(svn r10197) -Codechange: replace int32 with CommandCost where appropriate.

45 files changed, 337 insertions, 331 deletions

diff --git a/src/ai/ai.cpp b/src/ai/ai.cpp
index 126d9fb89..ec8837f2c 100644
--- a/src/ai/ai.cpp
+++ b/src/ai/ai.cpp
@@ -81,10 +81,10 @@ static void AI_PutCommandInQueue(PlayerID player, TileIndex tile, uint32 p1, uin
 /**
  * Executes a raw DoCommand for the AI.
  */
-int32 AI_DoCommandCc(TileIndex tile, uint32 p1, uint32 p2, uint32 flags, uint procc, CommandCallback* callback)
+CommandCost AI_DoCommandCc(TileIndex tile, uint32 p1, uint32 p2, uint32 flags, uint procc, CommandCallback* callback)
 {
 	PlayerID old_lp;
-	int32 res = 0;
+	CommandCost res = 0;
 	const char* tmp_cmdtext;
 
 	/* If you enable DC_EXEC with DC_QUERY_COST you are a really strange
@@ -135,7 +135,7 @@ int32 AI_DoCommandCc(TileIndex tile, uint32 p1, uint32 p2, uint32 flags, uint pr
 }
 
 
-int32 AI_DoCommand(TileIndex tile, uint32 p1, uint32 p2, uint32 flags, uint procc)
+CommandCost AI_DoCommand(TileIndex tile, uint32 p1, uint32 p2, uint32 flags, uint procc)
 {
 	return AI_DoCommandCc(tile, p1, p2, flags, procc, NULL);
 }
diff --git a/src/ai/ai.h b/src/ai/ai.h
index 4e7c999a5..a0a4c5793 100644
--- a/src/ai/ai.h
+++ b/src/ai/ai.h
@@ -43,8 +43,8 @@ void AI_PlayerDied(PlayerID player);
 void AI_RunGameLoop();
 void AI_Initialize();
 void AI_Uninitialize();
-int32 AI_DoCommand(TileIndex tile, uint32 p1, uint32 p2, uint32 flags, uint procc);
-int32 AI_DoCommandCc(TileIndex tile, uint32 p1, uint32 p2, uint32 flags, uint procc, CommandCallback* callback);
+CommandCost AI_DoCommand(TileIndex tile, uint32 p1, uint32 p2, uint32 flags, uint procc);
+CommandCost AI_DoCommandCc(TileIndex tile, uint32 p1, uint32 p2, uint32 flags, uint procc, CommandCallback* callback);
 
 /** Is it allowed to start a new AI.
  * This function checks some boundries to see if we should launch a new AI.
diff --git a/src/ai/default/default.cpp b/src/ai/default/default.cpp
index d50da8ed8..83ae1e004 100644
--- a/src/ai/default/default.cpp
+++ b/src/ai/default/default.cpp
@@ -136,7 +136,7 @@ static EngineID AiChooseTrainToBuild(RailType railtype, int32 money, byte flag,
 {
 	EngineID best_veh_index = INVALID_ENGINE;
 	byte best_veh_score = 0;
-	int32 ret;
+	CommandCost ret;
 	EngineID i;
 
 	for (i = 0; i < NUM_TRAIN_ENGINES; i++) {
@@ -172,7 +172,7 @@ static EngineID AiChooseRoadVehToBuild(CargoID cargo, int32 money, TileIndex til
 		const RoadVehicleInfo *rvi = RoadVehInfo(i);
 		const Engine* e = GetEngine(i);
 		int32 rating;
-		int32 ret;
+		CommandCost ret;
 
 		if (!HASBIT(e->player_avail, _current_player) || e->reliability < 0x8A3D) {
 			continue;
@@ -207,7 +207,7 @@ static EngineID AiChooseAircraftToBuild(int32 money, byte flag)
 
 	for (i = AIRCRAFT_ENGINES_INDEX; i != AIRCRAFT_ENGINES_INDEX + NUM_AIRCRAFT_ENGINES; i++) {
 		const Engine* e = GetEngine(i);
-		int32 ret;
+		CommandCost ret;
 
 		if (!HASBIT(e->player_avail, _current_player) || e->reliability < 0x8A3D) {
 			continue;
@@ -1638,10 +1638,10 @@ static bool AiCheckTrackResources(TileIndex tile, const AiDefaultBlockData *p, b
 	return true;
 }
 
-static int32 AiDoBuildDefaultRailTrack(TileIndex tile, const AiDefaultBlockData* p, RailType railtype, byte flag)
+static CommandCost AiDoBuildDefaultRailTrack(TileIndex tile, const AiDefaultBlockData* p, RailType railtype, byte flag)
 {
-	int32 ret;
-	int32 total_cost = 0;
+	CommandCost ret;
+	CommandCost total_cost = 0;
 	Town *t = NULL;
 	int rating = 0;
 	int i, j, k;
@@ -1734,7 +1734,7 @@ clear_town_stuff:;
 }
 
 // Returns rule and cost
-static int AiBuildDefaultRailTrack(TileIndex tile, byte p0, byte p1, byte p2, byte p3, byte dir, byte cargo, RailType railtype, int32* cost)
+static int AiBuildDefaultRailTrack(TileIndex tile, byte p0, byte p1, byte p2, byte p3, byte dir, byte cargo, RailType railtype, CommandCost* cost)
 {
 	int i;
 	const AiDefaultRailBlock *p;
@@ -1821,7 +1821,7 @@ static void AiStateBuildDefaultRailBlocks(Player *p)
 	int j;
 	AiBuildRec *aib;
 	int rule;
-	int32 cost;
+	CommandCost cost;
 
 	// time out?
 	if (++p->ai.timeout_counter == 1388) {
@@ -2067,7 +2067,7 @@ static inline void AiCheckBuildRailTunnelHere(AiRailFinder *arf, TileIndex tile,
 	uint z;
 
 	if (GetTileSlope(tile, &z) == _dir_table_2[p[0] & 3] && z != 0) {
-		int32 cost = DoCommand(tile, arf->player->ai.railtype_to_use, 0, DC_AUTO, CMD_BUILD_TUNNEL);
+		CommandCost cost = DoCommand(tile, arf->player->ai.railtype_to_use, 0, DC_AUTO, CMD_BUILD_TUNNEL);
 
 		if (!CmdFailed(cost) && cost <= (arf->player->player_money >> 4)) {
 			AiBuildRailRecursive(arf, _build_tunnel_endtile, p[0] & 3);
@@ -2465,7 +2465,7 @@ static void AiStateBuildRailVeh(Player *p)
 	EngineID veh;
 	int i;
 	CargoID cargo;
-	int32 cost;
+	CommandCost cost;
 	Vehicle *v;
 	VehicleID loco_id;
 
@@ -2605,10 +2605,10 @@ static bool AiCheckRoadResources(TileIndex tile, const AiDefaultBlockData *p, by
 }
 
 static bool _want_road_truck_station;
-static int32 AiDoBuildDefaultRoadBlock(TileIndex tile, const AiDefaultBlockData *p, byte flag);
+static CommandCost AiDoBuildDefaultRoadBlock(TileIndex tile, const AiDefaultBlockData *p, byte flag);
 
 // Returns rule and cost
-static int AiFindBestDefaultRoadBlock(TileIndex tile, byte direction, byte cargo, int32 *cost)
+static int AiFindBestDefaultRoadBlock(TileIndex tile, byte direction, byte cargo, CommandCost *cost)
 {
 	int i;
 	const AiDefaultRoadBlock *p;
@@ -2626,10 +2626,10 @@ static int AiFindBestDefaultRoadBlock(TileIndex tile, byte direction, byte cargo
 	return -1;
 }
 
-static int32 AiDoBuildDefaultRoadBlock(TileIndex tile, const AiDefaultBlockData *p, byte flag)
+static CommandCost AiDoBuildDefaultRoadBlock(TileIndex tile, const AiDefaultBlockData *p, byte flag)
 {
-	int32 ret;
-	int32 total_cost = 0;
+	CommandCost ret;
+	CommandCost total_cost = 0;
 	Town *t = NULL;
 	int rating = 0;
 	int roadflag = 0;
@@ -2721,7 +2721,7 @@ static void AiStateBuildDefaultRoadBlocks(Player *p)
 	int j;
 	AiBuildRec *aib;
 	int rule;
-	int32 cost;
+	CommandCost cost;
 
 	// time out?
 	if (++p->ai.timeout_counter == 1388) {
@@ -2758,7 +2758,7 @@ static void AiStateBuildDefaultRoadBlocks(Player *p)
 					p->ai.state_mode = -p->ai.state_mode;
 				}
 			} else if (CheckPlayerHasMoney(cost) && AiCheckBlockDistances(p, aib->use_tile)) {
-				int32 r;
+				CommandCost r;
 
 				// player has money, build it.
 				aib->cur_building_rule = rule;
@@ -2967,7 +2967,7 @@ static inline void AiCheckBuildRoadTunnelHere(AiRoadFinder *arf, TileIndex tile,
 	uint z;
 
 	if (GetTileSlope(tile, &z) == _dir_table_2[p[0] & 3] && z != 0) {
-		int32 cost = DoCommand(tile, 0x200, 0, DC_AUTO, CMD_BUILD_TUNNEL);
+		CommandCost cost = DoCommand(tile, 0x200, 0, DC_AUTO, CMD_BUILD_TUNNEL);
 
 		if (!CmdFailed(cost) && cost <= (arf->player->player_money >> 4)) {
 			AiBuildRoadRecursive(arf, _build_tunnel_endtile, p[0] & 3);
@@ -3101,7 +3101,7 @@ do_some_terraform:
 		 */
 		for (i = 10; i != 0; i--) {
 			if (CheckBridge_Stuff(i, bridge_len)) {
-				int32 cost = DoCommand(tile, p->ai.cur_tile_a, i + ((0x80 | ROADTYPES_ROAD) << 8), DC_AUTO, CMD_BUILD_BRIDGE);
+				CommandCost cost = DoCommand(tile, p->ai.cur_tile_a, i + ((0x80 | ROADTYPES_ROAD) << 8), DC_AUTO, CMD_BUILD_BRIDGE);
 				if (!CmdFailed(cost) && cost < (p->player_money >> 5)) break;
 			}
 		}
@@ -3387,10 +3387,10 @@ static void AiStateAirportStuff(Player *p)
 	p->ai.state_counter = 0;
 }
 
-static int32 AiDoBuildDefaultAirportBlock(TileIndex tile, const AiDefaultBlockData *p, byte flag)
+static CommandCost AiDoBuildDefaultAirportBlock(TileIndex tile, const AiDefaultBlockData *p, byte flag)
 {
 	uint32 avail_airports = GetValidAirports();
-	int32 total_cost = 0, ret;
+	CommandCost total_cost = 0, ret;
 
 	for (; p->mode == 0; p++) {
 		if (!HASBIT(avail_airports, p->attr)) return CMD_ERROR;
@@ -3424,7 +3424,7 @@ static bool AiCheckAirportResources(TileIndex tile, const AiDefaultBlockData *p,
 	return true;
 }
 
-static int AiFindBestDefaultAirportBlock(TileIndex tile, byte cargo, byte heli, int32 *cost)
+static int AiFindBestDefaultAirportBlock(TileIndex tile, byte cargo, byte heli, CommandCost *cost)
 {
 	const AiDefaultBlockData *p;
 	uint i;
@@ -3446,7 +3446,7 @@ static void AiStateBuildDefaultAirportBlocks(Player *p)
 	int i, j;
 	AiBuildRec *aib;
 	int rule;
-	int32 cost;
+	CommandCost cost;
 
 	// time out?
 	if (++p->ai.timeout_counter == 1388) {
@@ -3485,7 +3485,7 @@ static void AiStateBuildDefaultAirportBlocks(Player *p)
 				}
 			} else if (CheckPlayerHasMoney(cost) && AiCheckBlockDistances(p, aib->use_tile)) {
 				// player has money, build it.
-				int32 r;
+				CommandCost r;
 
 				aib->cur_building_rule = rule;
 
diff --git a/src/ai/trolly/build.cpp b/src/ai/trolly/build.cpp
index ac66bfaa6..60518d0fa 100644
--- a/src/ai/trolly/build.cpp
+++ b/src/ai/trolly/build.cpp
@@ -36,7 +36,7 @@ bool AiNew_Build_CompanyHQ(Player *p, TileIndex tile)
 //    numtracks : in case of AI_TRAIN: tracks of station
 //    direction : the direction of the station
 //    flag : flag passed to DoCommand (normally 0 to get the cost or DC_EXEC to build it)
-int AiNew_Build_Station(Player *p, byte type, TileIndex tile, byte length, byte numtracks, byte direction, byte flag)
+CommandCost AiNew_Build_Station(Player *p, byte type, TileIndex tile, byte length, byte numtracks, byte direction, byte flag)
 {
 	if (type == AI_TRAIN)
 		return AI_DoCommand(tile, direction + (numtracks << 8) + (length << 16), 0, flag | DC_AUTO | DC_NO_WATER, CMD_BUILD_RAILROAD_STATION);
@@ -53,7 +53,7 @@ int AiNew_Build_Station(Player *p, byte type, TileIndex tile, byte length, byte
 //   tile_a : starting point
 //   tile_b : end point
 //   flag : flag passed to DoCommand
-int AiNew_Build_Bridge(Player *p, TileIndex tile_a, TileIndex tile_b, byte flag)
+CommandCost AiNew_Build_Bridge(Player *p, TileIndex tile_a, TileIndex tile_b, byte flag)
 {
 	int bridge_type, bridge_len, type, type2;
 
@@ -90,15 +90,15 @@ int AiNew_Build_Bridge(Player *p, TileIndex tile_a, TileIndex tile_b, byte flag)
 //   part : Which part we need to build
 //
 // TODO: skip already builded road-pieces (e.g.: cityroad)
-int AiNew_Build_RoutePart(Player *p, Ai_PathFinderInfo *PathFinderInfo, byte flag)
+CommandCost AiNew_Build_RoutePart(Player *p, Ai_PathFinderInfo *PathFinderInfo, byte flag)
 {
 	int part = PathFinderInfo->position;
 	byte *route_extra = PathFinderInfo->route_extra;
 	TileIndex *route = PathFinderInfo->route;
 	int dir;
 	int old_dir = -1;
-	int cost = 0;
-	int res;
+	CommandCost cost = 0;
+	CommandCost res;
 	// We need to calculate the direction with the parent of the parent.. so we skip
 	//  the first pieces and the last piece
 	if (part < 1) part = 1;
@@ -243,7 +243,7 @@ EngineID AiNew_PickVehicle(Player *p)
 			const RoadVehicleInfo *rvi = RoadVehInfo(i);
 			const Engine* e = GetEngine(i);
 			int32 rating;
-			int32 ret;
+			CommandCost ret;
 
 			/* Skip vehicles which can't take our cargo type */
 			if (rvi->cargo_type != p->ainew.cargo && !CanRefitTo(i, p->ainew.cargo)) continue;
@@ -293,7 +293,7 @@ void CcAI(bool success, TileIndex tile, uint32 p1, uint32 p2)
 
 
 // Builds the best vehicle possible
-int AiNew_Build_Vehicle(Player *p, TileIndex tile, byte flag)
+CommandCost AiNew_Build_Vehicle(Player *p, TileIndex tile, byte flag)
 {
 	EngineID i = AiNew_PickVehicle(p);
 
@@ -307,9 +307,9 @@ int AiNew_Build_Vehicle(Player *p, TileIndex tile, byte flag)
 	}
 }
 
