[CODE HEALTH] fix clang-tidy cppcoreguidelines-pro-type-const-cast warnings

api/include/opentelemetry/metrics/multi_observer_result.h

@@ -35,25 +35,25 @@ class MultiObserverResult
    * @return An ObserverResultT<T> for the given instrument.
    */
   template <typename T>
-  ObserverResultT<T> &ForInstrument(const ObservableInstrument *instrument) = delete;
+  ObserverResultT<T> &ForInstrument(ObservableInstrument *instrument) = delete;
 
 protected:
   // You can't have a virtual template, and you can't overload on return type, so we need to
   // enumerate the options for the observer result type as separate methods to override.
-  virtual ObserverResultT<double> &ForInstrumentDouble(const ObservableInstrument *instrument) = 0;
-  virtual ObserverResultT<int64_t> &ForInstrumentInt64(const ObservableInstrument *instrument) = 0;
+  virtual ObserverResultT<double> &ForInstrumentDouble(ObservableInstrument *instrument) = 0;
+  virtual ObserverResultT<int64_t> &ForInstrumentInt64(ObservableInstrument *instrument) = 0;
 };
 
 template <>
 inline ObserverResultT<double> &MultiObserverResult::ForInstrument<double>(
-    const ObservableInstrument *instrument)
+    ObservableInstrument *instrument)
 {
   return ForInstrumentDouble(instrument);
 }
 
 template <>
 inline ObserverResultT<int64_t> &MultiObserverResult::ForInstrument<int64_t>(
-    const ObservableInstrument *instrument)
+    ObservableInstrument *instrument)
 {
   return ForInstrumentInt64(instrument);
 }

examples/http/server.cc

@@ -51,9 +51,7 @@ class RequestHandler : public HTTP_SERVER_NS::HttpRequestCallback
     std::string span_name = request.uri;
 
     // extract context from http header
-    std::map<std::string, std::string> &request_headers =
-        const_cast<std::map<std::string, std::string> &>(request.headers);
-    const HttpTextMapCarrier<std::map<std::string, std::string>> carrier(request_headers);
+    const HttpTextMapCarrier<std::map<std::string, std::string>> carrier(request.headers);
     auto prop        = context::propagation::GlobalTextMapPropagator::GetGlobalPropagator();
     auto current_ctx = context::RuntimeContext::GetCurrent();
     auto new_context = prop->Extract(carrier, current_ctx);

examples/http/tracer_common.h

@@ -29,7 +29,7 @@ template <typename T>
 class HttpTextMapCarrier : public opentelemetry::context::propagation::TextMapCarrier
 {
 public:
-  HttpTextMapCarrier(T &headers) : headers_(headers) {}
+  HttpTextMapCarrier(const T &headers) : headers_(headers) {}
   HttpTextMapCarrier() = default;
   opentelemetry::nostd::string_view Get(
       opentelemetry::nostd::string_view key) const noexcept override

ext/include/opentelemetry/ext/http/client/curl/http_operation_curl.h

@@ -290,12 +290,11 @@ class HttpOperation
   inline CURL *GetCurlEasyHandle() noexcept { return curl_resource_.easy_handle; }
 
 private:
-  CURLcode SetCurlPtrOption(CURLoption option, void *value);
+  CURLcode SetCurlPtrOption(CURLoption option, const void *value);
 
   CURLcode SetCurlStrOption(CURLoption option, const char *str)
   {
-    void *ptr = const_cast<char *>(str);
-    return SetCurlPtrOption(option, ptr);
+    return SetCurlPtrOption(option, str);
   }
 
   CURLcode SetCurlBlobOption(CURLoption option, struct curl_blob *blob)

ext/src/http/client/curl/http_operation_curl.cc

@@ -721,7 +721,7 @@ const char *HttpOperation::GetCurlErrorMessage(CURLcode code)
   return message;
 }
 
