Fix nqp::setinvokespec on parrot. Add a test for it.

src/vm/parrot/ops/nqp.ops

@@ -2374,6 +2374,7 @@ inline op set_invocation_spec(invar PMC, invar PMC, in STR, invar PMC) :base_cor
         InvocationSpec *new_spec = mem_allocate_zeroed_typed(InvocationSpec);
         new_spec->value_slot.class_handle = $2;
         new_spec->value_slot.attr_name    = $3;
+        new_spec->value_slot.hint    = NO_HINT;
         new_spec->invocation_handler      = $4;
 
         /* Free any existing spec and put the new one in place. */

t/nqp/70-invokespec.t

@@ -0,0 +1,27 @@
+plan(2);
+class Foo {
+    has $!here_we_keep_the_code_ref;
+    has $!other_place_we_could_keep_the_code_ref_in;
+    method set_code_ref($code_ref) {
+        $!here_we_keep_the_code_ref := $code_ref;
+    }
+    method set_code_ref_differently($code_ref) {
+        $!other_place_we_could_keep_the_code_ref_in := $code_ref;
+    }
+}
+class Bar is Foo {
+}
+nqp::setinvokespec(Foo,Foo,'$!here_we_keep_the_code_ref',nqp::null());
+
+nqp::setinvokespec(Bar,Foo,'$!other_place_we_could_keep_the_code_ref_in',nqp::null());
+
+my $foo := Foo.new();
+$foo.set_code_ref(sub() {123});
+$foo.set_code_ref_differently(sub() {456});
+ok($foo() == 123,"basic setinvokespec");
+
+my $bar := Bar.new();
+$bar.set_code_ref(sub() {1001});
+$bar.set_code_ref_differently(sub() {1002});
+ok($bar() == 1002,"setinvokespec with a attribute in a subclass");
+