Adjust signal speed restriction timeouts when date or day length changed

src/settings.cpp

@@ -1793,7 +1793,12 @@ static bool ImprovedBreakdownsSettingChanged(int32 p1)
 
 static bool DayLengthChanged(int32 p1)
 {
+	const DateTicksScaled old_scaled_date_ticks = _scaled_date_ticks;
 	SetScaledTickVariables();
+
+	extern void AdjustAllSignalSpeedRestrictionTickValues(DateTicksScaled delta);
+	AdjustAllSignalSpeedRestrictionTickValues(_scaled_date_ticks - old_scaled_date_ticks);
+
 	MarkWholeScreenDirty();
 	return true;
 }

src/train_cmd.cpp

@@ -122,6 +122,13 @@ void ClearAllSignalSpeedRestrictions()
 	_signal_speeds.clear();
 }
 
+void AdjustAllSignalSpeedRestrictionTickValues(DateTicksScaled delta)
+{
+	for (auto &it : _signal_speeds) {
+		it.second.time_stamp += delta;
+	}
+}
+
 /** Removes all speed restrictions which have passed their timeout from all signals */
 void ClearOutOfDateSignalSpeedRestrictions()
 {

src/vehicle.cpp

@@ -4310,4 +4310,7 @@ void ShiftVehicleDates(int interval)
 	for (Vehicle *v : Vehicle::Iterate()) {
 		v->date_of_last_service += interval;
 	}
+
+	extern void AdjustAllSignalSpeedRestrictionTickValues(DateTicksScaled delta);
+	AdjustAllSignalSpeedRestrictionTickValues(interval * DAY_TICKS * _settings_game.economy.day_length_factor);
 }