
-          | hpux* | solaris* | cygwin* | mingw*)
+          *-gnu* | freebsd* | netbsd* | openbsd* | bitrig* \
+          | gnu* | *-musl* | midnightbsd* \
+          | hpux* | solaris* | cygwin* | mingw* | msys* )
            ac_cv_func_malloc_0_nonnull="guessing yes" ;;
          # If we don't know, obey --enable-cross-guesses.
          *) ac_cv_func_malloc_0_nonnull="$gl_cross_guess_normal" ;;
        esac
       ])
    ])
-  case "$ac_cv_func_malloc_0_nonnull" in
-    *yes)
-      $1
-      ;;
-    *)
-      $2
-      ;;
-  esac
+  AS_CASE([$ac_cv_func_malloc_0_nonnull], [*yes], [$1], [$2])
 ])# _AC_FUNC_MALLOC_IF

 # gl_FUNC_MALLOC_GNU
 # ------------------
-# Test whether 'malloc (0)' is handled like in GNU libc, and replace malloc if
-# it is not.
+# Replace malloc if it is not compatible with GNU libc.
 AC_DEFUN([gl_FUNC_MALLOC_GNU],
 [
  AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
-  dnl _AC_FUNC_MALLOC_IF is defined in Autoconf.
-  _AC_FUNC_MALLOC_IF(
-    [AC_DEFINE([HAVE_MALLOC_GNU], [1],
-               [Define to 1 if your system has a GNU libc compatible 'malloc'
-                function, and to 0 otherwise.])],
-    [AC_DEFINE([HAVE_MALLOC_GNU], [0])
-     REPLACE_MALLOC=1
+  AC_REQUIRE([gl_FUNC_MALLOC_POSIX])
+  if test $REPLACE_MALLOC = 0; then
+    _AC_FUNC_MALLOC_IF([], [REPLACE_MALLOC=1])
+  fi
+])
+
+# gl_FUNC_MALLOC_PTRDIFF
+# ----------------------
+# Test whether malloc (N) reliably fails when N exceeds PTRDIFF_MAX,
+# and replace malloc otherwise.
+AC_DEFUN([gl_FUNC_MALLOC_PTRDIFF],
+[
+  AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
+  AC_REQUIRE([gl_CHECK_MALLOC_PTRDIFF])
+  test "$gl_cv_malloc_ptrdiff" = yes || REPLACE_MALLOC=1
+])
+
+# Test whether malloc, realloc, calloc refuse to create objects
+# larger than what can be expressed in ptrdiff_t.
+# Set gl_cv_func_malloc_gnu to yes or no accordingly.
+AC_DEFUN([gl_CHECK_MALLOC_PTRDIFF],
+[
+  AC_CACHE_CHECK([whether malloc is ptrdiff_t safe],
+    [gl_cv_malloc_ptrdiff],
+    [AC_COMPILE_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[#include <stdint.h>
+          ]],
+          [[/* 64-bit ptrdiff_t is so wide that no practical platform
+               can exceed it.  */
+            #define WIDE_PTRDIFF (PTRDIFF_MAX >> 31 >> 31 != 0)
+
+            /* On rare machines where size_t fits in ptrdiff_t there
+               is no problem.  */
+            #define NARROW_SIZE (SIZE_MAX <= PTRDIFF_MAX)
+
+            /* glibc 2.30 and later malloc refuses to exceed ptrdiff_t
+               bounds even on 32-bit platforms.  We don't know which
+               non-glibc systems are safe.  */
+            #define KNOWN_SAFE (2 < __GLIBC__ + (30 <= __GLIBC_MINOR__))
+
+            #if WIDE_PTRDIFF || NARROW_SIZE || KNOWN_SAFE
+              return 0;
+            #else
+              #error "malloc might not be ptrdiff_t safe"
+              syntax error
+            #endif
+          ]])],
+       [gl_cv_malloc_ptrdiff=yes],
+       [gl_cv_malloc_ptrdiff=no])
    ])
 ])

 # gl_FUNC_MALLOC_POSIX
 # --------------------
 # Test whether 'malloc' is POSIX compliant (sets errno to ENOMEM when it
-# fails), and replace malloc if it is not.
+# fails, and doesn't mess up with ptrdiff_t overflow), and replace
+# malloc if it is not.
 AC_DEFUN([gl_FUNC_MALLOC_POSIX],
 [
  AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
+  AC_REQUIRE([gl_FUNC_MALLOC_PTRDIFF])
  AC_REQUIRE([gl_CHECK_MALLOC_POSIX])
-  if test $gl_cv_func_malloc_posix = yes; then
+  if test "$gl_cv_func_malloc_posix" = yes; then
    AC_DEFINE([HAVE_MALLOC_POSIX], [1],
-      [Define if the 'malloc' function is POSIX compliant.])
+      [Define if malloc, realloc, and calloc set errno on allocation failure.])
  else
    REPLACE_MALLOC=1
  fi
 ])

-# Test whether malloc, realloc, calloc are POSIX compliant,
+# Test whether malloc, realloc, calloc set errno to ENOMEM on failure.
 # Set gl_cv_func_malloc_posix to yes or no accordingly.
 AC_DEFUN([gl_CHECK_MALLOC_POSIX],
 [
-  AC_CACHE_CHECK([whether malloc, realloc, calloc are POSIX compliant],
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  AC_CACHE_CHECK([whether malloc, realloc, calloc set errno on failure],
    [gl_cv_func_malloc_posix],
    [
      dnl It is too dangerous to try to allocate a large amount of memory:
      dnl some systems go to their knees when you do that. So assume that
-      dnl all Unix implementations of the function are POSIX compliant.
-      AC_COMPILE_IFELSE(
-        [AC_LANG_PROGRAM(
-           [[]],
-           [[#if defined _WIN32 && ! defined __CYGWIN__
-             choke me
-             #endif
-            ]])],
-        [gl_cv_func_malloc_posix=yes],
-        [gl_cv_func_malloc_posix=no])
+      dnl all Unix implementations of the function set errno on failure,
+      dnl except on those platforms where we have seen 'test-malloc-gnu',
+      dnl 'test-realloc-gnu', 'test-calloc-gnu' fail.
+      case "$host_os" in
+        mingw*)
+          gl_cv_func_malloc_posix=no ;;
+        irix* | solaris*)
+          dnl On IRIX 6.5, the three functions return NULL with errno unset
+          dnl when the argument is larger than PTRDIFF_MAX.
+          dnl On Solaris 11.3, the three functions return NULL with errno set
+          dnl to EAGAIN, not ENOMEM, when the argument is larger than
+          dnl PTRDIFF_MAX.
+          dnl Here is a test program:
+m4_divert_push([KILL])
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#define ptrdiff_t long
+#ifndef PTRDIFF_MAX
+# define PTRDIFF_MAX ((ptrdiff_t) ((1UL << (8 * sizeof (ptrdiff_t) - 1)) - 1))
+#endif
+
+int main ()
+{
+  void *p;
+
+  fprintf (stderr, "PTRDIFF_MAX = %lu\n", (unsigned long) PTRDIFF_MAX);
+
+  errno = 0;
+  p = malloc ((unsigned long) PTRDIFF_MAX + 1);
+  fprintf (stderr, "p=%p errno=%d\n", p, errno);
+
+  errno = 0;
+  p = calloc (PTRDIFF_MAX / 2 + 1, 2);
+  fprintf (stderr, "p=%p errno=%d\n", p, errno);
+
+  errno = 0;
+  p = realloc (NULL, (unsigned long) PTRDIFF_MAX + 1);
+  fprintf (stderr, "p=%p errno=%d\n", p, errno);
+
+  return 0;
+}
+m4_divert_pop([KILL])
+          gl_cv_func_malloc_posix=no ;;
+        *)
+          gl_cv_func_malloc_posix=yes ;;
+      esac
    ])
 ])
--- a/m4/math_h.m4
+++ b/m4/math_h.m4
@ -1,10 +1,10 @@
-# math_h.m4 serial 122
+# math_h.m4 serial 125
 dnl Copyright (C) 2007-2021 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_MATH_H],
+AC_DEFUN_ONCE([gl_MATH_H],
 [
  AC_REQUIRE([gl_MATH_H_DEFAULTS])
  gl_CHECK_NEXT_HEADERS([math.h])
@ -53,119 +53,134 @@ AC_DEFUN([gl_MATH_H],
     tanf tanl tanhf trunc truncf truncl])
 ])

+# gl_MATH_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_MATH_MODULE_INDICATOR],
 [
-  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
-  AC_REQUIRE([gl_MATH_H_DEFAULTS])
+  dnl Ensure to expand the default settings once only.
+  gl_MATH_H_REQUIRE_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])
 ])

