test.pl

#!perl
use strict;
use warnings;

{
    package MyRole;
    use Moose::Role;

}
{
    package MyClass;
    use Moose;

    has myrole => (
        is => 'ro',
        isa => 'RoleName',
        default => 'MyRole',
    );
}

my $c2 = MyClass->new;