Also consider type aliases when checking for realizability

Fixes #50.

1 files changed, 16 insertions, 1 deletions

diff --git a/src/dotty/tools/dotc/core/Types.scala b/src/dotty/tools/dotc/core/Types.scala
index db0831ba0..7e8a11e5b 100644
--- a/src/dotty/tools/dotc/core/Types.scala
+++ b/src/dotty/tools/dotc/core/Types.scala
@@ -139,7 +139,7 @@ object Types {
           case _ => false
         }
         isConcrete(tp) &&
-        tp.abstractTypeMembers.forall { m =>
+        tp.nonClassTypeMembers.forall { m =>
           val bounds = m.info.bounds
           bounds.lo <:< bounds.hi
         } ||
@@ -592,6 +592,12 @@ object Types {
           (name, buf) => buf += member(name).asSingleDenotation)
     }
 
+    /** The set of abstract type members of this type. */
+    final def nonClassTypeMembers(implicit ctx: Context): Seq[SingleDenotation] = track("nonClassTypeMembers") {
+      memberDenots(nonClassTypeNameFilter,
+          (name, buf) => buf += member(name).asSingleDenotation)
+    }
+
     /** The set of type members of this type */
     final def typeMembers(implicit ctx: Context): Seq[SingleDenotation] = track("typeMembers") {
       memberDenots(typeNameFilter,
@@ -3387,6 +3393,15 @@ object Types {
       }
   }
 
+  /** A filter for names of abstract types of a given type */
+  object nonClassTypeNameFilter extends NameFilter {
+    def apply(pre: Type, name: Name)(implicit ctx: Context): Boolean =
+      name.isTypeName && {
+        val mbr = pre.member(name)
+        mbr.symbol.isType && !mbr.symbol.isClass
+      }
+  }
+
   /** A filter for names of deferred term definitions of a given type */
   object abstractTermNameFilter extends NameFilter {
     def apply(pre: Type, name: Name)(implicit ctx: Context): Boolean =