C++ undefined reference when linking

Question

Im wondering if anyone would be able to help me as I have been scratching my head for two days on this.

I have done the compilation and when trying to link a source code on linux getting undefined reference

Compiling using,

g++ -g -I/u01/kasunt/workspace/corelibCORBA/include -I/u01/kasunt/workspace/corelibCORBA/installed_components/include -I/u01/kasunt/workspace/corelibCORBA/idl -I/u01/kasunt/workspace/corelibCORBA/src/Server -I/u01/kasunt/workspace/corelibCORBA/installed_components/idl -I/u01/kasunt/workspace/corelibCORBA/installed_components/src/Server -I/u01/kasunt/workspace/corelibCORBA/installed_components/imake -DNARROWPROTO -I . -I/u01/kasunt/workspace/corelibCORBA/installed_components/include -W -Wall -Wpointer-arith -pipe -D_POSIX_THREADS -D_POSIX_THREAD_SAFE_FUNCTIONS -g -O -I/u01/kasunt/workspace/corelibCORBA/include -g -O -I/u01/kasunt/workspace/corelibCORBA/include -fvisibility=hidden -fvisibility-inlines-hidden -DACE_GCC_HAS_TEMPLATE_INSTANTIATION_VISIBILITY_ATTRS=1 -W -Wall -Wpointer-arith -ggdb -pipe -Wall -g -D_linux_ -D_x86_ -rdynamic -D_REENTRANT -DTAO_HAS_INTERCEPTORS=0 -DTAO_HAS_VALUETYPE=1 -D_REENTRANT -DACE_HAS_AIO_CALLS -D_GNU_SOURCE -I/usr/local/ACE+TAO+CIAO-5.7.9/ACE_wrappers -I/usr/local/ACE+TAO+CIAO-5.7.9/ACE_wrappers/TAO -I/usr/local/ACE+TAO+CIAO-5.7.9/ACE_wrappers/TAO/orbsvcs -DACE_HAS_EXCEPTIONS -D__ACE_INLINE__ -c -o TestSeqWrapper.o TestSeqWrapper.cpp

Linking using,

g++ -o TestSeqWrapper TestSeqWrapper.o -g -L/u01/kasunt/workspace/corelibCORBA/lib -L/u01/kasunt/workspace/corelibCORBA/installed_components/lib -g -O -Wl,-E -L/usr/local/ACE+TAO+CIAO-5.7.9/ACE_wrappers/lib -L/usr/local/ACE+TAO+CIAO-5.7.9/ACE_wrappers/lib -L/usr/local/ACE+TAO+CIAO-5.7.9/ACE_wrappers/TAO/tao -L/u01/kasunt/workspace/corelibCORBA/installed_components/idl -lcorelibCORBA -lcorelibCORBA /u01/kasunt/workspace/corelibCORBA/installed_components/lib/corelibCORBA3r.lib /u01/kasunt/workspace/corelibCORBA/installed_components/lib/CorbaController3r.lib /u01/kasunt/workspace/corelibCORBA/installed_components/lib/EConcurrency3r.lib /u01/kasunt/workspace/corelibCORBA/installed_components/lib/corelibLogger3r.lib /u01/kasunt/workspace/corelibCORBA/installed_components/lib/LeakTracker3r.lib /u01/kasunt/workspace/corelibCORBA/installed_components/lib/trace3r.lib -lDefineTimeZone /u01/kasunt/workspace/corelibCORBA/installed_components/lib/timestamp3r.lib /u01/kasunt/workspace/corelibCORBA/installed_components/lib/ApplConfig3r.lib /u01/kasunt/workspace/corelibCORBA/installed_components/lib/appl3r.lib /u01/kasunt/workspace/corelibCORBA/installed_components/lib/logstream3r.lib /u01/kasunt/workspace/corelibCORBA/installed_components/lib/disklog3r.lib /u01/kasunt/workspace/corelibCORBA/installed_components/lib/timeout3r.lib /u01/kasunt/workspace/corelibCORBA/installed_components/lib/getpnam3r.lib /u01/kasunt/workspace/corelibCORBA/installed_components/lib/config3r.lib /u01/kasunt/workspace/corelibCORBA/installed_components/lib/strl3r.lib /u01/kasunt/workspace/corelibCORBA/installed_components/lib/string3r.lib /u01/kasunt/workspace/corelibCORBA/installed_components/lib/command3r.lib /u01/kasunt/workspace/corelibCORBA/installed_components/lib/cmdargs3r.lib /u01/kasunt/workspace/corelibCORBA/installed_components/lib/CppUtils3r.lib /u01/kasunt/workspace/corelibCORBA/installed_components/lib/BuildTag3r.lib /u01/kasunt/workspace/corelibCORBA/installed_components/lib/exception3r.lib -lCorbaIdl -lTAO_Valuetype -lTAO_PortableServer -lTAO_IORTable -lTAO_AnyTypeCode -lTAO_CosEvent -lTAO_CosNaming -lTAO -lACE

TestSeqWrapper.o: In function `SeqWrapper':
/u01/kasunt/workspace/corelibCORBA/include/corelibCORBA/SeqWrapper.hpp:165: undefined reference to `ECONZ::Corba::ComboElementSeq_T::ComboElementSeq_T()'

