`Quotes#TypeTree` with empty bounds type-tests as both `Quotes#TypeTree` and `Quotes#TypeBoundsTree`

[pweisenburger]

Compiler version

3.3.1-RC1-bin-20230216-2507577-NIGHTLY

Minimized code

import scala.quoted.*

inline def test = ${ testImpl }

def testImpl(using Quotes) =
  import quotes.reflect.*

  val tree = TypeTree.of(using TypeBounds.empty.asType)

  tree match
    case _: Inferred => println("Inferred")
    case _ =>

  tree match
    case _: TypeTree => println("TypeTree")
    case _ =>

  tree match
    case _: TypeBoundsTree => println("TypeBoundsTree")
    case _ =>

  '{ () }

Output

When expanding, the macro prints:

TypeTree
TypeBoundsTree

Expectation

According to the documentation, a tree should not be both a TypeTree and TypeBoundsTree since none of them is a subtype of the other. When mapping over such a tree, Quotes#TreeMap runs into an exception.

I suppose, the tree should be either (1) an Inferred (which it is currently not), or (2) a TypeBoundsTree but not a TypeTree or (3) TypeBoundsTree should be a subtype of TypeTree (and be handled accordingly by TreeMap).