diff --git a/bootstrap b/bootstrap
index ede0778..3173829 100755
--- a/bootstrap
+++ b/bootstrap
@@ -3,7 +3,7 @@
 
 # Bootstrap this package from checked-out sources.
 
-scriptversion=2022-12-27.07; # UTC
+scriptversion=2023-12-10.18; # UTC
 
 # Copyright (C) 2003-2024 Free Software Foundation, Inc.
 #
@@ -37,7 +37,7 @@ medir=`dirname "$me"`
 
 # A library of shell functions for autopull.sh, autogen.sh, and bootstrap.
 
-scriptlibversion=2023-01-06.19; # UTC
+scriptlibversion=2023-12-10.18; # UTC
 
 # Copyright (C) 2003-2024 Free Software Foundation, Inc.
 #
@@ -340,7 +340,7 @@ check_versions() {
     # Handle the still-experimental Automake-NG programs specially.
     # They remain named as the mainstream Automake programs ("automake",
     # and "aclocal") to avoid gratuitous incompatibilities with
-    # pre-existing usages (by, say, autoreconf, or custom autogen.sh
+    # preexisting usages (by, say, autoreconf, or custom autogen.sh
     # scripts), but correctly identify themselves (as being part of
     # "GNU automake-ng") when asked their version.
     case $app in
@@ -497,7 +497,8 @@ prepare_GNULIB_SRCDIR ()
     # We already checked that $GNULIB_SRCDIR references a directory.
     # Verify that it contains a gnulib checkout.
     test -f "$GNULIB_SRCDIR/gnulib-tool" \
-      || die "Error: --gnulib-srcdir or \$GNULIB_SRCDIR is specified, but does not contain gnulib-tool"
+      || die "Error: --gnulib-srcdir or \$GNULIB_SRCDIR is specified," \
+             "but does not contain gnulib-tool"
   elif $use_git; then
     gnulib_path=$(git_modules_config submodule.gnulib.path)
     test -z "$gnulib_path" && gnulib_path=gnulib
@@ -558,7 +559,8 @@ prepare_GNULIB_SRCDIR ()
           # be processed, which can drastically reduce download and processing
           # time for checkout. If the fetch by commit fails, a shallow fetch can
           # not be performed because we do not know what the depth of the commit
-          # is without fetching all commits. So fallback to fetching all commits.
+          # is without fetching all commits. So fall back to fetching all
+          # commits.
           git -C "$gnulib_path" init
           git -C "$gnulib_path" remote add origin \
               ${GNULIB_URL:-$default_gnulib_url}
@@ -574,7 +576,8 @@ prepare_GNULIB_SRCDIR ()
     GNULIB_SRCDIR=$gnulib_path
     # Verify that the submodule contains a gnulib checkout.
     test -f "$gnulib_path/gnulib-tool" \
-      || die "Error: $gnulib_path is supposed to contain a gnulib checkout, but does not contain gnulib-tool"
+      || die "Error: $gnulib_path is supposed to contain a gnulib checkout," \
+             "but does not contain gnulib-tool"
   fi
 
