Fix infrastructure sharing checks not being executed when disabling

src/infrastructure.cpp

@@ -25,6 +25,7 @@
 #include "scope_info.h"
 #include "order_cmd.h"
 #include "strings_func.h"
+#include "scope.h"
 
 #include "table/strings.h"
 
@@ -238,13 +239,19 @@ static void FixAllReservations()
  * If vehicles are still on others' infrastructure or using others' stations,
  * The change is not possible and false is returned.
  * @param type The type of vehicle whose setting will be changed.
+ * @param new_value True if sharing will become enabled.
  * @return True if the change can take place, false otherwise.
  */
-bool CheckSharingChangePossible(VehicleType type)
+bool CheckSharingChangePossible(VehicleType type, bool new_value)
 {
 	if (type != VEH_AIRCRAFT) YapfNotifyTrackLayoutChange(INVALID_TILE, INVALID_TRACK);
 	/* Only do something when sharing is being disabled */
-	if (_settings_game.economy.infrastructure_sharing[type]) return true;
+	if (!_settings_game.economy.infrastructure_sharing[type] || new_value) return true;
+
+	_settings_game.economy.infrastructure_sharing[type] = false;
+	auto guard = scope_guard([type]() {
+		_settings_game.economy.infrastructure_sharing[type] = true;
+	});
 
 	StringID error_message = STR_NULL;
 	for (Vehicle *v : Vehicle::Iterate()) {

src/infrastructure_func.h

@@ -19,7 +19,7 @@
 void PayStationSharingFee(Vehicle *v, const Station *st);
 void PayDailyTrackSharingFee(Train *v);
 
-bool CheckSharingChangePossible(VehicleType type);
+bool CheckSharingChangePossible(VehicleType type, bool new_value);
 void HandleSharingCompanyDeletion(Owner owner);
 void UpdateAllBlockSignals(Owner owner = INVALID_OWNER);
 

src/settings.cpp

@@ -1617,7 +1617,7 @@ static void StationCatchmentChanged(int32 new_value)
 
 static bool CheckSharingRail(int32 &new_value)
 {
-	return CheckSharingChangePossible(VEH_TRAIN);
+	return CheckSharingChangePossible(VEH_TRAIN, new_value);
 }
 
 static void SharingRailChanged(int32 new_value)
@@ -1627,17 +1627,17 @@ static void SharingRailChanged(int32 new_value)
 
 static bool CheckSharingRoad(int32 &new_value)
 {
-	return CheckSharingChangePossible(VEH_ROAD);
+	return CheckSharingChangePossible(VEH_ROAD, new_value);
 }
 
 static bool CheckSharingWater(int32 &new_value)
 {
-	return CheckSharingChangePossible(VEH_SHIP);
+	return CheckSharingChangePossible(VEH_SHIP, new_value);
 }
 
 static bool CheckSharingAir(int32 &new_value)
 {
-	return CheckSharingChangePossible(VEH_AIRCRAFT);
+	return CheckSharingChangePossible(VEH_AIRCRAFT, new_value);
 }
 
 static void MaxVehiclesChanged(int32 new_value)