@b = @a;

##</code><code>##

@b = (); # temporary internal step
@b = @a;

##</code><code>##

use Data::Dumper;

*a = *b;
@b = (1,2);

@b = @b; # perl detects this is assigning into same variable
print Dumper(\@b);

@b = @a ? @a : (); # new assignment

print Dumper(\@a);
print Dumper(\@b);

##</code><code>##

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