Re: [Swig-user] How do I get rid of these undefined symbols in the generated output?

[Eric Prud'h. <er...@w3...>]

* Josh Cherry <jc...@nc...> [2010-08-17 22:28-0400]
> 
> 
> On Sat, 14 Aug 2010, Bryan Bishop wrote:
> 
> > I am wrapping openNURBS for python consumption and want to fix some
> > undefined symbols, which seem to be traced back to the _wrap.cxx file
> > (the symbols aren't used in the wrapped library as far as I can tell).
> > My work flow is as follows:
> >
> > swig -classic -cpperraswarn -c++ -python opennurbs.i
> > gcc -c ../opennurbs/*.cpp opennurbs_wrap.cxx -I/usr/include/python2.5/
> > -I/usr/lib/python2.5/ -L. -lstdc++ -lpython2.5 -lopenNURBS -lGLU -lGL
> > -lglut -lXmu -lXi -lXext -lX11 2>&1
> > gcc -z defs -shared libopenNURBS.a opennurbs_wrap.o -L. -lstdc++
> > -lpython2.5 -lopenNURBS -lGLU -lGL -lglut -lXmu -lXi -lXext -lX11 -o
> > _opennurbs.so
> > ldd -r _opennurbs.so
> >
> > When I run the ldd -r line I get this back:
> >
> > undefined symbol:
> > _ZNK16ON_UuidIndexList5WriteER16ON_BinaryArchive	(./_opennurbs.so)

Make sure the symbol is located in e.g. one of your .o files:
for f in *.o; do echo $f && objump -t $f | grep _ZNK16ON_UuidIndexList5WriteER16ON_BinaryArchive; done

Here's an annotated example of me looking for some symbol:

eric@ubu:~/checkouts/swobjects/bin$ for f in ../lib/RdfDB.o ../lib/ResultSet.o; do echo $f && objdump -t $f | grep _ZN6w3c_sw5RdfDB13bindVariablesEPNS_9ResultSetEPKNS_5TTermEPKNS_17BasicGraphPatternE; done
../lib/ParserCommon.o
../lib/RdfQueryDB.o
00000000         *UND*	00000000 _ZN6w3c_sw5RdfDB13bindVariablesEPNS_9ResultSetEPKNS_5TTermEPKNS_17BasicGraphPatternE
../lib/RdfDB.o
00001608 g     F .text	00000511 _ZN6w3c_sw5RdfDB13bindVariablesEPNS_9ResultSetEPKNS_5TTermEPKNS_17BasicGraphPatternE
../lib/ResultSet.o

It's undefined (*UND*) in RdfQueryDB.o; but at offset 1608 in RdfDB.o.
Let's find out what the real function name is:

eric@ubu:~/checkouts/swobjects/bin$ objdump -C -t ../lib/RdfDB.o | grep ^00001608
00001608 g     F .text	00000511 w3c_sw::RdfDB::bindVariables(w3c_sw::ResultSet*, w3c_sw::TTerm const*, w3c_sw::BasicGraphPattern const*)


> I would have guessed that those symbols are what the library provides. 
> Usually missing symbols mean that you need change your link line.  I'm not 
> sure why you have libopenNURBS.a in addition to -lopenNURBS.  Having 
> libopenNURBS.a before opennurbs_wrap.o might be the problem.

While you're trying to understand the problem, don't be afraid to
include -lopenNURBS multiple times in the link invocation. A link
invocation of -lfoo -lbar -lfoo allows the linker to resolve foofunc1,
which references barfunc1, which in turn references foofunc2. Such
circularity is rare, but it's still a useful strategy to double your
link line and whittle it back to the minimum.


> Josh
> 
> 
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-- 
-ericP