+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_MATH_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_MATH_H_MODULE_INDICATOR_DEFAULTS], [
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ACOSF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ACOSL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ASINF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ASINL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ATANF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ATANL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ATAN2F])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_CBRT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_CBRTF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_CBRTL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_CEIL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_CEILF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_CEILL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_COPYSIGN])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_COPYSIGNF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_COPYSIGNL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_COSF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_COSL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_COSHF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_EXPF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_EXPL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_EXP2])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_EXP2F])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_EXP2L])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_EXPM1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_EXPM1F])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_EXPM1L])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FABSF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FABSL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FLOOR])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FLOORF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FLOORL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FMA])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FMAF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FMAL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FMOD])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FMODF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FMODL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FREXPF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FREXP])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FREXPL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_HYPOT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_HYPOTF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_HYPOTL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ILOGB])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ILOGBF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ILOGBL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ISFINITE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ISINF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ISNAN])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ISNANF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ISNAND])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ISNANL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LDEXPF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LDEXPL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LOG])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LOGF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LOGL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LOG10])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LOG10F])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LOG10L])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LOG1P])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LOG1PF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LOG1PL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LOG2])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LOG2F])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LOG2L])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LOGB])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LOGBF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LOGBL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MODF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MODFF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MODFL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_POWF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_REMAINDER])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_REMAINDERF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_REMAINDERL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_RINT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_RINTF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_RINTL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ROUND])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ROUNDF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ROUNDL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SIGNBIT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SINF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SINL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SINHF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SQRTF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SQRTL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TANF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TANL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TANHF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TRUNC])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TRUNCF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TRUNCL])
+    dnl Support Microsoft deprecated alias function names by default.
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_J0], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_J1], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_JN], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_Y0], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_Y1], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_YN], [1])
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_MATH_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_MATH_H_DEFAULTS])
+])
+
 AC_DEFUN([gl_MATH_H_DEFAULTS],
 [
-  GNULIB_ACOSF=0;      AC_SUBST([GNULIB_ACOSF])
-  GNULIB_ACOSL=0;      AC_SUBST([GNULIB_ACOSL])
-  GNULIB_ASINF=0;      AC_SUBST([GNULIB_ASINF])
-  GNULIB_ASINL=0;      AC_SUBST([GNULIB_ASINL])
-  GNULIB_ATANF=0;      AC_SUBST([GNULIB_ATANF])
-  GNULIB_ATANL=0;      AC_SUBST([GNULIB_ATANL])
-  GNULIB_ATAN2F=0;     AC_SUBST([GNULIB_ATAN2F])
-  GNULIB_CBRT=0;       AC_SUBST([GNULIB_CBRT])
-  GNULIB_CBRTF=0;      AC_SUBST([GNULIB_CBRTF])
-  GNULIB_CBRTL=0;      AC_SUBST([GNULIB_CBRTL])
-  GNULIB_CEIL=0;       AC_SUBST([GNULIB_CEIL])
-  GNULIB_CEILF=0;      AC_SUBST([GNULIB_CEILF])
-  GNULIB_CEILL=0;      AC_SUBST([GNULIB_CEILL])
-  GNULIB_COPYSIGN=0;   AC_SUBST([GNULIB_COPYSIGN])
-  GNULIB_COPYSIGNF=0;  AC_SUBST([GNULIB_COPYSIGNF])
-  GNULIB_COPYSIGNL=0;  AC_SUBST([GNULIB_COPYSIGNL])
-  GNULIB_COSF=0;       AC_SUBST([GNULIB_COSF])
-  GNULIB_COSL=0;       AC_SUBST([GNULIB_COSL])
-  GNULIB_COSHF=0;      AC_SUBST([GNULIB_COSHF])
-  GNULIB_EXPF=0;       AC_SUBST([GNULIB_EXPF])
-  GNULIB_EXPL=0;       AC_SUBST([GNULIB_EXPL])
-  GNULIB_EXP2=0;       AC_SUBST([GNULIB_EXP2])
-  GNULIB_EXP2F=0;      AC_SUBST([GNULIB_EXP2F])
-  GNULIB_EXP2L=0;      AC_SUBST([GNULIB_EXP2L])
-  GNULIB_EXPM1=0;      AC_SUBST([GNULIB_EXPM1])
-  GNULIB_EXPM1F=0;     AC_SUBST([GNULIB_EXPM1F])
-  GNULIB_EXPM1L=0;     AC_SUBST([GNULIB_EXPM1L])
-  GNULIB_FABSF=0;      AC_SUBST([GNULIB_FABSF])
-  GNULIB_FABSL=0;      AC_SUBST([GNULIB_FABSL])
-  GNULIB_FLOOR=0;      AC_SUBST([GNULIB_FLOOR])
-  GNULIB_FLOORF=0;     AC_SUBST([GNULIB_FLOORF])
-  GNULIB_FLOORL=0;     AC_SUBST([GNULIB_FLOORL])
-  GNULIB_FMA=0;        AC_SUBST([GNULIB_FMA])
-  GNULIB_FMAF=0;       AC_SUBST([GNULIB_FMAF])
-  GNULIB_FMAL=0;       AC_SUBST([GNULIB_FMAL])
-  GNULIB_FMOD=0;       AC_SUBST([GNULIB_FMOD])
-  GNULIB_FMODF=0;      AC_SUBST([GNULIB_FMODF])
-  GNULIB_FMODL=0;      AC_SUBST([GNULIB_FMODL])
-  GNULIB_FREXPF=0;     AC_SUBST([GNULIB_FREXPF])
-  GNULIB_FREXP=0;      AC_SUBST([GNULIB_FREXP])
-  GNULIB_FREXPL=0;     AC_SUBST([GNULIB_FREXPL])
-  GNULIB_HYPOT=0;      AC_SUBST([GNULIB_HYPOT])
-  GNULIB_HYPOTF=0;     AC_SUBST([GNULIB_HYPOTF])
-  GNULIB_HYPOTL=0;     AC_SUBST([GNULIB_HYPOTL])
-  GNULIB_ILOGB=0;      AC_SUBST([GNULIB_ILOGB])
-  GNULIB_ILOGBF=0;     AC_SUBST([GNULIB_ILOGBF])
-  GNULIB_ILOGBL=0;     AC_SUBST([GNULIB_ILOGBL])
-  GNULIB_ISFINITE=0;   AC_SUBST([GNULIB_ISFINITE])
-  GNULIB_ISINF=0;      AC_SUBST([GNULIB_ISINF])
-  GNULIB_ISNAN=0;      AC_SUBST([GNULIB_ISNAN])
-  GNULIB_ISNANF=0;     AC_SUBST([GNULIB_ISNANF])
-  GNULIB_ISNAND=0;     AC_SUBST([GNULIB_ISNAND])
-  GNULIB_ISNANL=0;     AC_SUBST([GNULIB_ISNANL])
-  GNULIB_LDEXPF=0;     AC_SUBST([GNULIB_LDEXPF])
-  GNULIB_LDEXPL=0;     AC_SUBST([GNULIB_LDEXPL])
-  GNULIB_LOG=0;        AC_SUBST([GNULIB_LOG])
-  GNULIB_LOGF=0;       AC_SUBST([GNULIB_LOGF])
-  GNULIB_LOGL=0;       AC_SUBST([GNULIB_LOGL])
-  GNULIB_LOG10=0;      AC_SUBST([GNULIB_LOG10])
-  GNULIB_LOG10F=0;     AC_SUBST([GNULIB_LOG10F])
-  GNULIB_LOG10L=0;     AC_SUBST([GNULIB_LOG10L])
-  GNULIB_LOG1P=0;      AC_SUBST([GNULIB_LOG1P])
-  GNULIB_LOG1PF=0;     AC_SUBST([GNULIB_LOG1PF])
-  GNULIB_LOG1PL=0;     AC_SUBST([GNULIB_LOG1PL])
-  GNULIB_LOG2=0;       AC_SUBST([GNULIB_LOG2])
-  GNULIB_LOG2F=0;      AC_SUBST([GNULIB_LOG2F])
-  GNULIB_LOG2L=0;      AC_SUBST([GNULIB_LOG2L])
-  GNULIB_LOGB=0;       AC_SUBST([GNULIB_LOGB])
-  GNULIB_LOGBF=0;      AC_SUBST([GNULIB_LOGBF])
-  GNULIB_LOGBL=0;      AC_SUBST([GNULIB_LOGBL])
-  GNULIB_MODF=0;       AC_SUBST([GNULIB_MODF])
-  GNULIB_MODFF=0;      AC_SUBST([GNULIB_MODFF])
-  GNULIB_MODFL=0;      AC_SUBST([GNULIB_MODFL])
-  GNULIB_POWF=0;       AC_SUBST([GNULIB_POWF])
-  GNULIB_REMAINDER=0;  AC_SUBST([GNULIB_REMAINDER])
-  GNULIB_REMAINDERF=0; AC_SUBST([GNULIB_REMAINDERF])
-  GNULIB_REMAINDERL=0; AC_SUBST([GNULIB_REMAINDERL])
-  GNULIB_RINT=0;       AC_SUBST([GNULIB_RINT])
-  GNULIB_RINTF=0;      AC_SUBST([GNULIB_RINTF])
-  GNULIB_RINTL=0;      AC_SUBST([GNULIB_RINTL])
-  GNULIB_ROUND=0;      AC_SUBST([GNULIB_ROUND])
-  GNULIB_ROUNDF=0;     AC_SUBST([GNULIB_ROUNDF])
-  GNULIB_ROUNDL=0;     AC_SUBST([GNULIB_ROUNDL])
-  GNULIB_SIGNBIT=0;    AC_SUBST([GNULIB_SIGNBIT])
-  GNULIB_SINF=0;       AC_SUBST([GNULIB_SINF])
-  GNULIB_SINL=0;       AC_SUBST([GNULIB_SINL])
-  GNULIB_SINHF=0;      AC_SUBST([GNULIB_SINHF])
-  GNULIB_SQRTF=0;      AC_SUBST([GNULIB_SQRTF])
-  GNULIB_SQRTL=0;      AC_SUBST([GNULIB_SQRTL])
-  GNULIB_TANF=0;       AC_SUBST([GNULIB_TANF])
-  GNULIB_TANL=0;       AC_SUBST([GNULIB_TANL])
-  GNULIB_TANHF=0;      AC_SUBST([GNULIB_TANHF])
-  GNULIB_TRUNC=0;      AC_SUBST([GNULIB_TRUNC])
-  GNULIB_TRUNCF=0;     AC_SUBST([GNULIB_TRUNCF])
-  GNULIB_TRUNCL=0;     AC_SUBST([GNULIB_TRUNCL])
-  dnl Support Microsoft deprecated alias function names by default.
-  GNULIB_MDA_J0=1;     AC_SUBST([GNULIB_MDA_J0])
-  GNULIB_MDA_J1=1;     AC_SUBST([GNULIB_MDA_J1])
-  GNULIB_MDA_JN=1;     AC_SUBST([GNULIB_MDA_JN])
-  GNULIB_MDA_Y0=1;     AC_SUBST([GNULIB_MDA_Y0])
-  GNULIB_MDA_Y1=1;     AC_SUBST([GNULIB_MDA_Y1])
-  GNULIB_MDA_YN=1;     AC_SUBST([GNULIB_MDA_YN])
  dnl Assume proper GNU behavior unless another module says otherwise.
  HAVE_ACOSF=1;                     AC_SUBST([HAVE_ACOSF])
  HAVE_ACOSL=1;                     AC_SUBST([HAVE_ACOSL])
--- a/m4/memchr.m4
+++ b/m4/memchr.m4
@ -1,4 +1,4 @@
-# memchr.m4 serial 17
+# memchr.m4 serial 18
 dnl Copyright (C) 2002-2004, 2009-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@ -13,7 +13,7 @@ AC_DEFUN_ONCE([gl_FUNC_MEMCHR],
  AC_CHECK_HEADERS_ONCE([sys/mman.h])
  AC_CHECK_FUNCS_ONCE([mprotect])

-  AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
+  AC_REQUIRE([gl_STRING_H_DEFAULTS])
  # 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
--- a/m4/mempcpy.m4
+++ b/m4/mempcpy.m4
@ -1,4 +1,4 @@
-# mempcpy.m4 serial 11
+# mempcpy.m4 serial 12
 dnl Copyright (C) 2003-2004, 2006-2007, 2009-2021 Free Software Foundation,
 dnl Inc.
 dnl This file is free software; the Free Software Foundation
@ -13,7 +13,7 @@ AC_DEFUN([gl_FUNC_MEMPCPY],
  dnl The mempcpy() declaration in lib/string.in.h uses 'restrict'.
  AC_REQUIRE([AC_C_RESTRICT])

-  AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
+  AC_REQUIRE([gl_STRING_H_DEFAULTS])
  AC_CHECK_FUNCS([mempcpy])
  if test $ac_cv_func_mempcpy = no; then
    HAVE_MEMPCPY=0
--- a/m4/mktime.m4
+++ b/m4/mktime.m4
@ -1,4 +1,4 @@
-# serial 35
+# serial 36
 dnl Copyright (C) 2002-2003, 2005-2007, 2009-2021 Free Software Foundation,
 dnl Inc.
 dnl This file is free software; the Free Software Foundation
@ -255,7 +255,7 @@ main ()
 dnl Main macro of module 'mktime'.
 AC_DEFUN([gl_FUNC_MKTIME],
 [
-  AC_REQUIRE([gl_HEADER_TIME_H_DEFAULTS])
+  AC_REQUIRE([gl_TIME_H_DEFAULTS])
  AC_REQUIRE([AC_CANONICAL_HOST])
  AC_REQUIRE([gl_FUNC_MKTIME_WORKS])

--- a/m4/netdb_h.m4
+++ b/m4/netdb_h.m4
@ -1,10 +1,10 @@
-# netdb_h.m4 serial 12
+# netdb_h.m4 serial 15
 dnl Copyright (C) 2008-2021 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_NETDB],
+AC_DEFUN_ONCE([gl_NETDB_H],
 [
  AC_REQUIRE([gl_NETDB_H_DEFAULTS])
  gl_CHECK_NEXT_HEADERS([netdb.h])
@ -21,18 +21,33 @@ AC_DEFUN([gl_HEADER_NETDB],
    [getaddrinfo freeaddrinfo gai_strerror getnameinfo])
 ])

+# gl_NETDB_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_NETDB_MODULE_INDICATOR],
 [
-  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
-  AC_REQUIRE([gl_NETDB_H_DEFAULTS])
+  dnl Ensure to expand the default settings once only.
+  gl_NETDB_H_REQUIRE_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])
 ])

+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_NETDB_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_NETDB_H_MODULE_INDICATOR_DEFAULTS], [
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETADDRINFO])
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_NETDB_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_NETDB_H_DEFAULTS])
+])
+
 AC_DEFUN([gl_NETDB_H_DEFAULTS],
 [
-  GNULIB_GETADDRINFO=0; AC_SUBST([GNULIB_GETADDRINFO])
  dnl Assume proper GNU behavior unless another module says otherwise.
  HAVE_STRUCT_ADDRINFO=1;   AC_SUBST([HAVE_STRUCT_ADDRINFO])
  HAVE_DECL_FREEADDRINFO=1; AC_SUBST([HAVE_DECL_FREEADDRINFO])
--- a/m4/poll_h.m4
+++ b/m4/poll_h.m4
@ -1,4 +1,4 @@
-# poll_h.m4 serial 3
+# poll_h.m4 serial 6
 dnl Copyright (C) 2010-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@ -6,10 +6,10 @@ dnl with or without modifications, as long as this notice is preserved.

 dnl Written by Bruno Haible.

-AC_DEFUN([gl_POLL_H],
+AC_DEFUN_ONCE([gl_POLL_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.
+  dnl Ensure to expand the default settings once only, before all statements
+  dnl that occur in other macros.
  AC_REQUIRE([gl_POLL_H_DEFAULTS])

  AC_CHECK_HEADERS_ONCE([poll.h])
@ -31,18 +31,33 @@ AC_DEFUN([gl_POLL_H],
    [poll])
 ])

+# gl_POLL_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_POLL_MODULE_INDICATOR],
 [
-  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
-  AC_REQUIRE([gl_POLL_H_DEFAULTS])
+  dnl Ensure to expand the default settings once only.
+  gl_POLL_H_REQUIRE_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])
 ])

+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_POLL_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_POLL_H_MODULE_INDICATOR_DEFAULTS], [
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_POLL])
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_POLL_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_POLL_H_DEFAULTS])
+])
+
 AC_DEFUN([gl_POLL_H_DEFAULTS],
 [
-  GNULIB_POLL=0;        AC_SUBST([GNULIB_POLL])
  dnl Assume proper GNU behavior unless another module says otherwise.
  HAVE_POLL=1;          AC_SUBST([HAVE_POLL])
  REPLACE_POLL=0;       AC_SUBST([REPLACE_POLL])
--- a/m4/printf.m4
+++ b/m4/printf.m4
@ -1,4 +1,4 @@
-# printf.m4 serial 72
+# printf.m4 serial 73
 dnl Copyright (C) 2003, 2007-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@ -537,7 +537,7 @@ int main ()
          && strcmp (buf, "-0X6.488P-1 33") != 0
          && strcmp (buf, "-0XC.91P-2 33") != 0))
    result |= 2;
-  /* This catches a FreeBSD 6.1 bug: it doesn't round.  */
+  /* This catches a FreeBSD 13.0 bug: it doesn't round.  */
  if (sprintf (buf, "%.2a %d", 1.51, 33, 44, 55) < 0
      || (strcmp (buf, "0x1.83p+0 33") != 0
          && strcmp (buf, "0x3.05p-1 33") != 0
@ -1690,6 +1690,7 @@ dnl
 dnl                                  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20
 dnl   glibc 2.5                      .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
 dnl   glibc 2.3.6                    .  .  .  .  #  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
+dnl   FreeBSD 13.0                   .  .  .  .  #  .  .  .  .  .  .  .  .  #  .  .  .  .  .  .
 dnl   FreeBSD 5.4, 6.1               .  .  .  .  #  .  .  .  .  .  .  #  .  #  .  .  .  .  .  .
 dnl   Mac OS X 10.13.5               .  .  .  #  #  .  #  .  .  .  .  .  .  .  .  .  .  #  .  .
 dnl   Mac OS X 10.5.8                .  .  .  #  #  .  .  .  .  .  .  #  .  .  .  .  .  .  .  .
--- a/m4/rawmemchr.m4
+++ b/m4/rawmemchr.m4
@ -1,4 +1,4 @@
-# rawmemchr.m4 serial 2
+# rawmemchr.m4 serial 3
 dnl Copyright (C) 2003, 2007-2021 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 +9,7 @@ AC_DEFUN([gl_FUNC_RAWMEMCHR],
  dnl Persuade glibc <string.h> to declare rawmemchr().
  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])

