Linking G729 library (Library exists and symbols too)

Linking G729 library (Library exists and symbols too) - c++

Iam currently struggeling with linking just a simple library.
I compiled and installed successfully the G729 implementation from here Belledonne G729 like this:
cmake . -DCMAKE_INSTALL_PREFIX=/usr
make
make install
When i check the if the symbols exist they exsist:
nm /usr/lib64/libbcg729.so | less
....
0000000000001fb8 T _init
000000000000de40 T initBcg729CNGChannel
00000000000046dd T initBcg729DecoderChannel
000000000000f5c6 T initBcg729DTXChannel
0000000000005353 T initBcg729EncoderChannel
0000000000010107 T initBcg729VADChannel
....
But when i try to compile this simple main.cpp:
#include <bcg729/decoder.h> // for bcg729DecoderChannelContextStruct
int main()
{
bcg729DecoderChannelContextStruct* decoderChannelContext = initBcg729DecoderChannel();
return 0;
}
I get this as result:
c++ -v main.o -o main -lbcg729
Using built-in specs.
COLLECT_GCC=c++
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/4.8.5/lto-wrapper
Target: x86_64-redhat-linux
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-bootstrap --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-linker-build-id --with-linker-hash-style=gnu --enable-languages=c,c++,objc,obj-c++,java,fortran,ada,go,lto --enable-plugin --enable-initfini-array --disable-libgcj --with-isl=/builddir/build/BUILD/gcc-4.8.5-20150702/obj-x86_64-redhat-linux/isl-install --with-cloog=/builddir/build/BUILD/gcc-4.8.5-20150702/obj-x86_64-redhat-linux/cloog-install --enable-gnu-indirect-function --with-tune=generic --with-arch_32=x86-64 --build=x86_64-redhat-linux
Thread model: posix
gcc version 4.8.5 20150623 (Red Hat 4.8.5-16) (GCC)
COMPILER_PATH=/usr/libexec/gcc/x86_64-redhat-linux/4.8.5/:/usr/libexec/gcc/x86_64-redhat-linux/4.8.5/:/usr/libexec/gcc/x86_64-redhat-linux/:/usr/lib/gcc/x86_64-redhat-linux/4.8.5/:/usr/lib/gcc/x86_64-redhat-linux/
LIBRARY_PATH=/usr/lib/gcc/x86_64-redhat-linux/4.8.5/:/usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../../lib64/:/lib/../lib64/:/usr/lib/../lib64/:/usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-v' '-o' 'main' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
/usr/libexec/gcc/x86_64-redhat-linux/4.8.5/collect2 --build-id --no-add-needed --eh-frame-hdr --hash-style=gnu -m elf_x86_64 -dynamic-linker /lib64/ld-linux-x86-64.so.2 -o main /usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../../lib64/crt1.o /usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../../lib64/crti.o /usr/lib/gcc/x86_64-redhat-linux/4.8.5/crtbegin.o -L/usr/lib/gcc/x86_64-redhat-linux/4.8.5 -L/usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../../lib64 -L/lib/../lib64 -L/usr/lib/../lib64 -L/usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../.. main.o -lbcg729 -lstdc++ -lm -lgcc_s -lgcc -lc -lgcc_s -lgcc /usr/lib/gcc/x86_64-redhat-linux/4.8.5/crtend.o /usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../../lib64/crtn.o
main.o: In function `main':
/opt/cppplayground/main.cpp:39: undefined reference to `initBcg729DecoderChannel()'
collect2: error: ld returned 1 exit status
I dont get where the issue is here, since if the library wouldnt be found, the linker would complain it does not exist. But in this case the library exists and the function i want to use does also exists.
Woulbe be nice if anyone could help ;)
Thanks in advance!

Found it ....
Since it's a C-Library i forgot to add the 'extern "C" {}' around the includes.

Related

Why does g++ require libstdc++.a? Why is it not the default?

