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capture-checking + match-type reduction crash #25843

Closed
#26306
Closed
capture-checking + match-type reduction crash#25843
#26306
Labels
area:experimental:ccCapture checking relatedarea:match-typesitype:bugitype:crash

Description

@halotukozak
halotukozak
opened on Apr 17, 2026

Compiler version

3.8.3

Minimized code

//> using scala 3.8.3
//> using options -language:experimental.captureChecking -experimental

import scala.deriving.Mirror

trait Show[T]:
  def show(t: T): String

object Show:
  given Show[Int] = _.toString
  given Show[String] = identity

  inline def derived[T <: Product: Mirror.ProductOf as m]: Show[T] = t =>
    val showables: List[Show[Any]] = ???
    val values = Tuple.fromProductTyped(t).toList
    showables.zip(values)
    ???

case class Foo(x: Int, y: String) derives Show

Output (click arrow to expand)

Details 
❯ scala-cli compile minimized.scala
Compiling project (Scala 3.8.3, JVM (21))
Error compiling project (Scala 3.8.3, JVM (21))
Error: scala.MatchError: AnnotatedType(AppliedType(TypeRef(ThisType(TypeRef(NoPrefix,module class runtime)),class MatchCase),List(AnnotatedType(TermRef(TermRef(TermRef(ThisType(TypeRef(NoPrefix,module class <root>)),object scala),object Tuple$package),object EmptyTuple),CaptureAnnotation({TermRef(TermRef(TermRef(ThisType(TypeRef(NoPrefix,module class <root>)),object scala),object Tuple$package),object EmptyTuple)},true)), TypeRef(TermRef(ThisType(TypeRef(NoPrefix,module class <root>)),object scala),Nothing))),CaptureAnnotation(Var10{},false)) (of class dotty.tools.dotc.core.Types$CachedAnnotatedType)
        at dotty.tools.dotc.core.Types$MatchTypeCaseSpec$.analyze(Types.scala:5424)
        at dotty.tools.dotc.core.Types$.dotty$tools$dotc$core$Types$MatchType$$_$reduced$$anonfun$1$$anonfun$1(Types.scala:5322)
        at scala.collection.immutable.List.map(List.scala:240)
        at dotty.tools.dotc.core.Types$MatchType.reduced$$anonfun$1(Types.scala:5322)
        at dotty.tools.dotc.core.TypeComparer.inSubComparer(TypeComparer.scala:3351)
        at dotty.tools.dotc.core.TypeComparer.reduceMatchWith(TypeComparer.scala:3362)
        at dotty.tools.dotc.core.TypeComparer$.reduceMatchWith(TypeComparer.scala:3573)
        at dotty.tools.dotc.core.Types$MatchType.reduced(Types.scala:5322)
        at dotty.tools.dotc.core.TypeComparer.secondTry$1(TypeComparer.scala:568)
        at dotty.tools.dotc.core.TypeComparer.compareNamed$1(TypeComparer.scala:348)
        at dotty.tools.dotc.core.TypeComparer.firstTry$1(TypeComparer.scala:354)
        at dotty.tools.dotc.core.TypeComparer.recur(TypeComparer.scala:1629)
        at dotty.tools.dotc.core.TypeComparer.isSubType(TypeComparer.scala:226)
        at dotty.tools.dotc.core.TypeComparer.isSubType(TypeComparer.scala:236)
        at dotty.tools.dotc.core.TypeComparer$.isSubType(TypeComparer.scala:3470)
        at dotty.tools.dotc.core.TypeOps$.check$1(TypeOps.scala:689)
        at dotty.tools.dotc.core.TypeOps$.checkOverlapsBounds$1(TypeOps.scala:700)
        at dotty.tools.dotc.core.TypeOps$.loop$1(TypeOps.scala:734)
        at dotty.tools.dotc.core.TypeOps$.boundsViolations(TypeOps.scala:739)
        at dotty.tools.dotc.typer.Checking$.checkBounds(Checking.scala:77)
        at dotty.tools.dotc.typer.Checking$.checkBounds(Checking.scala:87)
        at dotty.tools.dotc.cc.CheckCaptures.dotty$tools$dotc$cc$CheckCaptures$$anon$9$$_$op$proxy21$1(CheckCaptures.scala:2442)
        at dotty.tools.dotc.cc.CheckCaptures$$anon$9.check(CheckCaptures.scala:2442)
