From 1424a184d8eff1ae78bd5c299386d6bac3e8640b Mon Sep 17 00:00:00 2001
From: Peter Nelson <peter1138@openttd.org>
Date: Wed, 1 May 2024 18:23:27 +0100
Subject: [PATCH] Codechange: Use vector/span when loading wagon overrides.
 (#12604)

Replaces manual memory allocation and passing pointer with size.
---
 src/newgrf.cpp        | 18 +++++++-----------
 src/newgrf_engine.cpp |  4 ++--
 src/newgrf_engine.h   |  2 +-
 3 files changed, 10 insertions(+), 14 deletions(-)

diff --git a/src/newgrf.cpp b/src/newgrf.cpp
index 0b8628f370..2444e82121 100644
--- a/src/newgrf.cpp
+++ b/src/newgrf.cpp
@@ -5611,8 +5611,7 @@ static bool IsValidGroupID(uint16_t groupid, const char *function)
 
 static void VehicleMapSpriteGroup(ByteReader *buf, uint8_t feature, uint8_t idcount)
 {
-	static EngineID *last_engines;
-	static uint last_engines_count;
+	static std::vector<EngineID> last_engines; // Engine IDs are remembered in case the next action is a wagon override.
 	bool wagover = false;
 
 	/* Test for 'wagon override' flag */
@@ -5621,21 +5620,18 @@ static void VehicleMapSpriteGroup(ByteReader *buf, uint8_t feature, uint8_t idco
 		/* Strip off the flag */
 		idcount = GB(idcount, 0, 7);
 
-		if (last_engines_count == 0) {
+		if (last_engines.empty()) {
 			GrfMsg(0, "VehicleMapSpriteGroup: WagonOverride: No engine to do override with");
 			return;
 		}
 
-		GrfMsg(6, "VehicleMapSpriteGroup: WagonOverride: {} engines, {} wagons",
-				last_engines_count, idcount);
+		GrfMsg(6, "VehicleMapSpriteGroup: WagonOverride: {} engines, {} wagons", last_engines.size(), idcount);
 	} else {
-		if (last_engines_count != idcount) {
-			last_engines = ReallocT(last_engines, idcount);
-			last_engines_count = idcount;
-		}
+		last_engines.resize(idcount);
 	}
 
 	std::vector<EngineID> engines;
+	engines.reserve(idcount);
 	for (uint i = 0; i < idcount; i++) {
 		Engine *e = GetNewEngine(_cur.grffile, (VehicleType)feature, buf->ReadExtendedByte());
 		if (e == nullptr) {
@@ -5667,7 +5663,7 @@ static void VehicleMapSpriteGroup(ByteReader *buf, uint8_t feature, uint8_t idco
 			GrfMsg(7, "VehicleMapSpriteGroup: [{}] Engine {}...", i, engine);
 
 			if (wagover) {
-				SetWagonOverrideSprites(engine, cid, _cur.spritegroups[groupid], last_engines, last_engines_count);
+				SetWagonOverrideSprites(engine, cid, _cur.spritegroups[groupid], last_engines);
 			} else {
 				SetCustomEngineSprites(engine, cid, _cur.spritegroups[groupid]);
 			}
@@ -5683,7 +5679,7 @@ static void VehicleMapSpriteGroup(ByteReader *buf, uint8_t feature, uint8_t idco
 		EngineID engine = engines[i];
 
 		if (wagover) {
-			SetWagonOverrideSprites(engine, SpriteGroupCargo::SG_DEFAULT, _cur.spritegroups[groupid], last_engines, last_engines_count);
+			SetWagonOverrideSprites(engine, SpriteGroupCargo::SG_DEFAULT, _cur.spritegroups[groupid], last_engines);
 		} else {
 			SetCustomEngineSprites(engine, SpriteGroupCargo::SG_DEFAULT, _cur.spritegroups[groupid]);
 			SetEngineGRF(engine, _cur.grffile);
diff --git a/src/newgrf_engine.cpp b/src/newgrf_engine.cpp
index 0b7e6e08e7..4a5abcdce0 100644
--- a/src/newgrf_engine.cpp
+++ b/src/newgrf_engine.cpp
@@ -27,7 +27,7 @@
 
 #include "safeguards.h"
 
-void SetWagonOverrideSprites(EngineID engine, CargoID cargo, const SpriteGroup *group, EngineID *train_id, uint trains)
+void SetWagonOverrideSprites(EngineID engine, CargoID cargo, const SpriteGroup *group, std::span<EngineID> engine_ids)
 {
 	Engine *e = Engine::Get(engine);
 
@@ -36,7 +36,7 @@ void SetWagonOverrideSprites(EngineID engine, CargoID cargo, const SpriteGroup *
 	WagonOverride *wo = &e->overrides.emplace_back();
 	wo->group = group;
 	wo->cargo = cargo;
-	wo->engines.assign(train_id, train_id + trains);
+	wo->engines.assign(engine_ids.begin(), engine_ids.end());
 }
 
 const SpriteGroup *GetWagonOverrideSpriteSet(EngineID engine, CargoID cargo, EngineID overriding_engine)
diff --git a/src/newgrf_engine.h b/src/newgrf_engine.h
index 527942a0a3..a2795a8d2c 100644
--- a/src/newgrf_engine.h
+++ b/src/newgrf_engine.h
@@ -76,7 +76,7 @@ static const uint VEHICLEINFO_FULL_VEHICLE_WIDTH    = 32;
 
 struct VehicleSpriteSeq;
 
-void SetWagonOverrideSprites(EngineID engine, CargoID cargo, const struct SpriteGroup *group, EngineID *train_id, uint trains);
+void SetWagonOverrideSprites(EngineID engine, CargoID cargo, const struct SpriteGroup *group, std::span<EngineID> engine_ids);
 const SpriteGroup *GetWagonOverrideSpriteSet(EngineID engine, CargoID cargo, EngineID overriding_engine);
 void SetCustomEngineSprites(EngineID engine, uint8_t cargo, const struct SpriteGroup *group);