Re: [CLN-list] fixing undefined references

27 Mar 2014

      On 03/26/2014 04:50 PM, Richard B. Kreckel wrote:
...
Michael,
On 03/26/2014 06:35 PM, Michael Miller wrote:
...
I've spent 5 hours trying to understand the reason for an undefined
reference, so I'm asking for some help.
The code
--------------------
#include <cstdlib>
#include <gmp.h>
#include <cln/cln.h>
using namespace std;
using namespace cln;
const cl_univpoly_complex_ring CZ = find_univpoly_ring(cl_C_ring);
struct parameter { cl_N z0; cl_UP_N p(); };
int main(void) {
    cl_UP_N q=CZ->create(1);
    q.set_coeff(1, 1);
    q.set_coeff(0, -1);
    q.finalize();
parameter param;
    param.z0=1;
    param.p()=q;
}
--------------------
produces the error message
--------------------
/tmp/ccZPl6fM.o: In function `main':
test.cpp:(.text+0xc6): undefined reference to `parameter::p()'
collect2: error: ld returned 1 exit status
--------------------
What am I doing wrong?
Note: replacing p() with p, which would make more sense to me, generates compiler errors.
The linker is telling you that you are call an undefined member function
p of struct parameter. You declared that member function in line 10 of
your program, call it in line 20, but never defined it.
My bet is that you wanted to declare p as a member variable, not as a
member function, in line 10.
hope this helps
   -richard.
Thanks for your quick response!

Your bet is correct - I do want to declare p as a member variable. 
However, when I try to do this, the code

==================
#include <cstdlib>
#include <gmp.h>
#include <cln/cln.h>

using namespace std;
using namespace cln;

struct parameter { cl_N z0; cl_UP_N p; };

int main(void) {
    parameter param;
}
==================

produces the error messages:

==================
In file included from /usr/include/cln/cln.h:126:0,
                  from test3.cpp:6:
/usr/include/cln/univpoly.h: In constructor ‘cln::cl_UP_N::cl_UP_N()’:
/usr/include/cln/univpoly.h:473:8: error: ‘cln::cl_UP::cl_UP()’ is private
  inline cl_UP::cl_UP ()
         ^
In file included from /usr/include/cln/cln.h:127:0,
                  from test3.cpp:6:
/usr/include/cln/univpoly_complex.h:44:7: error: within this context
  class cl_UP_N : public cl_UP {
        ^
test3.cpp: In constructor ‘parameter::parameter()’:
test3.cpp:11:8: note: synthesized method ‘cln::cl_UP_N::cl_UP_N()’ first 
required here
  struct parameter { cl_N z0; cl_UP_N p; };
         ^
test3.cpp: In function ‘int main()’:
test3.cpp:14:14: note: synthesized method ‘parameter::parameter()’ first 
required here
     parameter param;
======================

What is the compiler trying to tell me?

Thanks,

Michael