Ticket #4728: boost_iostreams-mode_adaptor-flushable.patch

boost/iostreams/detail/adapter/mode_adapter.hpp

@@ -23 +23 @@
 #include <boost/iostreams/traits.hpp>
 #include <boost/iostreams/operations.hpp> 
 #include <boost/mpl/if.hpp> 
+#include <boost/type_traits/is_convertible.hpp>
 
 namespace boost { namespace iostreams { namespace detail {
 
@@ -38 +39 @@
           device_tag,
           mpl::if_<is_filter<T>, filter_tag, device_tag>,
           mpl::if_<is_filter<T>, multichar_tag, empty_base>,
+          mpl::if_<
+              mpl::or_<
+                  is_convertible<BOOST_DEDUCED_TYPENAME category_of<T>::type, ostream_tag>,
+                  is_convertible<BOOST_DEDUCED_TYPENAME category_of<T>::type, streambuf_tag>,
+                  is_convertible<BOOST_DEDUCED_TYPENAME category_of<T>::type, flushable_tag>
+              >,
+              flushable_tag,
+              empty_base
+          >::type,
           #if !BOOST_WORKAROUND(BOOST_MSVC, < 1300)
               closable_tag, // VC6 can't see member close()!
           #endif
@@ -67 +77 @@
     std::streamsize write(Sink& snk, const char_type* s, std::streamsize n)
     { return iostreams::write(t_, snk, s, n); }
 
+    bool flush()
+    { return iostreams::flush(t_); }
+
+    template<typename Sink>
+    bool flush(Sink& snk)
+    { return iostreams::flush(t_, snk); }
+
     template<typename Device>
     std::streampos seek(Device& dev, stream_offset off, BOOST_IOS::seekdir way)
     { return iostreams::seek(t_, dev, off, way); }