Fix compile warnings and add a clarifying comment. (#105)

cartographer_ros/cartographer_ros/node_main.cc

@@ -333,7 +333,6 @@ bool Node::HandleSubmapQuery(
   response.height = response_proto.height();
   response.resolution = response_proto.resolution();
 
-  auto pose = carto::transform::ToRigid3(response_proto.slice_pose());
   response.slice_pose.position.x =
       response_proto.slice_pose().translation().x();
   response.slice_pose.position.y =

cartographer_rviz/cartographer_rviz/submaps_display.cc

@@ -91,7 +91,7 @@ void SubmapsDisplay::reset() {
 void SubmapsDisplay::processMessage(
     const ::cartographer_ros_msgs::SubmapList::ConstPtr& msg) {
   ::cartographer::common::MutexLocker locker(&mutex_);
-  for (int trajectory_id = 0; trajectory_id < msg->trajectory.size();
+  for (size_t trajectory_id = 0; trajectory_id < msg->trajectory.size();
        ++trajectory_id) {
     if (trajectory_id >= trajectories_.size()) {
       trajectories_.emplace_back();
@@ -99,7 +99,7 @@ void SubmapsDisplay::processMessage(
     auto& trajectory = trajectories_[trajectory_id];
     const std::vector<::cartographer_ros_msgs::SubmapEntry>& submap_entries =
         msg->trajectory[trajectory_id].submap;
-    for (int submap_id = 0; submap_id < submap_entries.size(); ++submap_id) {
+    for (size_t submap_id = 0; submap_id < submap_entries.size(); ++submap_id) {
       if (submap_id >= trajectory.size()) {
         trajectory.push_back(
             ::cartographer::common::make_unique<DrawableSubmap>(

cartographer_rviz/cartographer_rviz/submaps_display.h

@@ -53,6 +53,7 @@ class SubmapsDisplay
  private:
   void CreateClient();
 
+  // These are called by RViz and therefore do not adhere to the style guide.
   void onInitialize() override;
   void reset() override;
   void processMessage(