Inspired by a bug I watched kragen track down today, here's a quiz: Without running the program below, describe the output you expect, and explain why.

See How to present spoilers :-) for instructions on how to obscure your response.

Updated to add a bit more challenge: If the comment is removed, does the order change? Why (or why not)? 

package OnDestroy;

sub say {
  my ($class, $msg) = @_;
  bless { msg => $msg }, $class;
}

sub DESTROY {
  my ($self) = @_;
  print $self->{msg}, "\n";
}

package main;
{
  my $one = OnDestroy->say("one");
}

{
  my $two = OnDestroy->say("two");

  sub closure {
    my ($four) = @_;
    my $three = OnDestroy->say("three");
    sub { $two = $four }
  }
}

my $four = closure(OnDestroy->say("four"));

$four->();

# undef $four;

print "five\n";

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In reply to Know Your Garbage -- A Quiz by dws

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