proto auto-generation for methods, so it's now possible to write mult…

…i methods again without having to write an explicit proto. Re-uses generic instantiation get get the invocant type on the auto-gen'd proto right...a cunning use I'd not thought of for it. :-)

src/Perl6/Metamodel/BOOTSTRAP.pm

@@ -352,7 +352,12 @@ Code.HOW.add_method(Code, 'name', sub ($self) {
         ~pir::getattribute__PPPs(pir::perl6_decontainerize__PP($self),
             Code, '$!do')
     });
-
+Code.HOW.add_method(Code, '!set_name', sub ($self, $name) {
+        pir::assign__vPS(
+            pir::getattribute__PPPs(pir::perl6_decontainerize__PP($self), Code, '$!do'),
+            $name)
+    });
+
 # Need to actually run the code block. Also need this available before we finish
 # up the stub.
 Code.HOW.add_parrot_vtable_handler_mapping(Code, 'invoke', '$!do');

src/Perl6/Metamodel/MultiMethodContainer.pm

@@ -2,6 +2,14 @@ role Perl6::Metamodel::MultiMethodContainer {
     # Set of multi-methods to incorporate. Not just the method handles;
     # each is a hash containing keys name and body.
     has @!multi_methods_to_incorporate;
+
+    # The proto we'll clone.
+    my $autogen_proto;
+
+    # Sets the proto we'll auto-gen based on.
+    method set_autogen_proto($proto) {
+        $autogen_proto := $proto
+    }
 
     # We can't incorporate multis right away as we don't know all parents
     # yet, maybe, which influences whether we even can have multis, need to
@@ -80,9 +88,12 @@ role Perl6::Metamodel::MultiMethodContainer {
                     $j := $j + 1;
                 }
                 unless $found {
-                    pir::die("Could not find a proto for multi '" ~ $name ~
-                        "' in package '" ~ self.name($obj) ~
-                        "', and proto generation is not yet implemented");
+                    # No proto found, so we'll generate one here.
+                    my $proto := $autogen_proto.instantiate_generic(
+                        hash( T => $obj ));
+                    $proto."!set_name"($name);
+                    $proto.add_dispatchee($code);
+                    self.add_method($obj, $name, $proto);
                 }
             }
             $i := $i + 1;

src/core/stubs.pm

@@ -23,4 +23,12 @@ sub DYNAMIC(\$name) is rw {
     $x
 }
 
+# Set up ClassHOW's auto-gen proto (nested scope so it won't
+# actually appear in the setting).
+{
+    my class Dummy {
+        our proto method AUTOGEN(::T $: |$) { * }
+    }
+    Dummy.HOW.set_autogen_proto(&Dummy::AUTOGEN);
+}