AntiAliasing does not update local aliasing information after replacement

[mario-bucev]

The following snippet is incorrectly transformed by AntiAliasing after the marked line, resulting in the snippet being accepted even though it is incorrect.

object AntiAntiAliasing {
  case class Ref(var x: Int)
  case class RefRef(var lhs: Ref, var rhs: Ref)

  def replaceLhs(rr: RefRef, v: Int): Unit = {
    rr.lhs = Ref(v)
  }

  def t3(refref: RefRef): Unit = {
    val lhs = refref.lhs
    val oldLhs = lhs.x
    replaceLhs(refref, 123)
    assert(lhs.x == oldLhs)
    assert(refref.lhs.x == 123)
    refref.lhs.x = 456 // !
    assert(lhs.x == 456) // Incorrect because `lhs` and `refref.lhs` become unrelated after the call to `replaceLhs`
    assert(refref.lhs.x == 456)
  }
}

If we check the tree we have after AntiAliasing, we get (with some cleaning):

var lhs: Ref = refref.lhs
val oldLhs: Int = lhs.x
var res: (Unit, RefRef) = replaceLhs(refref, 123)
refref = RefRef(res._2.lhs, refref.rhs)
assert(lhs.x == oldLhs)
assert(refref.lhs.x == 123)
refref = RefRef(Ref(456), refref.rhs)
lhs = refref.lhs // Incorrect
assert(lhs.x == 456)
assert(refref.lhs.x == 456)

This is due to AntiAliasing not updating the aliasing information of lhs: after the call to replaceLhs, lhs is no longer aliasing refref.lhs.
Note that this is very similar to #1497 but manifesting in a different way.
Will we be able to fix AntiAliasing one day? After all, what is crooked cannot be made straight 😋