I had this problem, and the solution was to explicitly pass libstdc++.a to g++, like the following:
/usr/local/gcc-10.2.0/bin/g++ -I/usr/local/gcc-10.2.0/include -L/usr/local/gcc-10.2.0/lib64 -Wl,-rpath,/usr/local/gcc-10.2.0/lib64 b.cpp /usr/local/gcc-10.2.0/lib64/libstdc++.a
My question: Why do I need to explicitly pass libstdc++.a? How can I make it automatic so that libstdc++.a is used by default? How can I find the answer to the two questions?
The test code:
#include <sstream>
using namespace std;
int
main ()
{
ostringstream oss;
unsigned long k = 5;
oss << k;
}
Compiled with the following parameters:
/usr/local/gcc-10.2.0/bin/g++ -I/usr/local/gcc-10.2.0/include -L/usr/local/gcc-10.2.0/lib64 -Wl,-rpath,/usr/local/gcc-10.2.0/lib64 -lstdc++ b.cpp
Got the following output:
/tmp/cclRSXGV.o: In function main': b.cpp:(.text+0x35): undefined reference to std::ostream::operator<<(unsigned long)'
collect2: error: ld returned 1 exit status
Using GNU gcc 10.2.0, installed with the following:
../gcc-10.2.0/configure --prefix=/usr/local/gcc-10.2.0 --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=bugzilla.redhat.com/bugzilla --enable-bootstrap --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-languages=c,c++ --disable-dssi --enable-libgcj-multifile --with-ppl --with-cloog --with-tune=generic --with-arch_32=i686 --build=x86_64-redhat-linux && make install-strip
Already had GNU gcc 4.4.7 installed by default at /usr, and GNU gcc 9.2.0 at /usr/local/gcc-9.2.0
Running /usr/local/gcc-10.2.0/bin/g++ -v b.cpp produces the following:
Using built-in specs.
COLLECT_GCC=/usr/local/gcc-10.2.0/bin/g++
COLLECT_LTO_WRAPPER=/usr/local/gcc-10.2.0/libexec/gcc/x86_64-redhat-linux/10.2.0/lto-wrapper
Target: x86_64-redhat-linux
Configured with: ../gcc-10.2.0/configure --prefix=/usr/local/gcc-10.2.0 --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-bootstrap --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-languages=c,c++ --disable-dssi --enable-libgcj-multifile --with-ppl --with-cloog --with-tune=generic --with-arch_32=i686 --build=x86_64-redhat-linux
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 10.2.0 (GCC)
COLLECT_GCC_OPTIONS='-v' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
/usr/local/gcc-10.2.0/libexec/gcc/x86_64-redhat-linux/10.2.0/cc1plus -quiet -v -D_GNU_SOURCE b.cpp -quiet -dumpbase b.cpp -mtune=generic -march=x86-64 -auxbase b -version -o /tmp/ccJiMH6j.s
GNU C++14 (GCC) version 10.2.0 (x86_64-redhat-linux)
compiled by GNU C version 10.2.0, GMP version 6.1.0, MPFR version 3.1.4, MPC version 1.0.3, isl version isl-0.18-GMP
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
ignoring nonexistent directory "/usr/local/gcc-10.2.0/lib/gcc/x86_64-redhat-linux/10.2.0/../../../../x86_64-redhat-linux/include"
#include "..." search starts here:
#include <...> search starts here:
/usr/local/gcc-10.2.0/lib/gcc/x86_64-redhat-linux/10.2.0/../../../../include/c++/10.2.0
/usr/local/gcc-10.2.0/lib/gcc/x86_64-redhat-linux/10.2.0/../../../../include/c++/10.2.0/x86_64-redhat-linux
/usr/local/gcc-10.2.0/lib/gcc/x86_64-redhat-linux/10.2.0/../../../../include/c++/10.2.0/backward
/usr/local/gcc-10.2.0/lib/gcc/x86_64-redhat-linux/10.2.0/include
/usr/local/include
/usr/local/gcc-10.2.0/include
/usr/local/gcc-10.2.0/lib/gcc/x86_64-redhat-linux/10.2.0/include-fixed
/usr/include
End of search list.
GNU C++14 (GCC) version 10.2.0 (x86_64-redhat-linux)
compiled by GNU C version 10.2.0, GMP version 6.1.0, MPFR version 3.1.4, MPC version 1.0.3, isl version isl-0.18-GMP
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 410dfe626634fcd13dbcedee05209c5e
COLLECT_GCC_OPTIONS='-v' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
as -v --64 -o /tmp/ccUyoUr2.o /tmp/ccJiMH6j.s
GNU assembler version 2.35 (x86_64-pc-linux-gnu) using BFD version (GNU Binutils) 2.35
COMPILER_PATH=/usr/local/gcc-10.2.0/libexec/gcc/x86_64-redhat-linux/10.2.0/:/usr/local/gcc-10.2.0/libexec/gcc/x86_64-redhat-linux/10.2.0/:/usr/local/gcc-10.2.0/libexec/gcc/x86_64-redhat-linux/:/usr/local/gcc-10.2.0/lib/gcc/x86_64-redhat-linux/10.2.0/:/usr/local/gcc-10.2.0/lib/gcc/x86_64-redhat-linux/
LIBRARY_PATH=/usr/local/gcc-10.2.0/lib/gcc/x86_64-redhat-linux/10.2.0/:/usr/local/gcc-10.2.0/lib/gcc/x86_64-redhat-linux/10.2.0/../../../../lib64/:/lib/../lib64/:/usr/lib/../lib64/:/usr/local/gcc-10.2.0/lib/gcc/x86_64-redhat-linux/10.2.0/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-v' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
/usr/local/gcc-10.2.0/libexec/gcc/x86_64-redhat-linux/10.2.0/collect2 -plugin /usr/local/gcc-10.2.0/libexec/gcc/x86_64-redhat-linux/10.2.0/liblto_plugin.so -plugin-opt=/usr/local/gcc-10.2.0/libexec/gcc/x86_64-redhat-linux/10.2.0/lto-wrapper -plugin-opt=-fresolution=/tmp/ccfGN6NK.res -plugin-opt=-pass-through=-lgcc_s -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lc -plugin-opt=-pass-through=-lgcc_s -plugin-opt=-pass-through=-lgcc --eh-frame-hdr -m elf_x86_64 -dynamic-linker /lib64/ld-linux-x86-64.so.2 /usr/lib/../lib64/crt1.o /usr/lib/../lib64/crti.o /usr/local/gcc-10.2.0/lib/gcc/x86_64-redhat-linux/10.2.0/crtbegin.o -L/usr/local/gcc-10.2.0/lib/gcc/x86_64-redhat-linux/10.2.0 -L/usr/local/gcc-10.2.0/lib/gcc/x86_64-redhat-linux/10.2.0/../../../../lib64 -L/lib/../lib64 -L/usr/lib/../lib64 -L/usr/local/gcc-10.2.0/lib/gcc/x86_64-redhat-linux/10.2.0/../../.. /tmp/ccUyoUr2.o -lstdc++ -lm -lgcc_s -lgcc -lc -lgcc_s -lgcc /usr/local/gcc-10.2.0/lib/gcc/x86_64-redhat-linux/10.2.0/crtend.o /usr/lib/../lib64/crtn.o
/usr/local/bin/ld: /tmp/ccUyoUr2.o: in function `main':
b.cpp:(.text+0xc9): undefined reference to `std::cout'
/usr/local/bin/ld: b.cpp:(.text+0x35): undefined reference to std::ostream::operator<<(unsigned long)'
collect2: error: ld returned 1 exit status

By default g++ links against the dynamic libstdc++ library (libstdc++.so). By passing libstdc++.a explicitly you're linking against the static counterpart. You could achieve the same end result with -static-libstdc++.
Both static and dynamic linking against libstdc++ should work. Your issue could be possibly caused by building or installing GCC incorrectly (e.g. applying an incorrect patch, or mixing include files from different GCC builds).
To investigate, produce object file b.o by adding -c to your g++ command line, and preprocessed source b.ii by adding -E -o b.ii. Use nm -u b.o to get mangled names of undefined symbols (add -C to demangle). You'll see that mangled name of the missing symbol is _ZNSolsEm. Try to grep the missing symbol in the list of symbols defined by libstdc++ (nm -D --defined-only /usr/local/gcc-10.2.0/lib64/libstdc++.so). If it is missing from the library, the issue is that the included files expect the library to provide those template instantiations, while the actual library does not.
If you look in b.ii, you'll find that it declares the corresponding extern template towards the end:
extern template class basic_ostringstream<char>;
If you look into sstream.tcc file from gcc install tree that this line comes from, you'll see it's guarded by #if _GLIBCXX_EXTERN_TEMPLATE. The definition of this macro is in c++config.h, and is set depending on --enable-extern-template option at libstdc++ configuration time. If the library is built with --disable-extern-template, it will not provide those template instantiations.

