# uname -a
FreeBSD barracuda.acadix.biz 14.3-RELEASE-p2 FreeBSD 14.3-RELEASE-p2 GENERIC amd64

# clang --version
FreeBSD clang version 19.1.7 (https://github.com/llvm/llvm-project.git llvmorg-19.1.7-0-gcd708029e0b2)
Target: x86_64-unknown-freebsd14.3
Thread model: posix
InstalledDir: /usr/bin

# pkg info|grep -E 'opentelemetry|grpc|abseil'
abseil-20250127.1              Abseil Common Libraries (C++)
grpc-1.74.0,2                  HTTP/2-based RPC framework
opentelemetry-cpp-1.20.0       OpenTelemetry C++ client

# git describe --tags
v2.41.0-9-gc06d686e32

[ 50% 744/1457] /usr/bin/c++ -DGOOGLE_CLOUD_CPP_HAVE_OPENSSL -DOPENTELEMETRY_ABI_VERSION_NO=1 -DPROTOBUF_USE_DLLS -Dgoogle_cloud_cpp_opentelemetry_EXPORTS -I/usr/ports/wip/google-cloud-cpp/work/google-cloud-cpp-2.41.0-9-gc06d686e32 -isystem /usr/local/include -isystem /usr/ports/wip/google-cloud-cpp/work/.build -isystem /usr/ports/wip/google-cloud-cpp/work/.build/external/googleapis -isystem /usr/ports/wip/google-cloud-cpp/work/.build/google/cloud/monitoring -isystem /usr/ports/wip/google-cloud-cpp/work/.build/google/cloud/trace -O2 -pipe  -fstack-protector-strong -fno-strict-aliasing   -std=c++17 -O2 -pipe  -fstack-protector-strong -fno-strict-aliasing   -std=c++17  -DNDEBUG -fPIC -Wall -Wextra -Wconversion -Wno-sign-conversion -fno-exceptions -pthread -Wno-float-conversion -Wno-implicit-float-conversion -Wno-implicit-int-float-conversion -Wno-unknown-warning-option -DNOMINMAX -MD -MT google/cloud/opentelemetry/CMakeFiles/google_cloud_cpp_opentelemetry.dir/internal/monitored_resource.cc.o -MF google/cloud/opentelemetry/CMakeFiles/google_cloud_cpp_opentelemetry.dir/internal/monitored_resource.cc.o.d -o google/cloud/opentelemetry/CMakeFiles/google_cloud_cpp_opentelemetry.dir/internal/monitored_resource.cc.o -c /usr/ports/wip/google-cloud-cpp/work/google-cloud-cpp-2.41.0-9-gc06d686e32/google/cloud/opentelemetry/internal/monitored_resource.cc
FAILED: google/cloud/opentelemetry/CMakeFiles/google_cloud_cpp_opentelemetry.dir/internal/monitored_resource.cc.o 
/usr/bin/c++ -DGOOGLE_CLOUD_CPP_HAVE_OPENSSL -DOPENTELEMETRY_ABI_VERSION_NO=1 -DPROTOBUF_USE_DLLS -Dgoogle_cloud_cpp_opentelemetry_EXPORTS -I/usr/ports/wip/google-cloud-cpp/work/google-cloud-cpp-2.41.0-9-gc06d686e32 -isystem /usr/local/include -isystem /usr/ports/wip/google-cloud-cpp/work/.build -isystem /usr/ports/wip/google-cloud-cpp/work/.build/external/googleapis -isystem /usr/ports/wip/google-cloud-cpp/work/.build/google/cloud/monitoring -isystem /usr/ports/wip/google-cloud-cpp/work/.build/google/cloud/trace -O2 -pipe  -fstack-protector-strong -fno-strict-aliasing   -std=c++17 -O2 -pipe  -fstack-protector-strong -fno-strict-aliasing   -std=c++17  -DNDEBUG -fPIC -Wall -Wextra -Wconversion -Wno-sign-conversion -fno-exceptions -pthread -Wno-float-conversion -Wno-implicit-float-conversion -Wno-implicit-int-float-conversion -Wno-unknown-warning-option -DNOMINMAX -MD -MT google/cloud/opentelemetry/CMakeFiles/google_cloud_cpp_opentelemetry.dir/internal/monitored_resource.cc.o -MF google/cloud/opentelemetry/CMakeFiles/google_cloud_cpp_opentelemetry.dir/internal/monitored_resource.cc.o.d -o google/cloud/opentelemetry/CMakeFiles/google_cloud_cpp_opentelemetry.dir/internal/monitored_resource.cc.o -c /usr/ports/wip/google-cloud-cpp/work/google-cloud-cpp-2.41.0-9-gc06d686e32/google/cloud/opentelemetry/internal/monitored_resource.cc
/usr/ports/wip/google-cloud-cpp/work/google-cloud-cpp-2.41.0-9-gc06d686e32/google/cloud/opentelemetry/internal/monitored_resource.cc:225:10: error: no matching function for call to 'visit'
  225 |   return absl::visit(AsStringVisitor{}, attribute);
      |          ^~~~~~~~~~~
/usr/include/c++/v1/variant:1573:1: note: candidate template ignored: substitution failure [with _Visitor = AsStringVisitor, _Vs = <const opentelemetry::sdk::common::OwnedAttributeValue &>]: no matching function for call to '__as_variant'
 1153 | visit(_Visitor&& __visitor, _Vs&&... __vs) {
      | ^
1 error generated.