Function ValidateTrains

src/train_cmd.cpp:1130–1140

* Validate whether we are going to create valid trains. * @note All vehicles are/were 'heads' of their chains. * @param original_dst The original destination chain. * @param dst The destination chain after constructing the train. * @param original_src The original source chain. * @param src The source chain after constructing the train. * @param check_limit Whether to chec

 * @return possible error of this command.
 */
static CommandCost ValidateTrains(Train *original_dst, Train *dst, Train *original_src, Train *src, bool check_limit)
{
	/* Check whether we may actually construct the trains. */
	CommandCost ret = CheckTrainAttachment(src);
	if (ret.Failed()) return ret;
	ret = CheckTrainAttachment(dst);
	if (ret.Failed()) return ret;

	/* Check whether we need to build a new train. */
	return check_limit ? CheckNewTrain(original_dst, dst, original_src, src) : CommandCost();
}

/**
 * Arrange the trains in the wanted way.