-int AiNew_Build_Depot(Player* p, TileIndex tile, DiagDirection direction, byte flag)
+CommandCost AiNew_Build_Depot(Player* p, TileIndex tile, DiagDirection direction, byte flag)
 {
-	int ret, ret2;
+	CommandCost ret, ret2;
 	if (p->ainew.tbt == AI_TRAIN) {
 		return AI_DoCommand(tile, 0, direction, flag | DC_AUTO | DC_NO_WATER, CMD_BUILD_TRAIN_DEPOT);
 	} else {
diff --git a/src/ai/trolly/pathfinder.cpp b/src/ai/trolly/pathfinder.cpp
index d117f48dd..4fca513df 100644
--- a/src/ai/trolly/pathfinder.cpp
+++ b/src/ai/trolly/pathfinder.cpp
@@ -23,7 +23,7 @@ static bool TestCanBuildStationHere(TileIndex tile, byte dir)
 	Player *p = GetPlayer(_current_player);
 
 	if (dir == TEST_STATION_NO_DIR) {
-		int32 ret;
+		CommandCost ret;
 		// TODO: currently we only allow spots that can be access from al 4 directions...
 		//  should be fixed!!!
 		for (dir = 0; dir < 4; dir++) {
@@ -214,7 +214,7 @@ static void AyStar_AiPathFinder_FoundEndNode(AyStar *aystar, OpenListNode *curre
 // What tiles are around us.
 static void AyStar_AiPathFinder_GetNeighbours(AyStar *aystar, OpenListNode *current)
 {
-	int ret;
+	CommandCost ret;
 	int dir;
 
 	Ai_PathFinderInfo *PathFinderInfo = (Ai_PathFinderInfo*)aystar->user_target;
diff --git a/src/ai/trolly/trolly.cpp b/src/ai/trolly/trolly.cpp
index cd5ca16a5..dd274e2ed 100644
--- a/src/ai/trolly/trolly.cpp
+++ b/src/ai/trolly/trolly.cpp
@@ -642,7 +642,7 @@ static void AiNew_State_FindStation(Player *p)
 
 	if (new_tile == 0 && p->ainew.tbt == AI_BUS) {
 		uint x, y, i = 0;
-		int r;
+		CommandCost r;
 		uint best;
 		uint accepts[NUM_CARGO];
 		TileIndex found_spot[AI_FINDSTATION_TILE_RANGE*AI_FINDSTATION_TILE_RANGE * 4];
@@ -788,7 +788,8 @@ static void AiNew_State_FindDepot(Player *p)
 	// To make the depot stand in the middle of the route, we start from the center..
 	// But first we walk through the route see if we can find a depot that is ours
 	//  this keeps things nice ;)
-	int g, i, r;
+	int g, i;
+	CommandCost r;
 	DiagDirection j;
 	TileIndex tile;
 	assert(p->ainew.state == AI_STATE_FIND_DEPOT);
@@ -984,7 +985,7 @@ static void AiNew_State_VerifyRoute(Player *p)
 // Build the stations
 static void AiNew_State_BuildStation(Player *p)
 {
-	int res = 0;
+	CommandCost res = 0;
 	assert(p->ainew.state == AI_STATE_BUILD_STATION);
 	if (p->ainew.temp == 0) {
 		if (!IsTileType(p->ainew.from_tile, MP_STATION))
@@ -1037,8 +1038,8 @@ static void AiNew_State_BuildPath(Player *p)
 			// We don't want that, so try building some road left or right of the station
 			int dir1, dir2, dir3;
 			TileIndex tile;
-			int i, ret;
-			for (i=0;i<2;i++) {
+			CommandCost ret;
+			for (int i = 0; i < 2; i++) {
 				if (i == 0) {
 					tile = p->ainew.from_tile + TileOffsByDiagDir(p->ainew.from_direction);
 					dir1 = p->ainew.from_direction - 1;
@@ -1102,7 +1103,7 @@ static void AiNew_State_BuildPath(Player *p)
 // Builds the depot
 static void AiNew_State_BuildDepot(Player *p)
 {
-	int res = 0;
+	CommandCost res = 0;
 	assert(p->ainew.state == AI_STATE_BUILD_DEPOT);
 
 	if (IsTileType(p->ainew.depot_tile, MP_STREET) && GetRoadTileType(p->ainew.depot_tile) == ROAD_TILE_DEPOT) {
@@ -1137,7 +1138,7 @@ static void AiNew_State_BuildDepot(Player *p)
 // Build vehicles
 static void AiNew_State_BuildVehicle(Player *p)
 {
-	int res;
+	CommandCost res;
 	assert(p->ainew.state == AI_STATE_BUILD_VEHICLE);
 
 	// Check if we need to build a vehicle
@@ -1277,7 +1278,7 @@ static void AiNew_CheckVehicle(Player *p, Vehicle *v)
 
 			if (!AiNew_SetSpecialVehicleFlag(p, v, AI_VEHICLEFLAG_SELL)) return;
 			{
-				int ret = 0;
+				CommandCost ret = 0;
 				if (v->type == VEH_ROAD)
 					ret = AI_DoCommand(0, v->index, 0, DC_EXEC, CMD_SEND_ROADVEH_TO_DEPOT);
 				// This means we can not find a depot :s
diff --git a/src/ai/trolly/trolly.h b/src/ai/trolly/trolly.h
index e0d70fbf6..52bad9aa1 100644
--- a/src/ai/trolly/trolly.h
+++ b/src/ai/trolly/trolly.h
@@ -252,11 +252,11 @@ uint AiNew_GetSpecialVehicleFlag(Player *p, Vehicle *v);
 
 // ai_build.c
 bool AiNew_Build_CompanyHQ(Player *p, TileIndex tile);
-int AiNew_Build_Station(Player *p, byte type, TileIndex tile, byte length, byte numtracks, byte direction, byte flag);
-int AiNew_Build_Bridge(Player *p, TileIndex tile_a, TileIndex tile_b, byte flag);
-int AiNew_Build_RoutePart(Player *p, Ai_PathFinderInfo *PathFinderInfo, byte flag);
+CommandCost AiNew_Build_Station(Player *p, byte type, TileIndex tile, byte length, byte numtracks, byte direction, byte flag);
+CommandCost AiNew_Build_Bridge(Player *p, TileIndex tile_a, TileIndex tile_b, byte flag);
+CommandCost AiNew_Build_RoutePart(Player *p, Ai_PathFinderInfo *PathFinderInfo, byte flag);
 EngineID AiNew_PickVehicle(Player *p);
-int AiNew_Build_Vehicle(Player *p, TileIndex tile, byte flag);
-int AiNew_Build_Depot(Player* p, TileIndex tile, DiagDirection direction, byte flag);
+CommandCost AiNew_Build_Vehicle(Player *p, TileIndex tile, byte flag);
+CommandCost AiNew_Build_Depot(Player* p, TileIndex tile, DiagDirection direction, byte flag);
 
 #endif /* AI_TROLLY_H */
diff --git a/src/aircraft_cmd.cpp b/src/aircraft_cmd.cpp
index 90192e023..de5c27ea1 100644
--- a/src/aircraft_cmd.cpp
+++ b/src/aircraft_cmd.cpp
@@ -227,7 +227,7 @@ void GetAircraftSpriteSize(EngineID engine, uint &width, uint &height)
 	height = spr->height;
 }
 
-static int32 EstimateAircraftCost(EngineID engine, const AircraftVehicleInfo *avi)
+static CommandCost EstimateAircraftCost(EngineID engine, const AircraftVehicleInfo *avi)
 {
 	return GetEngineProperty(engine, 0x0B, avi->base_cost) * (_price.aircraft_base >> 3) >> 5;
 }
@@ -265,12 +265,12 @@ uint16 AircraftDefaultCargoCapacity(CargoID cid, const AircraftVehicleInfo *avi)
  * @param p2 bit 0 when set, the unitnumber will be 0, otherwise it will be a free number
  * return result of operation.  Could be cost, error
  */
-int32 CmdBuildAircraft(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdBuildAircraft(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	if (!IsEngineBuildable(p1, VEH_AIRCRAFT, _current_player)) return_cmd_error(STR_AIRCRAFT_NOT_AVAILABLE);
 
 	const AircraftVehicleInfo *avi = AircraftVehInfo(p1);
-	int32 value = EstimateAircraftCost(p1, avi);
+	CommandCost value = EstimateAircraftCost(p1, avi);
 
 	/* to just query the cost, it is not neccessary to have a valid tile (automation/AI) */
 	if (flags & DC_QUERY_COST) return value;
@@ -476,7 +476,7 @@ static void DoDeleteAircraft(Vehicle *v)
  * @param p2 unused
  * @return result of operation.  Error or sold value
  */
-int32 CmdSellAircraft(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdSellAircraft(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	if (!IsValidVehicleID(p1)) return CMD_ERROR;
 
@@ -503,7 +503,7 @@ int32 CmdSellAircraft(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * @param p2 unused
  * @return result of operation.  Nothing if everything went well
  */
-int32 CmdStartStopAircraft(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdStartStopAircraft(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	if (!IsValidVehicleID(p1)) return CMD_ERROR;
 
@@ -546,7 +546,7 @@ int32 CmdStartStopAircraft(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * - p2 bit 8-10 - VLW flag (for mass goto depot)
  * @return o if everything went well
  */
-int32 CmdSendAircraftToHangar(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdSendAircraftToHangar(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	if (p2 & DEPOT_MASS_SEND) {
 		/* Mass goto depot requested */
@@ -623,7 +623,7 @@ int32 CmdSendAircraftToHangar(TileIndex tile, uint32 flags, uint32 p1, uint32 p2
  * - p2 = (bit 16) - refit only this vehicle (ignored)
  * @return cost of refit or error
  */
-int32 CmdRefitAircraft(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdRefitAircraft(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	byte new_subtype = GB(p2, 8, 8);
 
@@ -668,7 +668,7 @@ int32 CmdRefitAircraft(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 	}
 	_returned_refit_capacity = pass;
 
-	int32 cost = 0;
+	CommandCost cost = 0;
 	if (IsHumanPlayer(v->owner) && new_cid != v->cargo_type) {
 		cost = GetRefitCost(v->engine_type);
 	}
@@ -744,7 +744,7 @@ void OnNewDay_Aircraft(Vehicle *v)
 
 	if (v->vehstatus & VS_STOPPED) return;
 
-	int32 cost = GetVehicleProperty(v, 0x0E, AircraftVehInfo(v->engine_type)->running_cost) * _price.aircraft_running / 364;
+	CommandCost cost = GetVehicleProperty(v, 0x0E, AircraftVehInfo(v->engine_type)->running_cost) * _price.aircraft_running / 364;
 
 	v->profit_this_year -= cost >> 8;
 
@@ -1379,7 +1379,7 @@ static void ProcessAircraftOrder(Vehicle *v)
 		 */
 		const Station *st = GetStation(v->u.air.targetairport);
 		if (!st->IsValid() || st->airport_tile == 0) {
-			int32 ret;
+			CommandCost ret;
 			PlayerID old_player = _current_player;
 
 			_current_player = v->owner;
diff --git a/src/autoreplace_cmd.cpp b/src/autoreplace_cmd.cpp
index a906274aa..4a69e17fa 100644
--- a/src/autoreplace_cmd.cpp
+++ b/src/autoreplace_cmd.cpp
@@ -124,10 +124,10 @@ static CargoID GetNewCargoTypeForReplace(Vehicle *v, EngineID engine_type)
  * @param flags is the flags to use when calling DoCommand(). Mainly DC_EXEC counts
  * @return value is cost of the replacement or CMD_ERROR
  */
-static int32 ReplaceVehicle(Vehicle **w, byte flags, int32 total_cost)
+static CommandCost ReplaceVehicle(Vehicle **w, byte flags, int32 total_cost)
 {
-	int32 cost;
-	int32 sell_value;
+	CommandCost cost;
+	CommandCost sell_value;
 	Vehicle *old_v = *w;
 	const Player *p = GetPlayer(old_v->owner);
 	EngineID new_engine_type;
@@ -173,7 +173,7 @@ static int32 ReplaceVehicle(Vehicle **w, byte flags, int32 total_cost)
 
 	if (replacement_cargo_type != CT_NO_REFIT) {
 		/* add refit cost */
-		int32 refit_cost = GetRefitCost(new_engine_type);
+		CommandCost refit_cost = GetRefitCost(new_engine_type);
 		if (old_v->type == VEH_TRAIN && IsMultiheaded(old_v)) refit_cost += refit_cost; // pay for both ends
 		cost += refit_cost;
 	}
@@ -246,7 +246,7 @@ static int32 ReplaceVehicle(Vehicle **w, byte flags, int32 total_cost)
 			GetName(vehicle_name, old_v->string_id & 0x7FF, lastof(vehicle_name));
 		}
 	} else { // flags & DC_EXEC not set
-		int32 tmp_move = 0;
+		CommandCost tmp_move = 0;
 		if (old_v->type == VEH_TRAIN && IsFrontEngine(old_v) && old_v->next != NULL) {
 			/* Verify that the wagons can be placed on the engine in question.
 			 * This is done by building an engine, test if the wagons can be added and then sell the test engine. */
@@ -295,12 +295,12 @@ static int32 ReplaceVehicle(Vehicle **w, byte flags, int32 total_cost)
  * @param display_costs If set, a cost animation is shown (only if check is false)
  * @return CMD_ERROR if something went wrong. Otherwise the price of the replace
  */
-int32 MaybeReplaceVehicle(Vehicle *v, bool check, bool display_costs)
+CommandCost MaybeReplaceVehicle(Vehicle *v, bool check, bool display_costs)
 {
 	Vehicle *w;
 	const Player *p = GetPlayer(v->owner);
 	byte flags = 0;
-	int32 cost, temp_cost = 0;
+	CommandCost cost, temp_cost = 0;
 	bool stopped;
 
 	/* Remember the length in case we need to trim train later on
diff --git a/src/bridge_gui.cpp b/src/bridge_gui.cpp
index 64934dd79..b78f4ddd8 100644
--- a/src/bridge_gui.cpp
+++ b/src/bridge_gui.cpp
@@ -113,7 +113,7 @@ static const WindowDesc _build_road_bridge_desc = {
 void ShowBuildBridgeWindow(TileIndex start, TileIndex end, byte bridge_type)
 {
 	uint j = 0;
-	int32 ret;
+	CommandCost ret;
 	StringID errmsg;
 
 	DeleteWindowById(WC_BUILD_BRIDGE, 0);
diff --git a/src/clear_cmd.cpp b/src/clear_cmd.cpp
index f2ed0df81..d7a077c8a 100644
--- a/src/clear_cmd.cpp
+++ b/src/clear_cmd.cpp
@@ -36,7 +36,7 @@ struct TerraformerState {
 	int modheight_count;
 	int tile_table_count;
 
-	int32 cost;
+	CommandCost cost;
 
 	TileIndex *tile_table;
 	TerraformerHeightMod *modheight;
@@ -97,7 +97,7 @@ static void TerraformAddDirtyTileAround(TerraformerState *ts, TileIndex tile)
 static int TerraformProc(TerraformerState *ts, TileIndex tile, int mode)
 {
 	int r;
-	int32 ret;
+	CommandCost ret;
 
 	assert(tile < MapSize());
 
@@ -232,7 +232,7 @@ static bool TerraformTileHeight(TerraformerState *ts, TileIndex tile, int height
  * @param p2 direction; eg up or down
  * @return error or cost of terraforming
  */
-int32 CmdTerraformLand(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdTerraformLand(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	TerraformerState ts;
 	TileIndex t;
@@ -357,14 +357,16 @@ int32 CmdTerraformLand(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * @param p2 unused
  * @return  error or cost of terraforming
  */
-int32 CmdLevelLand(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdLevelLand(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	int size_x, size_y;
 	int ex;
 	int ey;
 	int sx, sy;
 	uint h, curh;
-	int32 ret, cost, money;
+	int32 money;
+	CommandCost ret;
+	CommandCost cost;
 
 	if (p1 >= MapSize()) return CMD_ERROR;
 
@@ -418,9 +420,9 @@ int32 CmdLevelLand(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * @param p2 unused
  * @return error of cost of operation
  */
-int32 CmdPurchaseLandArea(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdPurchaseLandArea(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
-	int32 cost;
+	CommandCost cost;
 
 	SET_EXPENSES_TYPE(EXPENSES_CONSTRUCTION);
 
