ROS2 C++服务文件编译报错排查：格式化符与链接错误问题

问题说明 #

编译ROS2 C++服务节点时，最初怀疑打印int变量的%d格式化符有问题，改成%ld后出现新的链接错误，提示未找到rosidl_typesupport_cpp::get_message_type_support_handle<geometry_msgs::msg::PoseStamped_<std::allocator<void>>>()的定义。

报错日志 #

> Starting >>> my_cpp_pkg
> --- stderr: my_cpp_pkg                              /usr/bin/ld: CMakeFiles/turtlebot_goal.dir/src/turtlebot_goal.cpp.o: in function
> `rclcpp::Publisher<geometry_msgs::msg::PoseStamped_<std::allocator<void>
> >, std::allocator<void> >::Publisher(rclcpp::node_interfaces::NodeBaseInterface*, std::__cxx11::basic_string<char, std::char_traits<char>,
> std::allocator<char> > const&, rclcpp::QoS const&,
> rclcpp::PublisherOptionsWithAllocator<std::allocator<void> > const&)':
> turtlebot_goal.cpp:(.text._ZN6rclcpp9PublisherIN13geometry_msgs3msg12PoseStamped_ISaIvEEES4_EC2EPNS_15node_interfaces17NodeBaseInterfaceERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEERKNS_3QoSERKNS_29PublisherOptionsWithAllocatorIS4_EE[_ZN6rclcpp9PublisherIN13geometry_msgs3msg12PoseStamped_ISaIvEEES4_EC5EPNS_15node_interfaces17NodeBaseInterfaceERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEERKNS_3QoSERKNS_29PublisherOptionsWithAllocatorIS4_EE]+0x6e):
> undefined reference to `rosidl_message_type_support_t const*
> rosidl_typesupport_cpp::get_message_type_support_handle<geometry_msgs::msg::PoseStamped_<std::allocator<void>
> > >()' collect2: error: ld returned 1 exit status make[2]: *** [CMakeFiles/turtlebot_goal.dir/build.make:145: turtlebot_goal] Error 1
> make[1]: *** [CMakeFiles/Makefile2:389:
> CMakeFiles/turtlebot_goal.dir/all] Error 2 make: *** [Makefile:146:
> all] Error 2
> --- Failed   <<< my_cpp_pkg [0.26s, exited with code 2]

服务端代码 #

#include "rclcpp/rclcpp.hpp"
#include "example_interfaces/srv/add_two_ints.hpp"

using std::placeholders::_1;
using std::placeholders::_2;

class AddTwoIntsServerNode : public rclcpp::Node
{
public:
    AddTwoIntsServerNode() : Node("add_two_ints_server")
    {
        server_ = this->create_service<example_interfaces::srv::AddTwoInts>(
            "add_two_ints",
            std::bind(&AddTwoIntsServerNode::callbackAddTwoInts, this, _1, _2));
        RCLCPP_INFO(this->get_logger(), "Service server has been started.");
    }

private:
    void callbackAddTwoInts(const example_interfaces::srv::AddTwoInts::Request::SharedPtr request,
                            const example_interfaces::srv::AddTwoInts::Response::SharedPtr response)
    {
        response->sum = request->a + request->b;
        RCLCPP_INFO(this->get_logger(), "%d + %d = %d", request->a, request->b, response->sum);
    }

    rclcpp::Service<example_interfaces::srv::AddTwoInts>::SharedPtr server_;
};

int main(int argc, char **argv)
{
    rclcpp::init(argc, argv);
    auto node = std::make_shared<AddTwoIntsServerNode>();
    rclcpp::spin(node);
    rclcpp::shutdown();
    return 0;
}

错误分析 #

1. 链接错误根源：报错指向turtlebot_goal.cpp文件，而非当前贴出的服务端代码。该文件中创建了geometry_msgs::msg::PoseStamped类型的Publisher，但编译配置中未正确引入geometry_msgs包的依赖，导致链接时找不到类型支持函数。
2. 格式化符问题：example_interfaces/srv/AddTwoInts中的a、b、sum均为int32_t类型，在多数系统中与int兼容，使用%d完全正确，无需改为%ld，修改后反而可能引发类型不匹配警告。

修复方案 #

1. 修正CMakeLists.txt依赖 #

找到包中的CMakeLists.txt，针对turtlebot_goal编译目标添加geometry_msgs依赖：

• 在find_package段添加：

find_package(geometry_msgs REQUIRED)

• 在add_executable之后的ament_target_dependencies中加入geometry_msgs：

ament_target_dependencies(turtlebot_goal
  rclcpp
  geometry_msgs
)

2. 恢复格式化符（若已修改） #

将服务端代码中RCLCPP_INFO里的%ld改回%d，匹配int32_t类型的变量。

内容的提问来源于stack exchange，提问作者gurselturkeri