Feature: Allow vehicle replacements even if new road or rail type is not compatible.

src/autoreplace_cmd.cpp

@@ -71,7 +71,10 @@ bool CheckAutoreplaceValidity(EngineID from, EngineID to, CompanyID company)
 	switch (type) {
 		case VEH_TRAIN: {
 			/* make sure the railtypes are compatible */
-			if ((GetRailTypeInfo(e_from->u.rail.railtype)->compatible_railtypes & GetRailTypeInfo(e_to->u.rail.railtype)->compatible_railtypes) == 0) return false;
+			if (!_settings_game.depot.allow_no_comp_railtype_replacements &&
+					(GetRailTypeInfo(e_from->u.rail.railtype)->compatible_railtypes & GetRailTypeInfo(e_to->u.rail.railtype)->compatible_railtypes) == 0) {
+				return false;
+			}
 
 			/* make sure we do not replace wagons with engines or vice versa */
 			if ((e_from->u.rail.railveh_type == RAILVEH_WAGON) != (e_to->u.rail.railveh_type == RAILVEH_WAGON)) return false;
@@ -79,11 +82,15 @@ bool CheckAutoreplaceValidity(EngineID from, EngineID to, CompanyID company)
 		}
 
 		case VEH_ROAD:
-			/* make sure the roadtypes are compatible */
+			if (!_settings_game.depot.allow_no_comp_roadtype_replacements) {
-			if ((GetRoadTypeInfo(e_from->u.road.roadtype)->powered_roadtypes & GetRoadTypeInfo(e_to->u.road.roadtype)->powered_roadtypes) == ROADTYPES_NONE) return false;
+				/* make sure the roadtypes are compatible */
+				if ((GetRoadTypeInfo(e_from->u.road.roadtype)->powered_roadtypes & GetRoadTypeInfo(e_to->u.road.roadtype)->powered_roadtypes) == ROADTYPES_NONE) {
+					return false;
+				}
 
-			/* make sure that we do not replace a tram with a normal road vehicles or vice versa */
+				/* make sure that we do not replace a tram with a normal road vehicles or vice versa */
-			if (HasBit(e_from->info.misc_flags, EF_ROAD_TRAM) != HasBit(e_to->info.misc_flags, EF_ROAD_TRAM)) return false;
+				if (HasBit(e_from->info.misc_flags, EF_ROAD_TRAM) != HasBit(e_to->info.misc_flags, EF_ROAD_TRAM)) return false;
+			}
 			break;
 
 		case VEH_AIRCRAFT:

src/lang/english.txt

@@ -1464,6 +1464,7 @@ STR_CONFIG_SETTING_STOP_ON_TOWN_ROAD_HELPTEXT                   :Allow construct
 STR_CONFIG_SETTING_STOP_ON_COMPETITOR_ROAD                      :Allow drive-through road stops on roads owned by competitors: {STRING2}
 STR_CONFIG_SETTING_STOP_ON_COMPETITOR_ROAD_HELPTEXT             :Allow construction of drive-through road stops on roads owned by other companies
 STR_CONFIG_SETTING_DYNAMIC_ENGINES_EXISTING_VEHICLES            :{WHITE}Changing this setting is not possible when there are vehicles
+STR_CONFIG_SETTING_REPLACEMENTS_DIFF_TYPE                       :{WHITE}Disabling this setting is not possible during a game
 
 STR_CONFIG_SETTING_INFRASTRUCTURE_MAINTENANCE                   :Infrastructure maintenance: {STRING2}
 STR_CONFIG_SETTING_INFRASTRUCTURE_MAINTENANCE_HELPTEXT          :When enabled, infrastructure causes maintenance costs. The cost grows over-proportional with the network size, thus affecting bigger companies more than smaller ones
@@ -1621,6 +1622,10 @@ STR_CONFIG_SETTING_DISTANT_JOIN_DEPOTS                          :Allow to join d
 STR_CONFIG_SETTING_DISTANT_JOIN_DEPOTS_HELPTEXT                 :Allow adding parts to a depot without directly touching the existing parts. Needs Ctrl+Click while placing the new parts
 STR_CONFIG_SETTING_DEPOT_SPREAD                                 :Maximum depot spread: {STRING2}
 STR_CONFIG_SETTING_DEPOT_SPREAD_HELPTEXT                        :Maximum area the parts of a single depot may be spread out on
+STR_CONFIG_SETTING_REPLACE_INCOMPATIBLE_RAIL                    :Allow replacing rail vehicles with incompatible rail types: {STRING2}
+STR_CONFIG_SETTING_REPLACE_INCOMPATIBLE_RAIL_HELPTEXT           :Allow replacing rail vehicles even if they are not compatible by rail type
+STR_CONFIG_SETTING_REPLACE_INCOMPATIBLE_ROAD                    :Allow replacing road vehicles with incompatible road types: {STRING2}
+STR_CONFIG_SETTING_REPLACE_INCOMPATIBLE_ROAD_HELPTEXT           :Allow replacing road vehicles even if they are not compatible by road type
 
 STR_CONFIG_SETTING_STATION_SPREAD                               :Maximum station spread: {STRING2}
 STR_CONFIG_SETTING_STATION_SPREAD_HELPTEXT                      :Maximum area the parts of a single station may be spread out on. Note that high values will slow the game

src/saveload/afterload.cpp

@@ -804,6 +804,11 @@ bool AfterLoadGame()
 		_settings_game.depot.distant_join_depots = true;
 	}
 