@@ -442,7 +444,7 @@ int32 CmdPurchaseLandArea(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 }
 
 
-static int32 ClearTile_Clear(TileIndex tile, byte flags)
+static CommandCost ClearTile_Clear(TileIndex tile, byte flags)
 {
 	static const int32* clear_price_table[] = {
 		&_price.clear_1,
@@ -453,7 +455,7 @@ static int32 ClearTile_Clear(TileIndex tile, byte flags)
 		&_price.purchase_land,
 		&_price.clear_2, // XXX unused?
 	};
-	int32 price;
+	CommandCost price;
 
 	if (IsClearGround(tile, CLEAR_GRASS) && GetClearDensity(tile) == 0) {
 		price = 0;
@@ -474,7 +476,7 @@ static int32 ClearTile_Clear(TileIndex tile, byte flags)
  * @param p2 unused
  * @return error or cost of operation
  */
-int32 CmdSellLandArea(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdSellLandArea(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	SET_EXPENSES_TYPE(EXPENSES_CONSTRUCTION);
 
diff --git a/src/command.cpp b/src/command.cpp
index 2b6946852..210aaadf6 100644
--- a/src/command.cpp
+++ b/src/command.cpp
@@ -17,7 +17,7 @@
 
 const char* _cmd_text = NULL;
 
-#define DEF_COMMAND(yyyy) int32 yyyy(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+#define DEF_COMMAND(yyyy) CommandCost yyyy(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 
 DEF_COMMAND(CmdBuildRailroadTrack);
 DEF_COMMAND(CmdRemoveRailroadTrack);
@@ -351,9 +351,9 @@ byte GetCommandFlags(uint cmd)
 
 static int _docommand_recursive;
 
-int32 DoCommand(TileIndex tile, uint32 p1, uint32 p2, uint32 flags, uint procc)
+CommandCost DoCommand(TileIndex tile, uint32 p1, uint32 p2, uint32 flags, uint procc)
 {
-	int32 res;
+	CommandCost res;
 	CommandProc *proc;
 
 	/* Do not even think about executing out-of-bounds tile-commands */
@@ -425,7 +425,7 @@ int32 GetAvailableMoneyForCommand()
  * the callback is called when the command succeeded or failed. */
 bool DoCommandP(TileIndex tile, uint32 p1, uint32 p2, CommandCallback *callback, uint32 cmd)
 {
-	int32 res = 0, res2;
+	CommandCost res = 0, res2;
 	CommandProc *proc;
 	uint32 flags;
 	bool notest;
diff --git a/src/command.h b/src/command.h
index d13638d2d..428dd32d6 100644
--- a/src/command.h
+++ b/src/command.h
@@ -184,7 +184,7 @@ enum {
 	CMD_OFFLINE = 0x2, ///< the command cannot be executed in a multiplayer game; single-player only
 };
 
-typedef int32 CommandProc(TileIndex tile, uint32 flags, uint32 p1, uint32 p2);
+typedef CommandCost CommandProc(TileIndex tile, uint32 flags, uint32 p1, uint32 p2);
 
 struct Command {
 	CommandProc *proc;
@@ -199,7 +199,7 @@ struct Command {
  * @param res the resulting value from the command to be checked
  * @return Return true if the command failed, false otherwise
  */
-static inline bool CmdFailed(int32 res)
+static inline bool CmdFailed(CommandCost res)
 {
 	/* lower 16bits are the StringID of the possible error */
 	return res <= (CMD_ERROR | INVALID_STRING_ID);
@@ -207,7 +207,7 @@ static inline bool CmdFailed(int32 res)
 
 /* command.cpp */
 typedef void CommandCallback(bool success, TileIndex tile, uint32 p1, uint32 p2);
-int32 DoCommand(TileIndex tile, uint32 p1, uint32 p2, uint32 flags, uint procc);
+CommandCost DoCommand(TileIndex tile, uint32 p1, uint32 p2, uint32 flags, uint procc);
 bool DoCommandP(TileIndex tile, uint32 p1, uint32 p2, CommandCallback *callback, uint32 cmd);
 
 #ifdef ENABLE_NETWORK
diff --git a/src/dummy_land.cpp b/src/dummy_land.cpp
index 8395f170d..8ad015f34 100644
--- a/src/dummy_land.cpp
+++ b/src/dummy_land.cpp
@@ -26,7 +26,7 @@ static Slope GetSlopeTileh_Dummy(TileIndex tile, Slope tileh)
 	return SLOPE_FLAT;
 }
 
-static int32 ClearTile_Dummy(TileIndex tile, byte flags)
+static CommandCost ClearTile_Dummy(TileIndex tile, byte flags)
 {
 	return_cmd_error(STR_0001_OFF_EDGE_OF_MAP);
 }
diff --git a/src/economy.cpp b/src/economy.cpp
index 47ee5c883..fd7d4babd 100644
--- a/src/economy.cpp
+++ b/src/economy.cpp
@@ -259,7 +259,7 @@ void ChangeOwnershipOfPlayerItems(PlayerID old_player, PlayerID new_player)
 			for (i = 0; i < 4; i++) {
 				if (p->share_owners[i] == old_player) {
 					/* Sell his shares */
-					int32 res = DoCommand(0, p->index, 0, DC_EXEC, CMD_SELL_SHARE_IN_COMPANY);
+					CommandCost res = DoCommand(0, p->index, 0, DC_EXEC, CMD_SELL_SHARE_IN_COMPANY);
 					/* Because we are in a DoCommand, we can't just execute an other one and
 					 *  expect the money to be removed. We need to do it ourself! */
 					SubtractMoneyFromPlayer(res);
@@ -273,7 +273,7 @@ void ChangeOwnershipOfPlayerItems(PlayerID old_player, PlayerID new_player)
 			_current_player = p->share_owners[i];
 			if (_current_player != PLAYER_SPECTATOR) {
 				/* Sell the shares */
-				int32 res = DoCommand(0, old_player, 0, DC_EXEC, CMD_SELL_SHARE_IN_COMPANY);
+				CommandCost res = DoCommand(0, old_player, 0, DC_EXEC, CMD_SELL_SHARE_IN_COMPANY);
 				/* Because we are in a DoCommand, we can't just execute an other one and
 				 *  expect the money to be removed. We need to do it ourself! */
 				SubtractMoneyFromPlayer(res);
@@ -1808,10 +1808,10 @@ extern int GetAmountOwnedBy(const Player *p, PlayerID owner);
  * @param p1 player to buy the shares from
  * @param p2 unused
  */
-int32 CmdBuyShareInCompany(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdBuyShareInCompany(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Player *p;
-	int64 cost;
+	CommandCost cost;
 
 	/* Check if buying shares is allowed (protection against modified clients */
 	if (!IsValidPlayer((PlayerID)p1) || !_patches.allow_shares) return CMD_ERROR;
@@ -1854,7 +1854,7 @@ int32 CmdBuyShareInCompany(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * @param p1 player to sell the shares from
  * @param p2 unused
  */
-int32 CmdSellShareInCompany(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdSellShareInCompany(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Player *p;
 	int64 cost;
@@ -1890,7 +1890,7 @@ int32 CmdSellShareInCompany(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * @param p1 player/company to buy up
  * @param p2 unused
  */
-int32 CmdBuyCompany(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdBuyCompany(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Player *p;
 	PlayerID pid = (PlayerID)p1;
diff --git a/src/engine.cpp b/src/engine.cpp
index 80b07adca..e0e3fd430 100644
--- a/src/engine.cpp
+++ b/src/engine.cpp
@@ -266,7 +266,7 @@ void EnginesDailyLoop()
  * @param p1 engine-prototype offered
  * @param p2 unused
  */
-int32 CmdWantEnginePreview(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdWantEnginePreview(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Engine *e;
 
@@ -374,7 +374,7 @@ void EnginesMonthlyLoop()
  * @param p1 engine ID to rename
  * @param p2 unused
  */
-int32 CmdRenameEngine(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdRenameEngine(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	StringID str;
 
@@ -533,7 +533,7 @@ EngineID EngineReplacement(EngineRenewList erl, EngineID engine, GroupID group)
 	return er == NULL ? INVALID_ENGINE : er->to;
 }
 
-int32 AddEngineReplacement(EngineRenewList *erl, EngineID old_engine, EngineID new_engine, GroupID group, uint32 flags)
+CommandCost AddEngineReplacement(EngineRenewList *erl, EngineID old_engine, EngineID new_engine, GroupID group, uint32 flags)
 {
 	EngineRenew *er;
 
@@ -560,7 +560,7 @@ int32 AddEngineReplacement(EngineRenewList *erl, EngineID old_engine, EngineID n
 	return 0;
 }
 
-int32 RemoveEngineReplacement(EngineRenewList *erl, EngineID engine, GroupID group, uint32 flags)
+CommandCost RemoveEngineReplacement(EngineRenewList *erl, EngineID engine, GroupID group, uint32 flags)
 {
 	EngineRenew *er = (EngineRenew *)(*erl);
 	EngineRenew *prev = NULL;
diff --git a/src/engine.h b/src/engine.h
index 95d4fd338..be0a7c87e 100644
--- a/src/engine.h
+++ b/src/engine.h
@@ -328,7 +328,7 @@ EngineID EngineReplacement(EngineRenewList erl, EngineID engine, GroupID group);
  * @param flags The calling command flags.
  * @return 0 on success, CMD_ERROR on failure.
  */
-int32 AddEngineReplacement(EngineRenewList* erl, EngineID old_engine, EngineID new_engine, GroupID group, uint32 flags);
+CommandCost AddEngineReplacement(EngineRenewList* erl, EngineID old_engine, EngineID new_engine, GroupID group, uint32 flags);
 
 /**
  * Remove an engine replacement from a given renewlist.
@@ -337,7 +337,7 @@ int32 AddEngineReplacement(EngineRenewList* erl, EngineID old_engine, EngineID n
  * @param flags The calling command flags.
  * @return 0 on success, CMD_ERROR on failure.
  */
-int32 RemoveEngineReplacement(EngineRenewList* erl, EngineID engine, GroupID group, uint32 flags);
+CommandCost RemoveEngineReplacement(EngineRenewList* erl, EngineID engine, GroupID group, uint32 flags);
 
 /** When an engine is made buildable or is removed from being buildable, add/remove it from the build/autoreplace lists
  * @param type The type of engine
diff --git a/src/functions.h b/src/functions.h
index cc885917e..9edddce4b 100644
--- a/src/functions.h
+++ b/src/functions.h
@@ -20,9 +20,9 @@ void DrawShipDepotSprite(int x, int y, int image);
 void TileLoop_Water(TileIndex tile);
 
 /* players.cpp */
-bool CheckPlayerHasMoney(int32 cost);
-void SubtractMoneyFromPlayer(int32 cost);
-void SubtractMoneyFromPlayerFract(PlayerID player, int32 cost);
+bool CheckPlayerHasMoney(CommandCost cost);
+void SubtractMoneyFromPlayer(CommandCost cost);
+void SubtractMoneyFromPlayerFract(PlayerID player, CommandCost cost);
 bool CheckOwnership(Owner owner);
 bool CheckTileOwnership(TileIndex tile);
 StringID GetPlayerNameString(PlayerID player, uint index);
diff --git a/src/group_cmd.cpp b/src/group_cmd.cpp
index 41f28af57..49ebfb35c 100644
--- a/src/group_cmd.cpp
+++ b/src/group_cmd.cpp
@@ -93,7 +93,7 @@ static WindowClass GetWCForVT(VehicleType vt)
  * @param p1   vehicle type
  * @param p2   unused
  */
-int32 CmdCreateGroup(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdCreateGroup(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	VehicleType vt = (VehicleType)p1;
 	if (!IsPlayerBuildableVehicleType(vt)) return CMD_ERROR;
@@ -121,7 +121,7 @@ int32 CmdCreateGroup(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  *      - p1 bit 0-15 : GroupID
  * @param p2   unused
  */
-int32 CmdDeleteGroup(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdDeleteGroup(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	if (!IsValidGroupID(p1)) return CMD_ERROR;
 
@@ -167,7 +167,7 @@ int32 CmdDeleteGroup(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  *   - p1 bit 0-15 : GroupID
  * @param p2   unused
  */
-int32 CmdRenameGroup(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdRenameGroup(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	if (!IsValidGroupID(p1) || StrEmpty(_cmd_text)) return CMD_ERROR;
 
@@ -199,7 +199,7 @@ int32 CmdRenameGroup(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * @param p2   vehicle to add to a group
  *   - p2 bit 0-15 : VehicleID
  */
-int32 CmdAddVehicleGroup(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdAddVehicleGroup(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	GroupID new_g = p1;
 
@@ -245,7 +245,7 @@ int32 CmdAddVehicleGroup(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  *  - p1 bit 0-15 : GroupID
  * @param p2   type of vehicles
  */
-int32 CmdAddSharedVehicleGroup(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdAddSharedVehicleGroup(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	VehicleType type = (VehicleType)p2;
 	if (!IsValidGroupID(p1) || !IsPlayerBuildableVehicleType(type)) return CMD_ERROR;
@@ -282,7 +282,7 @@ int32 CmdAddSharedVehicleGroup(TileIndex tile, uint32 flags, uint32 p1, uint32 p
  * - p1 bit 0-15 : GroupID
  * @param p2   type of vehicles
  */
-int32 CmdRemoveAllVehiclesGroup(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdRemoveAllVehiclesGroup(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	VehicleType type = (VehicleType)p2;
 	if (!IsValidGroupID(p1) || !IsPlayerBuildableVehicleType(type)) return CMD_ERROR;
@@ -319,7 +319,7 @@ int32 CmdRemoveAllVehiclesGroup(TileIndex tile, uint32 flags, uint32 p1, uint32
  * @param p2
  * - p2 bit 0    : 1 to set or 0 to clear protection.
  */
-int32 CmdSetGroupReplaceProtection(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdSetGroupReplaceProtection(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	if (!IsValidGroupID(p1)) return CMD_ERROR;
 
diff --git a/src/industry_cmd.cpp b/src/industry_cmd.cpp
index 1c4de08b5..808270af5 100644
--- a/src/industry_cmd.cpp
+++ b/src/industry_cmd.cpp
@@ -336,7 +336,7 @@ static void GetTileDesc_Industry(TileIndex tile, TileDesc *td)
 	}
 }
 
-static int32 ClearTile_Industry(TileIndex tile, byte flags)
+static CommandCost ClearTile_Industry(TileIndex tile, byte flags)
 {
 	Industry *i = GetIndustryByTile(tile);
 	const IndustrySpec *indspec = GetIndustrySpec(i->type);
@@ -1469,7 +1469,7 @@ static Industry *CreateNewIndustryHelper(TileIndex tile, IndustryType type, uint
  * @param p2 unused
  * @return index of the newly create industry, or CMD_ERROR if it failed
  */
-int32 CmdBuildIndustry(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdBuildIndustry(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	int num;
 	const IndustryTileTable * const *itt;
diff --git a/src/landscape.cpp b/src/landscape.cpp
index 167709c52..07b7ca4b6 100644
--- a/src/landscape.cpp
+++ b/src/landscape.cpp
@@ -367,7 +367,7 @@ void ClearSnowLine(void)
  * @param p1 unused
  * @param p2 unused
  */
-int32 CmdLandscapeClear(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdLandscapeClear(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	SET_EXPENSES_TYPE(EXPENSES_CONSTRUCTION);
 
@@ -380,9 +380,9 @@ int32 CmdLandscapeClear(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * @param flags of operation to conduct
  * @param p2 unused
  */
-int32 CmdClearArea(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdClearArea(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
-	int32 cost, ret, money;
+	CommandCost cost, ret, money;
 	int ex;
 	int ey;
 	int sx, sy;
diff --git a/src/misc_cmd.cpp b/src/misc_cmd.cpp
index 4d3d5ae6f..11635f1b8 100644
--- a/src/misc_cmd.cpp
+++ b/src/misc_cmd.cpp
@@ -24,7 +24,7 @@
  * @param p1 unused
  * @param p2 face bitmasked
  */
-int32 CmdSetPlayerFace(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdSetPlayerFace(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	PlayerFace pf = (PlayerFace)p2;
 
