Re: gcc linking and address of template function

["Brian Budge" <brian.budge@gmail.com>]

Hi Perry -

Here are the errors I'm getting:

test/tester.o: In function
`STLocate2<OpenMesh::PolyMesh_ArrayKernelT<OpenMesh::DefaultTraits>,
double, CCStencil, BSphere<double, 2, OpenMesh::FaceHandle>
>::operator()(BSphere<double, 2, OpenMesh::FaceHandle> const&, bool)':
tester.cc:(.gnu.linkonce.t._ZN9STLocate2IN8OpenMesh21PolyMesh_ArrayKernelTINS0_13DefaultTraitsEEEd22CCStencil7BSphereIdLi2ENS0_10FaceHandleEEEclERKS7_b+0x30e):
undefined reference to `ll_uv_f(gsl_vector const*, void*,
gsl_vector*)'
tester.cc:(.gnu.linkonce.t._ZN9STLocate2IN8OpenMesh21PolyMesh_ArrayKernelTINS0_13DefaultTraitsEEEd22CCStencil7BSphereIdLi2ENS0_10FaceHandleEEEclERKS7_b+0x318):
undefined reference to `ll_uv_df(gsl_vector const*, void*,
gsl_matrix*)'
tester.cc:(.gnu.linkonce.t._ZN9STLocate2IN8OpenMesh21PolyMesh_ArrayKernelTINS0_13DefaultTraitsEEEd22CCStencil7BSphereIdLi2ENS0_10FaceHandleEEEclERKS7_b+0x322):
undefined reference to `ll_uv_fdf(gsl_vector const*, void*,
gsl_vector*, gsl_matrix*)'

Note I've only instantiated my classes with the template type =
CCStencil, so there aren't any errors regarding BSStencil.

When I do an nm on one of my .o files (which is on the link line), I get this:
00000000 W _Z7ll_uv_fI21BSStencilEiPK10gsl_vectorPvPS1_
00000000 W _Z7ll_uv_fI22CCStencilEiPK10gsl_vectorPvPS1_
00000000 W _Z8ll_uv_dfI21BSStencilEiPK10gsl_vectorPvP10gsl_matrix
00000000 W _Z8ll_uv_dfI22CCStencilEiPK10gsl_vectorPvP10gsl_matrix
00000000 W _Z9ll_uv_fdfI21BSStencilEiPK10gsl_vectorPvPS1_P10gsl_matrix
00000000 W _Z9ll_uv_fdfI22CCStencilEiPK10gsl_vectorPvPS1_P10gsl_matrix

nm --demangle gives:

00000000 W int ll_uv_f<BSStencil>(gsl_vector const*, void*, gsl_vector*)
00000000 W int ll_uv_f<CCStencil>(gsl_vector const*, void*, gsl_vector*)
00000000 W int ll_uv_df<BSStencil>(gsl_vector const*, void*, gsl_matrix*)
00000000 W int ll_uv_df<CCStencil>(gsl_vector const*, void*, gsl_matrix*)
00000000 W int ll_uv_fdf<BSStencil>(gsl_vector const*, void*,
gsl_vector*, gsl_matrix*)
00000000 W int ll_uv_fdf<CCStencil>(gsl_vector const*, void*,
gsl_vector*, gsl_matrix*)


Thanks!
  Brian


On 5/7/06, Perry Smith <pedz@easesoftware.com> wrote:
> I may be right in front of my face but I don't see it.  Can you send
> a couple lines of what the link's error messages are like?
>
> On May 5, 2006, at 4:29 PM, Brian Budge wrote:
>
> > Hi all -
> >
> > I'm attempting to use gsl (gnu scientific library) from my C++
> > program.  gsl is a C program, and I need to pass function pointers to
> > gsl to make it do it's magic on my data.
> >
> > The problem I'm having stems from the fact that I need my functions to
> > be template functions.
> >
> > I can get everything to compile, but I can't get it to link.
> >
> > The gist is like this:
> >
> > template<class Stencil>
> > int ll_uv_f(const gsl_vector *x, void *params, gsl_vector *f){
> >    LL_uv_data<Stencil> *lld = static_cast< LL_uv_data<Stencil>* >
> > (params);
> >    const real a = gsl_vector_get(x,0);
> >    const real b = gsl_vector_get(x,1);
> >    Vec v = lld->ll->eval(a, b) - lld->pt;
> >    for(int i = 0; i < 2; ++i){
> >        gsl_vector_set(f, i, v[i]);
> >    }
> >    return GSL_SUCCESS;
> > }
> >
> > template<class Stencil>
> > int ll_uv_df(const gsl_vector *x, void *params, gsl_matrix *J){...}
> >
> > template<class Stencil>
> > int ll_uv_fdf(const gsl_vector *x, void *params, gsl_vector *f,
> > gsl_matrix *J){...}
> >
> > The calling function then contains the code:
> >
> > LL_uv_data<BaseStencil> dat(Vec(u,v), this);
> > gsl_multiroot_function_fdf f = {ll_uv_f<BaseStencil>,
> >                                           ll_uv_df<BaseStencil>,
> >                                           ll_uv_fdf<BaseStencil>,
> >                                           2, &dat};
> >
> > I also explicitly instantiate the template functions for several
> > instances in a .cc file:
> >
> > //explicit instantiation of template functions
> > template int ll_uv_fdf<CCStencil>(const gsl_vector *x, void *params,
> > gsl_vector *f, gsl_matrix *J);
> > template int ll_uv_fdf<BSStencil>(const gsl_vector *x, void *params,
> > gsl_vector *f, gsl_matrix *J);
> > .
> > .
> > .
> > template int ll_uv_df<CCStencil>(const gsl_vector *x, void *params,
> > gsl_matrix *J);
> > template int ll_uv_df<BSStencil>(const gsl_vector *x, void *params,
> > gsl_matrix *J);
> > .
> > .
> > .
> > template int ll_uv_f<CCStencil>(const gsl_vector *x, void *params,
> > gsl_vector *f);
> > template int ll_uv_f<BSStencil>(const gsl_vector *x, void *params,
> > gsl_vector *f);
> > .
> > .
> > .
> >
> > The program compiles fine, and the functions int ll_uv_*() are found
> > by the nm utility to be in a .o file.
> >
> > The program still won't link.  Anyone have any ideas?  Is this
> > something I'm doing wrong?  The gcc version is 3.4.5-r1, and this is
> > on a xeon box running linux.
> >
> > Thanks,
> >  Brian
> >
>
>