open-telemetry · marcalff · Mar 12, 2026 · Mar 11, 2026 · Mar 11, 2026 · Mar 11, 2026
@@ -48,6 +48,9 @@ Increment the:
 * [CODE HEALTH] Fix clang-tidy macro to enum warnings
   [#3922](https://github.com/open-telemetry/opentelemetry-cpp/pull/3922)
 
+* [CODE HEALTH] Fix clang-tidy performance enum size warnings
+  [#3923](https://github.com/open-telemetry/opentelemetry-cpp/pull/3923)
+
 Important changes:
 
 * [BUILD] Revisit EventLogger deprecation

@@ -57,7 +57,11 @@ using AttributeValue =
                    nostd::span<const uint64_t>,
                    nostd::span<const uint8_t>>;
 
-enum AttributeType
+#if OPENTELEMETRY_ABI_VERSION_NO >= 2
+enum AttributeType : std::uint8_t
+#else
+enum AttributeType  // NOLINT(performance-enum-size)
+#endif
 {
   kTypeBool,
   kTypeInt,

@@ -6,11 +6,19 @@
 #include "opentelemetry/common/timestamp.h"
 #include "opentelemetry/version.h"
 
+#if OPENTELEMETRY_ABI_VERSION_NO >= 2
+#  include <cstdint>
+#endif
+
 OPENTELEMETRY_BEGIN_NAMESPACE
 namespace trace
 {
 
-enum class SpanKind
+#if OPENTELEMETRY_ABI_VERSION_NO >= 2
+enum class SpanKind : std::uint8_t
+#else
+enum class SpanKind  // NOLINT(performance-enum-size)
+#endif
 {
   kInternal,
   kServer,
@@ -24,7 +32,11 @@ constexpr char kSpanKey[]       = "active_span";
 constexpr char kIsRootSpanKey[] = "is_root_span";
 
 // StatusCode - Represents the canonical set of status codes of a finished Span.
-enum class StatusCode
+#if OPENTELEMETRY_ABI_VERSION_NO >= 2
+enum class StatusCode : std::uint8_t
+#else
+enum class StatusCode  // NOLINT(performance-enum-size)
+#endif
 {
   kUnset,  // default status
   kOk,     // Operation has completed successfully.

@@ -3,6 +3,8 @@
 
 #pragma once
 
+#include <cstdint>
+
 #include "opentelemetry/nostd/string_view.h"
 #include "opentelemetry/version.h"
 
@@ -12,14 +14,14 @@ namespace exporter
 namespace otlp
 {
 
-enum class JsonBytesMappingKind
+enum class JsonBytesMappingKind : std::uint8_t
 {
   kHexId,
   kHex,
   kBase64,
 };
 
-enum class HttpRequestContentType
+enum class HttpRequestContentType : std::uint8_t
 {
   kJson,
   kBinary,

@@ -2,6 +2,9 @@
 // SPDX-License-Identifier: Apache-2.0
 
 #pragma once
+
+#include <cstdint>
+
 #include "opentelemetry/version.h"
 
 OPENTELEMETRY_BEGIN_NAMESPACE
@@ -10,7 +13,7 @@ namespace exporter
 namespace otlp
 {
 
-enum class PreferredAggregationTemporality
+enum class PreferredAggregationTemporality : std::uint8_t
 {
   kUnspecified,
   kDelta,

@@ -3,6 +3,8 @@
 
 #pragma once
 
+#include <cstdint>
+
 #include "opentelemetry/ext/http/client/http_client_factory.h"
 #include "opentelemetry/ext/http/common/url_parser.h"
 #include "opentelemetry/sdk/common/env_variables.h"
@@ -26,7 +28,7 @@ inline const std::string GetDefaultZipkinEndpoint()
   return exists ? endpoint : kZipkinEndpointDefault;
 }
 
-enum class TransportFormat
+enum class TransportFormat : std::uint8_t
 {
   kJson,
   kProtobuf

@@ -4,6 +4,7 @@
 #pragma once
 
 #include <chrono>
+#include <cstdint>
 #include <cstring>
 #include <map>
 #include <memory>
@@ -67,7 +68,7 @@ namespace http
 namespace client
 {
 
-enum class Method
+enum class Method : std::uint8_t
 {
   Get,
   Post,
@@ -78,7 +79,7 @@ enum class Method
   Delete
 };
 
-enum class SessionState
+enum class SessionState : std::uint8_t
 {
   CreateFailed,        // session create failed
   Created,             // session created
@@ -97,7 +98,7 @@ enum class SessionState
   Cancelled            // (manually) cancelled
 };
 
-enum class Compression
+enum class Compression : std::uint8_t
 {
   kNone,
   kGzip

@@ -3,6 +3,7 @@
 
 #pragma once
 
+#include <cstdint>
 #include <functional>
 #include <list>
 #include <map>
@@ -95,7 +96,7 @@ class HttpServer : private SocketTools::Reactor::SocketCallback
     SocketTools::Socket socket;
     std::string receiveBuffer;
     std::string sendBuffer;
-    enum
+    enum : std::uint8_t
     {
       Idle,
       ReceivingHeaders,