@@ -45,7 +45,7 @@ int32 CmdSetPlayerFace(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * p1 bits 8-9 set in use state or first/second colour
  * @param p2 new colour for vehicles, property, etc.
  */
-int32 CmdSetPlayerColor(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdSetPlayerColor(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Player *p, *pp;
 	byte colour;
@@ -124,7 +124,7 @@ int32 CmdSetPlayerColor(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * @param p2 when 0: loans LOAN_INTERVAL
  *           when 1: loans the maximum loan permitting money (press CTRL),
  */
-int32 CmdIncreaseLoan(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdIncreaseLoan(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Player *p = GetPlayer(_current_player);
 
@@ -161,7 +161,7 @@ int32 CmdIncreaseLoan(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * @param p2 when 0: pays back LOAN_INTERVAL
  *           when 1: pays back the maximum loan permitting money (press CTRL),
  */
-int32 CmdDecreaseLoan(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdDecreaseLoan(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Player *p = GetPlayer(_current_player);
 
@@ -199,7 +199,7 @@ int32 CmdDecreaseLoan(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * @param p1 unused
  * @param p2 unused
  */
-int32 CmdChangeCompanyName(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdChangeCompanyName(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	StringID str;
 	Player *p;
@@ -227,7 +227,7 @@ int32 CmdChangeCompanyName(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * @param p1 unused
  * @param p2 unused
  */
-int32 CmdChangePresidentName(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdChangePresidentName(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	StringID str;
 	Player *p;
@@ -266,7 +266,7 @@ int32 CmdChangePresidentName(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * @param p1 0 = decrease pause counter; 1 = increase pause counter
  * @param p2 unused
  */
-int32 CmdPause(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdPause(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	if (flags & DC_EXEC) {
 		_pause_game += (p1 == 1) ? 1 : -1;
@@ -285,7 +285,7 @@ int32 CmdPause(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * @param p1 the amount of money to receive (if negative), or spend (if positive)
  * @param p2 unused
  */
-int32 CmdMoneyCheat(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdMoneyCheat(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 #ifndef _DEBUG
 	if (_networking) return CMD_ERROR;
@@ -303,10 +303,10 @@ int32 CmdMoneyCheat(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * @param p1 the amount of money to transfer; max 20.000.000
  * @param p2 the player to transfer the money to
  */
-int32 CmdGiveMoney(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdGiveMoney(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	const Player *p = GetPlayer(_current_player);
-	int32 amount = min((int32)p1, 20000000);
+	CommandCost amount = min((int32)p1, 20000000);
 
 	SET_EXPENSES_TYPE(EXPENSES_OTHER);
 
@@ -336,7 +336,7 @@ int32 CmdGiveMoney(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  *           itself is changed. The new value is inside p2
  * @param p2 new value for a difficulty setting or difficulty level
  */
-int32 CmdChangeDifficultyLevel(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdChangeDifficultyLevel(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	if (p1 != (uint32)-1L && ((int32)p1 >= GAME_DIFFICULTY_NUM || (int32)p1 < 0)) return CMD_ERROR;
 
diff --git a/src/openttd.h b/src/openttd.h
index 69df7c271..6969f1c23 100644
--- a/src/openttd.h
+++ b/src/openttd.h
@@ -67,6 +67,7 @@ typedef uint16 SignID;
 typedef uint16 GroupID;
 typedef uint16 EngineRenewID;
 typedef uint16 DestinationID;
+typedef int32 CommandCost;
 
 /* DestinationID must be at least as large as every these below, because it can
  * be any of them
diff --git a/src/order_cmd.cpp b/src/order_cmd.cpp
index 34cfd0a5c..986987da8 100644
--- a/src/order_cmd.cpp
+++ b/src/order_cmd.cpp
@@ -190,7 +190,7 @@ static TileIndex GetOrderLocation(const Order& o)
  *                        only the first 8 bits used currently (bit 16 - 23) (max 255)
  * @param p2 packed order to insert
  */
-int32 CmdInsertOrder(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdInsertOrder(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Vehicle *v;
 	VehicleID veh   = GB(p1,  0, 16);
@@ -448,7 +448,7 @@ int32 CmdInsertOrder(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * @param *dst delete the orders of this vehicle
  * @param flags execution flags
  */
-static int32 DecloneOrder(Vehicle *dst, uint32 flags)
+static CommandCost DecloneOrder(Vehicle *dst, uint32 flags)
 {
 	if (flags & DC_EXEC) {
 		DeleteVehicleOrders(dst);
@@ -483,7 +483,7 @@ static void RemoveSharedOrderVehicleList(Vehicle *v)
  * @param p1 the ID of the vehicle
  * @param p2 the order to delete (max 255)
  */
-int32 CmdDeleteOrder(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdDeleteOrder(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Vehicle *v, *u;
 	VehicleID veh_id = p1;
@@ -563,7 +563,7 @@ int32 CmdDeleteOrder(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * @param p1 The ID of the vehicle which order is skipped
  * @param p2 the selected order to which we want to skip
  */
-int32 CmdSkipToOrder(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdSkipToOrder(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Vehicle *v;
 	VehicleID veh_id = p1;
@@ -608,7 +608,7 @@ int32 CmdSkipToOrder(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * @note The target order will move one place down in the orderlist
  *  if you move the order upwards else it'll move it one place down
  */
-int32 CmdMoveOrder(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdMoveOrder(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	VehicleID veh = p1;
 	VehicleOrderID moving_order = GB(p2,  0, 16);
@@ -694,7 +694,7 @@ int32 CmdMoveOrder(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  *                        only the first 8 bits used currently (bit 16 - 23) (max 255)
  * @param p2 mode to change the order to (always set)
  */
-int32 CmdModifyOrder(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdModifyOrder(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Vehicle *v;
 	Order *order;
@@ -774,7 +774,7 @@ int32 CmdModifyOrder(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * - p1 = (bit 16-31) - source vehicle to clone orders from, if any (none for CO_UNSHARE)
  * @param p2 mode of cloning: CO_SHARE, CO_COPY, or CO_UNSHARE
  */
-int32 CmdCloneOrder(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdCloneOrder(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Vehicle *dst;
 	VehicleID veh_src = GB(p1, 16, 16);
@@ -908,7 +908,7 @@ int32 CmdCloneOrder(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  *   - bit 8-15 Cargo subtype
  *   - bit 16-23 number of order to modify
  */
-int32 CmdOrderRefit(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdOrderRefit(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	const Vehicle *v;
 	Order *order;
@@ -1039,7 +1039,7 @@ void RestoreVehicleOrders(const Vehicle* v, const BackuppedOrders* bak)
  * If we do want to backup/restore it, just add UnitID uid to BackuppedOrders, and
  * restore it as parameter 'y' (ugly hack I know) for example. "v->unitnumber = y;"
  */
-int32 CmdRestoreOrderIndex(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdRestoreOrderIndex(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Vehicle *v;
 	VehicleOrderID cur_ord = GB(p2,  0, 16);
diff --git a/src/player.h b/src/player.h
index d6857aa3f..faccd94bf 100644
--- a/src/player.h
+++ b/src/player.h
@@ -337,7 +337,7 @@ static inline bool EngineHasReplacementForPlayer(const Player *p, EngineID engin
  * @param flags The calling command flags.
  * @return 0 on success, CMD_ERROR on failure.
  */
-static inline int32 AddEngineReplacementForPlayer(Player *p, EngineID old_engine, EngineID new_engine, GroupID group, uint32 flags) { return AddEngineReplacement(&p->engine_renew_list, old_engine, new_engine, group, flags); }
+static inline CommandCost AddEngineReplacementForPlayer(Player *p, EngineID old_engine, EngineID new_engine, GroupID group, uint32 flags) { return AddEngineReplacement(&p->engine_renew_list, old_engine, new_engine, group, flags); }
 
 /**
  * Remove an engine replacement for the player.
@@ -346,7 +346,7 @@ static inline int32 AddEngineReplacementForPlayer(Player *p, EngineID old_engine
  * @param flags The calling command flags.
  * @return 0 on success, CMD_ERROR on failure.
  */
-static inline int32 RemoveEngineReplacementForPlayer(Player *p, EngineID engine, GroupID group, uint32 flags) {return RemoveEngineReplacement(&p->engine_renew_list, engine, group, flags); }
+static inline CommandCost RemoveEngineReplacementForPlayer(Player *p, EngineID engine, GroupID group, uint32 flags) {return RemoveEngineReplacement(&p->engine_renew_list, engine, group, flags); }
 
 /**
  * Reset the livery schemes to the player's primary colour.
diff --git a/src/players.cpp b/src/players.cpp
index 3a71b4d08..293a3243b 100644
--- a/src/players.cpp
+++ b/src/players.cpp
@@ -173,7 +173,7 @@ void InvalidatePlayerWindows(const Player *p)
 	InvalidateWindow(WC_FINANCES, pid);
 }
 
-bool CheckPlayerHasMoney(int32 cost)
+bool CheckPlayerHasMoney(CommandCost cost)
 {
 	if (cost > 0) {
 		PlayerID pid = _current_player;
@@ -186,7 +186,7 @@ bool CheckPlayerHasMoney(int32 cost)
 	return true;
 }
 
-static void SubtractMoneyFromAnyPlayer(Player *p, int32 cost)
+static void SubtractMoneyFromAnyPlayer(Player *p, CommandCost cost)
 {
 	p->money64 -= cost;
 	UpdatePlayerMoney32(p);
@@ -210,14 +210,14 @@ static void SubtractMoneyFromAnyPlayer(Player *p, int32 cost)
 	InvalidatePlayerWindows(p);
 }
 
-void SubtractMoneyFromPlayer(int32 cost)
+void SubtractMoneyFromPlayer(CommandCost cost)
 {
 	PlayerID pid = _current_player;
 
 	if (IsValidPlayer(pid)) SubtractMoneyFromAnyPlayer(GetPlayer(pid), cost);
 }
 
-void SubtractMoneyFromPlayerFract(PlayerID player, int32 cost)
+void SubtractMoneyFromPlayerFract(PlayerID player, CommandCost cost)
 {
 	Player *p = GetPlayer(player);
 	byte m = p->player_money_fraction;
@@ -676,7 +676,7 @@ static void DeletePlayerStuff(PlayerID pi)
  * if p1 = 5, then
  * - p2 = enable renew_keep_length
  */
-int32 CmdSetAutoReplace(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdSetAutoReplace(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Player *p;
 	if (!IsValidPlayer(_current_player)) return CMD_ERROR;
@@ -723,7 +723,7 @@ int32 CmdSetAutoReplace(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 			EngineID old_engine_type = GB(p2, 0, 16);
 			EngineID new_engine_type = GB(p2, 16, 16);
 			GroupID id_g = GB(p1, 16, 16);
-			int32 cost;
+			CommandCost cost;
 
 			if (!IsValidGroupID(id_g) && !IsDefaultGroupID(id_g)) return CMD_ERROR;
 			if (new_engine_type != INVALID_ENGINE) {
@@ -805,7 +805,7 @@ int32 CmdSetAutoReplace(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * @arg - network_server.c:838 DEF_SERVER_RECEIVE_COMMAND(PACKET_CLIENT_COMMAND)@n
  * @arg - network_client.c:536 DEF_CLIENT_RECEIVE_COMMAND(PACKET_SERVER_MAP) from where the map has been received
  */
-int32 CmdPlayerCtrl(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdPlayerCtrl(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	if (flags & DC_EXEC) _current_player = OWNER_NONE;
 
diff --git a/src/rail_cmd.cpp b/src/rail_cmd.cpp
index 16d95eaeb..8e54cafd2 100644
--- a/src/rail_cmd.cpp
+++ b/src/rail_cmd.cpp
@@ -189,7 +189,7 @@ uint GetRailFoundation(Slope tileh, TrackBits bits)
 }
 
 
-static uint32 CheckRailSlope(Slope tileh, TrackBits rail_bits, TrackBits existing, TileIndex tile)
+static CommandCost CheckRailSlope(Slope tileh, TrackBits rail_bits, TrackBits existing, TileIndex tile)
 {
 	if (IsSteepSlope(tileh)) {
 		if (_patches.build_on_slopes && existing == 0) {
@@ -231,14 +231,14 @@ static inline bool ValParamTrackOrientation(Track track) {return IsValidTrack(tr
  * @param p1 railtype of being built piece (normal, mono, maglev)
  * @param p2 rail track to build
  */
-int32 CmdBuildSingleRail(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdBuildSingleRail(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Slope tileh;
 	RailType railtype;
 	Track track;
 	TrackBits trackbit;
-	int32 cost = 0;
-	int32 ret;
+	CommandCost cost = 0;
+	CommandCost ret;
 
 	if (!ValParamRailtype(p1) || !ValParamTrackOrientation((Track)p2)) return CMD_ERROR;
 	railtype = (RailType)p1;
@@ -355,11 +355,11 @@ int32 CmdBuildSingleRail(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * @param p1 unused
  * @param p2 rail orientation
  */
-int32 CmdRemoveSingleRail(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdRemoveSingleRail(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Track track = (Track)p2;
 	TrackBits trackbit;
-	int32 cost = _price.remove_rail;
+	CommandCost cost = _price.remove_rail;
 	bool crossing = false;
 
 	if (!ValParamTrackOrientation((Track)p2)) return CMD_ERROR;
@@ -444,7 +444,7 @@ static const TileIndexDiffC _trackdelta[] = {
 };
 
 
-static int32 ValidateAutoDrag(Trackdir *trackdir, TileIndex start, TileIndex end)
+static CommandCost ValidateAutoDrag(Trackdir *trackdir, TileIndex start, TileIndex end)
 {
 	int x = TileX(start);
 	int y = TileY(start);
@@ -504,9 +504,9 @@ static int32 ValidateAutoDrag(Trackdir *trackdir, TileIndex start, TileIndex end
  * - p2 = (bit 4-6) - track-orientation, valid values: 0-5 (Track enum)
  * - p2 = (bit 7)   - 0 = build, 1 = remove tracks
  */
-static int32 CmdRailTrackHelper(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+static CommandCost CmdRailTrackHelper(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
-	int32 ret, total_cost = 0;
+	CommandCost ret, total_cost = 0;
 	Track track = (Track)GB(p2, 4, 3);
 	Trackdir trackdir;
 	byte mode = HASBIT(p2, 7);
@@ -556,7 +556,7 @@ static int32 CmdRailTrackHelper(TileIndex tile, uint32 flags, uint32 p1, uint32
  * - p2 = (bit 7)   - 0 = build, 1 = remove tracks
  * @see CmdRailTrackHelper
  */
-int32 CmdBuildRailroadTrack(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdBuildRailroadTrack(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	return CmdRailTrackHelper(tile, flags, p1, CLRBIT(p2, 7));
 }
@@ -572,7 +572,7 @@ int32 CmdBuildRailroadTrack(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * - p2 = (bit 7)   - 0 = build, 1 = remove tracks
  * @see CmdRailTrackHelper
  */
-int32 CmdRemoveRailroadTrack(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdRemoveRailroadTrack(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	return CmdRailTrackHelper(tile, flags, p1, SETBIT(p2, 7));
 }
@@ -586,10 +586,10 @@ int32 CmdRemoveRailroadTrack(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * @todo When checking for the tile slope,
  * distingush between "Flat land required" and "land sloped in wrong direction"
  */
-int32 CmdBuildTrainDepot(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdBuildTrainDepot(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Depot *d;
-	int32 cost, ret;
+	CommandCost cost, ret;
 	Slope tileh;
 
