--- make $x alias of $y
do {
  my $a = \*main::x;
  *{$a} = \"Y";
  *{$a} = [];
  $a;
}

$x= 'Y'
$x= 'YY'
--- make *x alias of *z
do {
  my $a = \*main::z;
  *{$a} = [];
  $a;
}

$x= 'Z'
@x= qw/Z ZZ ZZZ/