diff.diff

cpan@perlbuild2~/CPANPRC/rakudo (nom)$ gd
diff --git a/src/core/Array.pm b/src/core/Array.pm
index 13f430a..d9b464e 100644
--- a/src/core/Array.pm
+++ b/src/core/Array.pm
@@ -47,7 +47,7 @@ my class Array { # declared in BOOTSTRAP
         }
     }
 
-    method clone { [self] }
+    multi method clone(Array:D:) { [self] }
 
     method iterator(Array:D:) {
 
diff --git a/src/core/Mu.pm b/src/core/Mu.pm
index ca266cf..8a0c2ab 100644
--- a/src/core/Mu.pm
+++ b/src/core/Mu.pm
@@ -622,7 +622,8 @@ my class Mu { # declared in BOOTSTRAP
         SELF.^can($name)
     }
 
-    method clone(*%twiddles) {
+    proto method clone (|) { * }
+    multi method clone(*%twiddles) {
         my $cloned := nqp::clone(self);
         if %twiddles.elems {
             for self.^attributes.flat -> $attr {
cpan@perlbuild2~/CPANPRC/rakudo (nom)$ ./perl6 -e 'Array.clone'
Cannot look up attributes in a Array type object
  in block <unit> at -e line 1

cpan@perlbuild2~/CPANPRC/rakudo (nom)$ ./perl6 -e 'Cool.clone'
cpan@perlbuild2~/CPANPRC/rakudo (nom)$