When the scope (the file) ends, the last reference to $foo is released, so it's detroyed.

If any function (incl END) referenced $foo, it would capture the variable. In that case, there would still be a reference to the variable at the end of the file scope, so the variable will survive until global destruction.

use strict;
use warnings;

sub Foo::DESTROY{ print "object $_[0]->[0] destroyed\n"; }

my $foo  = bless [ 'foo' ], 'Foo';  # notice 'my'
our $bar = bless [ 'bar' ], 'Foo';  # notice 'our'

END {
    $foo;
    print "END block executed\n";
}
[download]

should produce

END block executed
object foo destroyed
object bar destroyed
[download]