[CI] Check compiler warnings. (dmlc#9444)

Author: trivialfis

plugin/federated/federated_server.cc

@@ -14,24 +14,24 @@
 namespace xgboost {
 namespace federated {
 
-grpc::Status FederatedService::Allgather(grpc::ServerContext* context,
-                                         AllgatherRequest const* request, AllgatherReply* reply) {
+grpc::Status FederatedService::Allgather(grpc::ServerContext*, AllgatherRequest const* request,
+                                         AllgatherReply* reply) {
   handler_.Allgather(request->send_buffer().data(), request->send_buffer().size(),
                      reply->mutable_receive_buffer(), request->sequence_number(), request->rank());
   return grpc::Status::OK;
 }
 
-grpc::Status FederatedService::Allreduce(grpc::ServerContext* context,
-                                         AllreduceRequest const* request, AllreduceReply* reply) {
+grpc::Status FederatedService::Allreduce(grpc::ServerContext*, AllreduceRequest const* request,
+                                         AllreduceReply* reply) {
   handler_.Allreduce(request->send_buffer().data(), request->send_buffer().size(),
                      reply->mutable_receive_buffer(), request->sequence_number(), request->rank(),
                      static_cast<xgboost::collective::DataType>(request->data_type()),
                      static_cast<xgboost::collective::Operation>(request->reduce_operation()));
   return grpc::Status::OK;
 }
 
-grpc::Status FederatedService::Broadcast(grpc::ServerContext* context,
-                                         BroadcastRequest const* request, BroadcastReply* reply) {
+grpc::Status FederatedService::Broadcast(grpc::ServerContext*, BroadcastRequest const* request,
+                                         BroadcastReply* reply) {
   handler_.Broadcast(request->send_buffer().data(), request->send_buffer().size(),
                      reply->mutable_receive_buffer(), request->sequence_number(), request->rank(),
                      request->root());

tests/ci_build/build_via_cmake.sh

@@ -24,7 +24,7 @@ fi
 rm -rf build
 mkdir build
 cd build
-cmake .. ${cmake_args} -DGOOGLE_TEST=ON -DUSE_DMLC_GTEST=ON -DCMAKE_VERBOSE_MAKEFILE=ON -DENABLE_ALL_WARNINGS=ON -GNinja ${cmake_prefix_flag} -DHIDE_CXX_SYMBOLS=ON
+cmake .. ${cmake_args} -DGOOGLE_TEST=ON -DUSE_DMLC_GTEST=ON -DCMAKE_VERBOSE_MAKEFILE=ON -DENABLE_ALL_WARNINGS=ON -DCMAKE_COMPILE_WARNING_AS_ERROR=ON -GNinja ${cmake_prefix_flag} -DHIDE_CXX_SYMBOLS=ON
 ninja clean
 time ninja -v
 cd ..