File "PCLConfig.cmake" will unexpectedly change BOOST_ROOT and lead to link error

[Jialiang Kang]

In PCLConfig.cmake line 115&116 says:

if(PCL_ALL_IN_ONE_INSTALLER)
    set(BOOST_ROOT "${PCL_ROOT}/3rdParty/Boost")

,in which PCL_ALL_IN_ONE_INSTALLER has already set to be ON in line 435 through a normal apt install procedure. That will lead to a link error of libboost, if we firstly find boost and then find pcl. The following is a simple example of CMakeList.txt:

cmake_minimum_required(VERSION 3.16)

project(main)

find_package(
  Boost
  COMPONENTS
  system
  thread
  chrono
  REQUIRED
  )
find_package(
  PCL
  REQUIRED
  )

include_directories(
  ${Boost_INCLUDE_DIRS}
  )
link_directories(
  ${Boost_LIBRARY_DIRS}
  )

add_executable(main main.cpp)

target_link_libraries(
 main
 ${Boost_LIBRARIES}
 )

Any used boost functions in main.cpp will lead to link error like this: main.cpp:5: undefined reference to `boost::thread::hardware_concurrency()', even though pcl remains unused in the cpp file. Simply move find_package(Boost ...) to the back of find_package(PCL ...) will solve the problem, because now we are using the boost lib provided by pcl.However, such a solution is not stragihtforward at all anc hart to be figured out. Hope you can help to remove such a confusing change of BOOST_ROOT, given that libboost-dev can also easily get installed by apt and already exists in many ubuntus.

[Jochen Sprickerhof (v-launchpad-jochen-sprickerhof-de)]

I assume you are using libpcl-dev_1.10.0 (Ubuntu 20.04) or libpcl-dev_1.11.1 (Ubuntu 20.10 and 21.04) based on that line 435 should set PCL_ALL_IN_ONE_INSTALLER to ON. That would be this line in git: https://github.com/PointCloudLibrary/pcl/blob/pcl-1.11.1/PCLConfig.cmake.in#L411
PCL_ROOT is set to /usr in the package, so there would need to be a /usr/3rdParty folder on your system to trigger this behavior. That is not a path provided by Ubuntu and I would propose to remove it from your system and see if it fixes your problem.

I've send a PR upstream to fix this: https://github.com/PointCloudLibrary/pcl/pull/4821

[Launchpad Janitor (janitor)]

This bug was fixed in the package pcl - 1.12.0+dfsg-5build1

---------------
pcl (1.12.0+dfsg-5build1) jammy; urgency=medium

  * No-change rebuild against libproj22

 -- Graham Inggs <email address hidden> Fri, 29 Oct 2021 05:22:15 +0000