announcing support for C++

[Bruno Haible]

A testdir created with
  ./gnulib-tool --create-testdir --dir=../testdir1 --single-configure 
--with-c++-tests `./posix-modules`
is now known to build fine on the following platforms:

  - glibc
  - musl libc
  - macOS 10.13
  - FreeBSD 12
  - NetBSD 7
  - OpenBSD 6.5
  - Solaris 10, 11.0, 11.4, OpenIndiana
  - AIX 7.1, 7.2
  - HP-UX 11.31
  - Haiku
  - Cygwin
  - mingw
  - MSVC 14

This means that the ISO C and POSIX substitutes of gnulib are now supported
in C++ mode.

I don't think future platforms or future versions of existing platforms will
create unsurmountable problems in maintaining this support, because newer
platforms tend to be closer to POSIX than older ones, thus requiring fewer
workarounds.

Therefore we can now declare C++ as being supported for these modules.


2019-12-11  Bruno Haible  <address@hidden>

        doc: Document that ISO C or POSIX substitutes are supported in C++ mode.
        * doc/gnulib-intro.texi (Various Kinds of Modules): Document that ISO C
        and POSIX substitutes are supported in C++ mode.
        * NEWS: Likewise.

diff --git a/NEWS b/NEWS
index 30bb223..8085c35 100644
--- a/NEWS
+++ b/NEWS
@@ -3,6 +3,12 @@ Important general notes
 
 Date        Modules         Changes
 
+2019-12-11  Support for     These modules are now supported in C++ mode as 
well.
+            ISO C or POSIX  This means, while the autoconfiguration uses the C
+            functions       compiler, the resulting header files and function
+                            substitutes can be used with a matching C++ 
compiler
+                            as well.
+
 2019-02-14  gnulib-tool     If you use multiple --local-dir options at once:
                             The first one now has the highest priority, not the
                             last one.
diff --git a/doc/gnulib-intro.texi b/doc/gnulib-intro.texi
index 26f8cb8..5d75c9b 100644
--- a/doc/gnulib-intro.texi
+++ b/doc/gnulib-intro.texi
@@ -323,6 +323,11 @@ with @samp{.in} inserted before the @samp{.h} extension, 
so that on
 systems which do provide a correct
 header file the system's one is used.
 
+The modules in this category are supported in C++ mode as well.  This
+means, while the autoconfiguration uses the C compiler, the resulting
+header files and function substitutes can be used with a matching C++
+compiler as well.
+
 @subsection Enhancements of ISO C or POSIX functions
 
 These are sometimes POSIX functions with GNU extensions also found in