Linking error in test program with RTP (Real-Time Transport Protocol) [duplicate]

This question already has answers here:
What is an undefined reference/unresolved external symbol error and how do I fix it?
(39 answers)
Closed 2 years ago.
I am trying to compile a simple test program using rtp (Real-Time Transport Protocol). Unfortunately I get a linking error I can not get rid off. Here is the Code i try to compile with:
g++ -v main.cpp -o rtp -lccrtp
Here is the main.cpp
#include <ccrtp/rtp.h>
int main(int argc, char *argv[])
{
ost::RTPSession s(ost::InetHostAddress("127.0.0.1"),9000); // bind reception socket.
return 0;
}
and the output:
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/8/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian 8.3.0-6' --with-bugurl=file:///usr/share/doc/gcc-8/README.Bugs --enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++ --prefix=/usr --with-gcc-major-version-only --program-suffix=-8 --program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --enable-bootstrap --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-libmpx --enable-plugin --enable-default-pie --with-system-zlib --with-target-system-zlib --enable-objc-gc=auto --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-offload-targets=nvptx-none --without-cuda-driver --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 8.3.0 (Debian 8.3.0-6)
COLLECT_GCC_OPTIONS='-v' '-o' 'rtp' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
/usr/lib/gcc/x86_64-linux-gnu/8/cc1plus -quiet -v -imultiarch x86_64-linux-gnu -D_GNU_SOURCE main.cpp -quiet -dumpbase main.cpp -mtune=generic -march=x86-64 -auxbase main -version -o /tmp/ccMnYiXi.s
GNU C++14 (Debian 8.3.0-6) version 8.3.0 (x86_64-linux-gnu)
compiled by GNU C version 8.3.0, GMP version 6.1.2, MPFR version 4.0.2, MPC version 1.1.0, isl version isl-0.20-GMP
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
ignoring duplicate directory "/usr/include/x86_64-linux-gnu/c++/8"
ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
ignoring nonexistent directory "/usr/lib/gcc/x86_64-linux-gnu/8/../../../../x86_64-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
/usr/include/c++/8
/usr/include/x86_64-linux-gnu/c++/8
/usr/include/c++/8/backward
/usr/lib/gcc/x86_64-linux-gnu/8/include
/usr/local/include
/usr/lib/gcc/x86_64-linux-gnu/8/include-fixed
/usr/include/x86_64-linux-gnu
/usr/include
End of search list.
GNU C++14 (Debian 8.3.0-6) version 8.3.0 (x86_64-linux-gnu)
compiled by GNU C version 8.3.0, GMP version 6.1.2, MPFR version 4.0.2, MPC version 1.1.0, isl version isl-0.20-GMP
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 3c854693d01dc9a844a56a0b1ab1c0f4
COLLECT_GCC_OPTIONS='-v' '-o' 'rtp' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
as -v --64 -o /tmp/ccBl5GBx.o /tmp/ccMnYiXi.s
GNU assembler version 2.31.1 (x86_64-linux-gnu) using BFD version (GNU Binutils for Debian) 2.31.1
COMPILER_PATH=/usr/lib/gcc/x86_64-linux-gnu/8/:/usr/lib/gcc/x86_64-linux-gnu/8/:/usr/lib/gcc/x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/8/:/usr/lib/gcc/x86_64-linux-gnu/
LIBRARY_PATH=/usr/lib/gcc/x86_64-linux-gnu/8/:/usr/lib/gcc/x86_64-linux-gnu/8/../../../x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/8/../../../../lib/:/lib/x86_64-linux-gnu/:/lib/../lib/:/usr/lib/x86_64-linux-gnu/:/usr/lib/../lib/:/usr/lib/gcc/x86_64-linux-gnu/8/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-v' '-o' 'rtp' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
/usr/lib/gcc/x86_64-linux-gnu/8/collect2 -plugin /usr/lib/gcc/x86_64-linux-gnu/8/liblto_plugin.so -plugin-opt=/usr/lib/gcc/x86_64-linux-gnu/8/lto-wrapper -plugin-opt=-fresolution=/tmp/cc36T3hM.res -plugin-opt=-pass-through=-lgcc_s -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lc -plugin-opt=-pass-through=-lgcc_s -plugin-opt=-pass-through=-lgcc --build-id --eh-frame-hdr -m elf_x86_64 --hash-style=gnu -dynamic-linker /lib64/ld-linux-x86-64.so.2 -pie -o rtp /usr/lib/gcc/x86_64-linux-gnu/8/../../../x86_64-linux-gnu/Scrt1.o /usr/lib/gcc/x86_64-linux-gnu/8/../../../x86_64-linux-gnu/crti.o /usr/lib/gcc/x86_64-linux-gnu/8/crtbeginS.o -L/usr/lib/gcc/x86_64-linux-gnu/8 -L/usr/lib/gcc/x86_64-linux-gnu/8/../../../x86_64-linux-gnu -L/usr/lib/gcc/x86_64-linux-gnu/8/../../../../lib -L/lib/x86_64-linux-gnu -L/lib/../lib -L/usr/lib/x86_64-linux-gnu -L/usr/lib/../lib -L/usr/lib/gcc/x86_64-linux-gnu/8/../../.. /tmp/ccBl5GBx.o -lccrtp -lstdc++ -lm -lgcc_s -lgcc -lc -lgcc_s -lgcc /usr/lib/gcc/x86_64-linux-gnu/8/crtendS.o /usr/lib/gcc/x86_64-linux-gnu/8/../../../x86_64-linux-gnu/crtn.o
/usr/bin/ld: /tmp/ccBl5GBx.o: undefined reference to symbol '_ZNK7ucommon14JoinableThread9is_activeEv'
/usr/bin/ld: //lib/x86_64-linux-gnu/libucommon.so.8: error adding symbols: DSO missing from command line
collect2: error: ld returned 1 exit status
Thanks for the help.

