编译ros2时候报错如下：                  
CMake Error at CMakeLists.txt:11 (find_package):
  By not providing "Findstd_msg.cmake" in CMAKE_MODULE_PATH this project has
  asked CMake to find a package configuration file provided by "std_msg", but
  CMake did not find one.

  Could not find a package configuration file provided by "std_msg" with any
  of the following names:

    std_msgConfig.cmake
    std_msg-config.cmake

  Add the installation prefix of "std_msg" to CMAKE_PREFIX_PATH or set
  "std_msg_DIR" to a directory containing one of the above files.  If
  "std_msg" provides a separate development package or SDK, be sure it has
  been installed.

解决方法：

打开目录下的 package.xml 和 CMakeLists.txt 把所有的 std_msg 改成 std_msgs，保存并退出，重新编译即可。