 	SET_EXPENSES_TYPE(EXPENSES_CONSTRUCTION);
@@ -653,12 +653,12 @@ int32 CmdBuildTrainDepot(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * @param p2 used for CmdBuildManySignals() to copy direction of first signal
  * TODO: p2 should be replaced by two bits for "along" and "against" the track.
  */
-int32 CmdBuildSingleSignal(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdBuildSingleSignal(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Track track = (Track)GB(p1, 0, 3);
 	bool pre_signal = HASBIT(p1, 3);
 	SignalVariant sigvar = (pre_signal ^ HASBIT(p1, 4)) ? SIG_SEMAPHORE : SIG_ELECTRIC;
-	int32 cost;
+	CommandCost cost;
 
 	if (!ValParamTrackOrientation(track) || !IsTileType(tile, MP_RAILWAY) || !EnsureNoVehicleOnGround(tile))
 		return CMD_ERROR;
@@ -750,9 +750,10 @@ int32 CmdBuildSingleSignal(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * - p2 = (bit  5)    - 0 = build, 1 = remove signals
  * - p2 = (bit 24-31) - user defined signals_density
  */
-static int32 CmdSignalTrackHelper(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+static CommandCost CmdSignalTrackHelper(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
-	int32 ret, total_cost, signal_ctr;
+	CommandCost ret, total_cost;
+	int signal_ctr;
 	byte signals;
 	bool error = true;
 	TileIndex end_tile;
@@ -840,7 +841,7 @@ static int32 CmdSignalTrackHelper(TileIndex tile, uint32 flags, uint32 p1, uint3
  * - p2 = (bit 24-31) - user defined signals_density
  * @see CmdSignalTrackHelper
  */
-int32 CmdBuildSignalTrack(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdBuildSignalTrack(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	return CmdSignalTrackHelper(tile, flags, p1, p2);
 }
@@ -854,7 +855,7 @@ int32 CmdBuildSignalTrack(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  *           - (bit  4)    - 0 = signals, 1 = semaphores
  * @param p2 unused
  */
-int32 CmdRemoveSingleSignal(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdRemoveSingleSignal(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Track track = (Track)GB(p1, 0, 3);
 
@@ -903,12 +904,12 @@ int32 CmdRemoveSingleSignal(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * - p2 = (bit 24-31) - user defined signals_density
  * @see CmdSignalTrackHelper
  */
-int32 CmdRemoveSignalTrack(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdRemoveSignalTrack(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	return CmdSignalTrackHelper(tile, flags, p1, SETBIT(p2, 5)); // bit 5 is remove bit
 }
 
-typedef int32 DoConvertRailProc(TileIndex tile, RailType totype, bool exec);
+typedef CommandCost DoConvertRailProc(TileIndex tile, RailType totype, bool exec);
 
 /**
  * Switches the rail type.
@@ -920,7 +921,7 @@ typedef int32 DoConvertRailProc(TileIndex tile, RailType totype, bool exec);
  * @return            The cost and state of the operation
  * @retval CMD_ERROR  An error occured during the operation.
  */
-static int32 DoConvertRail(TileIndex tile, RailType totype, bool exec)
+static CommandCost DoConvertRail(TileIndex tile, RailType totype, bool exec)
 {
 	if (!CheckTileOwnership(tile)) return CMD_ERROR;
 
@@ -960,9 +961,9 @@ static int32 DoConvertRail(TileIndex tile, RailType totype, bool exec)
 	return _price.build_rail / 2;
 }
 
-extern int32 DoConvertStationRail(TileIndex tile, RailType totype, bool exec);
-extern int32 DoConvertStreetRail(TileIndex tile, RailType totype, bool exec);
-extern int32 DoConvertTunnelBridgeRail(TileIndex tile, RailType totype, bool exec);
+extern CommandCost DoConvertStationRail(TileIndex tile, RailType totype, bool exec);
+extern CommandCost DoConvertStreetRail(TileIndex tile, RailType totype, bool exec);
+extern CommandCost DoConvertTunnelBridgeRail(TileIndex tile, RailType totype, bool exec);
 
 /** Convert one rail type to the other. You can convert normal rail to
  * monorail/maglev easily or vice-versa.
@@ -971,9 +972,10 @@ extern int32 DoConvertTunnelBridgeRail(TileIndex tile, RailType totype, bool exe
  * @param p1 start tile of drag
  * @param p2 new railtype to convert to
  */
-int32 CmdConvertRail(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdConvertRail(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
-	int32 ret, cost, money;
+	CommandCost ret, cost;
+	int32 money;
 	int ex;
 	int ey;
 	int sx, sy, x, y;
@@ -1026,7 +1028,7 @@ int32 CmdConvertRail(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 	return (cost == 0) ? ret : cost;
 }
 
-static int32 RemoveTrainDepot(TileIndex tile, uint32 flags)
+static CommandCost RemoveTrainDepot(TileIndex tile, uint32 flags)
 {
 	if (!CheckTileOwnership(tile) && _current_player != OWNER_WATER)
 		return CMD_ERROR;
@@ -1045,10 +1047,10 @@ static int32 RemoveTrainDepot(TileIndex tile, uint32 flags)
 	return _price.remove_train_depot;
 }
 
-static int32 ClearTile_Track(TileIndex tile, byte flags)
+static CommandCost ClearTile_Track(TileIndex tile, byte flags)
 {
-	int32 cost;
-	int32 ret;
+	CommandCost cost;
+	CommandCost ret;
 
 	if (flags & DC_AUTO) {
 		if (!IsTileOwner(tile, _current_player))
diff --git a/src/road_cmd.cpp b/src/road_cmd.cpp
index 48c9ef3a9..7f29577e6 100644
--- a/src/road_cmd.cpp
+++ b/src/road_cmd.cpp
@@ -107,7 +107,7 @@ static bool CheckAllowRemoveRoad(TileIndex tile, RoadBits remove, bool *edge_roa
  *                    removing the tram bits before the test.
  * @param p2 unused
  */
-int32 CmdRemoveRoad(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdRemoveRoad(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	/* cost for removing inner/edge -roads */
 	static const uint16 road_remove_cost[2] = {50, 18};
@@ -166,7 +166,7 @@ int32 CmdRemoveRoad(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 		/* If it's the last roadtype, just clear the whole tile */
 		if (rts == RoadTypeToRoadTypes(rt)) return DoCommand(tile, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
 
-		int32 cost;
+		CommandCost cost;
 		if (IsTileType(tile, MP_TUNNELBRIDGE)) {
 			TileIndex other_end = IsTunnel(tile) ? GetOtherTunnelEnd(tile) : GetOtherBridgeEnd(tile);
 			/* Pay for *every* tile of the bridge or tunnel */
@@ -301,7 +301,7 @@ static const RoadBits _valid_tileh_slopes_road[][15] = {
 };
 
 
-static uint32 CheckRoadSlope(Slope tileh, RoadBits* pieces, RoadBits existing)
+static CommandCost CheckRoadSlope(Slope tileh, RoadBits* pieces, RoadBits existing)
 {
 	RoadBits road_bits;
 
@@ -346,10 +346,10 @@ static uint32 CheckRoadSlope(Slope tileh, RoadBits* pieces, RoadBits existing)
  *           bit 6..7 disallowed directions to toggle
  * @param p2 the town that is building the road (0 if not applicable)
  */
-int32 CmdBuildRoad(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdBuildRoad(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
-	int32 cost = 0;
-	int32 ret;
+	CommandCost cost = 0;
+	CommandCost ret;
 	RoadBits existing = ROAD_NONE;
 	RoadBits all_bits = ROAD_NONE;
 	Slope tileh;
@@ -553,7 +553,7 @@ do_clear:;
  * @return            The cost and state of the operation
  * @retval CMD_ERROR  An error occured during the operation.
  */
-int32 DoConvertStreetRail(TileIndex tile, RailType totype, bool exec)
+CommandCost DoConvertStreetRail(TileIndex tile, RailType totype, bool exec)
 {
 	/* not a railroad crossing? */
 	if (!IsLevelCrossing(tile)) return CMD_ERROR;
@@ -587,10 +587,10 @@ int32 DoConvertStreetRail(TileIndex tile, RailType totype, bool exec)
  * - p2 = (bit 3 + 4) - road type
  * - p2 = (bit 5) - set road direction
  */
-int32 CmdBuildLongRoad(TileIndex end_tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdBuildLongRoad(TileIndex end_tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	TileIndex start_tile, tile;
-	int32 cost, ret;
+	CommandCost cost, ret;
 	bool had_bridge = false;
 	bool had_success = false;
 	DisallowedRoadDirections drd = DRD_NORTHBOUND;
@@ -667,10 +667,10 @@ int32 CmdBuildLongRoad(TileIndex end_tile, uint32 flags, uint32 p1, uint32 p2)
  * - p2 = (bit 2) - direction: 0 = along x-axis, 1 = along y-axis (p2 & 4)
  * - p2 = (bit 3 + 4) - road type
  */
-int32 CmdRemoveLongRoad(TileIndex end_tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdRemoveLongRoad(TileIndex end_tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	TileIndex start_tile, tile;
-	int32 cost, ret;
+	CommandCost cost, ret;
 
 	SET_EXPENSES_TYPE(EXPENSES_CONSTRUCTION);
 
@@ -725,9 +725,9 @@ int32 CmdRemoveLongRoad(TileIndex end_tile, uint32 flags, uint32 p1, uint32 p2)
  * @todo When checking for the tile slope,
  * distingush between "Flat land required" and "land sloped in wrong direction"
  */
-int32 CmdBuildRoadDepot(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdBuildRoadDepot(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
-	int32 cost;
+	CommandCost cost;
 	Depot *dep;
 	Slope tileh;
 
@@ -765,7 +765,7 @@ int32 CmdBuildRoadDepot(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 	return cost + _price.build_road_depot;
 }
 
-static int32 RemoveRoadDepot(TileIndex tile, uint32 flags)
+static CommandCost RemoveRoadDepot(TileIndex tile, uint32 flags)
 {
 	if (!CheckTileOwnership(tile) && _current_player != OWNER_WATER)
 		return CMD_ERROR;
@@ -777,7 +777,7 @@ static int32 RemoveRoadDepot(TileIndex tile, uint32 flags)
 	return _price.remove_road_depot;
 }
 
-static int32 ClearTile_Road(TileIndex tile, byte flags)
+static CommandCost ClearTile_Road(TileIndex tile, byte flags)
 {
 	switch (GetRoadTileType(tile)) {
 		case ROAD_TILE_NORMAL: {
@@ -791,10 +791,10 @@ static int32 ClearTile_Road(TileIndex tile, byte flags)
 			    !(flags & DC_AUTO)
 				) {
 				RoadTypes rts = GetRoadTypes(tile);
-				int32 ret = 0;
+				CommandCost ret = 0;
 				for (RoadType rt = ROADTYPE_ROAD; rt < ROADTYPE_END; rt++) {
 					if (HASBIT(rts, rt)) {
-						int32 tmp_ret = DoCommand(tile, rt << 4 | GetRoadBits(tile, rt), 0, flags, CMD_REMOVE_ROAD);
+						CommandCost tmp_ret = DoCommand(tile, rt << 4 | GetRoadBits(tile, rt), 0, flags, CMD_REMOVE_ROAD);
 						if (CmdFailed(tmp_ret)) return tmp_ret;
 						ret += tmp_ret;
 					}
@@ -807,7 +807,7 @@ static int32 ClearTile_Road(TileIndex tile, byte flags)
 
 		case ROAD_TILE_CROSSING: {
 			RoadTypes rts = GetRoadTypes(tile);
-			int32 ret = 0;
+			CommandCost ret = 0;
 
 			if (flags & DC_AUTO) return_cmd_error(STR_1801_MUST_REMOVE_ROAD_FIRST);
 
@@ -815,7 +815,7 @@ static int32 ClearTile_Road(TileIndex tile, byte flags)
 			 * tram tracks must be removed before the road bits. */
 			for (RoadType rt = ROADTYPE_HWAY; rt >= ROADTYPE_ROAD; rt--) {
 				if (HASBIT(rts, rt)) {
-					int32 tmp_ret = DoCommand(tile, 1 << 6 | rt << 4 | GetCrossingRoadBits(tile), 0, flags, CMD_REMOVE_ROAD);
+					CommandCost tmp_ret = DoCommand(tile, 1 << 6 | rt << 4 | GetCrossingRoadBits(tile), 0, flags, CMD_REMOVE_ROAD);
 					if (CmdFailed(tmp_ret)) return tmp_ret;
 					ret += tmp_ret;
 				}
diff --git a/src/roadveh_cmd.cpp b/src/roadveh_cmd.cpp
index 5c5e4023b..e3aacdc38 100644
--- a/src/roadveh_cmd.cpp
+++ b/src/roadveh_cmd.cpp
@@ -116,7 +116,7 @@ void DrawRoadVehEngine(int x, int y, EngineID engine, SpriteID pal)
 	DrawSprite(6 + _roadveh_images[spritenum], pal, x, y);
 }
 
-static int32 EstimateRoadVehCost(EngineID engine_type)
+static CommandCost EstimateRoadVehCost(EngineID engine_type)
 {
 	return ((_price.roadveh_base >> 3) * GetEngineProperty(engine_type, 0x11, RoadVehInfo(engine_type)->base_cost)) >> 5;
 }
@@ -156,9 +156,9 @@ void RoadVehUpdateCache(Vehicle *v)
  * @param p1 bus/truck type being built (engine)
  * @param p2 bit 0 when set, the unitnumber will be 0, otherwise it will be a free number
  */
-int32 CmdBuildRoadVeh(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdBuildRoadVeh(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
-	int32 cost;
+	CommandCost cost;
 	Vehicle *v;
 	UnitID unit_num;
 	Engine *e;
@@ -282,7 +282,7 @@ int32 CmdBuildRoadVeh(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * @param p1 road vehicle ID to start/stop
  * @param p2 unused
  */
-int32 CmdStartStopRoadVeh(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdStartStopRoadVeh(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Vehicle *v;
 	uint16 callback;
@@ -347,7 +347,7 @@ static bool CheckRoadVehInDepotStopped(const Vehicle *v)
  * @param p1 vehicle ID to be sold
  * @param p2 unused
  */
-int32 CmdSellRoadVeh(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdSellRoadVeh(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Vehicle *v;
 
@@ -447,7 +447,7 @@ static const Depot* FindClosestRoadDepot(const Vehicle* v)
  * - p2 bit 0-3 - DEPOT_ flags (see vehicle.h)
  * - p2 bit 8-10 - VLW flag (for mass goto depot)
  */
-int32 CmdSendRoadVehToDepot(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdSendRoadVehToDepot(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Vehicle *v;
 	const Depot *dep;
@@ -520,7 +520,7 @@ int32 CmdSendRoadVehToDepot(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * @param p1 vehicle ID to turn
  * @param p2 unused
  */
-int32 CmdTurnRoadVeh(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdTurnRoadVeh(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Vehicle *v;
 
@@ -1886,7 +1886,7 @@ static void CheckIfRoadVehNeedsService(Vehicle *v)
 
 void OnNewDay_RoadVeh(Vehicle *v)
 {
-	int32 cost;
+	CommandCost cost;
 
 	if (!IsRoadVehFront(v)) return;
 
