fix recent clang warnings

Jamfile

@@ -215,6 +215,9 @@ rule warnings ( properties * )
 
 		result += <cflags>-Wno-return-std-move-in-c++11 ;
 		result += <cflags>-Wno-unknown-warning-option ;
+
+# libtorrent uses alloca() carefully
+		result += <cflags>-Wno-alloca ;
 	}
 
 	if <toolset>gcc in $(properties)

include/libtorrent/settings_pack.hpp

@@ -1714,11 +1714,11 @@ namespace aux {
 			max_int_setting_internal
 		};
 
-		enum settings_counts_t : std::uint8_t
+		enum settings_counts_t : int
 		{
-			num_string_settings = max_string_setting_internal - string_type_base,
+			num_string_settings = int(max_string_setting_internal) - int(string_type_base),
-			num_bool_settings = max_bool_setting_internal - bool_type_base,
+			num_bool_settings = int(max_bool_setting_internal) - int(bool_type_base),
-			num_int_settings = max_int_setting_internal - int_type_base
+			num_int_settings = int(max_int_setting_internal) - int(int_type_base)
 		};
 
 		enum suggest_mode_t : std::uint8_t { no_piece_suggestions = 0, suggest_read_cache = 1 };

src/lsd.cpp

@@ -69,8 +69,6 @@ int render_lsd_packet(char* dst, int const len, int const listen_port
 }
 } // anonymous namespace
 
-static error_code dummy;
-
 lsd::lsd(io_service& ios, aux::lsd_callback& cb
 	, address const& listen_address, address const& netmask)
 	: m_callback(cb)

src/upnp.cpp

@@ -1419,7 +1419,7 @@ void upnp::on_upnp_map_response(error_code const& e
 		if (d.lease_duration > 0)
 		{
 			m.expires = aux::time_now()
-				+ seconds(int(d.lease_duration * 0.75f));
+				+ seconds(d.lease_duration * 3 / 4);
 			time_point next_expire = m_refresh_timer.expires_at();
 			if (next_expire < aux::time_now()
 				|| next_expire > m.expires)