snprintf-gnu: New module.

* m4/snprintf-posix.m4 (gl_FUNC_SNPRINTF_IS_POSIX): New macro,
extracted from gl_FUNC_SNPRINTF_POSIX.
(gl_FUNC_SNPRINTF_POSIX): Require it. Invoke
gl_PREREQ_VASNPRINTF_WITH_POSIX_EXTRAS.
* m4/snprintf-gnu.m4: New file, based on m4/snprintf-posix.m4.
* modules/snprintf-gnu: New file, based on modules/vasnprintf-gnu.
* doc/posix-functions/snprintf.texi: Mention the new module.

5 files changed, 88 insertions, 21 deletions

diff --git a/ChangeLog b/ChangeLog
index 21b11ddca4..1b5e632a96 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,16 @@
 2023-03-24  Bruno Haible  <bruno@clisp.org>
 
+	snprintf-gnu: New module.
+	* m4/snprintf-posix.m4 (gl_FUNC_SNPRINTF_IS_POSIX): New macro,
+	extracted from gl_FUNC_SNPRINTF_POSIX.
+	(gl_FUNC_SNPRINTF_POSIX): Require it. Invoke
+	gl_PREREQ_VASNPRINTF_WITH_POSIX_EXTRAS.
+	* m4/snprintf-gnu.m4: New file, based on m4/snprintf-posix.m4.
+	* modules/snprintf-gnu: New file, based on modules/vasnprintf-gnu.
+	* doc/posix-functions/snprintf.texi: Mention the new module.
+
+2023-03-24  Bruno Haible  <bruno@clisp.org>
+
 	vsnprintf-gnu: Add tests.
 	* tests/test-vsnprintf-gnu.c: New file, based on
 	tests/test-vsnprintf-posix.c.
diff --git a/doc/posix-functions/snprintf.texi b/doc/posix-functions/snprintf.texi
index 9ea76cfa8b..a5a7550c7d 100644
--- a/doc/posix-functions/snprintf.texi
+++ b/doc/posix-functions/snprintf.texi
@@ -4,9 +4,9 @@
 
 POSIX specification:@* @url{https://pubs.opengroup.org/onlinepubs/9699919799/functions/snprintf.html}
 
-Gnulib module: snprintf or snprintf-posix
+Gnulib module: snprintf or snprintf-posix or snprintf-gnu
 
-Portability problems fixed by either Gnulib module @code{snprintf} or @code{snprintf-posix}:
+Portability problems fixed by either Gnulib module @code{snprintf} or @code{snprintf-posix} or @code{snprintf-gnu}:
 @itemize
 @item
 This function is missing on some platforms:
@@ -21,7 +21,7 @@ platforms:
 HP-UX 11, IRIX 6.5, Solaris 9, mingw.
 @end itemize
 
-Portability problems fixed by Gnulib module @code{snprintf-posix}:
+Portability problems fixed by either Gnulib module @code{snprintf-posix} or @code{snprintf-gnu}:
 @itemize
 @item
 This function does not support size specifiers as in C99 (@code{hh}, @code{ll},
@@ -94,6 +94,13 @@ This function does not fully support the @samp{n} directive on some platforms:
 HP-UX 11, mingw, MSVC 14.
 @end itemize
 
+Portability problems fixed by Gnulib module @code{snprintf-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 not fixed by Gnulib:
 @itemize
 @item
diff --git a/m4/snprintf-gnu.m4 b/m4/snprintf-gnu.m4
new file mode 100644
index 0000000000..cc3ab77c78
--- /dev/null
+++ b/m4/snprintf-gnu.m4
@@ -0,0 +1,25 @@
+# snprintf-gnu.m4 serial 1
+dnl Copyright (C) 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_SNPRINTF_GNU],
+[
+  AC_REQUIRE([gl_FUNC_SNPRINTF_IS_POSIX])
+  AC_REQUIRE([gl_PRINTF_DIRECTIVE_UPPERCASE_B])
+  gl_cv_func_snprintf_gnu=no
+  if test $gl_cv_func_snprintf_posix = yes; then
+    case "$gl_cv_func_printf_directive_uppercase_b" in
+      *yes)
+        # snprintf exists and is already POSIX compliant and GNU compatible.
+        gl_cv_func_snprintf_gnu=yes
+        ;;
+    esac
+  fi
+  if test $gl_cv_func_snprintf_gnu = no; then
+    gl_PREREQ_VASNPRINTF_WITH_GNU_EXTRAS
+    gl_REPLACE_VASNPRINTF
+    gl_REPLACE_SNPRINTF
+  fi
+])
diff --git a/m4/snprintf-posix.m4 b/m4/snprintf-posix.m4
index 1a0147f3b6..303db27a84 100644
--- a/m4/snprintf-posix.m4
+++ b/m4/snprintf-posix.m4
@@ -1,4 +1,4 @@
-# snprintf-posix.m4 serial 16
+# snprintf-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,
@@ -6,6 +6,18 @@ dnl with or without modifications, as long as this notice is preserved.
 
 AC_DEFUN([gl_FUNC_SNPRINTF_POSIX],
 [
+  AC_REQUIRE([gl_FUNC_SNPRINTF_IS_POSIX])
+  if test $gl_cv_func_snprintf_posix = no; then
+    gl_PREREQ_VASNPRINTF_WITH_POSIX_EXTRAS
+    gl_REPLACE_VASNPRINTF
+    gl_REPLACE_SNPRINTF
+  fi
+])
+
+dnl Test whether snprintf exists and is POSIX compliant.
+dnl Result is gl_cv_func_snprintf_posix.
+AC_DEFUN([gl_FUNC_SNPRINTF_IS_POSIX],
+[
   AC_REQUIRE([gl_PRINTF_SIZES_C99])
   AC_REQUIRE([gl_PRINTF_LONG_DOUBLE])
   AC_REQUIRE([gl_PRINTF_INFINITE])
@@ -118,21 +130,4 @@ AC_DEFUN([gl_FUNC_SNPRINTF_POSIX],
         ;;
     esac
   fi
-  if test $gl_cv_func_snprintf_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_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
-    gl_PREREQ_VASNPRINTF_PRECISION
-    gl_PREREQ_VASNPRINTF_ENOMEM
-    gl_REPLACE_VASNPRINTF
-    gl_REPLACE_SNPRINTF
-  fi
 ])
diff --git a/modules/snprintf-gnu b/modules/snprintf-gnu
new file mode 100644
index 0000000000..2850c16a34
--- /dev/null
+++ b/modules/snprintf-gnu
@@ -0,0 +1,29 @@
+Description:
+POSIX and GNU compatible snprintf() function: print formatted output to
+a fixed length string
+
+Comment:
+This module should not be used as a dependency from a test module,
+otherwise when this module occurs as a tests-related module, it will
+have side effects on the compilation of the 'vasnprintf' module, if
+that module occurs among the main modules in lib/.
+
+Files:
+m4/snprintf-gnu.m4
+
+Depends-on:
+snprintf-posix
+
+configure.ac:
+gl_FUNC_SNPRINTF_GNU
+
+Makefile.am:
+
+Include:
+<stdio.h>
+
+License:
+LGPL
+
+Maintainer:
+all