Am I checking for undef in the wrong way?

I have an issue with an XS module of mine. I lean towards that it is a
bug in threads::shared, but maybe I am doing something wrong?

To show the issue, I have this silly XS routine:

   void
   arraytest(arrayref)
         SV * arrayref
   CODE:
   {
     AV *  av = (AV *) SvRV(arrayref);
     SV ** svp = av_fetch(av, 0, 0);
     SV *  sv  = *svp;
   
     warn ("SvOK = %d\n", SvOK(sv));
     warn ("SvIV = %d\n", SvIV(sv));
     warn ("SvOK = %d\n", SvOK(sv));
   }

The main script runs:

   my $arrayref = [5678];
   arraytest($arrayref);
   my $shared_arrayref : shared = shared_clone($arrayref);
   arraytest($shared_arrayref);

The output is:

   SvOK = 4352
   SvIV = 5678
   SvOK = 4352
   SvOK = 0
   SvIV = 5678
   SvOK = 4096

That is, when I send in a regular array reference, results are as
expected. But when the reference is a shared object, SvOK first 
returns 0. When I retrieve the value with SvIV I get the correct
value nevertheless, and next time SvOK returns a true value!

Am I doing somethinug wrong? Or should I file a bug for threads::shared?

If it is a bug, any suggestion for a workaround? In the real module, the
value can be of any type, so SvIV does not seem like a good idea.

This happens on Win32 with ActivePerl builds 1005. I attach my test
module and test script (which also shows the same thing happens with a
hash reference.)



-- 
Erland Sommarskog, Stockholm, [email protected]

use strict;

use ExtUtils::MakeMaker;


WriteMakefile(
    'NAME'         => 'TestInSummertime',
    'OBJECT'       => 'TestInSummertime.obj',
    'CCFLAGS'      => '-MT',
    'LIBS'         => [":nosearch :nodefault delayimp.lib kernel32.lib user32.lib ole32.lib oleaut32.lib uuid.lib libcmt.lib"],
    'VERSION_FROM' => 'TestInSummertime.pm',
    'XS'           => { 'TestInSummertime.xs' => 'TestInSummertime.cpp' }
);

sub MY::xs_c {
    '
.xs.cpp:
   $(PERL) -I$(PERL_ARCHLIB) -I$(PERL_LIB) $(XSUBPP) $(XSPROTOARG) $(XSUBPPARGS) $*.xs >xstmp.c && $(MV) xstmp.c $*.cpp
';
}

use strict;
use threads;
use threads::shared;

use TestInSummertime;

my $arrayref = [5678];
my $hashref = {Key => 4711};

arraytest($arrayref);
hashtest($hashref);

my $shared_arrayref : shared = shared_clone($arrayref);
my $shared_hashref  : shared = shared_clone($hashref);

arraytest($shared_arrayref);
hashtest($shared_hashref);

package TestInSummertime;

use strict;
use Exporter;
use DynaLoader;

use vars qw(@ISA @EXPORT $VERSION);

$VERSION = '1.000';

@ISA = qw(Exporter DynaLoader);

bootstrap TestInSummertime;

@EXPORT = qw(arraytest hashtest);


1;