尝试以下macro

import scala.quoted.*

inline def serialize(x: Any): Unit = ${serializeImpl('x)}

def serializeImpl(x: Expr[Any])(using Quotes): Expr[Unit] = {
  import quotes.reflect.*

  def owners(s: Symbol): List[Symbol] = s :: List.unfold(s)(s1 => Option.when(s1.maybeOwner != Symbol.noSymbol)((s1.maybeOwner, s1.maybeOwner)))

  val symbol = x.asTerm.underlying.symbol
  val rhs = symbol.tree match {
    case ValDef(_, _, Some(rhs)) => rhs
  }

  val traverser = new TreeTraverser {
    override def traverseTree(tree: Tree)(owner: Symbol): Unit = {
      tree match {
        case Ident(name) =>
          val symbol1 = tree.symbol
          val pos1 = symbol1.pos.get
          println(s"identifier: $name, defined inside lambda: ${owners(symbol1).contains(symbol)}, defined in current file: ${pos1.sourceFile == SourceFile.current}")

        case _ =>
      }

      super.traverseTree(tree)(owner)
    }
  }

  traverser.traverseTree(rhs)(rhs.symbol)

  '{()}
}

用法：
x一个一个一个一个x一个一个二个x