CMake Error at CMakeLists.txt:21 (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. ---

这个错误是由于CMake无法在CMAKE_MODULE_PATH中找到"std_msg.cmake"包配置文件。它提示你需要将"std_msg"的安装前缀添加到CMAKE_PREFIX_PATH中，或者将"std_msg_DIR"设置为包含上述文件之一的目录。如果"std_msg"提供了单独的开发包或SDK，请确保已经安装。你需要检查一下CMakeLists.txt中的第21行，看看是否正确地配置了"std_msg"的路径。