-CURLcode HttpOperation::SetCurlPtrOption(CURLoption option, void *value)
+CURLcode HttpOperation::SetCurlPtrOption(CURLoption option, const void *value)
 {
   /*
     curl_easy_setopt() is a macro with variadic arguments, type unsafe.
@@ -907,13 +907,13 @@ CURLcode HttpOperation::Setup()
     else if (!ssl_options_.ssl_ca_cert_string.empty())
     {
 #if LIBCURL_VERSION_NUM >= CURL_VERSION_BITS(7, 77, 0)
-      const char *data = ssl_options_.ssl_ca_cert_string.c_str();
-      size_t data_len  = ssl_options_.ssl_ca_cert_string.length();
+      std::vector<char> blob_data(ssl_options_.ssl_ca_cert_string.begin(),
+                                  ssl_options_.ssl_ca_cert_string.end());
 
       struct curl_blob stblob
       {};
-      stblob.data  = const_cast<char *>(data);
-      stblob.len   = data_len;
+      stblob.data  = blob_data.data();
+      stblob.len   = blob_data.size();
       stblob.flags = CURL_BLOB_COPY;
 
       rc = SetCurlBlobOption(CURLOPT_CAINFO_BLOB, &stblob);
@@ -949,13 +949,13 @@ CURLcode HttpOperation::Setup()
     else if (!ssl_options_.ssl_client_key_string.empty())
     {
 #if LIBCURL_VERSION_NUM >= CURL_VERSION_BITS(7, 71, 0)
-      const char *data = ssl_options_.ssl_client_key_string.c_str();
-      size_t data_len  = ssl_options_.ssl_client_key_string.length();
+      std::vector<char> blob_data(ssl_options_.ssl_client_key_string.begin(),
+                                  ssl_options_.ssl_client_key_string.end());
 
       struct curl_blob stblob
       {};
-      stblob.data  = const_cast<char *>(data);
-      stblob.len   = data_len;
+      stblob.data  = blob_data.data();
+      stblob.len   = blob_data.size();
       stblob.flags = CURL_BLOB_COPY;
 
       rc = SetCurlBlobOption(CURLOPT_SSLKEY_BLOB, &stblob);
@@ -997,13 +997,13 @@ CURLcode HttpOperation::Setup()
     else if (!ssl_options_.ssl_client_cert_string.empty())
     {
 #if LIBCURL_VERSION_NUM >= CURL_VERSION_BITS(7, 71, 0)
-      const char *data = ssl_options_.ssl_client_cert_string.c_str();
-      size_t data_len  = ssl_options_.ssl_client_cert_string.length();
+      std::vector<char> blob_data(ssl_options_.ssl_client_cert_string.begin(),
+                                  ssl_options_.ssl_client_cert_string.end());
 
       struct curl_blob stblob
       {};
-      stblob.data  = const_cast<char *>(data);
-      stblob.len   = data_len;
+      stblob.data  = blob_data.data();
+      stblob.len   = blob_data.size();
       stblob.flags = CURL_BLOB_COPY;
 
       rc = SetCurlBlobOption(CURLOPT_SSLCERT_BLOB, &stblob);

ext/test/w3c_tracecontext_http_test_server/main.cc

@@ -203,7 +203,7 @@ int main(int argc, char *argv[])
 
         for (auto &part : body)
         {
-          auto headers_2 = const_cast<std::map<std::string, std::string> &>(req.headers);
+          auto headers_2 = req.headers;
 
           const TextMapCarrierTest carrier(headers_2);
           auto current_ctx = context::RuntimeContext::GetCurrent();

sdk/include/opentelemetry/sdk/common/circular_buffer.h

@@ -38,10 +38,7 @@ class CircularBuffer
    *
    * Note: This method must only be called from the consumer thread.
    */
-  CircularBufferRange<const AtomicUniquePtr<T>> Peek() const noexcept
-  {
-    return const_cast<CircularBuffer *>(this)->PeekImpl();
-  }
+  CircularBufferRange<const AtomicUniquePtr<T>> Peek() const noexcept { return PeekImpl(); }
 
   /**
    * Consume elements from the circular buffer's tail.
@@ -172,7 +169,7 @@ class CircularBuffer
   std::atomic<uint64_t> head_{0};
   std::atomic<uint64_t> tail_{0};
 