@@ -2001,10 +2001,10 @@ void RoadVehiclesYearlyLoop()
  * - p2 = (bit 16) - refit only this vehicle (ignored)
  * @return cost of refit or error
  */
-int32 CmdRefitRoadVeh(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdRefitRoadVeh(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Vehicle *v;
-	int32 cost;
+	CommandCost cost;
 	CargoID new_cid = GB(p2, 0, 8);
 	byte new_subtype = GB(p2, 8, 8);
 	uint16 capacity = CALLBACK_FAILED;
diff --git a/src/settings.cpp b/src/settings.cpp
index 4b7452ac3..e258b55cc 100644
--- a/src/settings.cpp
+++ b/src/settings.cpp
@@ -1766,7 +1766,7 @@ static const SettingDesc *GetSettingDescription(uint index)
  * The new value is properly clamped to its minimum/maximum when setting
  * @see _patch_settings
  */
-int32 CmdChangePatchSetting(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdChangePatchSetting(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	const SettingDesc *sd = GetSettingDescription(p1);
 
diff --git a/src/settings_gui.cpp b/src/settings_gui.cpp
index ceb8e1a07..07a155d8c 100644
--- a/src/settings_gui.cpp
+++ b/src/settings_gui.cpp
@@ -251,7 +251,7 @@ static void GameOptionsWndProc(Window *w, WindowEvent *e)
  * @param p1 the side of the road; 0 = left side and 1 = right side
  * @param p2 unused
  */
-int32 CmdSetRoadDriveSide(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdSetRoadDriveSide(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	/* Check boundaries and you can only change this if NO vehicles have been built yet,
 	 * except in the intro-menu where of course it's always possible to do so. */
diff --git a/src/ship_cmd.cpp b/src/ship_cmd.cpp
index dd5675800..9a3927887 100644
--- a/src/ship_cmd.cpp
+++ b/src/ship_cmd.cpp
@@ -175,7 +175,7 @@ static void CheckIfShipNeedsService(Vehicle *v)
 
 void OnNewDay_Ship(Vehicle *v)
 {
-	int32 cost;
+	CommandCost cost;
 
 	if ((++v->day_counter & 7) == 0)
 		DecreaseVehicleValue(v);
@@ -403,9 +403,9 @@ static bool ShipAccelerate(Vehicle *v)
 	return (t < v->progress);
 }
 
-static int32 EstimateShipCost(EngineID engine_type)
+static CommandCost EstimateShipCost(EngineID engine_type)
 {
-	return GetEngineProperty(engine_type, 0x0A, ShipVehInfo(engine_type)->base_cost) * (_price.ship_base>>3)>>5;
+	return GetEngineProperty(engine_type, 0x0A, ShipVehInfo(engine_type)->base_cost) * (_price.ship_base >> 3) >> 5;
 }
 
 static void ShipArrivesAt(const Vehicle* v, Station* st)
@@ -809,9 +809,9 @@ void ShipsYearlyLoop()
  * @param p1 ship type being built (engine)
  * @param p2 bit 0 when set, the unitnumber will be 0, otherwise it will be a free number
  */
-int32 CmdBuildShip(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdBuildShip(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
-	int32 value;
+	CommandCost value;
 	Vehicle *v;
 	UnitID unit_num;
 	Engine *e;
@@ -904,7 +904,7 @@ int32 CmdBuildShip(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * @param p1 vehicle ID to be sold
  * @param p2 unused
  */
-int32 CmdSellShip(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdSellShip(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Vehicle *v;
 
@@ -938,7 +938,7 @@ int32 CmdSellShip(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * @param p1 ship ID to start/stop
  * @param p2 unused
  */
-int32 CmdStartStopShip(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdStartStopShip(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Vehicle *v;
 	uint16 callback;
@@ -979,7 +979,7 @@ int32 CmdStartStopShip(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * - p2 bit 0-3 - DEPOT_ flags (see vehicle.h)
  * - p2 bit 8-10 - VLW flag (for mass goto depot)
  */
-int32 CmdSendShipToDepot(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdSendShipToDepot(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Vehicle *v;
 	const Depot *dep;
@@ -1056,10 +1056,10 @@ int32 CmdSendShipToDepot(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * - p2 = (bit 16) - refit only this vehicle (ignored)
  * @return cost of refit or error
  */
-int32 CmdRefitShip(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdRefitShip(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Vehicle *v;
-	int32 cost;
+	CommandCost cost;
 	CargoID new_cid = GB(p2, 0, 8); //gets the cargo number
 	byte new_subtype = GB(p2, 8, 8);
 	uint16 capacity = CALLBACK_FAILED;
diff --git a/src/signs.cpp b/src/signs.cpp
index 8f3f0f365..5ac30dae9 100644
--- a/src/signs.cpp
+++ b/src/signs.cpp
@@ -122,7 +122,7 @@ void DestroySign(Sign *si)
  * @param p1 unused
  * @param p2 unused
  */
-int32 CmdPlaceSign(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdPlaceSign(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Sign *si;
 
@@ -159,7 +159,7 @@ int32 CmdPlaceSign(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * @param p2 unused
  * @return 0 if succesfull, otherwise CMD_ERROR
  */
-int32 CmdRenameSign(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdRenameSign(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	if (!IsValidSignID(p1)) return CMD_ERROR;
 
diff --git a/src/station_cmd.cpp b/src/station_cmd.cpp
index 08ebbe58c..9cb7f7131 100644
--- a/src/station_cmd.cpp
+++ b/src/station_cmd.cpp
@@ -612,13 +612,13 @@ static void DeleteStationIfEmpty(Station* st)
 	UpdateStationSignCoord(st);
 }
 
-static int32 ClearTile_Station(TileIndex tile, byte flags);
+static CommandCost ClearTile_Station(TileIndex tile, byte flags);
 
 // Tries to clear the given area. Returns the cost in case of success.
 // Or an error code if it failed.
-int32 CheckFlatLandBelow(TileIndex tile, uint w, uint h, uint flags, uint invalid_dirs, StationID* station, bool check_clear = true)
+CommandCost CheckFlatLandBelow(TileIndex tile, uint w, uint h, uint flags, uint invalid_dirs, StationID* station, bool check_clear = true)
 {
-	int32 cost = 0;
+	CommandCost cost = 0;
 	int allowed_z = -1;
 
 	BEGIN_TILE_LOOP(tile_cur, w, h, tile) {
@@ -680,7 +680,7 @@ int32 CheckFlatLandBelow(TileIndex tile, uint w, uint h, uint flags, uint invali
 				}
 			}
 		} else if (check_clear) {
-			int32 ret = DoCommand(tile_cur, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
+			CommandCost ret = DoCommand(tile_cur, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
 			if (CmdFailed(ret)) return ret;
 			cost += ret;
 		}
@@ -801,10 +801,10 @@ static void GetStationLayout(byte *layout, int numtracks, int plat_len, const St
  * - p2 = (bit  8-15) - custom station class
  * - p2 = (bit 16-23) - custom station id
  */
-int32 CmdBuildRailroadStation(TileIndex tile_org, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdBuildRailroadStation(TileIndex tile_org, uint32 flags, uint32 p1, uint32 p2)
 {
 	int w_org, h_org;
-	int32 ret;
+	CommandCost ret;
 
 	SET_EXPENSES_TYPE(EXPENSES_CONSTRUCTION);
 
@@ -838,7 +838,7 @@ int32 CmdBuildRailroadStation(TileIndex tile_org, uint32 flags, uint32 p1, uint3
 	//  for detail info, see: https://sourceforge.net/tracker/index.php?func=detail&aid=1029064&group_id=103924&atid=636365
 	ret = CheckFlatLandBelow(tile_org, w_org, h_org, flags & ~DC_EXEC, 5 << axis, _patches.nonuniform_stations ? &est : NULL);
 	if (CmdFailed(ret)) return ret;
-	int32 cost = ret + (numtracks * _price.train_station_track + _price.train_station_length) * plat_len;
+	CommandCost cost = ret + (numtracks * _price.train_station_track + _price.train_station_length) * plat_len;
 
 	Station *st = NULL;
 	bool check_surrounding = true;
@@ -1054,7 +1054,7 @@ restart:
  * @param p1 start_tile
  * @param p2 unused
  */
-int32 CmdRemoveFromRailroadStation(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdRemoveFromRailroadStation(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	TileIndex start = p1 == 0 ? tile : p1;
 
@@ -1125,7 +1125,7 @@ int32 CmdRemoveFromRailroadStation(TileIndex tile, uint32 flags, uint32 p1, uint
 }
 
 
-static int32 RemoveRailroadStation(Station *st, TileIndex tile, uint32 flags)
+static CommandCost RemoveRailroadStation(Station *st, TileIndex tile, uint32 flags)
 {
 	/* if there is flooding and non-uniform stations are enabled, remove platforms tile by tile */
 	if (_current_player == OWNER_WATER && _patches.nonuniform_stations)
@@ -1142,7 +1142,7 @@ static int32 RemoveRailroadStation(Station *st, TileIndex tile, uint32 flags)
 
 	assert(w != 0 && h != 0);
 
-	int32 cost = 0;
+	CommandCost cost = 0;
 	/* clear all areas of the station */
 	do {
 		int w_bak = w;
@@ -1191,7 +1191,7 @@ static int32 RemoveRailroadStation(Station *st, TileIndex tile, uint32 flags)
  * @return            The cost and state of the operation
  * @retval CMD_ERROR  An error occured during the operation.
  */
-int32 DoConvertStationRail(TileIndex tile, RailType totype, bool exec)
+CommandCost DoConvertStationRail(TileIndex tile, RailType totype, bool exec)
 {
 	const Station* st = GetStationByTile(tile);
 
@@ -1243,7 +1243,7 @@ static RoadStop **FindRoadStopSpot(bool truck_station, Station* st)
  *           bit 2..4: the roadtypes
  *           bit 5: allow stations directly adjacent to other stations.
  */
-int32 CmdBuildRoadStop(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdBuildRoadStop(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	bool type = HASBIT(p2, 0);
 	bool is_drive_through = HASBIT(p2, 1);
@@ -1267,7 +1267,7 @@ int32 CmdBuildRoadStop(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 
 	if (!(flags & DC_NO_TOWN_RATING) && !CheckIfAuthorityAllows(tile)) return CMD_ERROR;
 
-	int32 cost = 0;
+	CommandCost cost = 0;
 
 	/* Not allowed to build over this road */
 	if (build_over_road) {
@@ -1371,7 +1371,7 @@ int32 CmdBuildRoadStop(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 }
 
 // Remove a bus station
-static int32 RemoveRoadStop(Station *st, uint32 flags, TileIndex tile)
+static CommandCost RemoveRoadStop(Station *st, uint32 flags, TileIndex tile)
 {
 	if (_current_player != OWNER_WATER && !CheckOwnership(st->owner)) {
 		return CMD_ERROR;
@@ -1425,7 +1425,7 @@ static int32 RemoveRoadStop(Station *st, uint32 flags, TileIndex tile)
  * @param p1 not used
  * @param p2 bit 0: 0 for Bus stops, 1 for truck stops
  */
-int32 CmdRemoveRoadStop(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdRemoveRoadStop(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	/* Make sure the specified tile is a road stop of the correct type */
 	if (!IsTileType(tile, MP_STATION) || !IsRoadStop(tile) || (uint32)GetRoadStopType(tile) != p2) return CMD_ERROR;
@@ -1438,7 +1438,7 @@ int32 CmdRemoveRoadStop(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 			DiagDirToRoadBits(GetRoadStopDir(tile));
 	bool is_towns_road = is_drive_through && GetStopBuiltOnTownRoad(tile);
 
-	int32 ret = RemoveRoadStop(st, flags, tile);
+	CommandCost ret = RemoveRoadStop(st, flags, tile);
 
 	/* If the stop was a drive-through stop replace the road */
 	if ((flags & DC_EXEC) && !CmdFailed(ret) && is_drive_through) {
@@ -1550,7 +1550,7 @@ static const byte * const _airport_sections[] = {
  * @param p1 airport type, @see airport.h
  * @param p2 (bit 0) - allow airports directly adjacent to other airports.
  */
-int32 CmdBuildAirport(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdBuildAirport(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	bool airport_upgrade = true;
 
@@ -1582,9 +1582,9 @@ int32 CmdBuildAirport(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 	int w = afc->size_x;
 	int h = afc->size_y;
 
-	int32 ret = CheckFlatLandBelow(tile, w, h, flags, 0, NULL);
+	CommandCost ret = CheckFlatLandBelow(tile, w, h, flags, 0, NULL);
 	if (CmdFailed(ret)) return ret;
-	int32 cost = ret;
+	CommandCost cost = ret;
 
 	Station *st = NULL;
 
@@ -1676,7 +1676,7 @@ int32 CmdBuildAirport(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 	return cost;
 }
 
-static int32 RemoveAirport(Station *st, uint32 flags)
+static CommandCost RemoveAirport(Station *st, uint32 flags)
 {
 	if (_current_player != OWNER_WATER && !CheckOwnership(st->owner))
 		return CMD_ERROR;
@@ -1687,7 +1687,7 @@ static int32 RemoveAirport(Station *st, uint32 flags)
 	int w = afc->size_x;
 	int h = afc->size_y;
 
-	int32 cost = w * h * _price.remove_airport;
+	CommandCost cost = w * h * _price.remove_airport;
 
 	Vehicle *v;
 	FOR_ALL_VEHICLES(v) {
@@ -1730,7 +1730,7 @@ static int32 RemoveAirport(Station *st, uint32 flags)
  * @param p1 unused
  * @param p2 unused
  */
-int32 CmdBuildBuoy(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdBuildBuoy(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	SET_EXPENSES_TYPE(EXPENSES_CONSTRUCTION);
 
@@ -1789,7 +1789,7 @@ static bool CheckShipsOnBuoy(Station *st)
 	return false;
 }
 
-static int32 RemoveBuoy(Station *st, uint32 flags)
+static CommandCost RemoveBuoy(Station *st, uint32 flags)
 {
 	/* XXX: strange stuff */
 	if (!IsValidPlayer(_current_player))  return_cmd_error(INVALID_STRING_ID);
@@ -1839,9 +1839,9 @@ static const byte _dock_h_chk[4] = { 1, 2, 1, 2 };
  * @param p1 (bit 0) - allow docks directly adjacent to other docks.
  * @param p2 unused
  */
-int32 CmdBuildDock(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdBuildDock(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
-	int32 cost;
+	CommandCost cost;
 
 	SET_EXPENSES_TYPE(EXPENSES_CONSTRUCTION);
 
@@ -1938,7 +1938,7 @@ int32 CmdBuildDock(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 	return _price.build_dock;
 }
 
-static int32 RemoveDock(Station *st, uint32 flags)
+static CommandCost RemoveDock(Station *st, uint32 flags)
 {
 	if (!CheckOwnership(st->owner)) return CMD_ERROR;
 
@@ -2494,7 +2494,7 @@ static void UpdateStationWaiting(Station *st, CargoID type, uint amount)
  * @param p1 station ID that is to be renamed
  * @param p2 unused
  */
-int32 CmdRenameStation(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdRenameStation(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	if (!IsValidStationID(p1) || _cmd_text[0] == '\0') return CMD_ERROR;
 	Station *st = GetStation(p1);
@@ -2748,7 +2748,7 @@ static bool CanRemoveRoadWithStop(TileIndex tile)
 				CheckAllowRemoveRoad(tile, GetAnyRoadBits(tile, ROADTYPE_TRAM), OWNER_TOWN, &edge_road, ROADTYPE_TRAM);
 }
 
-static int32 ClearTile_Station(TileIndex tile, byte flags)
+static CommandCost ClearTile_Station(TileIndex tile, byte flags)
 {
 	if (flags & DC_AUTO) {
 		switch (GetStationType(tile)) {
diff --git a/src/town_cmd.cpp b/src/town_cmd.cpp
index 800de934b..783137e48 100644
--- a/src/town_cmd.cpp
+++ b/src/town_cmd.cpp
@@ -478,10 +478,10 @@ static void ClickTile_Town(TileIndex tile)
 	/* not used */
 }
 
-static int32 ClearTile_Town(TileIndex tile, byte flags)
+static CommandCost ClearTile_Town(TileIndex tile, byte flags)
 {
 	int rating;
-	int32 cost;
+	CommandCost cost;
 	Town *t;
 	HouseSpec *hs = GetHouseSpecs(GetHouseType(tile));
 
@@ -708,7 +708,7 @@ no_slope:
 			uint32 r = Random();
 
 			if (CHANCE16I(1, 8, r) && !_generating_world) {
-				int32 res;
+				CommandCost res;
 
 				if (CHANCE16I(1, 16, r)) {
 					res = DoCommand(tile, slope, 0, DC_EXEC | DC_AUTO | DC_NO_WATER,
@@ -730,7 +730,7 @@ no_slope:
 
 static bool TerraformTownTile(TileIndex tile, int edges, int dir)
 {
-	int32 r;
+	CommandCost r;
 
 	TILE_ASSERT(tile);
 
