The approximation of path-dependent classes in TypeAssigner#avoid is too imprecise

[smarter]

class Outer {
  class Inner
}
object Test {
  def test = {
    // works
    val a: Outer#Inner = {
      val o = new Outer
      new o.Inner: Outer#Inner
    }


    // error: type mismatch:
    // found   : Object
    // required: Outer#Inner
    //    val b: Outer#Inner = {
    //                         ^
    val b: Outer#Inner = {
      val o = new Outer
      new o.Inner
    }
  }
}

The approximation is done in TypeAssigner#avoid:

        case tp: TypeRef if (forbidden contains tp.symbol) || toAvoid(tp.prefix) =>
           //...

Instead of approximating the class o.Inner by its parent class Object, it should approximate it by its supertypeOuter#Inner.