(svn r15541) -Revert (r15399): 'v->cargo_type' is also used in other places, which cannot accept CT_INVALID.

-Codechange: Add Engine::GetDefaultCargoType() and Engine::CanCarryCargo() and use them.
-Fix [FS#2617]: When articulated parts have no available default cargo, use the cargo type of the first part for livery selection.
-Change: To decide whether a vehicle is refittable do not test its current capacity for being zero, but always use the 'capacity property'.
  Note: The property is used unmodifed without calling CB 15/36. By setting it to a non-zero value and returning zero in the callback vehicles can be refitted to/from zero capacity for e.g. livery effects.
  Note: It is intentional that you cannot control refittability by CB 36.

1 files changed, 5 insertions, 10 deletions

diff --git a/src/aircraft_cmd.cpp b/src/aircraft_cmd.cpp
index 200e83653..fc3307218 100644
--- a/src/aircraft_cmd.cpp
+++ b/src/aircraft_cmd.cpp
@@ -254,6 +254,9 @@ CommandCost CmdBuildAircraft(TileIndex tile, DoCommandFlag flags, uint32 p1, uin
 	const Engine *e = GetEngine(p1);
 	CommandCost value(EXPENSES_NEW_VEHICLES, e->GetCost());
 
+	/* Engines without valid cargo should not be available */
+	if (e->GetDefaultCargoType() == CT_INVALID) return CMD_ERROR;
+
 	/* to just query the cost, it is not neccessary to have a valid tile (automation/AI) */
 	if (flags & DC_QUERY_COST) return value;
 
@@ -309,7 +312,7 @@ CommandCost CmdBuildAircraft(TileIndex tile, DoCommandFlag flags, uint32 p1, uin
 		v->cargo_cap = avi->passenger_capacity;
 		u->cargo_cap = avi->mail_capacity;
 
-		v->cargo_type = CT_PASSENGERS;
+		v->cargo_type = e->GetDefaultCargoType();
 		u->cargo_type = CT_MAIL;
 
 		v->cargo_subtype = 0;
@@ -334,17 +337,9 @@ CommandCost CmdBuildAircraft(TileIndex tile, DoCommandFlag flags, uint32 p1, uin
 		u->subtype = AIR_SHADOW;
 		u->UpdateDeltaXY(INVALID_DIR);
 
-		/* Danger, Will Robinson!
-		 * If the aircraft is refittable, but cannot be refitted to
-		 * passengers, we select the cargo type from the refit mask.
-		 * This is a fairly nasty hack to get around the fact that TTD
-		 * has no default cargo type specifier for planes... */
-		CargoID cargo = FindFirstRefittableCargo(p1);
-		if (cargo != CT_INVALID && cargo != CT_PASSENGERS) {
+		if (v->cargo_type != CT_PASSENGERS) {
 			uint16 callback = CALLBACK_FAILED;
 
-			v->cargo_type = cargo;
-
 			if (HasBit(EngInfo(p1)->callbackmask, CBM_VEHICLE_REFIT_CAPACITY)) {
 				callback = GetVehicleCallback(CBID_VEHICLE_REFIT_CAPACITY, 0, 0, v->engine_type, v);
 			}