open-telemetry · marcalff · Mar 14, 2026 · Mar 12, 2026 · Mar 12, 2026 · Mar 12, 2026
@@ -54,6 +54,9 @@ Increment the:
 * [EXPORTER] Allow custom HttpClient in OTLP HTTP
   [#3930](https://github.com/open-telemetry/opentelemetry-cpp/pull/3930)
 
+* [CODE HEALTH] Fix clang-tidy unnecessary value param warnings
+  [#3931](https://github.com/open-telemetry/opentelemetry-cpp/pull/3931)
+
 Important changes:
 
 * [BUILD] Revisit EventLogger deprecation

@@ -100,7 +100,8 @@ void CleanupTracer()
   opentelemetry::sdk::trace::Provider::SetTracerProvider(none);
 }
 
-opentelemetry::nostd::shared_ptr<opentelemetry::trace::Tracer> get_tracer(std::string tracer_name)
+opentelemetry::nostd::shared_ptr<opentelemetry::trace::Tracer> get_tracer(
+    const std::string &tracer_name)
 {
   auto provider = opentelemetry::trace::Provider::GetTracerProvider();
   return provider->GetTracer(tracer_name);

@@ -89,7 +89,8 @@ void CleanupTracer()
   opentelemetry::sdk::trace::Provider::SetTracerProvider(none);
 }
 
-opentelemetry::nostd::shared_ptr<opentelemetry::trace::Tracer> get_tracer(std::string tracer_name)
+opentelemetry::nostd::shared_ptr<opentelemetry::trace::Tracer> get_tracer(
+    const std::string &tracer_name)
 {
   auto provider = opentelemetry::trace::Provider::GetTracerProvider();
   return provider->GetTracer(tracer_name);

@@ -56,7 +56,7 @@ class ProtobufGlobalSymbolGuard
 };
 
 template <class IntegerType>
-static IntegerType JsonToInteger(nlohmann::json value)
+static IntegerType JsonToInteger(const nlohmann::json &value)
 {
   if (value.is_string())
   {

@@ -407,7 +407,8 @@ TEST_F(OtlpGrpcExporterTestPeer, ConfigRetryGenericValuesFromEnv)
 #  ifdef ENABLE_OTLP_RETRY_PREVIEW
 struct TestTraceService : public opentelemetry::proto::collector::trace::v1::TraceService::Service
 {
-  TestTraceService(std::vector<grpc::StatusCode> status_codes) : status_codes_(status_codes) {}
+  TestTraceService(const std::vector<grpc::StatusCode> &status_codes) : status_codes_(status_codes)
+  {}
 
   inline grpc::Status Export(
       grpc::ServerContext *,

@@ -67,15 +67,15 @@ class OtlpGrpcMetricExporterTestPeer : public ::testing::Test
 
   std::unique_ptr<sdk::metrics::PushMetricExporter> GetExporter(
       std::unique_ptr<proto::collector::metrics::v1::MetricsService::StubInterface> stub_interface,
-      std::shared_ptr<OtlpGrpcClient> client)
+      const std::shared_ptr<OtlpGrpcClient> &client)
   {
     return std::unique_ptr<sdk::metrics::PushMetricExporter>(
         new OtlpGrpcMetricExporter(std::move(stub_interface), std::move(client)));
   }
 
   std::unique_ptr<sdk::metrics::PushMetricExporter> GetExporter(
       const OtlpGrpcMetricExporterOptions &options,
-      std::shared_ptr<OtlpGrpcClient> client)
+      const std::shared_ptr<OtlpGrpcClient> &client)
   {
     return std::unique_ptr<sdk::metrics::PushMetricExporter>(
         new OtlpGrpcMetricExporter(options, std::move(client)));

@@ -62,7 +62,7 @@ namespace otlp
 {
 
 template <class IntegerType>
-static IntegerType JsonToInteger(nlohmann::json value)
+static IntegerType JsonToInteger(const nlohmann::json &value)
 {
   if (value.is_string())
   {

@@ -162,7 +162,7 @@ class PrometheusExporterUtils
    * Counter => Prometheus Counter
    */
   template <typename T>
-  static void SetData(std::vector<T> values,
+  static void SetData(const std::vector<T> &values,
                       const opentelemetry::sdk::metrics::PointAttributes &labels,
                       const opentelemetry::sdk::instrumentationscope::InstrumentationScope *scope,
                       ::prometheus::MetricType type,
@@ -175,7 +175,7 @@ class PrometheusExporterUtils
    * Histogram => Prometheus Histogram
    */
   template <typename T>
-  static void SetData(std::vector<T> values,
+  static void SetData(const std::vector<T> &values,
                       const std::vector<double> &boundaries,
                       const std::vector<uint64_t> &counts,
                       const opentelemetry::sdk::metrics::PointAttributes &labels,