-  AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
+  AC_REQUIRE([gl_STRING_H_DEFAULTS])
  AC_CHECK_FUNCS([rawmemchr])
  if test $ac_cv_func_rawmemchr = no; then
    HAVE_RAWMEMCHR=0
--- a/m4/realloc.m4
+++ b/m4/realloc.m4
@ -1,21 +1,21 @@
-# realloc.m4 serial 20
+# realloc.m4 serial 24
 dnl Copyright (C) 2007, 2009-2021 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
+# https://git.savannah.gnu.org/cgit/autoconf.git/tree/lib/autoconf/functions.m4?id=v2.70#n1455
 AC_DEFUN([_AC_FUNC_REALLOC_IF],
 [
  AC_REQUIRE([AC_CANONICAL_HOST])dnl for cross-compiles
-  AC_CACHE_CHECK([for GNU libc compatible realloc],
+  AC_CACHE_CHECK([whether realloc (0, 0) returns nonnull],
    [ac_cv_func_realloc_0_nonnull],
    [AC_RUN_IFELSE(
       [AC_LANG_PROGRAM(
          [[#include <stdlib.h>
          ]],
-          [[char *p = realloc (0, 0);
+          [[void *p = realloc (0, 0);
            int result = !p;
            free (p);
            return result;]])
@ -24,53 +24,40 @@ AC_DEFUN([_AC_FUNC_REALLOC_IF],
       [ac_cv_func_realloc_0_nonnull=no],
       [case "$host_os" in
          # Guess yes on platforms where we know the result.
-          *-gnu* | gnu* | *-musl* | freebsd* | midnightbsd* | netbsd* | openbsd* \
-          | hpux* | solaris* | cygwin* | mingw*)
+          *-gnu* | freebsd* | netbsd* | openbsd* | bitrig* \
+          | gnu* | *-musl* | midnightbsd* \
+          | hpux* | solaris* | cygwin* | mingw* | msys* )
            ac_cv_func_realloc_0_nonnull="guessing yes" ;;
          # If we don't know, obey --enable-cross-guesses.
          *) ac_cv_func_realloc_0_nonnull="$gl_cross_guess_normal" ;;
        esac
       ])
    ])
-  case "$ac_cv_func_realloc_0_nonnull" in
-    *yes)
-      $1
-      ;;
-    *)
-      $2
-      ;;
-  esac
+  AS_CASE([$ac_cv_func_realloc_0_nonnull], [*yes], [$1], [$2])
 ])# 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.
+# Replace realloc if it is not compatible with GNU libc.
 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
-    ])
+  AC_REQUIRE([gl_FUNC_REALLOC_POSIX])
+  if test $REPLACE_REALLOC = 0; then
+    _AC_FUNC_REALLOC_IF([], [REPLACE_REALLOC=1])
+  fi
 ])# 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.
+# fails, and doesn't mess up with ptrdiff_t overflow),
+# 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
+  AC_REQUIRE([gl_FUNC_MALLOC_POSIX])
+  if test $REPLACE_MALLOC = 1; then
    REPLACE_REALLOC=1
  fi
 ])
--- a/m4/regex.m4
+++ b/m4/regex.m4
@ -1,4 +1,4 @@
-# serial 71
+# serial 73

 # Copyright (C) 1996-2001, 2003-2021 Free Software Foundation, Inc.
 #
@ -246,7 +246,7 @@ AC_DEFUN([gl_REGEX],
                           & ~RE_CONTEXT_INVALID_DUP
                           & ~RE_NO_EMPTY_RANGES);
            memset (&regex, 0, sizeof regex);
-            s = re_compile_pattern ("[[:alnum:]_-]\\\\+$", 16, &regex);
+            s = re_compile_pattern ("[[:alnum:]_-]\\\\+\$", 16, &regex);
            if (s)
              result |= 32;
            else
@ -264,14 +264,50 @@ AC_DEFUN([gl_REGEX],
               back reference.  */
            re_set_syntax (RE_SYNTAX_POSIX_EGREP);
            memset (&regex, 0, sizeof regex);
-            s = re_compile_pattern ("0|()0|\\1|0", 10, &regex);
+            s = re_compile_pattern ("0|()0|\\\\1|0", 10, &regex);
            if (!s)
-              result |= 64;
+              {
+                memset (&regs, 0, sizeof regs);
+                i = re_search (&regex, "x", 1, 0, 1, &regs);
+                if (i != -1)
+                  result |= 64;
+                if (0 <= i)
+                  {
+                    free (regs.start);
+                    free (regs.end);
+                  }
+                regfree (&regex);
+              }
            else
              {
                if (strcmp (s, "Invalid back reference"))
                  result |= 64;
+              }
+
+            /* glibc bug 11053.  */
+            re_set_syntax (RE_SYNTAX_POSIX_BASIC);
+            memset (&regex, 0, sizeof regex);
+            static char const pat_sub2[] = "\\\\(a*\\\\)*a*\\\\1";
+            s = re_compile_pattern (pat_sub2, sizeof pat_sub2 - 1, &regex);
+            if (s)
+              result |= 64;
+            else
+              {
+                memset (&regs, 0, sizeof regs);
+                static char const data[] = "a";
+                int datalen = sizeof data - 1;
+                i = re_search (&regex, data, datalen, 0, datalen, &regs);
+                if (i != 0)
+                  result |= 64;
+                else if (regs.num_regs < 2)
+                  result |= 64;
+                else if (! (regs.start[0] == 0 && regs.end[0] == 1))
+                  result |= 64;
+                else if (! (regs.start[1] == 0 && regs.end[1] == 0))
+                  result |= 64;
                regfree (&regex);
+                free (regs.start);
+                free (regs.end);
              }

 #if 0
--- a/m4/select.m4
+++ b/m4/select.m4
@ -1,4 +1,4 @@
-# select.m4 serial 12
+# select.m4 serial 13
 dnl Copyright (C) 2009-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@ -6,7 +6,7 @@ dnl with or without modifications, as long as this notice is preserved.

 AC_DEFUN([gl_FUNC_SELECT],
 [
-  AC_REQUIRE([gl_HEADER_SYS_SELECT])
+  AC_REQUIRE([gl_SYS_SELECT_H])
  AC_REQUIRE([AC_C_RESTRICT])
  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
  AC_REQUIRE([gl_SOCKETS])
--- a/m4/servent.m4
+++ b/m4/servent.m4
@ -1,4 +1,4 @@
-# servent.m4 serial 3
+# servent.m4 serial 4
 dnl Copyright (C) 2008, 2010-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@ -15,7 +15,7 @@ AC_DEFUN([gl_SERVENT],
  dnl - On BeOS, they are in libnet.
  dnl - On native Windows, they are in ws2_32.dll.
  dnl - Otherwise they are in libc.
-  AC_REQUIRE([gl_HEADER_SYS_SOCKET])dnl for HAVE_SYS_SOCKET_H, HAVE_WINSOCK2_H
+  AC_REQUIRE([gl_SYS_SOCKET_H])dnl for HAVE_SYS_SOCKET_H, HAVE_WINSOCK2_H
  SERVENT_LIB=
  gl_saved_libs="$LIBS"
  AC_SEARCH_LIBS([getservbyname], [socket network net],
--- a/m4/signal_h.m4
+++ b/m4/signal_h.m4
@ -1,10 +1,10 @@
-# signal_h.m4 serial 19
+# signal_h.m4 serial 22
 dnl Copyright (C) 2007-2021 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_SIGNAL_H],
+AC_DEFUN_ONCE([gl_SIGNAL_H],
 [
  AC_REQUIRE([gl_SIGNAL_H_DEFAULTS])
  AC_REQUIRE([gl_CHECK_TYPE_SIGSET_T])
@ -52,22 +52,37 @@ AC_DEFUN([gl_CHECK_TYPE_SIGSET_T],
  fi
 ])

+# gl_SIGNAL_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_SIGNAL_MODULE_INDICATOR],
 [
-  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
-  AC_REQUIRE([gl_SIGNAL_H_DEFAULTS])
+  dnl Ensure to expand the default settings once only.
+  gl_SIGNAL_H_REQUIRE_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])
 ])

+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_SIGNAL_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_SIGNAL_H_MODULE_INDICATOR_DEFAULTS], [
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_PTHREAD_SIGMASK])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_RAISE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SIGNAL_H_SIGPIPE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SIGPROCMASK])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SIGACTION])
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_SIGNAL_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_SIGNAL_H_DEFAULTS])
+])
+
 AC_DEFUN([gl_SIGNAL_H_DEFAULTS],
 [
-  GNULIB_PTHREAD_SIGMASK=0;    AC_SUBST([GNULIB_PTHREAD_SIGMASK])
-  GNULIB_RAISE=0;              AC_SUBST([GNULIB_RAISE])
-  GNULIB_SIGNAL_H_SIGPIPE=0;   AC_SUBST([GNULIB_SIGNAL_H_SIGPIPE])
-  GNULIB_SIGPROCMASK=0;        AC_SUBST([GNULIB_SIGPROCMASK])
-  GNULIB_SIGACTION=0;          AC_SUBST([GNULIB_SIGACTION])
  dnl Assume proper GNU behavior unless another module says otherwise.
  HAVE_POSIX_SIGNALBLOCKING=1; AC_SUBST([HAVE_POSIX_SIGNALBLOCKING])
  HAVE_PTHREAD_SIGMASK=1;      AC_SUBST([HAVE_PTHREAD_SIGMASK])
--- a/m4/sockpfaf.m4
+++ b/m4/sockpfaf.m4
@ -1,4 +1,4 @@
-# sockpfaf.m4 serial 9
+# sockpfaf.m4 serial 10
 dnl Copyright (C) 2004, 2006, 2009-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@ -13,7 +13,7 @@ dnl From Bruno Haible.

 AC_DEFUN([gl_SOCKET_FAMILIES],
 [
-  AC_REQUIRE([gl_HEADER_SYS_SOCKET])
+  AC_REQUIRE([gl_SYS_SOCKET_H])
  AC_CHECK_HEADERS_ONCE([netinet/in.h])

  AC_CACHE_CHECK([for IPv4 sockets],
@ -60,7 +60,7 @@ AC_DEFUN([gl_SOCKET_FAMILIES],

 AC_DEFUN([gl_SOCKET_FAMILY_UNIX],
 [
-  AC_REQUIRE([gl_HEADER_SYS_SOCKET])
+  AC_REQUIRE([gl_SYS_SOCKET_H])
  AC_CHECK_HEADERS_ONCE([sys/un.h])

  AC_CACHE_CHECK([for UNIX domain sockets],
--- a/m4/stat.m4
+++ b/m4/stat.m4
@ -1,4 +1,4 @@
-# serial 17
+# serial 18

 # Copyright (C) 2009-2021 Free Software Foundation, Inc.
 #
@ -69,7 +69,7 @@ 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_SYS_STAT_H])
  AC_REQUIRE([gl_PREREQ_STAT_W32])
  :
 ])
--- a/m4/stddef_h.m4
+++ b/m4/stddef_h.m4
@ -1,4 +1,4 @@
-# stddef_h.m4 serial 9
+# stddef_h.m4 serial 11
 dnl Copyright (C) 2009-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@ -6,7 +6,7 @@ dnl with or without modifications, as long as this notice is preserved.

 dnl A placeholder for <stddef.h>, for platforms that have issues.

