Codechange: Add town production effect type and assign to cargo types.

src/cargotype.cpp

@@ -22,6 +22,7 @@
 #include "safeguards.h"
 
 CargoSpec CargoSpec::array[NUM_CARGO];
+std::array<std::vector<const CargoSpec *>, NUM_TPE> CargoSpec::town_production_cargoes{};
 
 /**
  * Bitmask of cargo types available. This includes phony cargoes like regearing cargoes.
@@ -192,6 +193,7 @@ static bool CargoSpecClassSorter(const CargoSpec * const &a, const CargoSpec * c
 /** Initialize the list of sorted cargo specifications. */
 void InitializeSortedCargoSpecs()
 {
+	for (auto &tpc : CargoSpec::town_production_cargoes) tpc.clear();
 	_sorted_cargo_specs.clear();
 	/* Add each cargo spec to the list, and determine the largest cargo icon size. */
 	for (const CargoSpec *cargo : CargoSpec::Iterate()) {
@@ -210,6 +212,8 @@ void InitializeSortedCargoSpecs()
 	_standard_cargo_mask = 0;
 	uint8_t nb_standard_cargo = 0;
 	for (const auto &cargo : _sorted_cargo_specs) {
+		assert(cargo->town_production_effect != INVALID_TPE);
+		CargoSpec::town_production_cargoes[cargo->town_production_effect].push_back(cargo);
 		if (cargo->classes & CC_SPECIAL) break;
 		nb_standard_cargo++;
 		SetBit(_standard_cargo_mask, cargo->Index());

src/cargotype.h

@@ -33,6 +33,20 @@ enum TownAcceptanceEffect : byte {
 	NUM_TAE = TAE_END, ///< Amount of town effects.
 };
 
+/** Town effect when producing cargo. */
+enum TownProductionEffect : byte {
+	TPE_NONE, ///< Town will not produce this cargo type.
+	TPE_PASSENGERS, ///< Cargo behaves passenger-like for production.
+	TPE_MAIL, ///< Cargo behaves mail-like for production.
+	NUM_TPE,
+
+	/**
+	 * Invalid town production effect. Used as a sentinel to indicate if a NewGRF has explicitly set an effect.
+	 * This does not 'exist' after cargo types are finalised.
+	 */
+	INVALID_TPE,
+};
+
 /** Cargo classes. */
 enum CargoClass {
 	CC_NOAVAILABLE  = 0,       ///< No cargo class has been specified
@@ -65,6 +79,7 @@ struct CargoSpec {
 
 	bool is_freight;                 ///< Cargo type is considered to be freight (affects train freight multiplier).
 	TownAcceptanceEffect town_acceptance_effect; ///< The effect that delivering this cargo type has on towns. Also affects destination of subsidies.
+	TownProductionEffect town_production_effect{INVALID_TPE}; ///< The effect on town cargo production.
 	uint8_t callback_mask;             ///< Bitmask of cargo callbacks that have to be called
 
 	StringID name;                   ///< Name of this type of cargo.
@@ -171,6 +186,9 @@ struct CargoSpec {
 	 */
 	static IterateWrapper Iterate(size_t from = 0) { return IterateWrapper(from); }
 
+	/** List of cargo specs for each Town Product Effect. */
+	static std::array<std::vector<const CargoSpec *>, NUM_TPE> town_production_cargoes;
+
 private:
 	static CargoSpec array[NUM_CARGO]; ///< Array holding all CargoSpecs
 

src/newgrf.cpp

@@ -9186,6 +9186,14 @@ static void FinaliseEngineArray()
 void FinaliseCargoArray()
 {
 	for (CargoSpec &cs : CargoSpec::array) {
+		if (cs.town_production_effect == INVALID_TPE) {
+			/* Set default town production effect by cargo label. */
+			switch (cs.label) {
+				case 'PASS': cs.town_production_effect = TPE_PASSENGERS; break;
+				case 'MAIL': cs.town_production_effect = TPE_MAIL; break;
+				default:     cs.town_production_effect = TPE_NONE; break;
+			}
+		}
 		if (!cs.IsValid()) {
 			cs.name = cs.name_single = cs.units_volume = STR_NEWGRF_INVALID_CARGO;
 			cs.quantifier = STR_NEWGRF_INVALID_CARGO_QUANTITY;

src/table/cargo_const.h

@@ -44,7 +44,7 @@
  * @param classes      Classes of this cargo type. @see CargoClass
  */
 #define MK(bt, label, colour, weight, mult, ip, td1, td2, freight, tae, str_plural, str_singular, str_volume, classes) \
-		{label, bt, colour, colour, weight, mult, classes, ip, {td1, td2}, freight, tae, 0, \
+		{label, bt, colour, colour, weight, mult, classes, ip, {td1, td2}, freight, tae, INVALID_TPE, 0, \
 		MK_STR_CARGO_PLURAL(str_plural), MK_STR_CARGO_SINGULAR(str_singular), str_volume, MK_STR_QUANTITY(str_plural), MK_STR_ABBREV(str_plural), \
 		MK_SPRITE(str_plural), nullptr, nullptr, 0}