I think this will work out ok if .meta.can, when it's looking for wildcarding classes, distinguishes classes that define their own .can from those that don't, and only adds autoloaders to the end of the list that aren't shielded by a corresponding .can method. (The problems Perl 5 has with defining a .can method in a class shouldn't arise in Perl 6, which tries to prefer "next" semantics to "super" semantics. At worst we'll require people to say "next METHOD" at the end of each such .can method definition.)