1 files changed, 6 insertions, 2 deletions
diff --git a/include/mbgl/style/expression/compound_expression.hpp b/include/mbgl/style/expression/compound_expression.hpp
index fc3edbfd4a..8b74027578 100644
--- a/include/mbgl/style/expression/compound_expression.hpp
+++ b/include/mbgl/style/expression/compound_expression.hpp
@@ -72,7 +72,11 @@ public:
             [&](const std::vector<type::Type>& p) -> optional<std::size_t> { return p.size(); }
         );
     }
-    
+
+    std::vector<optional<Value>> possibleOutputs() const override {
+        return { nullopt };
+    }
+
 private:
     std::string name;
     variant<std::vector<type::Type>, VarargsType> params;
@@ -107,7 +111,7 @@ public:
         }
         return false;
     }
-    
+
 private:
     Signature signature;
     typename Signature::Args args;