; Update from Gnulib

9 files changed, 723 insertions, 172 deletions

diff --git a/m4/exponentd.m4 b/m4/exponentd.m4
index 2ef46437deb..163114b89ec 100644
--- a/m4/exponentd.m4
+++ b/m4/exponentd.m4
@@ -1,9 +1,9 @@
-# exponentd.m4 serial 3
+# exponentd.m4 serial 4
 dnl Copyright (C) 2007-2008, 2010-2023 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_DOUBLE_EXPONENT_LOCATION],
+AC_DEFUN_ONCE([gl_DOUBLE_EXPONENT_LOCATION],
 [
   AC_CACHE_CHECK([where to find the exponent in a 'double'],
     [gl_cv_cc_double_expbit0],
diff --git a/m4/exponentf.m4 b/m4/exponentf.m4
index f6395f23f27..e761883939b 100644
--- a/m4/exponentf.m4
+++ b/m4/exponentf.m4
@@ -1,9 +1,9 @@
-# exponentf.m4 serial 2
+# exponentf.m4 serial 3
 dnl Copyright (C) 2007-2008, 2010-2023 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_FLOAT_EXPONENT_LOCATION],
+AC_DEFUN_ONCE([gl_FLOAT_EXPONENT_LOCATION],
 [
   AC_CACHE_CHECK([where to find the exponent in a 'float'],
     [gl_cv_cc_float_expbit0],
diff --git a/m4/exponentl.m4 b/m4/exponentl.m4
index e1fa5c48cc7..bc5638737e5 100644
--- a/m4/exponentl.m4
+++ b/m4/exponentl.m4
@@ -1,9 +1,9 @@
-# exponentl.m4 serial 5
+# exponentl.m4 serial 6
 dnl Copyright (C) 2007-2023 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_LONG_DOUBLE_EXPONENT_LOCATION],
+AC_DEFUN_ONCE([gl_LONG_DOUBLE_EXPONENT_LOCATION],
 [
   AC_REQUIRE([gl_BIGENDIAN])
   AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
diff --git a/m4/gnulib-comp.m4 b/m4/gnulib-comp.m4
index 9f701e95211..4c1e41daf51 100644
--- a/m4/gnulib-comp.m4
+++ b/m4/gnulib-comp.m4
@@ -232,12 +232,9 @@ AC_DEFUN([gl_EARLY],
   # Code from module vla:
   # Code from module warnings:
   # Code from module xalloc-oversized:
-<<<<<<< HEAD
   # Code from module xsize:
-=======
   # Code from module year2038:
   AC_REQUIRE([AC_SYS_YEAR2038])
->>>>>>> origin/master
 ])
 
 # This macro should be invoked from ./configure.ac, in the section
@@ -803,7 +800,7 @@ AC_DEFUN([gl_INIT],
   }
   func_gl_gnulib_m4code_fseterr ()
   {
-    if ! $gl_gnulib_enabled_fseterr; then
+    if $gl_gnulib_enabled_fseterr; then :; else
       gl_FUNC_FSETERR
       gl_CONDITIONAL([GL_COND_OBJ_FSETERR], [test $ac_cv_func___fseterr = no])
       gl_gnulib_enabled_fseterr=true
@@ -811,7 +808,7 @@ AC_DEFUN([gl_INIT],
   }
   func_gl_gnulib_m4code_getdelim ()
   {
-    if ! $gl_gnulib_enabled_getdelim; then
+    if $gl_gnulib_enabled_getdelim; then :; else
       gl_FUNC_GETDELIM
       gl_CONDITIONAL([GL_COND_OBJ_GETDELIM],
                      [test $HAVE_GETDELIM = 0 || test $REPLACE_GETDELIM = 1])
@@ -892,7 +889,7 @@ AC_DEFUN([gl_INIT],
   }
   func_gl_gnulib_m4code_3f0e593033d1fc2c127581960f641b66 ()
   {
-    if ! $gl_gnulib_enabled_3f0e593033d1fc2c127581960f641b66; then
+    if $gl_gnulib_enabled_3f0e593033d1fc2c127581960f641b66; then :; else
       gl_FUNC_ISNANF_NO_LIBM
       if test $gl_func_isnanf_no_libm != yes; then
         AC_LIBOBJ([isnanf])
@@ -1029,7 +1026,7 @@ AC_DEFUN([gl_INIT],
   }
   func_gl_gnulib_m4code_size_max ()
   {
-    if ! $gl_gnulib_enabled_size_max; then
+    if $gl_gnulib_enabled_size_max; then :; else
       gl_SIZE_MAX
       gl_gnulib_enabled_size_max=true
     fi
@@ -1056,7 +1053,7 @@ AC_DEFUN([gl_INIT],
   }
   func_gl_gnulib_m4code_vasnprintf ()
   {
-    if ! $gl_gnulib_enabled_vasnprintf; then
+    if $gl_gnulib_enabled_vasnprintf; then :; else
       AC_REQUIRE([AC_C_RESTRICT])
       gl_FUNC_VASNPRINTF
       gl_gnulib_enabled_vasnprintf=true
@@ -1065,7 +1062,7 @@ AC_DEFUN([gl_INIT],
   }
   func_gl_gnulib_m4code_ed5616be3593d355b981ffab56b9f37b ()
   {
-    if ! $gl_gnulib_enabled_ed5616be3593d355b981ffab56b9f37b; then
+    if $gl_gnulib_enabled_ed5616be3593d355b981ffab56b9f37b; then :; else
       gl_FUNC_VFPRINTF_POSIX
       gl_STDIO_MODULE_INDICATOR([vfprintf-posix])
       gl_MODULE_INDICATOR([vfprintf-posix])
@@ -1086,7 +1083,7 @@ AC_DEFUN([gl_INIT],
   }
   func_gl_gnulib_m4code_xsize ()
   {
-    if ! $gl_gnulib_enabled_xsize; then
+    if $gl_gnulib_enabled_xsize; then :; else
       gl_XSIZE
       gl_gnulib_enabled_xsize=true
       func_gl_gnulib_m4code_size_max
@@ -1749,7 +1746,7 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/pipe2.m4
   m4/printf-frexp.m4
   m4/printf-frexpl.m4
-  m4/printf-posix-rpl.m4
+  m4/printf-posix.m4
   m4/printf.m4
   m4/pselect.m4
   m4/pthread_sigmask.m4
diff --git a/m4/printf-posix.m4 b/m4/printf-posix.m4
new file mode 100644
index 00000000000..9aebf4002d6
--- /dev/null
+++ b/m4/printf-posix.m4
@@ -0,0 +1,36 @@
+# printf-posix.m4 serial 5
+dnl Copyright (C) 2007-2023 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_FUNC_PRINTF_POSIX],
+[
+  AC_REQUIRE([gl_FUNC_PRINTF_IS_POSIX])
+  if test $gl_cv_func_printf_posix = no; then
+    gl_PREREQ_VASNPRINTF_WITH_POSIX_EXTRAS
+    gl_REPLACE_VASNPRINTF
+    gl_REPLACE_PRINTF
+  fi
+])
+
+dnl Test whether printf is POSIX compliant.
+dnl Result is gl_cv_func_printf_posix.
+AC_DEFUN([gl_FUNC_PRINTF_IS_POSIX],
+[
+  AC_REQUIRE([gl_FUNC_VFPRINTF_IS_POSIX])
+  gl_cv_func_printf_posix="$gl_cv_func_vfprintf_posix"
+])
+
+AC_DEFUN([gl_REPLACE_PRINTF],
+[
+  AC_REQUIRE([gl_STDIO_H_DEFAULTS])
+  AC_REQUIRE([gl_ASM_SYMBOL_PREFIX])
+  AC_LIBOBJ([printf])
+  REPLACE_PRINTF=1
+  AC_DEFINE([REPLACE_PRINTF_POSIX], [1],
+    [Define if printf is overridden by a POSIX compliant gnulib implementation.])
+  gl_PREREQ_PRINTF
+])
+
+AC_DEFUN([gl_PREREQ_PRINTF], [:])
diff --git a/m4/printf.m4 b/m4/printf.m4
index de98a870e98..efb85a57afd 100644
--- a/m4/printf.m4
+++ b/m4/printf.m4
@@ -1,4 +1,4 @@
-# printf.m4 serial 74
+# printf.m4 serial 82
 dnl Copyright (C) 2003, 2007-2023 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -101,6 +101,92 @@ changequote([,])dnl
     ])
 ])
 
