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I have installed boost on Fedora 20 via yum and am trying some simple examples. However I have trouble to compile the first example from the logging tutorial.
Compiling with g++ -c boosttest.cc works fine, but I get lot's of errors when I try to link it with
g++ boosttest.o -o boosttest -lboost_log -lpthread the full error-log:
boosttest.o: In function `main': boosttest.cc:(.text+0x44): undefined reference to `boost::log::v2s_mt_posix::trivial::logger::get()' boosttest.cc:(.text+0x9a): undefined reference to `boost::log::v2s_mt_posix::trivial::logger::get()' boosttest.cc:(.text+0x167): undefined reference to `boost::log::v2s_mt_posix::trivial::logger::get()' boosttest.cc:(.text+0x1bd): undefined reference to `boost::log::v2s_mt_posix::trivial::logger::get()' boosttest.cc:(.text+0x28a): undefined reference to `boost::log::v2s_mt_posix::trivial::logger::get()' boosttest.o:boosttest.cc:(.text+0x2e0): more undefined references to `boost::log::v2s_mt_posix::trivial::logger::get()' follow boosttest.o: In function `boost::log::v2s_mt_posix::record::reset()': boosttest.cc:(.text._ZN5boost3log12v2s_mt_posix6record5resetEv[_ZN5boost3log12v2s_mt_posix6record5resetEv]+0x18): undefined reference to `boost::log::v2s_mt_posix::record_view::public_data::destroy(boost::log::v2s_mt_posix::record_view::public_data const*)' boosttest.o: In function `boost::log::v2s_mt_posix::record boost::log::v2s_mt_posix::sources::basic_composite_logger<char, boost::log::v2s_mt_posix::sources::severity_logger_mt<boost::log::v2s_mt_posix::trivial::severity_level>, boost::log::v2s_mt_posix::sources::multi_thread_model<boost::log::v2s_mt_posix::aux::light_rw_mutex>, boost::log::v2s_mt_posix::sources::features<boost::log::v2s_mt_posix::sources::severity<boost::log::v2s_mt_posix::trivial::severity_level>, void, void, void, void, void, void, void, void, void> >::open_record<boost::parameter::aux::tagged_argument<boost::log::v2s_mt_posix::keywords::tag::severity, boost::log::v2s_mt_posix::trivial::severity_level const> >(boost::parameter::aux::tagged_argument<boost::log::v2s_mt_posix::keywords::tag::severity, boost::log::v2s_mt_posix::trivial::severity_level const> const&)': boosttest.cc:(.text._ZN5boost3log12v2s_mt_posix7sources22basic_composite_loggerIcNS2_18severity_logger_mtINS1_7trivial14severity_levelEEENS2_18multi_thread_modelINS1_3aux14light_rw_mutexEEENS2_8featuresINS2_8severityIS6_EEvvvvvvvvvEEE11open_recordINS_9parameter3aux15tagged_argumentINS1_8keywords3tag8severityEKS6_EEEENS1_6recordERKT_[_ZN5boost3log12v2s_mt_posix7sources22basic_composite_loggerIcNS2_18severity_logger_mtINS1_7trivial14severity_levelEEENS2_18multi_thread_modelINS1_3aux14light_rw_mutexEEENS2_8featuresINS2_8severityIS6_EEvvvvvvvvvEEE11open_recordINS_9parameter3aux15tagged_argumentINS1_8keywords3tag8severityEKS6_EEEENS1_6recordERKT_]+0x1e): undefined reference to `boost::log::v2s_mt_posix::core::get_logging_enabled() const' boosttest.o: In function `boost::log::v2s_mt_posix::aux::record_pump<boost::log::v2s_mt_posix::sources::severity_logger_mt<boost::log::v2s_mt_posix::trivial::severity_level> >::~record_pump()': boosttest.cc:(.text._ZN5boost3log12v2s_mt_posix3aux11record_pumpINS1_7sources18severity_logger_mtINS1_7trivial14severity_levelEEEED2Ev[_ZN5boost3log12v2s_mt_posix3aux11record_pumpINS1_7sources18severity_logger_mtINS1_7trivial14severity_levelEEEED5Ev]+0x2c): undefined