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Fix #4297: handle type param reference #4298

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Apr 12, 2018
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Fix #4297: handle type param reference #4298

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eec6854
Fix #4297: handle type param reference in isInstanceOfCheck
liufengyun Apr 11, 2018
f282783
address review
liufengyun Apr 12, 2018
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28 changes: 22 additions & 6 deletions compiler/src/dotty/tools/dotc/transform/IsInstanceOfChecker.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -88,19 +88,33 @@ object Checkable {
}
}

def stripTypeParam(implicit ctx: Context) = new ApproximatingTypeMap {
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@allanrenucci allanrenucci Apr 12, 2018

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Maybe add a comment: /** Approximate type parameters depending on variance */

def apply(tp: Type): Type = tp match {
case tp: TypeRef if tp.underlying.isInstanceOf[TypeBounds] =>
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@allanrenucci allanrenucci Apr 12, 2018

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Probably equivalent to case tp: TypeRef if tp.symbol.isTypeParam. Maybe clearer?

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@liufengyun liufengyun Apr 12, 2018

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tp.symbol.isTypeParam doesn't cover the case of type members, so I think it's better to keep the original version here.

val lo = this(tp.info.loBound)
val hi = this(tp.info.hiBound)
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@allanrenucci allanrenucci Apr 12, 2018

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Replace this by apply? It makes it clearer that this is a recursive call

range(lo, hi)
case _ =>
mapOver(tp)
}
}

def isClassDetermined(X: Type, P: AppliedType)(implicit ctx: Context) = {
val AppliedType(tycon, _) = P
val typeLambda = tycon.ensureLambdaSub.asInstanceOf[TypeLambda]
val tvars = constrained(typeLambda, untpd.EmptyTree, alwaysAddTypeVars = true)._2.map(_.tpe)
val P1 = tycon.appliedTo(tvars)

debug.println("P : " + P.show)
debug.println("P1 : " + P1.show)
debug.println("X : " + X.show)
debug.println("P : " + P)
debug.println("P1 : " + P1)
debug.println("X : " + X)

P1 <:< X // constraint P1

P1 <:< X // may fail, ignore
// use fromScala2x to avoid generating pattern bound symbols
maximizeType(P1, pos, fromScala2x = true)

val res = isFullyDefined(P1, ForceDegree.noBottom) && P1 <:< P
val res = P1 <:< P
debug.println("P1 : " + P1)
debug.println("P1 <:< P = " + res)

Expand All @@ -116,7 +130,9 @@ object Checkable {
case defn.ArrayOf(tpE) => recur(tpE, tpT)
case _ => recur(defn.AnyType, tpT)
}
case tpe: AppliedType => isClassDetermined(X, tpe)(ctx.fresh.setNewTyperState())
case tpe: AppliedType =>
isClassDetermined(X, tpe)(ctx.fresh.setNewTyperState()) ||
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@allanrenucci allanrenucci Apr 12, 2018

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Here, you first try without stripping type parameters for performance reasons? Maybe add a comment

isClassDetermined(stripTypeParam.apply(X), tpe)(ctx.fresh.setNewTyperState())
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@allanrenucci allanrenucci Apr 12, 2018

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Call it as stripTypeParam(X) instead of stripTypeParam.apply(X)?

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@liufengyun liufengyun Apr 12, 2018

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It seems scalac has problem with this syntax, however, I've changed the method so we don't need to call apply anymore.

case AndType(tp1, tp2) => recur(X, tp1) && recur(X, tp2)
case OrType(tp1, tp2) => recur(X, tp1) && recur(X, tp2)
case AnnotatedType(t, _) => recur(X, t)
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11 changes: 11 additions & 0 deletions tests/neg-custom-args/isInstanceOf/i4297.scala
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Original file line number Diff line number Diff line change
@@ -0,0 +1,11 @@
class Test {
def test[X <: Option[Int]](x: X) = x.isInstanceOf[Some[Int]]
def test1[Y <: Int, X <: Option[Y]](x: X) = x.isInstanceOf[Some[Int]]
def test2(x: Any) = x.isInstanceOf[Function1[Nothing, _]]
def test3a(x: Any) = x.isInstanceOf[Function1[Any, _]] // error
def test3b(x: Any) = x.isInstanceOf[Function1[Int, _]] // error
def test4[Y <: Int, X <: Function1[Y, Unit]](x: X) = x.isInstanceOf[Function1[Int, _]] // error
def test5[Y <: Int, X <: Function1[Y, Unit]](x: X) = x.isInstanceOf[Function1[Int, Unit]] // error
def test6[Y <: Int, X <: Function1[Y, Unit]](x: X) = x.isInstanceOf[Function1[Int, Any]] // error
def test7[Y <: Int, X <: Function1[Y, Unit]](x: X) = x.isInstanceOf[Function1[_, Unit]]
}