use strict;

use Scalar::Util qw(weaken isweak);
my $a = [];

my $r1 = $a;
my $r2 = $a;

weaken $r1;

print "a is weak\n" if isweak $a;
print "r1 is weak\n" if isweak $r1;
print "r2 is weak\n" if isweak $r2;