Merge branch 'main' into fix/reader_data_race

CHANGELOG.md

@@ -23,6 +23,10 @@ Increment the:
   [#2579](https://github.com/open-telemetry/opentelemetry-cpp/pull/2579)
 * [CI] Use platform CMake
   [#2627](https://github.com/open-telemetry/opentelemetry-cpp/pull/2627)
+* [PROTO] Upgrade to opentelemetry-proto v1.2.0
+  [#2631](https://github.com/open-telemetry/opentelemetry-cpp/pull/2631)
+* [SDK] DefaultLogHandler to print errors to std::cerr, add LogLevel::None
+  [#2622](https://github.com/open-telemetry/opentelemetry-cpp/pull/2622)
 
 Important changes:
 
@@ -43,6 +47,23 @@ Important changes:
   * As part of this change, the script `ci/setup_cmake.sh` was renamed
     to `ci/setup_googletest.sh`, for clarity, now that this script
     only installs googletest.
+* [SDK] DefaultLogHandler to print to std::cerr, add LogLevel::None
+  [#2622](https://github.com/open-telemetry/opentelemetry-cpp/pull/2622)
+  * Change DefaultLogHandler output
+    * Before, the default internal logger, DefaultLogHandler,
+      used to print to std::cout.
+    * Now, DefaultLogHandler prints errors and warnings to std::cerr,
+      as expected, while printing info and debug messages to std::cout.
+    * Applications that expected to find the opentelemetry-cpp internal
+      error log in std::cout may need adjustments, either by looking
+      at std::cerr instead, or by using a custom log handler.
+  * Additional LogLevel::None
+    * LogLevel::None is a new supported log level, which does not print
+      any message.
+    * Custom log handlers may need to implement a new case, to avoid
+      compiler warnings.
+    * Numbering of log levels like OTEL_INTERNAL_LOG_LEVEL_ERROR
+      has changed, which requires to rebuild, as the SDK ABI differs.
 
 ## [1.14.2] 2024-02-27
 

INSTALL.md

@@ -85,6 +85,8 @@ You can link OpenTelemetry C++ SDK with libraries provided in
    - `-DWITH_OTLP_GRPC=ON` : To enable building OTLP GRPC exporter.
    - `-DWITH_OTLP_HTTP=ON` : To enable building OTLP HTTP exporter.
    - `-DWITH_PROMETHEUS=ON` : To enable building prometheus exporter.
+   - `-DOPENTELEMETRY_INSTALL=ON`: To install `otel-cpp` library needed
+      for external code linking.
 
 3. Once the build configuration is created, build the CMake targets - this
    includes building SDKs and unittests for API and SDK. Note that since API is