Codechange: strongly type TownID

src/cargomonitor.h

@@ -81,7 +81,7 @@ inline CargoMonitorID EncodeCargoTownMonitor(CompanyID company, CargoType ctype,
 	assert(company < (1 << CCB_COMPANY_LENGTH));
 
 	uint32_t ret = 0;
-	SB(ret, CCB_TOWN_IND_NUMBER_START, CCB_TOWN_IND_NUMBER_LENGTH, town);
+	SB(ret, CCB_TOWN_IND_NUMBER_START, CCB_TOWN_IND_NUMBER_LENGTH, town.base());
 	SB(ret, CCB_CARGO_TYPE_START, CCB_CARGO_TYPE_LENGTH, ctype);
 	SB(ret, CCB_COMPANY_START, CCB_COMPANY_LENGTH, company.base());
 	return ret;

src/newgrf_industries.cpp

@@ -170,7 +170,7 @@ static uint32_t GetCountAndDistanceOfClosestInstance(uint8_t param_setID, uint8_
 			case 0x81: return GB(this->tile.base(), 8, 8);
 
 			/* Pointer to the town the industry is associated with */
-			case 0x82: return this->industry->town->index;
+			case 0x82: return this->industry->town->index.base();
 			case 0x83:
 			case 0x84:
 			case 0x85: Debug(grf, 0, "NewGRFs shouldn't be doing pointer magic"); break; // not supported
@@ -357,7 +357,7 @@ static uint32_t GetCountAndDistanceOfClosestInstance(uint8_t param_setID, uint8_
 		case 0x80: return this->industry->location.tile.base();
 		case 0x81: return GB(this->industry->location.tile.base(), 8, 8);
 		/* Pointer to the town the industry is associated with */
-		case 0x82: return this->industry->town->index;
+		case 0x82: return this->industry->town->index.base();
 		case 0x83:
 		case 0x84:
 		case 0x85: Debug(grf, 0, "NewGRFs shouldn't be doing pointer magic"); break; // not supported

src/newgrf_town.cpp

@@ -31,7 +31,7 @@
 			return 0;
 
 		/* Town index */
-		case 0x41: return this->t->index;
+		case 0x41: return this->t->index.base();
 
 		/* Get a variable from the persistent storage */
 		case 0x7C: {

src/news_gui.cpp

@@ -923,7 +923,7 @@ uint32_t SerialiseNewsReference(const NewsReference &reference)
 		uint32_t operator()(const VehicleID v) { return v; }
 		uint32_t operator()(const StationID s) { return s; }
 		uint32_t operator()(const IndustryID i) { return i.base(); }
-		uint32_t operator()(const TownID t) { return t; }
+		uint32_t operator()(const TownID t) { return t.base(); }
 		uint32_t operator()(const EngineID e) { return e.base(); }
 	};
 

src/road_map.h

@@ -636,7 +636,7 @@ inline void MakeRoadNormal(Tile t, RoadBits bits, RoadType road_rt, RoadType tra
 {
 	SetTileType(t, MP_ROAD);
 	SetTileOwner(t, road);
-	t.m2() = town;
+	t.m2() = town.base();
 	t.m3() = (tram_rt != INVALID_ROADTYPE ? bits : 0);
 	t.m5() = (road_rt != INVALID_ROADTYPE ? bits : 0) | ROAD_TILE_NORMAL << 6;
 	SB(t.m6(), 2, 4, 0);
@@ -661,7 +661,7 @@ inline void MakeRoadCrossing(Tile t, Owner road, Owner tram, Owner rail, Axis ro
 {
 	SetTileType(t, MP_ROAD);
 	SetTileOwner(t, rail);
-	t.m2() = town;
+	t.m2() = town.base();
 	t.m3() = 0;
 	t.m4() = INVALID_ROADTYPE;
 	t.m5() = ROAD_TILE_CROSSING << 6 | roaddir;

src/saveload/afterload.cpp

@@ -1010,7 +1010,7 @@ bool AfterLoadGame()
 					if ((GB(t.m5(), 4, 2) == ROAD_TILE_CROSSING ? (Owner)t.m3() : GetTileOwner(t)) == OWNER_TOWN) {
 						SetTownIndex(t, CalcClosestTownFromTile(t)->index);
 					} else {
-						SetTownIndex(t, TOWN_BEGIN);
+						SetTownIndex(t, TownID::Begin());
 					}
 					break;
 
