Don't force LazyRefs when computing DepStatus

Fixes #14771

Author: odersky

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

@@ -3635,6 +3635,9 @@ object Types {
             if ann.refersToParamOf(thisLambdaType) then TrueDeps
             else compute(status, parent, theAcc)
           case _: ThisType | _: BoundType | NoPrefix => status
+          case t: LazyRef =>
+            if t.completed then compute(status, t.ref, theAcc)
+            else Unknown
           case _ =>
             (if theAcc != null then theAcc else DepAcc()).foldOver(status, tp)
       compute(initial, tp, null)

tests/pos/i14771.scala

@@ -0,0 +1,13 @@
+trait Layouts:
+  type Layout <: {
+    def withName(name: String): Layout
+  }
+  val l: Layout
+
+val ls = new Layouts:
+  class Layout17:
+    def withName(name: String): Layout17 = this
+  type Layout = Layout17
+  val l = Layout17()
+
+def test = ls.l