Change: Avoid crashing to the side of a train

When a road vehicle is already running on a multi level crossing, and a train shows up ahead, don't make the road vehicle crash on the side of the train.

src/road_cmd.cpp

@@ -26,6 +26,7 @@
 #include "effectvehicle_base.h"
 #include "elrail_func.h"
 #include "roadveh.h"
+#include "train.h"
 #include "town.h"
 #include "company_base.h"
 #include "core/random_func.hpp"
@@ -2086,6 +2087,8 @@ static TrackStatus GetTileTrackStatus_Road(TileIndex tile, TransportType mode, u
 					trackdirbits = TrackBitsToTrackdirBits(AxisToTrackBits(axis));
 					if (IsCrossingBarred(tile)) {
 						red_signals = trackdirbits;
+						if (TrainOnCrossing(tile)) break;
+
 						auto mask_red_signal_bits_if_crossing_barred = [&](TileIndex t, TrackdirBits mask) {
 							if (IsLevelCrossingTile(t) && IsCrossingBarred(t)) red_signals &= mask;
 						};

src/train.h

@@ -65,6 +65,8 @@ int GetTrainStopLocation(StationID station_id, TileIndex tile, const Train *v, i
 
 void GetTrainSpriteSize(EngineID engine, uint &width, uint &height, int &xoffs, int &yoffs, EngineImageType image_type);
 
+bool TrainOnCrossing(TileIndex tile);
+
 /** Variables that are cached to improve performance and such */
 struct TrainCache {
 	/* Cached wagon override spritegroup */

src/train_cmd.cpp

@@ -1658,6 +1658,19 @@ static Vehicle *TrainOnTileEnum(Vehicle *v, void *)
 	return (v->type == VEH_TRAIN) ? v : nullptr;
 }
 
+/**
+ * Check if a level crossing tile has a train on it
+ * @param tile tile to test
+ * @return true if a train is on the crossing
+ * @pre tile is a level crossing
+ */
+bool TrainOnCrossing(TileIndex tile)
+{
+	assert(IsLevelCrossingTile(tile));
+
+	return HasVehicleOnPos(tile, nullptr, &TrainOnTileEnum);
+}
+
 
 /**
  * Checks if a train is approaching a rail-road crossing
@@ -1709,7 +1722,7 @@ static bool TrainApproachingCrossing(TileIndex tile)
 static inline bool CheckLevelCrossing(TileIndex tile)
 {
 	/* reserved || train on crossing || train approaching crossing */
-	return HasCrossingReservation(tile) || HasVehicleOnPos(tile, NULL, &TrainOnTileEnum) || TrainApproachingCrossing(tile);
+	return HasCrossingReservation(tile) || TrainOnCrossing(tile) || TrainApproachingCrossing(tile);
 }
 
 /**