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I am trying to include Boost's thread library in my C++ project. My CMake file is like so:

cmake_minimum_required(VERSION 3.6) project(LearningC) find_package(Boost REQUIRED) include_directories(${Boost_INCLUDE_DIR}) set(CMAKE_CXX_STANDARD 11) set(SOURCE_FILES main.cpp Student.cpp Student.h) add_executable(LearningC ${SOURCE_FILES}) target_link_libraries(LearningC ${Boost_LIBRARIES})

I get an error:

Undefined symbols for architecture x86_64: "boost::this_thread::interruption_point()", referenced from: boost::condition_variable::wait(boost::unique_lock<boost::mutex>&) in main.cpp.o [More stack traces...]

What am I doing wrong?

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  • 1
    So you need to list 'thread' library in find_package(Boost) call: find_package(Boost COMPONENTS thread REQUIRED). Like there. Commented Dec 30, 2016 at 9:11
  • 1
    In my case I had to add find_package(Boost COMPONENTS thread system REQUIRED) and target_link_libraries(<target> ${Boost_LIBRARIES}) of course! Commented Oct 3, 2017 at 10:20

2 Answers 2

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Ok, I see you've found a solution, but there are some improvements I'd like to propose (as soon as you require CMake 3.6):

  • use imported targets to manage compiler/linker options per target, instead of "global" variables and functions (like include_directories(), ...)
  • use full signature of project() to define a bunch of PROJECT_xxx variables, then use them
  • provide explicit list of languages do you use to avoid default and possible redundant checks
  • in case of Boost, you don't need to find and link with implicit dependencies -- FindBoost.cmake would do it for you. Just specify components only what you really need and use.

Here is a modified CMakeLists.txt:

cmake_minimum_required(VERSION 3.6) project(LearningCxx VERSION 1.0.0 LANGUAGES CXX) set(CMAKE_CXX_STANDARD 11) set(CMAKE_CXX_STANDARD_REQUIRED ON) find_package(Boost COMPONENTS thread REQUIRED) add_executable( ${PROJECT_NAME} main.cpp Student.cpp ) target_link_libraries( ${PROJECT_NAME} Boost::thread )

Update: I've done an example for this project, but remove Students.cpp and replace main.cpp with the following code:

#include <boost/thread.hpp> #include <iostream> int main() { std::cout << boost::thread::hardware_concurrency() << std::endl; }

Here is my test run:

zaufi@gentop〉…/tests/boost-thread-cmake/build〉empty dir〉cmake .. -- The CXX compiler identification is GNU 5.4.0 -- Check for working CXX compiler: /usr/lib/outproc/bin/c++ -- works -- Detecting CXX compiler ABI info - done -- Detecting CXX compile features - done -- Looking for C++ include pthread.h - found -- Looking for pthread_create - not found -- Looking for pthread_create in pthreads - not found -- Looking for pthread_create in pthread - found -- Found Threads: TRUE -- Boost version: 1.62.0 -- Found the following Boost libraries: -- thread -- chrono -- system -- date_time -- atomic -- Configuring done -- Generating done -- Build files have been written to: /work/tests/boost-thread-cmake/build zaufi@gentop〉…/tests/boost-thread-cmake/build〉default〉pfx: /usr/local〉make Scanning dependencies of target LearningCxx [ 50%] Building CXX object CMakeFiles/LearningCxx.dir/main.cpp.o [100%] Linking CXX executable LearningCxx [100%] Built target LearningCxx zaufi@gentop〉…/tests/boost-thread-cmake/build〉default〉pfx: /usr/local〉ldd ./LearningCxx linux-vdso.so.1 (0x00007fff73b75000) libboost_thread.so.1.62.0 => /usr/lib64/libboost_thread.so.1.62.0 (0x00007fd1adafd000) libboost_chrono.so.1.62.0 => /usr/lib64/libboost_chrono.so.1.62.0 (0x00007fd1ad8f6000) libboost_system.so.1.62.0 => /usr/lib64/libboost_system.so.1.62.0 (0x00007fd1ad6f2000) libboost_date_time.so.1.62.0 => /usr/lib64/libboost_date_time.so.1.62.0 (0x00007fd1ad4e1000) libboost_atomic.so.1.62.0 => /usr/lib64/libboost_atomic.so.1.62.0 (0x00007fd1ad2df000) libpthread.so.0 => /lib64/libpthread.so.0 (0x00007fd1ad0c3000) libstdc++.so.6 => /usr/lib/gcc/x86_64-pc-linux-gnu/6.3.0/libstdc++.so.6 (0x00007fd1accc8000) libm.so.6 => /lib64/libm.so.6 (0x00007fd1ac9cd000) libgcc_s.so.1 => /usr/lib/gcc/x86_64-pc-linux-gnu/6.3.0/libgcc_s.so.1 (0x00007fd1ac7b6000) libc.so.6 => /lib64/libc.so.6 (0x00007fd1ac41d000) librt.so.1 => /lib64/librt.so.1 (0x00007fd1ac215000) /lib64/ld-linux-x86-64.so.2 (0x00007fd1add25000) zaufi@gentop〉…/tests/boost-thread-cmake/build〉default〉pfx: /usr/local〉cmake --version cmake version 3.7.1
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2 Comments

By "implicit dependencies"... do you mean the system library? If so, I had it removed and the compiler was complaining with: Undefined symbols for architecture x86_64: "boost::system::system_category()"
@MikeM, as far as I recall FindBoost.cmake is capable to find and link w/ implicit deps in CMake 3.6 as well... check _Boost_MISSING_DEPENDENCIES function in this module...
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I found a solution. Basically, Boost has most of its code in C++ headers (.hpp). Some of the libraries however need to be compiled and linked... The code below works!

cmake_minimum_required(VERSION 3.6) project(LearningC) set(CMAKE_CXX_STANDARD 11) set(SOURCE_FILES main.cpp Student.cpp Student.h) add_executable(LearningC ${SOURCE_FILES}) find_package(Boost COMPONENTS thread system REQUIRED) include_directories(${Boost_INCLUDE_DIR}) target_link_libraries(LearningC ${Boost_LIBRARIES})
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