+	if (IsSavegameVersionBefore(SLV_ALLOW_INCOMPATIBLE_REPLACEMENTS)) {
+		_settings_game.depot.allow_no_comp_railtype_replacements = false;
+		_settings_game.depot.allow_no_comp_roadtype_replacements = false;
+	}
+
 	/* Load the sprites */
 	GfxLoadSprites();
 	LoadStringWidthTable();

src/saveload/saveload.h

@@ -389,6 +389,7 @@ enum SaveLoadVersion : uint16_t {
 	SLV_DEPOTID_BACKUP_ORDERS,              ///< 341  PR#XXXXX Backup orders are indexed through DepotIDs.
 	SLV_ADD_MEMBERS_TO_DEPOT_STRUCT,        ///< 342  PR#XXXXX Add some members to depot struct.
 	SLV_DEPOT_SPREAD,                       ///< 343  PR#XXXXX Add a setting for max depot spread.
+	SLV_ALLOW_INCOMPATIBLE_REPLACEMENTS,    ///< 344  PR#XXXXX Allow incompatible vehicle replacements.
 
 	SL_MAX_VERSION,                         ///< Highest possible saveload version
 };

src/settings_gui.cpp

@@ -2149,6 +2149,9 @@ static SettingsContainer &GetSettingsTree()
 			{
 				depots->Add(new SettingEntry("depot.depot_spread"));
 				depots->Add(new SettingEntry("depot.distant_join_depots"));
+
+				depots->Add(new SettingEntry("depot.allow_no_comp_railtype_replacements"));
+				depots->Add(new SettingEntry("depot.allow_no_comp_roadtype_replacements"));
 			}
 
 			limitations->Add(new SettingEntry("construction.command_pause_level"));

src/settings_table.cpp

@@ -380,6 +380,22 @@ static void SpriteZoomMinChanged(int32_t)
 	MarkWholeScreenDirty();
 }
 
+static bool CheckDifferentRailRoadTypesReplacements(int32_t &new_value)
+{
+	if (_game_mode == GM_NORMAL) {
+		if (new_value == 0) {
+			ShowErrorMessage(STR_CONFIG_SETTING_REPLACEMENTS_DIFF_TYPE, INVALID_STRING_ID, WL_ERROR);
+			return false;
+		}
+	}
+	return true;
+}
+
+static void InvalidateReplacementWindows(int32_t)
+{
+	InvalidateWindowClassesData(WC_REPLACE_VEHICLE);
+}
+
 /**
  * Update any possible saveload window and delete any newgrf dialogue as
  * its widget parts might change. Reinit all windows as it allows access to the

src/settings_type.h

@@ -574,6 +574,9 @@ struct StationSettings {
 struct DepotSettings {
 	uint8_t depot_spread;            ///< amount a depot may spread
 	bool    distant_join_depots;     ///< allow to join non-adjacent depots
+
+	bool    allow_no_comp_railtype_replacements;  ///< allow replacing rail vehicles even if rail type is not compatible
+	bool    allow_no_comp_roadtype_replacements;  ///< allow replacing road vehicles even if road type is not compatible
 };
 
 /** Default settings for vehicles. */

src/table/settings/game_settings.ini

@@ -21,6 +21,8 @@ static bool CheckRoadSide(int32_t &new_value);
 static bool CheckDynamicEngines(int32_t &new_value);
 static void StationCatchmentChanged(int32_t new_value);
 static void MaxVehiclesChanged(int32_t new_value);
+static bool CheckDifferentRailRoadTypesReplacements(int32_t &new_value);
+static void InvalidateReplacementWindows(int32_t new_value);
 
 static const SettingVariant _game_settings_table[] = {
 [post-amble]
@@ -166,6 +168,26 @@ strval   = STR_CONFIG_SETTING_TILE_LENGTH
 post_cb  = [](auto) { CloseWindowByClass(WC_SELECT_DEPOT); }
 cat      = SC_BASIC
 
+[SDT_BOOL]
+var      = depot.allow_no_comp_railtype_replacements
+from     = SLV_ALLOW_INCOMPATIBLE_REPLACEMENTS
+def      = false
+str      = STR_CONFIG_SETTING_REPLACE_INCOMPATIBLE_RAIL
+strhelp  = STR_CONFIG_SETTING_REPLACE_INCOMPATIBLE_RAIL_HELPTEXT
+pre_cb   = CheckDifferentRailRoadTypesReplacements
+post_cb  = InvalidateReplacementWindows
+cat      = SC_EXPERT
+
+[SDT_BOOL]
+var      = depot.allow_no_comp_roadtype_replacements
+from     = SLV_ALLOW_INCOMPATIBLE_REPLACEMENTS
+def      = false
+str      = STR_CONFIG_SETTING_REPLACE_INCOMPATIBLE_ROAD
+strhelp  = STR_CONFIG_SETTING_REPLACE_INCOMPATIBLE_ROAD_HELPTEXT
+pre_cb   = CheckDifferentRailRoadTypesReplacements
+post_cb  = InvalidateReplacementWindows
+cat      = SC_EXPERT
+
 [SDT_OMANY]
 var      = vehicle.road_side
 type     = SLE_UINT8