Unusual C++ linker error - 'Defined in discard

I am attempting to link my program executable, but I keep getting errors.

Having

boost::this_thread::sleep(boost::posix_time::milliseconds(10));

in my source code yields the following error in the linker:

`.text._ZN5boost16exception_detail19error_info_injectorISt13runtime_errorED2Ev' referenced in section `.text._ZN5boost16exception_detail19error_info_injectorISt13runtime_errorED1Ev[non-virtual thunk to boost::exception_detail::error_info_injector<std::runtime_error>::~error_info_injector()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail19error_info_injectorISt13runtime_errorED2Ev[_ZN5boost16exception_detail19error_info_injectorISt13runtime_errorED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)
`.text._ZN5boost16exception_detail19error_info_injectorINS_9gregorian16bad_day_of_monthEED2Ev' referenced in section `.text._ZN5boost16exception_detail19error_info_injectorINS_9gregorian16bad_day_of_monthEED1Ev[non-virtual thunk to boost::exception_detail::error_info_injector<boost::gregorian::bad_day_of_month>::~error_info_injector()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail19error_info_injectorINS_9gregorian16bad_day_of_monthEED2Ev[_ZN5boost16exception_detail19error_info_injectorINS_9gregorian16bad_day_of_monthEED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)
`.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian8bad_yearEEEED2Ev' referenced in section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian8bad_yearEEEED1Ev[non-virtual thunk to boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::gregorian::bad_year> >::~clone_impl()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian8bad_yearEEEED2Ev[_ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian8bad_yearEEEED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)
`.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian8bad_yearEEEED2Ev' referenced in section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian8bad_yearEEEED1Ev[non-virtual thunk to boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::gregorian::bad_year> >::~clone_impl()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian8bad_yearEEEED2Ev[_ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian8bad_yearEEEED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)
`.text._ZN5boost16exception_detail19error_info_injectorINS_9gregorian8bad_yearEED2Ev' referenced in section `.text._ZN5boost16exception_detail19error_info_injectorINS_9gregorian8bad_yearEED1Ev[non-virtual thunk to boost::exception_detail::error_info_injector<boost::gregorian::bad_year>::~error_info_injector()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail19error_info_injectorINS_9gregorian8bad_yearEED2Ev[_ZN5boost16exception_detail19error_info_injectorINS_9gregorian8bad_yearEED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)
`.text._ZN5boost16exception_detail19error_info_injectorINS_9gregorian9bad_monthEED2Ev' referenced in section `.text._ZN5boost16exception_detail19error_info_injectorINS_9gregorian9bad_monthEED1Ev[non-virtual thunk to boost::exception_detail::error_info_injector<boost::gregorian::bad_month>::~error_info_injector()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail19error_info_injectorINS_9gregorian9bad_monthEED2Ev[_ZN5boost16exception_detail19error_info_injectorINS_9gregorian9bad_monthEED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)
`.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian16bad_day_of_monthEEEED2Ev' referenced in section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian16bad_day_of_monthEEEED1Ev[non-virtual thunk to boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::gregorian::bad_day_of_month> >::~clone_impl()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian16bad_day_of_monthEEEED2Ev[_ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian16bad_day_of_monthEEEED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)
`.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian16bad_day_of_monthEEEED2Ev' referenced in section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian16bad_day_of_monthEEEED1Ev[non-virtual thunk to boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::gregorian::bad_day_of_month> >::~clone_impl()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian16bad_day_of_monthEEEED2Ev[_ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian16bad_day_of_monthEEEED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)
`.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorISt13runtime_errorEEED2Ev' referenced in section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorISt13runtime_errorEEED1Ev[non-virtual thunk to boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<std::runtime_error> >::~clone_impl()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorISt13runtime_errorEEED2Ev[_ZN5boost16exception_detail10clone_implINS0_19error_info_injectorISt13runtime_errorEEED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)
`.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorISt13runtime_errorEEED2Ev' referenced in section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorISt13runtime_errorEEED1Ev[non-virtual thunk to boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<std::runtime_error> >::~clone_impl()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorISt13runtime_errorEEED2Ev[_ZN5boost16exception_detail10clone_implINS0_19error_info_injectorISt13runtime_errorEEED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)
`.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian9bad_monthEEEED2Ev' referenced in section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian9bad_monthEEEED1Ev[non-virtual thunk to boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::gregorian::bad_month> >::~clone_impl()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian9bad_monthEEEED2Ev[_ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian9bad_monthEEEED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)
`.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian9bad_monthEEEED2Ev' referenced in section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian9bad_monthEEEED1Ev[non-virtual thunk to boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::gregorian::bad_month> >::~clone_impl()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian9bad_monthEEEED2Ev[_ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian9bad_monthEEEED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)