   # XXX Should this be done if $use_git is false?
@@ -594,7 +597,8 @@ upgrade_bootstrap ()
   if test -f "$medir"/bootstrap-funclib.sh; then
     update_lib=true
     { cmp -s "$medir"/bootstrap "$GNULIB_SRCDIR/top/bootstrap" \
-      && cmp -s "$medir"/bootstrap-funclib.sh "$GNULIB_SRCDIR/top/bootstrap-funclib.sh" \
+      && cmp -s "$medir"/bootstrap-funclib.sh \
+                "$GNULIB_SRCDIR/top/bootstrap-funclib.sh" \
       && cmp -s "$medir"/autopull.sh "$GNULIB_SRCDIR/top/autopull.sh" \
       && cmp -s "$medir"/autogen.sh "$GNULIB_SRCDIR/top/autogen.sh"; \
     }
@@ -611,10 +615,18 @@ upgrade_bootstrap ()
       a) ignored=--;;
       *) ignored=ignored;;
     esac
+    u=$update_lib
     exec sh -c \
-      '{ if '$update_lib' && test -f "$1"; then cp "$1" "$3"; else cp "$2" "$3"; fi; } && { if '$update_lib' && test -f "$4"; then cp "$4" "$5"; else rm -f "$5"; fi; } && { if '$update_lib' && test -f "$6"; then cp "$6" "$7"; else rm -f "$7"; fi; } && { if '$update_lib' && test -f "$8"; then cp "$8" "$9"; else rm -f "$9"; fi; } && shift && shift && shift && shift && shift && shift && shift && shift && shift && exec "${CONFIG_SHELL-/bin/sh}" "$@"' \
+      '{ if '$u' && test -f "$1"; then cp "$1" "$3"; else cp "$2" "$3"; fi; } &&
+       { if '$u' && test -f "$4"; then cp "$4" "$5"; else rm -f "$5"; fi; } &&
+       { if '$u' && test -f "$6"; then cp "$6" "$7"; else rm -f "$7"; fi; } &&
+       { if '$u' && test -f "$8"; then cp "$8" "$9"; else rm -f "$9"; fi; } &&
+       shift && shift && shift && shift && shift &&
+       shift && shift && shift && shift &&
+       exec "${CONFIG_SHELL-/bin/sh}" "$@"' \
       $ignored \
-      "$GNULIB_SRCDIR/top/bootstrap" "$GNULIB_SRCDIR/build-aux/bootstrap" "$medir/bootstrap" \
+      "$GNULIB_SRCDIR/top/bootstrap" "$GNULIB_SRCDIR/build-aux/bootstrap" \
+      "$medir/bootstrap" \
       "$GNULIB_SRCDIR/top/bootstrap-funclib.sh" "$medir/bootstrap-funclib.sh" \
       "$GNULIB_SRCDIR/top/autopull.sh" "$medir/autopull.sh" \
       "$GNULIB_SRCDIR/top/autogen.sh" "$medir/autogen.sh" \
@@ -647,7 +659,9 @@ Optional environment variables:
                            Use this if you already have gnulib sources
                            and history on your machine, and do not want
                            to waste your bandwidth downloading them again.
-  GNULIB_URL               Cloneable URL of the gnulib repository.
+  GNULIB_URL               URL of the gnulib repository.  The default is
+                           $default_gnulib_url,
+                           which is Gnulib's upstream repository.
 
 Options:
   --bootstrap-sync         if this bootstrap script is not identical to
@@ -747,9 +761,12 @@ autopull()
   done
 
   $use_git || test -n "$GNULIB_SRCDIR" \
-    || die "Error: --no-git requires \$GNULIB_SRCDIR environment variable or --gnulib-srcdir option"
+    || die "Error: --no-git requires \$GNULIB_SRCDIR environment variable" \
+           "or --gnulib-srcdir option"
   test -z "$GNULIB_SRCDIR" || test -d "$GNULIB_SRCDIR" \
-    || die "Error: \$GNULIB_SRCDIR environment variable or --gnulib-srcdir option is specified, but does not denote a directory"
+    || die "Error: \$GNULIB_SRCDIR environment variable" \
+           "or --gnulib-srcdir option is specified," \
+           "but does not denote a directory"
 
   if test -n "$checkout_only_file" && test ! -r "$checkout_only_file"; then
     die "Running this script from a non-checked-out distribution is risky."
@@ -760,7 +777,7 @@ autopull()
   if $use_gnulib || $bootstrap_sync; then
     prepare_GNULIB_SRCDIR
     if $bootstrap_sync; then
-      upgrade_bootstrap
+      upgrade_bootstrap "$@"
     fi
   fi
 
@@ -811,7 +828,10 @@ autopull()
       uninitialized=`echo "$uninitialized" | grep -v '^gnulib$'`
     fi
     if test -n "$uninitialized"; then
-      die "Some git submodules are not initialized: "`echo "$uninitialized" | tr '\n' ',' | sed -e 's|,$|.|'`" Either use option '--no-git', or run 'git submodule update --init' and bootstrap again."
+      uninit_comma=`echo "$uninitialized" | tr '\n' ',' | sed -e 's|,$|.|'`
+      die "Some git submodules are not initialized: "$uninit_comma \
+          "Either use option '--no-git'," \
+          "or run 'git submodule update --init' and bootstrap again."
     fi
   fi
 
