#if GMP_HAS_MAGICEXT
        && mg->mg_virtual == &vtbl_gmp
#endif

##</code><code>##

#if GMP_HAS_MAGICEXT
        && mg->mg_virtual != &vtbl_gmp
#endif

##</code><code>##

use warnings;
use Math::BigInt lib => 'GMP';

use Inline C  => Config =>
 LIBS => '-lgmp',
 USING => 'ParseRegExp',
 BUILD_NOISY => 1;

use Inline C => <<'EOC';

#include <gmp.h>

#ifndef PERL_UNUSED_ARG
#  define PERL_UNUSED_ARG(x) ((void)x)
#endif

#ifndef gv_stashpvs
#  define gv_stashpvs(name, create) gv_stashpvn(name, sizeof(name) - 1, create)
#endif

#ifndef PERL_MAGIC_ext
#  define PERL_MAGIC_ext '~'
#endif

#if defined(USE_ITHREADS) && defined(MGf_DUP)
#  define GMP_THREADSAFE 1
#else
#  define GMP_THREADSAFE 0
#endif

#ifdef sv_magicext
#  define GMP_HAS_MAGICEXT 1
#else
#  define GMP_HAS_MAGICEXT 0
#endif

#define NEW_GMP_MPZ_T      RETVAL = malloc (sizeof(mpz_t));
#define NEW_GMP_MPZ_T_INIT RETVAL = malloc (sizeof(mpz_t)); mpz_init(*RETVAL);
#define GMP_GET_ARG_0      TEMP = mpz_from_sv(x);
#define GMP_GET_ARG_1      TEMP_1 = mpz_from_sv(y);
#define GMP_GET_ARGS_0_1   GMP_GET_ARG_0; GMP_GET_ARG_1;

#if GMP_THREADSAFE
STATIC int
dup_gmp_mpz (pTHX_ MAGIC *mg, CLONE_PARAMS *params)
{
  mpz_t *RETVAL;
  PERL_UNUSED_ARG(params);
  NEW_GMP_MPZ_T;
  mpz_init_set(*RETVAL, *((mpz_t *)mg->mg_ptr));
  mg->mg_ptr = (char *)RETVAL;
  return 0;
}
#endif

#if GMP_HAS_MAGICEXT
STATIC MGVTBL vtbl_gmp = {
  NULL, /* get */
  NULL, /* set */
  NULL, /* len */
  NULL, /* clear */
  NULL, /* free */
# ifdef MGf_COPY
  NULL, /* copy */
# endif
# ifdef MGf_DUP
#  if GMP_THREADSAFE
  dup_gmp_mpz,
#  else
  NULL, /* dup */
#  endif
# endif
# ifdef MGf_LOCAL
  NULL, /* local */
# endif
};
#endif

void magic_status(void){
  printf("GMP_HAS_MAGICEXT: %d\n", GMP_HAS_MAGICEXT);
}

STATIC mpz_t *
 (SV *sv)
{
  MAGIC *mg;

  if (!sv_derived_from(sv, "Math::BigInt::GMP"))
    croak("not of type Math::BigInt::GMP");

  for (mg = SvMAGIC(SvRV(sv)); mg; mg = mg->mg_moremagic) {
    if (mg->mg_type == PERL_MAGIC_ext
#if GMP_HAS_MAGICEXT
        && mg->mg_virtual != &vtbl_gmp
#endif
        ) {
#if GMP_HAS_MAGICEXT
      return (mpz_t *)mg->mg_ptr;
#else
      return INT2PTR(mpz_t *, SvIV((SV *)mg->mg_ptr));
#endif
    }
  }

  return (mpz_t *)NULL;
}

void access_mpz(SV * sv) {
  mpz_t *mpz;

  if (!(mpz = mpz_from_sv_nofail(sv)))
    croak("failed to fetch mpz pointer");

  mpz_out_str(NULL, 10, mpz);
}


EOC

magic_status();

my $x = Math::BigInt->new('-' . ('9876543210123456789' x 4));

access_mpz($x->{value}); # Ignores $x->{sign}

##</code><code>##

GMP_HAS_MAGICEXT: 1
9876543210123456789987654321012345678998765432101234567899876543210123456789

##</code><code>##

GMP_HAS_MAGICEXT: 1
failed to fetch mpz pointer at try.pl line 125.