Fix date cheat/scenario load not adjusting vehicle date of last service

src/cheat_gui.cpp

@@ -29,6 +29,7 @@
 #include "error.h"
 #include "network/network.h"
 #include "order_base.h"
+#include "vehicle_base.h"
 #include "currency.h"
 
 #include "widgets/cheat_widget.h"
@@ -111,6 +112,7 @@ static int32 ClickChangeDateCheat(int32 p1, int32 p2)
 	Date new_date = ConvertYMDToDate(p1, ymd.month, ymd.day);
 	LinkGraphSchedule::instance.ShiftDates(new_date - _date);
 	ShiftOrderDates(new_date - _date);
+	ShiftVehicleDates(new_date - _date);
 	SetDate(new_date, _date_fract);
 	EnginesMonthlyLoop();
 	InvalidateWindowClassesData(WC_BUILD_STATION, 0);

src/date.cpp

@@ -228,9 +228,9 @@ static void OnNewYear()
 		_cur_date_ymd.year--;
 		days_this_year = IsLeapYear(_cur_date_ymd.year) ? DAYS_IN_LEAP_YEAR : DAYS_IN_YEAR;
 		_date -= days_this_year;
-		for (Vehicle *v : Vehicle::Iterate()) v->date_of_last_service -= days_this_year;
 		for (LinkGraph *lg : LinkGraph::Iterate()) lg->ShiftDates(-days_this_year);
 		ShiftOrderDates(-days_this_year);
+		ShiftVehicleDates(-days_this_year);
 
 		/* Because the _date wraps here, and text-messages expire by game-days, we have to clean out
 		 *  all of them if the date is set back, else those messages will hang for ever */

src/toolbar_gui.cpp

@@ -1131,6 +1131,7 @@ void SetStartingYear(Year year)
 	/* If you open a savegame as scenario there may already be link graphs.*/
 	LinkGraphSchedule::instance.ShiftDates(new_date - _date);
 	ShiftOrderDates(new_date - _date);
+	ShiftVehicleDates(new_date - _date);
 	SetDate(new_date, 0);
 }
 

src/vehicle.cpp

@@ -4204,3 +4204,10 @@ void DumpVehicleStats(char *buffer, const char *last)
 		buffer += seprintf(buffer, last, "\n");
 	}
 }
+
+void ShiftVehicleDates(int interval)
+{
+	for (Vehicle *v : Vehicle::Iterate()) {
+		v->date_of_last_service += interval;
+	}
+}

src/vehicle_base.h

@@ -1427,4 +1427,6 @@ void ClearVehicleTickCaches();
 void RemoveFromOtherVehicleTickCache(const Vehicle *v);
 void UpdateAllVehiclesIsDrawn();
 
+void ShiftVehicleDates(int interval);
+
 #endif /* VEHICLE_BASE_H */