Hello list! After switching from g++-4.4 to g++-4.5, my code stopped compiling and began reporting errors on linking. Here's an example (as is, could not reproduce the error on purpose in small example) - parts of the application are compiled as static libraries and then linked together with main.cpp.o and shared libraries: <...> /usr/local/bin/c++ -Wall -g CMakeFiles/test_backend.dir/main.cpp.o -o test_backend -rdynamic liblibtest_backend.a /usr/local/lib/liblog4cplus.so /usr/local/lib/libpion-net.so /usr/local/lib/libpion-common.so -lboost_regex-mt -lpthread -lxml2 -lboost_program_options-mt -lboost_filesystem-mt -lboost_thread-mt /usr/local/lib/libboost_xml.so -lboost_system-mt ../Utils/liblibsearch_utils.a /usr/local/lib/libcurlpp.so -lxslt ../SearchData/liblibsearch_data.a -lboost_filesystem-mt -Wl,-rpath,/usr/local/lib: The reported error is: /usr/bin/ld: liblibtest_backend.a(DocumentGeneratorService.cpp.o): undefined reference to symbol 'SSL_write@@OPENSSL_0.9.8' /usr/bin/ld: note: 'SSL_write@@OPENSSL_0.9.8' is defined in DSO //lib64/libssl.so.0.9.8 so try adding it to the linker command line //lib64/libssl.so.0.9.8: could not read symbols: Invalid operation OK, adding -lssl to the linking list fixes that, but another similar error occurs - looks like I'll have to add all dependent shared libraries to the list to fix that, so there should be a better way. Adding --verbose option to compilcation, I get the following output: <...> COLLECT_GCC_OPTIONS='-v' '-Wall' '-g' '-o' 'test_backend' '-rdynamic' '-shared-libgcc' '-mtune=generic' '-march=x86-64' /usr/lib/gcc/x86_64-linux-gnu/4.5.1/collect2 --build-id --no-add-needed --eh-frame-hdr -m elf_x86_64 --hash-style=gnu -export-dynamic -dynamic-linker /lib64/ld-linux-x86-64.so.2 -z relro -o test_backend /usr/lib/gcc/x86_64-linux-gnu/4.5.1/../../../../lib64/crt1.o /usr/lib/gcc/x86_64-linux-gnu/4.5.1/../../../../lib64/crti.o /usr/lib/gcc/x86_64-linux-gnu/4.5.1/crtbegin.o -L/usr/lib/gcc/x86_64-linux-gnu/4.5.1 -L/usr/lib/gcc/x86_64-linux-gnu/4.5.1/../../../../lib64 -L/lib/../lib64 -L/usr/lib/../lib64 -L/usr/lib/gcc/x86_64-linux-gnu/4.5.1/../../.. -L/usr/lib/x86_64-linux-gnu CMakeFiles/test_backend.dir/main.cpp.o liblibtest_backend.a /usr/local/lib/liblog4cplus.so /usr/local/lib/libpion-net.so /usr/local/lib/libpion-common.so -lboost_regex-mt -lpthread -lxml2 -lboost_program_options-mt -lboost_filesystem-mt -lboost_thread-mt /usr/local/lib/libboost_xml.so -lboost_system-mt ../Utils/liblibsearch_utils.a /usr/local/lib/libcurlpp.so -lxslt ../SearchData/liblibsearch_data.a -lboost_filesystem-mt -rpath /usr/local/lib: -lstdc++ -lm -lgcc_s -lgcc -lc -lgcc_s -lgcc /usr/lib/gcc/x86_64-linux-gnu/4.5.1/crtend.o /usr/lib/gcc/x86_64-linux-gnu/4.5.1/../../../../lib64/crtn.o OK, --no-add-needed is the offending option and removing it fixes the linking. But why did it get there? While I can disable it via -Wl,--add-needed, I want to know the root cause for this error and fix it. My system is Linux 2.6.35 (Ubuntu Maverick), gcc (Ubuntu/Linaro 4.5.1-7ubuntu2) 4.5.1. -- Dmitry Risenberg