+dnl Test whether the *printf family of functions supports the 'w8', 'w16',
+dnl 'w32', 'w64', 'wf8', 'wf16', 'wf32', 'wf64' size specifiers. (ISO C23)
+dnl Result is gl_cv_func_printf_sizes_c23.
+
+AC_DEFUN([gl_PRINTF_SIZES_C23],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([gl_AC_HEADER_STDINT_H])
+  AC_REQUIRE([gl_AC_HEADER_INTTYPES_H])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CACHE_CHECK([whether printf supports size specifiers as in C23],
+    [gl_cv_func_printf_sizes_c23],
+    [
+      AC_RUN_IFELSE(
+        [AC_LANG_SOURCE([[
+#include <stddef.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/types.h>
+#if HAVE_STDINT_H_WITH_UINTMAX
+# include <stdint.h>
+#endif
+#if HAVE_INTTYPES_H_WITH_UINTMAX
+# include <inttypes.h>
+#endif
+static char buf[100];
+int main ()
+{
+  int result = 0;
+  buf[0] = '\0';
+  if (sprintf (buf, "%w8u %d", (uint8_t) 123, 33, 44, 55) < 0
+      || strcmp (buf, "123 33") != 0)
+    result |= 1;
+  buf[0] = '\0';
+  if (sprintf (buf, "%wf8u %d", (uint_fast8_t) 123, 33, 44, 55) < 0
+      || strcmp (buf, "123 33") != 0)
+    result |= 1;
+  buf[0] = '\0';
+  if (sprintf (buf, "%w16u %d", (uint16_t) 12345, 33, 44, 55) < 0
+      || strcmp (buf, "12345 33") != 0)
+    result |= 2;
+  buf[0] = '\0';
+  if (sprintf (buf, "%wf16u %d", (uint_fast16_t) 12345, 33, 44, 55) < 0
+      || strcmp (buf, "12345 33") != 0)
+    result |= 2;
+  buf[0] = '\0';
+  if (sprintf (buf, "%w32u %d", (uint32_t) 12345671, 33, 44, 55) < 0
+      || strcmp (buf, "12345671 33") != 0)
+    result |= 4;
+  buf[0] = '\0';
+  if (sprintf (buf, "%wf32u %d", (uint_fast32_t) 12345671, 33, 44, 55) < 0
+      || strcmp (buf, "12345671 33") != 0)
+    result |= 4;
+#if HAVE_STDINT_H_WITH_UINTMAX || HAVE_INTTYPES_H_WITH_UINTMAX
+  buf[0] = '\0';
+  if (sprintf (buf, "%w64u %d", (uint64_t) 12345671, 33, 44, 55) < 0
+      || strcmp (buf, "12345671 33") != 0)
+    result |= 8;
+  buf[0] = '\0';
+  if (sprintf (buf, "%wf64u %d", (uint_fast64_t) 12345671, 33, 44, 55) < 0
+      || strcmp (buf, "12345671 33") != 0)
+    result |= 8;
+#else
+  result |= 8;
+#endif
+  return result;
+}]])],
+        [gl_cv_func_printf_sizes_c23=yes],
+        [gl_cv_func_printf_sizes_c23=no],
+        [
+         case "$host_os" in
+                               # Guess no on glibc systems.
+           *-gnu* | gnu*)      gl_cv_func_printf_sizes_c23="guessing no";;
+                               # Guess no on musl systems.
+           *-musl* | midipix*) gl_cv_func_printf_sizes_c23="guessing no";;
+                               # Guess no on Android.
+           linux*-android*)    gl_cv_func_printf_sizes_c23="guessing no";;
+                               # Guess no on native Windows.
+           mingw*)             gl_cv_func_printf_sizes_c23="guessing no";;
+                               # If we don't know, obey --enable-cross-guesses.
+           *)                  gl_cv_func_printf_sizes_c23="$gl_cross_guess_normal";;
+         esac
+        ])
+    ])
+])
+
 dnl Test whether the *printf family of functions supports 'long double'
 dnl arguments together with the 'L' size specifier. (ISO C99, POSIX:2001)
 dnl Result is gl_cv_func_printf_long_double.
@@ -603,6 +689,116 @@ int main ()
     ])
 ])
 
+dnl Test whether the *printf family of functions supports the 'b' conversion
+dnl specifier for binary output of integers.
+dnl (ISO C23)
+dnl Result is gl_cv_func_printf_directive_b.
+
+AC_DEFUN([gl_PRINTF_DIRECTIVE_B],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CACHE_CHECK([whether printf supports the 'b' directive],
+    [gl_cv_func_printf_directive_b],
+    [
+      AC_RUN_IFELSE(
+        [AC_LANG_SOURCE([[
+#include <stdio.h>
+#include <string.h>
+static char buf[100];
+int main ()
+{
+  int result = 0;
+  if (sprintf (buf, "%b %d", 12345, 33, 44, 55) < 0
+      || strcmp (buf, "11000000111001 33") != 0)
+    result |= 1;
+  return result;
+}]])],
+        [gl_cv_func_printf_directive_b=yes],
+        [gl_cv_func_printf_directive_b=no],
+        [
+         case "$host_os" in
+                               # Guess yes on glibc >= 2.35 systems.
+           *-gnu* | gnu*)
+             AC_EGREP_CPP([Lucky], [
+               #include <features.h>
+               #ifdef __GNU_LIBRARY__
+                #if (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 35) || (__GLIBC__ > 2)
+                 Lucky user
+                #endif
+               #endif
+               ],
+               [gl_cv_func_printf_directive_uppercase_b="guessing yes"],
+               [gl_cv_func_printf_directive_uppercase_b="guessing no"])
+             ;;
+                               # Guess no on musl systems.
+           *-musl* | midipix*) gl_cv_func_printf_directive_b="guessing no";;
+                               # Guess no on Android.
+           linux*-android*)    gl_cv_func_printf_directive_b="guessing no";;
+                               # Guess no on native Windows.
+           mingw*)             gl_cv_func_printf_directive_b="guessing no";;
+                               # If we don't know, obey --enable-cross-guesses.
+           *)                  gl_cv_func_printf_directive_b="$gl_cross_guess_normal";;
+         esac
+        ])
+    ])
+])
+
+dnl Test whether the *printf family of functions supports the 'B' conversion
+dnl specifier for binary output of integers.
+dnl (GNU, encouraged by ISO C23 § 7.23.6.1)
+dnl Result is gl_cv_func_printf_directive_uppercase_b.
+
+AC_DEFUN([gl_PRINTF_DIRECTIVE_UPPERCASE_B],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CACHE_CHECK([whether printf supports the 'B' directive],
+    [gl_cv_func_printf_directive_uppercase_b],
+    [
+      AC_RUN_IFELSE(
+        [AC_LANG_SOURCE([[
+#include <stdio.h>
+#include <string.h>
+static char buf[100];
+int main ()
+{
+  int result = 0;
+  if (sprintf (buf, "%#B %d", 12345, 33, 44, 55) < 0
+      || strcmp (buf, "0B11000000111001 33") != 0)
+    result |= 1;
+  return result;
+}]])],
+        [gl_cv_func_printf_directive_uppercase_b=yes],
+        [gl_cv_func_printf_directive_uppercase_b=no],
+        [
+         case "$host_os" in
+                               # Guess yes on glibc >= 2.35 systems.
+           *-gnu* | gnu*)
+             AC_EGREP_CPP([Lucky], [
+               #include <features.h>
+               #ifdef __GNU_LIBRARY__
+                #if (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 35) || (__GLIBC__ > 2)
+                 Lucky user
+                #endif
+               #endif
+               ],
+               [gl_cv_func_printf_directive_uppercase_b="guessing yes"],
+               [gl_cv_func_printf_directive_uppercase_b="guessing no"])
+             ;;
+                               # Guess no on musl systems.
+           *-musl* | midipix*) gl_cv_func_printf_directive_uppercase_b="guessing no";;
+                               # Guess no on Android.
+           linux*-android*)    gl_cv_func_printf_directive_uppercase_b="guessing no";;
+                               # Guess no on native Windows.
+           mingw*)             gl_cv_func_printf_directive_uppercase_b="guessing no";;
+                               # If we don't know, obey --enable-cross-guesses.
+           *)                  gl_cv_func_printf_directive_uppercase_b="$gl_cross_guess_normal";;
+         esac
+        ])
+    ])
+])
+
 dnl Test whether the *printf family of functions supports the %F format
 dnl directive. (ISO C99, POSIX:2001)
 dnl Result is gl_cv_func_printf_directive_f.
@@ -829,11 +1025,58 @@ changequote([,])dnl
     ])
 ])
 
