Почему CMake не помещает флаг `-L` в соответствующие места?

Question

Я пытаюсь создать общую библиотеку с cmake на linux. Часть кода, отвечающая за его настройку:

if (BUILD_SHARED)
    set(BUILD_SHARED_LIBS ON)
    set(CMAKE_VERBOSE_MAKEFILE ON)
    # shared library
    add_library(semsim SHARED "${SEMSIM_HEADERS}" "${SEMSIM_SOURCES}")
    #Note: not sure if this command does anything. It was supposed to be to link static libraries into my shared one
#    target_link_options(semsim PUBLIC -Wl,--whole-archive)
#
    message(STATUS "LIBBZ_INCLUDE_DIR ${LIBBZ_INCLUDE_DIR}")
    target_include_directories(semsim PUBLIC # make public so include dirs propagate into test binaries
            ${CMAKE_SOURCE_DIR}
            ${LIBXML2_INCLUDE_DIR}
            ${LIBSBML_DEPS_INCLUDE_DIR}
            ${LIBSBML_INCLUDE_DIR}
            ${ZLIB_INCLUDE_DIR}
            ${ZIPPER_INCLUDE_DIR}
            ${LIBCOMBINE_INCLUDE_DIR}
            ${BZ2_INCLUDE_DIR}

            ${REDLAND_INCLUDE_DIR}
            ${RASQAL_INCLUDE_DIR}
            ${RAPTOR2_INCLUDE_DIR}

            )

    target_link_libraries(semsim PUBLIC # make public so libraries propagate into test binaries
            ${LIBCOMBINE_STATIC_LIBRARY}
            ${ZIPPER_STATIC_LIBRARY}
            ${ZLIB_STATIC_LIBRARY}
            ${LIBSBML_STATIC_LIB}
            ${LIBBZ_STATIC_LIBRARY}
            ${REDLAND_LIBRARY}
            ${RASQAL_LIBRARY}
            ${RAPTOR2_LIBRARY}
            ${LIBXML2_STATIC_LIBRARY}
            dl
            ${BZ2_STATIC_LIBRARY}
            curl xslt
            )

endif ()

Это дает следующую команду для выполнения:

/usr/bin/c++ -fPIC -std=c++14 -g  -shared -Wl,-soname,libsemsim.so -o libsemsim.so CMakeFiles/semsim.dir/CurlGet.cpp.o CMakeFiles/semsim.dir/RDFNode.cpp.o CMakeFiles/semsim.dir/Subject.cpp.o CMakeFiles/semsim.dir/Predicate.cpp.o CMakeFiles/semsim.dir/Resource.cpp.o CMakeFiles/semsim.dir/Triple.cpp.o CMakeFiles/semsim.dir/SemsimUtils.cpp.o CMakeFiles/semsim.dir/MetaID.cpp.o CMakeFiles/semsim.dir/XmlAssistant.cpp.o CMakeFiles/semsim.dir/Reader.cpp.o CMakeFiles/semsim.dir/Editor.cpp.o CMakeFiles/semsim.dir/Writer.cpp.o CMakeFiles/semsim.dir/RDF.cpp.o CMakeFiles/semsim.dir/Participant.cpp.o CMakeFiles/semsim.dir/PhysicalEntity.cpp.o CMakeFiles/semsim.dir/PhysicalPhenomenon.cpp.o CMakeFiles/semsim.dir/PhysicalProcess.cpp.o CMakeFiles/semsim.dir/PhysicalPropertyResource.cpp.o CMakeFiles/semsim.dir/PhysicalForce.cpp.o CMakeFiles/semsim.dir/Query.cpp.o CMakeFiles/semsim.dir/SemsimCombineArchive.cpp.o CMakeFiles/semsim.dir/Triples.cpp.o ../../third_party/libCombine-0.2.3/INSTALL/lib/libCombine-static.a ../../third_party/zipper/INSTALL/lib/libZipper-static.a ../../third_party/zlib-1.2.11/INSTALL/lib/libz.a /usr/local/lib/libxml2.a -ldl ../../third_party/libsbml-dependencies/INSTALL/lib/libbz2.a -lcurl -lxslt 

Если я позволю CMake попытаться построить с этой командой, я получу следующая ошибка:

/usr/bin/ld: /usr/local/lib/libxml2.a(uri.o): relocation R_X86_64_PC32 against symbol `xmlFree' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: final link failed: Bad value

Однако я заметил, что в команде, созданной CMake, отсутствуют флаги -L. Поэтому я изменил команду на:

/usr/bin/c++ -fPIC -std=c++14 -g -shared -o libsemsim.so CMakeFiles/semsim.dir/CurlGet.cpp.o CMakeFiles/semsim.dir/RDFNode.cpp.o CMakeFiles/semsim.dir/Subject.cpp.o CMakeFiles/semsim.dir/Predicate.cpp.o CMakeFiles/semsim.dir/Resource.cpp.o CMakeFiles/semsim.dir/Triple.cpp.o CMakeFiles/semsim.dir/SemsimUtils.cpp.o CMakeFiles/semsim.dir/MetaID.cpp.o CMakeFiles/semsim.dir/XmlAssistant.cpp.o CMakeFiles/semsim.dir/Reader.cpp.o CMakeFiles/semsim.dir/Editor.cpp.o CMakeFiles/semsim.dir/Writer.cpp.o CMakeFiles/semsim.dir/RDF.cpp.o CMakeFiles/semsim.dir/Participant.cpp.o CMakeFiles/semsim.dir/PhysicalEntity.cpp.o CMakeFiles/semsim.dir/PhysicalPhenomenon.cpp.o CMakeFiles/semsim.dir/PhysicalProcess.cpp.o CMakeFiles/semsim.dir/PhysicalPropertyResource.cpp.o CMakeFiles/semsim.dir/PhysicalForce.cpp.o CMakeFiles/semsim.dir/Query.cpp.o CMakeFiles/semsim.dir/SemsimCombineArchive.cpp.o CMakeFiles/semsim.dir/Triples.cpp.o -L ../../third_party/libCombine-0.2.3/INSTALL/lib/libCombine-static.a -L ../../third_party/
zipper/INSTALL/lib/libZipper-static.a -L ../../third_party/zlib-1.2.11/INSTALL/lib/libz.a -L /usr/local/lib/libxml2.a -l
dl -L ../../third_party/libsbml-dependencies/INSTALL/lib/libbz2.a -lcurl -lxslt

запустил ее в оболочке, и она сработала. Может ли кто-нибудь предложить, почему CMake не использует флаг -L в соответствующих местах?