Using boost::thread::condition_variable::wait yields

src/net/libnet.a(semaphore.cpp.o): In function `interruption_checker':
/usr/local/include/boost/thread/pthread/thread_data.hpp:96: undefined reference to `boost::detail::get_current_thread_data()'
src/net/libnet.a(semaphore.cpp.o): In function `boost::condition_variable::wait(boost::unique_lock<boost::mutex>&)':
/usr/local/include/boost/thread/pthread/condition_variable.hpp:57: undefined reference to `boost::this_thread::interruption_point()'
collect2: ld returned 1 exit status

I am using CMake, and it tells me Make issues the following command, which fails:

    /usr/bin/c++       CMakeFiles/rcon.dir/src/main.cpp.o  -o rcon -rdynamic -L/usr/local/lib /usr/local/lib/libboost_system.a /usr/local/lib/libboost_thread.a -lpthread src/net/libnet.a src/log/liblogging.a -Wl,-rpath,/usr/local/lib 

Whatever could be wrong? It is linking in libboost_thread.a?

Update

After moving libnet and liblogging (parts of my program, compiled into static libraries because I thought it was neat) before the boost libraries in the command line removes the undefined errors. However, now I get these when compiling with boost::condition_variable in my code, while the other error is unchanged:

`.text._ZN5boost16exception_detail19error_info_injectorINS_10lock_errorEED2Ev' referenced in section `.text._ZN5boost16exception_detail19error_info_injectorINS_10lock_errorEED1Ev[non-virtual thunk to boost::exception_detail::error_info_injector<boost::lock_error>::~error_info_injector()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail19error_info_injectorINS_10lock_errorEED2Ev[_ZN5boost16exception_detail19error_info_injectorINS_10lock_errorEED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)
`.text._ZN5boost16exception_detail19error_info_injectorISt13runtime_errorED2Ev' referenced in section `.text._ZN5boost16exception_detail19error_info_injectorISt13runtime_errorED1Ev[non-virtual thunk to boost::exception_detail::error_info_injector<std::runtime_error>::~error_info_injector()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail19error_info_injectorISt13runtime_errorED2Ev[_ZN5boost16exception_detail19error_info_injectorISt13runtime_errorED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)
`.text._ZN5boost16exception_detail19error_info_injectorINS_9gregorian16bad_day_of_monthEED2Ev' referenced in section `.text._ZN5boost16exception_detail19error_info_injectorINS_9gregorian16bad_day_of_monthEED1Ev[non-virtual thunk to boost::exception_detail::error_info_injector<boost::gregorian::bad_day_of_month>::~error_info_injector()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail19error_info_injectorINS_9gregorian16bad_day_of_monthEED2Ev[_ZN5boost16exception_detail19error_info_injectorINS_9gregorian16bad_day_of_monthEED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)
`.text._ZN5boost16exception_detail19error_info_injectorINS_21thread_resource_errorEED2Ev' referenced in section `.text._ZN5boost16exception_detail19error_info_injectorINS_21thread_resource_errorEED1Ev[non-virtual thunk to boost::exception_detail::error_info_injector<boost::thread_resource_error>::~error_info_injector()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail19error_info_injectorINS_21thread_resource_errorEED2Ev[_ZN5boost16exception_detail19error_info_injectorINS_21thread_resource_errorEED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)
`.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_15condition_errorEEEED2Ev' referenced in section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_15condition_errorEEEED1Ev[non-virtual thunk to boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::condition_error> >::~clone_impl()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_15condition_errorEEEED2Ev[_ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_15condition_errorEEEED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)
`.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_15condition_errorEEEED2Ev' referenced in section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_15condition_errorEEEED1Ev[non-virtual thunk to boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::condition_error> >::~clone_impl()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_15condition_errorEEEED2Ev[_ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_15condition_errorEEEED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)
`.text._ZN5boost16exception_detail19error_info_injectorINS_15condition_errorEED2Ev' referenced in section `.text._ZN5boost16exception_detail19error_info_injectorINS_15condition_errorEED1Ev[non-virtual thunk to boost::exception_detail::error_info_injector<boost::condition_error>::~error_info_injector()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail19error_info_injectorINS_15condition_errorEED2Ev[_ZN5boost16exception_detail19error_info_injectorINS_15condition_errorEED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)
`.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian8bad_yearEEEED2Ev' referenced in section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian8bad_yearEEEED1Ev[non-virtual thunk to boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::gregorian::bad_year> >::~clone_impl()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian8bad_yearEEEED2Ev[_ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian8bad_yearEEEED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)
`.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian8bad_yearEEEED2Ev' referenced in section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian8bad_yearEEEED1Ev[non-virtual thunk to boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::gregorian::bad_year> >::~clone_impl()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian8bad_yearEEEED2Ev[_ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian8bad_yearEEEED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)