@@ -1234,11 +1234,11 @@ bool AfterLoadGame()
 								GetRailType(t)
 							);
 						} else {
-							TownID town = IsTileOwner(t, OWNER_TOWN) ? ClosestTownFromTile(t, UINT_MAX)->index : TOWN_BEGIN;
+							TownID town = IsTileOwner(t, OWNER_TOWN) ? ClosestTownFromTile(t, UINT_MAX)->index : TownID::Begin();
 
 							/* MakeRoadNormal */
 							SetTileType(t, MP_ROAD);
-							t.m2() = town;
+							t.m2() = town.base();
 							t.m3() = 0;
 							t.m5() = (axis == AXIS_X ? ROAD_Y : ROAD_X) | ROAD_TILE_NORMAL << 6;
 							SB(t.m6(), 2, 4, 0);
@@ -1626,7 +1626,7 @@ bool AfterLoadGame()
 	if (IsSavegameVersionBefore(SLV_52)) {
 		for (auto t : Map::Iterate()) {
 			if (IsTileType(t, MP_OBJECT) && t.m5() == OBJECT_STATUE) {
-				t.m2() = CalcClosestTownFromTile(t)->index;
+				t.m2() = CalcClosestTownFromTile(t)->index.base();
 			}
 		}
 	}

src/saveload/depot_sl.cpp

@@ -53,7 +53,7 @@ struct DEPTChunkHandler : ChunkHandler {
 			SlObject(depot, slt);
 
 			/* Set the town 'pointer' so we can restore it later. */
-			if (IsSavegameVersionBefore(SLV_141)) depot->town = (Town *)(size_t)_town_index;
+			if (IsSavegameVersionBefore(SLV_141)) depot->town = reinterpret_cast<Town *>(static_cast<size_t>(_town_index.base()));
 		}
 	}
 

src/town.h

@@ -33,7 +33,7 @@ static const uint TOWN_GROWTH_DESERT = 0xFFFFFFFF; ///< The town needs the cargo
 static const uint16_t TOWN_GROWTH_RATE_NONE = 0xFFFF; ///< Special value for Town::growth_rate to disable town growth.
 static const uint16_t MAX_TOWN_GROWTH_TICKS = 930; ///< Max amount of original town ticks that still fit into uint16_t, about equal to UINT16_MAX / TOWN_GROWTH_TICKS but slightly less to simplify calculations
 
-typedef Pool<Town, TownID, 64, TOWN_END> TownPool;
+typedef Pool<Town, TownID, 64, TownID::End().base()> TownPool;
 extern TownPool _town_pool;
 
 /** Data structure with cached data of towns. */

src/town_map.h

@@ -35,7 +35,7 @@ inline TownID GetTownIndex(Tile t)
 inline void SetTownIndex(Tile t, TownID index)
 {
 	assert(IsTileType(t, MP_HOUSE) || (IsTileType(t, MP_ROAD) && !IsRoadDepot(t)));
-	t.m2() = index;
+	t.m2() = index.base();
 }
 
 /**
@@ -378,7 +378,7 @@ inline void MakeHouseTile(Tile t, TownID tid, uint8_t counter, uint8_t stage, Ho
 
 	SetTileType(t, MP_HOUSE);
 	t.m1() = random_bits;
-	t.m2() = tid;
+	t.m2() = tid.base();
 	t.m3() = 0;
 	SetHouseType(t, type);
 	SetHouseCompleted(t, stage == TOWN_HOUSE_COMPLETED);

src/town_type.h

@@ -11,12 +11,10 @@
 #define TOWN_TYPE_H
 
 #include "core/enum_type.hpp"
+#include "core/pool_type.hpp"
 
-enum TownID : uint16_t {
+using TownID = PoolID<uint16_t, struct TownIDTag, 64000, 0xFFFF>;
-	TOWN_BEGIN = 0,
+static constexpr TownID INVALID_TOWN = TownID::Invalid();
-	TOWN_END = 64000,
-	INVALID_TOWN = 0xFFFF
-};
 
 struct Town;