What are you talking about?

#!/usr/local/bin/perl -l -w

use strict;
use Data::Dumper;

sub x {
 ();
}

my @x = x();

my $num = @x;
print $num;
for (@x) {
 print;
}

print Dumper (\@x, $num);

#output:
0
$VAR1 = [];
$VAR2 = 0;
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Update: You gave Dumper() a reference to an array with an element which was a reference to an empty array.