Various fixes to late expansion

  - Detect cross-state symbol references where the RefTree is nested
    in a LabelDef. Failure to do so led to ill-scoped local variable
    references which sometimes manifest as VerifyErrors.
  - Emit a default case in the Match intended to be a tableswitch.
    We have to do this ourselves if we expand after pattern matcher
  - Cleanup generated code to avoid redundant blocks
  - Avoid unnecessary `matchRes` temporary variable for unit-typed
    pattern matches
  - Fix the trace level logging in the ANF transform to restore
    indented output.
  - Emit `{ state = nextState; ... }` rather than
    `try { ... } finally { state = nextState }` in state handlers.
    This simplifies generated code and has the same meaning, as the
    code in the state machine isn't reentrant and can't observe the
    "early" transition of the state.

1 files changed, 3 insertions, 2 deletions

diff --git a/src/main/scala/scala/async/internal/Lifter.scala b/src/main/scala/scala/async/internal/Lifter.scala
index 2998baf..9481f69 100644
--- a/src/main/scala/scala/async/internal/Lifter.scala
+++ b/src/main/scala/scala/async/internal/Lifter.scala
@@ -76,8 +76,9 @@ trait Lifter {
     // are already accounted for.
     val stateIdToDirectlyReferenced: Map[Int, List[Symbol]] = {
       val refs: List[(Int, Symbol)] = asyncStates.flatMap(
-        asyncState => asyncState.stats.filterNot(_.isDef).flatMap(_.collect {
-          case rt: RefTree if symToDefiningState.contains(rt.symbol) => (asyncState.state, rt.symbol)
+        asyncState => asyncState.stats.filterNot(t => t.isDef && !isLabel(t.symbol)).flatMap(_.collect {
+          case rt: RefTree
+            if symToDefiningState.contains(rt.symbol) => (asyncState.state, rt.symbol)
         })
       )
       toMultiMap(refs)