use strict;

# print RE into variable and examine it...
sub is_ci {
    my $check_re = shift;

    die "$check_re is not a RE" if ref $check_re ne 'Regexp';

    open my $redir , '>', \my $output; 
    print $redir $check_re; 
    close $redir;

    return $output =~ /i.*?\-/; # i before '-' 
}


my $r1 = qr/hello/i;
my $r2 = qr/hello/;

print "true  is " ,  is_ci($r1) ? 'true' : 'false' , " ?\n"; # true
print "false is " ,  is_ci($r2) ? 'true' : 'false' , " ?\n"; # false
print "false is " ,  is_ci(\"nonsense") ? 'true' : 'false' , " ?\n"; # die!