Fix unapply of ShouldTransformTree

Author: felixmulder

compiler/src/dotty/tools/dotc/transform/SpecializeFunction1.scala

@@ -46,6 +46,7 @@ class SpecializeFunction1 extends MiniPhaseTransform with DenotTransformer {
     */
   def transform(ref: SingleDenotation)(implicit ctx: Context) = ref match {
     case cref @ ShouldTransformDenot(targets) => {
+      ctx.echo(s"Transforming denot $cref...")
       val specializedSymbols: Map[Symbol, (Symbol, Symbol)] = (for (SpecializationTarget(target, args, ret, original) <- targets) yield {
         val arity = args.length
         val specializedParent = ctx.getClassIfDefined {
@@ -171,12 +172,10 @@ class SpecializeFunction1 extends MiniPhaseTransform with DenotTransformer {
 
   private object ShouldTransformTree {
     def unapply(tree: Template)(implicit ctx: Context): Option[Seq[(Tree, SpecializationTarget)]] = {
-      val targets = getSpecTargets(tree.tpe)
-      val treeToTargets =
-        tree.parents.filter(t => defn.isFunctionClass(t.symbol)).map { tree =>
-          targets.find(_.original eq tree.symbol).map(target => (tree, target))
-        }
-        .flatten
+      val treeToTargets = tree.parents
+        .map(t => (t, getSpecTargets(t.tpe)))
+        .filter(_._2.nonEmpty)
+        .map { case (t, xs) => (t, xs.head) }
 
       if (treeToTargets.isEmpty) None else Some(treeToTargets)
     }