reference to `boost::log::v2s_mt_posix::aux::unhandled_exception_count()' boosttest.o: In function `boost::log::v2s_mt_posix::aux::record_pump<boost::log::v2s_mt_posix::sources::severity_logger_mt<boost::log::v2s_mt_posix::trivial::severity_level> >::record_pump(boost::log::v2s_mt_posix::sources::severity_logger_mt<boost::log::v2s_mt_posix::trivial::severity_level>&, boost::log::v2s_mt_posix::record&)': boosttest.cc:(.text._ZN5boost3log12v2s_mt_posix3aux11record_pumpINS1_7sources18severity_logger_mtINS1_7trivial14severity_levelEEEEC2ERS8_RNS1_6recordE[_ZN5boost3log12v2s_mt_posix3aux11record_pumpINS1_7sources18severity_logger_mtINS1_7trivial14severity_levelEEEEC5ERS8_RNS1_6recordE]+0x1d): undefined reference to `boost::log::v2s_mt_posix::aux::stream_provider<char>::allocate_compound(boost::log::v2s_mt_posix::record&)' boosttest.cc:(.text._ZN5boost3log12v2s_mt_posix3aux11record_pumpINS1_7sources18severity_logger_mtINS1_7trivial14severity_levelEEEEC2ERS8_RNS1_6recordE[_ZN5boost3log12v2s_mt_posix3aux11record_pumpINS1_7sources18severity_logger_mtINS1_7trivial14severity_levelEEEEC5ERS8_RNS1_6recordE]+0x28): undefined reference to `boost::log::v2s_mt_posix::aux::unhandled_exception_count()' boosttest.o: In function `boost::log::v2s_mt_posix::aux::record_pump<boost::log::v2s_mt_posix::sources::severity_logger_mt<boost::log::v2s_mt_posix::trivial::severity_level> >::auto_release::~auto_release()': boosttest.cc:(.text._ZN5boost3log12v2s_mt_posix3aux11record_pumpINS1_7sources18severity_logger_mtINS1_7trivial14severity_levelEEEE12auto_releaseD2Ev[_ZN5boost3log12v2s_mt_posix3aux11record_pumpINS1_7sources18severity_logger_mtINS1_7trivial14severity_levelEEEE12auto_releaseD5Ev]+0xf): undefined reference to `boost::log::v2s_mt_posix::aux::stream_provider<char>::release_compound(boost::log::v2s_mt_posix::aux::stream_provider<char>::stream_compound*)' boosttest.o: In function `boost::log::v2s_mt_posix::sources::aux::severity_level<boost::log::v2s_mt_posix::trivial::severity_level>::set_value(boost::log::v2s_mt_posix::trivial::severity_level)': boosttest.cc:(.text._ZN5boost3log12v2s_mt_posix7sources3aux14severity_levelINS1_7trivial14severity_levelEE9set_valueES6_[_ZN5boost3log12v2s_mt_posix7sources3aux14severity_levelINS1_7trivial14severity_levelEE9set_valueES6_]+0x7): undefined reference to `boost::log::v2s_mt_posix::sources::aux::get_severity_level()' boosttest.o: In function `boost::log::v2s_mt_posix::record boost::log::v2s_mt_posix::sources::basic_logger<char, boost::log::v2s_mt_posix::sources::severity_logger_mt<boost::log::v2s_mt_posix::trivial::severity_level>, boost::log::v2s_mt_posix::sources::multi_thread_model<boost::log::v2s_mt_posix::aux::light_rw_mutex> >::open_record_unlocked<boost::parameter::aux::tagged_argument<boost::log::v2s_mt_posix::keywords::tag::severity, boost::log::v2s_mt_posix::trivial::severity_level const> >(boost::parameter::aux::tagged_argument<boost::log::v2s_mt_posix::keywords::tag::severity, boost::log::v2s_mt_posix::trivial::severity_level const> const&)': boosttest.cc:(.text._ZN5boost3log12v2s_mt_posix7sources12basic_loggerIcNS2_18severity_logger_mtINS1_7trivial14severity_levelEEENS2_18multi_thread_modelINS1_3aux14light_rw_mutexEEEE20open_record_unlockedINS_9parameter3aux15tagged_argumentINS1_8keywords3tag8severityEKS6_EEEENS1_6recordERKT_[_ZN5boost3log12v2s_mt_posix7sources12basic_loggerIcNS2_18severity_logger_mtINS1_7trivial14severity_levelEEENS2_18multi_thread_modelINS1_3aux14light_rw_mutexEEEE20open_record_unlockedINS_9parameter3aux15tagged_argumentINS1_8keywords3tag8severityEKS6_EEEENS1_6recordERKT_]+0x2a): undefined