Thanks for the fast reply. That directed me to the solution. I also needed to install
libcommoncpp2-dev
and now it compiles with:
g++ -lccrtp -lucommon -lcommoncpp -o rtp main.cpp
without any errors. Thanks again.

Runtime "symbol lookup error" after compilation and linking of .so

first of all I've searched this one quite a bit and haven't managed to find a question with the same situation.
I'm building a 32 bit plugin as a shared-object on a 64 bit machine and using cpp-redis. cpp-redis built fine and I used a cmake toolchain to force 32 bit, checked the .o files during build and confirmed they are 32 bit.
I compiled and linked my very basic program (consisting of one main source file and an extra lib for talking to my host application since this is a plugin).
Upon running loading the plugin into the host app, I am greeted with:
symbol lookup error: plugins/samp-redis.so: undefined symbol: _ZN9cpp_redis16redis_subscriberC1ERKSt10shared_ptrINS_7network10io_serviceEE
I'm pretty stumped as I've added the cpp-redis dir to the linker path with -L and the library with -l, here's my comp/link lines:
(SDK_DIR is my host app sdk, pretty small and minimal set of .c/h files)
g++ -fpermissive -fPIC -m32 -std=c++11 -c -O3 -w -D LINUX -I$(SDK_DIR) -I$(SDK_DIR)/amx -I/usr/local/include/cpp_redis (source .cpp files...)
g++ -v -Wall -O2 -m32 -fshort-wchar -s -shared -L/usr/local/lib/ -lcpp_redis -o $(OUTFILE) *.o
Which runs fine with no errors, I ran the link stage with -v to check the flags went in properly and it all looks fine.
(added some newlines for readability)
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.9/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure
-v
--with-pkgversion='Debian 4.9.2-10'
--with-bugurl=file:///usr/share/doc/gcc-4.9/README.Bugs
--enable-languages=c,c++,java,go,d,fortran,objc,obj-c++
--prefix=/usr
--program-suffix=-4.9
--enable-shared
--enable-linker-build-id
--libexecdir=/usr/lib
--without-included-gettext
--enable-threads=posix
--with-gxx-include-dir=/usr/include/c++/4.9
--libdir=/usr/lib
--enable-nls
--with-sysroot=/
--enable-clocale=gnu
--enable-libstdcxx-debug
--enable-libstdcxx-time=yes
--enable-gnu-unique-object
--disable-vtable-verify
--enable-plugin
--with-system-zlib
--disable-browser-plugin
--enable-java-awt=gtk
--enable-gtk-cairo
--with-java-home=/usr/lib/jvm/java-1.5.0-gcj-4.9-amd64/jre
--enable-java-home
--with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-4.9-amd64
--with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-4.9-amd64
--with-arch-directory=amd64
--with-ecj-jar=/usr/share/java/eclipse-ecj.jar
--enable-objc-gc
--enable-multiarch
--with-arch-32=i586
--with-abi=m64
--with-multilib-list=m32,m64,mx32
--enable-multilib
--with-tune=generic
--enable-checking=release
--build=x86_64-linux-gnu
--host=x86_64-linux-gnu
--target=x86_64-linux-gnu
Thread model: posix
gcc version 4.9.2 (Debian 4.9.2-10)
COMPILER_PATH=/usr/lib/gcc/x86_64-linux-gnu/4.9/
:/usr/lib/gcc/x86_64-linux-gnu/4.9/
:/usr/lib/gcc/x86_64-linux-gnu/
:/usr/lib/gcc/x86_64-linux-gnu/4.9/
:/usr/lib/gcc/x86_64-linux-gnu/
LIBRARY_PATH=/usr/lib/gcc/x86_64-linux-gnu/4.9/32/
:/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../lib32/
:/lib/../lib32/
:/usr/lib/../lib32/
:/usr/lib/gcc/x86_64-linux-gnu/4.9/
:/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../
:/lib/
:/usr/lib/
COLLECT_GCC_OPTIONS='-v' '-Wall' '-O2' '-m32' '-fshort-wchar' '-s' '-shared' '-L/usr/local/lib/' '-o' 'samp-redis.so' '-shared-libgcc' '-mtune=generic' '-march=i586'
/usr/lib/gcc/x86_64-linux-gnu/4.9/collect2
-plugin /usr/lib/gcc/x86_64-linux-gnu/4.9/liblto_plugin.so
-plugin-opt=/usr/lib/gcc/x86_64-linux-gnu/4.9/lto-wrapper
-plugin-opt=-fresolution=/tmp/cc0Lo5po.res
-plugin-opt=-pass-through=-lgcc_s
-plugin-opt=-pass-through=-lc
-plugin-opt=-pass-through=-lgcc_s
--sysroot=/
--build-id
--eh-frame-hdr
-m elf_i386
--hash-style=gnu
-shared
-o samp-redis.so
-s /usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../lib32/crti.o /usr/lib/gcc/x86_64-linux-gnu/4.9/32/crtbeginS.o
-L/usr/local/lib/
-L/usr/lib/gcc/x86_64-linux-gnu/4.9/32
-L/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../lib32
-L/lib/../lib32
-L/usr/lib/../lib32
-L/usr/lib/gcc/x86_64-linux-gnu/4.9
-L/usr/lib/gcc/x86_64-linux-gnu/4.9/../../..
-lcpp_redis amxplugin2.o amxplugin.o main.o
-lstdc++
-lm
-lgcc_s
-lc
-lgcc_s /usr/lib/gcc/x86_64-linux-gnu/4.9/32/crtendS.o /usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../lib32/crtn.o