@@ -978,7 +998,7 @@ symlink_to_dir()
       for dot_ig in x $vc_ignore; do
         test $dot_ig = x && continue
         ig=$parent/$dot_ig
-        insert_vc_ignore $ig "${dst_dir##*/}"
+        insert_vc_ignore $ig "${dst_dir##*/}/"
       done
     fi
 
@@ -1075,7 +1095,8 @@ autogen()
   done
 
   test -z "$GNULIB_SRCDIR" || test -d "$GNULIB_SRCDIR" \
-    || die "Error: \$GNULIB_SRCDIR environment variable or --gnulib-srcdir option is specified, but does not denote a directory"
+    || die "Error: \$GNULIB_SRCDIR environment variable or --gnulib-srcdir" \
+           "option is specified, but does not denote a directory"
 
   if test -n "$checkout_only_file" && test ! -r "$checkout_only_file"; then
     die "Running this script from a non-checked-out distribution is risky."
@@ -1083,7 +1104,8 @@ autogen()
 
   if $use_gnulib; then
     if test -z "$GNULIB_SRCDIR"; then
-      gnulib_path=$(test -f .gitmodules && git config --file .gitmodules submodule.gnulib.path)
+      gnulib_path=$(test -f .gitmodules &&
+                    git config --file .gitmodules submodule.gnulib.path)
       test -z "$gnulib_path" && gnulib_path=gnulib
       GNULIB_SRCDIR=$gnulib_path
     fi
@@ -1104,7 +1126,7 @@ autogen()
     mkdir $build_aux
     for dot_ig in x $vc_ignore; do
       test $dot_ig = x && continue
-      insert_vc_ignore $dot_ig $build_aux
+      insert_vc_ignore $dot_ig $build_aux/
     done
   fi
 
@@ -1236,14 +1258,7 @@ autogen()
   # Invoke autoreconf with --force --install to ensure upgrades of tools
   # such as ylwrap.
   AUTORECONFFLAGS="--verbose --install --force -I $m4_base $ACLOCAL_FLAGS"
-
-  # Some systems (RHEL 5) are using ancient autotools, for which the
-  # --no-recursive option had not been invented.  Detect that lack and
-  # omit the option when it's not supported.  FIXME in 2017: remove this
-  # hack when RHEL 5 autotools are updated, or when they become irrelevant.
-  case $($AUTORECONF --help) in
-    *--no-recursive*) AUTORECONFFLAGS="$AUTORECONFFLAGS --no-recursive";;
-  esac
+  AUTORECONFFLAGS="$AUTORECONFFLAGS --no-recursive"
 
   # Tell autoreconf not to invoke autopoint or libtoolize; they were run above.
   echo "running: AUTOPOINT=true LIBTOOLIZE=true $AUTORECONF $AUTORECONFFLAGS"
@@ -1334,7 +1349,9 @@ Optional environment variables:
                            have gnulib sources on your machine, and
                            do not want to waste your bandwidth downloading
                            them again.
-  GNULIB_URL               Cloneable URL of the gnulib repository.
+  GNULIB_URL               URL of the gnulib repository.  The default is
+                           $default_gnulib_url,
+                           which is Gnulib's upstream repository.
 
 Options:
 
@@ -1465,9 +1482,11 @@ done
 $pull || $gen || pull=true gen=true
 
 $use_git || test -n "$GNULIB_SRCDIR" \
-  || die "Error: --no-git requires \$GNULIB_SRCDIR environment variable or --gnulib-srcdir option"
+  || die "Error: --no-git requires \$GNULIB_SRCDIR environment variable" \
+         "or --gnulib-srcdir option"
 test -z "$GNULIB_SRCDIR" || test -d "$GNULIB_SRCDIR" \
-  || die "Error: \$GNULIB_SRCDIR environment variable or --gnulib-srcdir option is specified, but does not denote a directory"
+  || die "Error: \$GNULIB_SRCDIR environment variable or --gnulib-srcdir" \
+         "option is specified, but does not denote a directory"
 
