Make nqp::istype also work for roles that are part of an ancestor.

Author: pmurias

src/how/NQPClassHOW.nqp

@@ -421,8 +421,16 @@ knowhow NQPClassHOW {
 
     method publish_type_cache($obj) {
         my @tc;
-        for @!mro { nqp::push(@tc, $_); }
-        for @!done { nqp::push(@tc, $_); }
+
+        for self.mro($obj) {
+            nqp::push(@tc, $_);
+            if nqp::can($_.HOW, 'role_typecheck_list') {
+                for $_.HOW.role_typecheck_list($_) {
+                    nqp::push(@tc, $_);
+                }
+            }
+        }
+
         nqp::settypecache($obj, @tc)
     }
 
@@ -543,6 +551,10 @@ knowhow NQPClassHOW {
         @!roles
     }
 
+    method role_typecheck_list($obj) {
+        @!done;
+    }
+
     method methods($obj, :$local = 0) {
         if $local {
             @!method_order

t/nqp/056-role.t

@@ -1,4 +1,4 @@
-plan(13);
+plan(15);
 
 role R1 {
     has $!a;
@@ -38,3 +38,12 @@ ok(!C3.HOW.does(C3, R1));
 ok(C3.HOW.does(C3, R3));
 ok(C3.HOW.does(C3, R4));
 
+role Foo {
+}
+class Parent does Foo {
+}
+class Child is Parent {
+};
+
+ok(nqp::istype(Parent, Foo), 'nqp::istype with a role directly on class');
+ok(nqp::istype(Child, Foo), 'nqp::istype with a role on a parent class');