Am I misunderstanding the linking stage or statically linking? It has been a while since I did C++... I'm all about Python and Go these days!
EDIT:
Compiling with -W,--no-undefined results in this output:
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.9/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure
-v
--with-pkgversion='Debian 4.9.2-10'
--with-bugurl=file:///usr/share/doc/gcc-4.9/README.Bugs
--enable-languages=c,c++,java,go,d,fortran,objc,obj-c++
--prefix=/usr
--program-suffix=-4.9
--enable-shared
--enable-linker-build-id
--libexecdir=/usr/lib
--without-included-gettext
--enable-threads=posix
--with-gxx-include-dir=/usr/include/c++/4.9
--libdir=/usr/lib
--enable-nls
--with-sysroot=/
--enable-clocale=gnu
--enable-libstdcxx-debug
--enable-libstdcxx-time=yes
--enable-gnu-unique-object
--disable-vtable-verify
--enable-plugin
--with-system-zlib
--disable-browser-plugin
--enable-java-awt=gtk
--enable-gtk-cairo
--with-java-home=/usr/lib/jvm/java-1.5.0-gcj-4.9-amd64/jre
--enable-java-home
--with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-4.9-amd64
--with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-4.9-amd64
--with-arch-directory=amd64
--with-ecj-jar=/usr/share/java/eclipse-ecj.jar
--enable-objc-gc
--enable-multiarch
--with-arch-32=i586
--with-abi=m64
--with-multilib-list=m32,m64,mx32
--enable-multilib
--with-tune=generic
--enable-checking=release
--build=x86_64-linux-gnu
--host=x86_64-linux-gnu
--target=x86_64-linux-gnu
Thread model: posix
gcc version 4.9.2 (Debian 4.9.2-10)
COMPILER_PATH=/usr/lib/gcc/x86_64-linux-gnu/4.9/
:/usr/lib/gcc/x86_64-linux-gnu/4.9/
:/usr/lib/gcc/x86_64-linux-gnu/
:/usr/lib/gcc/x86_64-linux-gnu/4.9/
:/usr/lib/gcc/x86_64-linux-gnu/
LIBRARY_PATH=/usr/lib/gcc/x86_64-linux-gnu/4.9/32/
:/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../lib32/
:/lib/../lib32/
:/usr/lib/../lib32/
:/usr/lib/gcc/x86_64-linux-gnu/4.9/
:/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../
:/lib/
:/usr/lib/
COLLECT_GCC_OPTIONS='-v' '-Wall' '-O2' '-m32' '-fshort-wchar' '-s' '-shared' '-L/usr/local/lib/' '-o' 'samp-redis.so' '-shared-libgcc' '-mtune=generic' '-march=i586'
/usr/lib/gcc/x86_64-linux-gnu/4.9/collect2
-plugin /usr/lib/gcc/x86_64-linux-gnu/4.9/liblto_plugin.so
-plugin-opt=/usr/lib/gcc/x86_64-linux-gnu/4.9/lto-wrapper
-plugin-opt=-fresolution=/tmp/ccOq8qY8.res
-plugin-opt=-pass-through=-lgcc_s
-plugin-opt=-pass-through=-lc
-plugin-opt=-pass-through=-lgcc_s
--sysroot=/
--build-id
--eh-frame-hdr
-m elf_i386
--hash-style=gnu
-shared
-o samp-redis.so
-s /usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../lib32/crti.o /usr/lib/gcc/x86_64-linux-gnu/4.9/32/crtbeginS.o
-L/usr/local/lib/
-L/usr/lib/gcc/x86_64-linux-gnu/4.9/32
-L/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../lib32
-L/lib/../lib32
-L/usr/lib/../lib32
-L/usr/lib/gcc/x86_64-linux-gnu/4.9
-L/usr/lib/gcc/x86_64-linux-gnu/4.9/../../..
-Bstatic
--no-undefined
-lcpp_redis amxplugin.o amxplugin2.o main.o
-lstdc++
-lm
-lgcc_s
-lc
-lgcc_s /usr/lib/gcc/x86_64-linux-gnu/4.9/32/crtendS.o /usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../lib32/crtn.o
/usr/bin/ld: cannot find
-lgcc_s
/usr/bin/ld: cannot find
-lgcc_s
collect2: error: ld returned 1 exit status
makefile:15: recipe for target 'build' failed
make: *** [build] Error 1
Apparently it can't find gcc_s whatever that is? s=static?
I tried searching for gcc libs:
$ find /usr/ -name libgcc*
/usr/lib/gcc/x86_64-linux-gnu/4.9/libgcc_s.so
/usr/lib/gcc/x86_64-linux-gnu/4.9/libgcc_eh.a
/usr/lib/gcc/x86_64-linux-gnu/4.9/x32/libgcc_s.so
/usr/lib/gcc/x86_64-linux-gnu/4.9/x32/libgcc_eh.a
/usr/lib/gcc/x86_64-linux-gnu/4.9/x32/libgcc.a
/usr/lib/gcc/x86_64-linux-gnu/4.9/libgcc.a
/usr/lib/gcc/x86_64-linux-gnu/4.9/32/libgcc_s.so
/usr/lib/gcc/x86_64-linux-gnu/4.9/32/libgcc_eh.a
/usr/lib/gcc/x86_64-linux-gnu/4.9/32/libgcc.a
/usr/lib/gcc/x86_64-linux-gnu/4.9/libgcc_s_32.so
/usr/lib/gcc/x86_64-linux-gnu/4.9/libgcc_s_x32.so
/usr/lib/gcc/x86_64-linux-gnu/4.8/libgcc_s.so
/usr/lib/gcc/x86_64-linux-gnu/4.8/libgcc_eh.a
/usr/lib/gcc/x86_64-linux-gnu/4.8/libgcc.a
/usr/lib/x86_64-linux-gnu/libgccpp.so.1
/usr/lib/x86_64-linux-gnu/libgccpp.so.1.0.3
Yet doing a ldconfig search shows files named libgcc.so.1:
$ sudo /sbin/ldconfig -p | grep libgcc
libgccpp.so.1 (libc6,x86-64) => /usr/lib/x86_64-linux-gnu/libgccpp.so.1
libgcc_s.so.1 (libc6,x32) => /usr/libx32/libgcc_s.so.1
libgcc_s.so.1 (libc6,x86-64) => /lib/x86_64-linux-gnu/libgcc_s.so.1
libgcc_s.so.1 (libc6) => /usr/lib32/libgcc_s.so.1
Could this be the reason?
And googling the error brings up some results so I'll keep digging...

