(svn r19141) -Fix [FS#3619] (r18421): look-ahead for multitile waypoints 'made up' data that shouldn't go into the cache, causing desyncs in MP

src/pathfinder/yapf/yapf_costrail.hpp

@@ -410,7 +410,9 @@ no_entry_cost: // jump here at the beginning if the node has no parent (it is th
 				end_segment_reason |= ESRB_DEPOT;
 
 			} else if (cur.tile_type == MP_STATION && IsRailWaypoint(cur.tile)) {
-				if (v->current_order.IsType(OT_GOTO_WAYPOINT) && GetStationIndex(cur.tile) == v->current_order.GetDestination()) {
+				if (v->current_order.IsType(OT_GOTO_WAYPOINT) &&
+						GetStationIndex(cur.tile) == v->current_order.GetDestination() &&
+						!Waypoint::Get(v->current_order.GetDestination())->IsSingleTile()) {
 					/* This waypoint is our destination; maybe this isn't an unreserved
 					 * one, so check that and if so see that as the last signal being
 					 * red. This way waypoints near stations should work better. */

src/pathfinder/yapf/yapf_destrail.hpp

@@ -135,8 +135,17 @@ public:
 	void SetDestination(const Train *v)
 	{
 		switch (v->current_order.GetType()) {
-			case OT_GOTO_STATION:
 			case OT_GOTO_WAYPOINT:
+				if (!Waypoint::Get(v->current_order.GetDestination())->IsSingleTile()) {
+					/* In case of 'complex' waypoints we need to do a look
+					 * ahead. This look ahead messes a bit about, which
+					 * means that it 'corrupts' the cache. To prevent this
+					 * we disable caching when we're looking for a complex
+					 * waypoint. */
+					Yapf().DisableCache(true);
+				}
+				/* FALL THROUGH */
+			case OT_GOTO_STATION:
 				m_destTile = CalcClosestStationTile(v->current_order.GetDestination(), v->tile, v->current_order.IsType(OT_GOTO_STATION) ? STATION_RAIL : STATION_WAYPOINT);
 				m_dest_station_id = v->current_order.GetDestination();
 				m_destTrackdirs = INVALID_TRACKDIR_BIT;

src/waypoint_base.h

@@ -40,6 +40,15 @@ struct Waypoint : SpecializedStation<Waypoint, true> {
 	{
 		return 1;
 	}
+
+	/**
+	 * Is this a single tile waypoint?
+	 * @return true if it is.
+	 */
+	FORCEINLINE bool IsSingleTile() const
+	{
+		return (this->facilities & FACIL_TRAIN) != 0 && this->train_station.w == 1 && this->train_station.h == 1;
+	}
 };
 
 #define FOR_ALL_WAYPOINTS(var) FOR_ALL_BASE_STATIONS_OF_TYPE(Waypoint, var)