ClassMirror.mixin

runtime/vm/class_finalizer.cc

Index: runtime/vm/class_finalizer.cc
diff --git a/runtime/vm/class_finalizer.cc b/runtime/vm/class_finalizer.cc
index cd9bb2bf42f6b7dda41a95cea60a0b9ef9ccc322..84f3d88a9b721d3079901c5a61bce62b762d3015 100644
--- a/runtime/vm/class_finalizer.cc
+++ b/runtime/vm/class_finalizer.cc
@@ -1297,7 +1297,11 @@ void ClassFinalizer::ResolveAndFinalizeMemberTypes(const Class& cls) {
 // interfaces to refer to the respective type parameters of the mixin
 // application class.
 void ClassFinalizer::CloneTypeParameters(const Class& mixapp_class) {
-  ASSERT(mixapp_class.NumTypeParameters() == 0);
+  if (mixapp_class.NumTypeParameters() != 0) {
+    // Mixin applications created by typedef can introduce their own type
+    // paramaters.
+    return;

[regis, 2013/08/20 18:56:37]

I think that returning here is actually correct if the mixapp_class is an alias,
not just if it has no type parameters. Take the following example:
typedef MA = List<int> with Map<int, int>;

There is no need to parameterize MA.
Assumming List<E> and Map<K, V>, we would get MA<E, K, V>, but this is
unnecessary, since mixin sets all type parameters to 'int'.

On the other hand:
typedef MA<K> = List<int> with Map<K, int>;
MA already has one type parameter and nothing needs to change. You can return
too.

In the non-alias case:
class MA<K> extends List<int> with Map<K, int> {}
We create a S&M<E`, K, V>, which is overkill, but correct.
We could optimize this at a later stage an create a simpler S&M<K>.

Bottom line:
You need to detect if the mixapp_class is an alias. One way is to check that its
name does not contain '&'. There may be a more elegant way.

+  }
 
   const AbstractType& super_type =
       AbstractType::Handle(mixapp_class.super_type());