`.text._ZN5boost16exception_detail19error_info_injectorINS_9gregorian8bad_yearEED2Ev' referenced in section `.text._ZN5boost16exception_detail19error_info_injectorINS_9gregorian8bad_yearEED1Ev[non-virtual thunk to boost::exception_detail::error_info_injector<boost::gregorian::bad_year>::~error_info_injector()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail19error_info_injectorINS_9gregorian8bad_yearEED2Ev[_ZN5boost16exception_detail19error_info_injectorINS_9gregorian8bad_yearEED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)
`.text._ZN5boost16exception_detail19error_info_injectorINS_9gregorian9bad_monthEED2Ev' referenced in section `.text._ZN5boost16exception_detail19error_info_injectorINS_9gregorian9bad_monthEED1Ev[non-virtual thunk to boost::exception_detail::error_info_injector<boost::gregorian::bad_month>::~error_info_injector()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail19error_info_injectorINS_9gregorian9bad_monthEED2Ev[_ZN5boost16exception_detail19error_info_injectorINS_9gregorian9bad_monthEED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)
`.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian16bad_day_of_monthEEEED2Ev' referenced in section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian16bad_day_of_monthEEEED1Ev[non-virtual thunk to boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::gregorian::bad_day_of_month> >::~clone_impl()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian16bad_day_of_monthEEEED2Ev[_ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian16bad_day_of_monthEEEED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)
`.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian16bad_day_of_monthEEEED2Ev' referenced in section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian16bad_day_of_monthEEEED1Ev[non-virtual thunk to boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::gregorian::bad_day_of_month> >::~clone_impl()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian16bad_day_of_monthEEEED2Ev[_ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian16bad_day_of_monthEEEED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)
`.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorISt13runtime_errorEEED2Ev' referenced in section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorISt13runtime_errorEEED1Ev[non-virtual thunk to boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<std::runtime_error> >::~clone_impl()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorISt13runtime_errorEEED2Ev[_ZN5boost16exception_detail10clone_implINS0_19error_info_injectorISt13runtime_errorEEED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)
`.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorISt13runtime_errorEEED2Ev' referenced in section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorISt13runtime_errorEEED1Ev[non-virtual thunk to boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<std::runtime_error> >::~clone_impl()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorISt13runtime_errorEEED2Ev[_ZN5boost16exception_detail10clone_implINS0_19error_info_injectorISt13runtime_errorEEED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)
`.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian9bad_monthEEEED2Ev' referenced in section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian9bad_monthEEEED1Ev[non-virtual thunk to boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::gregorian::bad_month> >::~clone_impl()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian9bad_monthEEEED2Ev[_ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian9bad_monthEEEED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)
`.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian9bad_monthEEEED2Ev' referenced in section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian9bad_monthEEEED1Ev[non-virtual thunk to boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::gregorian::bad_month> >::~clone_impl()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian9bad_monthEEEED2Ev[_ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_9gregorian9bad_monthEEEED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)
`.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_21thread_resource_errorEEEED2Ev' referenced in section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_21thread_resource_errorEEEED1Ev[non-virtual thunk to boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::thread_resource_error> >::~clone_impl()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_21thread_resource_errorEEEED2Ev[_ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_21thread_resource_errorEEEED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)
`.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_21thread_resource_errorEEEED2Ev' referenced in section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_21thread_resource_errorEEEED1Ev[non-virtual thunk to boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::thread_resource_error> >::~clone_impl()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_21thread_resource_errorEEEED2Ev[_ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_21thread_resource_errorEEEED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)
`.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_10lock_errorEEEED2Ev' referenced in section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_10lock_errorEEEED1Ev[non-virtual thunk to boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::lock_error> >::~clone_impl()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_10lock_errorEEEED2Ev[_ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_10lock_errorEEEED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)
`.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_10lock_errorEEEED2Ev' referenced in section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_10lock_errorEEEED1Ev[non-virtual thunk to boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::lock_error> >::~clone_impl()]' of /usr/local/lib/libboost_thread.a(thread.o): defined in discarded section `.text._ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_10lock_errorEEEED2Ev[_ZN5boost16exception_detail10clone_implINS0_19error_info_injectorINS_10lock_errorEEEED5Ev]' of /usr/local/lib/libboost_thread.a(thread.o)

