Can't link type parameters to fields in generic classes for TASTY reflect

[yilinwei]

Minimized example

case class Foo[A](a: A)

object Test {

  import scala.quoted._

  def impl[T](t: T)(using qctx: QuoteContext, tt: Type[T]): Expr[Any] = {

    import qctx.tasty._
    import util._

    val symbol = typeOf[Foo[String]].typeSymbol.field("a")
    val ValDef(field, typeTree, _) = symbol.tree
    qctx.error(s"${typeTree}")

    '{???}
  }


  inline def apply[T](inline t: T) = ${ Test.impl('t )}

}

object Run {
  def test(): Unit = {
    Test[Foo[String]](Foo("moo"))
  }
}

Output

[error] 7 |    Test[Foo[String]](Foo("moo"))
[error]   |    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[error]   |TypeTree[TypeRef(ThisType(TypeRef(ThisType(TypeRef(NoPrefix,module class <empty>)),class Foo)),type A)]
[error]   | This location contains code that was inlined from Run.scala:7

Expectation

typeOf[Foo[String], has the following type constructor information. I can't work out a way of linking the applied type to type A. This is problematic in generic methods such as copy because it's hard to work out what arguments should be passed in TypeApply when using TASTY reflect and in which order. I expect there's some part of the API I'm missing which would allow me to map A to String in this case.

[error]   |AppliedType(TypeRef(ThisType(TypeRef(ThisType(TypeRef(NoPrefix,module class <root>)),module class <empty>)),Foo),List(TypeRef(TermRef(ThisType(TypeRef(NoPrefix,module class java)),module lang),String)))
[error]   | This location contains code that was inlined from Run.scala:7