[core] Restored shape annotation z-order

Shapes are once again always added to the top z-index.

Fixes #5691.

Cherry-picked from 74fe96d2617f870206ff358d7dfcafccf4e109bc.

1 files changed, 4 insertions, 2 deletions

diff --git a/src/mbgl/annotation/annotation_manager.hpp b/src/mbgl/annotation/annotation_manager.hpp
index 73907e10c8..7e0cf3a394 100644
--- a/src/mbgl/annotation/annotation_manager.hpp
+++ b/src/mbgl/annotation/annotation_manager.hpp
@@ -58,8 +58,10 @@ private:
     AnnotationID nextID = 0;
 
     using SymbolAnnotationTree = boost::geometry::index::rtree<std::shared_ptr<const SymbolAnnotationImpl>, boost::geometry::index::rstar<16, 4>>;
-    using SymbolAnnotationMap = std::unordered_map<AnnotationID, std::shared_ptr<SymbolAnnotationImpl>>;
-    using ShapeAnnotationMap = std::unordered_map<AnnotationID, std::unique_ptr<ShapeAnnotationImpl>>;
+    // Unlike std::unordered_map, std::map is guaranteed to sort by AnnotationID, ensuring that older annotations are below newer annotations.
+    // <https://github.com/mapbox/mapbox-gl-native/issues/5691>
+    using SymbolAnnotationMap = std::map<AnnotationID, std::shared_ptr<SymbolAnnotationImpl>>;
+    using ShapeAnnotationMap = std::map<AnnotationID, std::unique_ptr<ShapeAnnotationImpl>>;
 
     SymbolAnnotationTree symbolTree;
     SymbolAnnotationMap symbolAnnotations;