I think the issue is that Lingua::StanfordCoreNLP has the java code in the __DATA__ section of the PM file

Doesn't seem to be an issue with Inline::C - though, faik, that might be quite irrelevant wrt Inline::Java.

With a site/lib/FOO/Soldier.pm that contains:

package FOO::Soldier;

use warnings;
use strict;

use Inline 'C';

1;

__DATA__
__C__
    
typedef struct {
  char* name;
  char* rank;
  long  serial;
  } Soldier;
 

   
SV* new(char* class, char* name, char* rank, long serial) {
    Soldier* soldier;
    SV*      obj_ref = newSViv(0);
    SV*      obj = newSVrv(obj_ref, class);

    New(42, soldier, 1, Soldier);

    soldier->name = savepv(name);
    soldier->rank = savepv(rank);
    soldier->serial = serial;
        
    sv_setiv(obj, (IV)soldier);
    SvREADONLY_on(obj);
    return obj_ref;
}
    
char* get_name(SV* obj) {
      return ((Soldier*)SvIV(SvRV(obj)))->name;
}
    
char* get_rank(SV* obj) {
      return ((Soldier*)SvIV(SvRV(obj)))->rank;
}
    
long get_serial(SV* obj) {
     return ((Soldier*)SvIV(SvRV(obj)))->serial;
}


void DESTROY(SV* obj) {
     printf("Destroy called\n");
     Soldier* soldier = (Soldier*)SvIV(SvRV(obj));
     Safefree(soldier->name);
     Safefree(soldier->rank);
     Safefree(soldier);
}
[download]

I can run the following script without any trouble:

package MyPackage;
use warnings;
use strict;

use FOO::Soldier;

my $obj1 = FOO::Soldier->new('Benjamin', 'Private', 11111);
my $obj2 = FOO::Soldier->new('Sanders', 'Colonel', 22222);
my $obj3 = FOO::Soldier->new('Matt', 'Sergeant', 33333);
    
for my $obj ($obj1, $obj2, $obj3) {
    print  $obj->get_serial, ") ", 
           $obj->get_name, " is a ", 
           $obj->get_rank, "\n";
}
[download]

which outputs (as expected):

11111) Benjamin is a Private
22222) Sanders is a Colonel
33333) Matt is a Sergeant
Destroy called
Destroy called
Destroy called
[download]

Good luck with it!

Cheers,
Rob