I am attempting to fix some XS code and have reached a point where I'm slightly confused with the output of B::PV. The XS code now does a sv_setsv(sv, 100) (it used to do a sv_setpvn) and the test code is:

use Devel::Peek;
use B qw( svref_2object SVf_IOK SVf_NOK SVf_POK );

sub is_iv {
   my $sv = svref_2object(my $ref = \$_[0]);
   my $flags = $sv->FLAGS;

   my $x = $sv->PV;
  
   if (wantarray) {
       return ($flags & SVf_IOK, $x);
   } else {
       return $flags & SVf_IOK;
   }
}

# code to connect to database here

$sth = $dbh->prepare(q/select a from PERL_DBD_drop_me/);
$sth->execute;
$sth->bind_col(1, \$r, {TYPE => SQL_INTEGER});
$sth->fetch; # this will do a sv_setiv($r, 100)
is($r, 100, "correct value returned SQL_INTEGER") or Dump($r);
my ($iv, $pv) = is_iv($r);
ok($iv, "ivok bind integer") or Dump($r);
ok($pv, "pv not null bind integer") or Dump($r);
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The output is:

not ok 10 - pv not null bind integer
#   Failed test 'pv not null bind integer'
#   at t/sql_type_cast.t line 149.
SV = PVIV(0x9f81420) at 0xa1353f4
  REFCNT = 2
  FLAGS = (PADMY,IOK,pIOK)
  IV = 100
  PV = 0xa23fd88 "100"\0         # <--- should this be set?
  CUR = 3
  LEN = 4
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I am unsure why B::PV returns undef. Could someone explain this? Thanks.