-AC_DEFUN([gl_STDDEF_H],
+AC_DEFUN_ONCE([gl_STDDEF_H],
 [
  AC_REQUIRE([gl_STDDEF_H_DEFAULTS])
  AC_REQUIRE([gt_TYPE_WCHAR_T])
@ -68,13 +68,28 @@ AC_DEFUN([gl_STDDEF_H],
  fi
 ])

+# gl_STDDEF_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_STDDEF_MODULE_INDICATOR],
 [
-  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
-  AC_REQUIRE([gl_STDDEF_H_DEFAULTS])
+  dnl Ensure to expand the default settings once only.
+  gl_STDDEF_H_REQUIRE_DEFAULTS
  gl_MODULE_INDICATOR_SET_VARIABLE([$1])
 ])

+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_STDDEF_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_STDDEF_H_MODULE_INDICATOR_DEFAULTS], [
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_STDDEF_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_STDDEF_H_DEFAULTS])
+])
+
 AC_DEFUN([gl_STDDEF_H_DEFAULTS],
 [
  dnl Assume proper GNU behavior unless another module says otherwise.
--- a/m4/stdint.m4
+++ b/m4/stdint.m4
@ -1,4 +1,4 @@
-# stdint.m4 serial 58
+# stdint.m4 serial 60
 dnl Copyright (C) 2001-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@ -170,7 +170,7 @@ struct s {
      PTRDIFF_MIN == TYPE_MINIMUM (ptrdiff_t)
      && PTRDIFF_MAX == TYPE_MAXIMUM (ptrdiff_t)
      ? 1 : -1;
-  /* Detect bug in FreeBSD 6.0 / ia64.  */
+  /* Detect bug in FreeBSD 6.0/ia64 and FreeBSD 13.0/arm64.  */
  int check_SIG_ATOMIC:
      SIG_ATOMIC_MIN == TYPE_MINIMUM (sig_atomic_t)
      && SIG_ATOMIC_MAX == TYPE_MAXIMUM (sig_atomic_t)
@ -527,7 +527,7 @@ AC_DEFUN([gl_STDINT_TYPE_PROPERTIES],
  dnl requirement that wint_t is "unchanged by default argument promotions".
  dnl In this case gnulib's <wchar.h> and <wctype.h> override wint_t.
  dnl Set the variable BITSIZEOF_WINT_T accordingly.
-  if test $GNULIB_OVERRIDES_WINT_T = 1; then
+  if test $GNULIBHEADERS_OVERRIDE_WINT_T = 1; then
    BITSIZEOF_WINT_T=32
  fi
 ])
--- a/m4/stdio_h.m4
+++ b/m4/stdio_h.m4
@ -1,11 +1,12 @@
-# stdio_h.m4 serial 52
+# stdio_h.m4 serial 56
 dnl Copyright (C) 2007-2021 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_STDIO_H],
+AC_DEFUN_ONCE([gl_STDIO_H],
 [
+  AC_REQUIRE([gl_STDIO_H_DEFAULTS])
  AH_VERBATIM([MINGW_ANSI_STDIO],
 [/* Use GNU style printf and scanf.  */
 #ifndef __USE_MINGW_ANSI_STDIO
@ -13,7 +14,6 @@ AC_DEFUN([gl_STDIO_H],
 #endif
 ])
  AC_DEFINE([__USE_MINGW_ANSI_STDIO])
-  AC_REQUIRE([gl_STDIO_H_DEFAULTS])
  gl_NEXT_HEADERS([stdio.h])

  dnl Determine whether __USE_MINGW_ANSI_STDIO makes printf and
@ -40,17 +40,6 @@ AC_DEFUN([gl_STDIO_H],
       attribute "__gnu_printf__" instead of "__printf__"])
  fi

-  dnl No need to create extra modules for these functions. Everyone who uses
-  dnl <stdio.h> likely needs them.
-  GNULIB_FSCANF=1
-  gl_MODULE_INDICATOR([fscanf])
-  GNULIB_SCANF=1
-  gl_MODULE_INDICATOR([scanf])
-  GNULIB_FGETC=1
-  GNULIB_GETC=1
-  GNULIB_GETCHAR=1
-  GNULIB_FGETS=1
-  GNULIB_FREAD=1
  dnl This ifdef is necessary to avoid an error "missing file lib/stdio-read.c"
  dnl "expected source file, required through AC_LIBSOURCES, not found". It is
  dnl also an optimization, to avoid performing a configure check whose result
@ -64,18 +53,6 @@ AC_DEFUN([gl_STDIO_H],
    fi
  ])

-  dnl No need to create extra modules for these functions. Everyone who uses
-  dnl <stdio.h> likely needs them.
-  GNULIB_FPRINTF=1
-  GNULIB_PRINTF=1
-  GNULIB_VFPRINTF=1
-  GNULIB_VPRINTF=1
-  GNULIB_FPUTC=1
-  GNULIB_PUTC=1
-  GNULIB_PUTCHAR=1
-  GNULIB_FPUTS=1
-  GNULIB_PUTS=1
-  GNULIB_FWRITE=1
  dnl This ifdef is necessary to avoid an error "missing file lib/stdio-write.c"
  dnl "expected source file, required through AC_LIBSOURCES, not found". It is
  dnl also an optimization, to avoid performing a configure check whose result
@ -116,77 +93,92 @@ AC_DEFUN([gl_STDIO_H],
  fi
 ])

+# gl_STDIO_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_STDIO_MODULE_INDICATOR],
 [
-  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
-  AC_REQUIRE([gl_STDIO_H_DEFAULTS])
+  dnl Ensure to expand the default settings once only.
+  gl_STDIO_H_REQUIRE_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])
 ])

+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_STDIO_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_STDIO_H_MODULE_INDICATOR_DEFAULTS], [
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_DPRINTF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FCLOSE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FDOPEN])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FFLUSH])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FGETC])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FGETS])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FOPEN])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FPRINTF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FPRINTF_POSIX])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FPURGE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FPUTC])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FPUTS])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FREAD])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FREOPEN])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FSCANF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FSEEK])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FSEEKO])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FTELL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FTELLO])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FWRITE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETC])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETCHAR])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETDELIM])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETLINE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_OBSTACK_PRINTF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_OBSTACK_PRINTF_POSIX])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_PCLOSE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_PERROR])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_POPEN])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_PRINTF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_PRINTF_POSIX])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_PUTC])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_PUTCHAR])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_PUTS])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_REMOVE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_RENAME])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_RENAMEAT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SCANF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SNPRINTF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SPRINTF_POSIX])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STDIO_H_NONBLOCKING])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STDIO_H_SIGPIPE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TMPFILE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_VASPRINTF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_VFSCANF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_VSCANF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_VDPRINTF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_VFPRINTF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_VFPRINTF_POSIX])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_VPRINTF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_VPRINTF_POSIX])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_VSNPRINTF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_VSPRINTF_POSIX])
+    dnl Support Microsoft deprecated alias function names by default.
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_FCLOSEALL], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_FDOPEN], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_FILENO], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_GETW], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_PUTW], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_TEMPNAM], [1])
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_STDIO_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_STDIO_H_DEFAULTS])
+])
+
 AC_DEFUN([gl_STDIO_H_DEFAULTS],
 [
-  GNULIB_DPRINTF=0;              AC_SUBST([GNULIB_DPRINTF])
-  GNULIB_FCLOSE=0;               AC_SUBST([GNULIB_FCLOSE])
-  GNULIB_FDOPEN=0;               AC_SUBST([GNULIB_FDOPEN])
-  GNULIB_FFLUSH=0;               AC_SUBST([GNULIB_FFLUSH])
-  GNULIB_FGETC=0;                AC_SUBST([GNULIB_FGETC])
-  GNULIB_FGETS=0;                AC_SUBST([GNULIB_FGETS])
-  GNULIB_FOPEN=0;                AC_SUBST([GNULIB_FOPEN])
-  GNULIB_FPRINTF=0;              AC_SUBST([GNULIB_FPRINTF])
-  GNULIB_FPRINTF_POSIX=0;        AC_SUBST([GNULIB_FPRINTF_POSIX])
-  GNULIB_FPURGE=0;               AC_SUBST([GNULIB_FPURGE])
-  GNULIB_FPUTC=0;                AC_SUBST([GNULIB_FPUTC])
-  GNULIB_FPUTS=0;                AC_SUBST([GNULIB_FPUTS])
-  GNULIB_FREAD=0;                AC_SUBST([GNULIB_FREAD])
-  GNULIB_FREOPEN=0;              AC_SUBST([GNULIB_FREOPEN])
-  GNULIB_FSCANF=0;               AC_SUBST([GNULIB_FSCANF])
-  GNULIB_FSEEK=0;                AC_SUBST([GNULIB_FSEEK])
-  GNULIB_FSEEKO=0;               AC_SUBST([GNULIB_FSEEKO])
-  GNULIB_FTELL=0;                AC_SUBST([GNULIB_FTELL])
-  GNULIB_FTELLO=0;               AC_SUBST([GNULIB_FTELLO])
-  GNULIB_FWRITE=0;               AC_SUBST([GNULIB_FWRITE])
-  GNULIB_GETC=0;                 AC_SUBST([GNULIB_GETC])
-  GNULIB_GETCHAR=0;              AC_SUBST([GNULIB_GETCHAR])
-  GNULIB_GETDELIM=0;             AC_SUBST([GNULIB_GETDELIM])
-  GNULIB_GETLINE=0;              AC_SUBST([GNULIB_GETLINE])
-  GNULIB_OBSTACK_PRINTF=0;       AC_SUBST([GNULIB_OBSTACK_PRINTF])
-  GNULIB_OBSTACK_PRINTF_POSIX=0; AC_SUBST([GNULIB_OBSTACK_PRINTF_POSIX])
-  GNULIB_PCLOSE=0;               AC_SUBST([GNULIB_PCLOSE])
-  GNULIB_PERROR=0;               AC_SUBST([GNULIB_PERROR])
-  GNULIB_POPEN=0;                AC_SUBST([GNULIB_POPEN])
-  GNULIB_PRINTF=0;               AC_SUBST([GNULIB_PRINTF])
-  GNULIB_PRINTF_POSIX=0;         AC_SUBST([GNULIB_PRINTF_POSIX])
-  GNULIB_PUTC=0;                 AC_SUBST([GNULIB_PUTC])
-  GNULIB_PUTCHAR=0;              AC_SUBST([GNULIB_PUTCHAR])
-  GNULIB_PUTS=0;                 AC_SUBST([GNULIB_PUTS])
-  GNULIB_REMOVE=0;               AC_SUBST([GNULIB_REMOVE])
-  GNULIB_RENAME=0;               AC_SUBST([GNULIB_RENAME])
-  GNULIB_RENAMEAT=0;             AC_SUBST([GNULIB_RENAMEAT])
-  GNULIB_SCANF=0;                AC_SUBST([GNULIB_SCANF])
-  GNULIB_SNPRINTF=0;             AC_SUBST([GNULIB_SNPRINTF])
-  GNULIB_SPRINTF_POSIX=0;        AC_SUBST([GNULIB_SPRINTF_POSIX])
-  GNULIB_STDIO_H_NONBLOCKING=0;  AC_SUBST([GNULIB_STDIO_H_NONBLOCKING])
-  GNULIB_STDIO_H_SIGPIPE=0;      AC_SUBST([GNULIB_STDIO_H_SIGPIPE])
-  GNULIB_TMPFILE=0;              AC_SUBST([GNULIB_TMPFILE])
-  GNULIB_VASPRINTF=0;            AC_SUBST([GNULIB_VASPRINTF])
-  GNULIB_VFSCANF=0;              AC_SUBST([GNULIB_VFSCANF])
-  GNULIB_VSCANF=0;               AC_SUBST([GNULIB_VSCANF])
-  GNULIB_VDPRINTF=0;             AC_SUBST([GNULIB_VDPRINTF])
-  GNULIB_VFPRINTF=0;             AC_SUBST([GNULIB_VFPRINTF])
-  GNULIB_VFPRINTF_POSIX=0;       AC_SUBST([GNULIB_VFPRINTF_POSIX])
-  GNULIB_VPRINTF=0;              AC_SUBST([GNULIB_VPRINTF])
-  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])
--- a/m4/stdlib_h.m4
+++ b/m4/stdlib_h.m4
@ -1,10 +1,10 @@
-# stdlib_h.m4 serial 59
+# stdlib_h.m4 serial 63
 dnl Copyright (C) 2007-2021 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_STDLIB_H],
+AC_DEFUN_ONCE([gl_STDLIB_H],
 [
  AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
  gl_NEXT_HEADERS([stdlib.h])
@ -46,63 +46,78 @@ AC_DEFUN([gl_STDLIB_H],
  fi
 ])

+# gl_STDLIB_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_STDLIB_MODULE_INDICATOR],
 [
-  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
-  AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
+  dnl Ensure to expand the default settings once only.
+  gl_STDLIB_H_REQUIRE_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])
 ])

