package EvilHash;
use overload '%{}' => \&conditional_reference;
sub conditional_reference {
    my @call = caller(1);
    if ( @call && $call[3] eq '(eval)' ) {
        die 'no testing';
    }
    return { a => 1 };
}
sub new { bless [], shift }

package main;
my $evil_hash = EvilHash->new();
ok( ref $evil_hash, '$evil_hash is a reference' );
is( reftype $evil_hash, reftype [],
    '$evil_hash is an array reference' );
# Useless use of a variable in void context
ok( ! eval { %{$evil_hash}; 1 },
    '$evil_hash will not be dereferenced inside eval' );
ok( scalar %{$evil_hash},
    '$evil_hash allows dereference ouside eval' );