fprintf-gnu: New module.

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

5 files changed, 88 insertions, 22 deletions

diff --git a/ChangeLog b/ChangeLog
index 46d1665f2b..07ef028cff 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,16 @@
 2023-03-24  Bruno Haible  <bruno@clisp.org>
 
+	fprintf-gnu: New module.
+	* m4/fprintf-posix.m4 (gl_FUNC_FPRINTF_IS_POSIX): New macro,
+	extracted from gl_FUNC_FPRINTF_POSIX.
+	(gl_FUNC_FPRINTF_POSIX): Require it. Invoke
+	gl_PREREQ_VASNPRINTF_WITH_POSIX_EXTRAS.
+	* m4/fprintf-gnu.m4: New file, based on m4/fprintf-posix.m4.
+	* modules/fprintf-gnu: New file, based on modules/vasnprintf-gnu.
+	* doc/posix-functions/fprintf.texi: Mention the new module.
+
+2023-03-24  Bruno Haible  <bruno@clisp.org>
+
 	vfprintf-gnu: Add tests.
 	* tests/test-vfprintf-gnu.sh: New file, based on
 	tests/test-vfprintf-posix.sh.
diff --git a/doc/posix-functions/fprintf.texi b/doc/posix-functions/fprintf.texi
index 513777c0a4..3ee74b41ae 100644
--- a/doc/posix-functions/fprintf.texi
+++ b/doc/posix-functions/fprintf.texi
@@ -4,9 +4,9 @@
 
 POSIX specification:@* @url{https://pubs.opengroup.org/onlinepubs/9699919799/functions/fprintf.html}
 
-Gnulib module: fprintf-posix or stdio, nonblocking, sigpipe
+Gnulib module: fprintf-posix or fprintf-gnu or stdio, nonblocking, sigpipe
 
-Portability problems fixed by Gnulib module @code{fprintf-posix}:
+Portability problems fixed by either Gnulib module @code{fprintf-posix} or @code{fprintf-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{fprintf-posix}, together with module @code{nonblocking}:
+Portability problems fixed by Gnulib module @code{fprintf-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{fprintf-posix} or @code{fprintf-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{fprintf-posix}, together with module @code{sigpipe}:
+Portability problems fixed by Gnulib module @code{stdio} or @code{fprintf-posix} or @code{fprintf-gnu}, together with module @code{sigpipe}:
 @itemize
 @item
 When writing to a pipe with no readers, this function fails, instead of
diff --git a/m4/fprintf-gnu.m4 b/m4/fprintf-gnu.m4
new file mode 100644
index 0000000000..b1a32ce188
--- /dev/null
+++ b/m4/fprintf-gnu.m4
@@ -0,0 +1,25 @@
+# fprintf-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_FPRINTF_GNU],
+[
+  AC_REQUIRE([gl_FUNC_FPRINTF_IS_POSIX])
+  AC_REQUIRE([gl_PRINTF_DIRECTIVE_UPPERCASE_B])
+  gl_cv_func_fprintf_gnu=no
+  if test $gl_cv_func_fprintf_posix = yes; then
+    case "$gl_cv_func_printf_directive_uppercase_b" in
+      *yes)
+        # fprintf is already POSIX compliant and GNU compatible.
+        gl_cv_func_fprintf_gnu=yes
+        ;;
+    esac
+  fi
+  if test $gl_cv_func_fprintf_gnu = no; then
+    gl_PREREQ_VASNPRINTF_WITH_GNU_EXTRAS
+    gl_REPLACE_VASNPRINTF
+    gl_REPLACE_FPRINTF
+  fi
+])
diff --git a/m4/fprintf-posix.m4 b/m4/fprintf-posix.m4
index 1eb669fd5d..4d016c4fc5 100644
--- a/m4/fprintf-posix.m4
+++ b/m4/fprintf-posix.m4
@@ -1,4 +1,4 @@
-# fprintf-posix.m4 serial 16
+# fprintf-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_FPRINTF_POSIX],
 [
+  AC_REQUIRE([gl_FUNC_FPRINTF_IS_POSIX])
+  if test $gl_cv_func_fprintf_posix = no; then
+    gl_PREREQ_VASNPRINTF_WITH_POSIX_EXTRAS
+    gl_REPLACE_VASNPRINTF
+    gl_REPLACE_FPRINTF
+  fi
+])
+
+dnl Test whether fprintf is POSIX compliant.
+dnl Result is gl_cv_func_fprintf_posix.
+AC_DEFUN([gl_FUNC_FPRINTF_IS_POSIX],
+[
   AC_REQUIRE([gl_PRINTF_SIZES_C99])
   AC_REQUIRE([gl_PRINTF_LONG_DOUBLE])
   AC_REQUIRE([gl_PRINTF_INFINITE])
@@ -90,23 +102,6 @@ AC_DEFUN([gl_FUNC_FPRINTF_POSIX],
       esac
       ;;
   esac
-  if test $gl_cv_func_fprintf_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_FPRINTF
-  fi
 ])
 
 AC_DEFUN([gl_REPLACE_FPRINTF],
diff --git a/modules/fprintf-gnu b/modules/fprintf-gnu
new file mode 100644
index 0000000000..fce7578459
--- /dev/null
+++ b/modules/fprintf-gnu
@@ -0,0 +1,28 @@
+Description:
+POSIX and GNU compatible fprintf() function: print formatted output to a stream
+
+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/fprintf-gnu.m4
+
+Depends-on:
+fprintf-posix
+
+configure.ac:
+gl_FUNC_FPRINTF_GNU
+
+Makefile.am:
+
+Include:
+<stdio.h>
+
+License:
+LGPL
+
+Maintainer:
+all