[core] Fix performance-no-automatic-move (bonus)

As reported by clang-tidy-10. We don't run clang-tidy-10 yet. We
should probably consider moving the bots at some point so errors
like this won't return.

2 files changed, 3 insertions, 3 deletions

diff --git a/src/mbgl/style/expression/boolean_operator.cpp b/src/mbgl/style/expression/boolean_operator.cpp
index a02c08131f..6beae6062a 100644
--- a/src/mbgl/style/expression/boolean_operator.cpp
+++ b/src/mbgl/style/expression/boolean_operator.cpp
@@ -7,7 +7,7 @@ namespace expression {
 
 EvaluationResult Any::evaluate(const EvaluationContext& params) const {
     for (const auto& input : inputs) {
-        const EvaluationResult result = input->evaluate(params);
+        EvaluationResult result = input->evaluate(params);
         if (!result) return result;
         if (result->get<bool>()) return EvaluationResult(true);
     }
@@ -35,7 +35,7 @@ std::vector<optional<Value>> Any::possibleOutputs() const {
 
 EvaluationResult All::evaluate(const EvaluationContext& params) const {
     for (const auto& input : inputs) {
-        const EvaluationResult result = input->evaluate(params);
+        EvaluationResult result = input->evaluate(params);
         if (!result) return result;
         if (!result->get<bool>()) return EvaluationResult(false);
     }
diff --git a/src/mbgl/style/expression/length.cpp b/src/mbgl/style/expression/length.cpp
index f1b58d7952..340a2debea 100644
--- a/src/mbgl/style/expression/length.cpp
+++ b/src/mbgl/style/expression/length.cpp
@@ -12,7 +12,7 @@ Length::Length(std::unique_ptr<Expression> input_)
 }
 
 EvaluationResult Length::evaluate(const EvaluationContext& params) const {
-    const EvaluationResult value = input->evaluate(params);
+    EvaluationResult value = input->evaluate(params);
     if (!value) return value;
     return value->match(
         [] (const std::string& s) {