Test.Scala

@WhatAmI
object Test {
  @WhatAmI
  def main(args: Array[String]) = {}

  @WhatAmI
  val hi = ""

  @WhatAmI
  var hello = ""

  @WhatAmI
  object SomeObject {}

  @WhatAmI
  class SomeClass(a:String) {}

  @WhatAmI
  case class SomeCaseClass(a:String) {}

  @WhatAmI
  trait SomeTrait

  @WhatAmI
  sealed trait SomeSealedTrait
}

WhatAmI.scala

import scala.annotation.compileTimeOnly
import scala.meta._

@compileTimeOnly("@WhatAmI not expanded")
class WhatAmI extends scala.annotation.StaticAnnotation {
  inline def apply(defn: Defn) = meta {
    defn match {
      case _:Defn.Def => println("Def")
      case _:Defn.Class => println("Class")
      case _:Defn.Macro => println("Macro")
      case _:Defn.Trait => println("Trait")
      case _:Defn.Type => println("Type")
      case _:Defn.Val => println("Val")
      case _:Defn.Var => println("Var")
      case _:Defn.Object => println("Object")
      case _=> println("Unknown")
    }
    defn
  }
}

1.Compile:
2. Observe that it only prints Object
3. Remove WhatAmI in line 1 of Test.scala
4. Compile
5. Observe that the list of annotations are printed correctly