Ros catkin_make fail with Qt

Question

I'm getting this error when I catkin_make my workspace:

[100%] Linking CXX executable /home/ankilp/test_ws/devel/lib/lidar_depth/lidar_depth
/usr/bin/ld: cannot find -lQt5::Widgets

This is my CMakeList file:

    cmake_minimum_required(VERSION 2.8.3)
project(lidar_depth)

## Compile as C++11, supported in ROS Kinetic and newer
add_compile_options(-std=c++11)

find_package(catkin REQUIRED COMPONENTS
  roscpp
  rospy
  std_msgs
  genmsg
)

find_package( PCL REQUIRED)
find_package(Qt4 COMPONENTS QtCore QtGui REQUIRED)

include(${QT_USE_FILE})

add_definitions(-DQT_NO_KEYWORDS)

catkin_package(

)

###########
## Build ##
###########

## Specify additional locations of header files
## Your package locations should be listed before other locations
include_directories(
# include
  ${catkin_INCLUDE_DIRS}
  ${PCL_INCLUDE_DIRS}
)

link_directories(${PCL_LIBRARY_DIRS})
add_definitions(${PCL_DEFINITIONS})

add_executable(${PROJECT_NAME} src/LidarDepth.cpp src/Projection_matrices.hpp)

target_link_libraries(${PROJECT_NAME}
   ${catkin_LIBRARIES}
   ${PCL_LIBRARIES}
   ${QT_LIBRARIES}
)

I don't explicitly use anything related to Qt. I installed Qt5 separately but the problem persists. Is there a separate process to link Qt to my system?

Are you using ROS Kinetic and Ubuntu 16.04? – adamconkey Jul 19 '18 at 18:35 — adamconkey, Jul 19 '18 at 18:35

score 1 · Answer 1 · answered Jul 20 '18 at 20:55

It looks like you're using at least ROS Kinetic (based on the comment where you add compile options). Most things in Kinetic depend on Qt5 instead of Qt4. Try making the following changes to your CMakeLists.txt file:

Replace this line

find_package(Qt4 COMPONENTS QtCore QtGui REQUIRED)

with these lines

find_package(Qt5 COMPONENTS Core Gui Widgets REQUIRED)
set(QT_LIBRARIES Qt5::Widgets)

If this doesn't work for you, leave a comment as I have a working CMakeLists.txt file for Qt5 in Kinetic and can probably determine what else needs changed, but I think that is the minimal change to make.

score 0 · Answer 2 · answered Jul 19 '18 at 06:54

If you have installed Qt seperately, you have to tell CMAKE where it can find you installation. This can be done by specifying the CMAKE_PREFIX_PATH inside the CMakeLists.txt file or in the terminal before executing cmake (ref). E.g.:

$ export CMAKE_PREFIX_PATH=/location/to/you/installation

Ros catkin_make fail with Qt

2 Answers2