Boost::system link error on Ubuntu

Question

I'm trying to compile the following c++ code that implements Context Tree Switching (More info on the download page):

Zip archive, 0.2 MB

which requires some boost libraries. I download the latest version from boost.org and built all libraries that needed building following the instructions on the website. I also modified the makefile included in the archive to add the boost lib path and boost_system, but I still get an error. Here's the makefile i'm using:

PROGRAM = cts
SOURCES = $(wildcard *.cpp)
OBJECTS = $(SOURCES:.cpp=.o)
CFLAGS = -Wall
LDFLAGS = -lboost_program_options -lboost_filesystem -lboost_system

$(PROGRAM): $(OBJECTS) Makefile
    g++ $(CFLAGS) -L/home/users/mnembrini/opt/boost/lib $(LDFLAGS) -o $(PROGRAM) $(OBJECTS)

# Include known dependecies from -MMD
#-include $(OBJECTS:.o=.d)

%.o: %.cpp
    g++ -MMD $(CFLAGS) -I/home/users/mnembrini/opt/boost/include -c $<

clean:
    rm -f $(OBJECTS) *.d

.PHONY: clean

where boost is in ~/opt/boost (constains lib and include subdir). And here's the linking error:

mnembrini@meem:~/src/cts-v1 $ make
g++ -MMD -Wall -I/home/users/mnembrini/opt/boost/include -c ac.cpp
g++ -MMD -Wall -I/home/users/mnembrini/opt/boost/include -c cts.cpp
cts.cpp: In member function ‘virtual void SwitchingTree::update(bit_t)’:
cts.cpp:402:12: warning: variable ‘snc’ set but not used [-Wunused-but-set-variable]
cts.cpp: In member function ‘virtual double SwitchingTree::prob(bit_t)’:
cts.cpp:432:12: warning: variable ‘snc’ set but not used [-Wunused-but-set-variable]
g++ -MMD -Wall -I/home/users/mnembrini/opt/boost/include -c ctw.cpp
g++ -MMD -Wall -I/home/users/mnembrini/opt/boost/include -c icsilog.cpp
g++ -MMD -Wall -I/home/users/mnembrini/opt/boost/include -c main.cpp
g++ -MMD -Wall -I/home/users/mnembrini/opt/boost/include -c PowFast.cpp
g++ -Wall -L/home/users/mnembrini/opt/boost/lib -lboost_program_options -lboost_filesystem -lboost_system -o cts ac.o cts.o ctw.o icsilog.o main.o PowFast.o
cts.o: In function `__static_initialization_and_destruction_0(int, int)':
cts.cpp:(.text+0x1743): undefined reference to `boost::system::generic_category()'
cts.cpp:(.text+0x174f): undefined reference to `boost::system::generic_category()'
cts.cpp:(.text+0x175b): undefined reference to `boost::system::system_category()'
ctw.o: In function `__static_initialization_and_destruction_0(int, int)':
ctw.cpp:(.text+0xfcf): undefined reference to `boost::system::generic_category()'
ctw.cpp:(.text+0xfdb): undefined reference to `boost::system::generic_category()'
ctw.cpp:(.text+0xfe7): undefined reference to `boost::system::system_category()'
main.o: In function `showHelp()':
main.cpp:(.text+0x1c): undefined reference to `boost::program_options::operator<<(std::basic_ostream<char, std::char_traits<char> >&, boost::program_options::options_description const&)'
main.o: In function `initOptions(int, char**, boost::program_options::variables_map&)':
main.cpp:(.text+0x10f): undefined reference to `boost::program_options::options_description::add_options()'
main.cpp:(.text+0x129): undefined reference to `boost::program_options::options_description_easy_init::operator()(char const*, char const*)'
main.cpp:(.text+0x13e): undefined reference to `boost::program_options::options_description_easy_init::operator()(char const*, boost::program_options::value_semantic const*, char const*)'
main.cpp:(.text+0x153): undefined reference to `boost::program_options::options_description_easy_init::operator()(char const*, boost::program_options::value_semantic const*, char const*)'
main.cpp:(.text+0x166): undefined reference to `boost::program_options::options_description_easy_init::operator()(char const*, boost::program_options::value_semantic const*, char const*)'
main.cpp:(.text+0x1d6): undefined reference to `boost::program_options::store(boost::program_options::basic_parsed_options<char> const&, boost::program_options::variables_map&, bool)'
main.cpp:(.text+0x200): undefined reference to `boost::program_options::notify(boost::program_options::variables_map&)'
main.o: In function `__static_initialization_and_destruction_0(int, int)':
main.cpp:(.text+0x1f13): undefined reference to `boost::system::generic_category()'
main.cpp:(.text+0x1f1f): undefined reference to `boost::system::generic_category()'
[snip (2-3 screens like above)]
collect2: ld returned 1 exit status
make: *** [cts] Error 1

I'm using Gcc 4.6.3 on Ubuntu 12.04 64bit.

Answer 1

You need to (just like n.m earlier wrote) make sure you have the correct order of the linking. Basically some implementations care about what order you link object but also libraries.

If you link a library that hasnt yet been referenced by previous code it will be discarded. I remember coming up with a solution to hack in different (versions of) libraries in a program by referencing the same symbol but in an object linked after the first one and then re-link another library version:

-lyourprojwantingv1 -llibraryofv1 -lyourprojwantingv2 -llibraryofv2

Personally i think this is all just madness! (All of it!)

Answer 2

Place all the libraries after all the object files within the command line. The order is important here, unlike on some other operating systems.