Fix CyclicError reporting

Author: odersky

compiler/src/dotty/tools/dotc/core/TypeErrors.scala

@@ -86,25 +86,27 @@ object handleRecursive {
   }
 }
 
-class CyclicReference private (val denot: SymDenotation) extends TypeError {
+class CyclicReference private (val denot: SymDenotation)(implicit val ctx: Context) extends TypeError {
+
+  def errorMsg(cx: Context): Message =
+    if (cx.mode is Mode.InferringReturnType) {
+      cx.tree match {
+        case tree: untpd.DefDef if !tree.tpt.typeOpt.exists =>
+          OverloadedOrRecursiveMethodNeedsResultType(tree.name)
+        case tree: untpd.ValDef if !tree.tpt.typeOpt.exists =>
+          RecursiveValueNeedsResultType(tree.name)
+        case _ =>
+          errorMsg(cx.outer)
+      }
+    }
+    else CyclicReferenceInvolving(denot)
+
   override def toMessage(implicit ctx: Context) = {
     val cycleSym = denot.symbol
-    def errorMsg(msg: Message, cx: Context): Message =
-      if (cx.mode is Mode.InferringReturnType) {
-        cx.tree match {
-          case tree: untpd.DefDef if !tree.tpt.typeOpt.exists =>
-            OverloadedOrRecursiveMethodNeedsResultType(tree.name)
-          case tree: untpd.ValDef if !tree.tpt.typeOpt.exists =>
-            RecursiveValueNeedsResultType(tree.name)
-          case _ =>
-            errorMsg(msg, cx.outer)
-        }
-      } else msg
-
     if (cycleSym.is(Implicit, butNot = Method) && cycleSym.owner.isTerm)
       CyclicReferenceInvolvingImplicit(cycleSym)
     else
-      CyclicReferenceInvolving(denot)
+      errorMsg(this.ctx)
   }
 }