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NullPointerException at dotty.tools.dotc.core.Types$HKTypeLambda.iso #13513

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aborg0 opened this issue Sep 12, 2021 · 0 comments · Fixed by #13517
Closed

NullPointerException at dotty.tools.dotc.core.Types$HKTypeLambda.iso #13513

aborg0 opened this issue Sep 12, 2021 · 0 comments · Fixed by #13517
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@smarter
Labels
area:typer itype:crash
Milestone
3.1.1

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@aborg0
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aborg0 commented Sep 12, 2021

Compiler version

3.0.2

Minimized code

final case class TwoTypes[F, A](value: A)
class Minimal {
  def x[C[_]]: C[Int] = ???
  x[TwoTypes].value
}

Output (click arrow to expand)

/tmp/scala3-3.0.2$ bin/scalac Minimal.scala
exception occurred while typechecking Minimal.scala
exception occurred while compiling Minimal.scala
java.lang.NullPointerException while compiling Minimal.scala
Exception in thread "main" java.lang.NullPointerException
        at dotty.tools.dotc.core.Types$HKTypeLambda.iso(Types.scala:3883)
        at dotty.tools.dotc.core.Types$Type.equals(Types.scala:1874)
        at dotty.tools.dotc.core.Types$HKLambda.equals(Types.scala:3465)
        at dotty.tools.dotc.core.Substituters$.substParams(Substituters.scala:151)
        at dotty.tools.dotc.core.Substituters$.mapArgs$2(Substituters.scala:158)
        at dotty.tools.dotc.core.Substituters$.substParams(Substituters.scala:158)
        at dotty.tools.dotc.core.Types$Type.substParams(Types.scala:1765)
        at dotty.tools.dotc.core.Types$LambdaType.instantiate(Types.scala:3428)
        at dotty.tools.dotc.core.Types$LambdaType.instantiate$(Types.scala:3389)
        at dotty.tools.dotc.core.Types$HKLambda.instantiate(Types.scala:3462)
        at dotty.tools.dotc.core.TypeApplications$.tryReduce$1(TypeApplications.scala:335)
        at dotty.tools.dotc.core.TypeApplications$.appliedTo$extension(TypeApplications.scala:354)
        at dotty.tools.dotc.core.Types$AppliedType.derivedAppliedType(Types.scala:4288)
        at dotty.tools.dotc.core.Substituters$.subst(Substituters.scala:20)
        at dotty.tools.dotc.core.Substituters$.subst(Substituters.scala:16)
        at dotty.tools.dotc.core.Types$Type.subst(Types.scala:1745)
        at dotty.tools.dotc.core.Types$HKTypeLambda.newLikeThis$$anonfun$2(Types.scala:3895)
        at dotty.tools.dotc.core.Types$HKTypeLambda.<init>(Types.scala:3851)
        at dotty.tools.dotc.core.Types$HKTypeLambda$.apply(Types.scala:3956)
        at dotty.tools.dotc.core.Types$HKTypeLambda.newLikeThis(Types.scala:3895)
        at dotty.tools.dotc.core.Types$HKTypeLambda.newLikeThis(Types.scala:3890)
        at dotty.tools.dotc.core.Types$HKTypeLambda.newLikeThis(Types.scala:3889)
        at dotty.tools.dotc.core.Types$LambdaType.derivedLambdaType(Types.scala:3446)
        at dotty.tools.dotc.core.Types$LambdaType.derivedLambdaType$(Types.scala:3389)
        at dotty.tools.dotc.core.Types$HKLambda.derivedLambdaType(Types.scala:3462)
        at dotty.tools.dotc.core.Types$TypeLambda.derivedLambdaAbstraction(Types.scala:3826)
        at dotty.tools.dotc.core.Types$TypeLambda.derivedLambdaAbstraction$(Types.scala:3803)
        at dotty.tools.dotc.core.Types$HKTypeLambda.derivedLambdaAbstraction(Types.scala:3844)
        at dotty.tools.dotc.core.Types$Type.goApplied$2$$anonfun$1(Types.scala:803)
        at dotty.tools.dotc.core.Denotations$SingleDenotation.mapInfo(Denotations.scala:626)
        at dotty.tools.dotc.core.Denotations$SingleDenotation.mapInfo(Denotations.scala:625)
        at dotty.tools.dotc.core.Types$Type.goApplied$1(Types.scala:803)
        at dotty.tools.dotc.core.Types$Type.go$1(Types.scala:695)
        at dotty.tools.dotc.core.Types$Type.findMember(Types.scala:870)
        at dotty.tools.dotc.core.Types$Type.memberBasedOnFlags(Types.scala:666)
        at dotty.tools.dotc.core.Types$Type.member(Types.scala:650)
        at dotty.tools.dotc.typer.ProtoTypes$SelectionProto.isMatchedBy(ProtoTypes.scala:187)
        at dotty.tools.dotc.core.TypeComparer.isMatchedByProto(TypeComparer.scala:1874)
        at dotty.tools.dotc.core.TypeComparer.firstTry$1(TypeComparer.scala:315)
        at dotty.tools.dotc.core.TypeComparer.recur(TypeComparer.scala:1296)
        at dotty.tools.dotc.core.TypeComparer.isSubType(TypeComparer.scala:195)
        at dotty.tools.dotc.core.TypeComparer.isSubType(TypeComparer.scala:205)
        at dotty.tools.dotc.core.TypeComparer.topLevelSubType(TypeComparer.scala:128)
        at dotty.tools.dotc.core.TypeComparer.testSubType(TypeComparer.scala:154)
        at dotty.tools.dotc.core.TypeComparer$.testSubType(TypeComparer.scala:2715)
        at dotty.tools.dotc.typer.Typer.adaptNoArgsOther$4(Typer.scala:3523)
        at dotty.tools.dotc.typer.Typer.adaptNoArgs$1(Typer.scala:3619)
        at dotty.tools.dotc.typer.Typer.adapt1(Typer.scala:3810)
