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, 9 insertions, 3 deletions

diff --git a/src/main/scala/scala/async/internal/TransformUtils.scala b/src/main/scala/scala/async/internal/TransformUtils.scala
index e15ef1b..2999be2 100644
--- a/src/main/scala/scala/async/internal/TransformUtils.scala
+++ b/src/main/scala/scala/async/internal/TransformUtils.scala
@@ -167,8 +167,8 @@ private[async] trait TransformUtils {
 
     val NonFatalClass = rootMirror.staticModule("scala.util.control.NonFatal")
     val ThrowableClass = rootMirror.staticClass("java.lang.Throwable")
-    val Async_async   = asyncBase.asyncMethod(c.universe)(c.macroApplication.symbol).ensuring(_ != NoSymbol)
-    val Async_await   = asyncBase.awaitMethod(c.universe)(c.macroApplication.symbol).ensuring(_ != NoSymbol)
+    lazy val Async_async   = asyncBase.asyncMethod(c.universe)(c.macroApplication.symbol)
+    lazy val Async_await   = asyncBase.awaitMethod(c.universe)(c.macroApplication.symbol)
     val IllegalStateExceptionClass = rootMirror.staticClass("java.lang.IllegalStateException")
   }
 
@@ -190,6 +190,10 @@ private[async] trait TransformUtils {
     val LABEL = 1L << 17 // not in the public reflection API.
     (internal.flags(sym).asInstanceOf[Long] & LABEL) != 0L
   }
+  def isSynth(sym: Symbol): Boolean = {
+    val SYNTHETIC = 1 << 21 // not in the public reflection API.
+    (internal.flags(sym).asInstanceOf[Long] & SYNTHETIC) != 0L
+  }
   def symId(sym: Symbol): Int = {
     val symtab = this.c.universe.asInstanceOf[reflect.internal.SymbolTable]
     sym.asInstanceOf[symtab.Symbol].id
@@ -388,7 +392,7 @@ private[async] trait TransformUtils {
     catch { case _: ScalaReflectionException => NoSymbol }
   }
   final def uncheckedBounds(tp: Type): Type = {
-    if (tp.typeArgs.isEmpty || UncheckedBoundsClass == NoSymbol) tp
+    if ((tp.typeArgs.isEmpty && (tp match { case _: TypeRef => true; case _ => false}))|| UncheckedBoundsClass == NoSymbol) tp
     else withAnnotation(tp, Annotation(UncheckedBoundsClass.asType.toType, Nil, ListMap()))
   }
   // =====================================
@@ -402,6 +406,8 @@ private[async] trait TransformUtils {
    * in search of a sub tree that was decorated with the cached answer.
    */
   final def containsAwaitCached(t: Tree): Tree => Boolean = {
+    if (c.macroApplication.symbol == null) return (t => false)
+
     def treeCannotContainAwait(t: Tree) = t match {
       case _: Ident | _: TypeTree | _: Literal => true
       case _ => isAsync(t)