1 files changed, 5 insertions, 10 deletions
diff --git a/src/mbgl/style/expression/compound_expression.cpp b/src/mbgl/style/expression/compound_expression.cpp
index 45b8b793a2..31628617f6 100644
--- a/src/mbgl/style/expression/compound_expression.cpp
+++ b/src/mbgl/style/expression/compound_expression.cpp
@@ -249,17 +249,15 @@ optional<double> featurePropertyAsDouble(const EvaluationContext& params, const
     return property->match([](double value) { return value; },
                            [](uint64_t value) -> optional<double> { return {static_cast<double>(value)}; },
                            [](int64_t value) -> optional<double> { return {static_cast<double>(value)}; },
-                           [](auto) -> optional<double> { return {}; });
+                           [](const auto&) -> optional<double> { return {}; });
 };
 
 optional<std::string> featurePropertyAsString(const EvaluationContext& params, const std::string& key) {
     assert(params.feature);
     auto property = params.feature->getValue(key);
     if (!property) return {};
-    return property->match(
-        [](std::string value) { return value; },
-        [](auto) { return optional<std::string>(); }
-    );
+    return property->match([](std::string value) { return value; },
+                           [](const auto&) { return optional<std::string>(); });
 };
 
 optional<double> featureIdAsDouble(const EvaluationContext& params) {
@@ -268,16 +266,13 @@ optional<double> featureIdAsDouble(const EvaluationContext& params) {
     return id.match([](double value) { return value; },
                     [](uint64_t value) -> optional<double> { return {static_cast<double>(value)}; },
                     [](int64_t value) -> optional<double> { return {static_cast<double>(value)}; },
-                    [](auto) -> optional<double> { return {}; });
+                    [](const auto&) -> optional<double> { return {}; });
 };
 
 optional<std::string> featureIdAsString(const EvaluationContext& params) {
     assert(params.feature);
     auto id = params.feature->getID();
-    return id.match(
-        [](std::string value) { return value; },
-        [](auto) { return optional<std::string>(); }
-    );
+    return id.match([](std::string value) { return value; }, [](const auto&) { return optional<std::string>(); });
 };
 
 const auto& eCompoundExpression() {