Fix #1865: Compute outer path at right phase

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

@@ -276,7 +276,7 @@ object ExplicitOuter {
           if (tpe.prefix eq NoPrefix) cls.owner.enclosingClass.thisType
           else tpe.prefix
         case _ =>
-          outerPrefix(tpe.underlying)
+          outerPrefix(tpe.underlying(ctx.withPhaseNoLater(ctx.erasurePhase)))
       }
     case tpe: TypeProxy =>
       outerPrefix(tpe.underlying)
@@ -339,6 +339,7 @@ object ExplicitOuter {
         val cls = fun.symbol.owner.asClass
         def outerArg(receiver: Tree): Tree = receiver match {
           case New(_) | Super(_, _) =>
+            println(i"outerarg: ${receiver.tpe} --> ${outerPrefix(receiver.tpe)} at ${ctx.phase}")
             singleton(fixThis(outerPrefix(receiver.tpe)))
           case This(_) =>
             ref(outerParamAccessor(cls)) // will be rewired to outer argument of secondary constructor in phase Constructors

tests/pending/pos/i1865.scala

@@ -0,0 +1,24 @@
+class AbsCell {
+  type T = Node
+  class Node
+}
+
+object Test {
+  def test: Unit = {
+    val cell = new AbsCell
+    new cell.T
+  }
+}
+
+class AbsCell2 {
+  type T = Node
+  val value: T = value
+  def set(x: T): Unit = {}
+  class Node
+}
+object init {
+  def main = {
+    val cell = new AbsCell2 { val init = new Node }
+    cell set (new cell.T)
+  }
+}