Wrong owner for quoted pattern bind symbol

[nicolasstucki]

object Test {
  def res(x: quoted.Expr[Int]) given tasty.Reflection: quoted.Expr[Int] = x match {
    case '{ val a: Int = $y; 1} => y
  }
}

fail to Ycheck

exception while typing {
  case val y: scala.quoted.Expr[Int] = x4._1
  return[matchResult1] 
    {
      y:scala.quoted.Expr[Int]
    }
} of class class dotty.tools.dotc.ast.Trees$Block # 1604
...
...
...
*** error while checking tests/pos/quotedPatterns.scala after phase crossCast ***
exception occurred while compiling tests/pos/quotedPatterns.scala
java.lang.AssertionError: assertion failed: bad owner; value y has owner value a, expected was method res
owner chain = value y, value a, method res, object Test, package <empty>, package <root>, ctxOwners = method res, method res, method res, method res, method res, method res, object Test, object Test, object Test, package <empty>, package <root>, package <root>, package <root>, package <root>, package <root>, package <root>, package <root>, package <root>, <none>, <none>, <none>, <none> while compiling tests/pos/quotedPatterns.scala
Exception in thread "main" java.lang.AssertionError: assertion failed: bad owner; value y has owner value a, expected was method res
owner chain = value y, value a, method res, object Test, package <empty>, package <root>, ctxOwners = method res, method res, method res, method res, method res, method res, object Test, object Test, object Test, package <empty>, package <root>, package <root>, package <root>, package <root>, package <root>, package <root>, package <root>, package <root>, <none>, <none>, <none>, <none>
	at scala.Predef$.assert(Predef.scala:223)
	at dotty.tools.dotc.transform.TreeChecker$Checker.checkOwner(TreeChecker.scala:356)
	at dotty.tools.dotc.transform.TreeChecker$Checker.$anonfun$typedStats$1(TreeChecker.scala:425)
	at dotty.tools.dotc.transform.TreeChecker$Checker.$anonfun$typedStats$1$adapted(TreeChecker.scala:424)
	at scala.collection.immutable.List.foreach(List.scala:392)
	at dotty.tools.dotc.transform.TreeChecker$Checker.typedStats(TreeChecker.scala:424)
	at dotty.tools.dotc.typer.Typer.typedBlockStats(Typer.scala:698)
	at dotty.tools.dotc.typer.Typer.$anonfun$typedBlock$1(Typer.scala:701)
	at dotty.tools.dotc.util.Stats$.track(Stats.scala:37)
	at dotty.tools.dotc.typer.Typer.typedBlock(Typer.scala:700)
	at dotty.tools.dotc.transform.TreeChecker$Checker.super$typedBlock(TreeChecker.scala:411)
	at dotty.tools.dotc.transform.TreeChecker$Checker.$anonfun$typedBlock$1(TreeChecker.scala:411)
	at dotty.tools.dotc.transform.TreeChecker$Checker.withDefinedSyms(TreeChecker.scala:169)
	at dotty.tools.dotc.transform.TreeChecker$Checker.typedBlock(TreeChecker.scala:411)
	at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2077)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2124)
	at dotty.tools.dotc.typer.ReTyper.typedUnadapted(ReTyper.scala:117)
	at dotty.tools.dotc.transform.TreeChecker$Checker.typedUnadapted(TreeChecker.scala:267)
	...

[nicolasstucki]

The pattern is moved out of it scope in splitQuotePattern but the owner in never changed. It requires the owner of the outer ctx (the one of splitQuotePattern) but has the one of the transform ctx. I tried to use changeOwner but it deos not change the owner. Not sure if this is a bug in changeOwner.

I would imagine this fixed version should work

def splitQuotePattern(quoted: Tree)(implicit ctx: Context): (Tree, List[Tree]) = {
    val patternOwner = ctx.owner
    object splitter extends tpd.TreeMap {
      val patBuf = new mutable.ListBuffer[Tree]
      override def transform(tree: Tree)(implicit ctx: Context) = tree match {
        case Typed(Splice(pat), tpt) =>
          val exprTpt = AppliedTypeTree(TypeTree(defn.QuotedExprType), tpt :: Nil)
          transform(Splice(Typed(pat, exprTpt)))
        case Splice(pat) =>
          try patternHole(tree)
          finally patBuf += pat.changeOwner(ctx.owner, patternOwner)
        case _ =>
          super.transform(tree)
      }
    }
    val result = splitter.transform(quoted)
    (result, splitter.patBuf.toList)
  }

[nicolasstucki]

@odersky could you have a look?

[nicolasstucki]

The context I used above might not be the correct one in a case like

object Test {
  def res(x: quoted.Expr[Int]) given tasty.Reflection: quoted.Expr[Int] = x match {
    case '{ val a: Int = ${ Foo('{ val b: Int = $y }) }; 1} => y
  }
 object Foo {
   def unapply(x: Expr[Int]): Option[Expr[Int]] = Some(x)
 }
}

[nicolasstucki]

Actually in that last one the owner should be fixed when the outer splice is transformed

[odersky]

changeOwner does not work for toplevel binds. It only works on the level of whole match expressions. It's better not to create a wrong owner in the first place.