 if test -n "$checkout_only_file" && test ! -r "$checkout_only_file"; then
   die "Bootstrapping from a non-checked-out distribution is risky."
@@ -1477,7 +1496,7 @@ check_build_prerequisites $use_git
 
 if $bootstrap_sync; then
   prepare_GNULIB_SRCDIR
-  upgrade_bootstrap
+  upgrade_bootstrap "$@"
   # Since we have now upgraded if needed, no need to try it a second time below.
   bootstrap_sync=false
 fi
@@ -1490,7 +1509,11 @@ export GNULIB_REFDIR
 
 if $pull && { $use_git || test -z "$SKIP_PO"; }; then
   autopull \
-      `if $bootstrap_sync; then echo ' --bootstrap-sync'; else echo ' --no-bootstrap-sync'; fi` \
+      `if $bootstrap_sync; then
+         echo ' --bootstrap-sync'
+       else
+         echo ' --no-bootstrap-sync'
+       fi` \
       `if test -z "$checkout_only_file"; then echo ' --force'; fi` \
       `if ! $use_git; then echo ' --no-git'; fi` \
       `if test -n "$SKIP_PO"; then echo ' --skip-po'; fi` \
diff --git a/gnulib b/gnulib
index 5ec3136..99ce3a0 160000
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 5ec3136235d7a0d5db77a474c40e35edd47b6dd7
+Subproject commit 99ce3a004a2974c71f510f5df5bc6be7e2811d30
diff --git a/lib/.gitignore b/lib/.gitignore
index 2adc903..3a1ab19 100644
--- a/lib/.gitignore
+++ b/lib/.gitignore
@@ -203,23 +203,28 @@
 /tempname.h
 /time.h
 /time.in.h
+/uchar.h
+/unicase.h
+/unictype.h
+/uninorm.h
 /unistd.c
 /unistd.h
 /unistd.in.h
+/unitypes.h
 /unlocked-io.h
 /verify.h
-/version-etc-fsf.c
 /version-etc.c
+/version-etc-fsf.c
 /version-etc.h
 /warn-on-use.h
 /wchar.h
 /wchar.in.h
 /wcrtomb.c
 /wctob.c
-/wctomb-impl.h
 /wctomb.c
-/wctype-h.c
+/wctomb-impl.h
 /wctype.h
+/wctype-h.c
 /wctype.in.h
 /windows-initguard.h
 /windows-mutex.c
@@ -231,6 +236,6 @@
 /windows-rwlock.c
 /windows-rwlock.h
 /xalloc-die.c
-/xalloc-oversized.h
 /xalloc.h
+/xalloc-oversized.h
 /xmalloc.c
diff --git a/testsuite/init.sh b/testsuite/init.sh
index ec9317b..aef5eea 100644
--- a/testsuite/init.sh
+++ b/testsuite/init.sh
@@ -646,18 +646,19 @@ compare_dev_null_ ()
 
 for diff_opt_ in -u -U3 -c '' no; do
   test "$diff_opt_" != no &&
-    diff_out_=`exec 2>/dev/null; diff $diff_opt_ "$0" "$0" < /dev/null` &&
+    diff_out_=`exec 2>/dev/null
+      LC_ALL=C diff $diff_opt_ "$0" "$0" < /dev/null` &&
     break
 done
 if test "$diff_opt_" != no; then
   if test -z "$diff_out_"; then
-    compare_ () { diff $diff_opt_ "$@"; }
+    compare_ () { LC_ALL=C diff $diff_opt_ "$@"; }
   else
     compare_ ()
     {
       # If no differences were found, AIX and HP-UX 'diff' produce output
       # like "No differences encountered".  Hide this output.
-      diff $diff_opt_ "$@" > diff.out
+      LC_ALL=C diff $diff_opt_ "$@" > diff.out
       diff_status_=$?
       test $diff_status_ -eq 0 || cat diff.out || diff_status_=2
       rm -f diff.out || diff_status_=2
@@ -702,4 +703,4 @@ test -f "$srcdir/init.cfg" \
 setup_ "$@"
 # This trap is here, rather than in the setup_ function, because some
 # shells run the exit trap at shell function exit, rather than script exit.
-trap remove_tmp_ 0
+trap remove_tmp_ EXIT