Workaround non-idempotency of typing pattern matching anonymous functions.

 - Undo the transformation that takes place in Typers to
   leave us with Match(EmptyTree, cases).
 - Make sure we don't descend into the cases of such a
   tree when peforming the async transform

1 files changed, 2 insertions, 1 deletions

diff --git a/src/main/scala/scala/async/Async.scala b/src/main/scala/scala/async/Async.scala
index 1961e69..2ff0f07 100644
--- a/src/main/scala/scala/async/Async.scala
+++ b/src/main/scala/scala/async/Async.scala
@@ -78,7 +78,8 @@ abstract class AsyncBase {
     //  - if/match only used in statement position.
     val anfTree: Block = {
       val anf = AnfTransform[c.type](c)
-      val stats1 :+ expr1 = anf(body.tree)
+      val restored = utils.restorePatternMatchingFunctions(body.tree)
+      val stats1 :+ expr1 = anf(restored)
       val block = Block(stats1, expr1)
       c.typeCheck(block).asInstanceOf[Block]
     }