Doing nm of the library I can see the above constructor is included,

nm --demangle ../installed_components/lib/libCorbaIdl.so | grep "ECONZ::Corba::ComboElementSeq_T::ComboElementSeq_T"
000327ba t ECONZ::Corba::ComboElementSeq_T::ComboElementSeq_T(ECONZ::Corba::ComboElementSeq_T const&)
000331c2 t ECONZ::Corba::ComboElementSeq_T::ComboElementSeq_T(unsigned int)
0002edb0 t ECONZ::Corba::ComboElementSeq_T::ComboElementSeq_T(unsigned int, unsigned int, ECONZ::Corba::ComboElement_T*, bool)
0002d768 t ECONZ::Corba::ComboElementSeq_T::ComboElementSeq_T()
00032e52 t ECONZ::Corba::ComboElementSeq_T::ComboElementSeq_T(ECONZ::Corba::ComboElementSeq_T const&)
0003172a t ECONZ::Corba::ComboElementSeq_T::ComboElementSeq_T(unsigned int)
0002d8e0 t ECONZ::Corba::ComboElementSeq_T::ComboElementSeq_T(unsigned int, unsigned int, ECONZ::Corba::ComboElement_T*, bool)
0002d8a6 t ECONZ::Corba::ComboElementSeq_T::ComboElementSeq_T()

Offending line on the source code (line 165), SeqWrapper() : var_( new SequenceType ), size_( 0 ) { }

Part of the code,

template< typename SEQUENCE >
class SeqWrapper : CppUtils::NonCopy
{
public:
   typedef SEQUENCE SequenceType;
   typedef typename SequenceType::_var_type SequenceType_var;

   typedef typename ElementTypeOf<SequenceType_var>::ElementType ElementType;
   typedef typename ElementTypeOf<SequenceType_var>::ReturnType ReturnType;
   typedef typename ElementTypeOf<SequenceType_var>::ConstReturnType ConstReturnType;

private:
   SequenceType_var var_;
   CORBA::ULong size_;

  void expand_( CORBA::ULong size )
  {
     // NOTE: current implementation assumes size only increases by small increments
     if (size > var_->length()) {
        var_->length( (size < 16)? 16 : (size > 256? size+256 : 2*size-2) );
     }
  }

public:
   SeqWrapper() : var_( new SequenceType ), size_( 0 ) { }
   SeqWrapper( CORBA::ULong reserve ) : var_( new SequenceType( reserve ) ), size_( 0 ) { var_->length( reserve ); }
   SeqWrapper( SequenceType *ownSeq ) : var_( ownSeq ), size_( ownSeq->length() ) { }

.....

Source code of TestSeqWrapper.cpp (I have removed most of the unwanted stuff to make it less confusing)

#include <iostream>
#include <CppUtils/StringHelpers.hpp>
#include <corelibCORBA/SeqWrapper.hpp>
#include <CorbaC.h>

using namespace std;

int main()
{
    ECONZ::Corba::SeqWrapper< ECONZ::Corba::StringSeq_T > seq;
}

And you can see that I have specified the shared library in the link options (shown in bold). I initially thought it might be due a dependency of some sort and moved the library flag to the beginning to no affect.

I appreciate it.

Answer 1

Since you say

nm --demangle ../installed_components/lib/libCorbaIdl.so
> 0002d768 t ECONZ::Corba::ComboElementSeq_T::ComboElementSeq_T()

This means that ComboElementSeq_T() is in the lib -lCorbaIdl
If the reference is not being found, then it is being used by one of the libraries specified after this library:

> -lCorbaIdl -lTAO_Valuetype -lTAO_PortableServer -lTAO_IORTable
> -lTAO_AnyTypeCode -lTAO_CosEvent -lTAO_CosNaming -lTAO -lACE

Thus one of the follwoing contains : TestSeqWrapper.o: In functionSeqWrapper'`

• -lTAO_Valuetype
• -lTAO_PortableServer
• -lTAO_IORTable
• -lTAO_AnyTypeCode
• -lTAO_CosEvent
• -lTAO_CosNaming
• -lTAO
• -lACE

See: http://stackoverflow.com/questions/1095298/gcc-c-linker-errors-undefined-reference-to-vtable-for-xxx-undefined-referen/1095321#1095321

If you build all the libs as shared libraries then this problem goes away.

Answer 2

typo in your link line?

-L/u01/kasunt/workspace/corelibCORBA/idl

should be

-L/u01/kasunt/workspace/corelibCORBA/lib

Answer 3

Guys,

I dont know if this makes sense to anyone but seems that using library as a static instead of shared works perfectly. So I attached

/u01/kasunt/workspace/corelibCORBA/installed_components/lib/libCorbaIdl.a

and it worked perfectly. Anyone able to explain this ?????

Answer 4

People,

After 10 cups of coffee and few almost sleepless nights I managed to get to the bottom of the problem. Hopefully this helps someone and someone will be able shed some light into me about avoiding such things. So here goes.

I ran the following once again with the -D option this time and it showed a completely different output and one that I was kind of expecting. It resulted in nothing and "ECONZ::Corba::ComboElementSeq_T::ComboElementSeq_T" was not found.

nm -DC ../installed_components/lib/libCorbaIdl.so | grep "ECONZ::Corba::ComboElementSeq_T::ComboElementSeq_T"

Then it sort of led me to believe a compilation problem with the lib. So I looked closely into the compiler flags and found these two "-fvisibility=hidden -fvisibility-inlines-hidden". This was coming from ACE/TAO and it was a new attribute they have added since GCC 4. This was causing the dynamic symbols to be hidden. So my question for anyone who is aware of this is what I should have done to link the library ?

For further reading please read http://gcc.gnu.org/wiki/Visibility