Merge pull request #46 from retronym/topic/pres-compiler-npe

Presentation compiler friendliness

Author: retronym

src/main/scala/scala/async/internal/AsyncBase.scala

@@ -43,20 +43,26 @@ abstract class AsyncBase {
                                  (body: c.Expr[T])
                                  (execContext: c.Expr[futureSystem.ExecContext]): c.Expr[futureSystem.Fut[T]] = {
     import c.universe._
-
     val asyncMacro = AsyncMacro(c, self)
 
+    val isPresentationCompiler = asyncMacro.global.forInteractive
+
     val code = asyncMacro.asyncTransform[T](
       body.tree.asInstanceOf[asyncMacro.global.Tree],
       execContext.tree.asInstanceOf[asyncMacro.global.Tree]
-      )(implicitly[c.WeakTypeTag[T]].asInstanceOf[asyncMacro.global.WeakTypeTag[T]]).asInstanceOf[Tree]
-
-    // Mark range positions for synthetic code as transparent to allow some wiggle room for overlapping ranges
-    for (t <- code)
-      t.pos = t.pos.makeTransparent
+    )(implicitly[c.WeakTypeTag[T]].asInstanceOf[asyncMacro.global.WeakTypeTag[T]]).asInstanceOf[Tree]
 
     AsyncUtils.vprintln(s"async state machine transform expands to:\n ${code}")
-    c.Expr[futureSystem.Fut[T]](code)
+    val result = if (isPresentationCompiler) {
+      asyncMacro.suppressExpansion()
+      c.macroApplication
+    } else {
+      // Mark range positions for synthetic code as transparent to allow some wiggle room for overlapping ranges
+      for (t <- code)
+        t.pos = t.pos.makeTransparent
+      code
+    }
+    c.Expr[futureSystem.Fut[T]](result)
   }
 
   protected[async] def awaitMethod(u: Universe)(asyncMacroSymbol: u.Symbol): u.Symbol = {

src/main/scala/scala/async/internal/AsyncMacro.scala

@@ -32,4 +32,21 @@ private[async] trait AsyncMacro
   lazy val macroPos = macroApplication.pos.makeTransparent
   def atMacroPos(t: global.Tree) = global.atPos(macroPos)(t)
 
+  def suppressExpansion() {
+    // Have your cake : Scala IDE sees original trees and hyperlinking, etc within async blocks "Just Works"
+    // Eat it too     : (domain specific errors like "unsupported use of await"
+    //
+    // TODO roll this idea back into scala/scala
+    def suppress(globalOrAnalzer: Any) = {
+      type Suppress = { def suppressMacroExpansion(a: Object): Object }
+      globalOrAnalzer.asInstanceOf[Suppress].suppressMacroExpansion(macroApplication)
+    }
+    try {
+      suppress(global) // 2.10.x
+    } catch {
+      case _: NoSuchMethodException =>
+        suppress(global.analyzer) // 2.11
+    }
+  }
+
 }

src/main/scala/scala/async/internal/TransformUtils.scala

@@ -203,6 +203,7 @@ private[async] trait TransformUtils {
 
   abstract class MacroTypingTransformer extends TypingTransformer(callSiteTyper.context.unit) {
     currentOwner = callSiteTyper.context.owner
+    curTree = EmptyTree
 
     def currOwner: Symbol = currentOwner