Summary: On a CentOS 7 x64 system, I've build the latest Boost 1.61.0 with -fPIC enabled. I'm trying to link libboost_log.a to the dynamic library I'm building so that the user of my library doesn't have to have Boost installed. That succeeded using the stock GCC 4.8.5 shipped with CentOS 7, but failed when I'm using GCC 5.2.1 from devtoolset-4.
Error:
/opt/rh/devtoolset-4/root/usr/libexec/gcc/x86_64-redhat-linux/5.2.1/ld: /opt/boost/lib/libboost_log.a(attribute_name.o): relocation R_X86_64_32 against `_ZZN5boost3log12v2s_mt_posix3aux14lazy_singletonINS1_14attribute_name10repositoryENS_10shared_ptrIS5_EEE3getEvE29_boost_log_once_block_flag_43' can not be used when making a shared object; recompile with -fPIC /opt/boost/lib/libboost_log.a: error adding symbols: Bad value collect2: error: ld retued 1 exit status
How I built Boost: ./b2 -j6 -q -d+2 cxxflags=-fPIC cflags=-fPIC variant=release Boost uses -O3 by default. My program thus used -O3 as well.
Command for building my library: /opt/rh/devtoolset-4/root/usr/bin/c++ -fPIC -O3 -g -DNDEBUG -shared -Wl,-soname,libfoobar.so.0 -o libfoobar.so.0.5 foobar.cc.o -L/opt/boost/lib /opt/boost/lib/libboost_filesystem.a /opt/boost/lib/libboost_log.a /opt/boost/lib/libboost_program_options.a -lpthread -Wl,-rpath,/opt/boost/lib
Proof that libboost_log.a is built with fPIC:
$ objdump -r /opt/boost/lib/libboost_log.a | grep _ZZN5boost3log12v2s_mt_posix3aux14lazy_singletonINS1_14attribute_name10repositoryENS_10shared_ptrIS5_EEE3getEvE29_boost_log_once_block_flag_43 0000000000000002 R_X86_64_32 _ZZN5boost3log12v2s_mt_posix3aux14lazy_singletonINS1_14attribute_name10repositoryENS_10shared_ptrIS5_EEE3getEvE29_boost_log_once_block_flag_43 0000000000000011 R_X86_64_32S _ZZN5boost3log12v2s_mt_posix3aux14lazy_singletonINS1_14attribute_name10repositoryENS_10shared_ptrIS5_EEE3getEvE29_boost_log_once_block_flag_43 00000000000001a3 R_X86_64_32 _ZZN5boost3log12v2s_mt_posix3aux14lazy_singletonINS1_14attribute_name10repositoryENS_10shared_ptrIS5_EEE3getEvE29_boost_log_once_block_flag_43 00000000000001be R_X86_64_32S _ZZN5boost3log12v2s_mt_posix3aux14lazy_singletonINS1_14attribute_name10repositoryENS_10shared_ptrIS5_EEE3getEvE29_boost_log_once_block_flag_43 000000000000001c R_X86_64_32S _ZZN5boost3log12v2s_mt_posix3aux14lazy_singletonINS1_14attribute_name10repositoryENS_10shared_ptrIS5_EEE3getEvE29_boost_log_once_block_flag_43 0000000000000021 R_X86_64_32 _ZZN5boost3log12v2s_mt_posix3aux14lazy_singletonINS1_14attribute_name10repositoryENS_10shared_ptrIS5_EEE3getEvE29_boost_log_once_block_flag_43
Thoughts: As you can see libboost_filesystem.a seems linked fine, just libboost_log.a caot be linked in. What things can I check now? Any hints are welcome. Thanks!