reference to `boost::log::v2s_mt_posix::core::open_record(boost::log::v2s_mt_posix::attribute_set const&)' boosttest.o: In function `boost::log::v2s_mt_posix::sources::basic_logger<char, boost::log::v2s_mt_posix::sources::severity_logger_mt<boost::log::v2s_mt_posix::trivial::severity_level>, boost::log::v2s_mt_posix::sources::multi_thread_model<boost::log::v2s_mt_posix::aux::light_rw_mutex> >::push_record_unlocked(boost::rv<boost::log::v2s_mt_posix::record>&)': boosttest.cc:(.text._ZN5boost3log12v2s_mt_posix7sources12basic_loggerIcNS2_18severity_logger_mtINS1_7trivial14severity_levelEEENS2_18multi_thread_modelINS1_3aux14light_rw_mutexEEEE20push_record_unlockedERNS_2rvINS1_6recordEEE[_ZN5boost3log12v2s_mt_posix7sources12basic_loggerIcNS2_18severity_logger_mtINS1_7trivial14severity_levelEEENS2_18multi_thread_modelINS1_3aux14light_rw_mutexEEEE20push_record_unlockedERNS_2rvINS1_6recordEEE]+0x36): undefined reference to `boost::log::v2s_mt_posix::core::push_record_move(boost::log::v2s_mt_posix::record&)' collect2: error: ld returned 1 exit status What am I missing? What am I doing wrong?
EDIT 1: The order of -lboost_log -lpthread makes no difference in the output. There is also a very similar question, but the solution does not work for me. The following also fails with the same errors:
g++ -DBOOST_LOG_DYN_LINK boosttest.o -o boosttest -lboost_log -lpthread 
520
You can fix the errors by including the source code file that contains the definitions as part of the compilation. Alternatively, you can pass . obj files or . lib files that contain the definitions to the linker.
So when we try to assign it a value in the main function, the linker doesn't find the symbol and may result in an “unresolved external symbol” or “undefined reference”. The way to fix this error is to explicitly scope the variable using '::' outside the main before using it.
These are the linking errors caused when the compiler tries to link your application with the appropriate libraries that define all the symbols. Just providing the path to these libraries (lib files) is not enough. You will need to add them manually to your Visual Studio project in order to resolve all the symbols.
Unresolved external references occur when the symbol for a function or global variable is referenced in a program, but none of the object files or libraries specified in the link step contain a definition for that symbol.
Just add a line
#define BOOST_LOG_DYN_LINK 1 as the first line of boosttest.cc.
Alternatively, you can add -DBOOST_LOG_DYN_LINK to you compilation step (not the linking step, as you posted in the question):
g++ -std=c++11 -Wall -pedantic -g -O0 -DBOOST_LOG_DYN_LINK -c boosttest.cc g++ boosttest.o -lpthread -lboost_log -o boosttest I had the same annoying problem. The macro should be defined while compiling, not linking:
g++ -std=c++11 -DBOOST_LOG_DYN_LINK -c boosttest.cc In the linker command, make sure the order is as follows:
g++ boosttest.o -lboost_log -lpthread -o boosttest If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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