+dnl Test whether the *printf family of functions supports the %lc format
+dnl directive and in particular, when the argument is a null wide character,
+dnl whether the functions don't produce a NUL byte.
+dnl Result is gl_cv_func_printf_directive_lc.
+
+AC_DEFUN([gl_PRINTF_DIRECTIVE_LC],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CACHE_CHECK([whether printf supports the 'lc' directive correctly],
+    [gl_cv_func_printf_directive_lc],
+    [
+      AC_RUN_IFELSE(
+        [AC_LANG_SOURCE([[
+#include <stdio.h>
+#include <wchar.h>
+#include <string.h>
+int main ()
+{
+  int result = 0;
+  char buf[100];
+  /* This test fails on glibc 2.35, FreeBSD 13.1, NetBSD 9.0, OpenBSD 7.2,
+     macOS 12.5, AIX 7.2, Solaris 11.4.
+     glibc 2.35 bug: <https://sourceware.org/bugzilla/show_bug.cgi?id=30257>  */
+  {
+    buf[0] = '\0';
+    if (sprintf (buf, "%lc%lc%lc", (wint_t) 'a', (wint_t) 0, (wint_t) 'z') < 0
+        || strcmp (buf, "az") != 0)
+      result |= 1;
+  }
+  return result;
+}]])],
+        [gl_cv_func_printf_directive_lc=yes],
+        [gl_cv_func_printf_directive_lc=no],
+        [
+changequote(,)dnl
+         case "$host_os" in
+                               # Guess yes on musl libc.
+           *-musl* | midipix*) gl_cv_func_printf_directive_lc="guessing yes";;
+                               # Guess no otherwise.
+           *)                  gl_cv_func_printf_directive_lc="guessing no";;
+         esac
+changequote([,])dnl
+        ])
+    ])
+])
+
 dnl Test whether the *printf family of functions supports POSIX/XSI format
 dnl strings with positions. (POSIX:2001)
 dnl Result is gl_cv_func_printf_positions.
 
-AC_DEFUN([gl_PRINTF_POSITIONS],
+AC_DEFUN_ONCE([gl_PRINTF_POSITIONS],
 [
   AC_REQUIRE([AC_PROG_CC])
   AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
@@ -1641,88 +1884,227 @@ changequote([,])dnl
     ])
 ])
 
