Fix #15495: unable to build bridge over default waypoints

src/station_cmd.cpp

@@ -1226,16 +1226,9 @@ CommandCost CanExpandRailStation(const BaseStation *st, TileArea &new_ta)
 	return CommandCost();
 }
 
-RailStationTileLayout::RailStationTileLayout(const StationSpec *spec, uint8_t platforms, uint8_t length) : platforms(platforms), length(length)
-{
-	if (spec == nullptr) return;
-
-	/* Look for a predefined layout for the required size. */
-	auto found = spec->layouts.find(GetStationLayoutKey(platforms, length));
-	if (found != std::end(spec->layouts)) this->layout = found->second;
-}
-
-StationGfx RailStationTileLayout::Iterator::operator*() const
+/** @copydoc RailStationTileLayout::Iterator::operator* */
+template <>
+StationGfx RailStationTileLayout<StationType::Rail>::Iterator::operator*() const
 {
 	/* Use predefined layout if it exists. Mask bit zero which will indicate axis. */
 	if (!stl.layout.empty()) return this->stl.layout[this->position] & ~1;
@@ -1515,7 +1508,7 @@ CommandCost CmdBuildRailStation(DoCommandFlags flags, TileIndex tile_org, RailTy
 	TileIndexDiff tile_delta = TileOffsByAxis(axis); // offset to go to the next platform tile
 	TileIndexDiff track_delta = TileOffsByAxis(OtherAxis(axis)); // offset to go to the next track
 
-	RailStationTileLayout stl{statspec, numtracks, plat_len};
+	RailStationTileLayout<StationType::Rail> stl{statspec, numtracks, plat_len};
 	for (auto [i, it, tile_track] = std::make_tuple(0, stl.begin(), tile_org); i != numtracks; ++i, tile_track += track_delta) {
 		for (auto [j, tile] = std::make_tuple(0, tile_track); j != plat_len; ++j, tile += tile_delta, ++it) {
 			/* Don't check the layout if there's no bridge above anyway. */

src/station_layout_type.h

@@ -13,13 +13,21 @@
 #include "newgrf_station.h"
 #include "station_map.h"
 
+template <StationType T>
 class RailStationTileLayout {
 private:
 	std::span<const StationGfx> layout{}; ///< Predefined tile layout.
 	uint platforms; ///< Number of platforms.
 	uint length; ///< Length of platforms.
 public:
-	RailStationTileLayout(const StationSpec *spec, uint8_t platforms, uint8_t length);
+	RailStationTileLayout(const StationSpec *spec, uint8_t platforms, uint8_t length) : platforms(platforms), length(length)
+	{
+		if (spec == nullptr) return;
+
+		/* Look for a predefined layout for the required size. */
+		auto found = spec->layouts.find(GetStationLayoutKey(platforms, length));
+		if (found != std::end(spec->layouts)) this->layout = found->second;
+	}
 
 	class Iterator {
 		const RailStationTileLayout &stl; ///< Station tile layout being iterated.
@@ -36,6 +44,10 @@ public:
 		bool operator==(const Iterator &rhs) const { return this->position == rhs.position; }
 		bool operator==(const std::default_sentinel_t &) const { return this->position == this->stl.platforms * this->stl.length; }
 
+		/**
+		 * Dereference operator.
+		 * @return The StationGfx value associated with the index this iterator points to.
+		 */
 		StationGfx operator*() const;
 
 		Iterator &operator++()

src/waypoint_cmd.cpp

@@ -192,6 +192,16 @@ extern CommandCost IsBuoyBridgeAboveOk(TileIndex tile);
 
 extern CommandCost RemoveRoadWaypointStop(TileIndex tile, DoCommandFlags flags, int replacement_spec_index);
 
+/** @copydoc RailStationTileLayout::Iterator::operator* */
+template <>
+StationGfx RailStationTileLayout<StationType::RailWaypoint>::Iterator::operator*() const
+{
+	/* Use predefined layout if it exists. Mask bit zero which will indicate axis. */
+	if (!stl.layout.empty()) return this->stl.layout[this->position] & ~1;
+
+	return 0;
+}
+
 /**
  * Convert existing rail to waypoint. Eg build a waypoint station over
  * piece of rail
@@ -239,7 +249,7 @@ CommandCost CmdBuildRailWaypoint(DoCommandFlags flags, TileIndex start_tile, Axi
 	StationID est = StationID::Invalid();
 
 	const StationSpec *spec = StationClass::Get(spec_class)->GetSpec(spec_index);
-	RailStationTileLayout stl{spec, count, 1};
+	RailStationTileLayout<StationType::RailWaypoint> stl{spec, count, 1};
 
 	/* Check whether the tiles we're building on are valid rail or not. */
 	TileIndexDiff offset = TileOffsByAxis(OtherAxis(axis));