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Can't match partial functions after typechecking with quasiquotes #8411

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scabug opened this issue Mar 13, 2014 · 5 comments
Closed

Can't match partial functions after typechecking with quasiquotes #8411

scabug opened this issue Mar 13, 2014 · 5 comments
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@scabug
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@scabug scabug commented Mar 13, 2014

scala> tb.typecheck(q"{ case 1 => 2 }", pt = typeOf[PartialFunction[Int, Int]]) match { case q"{ case 1 => 2 }" => }
scala.MatchError: ({
  @SerialVersionUID(0) final <synthetic> class $anonfun extends scala.runtime.AbstractPartialFunction[Int,Int] with Serializable {
    def <init>(): <$anon: Int => Int> = {
      $anonfun.super.<init>();
      ()
    };
    final override def applyOrElse[A1 <: Int, B1 >: Int](x1: A1, default: A1 => B1): B1 = ((x1.asInstanceOf[Int]: Int): Int @unchecked) match {
      case 1 => 2
      case (defaultCase$ @ _) => default.apply(x1)
    };
    final def isDefinedAt(x1: Int): Boolean = ((x1.asInstanceOf[Int]: Int): Int @unchecked) match {
      case 1 => true
      case (defaultCase$ @ _) => false
    }
  };
  new $anonfun()
}: scala.PartialFunction[Int,Int]) (of class scala.reflect.internal.Trees$Typed)
  ... 32 elided
@scabug
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@scabug scabug commented Mar 13, 2014

Imported From: https://issues.scala-lang.org/browse/SI-8411?orig=1
Reporter: @xeno-by
Affected Versions: 2.11.0-RC1
Blocks #8416

@scabug
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@scabug scabug commented Mar 17, 2014

@densh said (edited on Mar 17, 2014 1:32:59 PM UTC):
Clean fix requires binary incompatible change to reificationSupport :(

densh/scala@2b67909

@scabug
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@scabug scabug commented Mar 17, 2014

@densh said (edited on Mar 17, 2014 1:23:32 PM UTC):
Workaround: use following extractor to match partial functions instead of using native syntax

import universe._, Flag._
object PartialFunction {
  private val AnonFun = TypeName("$anonfun")
  private val ApplyOrElse = TermName("applyOrElse")
  private val DefaultCase = TermName("defaultCase$")
  private val IsDefinedAt = TermName("isDefinedAt")
  def unapply(tree: Tree): Option[List[CaseDef]] = tree match {
    case Match(EmptyTree, cases) => Some(cases)
    case Typed(
           Block(
             List(ClassDef(clsMods, AnonFun, Nil, Template(
               List(abspf: TypeTree, ser: TypeTree), noSelfType, List(
                 DefDef(_, termNames.CONSTRUCTOR, _, _, _, _),
                 DefDef(_, ApplyOrElse, _, _, _,
                   Match(_, cases :+
                     CaseDef(Bind(DefaultCase, Ident(nme.WILDCARD)), _, _))),
                 DefDef(_, IsDefinedAt, _, _, _, _))))),
             Apply(Select(New(Ident(AnonFun)), termNames.CONSTRUCTOR), List())),
           pf: TypeTree)
      if pf.tpe != null && pf.tpe <:< typeOf[scala.PartialFunction[_, _]] &&
         abspf.tpe != null && abspf.tpe <:< typeOf[scala.runtime.AbstractPartialFunction[_, _]] &&
         ser.tpe != null && ser.tpe =:= typeOf[scala.Serializable] &&
         clsMods.hasFlag(FINAL) && clsMods.hasFlag(SYNTHETIC) =>
      Some(cases)
    case _ =>
      None
  }
}

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@scabug scabug commented Mar 22, 2014

@scabug scabug closed this Mar 25, 2014
@scabug scabug added the has PR label Apr 7, 2017
@scabug scabug added this to the 2.11.0-RC4 milestone Apr 7, 2017
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