@@ -1464,7 +1464,7 @@ static Town *AllocateTown()
  * @param p1 size of the town (0 = small, 1 = medium, 2 = large)
  * @param p2 size mode (@see TownSizeMode)
  */
-int32 CmdBuildTown(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdBuildTown(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Town *t;
 	uint32 townnameparts;
@@ -1770,7 +1770,7 @@ static void DoBuildTownHouse(Town *t, TileIndex tile)
 
 static bool BuildTownHouse(Town *t, TileIndex tile)
 {
-	int32 r;
+	CommandCost r;
 
 	if (IsSteepSlope(GetTileSlope(tile, NULL))) return false;
 	if (MayHaveBridgeAbove(tile) && IsBridgeAbove(tile)) return false;
@@ -1846,7 +1846,7 @@ void ClearTownHouse(Town *t, TileIndex tile)
  * @param p1 town ID to rename
  * @param p2 unused
  */
-int32 CmdRenameTown(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdRenameTown(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	StringID str;
 	Town *t;
@@ -1932,7 +1932,7 @@ static void TownActionRoadRebuild(Town* t)
 static bool DoBuildStatueOfCompany(TileIndex tile, TownID town_id)
 {
 	PlayerID old;
-	int32 r;
+	CommandCost r;
 
 	if (GetTileSlope(tile, NULL) != SLOPE_FLAT) return false;
 
@@ -2050,9 +2050,9 @@ extern uint GetMaskOfTownActions(int *nump, PlayerID pid, const Town *t);
  * @param p1 town to do the action at
  * @param p2 action to perform, @see _town_action_proc for the list of available actions
  */
-int32 CmdDoTownAction(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdDoTownAction(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
-	int32 cost;
+	CommandCost cost;
 	Town *t;
 
 	if (!IsValidTownID(p1) || p2 > lengthof(_town_action_proc)) return CMD_ERROR;
diff --git a/src/train_cmd.cpp b/src/train_cmd.cpp
index 5ea332b5f..7d1356270 100644
--- a/src/train_cmd.cpp
+++ b/src/train_cmd.cpp
@@ -502,12 +502,12 @@ void DrawTrainEngine(int x, int y, EngineID engine, SpriteID pal)
 	DrawSprite(image, pal, x, y);
 }
 
-static int32 CmdBuildRailWagon(EngineID engine, TileIndex tile, uint32 flags)
+static CommandCost CmdBuildRailWagon(EngineID engine, TileIndex tile, uint32 flags)
 {
 	SET_EXPENSES_TYPE(EXPENSES_NEW_VEHICLES);
 
 	const RailVehicleInfo *rvi = RailVehInfo(engine);
-	int32 value = (GetEngineProperty(engine, 0x17, rvi->base_cost) * _price.build_railwagon) >> 8;
+	CommandCost value = (GetEngineProperty(engine, 0x17, rvi->base_cost) * _price.build_railwagon) >> 8;
 
 	uint num_vehicles = 1 + CountArticulatedParts(engine);
 
@@ -611,7 +611,7 @@ static void NormalizeTrainVehInDepot(const Vehicle* u)
 	}
 }
 
-static int32 EstimateTrainCost(EngineID engine, const RailVehicleInfo* rvi)
+static CommandCost EstimateTrainCost(EngineID engine, const RailVehicleInfo* rvi)
 {
 	return GetEngineProperty(engine, 0x17, rvi->base_cost) * (_price.build_railvehicle >> 3) >> 5;
 }
@@ -651,7 +651,7 @@ static void AddRearEngineToMultiheadedTrain(Vehicle* v, Vehicle* u, bool buildin
  * @param p2 bit 0 when set, the train will get number 0, otherwise it will get a free number
  *           bit 1 prevents any free cars from being added to the train
  */
-int32 CmdBuildRailVehicle(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdBuildRailVehicle(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	/* Check if the engine-type is valid (for the player) */
 	if (!IsEngineBuildable(p1, VEH_TRAIN, _current_player)) return_cmd_error(STR_RAIL_VEHICLE_NOT_AVAILABLE);
@@ -673,7 +673,7 @@ int32 CmdBuildRailVehicle(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 
 	if (rvi->railveh_type == RAILVEH_WAGON) return CmdBuildRailWagon(p1, tile, flags);
 
-	int32 value = EstimateTrainCost(p1, rvi);
+	CommandCost value = EstimateTrainCost(p1, rvi);
 
 	uint num_vehicles =
 		(rvi->railveh_type == RAILVEH_MULTIHEAD ? 2 : 1) +
@@ -909,7 +909,7 @@ static void NormaliseTrainConsist(Vehicle *v)
  * - p1 (bit 16 - 31) what wagon to put the source wagon AFTER, XXX - INVALID_VEHICLE to make a new line
  * @param p2 (bit 0) move all vehicles following the source vehicle
  */
-int32 CmdMoveRailVehicle(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdMoveRailVehicle(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	VehicleID s = GB(p1, 0, 16);
 	VehicleID d = GB(p1, 16, 16);
@@ -1162,7 +1162,7 @@ int32 CmdMoveRailVehicle(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * @param p1 train to start/stop
  * @param p2 unused
  */
-int32 CmdStartStopTrain(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdStartStopTrain(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	if (!IsValidVehicleID(p1)) return CMD_ERROR;
 
@@ -1203,7 +1203,7 @@ int32 CmdStartStopTrain(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * - p2 = 2: when selling attached locos, rearrange all vehicles after it to separate lines;
  *           all wagons of the same type will go on the same line. Used by the AI currently
  */
-int32 CmdSellRailWagon(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdSellRailWagon(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	/* Check if we deleted a vehicle window */
 	Window *w = NULL;
@@ -1235,7 +1235,7 @@ int32 CmdSellRailWagon(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 		RebuildVehicleLists();
 	}
 
-	int32 cost = 0;
+	CommandCost cost = 0;
 	switch (p2) {
 		case 0: case 2: { /* Delete given wagon */
 			bool switch_engine = false;    // update second wagon to engine?
@@ -1616,7 +1616,7 @@ static void ReverseTrainDirection(Vehicle *v)
  * @param p1 train to reverse
  * @param p2 if true, reverse a unit in a train (needs to be in a depot)
  */
-int32 CmdReverseTrainDirection(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdReverseTrainDirection(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	if (!IsValidVehicleID(p1)) return CMD_ERROR;
 
@@ -1665,7 +1665,7 @@ int32 CmdReverseTrainDirection(TileIndex tile, uint32 flags, uint32 p1, uint32 p
  * @param p1 train to ignore the red signal
  * @param p2 unused
  */
-int32 CmdForceTrainProceed(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdForceTrainProceed(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	if (!IsValidVehicleID(p1)) return CMD_ERROR;
 
@@ -1688,7 +1688,7 @@ int32 CmdForceTrainProceed(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * - p2 = (bit 16) - refit only this vehicle
  * @return cost of refit or error
  */
-int32 CmdRefitRailVehicle(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdRefitRailVehicle(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	CargoID new_cid = GB(p2, 0, 8);
 	byte new_subtype = GB(p2, 8, 8);
@@ -1706,7 +1706,7 @@ int32 CmdRefitRailVehicle(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 
 	SET_EXPENSES_TYPE(EXPENSES_TRAIN_RUN);
 
-	int32 cost = 0;
+	CommandCost cost = 0;
 	uint num = 0;
 
 	do {
@@ -1872,7 +1872,7 @@ static TrainFindDepotData FindClosestTrainDepot(Vehicle *v, int max_distance)
  * - p2 bit 0-3 - DEPOT_ flags (see vehicle.h)
  * - p2 bit 8-10 - VLW flag (for mass goto depot)
  */
-int32 CmdSendTrainToDepot(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdSendTrainToDepot(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	if (p2 & DEPOT_MASS_SEND) {
 		/* Mass goto depot requested */
@@ -3389,7 +3389,7 @@ void OnNewDay_Train(Vehicle *v)
 
 		if ((v->vehstatus & VS_STOPPED) == 0) {
 			/* running costs */
-			int32 cost = GetTrainRunningCost(v) / 364;
+			CommandCost cost = GetTrainRunningCost(v) / 364;
 
 			v->profit_this_year -= cost >> 8;
 
diff --git a/src/tree_cmd.cpp b/src/tree_cmd.cpp
index b4cb5fa38..42598789d 100644
--- a/src/tree_cmd.cpp
+++ b/src/tree_cmd.cpp
@@ -213,10 +213,10 @@ void GenerateTrees()
  * @param p1 tree type, -1 means random.
  * @param p2 end tile of area-drag
  */
-int32 CmdPlantTree(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdPlantTree(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	StringID msg = INVALID_STRING_ID;
-	int32 cost;
+	CommandCost cost;
 	int ex;
 	int ey;
 	int sx, sy, x, y;
@@ -428,7 +428,7 @@ static Slope GetSlopeTileh_Trees(TileIndex tile, Slope tileh)
 	return tileh;
 }
 
-static int32 ClearTile_Trees(TileIndex tile, byte flags)
+static CommandCost ClearTile_Trees(TileIndex tile, byte flags)
 {
 	uint num;
 
diff --git a/src/tunnelbridge_cmd.cpp b/src/tunnelbridge_cmd.cpp
index c565a5f66..d8fcfb8d8 100644
--- a/src/tunnelbridge_cmd.cpp
+++ b/src/tunnelbridge_cmd.cpp
@@ -110,7 +110,7 @@ static inline byte GetBridgeFlags(int index) { return _bridge[index].flags;}
  * - rest is invalid
  */
 #define M(x) (1 << (x))
-static int32 CheckBridgeSlopeNorth(Axis axis, Slope tileh)
+static CommandCost CheckBridgeSlopeNorth(Axis axis, Slope tileh)
 {
 	uint32 valid;
 
@@ -125,7 +125,7 @@ static int32 CheckBridgeSlopeNorth(Axis axis, Slope tileh)
 	return CMD_ERROR;
 }
 
-static int32 CheckBridgeSlopeSouth(Axis axis, Slope tileh)
+static CommandCost CheckBridgeSlopeSouth(Axis axis, Slope tileh)
 {
 	uint32 valid;
 
@@ -175,7 +175,7 @@ bool CheckBridge_Stuff(byte bridge_type, uint bridge_len)
  * - p2 = (bit 8-..) - rail type or road types.
  * - p2 = (bit 15  ) - set means road bridge.
  */
-int32 CmdBuildBridge(TileIndex end_tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdBuildBridge(TileIndex end_tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	uint bridge_type;
 	RailType railtype;
@@ -194,7 +194,7 @@ int32 CmdBuildBridge(TileIndex end_tile, uint32 flags, uint32 p1, uint32 p2)
 	TileIndexDiff delta;
 	uint bridge_len;
 	Axis direction;
-	int32 cost, terraformcost, ret;
+	CommandCost cost, terraformcost, ret;
 	bool allow_on_slopes;
 	bool replace_bridge = false;
 	uint replaced_bridge_type;
@@ -453,7 +453,7 @@ not_valid_below:;
  * @param p1 railtype or roadtypes. bit 9 set means road tunnel
  * @param p2 unused
  */
-int32 CmdBuildTunnel(TileIndex start_tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdBuildTunnel(TileIndex start_tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	TileIndexDiff delta;
 	TileIndex end_tile;
@@ -462,8 +462,8 @@ int32 CmdBuildTunnel(TileIndex start_tile, uint32 flags, uint32 p1, uint32 p2)
 	Slope end_tileh;
 	uint start_z;
 	uint end_z;
-	int32 cost;
-	int32 ret;
+	CommandCost cost;
+	CommandCost ret;
 
 	_build_tunnel_endtile = 0;
 	if (!HASBIT(p1, 9)) {
@@ -578,7 +578,7 @@ static inline bool CheckAllowRemoveTunnelBridge(TileIndex tile)
 	return false;
 }
 
-static int32 DoClearTunnel(TileIndex tile, uint32 flags)
+static CommandCost DoClearTunnel(TileIndex tile, uint32 flags)
 {
 	Town *t = NULL;
 	TileIndex endtile;
@@ -638,7 +638,7 @@ static bool IsVehicleOnBridge(TileIndex starttile, TileIndex endtile, uint z)
 	return false;
 }
 
-static int32 DoClearBridge(TileIndex tile, uint32 flags)
+static CommandCost DoClearBridge(TileIndex tile, uint32 flags)
 {
 	DiagDirection direction;
 	TileIndexDiff delta;
@@ -698,7 +698,7 @@ static int32 DoClearBridge(TileIndex tile, uint32 flags)
 	return (DistanceManhattan(tile, endtile) + 1) * _price.clear_bridge;
 }
 
-static int32 ClearTile_TunnelBridge(TileIndex tile, byte flags)
+static CommandCost ClearTile_TunnelBridge(TileIndex tile, byte flags)
 {
 	if (IsTunnel(tile)) {
 		if (flags & DC_AUTO) return_cmd_error(STR_5006_MUST_DEMOLISH_TUNNEL_FIRST);
@@ -721,7 +721,7 @@ static int32 ClearTile_TunnelBridge(TileIndex tile, byte flags)
  * @return            The cost and state of the operation
  * @retval CMD_ERROR  An error occured during the operation.
  */
-int32 DoConvertTunnelBridgeRail(TileIndex tile, RailType totype, bool exec)
+CommandCost DoConvertTunnelBridgeRail(TileIndex tile, RailType totype, bool exec)
 {
 	TileIndex endtile;
 
diff --git a/src/unmovable_cmd.cpp b/src/unmovable_cmd.cpp
index dc3bf1112..97a558caa 100644
--- a/src/unmovable_cmd.cpp
+++ b/src/unmovable_cmd.cpp
@@ -31,7 +31,7 @@
  * @param flags docommand flags of calling function
  * @return cost of the operation
  */
-static int32 DestroyCompanyHQ(PlayerID pid, uint32 flags)
+static CommandCost DestroyCompanyHQ(PlayerID pid, uint32 flags)
 {
 	Player* p = GetPlayer(pid);
 
@@ -73,7 +73,7 @@ void UpdateCompanyHQ(Player *p, uint score)
 	MarkTileDirtyByTile(tile + TileDiffXY(1, 1));
 }
 
-extern int32 CheckFlatLandBelow(TileIndex tile, uint w, uint h, uint flags, uint invalid_dirs, StationID* station, bool check_clear = true);
+extern CommandCost CheckFlatLandBelow(TileIndex tile, uint w, uint h, uint flags, uint invalid_dirs, StationID* station, bool check_clear = true);
 
 /** Build or relocate the HQ. This depends if the HQ is already built or not
  * @param tile tile where the HQ will be built or relocated to
@@ -81,11 +81,11 @@ extern int32 CheckFlatLandBelow(TileIndex tile, uint w, uint h, uint flags, uint
  * @param p1 unused
  * @param p2 unused
  */
-int32 CmdBuildCompanyHQ(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdBuildCompanyHQ(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Player *p = GetPlayer(_current_player);
-	int cost;
-	int32 ret;
+	CommandCost cost;
+	CommandCost ret;
 
 	SET_EXPENSES_TYPE(EXPENSES_PROPERTY);
 
@@ -216,7 +216,7 @@ static Slope GetSlopeTileh_Unmovable(TileIndex tile, Slope tileh)
 	return IsOwnedLand(tile) ? tileh : SLOPE_FLAT;
 }
 