+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_STDLIB_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_STDLIB_H_MODULE_INDICATOR_DEFAULTS], [
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB__EXIT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ALIGNED_ALLOC])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ATOLL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_CALLOC_POSIX])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_CANONICALIZE_FILE_NAME])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FREE_POSIX])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETLOADAVG])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETSUBOPT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GRANTPT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MALLOC_POSIX])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBTOWC])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MKDTEMP])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MKOSTEMP])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MKOSTEMPS])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MKSTEMP])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MKSTEMPS])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_POSIX_MEMALIGN])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_POSIX_OPENPT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_PTSNAME])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_PTSNAME_R])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_PUTENV])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_QSORT_R])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_RANDOM])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_RANDOM_R])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_REALLOCARRAY])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_REALLOC_POSIX])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_REALPATH])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_RPMATCH])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SECURE_GETENV])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SETENV])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRTOD])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRTOL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRTOLD])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRTOLL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRTOUL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRTOULL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SYSTEM_POSIX])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNLOCKPT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNSETENV])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCTOMB])
+    dnl Support Microsoft deprecated alias function names by default.
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_ECVT], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_FCVT], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_GCVT], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_MKTEMP], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_PUTENV], [1])
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_STDLIB_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
+])
+
 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])
-  GNULIB_MALLOC_POSIX=0;  AC_SUBST([GNULIB_MALLOC_POSIX])
-  GNULIB_MBTOWC=0;        AC_SUBST([GNULIB_MBTOWC])
-  GNULIB_MKDTEMP=0;       AC_SUBST([GNULIB_MKDTEMP])
-  GNULIB_MKOSTEMP=0;      AC_SUBST([GNULIB_MKOSTEMP])
-  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])
-  GNULIB_PUTENV=0;        AC_SUBST([GNULIB_PUTENV])
-  GNULIB_QSORT_R=0;       AC_SUBST([GNULIB_QSORT_R])
-  GNULIB_RANDOM=0;        AC_SUBST([GNULIB_RANDOM])
-  GNULIB_RANDOM_R=0;      AC_SUBST([GNULIB_RANDOM_R])
-  GNULIB_REALLOCARRAY=0;  AC_SUBST([GNULIB_REALLOCARRAY])
-  GNULIB_REALLOC_POSIX=0; AC_SUBST([GNULIB_REALLOC_POSIX])
-  GNULIB_REALPATH=0;      AC_SUBST([GNULIB_REALPATH])
-  GNULIB_RPMATCH=0;       AC_SUBST([GNULIB_RPMATCH])
-  GNULIB_SECURE_GETENV=0; AC_SUBST([GNULIB_SECURE_GETENV])
-  GNULIB_SETENV=0;        AC_SUBST([GNULIB_SETENV])
-  GNULIB_STRTOD=0;        AC_SUBST([GNULIB_STRTOD])
-  GNULIB_STRTOL=0;        AC_SUBST([GNULIB_STRTOL])
-  GNULIB_STRTOLD=0;       AC_SUBST([GNULIB_STRTOLD])
-  GNULIB_STRTOLL=0;       AC_SUBST([GNULIB_STRTOLL])
-  GNULIB_STRTOUL=0;       AC_SUBST([GNULIB_STRTOUL])
-  GNULIB_STRTOULL=0;      AC_SUBST([GNULIB_STRTOULL])
-  GNULIB_SYSTEM_POSIX=0;  AC_SUBST([GNULIB_SYSTEM_POSIX])
-  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])
@ -164,6 +179,7 @@ AC_DEFUN([gl_STDLIB_H_DEFAULTS],
  REPLACE_RANDOM=0;          AC_SUBST([REPLACE_RANDOM])
  REPLACE_RANDOM_R=0;        AC_SUBST([REPLACE_RANDOM_R])
  REPLACE_REALLOC=0;         AC_SUBST([REPLACE_REALLOC])
+  REPLACE_REALLOCARRAY=0;    AC_SUBST([REPLACE_REALLOCARRAY])
  REPLACE_REALPATH=0;        AC_SUBST([REPLACE_REALPATH])
  REPLACE_SETENV=0;          AC_SUBST([REPLACE_SETENV])
  REPLACE_SETSTATE=0;        AC_SUBST([REPLACE_SETSTATE])
--- a/m4/strdup.m4
+++ b/m4/strdup.m4
@ -1,4 +1,4 @@
-# strdup.m4 serial 14
+# strdup.m4 serial 15

 dnl Copyright (C) 2002-2021 Free Software Foundation, Inc.

@ -8,7 +8,7 @@ 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_REQUIRE([gl_STRING_H_DEFAULTS])
  AC_CHECK_DECLS_ONCE([strdup])
  if test $ac_cv_have_decl_strdup = no; then
    HAVE_DECL_STRDUP=0
@ -17,7 +17,7 @@ AC_DEFUN([gl_FUNC_STRDUP],

 AC_DEFUN([gl_FUNC_STRDUP_POSIX],
 [
-  AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
+  AC_REQUIRE([gl_STRING_H_DEFAULTS])
  AC_REQUIRE([gl_CHECK_MALLOC_POSIX])
  if test $gl_cv_func_malloc_posix != yes; then
    REPLACE_STRDUP=1
--- a/m4/string_h.m4
+++ b/m4/string_h.m4
@ -5,20 +5,15 @@
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.

-# serial 29
+# serial 32

 # Written by Paul Eggert.

-AC_DEFUN([gl_HEADER_STRING_H],
+AC_DEFUN_ONCE([gl_STRING_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_HEADER_STRING_H_BODY])
-])
-
-AC_DEFUN([gl_HEADER_STRING_H_BODY],
-[
-  AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
+  dnl Ensure to expand the default settings once only, before all statements
+  dnl that occur in other macros.
+  AC_REQUIRE([gl_STRING_H_DEFAULTS])
  gl_NEXT_HEADERS([string.h])

  dnl Check for declarations of anything we want to poison if the
@ -33,62 +28,77 @@ AC_DEFUN([gl_HEADER_STRING_H_BODY],
  AC_REQUIRE([AC_C_RESTRICT])
 ])

+# gl_STRING_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_STRING_MODULE_INDICATOR],
 [
-  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
-  AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
+  dnl Ensure to expand the default settings once only.
+  gl_STRING_H_REQUIRE_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_HEADER_STRING_H_DEFAULTS],
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_STRING_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_STRING_H_MODULE_INDICATOR_DEFAULTS], [
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_EXPLICIT_BZERO])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FFSL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FFSLL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MEMCHR])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MEMMEM])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MEMPCPY])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MEMRCHR])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_RAWMEMCHR])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STPCPY])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STPNCPY])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRCHRNUL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRDUP])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRNCAT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRNDUP])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRNLEN])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRPBRK])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRSEP])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRSTR])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRCASESTR])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRTOK_R])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBSLEN])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBSNLEN])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBSCHR])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBSRCHR])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBSSTR])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBSCASECMP])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBSNCASECMP])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBSPCASECMP])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBSCASESTR])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBSCSPN])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBSPBRK])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBSSPN])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBSSEP])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBSTOK_R])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRERROR])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRERROR_R])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRERRORNAME_NP])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SIGABBREV_NP])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SIGDESCR_NP])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRSIGNAL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRVERSCMP])
+    dnl Support Microsoft deprecated alias function names by default.
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_MEMCCPY], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_STRDUP], [1])
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_STRING_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_STRING_H_DEFAULTS])
+])
+
+AC_DEFUN([gl_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_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])
--- a/m4/sys_file_h.m4
+++ b/m4/sys_file_h.m4
@ -1,5 +1,5 @@
 # Configure a replacement for <sys/file.h>.
-# serial 6
+# serial 9

 # Copyright (C) 2008-2021 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
@ -8,9 +8,9 @@

 # Written by Richard W.M. Jones.

-AC_DEFUN([gl_HEADER_SYS_FILE_H],
+AC_DEFUN_ONCE([gl_SYS_FILE_H],
 [
-  AC_REQUIRE([gl_HEADER_SYS_FILE_H_DEFAULTS])
+  AC_REQUIRE([gl_SYS_FILE_H_DEFAULTS])

  dnl <sys/file.h> is always overridden, because of GNULIB_POSIXCHECK.
  gl_CHECK_NEXT_HEADERS([sys/file.h])
@ -28,14 +28,29 @@ AC_DEFUN([gl_HEADER_SYS_FILE_H],
    ]], [flock])
 ])

-AC_DEFUN([gl_HEADER_SYS_FILE_MODULE_INDICATOR],
+# gl_SYS_FILE_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
+AC_DEFUN([gl_SYS_FILE_MODULE_INDICATOR],
 [
-  AC_REQUIRE([gl_HEADER_SYS_FILE_H_DEFAULTS])
+  gl_SYS_FILE_H_REQUIRE_DEFAULTS
  gl_MODULE_INDICATOR_SET_VARIABLE([$1])
 ])

-AC_DEFUN([gl_HEADER_SYS_FILE_H_DEFAULTS],
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_SYS_FILE_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_SYS_FILE_H_MODULE_INDICATOR_DEFAULTS], [
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FLOCK])
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_SYS_FILE_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_SYS_FILE_H_DEFAULTS])
+])
+
+AC_DEFUN([gl_SYS_FILE_H_DEFAULTS],
 [
-  GNULIB_FLOCK=0;        AC_SUBST([GNULIB_FLOCK])
  HAVE_FLOCK=1;          AC_SUBST([HAVE_FLOCK])
 ])
--- a/m4/sys_random_h.m4
+++ b/m4/sys_random_h.m4
@ -1,10 +1,10 @@
-# sys_random_h.m4 serial 5
+# sys_random_h.m4 serial 8
 dnl Copyright (C) 2020-2021 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_DEFUN_ONCE([gl_SYS_RANDOM_H],
 [
  AC_REQUIRE([gl_SYS_RANDOM_H_DEFAULTS])
  dnl <sys/random.h> is always overridden, because of GNULIB_POSIXCHECK.
@ -35,18 +35,33 @@ AC_DEFUN([gl_HEADER_SYS_RANDOM],
    [getrandom])
 ])

+# gl_SYS_RANDOM_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 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])
+  dnl Ensure to expand the default settings once only.
+  gl_SYS_RANDOM_H_REQUIRE_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])
 ])

+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_SYS_RANDOM_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_SYS_RANDOM_H_MODULE_INDICATOR_DEFAULTS], [
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETRANDOM])
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_SYS_RANDOM_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_SYS_RANDOM_H_DEFAULTS])
+])
+
 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])
--- a/m4/sys_select_h.m4
+++ b/m4/sys_select_h.m4
@ -1,13 +1,13 @@
-# sys_select_h.m4 serial 20
+# sys_select_h.m4 serial 23
 dnl Copyright (C) 2006-2021 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_SELECT],
+AC_DEFUN_ONCE([gl_SYS_SELECT_H],
 [
-  AC_REQUIRE([AC_C_RESTRICT])
  AC_REQUIRE([gl_SYS_SELECT_H_DEFAULTS])
+  AC_REQUIRE([AC_C_RESTRICT])
  AC_CACHE_CHECK([whether <sys/select.h> is self-contained],
    [gl_cv_header_sys_select_h_selfcontained],
    [
@ -75,19 +75,34 @@ AC_DEFUN([gl_HEADER_SYS_SELECT],
    ]], [pselect select])
 ])

+# gl_SYS_SELECT_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_SYS_SELECT_MODULE_INDICATOR],
 [
-  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
-  AC_REQUIRE([gl_SYS_SELECT_H_DEFAULTS])
+  dnl Ensure to expand the default settings once only.
+  gl_SYS_SELECT_H_REQUIRE_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])
 ])

+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_SYS_SELECT_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_SYS_SELECT_H_MODULE_INDICATOR_DEFAULTS], [
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_PSELECT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SELECT])
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_SYS_SELECT_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_SYS_SELECT_H_DEFAULTS])
+])
+
 AC_DEFUN([gl_SYS_SELECT_H_DEFAULTS],
 [
-  GNULIB_PSELECT=0; AC_SUBST([GNULIB_PSELECT])
-  GNULIB_SELECT=0; AC_SUBST([GNULIB_SELECT])
  dnl Assume proper GNU behavior unless another module says otherwise.
  HAVE_PSELECT=1; AC_SUBST([HAVE_PSELECT])
  REPLACE_PSELECT=0; AC_SUBST([REPLACE_PSELECT])
--- a/m4/sys_socket_h.m4
+++ b/m4/sys_socket_h.m4
@ -1,4 +1,4 @@
-# sys_socket_h.m4 serial 25
+# sys_socket_h.m4 serial 28
 dnl Copyright (C) 2005-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@ -6,7 +6,7 @@ dnl with or without modifications, as long as this notice is preserved.

 dnl From Simon Josefsson.

-AC_DEFUN([gl_HEADER_SYS_SOCKET],
+AC_DEFUN_ONCE([gl_SYS_SOCKET_H],
 [
  AC_REQUIRE([gl_SYS_SOCKET_H_DEFAULTS])
  AC_REQUIRE([AC_CANONICAL_HOST])
@ -156,32 +156,47 @@ AC_DEFUN([gl_PREREQ_SYS_H_WS2TCPIP],
  AC_SUBST([HAVE_WS2TCPIP_H])
 ])

+# gl_SYS_SOCKET_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_SYS_SOCKET_MODULE_INDICATOR],
 [
-  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
-  AC_REQUIRE([gl_SYS_SOCKET_H_DEFAULTS])
+  dnl Ensure to expand the default settings once only.
+  gl_SYS_SOCKET_H_REQUIRE_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])
 ])

+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_SYS_SOCKET_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_SYS_SOCKET_H_MODULE_INDICATOR_DEFAULTS], [
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SOCKET])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_CONNECT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ACCEPT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_BIND])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETPEERNAME])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETSOCKNAME])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETSOCKOPT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LISTEN])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_RECV])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SEND])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_RECVFROM])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SENDTO])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SETSOCKOPT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SHUTDOWN])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ACCEPT4])
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_SYS_SOCKET_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_SYS_SOCKET_H_DEFAULTS])
+])
+
 AC_DEFUN([gl_SYS_SOCKET_H_DEFAULTS],
 [
-  GNULIB_SOCKET=0;      AC_SUBST([GNULIB_SOCKET])
-  GNULIB_CONNECT=0;     AC_SUBST([GNULIB_CONNECT])
-  GNULIB_ACCEPT=0;      AC_SUBST([GNULIB_ACCEPT])
-  GNULIB_BIND=0;        AC_SUBST([GNULIB_BIND])
-  GNULIB_GETPEERNAME=0; AC_SUBST([GNULIB_GETPEERNAME])
-  GNULIB_GETSOCKNAME=0; AC_SUBST([GNULIB_GETSOCKNAME])
-  GNULIB_GETSOCKOPT=0;  AC_SUBST([GNULIB_GETSOCKOPT])
-  GNULIB_LISTEN=0;      AC_SUBST([GNULIB_LISTEN])
-  GNULIB_RECV=0;        AC_SUBST([GNULIB_RECV])
-  GNULIB_SEND=0;        AC_SUBST([GNULIB_SEND])
-  GNULIB_RECVFROM=0;    AC_SUBST([GNULIB_RECVFROM])
-  GNULIB_SENDTO=0;      AC_SUBST([GNULIB_SENDTO])
-  GNULIB_SETSOCKOPT=0;  AC_SUBST([GNULIB_SETSOCKOPT])
-  GNULIB_SHUTDOWN=0;    AC_SUBST([GNULIB_SHUTDOWN])
-  GNULIB_ACCEPT4=0;     AC_SUBST([GNULIB_ACCEPT4])
  HAVE_STRUCT_SOCKADDR_STORAGE=1; AC_SUBST([HAVE_STRUCT_SOCKADDR_STORAGE])
  HAVE_STRUCT_SOCKADDR_STORAGE_SS_FAMILY=1;
                        AC_SUBST([HAVE_STRUCT_SOCKADDR_STORAGE_SS_FAMILY])
--- a/m4/sys_stat_h.m4
+++ b/m4/sys_stat_h.m4
@ -1,4 +1,4 @@
-# sys_stat_h.m4 serial 38   -*- Autoconf -*-
+# sys_stat_h.m4 serial 41   -*- Autoconf -*-
 dnl Copyright (C) 2006-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@ -7,7 +7,7 @@ dnl with or without modifications, as long as this notice is preserved.
 dnl From Eric Blake.
 dnl Provide a GNU-like <sys/stat.h>.

