use strict;
use warnings;
use Carp qw(croak);

package Test;

sub croak_test {
    Carp::croak "this is a test";
}

package main;
Test::croak_test;

##</code><code>##

use strict;
use warnings;
use Carp qw(croak);

my $croak = \&croak;

package Test;

sub croak_test {
    $croak->("this is a test");
}

package main;
Test::croak_test;

##</code><code>##

package Test;
*Test::croak = \&main::croak;

##</code><code>##

# package main; is implicit here
use strict;
use warnings;
use Carp qw(croak);

package Test;

sub croak_test {
    ::croak "this is a test";
}

package main;
Test::croak_test;