@@ -6,6 +6,7 @@
 #include <atomic>
 #include <cassert>
 #include <cstddef>
+#include <cstdint>
 #include <cstring>
 #include <iostream>
 #include <map>
@@ -405,7 +406,7 @@ struct Socket
 #endif
   }
 
-  enum
+  enum  // NOLINT(performance-enum-size)
   {
 #ifdef _WIN32
     ErrorWouldBlock = WSAEWOULDBLOCK
@@ -414,7 +415,7 @@ struct Socket
 #endif
   };
 
-  enum
+  enum  // NOLINT(performance-enum-size)
   {
 #ifdef _WIN32
     ShutdownReceive = SD_RECEIVE,
@@ -469,7 +470,7 @@ struct Reactor : protected common::Thread
   /// <summary>
   /// Socket State
   /// </summary>
-  enum State
+  enum State : std::uint8_t
   {
     Readable   = 1,
     Writable   = 2,

@@ -49,7 +49,7 @@ using OwnedAttributeValue = nostd::variant<bool,
                                            std::vector<uint64_t>,
                                            std::vector<uint8_t>>;
 
-enum OwnedAttributeType
+enum OwnedAttributeType : std::uint8_t
 {
   kTypeBool,
   kTypeInt,

@@ -3,6 +3,8 @@
 
 #pragma once
 
+#include <cstdint>
+
 #include "opentelemetry/version.h"
 
 OPENTELEMETRY_BEGIN_NAMESPACE
@@ -13,7 +15,7 @@ namespace common
 /**
  * ExportResult is returned as result of exporting a batch of Records.
  */
-enum class ExportResult
+enum class ExportResult : std::uint8_t
 {
   // Batch was exported successfully.
   kSuccess = 0,

@@ -3,6 +3,7 @@
 
 #pragma once
 
+#include <cstdint>
 #include <sstream>  // IWYU pragma: keep
 #include <string>
 
@@ -28,7 +29,7 @@ namespace common
 namespace internal_log
 {
 
-enum class LogLevel
+enum class LogLevel : std::uint8_t
 {
   None    = OTEL_INTERNAL_LOG_LEVEL_NONE,
   Error   = OTEL_INTERNAL_LOG_LEVEL_ERROR,

@@ -3,6 +3,7 @@
 
 #pragma once
 
+#include <cstdint>
 #include <functional>
 #include <memory>
 
@@ -35,14 +36,14 @@ namespace metrics
 class MetricFilter
 {
 public:
-  enum class MetricFilterResult
+  enum class MetricFilterResult : std::uint8_t
   {
     kAccept,
     kDrop,
     kAcceptPartial,
   };
 
-  enum class AttributesFilterResult
+  enum class AttributesFilterResult : std::uint8_t
   {
     kAccept,
     kDrop,

@@ -3,6 +3,7 @@
 
 #pragma once
 
+#include <cstdint>
 #include <memory>
 #include <utility>
 #include <vector>
@@ -94,7 +95,7 @@ class MetricProducer
   MetricProducer &operator=(const MetricProducer &) = delete;
   MetricProducer &operator=(MetricProducer &&)      = delete;
 
-  enum class Status
+  enum class Status : std::uint8_t
   {
     kSuccess,
     kFailure,

@@ -5,6 +5,7 @@
 
 #include <algorithm>
 #include <cctype>
+#include <cstdint>
 #include <functional>
 #include <string>
 
@@ -16,7 +17,7 @@ namespace sdk
 {
 namespace metrics
 {
-enum class InstrumentType
+enum class InstrumentType : std::uint8_t
 {
   kCounter,
   kHistogram,
@@ -27,21 +28,21 @@ enum class InstrumentType
   kGauge
 };
 
-enum class InstrumentClass
+enum class InstrumentClass : std::uint8_t
 {
   kSync,
   kAsync
 };
 
-enum class InstrumentValueType
+enum class InstrumentValueType : std::uint8_t
 {
   kInt,
   kLong,
   kFloat,
   kDouble
 };
 
-enum class AggregationType
+enum class AggregationType : std::uint8_t
 {
   kDrop,
   kHistogram,
@@ -51,7 +52,7 @@ enum class AggregationType
   kBase2ExponentialHistogram
 };
 
-enum class AggregationTemporality
+enum class AggregationTemporality : std::uint8_t
 {
   kUnspecified,
   kDelta,

@@ -3,6 +3,7 @@
 
 #pragma once
 
+#include <cstdint>
 #include <map>
 #include <memory>
 #include <string>
@@ -34,7 +35,7 @@ namespace trace
 /**
  * A sampling Decision for a Span to be created.
  */
-enum class Decision
+enum class Decision : std::uint8_t
 {
   // IsRecording() == false, span will not be recorded and all events and attributes will be
   // dropped.