Could not find the following Boost libraries: boost_asio

Question

When I try to compile my cmake project, which uses boost and asio, with make I get these errors:

CMakeFiles/client-network-handler-test.dir/main.cpp.o: In function `__cxx_global_var_init1':
/usr/include/boost/system/error_code.hpp:222: undefined reference to `boost::system::generic_category()'    CMakeFiles/client-network-handler-test.dir/main.cpp.o: In function `__cxx_global_var_init1':
/usr/include/boost/system/error_code.hpp:222: undefined reference to `boost::system::generic_category()'
CMakeFiles/client-network-handler-test.dir/main.cpp.o: In function `__cxx_global_var_init2':
/usr/include/boost/system/error_code.hpp:223: undefined reference to `boost::system::generic_category()'
CMakeFiles/client-network-handler-test.dir/main.cpp.o: In function `__cxx_global_var_init3':
/usr/include/boost/system/error_code.hpp:224: undefined reference to `boost::system::system_category()'
CMakeFiles/client-network-handler-test.dir/main.cpp.o: In function `boost::asio::error::get_system_category()':
/usr/include/boost/asio/error.hpp:216: undefined reference to `boost::system::system_category()'
../../lib/libclient-network-handler.a(ClientNetworkHandler.cpp.o): In function `__cxx_global_var_init1':
/usr/include/boost/system/error_code.hpp:222: undefined reference to `boost::system::generic_category()'
../../lib/libclient-network-handler.a(ClientNetworkHandler.cpp.o): In function `__cxx_global_var_init2':
/usr/include/boost/system/error_code.hpp:223: undefined reference to `boost::system::generic_category()'
../../lib/libclient-network-handler.a(ClientNetworkHandler.cpp.o): In function `__cxx_global_var_init3':
/usr/include/boost/system/error_code.hpp:224: undefined reference to `boost::system::system_category()'
../../lib/libclient-network-handler.a(ClientNetworkHandler.cpp.o): In function `boost::network::uri::uri::parse()':
/home/darren/373project/include/boost/network/uri/uri.hpp:178: undefined reference to `boost::network::uri::detail::parse(__gnu_cxx::__normal_iterator<char const*, std::string>, __gnu_cxx::__normal_iterator<char const*, std::string>, boost::network::uri::detail::uri_parts<__gnu_cxx::__normal_iterator<char const*, std::string> >&)'
../../lib/libclient-network-handler.a(ClientNetworkHandler.cpp.o): In function `error_code':
/usr/include/boost/system/error_code.hpp:323: undefined reference to `boost::system::system_category()'
CMakeFiles/client-network-handler-test.dir/main.cpp.o: In function `__cxx_global_var_init2':
/usr/include/boost/system/error_code.hpp:223: undefined reference to `boost::system::generic_category()'
CMakeFiles/client-network-handler-test.dir/main.cpp.o: In function `__cxx_global_var_init3':
/usr/include/boost/system/error_code.hpp:224: undefined reference to `boost::system::system_category()'
CMakeFiles/client-network-handler-test.dir/main.cpp.o: In function `boost::asio::error::get_system_category()':
/usr/include/boost/asio/error.hpp:216: undefined reference to `boost::system::system_category()'
../../lib/libclient-network-handler.a(ClientNetworkHandler.cpp.o): In function `__cxx_global_var_init1':
/usr/include/boost/system/error_code.hpp:222: undefined reference to `boost::system::generic_category()'
../../lib/libclient-network-handler.a(ClientNetworkHandler.cpp.o): In function `__cxx_global_var_init2':
/usr/include/boost/system/error_code.hpp:223: undefined reference to `boost::system::generic_category()'
../../lib/libclient-network-handler.a(ClientNetworkHandler.cpp.o): In function `__cxx_global_var_init3':
/usr/include/boost/system/error_code.hpp:224: undefined reference to `boost::system::system_category()'
../../lib/libclient-network-handler.a(ClientNetworkHandler.cpp.o): In function `boost::network::uri::uri::parse()':
/home/myUserName/373project/include/boost/network/uri/uri.hpp:178: undefined reference to `boost::network::uri::detail::parse(__gnu_cxx::__normal_iterator<char const*, std::string>, __gnu_cxx::__normal_iterator<char const*, std::string>, boost::network::uri::detail::uri_parts<__gnu_cxx::__normal_iterator<char const*, std::string> >&)'
../../lib/libclient-network-handler.a(ClientNetworkHandler.cpp.o): In function `error_code':
/usr/include/boost/system/error_code.hpp:323: undefined reference to `boost::system::system_category()'

I gather that the asio library cannot be found. So I add this line to my root CMakeLists.txt:

find_package(Boost 1.54.0 REQUIRED)

And CMake can find all the relevant libraries, as shown by this part of the build log:

-- Found the following Boost libraries:
--   unit_test_framework
--   system
--   regex
--   date_time
--   thread
--   filesystem
--   program_options
--   chrono
--   atomic

But compilation still produces the first error listed. When I change that CMake line to:

find_package(Boost 1.54.0 REQUIRED asio)

I get this message from CMake:

CMake Error at /usr/share/cmake-2.8/Modules/FindBoost.cmake:1131 (message):
  Unable to find the requested Boost libraries.

  Boost version: 1.54.0

  Boost include path: /usr/include

  Could not find the following Boost libraries:

          boost_asio

I have all the Boost libraries installed, as you can see, and I can't understand why it can't find asio.

Are you compiling a library or an executable? It's pretty important, because how you must configure boost for correctly using asio changes whether you're building asio into a lib or not. — user562566

Fraser Fraser · Accepted Answer · 2015-10-12T23:18:36

Boost.Asio is a header-only library - i.e. it doesn't need linked to your application.

From the docs for CMake's FindBoost module:

This module finds headers and requested component libraries

(emphasis mine).

In other words, find_package(Boost ...) should only be used to find Boost libraries which are non-header-only, as listed in the Boost docs.

From your linker errors, it looks like you do need to link Boost.System though:

find_package(Boost 1.54.0 REQUIRED system)
target_include_directories(MyExe PRIVATE ${Boost_INCLUDE_DIRS})
target_link_libraries(MyExe ${Boost_LIBRARIES})

Could not find the following Boost libraries: boost_asio

1 Answers