ros package 由于依赖 msg 导致编译问题解决

1. 问题

经常我们会自定义一些 msg 给其他的 package 使用, 如果正常写 CmakeLists.txt 在编译的时候,就会提示没有找到依赖的 msg.
需要先编译 msg 的 package, 再编译其他的 package , 这就很麻烦

2. 解决

想到 lego-loam 里面也是依赖 cloud_info.msg, 但是编译的时候却不会出现这个问题, 看一下他是怎么写的 CmakeLists.txt 的:

cmake_minimum_required(VERSION 2.8.3)
project(lego_loam)

set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -O3")

find_package(catkin REQUIRED COMPONENTS
  tf
  roscpp
  rospy
  cv_bridge
  image_transport

  pcl_ros
  pcl_conversions

  std_msgs
  sensor_msgs
  geometry_msgs
  nav_msgs
  cloud_msgs
  common
)

find_package(Boost REQUIRED COMPONENTS system thread timer)
find_package(GTSAM REQUIRED QUIET)
find_package(PCL REQUIRED QUIET)
find_package(OpenCV REQUIRED QUIET)

catkin_package(
  INCLUDE_DIRS include
  CATKIN_DEPENDS cloud_msgs
  DEPENDS PCL
)

include_directories(
	include
	${catkin_INCLUDE_DIRS}
	${PCL_INCLUDE_DIRS}
	${OpenCV_INCLUDE_DIRS}
	${GTSAM_INCLUDE_DIR}
)

link_directories(
	include
	${OpenCV_LIBRARY_DIRS}
	${PCL_LIBRARY_DIRS}
	${GTSAM_LIBRARY_DIRS}
)

add_executable(imageProjection src/imageProjection.cpp)
add_dependencies(imageProjection ${catkin_EXPORTED_TARGETS} cloud_msgs_gencpp)
target_link_libraries(imageProjection ${catkin_LIBRARIES} ${PCL_LIBRARIES} ${OpenCV_LIBRARIES})

add_executable(featureAssociation src/featureAssociation.cpp)
add_dependencies(featureAssociation ${catkin_EXPORTED_TARGETS} cloud_msgs_gencpp)
target_link_libraries(featureAssociation ${catkin_LIBRARIES} ${PCL_LIBRARIES} ${OpenCV_LIBRARIES})

add_executable(mapOptmization src/mapOptmization.cpp)
target_link_libraries(mapOptmization ${catkin_LIBRARIES} ${PCL_LIBRARIES} ${OpenCV_LIBRARIES} gtsam)

add_executable(transformFusion src/transformFusion.cpp)
target_link_libraries(transformFusion ${catkin_LIBRARIES} ${PCL_LIBRARIES} ${OpenCV_LIBRARIES})

可以看到:

add_executable(imageProjection src/imageProjection.cpp)
add_dependencies(imageProjection ${catkin_EXPORTED_TARGETS} cloud_msgs_gencpp)
target_link_libraries(imageProjection ${catkin_LIBRARIES} ${PCL_LIBRARIES} ${OpenCV_LIBRARIES})

多了一行:

add_dependencies(imageProjection ${catkin_EXPORTED_TARGETS} cloud_msgs_gencpp)

使用 add_dependencies 添加了 依赖 cloud_msgs_gencpp

如果缺少 add_dependencies 中对 cloud_msgs_gencpp 的依赖声明，在编译的时候如果先编译imageProjection 包再编译 cloud_msgs 包则会出现报错.

ROS工作空间各个软件包的编译顺序是随机的，此时头文件cloud_msgs/cloud_info.h 还未生成