        at dotty.tools.dotc.cc.CheckCaptures$$anon$9.traverse(CheckCaptures.scala:2431)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.foldOver(Trees.scala:1702)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.traverseChildren(Trees.scala:1820)
        at dotty.tools.dotc.cc.CheckCaptures$$anon$9.traverse(CheckCaptures.scala:2430)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.fold$1(Trees.scala:1683)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.apply(Trees.scala:1685)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.foldOver(Trees.scala:1716)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.traverseChildren(Trees.scala:1820)
        at dotty.tools.dotc.cc.CheckCaptures$$anon$9.traverse(CheckCaptures.scala:2430)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.foldOver(Trees.scala:1771)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.traverseChildren(Trees.scala:1820)
        at dotty.tools.dotc.cc.CheckCaptures$$anon$9.traverse(CheckCaptures.scala:2430)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.fold$1(Trees.scala:1683)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.apply(Trees.scala:1685)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.foldOver(Trees.scala:1716)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.traverseChildren(Trees.scala:1820)
        at dotty.tools.dotc.cc.CheckCaptures$$anon$9.traverse(CheckCaptures.scala:2430)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.foldOver(Trees.scala:1710)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.traverseChildren(Trees.scala:1820)
        at dotty.tools.dotc.cc.CheckCaptures$$anon$9.traverse(CheckCaptures.scala:2430)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.foldOver(Trees.scala:1771)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.traverseChildren(Trees.scala:1820)
        at dotty.tools.dotc.cc.CheckCaptures$$anon$9.traverse(CheckCaptures.scala:2430)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.fold$1(Trees.scala:1683)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.apply(Trees.scala:1685)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.foldOver(Trees.scala:1778)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.traverseChildren(Trees.scala:1820)
        at dotty.tools.dotc.cc.CheckCaptures$$anon$9.traverse(CheckCaptures.scala:2430)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.foldOver(Trees.scala:1775)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.traverseChildren(Trees.scala:1820)
        at dotty.tools.dotc.cc.CheckCaptures$$anon$9.traverse(CheckCaptures.scala:2430)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.fold$1(Trees.scala:1683)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.apply(Trees.scala:1685)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.foldOver(Trees.scala:1784)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.traverseChildren(Trees.scala:1820)
        at dotty.tools.dotc.cc.CheckCaptures$$anon$9.traverse(CheckCaptures.scala:2430)
        at dotty.tools.dotc.cc.CheckCaptures$CaptureChecker.postCheck(CheckCaptures.scala:2452)
        at dotty.tools.dotc.cc.CheckCaptures$CaptureChecker.checkUnit$$anonfun$3(CheckCaptures.scala:2244)
        at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
        at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
        at dotty.tools.dotc.cc.CaptureSet$.withCaptureSetsExplained(CaptureSet.scala:1847)
        at dotty.tools.dotc.cc.CheckCaptures$CaptureChecker.checkUnit(CheckCaptures.scala:2248)