+dnl Test whether the swprintf function works correctly when it produces output
+dnl that contains null wide characters.
+dnl Result is gl_cv_func_swprintf_works.
+
+AC_DEFUN([gl_SWPRINTF_WORKS],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CHECK_FUNCS_ONCE([swprintf])
+  AC_CACHE_CHECK([whether swprintf works],
+    [gl_cv_func_swprintf_works],
+    [
+      AC_RUN_IFELSE(
+        [AC_LANG_SOURCE([[
+#ifndef __USE_MINGW_ANSI_STDIO
+# define __USE_MINGW_ANSI_STDIO 1
+#endif
+#include <stdio.h>
+#include <wchar.h>
+int main()
+{
+  int result = 0;
+  { /* This test fails on musl, FreeBSD, NetBSD, OpenBSD, macOS, AIX.  */
+    wchar_t buf[5] = { 0xBEEF, 0xBEEF, 0xBEEF, 0xBEEF, 0xBEEF };
+    int ret = swprintf (buf, 4, L"%cz", '\0');
+    /* Expected result:
+         ret = 2, buf[0] = 0x0, buf[1] = 0x7a, buf[2] = 0x0, buf[3] = 0xbeef
+       musl libc 1.2.3:
+         ret = 2, buf[0] = 0x0, buf[1] = 0x0, buf[2] = 0x0, buf[3] = 0x0
+         Reported at <https://www.openwall.com/lists/musl/2023/03/22/9>.
+       FreeBSD 13.1, NetBSD 9.0, OpenBSD 7.2, macOS 12.5, AIX 7.2:
+         ret = 2, buf[0] = 0x0, buf[1] = 0xbeef, buf[2] = 0xbeef, buf[3] = 0xbeef
+     */
+    if (ret < 0 || buf[1] != 'z')
+      result |= 1;
+  }
+  { /* This test fails on mingw.  */
+    wchar_t buf[2];
+    int ret = swprintf (buf, 2, L"%lc", (wint_t)0);
+    /* Expected: ret = 1
+       mingw:    ret = 0
+     */
+    if (ret != 1)
+      result |= 2;
+  }
+  return result;
+}]])],
+        [gl_cv_func_swprintf_works=yes],
+        [gl_cv_func_swprintf_works=no],
+        [case "$host_os" in
+                               # Guess yes on glibc systems.
+           *-gnu* | gnu*)      gl_cv_func_swprintf_works="guessing yes";;
+                               # Guess no on musl systems.
+           *-musl* | midipix*) gl_cv_func_swprintf_works="guessing yes";;
+                               # Guess no on FreeBSD, NetBSD, OpenBSD, macOS, AIX.
+           freebsd* | midnightbsd* | netbsd* | openbsd* | darwin* | aix*)
+                               gl_cv_func_swprintf_works="guessing no";;
+                               # Guess no on native Windows.
+           mingw* | pw*)       gl_cv_func_swprintf_works="guessing no";;
+                               # If we don't know, obey --enable-cross-guesses.
+           *)                  gl_cv_func_swprintf_works="$gl_cross_guess_normal";;
+         esac
+        ])
+    ])
+])
+
+dnl Test whether the *wprintf family of functions supports the 'a' and 'A'
+dnl conversion specifier for hexadecimal output of 'long double' numbers.
+dnl (ISO C99, POSIX:2001)
+dnl Result is gl_cv_func_swprintf_directive_la.
+
+AC_DEFUN([gl_SWPRINTF_DIRECTIVE_LA],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CACHE_CHECK([whether swprintf supports the 'La' and 'LA' directives],
+    [gl_cv_func_swprintf_directive_la],
+    [
+      AC_RUN_IFELSE(
+        [AC_LANG_SOURCE([[
+#include <stdio.h>
+#include <wchar.h>
+static wchar_t buf[100];
+int main ()
+{
+  int result = 0;
+  /* This catches a glibc 2.15 and Haiku 2022 bug.  */
+  if (swprintf (buf, sizeof (buf) / sizeof (wchar_t),
+                L"%La %d", 3.1416015625L, 33, 44, 55) < 0
+      || (wcscmp (buf, L"0x1.922p+1 33") != 0
+          && wcscmp (buf, L"0x3.244p+0 33") != 0
+          && wcscmp (buf, L"0x6.488p-1 33") != 0
+          && wcscmp (buf, L"0xc.91p-2 33") != 0))
+    result |= 1;
+  return result;
+}]])],
+        [gl_cv_func_swprintf_directive_la=yes],
+        [gl_cv_func_swprintf_directive_la=no],
+        [case "$host_os" in
+                                 # Guess yes on glibc >= 2.17 systems.
+           *-gnu* | gnu*)
+             AC_EGREP_CPP([Unlucky], [
+               #include <features.h>
+               #ifdef __GNU_LIBRARY__
+                #if ((__GLIBC__ == 2 && __GLIBC_MINOR__ >= 16) || (__GLIBC__ > 2)) && !defined __UCLIBC__
+                 Unlucky
+                #endif
+               #endif
+               ],
+               [gl_cv_func_swprintf_directive_la="guessing yes"],
+               [gl_cv_func_swprintf_directive_la="guessing no"])
+             ;;
+                                 # Guess yes on musl systems.
+           *-musl* | midipix*)   gl_cv_func_swprintf_directive_la="guessing yes";;
+                                 # Guess yes on Android.
+           linux*-android*)      gl_cv_func_swprintf_directive_la="guessing no";;
+                                 # Guess yes on native Windows.
+           mingw*)               gl_cv_func_swprintf_directive_la="guessing no";;
+                                 # If we don't know, obey --enable-cross-guesses.
+           *)                    gl_cv_func_swprintf_directive_la="$gl_cross_guess_normal";;
+         esac
+        ])
+    ])
+])
+
 dnl The results of these tests on various platforms are:
 dnl
 dnl 1 = gl_PRINTF_SIZES_C99
-dnl 2 = gl_PRINTF_LONG_DOUBLE
-dnl 3 = gl_PRINTF_INFINITE
-dnl 4 = gl_PRINTF_INFINITE_LONG_DOUBLE
-dnl 5 = gl_PRINTF_DIRECTIVE_A
-dnl 6 = gl_PRINTF_DIRECTIVE_F
-dnl 7 = gl_PRINTF_DIRECTIVE_N
-dnl 8 = gl_PRINTF_DIRECTIVE_LS
-dnl 9 = gl_PRINTF_POSITIONS
-dnl 10 = gl_PRINTF_FLAG_GROUPING
-dnl 11 = gl_PRINTF_FLAG_LEFTADJUST
-dnl 12 = gl_PRINTF_FLAG_ZERO
-dnl 13 = gl_PRINTF_PRECISION
-dnl 14 = gl_PRINTF_ENOMEM
-dnl 15 = gl_SNPRINTF_PRESENCE
-dnl 16 = gl_SNPRINTF_TRUNCATION_C99
-dnl 17 = gl_SNPRINTF_RETVAL_C99
-dnl 18 = gl_SNPRINTF_DIRECTIVE_N
-dnl 19 = gl_SNPRINTF_SIZE1
-dnl 20 = gl_VSNPRINTF_ZEROSIZE_C99
+dnl 2 = gl_PRINTF_SIZES_C23
+dnl 3 = gl_PRINTF_LONG_DOUBLE
+dnl 4 = gl_PRINTF_INFINITE
+dnl 5 = gl_PRINTF_INFINITE_LONG_DOUBLE
+dnl 6 = gl_PRINTF_DIRECTIVE_A
+dnl 7 = gl_PRINTF_DIRECTIVE_B
+dnl 8 = gl_PRINTF_DIRECTIVE_UPPERCASE_B
+dnl 9 = gl_PRINTF_DIRECTIVE_F
+dnl 10 = gl_PRINTF_DIRECTIVE_N
+dnl 11 = gl_PRINTF_DIRECTIVE_LS
+dnl 12 = gl_PRINTF_DIRECTIVE_LC
+dnl 13 = gl_PRINTF_POSITIONS
+dnl 14 = gl_PRINTF_FLAG_GROUPING
+dnl 15 = gl_PRINTF_FLAG_LEFTADJUST
+dnl 16 = gl_PRINTF_FLAG_ZERO
+dnl 17 = gl_PRINTF_PRECISION
+dnl 18 = gl_PRINTF_ENOMEM
+dnl 19 = gl_SNPRINTF_PRESENCE
+dnl 20 = gl_SNPRINTF_TRUNCATION_C99
+dnl 21 = gl_SNPRINTF_RETVAL_C99
+dnl 22 = gl_SNPRINTF_DIRECTIVE_N
+dnl 23 = gl_SNPRINTF_SIZE1
+dnl 24 = gl_VSNPRINTF_ZEROSIZE_C99
+dnl 25 = gl_SWPRINTF_WORKS
+dnl 26 = gl_SWPRINTF_DIRECTIVE_LA
 dnl
 dnl 1 = checking whether printf supports size specifiers as in C99...
-dnl 2 = checking whether printf supports 'long double' arguments...
-dnl 3 = checking whether printf supports infinite 'double' arguments...
-dnl 4 = checking whether printf supports infinite 'long double' arguments...
-dnl 5 = checking whether printf supports the 'a' and 'A' directives...
-dnl 6 = checking whether printf supports the 'F' directive...
-dnl 7 = checking whether printf supports the 'n' directive...
-dnl 8 = checking whether printf supports the 'ls' directive...
-dnl 9 = checking whether printf supports POSIX/XSI format strings with positions...
-dnl 10 = checking whether printf supports the grouping flag...
-dnl 11 = checking whether printf supports the left-adjust flag correctly...
-dnl 12 = checking whether printf supports the zero flag correctly...
-dnl 13 = checking whether printf supports large precisions...
-dnl 14 = checking whether printf survives out-of-memory conditions...
-dnl 15 = checking for snprintf...
-dnl 16 = checking whether snprintf truncates the result as in C99...
-dnl 17 = checking whether snprintf returns a byte count as in C99...
-dnl 18 = checking whether snprintf fully supports the 'n' directive...
-dnl 19 = checking whether snprintf respects a size of 1...
-dnl 20 = checking whether vsnprintf respects a zero size as in C99...
+dnl 2 = checking whether printf supports size specifiers as in C23...
+dnl 3 = checking whether printf supports 'long double' arguments...
+dnl 4 = checking whether printf supports infinite 'double' arguments...
+dnl 5 = checking whether printf supports infinite 'long double' arguments...
+dnl 6 = checking whether printf supports the 'a' and 'A' directives...
+dnl 7 = checking whether printf supports the 'b' directive...
+dnl 8 = checking whether printf supports the 'B' directive...
+dnl 9 = checking whether printf supports the 'F' directive...
+dnl 10 = checking whether printf supports the 'n' directive...
+dnl 11 = checking whether printf supports the 'ls' directive...
+dnl 12 = checking whether printf supports the 'lc' directive correctly...
+dnl 13 = checking whether printf supports POSIX/XSI format strings with positions...
+dnl 14 = checking whether printf supports the grouping flag...
