deprecate start_default_features flag, it's only used in deprecated API

bindings/python/src/session.cpp

@@ -818,7 +818,9 @@ void bind_session()
     {
         scope s = class_<dummy10>("session_flags_t");
         s.attr("add_default_plugins") = lt::session::add_default_plugins;
+#if TORRENT_ABI_VERSION == 1
         s.attr("start_default_features") = lt::session::start_default_features;
+#endif
     }
 
     {
@@ -942,8 +944,7 @@ void bind_session()
         .def("__init__", boost::python::make_constructor(&make_session
                 , default_call_policies()
                 , (arg("settings")
-                , arg("flags")=lt::session::start_default_features
-                    | lt::session::add_default_plugins))
+                , arg("flags")=lt::session::add_default_plugins))
         )
 #if TORRENT_ABI_VERSION == 1
         .def(

include/libtorrent/session.hpp

@@ -223,10 +223,10 @@ namespace aux {
 		// default is to start those features. If you do not want them to start,
 		// pass 0 as the flags parameter.
 		session(settings_pack&& pack
-			, session_flags_t const flags = start_default_features | add_default_plugins)
+			, session_flags_t const flags = add_default_plugins)
 		{ start(flags, std::move(pack), nullptr); }
 		session(settings_pack const& pack
-			, session_flags_t const flags = start_default_features | add_default_plugins)
+			, session_flags_t const flags = add_default_plugins)
 		{ start(flags, settings_pack(pack), nullptr); }
 
 		// movable
@@ -252,11 +252,11 @@ namespace aux {
 		// 	destruct the session_proxy object.
 		session(settings_pack&& pack
 			, io_service& ios
-			, session_flags_t const flags = start_default_features | add_default_plugins)
+			, session_flags_t const flags = add_default_plugins)
 		{ start(flags, std::move(pack), &ios); }
 		session(settings_pack const& pack
 			, io_service& ios
-			, session_flags_t const flags = start_default_features | add_default_plugins)
+			, session_flags_t const flags = add_default_plugins)
 		{ start(flags, settings_pack(pack), &ios); }
 
 #if TORRENT_ABI_VERSION == 1

include/libtorrent/session_handle.hpp

@@ -753,9 +753,11 @@ namespace libtorrent {
 		// smart_ban and possibly others.
 		static constexpr session_flags_t add_default_plugins = 0_bit;
 
+#if TORRENT_ABI_VERSION == 1
 		// this will start features like DHT, local service discovery, UPnP
 		// and NAT-PMP.
-		static constexpr session_flags_t start_default_features = 1_bit;
+		static constexpr session_flags_t TORRENT_DEPRECATED_MEMBER start_default_features = 1_bit;
+#endif
 
 		// ``remove_torrent()`` will close all peer connections associated with
 		// the torrent and tell the tracker that we've stopped participating in

src/session_handle.cpp

@@ -67,7 +67,9 @@ namespace libtorrent {
 #endif
 
 	constexpr session_flags_t session_handle::add_default_plugins;
+#if TORRENT_ABI_VERSION == 1
 	constexpr session_flags_t session_handle::start_default_features;
+#endif
 
 	constexpr remove_flags_t session_handle::delete_files;
 	constexpr remove_flags_t session_handle::delete_partfile;