[core] Fix potential race condition crash in symbol querying..

Second half of fix for issue #11538.

If a global placement took place between the time a tile's non-symbol layout updated and the time new symbol buckets arrived, the tile's new FeatureIndex would be committed, but the global CollisionIndex would be generated against the old symbolBuckets. The mismatch could cause the CollisionIndex to contain indices that didn't exist in the new FeatureIndex, and attempting to access them would generate an out-of-bounds exception.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/mbgl/tile/geometry_tile.hpp b/src/mbgl/tile/geometry_tile.hpp
index 0c6adf0337..8843d6e579 100644
--- a/src/mbgl/tile/geometry_tile.hpp
+++ b/src/mbgl/tile/geometry_tile.hpp
@@ -125,9 +125,9 @@ private:
 
     std::unordered_map<std::string, std::shared_ptr<Bucket>> nonSymbolBuckets;
     std::unique_ptr<FeatureIndex> featureIndex;
-    optional<std::unique_ptr<FeatureIndex>> pendingFeatureIndex;
+    optional<std::pair<bool,std::unique_ptr<FeatureIndex>>> pendingFeatureIndex;
     std::unique_ptr<const GeometryTileData> data;
-    optional<std::unique_ptr<const GeometryTileData>> pendingData;
+    optional<std::pair<bool, std::unique_ptr<const GeometryTileData>>> pendingData;
 
     optional<AlphaImage> glyphAtlasImage;
     optional<PremultipliedImage> iconAtlasImage;