Minor changes to avoid undefined behaviour warnings.

Avoid creating a reference from a nullptr.
Avoid trying a malloc and memcpy into a 0 length buffer.
Virtual trains should never be drawn.

src/newgrf.cpp

@@ -3664,8 +3664,11 @@ static void DuplicateTileTable(AirportSpec *as)
 		MemCpyT(table_list[i], as->table[i], num_tiles);
 	}
 	as->table = table_list;
-	HangarTileTable *depot_table = MallocT<HangarTileTable>(as->nof_depots);
+	HangarTileTable *depot_table = NULL;
-	MemCpyT(depot_table, as->depot_table, as->nof_depots);
+	if (as->nof_depots > 0) {
+		depot_table = MallocT<HangarTileTable>(as->nof_depots);
+		MemCpyT(depot_table, as->depot_table, as->nof_depots);
+	}
 	as->depot_table = depot_table;
 }
 

src/pathfinder/follow_track.hpp

@@ -236,7 +236,7 @@ protected:
 	/** stores track status (available trackdirs) for the new tile into m_new_td_bits */
 	inline bool QueryNewTileTrackStatus()
 	{
-		CPerfStart perf(*m_pPerf);
+		CPerfStart perf(m_pPerf);
 		if (IsRailTT() && IsPlainRailTile(m_new_tile)) {
 			m_new_td_bits = (TrackdirBits)(GetTrackBits(m_new_tile) * 0x101);
 		} else {

src/pathfinder/pf_performance_timer.hpp

@@ -51,7 +51,7 @@ struct CPerfStartReal
 {
 	CPerformanceTimer *m_pperf;
 
-	inline CPerfStartReal(CPerformanceTimer& perf) : m_pperf(&perf)
+	inline CPerfStartReal(CPerformanceTimer* perf) : m_pperf(perf)
 	{
 		if (m_pperf != NULL) m_pperf->Start();
 	}
@@ -72,7 +72,7 @@ struct CPerfStartReal
 
 struct CPerfStartFake
 {
-	inline CPerfStartFake(CPerformanceTimer& perf) {}
+	inline CPerfStartFake(CPerformanceTimer* perf) {}
 	inline ~CPerfStartFake() {}
 	inline void Stop() {}
 };

src/pathfinder/yapf/yapf_costrail.hpp

@@ -94,7 +94,7 @@ protected:
 public:
 	inline int SlopeCost(TileIndex tile, Trackdir td)
 	{
-		CPerfStart perf_cost(Yapf().m_perf_slope_cost);
+		CPerfStart perf_cost(&Yapf().m_perf_slope_cost);
 		if (!stSlopeCost(tile, td)) return 0;
 		return Yapf().PfGetSettings().rail_slope_penalty;
 	}
@@ -280,7 +280,7 @@ public:
 	{
 		int cost = 0;
 		/* if there is one-way signal in the opposite direction, then it is not our way */
-		CPerfStart perf_cost(Yapf().m_perf_other_cost);
+		CPerfStart perf_cost(&Yapf().m_perf_other_cost);
 		if (IsTileType(tile, MP_RAILWAY)) {
 			bool has_signal_against = HasSignalOnTrackdir(tile, ReverseTrackdir(trackdir));
 			bool has_signal_along = HasSignalOnTrackdir(tile, trackdir);
@@ -402,7 +402,7 @@ public:
 		assert(tf->m_new_tile == n.m_key.m_tile);
 		assert((TrackdirToTrackdirBits(n.m_key.m_td) & tf->m_new_td_bits) != TRACKDIR_BIT_NONE);
 
-		CPerfStart perf_cost(Yapf().m_perf_cost);
+		CPerfStart perf_cost(&Yapf().m_perf_cost);
 
 		/* Does the node have some parent node? */
 		bool has_parent = (n.m_parent != NULL);

src/vehicle.cpp

@@ -296,10 +296,10 @@ uint Vehicle::Crash(bool flooded)
  */
 bool Vehicle::IsDrawn() const
 {
-	return !(this->vehstatus & VS_HIDDEN) ||
+	return !(HasBit(this->subtype, GVSF_VIRTUAL)) && (!(this->vehstatus & VS_HIDDEN) ||
 			(IsTransparencySet(TO_TUNNELS) &&
 				((this->type == VEH_TRAIN && Train::From(this)->track == TRACK_BIT_WORMHOLE) ||
-				(this->type == VEH_ROAD && RoadVehicle::From(this)->state == RVSB_WORMHOLE)));
+				(this->type == VEH_ROAD && RoadVehicle::From(this)->state == RVSB_WORMHOLE))));
 }
 
 /**