Merge [51862], [53211], [53212], and [53218] from the trunk

[SVN r53872]

include/boost/tuple/detail/tuple_basic.hpp

@@ -213,7 +213,7 @@ struct element_impl<0, T, true /* IsConst */>
 
 
 template<int N, class T>
-struct element: 
+struct element:
   public detail::element_impl<N, T, ::boost::is_const<T>::value>
 {
 };
@@ -488,11 +488,20 @@ struct length<tuple<> > {
   BOOST_STATIC_CONSTANT(int, value = 0);
 };
 
+template<>
+struct length<tuple<> const> {
+  BOOST_STATIC_CONSTANT(int, value = 0);
+};
+
 template<>
 struct length<null_type> {
   BOOST_STATIC_CONSTANT(int, value = 0);
 };
 
+template<>
+struct length<null_type const> {
+  BOOST_STATIC_CONSTANT(int, value = 0);
+};
 
 namespace detail {
 

include/boost/tuple/tuple_io.hpp

@@ -285,6 +285,21 @@ print(std::basic_ostream<CharType, CharTrait>& o, const cons<T1, T2>& t) {
 } // namespace detail
 
 #if defined (BOOST_NO_TEMPLATED_STREAMS)
+
+inline std::ostream& operator<<(std::ostream& o, const null_type& t) {
+  if (!o.good() ) return o;
+ 
+  const char l = 
+    detail::format_info::get_manipulator(o, detail::format_info::open);
+  const char r = 
+    detail::format_info::get_manipulator(o, detail::format_info::close);
+   
+  o << l;
+  o << r;
+
+  return o;
+}
+
 template<class T1, class T2>
 inline std::ostream& operator<<(std::ostream& o, const cons<T1, T2>& t) {
   if (!o.good() ) return o;
@@ -305,6 +320,23 @@ inline std::ostream& operator<<(std::ostream& o, const cons<T1, T2>& t) {
 
 #else
 
+template<class CharType, class CharTrait>
+inline std::basic_ostream<CharType, CharTrait>& 
+operator<<(std::basic_ostream<CharType, CharTrait>& o, 
+           const null_type& t) {
+  if (!o.good() ) return o;
+ 
+  const CharType l = 
+    detail::format_info::get_manipulator(o, detail::format_info::open);
+  const CharType r = 
+    detail::format_info::get_manipulator(o, detail::format_info::close);
+   
+  o << l;
+  o << r;
+
+  return o;
+}
+
 template<class CharType, class CharTrait, class T1, class T2>
 inline std::basic_ostream<CharType, CharTrait>& 
 operator<<(std::basic_ostream<CharType, CharTrait>& o,