@@ -641,7 +641,7 @@ void PrometheusExporterUtils::SetTarget(
  */
 template <typename T>
 void PrometheusExporterUtils::SetData(
-    std::vector<T> values,
+    const std::vector<T> &values,
     const metric_sdk::PointAttributes &labels,
     const opentelemetry::sdk::instrumentationscope::InstrumentationScope *scope,
     prometheus_client::MetricType type,
@@ -661,7 +661,7 @@ void PrometheusExporterUtils::SetData(
  */
 template <typename T>
 void PrometheusExporterUtils::SetData(
-    std::vector<T> values,
+    const std::vector<T> &values,
     const std::vector<double> &boundaries,
     const std::vector<uint64_t> &counts,
     const metric_sdk::PointAttributes &labels,

@@ -63,11 +63,11 @@ class HttpRequestCallback
 
   virtual ~HttpRequestCallback() = default;
 
-  HttpRequestCallback(CallbackFunction func) : callback(func) {}
+  HttpRequestCallback(CallbackFunction func) : callback(std::move(func)) {}
 
   HttpRequestCallback &operator=(CallbackFunction func)
   {
-    callback = func;
+    callback = std::move(func);
     return (*this);
   }
 
@@ -133,7 +133,7 @@ class HttpServer : private SocketTools::Reactor::SocketCallback
       second = nullptr;
     }
 
-    HttpRequestHandler &operator=(std::pair<std::string, HttpRequestCallback *> other)
+    HttpRequestHandler &operator=(const std::pair<std::string, HttpRequestCallback *> &other)
     {
       first  = other.first;
       second = other.second;

@@ -439,7 +439,7 @@ struct SocketData
 
   SocketData() : socket(), flags(0) {}
 
-  bool operator==(Socket s) { return (socket == s); }
+  bool operator==(const Socket &s) { return (socket == s); }
 };
 
 /// <summary>

@@ -3,6 +3,7 @@
 
 #pragma once
 #include <functional>
+#include <utility>
 
 #include "opentelemetry/sdk/instrumentationscope/instrumentation_scope.h"
 #include "opentelemetry/version.h"
@@ -48,7 +49,7 @@ class ScopeConfigurator
     Builder &AddCondition(std::function<bool(const InstrumentationScope &)> scope_matcher,
                           T scope_config)
     {
-      conditions_.emplace_back(scope_matcher, scope_config);
+      conditions_.emplace_back(std::move(scope_matcher), scope_config);
       return *this;
     }
 
@@ -135,7 +136,7 @@ class ScopeConfigurator
 private:
   // Prevent direct initialization of ScopeConfigurator objects.
   explicit ScopeConfigurator(std::function<T(const InstrumentationScope &)> configurator)
-      : configurator_(configurator)
+      : configurator_(std::move(configurator))
   {}
 
   std::function<T(const InstrumentationScope &)> configurator_;

@@ -63,7 +63,7 @@ class DefaultAggregation
 
   static std::unique_ptr<Aggregation> CreateAggregation(
       AggregationType aggregation_type,
-      InstrumentDescriptor instrument_descriptor,
+      const InstrumentDescriptor &instrument_descriptor,
       const AggregationConfig *aggregation_config = nullptr)
   {
     switch (aggregation_type)

@@ -26,7 +26,7 @@ using MetricAttributes = opentelemetry::sdk::metrics::FilteredOrderedAttributeMa
 class ExemplarData
 {
 public:
-  static ExemplarData Create(std::shared_ptr<opentelemetry::trace::SpanContext> context,
+  static ExemplarData Create(const std::shared_ptr<opentelemetry::trace::SpanContext> &context,
                              const opentelemetry::common::SystemTimestamp &timestamp,
                              const PointDataAttributes &point_data_attr)
   {
@@ -68,7 +68,7 @@ class ExemplarData
   static PointType CreateDropPointData() { return DropPointData{}; }
 
 private:
-  ExemplarData(std::shared_ptr<opentelemetry::trace::SpanContext> context,
+  ExemplarData(const std::shared_ptr<opentelemetry::trace::SpanContext> &context,
                opentelemetry::common::SystemTimestamp timestamp,
                const PointDataAttributes &point_data_attr)
       : context_(*context.get()), timestamp_(timestamp), point_data_attr_(point_data_attr)