        at dotty.tools.dotc.transform.Recheck.run(Recheck.scala:154)
        at dotty.tools.dotc.cc.CheckCaptures.run(CheckCaptures.scala:276)
        at dotty.tools.dotc.core.Phases$Phase.runOn$$anonfun$1(Phases.scala:406)
        at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
        at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
        at scala.collection.immutable.List.foreach(List.scala:327)
        at dotty.tools.dotc.core.Phases$Phase.runOn(Phases.scala:399)
        at dotty.tools.dotc.transform.Recheck.runOn(Recheck.scala:158)
        at dotty.tools.dotc.cc.CheckCaptures.runOn(CheckCaptures.scala:272)
        at dotty.tools.dotc.Run.runPhases$1$$anonfun$1(Run.scala:380)
        at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
        at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
        at scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1324)
        at dotty.tools.dotc.Run.runPhases$1(Run.scala:373)
        at dotty.tools.dotc.Run.compileUnits$$anonfun$1$$anonfun$2(Run.scala:420)
        at dotty.tools.dotc.Run.compileUnits$$anonfun$1$$anonfun$adapted$1(Run.scala:420)
        at scala.Function0.apply$mcV$sp(Function0.scala:42)
        at dotty.tools.dotc.Run.showProgress(Run.scala:482)
        at dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:420)
        at dotty.tools.dotc.Run.compileUnits$$anonfun$adapted$1(Run.scala:432)
        at dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:69)
        at dotty.tools.dotc.Run.compileUnits(Run.scala:432)
        at dotty.tools.dotc.Run.compileSources(Run.scala:319)
        at dotty.tools.dotc.Run.compile(Run.scala:304)
        at dotty.tools.dotc.Driver.doCompile(Driver.scala:37)
        at dotty.tools.xsbt.CompilerBridgeDriver.run(CompilerBridgeDriver.java:141)
        at dotty.tools.xsbt.CompilerBridge.run(CompilerBridge.java:22)
        at sbt.internal.inc.AnalyzingCompiler.compile(AnalyzingCompiler.scala:91)
        at sbt.internal.inc.bloop.internal.BloopHighLevelCompiler.compileSources$1(BloopHighLevelCompiler.scala:148)
        at sbt.internal.inc.bloop.internal.BloopHighLevelCompiler.$anonfun$compile$9(BloopHighLevelCompiler.scala:181)
        at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
        at sbt.internal.inc.bloop.internal.BloopHighLevelCompiler.$anonfun$compile$1(BloopHighLevelCompiler.scala:73)
        at bloop.tracing.NoopTracer$.trace(BraveTracer.scala:53)
        at sbt.internal.inc.bloop.internal.BloopHighLevelCompiler.timed$1(BloopHighLevelCompiler.scala:72)
        at sbt.internal.inc.bloop.internal.BloopHighLevelCompiler.$anonfun$compile$8(BloopHighLevelCompiler.scala:181)
        at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
        at monix.eval.internal.TaskRunLoop$.startFull(TaskRunLoop.scala:81)
        at monix.eval.internal.TaskRestartCallback.syncOnSuccess(TaskRestartCallback.scala:101)
        at monix.eval.internal.TaskRestartCallback.onSuccess(TaskRestartCallback.scala:74)
        at monix.eval.internal.TaskExecuteOn$AsyncRegister$$anon$1.run(TaskExecuteOn.scala:71)
        at java.base/java.util.concurrent.ForkJoinTask$RunnableExecuteAction.exec(ForkJoinTask.java:1423)
        at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:387)
        at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1312)
        at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1843)
        at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1808)
        at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:188)

