3 files changed, 11 insertions, 12 deletions

diff --git a/src/mbgl/layout/symbol_instance.cpp b/src/mbgl/layout/symbol_instance.cpp
index 7dfa8edf43..a9b4b929ec 100644
--- a/src/mbgl/layout/symbol_instance.cpp
+++ b/src/mbgl/layout/symbol_instance.cpp
@@ -11,7 +11,6 @@ SymbolInstance::SymbolInstance(Anchor& anchor_,
                                optional<PositionedIcon> shapedIcon,
                                const SymbolLayoutProperties::Evaluated& layout,
                                const float layoutTextSize,
-                               const uint32_t index_,
                                const float textBoxScale,
                                const float textPadding,
                                const SymbolPlacementType textPlacement,
@@ -21,19 +20,20 @@ SymbolInstance::SymbolInstance(Anchor& anchor_,
                                const std::array<float, 2> iconOffset_,
                                const GlyphPositionMap& positions,
                                const IndexedSubfeature& indexedFeature,
-                               const std::size_t featureIndex_,
+                               const std::size_t layoutFeatureIndex_,
+                               const std::size_t dataFeatureIndex_,
                                const std::u16string& key_,
                                const float overscaling) :
     anchor(anchor_),
     line(line_),
-    index(index_),
     hasText(false),
     hasIcon(shapedIcon),
 
     // Create the collision features that will be used to check whether this symbol instance can be placed
     textCollisionFeature(line_, anchor, shapedTextOrientations.first, textBoxScale, textPadding, textPlacement, indexedFeature, overscaling),
     iconCollisionFeature(line_, anchor, shapedIcon, iconBoxScale, iconPadding, indexedFeature),
-    featureIndex(featureIndex_),
+    layoutFeatureIndex(layoutFeatureIndex_),
+    dataFeatureIndex(dataFeatureIndex_),
     textOffset(textOffset_),
     iconOffset(iconOffset_),
     key(key_) {
diff --git a/src/mbgl/layout/symbol_instance.hpp b/src/mbgl/layout/symbol_instance.hpp
index 827a5dbbdb..ae79311790 100644
--- a/src/mbgl/layout/symbol_instance.hpp
+++ b/src/mbgl/layout/symbol_instance.hpp
@@ -19,7 +19,6 @@ public:
                    optional<PositionedIcon> shapedIcon,
                    const style::SymbolLayoutProperties::Evaluated&,
                    const float layoutTextSize,
-                   const uint32_t index,
                    const float textBoxScale,
                    const float textPadding,
                    style::SymbolPlacementType textPlacement,
@@ -29,13 +28,13 @@ public:
                    const std::array<float, 2> iconOffset,
                    const GlyphPositionMap&,
                    const IndexedSubfeature&,
-                   const std::size_t featureIndex,
+                   const std::size_t layoutFeatureIndex,
+                   const std::size_t dataFeatureIndex,
                    const std::u16string& key,
                    const float overscaling);
 
     Anchor anchor;
     GeometryCoordinates line;
-    uint32_t index;
     bool hasText;
     bool hasIcon;
     SymbolQuads horizontalGlyphQuads;
@@ -44,7 +43,8 @@ public:
     CollisionFeature textCollisionFeature;
     CollisionFeature iconCollisionFeature;
     WritingModeType writingModes;
-    std::size_t featureIndex;
+    std::size_t layoutFeatureIndex; // Index into the set of features included at layout time
+    std::size_t dataFeatureIndex;   // Index into the underlying tile data feature set
     std::array<float, 2> textOffset;
     std::array<float, 2> iconOffset;
     std::u16string key;
diff --git a/src/mbgl/layout/symbol_layout.cpp b/src/mbgl/layout/symbol_layout.cpp
index 4249ffc24e..e71cfb93b0 100644
--- a/src/mbgl/layout/symbol_layout.cpp
+++ b/src/mbgl/layout/symbol_layout.cpp
@@ -260,7 +260,7 @@ void SymbolLayout::prepare(const GlyphMap& glyphMap, const GlyphPositions& glyph
     compareText.clear();
 }
 
-void SymbolLayout::addFeature(const std::size_t index,
+void SymbolLayout::addFeature(const std::size_t layoutFeatureIndex,
                               const SymbolFeature& feature,
                               const std::pair<Shaping, Shaping>& shapedTextOrientations,
                               optional<PositionedIcon> shapedIcon,
@@ -317,10 +317,9 @@ void SymbolLayout::addFeature(const std::size_t index,
         if (mode == MapMode::Tile || withinPlus0) {
             symbolInstances.emplace_back(anchor, line, shapedTextOrientations, shapedIcon,
                     layout.evaluate(zoom, feature), layoutTextSize,
-                    symbolInstances.size(),
                     textBoxScale, textPadding, textPlacement, textOffset,
                     iconBoxScale, iconPadding, iconOffset,
-                    glyphPositionMap, indexedFeature, index, feature.text.value_or(std::u16string()), overscaling);
+                    glyphPositionMap, indexedFeature, layoutFeatureIndex, feature.index, feature.text.value_or(std::u16string()), overscaling);
         }
     };
     
@@ -426,7 +425,7 @@ std::unique_ptr<SymbolBucket> SymbolLayout::place(const bool showCollisionBoxes)
         const bool hasText = symbolInstance.hasText;
         const bool hasIcon = symbolInstance.hasIcon;
 
-        const auto& feature = features.at(symbolInstance.featureIndex);
+        const auto& feature = features.at(symbolInstance.layoutFeatureIndex);
 
         // Insert final placement into collision tree and add glyphs/icons to buffers