Fix "not a class" crasher in live variable analysis

Predicate the `asClass` cast with an `isClass` check.

Fixes #63

2 files changed, 30 insertions, 1 deletions

diff --git a/src/main/scala/scala/async/internal/LiveVariables.scala b/src/main/scala/scala/async/internal/LiveVariables.scala
index 6c67e99..7f386c8 100644
--- a/src/main/scala/scala/async/internal/LiveVariables.scala
+++ b/src/main/scala/scala/async/internal/LiveVariables.scala
@@ -55,7 +55,8 @@ trait LiveVariables {
 
     // determine which fields should be live also at the end (will not be nulled out)
     val noNull: Set[Symbol] = liftedSyms.filter { sym =>
-      tpe(sym).typeSymbol.asClass.isPrimitive || liftables.exists { tree =>
+      val typeSym = tpe(sym).typeSymbol
+      (typeSym.isClass && typeSym.asClass.isPrimitive) || liftables.exists { tree =>
         !liftedSyms.contains(tree.symbol) && tree.exists(_.symbol == sym)
       }
     }
diff --git a/src/test/scala/scala/async/run/toughtype/ToughType.scala b/src/test/scala/scala/async/run/toughtype/ToughType.scala
index 6159f7b..458157c 100644
--- a/src/test/scala/scala/async/run/toughtype/ToughType.scala
+++ b/src/test/scala/scala/async/run/toughtype/ToughType.scala
@@ -184,6 +184,34 @@ class ToughTypeSpec {
     }
     Bippy
   }
+
+  @Test
+  def ticket63(): Unit = {
+    import scala.async.Async._
+    import scala.concurrent.{ ExecutionContext, Future }
+
+    object SomeExecutionContext extends ExecutionContext {
+      def reportFailure(t: Throwable): Unit = ???
+      def execute(runnable: Runnable): Unit = ???
+    }
+
+    trait FunDep[W, S, R] {
+      def method(w: W, s: S): Future[R]
+    }
+
+    object FunDep {
+      implicit def `Something to do with List`[W, S, R](implicit funDep: FunDep[W, S, R]) =
+        new FunDep[W, List[S], W] {
+          def method(w: W, l: List[S]) = async {
+            val it = l.iterator
+            while (it.hasNext) {
+              await(funDep.method(w, it.next()))
+            }
+            w
+          }(SomeExecutionContext)
+        }
+    }
+  }
 }
 
 trait A