+dnl 15 = checking whether printf supports the left-adjust flag correctly...
+dnl 16 = checking whether printf supports the zero flag correctly...
+dnl 17 = checking whether printf supports large precisions...
+dnl 18 = checking whether printf survives out-of-memory conditions...
+dnl 19 = checking for snprintf...
+dnl 20 = checking whether snprintf truncates the result as in C99...
+dnl 21 = checking whether snprintf returns a byte count as in C99...
+dnl 22 = checking whether snprintf fully supports the 'n' directive...
+dnl 23 = checking whether snprintf respects a size of 1...
+dnl 24 = checking whether vsnprintf respects a zero size as in C99...
+dnl 25 = checking whether swprintf works...
+dnl 26 = checking whether swprintf supports the 'La' and 'LA' directives...
 dnl
 dnl . = yes, # = no.
 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                .  .  .  #  #  .  .  .  .  .  .  #  .  .  .  .  .  .  .  .
-dnl   Mac OS X 10.3.9                .  .  .  .  #  .  .  .  .  .  .  #  .  #  .  .  .  .  .  .
-dnl   OpenBSD 6.0, 6.7               .  .  .  .  #  .  .  .  .  .  .  .  .  #  .  .  .  .  .  .
-dnl   OpenBSD 3.9, 4.0               .  .  #  #  #  #  .  #  .  #  .  #  .  #  .  .  .  .  .  .
-dnl   Cygwin 1.7.0 (2009)            .  .  .  #  .  .  .  ?  .  .  .  .  .  ?  .  .  .  .  .  .
-dnl   Cygwin 1.5.25 (2008)           .  .  .  #  #  .  .  #  .  .  .  .  .  #  .  .  .  .  .  .
-dnl   Cygwin 1.5.19 (2006)           #  .  .  #  #  #  .  #  .  #  .  #  #  #  .  .  .  .  .  .
-dnl   Solaris 11.4                   .  .  #  #  #  .  .  #  .  .  .  #  .  .  .  .  .  .  .  .
-dnl   Solaris 11.3                   .  .  .  .  #  .  .  #  .  .  .  .  .  .  .  .  .  .  .  .
-dnl   Solaris 11.0                   .  .  #  #  #  .  .  #  .  .  .  #  .  .  .  .  .  .  .  .
-dnl   Solaris 10                     .  .  #  #  #  .  .  #  .  .  .  #  #  .  .  .  .  .  .  .
-dnl   Solaris 2.6 ... 9              #  .  #  #  #  #  .  #  .  .  .  #  #  .  .  .  #  .  .  .
-dnl   Solaris 2.5.1                  #  .  #  #  #  #  .  #  .  .  .  #  .  .  #  #  #  #  #  #
-dnl   AIX 7.1                        .  .  #  #  #  .  .  .  .  .  .  #  #  .  .  .  .  .  .  .
-dnl   AIX 5.2                        .  .  #  #  #  .  .  .  .  .  .  #  .  .  .  .  .  .  .  .
-dnl   AIX 4.3.2, 5.1                 #  .  #  #  #  #  .  .  .  .  .  #  .  .  .  .  #  .  .  .
-dnl   HP-UX 11.31                    .  .  .  .  #  .  .  .  .  .  .  #  .  .  .  .  #  #  .  .
-dnl   HP-UX 11.{00,11,23}            #  .  .  .  #  #  .  .  .  .  .  #  .  .  .  .  #  #  .  #
-dnl   HP-UX 10.20                    #  .  #  .  #  #  .  ?  .  .  #  #  .  .  .  .  #  #  ?  #
-dnl   IRIX 6.5                       #  .  #  #  #  #  .  #  .  .  .  #  .  .  .  .  #  .  .  .
-dnl   OSF/1 5.1                      #  .  #  #  #  #  .  .  .  .  .  #  .  .  .  .  #  .  .  #
-dnl   OSF/1 4.0d                     #  .  #  #  #  #  .  .  .  .  .  #  .  .  #  #  #  #  #  #
-dnl   NetBSD 9.0                     .  .  .  .  #  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
-dnl   NetBSD 5.0                     .  .  .  #  #  .  .  .  .  .  .  #  .  #  .  .  .  .  .  .
-dnl   NetBSD 4.0                     .  ?  ?  ?  ?  ?  .  ?  .  ?  ?  ?  ?  ?  .  .  .  ?  ?  ?
-dnl   NetBSD 3.0                     .  .  .  .  #  #  .  ?  #  #  ?  #  .  #  .  .  .  .  .  .
-dnl   Haiku                          .  .  .  #  #  #  .  #  .  .  .  .  .  ?  .  .  ?  .  .  .
-dnl   BeOS                           #  #  .  #  #  #  .  ?  #  .  ?  .  #  ?  .  .  ?  .  .  .
-dnl   Android 4.3                    .  .  #  #  #  #  #  #  .  #  .  #  .  #  .  .  .  #  .  .
-dnl   old mingw / msvcrt             #  #  #  #  #  #  .  .  #  #  .  #  #  ?  .  #  #  #  .  .
-dnl   MSVC 9                         #  #  #  #  #  #  #  .  #  #  .  #  #  ?  #  #  #  #  .  .
-dnl   mingw 2009-2011                .  #  .  #  .  .  .  .  #  #  .  .  .  ?  .  .  .  .  .  .
-dnl   mingw-w64 2011                 #  #  #  #  #  #  .  .  #  #  .  #  #  ?  .  #  #  #  .  .
+dnl                                  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
+dnl   musl libc 1.2.3                .  #  .  .  .  .  #  #  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  #  .
+dnl   glibc 2.35                     .  #  .  .  .  .  .  .  .  .  .  #  .  .  .  .  .  .  .  .  .  .  .  .  .  .
+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                .  #  .  .  #  #  #  #  .  .  .  #  .  .  .  #  .  .  .  .  .  .  .  .  #  ?
+dnl   Mac OS X 10.3.9                .  #  .  .  .  #  #  #  .  .  .  #  .  .  .  #  .  #  .  .  .  .  .  .  #  ?
+dnl   OpenBSD 6.0, 6.7               .  #  .  .  .  #  #  #  .  .  .  #  .  .  .  .  .  #  .  .  .  .  .  .  #  .
+dnl   OpenBSD 3.9, 4.0               .  #  .  #  #  #  #  #  #  .  #  #  .  #  .  #  .  #  .  .  .  .  .  .  #  ?
+dnl   Cygwin 1.7.0 (2009)            .  #  .  .  #  .  #  #  .  .  ?  ?  .  .  .  .  .  ?  .  .  .  .  .  .  ?  ?
+dnl   Cygwin 1.5.25 (2008)           .  #  .  .  #  #  #  #  .  .  #  ?  .  .  .  .  .  #  .  .  .  .  .  .  ?  ?
+dnl   Cygwin 1.5.19 (2006)           #  #  .  .  #  #  #  #  #  .  #  ?  .  #  .  #  #  #  .  .  .  .  .  .  ?  ?
+dnl   Solaris 11.4                   .  #  .  #  #  #  #  #  .  .  #  #  .  .  .  #  .  .  .  .  .  .  .  .  .  ?
+dnl   Solaris 11.3                   .  #  .  .  .  #  #  #  .  .  #  #  .  .  .  .  .  .  .  .  .  .  .  .  .  ?
+dnl   Solaris 11.0                   .  #  .  #  #  #  #  #  .  .  #  #  .  .  .  #  .  .  .  .  .  .  .  .  ?  ?
+dnl   Solaris 10                     .  #  .  #  #  #  #  #  .  .  #  #  .  .  .  #  #  .  .  .  .  .  .  .  ?  ?
+dnl   Solaris 2.6 ... 9              #  #  .  #  #  #  #  #  #  .  #  #  .  .  .  #  #  .  .  .  #  .  .  .  ?  ?
+dnl   Solaris 2.5.1                  #  #  .  #  #  #  #  #  #  .  #  #  .  .  .  #  .  .  #  #  #  #  #  #  ?  ?
+dnl   AIX 7.1                        .  #  .  #  #  #  #  #  .  .  .  #  .  .  .  #  #  .  .  .  .  .  .  .  #  .
+dnl   AIX 5.2                        .  #  .  #  #  #  #  #  .  .  .  #  .  .  .  #  .  .  .  .  .  .  .  .  #  ?
+dnl   AIX 4.3.2, 5.1                 #  #  .  #  #  #  #  #  #  .  .  #  .  .  .  #  .  .  .  .  #  .  .  .  #  ?
+dnl   HP-UX 11.31                    .  #  .  .  .  #  #  #  .  .  .  ?  .  .  .  #  .  .  .  .  #  #  .  .  ?  ?
+dnl   HP-UX 11.{00,11,23}            #  #  .  .  .  #  #  #  #  .  .  ?  .  .  .  #  .  .  .  .  #  #  .  #  ?  ?
+dnl   HP-UX 10.20                    #  #  .  #  .  #  #  #  #  .  ?  ?  .  .  #  #  .  .  .  .  #  #  ?  #  ?  ?
+dnl   IRIX 6.5                       #  #  .  #  #  #  #  #  #  .  #  #  .  .  .  #  .  .  .  .  #  .  .  .  #  ?
+dnl   OSF/1 5.1                      #  #  .  #  #  #  #  #  #  .  .  ?  .  .  .  #  .  .  .  .  #  .  .  #  ?  ?
+dnl   OSF/1 4.0d                     #  #  .  #  #  #  #  #  #  .  .  ?  .  .  .  #  .  .  #  #  #  #  #  #  ?  ?
+dnl   NetBSD 9.0                     .  #  .  .  .  #  #  #  .  .  .  #  .  .  .  .  .  .  .  .  .  .  .  .  #  .
+dnl   NetBSD 5.0                     .  #  .  .  #  #  #  #  .  .  .  #  .  .  .  #  .  #  .  .  .  .  .  .  #  ?
+dnl   NetBSD 4.0                     .  #  ?  ?  ?  ?  #  #  ?  .  ?  #  .  ?  ?  ?  ?  ?  .  .  .  ?  ?  ?  #  ?
+dnl   NetBSD 3.0                     .  #  .  .  .  #  #  #  #  .  ?  #  #  #  ?  #  .  #  .  .  .  .  .  .  #  ?
+dnl   Haiku                          .  #  .  .  #  #  #  #  #  .  #  ?  .  .  .  .  .  ?  .  .  ?  .  .  .  .  #
+dnl   BeOS                           #  #  #  .  #  #  #  #  #  .  ?  ?  #  .  ?  .  #  ?  .  .  ?  .  .  .  ?  ?
+dnl   Android 4.3                    .  #  .  #  #  #  #  #  #  #  #  ?  .  #  .  #  .  #  .  .  .  #  .  .  ?  ?
+dnl   old mingw / msvcrt             #  #  #  #  #  #  #  #  #  .  .  ?  #  #  .  #  #  ?  .  #  #  #  .  .  #  ?
+dnl   MSVC 9                         #  #  #  #  #  #  #  #  #  #  .  ?  #  #  .  #  #  ?  #  #  #  #  .  .  #  ?
+dnl   mingw 2009-2011                .  #  #  .  #  .  #  #  .  .  .  ?  #  #  .  .  .  ?  .  .  .  .  .  .  #  ?
+dnl   mingw-w64 2011                 #  #  #  #  #  #  #  #  #  .  .  ?  #  #  .  #  #  ?  .  #  #  #  .  .  #  ?
diff --git a/m4/vasnprintf.m4 b/m4/vasnprintf.m4
index fda90c402b4..639b29a1f39 100644
--- a/m4/vasnprintf.m4
+++ b/m4/vasnprintf.m4
@@ -1,4 +1,4 @@
-# vasnprintf.m4 serial 39
+# vasnprintf.m4 serial 49
 dnl Copyright (C) 2002-2004, 2006-2023 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -29,6 +29,15 @@ AC_DEFUN([gl_REPLACE_VASNPRINTF],
   gl_PREREQ_ASNPRINTF
 ])
 