-AC_DEFUN([gl_HEADER_SYS_STAT_H],
+AC_DEFUN_ONCE([gl_SYS_STAT_H],
 [
  AC_REQUIRE([gl_SYS_STAT_H_DEFAULTS])

@ -52,38 +52,53 @@ AC_DEFUN([gl_HEADER_SYS_STAT_H],
  AC_REQUIRE([AC_C_RESTRICT])
 ])

+# gl_SYS_STAT_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_SYS_STAT_MODULE_INDICATOR],
 [
-  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
-  AC_REQUIRE([gl_SYS_STAT_H_DEFAULTS])
+  dnl Ensure to expand the default settings once only.
+  gl_SYS_STAT_H_REQUIRE_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])
 ])

+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_SYS_STAT_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_SYS_STAT_H_MODULE_INDICATOR_DEFAULTS], [
+    gl_UNISTD_H_REQUIRE_DEFAULTS dnl for REPLACE_FCHDIR
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FCHMODAT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FSTAT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FSTATAT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FUTIMENS])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETUMASK])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LCHMOD])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LSTAT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MKDIR])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MKDIRAT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MKFIFO])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MKFIFOAT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MKNOD])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MKNODAT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STAT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UTIMENSAT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_OVERRIDES_STRUCT_STAT])
+    dnl Support Microsoft deprecated alias function names by default.
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_CHMOD], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_MKDIR], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_UMASK], [1])
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_SYS_STAT_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_SYS_STAT_H_DEFAULTS])
+])
+
 AC_DEFUN([gl_SYS_STAT_H_DEFAULTS],
 [
-  AC_REQUIRE([gl_UNISTD_H_DEFAULTS]) dnl for REPLACE_FCHDIR
-  GNULIB_FCHMODAT=0;    AC_SUBST([GNULIB_FCHMODAT])
-  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])
-  GNULIB_MKNOD=0;       AC_SUBST([GNULIB_MKNOD])
-  GNULIB_MKNODAT=0;     AC_SUBST([GNULIB_MKNODAT])
-  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])
--- a/m4/sys_time_h.m4
+++ b/m4/sys_time_h.m4
@ -1,5 +1,5 @@
 # Configure a replacement for <sys/time.h>.
-# serial 9
+# serial 12

 # Copyright (C) 2007, 2009-2021 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
@ -8,18 +8,13 @@

 # Written by Paul Eggert and Martin Lambers.

-AC_DEFUN([gl_HEADER_SYS_TIME_H],
+AC_DEFUN_ONCE([gl_SYS_TIME_H],
 [
  dnl Use AC_REQUIRE here, so that the REPLACE_GETTIMEOFDAY=0 statement
  dnl below is expanded once only, before all REPLACE_GETTIMEOFDAY=1
  dnl statements that occur in other macros.
-  AC_REQUIRE([gl_HEADER_SYS_TIME_H_BODY])
-])
-
-AC_DEFUN([gl_HEADER_SYS_TIME_H_BODY],
-[
+  AC_REQUIRE([gl_SYS_TIME_H_DEFAULTS])
  AC_REQUIRE([AC_C_RESTRICT])
-  AC_REQUIRE([gl_HEADER_SYS_TIME_H_DEFAULTS])
  AC_CHECK_HEADERS_ONCE([sys/time.h])
  gl_CHECK_NEXT_HEADERS([sys/time.h])

@ -89,18 +84,33 @@ AC_DEFUN([gl_HEADER_SYS_TIME_H_BODY],
    ]], [gettimeofday])
 ])

+# gl_SYS_TIME_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_SYS_TIME_MODULE_INDICATOR],
 [
-  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
-  AC_REQUIRE([gl_HEADER_SYS_TIME_H_DEFAULTS])
+  dnl Ensure to expand the default settings once only.
+  gl_SYS_TIME_H_REQUIRE_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_HEADER_SYS_TIME_H_DEFAULTS],
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_SYS_TIME_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_SYS_TIME_H_MODULE_INDICATOR_DEFAULTS], [
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETTIMEOFDAY])
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_SYS_TIME_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_SYS_TIME_H_DEFAULTS])
+])
+
+AC_DEFUN([gl_SYS_TIME_H_DEFAULTS],
 [
-  GNULIB_GETTIMEOFDAY=0;     AC_SUBST([GNULIB_GETTIMEOFDAY])
  dnl Assume POSIX behavior unless another module says otherwise.
  HAVE_GETTIMEOFDAY=1;       AC_SUBST([HAVE_GETTIMEOFDAY])
  HAVE_STRUCT_TIMEVAL=1;     AC_SUBST([HAVE_STRUCT_TIMEVAL])
--- a/m4/sys_times_h.m4
+++ b/m4/sys_times_h.m4
@ -1,5 +1,5 @@
 # Configure a replacement for <sys/times.h>.
-# serial 8
+# serial 11

 # Copyright (C) 2008-2021 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
@ -8,7 +8,7 @@

 # Written by Simon Josefsson.

-AC_DEFUN([gl_SYS_TIMES_H],
+AC_DEFUN_ONCE([gl_SYS_TIMES_H],
 [
  AC_REQUIRE([gl_SYS_TIMES_H_DEFAULTS])

@ -36,16 +36,31 @@ AC_DEFUN([gl_SYS_TIMES_H],
    ]], [times])
 ])

+# gl_SYS_TIMES_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_SYS_TIMES_MODULE_INDICATOR],
 [
-  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
-  AC_REQUIRE([gl_SYS_TIMES_H_DEFAULTS])
+  dnl Ensure to expand the default settings once only.
+  gl_SYS_TIMES_H_REQUIRE_DEFAULTS
  gl_MODULE_INDICATOR_SET_VARIABLE([$1])
 ])

+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_SYS_TIMES_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_SYS_TIMES_H_MODULE_INDICATOR_DEFAULTS], [
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TIMES])
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_SYS_TIMES_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_SYS_TIMES_H_DEFAULTS])
+])
+
 AC_DEFUN([gl_SYS_TIMES_H_DEFAULTS],
 [
-  GNULIB_TIMES=0;     AC_SUBST([GNULIB_TIMES])
  HAVE_STRUCT_TMS=1;  AC_SUBST([HAVE_STRUCT_TMS])
  HAVE_TIMES=1;       AC_SUBST([HAVE_TIMES])
 ])
--- a/m4/sys_types_h.m4
+++ b/m4/sys_types_h.m4
@ -1,4 +1,4 @@
-# sys_types_h.m4 serial 11
+# sys_types_h.m4 serial 13
 dnl Copyright (C) 2011-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@ -6,10 +6,11 @@ dnl with or without modifications, as long as this notice is preserved.

 AC_DEFUN_ONCE([gl_SYS_TYPES_H],
 [
+  AC_REQUIRE([gl_SYS_TYPES_H_DEFAULTS])
+
  dnl Use sane struct stat types in OpenVMS 8.2 and later.
  AC_DEFINE([_USE_STD_STAT], 1, [For standard stat data types on VMS.])

-  AC_REQUIRE([gl_SYS_TYPES_H_DEFAULTS])
  gl_NEXT_HEADERS([sys/types.h])

  dnl Ensure the type pid_t gets defined.
@ -30,6 +31,17 @@ AC_DEFUN_ONCE([gl_SYS_TYPES_H],
  AC_SUBST([WINDOWS_STAT_INODES])
 ])

+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_SYS_TYPES_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_SYS_TYPE_H_MODULE_INDICATOR_DEFAULTS], [
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_SYS_TYPE_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_SYS_TYPES_H_DEFAULTS])
+])
+
 AC_DEFUN([gl_SYS_TYPES_H_DEFAULTS],
 [
 ])
--- a/m4/sys_uio_h.m4
+++ b/m4/sys_uio_h.m4
@ -1,10 +1,10 @@
-# sys_uio_h.m4 serial 1
+# sys_uio_h.m4 serial 3
 dnl Copyright (C) 2011-2021 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_UIO],
+AC_DEFUN_ONCE([gl_SYS_UIO_H],
 [
  AC_REQUIRE([gl_SYS_UIO_H_DEFAULTS])
  dnl <sys/uio.h> is always overridden, because of GNULIB_POSIXCHECK.
@ -17,15 +17,30 @@ AC_DEFUN([gl_HEADER_SYS_UIO],
  AC_SUBST([HAVE_SYS_UIO_H])
 ])

+# gl_SYS_UIO_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_SYS_UIO_MODULE_INDICATOR],
 [
-  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
-  AC_REQUIRE([gl_SYS_UIO_H_DEFAULTS])
+  dnl Ensure to expand the default settings once only.
+  gl_SYS_UIO_H_REQUIRE_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])
 ])

+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_SYS_UIO_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_SYS_UIO_H_MODULE_INDICATOR_DEFAULTS], [
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_SYS_UIO_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_SYS_UIO_H_DEFAULTS])
+])
+
 AC_DEFUN([gl_SYS_UIO_H_DEFAULTS],
 [
 ])
--- a/m4/threadlib.m4
+++ b/m4/threadlib.m4
@ -1,4 +1,4 @@
-# threadlib.m4 serial 30
+# threadlib.m4 serial 31
 dnl Copyright (C) 2005-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@ -212,6 +212,27 @@ AC_DEFUN([gl_PTHREADLIB_BODY],
        LIBS=$save_LIBS
        test $gl_pthread_api = yes && break
      done
+      echo "$as_me:__oline__: gl_pthread_api=$gl_pthread_api" >&AS_MESSAGE_LOG_FD
+      echo "$as_me:__oline__: LIBPTHREAD=$LIBPTHREAD" >&AS_MESSAGE_LOG_FD
+
+      gl_pthread_in_glibc=no
+      # On Linux with glibc >= 2.34, libc contains the fully functional
+      # pthread functions.
+      case "$host_os" in
+        linux*)
+          AC_EGREP_CPP([Lucky user],
+            [#include <features.h>
+             #ifdef __GNU_LIBRARY__
+              #if (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 34) || (__GLIBC__ > 2)
+               Lucky user
+              #endif
+             #endif
+            ],
+            [gl_pthread_in_glibc=yes],
+            [])
+          ;;
+      esac
+      echo "$as_me:__oline__: gl_pthread_in_glibc=$gl_pthread_in_glibc" >&AS_MESSAGE_LOG_FD

      # Test for libpthread by looking for pthread_kill. (Not pthread_self,
      # since it is defined as a macro on OSF/1.)
@ -219,18 +240,22 @@ AC_DEFUN([gl_PTHREADLIB_BODY],
        # 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
+          [if test $gl_pthread_in_glibc = yes; then
+             LIBPMULTITHREAD=
+           else
+             LIBPMULTITHREAD=-lpthread
+             # On Solaris and HP-UX, most pthread functions exist also in libc.
+             # Therefore pthread_in_use() needs to actually try to create a
+             # thread: pthread_create from libc will fail, whereas
+             # pthread_create will actually create a thread.
+             # On Solaris 10 or newer, this test is no longer needed, because
+             # libc contains the fully functional pthread functions.
+             case "$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
+           fi
          ])
      elif test $gl_pthread_api != yes; then
        # Some library is needed. Try libpthread and libc_r.
@ -246,6 +271,7 @@ AC_DEFUN([gl_PTHREADLIB_BODY],
             LIBPMULTITHREAD=-lc_r])
        fi
      fi
+      echo "$as_me:__oline__: LIBPMULTITHREAD=$LIBPMULTITHREAD" >&AS_MESSAGE_LOG_FD
    fi
    AC_MSG_CHECKING([whether POSIX threads API is available])
    AC_MSG_RESULT([$gl_pthread_api])
@ -311,7 +337,8 @@ AC_DEFUN([gl_STDTHREADLIB_BODY],
          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.
+          dnl glibc >= 2.34, AIX >= 7.1, and Solaris >= 11.4 have thrd_create in
+          dnl libc.
          AC_CHECK_FUNCS([thrd_create])
          if test $ac_cv_func_thrd_create = yes; then
            LIBSTDTHREAD=
@ -481,7 +508,10 @@ AC_DEFUN([gl_THREADLIB_BODY],
          gl_threads_api=posix
          AC_DEFINE([USE_POSIX_THREADS], [1],
            [Define if the POSIX multithreading library can be used.])
-          if test -n "$LIBMULTITHREAD" || test -n "$LTLIBMULTITHREAD"; then
+          if test -z "$LIBMULTITHREAD" && test -z "$LTLIBMULTITHREAD"; then
+            AC_DEFINE([USE_POSIX_THREADS_FROM_LIBC], [1],
+              [Define if references to the POSIX multithreading library are satisfied by libc.])
+          else
            if case "$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.])
@ -576,7 +606,9 @@ dnl                    flavours   option      weak       result
 dnl ---------------    ---------  ---------   --------   ---------
 dnl Linux 2.4/glibc    posix      -lpthread       Y      OK
 dnl
-dnl GNU Hurd/glibc     posix
+dnl Linux/glibc 2.34   posix                      Y      OK
+dnl
+dnl GNU Hurd/glibc     posix      -lpthread       Y      OK
 dnl
 dnl Ubuntu 14.04       posix      -pthread        Y      OK
 dnl
--- a/m4/time_h.m4
+++ b/m4/time_h.m4
@ -2,7 +2,7 @@