Even if you build cpp_redis as static library for it to be linkable with shared library it must be compiled with -fPIC flag ie code must be relocatable. Looks like in your case linker silently ignores incompatible code when linking shared lib. You can check if symbols from cpp_redis resolved into your plugin by running nm with your .so file.
According to your update, you should link your plugin with -W,--no-undefined not cpp_redis. Most probably it will fail as symbols from host program would be missing. But you can check if symbols from cpp_redis are listed as missing or not.

unable to link Intel TBB library with libtbb in /usr/lib

I downloaded the pre built headers and libraries for Intel TBB from Intel's TBB website. I updated ldconfig to add the tbb shared library to /usr/lib. However on compiling with -tbb the code using g++ ld returns -1 as it is unable to find libtbb
libtbb.so.2 is present in /usr/lib/
here is my full g++ output
g++ hellotbb.cpp -o htbb -I$HOME/libs/tbb43/include -v -ltbb
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.8/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 4.8.2-19ubuntu1' --with-bugurl=file:///usr/share/doc/gcc-4.8/README.Bugs --enable-languages=c,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.8 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.8 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object --disable-libmudflap --enable-plugin --with-system-zlib --disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-4.8-amd64/jre --enable-java-home --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-4.8-amd64 --with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-4.8-amd64 --with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --enable-objc-gc --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.8.2 (Ubuntu 4.8.2-19ubuntu1)
COLLECT_GCC_OPTIONS='-o' 'htbb' '-I' '/home/govind/libs/tbb43/include' '-v' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
/usr/lib/gcc/x86_64-linux-gnu/4.8/cc1plus -quiet -v -I /home/govind/libs/tbb43/include -imultiarch x86_64-linux-gnu -D_GNU_SOURCE hellotbb.cpp -quiet -dumpbase hellotbb.cpp -mtune=generic -march=x86-64 -auxbase hellotbb -version -fstack-protector -Wformat -Wformat-security -o /tmp/ccnjmEt3.s
GNU C++ (Ubuntu 4.8.2-19ubuntu1) version 4.8.2 (x86_64-linux-gnu)
compiled by GNU C version 4.8.2, GMP version 5.1.3, MPFR version 3.1.2-p3, MPC version 1.0.1
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
ignoring duplicate directory "/usr/include/x86_64-linux-gnu/c++/4.8"
ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
ignoring nonexistent directory "/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../../x86_64-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
/home/govind/libs/tbb43/include
/usr/include/c++/4.8
/usr/include/x86_64-linux-gnu/c++/4.8
/usr/include/c++/4.8/backward
/usr/lib/gcc/x86_64-linux-gnu/4.8/include
/usr/local/include
/usr/lib/gcc/x86_64-linux-gnu/4.8/include-fixed
/usr/include/x86_64-linux-gnu
/usr/include
End of search list.
GNU C++ (Ubuntu 4.8.2-19ubuntu1) version 4.8.2 (x86_64-linux-gnu)
compiled by GNU C version 4.8.2, GMP version 5.1.3, MPFR version 3.1.2-p3, MPC version 1.0.1
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 26a7c0bd346d04102f6aea776e0cccc5
COLLECT_GCC_OPTIONS='-o' 'htbb' '-I' '/home/govind/libs/tbb43/include' '-v' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
as -v -I /home/govind/libs/tbb43/include --64 -o /tmp/ccC9Xpee.o /tmp/ccnjmEt3.s
GNU assembler version 2.24 (x86_64-linux-gnu) using BFD version (GNU Binutils for Ubuntu) 2.24
COMPILER_PATH=/usr/lib/gcc/x86_64-linux-gnu/4.8/:/usr/lib/gcc/x86_64-linux-gnu/4.8/:/usr/lib/gcc/x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/4.8/:/usr/lib/gcc/x86_64-linux-gnu/
LIBRARY_PATH=/usr/lib/gcc/x86_64-linux-gnu/4.8/:/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../../lib/:/lib/x86_64-linux-gnu/:/lib/../lib/:/usr/lib/x86_64-linux-gnu/:/usr/lib/../lib/:/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-o' 'htbb' '-I' '/home/govind/libs/tbb43/include' '-v' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
/usr/lib/gcc/x86_64-linux-gnu/4.8/collect2 --sysroot=/ --build-id --eh-frame-hdr -m elf_x86_64 --hash-style=gnu --as-needed -dynamic-linker /lib64/ld-linux-x86-64.so.2 -z relro -o htbb /usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crt1.o /usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crti.o /usr/lib/gcc/x86_64-linux-gnu/4.8/crtbegin.o -L/usr/lib/gcc/x86_64-linux-gnu/4.8 -L/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu -L/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../../lib -L/lib/x86_64-linux-gnu -L/lib/../lib -L/usr/lib/x86_64-linux-gnu -L/usr/lib/../lib -L/usr/lib/gcc/x86_64-linux-gnu/4.8/../../.. /tmp/ccC9Xpee.o -ltbb -lstdc++ -lm -lgcc_s -lgcc -lc -lgcc_s -lgcc /usr/lib/gcc/x86_64-linux-gnu/4.8/crtend.o /usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crtn.o
/usr/bin/ld: cannot find -ltbb
collect2: error: ld returned 1 exit status
It seems that ld does not detect my tbb library in /usr/lib/

Make sure libtbb.so is also present and install libtbb-dev package if needed:
apt-get install libtbb-dev
BTW, your include files are located in suspicious place. Looks like you mixed installation of TBB binaries and include files from different sources. It can lead to bad problems especially if headers are newer than binaries.

