Fix: Prevent ships moving into docks after finishing (un)loading. (#6791)

3 files changed, 31 insertions, 27 deletions

diff --git a/src/ship_cmd.cpp b/src/ship_cmd.cpp
index 967cd4e1d..0bdcf7041 100644
--- a/src/ship_cmd.cpp
+++ b/src/ship_cmd.cpp
@@ -537,6 +537,10 @@ static void ShipController(Ship *v)
 				if (v->current_order.IsType(OT_LEAVESTATION)) {
 					v->current_order.Free();
 					SetWindowWidgetDirty(WC_VEHICLE_VIEW, v->index, WID_VV_START_STOP);
+					/* Test if continuing forward would lead to a dead-end, moving into the dock. */
+					DiagDirection exitdir = VehicleExitDir(v->direction, v->state);
+					TileIndex tile = TileAddByDiagDir(v->tile, exitdir);
+					if (TrackStatusToTrackBits(GetTileTrackStatus(tile, TRANSPORT_WATER, 0, exitdir)) == TRACK_BIT_NONE) goto reverse_direction;
 				} else if (v->dest_tile != 0) {
 					/* We have a target, let's see if we reached it... */
 					if (v->current_order.IsType(OT_GOTO_WAYPOINT) &&
diff --git a/src/track_func.h b/src/track_func.h
index 68de827ef..5e1585c08 100644
--- a/src/track_func.h
+++ b/src/track_func.h
@@ -692,4 +692,25 @@ static inline bool IsUphillTrackdir(Slope slope, Trackdir dir)
 	return HasBit(_uphill_trackdirs[RemoveHalftileSlope(slope)], dir);
 }
 
+/**
+ * Determine the side in which the vehicle will leave the tile
+ *
+ * @param direction vehicle direction
+ * @param track vehicle track bits
+ * @return side of tile the vehicle will leave
+ */
+static inline DiagDirection VehicleExitDir(Direction direction, TrackBits track)
+{
+	static const TrackBits state_dir_table[DIAGDIR_END] = { TRACK_BIT_RIGHT, TRACK_BIT_LOWER, TRACK_BIT_LEFT, TRACK_BIT_UPPER };
+
+	DiagDirection diagdir = DirToDiagDir(direction);
+
+	/* Determine the diagonal direction in which we will exit this tile */
+	if (!HasBit(direction, 0) && track != state_dir_table[diagdir]) {
+		diagdir = ChangeDiagDir(diagdir, DIAGDIRDIFF_90LEFT);
+	}
+
+	return diagdir;
+}
+
 #endif /* TRACK_FUNC_H */
diff --git a/src/train_cmd.cpp b/src/train_cmd.cpp
index 9f4ecbea6..daebb9789 100644
--- a/src/train_cmd.cpp
+++ b/src/train_cmd.cpp
@@ -57,27 +57,6 @@ bool IsValidImageIndex<VEH_TRAIN>(uint8 image_index)
 	return image_index < lengthof(_engine_sprite_base);
 }
 
-/**
- * Determine the side in which the train will leave the tile
- *
- * @param direction vehicle direction
- * @param track vehicle track bits
- * @return side of tile the train will leave
- */
-static inline DiagDirection TrainExitDir(Direction direction, TrackBits track)
-{
-	static const TrackBits state_dir_table[DIAGDIR_END] = { TRACK_BIT_RIGHT, TRACK_BIT_LOWER, TRACK_BIT_LEFT, TRACK_BIT_UPPER };
-
-	DiagDirection diagdir = DirToDiagDir(direction);
-
-	/* Determine the diagonal direction in which we will exit this tile */
-	if (!HasBit(direction, 0) && track != state_dir_table[diagdir]) {
-		diagdir = ChangeDiagDir(diagdir, DIAGDIRDIFF_90LEFT);
-	}
-
-	return diagdir;
-}
-
 
 /**
  * Return the cargo weight multiplier to use for a rail vehicle
@@ -1872,9 +1851,9 @@ void ReverseTrainDirection(Train *v)
 		return;
 	}
 
-	/* TrainExitDir does not always produce the desired dir for depots and
+	/* VehicleExitDir does not always produce the desired dir for depots and
 	 * tunnels/bridges that is needed for UpdateSignalsOnSegment. */
-	DiagDirection dir = TrainExitDir(v->direction, v->track);
+	DiagDirection dir = VehicleExitDir(v->direction, v->track);
 	if (IsRailDepotTile(v->tile) || IsTileType(v->tile, MP_TUNNELBRIDGE)) dir = INVALID_DIAGDIR;
 
 	if (UpdateSignalsOnSegment(v->tile, dir, v->owner) == SIGSEG_PBS || _settings_game.pf.reserve_paths) {
@@ -3098,7 +3077,7 @@ static Vehicle *CheckTrainAtSignal(Vehicle *v, void *data)
 	/* not front engine of a train, inside wormhole or depot, crashed */
 	if (!t->IsFrontEngine() || !(t->track & TRACK_BIT_MASK)) return NULL;
 
-	if (t->cur_speed > 5 || TrainExitDir(t->direction, t->track) != exitdir) return NULL;
+	if (t->cur_speed > 5 || VehicleExitDir(t->direction, t->track) != exitdir) return NULL;
 
 	return t;
 }
@@ -3681,7 +3660,7 @@ static TileIndex TrainApproachingCrossingTile(const Train *v)
 
 	if (!TrainCanLeaveTile(v)) return INVALID_TILE;
 
-	DiagDirection dir = TrainExitDir(v->direction, v->track);
+	DiagDirection dir = VehicleExitDir(v->direction, v->track);
 	TileIndex tile = v->tile + TileOffsByDiagDir(dir);
 
 	/* not a crossing || wrong axis || unusable rail (wrong type or owner) */
@@ -3718,7 +3697,7 @@ static bool TrainCheckIfLineEnds(Train *v, bool reverse)
 	if (!TrainCanLeaveTile(v)) return true;
 
 	/* Determine the non-diagonal direction in which we will exit this tile */
-	DiagDirection dir = TrainExitDir(v->direction, v->track);
+	DiagDirection dir = VehicleExitDir(v->direction, v->track);
 	/* Calculate next tile */
 	TileIndex tile = v->tile + TileOffsByDiagDir(dir);
 
@@ -3786,7 +3765,7 @@ static bool TrainLocoHandler(Train *v, bool mode)
 		/* Try to reserve a path when leaving the station as we
 		 * might not be marked as wanting a reservation, e.g.
 		 * when an overlength train gets turned around in a station. */
-		DiagDirection dir = TrainExitDir(v->direction, v->track);
+		DiagDirection dir = VehicleExitDir(v->direction, v->track);
 		if (IsRailDepotTile(v->tile) || IsTileType(v->tile, MP_TUNNELBRIDGE)) dir = INVALID_DIAGDIR;
 
 		if (UpdateSignalsOnSegment(v->tile, dir, v->owner) == SIGSEG_PBS || _settings_game.pf.reserve_paths) {