Question

I already updated to the new Ubuntu 11.10.The problem is now, that the software I am working on is not linking any more. I found this wiki entry which seems to describe the problem. None the less I am unable to fix it. To reproduce the problem I wrote the following small test program:

#include <iostream>
#include <boost/thread.hpp>

void blubb() {
  std::cout << "hello world" << std::endl;
}

int main() {
  boost::thread t(&blubb);
  t.join();
}

Than I use the following command to compile:

g++ -o test -lboost_thread test.cc

The output I get is the following:

/tmp/cc0O0dAC.o: In function `main':
test.cc:(.text+0x49): undefined reference to `boost::thread::join()'
test.cc:(.text+0x55): undefined reference to `boost::thread::~thread()'
test.cc:(.text+0x70): undefined reference to `boost::thread::~thread()'
/tmp/cc0O0dAC.o: In function `boost::detail::thread_data_base::thread_data_base()':
test.cc:(.text._ZN5boost6detail16thread_data_baseC2Ev[_ZN5boost6detail16thread_data_baseC5Ev]+0x24):     undefined reference to `vtable for boost::detail::thread_data_base'
/tmp/cc0O0dAC.o: In function `boost::thread::thread<void (*)()>(void (*)(), boost::disable_if<boost::is_convertible<void (*&)(), boost::detail::thread_move_t<void (* ()> >, boost::thread::dummy*>::type)':
test.cc:(.text._ZN5boost6threadC2IPFvvEEET_NS_10disable_ifINS_14is_convertibleIRS4_NS_6detail13thread_move_tIS4_EEEEPNS0_5dummyEE4typeE[_ZN5boost6threadC5IPFvvEEET_NS_10disable_ifINS_14is_convertibleIRS4_NS_6detail13thread_move_tIS4_EEEEPNS0_5dummyEE4typeE]+0x30): undefined reference to `boost::thread::start_thread()'
/tmp/cc0O0dAC.o: In function `boost::detail::thread_data<void (*)()>::~thread_data()':
test.cc:(.text._ZN5boost6detail11thread_dataIPFvvEED2Ev[_ZN5boost6detail11thread_dataIPFvvEED5Ev]+0x1f): undefined reference to `boost::detail::thread_data_base::~thread_data_base()'
/tmp/cc0O0dAC.o:(.rodata._ZTIN5boost6detail11thread_dataIPFvvEEE[typeinfo for boost::detail::thread_data<void (*)()>]+0x10): undefined reference to `typeinfo for boost::detail::thread_data_base'
collect2: ld returned 1 exit status

I also tried to add -lpthread and -pthread in several orders with no success. This command works smoothly on an older Ubuntu version. What am I doing wrong (I have similar problems with PCRE and Google Protocol Buffers).

Thanks in advance for any help!

Answer 1

Ok I mamaged to fix it, it is ridiculous:

as written in the question

g++ -o test -lboost_thread test.cc

does not work, but

g++ -o test test.cc -lboost_thread

does… So not only the order of libraries matter, but also the source files must be written before the dependencies…