 # Copyright (C) 2000-2001, 2003-2007, 2009-2021 Free Software Foundation, Inc.

-# serial 15
+# serial 18

 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@ -10,16 +10,11 @@

 # Written by Paul Eggert and Jim Meyering.

-AC_DEFUN([gl_HEADER_TIME_H],
+AC_DEFUN_ONCE([gl_TIME_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_HEADER_TIME_H_BODY])
-])
-
-AC_DEFUN([gl_HEADER_TIME_H_BODY],
-[
-  AC_REQUIRE([gl_HEADER_TIME_H_DEFAULTS])
+  dnl Ensure to expand the default settings once only, before all statements
+  dnl that occur in other macros.
+  AC_REQUIRE([gl_TIME_H_DEFAULTS])

  gl_NEXT_HEADERS([time.h])
  AC_REQUIRE([gl_CHECK_TYPE_STRUCT_TIMESPEC])
@ -111,30 +106,45 @@ AC_DEFUN([gl_CHECK_TYPE_STRUCT_TIMESPEC],
  AC_SUBST([UNISTD_H_DEFINES_STRUCT_TIMESPEC])
 ])

+# gl_TIME_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_TIME_MODULE_INDICATOR],
 [
-  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
-  AC_REQUIRE([gl_HEADER_TIME_H_DEFAULTS])
+  dnl Ensure to expand the default settings once only.
+  gl_TIME_H_REQUIRE_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_HEADER_TIME_H_DEFAULTS],
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_TIME_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_TIME_H_MODULE_INDICATOR_DEFAULTS], [
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_CTIME])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MKTIME])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LOCALTIME])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_NANOSLEEP])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRFTIME])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRPTIME])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TIMEGM])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TIMESPEC_GET])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TIME_R])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TIME_RZ])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TZSET])
+    dnl Support Microsoft deprecated alias function names by default.
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_TZSET], [1])
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_TIME_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_TIME_H_DEFAULTS])
+])
+
+AC_DEFUN([gl_TIME_H_DEFAULTS],
 [
-  GNULIB_CTIME=0;                        AC_SUBST([GNULIB_CTIME])
-  GNULIB_MKTIME=0;                       AC_SUBST([GNULIB_MKTIME])
-  GNULIB_LOCALTIME=0;                    AC_SUBST([GNULIB_LOCALTIME])
-  GNULIB_NANOSLEEP=0;                    AC_SUBST([GNULIB_NANOSLEEP])
-  GNULIB_STRFTIME=0;                     AC_SUBST([GNULIB_STRFTIME])
-  GNULIB_STRPTIME=0;                     AC_SUBST([GNULIB_STRPTIME])
-  GNULIB_TIMEGM=0;                       AC_SUBST([GNULIB_TIMEGM])
-  GNULIB_TIMESPEC_GET=0;                 AC_SUBST([GNULIB_TIMESPEC_GET])
-  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])
--- a/m4/time_r.m4
+++ b/m4/time_r.m4
@ -12,7 +12,7 @@ AC_DEFUN([gl_TIME_R],
  dnl Persuade glibc and Solaris <time.h> to declare localtime_r.
  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])

-  AC_REQUIRE([gl_HEADER_TIME_H_DEFAULTS])
+  AC_REQUIRE([gl_TIME_H_DEFAULTS])
  AC_REQUIRE([AC_C_RESTRICT])

  dnl Some systems don't declare localtime_r() and gmtime_r() if _REENTRANT is
--- a/m4/time_rz.m4
+++ b/m4/time_rz.m4
@ -10,7 +10,7 @@ dnl Written by Paul Eggert.
 AC_DEFUN([gl_TIME_RZ],
 [
  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
-  AC_REQUIRE([gl_HEADER_TIME_H_DEFAULTS])
+  AC_REQUIRE([gl_TIME_H_DEFAULTS])
  AC_REQUIRE([AC_STRUCT_TIMEZONE])

  # On Mac OS X 10.6, localtime loops forever with some time_t values.
--- a/m4/timegm.m4
+++ b/m4/timegm.m4
@ -1,4 +1,4 @@
-# timegm.m4 serial 12
+# timegm.m4 serial 13
 dnl Copyright (C) 2003, 2007, 2009-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@ -6,7 +6,7 @@ dnl with or without modifications, as long as this notice is preserved.

 AC_DEFUN([gl_FUNC_TIMEGM],
 [
-  AC_REQUIRE([gl_HEADER_TIME_H_DEFAULTS])
+  AC_REQUIRE([gl_TIME_H_DEFAULTS])
  AC_REQUIRE([gl_FUNC_MKTIME_WORKS])
  REPLACE_TIMEGM=0
  AC_CHECK_FUNCS_ONCE([timegm])
--- a/m4/tzset.m4
+++ b/m4/tzset.m4
@ -1,4 +1,4 @@
-# serial 15
+# serial 16

 # Copyright (C) 2003, 2007, 2009-2021 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
@ -9,7 +9,7 @@

 AC_DEFUN([gl_FUNC_TZSET],
 [
-  AC_REQUIRE([gl_HEADER_TIME_H_DEFAULTS])
+  AC_REQUIRE([gl_TIME_H_DEFAULTS])
  AC_REQUIRE([AC_CANONICAL_HOST])
  REPLACE_TZSET=0
  case "$host_os" in
--- a/m4/unistd_h.m4
+++ b/m4/unistd_h.m4
@ -1,4 +1,4 @@
-# unistd_h.m4 serial 85
+# unistd_h.m4 serial 89
 dnl Copyright (C) 2006-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@ -6,10 +6,10 @@ dnl with or without modifications, as long as this notice is preserved.

 dnl Written by Simon Josefsson, Bruno Haible.

-AC_DEFUN([gl_UNISTD_H],
+AC_DEFUN_ONCE([gl_UNISTD_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.
+  dnl Ensure to expand the default settings once only, before all statements
+  dnl that occur in other macros.
  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])

  gl_CHECK_NEXT_HEADERS([unistd.h])
@ -59,100 +59,116 @@ AC_DEFUN([gl_UNISTD_H],
  fi
 ])

+# gl_UNISTD_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_UNISTD_MODULE_INDICATOR],
 [
-  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
-  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
+  dnl Ensure to expand the default settings once only.
+  gl_UNISTD_H_REQUIRE_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])
 ])

+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_UNISTD_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_UNISTD_H_MODULE_INDICATOR_DEFAULTS], [
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ACCESS])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_CHDIR])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_CHOWN])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_CLOSE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_COPY_FILE_RANGE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_DUP])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_DUP2])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_DUP3])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ENVIRON])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_EUIDACCESS])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_EXECL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_EXECLE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_EXECLP])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_EXECV])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_EXECVE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_EXECVP])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_EXECVPE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FACCESSAT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FCHDIR])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FCHOWNAT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FDATASYNC])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FSYNC])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FTRUNCATE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETCWD])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETDOMAINNAME])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETDTABLESIZE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETENTROPY])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETGROUPS])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETHOSTNAME])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETLOGIN])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETLOGIN_R])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETOPT_POSIX])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETPAGESIZE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETPASS])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETUSERSHELL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GROUP_MEMBER])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ISATTY])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LCHOWN])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LINK])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LINKAT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LSEEK])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_PIPE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_PIPE2])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_PREAD])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_PWRITE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_READ])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_READLINK])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_READLINKAT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_RMDIR])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SETHOSTNAME])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SLEEP])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SYMLINK])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SYMLINKAT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TRUNCATE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TTYNAME_R])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNISTD_H_GETOPT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNISTD_H_NONBLOCKING])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNISTD_H_SIGPIPE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNLINK])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNLINKAT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_USLEEP])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WRITE])
+    dnl Support Microsoft deprecated alias function names by default.
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_ACCESS], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_CHDIR], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_CLOSE], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_DUP], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_DUP2], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_EXECL], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_EXECLE], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_EXECLP], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_EXECV], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_EXECVE], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_EXECVP], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_EXECVPE], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_GETCWD], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_GETPID], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_ISATTY], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_LSEEK], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_READ], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_RMDIR], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_SWAB], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_UNLINK], [1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_WRITE], [1])
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_UNISTD_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
+])
+
 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])
-  GNULIB_FDATASYNC=0;            AC_SUBST([GNULIB_FDATASYNC])
-  GNULIB_FSYNC=0;                AC_SUBST([GNULIB_FSYNC])
-  GNULIB_FTRUNCATE=0;            AC_SUBST([GNULIB_FTRUNCATE])
-  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])
-  GNULIB_GROUP_MEMBER=0;         AC_SUBST([GNULIB_GROUP_MEMBER])
-  GNULIB_ISATTY=0;               AC_SUBST([GNULIB_ISATTY])
-  GNULIB_LCHOWN=0;               AC_SUBST([GNULIB_LCHOWN])
-  GNULIB_LINK=0;                 AC_SUBST([GNULIB_LINK])
-  GNULIB_LINKAT=0;               AC_SUBST([GNULIB_LINKAT])
-  GNULIB_LSEEK=0;                AC_SUBST([GNULIB_LSEEK])
-  GNULIB_PIPE=0;                 AC_SUBST([GNULIB_PIPE])
-  GNULIB_PIPE2=0;                AC_SUBST([GNULIB_PIPE2])
-  GNULIB_PREAD=0;                AC_SUBST([GNULIB_PREAD])
-  GNULIB_PWRITE=0;               AC_SUBST([GNULIB_PWRITE])
-  GNULIB_READ=0;                 AC_SUBST([GNULIB_READ])
-  GNULIB_READLINK=0;             AC_SUBST([GNULIB_READLINK])
-  GNULIB_READLINKAT=0;           AC_SUBST([GNULIB_READLINKAT])
-  GNULIB_RMDIR=0;                AC_SUBST([GNULIB_RMDIR])
-  GNULIB_SETHOSTNAME=0;          AC_SUBST([GNULIB_SETHOSTNAME])
-  GNULIB_SLEEP=0;                AC_SUBST([GNULIB_SLEEP])
-  GNULIB_SYMLINK=0;              AC_SUBST([GNULIB_SYMLINK])
-  GNULIB_SYMLINKAT=0;            AC_SUBST([GNULIB_SYMLINKAT])
-  GNULIB_TRUNCATE=0;             AC_SUBST([GNULIB_TRUNCATE])
-  GNULIB_TTYNAME_R=0;            AC_SUBST([GNULIB_TTYNAME_R])
-  GNULIB_UNISTD_H_NONBLOCKING=0; AC_SUBST([GNULIB_UNISTD_H_NONBLOCKING])
-  GNULIB_UNISTD_H_SIGPIPE=0;     AC_SUBST([GNULIB_UNISTD_H_SIGPIPE])
-  GNULIB_UNLINK=0;               AC_SUBST([GNULIB_UNLINK])
-  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_COPY_FILE_RANGE=1; AC_SUBST([HAVE_COPY_FILE_RANGE])
--- a/m4/visibility.m4
+++ b/m4/visibility.m4
@ -1,4 +1,4 @@
-# visibility.m4 serial 7
+# visibility.m4 serial 8
 dnl Copyright (C) 2005, 2008, 2010-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@ -59,6 +59,10 @@ AC_DEFUN([gl_VISIBILITY],
              extern __attribute__((__visibility__("hidden"))) int hiddenfunc (void);
              extern __attribute__((__visibility__("default"))) int exportedfunc (void);
              void dummyfunc (void);
+              int hiddenvar;
+              int exportedvar;
+              int hiddenfunc (void) { return 51; }
+              int exportedfunc (void) { return 1225736919; }
              void dummyfunc (void) {}
            ]],
            [[]])],
--- a/m4/wchar_h.m4
+++ b/m4/wchar_h.m4
@ -7,9 +7,9 @@ dnl with or without modifications, as long as this notice is preserved.

 dnl Written by Eric Blake.

