Add setting to disable vehicle expiry after a given year

src/engine.cpp

@@ -578,6 +578,18 @@ static bool IsWagon(EngineID index)
 	return e->type == VEH_TRAIN && e->u.rail.railveh_type == RAILVEH_WAGON;
 }
 
+static void RetireEngineIfPossible(Engine *e, int age_threshold)
+{
+	if (_settings_game.vehicle.no_expire_vehicles_after > 0) {
+		YearMonthDay ymd;
+		ConvertDateToYMD(e->intro_date, &ymd);
+		if ((ymd.year * 12) + ymd.month + age_threshold >= _settings_game.vehicle.no_expire_vehicles_after * 12) return;
+	}
+
+	e->company_avail = 0;
+	AddRemoveEngineFromAutoreplaceAndBuildWindows(e->type);
+}
+
 /**
  * Update #Engine::reliability and (if needed) update the engine GUIs.
  * @param e %Engine to update.
@@ -592,8 +604,7 @@ static void CalcEngineReliability(Engine *e)
 		uint retire_early_max_age = max(0, e->duration_phase_1 + e->duration_phase_2 - retire_early * 12);
 		if (retire_early != 0 && age >= retire_early_max_age) {
 			/* Early retirement is enabled and we're past the date... */
-			e->company_avail = 0;
-			AddRemoveEngineFromAutoreplaceAndBuildWindows(e->type);
+			RetireEngineIfPossible(e, retire_early_max_age);
 		}
 	}
 
@@ -608,12 +619,11 @@ static void CalcEngineReliability(Engine *e)
 		uint max = e->reliability_max;
 		e->reliability = (int)age * (int)(e->reliability_final - max) / e->duration_phase_3 + max;
 	} else {
+		e->reliability = e->reliability_final;
 		/* time's up for this engine.
 		 * We will now completely retire this design */
-		e->company_avail = 0;
-		e->reliability = e->reliability_final;
 		/* Kick this engine out of the lists */
-		AddRemoveEngineFromAutoreplaceAndBuildWindows(e->type);
+		RetireEngineIfPossible(e, e->duration_phase_1 + e->duration_phase_2 + e->duration_phase_3);
 	}
 	SetWindowClassesDirty(WC_BUILD_VEHICLE); // Update to show the new reliability
 	SetWindowClassesDirty(WC_REPLACE_VEHICLE);

src/lang/english.txt

@@ -1326,6 +1326,10 @@ STR_CONFIG_SETTING_WARN_INCOME_LESS                             :Warn if a vehic
 STR_CONFIG_SETTING_WARN_INCOME_LESS_HELPTEXT                    :When enabled, a news message gets sent when a vehicle has not made any profit within a calendar year
 STR_CONFIG_SETTING_NEVER_EXPIRE_VEHICLES                        :Vehicles never expire: {STRING2}
 STR_CONFIG_SETTING_NEVER_EXPIRE_VEHICLES_HELPTEXT               :When enabled, all vehicle models remain available forever after their introduction
+STR_CONFIG_SETTING_NO_EXPIRE_VEHICLES_AFTER                     :No vehicles expire after: {STRING2}
+STR_CONFIG_SETTING_NO_EXPIRE_VEHICLES_AFTER_HELPTEXT            :Vehicles which would otherwise expire after this year remain available forever
+STR_CONFIG_SETTING_NO_EXPIRE_VEHICLES_AFTER_VALUE               :{NUM}
+STR_CONFIG_SETTING_NO_EXPIRE_VEHICLES_AFTER_ZERO                :Off
 STR_CONFIG_SETTING_AUTORENEW_VEHICLE                            :Autorenew vehicle when it gets old: {STRING2}
 STR_CONFIG_SETTING_AUTORENEW_VEHICLE_HELPTEXT                   :When enabled, a vehicle nearing its end of life gets automatically replaced when the renew conditions are fulfilled
 STR_CONFIG_SETTING_AUTORENEW_MONTHS                             :Autorenew when vehicle is {STRING2} maximum age

src/settings_gui.cpp

@@ -1848,6 +1848,7 @@ static SettingsContainer &GetSettingsTree()
 			limitations->Add(new SettingEntry("construction.chunnel"));
 			limitations->Add(new SettingEntry("station.never_expire_airports"));
 			limitations->Add(new SettingEntry("vehicle.never_expire_vehicles"));
+			limitations->Add(new SettingEntry("vehicle.no_expire_vehicles_after"));
 			limitations->Add(new SettingEntry("vehicle.max_trains"));
 			limitations->Add(new SettingEntry("vehicle.max_roadveh"));
 			limitations->Add(new SettingEntry("vehicle.max_aircraft"));

src/settings_type.h

@@ -540,6 +540,7 @@ struct VehicleSettings {
 	uint8  freight_trains;                   ///< value to multiply the weight of cargo by
 	bool   dynamic_engines;                  ///< enable dynamic allocation of engine data
 	bool   never_expire_vehicles;            ///< never expire vehicles
+	Year   no_expire_vehicles_after;         ///< do not expire vehicles ater this year
 	byte   extend_vehicle_life;              ///< extend vehicle life by this many years
 	byte   road_side;                        ///< the side of the road vehicles drive on
 	uint8  plane_crashes;                    ///< number of plane crashes, 0 = none, 1 = reduced, 2 = normal

src/table/settings.ini

@@ -1379,6 +1379,21 @@ def      = false
 str      = STR_CONFIG_SETTING_NEVER_EXPIRE_VEHICLES
 strhelp  = STR_CONFIG_SETTING_NEVER_EXPIRE_VEHICLES_HELPTEXT
 
+[SDT_VAR]
+base     = GameSettings
+var      = vehicle.no_expire_vehicles_after
+type     = SLE_INT32
+guiflags = SGF_NO_NETWORK | SGF_0ISDISABLED
+def      = 0
+min      = MIN_YEAR
+max      = MAX_YEAR
+interval = 1
+str      = STR_CONFIG_SETTING_NO_EXPIRE_VEHICLES_AFTER
+strhelp  = STR_CONFIG_SETTING_NO_EXPIRE_VEHICLES_AFTER_HELPTEXT
+strval   = STR_CONFIG_SETTING_NO_EXPIRE_VEHICLES_AFTER_VALUE
+cat      = SC_EXPERT
+patxname = ""vehicle.no_expire_vehicles_after""
+
 ;; vehicle.exact_intro_date
 [SDT_NULL]
 length   = 1