回答1:

Now I'm a bit embarrassed. Apparently, something was wrong with my boost library. Probably, I compiled it with one version of gcc, after which I did an update all. This probably updated GCC with some form of minor incompatibility between the two versions. I could be completely wrong about that though.

I deleted all occurences of boost, and pulled boost from the Archlinux repositories instead, which currently is up to date with the official releases. Now it compiles as it should.

Silly me. :(

回答2:

Linkonce sections (and the newer notion of comdat groups) are a way for the compiler to emit template instantiations and out-of-line inlined functions without worrying about lots of duplicate copies in the linked output file. There may be a copy of, for instance, an instantiated template function in 2+ discrete object files, of which the linker will pick one and discard all the others. In order for that case to link properly, it's important that each copy defines and references exactly the same set of symbols.

Yet sometimes extra symbols are defined when different compilation options are used (e.g., -g, or when compiler options differ between object files, as is usually the case with shared libraries) or the set of symbols has changed from one version of gcc to the next (I suspect this is unlikely in your case - EDIT: well, colour me excited, looks like that might've been your folly. Glad your problem's solved). What may be happening here is that you have a reference from a non-linkonce section to a symbol that's defined in some (but not all) copies of a particular linkonce section. If the linker happens to discard the one with that symbol and keep the one without that symbol, you get this error.

I would propose you rearrange the link order of your object modules to try to get the linker to keep the section that defines the symbol(s) you need; in particular try to move the object files mentioned in the error message to the end or beginning of the object file list according to their dependencies (remember object files are linked left to right in their command line order).

回答3:

Here's my actual solution for it that does not involve changing your entire project's build flags:

Assuming you've got this function:

void foo() {/* ... */}

and your linker yields this error message:

`foo' referenced in section `...' of ...: defined in discarded section `.text' of ...

That means, somewhere in the compilation/linking process the function was removed.

You can enforce GCC's __attribute__((used)) function attribute to force the compiler not to garbage-collect the function in any way:

__attribute__((used)) void foo() {/* ... */}

When used often, I recommend defining a macro (which can also be used to be compatible with other compilers):

#define USED __attribute__((used))
//Usage example
USED void foo() {/* ... */}

Note that it is not advisable to add this attribute to all functions - it might increase your executable / library size because many unused functions will not be removed from the final compilate.

See the function attributes GCC docpage

回答4:

I suspect part or all of the problem is the order of libraries on the link line. Some linkers require you to list libraries from most dependent to least dependent, left to right, so they know which symbols to extract from each library. As a first start, move libnet before libboost_thread and see if things improve (or at least change).