Set the type of case bodies to Unit after ANF.

Avoids runtime errors like: "java.lang.Double cannot be cast to scala.runtime.BoxedUnit"

2 files changed, 15 insertions, 1 deletions

diff --git a/src/main/scala/scala/async/internal/AnfTransform.scala b/src/main/scala/scala/async/internal/AnfTransform.scala
index d98aaa3..13218f3 100644
--- a/src/main/scala/scala/async/internal/AnfTransform.scala
+++ b/src/main/scala/scala/async/internal/AnfTransform.scala
@@ -107,7 +107,7 @@ private[async] trait AnfTransform {
                     case b@Block(caseStats, caseExpr) => treeCopy.Block(b, caseStats, typedAssign(caseExpr))
                     case _                            => typedAssign(body)
                   }
-                  treeCopy.CaseDef(cd, pat, guard, newBody).setType(definitions.UnitTpe)
+                  treeCopy.CaseDef(cd, pat, guard, newBody.setType(definitions.UnitTpe)).setType(definitions.UnitTpe)
               }
               val matchWithAssign = treeCopy.Match(tree, scrut, casesWithAssign).setType(definitions.UnitTpe)
               require(matchWithAssign.tpe != null, matchWithAssign)
diff --git a/src/test/scala/scala/async/run/anf/AnfTransformSpec.scala b/src/test/scala/scala/async/run/anf/AnfTransformSpec.scala
index 595ed63..c8cec28 100644
--- a/src/test/scala/scala/async/run/anf/AnfTransformSpec.scala
+++ b/src/test/scala/scala/async/run/anf/AnfTransformSpec.scala
@@ -379,6 +379,20 @@ class AnfTransformSpec {
   }
 
   @Test
+  def caseBodyMustBeTypedAsUnit() {
+    import _root_.scala.async.internal.AsyncId.{async, await}
+    val Up = 1
+    val Down = 2
+    val sign = async {
+      await(1) match {
+        case Up   => 1.0
+        case Down => -1.0
+      }
+    }
+    sign mustBe 1.0
+  }
+
+  @Test
   def awaitInImplicitApply() {
     val tb = mkToolbox(s"-cp ${toolboxClasspath}")
     val tree = tb.typeCheck(tb.parse {