Compiler crashed when pattern matching on an abstract scrutinee, with a sealed trait extended by a private class

[SimonGuilloud]

Compiler version

3.5.1

Minimized code

trait S:
  sealed trait A 
  private class CA() extends A 

object O extends S

trait T

def f(e: T) = e match 
  case _: O.A => ()
  case _ => ()

Output

unhandled exception while running MegaPhase{protectedAccessors, extmethods, uncacheGivenAliases, checkStatic, elimByName, hoistSuperArgs, forwardDepChecks, specializeApplyMethods, tryCatchPatterns, patternMatcher} on /tmp/scastie9178258913818202660/src/main/scala/main.scala

  An unhandled exception was thrown in the compiler.
  Please file a crash report here:
  https://github.com/scala/scala3/issues/new/choose
  For non-enriched exceptions, compile with -Xno-enrich-error-messages.

     while compiling: /tmp/scastie9178258913818202660/src/main/scala/main.scala
        during phase: MegaPhase{protectedAccessors, extmethods, uncacheGivenAliases, checkStatic, elimByName, hoistSuperArgs, forwardDepChecks, specializeApplyMethods, tryCatchPatterns, patternMatcher}
                mode: Mode(ImplicitsEnabled)
     library version: version 2.13.14
    compiler version: version 3.5.1
            settings: -bootclasspath /home/sbtRunnerContainer/.cache/coursier/v1/https/repo1.maven.org/maven2/org/scala-lang/scala3-library_3/3.5.1/scala3-library_3-3.5.1.jar:/home/sbtRunnerContainer/.cache/coursier/v1/https/repo1.maven.org/maven2/org/scala-lang/scala-library/2.13.14/scala-library-2.13.14.jar -classpath /tmp/scastie9178258913818202660/target/scala-3.5.1/classes:/home/sbtRunnerContainer/.ivy2/local/org.scastie/runtime-scala_3/1.0.0-SNAPSHOT/jars/runtime-scala_3.jar:/home/sbtRunnerContainer/.ivy2/local/org.scastie/api_3/0.30.0-SNAPSHOT/jars/api_3.jar:/home/sbtRunnerContainer/.cache/coursier/v1/https/repo1.maven.org/maven2/com/typesafe/play/play-json_3/2.10.0-RC5/play-json_3-2.10.0-RC5.jar:/home/sbtRunnerContainer/.cache/coursier/v1/https/repo1.maven.org/maven2/com/typesafe/play/play-functional_3/2.10.0-RC5/play-functional_3-2.10.0-RC5.jar:/home/sbtRunnerContainer/.cache/coursier/v1/https/repo1.maven.org/maven2/com/fasterxml/jackson/core/jackson-core/2.11.4/jackson-core-2.11.4.jar:/home/sbtRunnerContainer/.cache/coursier/v1/https/repo1.maven.org/maven2/com/fasterxml/jackson/core/jackson-annotations/2.11.4/jackson-annotations-2.11.4.jar:/home/sbtRunnerContainer/.cache/coursier/v1/https/repo1.maven.org/maven2/com/fasterxml/jackson/datatype/jackson-datatype-jdk8/2.11.4/jackson-datatype-jdk8-2.11.4.jar:/home/sbtRunnerContainer/.cache/coursier/v1/https/repo1.maven.org/maven2/com/fasterxml/jackson/datatype/jackson-datatype-jsr310/2.11.4/jackson-datatype-jsr310-2.11.4.jar:/home/sbtRunnerContainer/.cache/coursier/v1/https/repo1.maven.org/maven2/com/fasterxml/jackson/core/jackson-databind/2.11.4/jackson-databind-2.11.4.jar -d /tmp/scastie9178258913818202660/target/scala-3.5.1/classes -deprecation true -feature true


[error] scala.MatchError: NoType (of class dotty.tools.dotc.core.Types$NoType$)
[error] dotty.tools.dotc.core.TypeComparer.disjointnessBoundary$1(TypeComparer.scala:2923)
[error] dotty.tools.dotc.core.TypeComparer.provablyDisjoint(TypeComparer.scala:2926)
[error] dotty.tools.dotc.core.TypeComparer.provablyDisjoint(TypeComparer.scala:2866)
[error] dotty.tools.dotc.core.TypeComparer$.provablyDisjoint(TypeComparer.scala:3251)
[error] dotty.tools.dotc.transform.patmat.SpaceEngine$$anon$1.applyOrElse(Space.scala:609)
[error] dotty.tools.dotc.transform.patmat.SpaceEngine$$anon$1.applyOrElse(Space.scala:607)
[error] scala.collection.immutable.List.collect(List.scala:268)
[error] dotty.tools.dotc.transform.patmat.SpaceEngine$.rec$1(Space.scala:609)
[error] dotty.tools.dotc.transform.patmat.SpaceEngine$.decompose(Space.scala:656)
[error] dotty.tools.dotc.transform.patmat.SpaceEngine$Parts$.unapply(Space.scala:674)
[error] dotty.tools.dotc.transform.patmat.Typ.decompose(Space.scala:98)
[error] dotty.tools.dotc.transform.patmat.SpaceEngine$.decompose(Space.scala:115)
[error] dotty.tools.dotc.transform.patmat.SpaceEngine$.computeSimplify(Space.scala:130)
[error] dotty.tools.dotc.transform.patmat.Space.simplify(Space.scala:67)
[error] dotty.tools.dotc.transform.patmat.Space.simplify$(Space.scala:49)
[error] dotty.tools.dotc.transform.patmat.Typ.simplify(Space.scala:89)
[error] dotty.tools.dotc.transform.patmat.SpaceEngine$.simplify(Space.scala:112)
[error] dotty.tools.dotc.transform.patmat.SpaceEngine$.$anonfun$3(Space.scala:125)
[error] scala.collection.immutable.List.map(List.scala:247)
[error] scala.collection.immutable.List.map(List.scala:79)
[error] dotty.tools.dotc.transform.patmat.SpaceEngine$.computeSimplify(Space.scala:125)
[error] dotty.tools.dotc.transform.patmat.Space.simplify(Space.scala:67)
[error] dotty.tools.dotc.transform.patmat.Space.simplify$(Space.scala:49)
[error] dotty.tools.dotc.transform.patmat.Or.simplify(Space.scala:109)
[error] dotty.tools.dotc.transform.patmat.SpaceEngine$.simplify(Space.scala:112)
[error] dotty.tools.dotc.transform.patmat.SpaceEngine$.checkReachability(Space.scala:877)
[error] dotty.tools.dotc.transform.patmat.SpaceEngine$.checkMatch(Space.scala:905)
[error] dotty.tools.dotc.transform.PatternMatcher.transformMatch(PatternMatcher.scala:58)
[error] dotty.tools.dotc.transform.MegaPhase.goMatch(MegaPhase.scala:816)
[error] dotty.tools.dotc.transform.MegaPhase.transformUnnamed$1(MegaPhase.scala:383)
[error] dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:454)
[error] dotty.tools.dotc.transform.MegaPhase.mapDefDef$1(MegaPhase.scala:265)
[error] dotty.tools.dotc.transform.MegaPhase.transformNamed$1(MegaPhase.scala:268)
[error] dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:452)
[error] dotty.tools.dotc.transform.MegaPhase.loop$1(MegaPhase.scala:465)
[error] dotty.tools.dotc.transform.MegaPhase.transformStats(MegaPhase.scala:465)
[error] dotty.tools.dotc.transform.MegaPhase.transformUnnamed$1(MegaPhase.scala:376)
[error] dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:454)
[error] dotty.tools.dotc.transform.MegaPhase.transformNamed$1(MegaPhase.scala:272)
[error] dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:452)
[error] dotty.tools.dotc.transform.MegaPhase.loop$1(MegaPhase.scala:465)
[error] dotty.tools.dotc.transform.MegaPhase.transformStats(MegaPhase.scala:465)
[error] dotty.tools.dotc.transform.MegaPhase.mapPackage$1(MegaPhase.scala:396)
[error] dotty.tools.dotc.transform.MegaPhase.transformUnnamed$1(MegaPhase.scala:399)
[error] dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:454)
[error] dotty.tools.dotc.transform.MegaPhase.transformUnit(MegaPhase.scala:481)
[error] dotty.tools.dotc.transform.MegaPhase.run(MegaPhase.scala:493)
[error] dotty.tools.dotc.core.Phases$Phase.runOn$$anonfun$1(Phases.scala:380)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
[error] scala.collection.immutable.List.foreach(List.scala:334)
[error] dotty.tools.dotc.core.Phases$Phase.runOn(Phases.scala:373)
[error] dotty.tools.dotc.Run.runPhases$1$$anonfun$1(Run.scala:343)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
[error] scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1323)
[error] dotty.tools.dotc.Run.runPhases$1(Run.scala:336)
[error] dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:384)
[error] dotty.tools.dotc.Run.compileUnits$$anonfun$adapted$1(Run.scala:396)
[error] dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:69)
[error] dotty.tools.dotc.Run.compileUnits(Run.scala:396)
[error] dotty.tools.dotc.Run.compileSources(Run.scala:282)
[error] dotty.tools.dotc.Run.compile(Run.scala:267)
[error] dotty.tools.dotc.Driver.doCompile(Driver.scala:37)
[error] dotty.tools.xsbt.CompilerBridgeDriver.run(CompilerBridgeDriver.java:141)
[error] dotty.tools.xsbt.CompilerBridge.run(CompilerBridge.java:22)
[error] sbt.internal.inc.AnalyzingCompiler.compile(AnalyzingCompiler.scala:91)
[error] sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$7(MixedAnalyzingCompiler.scala:194)
[error] scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
[error] sbt.internal.inc.MixedAnalyzingCompiler.timed(MixedAnalyzingCompiler.scala:249)
[error] sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4(MixedAnalyzingCompiler.scala:184)
[error] sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4$adapted(MixedAnalyzingCompiler.scala:164)
[error] sbt.internal.inc.JarUtils$.withPreviousJar(JarUtils.scala:239)
[error] sbt.internal.inc.MixedAnalyzingCompiler.compileScala$1(MixedAnalyzingCompiler.scala:164)
[error] sbt.internal.inc.MixedAnalyzingCompiler.compile(MixedAnalyzingCompiler.scala:212)
[error] sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1(IncrementalCompilerImpl.scala:534)
[error] sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1$adapted(IncrementalCompilerImpl.scala:534)
[error] sbt.internal.inc.Incremental$.$anonfun$apply$3(Incremental.scala:178)
[error] sbt.internal.inc.Incremental$.$anonfun$apply$3$adapted(Incremental.scala:176)
[error] sbt.internal.inc.Incremental$$anon$2.run(Incremental.scala:454)
[error] sbt.internal.inc.IncrementalCommon$CycleState.next(IncrementalCommon.scala:117)
[error] sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:56)
[error] sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:52)
[error] sbt.internal.inc.IncrementalCommon.cycle(IncrementalCommon.scala:265)
[error] sbt.internal.inc.Incremental$.$anonfun$incrementalCompile$8(Incremental.scala:409)
[error] sbt.internal.inc.Incremental$.withClassfileManager(Incremental.scala:496)
[error] sbt.internal.inc.Incremental$.incrementalCompile(Incremental.scala:396)
[error] sbt.internal.inc.Incremental$.apply(Incremental.scala:170)
[error] sbt.internal.inc.IncrementalCompilerImpl.compileInternal(IncrementalCompilerImpl.scala:534)
[error] sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileIncrementally$1(IncrementalCompilerImpl.scala:488)
[error] sbt.internal.inc.IncrementalCompilerImpl.handleCompilationError(IncrementalCompilerImpl.scala:332)
[error] sbt.internal.inc.IncrementalCompilerImpl.compileIncrementally(IncrementalCompilerImpl.scala:425)
[error] sbt.internal.inc.IncrementalCompilerImpl.compile(IncrementalCompilerImpl.scala:137)
[error] sbt.Defaults$.compileIncrementalTaskImpl(Defaults.scala:2427)
[error] sbt.Defaults$.$anonfun$compileIncrementalTask$2(Defaults.scala:2377)
[error] sbt.internal.server.BspCompileTask$.$anonfun$compute$1(BspCompileTask.scala:41)
[error] sbt.internal.io.Retry$.apply(Retry.scala:47)
[error] sbt.internal.io.Retry$.apply(Retry.scala:29)
[error] sbt.internal.io.Retry$.apply(Retry.scala:24)
[error] sbt.internal.server.BspCompileTask$.compute(BspCompileTask.scala:41)
[error] sbt.Defaults$.$anonfun$compileIncrementalTask$1(Defaults.scala:2375)
[error] scala.Function1.$anonfun$compose$1(Function1.scala:49)
[error] sbt.internal.util.$tilde$greater.$anonfun$$u2219$1(TypeFunctions.scala:63)
[error] sbt.std.Transform$$anon$4.work(Transform.scala:69)
[error] sbt.Execute.$anonfun$submit$2(Execute.scala:283)
[error] sbt.internal.util.ErrorHandling$.wideConvert(ErrorHandling.scala:24)
[error] sbt.Execute.work(Execute.scala:292)
[error] sbt.Execute.$anonfun$submit$1(Execute.scala:283)
[error] sbt.ConcurrentRestrictions$$anon$4.$anonfun$submitValid$1(ConcurrentRestrictions.scala:265)
[error] sbt.CompletionService$$anon$2.call(CompletionService.scala:65)
[error] java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
[error] java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:539)
[error] java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
[error] java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
[error] java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
[error] java.base/java.lang.Thread.run(Thread.java:840)
[error]            
[error] stack trace is suppressed; run last Compile / compileIncremental for the full output
[error] (Compile / compileIncremental) scala.MatchError: NoType (of class dotty.tools.dotc.core.Types$NoType$)
[error] Total time: 0 s, completed Oct 16, 2024, 7:48:41 PM

Expectation

Compiler does not crash. As far as I know, the combination of all elements of the minimized code are require to reproduce the error.