scala.reflect.reify.codegen.GenAnnotationInfos.scala Maven / Gradle / Ivy

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package scala.reflect.reify
package codegen

trait GenAnnotationInfos {
  self: Reifier =>

  import global._

  // usually annotations are reified as their originals from Modifiers
  // however, when reifying free and tough types, we're forced to reify annotation infos as is
  // why is that bad? take a look inside
  def reifyAnnotationInfo(ann: AnnotationInfo): Tree = {
    val reifiedArgs = ann.args map { arg =>
      val saved1 = reifyTreeSymbols
      val saved2 = reifyTreeTypes

      try {
        // one more quirk of reifying annotations
        //
        // when reifying AnnotatedTypes we need to reify all the types and symbols of inner ASTs
        // that's because a lot of logic expects post-typer trees to have non-null tpes
        //
        // Q: reified trees are pre-typer, so there's shouldn't be a problem.
        //    reflective typechecker will fill in missing symbols and types, right?
        // A: actually, no. annotation ASTs live inside AnnotatedTypes,
        //    and insides of the types is the place where typechecker doesn't look.
        state.reifyTreeSymbols = true
        state.reifyTreeTypes = true

        // todo. every AnnotationInfo is an island, entire of itself
        // no regular Traverser or Transformer can reach it
        // hence we need to run its contents through the entire reification pipeline
        // e.g. to apply reshaping or to check metalevels
        reify(arg)
      } finally {
        state.reifyTreeSymbols = saved1
        state.reifyTreeTypes = saved2
      }
    }

    // if you reify originals of anns, you get SO when trying to reify AnnotatedTypes, so screw it - after all, it's not that important
    val Apply(Select(New(tpt), name), args) = annotationToTree(ann)
    val reifiedAtp = mirrorCall(nme.Select, mirrorCall(nme.New, mirrorCall(nme.TypeTree, reifyType(tpt.tpe))), reify(name))
    val reifiedAnnRepr = mirrorCall(nme.Apply, reifiedAtp, reifyList(args))
    mirrorFactoryCall(nme.Annotation, reifiedAnnRepr)
  }
}