Question

I’m trying to compile a boost tutorial example from http://www.boost.org/doc/libs/1_36_0/doc/html/boost_asio/tutorial/tuttimer1.html.

My CMakeLists.txt looks like the following:

project(boost)
add_executable(timer1 timer1.cpp)
set_target_properties(timer1 PROPERTIES LINK_FLAGS -lboost_system,-lpthread)

trying to build the whole thing with cmake, I get:

/var/www/C++/boost/build$ make
-- Configuring done
-- Generating done
-- Build files have been written to: /var/www/C++/boost/build
Scanning dependencies of target timer1
[100%] Building CXX object CMakeFiles/timer1.dir/timer1.cpp.o                                                                                                    
Linking CXX executable timer1                                                                                                                                    
/usr/bin/ld: cannot find -lboost_system,-lpthread                                                                                                                
collect2: ld returned 1 exit status
make[2]: *** [timer1] Błąd 1
make[1]: *** [CMakeFiles/timer1.dir/all] Błąd 2
make: *** [all] Błąd 2

But when I run:

g++ timer1.cpp -lboost_system -lpthread -o timer1

manually, everything works fine. Can someone please point me on what do I do wrong?

PS
When I try to use solution described in Turning on linker flags with CMake, I add to cmake the following lines:

set(CMAKE_SHARED_LINKER_FLAGS "-lboost_system,-lpthread")
set(CMAKE_MODULE_LINKER_FLAGS "-lboost_system,-lpthread")
set(CMAKE_EXE_LINKER_FLAGS "-lboost_system,-lpthread")

and I get the same error as above.

Answer 1

I strongly suggest that you use the CMake integrated FindPackage. CMake will find boost and pthreads for you.

Your CMakeLists.txt should look like this:

find_package( Boost COMPONENTS thread system filesystem REQUIRED ) #whatever libs you need
include_directories( ${Boost_INCLUDE_DIRS} )
find_package( Threads )

In the subfolder src:

set( LIBS_TO_LINK
    ${Boost_LIBRARIES}
    ${CMAKE_THREAD_LIBS_INIT}
)

target_link_libraries( myApp
    ${LIBS_TO_LINK}
)