dnl 
dnl AC_CXX_NAMESPACES
dnl 
dnl Description
dnl 
dnl  If the compiler can prevent names clashes using namespaces,
dnl  define HAVE_NAMESPACES.
dnl 
dnl Version: 1.2 (last modified: 2000-07-19)
dnl Author: Luc Maisonobe
dnl 
dnl from http://www.gnu.org/software/ac-archive/htmldoc/index.html
dnl 
dnl License:
dnl GNU General Public License
dnl [http://www.gnu.org/software/ac-archive/htmldoc/COPYING.html]
dnl with this special exception
dnl [http://www.gnu.org/software/ac-archive/htmldoc/COPYING-Exception.html]. 
dnl 

AC_DEFUN([AC_CXX_NAMESPACES],
[AC_CACHE_CHECK(whether the compiler implements namespaces,
ac_cv_cxx_namespaces,
[AC_LANG_SAVE
 AC_LANG_CPLUSPLUS
 AC_TRY_COMPILE([namespace Outer { namespace Inner { int i = 0; }}],
                [using namespace Outer::Inner; return i;],
 ac_cv_cxx_namespaces=yes, ac_cv_cxx_namespaces=no)
 AC_LANG_RESTORE
])
if test "$ac_cv_cxx_namespaces" = yes; then
  AC_DEFINE(HAVE_NAMESPACES,,[define if the compiler implements namespaces])
fi
])