+AC_DEFUN([gl_FUNC_VASNWPRINTF],
+[
+  AC_LIBOBJ([printf-args])
+  gl_PREREQ_PRINTF_ARGS
+  gl_PREREQ_PRINTF_PARSE
+  gl_PREREQ_VASNWPRINTF
+  gl_PREREQ_ASNPRINTF
+])
+
 # Prerequisites of lib/printf-args.h, lib/printf-args.c.
 AC_DEFUN([gl_PREREQ_PRINTF_ARGS],
 [
@@ -37,6 +46,7 @@ AC_DEFUN([gl_PREREQ_PRINTF_ARGS],
 ])
 
 # Prerequisites of lib/printf-parse.h, lib/printf-parse.c.
+# Prerequisites of lib/wprintf-parse.h, lib/wprintf-parse.c.
 AC_DEFUN([gl_PREREQ_PRINTF_PARSE],
 [
   AC_REQUIRE([gl_FEATURES_H])
@@ -50,19 +60,13 @@ AC_DEFUN([gl_PREREQ_PRINTF_PARSE],
   AC_REQUIRE([gt_AC_TYPE_INTMAX_T])
 ])
 
-# Prerequisites of lib/vasnprintf.c.
+# Prerequisites of lib/vasnprintf.c if !WIDE_CHAR_VERSION.
 AC_DEFUN_ONCE([gl_PREREQ_VASNPRINTF],
 [
-  AC_REQUIRE([AC_FUNC_ALLOCA])
-  AC_REQUIRE([gt_TYPE_WCHAR_T])
-  AC_REQUIRE([gt_TYPE_WINT_T])
-  AC_CHECK_FUNCS([snprintf strnlen wcslen wcsnlen mbrtowc wcrtomb])
+  AC_CHECK_FUNCS([snprintf strnlen wcrtomb])
   dnl Use the _snprintf function only if it is declared (because on NetBSD it
   dnl is defined as a weak alias of snprintf; we prefer to use the latter).
   AC_CHECK_DECLS([_snprintf], , , [[#include <stdio.h>]])
-  dnl Knowing DBL_EXPBIT0_WORD and DBL_EXPBIT0_BIT enables an optimization
-  dnl in the code for NEED_PRINTF_LONG_DOUBLE || NEED_PRINTF_DOUBLE.
-  AC_REQUIRE([gl_DOUBLE_EXPONENT_LOCATION])
   dnl We can avoid a lot of code by assuming that snprintf's return value
   dnl conforms to ISO C99. So check that.
   AC_REQUIRE([gl_SNPRINTF_RETVAL_C99])
@@ -84,6 +88,55 @@ AC_DEFUN_ONCE([gl_PREREQ_VASNPRINTF],
          terminated.])
       ;;
   esac
+  gl_PREREQ_VASNXPRINTF
+])
+
+# Prerequisites of lib/vasnwprintf.c.
+AC_DEFUN_ONCE([gl_PREREQ_VASNWPRINTF],
+[
+  AC_CHECK_FUNCS_ONCE([swprintf wcsnlen mbrtowc])
+  AC_CHECK_DECLS([_snwprintf], , , [[#include <stdio.h>]])
+  AC_CHECK_DECLS([wcsnlen], , , [[#include <wchar.h>]])
+  gl_SWPRINTF_WORKS
+  case "$gl_cv_func_swprintf_works" in
+    *yes)
+      AC_DEFINE([HAVE_WORKING_SWPRINTF], [1],
+        [Define if the swprintf function works correctly when it produces output
+         that contains null wide characters.])
+      ;;
+  esac
+  gl_MBRTOWC_C_LOCALE
+  case "$gl_cv_func_mbrtowc_C_locale_sans_EILSEQ" in
+    *yes) ;;
+    *)
+      AC_DEFINE([NEED_WPRINTF_DIRECTIVE_C], [1],
+        [Define if the vasnwprintf implementation needs special code for
+         the 'c' directive.])
+      ;;
+  esac
+  gl_SWPRINTF_DIRECTIVE_LA
+  case "$gl_cv_func_swprintf_directive_la" in
+    *yes) ;;
+    *)
+      AC_DEFINE([NEED_WPRINTF_DIRECTIVE_LA], [1],
+        [Define if the vasnwprintf implementation needs special code for
+         the 'a' directive with 'long double' arguments.])
+      ;;
+  esac
+  gl_MUSL_LIBC
+  gl_PREREQ_VASNXPRINTF
+])
+
+# Common prerequisites of lib/vasnprintf.c and lib/vasnwprintf.c.
+AC_DEFUN_ONCE([gl_PREREQ_VASNXPRINTF],
+[
+  AC_REQUIRE([AC_FUNC_ALLOCA])
+  AC_REQUIRE([gt_TYPE_WCHAR_T])
+  AC_REQUIRE([gt_TYPE_WINT_T])
+  AC_CHECK_FUNCS([wcslen])
+  dnl Knowing DBL_EXPBIT0_WORD and DBL_EXPBIT0_BIT enables an optimization
+  dnl in the code for NEED_PRINTF_LONG_DOUBLE || NEED_PRINTF_DOUBLE.
+  AC_REQUIRE([gl_DOUBLE_EXPONENT_LOCATION])
 ])
 
 # Extra prerequisites of lib/vasnprintf.c for supporting 'long double'
@@ -157,6 +210,21 @@ AC_DEFUN([gl_PREREQ_VASNPRINTF_DIRECTIVE_A],
   esac
 ])
 
+# Extra prerequisites of lib/vasnprintf.c for supporting the 'b' directive.
+AC_DEFUN([gl_PREREQ_VASNPRINTF_DIRECTIVE_B],
+[
+  AC_REQUIRE([gl_PRINTF_DIRECTIVE_B])
+  case "$gl_cv_func_printf_directive_b" in
+    *yes)
+      ;;
+    *)
+      AC_DEFINE([NEED_PRINTF_DIRECTIVE_B], [1],
+        [Define if the vasnprintf implementation needs special code for
+         the 'b' directive.])
+      ;;
+  esac
+])
+
 # Extra prerequisites of lib/vasnprintf.c for supporting the 'F' directive.
 AC_DEFUN([gl_PREREQ_VASNPRINTF_DIRECTIVE_F],
 [
@@ -187,6 +255,21 @@ AC_DEFUN([gl_PREREQ_VASNPRINTF_DIRECTIVE_LS],
   esac
 ])
 
