dotty.tools.dotc.transform.RestoreScopes.scala Maven / Gradle / Ivy

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package dotty.tools.dotc
package transform

import core.*
import DenotTransformers.IdentityDenotTransformer
import Contexts.*
import Symbols.*
import Scopes.*
import MegaPhase.MiniPhase

/** The preceding lambda lift and flatten phases move symbols to different scopes
 *  and rename them. This miniphase cleans up afterwards and makes sure that all
 *  class scopes contain the symbols defined in them.
 */
class RestoreScopes extends MiniPhase with IdentityDenotTransformer { thisPhase =>
  import ast.tpd.*

  override def phaseName: String = RestoreScopes.name

  override def description: String = RestoreScopes.description

  override def changesMembers: Boolean = true // the phase affects scopes, applying tree transformations of previous phases

  /* Note: We need to wait until we see a package definition because
   * DropEmptyConstructors changes template members when analyzing the
   * enclosing package definitions. So by the time RestoreScopes gets to
   * see a typedef or template, it still might be changed by DropEmptyConstructors.
   */
  override def transformPackageDef(pdef: PackageDef)(using Context): PackageDef = {
    pdef.stats.foreach(restoreScope)
    pdef
  }

  private def restoreScope(tree: Tree)(using Context) = tree match {
    case TypeDef(_, impl: Template) =>
      val restoredDecls = newScope
      for (stat <- impl.constr :: impl.body)
        if (stat.isInstanceOf[MemberDef] && stat.symbol.exists)
          restoredDecls.enter(stat.symbol)
      // Enter class in enclosing package scope, in case it was an inner class before flatten.
      // For top-level classes this does nothing.
      val cls = tree.symbol.asClass
      val pkg = cls.owner.asClass

      pkg.enter(cls)
      tree.symbol.copySymDenotation(
        info =  cls.classInfo.derivedClassInfo(
          decls = restoredDecls: Scope)).installAfter(thisPhase)
      tree
    case tree => tree
  }
}

object RestoreScopes:
  val name: String = "restoreScopes"
  val description: String = "repair rendered invalid scopes"