Symbol.typeMembers can return empty Symbols on union type aliases

[jchyb]

Compiler version

main, 3.3.5, probably any

Minimized code

(minimisation partially stolen from #22472)

@main def Test: Unit = {
  class FooSmall[A, B] { type C; type D }
  class FooLarge[A, B, C] { type D; type E }
  type FooUnion[A, B] = FooSmall[A, B] | FooLarge[A, B, B]

  println(Macro.typeMembers[FooUnion])
}

import scala.quoted.*

object Macro {
  transparent inline def typeMembers[T <: AnyKind]: String = ${ typeMembersImpl[T] }

  def typeMembersImpl[T <: AnyKind: Type](using quotes: Quotes): Expr[String] = {
    import quotes.reflect.*
    Expr(TypeRepr.of[T].typeSymbol.typeMembers.toString)
  }
}

Output

List(val <none>, val <none>, val <none>, val <none>)

Expectation

Return either an empty list, or actually existing Symbols, not sure (probably the second one).