+# Extra prerequisites of lib/vasnprintf.c for supporting the 'lc' directive.
+AC_DEFUN([gl_PREREQ_VASNPRINTF_DIRECTIVE_LC],
+[
+  AC_REQUIRE([gl_PRINTF_DIRECTIVE_LC])
+  case "$gl_cv_func_printf_directive_lc" in
+    *yes)
+      ;;
+    *)
+      AC_DEFINE([NEED_PRINTF_DIRECTIVE_LC], [1],
+        [Define if the vasnprintf implementation needs special code for
+         the 'lc' directive.])
+      ;;
+  esac
+])
+
 # Extra prerequisites of lib/vasnprintf.c for supporting the ' flag.
 AC_DEFUN([gl_PREREQ_VASNPRINTF_FLAG_GROUPING],
 [
@@ -276,15 +359,17 @@ AC_DEFUN([gl_PREREQ_VASNPRINTF_ENOMEM],
 ])
 
 # Prerequisites of lib/vasnprintf.c including all extras for POSIX compliance.
-AC_DEFUN([gl_PREREQ_VASNPRINTF_WITH_EXTRAS],
+AC_DEFUN([gl_PREREQ_VASNPRINTF_WITH_POSIX_EXTRAS],
 [
   AC_REQUIRE([gl_PREREQ_VASNPRINTF])
   gl_PREREQ_VASNPRINTF_LONG_DOUBLE
   gl_PREREQ_VASNPRINTF_INFINITE_DOUBLE
   gl_PREREQ_VASNPRINTF_INFINITE_LONG_DOUBLE
   gl_PREREQ_VASNPRINTF_DIRECTIVE_A
+  gl_PREREQ_VASNPRINTF_DIRECTIVE_B
   gl_PREREQ_VASNPRINTF_DIRECTIVE_F
   gl_PREREQ_VASNPRINTF_DIRECTIVE_LS
+  gl_PREREQ_VASNPRINTF_DIRECTIVE_LC
   gl_PREREQ_VASNPRINTF_FLAG_GROUPING
   gl_PREREQ_VASNPRINTF_FLAG_LEFTADJUST
   gl_PREREQ_VASNPRINTF_FLAG_ZERO
@@ -292,7 +377,34 @@ AC_DEFUN([gl_PREREQ_VASNPRINTF_WITH_EXTRAS],
   gl_PREREQ_VASNPRINTF_ENOMEM
 ])
 
+# Extra prerequisites of lib/vasnprintf.c for supporting the 'B' directive.
+AC_DEFUN([gl_PREREQ_VASNPRINTF_DIRECTIVE_UPPERCASE_B],
+[
+  AC_REQUIRE([gl_PRINTF_DIRECTIVE_UPPERCASE_B])
+  case "$gl_cv_func_printf_directive_uppercase_b" in
+    *yes)
+      ;;
+    *)
+      AC_DEFINE([NEED_PRINTF_DIRECTIVE_UPPERCASE_B], [1],
+        [Define if the vasnprintf implementation needs special code for
+         the 'B' directive.])
+      ;;
+  esac
+])
+
+# Prerequisites of lib/vasnprintf.c including all extras for POSIX compliance
+# and GNU compatibility.
+AC_DEFUN([gl_PREREQ_VASNPRINTF_WITH_GNU_EXTRAS],
+[
+  gl_PREREQ_VASNPRINTF_WITH_POSIX_EXTRAS
+  AC_DEFINE([SUPPORT_GNU_PRINTF_DIRECTIVES], [1],
+    [Define if the vasnprintf implementation should support GNU compatible
+     printf directives.])
+  gl_PREREQ_VASNPRINTF_DIRECTIVE_UPPERCASE_B
+])
+
 # Prerequisites of lib/asnprintf.c.
+# Prerequisites of lib/asnwprintf.c.
 AC_DEFUN([gl_PREREQ_ASNPRINTF],
 [
 ])
diff --git a/m4/vasprintf-posix.m4 b/m4/vasprintf-posix.m4
index 7c198a64108..3c7a6540bd1 100644
--- a/m4/vasprintf-posix.m4
+++ b/m4/vasprintf-posix.m4
@@ -1,4 +1,4 @@
-# vasprintf-posix.m4 serial 13
+# vasprintf-posix.m4 serial 17
 dnl Copyright (C) 2007-2023 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -6,14 +6,29 @@ dnl with or without modifications, as long as this notice is preserved.
 
 AC_DEFUN([gl_FUNC_VASPRINTF_POSIX],
 [
+  AC_REQUIRE([gl_FUNC_VASPRINTF_IS_POSIX])
+  if test $gl_cv_func_vasprintf_posix = no; then
+    gl_PREREQ_VASNPRINTF_WITH_POSIX_EXTRAS
+    gl_REPLACE_VASNPRINTF
+    gl_REPLACE_VASPRINTF
+  fi
+])
+
+dnl Test whether vasprintf exists and is POSIX compliant.
+dnl Result is gl_cv_func_vasprintf_posix.
+AC_DEFUN([gl_FUNC_VASPRINTF_IS_POSIX],
+[
   AC_REQUIRE([gl_PRINTF_SIZES_C99])
+  AC_REQUIRE([gl_PRINTF_SIZES_C23])
   AC_REQUIRE([gl_PRINTF_LONG_DOUBLE])
   AC_REQUIRE([gl_PRINTF_INFINITE])
   AC_REQUIRE([gl_PRINTF_INFINITE_LONG_DOUBLE])
   AC_REQUIRE([gl_PRINTF_DIRECTIVE_A])
+  AC_REQUIRE([gl_PRINTF_DIRECTIVE_B])
   AC_REQUIRE([gl_PRINTF_DIRECTIVE_F])
   AC_REQUIRE([gl_PRINTF_DIRECTIVE_N])
   AC_REQUIRE([gl_PRINTF_DIRECTIVE_LS])
+  AC_REQUIRE([gl_PRINTF_DIRECTIVE_LC])
   AC_REQUIRE([gl_PRINTF_POSITIONS])
   AC_REQUIRE([gl_PRINTF_FLAG_GROUPING])
   AC_REQUIRE([gl_PRINTF_FLAG_LEFTADJUST])
@@ -24,37 +39,49 @@ AC_DEFUN([gl_FUNC_VASPRINTF_POSIX],
   AC_CHECK_FUNCS([vasprintf])
   case "$gl_cv_func_printf_sizes_c99" in
     *yes)
-      case "$gl_cv_func_printf_long_double" in
+      case "$gl_cv_func_printf_sizes_c23" in
         *yes)
-          case "$gl_cv_func_printf_infinite" in
+          case "$gl_cv_func_printf_long_double" in
             *yes)
-              case "$gl_cv_func_printf_infinite_long_double" in
+              case "$gl_cv_func_printf_infinite" in
                 *yes)
-                  case "$gl_cv_func_printf_directive_a" in
+                  case "$gl_cv_func_printf_infinite_long_double" in
                     *yes)
-                      case "$gl_cv_func_printf_directive_f" in
+                      case "$gl_cv_func_printf_directive_a" in
                         *yes)
-                          case "$gl_cv_func_printf_directive_n" in
+                          case "$gl_cv_func_printf_directive_b" in
                             *yes)
-                              case "$gl_cv_func_printf_directive_ls" in
+                              case "$gl_cv_func_printf_directive_f" in
                                 *yes)
-                                  case "$gl_cv_func_printf_positions" in
+                                  case "$gl_cv_func_printf_directive_n" in
                                     *yes)
-                                      case "$gl_cv_func_printf_flag_grouping" in
+                                      case "$gl_cv_func_printf_directive_ls" in
                                         *yes)
-                                          case "$gl_cv_func_printf_flag_leftadjust" in
+                                          case "$gl_cv_func_printf_directive_lc" in
                                             *yes)
-                                              case "$gl_cv_func_printf_flag_zero" in
+                                              case "$gl_cv_func_printf_positions" in
                                                 *yes)
-                                                  case "$gl_cv_func_printf_precision" in
+                                                  case "$gl_cv_func_printf_flag_grouping" in
                                                     *yes)
-                                                      case "$gl_cv_func_printf_enomem" in
+                                                      case "$gl_cv_func_printf_flag_leftadjust" in
                                                         *yes)
-                                                          if test $ac_cv_func_vasprintf = yes; then
-                                                            # vasprintf exists and is
-                                                            # already POSIX compliant.
-                                                            gl_cv_func_vasprintf_posix=yes
-                                                          fi
+                                                          case "$gl_cv_func_printf_flag_zero" in
+                                                            *yes)
+                                                              case "$gl_cv_func_printf_precision" in
+                                                                *yes)
+                                                                  case "$gl_cv_func_printf_enomem" in
+                                                                    *yes)
+                                                                      if test $ac_cv_func_vasprintf = yes; then
+                                                                        # vasprintf exists and is
+                                                                        # already POSIX compliant.
+                                                                        gl_cv_func_vasprintf_posix=yes
+                                                                      fi
+                                                                      ;;
+                                                                  esac
+                                                                  ;;
+                                                              esac
+                                                              ;;
+                                                          esac
                                                           ;;
                                                       esac
                                                       ;;
@@ -83,19 +110,4 @@ AC_DEFUN([gl_FUNC_VASPRINTF_POSIX],
       esac
       ;;
   esac
-  if test $gl_cv_func_vasprintf_posix = no; then
-    gl_PREREQ_VASNPRINTF_LONG_DOUBLE
-    gl_PREREQ_VASNPRINTF_INFINITE_DOUBLE
-    gl_PREREQ_VASNPRINTF_INFINITE_LONG_DOUBLE
-    gl_PREREQ_VASNPRINTF_DIRECTIVE_A
-    gl_PREREQ_VASNPRINTF_DIRECTIVE_F
-    gl_PREREQ_VASNPRINTF_DIRECTIVE_LS
-    gl_PREREQ_VASNPRINTF_FLAG_GROUPING
-    gl_PREREQ_VASNPRINTF_FLAG_LEFTADJUST
-    gl_PREREQ_VASNPRINTF_FLAG_ZERO
-    gl_PREREQ_VASNPRINTF_PRECISION
-    gl_PREREQ_VASNPRINTF_ENOMEM
-    gl_REPLACE_VASNPRINTF
-    gl_REPLACE_VASPRINTF
-  fi
 ])
diff --git a/m4/vfprintf-posix.m4 b/m4/vfprintf-posix.m4
index ec680522142..6b51c50adab 100644
--- a/m4/vfprintf-posix.m4
+++ b/m4/vfprintf-posix.m4
@@ -1,4 +1,4 @@
-# vfprintf-posix.m4 serial 14
+# vfprintf-posix.m4 serial 18
 dnl Copyright (C) 2007-2023 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -6,14 +6,29 @@ dnl with or without modifications, as long as this notice is preserved.
 
