(svn r21975) -Add: console command to reset the engine pool. It removes the traces of engines which are no longer associated to a NewGRF, and can be used to e.g. 'fix' scenarios which were screwed up by the author. You can only use it when there are no vehicles in the game though.

src/console_cmds.cpp

@@ -35,6 +35,7 @@
 #include "ai/ai_config.hpp"
 #include "newgrf.h"
 #include "console_func.h"
+#include "engine_base.h"
 
 #ifdef ENABLE_NETWORK
 	#include "table/strings.h"
@@ -141,6 +142,26 @@ DEF_CONSOLE_CMD(ConResetEngines)
 	return true;
 }
 
+DEF_CONSOLE_CMD(ConResetEnginePool)
+{
+	if (argc == 0) {
+		IConsoleHelp("Reset NewGRF allocations of engine slots. This will remove invalid engine definitions, and might make default engines available again.");
+		return true;
+	}
+
+	if (_game_mode == GM_MENU) {
+		IConsoleError("This command is only available in game and editor.");
+		return true;
+	}
+
+	if (!EngineOverrideManager::ResetToCurrentNewGRFConfig()) {
+		IConsoleError("This can only be done when there are no vehicles in the game.");
+		return true;
+	}
+
+	return true;
+}
+
 #ifdef _DEBUG
 DEF_CONSOLE_CMD(ConResetTile)
 {
@@ -1781,6 +1802,7 @@ void IConsoleStdLibRegister()
 	IConsoleCmdRegister("getdate",      ConGetDate);
 	IConsoleCmdRegister("quit",         ConExit);
 	IConsoleCmdRegister("resetengines", ConResetEngines, ConHookNoNetwork);
+	IConsoleCmdRegister("reset_enginepool", ConResetEnginePool, ConHookNoNetwork);
 	IConsoleCmdRegister("return",       ConReturn);
 	IConsoleCmdRegister("screenshot",   ConScreenShot);
 	IConsoleCmdRegister("script",       ConScript);

src/engine.cpp

@@ -29,6 +29,7 @@
 #include "engine_func.h"
 #include "engine_base.h"
 #include "company_base.h"
+#include "vehicle_func.h"
 
 #include "table/strings.h"
 #include "table/engines.h"
@@ -429,6 +430,25 @@ EngineID EngineOverrideManager::GetID(VehicleType type, uint16 grf_local_id, uin
 	return INVALID_ENGINE;
 }
 
+/**
+ * Tries to reset the engine mapping to match the current NewGRF configuration.
+ * This is only possible when there are currently no vehicles in the game.
+ * @return false if resetting failed due to present vehicles.
+ */
+bool EngineOverrideManager::ResetToCurrentNewGRFConfig()
+{
+	const Vehicle *v;
+	FOR_ALL_VEHICLES(v) {
+		if (IsCompanyBuildableVehicleType(v)) return false;
+	}
+
+	/* Reset the engines, they will get new EngineIDs */
+	_engine_mngr.ResetToDefaultMapping();
+	ReloadNewGRFData();
+
+	return true;
+}
+
 /**
  * Sets cached values in Company::num_vehicles and Group::num_vehicles
  */

src/engine_base.h

@@ -114,6 +114,8 @@ struct EngineOverrideManager : SmallVector<EngineIDMapping, 256> {
 
 	void ResetToDefaultMapping();
 	EngineID GetID(VehicleType type, uint16 grf_local_id, uint32 grfid);
+
+	static bool ResetToCurrentNewGRFConfig();
 };
 
 extern EngineOverrideManager _engine_mngr;

src/settings.cpp

@@ -36,7 +36,6 @@
 #include "train.h"
 #include "news_func.h"
 #include "window_func.h"
-#include "vehicle_func.h"
 #include "sound_func.h"
 #include "company_func.h"
 #include "rev.h"
@@ -58,7 +57,6 @@
 #include "ini_type.h"
 #include "ai/ai_config.hpp"
 #include "ai/ai.hpp"
-#include "newgrf.h"
 #include "ship.h"
 #include "smallmap_gui.h"
 #include "roadveh.h"
@@ -1133,18 +1131,11 @@ static bool ChangeDynamicEngines(int32 p1)
 {
 	if (_game_mode == GM_MENU) return true;
 
-	const Vehicle *v;
+	if (!EngineOverrideManager::ResetToCurrentNewGRFConfig()) {
-	FOR_ALL_VEHICLES(v) {
+		ShowErrorMessage(STR_CONFIG_SETTING_DYNAMIC_ENGINES_EXISTING_VEHICLES, INVALID_STRING_ID, WL_ERROR);
-		if (IsCompanyBuildableVehicleType(v)) {
+		return false;
-			ShowErrorMessage(STR_CONFIG_SETTING_DYNAMIC_ENGINES_EXISTING_VEHICLES, INVALID_STRING_ID, WL_ERROR);
-			return false;
-		}
 	}
 
-	/* Reset the engines, they will get new EngineIDs */
-	_engine_mngr.ResetToDefaultMapping();
-	ReloadNewGRFData();
-
 	return true;
 }
 

src/terraform_gui.cpp

@@ -31,6 +31,7 @@
 #include "newgrf_object.h"
 #include "object.h"
 #include "hotkeys.h"
+#include "engine_base.h"
 
 #include "table/strings.h"
 
@@ -560,6 +561,9 @@ static void ResetLandscapeConfirmationCallback(Window *w, bool confirmed)
 			if (!st->IsInUse()) delete st;
 		}
 
+		/* Now that all vehicles are gone, we can reset the engine pool. Maybe it reduces some NewGRF changing-mess */
+		EngineOverrideManager::ResetToCurrentNewGRFConfig();
+
 		MarkWholeScreenDirty();
 	}
 }