printf-gnu: New module.

* m4/printf-posix.m4: Renamed from m4/printf-posix-rpl.m4.
(gl_FUNC_PRINTF_IS_POSIX): New macro.
(gl_FUNC_PRINTF_POSIX): Require it. Don't require
gl_FUNC_VFPRINTF_POSIX. Invoke gl_PREREQ_VASNPRINTF_WITH_POSIX_EXTRAS
and gl_REPLACE_VASNPRINTF.
* m4/printf-gnu.m4: New file, based on m4/fprintf-posix.m4.
* modules/printf-posix (Files): Update.
* modules/printf-gnu: New file, based on modules/vasnprintf-gnu.
* doc/posix-functions/printf.texi: Mention the new module.

1 files changed, 11 insertions, 4 deletions

diff --git a/doc/posix-functions/printf.texi b/doc/posix-functions/printf.texi
index 8a3971aa30..382873e9e0 100644
--- a/doc/posix-functions/printf.texi
+++ b/doc/posix-functions/printf.texi
@@ -4,9 +4,9 @@
 
 POSIX specification:@* @url{https://pubs.opengroup.org/onlinepubs/9699919799/functions/printf.html}
 
-Gnulib module: printf-posix or stdio, nonblocking, sigpipe
+Gnulib module: printf-posix or printf-gnu or stdio, nonblocking, sigpipe
 
-Portability problems fixed by Gnulib module @code{printf-posix}:
+Portability problems fixed by either Gnulib module @code{printf-posix} or @code{printf-gnu}:
 @itemize
 @item
 This function does not support size specifiers as in C99 (@code{hh}, @code{ll},
@@ -77,7 +77,14 @@ This function can crash in out-of-memory conditions on some platforms:
 FreeBSD 13.0, NetBSD 5.0.
 @end itemize
 
-Portability problems fixed by Gnulib module @code{stdio} or @code{printf-posix}, together with module @code{nonblocking}:
+Portability problems fixed by Gnulib module @code{printf-gnu}:
+@itemize
+@item
+This function does not support the @samp{B} directive on some platforms:
+glibc 2.34, FreeBSD 13.1, NetBSD 9.0, OpenBSD 7.2, macOS 12.5, AIX 7.2, Solaris 11.4, and others.
+@end itemize
+
+Portability problems fixed by Gnulib module @code{stdio} or @code{printf-posix} or @code{printf-gnu}, together with module @code{nonblocking}:
 @itemize
 @item
 When writing to a non-blocking pipe whose buffer is full, this function fails
@@ -86,7 +93,7 @@ platforms:
 mingw, MSVC 14.
 @end itemize
 
-Portability problems fixed by Gnulib module @code{stdio} or @code{printf-posix}, together with module @code{sigpipe}:
+Portability problems fixed by Gnulib module @code{stdio} or @code{printf-posix} or @code{printf-gnu}, together with module @code{sigpipe}:
 @itemize
 @item
 When writing to a pipe with no readers, this function fails, instead of