attribute appertains to a friend declaration that is not a definition

[BenniProbst]

====================[ Build | Kodierungstheorie | Debug ]======================= /usr/local/bin/cmake --build /home/benjamin-elias/CLionProjects/Kodierungstheorie/cmake-build-debug --target Kodierungstheorie -- -j 6 Scanning dependencies of target Kodierungstheorie [ 16%] Building CXX object CMakeFiles/Kodierungstheorie.dir/main.cpp.o In Datei, eingebunden von /home/benjamin-elias/Downloads/boost_1_76_0/boost/thread/thread_only.hpp:22, von /home/benjamin-elias/Downloads/boost_1_76_0/boost/thread/thread.hpp:12, von /home/benjamin-elias/Downloads/boost_1_76_0/boost/thread.hpp:13, von /home/benjamin-elias/CLionProjects/Kodierungstheorie/main.cpp:2: /home/benjamin-elias/Downloads/boost_1_76_0/boost/thread/detail/thread.hpp:641:37: Fehler: attribute appertains to a friend declaration that is not a definition 641 | friend id BOOST_THREAD_DECL this_thread::get_id() BOOST_NOEXCEPT; | ^~~ make[3]: [CMakeFiles/Kodierungstheorie.dir/build.make:72: CMakeFiles/Kodierungstheorie.dir/main.cpp.o] Fehler 1 make[2]: [CMakeFiles/Makefile2:85: CMakeFiles/Kodierungstheorie.dir/all] Fehler 2 make[1]: [CMakeFiles/Makefile2:92: CMakeFiles/Kodierungstheorie.dir/rule] Fehler 2 make: [Makefile:124: Kodierungstheorie] Fehler 2