link static library with shared library problem - c++

Question

I'm new to Linux, so sorry if this my question is really stupid.
I have shared cross-platform library project, which uses third party static library (Libtorrent).
Windows/Android/macOS - builds and works fine.
But I can't figure out how to build it in Linux (Ubuntu) with GCC.
I'm getting the following linker errors:
/usr/bin/ld: /home/user/Desktop/project/libtorrent-build/prebuilt/linux/lib/libtorrent-rasterbar.a(create_torrent.o): relocation R_X86_64_TPOFF32 against symbol `_ZN5boost4asio6detail15keyword_tss_ptrINS1_10call_stackINS1_15task_io_serviceENS1_27task_io_service_thread_infoEE7contextEE6value_E' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: /home/user/Desktop/project/libtorrent-build/prebuilt/linux/lib/libtorrent-rasterbar.a(disk_io_thread.o): relocation R_X86_64_TPOFF32 against symbol `_ZN5boost4asio6detail15keyword_tss_ptrINS1_10call_stackINS1_15task_io_serviceENS1_27task_io_service_thread_infoEE7contextEE6value_E' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: /home/user/Desktop/project/libtorrent-build/prebuilt/linux/lib/libtorrent-rasterbar.a(peer_connection.o): relocation R_X86_64_TPOFF32 against symbol `_ZN5boost4asio6detail15keyword_tss_ptrINS1_10call_stackINS1_15task_io_serviceENS1_27task_io_service_thread_infoEE7contextEE6value_E' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: /home/user/Desktop/project/libtorrent-build/prebuilt/linux/lib/libtorrent-rasterbar.a(session.o): relocation R_X86_64_TPOFF32 against symbol `_ZN5boost4asio6detail15keyword_tss_ptrINS1_10call_stackINS1_15task_io_serviceENS1_27task_io_service_thread_infoEE7contextEE6value_E' can not be used when making a shared object; recompile with -fPIC
I've tried rebuilding Boost and Libtorrent with -fPIC flag: nothing is changed.
Boost build script:
#!/bin/bash
set -e
BOOST_VERSION=1.63.0
BOOST_VERSION_UNDERSCORES=${BOOST_VERSION//./_}
echo "Boost version $BOOST_VERSION"
echo "Downloading..."
BOOST_ARCH_NAME=boost_${BOOST_VERSION_UNDERSCORES}.tar.gz
curl -O -L https://dl.bintray.com/boostorg/release/$BOOST_VERSION/source/$BOOST_ARCH_NAME
echo "Extracting..."
tar -xvzf $BOOST_ARCH_NAME
BOOST_FOLDER_NAME=boost_${BOOST_VERSION_UNDERSCORES}
cd $BOOST_FOLDER_NAME
chmod +x bootstrap.sh
./bootstrap.sh
chmod +x b2
./b2 headers
./b2 \
--layout=versioned \
--with-thread \
--with-date_time \
--with-filesystem \
--with-chrono \
--with-random \
toolset=gcc \
threading=multi \
link=static \
runtime-link=shared \
variant=release \
threadapi=pthread \
debug-symbols=off \
warnings=off \
warnings-as-errors=off \
architecture=x86 \
address-model=64 \
--stagedir=stage/linux \
cxxflags="-std=gnu++0x -fPIC" \
stage
echo "Copying prebuilt..."
mkdir -p ../prebuilt/linux/lib
cp -rf ./stage/linux/lib ../prebuilt/linux/
cd ../
echo "Cleaning up..."
rm $BOOST_ARCH_NAME
rm -rf $BOOST_FOLDER_NAME
echo "Done."
Libtorrent build script:
#!/bin/sh
set -e
MY_PWD=$PWD
LIBTORRENT_VERSION=1_1_8
LIBTORRENT_NAME=libtorrent-$LIBTORRENT_VERSION
export LIBTORRENT_FOLDER_NAME=libtorrent-$LIBTORRENT_NAME
curl -O -L "https://github.com/arvidn/libtorrent/archive/${LIBTORRENT_NAME}.tar.gz"
echo "Extracting..."
rm -rf ./$LIBTORRENT_FOLDER_NAME
tar xfz "${LIBTORRENT_NAME}.tar.gz"
echo "Building for linux..."
cd $LIBTORRENT_FOLDER_NAME
. ./autotool.sh
mkdir -p lib
if [ ! -d "./include/boost" ]; then
ln -s $PWD/../../boost-build/prebuilt/include/boost $PWD/include/boost
ln -s $PWD/../../boost-build/prebuilt/linux/lib/* $PWD/lib/
fi
if [ ! -d "./include/openssl" ]; then
ln -s $PWD/../../openssl-build/prebuilt/include/openssl $PWD/include/openssl
ln -s $PWD/../../openssl-build/prebuilt/linux/lib/* $PWD/lib/
fi
export CXX=g++
export CC=gcc
export CXXFLAGS="-std=gnu++0x -fPIC -fPIE"
export CPPFLAGS="-I"$PWD"/include"
./configure --enable-debug=no --with-boost-python=no --enable-logging=no \
--enable-tests=no --with-openssl=$PWD \
--with-boost=$PWD \
--enable-shared=no \
--enable-encryption
make -j4
mkdir -p ../prebuilt/linux/lib
cp -rf ./src/.libs/libtorrent-rasterbar.a ../prebuilt/linux/lib/
cd $MY_PWD
echo "cleaning up"
rm -rf $LIBTORRENT_FOLDER_NAME
rm -rf ${LIBTORRENT_NAME}.tar.gz
echo "done"
My shared lib itself is a Qt-based library. I build it using Qt Creator, providing all the required headers and libs in .pro file.

Answer 1

The problem was in Libtorrent build script. I removed -fPIE option and added
export CFLAGS="-fPIC"
Rebuilt and now it links without errors.