perl -MFile::Find -le '
    for my $inc (@INC) {
        find(sub {
                   return unless /pm$/;
                   $_ = $File::Find::name;
                   s{^\Q$inc/}{};
                   s{/}{::}g;
                   s{.pm$}{};
                   print
                 },
                 $inc);
    }'