Error: Unexpected error when compiling repro_e6e96f4093-4bc1372c19: scala.MatchError: AnnotatedType(AppliedType(TypeRef(ThisType(TypeRef(NoPrefix,module class runtime)),class MatchCase),List(AnnotatedType(TermRef(TermRef(TermRef(ThisType(TypeRef(NoPrefix,module class <root>)),object scala),object Tuple$package),object EmptyTuple),CaptureAnnotation({TermRef(TermRef(TermRef(ThisType(TypeRef(NoPrefix,module class <root>)),object scala),object Tuple$package),object EmptyTuple)},true)), TypeRef(TermRef(ThisType(TypeRef(NoPrefix,module class <root>)),object scala),Nothing))),CaptureAnnotation(Var10{},false)) (of class dotty.tools.dotc.core.Types$CachedAnnotatedType)
        at dotty.tools.dotc.core.Types$MatchTypeCaseSpec$.analyze(Types.scala:5424)
        at dotty.tools.dotc.core.Types$.dotty$tools$dotc$core$Types$MatchType$$_$reduced$$anonfun$1$$anonfun$1(Types.scala:5322)
        at scala.collection.immutable.List.map(List.scala:240)
        at dotty.tools.dotc.core.Types$MatchType.reduced$$anonfun$1(Types.scala:5322)
        at dotty.tools.dotc.core.TypeComparer.inSubComparer(TypeComparer.scala:3351)
        at dotty.tools.dotc.core.TypeComparer.reduceMatchWith(TypeComparer.scala:3362)
        at dotty.tools.dotc.core.TypeComparer$.reduceMatchWith(TypeComparer.scala:3573)
        at dotty.tools.dotc.core.Types$MatchType.reduced(Types.scala:5322)
        at dotty.tools.dotc.core.TypeComparer.secondTry$1(TypeComparer.scala:568)
        at dotty.tools.dotc.core.TypeComparer.compareNamed$1(TypeComparer.scala:348)
        at dotty.tools.dotc.core.TypeComparer.firstTry$1(TypeComparer.scala:354)
        at dotty.tools.dotc.core.TypeComparer.recur(TypeComparer.scala:1629)
        at dotty.tools.dotc.core.TypeComparer.isSubType(TypeComparer.scala:226)
        at dotty.tools.dotc.core.TypeComparer.isSubType(TypeComparer.scala:236)
        at dotty.tools.dotc.core.TypeComparer$.isSubType(TypeComparer.scala:3470)
        at dotty.tools.dotc.core.TypeOps$.check$1(TypeOps.scala:689)
        at dotty.tools.dotc.core.TypeOps$.checkOverlapsBounds$1(TypeOps.scala:700)
        at dotty.tools.dotc.core.TypeOps$.loop$1(TypeOps.scala:734)
        at dotty.tools.dotc.core.TypeOps$.boundsViolations(TypeOps.scala:739)
        at dotty.tools.dotc.typer.Checking$.checkBounds(Checking.scala:77)
        at dotty.tools.dotc.typer.Checking$.checkBounds(Checking.scala:87)
        at dotty.tools.dotc.cc.CheckCaptures.dotty$tools$dotc$cc$CheckCaptures$$anon$9$$_$op$proxy21$1(CheckCaptures.scala:2442)
        at dotty.tools.dotc.cc.CheckCaptures$$anon$9.check(CheckCaptures.scala:2442)
        at dotty.tools.dotc.cc.CheckCaptures$$anon$9.traverse(CheckCaptures.scala:2431)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.foldOver(Trees.scala:1702)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.traverseChildren(Trees.scala:1820)
        at dotty.tools.dotc.cc.CheckCaptures$$anon$9.traverse(CheckCaptures.scala:2430)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.fold$1(Trees.scala:1683)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.apply(Trees.scala:1685)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.foldOver(Trees.scala:1716)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.traverseChildren(Trees.scala:1820)
        at dotty.tools.dotc.cc.CheckCaptures$$anon$9.traverse(CheckCaptures.scala:2430)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.foldOver(Trees.scala:1771)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.traverseChildren(Trees.scala:1820)
        at dotty.tools.dotc.cc.CheckCaptures$$anon$9.traverse(CheckCaptures.scala:2430)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.fold$1(Trees.scala:1683)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.apply(Trees.scala:1685)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.foldOver(Trees.scala:1716)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.traverseChildren(Trees.scala:1820)
        at dotty.tools.dotc.cc.CheckCaptures$$anon$9.traverse(CheckCaptures.scala:2430)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.foldOver(Trees.scala:1710)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.traverseChildren(Trees.scala:1820)
        at dotty.tools.dotc.cc.CheckCaptures$$anon$9.traverse(CheckCaptures.scala:2430)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.foldOver(Trees.scala:1771)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.traverseChildren(Trees.scala:1820)
        at dotty.tools.dotc.cc.CheckCaptures$$anon$9.traverse(CheckCaptures.scala:2430)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.fold$1(Trees.scala:1683)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.apply(Trees.scala:1685)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.foldOver(Trees.scala:1778)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.traverseChildren(Trees.scala:1820)