How to link C++ object files with ld

I'm trying to link the output of C++ using ld and not g++. I'm only doing this to learn how to do it, not for practical purposes, so please don't suggest just to do it with g++.
Looking at this question, the person gets the same error when they run the ld command:
$ ld test.o -o test.out
ld: warning: cannot find entry symbol _start; defaulting to 00000000004000e8
test.o: In function `main':
test.cpp:(.text+0x1c): undefined reference to `strcasecmp'
test.cpp:(.text+0x23): undefined reference to `std::cout'
test.cpp:(.text+0x28): undefined reference to `std::ostream::operator<<(int)'
test.cpp:(.text+0x2d): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::endl<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&)'
test.cpp:(.text+0x35): undefined reference to `std::ostream::operator<<(std::ostream& (*)(std::ostream&))'
test.o: In function `__static_initialization_and_destruction_0(int, int)':
test.cpp:(.text+0x75): undefined reference to `std::ios_base::Init::Init()'
test.cpp:(.text+0x7a): undefined reference to `__dso_handle'
test.cpp:(.text+0x84): undefined reference to `std::ios_base::Init::~Init()'
test.cpp:(.text+0x89): undefined reference to `__cxa_atexit'
ld: test.out: hidden symbol `__dso_handle' isn't defined
ld: final link failed: Bad value
The answers in the linked post suggest that adding the C++ library as a linker argument will fix the problem, so I tried
ld test.o -o test.out -llibstd++
which is what they suggested, and I also tried a lot of other library names like libstdc++ or stdc++. But I'll always get an error that looks like
ld: cannot find -llibstd++
What am I doing wrong and how can I link my object files using ld?