-# wchar_h.m4 serial 50
+# wchar_h.m4 serial 53

-AC_DEFUN([gl_WCHAR_H],
+AC_DEFUN_ONCE([gl_WCHAR_H],
 [
  AC_REQUIRE([gl_WCHAR_H_DEFAULTS])
  AC_REQUIRE([gl_WCHAR_H_INLINE_OK])
@ -125,60 +125,75 @@ Configuration aborted.])
  fi
 ])

+# gl_WCHAR_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_WCHAR_MODULE_INDICATOR],
 [
-  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
-  AC_REQUIRE([gl_WCHAR_H_DEFAULTS])
+  dnl Ensure to expand the default settings once only.
+  gl_WCHAR_H_REQUIRE_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])
 ])

+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_WCHAR_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_WCHAR_H_MODULE_INDICATOR_DEFAULTS], [
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_BTOWC])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCTOB])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBSINIT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBRTOWC])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBRLEN])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBSRTOWCS])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBSNRTOWCS])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCRTOMB])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCSRTOMBS])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCSNRTOMBS])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCWIDTH])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WMEMCHR])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WMEMCMP])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WMEMCPY])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WMEMMOVE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WMEMPCPY])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WMEMSET])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCSLEN])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCSNLEN])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCSCPY])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCPCPY])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCSNCPY])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCPNCPY])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCSCAT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCSNCAT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCSCMP])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCSNCMP])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCSCASECMP])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCSNCASECMP])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCSCOLL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCSXFRM])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCSDUP])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCSCHR])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCSRCHR])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCSCSPN])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCSSPN])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCSPBRK])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCSSTR])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCSTOK])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCSWIDTH])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCSFTIME])
+    dnl Support Microsoft deprecated alias function names by default.
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_WCSDUP], [1])
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_WCHAR_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_WCHAR_H_DEFAULTS])
+])
+
 AC_DEFUN([gl_WCHAR_H_DEFAULTS],
 [
-  GNULIB_BTOWC=0;       AC_SUBST([GNULIB_BTOWC])
-  GNULIB_WCTOB=0;       AC_SUBST([GNULIB_WCTOB])
-  GNULIB_MBSINIT=0;     AC_SUBST([GNULIB_MBSINIT])
-  GNULIB_MBRTOWC=0;     AC_SUBST([GNULIB_MBRTOWC])
-  GNULIB_MBRLEN=0;      AC_SUBST([GNULIB_MBRLEN])
-  GNULIB_MBSRTOWCS=0;   AC_SUBST([GNULIB_MBSRTOWCS])
-  GNULIB_MBSNRTOWCS=0;  AC_SUBST([GNULIB_MBSNRTOWCS])
-  GNULIB_WCRTOMB=0;     AC_SUBST([GNULIB_WCRTOMB])
-  GNULIB_WCSRTOMBS=0;   AC_SUBST([GNULIB_WCSRTOMBS])
-  GNULIB_WCSNRTOMBS=0;  AC_SUBST([GNULIB_WCSNRTOMBS])
-  GNULIB_WCWIDTH=0;     AC_SUBST([GNULIB_WCWIDTH])
-  GNULIB_WMEMCHR=0;     AC_SUBST([GNULIB_WMEMCHR])
-  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])
-  GNULIB_WCSCPY=0;      AC_SUBST([GNULIB_WCSCPY])
-  GNULIB_WCPCPY=0;      AC_SUBST([GNULIB_WCPCPY])
-  GNULIB_WCSNCPY=0;     AC_SUBST([GNULIB_WCSNCPY])
-  GNULIB_WCPNCPY=0;     AC_SUBST([GNULIB_WCPNCPY])
-  GNULIB_WCSCAT=0;      AC_SUBST([GNULIB_WCSCAT])
-  GNULIB_WCSNCAT=0;     AC_SUBST([GNULIB_WCSNCAT])
-  GNULIB_WCSCMP=0;      AC_SUBST([GNULIB_WCSCMP])
-  GNULIB_WCSNCMP=0;     AC_SUBST([GNULIB_WCSNCMP])
-  GNULIB_WCSCASECMP=0;  AC_SUBST([GNULIB_WCSCASECMP])
-  GNULIB_WCSNCASECMP=0; AC_SUBST([GNULIB_WCSNCASECMP])
-  GNULIB_WCSCOLL=0;     AC_SUBST([GNULIB_WCSCOLL])
-  GNULIB_WCSXFRM=0;     AC_SUBST([GNULIB_WCSXFRM])
-  GNULIB_WCSDUP=0;      AC_SUBST([GNULIB_WCSDUP])
-  GNULIB_WCSCHR=0;      AC_SUBST([GNULIB_WCSCHR])
-  GNULIB_WCSRCHR=0;     AC_SUBST([GNULIB_WCSRCHR])
-  GNULIB_WCSCSPN=0;     AC_SUBST([GNULIB_WCSCSPN])
-  GNULIB_WCSSPN=0;      AC_SUBST([GNULIB_WCSSPN])
-  GNULIB_WCSPBRK=0;     AC_SUBST([GNULIB_WCSPBRK])
-  GNULIB_WCSSTR=0;      AC_SUBST([GNULIB_WCSSTR])
-  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])
--- a/m4/wctype_h.m4
+++ b/m4/wctype_h.m4
@ -1,4 +1,4 @@
-# wctype_h.m4 serial 26
+# wctype_h.m4 serial 30

 dnl A placeholder for ISO C99 <wctype.h>, for platforms that lack it.

@ -9,7 +9,7 @@ dnl with or without modifications, as long as this notice is preserved.

 dnl Written by Paul Eggert.

-AC_DEFUN([gl_WCTYPE_H],
+AC_DEFUN_ONCE([gl_WCTYPE_H],
 [
  AC_REQUIRE([gl_WCTYPE_H_DEFAULTS])
  AC_REQUIRE([AC_PROG_CC])
@ -62,7 +62,7 @@ AC_DEFUN([gl_WCTYPE_H],
  fi
  AC_SUBST([HAVE_WCTYPE_H])

-  if test $GNULIB_OVERRIDES_WINT_T = 1; then
+  if test $GNULIBHEADERS_OVERRIDE_WINT_T = 1; then
    REPLACE_ISWCNTRL=1
  else
    case "$gl_cv_func_iswcntrl_works" in
@ -157,24 +157,39 @@ AC_DEFUN([gl_WCTYPE_H],
    ])
 ])

+# gl_WCTYPE_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_WCTYPE_MODULE_INDICATOR],
 [
-  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
-  AC_REQUIRE([gl_WCTYPE_H_DEFAULTS])
+  dnl Ensure to expand the default settings once only.
+  gl_WCTYPE_H_REQUIRE_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])
 ])

+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_WCTYPE_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_WCTYPE_H_MODULE_INDICATOR_DEFAULTS], [
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ISWBLANK])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ISWDIGIT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ISWXDIGIT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCTYPE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ISWCTYPE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCTRANS])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TOWCTRANS])
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_WCTYPE_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_WCTYPE_H_DEFAULTS])
+])
+
 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])
-  GNULIB_TOWCTRANS=0;   AC_SUBST([GNULIB_TOWCTRANS])
  dnl Assume proper GNU behavior unless another module says otherwise.
  HAVE_ISWBLANK=1;      AC_SUBST([HAVE_ISWBLANK])
  HAVE_WCTYPE_T=1;      AC_SUBST([HAVE_WCTYPE_T])
--- a/m4/wint_t.m4
+++ b/m4/wint_t.m4
@ -1,4 +1,4 @@
-# wint_t.m4 serial 10
+# wint_t.m4 serial 11
 dnl Copyright (C) 2003, 2007-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@ -34,14 +34,14 @@ AC_DEFUN([gt_TYPE_WINT_T],
         [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
+      GNULIBHEADERS_OVERRIDE_WINT_T=1
    else
-      GNULIB_OVERRIDES_WINT_T=0
+      GNULIBHEADERS_OVERRIDE_WINT_T=0
    fi
  else
-    GNULIB_OVERRIDES_WINT_T=0
+    GNULIBHEADERS_OVERRIDE_WINT_T=0
  fi
-  AC_SUBST([GNULIB_OVERRIDES_WINT_T])
+  AC_SUBST([GNULIBHEADERS_OVERRIDE_WINT_T])
 ])

 dnl Prerequisites of the 'wint_t' override.
--- a/m4/year2038.m4
+++ b/m4/year2038.m4
@ -0,0 +1,124 @@
+# year2038.m4 serial 7
+dnl Copyright (C) 2017-2021 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 Attempt to ensure that 'time_t' can go past the year 2038 and that
+dnl the functions 'time', 'stat', etc. work with post-2038 timestamps.
+
+AC_DEFUN([gl_YEAR2038_EARLY],
+[
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  case "$host_os" in
+    mingw*)
+      AC_DEFINE([__MINGW_USE_VC2005_COMPAT], [1],
+        [For 64-bit time_t on 32-bit mingw.])
+      ;;
+  esac
+])
+
+# gl_YEAR2038_TEST_INCLUDES
+# -------------------------
+AC_DEFUN([gl_YEAR2038_TEST_INCLUDES],
+[[
+  #include <time.h>
+  /* Check that time_t can represent 2**32 - 1 correctly.  */
+  #define LARGE_TIME_T \\
+    ((time_t) (((time_t) 1 << 30) - 1 + 3 * ((time_t) 1 << 30)))
+  int verify_time_t_range[(LARGE_TIME_T / 65537 == 65535
+                           && LARGE_TIME_T % 65537 == 0)
+                          ? 1 : -1];
+]])
+
+# gl_YEAR2038_BODY(REQUIRE-YEAR2038-SAFE)
+-----------------------------------------
+AC_DEFUN([gl_YEAR2038_BODY],
+[
+ AC_ARG_ENABLE([year2038],
+   [  --disable-year2038      omit support for timestamps past the year 2038])
+ AS_IF([test "$enable_year2038" != no],
+ [
+  dnl On many systems, time_t is already a 64-bit type.
+  dnl On those systems where time_t is still 32-bit, it requires kernel
+  dnl and libc support to make it 64-bit. For glibc 2.34 and later on Linux,
+  dnl defining _TIME_BITS=64 and _FILE_OFFSET_BITS=64 is needed on x86 and ARM.
+  dnl
+  dnl On native Windows, the system include files define types __time32_t
+  dnl and __time64_t. By default, time_t is an alias of
+  dnl   - __time32_t on 32-bit mingw,
+  dnl   - __time64_t on 64-bit mingw and on MSVC (since MSVC 8).
+  dnl But when compiling with -D__MINGW_USE_VC2005_COMPAT, time_t is an
+  dnl alias of __time64_t.
+  dnl And when compiling with -D_USE_32BIT_TIME_T, time_t is an alias of
+  dnl __time32_t.
+  AC_CACHE_CHECK([for time_t past the year 2038], [gl_cv_type_time_t_y2038],
+    [AC_COMPILE_IFELSE(
+       [AC_LANG_SOURCE([gl_YEAR2038_TEST_INCLUDES])],
+       [gl_cv_type_time_t_y2038=yes], [gl_cv_type_time_t_y2038=no])
+    ])
+  if test "$gl_cv_type_time_t_y2038" = no; then
+    AC_CACHE_CHECK([for 64-bit time_t with _TIME_BITS=64],
+      [gl_cv_type_time_t_bits_macro],
+      [AC_COMPILE_IFELSE(
+         [AC_LANG_SOURCE([[#define _TIME_BITS 64
+                           #define _FILE_OFFSET_BITS 64
+                           ]gl_YEAR2038_TEST_INCLUDES])],
+         [gl_cv_type_time_t_bits_macro=yes],
+         [gl_cv_type_time_t_bits_macro=no])
+      ])
+    if test "$gl_cv_type_time_t_bits_macro" = yes; then
+      AC_DEFINE([_TIME_BITS], [64],
+        [Number of bits in a timestamp, on hosts where this is settable.])
+      dnl AC_SYS_LARGFILE also defines this; it's OK if we do too.
+      AC_DEFINE([_FILE_OFFSET_BITS], [64],
+        [Number of bits in a file offset, on hosts where this is settable.])
+      gl_cv_type_time_t_y2038=yes
+    fi
+  fi
+  if test $gl_cv_type_time_t_y2038 = no; then
+    AC_COMPILE_IFELSE(
+      [AC_LANG_SOURCE(
+         [[#ifdef _USE_32BIT_TIME_T
+             int ok;
+           #else
+             error fail
+           #endif
+         ]])],
+      [AC_MSG_FAILURE(
+         [The 'time_t' type stops working after January 2038.
+          Remove _USE_32BIT_TIME_T from the compiler flags.])],
+      [# If not cross-compiling and $1 says we should check,
+       # and 'touch' works with a large timestamp, then evidently wider time_t
+       # is desired and supported, so fail and ask the builder to fix the
+       # problem.  Otherwise, just warn the builder.
+       m4_ifval([$1],
+         [if test $cross_compiling = no \
+             && TZ=UTC0 touch -t 210602070628.15 conftest.time 2>/dev/null; then
+            case `TZ=UTC0 LC_ALL=C ls -l conftest.time 2>/dev/null` in
+              *'Feb  7  2106'* | *'Feb  7 17:10'*)
+                AC_MSG_FAILURE(
+                  [The 'time_t' type stops working after January 2038,
+                   and your system appears to support a wider 'time_t'.
+                   Try configuring with 'CC="${CC} -m64"'.
+                   To build with a 32-bit time_t anyway (not recommended),
+                   configure with '--disable-year2038'.]);;
+            esac
+            rm -f conftest.time
+          fi])
+       if test "$gl_warned_about_y2038" != yes; then
+         AC_MSG_WARN(
+           [The 'time_t' type stops working after January 2038,
+            and this package needs a wider 'time_t' type
+            if there is any way to access timestamps after that.
+            Configure with 'CC="${CC} -m64"' perhaps?])
+         gl_warned_about_y2038=yes
+       fi
+      ])
+  fi])
+])
+
+AC_DEFUN([gl_YEAR2038],
+[
+  gl_YEAR2038_BODY([require-year2038-safe])
+])