@@ -44,7 +44,7 @@ class AlignedHistogramBucketExemplarReservoir : public FixedSizeExemplarReservoi
 
   AlignedHistogramBucketExemplarReservoir(
       size_t size,
-      std::shared_ptr<ReservoirCellSelector> reservoir_cell_selector,
+      const std::shared_ptr<ReservoirCellSelector> &reservoir_cell_selector,
       MapAndResetCellType map_and_reset_cell)
       : FixedSizeExemplarReservoir(size + 1, reservoir_cell_selector, map_and_reset_cell)
   {}

@@ -27,7 +27,7 @@ class FixedSizeExemplarReservoir : public ExemplarReservoir
 
 public:
   FixedSizeExemplarReservoir(size_t size,
-                             std::shared_ptr<ReservoirCellSelector> reservoir_cell_selector,
+                             const std::shared_ptr<ReservoirCellSelector> &reservoir_cell_selector,
                              MapAndResetCellType map_and_reset_cell)
       : storage_(size),
         reservoir_cell_selector_(reservoir_cell_selector),

@@ -79,12 +79,12 @@ class ExemplarReservoir
 
   static nostd::shared_ptr<ExemplarReservoir> GetSimpleFixedSizeExemplarReservoir(
       size_t size,
-      std::shared_ptr<ReservoirCellSelector> reservoir_cell_selector,
+      const std::shared_ptr<ReservoirCellSelector> &reservoir_cell_selector,
       MapAndResetCellType map_and_reset_cell);
 
   static nostd::shared_ptr<ExemplarReservoir> GetAlignedHistogramBucketExemplarReservoir(
       size_t size,
-      std::shared_ptr<ReservoirCellSelector> reservoir_cell_selector,
+      const std::shared_ptr<ReservoirCellSelector> &reservoir_cell_selector,
       MapAndResetCellType map_and_reset_cell);
 
   static nostd::shared_ptr<ExemplarReservoir> GetNoExemplarReservoir();

@@ -43,9 +43,10 @@ class SimpleFixedSizeExemplarReservoir : public FixedSizeExemplarReservoir
     return std::shared_ptr<ReservoirCellSelector>{new SimpleFixedSizeCellSelector{size}};
   }
 
-  SimpleFixedSizeExemplarReservoir(size_t size,
-                                   std::shared_ptr<ReservoirCellSelector> reservoir_cell_selector,
-                                   MapAndResetCellType map_and_reset_cell)
+  SimpleFixedSizeExemplarReservoir(
+      size_t size,
+      const std::shared_ptr<ReservoirCellSelector> &reservoir_cell_selector,
+      MapAndResetCellType map_and_reset_cell)
       : FixedSizeExemplarReservoir(size, reservoir_cell_selector, map_and_reset_cell)
   {}
 

@@ -63,13 +63,13 @@ class MetricFilter
       const PointAttributes &attributes)>;
 
   // static
-  static std::unique_ptr<MetricFilter> Create(TestMetricFn test_metric_fn,
-                                              TestAttributesFn test_attributes_fn)
+  static std::unique_ptr<MetricFilter> Create(const TestMetricFn &test_metric_fn,
+                                              const TestAttributesFn &test_attributes_fn)
   {
     return std::make_unique<MetricFilter>(test_metric_fn, test_attributes_fn);
   }
 
-  MetricFilter(TestMetricFn test_metric_fn, TestAttributesFn test_attributes_fn)
+  MetricFilter(const TestMetricFn &test_metric_fn, const TestAttributesFn &test_attributes_fn)
       : test_metric_fn_(test_metric_fn), test_attributes_fn_(test_attributes_fn)
   {}
 

@@ -34,7 +34,7 @@ namespace metrics
 class AsyncMetricStorage : public MetricStorage, public AsyncWritableMetricStorage
 {
 public:
-  AsyncMetricStorage(InstrumentDescriptor instrument_descriptor,
+  AsyncMetricStorage(const InstrumentDescriptor &instrument_descriptor,
                      const AggregationType aggregation_type,
 #ifdef ENABLE_METRICS_EXEMPLAR_PREVIEW
                      ExemplarFilterType exempler_filter_type,

