Add missing find_package

[kledom]

Add missing find_package call

Signed-off-by: Dominik Kleiser KleiserDominik@outlook.com

[ravijo]

Hi @kledom

Thank you very much for your suggestion. I am a bit concerned about find_package(Threads REQUIRED) right now. I will point my reasons below-

1. For newer versions, i.e., CMake 3.9+, the find_package(Threads REQUIRED) is not required.

2. For older versions, i.e., CMake < 3.9, the find_package(Threads REQUIRED) is required.

   The reference for the above two points can be found here.

3. In our CMakeLists.txt , we are supporting cmake_minimum_required(VERSION 2.8.3).

4. As per the webpage here, we also need to set target_link_libraries while using find_package(OpenMP).

5. A Github page here shows that find_package(Threads REQUIRED) is not required and set CMAKE_CXX_FLAGS as set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${OpenMP_CXX_FLAGS}") as we are doing.

6. Additionally, an answer given in SO doesn't mention the need for using find_package(Threads REQUIRED).

Considering all the points mentioned above, what is your opinion? What do you think?

[kledom]

Thank you for looking into this.

I'm running on Ubuntu 18.04 with ROS Melodic and CMake 3.17.1.
Without

find_package(Threads REQUIRED)

building fails with the error message

/usr/bin/ld: cannot find -lThreads::Threads

I'm not sure when this line is needed or not.

[ravijo]

I am glad to see that you made a workaround quickly by adding find_package(Threads REQUIRED)

I'm running on Ubuntu 18.04 with ROS Melodic and CMake 3.17.1.

For now,

• I mark it "help wanted" as we need to reproduce it on multiple machines to confirm.
• I am keeping this task on my todo list.

As always, feel free to add your comments/suggestions, please.

[kledom]

I'll close this request. I think the issue you created is the better place for this discussion.

[ravijo]

Hi @kledom

I just wanted to give you an update on this issue. Please check here.

Thanks!