[core] Functions must have at least one stop

This is already enforced by the style validator in mapbox-gl-style-spec. Enforce it here too.

2 files changed, 8 insertions, 2 deletions

diff --git a/include/mbgl/style/conversion/function.hpp b/include/mbgl/style/conversion/function.hpp
index f14b5089be..6a0b67618f 100644
--- a/include/mbgl/style/conversion/function.hpp
+++ b/include/mbgl/style/conversion/function.hpp
@@ -25,6 +25,10 @@ struct Converter<Function<T>> {
             return Error { "function stops must be an array" };
         }
 
+        if (arrayLength(*stopsValue) == 0) {
+            return Error { "function must have at least one stop" };
+        }
+
         std::vector<std::pair<float, T>> stops;
         for (std::size_t i = 0; i < arrayLength(*stopsValue); ++i) {
             const auto& stopValue = arrayMember(*stopsValue, i);
diff --git a/include/mbgl/style/function.hpp b/include/mbgl/style/function.hpp
index 97e880b280..3aefba6600 100644
--- a/include/mbgl/style/function.hpp
+++ b/include/mbgl/style/function.hpp
@@ -12,8 +12,10 @@ public:
     using Stop = std::pair<float, T>;
     using Stops = std::vector<Stop>;
 
-    explicit Function(Stops stops_, float base_)
-        : base(base_), stops(std::move(stops_)) {}
+    Function(Stops stops_, float base_)
+        : base(base_), stops(std::move(stops_)) {
+        assert(stops.size() > 0);
+    }
 
     float getBase() const { return base; }
     const std::vector<std::pair<float, T>>& getStops() const { return stops; }