From 798e9f229c0f91dd41301d391ddba7171e5cfeb2 Mon Sep 17 00:00:00 2001
From: Rubidium <rubidium@openttd.org>
Date: Fri, 7 Feb 2025 16:45:45 +0100
Subject: [PATCH] Codechange: strongly type DepotID

---
 src/depot_base.h           | 2 +-
 src/depot_map.h            | 2 +-
 src/depot_type.h           | 6 ++++--
 src/order_type.h           | 1 +
 src/rail_map.h             | 2 +-
 src/road_map.h             | 2 +-
 src/saveload/afterload.cpp | 4 ++--
 src/water_map.h            | 2 +-
 8 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/src/depot_base.h b/src/depot_base.h
index 1d8330fc74..3998f4456b 100644
--- a/src/depot_base.h
+++ b/src/depot_base.h
@@ -14,7 +14,7 @@
 #include "core/pool_type.hpp"
 #include "timer/timer_game_calendar.h"
 
-typedef Pool<Depot, DepotID, 64, 64000> DepotPool;
+typedef Pool<Depot, DepotID, 64, DepotID::End().base()> DepotPool;
 extern DepotPool _depot_pool;
 
 struct Depot : DepotPool::PoolItem<&_depot_pool> {
diff --git a/src/depot_map.h b/src/depot_map.h
index cb38fbaf97..793047ada2 100644
--- a/src/depot_map.h
+++ b/src/depot_map.h
@@ -54,7 +54,7 @@ inline DepotID GetDepotIndex(Tile t)
 {
 	/* Hangars don't have a Depot class, thus store no DepotID. */
 	assert(IsRailDepotTile(t) || IsRoadDepotTile(t) || IsShipDepotTile(t));
-	return t.m2();
+	return DepotID{t.m2()};
 }
 
 /**
diff --git a/src/depot_type.h b/src/depot_type.h
index 4e61c1bcbd..d76693aa26 100644
--- a/src/depot_type.h
+++ b/src/depot_type.h
@@ -10,10 +10,12 @@
 #ifndef DEPOT_TYPE_H
 #define DEPOT_TYPE_H
 
-typedef uint16_t DepotID; ///< Type for the unique identifier of depots.
+#include "core/pool_type.hpp"
+
+using DepotID = PoolID<uint16_t, struct DepotIDTag, 64000, 0xFFFF>; ///< Type for the unique identifier of depots.
 struct Depot;
 
-static const DepotID INVALID_DEPOT = UINT16_MAX;
+static constexpr DepotID INVALID_DEPOT = DepotID::Invalid();
 
 static const uint MAX_LENGTH_DEPOT_NAME_CHARS = 32; ///< The maximum length of a depot name in characters including '\0'
 
diff --git a/src/order_type.h b/src/order_type.h
index 915d0b242f..cf7f880297 100644
--- a/src/order_type.h
+++ b/src/order_type.h
@@ -25,6 +25,7 @@ struct DestinationID {
 
 	explicit DestinationID() = default;
 	constexpr DestinationID(size_t index) : value(static_cast<BaseType>(index)) {}
+	constexpr DestinationID(DepotID depot) : value(depot.base()) {}
 
 	constexpr DepotID ToDepotID() const noexcept { return static_cast<DepotID>(this->value); }
 	constexpr StationID ToStationID() const noexcept { return static_cast<StationID>(this->value); }
diff --git a/src/rail_map.h b/src/rail_map.h
index 88ea36af7f..17e2988dc0 100644
--- a/src/rail_map.h
+++ b/src/rail_map.h
@@ -554,7 +554,7 @@ inline void MakeRailDepot(Tile tile, Owner owner, DepotID depot_id, DiagDirectio
 	SetTileType(tile, MP_RAILWAY);
 	SetTileOwner(tile, owner);
 	SetDockingTile(tile, false);
-	tile.m2() = depot_id;
+	tile.m2() = depot_id.base();
 	tile.m3() = 0;
 	tile.m4() = 0;
 	tile.m5() = RAIL_TILE_DEPOT << 6 | dir;
diff --git a/src/road_map.h b/src/road_map.h
index e40ee33857..a99e94be1a 100644
--- a/src/road_map.h
+++ b/src/road_map.h
@@ -695,7 +695,7 @@ inline void MakeRoadDepot(Tile tile, Owner owner, DepotID depot_id, DiagDirectio
 {
 	SetTileType(tile, MP_ROAD);
 	SetTileOwner(tile, owner);
-	tile.m2() = depot_id;
+	tile.m2() = depot_id.base();
 	tile.m3() = 0;
 	tile.m4() = INVALID_ROADTYPE;
 	tile.m5() = ROAD_TILE_DEPOT << 6 | dir;
diff --git a/src/saveload/afterload.cpp b/src/saveload/afterload.cpp
index bfeb97c42b..572e739882 100644
--- a/src/saveload/afterload.cpp
+++ b/src/saveload/afterload.cpp
@@ -2355,8 +2355,8 @@ bool AfterLoadGame()
 				d = nullptr;
 				continue;
 			}
-			tile.m2() = d->index;
-			if (IsTileType(tile, MP_WATER)) Tile(GetOtherShipDepotTile(tile)).m2() = d->index;
+			tile.m2() = d->index.base();
+			if (IsTileType(tile, MP_WATER)) Tile(GetOtherShipDepotTile(tile)).m2() = d->index.base();
 		}
 	}
 
diff --git a/src/water_map.h b/src/water_map.h
index 82d532de88..b3a7a335f3 100644
--- a/src/water_map.h
+++ b/src/water_map.h
@@ -461,7 +461,7 @@ inline void MakeShipDepot(Tile t, Owner o, DepotID did, DepotPart part, Axis a,
 	SetTileOwner(t, o);
 	SetWaterClass(t, original_water_class);
 	SetDockingTile(t, false);
-	t.m2() = did;
+	t.m2() = did.base();
 	t.m3() = 0;
 	t.m4() = 0;
 	t.m5() = part << WBL_DEPOT_PART | a << WBL_DEPOT_AXIS;