@@ -25,7 +25,7 @@ namespace metrics
 class SyncMultiMetricStorage : public SyncWritableMetricStorage
 {
 public:
-  void AddStorage(std::shared_ptr<SyncWritableMetricStorage> storage)
+  void AddStorage(const std::shared_ptr<SyncWritableMetricStorage> &storage)
   {
     storages_.push_back(storage);
   }
@@ -73,7 +73,7 @@ class SyncMultiMetricStorage : public SyncWritableMetricStorage
 class AsyncMultiMetricStorage : public AsyncWritableMetricStorage
 {
 public:
-  void AddStorage(std::shared_ptr<AsyncWritableMetricStorage> storage)
+  void AddStorage(const std::shared_ptr<AsyncWritableMetricStorage> &storage)
   {
     storages_.push_back(storage);
   }

@@ -57,7 +57,7 @@ class SyncMetricStorage : public MetricStorage, public SyncWritableMetricStorage
 #endif  // ENABLE_METRICS_EXEMPLAR_PREVIEW
 
 public:
-  SyncMetricStorage(InstrumentDescriptor instrument_descriptor,
+  SyncMetricStorage(const InstrumentDescriptor &instrument_descriptor,
                     const AggregationType aggregation_type,
                     std::shared_ptr<const AttributesProcessor> attributes_processor,
 #ifdef ENABLE_METRICS_EXEMPLAR_PREVIEW

@@ -23,7 +23,7 @@ namespace metrics
 class Synchronous
 {
 public:
-  Synchronous(InstrumentDescriptor instrument_descriptor,
+  Synchronous(const InstrumentDescriptor &instrument_descriptor,
               std::unique_ptr<SyncWritableMetricStorage> storage)
       : instrument_descriptor_(instrument_descriptor), storage_(std::move(storage))
   {}

@@ -25,9 +25,9 @@ class View
 {
 public:
   View(const std::string &name,
-       const std::string &description                        = "",
-       AggregationType aggregation_type                      = AggregationType::kDefault,
-       std::shared_ptr<AggregationConfig> aggregation_config = nullptr,
+       const std::string &description                               = "",
+       AggregationType aggregation_type                             = AggregationType::kDefault,
+       const std::shared_ptr<AggregationConfig> &aggregation_config = nullptr,
        std::unique_ptr<opentelemetry::sdk::metrics::AttributesProcessor> attributes_processor =
            std::unique_ptr<opentelemetry::sdk::metrics::AttributesProcessor>(
                new opentelemetry::sdk::metrics::DefaultAttributesProcessor()))

@@ -35,12 +35,12 @@ class OPENTELEMETRY_EXPORT ViewFactory
   static std::unique_ptr<View> Create(const std::string &name,
                                       const std::string &description,
                                       AggregationType aggregation_type,
-                                      std::shared_ptr<AggregationConfig> aggregation_config);
+                                      const std::shared_ptr<AggregationConfig> &aggregation_config);
 
   static std::unique_ptr<View> Create(const std::string &name,
                                       const std::string &description,
                                       AggregationType aggregation_type,
-                                      std::shared_ptr<AggregationConfig> aggregation_config,
+                                      const std::shared_ptr<AggregationConfig> &aggregation_config,
                                       std::unique_ptr<AttributesProcessor> attributes_processor);
 };
 

@@ -123,7 +123,7 @@ class Recordable
    * Add a link to a span with default (empty) attributes.
    * @param span_context the span context of the linked span
    */
-  void AddLink(opentelemetry::trace::SpanContext span_context)
+  void AddLink(const opentelemetry::trace::SpanContext &span_context)
   {
     AddLink(span_context, opentelemetry::sdk::GetEmptyAttributes());
   }

@@ -8,6 +8,7 @@
 #include <memory>
 #include <string>
 #include <unordered_map>
+#include <utility>
 #include <vector>
 
 #include "opentelemetry/common/attribute_value.h"
@@ -40,7 +41,7 @@ class SpanDataEvent
   SpanDataEvent(std::string name,
                 opentelemetry::common::SystemTimestamp timestamp,
                 const opentelemetry::common::KeyValueIterable &attributes)
-      : name_(name), timestamp_(timestamp), attribute_map_(attributes)
+      : name_(std::move(name)), timestamp_(timestamp), attribute_map_(attributes)
   {}
 
   /**
@@ -79,7 +80,7 @@ class SpanDataLink
 public:
   SpanDataLink(opentelemetry::trace::SpanContext span_context,
                const opentelemetry::common::KeyValueIterable &attributes)
-      : span_context_(span_context), attribute_map_(attributes)
+      : span_context_(std::move(span_context)), attribute_map_(attributes)
   {}
 
   /**