@a = @b || @c;              # this is wrong
    @a = scalar(@b) || @c;      # really meant this

##</code><code>##

use strict;
use Data::Dumper;

my @a = (1, 2, 3);
my @b = (4, 5, 6);
my @c = @a or @b;  # equivalent to (my @c = @a) or @b;

print Dumper(\@c);

##</code><code>##

$VAR1 = [
          1,
          2,
          3
        ];

##</code><code>##

use strict;
use Data::Dumper;

my @a = (1, 2, 3);
my @b = (4, 5, 6);
my @c = @a or @b;
my @d = (@a or @b);

print Dumper(\@c);
print Dumper(\@d);

##</code><code>##

$VAR1 = [
          1,
          2,
          3
        ];
$VAR1 = [
          3
        ];