Installation: Build Error

[decada-robotics]

Bug report

Required information:

Using Ubuntu 20.04, ROS2 Galactic, Installing from Source.

Description of the bug

Hi building from source works smoothly in my other computers but for my current desktop I'm facing this error:

--- stderr: rmf_battery
/usr/bin/ld: /home/msi/workspace/trl_ws/install/rmf_traffic/lib/librmf_traffic.so: undefined reference to `pthread_rwlock_unlock'
/usr/bin/ld: /home/msi/workspace/trl_ws/install/rmf_traffic/lib/librmf_traffic.so: undefined reference to `pthread_rwlock_trywrlock'
/usr/bin/ld: /home/msi/workspace/trl_ws/install/rmf_traffic/lib/librmf_traffic.so: undefined reference to `pthread_rwlock_tryrdlock'
collect2: error: ld returned 1 exit status
make[2]: *** [CMakeFiles/test_rmf_battery.dir/build.make:147: test_rmf_battery] Error 1
make[1]: *** [CMakeFiles/Makefile2:80: CMakeFiles/test_rmf_battery.dir/all] Error 2
make: *** [Makefile:141: all] Error 2
---

I tried searching online to find for solutions but couldn't find any. Would appreciate any help!

[mxgrey]

Linkers can be very tricky and inconsistent.

Could you try out the branch link_threads from this PR: open-rmf/rmf_traffic#74 ?

Let me know if that solves this issue.

[samuelrawrs]

Hi, it solved the issue for rmf_traffic but other packages such as rmf_task_ros2 failed but we've managed to fix them for our system.

Here's a pull request for the fixes.

[mxgrey]

Using -lpthread isn't portable, so we should use find_package(Threads) and Threads::Threads similar to the rmf_traffic PR.

[samuelrawrs]

Oops okay I've edited it to use Threads::Threads and have double checked that the build still works. Thanks!