[core] Fix modernize-pass-by-value errors

As reported by clang-tidy-8.

8 files changed, 23 insertions, 35 deletions

diff --git a/include/mbgl/util/feature.hpp b/include/mbgl/util/feature.hpp
index 92d7ebf9da..de9b03f60e 100644
--- a/include/mbgl/util/feature.hpp
+++ b/include/mbgl/util/feature.hpp
@@ -32,19 +32,10 @@ public:
 
 template <class T>
 optional<T> numericValue(const Value& value) {
-    return value.match(
-        [] (uint64_t t) {
-            return optional<T>(t);
-        },
-        [] (int64_t t) {
-            return optional<T>(t);
-        },
-        [] (double t) {
-            return optional<T>(t);
-        },
-        [] (auto) {
-            return optional<T>();
-        });
+    return value.match([](uint64_t t) { return optional<T>(t); },
+                       [](int64_t t) { return optional<T>(t); },
+                       [](double t) { return optional<T>(t); },
+                       [](const auto&) { return optional<T>(); });
 }
 
 inline optional<std::string> featureIDtoString(const FeatureIdentifier& id) {
diff --git a/platform/glfw/test_writer.cpp b/platform/glfw/test_writer.cpp
index 9debaad643..9fe06cc2ca 100644
--- a/platform/glfw/test_writer.cpp
+++ b/platform/glfw/test_writer.cpp
@@ -7,6 +7,7 @@
 
 #include <cmath>
 #include <fstream>
+#include <utility>
 
 using Writer = rapidjson::PrettyWriter<rapidjson::StringBuffer>;
 
@@ -19,7 +20,7 @@ public:
 
 class SetCamera final : public TestOperationSerializer {
 public:
-    SetCamera(const mbgl::CameraOptions& camera_) : camera(camera_) {}
+    SetCamera(mbgl::CameraOptions camera_) : camera(std::move(camera_)) {}
 
     void serialize(Writer& writer) const override {
         if (camera.zoom) {
diff --git a/src/mbgl/renderer/buckets/line_bucket.cpp b/src/mbgl/renderer/buckets/line_bucket.cpp
index 809d8df6d3..256ce35eb5 100644
--- a/src/mbgl/renderer/buckets/line_bucket.cpp
+++ b/src/mbgl/renderer/buckets/line_bucket.cpp
@@ -5,16 +5,17 @@
 #include <mbgl/util/constants.hpp>
 
 #include <cassert>
+#include <utility>
 
 namespace mbgl {
 
 using namespace style;
 
-LineBucket::LineBucket(const LineBucket::PossiblyEvaluatedLayoutProperties& layout_,
+LineBucket::LineBucket(LineBucket::PossiblyEvaluatedLayoutProperties layout_,
                        const std::map<std::string, Immutable<LayerProperties>>& layerPaintProperties,
                        const float zoom_,
                        const uint32_t overscaling_)
-    : layout(layout_), zoom(zoom_), overscaling(overscaling_) {
+    : layout(std::move(layout_)), zoom(zoom_), overscaling(overscaling_) {
     for (const auto& pair : layerPaintProperties) {
         paintPropertyBinders.emplace(
             std::piecewise_construct,
diff --git a/src/mbgl/renderer/buckets/line_bucket.hpp b/src/mbgl/renderer/buckets/line_bucket.hpp
index 5b6a65440e..7ddcedef9f 100644
--- a/src/mbgl/renderer/buckets/line_bucket.hpp
+++ b/src/mbgl/renderer/buckets/line_bucket.hpp
@@ -19,7 +19,7 @@ class LineBucket final : public Bucket {
 public:
     using PossiblyEvaluatedLayoutProperties = style::LineLayoutProperties::PossiblyEvaluated;
 
-    LineBucket(const PossiblyEvaluatedLayoutProperties& layout,
+    LineBucket(PossiblyEvaluatedLayoutProperties layout,
                const std::map<std::string, Immutable<style::LayerProperties>>& layerPaintProperties,
                const float zoom,
                const uint32_t overscaling);
diff --git a/src/mbgl/renderer/buckets/symbol_bucket.cpp b/src/mbgl/renderer/buckets/symbol_bucket.cpp
index 234e81a9fd..cbdb4bf2ed 100644
--- a/src/mbgl/renderer/buckets/symbol_bucket.cpp
+++ b/src/mbgl/renderer/buckets/symbol_bucket.cpp
@@ -7,6 +7,8 @@
 #include <mbgl/text/glyph_atlas.hpp>
 #include <mbgl/text/placement.hpp>
 
+#include <utility>
+
 namespace mbgl {
 
 using namespace style;
@@ -21,7 +23,7 @@ SymbolBucket::SymbolBucket(Immutable<style::SymbolLayoutProperties::PossiblyEval
                            float zoom,
                            bool iconsNeedLinear_,
                            bool sortFeaturesByY_,
-                           const std::string& bucketName_,
+                           std::string bucketName_,
                            const std::vector<SymbolInstance>&& symbolInstances_,
                            const std::vector<SortKeyRange>&& sortKeyRanges_,
                            float tilePixelRatio_,
@@ -29,7 +31,7 @@ SymbolBucket::SymbolBucket(Immutable<style::SymbolLayoutProperties::PossiblyEval
                            std::vector<style::TextWritingModeType> placementModes_,
                            bool iconsInText_)
     : layout(std::move(layout_)),
-      bucketLeaderID(bucketName_),
+      bucketLeaderID(std::move(bucketName_)),
       iconsNeedLinear(iconsNeedLinear_ || iconSize.isDataDriven() || !iconSize.isZoomConstant()),
       sortFeaturesByY(sortFeaturesByY_),
       staticUploaded(false),
diff --git a/src/mbgl/renderer/buckets/symbol_bucket.hpp b/src/mbgl/renderer/buckets/symbol_bucket.hpp
index fa845a589a..00ba14589a 100644
--- a/src/mbgl/renderer/buckets/symbol_bucket.hpp
+++ b/src/mbgl/renderer/buckets/symbol_bucket.hpp
@@ -72,7 +72,7 @@ public:
                  float zoom,
                  bool iconsNeedLinear,
                  bool sortFeaturesByY,
-                 const std::string& bucketLeaderID,
+                 std::string bucketLeaderID,
                  const std::vector<SymbolInstance>&&,
                  const std::vector<SortKeyRange>&&,
                  const float tilePixelRatio,
diff --git a/src/mbgl/style/conversion/get_json_type.cpp b/src/mbgl/style/conversion/get_json_type.cpp
index 2e9d35a957..06becbb121 100644
--- a/src/mbgl/style/conversion/get_json_type.cpp
+++ b/src/mbgl/style/conversion/get_json_type.cpp
@@ -23,11 +23,9 @@ std::string getJSONType(const Convertible& value) {
     // conversion succeeds.
     assert(v);
 
-    return v->match(
-        [&] (const std::string&) { return "string"; },
-        [&] (bool) { return "boolean"; },
-        [&] (auto) { return "number"; }
-    );
+    return v->match([&](const std::string&) { return "string"; },
+                    [&](bool) { return "boolean"; },
+                    [&](const auto&) { return "number"; });
 }
 
 } // namespace conversion
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() {