[core] Ensure that TileWorker can retain tileData after layout

src/mbgl/annotation/annotation_tile.cpp

@@ -40,6 +40,10 @@ optional<Value> AnnotationTileFeature::getValue(const std::string& key) const {
 AnnotationTileLayer::AnnotationTileLayer(std::string name_)
     : name(std::move(name_)) {}
 
+std::unique_ptr<GeometryTileData> AnnotationTileData::clone() const {
+    return std::make_unique<AnnotationTileData>(*this);
+}
+
 const GeometryTileLayer* AnnotationTileData::getLayer(const std::string& name) const {
     auto it = layers.find(name);
     if (it != layers.end()) {

src/mbgl/annotation/annotation_tile.hpp

@@ -56,6 +56,7 @@ private:
 
 class AnnotationTileData : public GeometryTileData {
 public:
+    std::unique_ptr<GeometryTileData> clone() const override;
     const GeometryTileLayer* getLayer(const std::string&) const override;
 
     std::unordered_map<std::string, AnnotationTileLayer> layers;

src/mbgl/tile/geojson_tile.cpp

@@ -55,6 +55,10 @@ public:
         : features(std::move(features_)) {
     }
 
+    std::unique_ptr<GeometryTileData> clone() const override {
+        return std::make_unique<GeoJSONTileData>(*this);
+    }
+
     const GeometryTileLayer* getLayer(const std::string&) const override {
         return this;
     }

src/mbgl/tile/geometry_tile.cpp

@@ -66,6 +66,8 @@ void GeometryTile::setData(std::unique_ptr<const GeometryTileData> data_) {
         workRequest.reset();
         availableData = DataAvailability::All;
         buckets.clear();
+        featureIndex.reset();
+        data.reset();
         redoPlacement();
         observer->onTileLoaded(*this, true);
         return;

src/mbgl/tile/geometry_tile_data.hpp

@@ -51,6 +51,7 @@ public:
 class GeometryTileData {
 public:
     virtual ~GeometryTileData() = default;
+    virtual std::unique_ptr<GeometryTileData> clone() const = 0;
     virtual const GeometryTileLayer* getLayer(const std::string&) const = 0;
 };
 

src/mbgl/tile/tile_worker.cpp

@@ -95,7 +95,7 @@ TileParseResult TileWorker::prepareResult(const PlacementConfig& config) {
     if (result.complete) {
         featureIndex->setCollisionTile(placeLayers(config));
         result.featureIndex = std::move(featureIndex);
-        result.tileData = std::move(tileData);
+        result.tileData = tileData->clone();
     }
 
     return std::move(result);

src/mbgl/tile/vector_tile.cpp

@@ -59,6 +59,10 @@ class VectorTileData : public GeometryTileData {
 public:
     VectorTileData(std::shared_ptr<const std::string> data);
 
+    std::unique_ptr<GeometryTileData> clone() const override {
+        return std::make_unique<VectorTileData>(*this);
+    }
+
     const GeometryTileLayer* getLayer(const std::string&) const override;
 
 private: