Spurious " has non-class parent: val <none>" warnings/errors

[pshirshov]

3.1.3

This looks some kind of a race condition in the compiler because it's not always happening on my machine.

From time to time I'm getting output like this while compiling classes which use BIOCatsMonad

scala: java.lang.AssertionError: assertion failed: class BIOCatsMonad has non-class parent: val <none>
scala: 	at scala.runtime.Scala3RunTime$.assertFailed(Scala3RunTime.scala:8)
scala: 	at dotty.tools.dotc.core.SymDenotations$ClassDenotation.traverse$1(SymDenotations.scala:1899)
scala: 	at dotty.tools.dotc.core.SymDenotations$ClassDenotation.computeBaseData(SymDenotations.scala:1904)
scala: 	at dotty.tools.dotc.core.SymDenotations$BaseDataImpl.apply(SymDenotations.scala:2873)
scala: 	at dotty.tools.dotc.core.SymDenotations$ClassDenotation.baseData(SymDenotations.scala:1870)
scala: 	at dotty.tools.dotc.core.SymDenotations$ClassDenotation.baseClassSet(SymDenotations.scala:1886)
scala: 	at dotty.tools.dotc.core.SymDenotations$ClassDenotation.derivesFrom(SymDenotations.scala:1912)
scala: 	at dotty.tools.dotc.core.SymDenotations$SymDenotation.isValueClass(SymDenotations.scala:808)
scala: 	at dotty.tools.dotc.transform.ValueClasses$.isDerivedValueClass(ValueClasses.scala:19)
scala: 	at dotty.tools.dotc.core.TypeErasure$.dotty$tools$dotc$core$TypeErasure$$$erasureDependsOnArgs(TypeErasure.scala:75)
scala: 	at dotty.tools.dotc.core.TypeErasure.dotty$tools$dotc$core$TypeErasure$$sigName(TypeErasure.scala:814)
scala: 	at dotty.tools.dotc.core.TypeErasure$.sigName(TypeErasure.scala:204)
scala: 	at dotty.tools.dotc.core.Signature$.apply(Signature.scala:167)
scala: 	at dotty.tools.dotc.core.Types$MethodOrPoly.computeSignature$2(Types.scala:3535)
scala: 	at dotty.tools.dotc.core.Types$MethodOrPoly.signature(Types.scala:3556)
scala: 	at dotty.tools.dotc.core.Types$MethodOrPoly.computeSignature$2(Types.scala:3531)
scala: 	at dotty.tools.dotc.core.Denotations$SingleDenotation.signature(Denotations.scala:615)
scala: 	at dotty.tools.dotc.core.Denotations$SingleDenotation.signature(Denotations.scala:605)
scala: 	at dotty.tools.dotc.core.Denotations$SingleDenotation.atSignature(Denotations.scala:647)
scala: 	at dotty.tools.dotc.core.Denotations$SingleDenotation.atSignature(Denotations.scala:645)
scala: 	at dotty.tools.dotc.core.tasty.TreeUnpickler$TreeReader.readLengthTerm$1(TreeUnpickler.scala:1223)
scala: 	at dotty.tools.dotc.core.tasty.TreeUnpickler$TreeReader.readTerm(TreeUnpickler.scala:1297)
scala: 	at dotty.tools.dotc.core.tasty.TreeUnpickler$TreeReader.readLengthTerm$1(TreeUnpickler.scala:1140)
scala: 	at dotty.tools.dotc.core.tasty.TreeUnpickler$TreeReader.readLengthTerm$1(TreeUnpickler.scala:1137)
scala: 	at dotty.tools.dotc.core.tasty.TreeUnpickler$TreeReader.$anonfun$19(TreeUnpickler.scala:934)
scala: 	at dotty.tools.tasty.TastyReader.collectWhile(TastyReader.scala:137)
scala: 	at dotty.tools.dotc.core.tasty.TreeUnpickler$TreeReader.readTemplate(TreeUnpickler.scala:937)
scala: 	at dotty.tools.dotc.core.tasty.TreeUnpickler$TreeReader.readNewDef(TreeUnpickler.scala:855)
scala: 	at dotty.tools.dotc.core.tasty.TreeUnpickler$TreeReader.readIndexedDef(TreeUnpickler.scala:774)
scala: 	at dotty.tools.dotc.core.tasty.TreeUnpickler$Completer.complete(TreeUnpickler.scala:120)
scala: 	at dotty.tools.dotc.core.SymDenotations$SymDenotation.completeFrom(SymDenotations.scala:167)
scala: 	at dotty.tools.dotc.core.Denotations$Denotation.completeInfo$1(Denotations.scala:187)
scala: 	at dotty.tools.dotc.core.Denotations$Denotation.info(Denotations.scala:189)
scala: 	at dotty.tools.dotc.core.Types$NamedType.info(Types.scala:2204)
scala: 	at dotty.tools.dotc.core.Types$TypeRef.underlying(Types.scala:2702)
scala: 	at dotty.tools.dotc.core.Types$Type.findDecl(Types.scala:640)
scala: 	at dotty.tools.dotc.core.Types$Type.decl(Types.scala:625)
scala: 	at dotty.tools.dotc.core.NamerOps$.addConstructorApplies(NamerOps.scala:107)
scala: 	at dotty.tools.dotc.core.NamerOps$$anon$1.complete(NamerOps.scala:122)
scala: 	at dotty.tools.dotc.core.SymDenotations$SymDenotation.ensureCompleted(SymDenotations.scala:369)
scala: 	at dotty.tools.dotc.core.SymDenotations$SymDenotation.flags(SymDenotations.scala:64)
scala: 	at dotty.tools.dotc.core.SymDenotations$ModuleCompleter.complete(SymDenotations.scala:2690)
scala: 	at dotty.tools.dotc.core.SymDenotations$SymDenotation.is(SymDenotations.scala:116)
scala: 	at dotty.tools.dotc.typer.ImportSuggestions.lookInside$1(ImportSuggestions.scala:66)
scala: 	at dotty.tools.dotc.typer.ImportSuggestions.nestedRoots$1$$anonfun$1$$anonfun$1(ImportSuggestions.scala:75)
scala: 	at dotty.tools.dotc.core.Scopes$Scope.filter(Scopes.scala:102)
scala: 	at dotty.tools.dotc.typer.ImportSuggestions.nestedRoots$1$$anonfun$1(ImportSuggestions.scala:78)
scala: 	at scala.collection.immutable.List.flatMap(List.scala:293)
scala: 	at dotty.tools.dotc.typer.ImportSuggestions.nestedRoots$1(ImportSuggestions.scala:78)
scala: 	at dotty.tools.dotc.typer.ImportSuggestions.rootsStrictlyIn$1(ImportSuggestions.scala:97)
scala: 	at dotty.tools.dotc.typer.ImportSuggestions.rootsIn$1(ImportSuggestions.scala:108)
scala: 	at dotty.tools.dotc.typer.ImportSuggestions.rootsStrictlyIn$1$$anonfun$2(ImportSuggestions.scala:100)
scala: 	at dotty.tools.dotc.typer.ImportSuggestions.rootsStrictlyIn$1(ImportSuggestions.scala:100)
scala: 	at dotty.tools.dotc.typer.ImportSuggestions.rootsOnPath$1(ImportSuggestions.scala:111)
scala: 	at dotty.tools.dotc.typer.ImportSuggestions.recur$1(ImportSuggestions.scala:128)
scala: 	at dotty.tools.dotc.typer.ImportSuggestions.recur$1(ImportSuggestions.scala:130)
scala: 	at dotty.tools.dotc.typer.ImportSuggestions.suggestionRoots(ImportSuggestions.scala:133)
scala: 	at dotty.tools.dotc.typer.ImportSuggestions.importSuggestions(ImportSuggestions.scala:235)
scala: 	at dotty.tools.dotc.typer.ImportSuggestions.importSuggestionAddendum(ImportSuggestions.scala:323)
scala: 	at dotty.tools.dotc.typer.ImportSuggestions.importSuggestionAddendum$(ImportSuggestions.scala:21)
scala: 	at dotty.tools.dotc.typer.Typer.importSuggestionAddendum(Typer.scala:117)
scala: 	at dotty.tools.dotc.typer.Implicits.$anonfun$3(Implicits.scala:900)
scala: 	at scala.Option.getOrElse(Option.scala:201)
scala: 	at dotty.tools.dotc.typer.ImplicitSearchError.hiddenImplicitsAddendum(ErrorReporting.scala:417)
scala: 	at dotty.tools.dotc.typer.ImplicitSearchError.missingArgMsg(ErrorReporting.scala:265)
scala: 	at dotty.tools.dotc.typer.Implicits.missingArgMsg(Implicits.scala:901)
scala: 	at dotty.tools.dotc.typer.Implicits.missingArgMsg$(Implicits.scala:785)
scala: 	at dotty.tools.dotc.typer.Typer.missingArgMsg(Typer.scala:117)
scala: 	at dotty.tools.dotc.typer.Typer.issueErrors$1$$anonfun$1$$anonfun$1(Typer.scala:3520)
scala: 	at dotty.tools.dotc.reporting.NoExplanation.msg(Message.scala:141)
scala: 	at dotty.tools.dotc.reporting.Message.message(Message.scala:89)
scala: 	at dotty.tools.dotc.reporting.Diagnostic.message(Diagnostic.scala:99)
scala: 	at dotty.tools.dotc.typer.Inliner$Intrinsics$.packError(Inliner.scala:374)
scala: 	at dotty.tools.dotc.typer.Inliner$Intrinsics$.$anonfun$27(Inliner.scala:380)
scala: 	at scala.collection.immutable.List.map(List.scala:246)
scala: 	at dotty.tools.dotc.typer.Inliner$Intrinsics$.packErrors(Inliner.scala:380)
scala: 	at dotty.tools.dotc.typer.Inliner$Intrinsics$.typeCheckErrors(Inliner.scala:392)
scala: 	at dotty.tools.dotc.typer.Inliner$.inlineCall(Inliner.scala:103)
scala: 	at dotty.tools.dotc.typer.Inliner$InlineTyper.inlineIfNeeded(Inliner.scala:1706)
scala: 	at dotty.tools.dotc.typer.Inliner$InlineTyper.typedApply(Inliner.scala:1630)
scala: 	at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2832)
scala: 	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2895)
scala: 	at dotty.tools.dotc.typer.ReTyper.typedUnadapted(ReTyper.scala:123)
scala: 	at dotty.tools.dotc.typer.Inliner$InlineTyper.typedUnadapted(Inliner.scala:1710)
scala: 	at dotty.tools.dotc.typer.ProtoTypes$FunProto.$anonfun$7(ProtoTypes.scala:469)
scala: 	at dotty.tools.dotc.typer.ProtoTypes$FunProto.cacheTypedArg(ProtoTypes.scala:392)
scala: 	at dotty.tools.dotc.typer.ProtoTypes$FunProto.typedArg(ProtoTypes.scala:470)
scala: 	at dotty.tools.dotc.typer.Applications$ApplyToUntyped.typedArg(Applications.scala:866)
scala: 	at dotty.tools.dotc.typer.Applications$Application.addTyped$1(Applications.scala:557)
scala: 	at dotty.tools.dotc.typer.Applications$Application.matchArgs(Applications.scala:622)
scala: 	at dotty.tools.dotc.typer.Applications$Application.init(Applications.scala:460)
scala: 	at dotty.tools.dotc.typer.Applications$TypedApply.<init>(Applications.scala:748)
scala: 	at dotty.tools.dotc.typer.Applications$ApplyToUntyped.<init>(Applications.scala:865)
scala: 	at dotty.tools.dotc.typer.Applications.ApplyTo(Applications.scala:1065)
scala: 	at dotty.tools.dotc.typer.Applications.ApplyTo$(Applications.scala:327)
scala: 	at dotty.tools.dotc.typer.Typer.ApplyTo(Typer.scala:117)
scala: 	at dotty.tools.dotc.typer.Applications.simpleApply$1(Applications.scala:911)
scala: 	at dotty.tools.dotc.typer.Applications.realApply$1$$anonfun$3(Applications.scala:991)
scala: 	at dotty.tools.dotc.typer.Typer.tryEither(Typer.scala:3104)
scala: 	at dotty.tools.dotc.typer.Applications.realApply$1(Applications.scala:1002)
scala: 	at dotty.tools.dotc.typer.Applications.typedApply(Applications.scala:1040)
scala: 	at dotty.tools.dotc.typer.Applications.typedApply$(Applications.scala:327)
scala: 	at dotty.tools.dotc.typer.Inliner$InlineTyper.typedApply(Inliner.scala:1623)
scala: 	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2960)
scala: 	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2964)
scala: 	at dotty.tools.dotc.typer.Inliner$InlineTyper.typedSelect(Inliner.scala:1574)
scala: 	at dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:2801)
scala: 	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2894)
scala: 	at dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:3080)
scala: 	at dotty.tools.dotc.typer.Applications.realApply$1(Applications.scala:898)
scala: 	at dotty.tools.dotc.typer.Typer.$anonfun$47(Typer.scala:2278)
scala: 	at dotty.tools.dotc.typer.PrepareInlineable$.dropInlineIfError(PrepareInlineable.scala:248)
scala: 	at dotty.tools.dotc.typer.Typer.typedDefDef(Typer.scala:2278)
scala: 	at dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:2808)
scala: 	at dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:2986)
scala: 	at dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:3036)
scala: 	at dotty.tools.dotc.typer.Typer.typedBlockStats(Typer.scala:1067)
scala: 	at dotty.tools.dotc.typer.Typer.typedBlock(Typer.scala:1071)
scala: 	at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2840)
scala: 	at dotty.tools.dotc.typer.Typer.typedBlock(Typer.scala:1073)
scala: 	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2957)
scala: 	at dotty.tools.dotc.typer.Inliner.inlined(Inliner.scala:1070)
scala: 	at dotty.tools.dotc.typer.Inliner$.inlineCall(Inliner.scala:166)
scala: 	at dotty.tools.dotc.typer.Typer.adaptNoArgsOther$1(Typer.scala:3666)
scala: 	at dotty.tools.dotc.typer.Typer.adaptNoArgs$1(Typer.scala:3783)
scala: 	at dotty.tools.dotc.typer.Typer.adapt1(Typer.scala:3995)
scala: 	at dotty.tools.dotc.typer.Typer.adapt(Typer.scala:3329)
scala: 	at dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:3013)
scala: 	at dotty.tools.dotc.typer.Typer.typedApply(Typer.scala:117)
scala: 	at dotty.tools.dotc.typer.Typer.typedInfixOp(Typer.scala:2717)
scala: 	at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2871)
scala: 	at dotty.tools.dotc.typer.Typer.typedClassDef(Typer.scala:2476)
scala: 	at dotty.tools.dotc.typer.Typer.typedTypeOrClassDef$1(Typer.scala:2820)
scala: 	at dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:2824)
scala: 	at dotty.tools.dotc.typer.Typer.typedPackageDef(Typer.scala:2603)
scala: 	at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2865)
scala: 	at dotty.tools.dotc.typer.TyperPhase.typeCheck$$anonfun$1(TyperPhase.scala:43)
scala: 	at dotty.tools.dotc.typer.TyperPhase.typeCheck$$anonfun$adapted$1(TyperPhase.scala:50)
scala: 	at scala.Function0.apply$mcV$sp(Function0.scala:39)
scala: 	at dotty.tools.dotc.core.Phases$Phase.monitor(Phases.scala:414)
scala: 	at dotty.tools.dotc.typer.TyperPhase.typeCheck(TyperPhase.scala:50)
scala: 	at dotty.tools.dotc.typer.TyperPhase.runOn$$anonfun$3(TyperPhase.scala:84)
scala: 	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
scala: 	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
scala: 	at scala.collection.immutable.List.foreach(List.scala:333)
scala: 	at dotty.tools.dotc.typer.TyperPhase.runOn(TyperPhase.scala:84)
scala: 	at dotty.tools.dotc.Run.runPhases$1$$anonfun$1(Run.scala:225)
scala: 	at scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1328)
scala: 	at dotty.tools.dotc.Run.runPhases$1(Run.scala:236)
scala: 	at dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:244)
scala: 	at dotty.tools.dotc.Run.compileUnits$$anonfun$adapted$1(Run.scala:253)
scala: 	at dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:68)
scala: 	at dotty.tools.dotc.Run.compileUnits(Run.scala:253)
scala: 	at dotty.tools.dotc.Run.compileSources(Run.scala:186)
scala: 	at dotty.tools.dotc.Run.compile(Run.scala:170)
scala: 	at dotty.tools.dotc.Driver.doCompile(Driver.scala:35)
scala: 	at dotty.tools.xsbt.CompilerBridgeDriver.run(CompilerBridgeDriver.java:88)
scala: 	at dotty.tools.xsbt.CompilerBridge.run(CompilerBridge.java:22)
scala: 	at sbt.internal.inc.AnalyzingCompiler.compile(AnalyzingCompiler.scala:91)
scala: 	at sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$7(MixedAnalyzingCompiler.scala:192)
scala: 	at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.scala:18)
scala: 	at sbt.internal.inc.MixedAnalyzingCompiler.timed(MixedAnalyzingCompiler.scala:247)
scala: 	at sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4(MixedAnalyzingCompiler.scala:182)
scala: 	at sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4$adapted(MixedAnalyzingCompiler.scala:163)
scala: 	at sbt.internal.inc.JarUtils$.withPreviousJar(JarUtils.scala:239)
scala: 	at sbt.internal.inc.MixedAnalyzingCompiler.compileScala$1(MixedAnalyzingCompiler.scala:163)
scala: 	at sbt.internal.inc.MixedAnalyzingCompiler.compile(MixedAnalyzingCompiler.scala:210)
scala: 	at sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1(IncrementalCompilerImpl.scala:528)
scala: 	at sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1$adapted(IncrementalCompilerImpl.scala:528)
scala: 	at sbt.internal.inc.Incremental$.$anonfun$apply$5(Incremental.scala:177)
scala: 	at sbt.internal.inc.Incremental$.$anonfun$apply$5$adapted(Incremental.scala:175)
scala: 	at sbt.internal.inc.Incremental$$anon$2.run(Incremental.scala:461)
scala: 	at sbt.internal.inc.IncrementalCommon$CycleState.next(IncrementalCommon.scala:116)
scala: 	at sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:56)
scala: 	at sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:52)
scala: 	at sbt.internal.inc.IncrementalCommon.cycle(IncrementalCommon.scala:263)
scala: 	at sbt.internal.inc.Incremental$.$anonfun$incrementalCompile$8(Incremental.scala:416)
scala: 	at sbt.internal.inc.Incremental$.withClassfileManager(Incremental.scala:503)
scala: 	at sbt.internal.inc.Incremental$.incrementalCompile(Incremental.scala:403)
scala: 	at sbt.internal.inc.Incremental$.apply(Incremental.scala:169)
scala: 	at sbt.internal.inc.IncrementalCompilerImpl.compileInternal(IncrementalCompilerImpl.scala:528)
scala: 	at sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileIncrementally$1(IncrementalCompilerImpl.scala:482)
scala: 	at sbt.internal.inc.IncrementalCompilerImpl.handleCompilationError(IncrementalCompilerImpl.scala:332)
scala: 	at sbt.internal.inc.IncrementalCompilerImpl.compileIncrementally(IncrementalCompilerImpl.scala:420)
scala: 	at sbt.internal.inc.IncrementalCompilerImpl.compile(IncrementalCompilerImpl.scala:137)
scala: 	at org.jetbrains.jps.incremental.scala.local.SbtCompiler.$anonfun$doCompile$3(SbtCompiler.scala:91)
scala: 	at scala.util.Try$.apply(Try.scala:210)
scala: 	at org.jetbrains.jps.incremental.scala.local.SbtCompiler.doCompile(SbtCompiler.scala:89)
scala: 	at org.jetbrains.jps.incremental.scala.local.SbtCompiler.compile(SbtCompiler.scala:20)
scala: 	at org.jetbrains.jps.incremental.scala.local.LocalServer.doCompile(LocalServer.scala:52)
scala: 	at org.jetbrains.jps.incremental.scala.local.LocalServer.compile(LocalServer.scala:30)
scala: 	at org.jetbrains.jps.incremental.scala.remote.Main$.compileLogic(Main.scala:209)
scala: 	at org.jetbrains.jps.incremental.scala.remote.Main$.$anonfun$handleCommand$1(Main.scala:192)
scala: 	at org.jetbrains.jps.incremental.scala.remote.Main$.decorated$1(Main.scala:182)
scala: 	at org.jetbrains.jps.incremental.scala.remote.Main$.handleCommand(Main.scala:189)
scala: 	at org.jetbrains.jps.incremental.scala.remote.Main$.serverLogic(Main.scala:165)
scala: 	at org.jetbrains.jps.incremental.scala.remote.Main$.nailMain(Main.scala:105)
scala: 	at org.jetbrains.jps.incremental.scala.remote.Main.nailMain(Main.scala)
scala: 	at jdk.internal.reflect.GeneratedMethodAccessor13.invoke(Unknown Source)
scala: 	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
scala: 	at java.base/java.lang.reflect.Method.invoke(Method.java:568)
scala: 	at com.facebook.nailgun.NGSession.runImpl(NGSession.java:312)
scala: 	at com.facebook.nailgun.NGSession.run(NGSession.java:198)

In my case this does not prevent the compiler from going further though other users report compiler crashes with messages like

[error] class izumi.fundamentals.orphans.cats.Applicative cannot be unpickled because no class file was found for denot: val <none>

At this moment I cannot produce minimal repro and even reliable repro, I wasn't able to reproduce the crashes too.

[pshirshov]

@odersky , that's the issue I mentioned during our conversation.

In order to reproduce on izumi:

1. Clone izumi repo, check out commit 7mind/izumi@319bec4
2. Run ./sbtgen.sc --js
3. Type ++ 3 in the sbt shell followed by ;clean;test:compile

Watch the build log. There will be stacktraces like:

 java.lang.AssertionError: assertion failed: class DIException has non-class parent: val <none>
	at scala.runtime.Scala3RunTime$.assertFailed(Scala3RunTime.scala:8)
	at dotty.tools.dotc.core.SymDenotations$ClassDenotation.traverse$1(SymDenotations.scala:1912)
	at dotty.tools.dotc.core.SymDenotations$ClassDenotation.computeBaseData(SymDenotations.scala:1917)
	at dotty.tools.dotc.core.SymDenotations$BaseDataImpl.apply(SymDenotations.scala:2889)
	at dotty.tools.dotc.core.SymDenotations$ClassDenotation.baseData(SymDenotations.scala:1883)
	at dotty.tools.dotc.core.SymDenotations$ClassDenotation.baseClassSet(SymDenotations.scala:1899)
	at dotty.tools.dotc.core.SymDenotations$ClassDenotation.derivesFrom(SymDenotations.scala:1925)
	at dotty.tools.dotc.core.SymDenotations$SymDenotation.isValueClass(SymDenotations.scala:821)
	at dotty.tools.dotc.transform.ValueClasses$.isDerivedValueClass(ValueClasses.scala:19)
	at dotty.tools.dotc.core.TypeErasure.dotty$tools$dotc$core$TypeErasure$$sigName(TypeErasure.scala:822)
	at dotty.tools.dotc.core.TypeErasure$.sigName(TypeErasure.scala:204)
	at dotty.tools.dotc.core.Signature$.apply(Signature.scala:167)
	at dotty.tools.dotc.core.Types$MethodOrPoly.computeSignature$2(Types.scala:3678)
	at dotty.tools.dotc.core.Types$MethodOrPoly.signature(Types.scala:3699)
	at dotty.tools.dotc.core.Denotations$SingleDenotation.signature(Denotations.scala:615)
	at dotty.tools.dotc.core.Denotations$SingleDenotation.matchesLoosely(Denotations.scala:1033)
	at dotty.tools.dotc.core.Denotations$SingleDenotation.matches(Denotations.scala:1017)
	at dotty.tools.dotc.core.Denotations$Denotation.mergeDenot$1(Denotations.scala:406)
	at dotty.tools.dotc.core.Denotations$Denotation.meet(Denotations.scala:496)
	at dotty.tools.dotc.core.Denotations$DenotUnion.toDenot(Denotations.scala:1239)
	at dotty.tools.dotc.core.Denotations$DenotUnion.toDenot(Denotations.scala:1239)
	at dotty.tools.dotc.core.Types$Type.findDecl(Types.scala:641)
	at dotty.tools.dotc.core.Types$Type.decl(Types.scala:628)
	at dotty.tools.dotc.core.tasty.TreeUnpickler$TreeReader.readLengthTerm$1(TreeUnpickler.scala:1322)
	at dotty.tools.dotc.core.tasty.TreeUnpickler$TreeReader.readTerm(TreeUnpickler.scala:1394)
	at dotty.tools.dotc.core.tasty.TreeUnpickler$TreeReader.readLengthTerm$1(TreeUnpickler.scala:1233)
	at dotty.tools.dotc.core.tasty.TreeUnpickler$TreeReader.readTerm(TreeUnpickler.scala:1394)
	at dotty.tools.dotc.core.tasty.TreeUnpickler$TreeReader.$anonfun$19(TreeUnpickler.scala:984)
	at dotty.tools.tasty.TastyReader.collectWhile(TastyReader.scala:137)
	at dotty.tools.dotc.core.tasty.TreeUnpickler$TreeReader.readTemplate(TreeUnpickler.scala:987)
	at dotty.tools.dotc.core.tasty.TreeUnpickler$TreeReader.readNewDef(TreeUnpickler.scala:905)
	at dotty.tools.dotc.core.tasty.TreeUnpickler$TreeReader.readIndexedDef(TreeUnpickler.scala:824)
	at dotty.tools.dotc.core.tasty.TreeUnpickler$Completer.liftedTree1$1(TreeUnpickler.scala:138)
	at dotty.tools.dotc.core.tasty.TreeUnpickler$Completer.complete(TreeUnpickler.scala:142)
	at dotty.tools.dotc.core.SymDenotations$SymDenotation.completeFrom(SymDenotations.scala:173)
	at dotty.tools.dotc.core.Denotations$Denotation.completeInfo$1(Denotations.scala:187)
	at dotty.tools.dotc.core.Denotations$Denotation.info(Denotations.scala:189)
	at dotty.tools.dotc.core.Denotations$Denotation.completeInfo$1(Denotations.scala:187)
	at dotty.tools.dotc.core.Denotations$Denotation.info(Denotations.scala:189)
	at dotty.tools.dotc.core.SymDenotations$SymDenotation.ensureCompleted(SymDenotations.scala:380)
	at dotty.tools.dotc.core.SymDenotations$SymDenotation.flags(SymDenotations.scala:66)
	at dotty.tools.dotc.core.SymDenotations$SymDenotation.is(SymDenotations.scala:122)
	at dotty.tools.dotc.typer.Checking$NotPrivate$1.isLeaked(Checking.scala:617)
	at dotty.tools.dotc.typer.Checking$NotPrivate$1.apply(Checking.scala:632)
	at dotty.tools.dotc.typer.Checking$NotPrivate$1.apply(Checking.scala:628)
	at scala.collection.immutable.List.mapConserve(List.scala:472)
	at dotty.tools.dotc.core.Types$TypeMap.mapOverLambda(Types.scala:5585)
	at dotty.tools.dotc.core.Types$TypeMap.mapOver(Types.scala:5620)
	at dotty.tools.dotc.typer.Checking$NotPrivate$1.apply(Checking.scala:670)
	at dotty.tools.dotc.typer.Checking$.checkNoPrivateLeaks(Checking.scala:674)
	at dotty.tools.dotc.typer.TypeAssigner.avoidPrivateLeaks(TypeAssigner.scala:45)
	at dotty.tools.dotc.typer.TypeAssigner.avoidPrivateLeaks$(TypeAssigner.scala:16)
	at dotty.tools.dotc.typer.Typer.avoidPrivateLeaks(Typer.scala:121)
	at dotty.tools.dotc.core.tasty.TreeUnpickler$TreeReader.readNewDef(TreeUnpickler.scala:946)
	at dotty.tools.dotc.core.tasty.TreeUnpickler$TreeReader.readIndexedDef(TreeUnpickler.scala:824)
	at dotty.tools.dotc.core.tasty.TreeUnpickler$Completer.liftedTree1$1(TreeUnpickler.scala:138)
	at dotty.tools.dotc.core.tasty.TreeUnpickler$Completer.complete(TreeUnpickler.scala:142)
	at dotty.tools.dotc.core.SymDenotations$SymDenotation.completeFrom(SymDenotations.scala:173)
	at dotty.tools.dotc.core.Denotations$Denotation.completeInfo$1(Denotations.scala:187)
	at dotty.tools.dotc.core.Denotations$Denotation.info(Denotations.scala:189)
	at dotty.tools.dotc.core.Types$TermRef.underlying(Types.scala:2769)
	at dotty.tools.dotc.core.Types$Type.widenSingleton(Types.scala:1238)
	at dotty.tools.dotc.typer.ProtoTypes$Compatibility.normalizedCompatible(ProtoTypes.scala:59)
	at dotty.tools.dotc.typer.ProtoTypes$Compatibility.normalizedCompatible$(ProtoTypes.scala:26)
	at dotty.tools.dotc.typer.ProtoTypes$NoViewsAllowed$.normalizedCompatible(ProtoTypes.scala:120)
	at dotty.tools.dotc.typer.ProtoTypes$SelectionProto.qualifies$1(ProtoTypes.scala:209)
	at dotty.tools.dotc.typer.ProtoTypes$SelectionProto.liftedTree1$1(ProtoTypes.scala:213)
	at dotty.tools.dotc.typer.ProtoTypes$SelectionProto.isMatchedBy(ProtoTypes.scala:226)
	at dotty.tools.dotc.core.TypeComparer.isMatchedByProto(TypeComparer.scala:2032)
	at dotty.tools.dotc.core.TypeComparer.firstTry$1(TypeComparer.scala:329)
	at dotty.tools.dotc.core.TypeComparer.recur(TypeComparer.scala:1447)
	at dotty.tools.dotc.core.TypeComparer.isSubType(TypeComparer.scala:210)
	at dotty.tools.dotc.core.TypeComparer.isSubType(TypeComparer.scala:220)
	at dotty.tools.dotc.core.TypeComparer.topLevelSubType(TypeComparer.scala:130)
	at dotty.tools.dotc.core.TypeComparer.testSubType(TypeComparer.scala:146)
	at dotty.tools.dotc.core.TypeComparer$.testSubType(TypeComparer.scala:2932)
	at dotty.tools.dotc.typer.Typer.adaptNoArgsOther$1(Typer.scala:3770)
	at dotty.tools.dotc.typer.Typer.adaptNoArgs$1(Typer.scala:3849)
	at dotty.tools.dotc.typer.Typer.adapt1(Typer.scala:4071)
	at dotty.tools.dotc.typer.Typer.adapt(Typer.scala:3406)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3025)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3029)
	at dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:3145)
	at dotty.tools.dotc.typer.Typer.typeSelectOnTerm$1(Typer.scala:653)
	at dotty.tools.dotc.typer.Typer.typedSelect(Typer.scala:691)
	at dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:2864)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2957)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3025)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3029)
	at dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:3145)
	at dotty.tools.dotc.typer.Applications.tryWithProto$1(Applications.scala:1299)
	at dotty.tools.dotc.typer.Applications.tryWithTypeArgs$1$$anonfun$1(Applications.scala:1311)
	at dotty.tools.dotc.typer.Typer.tryEither(Typer.scala:3169)
	at dotty.tools.dotc.typer.Applications.tryWithTypeArgs$1(Applications.scala:1319)
	at dotty.tools.dotc.typer.Applications.tryWithName$1(Applications.scala:1326)
	at dotty.tools.dotc.typer.Applications.trySelectUnapply$1(Applications.scala:1340)
	at dotty.tools.dotc.typer.Applications.typedUnApply(Applications.scala:1353)
	at dotty.tools.dotc.typer.Applications.typedUnApply$(Applications.scala:346)
	at dotty.tools.dotc.typer.Typer.typedUnApply(Typer.scala:121)
	at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2895)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2958)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3025)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3029)
	at dotty.tools.dotc.typer.Typer.typedPattern(Typer.scala:3165)
	at dotty.tools.dotc.typer.Typer.typedCase(Typer.scala:1758)
	at dotty.tools.dotc.typer.Typer.typedCases$$anonfun$1(Typer.scala:1691)
	at dotty.tools.dotc.core.Decorators$ListDecorator$.loop$1(Decorators.scala:91)
	at dotty.tools.dotc.core.Decorators$ListDecorator$.mapconserve$extension(Decorators.scala:107)
	at dotty.tools.dotc.typer.Typer.typedCases(Typer.scala:1693)
	at dotty.tools.dotc.typer.Typer.$anonfun$35(Typer.scala:1860)
	at dotty.tools.dotc.typer.Applications.harmonic(Applications.scala:2287)
	at dotty.tools.dotc.typer.Applications.harmonic$(Applications.scala:346)
	at dotty.tools.dotc.typer.Typer.harmonic(Typer.scala:121)
	at dotty.tools.dotc.typer.Typer.typedTry(Typer.scala:1863)
	at dotty.tools.dotc.typer.Typer.typedTry(Typer.scala:1876)
	at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2935)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2958)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3025)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3029)
	at dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:3078)
	at dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:3101)
	at dotty.tools.dotc.typer.Typer.typedBlockStats(Typer.scala:1063)
	at dotty.tools.dotc.typer.Typer.typedBlock(Typer.scala:1067)
	at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2903)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2958)
	at dotty.tools.dotc.typer.ProtoTypes$FunProto.$anonfun$7(ProtoTypes.scala:491)
	at dotty.tools.dotc.typer.ProtoTypes$FunProto.cacheTypedArg(ProtoTypes.scala:414)
	at dotty.tools.dotc.typer.ProtoTypes$FunProto.typedArg(ProtoTypes.scala:492)
	at dotty.tools.dotc.typer.Applications$ApplyToUntyped.typedArg(Applications.scala:884)
	at dotty.tools.dotc.typer.Applications$ApplyToUntyped.typedArg(Applications.scala:884)
	at dotty.tools.dotc.typer.Applications$Application.addTyped$1(Applications.scala:576)
	at dotty.tools.dotc.typer.Applications$Application.matchArgs(Applications.scala:640)
	at dotty.tools.dotc.typer.Applications$Application.init(Applications.scala:479)
	at dotty.tools.dotc.typer.Applications$TypedApply.<init>(Applications.scala:766)
	at dotty.tools.dotc.typer.Applications$ApplyToUntyped.<init>(Applications.scala:883)
	at dotty.tools.dotc.typer.Applications.ApplyTo(Applications.scala:1095)
	at dotty.tools.dotc.typer.Applications.ApplyTo$(Applications.scala:346)
	at dotty.tools.dotc.typer.Typer.ApplyTo(Typer.scala:121)
	at dotty.tools.dotc.typer.Applications.simpleApply$1(Applications.scala:941)
	at dotty.tools.dotc.typer.Applications.realApply$1$$anonfun$3(Applications.scala:1021)
	at dotty.tools.dotc.typer.Typer.tryEither(Typer.scala:3169)
	at dotty.tools.dotc.typer.Applications.realApply$1(Applications.scala:1032)
	at dotty.tools.dotc.typer.Applications.typedApply(Applications.scala:1070)
	at dotty.tools.dotc.typer.Applications.typedApply$(Applications.scala:346)
	at dotty.tools.dotc.typer.Typer.typedApply(Typer.scala:121)
	at dotty.tools.dotc.typer.Typer.typedInfixOp(Typer.scala:2779)
	at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2934)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2958)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3025)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3029)
	at dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:3078)
	at dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:3101)
	at dotty.tools.dotc.typer.Typer.typedClassDef(Typer.scala:2532)
	at dotty.tools.dotc.typer.Typer.typedTypeOrClassDef$1(Typer.scala:2883)
	at dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:2887)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2957)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3025)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3029)
	at dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:3051)
	at dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:3101)
	at dotty.tools.dotc.typer.Typer.typedPackageDef(Typer.scala:2659)
	at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2928)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2958)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3025)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3029)
	at dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:3145)
	at dotty.tools.dotc.typer.TyperPhase.typeCheck$$anonfun$1(TyperPhase.scala:44)
	at dotty.tools.dotc.typer.TyperPhase.typeCheck$$anonfun$adapted$1(TyperPhase.scala:54)
	at scala.Function0.apply$mcV$sp(Function0.scala:42)
	at dotty.tools.dotc.core.Phases$Phase.monitor(Phases.scala:429)
	at dotty.tools.dotc.typer.TyperPhase.typeCheck(TyperPhase.scala:54)
	at dotty.tools.dotc.typer.TyperPhase.runOn$$anonfun$3(TyperPhase.scala:88)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.immutable.List.foreach(List.scala:333)
	at dotty.tools.dotc.typer.TyperPhase.runOn(TyperPhase.scala:88)
	at dotty.tools.dotc.Run.runPhases$1$$anonfun$1(Run.scala:238)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1321)
	at dotty.tools.dotc.Run.runPhases$1(Run.scala:249)
	at dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:257)
	at dotty.tools.dotc.Run.compileUnits$$anonfun$adapted$1(Run.scala:266)
	at dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:68)
	at dotty.tools.dotc.Run.compileUnits(Run.scala:266)
	at dotty.tools.dotc.Run.compileSources(Run.scala:190)
	at dotty.tools.dotc.Run.compile(Run.scala:174)
	at dotty.tools.dotc.Driver.doCompile(Driver.scala:35)
	at dotty.tools.xsbt.CompilerBridgeDriver.run(CompilerBridgeDriver.java:88)
	at dotty.tools.xsbt.CompilerBridge.run(CompilerBridge.java:22)
	at sbt.internal.inc.AnalyzingCompiler.compile(AnalyzingCompiler.scala:91)
	at sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$7(MixedAnalyzingCompiler.scala:193)
	at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
	at sbt.internal.inc.MixedAnalyzingCompiler.timed(MixedAnalyzingCompiler.scala:248)
	at sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4(MixedAnalyzingCompiler.scala:183)
	at sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4$adapted(MixedAnalyzingCompiler.scala:163)
	at sbt.internal.inc.JarUtils$.withPreviousJar(JarUtils.scala:239)
	at sbt.internal.inc.MixedAnalyzingCompiler.compileScala$1(MixedAnalyzingCompiler.scala:163)
	at sbt.internal.inc.MixedAnalyzingCompiler.compile(MixedAnalyzingCompiler.scala:211)
	at sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1(IncrementalCompilerImpl.scala:534)
	at sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1$adapted(IncrementalCompilerImpl.scala:534)
	at sbt.internal.inc.Incremental$.$anonfun$apply$5(Incremental.scala:179)
	at sbt.internal.inc.Incremental$.$anonfun$apply$5$adapted(Incremental.scala:177)
	at sbt.internal.inc.Incremental$$anon$2.run(Incremental.scala:463)
	at sbt.internal.inc.IncrementalCommon$CycleState.next(IncrementalCommon.scala:116)
	at sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:56)
	at sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:52)
	at sbt.internal.inc.IncrementalCommon.cycle(IncrementalCommon.scala:263)
	at sbt.internal.inc.Incremental$.$anonfun$incrementalCompile$8(Incremental.scala:418)
	at sbt.internal.inc.Incremental$.withClassfileManager(Incremental.scala:506)
	at sbt.internal.inc.Incremental$.incrementalCompile(Incremental.scala:405)
	at sbt.internal.inc.Incremental$.apply(Incremental.scala:171)
	at sbt.internal.inc.IncrementalCompilerImpl.compileInternal(IncrementalCompilerImpl.scala:534)
	at sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileIncrementally$1(IncrementalCompilerImpl.scala:488)
	at sbt.internal.inc.IncrementalCompilerImpl.handleCompilationError(IncrementalCompilerImpl.scala:332)
	at sbt.internal.inc.IncrementalCompilerImpl.compileIncrementally(IncrementalCompilerImpl.scala:425)
	at sbt.internal.inc.IncrementalCompilerImpl.compile(IncrementalCompilerImpl.scala:137)
	at sbt.Defaults$.compileIncrementalTaskImpl(Defaults.scala:2363)
	at sbt.Defaults$.$anonfun$compileIncrementalTask$2(Defaults.scala:2313)
	at sbt.internal.server.BspCompileTask$.$anonfun$compute$1(BspCompileTask.scala:30)
	at sbt.internal.io.Retry$.apply(Retry.scala:46)
	at sbt.internal.io.Retry$.apply(Retry.scala:28)
	at sbt.internal.io.Retry$.apply(Retry.scala:23)
	at sbt.internal.server.BspCompileTask$.compute(BspCompileTask.scala:30)
	at sbt.Defaults$.$anonfun$compileIncrementalTask$1(Defaults.scala:2311)
	at scala.Function1.$anonfun$compose$1(Function1.scala:49)
	at sbt.internal.util.$tilde$greater.$anonfun$$u2219$1(TypeFunctions.scala:62)
	at sbt.std.Transform$$anon$4.work(Transform.scala:68)
	at sbt.Execute.$anonfun$submit$2(Execute.scala:282)
	at sbt.internal.util.ErrorHandling$.wideConvert(ErrorHandling.scala:23)
	at sbt.Execute.work(Execute.scala:291)
	at sbt.Execute.$anonfun$submit$1(Execute.scala:282)
	at sbt.ConcurrentRestrictions$$anon$4.$anonfun$submitValid$1(ConcurrentRestrictions.scala:265)
	at sbt.CompletionService$$anon$2.call(CompletionService.scala:64)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:317)
	at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:577)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:317)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642)
	at java.base/java.lang.Thread.run(Thread.java:1589)
no sig for TypeRef(ThisType(TypeRef(NoPrefix,module class exceptions)),class DIException) because of ()

The build will succeed regardless. It might be interesting that the "problematic" classes differ from run to run. That makes me think that it might be some kind of a race condition in the compiler.

I still can't isolate it but it is easily reproducible and, as you requested, the stacktraces are available.

[Nexus6]

I'm seeing what looks to be an identical crash in one of my own projects.
Scala 3.2.2, SBT 1.8.2, Java 18.0.2 on Linux x86_64.

Stack trace

java.lang.AssertionError: assertion failed: trait AutoRollback has non-class parent: val scala.runtime.Scala3RunTime$.assertFailed(Scala3RunTime.scala:8) dotty.tools.dotc.core.SymDenotations$ClassDenotation.traverse$1(SymDenotations.scala:1912) dotty.tools.dotc.core.SymDenotations$ClassDenotation.computeBaseData(SymDenotations.scala:1917) dotty.tools.dotc.core.SymDenotations$BaseDataImpl.apply(SymDenotations.scala:2889) dotty.tools.dotc.core.SymDenotations$ClassDenotation.baseData(SymDenotations.scala:1883) dotty.tools.dotc.core.SymDenotations$ClassDenotation.baseClassSet(SymDenotations.scala:1899) dotty.tools.dotc.core.SymDenotations$ClassDenotation.derivesFrom(SymDenotations.scala:1925) dotty.tools.dotc.core.Types$Type.loop$1(Types.scala:268) dotty.tools.dotc.core.Types$Type.derivesFrom(Types.scala:292) dotty.tools.dotc.typer.Namer$ClassCompleter.checkedParentType$1(Namer.scala:1490) dotty.tools.dotc.typer.Namer$ClassCompleter.$anonfun$27(Namer.scala:1558) scala.collection.immutable.List.map(List.scala:246) dotty.tools.dotc.typer.Namer$ClassCompleter.completeInCreationContext(Namer.scala:1558) dotty.tools.dotc.typer.Namer$Completer.complete(Namer.scala:810) dotty.tools.dotc.core.SymDenotations$SymDenotation.completeFrom(SymDenotations.scala:173) dotty.tools.dotc.core.Denotations$Denotation.completeInfo$1(Denotations.scala:187) dotty.tools.dotc.core.Denotations$Denotation.info(Denotations.scala:189) dotty.tools.dotc.core.SymDenotations$SymDenotation.ensureCompleted(SymDenotations.scala:380) dotty.tools.dotc.typer.Typer.retrieveSym(Typer.scala:2836) dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:2861) dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2957) dotty.tools.dotc.typer.Typer.typed(Typer.scala:3025) dotty.tools.dotc.typer.Typer.typed(Typer.scala:3029) dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:3051) dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:3101) dotty.tools.dotc.typer.Typer.typedBlockStats(Typer.scala:1063) dotty.tools.dotc.typer.Typer.typedBlock(Typer.scala:1067) dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2903) dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2958) dotty.tools.dotc.typer.Typer.typed(Typer.scala:3025) dotty.tools.dotc.typer.Typer.typed(Typer.scala:3029) dotty.tools.dotc.typer.Typer.typedNew(Typer.scala:814) dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2899) dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2958) dotty.tools.dotc.typer.ProtoTypes$FunProto.$anonfun$7(ProtoTypes.scala:491) dotty.tools.dotc.typer.ProtoTypes$FunProto.cacheTypedArg(ProtoTypes.scala:414) dotty.tools.dotc.typer.ProtoTypes$FunProto.typedArg(ProtoTypes.scala:492) dotty.tools.dotc.typer.Applications$ApplyToUntyped.typedArg(Applications.scala:884) dotty.tools.dotc.typer.Applications$ApplyToUntyped.typedArg(Applications.scala:884) dotty.tools.dotc.typer.Applications$Application.addTyped$1(Applications.scala:576) dotty.tools.dotc.typer.Applications$Application.matchArgs(Applications.scala:640) dotty.tools.dotc.typer.Applications$Application.init(Applications.scala:479) dotty.tools.dotc.typer.Applications$TypedApply.(Applications.scala:766) dotty.tools.dotc.typer.Applications$ApplyToUntyped.(Applications.scala:883) dotty.tools.dotc.typer.Applications.ApplyTo(Applications.scala:1095) dotty.tools.dotc.typer.Applications.ApplyTo$(Applications.scala:346) dotty.tools.dotc.typer.Typer.ApplyTo(Typer.scala:121) dotty.tools.dotc.typer.Applications.simpleApply$1(Applications.scala:941) dotty.tools.dotc.typer.Applications.realApply$1$$anonfun$3(Applications.scala:1021) dotty.tools.dotc.typer.Typer.tryEither(Typer.scala:3169) dotty.tools.dotc.typer.Applications.realApply$1(Applications.scala:1032) dotty.tools.dotc.typer.Applications.typedApply(Applications.scala:1070) dotty.tools.dotc.typer.Applications.typedApply$(Applications.scala:346) dotty.tools.dotc.typer.Typer.typedApply(Typer.scala:121) dotty.tools.dotc.typer.Typer.typedInfixOp(Typer.scala:2779) dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2934) dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2958) dotty.tools.dotc.typer.Typer.typed(Typer.scala:3025) dotty.tools.dotc.typer.Typer.typed(Typer.scala:3029) dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:3078) dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:3101) dotty.tools.dotc.typer.Typer.typedBlockStats(Typer.scala:1063) dotty.tools.dotc.typer.Typer.typedBlock(Typer.scala:1067) dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2903) dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2958) dotty.tools.dotc.typer.ProtoTypes$FunProto.$anonfun$7(ProtoTypes.scala:491) dotty.tools.dotc.typer.ProtoTypes$FunProto.cacheTypedArg(ProtoTypes.scala:414) dotty.tools.dotc.typer.ProtoTypes$FunProto.typedArg(ProtoTypes.scala:492) dotty.tools.dotc.typer.Applications$ApplyToUntyped.typedArg(Applications.scala:884) dotty.tools.dotc.typer.Applications$ApplyToUntyped.typedArg(Applications.scala:884) dotty.tools.dotc.typer.Applications$Application.addTyped$1(Applications.scala:576) dotty.tools.dotc.typer.Applications$Application.matchArgs(Applications.scala:640) dotty.tools.dotc.typer.Applications$Application.init(Applications.scala:479) dotty.tools.dotc.typer.Applications$TypedApply.(Applications.scala:766) dotty.tools.dotc.typer.Applications$ApplyToUntyped.(Applications.scala:883) dotty.tools.dotc.typer.Applications.ApplyTo(Applications.scala:1095) dotty.tools.dotc.typer.Applications.ApplyTo$(Applications.scala:346) dotty.tools.dotc.typer.Typer.ApplyTo(Typer.scala:121) dotty.tools.dotc.typer.Applications.simpleApply$1(Applications.scala:941) dotty.tools.dotc.typer.Applications.realApply$1$$anonfun$3(Applications.scala:1021) dotty.tools.dotc.typer.Typer.tryEither(Typer.scala:3169) dotty.tools.dotc.typer.Applications.realApply$1(Applications.scala:1032) dotty.tools.dotc.typer.Applications.typedApply(Applications.scala:1070) dotty.tools.dotc.typer.Applications.typedApply$(Applications.scala:346) dotty.tools.dotc.typer.Typer.typedApply(Typer.scala:121) dotty.tools.dotc.typer.Typer.typedInfixOp(Typer.scala:2779) dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2934) dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2958) dotty.tools.dotc.typer.Typer.typed(Typer.scala:3025) dotty.tools.dotc.typer.Typer.typed(Typer.scala:3029) dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:3078) dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:3101) dotty.tools.dotc.typer.Typer.typedClassDef(Typer.scala:2532) dotty.tools.dotc.typer.Typer.typedTypeOrClassDef$1(Typer.scala:2883) dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:2887) dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2957) dotty.tools.dotc.typer.Typer.typed(Typer.scala:3025) dotty.tools.dotc.typer.Typer.typed(Typer.scala:3029) dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:3051) dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:3101) dotty.tools.dotc.typer.Typer.typedPackageDef(Typer.scala:2659) dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2928) dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2958) dotty.tools.dotc.typer.Typer.typed(Typer.scala:3025) dotty.tools.dotc.typer.Typer.typed(Typer.scala:3029) dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:3145) dotty.tools.dotc.typer.TyperPhase.typeCheck$$anonfun$1(TyperPhase.scala:44) dotty.tools.dotc.typer.TyperPhase.typeCheck$$anonfun$adapted$1(TyperPhase.scala:54) scala.Function0.apply$mcV$sp(Function0.scala:42) dotty.tools.dotc.core.Phases$Phase.monitor(Phases.scala:429) dotty.tools.dotc.typer.TyperPhase.typeCheck(TyperPhase.scala:54) dotty.tools.dotc.typer.TyperPhase.runOn$$anonfun$3(TyperPhase.scala:88) scala.runtime.function.JProcedure1.apply(JProcedure1.java:15) scala.runtime.function.JProcedure1.apply(JProcedure1.java:10) scala.collection.immutable.List.foreach(List.scala:333) dotty.tools.dotc.typer.TyperPhase.runOn(TyperPhase.scala:88) dotty.tools.dotc.Run.runPhases$1$$anonfun$1(Run.scala:238) scala.runtime.function.JProcedure1.apply(JProcedure1.java:15) scala.runtime.function.JProcedure1.apply(JProcedure1.java:10) scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1321) dotty.tools.dotc.Run.runPhases$1(Run.scala:249) dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:257) dotty.tools.dotc.Run.compileUnits$$anonfun$adapted$1(Run.scala:266) dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:68) dotty.tools.dotc.Run.compileUnits(Run.scala:266) dotty.tools.dotc.Run.compileSources(Run.scala:190) dotty.tools.dotc.Run.compile(Run.scala:174) dotty.tools.dotc.Driver.doCompile(Driver.scala:35) dotty.tools.xsbt.CompilerBridgeDriver.run(CompilerBridgeDriver.java:88) dotty.tools.xsbt.CompilerBridge.run(CompilerBridge.java:22) sbt.internal.inc.AnalyzingCompiler.compile(AnalyzingCompiler.scala:91) sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$7(MixedAnalyzingCompiler.scala:193) scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23) sbt.internal.inc.MixedAnalyzingCompiler.timed(MixedAnalyzingCompiler.scala:248) sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4(MixedAnalyzingCompiler.scala:183) sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4$adapted(MixedAnalyzingCompiler.scala:163) sbt.internal.inc.JarUtils$.withPreviousJar(JarUtils.scala:239) sbt.internal.inc.MixedAnalyzingCompiler.compileScala$1(MixedAnalyzingCompiler.scala:163) sbt.internal.inc.MixedAnalyzingCompiler.compile(MixedAnalyzingCompiler.scala:211) sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1(IncrementalCompilerImpl.scala:534) sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1$adapted(IncrementalCompilerImpl.scala:534) sbt.internal.inc.Incremental$.$anonfun$apply$5(Incremental.scala:179) sbt.internal.inc.Incremental$.$anonfun$apply$5$adapted(Incremental.scala:177) sbt.internal.inc.Incremental$$anon$2.run(Incremental.scala:463) sbt.internal.inc.IncrementalCommon$CycleState.next(IncrementalCommon.scala:116) sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:56) sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:52) sbt.internal.inc.IncrementalCommon.cycle(IncrementalCommon.scala:263) sbt.internal.inc.Incremental$.$anonfun$incrementalCompile$8(Incremental.scala:418) sbt.internal.inc.Incremental$.withClassfileManager(Incremental.scala:506) sbt.internal.inc.Incremental$.incrementalCompile(Incremental.scala:405) sbt.internal.inc.Incremental$.apply(Incremental.scala:171) sbt.internal.inc.IncrementalCompilerImpl.compileInternal(IncrementalCompilerImpl.scala:534) sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileIncrementally$1(IncrementalCompilerImpl.scala:488) sbt.internal.inc.IncrementalCompilerImpl.handleCompilationError(IncrementalCompilerImpl.scala:332) sbt.internal.inc.IncrementalCompilerImpl.compileIncrementally(IncrementalCompilerImpl.scala:425) sbt.internal.inc.IncrementalCompilerImpl.compile(IncrementalCompilerImpl.scala:137) sbt.Defaults$.compileIncrementalTaskImpl(Defaults.scala:2363) sbt.Defaults$.$anonfun$compileIncrementalTask$2(Defaults.scala:2313) sbt.internal.server.BspCompileTask$.$anonfun$compute$1(BspCompileTask.scala:30) sbt.internal.io.Retry$.apply(Retry.scala:46) sbt.internal.io.Retry$.apply(Retry.scala:28) sbt.internal.io.Retry$.apply(Retry.scala:23) sbt.internal.server.BspCompileTask$.compute(BspCompileTask.scala:30) sbt.Defaults$.$anonfun$compileIncrementalTask$1(Defaults.scala:2311) scala.Function1.$anonfun$compose$1(Function1.scala:49) sbt.internal.util.$tilde$greater.$anonfun$$u2219$1(TypeFunctions.scala:62) sbt.std.Transform$$anon$4.work(Transform.scala:68) sbt.Execute.$anonfun$submit$2(Execute.scala:282) sbt.internal.util.ErrorHandling$.wideConvert(ErrorHandling.scala:23) sbt.Execute.work(Execute.scala:291) sbt.Execute.$anonfun$submit$1(Execute.scala:282) sbt.ConcurrentRestrictions$$anon$4.$anonfun$submitValid$1(ConcurrentRestrictions.scala:265) sbt.CompletionService$$anon$2.call(CompletionService.scala:64) java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264) java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:539) java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264) java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136) java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635) java.base/java.lang.Thread.run(Thread.java:833) (postgres / Test / compileIncremental) java.lang.AssertionError: assertion failed: trait AutoRollback has non-class parent: val

This is a project using ScalikeJDBC 4.0.0 and the assertion is thrown only when compiling tests (i.e. "sbt test"). I can compile the project successfully (i.e. "sbt clean compile") every time - the assertion has something to do with my test classes it seems. The referenced "AutoRollback" trait is from ScalikeJDBC, not from my code.

[odersky]

It's probably not a race condition but a an error that depends on the order of files to be compiled. And the problem seems to be (as almost always) that there is a cyclic reference that the compiler cannot resolve.

[odersky]

I think it would be important to minimize it but I don't have the time. Can someone help me here?

The problem of @pshirshov looks like it can easily be avoided since it happens during import suggestions and we can simply turn off the assert then.

The problem of @Nexus6 is more serious and harder to fix. Essentially we end up with an illegal state in a core operation -- computing the base types of a type. I could simply turn off the assert and return no base type, but I really would like to find out what goes wrong here because this could be a deeper problem. Turning off the assert would simply mask the underlying problem which will make it much less likely to be fixed.

[odersky]

A minimization should be a small number of self contained files that demonstrates the problem. Typically it goes like this:

1. Compile all files together
2. Compile only a specific subset of these files and observe the problem.

[pshirshov]

Ok, I'll try.

[odersky]

@pshirshov Thanks! But I actually think it would be easier to start with the problem experienced by @Nexus6. The problem you are seeing is when the compiler tries to find suggestions for imports. That process depends not just on the files you compile and their dependencies but the whole classpath. That makes it hard to reproduce by definition. As far as I can see the problem experienced by @Nexus6 is a full compiler crash for normal compilation. As a first step it would be good to find out whether it is still present in 3.3.0.

[Nexus6]

@odersky To create a reproducible test case, I used vscode+metals to create a minimal sbt project from the Scala3 template. To this I added the ScalikeJDBC, specs2, and munit dependencies from the project where I originally observed the crash. In addition, I added a stripped-down version of one of the test classes that was originally generated for me, from an existing db schema, by ScalikeJDBC.

Github is not allowing me to attach the project archive (.tar.gz - 1.2K) here but you can download it here or let me know of some other way I can get it to you if you're interested.

Just download, unpack, switch to the new project directory, run "sbt test" and the crash should happen every time. I tested this on my x86_64 machine and on an ARM64 machine - same crash. Interestingly, the test class shouldn't compile at all as I left the source file for the "Header" model class out of the project. But the crash occurs before the compiler even gets to the point of complaining about the missing class.

[pshirshov]

We spotted another strange trace in come code using izumi-reflect. We'll try to isolate it but as with the previous trace it might be tricky.

java.lang.AssertionError: assertion failed: class Array
        at scala.runtime.Scala3RunTime$.assertFailed(Scala3RunTime.scala:8)
        at dotty.tools.backend.jvm.BCodeHelpers.primitiveOrClassToBType$1(BCodeHelpers.scala:713)
        at dotty.tools.backend.jvm.BCodeHelpers.dotty$tools$backend$jvm$BCodeHelpers$$typeToTypeKind(BCodeHelpers.scala:733)
        at dotty.tools.backend.jvm.BCodeHelpers$BCInnerClassGen.toTypeKind(BCodeHelpers.scala:201)
        at dotty.tools.backend.jvm.BCodeHelpers$BCInnerClassGen.toTypeKind$(BCodeHelpers.scala:129)
        at dotty.tools.backend.jvm.BCodeSkelBuilder$PlainSkelBuilder.toTypeKind(BCodeSkelBuilder.scala:74)
        at dotty.tools.backend.jvm.BCodeBodyBuilder$PlainBodyBuilder.genConstant(BCodeBodyBuilder.scala:578)
        at dotty.tools.backend.jvm.BCodeBodyBuilder$PlainBodyBuilder.genLoadTo(BCodeBodyBuilder.scala:447)
        at dotty.tools.backend.jvm.BCodeBodyBuilder$PlainBodyBuilder.genLoad(BCodeBodyBuilder.scala:303)
        at dotty.tools.backend.jvm.BCodeBodyBuilder$PlainBodyBuilder.loop$1(BCodeBodyBuilder.scala:1202)
        at dotty.tools.backend.jvm.BCodeBodyBuilder$PlainBodyBuilder.genLoadArguments(BCodeBodyBuilder.scala:1209)
        at dotty.tools.backend.jvm.BCodeBodyBuilder$PlainBodyBuilder.genApply(BCodeBodyBuilder.scala:832)
        at dotty.tools.backend.jvm.BCodeBodyBuilder$PlainBodyBuilder.genLoadTo(BCodeBodyBuilder.scala:382)
        at dotty.tools.backend.jvm.BCodeBodyBuilder$PlainBodyBuilder.genLoadTo(BCodeBodyBuilder.scala:462)
        at dotty.tools.backend.jvm.BCodeBodyBuilder$PlainBodyBuilder.genLoad(BCodeBodyBuilder.scala:303)
        at dotty.tools.backend.jvm.BCodeBodyBuilder$PlainBodyBuilder.loop$1(BCodeBodyBuilder.scala:1202)
        at dotty.tools.backend.jvm.BCodeBodyBuilder$PlainBodyBuilder.genLoadArguments(BCodeBodyBuilder.scala:1209)
        at dotty.tools.backend.jvm.BCodeBodyBuilder$PlainBodyBuilder.genApply(BCodeBodyBuilder.scala:832)
        at dotty.tools.backend.jvm.BCodeBodyBuilder$PlainBodyBuilder.genLoadTo(BCodeBodyBuilder.scala:382)
        at dotty.tools.backend.jvm.BCodeBodyBuilder$PlainBodyBuilder.genLoad(BCodeBodyBuilder.scala:303)
        at dotty.tools.backend.jvm.BCodeBodyBuilder$PlainBodyBuilder.genStat(BCodeBodyBuilder.scala:117)
        at dotty.tools.backend.jvm.BCodeBodyBuilder$PlainBodyBuilder.genBlockTo$$anonfun$1(BCodeBodyBuilder.scala:1087)
        at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
        at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
        at scala.collection.immutable.List.foreach(List.scala:333)
        at dotty.tools.backend.jvm.BCodeBodyBuilder$PlainBodyBuilder.genBlockTo(BCodeBodyBuilder.scala:1087)
        at dotty.tools.backend.jvm.BCodeBodyBuilder$PlainBodyBuilder.genLoadTo(BCodeBodyBuilder.scala:454)
        at dotty.tools.backend.jvm.BCodeSkelBuilder$PlainSkelBuilder.emitNormalMethodBody$1(BCodeSkelBuilder.scala:827)
        at dotty.tools.backend.jvm.BCodeSkelBuilder$PlainSkelBuilder.genDefDef(BCodeSkelBuilder.scala:850)
        at dotty.tools.backend.jvm.BCodeSkelBuilder$PlainSkelBuilder.gen(BCodeSkelBuilder.scala:632)
        at dotty.tools.backend.jvm.BCodeSkelBuilder$PlainSkelBuilder.gen$$anonfun$1(BCodeSkelBuilder.scala:638)
        at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
        at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
        at scala.collection.immutable.List.foreach(List.scala:333)
        at dotty.tools.backend.jvm.BCodeSkelBuilder$PlainSkelBuilder.gen(BCodeSkelBuilder.scala:638)
        at dotty.tools.backend.jvm.BCodeSkelBuilder$PlainSkelBuilder.genPlainClass(BCodeSkelBuilder.scala:233)
        at dotty.tools.backend.jvm.CodeGen.genClass(CodeGen.scala:138)
        at dotty.tools.backend.jvm.CodeGen.genClassDef$1(CodeGen.scala:55)
        at dotty.tools.backend.jvm.CodeGen.genClassDefs$1(CodeGen.scala:101)
        at dotty.tools.backend.jvm.CodeGen.genClassDefs$1$$anonfun$1(CodeGen.scala:99)
        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.backend.jvm.CodeGen.genClassDefs$1(CodeGen.scala:99)
        at dotty.tools.backend.jvm.CodeGen.genUnit(CodeGen.scala:104)
        at dotty.tools.backend.jvm.GenBCode.run(GenBCode.scala:76)
        at dotty.tools.dotc.core.Phases$Phase.runOn$$anonfun$1(Phases.scala:327)
        at scala.collection.immutable.List.map(List.scala:250)
        at dotty.tools.dotc.core.Phases$Phase.runOn(Phases.scala:331)
        at dotty.tools.backend.jvm.GenBCode.runOn(GenBCode.scala:87)
        at dotty.tools.dotc.Run.runPhases$1$$anonfun$1(Run.scala:246)
        at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
        at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
        at scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1321)
        at dotty.tools.dotc.Run.runPhases$1(Run.scala:262)
        at dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:270)
        at dotty.tools.dotc.Run.compileUnits$$anonfun$adapted$1(Run.scala:279)
        at dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:67)
        at dotty.tools.dotc.Run.compileUnits(Run.scala:279)
        at dotty.tools.dotc.Run.compileSources(Run.scala:194)
        at dotty.tools.dotc.Run.compile(Run.scala:179)
        at dotty.tools.dotc.Driver.doCompile(Driver.scala:37)
        at dotty.tools.xsbt.CompilerBridgeDriver.run(CompilerBridgeDriver.java:88)
        at dotty.tools.xsbt.CompilerBridge.run(CompilerBridge.java:22)
        at sbt.internal.inc.AnalyzingCompiler.compile(AnalyzingCompiler.scala:91)
        at sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$7(MixedAnalyzingCompiler.scala:193)
        at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
        at sbt.internal.inc.MixedAnalyzingCompiler.timed(MixedAnalyzingCompiler.scala:248)
        at sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4(MixedAnalyzingCompiler.scala:183)
        at sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4$adapted(MixedAnalyzingCompiler.scala:163)
        at sbt.internal.inc.JarUtils$.withPreviousJar(JarUtils.scala:239)
        at sbt.internal.inc.MixedAnalyzingCompiler.compileScala$1(MixedAnalyzingCompiler.scala:163)
        at sbt.internal.inc.MixedAnalyzingCompiler.compile(MixedAnalyzingCompiler.scala:211)
        at sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1(IncrementalCompilerImpl.scala:534)
        at sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1$adapted(IncrementalCompilerImpl.scala:534)
        at sbt.internal.inc.Incremental$.$anonfun$apply$5(Incremental.scala:180)
        at sbt.internal.inc.Incremental$.$anonfun$apply$5$adapted(Incremental.scala:178)
        at sbt.internal.inc.Incremental$$anon$2.run(Incremental.scala:464)
        at sbt.internal.inc.IncrementalCommon$CycleState.next(IncrementalCommon.scala:116)
        at sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:56)
        at sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:52)
        at sbt.internal.inc.IncrementalCommon.cycle(IncrementalCommon.scala:263)
        at sbt.internal.inc.Incremental$.$anonfun$incrementalCompile$8(Incremental.scala:419)
        at sbt.internal.inc.Incremental$.withClassfileManager(Incremental.scala:506)
        at sbt.internal.inc.Incremental$.incrementalCompile(Incremental.scala:406)
        at sbt.internal.inc.Incremental$.apply(Incremental.scala:172)
        at sbt.internal.inc.IncrementalCompilerImpl.compileInternal(IncrementalCompilerImpl.scala:534)
        at sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileIncrementally$1(IncrementalCompilerImpl.scala:488)
        at sbt.internal.inc.IncrementalCompilerImpl.handleCompilationError(IncrementalCompilerImpl.scala:332)
        at sbt.internal.inc.IncrementalCompilerImpl.compileIncrementally(IncrementalCompilerImpl.scala:425)
        at sbt.internal.inc.IncrementalCompilerImpl.compile(IncrementalCompilerImpl.scala:137)
        at sbt.Defaults$.compileIncrementalTaskImpl(Defaults.scala:2369)
        at sbt.Defaults$.$anonfun$compileIncrementalTask$2(Defaults.scala:2319)
        at sbt.internal.server.BspCompileTask$.$anonfun$compute$1(BspCompileTask.scala:31)
        at sbt.internal.io.Retry$.apply(Retry.scala:47)
        at sbt.internal.io.Retry$.apply(Retry.scala:29)
        at sbt.internal.io.Retry$.apply(Retry.scala:24)
        at sbt.internal.server.BspCompileTask$.compute(BspCompileTask.scala:31)
        at sbt.Defaults$.$anonfun$compileIncrementalTask$1(Defaults.scala:2317)
        at scala.Function1.$anonfun$compose$1(Function1.scala:49)
        at sbt.internal.util.$tilde$greater.$anonfun$$u2219$1(TypeFunctions.scala:63)
        at sbt.std.Transform$$anon$4.work(Transform.scala:69)
        at sbt.Execute.$anonfun$submit$2(Execute.scala:283)
        at sbt.internal.util.ErrorHandling$.wideConvert(ErrorHandling.scala:24)
        at sbt.Execute.work(Execute.scala:292)
        at sbt.Execute.$anonfun$submit$1(Execute.scala:283)
        at sbt.ConcurrentRestrictions$$anon$4.$anonfun$submitValid$1(ConcurrentRestrictions.scala:265)
        at sbt.CompletionService$$anon$2.call(CompletionService.scala:65)
        at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
        at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
        at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
        at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
        at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
        at java.base/java.lang.Thread.run(Thread.java:829)

[pshirshov]

Actually, this time the repro is stable and laughably simple: https://scastie.scala-lang.org/lUnGyx2XSXu81ZLWKCvw8A

@odersky