Codechange: Let the compile generate the master command table out of templated command traits.

This is using a non-intrusive type-traits like templated system, which
allows compile-time validation that the command table and the command
enum match up.

src/train_cmd.h

@@ -0,0 +1,28 @@
+/*
+ * This file is part of OpenTTD.
+ * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
+ * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** @file train_cmd.h Command definitions related to trains. */
+
+#ifndef TRAIN_CMD_H
+#define TRAIN_CMD_H
+
+#include "command_type.h"
+#include "engine_type.h"
+#include "vehicle_type.h"
+
+CommandCost CmdBuildRailVehicle(TileIndex tile, DoCommandFlag flags, const Engine *e, uint16 data, Vehicle **v);
+CommandCost CmdSellRailWagon(DoCommandFlag flags, Vehicle *v, uint16 data, uint32 user);
+
+CommandProc CmdMoveRailVehicle;
+CommandProc CmdForceTrainProceed;
+CommandProc CmdReverseTrainDirection;
+
+DEF_CMD_TRAIT(CMD_MOVE_RAIL_VEHICLE,       CmdMoveRailVehicle,       0, CMDT_VEHICLE_CONSTRUCTION)
+DEF_CMD_TRAIT(CMD_FORCE_TRAIN_PROCEED,     CmdForceTrainProceed,     0, CMDT_VEHICLE_MANAGEMENT)
+DEF_CMD_TRAIT(CMD_REVERSE_TRAIN_DIRECTION, CmdReverseTrainDirection, 0, CMDT_VEHICLE_MANAGEMENT)
+
+#endif /* TRAIN_CMD_H */