-  CircularBufferRange<AtomicUniquePtr<T>> PeekImpl() noexcept
+  CircularBufferRange<AtomicUniquePtr<T>> PeekImpl() const noexcept
   {
     uint64_t tail_index = tail_ % capacity_;
     uint64_t head_index = head_ % capacity_;

sdk/include/opentelemetry/sdk/metrics/multi_observer_result.h

@@ -25,17 +25,17 @@ class OPENTELEMETRY_EXPORT MultiObserverResult final
   void RegisterInstrument(opentelemetry::metrics::ObservableInstrument *instrument);
   void DeregisterInstrument(opentelemetry::metrics::ObservableInstrument *instrument);
   size_t InstrumentCount() const;
-  bool HasInstrument(const opentelemetry::metrics::ObservableInstrument *instrument) const;
+  bool HasInstrument(opentelemetry::metrics::ObservableInstrument *instrument) const;
   void GetInstruments(
       nostd::function_ref<void(opentelemetry::metrics::ObservableInstrument *)> callback);
   void Reset();
   void StoreResults(opentelemetry::common::SystemTimestamp collection_ts);
 
 protected:
   opentelemetry::metrics::ObserverResultT<double> &ForInstrumentDouble(
-      const opentelemetry::metrics::ObservableInstrument *instrument) override;
+      opentelemetry::metrics::ObservableInstrument *instrument) override;
   opentelemetry::metrics::ObserverResultT<int64_t> &ForInstrumentInt64(
-      const opentelemetry::metrics::ObservableInstrument *instrument) override;
+      opentelemetry::metrics::ObservableInstrument *instrument) override;
 
 private:
   // This is _different_ to opentelemetry::metrics::ObserverResult because this variant is

sdk/src/metrics/multi_observer_result.cc

@@ -63,10 +63,9 @@ size_t MultiObserverResult::InstrumentCount() const
 }
 
 bool MultiObserverResult::HasInstrument(
-    const opentelemetry::metrics::ObservableInstrument *instrument) const
+    opentelemetry::metrics::ObservableInstrument *instrument) const
 {
-  return observer_results_.find(const_cast<opentelemetry::metrics::ObservableInstrument *>(
-             instrument)) != observer_results_.end();
+  return observer_results_.find(instrument) != observer_results_.end();
 }
 
 void MultiObserverResult::GetInstruments(
@@ -100,13 +99,10 @@ void MultiObserverResult::StoreResults(opentelemetry::common::SystemTimestamp co
 }
 
 opentelemetry::metrics::ObserverResultT<double> &MultiObserverResult::ForInstrumentDouble(
-    const opentelemetry::metrics::ObservableInstrument *instrument)
+    opentelemetry::metrics::ObservableInstrument *instrument)
 {
   static opentelemetry::sdk::metrics::ObserverResultT<double> null_result;
-  // const_cast is appropriate here, because we're _not_ modifying the passed-in pointer;
-  // we just need to make it non-const to be able to look it up in our map.
-  auto it = observer_results_.find(
-      const_cast<opentelemetry::metrics::ObservableInstrument *>(instrument));
+  auto it = observer_results_.find(instrument);
   if (it == observer_results_.end())
   {
     OTEL_INTERNAL_LOG_ERROR("[MultiObserverResult::ForInstrumentDouble]"
@@ -125,11 +121,10 @@ opentelemetry::metrics::ObserverResultT<double> &MultiObserverResult::ForInstrum
 }
 
 opentelemetry::metrics::ObserverResultT<int64_t> &MultiObserverResult::ForInstrumentInt64(
-    const opentelemetry::metrics::ObservableInstrument *instrument)
+    opentelemetry::metrics::ObservableInstrument *instrument)
 {
   static opentelemetry::sdk::metrics::ObserverResultT<int64_t> null_result;
-  auto it = observer_results_.find(
-      const_cast<opentelemetry::metrics::ObservableInstrument *>(instrument));
+  auto it = observer_results_.find(instrument);
   if (it == observer_results_.end())
   {
     OTEL_INTERNAL_LOG_ERROR("[MultiObserverResult::ForInstrumentInt64]"