        at dotty.tools.dotc.typer.Typer.adapt(Typer.scala:3162)
        at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2821)
        at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2825)
        at dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:2941)
        at dotty.tools.dotc.typer.Typer.typeSelectOnTerm$1(Typer.scala:611)
        at dotty.tools.dotc.typer.Typer.typedSelect(Typer.scala:661)
        at dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:2663)
        at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2755)
        at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2821)
        at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2825)
        at dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:2874)
        at dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:2897)
        at dotty.tools.dotc.typer.Typer.typedClassDef(Typer.scala:2352)
        at dotty.tools.dotc.typer.Typer.typedTypeOrClassDef$2(Typer.scala:2681)
        at dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:2685)
        at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2755)
        at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2821)
        at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2825)
        at dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:2847)
        at dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:2897)
        at dotty.tools.dotc.typer.Typer.typedPackageDef(Typer.scala:2475)
        at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2726)
        at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2756)
        at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2821)
        at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2825)
        at dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:2941)
        at dotty.tools.dotc.typer.FrontEnd.liftedTree1$1(FrontEnd.scala:79)
        at dotty.tools.dotc.typer.FrontEnd.typeCheck$$anonfun$1(FrontEnd.scala:84)
        at dotty.tools.dotc.typer.FrontEnd.monitor(FrontEnd.scala:43)
        at dotty.tools.dotc.typer.FrontEnd.typeCheck(FrontEnd.scala:85)
        at dotty.tools.dotc.typer.FrontEnd.runOn$$anonfun$3(FrontEnd.scala:120)
        at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
        at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
        at scala.collection.immutable.List.foreach(List.scala:333)
        at dotty.tools.dotc.typer.FrontEnd.runOn(FrontEnd.scala:120)
        at dotty.tools.dotc.Run.runPhases$4$$anonfun$4(Run.scala:205)
        at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
        at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
        at scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1323)
        at dotty.tools.dotc.Run.runPhases$5(Run.scala:216)
        at dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:224)
        at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.scala:18)
        at dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:67)
        at dotty.tools.dotc.Run.compileUnits(Run.scala:231)
        at dotty.tools.dotc.Run.compileSources(Run.scala:166)
        at dotty.tools.dotc.Run.compile(Run.scala:150)
        at dotty.tools.dotc.Driver.doCompile(Driver.scala:39)
        at dotty.tools.dotc.Driver.process(Driver.scala:199)
        at dotty.tools.dotc.Driver.process(Driver.scala:167)
        at dotty.tools.dotc.Driver.process(Driver.scala:179)
        at dotty.tools.dotc.Driver.main(Driver.scala:209)
        at dotty.tools.dotc.Main.main(Main.scala)
@SethTisue SethTisue mentioned this issue Sep 12, 2021
Closed
smarter added a commit to dotty-staging/dotty that referenced this issue Sep 13, 2021
@smarter
Fix crash on uninstantiated field access
3f25f89 
The uninstantiated access in the test case happens because the closure
passed to the HKTypeLambda constructor to construct the result type by
`HKTypeLambda.newLikeThis` calls `subst` which eventually calls
`HKTypeLambda#equals`, I don't see a way to prevent that at the source,
so make equality checking robust to uninstantatied fields.

Fixes scala#13513.
@smarter smarter mentioned this issue Sep 13, 2021
Merged
olsdavis pushed a commit to olsdavis/dotty that referenced this issue Apr 4, 2022
@smarter @olsdavis
Fix crash on uninstantiated field access
852a497 
The uninstantiated access in the test case happens because the closure
passed to the HKTypeLambda constructor to construct the result type by
`HKTypeLambda.newLikeThis` calls `subst` which eventually calls
`HKTypeLambda#equals`, I don't see a way to prevent that at the source,
so make equality checking robust to uninstantatied fields.

Fixes scala#13513.
@Kordyjan Kordyjan added this to the 3.1.1 milestone Aug 2, 2023
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Fix crash on uninstantiated field access dotty-staging/dotty
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@smarter @aborg0 @Kordyjan