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Compiler stack overflow when converting an unapplied method with implicit to a function value #10156

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scabug opened this Issue Jan 20, 2017 · 2 comments

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scabug commented Jan 20, 2017

Having defined a simple method with an implicit argument, e.g.

trait A

def x(implicit a: A) = a

we can easily make the compiler to fail with stack overflow using (possibly errornous, but nevertheless) converting of an unapplied function to a function value:

val z = x _

Stack trace is

java.lang.StackOverflowError
        at scala.reflect.internal.Types$Type.isError(Types.scala:298)
        at scala.reflect.internal.Types$SimpleTypeProxy.isError(Types.scala:141)
        at scala.reflect.internal.Types$SimpleTypeProxy.isError$(Types.scala:141)
        at scala.reflect.internal.Types$SingletonType.isError(Types.scala:1088)
        at scala.reflect.internal.tpe.TypeMaps$ErroneousCollector$.traverse(TypeMaps.scala:1093)
        at scala.reflect.internal.tpe.TypeMaps$TypeTraverser.apply(TypeMaps.scala:300)
        at scala.reflect.internal.tpe.TypeMaps$TypeMap.mapOver(TypeMaps.scala:123)
        at scala.reflect.internal.tpe.TypeMaps$ErroneousCollector$.traverse(TypeMaps.scala:1094)
        at scala.reflect.internal.tpe.TypeMaps$TypeTraverser.apply(TypeMaps.scala:300)
        at scala.reflect.internal.tpe.TypeMaps$TypeMap.mapOver(TypeMaps.scala:123)
        at scala.reflect.internal.tpe.TypeMaps$ErroneousCollector$.traverse(TypeMaps.scala:1094)
        at scala.reflect.internal.tpe.TypeMaps$TypeTraverser.apply(TypeMaps.scala:300)
        at scala.reflect.internal.tpe.TypeMaps$TypeMap.mapOver(TypeMaps.scala:110)
        at scala.reflect.internal.tpe.TypeMaps$ErroneousCollector$.traverse(TypeMaps.scala:1094)
        at scala.reflect.internal.tpe.TypeMaps$TypeCollector.collect(TypeMaps.scala:312)
        at scala.reflect.internal.Types$Type.isErroneous(Types.scala:301)
        at scala.tools.nsc.typechecker.Typers$Typer.$anonfun$applyImplicitArgs$2(Typers.scala:172)
        at scala.collection.immutable.List.foreach(List.scala:378)
        at scala.tools.nsc.typechecker.Typers$Typer.applyImplicitArgs(Typers.scala:166)
        at scala.tools.nsc.typechecker.Typers$Typer.$anonfun$adapt$2(Typers.scala:850)
        at scala.tools.nsc.typechecker.Typers$Typer.silent(Typers.scala:703)
        at scala.tools.nsc.typechecker.Typers$Typer.$anonfun$adapt$1(Typers.scala:849)
        at scala.tools.nsc.typechecker.Typers$Typer.withCondConstrTyper(Typers.scala:482)
        at scala.tools.nsc.typechecker.Typers$Typer.adaptToImplicitMethod$1(Typers.scala:847)
        at scala.tools.nsc.typechecker.Typers$Typer.adapt(Typers.scala:1197)
        at scala.tools.nsc.typechecker.Typers$Typer.typedEta$1(Typers.scala:4523)
        at scala.tools.nsc.typechecker.Typers$Typer.typedTyped$1(Typers.scala:5224)
        at scala.tools.nsc.typechecker.Typers$Typer.typedInAnyMode$1(Typers.scala:5469)
        at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:5483)
        at scala.tools.nsc.typechecker.Typers$Typer.runTyper$1(Typers.scala:5519)
        at scala.tools.nsc.typechecker.Typers$Typer.typedInternal(Typers.scala:5549)
        at scala.tools.nsc.typechecker.Typers$Typer.body$2(Typers.scala:5493)
        at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:5497)
        at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:5594)
        at scala.tools.nsc.typechecker.Typers$Typer.$anonfun$adapt$3(Typers.scala:867)
        at scala.tools.nsc.typechecker.Typers$SilentResult.orElse(Typers.scala:77)
        at scala.tools.nsc.typechecker.Typers$Typer.$anonfun$adapt$1(Typers.scala:854)
        at scala.tools.nsc.typechecker.Typers$Typer.withCondConstrTyper(Typers.scala:482)

etc...

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scabug commented Jan 20, 2017

Imported From: https://issues.scala-lang.org/browse/SI-10156?orig=1
Reporter: Denis Buzdalov (buzden)
Affected Versions: 2.12.1

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diesalbla commented Sep 20, 2018

I have checked out the version 2.12.4, and tested the following code, added to a neg test file.

object t10156 {
  trait A
  def x(implicit a: A) = a
  val z = x _
}

Running this with partest test/files/pos/t10156.scala no longer gives a StackOverflow, but with a compiler error. It would seem that this bug has been solved since at least version 2.12.4.

@adriaanm adriaanm added this to the 2.12.4 milestone Sep 21, 2018

@SethTisue SethTisue closed this Sep 27, 2018

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