 AC_DEFUN([gl_FUNC_VFPRINTF_POSIX],
 [
+  AC_REQUIRE([gl_FUNC_VFPRINTF_IS_POSIX])
+  if test $gl_cv_func_vfprintf_posix = no; then
+    gl_PREREQ_VASNPRINTF_WITH_POSIX_EXTRAS
+    gl_REPLACE_VASNPRINTF
+    gl_REPLACE_VFPRINTF
+  fi
+])
+
+dnl Test whether vfprintf is POSIX compliant.
+dnl Result is gl_cv_func_vfprintf_posix.
+AC_DEFUN([gl_FUNC_VFPRINTF_IS_POSIX],
+[
   AC_REQUIRE([gl_PRINTF_SIZES_C99])
+  AC_REQUIRE([gl_PRINTF_SIZES_C23])
   AC_REQUIRE([gl_PRINTF_LONG_DOUBLE])
   AC_REQUIRE([gl_PRINTF_INFINITE])
   AC_REQUIRE([gl_PRINTF_INFINITE_LONG_DOUBLE])
   AC_REQUIRE([gl_PRINTF_DIRECTIVE_A])
+  AC_REQUIRE([gl_PRINTF_DIRECTIVE_B])
   AC_REQUIRE([gl_PRINTF_DIRECTIVE_F])
   AC_REQUIRE([gl_PRINTF_DIRECTIVE_N])
   AC_REQUIRE([gl_PRINTF_DIRECTIVE_LS])
+  AC_REQUIRE([gl_PRINTF_DIRECTIVE_LC])
   AC_REQUIRE([gl_PRINTF_POSITIONS])
   AC_REQUIRE([gl_PRINTF_FLAG_GROUPING])
   AC_REQUIRE([gl_PRINTF_FLAG_LEFTADJUST])
@@ -23,35 +38,47 @@ AC_DEFUN([gl_FUNC_VFPRINTF_POSIX],
   gl_cv_func_vfprintf_posix=no
   case "$gl_cv_func_printf_sizes_c99" in
     *yes)
-      case "$gl_cv_func_printf_long_double" in
+      case "$gl_cv_func_printf_sizes_c23" in
         *yes)
-          case "$gl_cv_func_printf_infinite" in
+          case "$gl_cv_func_printf_long_double" in
             *yes)
-              case "$gl_cv_func_printf_infinite_long_double" in
+              case "$gl_cv_func_printf_infinite" in
                 *yes)
-                  case "$gl_cv_func_printf_directive_a" in
+                  case "$gl_cv_func_printf_infinite_long_double" in
                     *yes)
-                      case "$gl_cv_func_printf_directive_f" in
+                      case "$gl_cv_func_printf_directive_a" in
                         *yes)
-                          case "$gl_cv_func_printf_directive_n" in
+                          case "$gl_cv_func_printf_directive_b" in
                             *yes)
-                              case "$gl_cv_func_printf_directive_ls" in
+                              case "$gl_cv_func_printf_directive_f" in
                                 *yes)
-                                  case "$gl_cv_func_printf_positions" in
+                                  case "$gl_cv_func_printf_directive_n" in
                                     *yes)
-                                      case "$gl_cv_func_printf_flag_grouping" in
+                                      case "$gl_cv_func_printf_directive_ls" in
                                         *yes)
-                                          case "$gl_cv_func_printf_flag_leftadjust" in
+                                          case "$gl_cv_func_printf_directive_lc" in
                                             *yes)
-                                              case "$gl_cv_func_printf_flag_zero" in
+                                              case "$gl_cv_func_printf_positions" in
                                                 *yes)
-                                                  case "$gl_cv_func_printf_precision" in
+                                                  case "$gl_cv_func_printf_flag_grouping" in
                                                     *yes)
-                                                      case "$gl_cv_func_printf_enomem" in
+                                                      case "$gl_cv_func_printf_flag_leftadjust" in
                                                         *yes)
-                                                          # vfprintf exists and is
-                                                          # already POSIX compliant.
-                                                          gl_cv_func_vfprintf_posix=yes
+                                                          case "$gl_cv_func_printf_flag_zero" in
+                                                            *yes)
+                                                              case "$gl_cv_func_printf_precision" in
+                                                                *yes)
+                                                                  case "$gl_cv_func_printf_enomem" in
+                                                                    *yes)
+                                                                      # vfprintf exists and is
+                                                                      # already POSIX compliant.
+                                                                      gl_cv_func_vfprintf_posix=yes
+                                                                      ;;
+                                                                  esac
+                                                                  ;;
+                                                              esac
+                                                              ;;
+                                                          esac
                                                           ;;
                                                       esac
                                                       ;;
@@ -80,21 +107,6 @@ AC_DEFUN([gl_FUNC_VFPRINTF_POSIX],
       esac
       ;;
   esac
-  if test $gl_cv_func_vfprintf_posix = no; then
-    gl_PREREQ_VASNPRINTF_LONG_DOUBLE
-    gl_PREREQ_VASNPRINTF_INFINITE_DOUBLE
-    gl_PREREQ_VASNPRINTF_INFINITE_LONG_DOUBLE
-    gl_PREREQ_VASNPRINTF_DIRECTIVE_A
-    gl_PREREQ_VASNPRINTF_DIRECTIVE_F
-    gl_PREREQ_VASNPRINTF_DIRECTIVE_LS
-    gl_PREREQ_VASNPRINTF_FLAG_GROUPING
-    gl_PREREQ_VASNPRINTF_FLAG_LEFTADJUST
-    gl_PREREQ_VASNPRINTF_FLAG_ZERO
-    gl_PREREQ_VASNPRINTF_PRECISION
-    gl_PREREQ_VASNPRINTF_ENOMEM
-    gl_REPLACE_VASNPRINTF
-    gl_REPLACE_VFPRINTF
-  fi
 ])
 
 AC_DEFUN([gl_REPLACE_VFPRINTF],