        at dotty.tools.dotc.cc.CheckCaptures$$anon$9.traverse(CheckCaptures.scala:2430)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.foldOver(Trees.scala:1775)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.traverseChildren(Trees.scala:1820)
        at dotty.tools.dotc.cc.CheckCaptures$$anon$9.traverse(CheckCaptures.scala:2430)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1819)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.fold$1(Trees.scala:1683)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.apply(Trees.scala:1685)
        at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.foldOver(Trees.scala:1784)
        at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.traverseChildren(Trees.scala:1820)
        at dotty.tools.dotc.cc.CheckCaptures$$anon$9.traverse(CheckCaptures.scala:2430)
        at dotty.tools.dotc.cc.CheckCaptures$CaptureChecker.postCheck(CheckCaptures.scala:2452)
        at dotty.tools.dotc.cc.CheckCaptures$CaptureChecker.checkUnit$$anonfun$3(CheckCaptures.scala:2244)
        at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
        at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
        at dotty.tools.dotc.cc.CaptureSet$.withCaptureSetsExplained(CaptureSet.scala:1847)
        at dotty.tools.dotc.cc.CheckCaptures$CaptureChecker.checkUnit(CheckCaptures.scala:2248)
        at dotty.tools.dotc.transform.Recheck.run(Recheck.scala:154)
        at dotty.tools.dotc.cc.CheckCaptures.run(CheckCaptures.scala:276)
        at dotty.tools.dotc.core.Phases$Phase.runOn$$anonfun$1(Phases.scala:406)
        at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
        at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
        at scala.collection.immutable.List.foreach(List.scala:327)
        at dotty.tools.dotc.core.Phases$Phase.runOn(Phases.scala:399)
        at dotty.tools.dotc.transform.Recheck.runOn(Recheck.scala:158)
        at dotty.tools.dotc.cc.CheckCaptures.runOn(CheckCaptures.scala:272)
        at dotty.tools.dotc.Run.runPhases$1$$anonfun$1(Run.scala:380)
        at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
        at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
        at scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1324)
        at dotty.tools.dotc.Run.runPhases$1(Run.scala:373)
        at dotty.tools.dotc.Run.compileUnits$$anonfun$1$$anonfun$2(Run.scala:420)
        at dotty.tools.dotc.Run.compileUnits$$anonfun$1$$anonfun$adapted$1(Run.scala:420)
        at scala.Function0.apply$mcV$sp(Function0.scala:42)
        at dotty.tools.dotc.Run.showProgress(Run.scala:482)
        at dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:420)
        at dotty.tools.dotc.Run.compileUnits$$anonfun$adapted$1(Run.scala:432)
        at dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:69)
        at dotty.tools.dotc.Run.compileUnits(Run.scala:432)
        at dotty.tools.dotc.Run.compileSources(Run.scala:319)
        at dotty.tools.dotc.Run.compile(Run.scala:304)
        at dotty.tools.dotc.Driver.doCompile(Driver.scala:37)
        at dotty.tools.xsbt.CompilerBridgeDriver.run(CompilerBridgeDriver.java:141)
        at dotty.tools.xsbt.CompilerBridge.run(CompilerBridge.java:22)
        at sbt.internal.inc.AnalyzingCompiler.compile(AnalyzingCompiler.scala:91)
        at sbt.internal.inc.bloop.internal.BloopHighLevelCompiler.compileSources$1(BloopHighLevelCompiler.scala:148)
        at sbt.internal.inc.bloop.internal.BloopHighLevelCompiler.$anonfun$compile$9(BloopHighLevelCompiler.scala:181)
        at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
        at sbt.internal.inc.bloop.internal.BloopHighLevelCompiler.$anonfun$compile$1(BloopHighLevelCompiler.scala:73)
        at bloop.tracing.NoopTracer$.trace(BraveTracer.scala:53)
        at sbt.internal.inc.bloop.internal.BloopHighLevelCompiler.timed$1(BloopHighLevelCompiler.scala:72)
        at sbt.internal.inc.bloop.internal.BloopHighLevelCompiler.$anonfun$compile$8(BloopHighLevelCompiler.scala:181)
        at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
        at monix.eval.internal.TaskRunLoop$.startFull(TaskRunLoop.scala:81)
        at monix.eval.internal.TaskRestartCallback.syncOnSuccess(TaskRestartCallback.scala:101)
        at monix.eval.internal.TaskRestartCallback.onSuccess(TaskRestartCallback.scala:74)
        at monix.eval.internal.TaskExecuteOn$AsyncRegister$$anon$1.run(TaskExecuteOn.scala:71)
        at java.base/java.util.concurrent.ForkJoinTask$RunnableExecuteAction.exec(ForkJoinTask.java:1423)
        at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:387)
        at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1312)
        at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1843)
        at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1808)
        at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:188)

Compilation failed

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