package X;

sub x { 1 }

package X::Y;
use base 'X';

1;

##</code><code>##

$ perl -cw X.pm
Subroutine x redefined at /data/web/lib/X.pm line 3.
X.pm syntax OK

##</code><code>##

package X;
$VERSION = 0.01;
sub x { 1 }

package X::Y;
use base 'X';

1;