Ensure unique names for definitions in the async block.

 - transform the provided tree using reflect.internal.Symbols#Symbol.name_=
   and treeCopy.{Ident, Select}.
    - not sure if this is possible within the public Symbol API.
 - move checking for unsupported nested module/class to AsyncAnalysis.
 - make block merging selective (only do so if there are nested await calls.)

1 files changed, 6 insertions, 2 deletions

diff --git a/src/main/scala/scala/async/Async.scala b/src/main/scala/scala/async/Async.scala
index 546445a..0b77c78 100644
--- a/src/main/scala/scala/async/Async.scala
+++ b/src/main/scala/scala/async/Async.scala
@@ -79,8 +79,12 @@ abstract class AsyncBase {
     //  - if/match only used in statement position.
     val anfTree: Block = {
       val transform = new AnfTransform[c.type](c)
-      val stats1 :+ expr1 = transform.anf.transformToList(body.tree)
-      c.typeCheck(Block(stats1, expr1)).asInstanceOf[Block]
+      val unique = transform.uniqueNames(body.tree)
+      val stats1 :+ expr1 = transform.anf.transformToList(unique)
+
+      val block = Block(stats1, expr1)
+
+      c.typeCheck(block).asInstanceOf[Block]
     }
 
     // Analyze the block to find locals that will be accessed from multiple