-static int32 ClearTile_Unmovable(TileIndex tile, byte flags)
+static CommandCost ClearTile_Unmovable(TileIndex tile, byte flags)
 {
 	if (IsCompanyHQ(tile)) {
 		if (_current_player == OWNER_WATER) {
diff --git a/src/vehicle.cpp b/src/vehicle.cpp
index 78afd5eb6..c6515fe19 100644
--- a/src/vehicle.cpp
+++ b/src/vehicle.cpp
@@ -845,9 +845,9 @@ CargoID FindFirstRefittableCargo(EngineID engine_type)
 * @param engine_type Which engine to refit
 * @return Price for refitting
 */
-int32 GetRefitCost(EngineID engine_type)
+CommandCost GetRefitCost(EngineID engine_type)
 {
-	int32 base_cost = 0;
+	CommandCost base_cost = 0;
 
 	switch (GetEngine(engine_type)->type) {
 		case VEH_SHIP: base_cost = _price.ship_base; break;
@@ -1679,12 +1679,12 @@ void AgeVehicle(Vehicle *v)
  *   - bit 6 if set, then it's a vehicle list window, not a depot and Tile is ignored in this case
  *   - bit 8-11 Vehicle List Window type (ignored unless bit 1 is set)
  */
-int32 CmdMassStartStopVehicle(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdMassStartStopVehicle(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Vehicle **vl = NULL;
 	uint16 engine_list_length = 0;
 	uint16 engine_count = 0;
-	int32 return_value = CMD_ERROR;
+	CommandCost return_value = CMD_ERROR;
 	uint i;
 	uint stop_command;
 	VehicleType vehicle_type = (VehicleType)GB(p2, 0, 5);
@@ -1711,7 +1711,7 @@ int32 CmdMassStartStopVehicle(TileIndex tile, uint32 flags, uint32 p1, uint32 p2
 
 	for (i = 0; i < engine_count; i++) {
 		const Vehicle *v = vl[i];
-		int32 ret;
+		CommandCost ret;
 
 		if (!!(v->vehstatus & VS_STOPPED) != start_stop) continue;
 
@@ -1743,7 +1743,7 @@ int32 CmdMassStartStopVehicle(TileIndex tile, uint32 flags, uint32 p1, uint32 p2
  * @param p1 Vehicle type
  * @param p2 unused
  */
-int32 CmdDepotSellAllVehicles(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdDepotSellAllVehicles(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Vehicle **engines = NULL;
 	Vehicle **wagons = NULL;
@@ -1752,7 +1752,7 @@ int32 CmdDepotSellAllVehicles(TileIndex tile, uint32 flags, uint32 p1, uint32 p2
 	uint16 wagon_list_length = 0;
 	uint16 wagon_count = 0;
 
-	int32 cost = 0;
+	CommandCost cost = 0;
 	uint i, sell_command, total_number_vehicles;
 	VehicleType vehicle_type = (VehicleType)GB(p1, 0, 8);
 
@@ -1771,7 +1771,7 @@ int32 CmdDepotSellAllVehicles(TileIndex tile, uint32 flags, uint32 p1, uint32 p2
 	total_number_vehicles = engine_count + wagon_count;
 	for (i = 0; i < total_number_vehicles; i++) {
 		const Vehicle *v;
-		int32 ret;
+		CommandCost ret;
 
 		if (i < engine_count) {
 			v = engines[i];
@@ -1796,13 +1796,13 @@ int32 CmdDepotSellAllVehicles(TileIndex tile, uint32 flags, uint32 p1, uint32 p2
  * @param p1 Type of vehicle
  * @param p2 Unused
  */
-int32 CmdDepotMassAutoReplace(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdDepotMassAutoReplace(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Vehicle **vl = NULL;
 	uint16 engine_list_length = 0;
 	uint16 engine_count = 0;
 	uint i, x = 0, y = 0, z = 0;
-	int32 cost = 0;
+	CommandCost cost = 0;
 	VehicleType vehicle_type = (VehicleType)GB(p1, 0, 8);
 
 	if (!IsTileOwner(tile, _current_player)) return CMD_ERROR;
@@ -1814,7 +1814,7 @@ int32 CmdDepotMassAutoReplace(TileIndex tile, uint32 flags, uint32 p1, uint32 p2
 	for (i = 0; i < engine_count; i++) {
 		Vehicle *v = vl[i];
 		bool stopped = !(v->vehstatus & VS_STOPPED);
-		int32 ret;
+		CommandCost ret;
 
 		/* Ensure that the vehicle completely in the depot */
 		if (!IsVehicleInDepot(v)) continue;
@@ -1862,11 +1862,11 @@ int32 CmdDepotMassAutoReplace(TileIndex tile, uint32 flags, uint32 p1, uint32 p2
  * @param p1 the original vehicle's index
  * @param p2 1 = shared orders, else copied orders
  */
-int32 CmdCloneVehicle(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdCloneVehicle(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Vehicle *v_front, *v;
 	Vehicle *w_front, *w, *w_rear;
-	int32 cost, total_cost = 0;
+	CommandCost cost, total_cost = 0;
 	uint32 build_argument = 2;
 
 	if (!IsValidVehicleID(p1)) return CMD_ERROR;
@@ -1926,7 +1926,7 @@ int32 CmdCloneVehicle(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 			if (v->type == VEH_TRAIN && !IsFrontEngine(v)) {
 				/* this s a train car
 				 * add this unit to the end of the train */
-				int32 result = DoCommand(0, (w_rear->index << 16) | w->index, 1, flags, CMD_MOVE_RAIL_VEHICLE);
+				CommandCost result = DoCommand(0, (w_rear->index << 16) | w->index, 1, flags, CMD_MOVE_RAIL_VEHICLE);
 				if (CmdFailed(result)) {
 					/* The train can't be joined to make the same consist as the original.
 					 * Sell what we already made (clean up) and return an error.           */
@@ -2223,7 +2223,7 @@ uint GenerateVehicleSortList(const Vehicle ***sort_list, uint16 *length_of_array
  * @param vlw_flag tells what kind of list requested the goto depot
  * @return 0 for success and CMD_ERROR if no vehicle is able to go to depot
  */
-int32 SendAllVehiclesToDepot(VehicleType type, uint32 flags, bool service, PlayerID owner, uint16 vlw_flag, uint32 id)
+CommandCost SendAllVehiclesToDepot(VehicleType type, uint32 flags, bool service, PlayerID owner, uint16 vlw_flag, uint32 id)
 {
 	const Vehicle **sort_list = NULL;
 	uint n, i;
@@ -2234,7 +2234,7 @@ int32 SendAllVehiclesToDepot(VehicleType type, uint32 flags, bool service, Playe
 	/* Send all the vehicles to a depot */
 	for (i = 0; i < n; i++) {
 		const Vehicle *v = sort_list[i];
-		int32 ret = DoCommand(v->tile, v->index, (service ? 1 : 0) | DEPOT_DONT_CANCEL, flags, GetCmdSendToDepot(type));
+		CommandCost ret = DoCommand(v->tile, v->index, (service ? 1 : 0) | DEPOT_DONT_CANCEL, flags, GetCmdSendToDepot(type));
 
 		/* Return 0 if DC_EXEC is not set this is a valid goto depot command)
 			* In this case we know that at least one vehicle can be sent to a depot
@@ -2314,7 +2314,7 @@ void VehicleEnterDepot(Vehicle *v)
 		v->current_order.flags = 0;
 
 		if (t.refit_cargo < NUM_CARGO) {
-			int32 cost;
+			CommandCost cost;
 
 			_current_player = v->owner;
 			cost = DoCommand(v->tile, v->index, t.refit_cargo | t.refit_subtype << 8, DC_EXEC, GetCmdRefitVeh(v));
@@ -2362,7 +2362,7 @@ void VehicleEnterDepot(Vehicle *v)
  * @param p1 vehicle ID to name
  * @param p2 unused
  */
-int32 CmdNameVehicle(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdNameVehicle(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Vehicle *v;
 	StringID str;
@@ -2396,7 +2396,7 @@ int32 CmdNameVehicle(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * @param p1 vehicle ID that is being service-interval-changed
  * @param p2 new service interval
  */
-int32 CmdChangeServiceInt(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdChangeServiceInt(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Vehicle* v;
 	uint16 serv_int = GetServiceIntervalClamped(p2); /* Double check the service interval from the user-input */
diff --git a/src/vehicle.h b/src/vehicle.h
index 2d808c0b9..f9103c930 100644
--- a/src/vehicle.h
+++ b/src/vehicle.h
@@ -509,7 +509,7 @@ void ResetVehiclePosHash();
 
 bool CanRefitTo(EngineID engine_type, CargoID cid_to);
 CargoID FindFirstRefittableCargo(EngineID engine_type);
-int32 GetRefitCost(EngineID engine_type);
+CommandCost GetRefitCost(EngineID engine_type);
 
 void ViewportAddVehicles(DrawPixelInfo *dpi);
 
@@ -556,13 +556,13 @@ bool VehicleNeedsService(const Vehicle *v);
 
 uint GenerateVehicleSortList(const Vehicle*** sort_list, uint16 *length_of_array, VehicleType type, PlayerID owner, uint32 index, uint16 window_type);
 void BuildDepotVehicleList(VehicleType type, TileIndex tile, Vehicle ***engine_list, uint16 *engine_list_length, uint16 *engine_count, Vehicle ***wagon_list, uint16 *wagon_list_length, uint16 *wagon_count);
-int32 SendAllVehiclesToDepot(VehicleType type, uint32 flags, bool service, PlayerID owner, uint16 vlw_flag, uint32 id);
+CommandCost SendAllVehiclesToDepot(VehicleType type, uint32 flags, bool service, PlayerID owner, uint16 vlw_flag, uint32 id);
 bool IsVehicleInDepot(const Vehicle *v);
 void VehicleEnterDepot(Vehicle *v);
 
 void InvalidateAutoreplaceWindow(EngineID e);
 
-int32 MaybeReplaceVehicle(Vehicle *v, bool check, bool display_costs);
+CommandCost MaybeReplaceVehicle(Vehicle *v, bool check, bool display_costs);
 
 /* Flags to add to p2 for goto depot commands */
 /* Note: bits 8-10 are used for VLW flags */
diff --git a/src/vehicle_gui.cpp b/src/vehicle_gui.cpp
index 03e232205..5bffa340d 100644
--- a/src/vehicle_gui.cpp
+++ b/src/vehicle_gui.cpp
@@ -338,7 +338,7 @@ static void VehicleRefitWndProc(Window *w, WindowEvent *e)
 			WP(w, refit_d).cargo = DrawVehicleRefitWindow(WP(w, refit_d).list, WP(w, refit_d).sel, w->vscroll.pos, w->vscroll.cap, w->resize.step_height);
 
 			if (WP(w, refit_d).cargo != NULL) {
-				int32 cost;
+				CommandCost cost;
 
 				cost = DoCommand(v->tile, v->index, WP(w, refit_d).cargo->cargo | WP(w, refit_d).cargo->subtype << 8,
 								 DC_QUERY_COST, GetCmdRefitVeh(GetVehicle(w->window_number)->type));
diff --git a/src/water_cmd.cpp b/src/water_cmd.cpp
index fd4099569..1a06c3ff6 100644
--- a/src/water_cmd.cpp
+++ b/src/water_cmd.cpp
@@ -56,11 +56,11 @@ static void FloodVehicle(Vehicle *v);
  * @param p1 bit 0 depot orientation (Axis)
  * @param p2 unused
  */
-int32 CmdBuildShipDepot(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdBuildShipDepot(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	TileIndex tile2;
 
-	int32 cost, ret;
+	CommandCost cost, ret;
 	Depot *depot;
 
 	SET_EXPENSES_TYPE(EXPENSES_CONSTRUCTION);
@@ -101,7 +101,7 @@ int32 CmdBuildShipDepot(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 	return cost + _price.build_ship_depot;
 }
 
-static int32 RemoveShipDepot(TileIndex tile, uint32 flags)
+static CommandCost RemoveShipDepot(TileIndex tile, uint32 flags)
 {
 	TileIndex tile2;
 
@@ -127,9 +127,9 @@ static int32 RemoveShipDepot(TileIndex tile, uint32 flags)
 }
 
 /** build a shiplift */
-static int32 DoBuildShiplift(TileIndex tile, DiagDirection dir, uint32 flags)
+static CommandCost DoBuildShiplift(TileIndex tile, DiagDirection dir, uint32 flags)
 {
-	int32 ret;
+	CommandCost ret;
 	int delta;
 
 	/* middle tile */
@@ -167,7 +167,7 @@ static int32 DoBuildShiplift(TileIndex tile, DiagDirection dir, uint32 flags)
 	return _price.clear_water * 22 >> 3;
 }
 
-static int32 RemoveShiplift(TileIndex tile, uint32 flags)
+static CommandCost RemoveShiplift(TileIndex tile, uint32 flags)
 {
 	TileIndexDiff delta = TileOffsByDiagDir(GetLockDirection(tile));
 
@@ -200,7 +200,7 @@ static void MarkTilesAroundDirty(TileIndex tile)
  * @param p1 unused
  * @param p2 unused
  */
-int32 CmdBuildLock(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdBuildLock(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	DiagDirection dir;
 
@@ -222,9 +222,9 @@ int32 CmdBuildLock(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * @param p1 start tile of stretch-dragging
  * @param p2 ctrl pressed - toggles ocean / canals at sealevel (ocean only allowed in the scenario editor)
  */
-int32 CmdBuildCanal(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdBuildCanal(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
-	int32 cost;
+	CommandCost cost;
 	int size_x, size_y;
 	int x;
 	int y;
@@ -251,7 +251,7 @@ int32 CmdBuildCanal(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 
 	cost = 0;
 	BEGIN_TILE_LOOP(tile, size_x, size_y, TileXY(sx, sy)) {
-		int32 ret;
+		CommandCost ret;
 
 		if (GetTileSlope(tile, NULL) != SLOPE_FLAT) {
 			return_cmd_error(STR_0007_FLAT_LAND_REQUIRED);
@@ -284,7 +284,7 @@ int32 CmdBuildCanal(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 	}
 }
 
-static int32 ClearTile_Water(TileIndex tile, byte flags)
+static CommandCost ClearTile_Water(TileIndex tile, byte flags)
 {
 	switch (GetWaterTileType(tile)) {
 		case WATER_TILE_CLEAR:
diff --git a/src/waypoint.cpp b/src/waypoint.cpp
index d691636dc..134b56996 100644
--- a/src/waypoint.cpp
+++ b/src/waypoint.cpp
@@ -201,7 +201,7 @@ void AfterLoadWaypoints()
  * @todo When checking for the tile slope,
  * distingush between "Flat land required" and "land sloped in wrong direction"
  */
-int32 CmdBuildTrainWaypoint(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdBuildTrainWaypoint(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Waypoint *wp;
 	Slope tileh;
@@ -295,7 +295,7 @@ void WaypointsDailyLoop()
  * @param justremove will indicate if it is removed from rail or if rails are removed too
  * @return cost of operation or error
  */
-int32 RemoveTrainWaypoint(TileIndex tile, uint32 flags, bool justremove)
+CommandCost RemoveTrainWaypoint(TileIndex tile, uint32 flags, bool justremove)
 {
 	Waypoint *wp;
 
@@ -335,7 +335,7 @@ int32 RemoveTrainWaypoint(TileIndex tile, uint32 flags, bool justremove)
  * @param p2 unused
  * @return cost of operation or error
  */
-int32 CmdRemoveTrainWaypoint(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdRemoveTrainWaypoint(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	SET_EXPENSES_TYPE(EXPENSES_CONSTRUCTION);
 	return RemoveTrainWaypoint(tile, flags, true);
@@ -349,7 +349,7 @@ int32 CmdRemoveTrainWaypoint(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
  * @param p2 unused
  * @return cost of operation or error
  */
-int32 CmdRenameWaypoint(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
+CommandCost CmdRenameWaypoint(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	Waypoint *wp;
 
diff --git a/src/waypoint.h b/src/waypoint.h
index 9f268bfd6..384bb4de4 100644
--- a/src/waypoint.h
+++ b/src/waypoint.h
@@ -66,7 +66,7 @@ static inline Waypoint *GetWaypointByTile(TileIndex tile)
 	return GetWaypoint(GetWaypointIndex(tile));
 }
 
-int32 RemoveTrainWaypoint(TileIndex tile, uint32 flags, bool justremove);
+CommandCost RemoveTrainWaypoint(TileIndex tile, uint32 flags, bool justremove);
 Station *ComposeWaypointStation(TileIndex tile);
 void ShowRenameWaypointWindow(const Waypoint *cp);
 void DrawWaypointSprite(int x, int y, int image, RailType railtype);