If you run g++ with the -v flag, you'll see the link line it uses. Here's a simple example program:
#include <iostream>
int main(void)
{
std::cout << "Hello, world!" << std::endl;
return 0;
}
And the output from running g++ -v -o example example.cpp:
Using built-in specs.
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro 4.4.4-14ubuntu5.1' --with-bugurl=file:///usr/share/doc/gcc-4.4/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.4 --enable-shared --enable-multiarch --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.4 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc --disable-werror --with-arch-32=i686 --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.4.5 (Ubuntu/Linaro 4.4.4-14ubuntu5.1)
COLLECT_GCC_OPTIONS='-v' '-o' 'example' '-shared-libgcc' '-mtune=generic'
/usr/lib/gcc/x86_64-linux-gnu/4.4.5/cc1plus -quiet -v -D_GNU_SOURCE example.cpp -D_FORTIFY_SOURCE=2 -quiet -dumpbase example.cpp -mtune=generic -auxbase example -version -fstack-protector -o /tmp/ccV8qjvd.s
ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
ignoring nonexistent directory "/usr/lib/gcc/x86_64-linux-gnu/4.4.5/../../../../x86_64-linux-gnu/include"
ignoring nonexistent directory "/usr/include/x86_64-linux-gnu"
#include "..." search starts here:
#include <...> search starts here:
/usr/include/c++/4.4
/usr/include/c++/4.4/x86_64-linux-gnu
/usr/include/c++/4.4/backward
/usr/local/include
/usr/lib/gcc/x86_64-linux-gnu/4.4.5/include
/usr/lib/gcc/x86_64-linux-gnu/4.4.5/include-fixed
/usr/include
End of search list.
GNU C++ (Ubuntu/Linaro 4.4.4-14ubuntu5.1) version 4.4.5 (x86_64-linux-gnu)
compiled by GNU C version 4.4.5, GMP version 4.3.2, MPFR version 3.0.0-p3.
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: d92fbc2d715a3b7e0f4133f0c40053e4
COLLECT_GCC_OPTIONS='-v' '-o' 'example' '-shared-libgcc' '-mtune=generic'
as -V -Qy -o /tmp/ccGHR0pc.o /tmp/ccV8qjvd.s
GNU assembler version 2.20.51 (x86_64-linux-gnu) using BFD version (GNU Binutils for Ubuntu) 2.20.51-system.20100908
COMPILER_PATH=/usr/lib/gcc/x86_64-linux-gnu/4.4.5/:/usr/lib/gcc/x86_64-linux-gnu/4.4.5/:/usr/lib/gcc/x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/4.4.5/:/usr/lib/gcc/x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/4.4.5/:/usr/lib/gcc/x86_64-linux-gnu/
LIBRARY_PATH=/usr/lib/gcc/x86_64-linux-gnu/4.4.5/:/usr/lib/gcc/x86_64-linux-gnu/4.4.5/:/usr/lib/gcc/x86_64-linux-gnu/4.4.5/../../../../lib/:/lib/../lib/:/usr/lib/../lib/:/usr/lib/gcc/x86_64-linux-gnu/4.4.5/../../../:/lib/:/usr/lib/:/usr/lib/x86_64-linux-gnu/
COLLECT_GCC_OPTIONS='-v' '-o' 'example' '-shared-libgcc' '-mtune=generic'
/usr/lib/gcc/x86_64-linux-gnu/4.4.5/collect2 --build-id --eh-frame-hdr -m elf_x86_64 --hash-style=gnu -dynamic-linker /lib64/ld-linux-x86-64.so.2 -o example -z relro /usr/lib/gcc/x86_64-linux-gnu/4.4.5/../../../../lib/crt1.o /usr/lib/gcc/x86_64-linux-gnu/4.4.5/../../../../lib/crti.o /usr/lib/gcc/x86_64-linux-gnu/4.4.5/crtbegin.o -L/usr/lib/gcc/x86_64-linux-gnu/4.4.5 -L/usr/lib/gcc/x86_64-linux-gnu/4.4.5 -L/usr/lib/gcc/x86_64-linux-gnu/4.4.5/../../../../lib -L/lib/../lib -L/usr/lib/../lib -L/usr/lib/gcc/x86_64-linux-gnu/4.4.5/../../.. -L/usr/lib/x86_64-linux-gnu /tmp/ccGHR0pc.o -lstdc++ -lm -lgcc_s -lgcc -lc -lgcc_s -lgcc /usr/lib/gcc/x86_64-linux-gnu/4.4.5/crtend.o /usr/lib/gcc/x86_64-linux-gnu/4.4.5/../../../../lib/crtn.o
Wow, what a mess. Conveniently the link line is the last one there, so you can see what's happening pretty easily.
As you noticed in your comment below, the front-end is using collect2 rather than ld. Luckily, collect2 is just an alias for ld. Here's an example using it:
First let's generate an object file:
$ ls
example.cpp
$ c++ -c example.cpp
$ ls
example.cpp example.o
Then we'll use the front-end to link it to see the link line:
$ c++ -v -o example example.o
Using built-in specs.
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro 4.4.4-14ubuntu5.1' --with-bugurl=file:///usr/share/doc/gcc-4.4/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.4 --enable-shared --enable-multiarch --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.4 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc --disable-werror --with-arch-32=i686 --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.4.5 (Ubuntu/Linaro 4.4.4-14ubuntu5.1)
COMPILER_PATH=/usr/lib/gcc/x86_64-linux-gnu/4.4.5/:/usr/lib/gcc/x86_64-linux-gnu/4.4.5/:/usr/lib/gcc/x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/4.4.5/:/usr/lib/gcc/x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/4.4.5/:/usr/lib/gcc/x86_64-linux-gnu/
LIBRARY_PATH=/usr/lib/gcc/x86_64-linux-gnu/4.4.5/:/usr/lib/gcc/x86_64-linux-gnu/4.4.5/:/usr/lib/gcc/x86_64-linux-gnu/4.4.5/../../../../lib/:/lib/../lib/:/usr/lib/../lib/:/usr/lib/gcc/x86_64-linux-gnu/4.4.5/../../../:/lib/:/usr/lib/:/usr/lib/x86_64-linux-gnu/
COLLECT_GCC_OPTIONS='-v' '-o' 'example' '-shared-libgcc' '-mtune=generic'
/usr/lib/gcc/x86_64-linux-gnu/4.4.5/collect2 --build-id --eh-frame-hdr -m elf_x86_64 --hash-style=gnu -dynamic-linker /lib64/ld-linux-x86-64.so.2 -o example -z relro /usr/lib/gcc/x86_64-linux-gnu/4.4.5/../../../../lib/crt1.o /usr/lib/gcc/x86_64-linux-gnu/4.4.5/../../../../lib/crti.o /usr/lib/gcc/x86_64-linux-gnu/4.4.5/crtbegin.o -L/usr/lib/gcc/x86_64-linux-gnu/4.4.5 -L/usr/lib/gcc/x86_64-linux-gnu/4.4.5 -L/usr/lib/gcc/x86_64-linux-gnu/4.4.5/../../../../lib -L/lib/../lib -L/usr/lib/../lib -L/usr/lib/gcc/x86_64-linux-gnu/4.4.5/../../.. -L/usr/lib/x86_64-linux-gnu example.o -lstdc++ -lm -lgcc_s -lgcc -lc -lgcc_s -lgcc /usr/lib/gcc/x86_64-linux-gnu/4.4.5/crtend.o /usr/lib/gcc/x86_64-linux-gnu/4.4.5/../../../../lib/crtn.o
Then throw away the binary, and link ourselves (normally, I would have just copy/pasted the line, but to make it easier to read I did it the multiline way with \s):
$ ls
example example.cpp example.o
$ rm example
$ ls
example.cpp example.o
$ ld \
> --build-id \
> --eh-frame-hdr \
> -m elf_x86_64 \
> --hash-style=gnu \
> -dynamic-linker \
> /lib64/ld-linux-x86-64.so.2 \
> -o example \
> -z relro \
> /usr/lib/gcc/x86_64-linux-gnu/4.4.5/../../../../lib/crt1.o \
> /usr/lib/gcc/x86_64-linux-gnu/4.4.5/../../../../lib/crti.o \
> /usr/lib/gcc/x86_64-linux-gnu/4.4.5/crtbegin.o \
> -L/usr/lib/gcc/x86_64-linux-gnu/4.4.5 \
> -L/usr/lib/gcc/x86_64-linux-gnu/4.4.5 \
> -L/usr/lib/gcc/x86_64-linux-gnu/4.4.5/../../../../lib \
> -L/lib/../lib \
> -L/usr/lib/../lib \
> -L/usr/lib/gcc/x86_64-linux-gnu/4.4.5/../../.. \
> -L/usr/lib/x86_64-linux-gnu \
> example.o \
> -lstdc++ \
> -lm \
> -lgcc_s \
> -lgcc \
> -lc \
> -lgcc_s \
> -lgcc \
> /usr/lib/gcc/x86_64-linux-gnu/4.4.5/crtend.o \
> /usr/lib/gcc/x86_64-linux-gnu/4.4.5/../../../../lib/crtn.o
Finally, run it!
$ ls
example example.cpp example.o
$ ./example
Hello, world!
You can probably significantly shorten that link line by removing some arguments. Here's the minimal set I came up with after some experimentation:
$ ld \
> -dynamic-linker \
> /lib64/ld-linux-x86-64.so.2 \
> -o example \
> /usr/lib/gcc/x86_64-linux-gnu/4.4.5/../../../../lib/crt1.o \
> /usr/lib/gcc/x86_64-linux-gnu/4.4.5/../../../../lib/crti.o \
> /usr/lib/gcc/x86_64-linux-gnu/4.4.5/crtbegin.o \
> example.o \
> -L/usr/lib/gcc/x86_64-linux-gnu/4.4.5 \
> -lstdc++ \
> -lc \
> /usr/lib/gcc/x86_64-linux-gnu/4.4.5/crtend.o \
> /usr/lib/gcc/x86_64-linux-gnu/4.4.5/../../../../lib/crtn.o
This set of flags and libraries will of course depend on what library functions and language features your program uses.

I managed to compile like this
ld -s hello.o crt2.o -o hello.exe libstdc++.a libgcc.a libmingw32.a libmingwex.a libmsvcrt.a libkernel32.a

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