Compiler crash with custom `unapply` method

[road21]

Compiler version

3.6.2, 3.6.3 NEXT

Minimized code

case class Data[A]()

trait TCl[A, B]

object Matches:
  def unapply[A](adt: Data[?])[B](using
      ft: TCl[A, B]
  ): Option[Data[A]] = None

given TCl[Unit, String] = new TCl {}

Data() match
  case Matches[Unit](x) => println(x)

scastie: https://scastie.scala-lang.org/road21/zxQttu6JT4qdQWgloptmGA/7

Output (click arrow to expand)

java.lang.AssertionError: assertion failed at scala.runtime.Scala3RunTime$.assertFailed(Scala3RunTime.scala:11) at dotty.tools.dotc.core.Decorators$.assertingErrorsReported(Decorators.scala:299) at dotty.tools.dotc.typer.Applications.loop$1(Applications.scala:1587) at dotty.tools.dotc.typer.Applications.loop$1(Applications.scala:1586) at dotty.tools.dotc.typer.Applications.unapplyImplicits$1(Applications.scala:1589) at dotty.tools.dotc.typer.Applications.typedUnApply(Applications.scala:1638) at dotty.tools.dotc.typer.Applications.typedUnApply$(Applications.scala:434) at dotty.tools.dotc.typer.Typer.typedUnApply(Typer.scala:145) at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:3496) at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:3581) at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3658) at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3662) at dotty.tools.dotc.typer.Typer.typedPattern(Typer.scala:3793) at dotty.tools.dotc.typer.Typer.typedCase(Typer.scala:2228) at dotty.tools.dotc.typer.Typer.typedCases$$anonfun$1(Typer.scala:2154) at dotty.tools.dotc.core.Decorators$.loop$1(Decorators.scala:99) at dotty.tools.dotc.core.Decorators$.mapconserve(Decorators.scala:115) at dotty.tools.dotc.typer.Typer.typedCases(Typer.scala:2153) at dotty.tools.dotc.typer.Typer.$anonfun$39(Typer.scala:2142) at dotty.tools.dotc.typer.Applications.harmonic(Applications.scala:2603) at dotty.tools.dotc.typer.Applications.harmonic$(Applications.scala:434) at dotty.tools.dotc.typer.Typer.harmonic(Typer.scala:145) at dotty.tools.dotc.typer.Typer.typedMatchFinish(Typer.scala:2142) at dotty.tools.dotc.typer.Typer.typedMatch(Typer.scala:2069) at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:3511) at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:3581) at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3658) at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3662) at dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:3773) at dotty.tools.dotc.typer.Namer.typedAheadExpr$$anonfun$1(Namer.scala:1765) at dotty.tools.dotc.typer.Namer.typedAhead(Namer.scala:1755) at dotty.tools.dotc.typer.Namer.typedAheadExpr(Namer.scala:1765) at dotty.tools.dotc.typer.Namer.typedAheadRhs$1$$anonfun$1(Namer.scala:2123) at dotty.tools.dotc.inlines.PrepareInlineable$.dropInlineIfError(PrepareInlineable.scala:256) at dotty.tools.dotc.typer.Namer.typedAheadRhs$1(Namer.scala:2123) at dotty.tools.dotc.typer.Namer.rhsType$1(Namer.scala:2131) at dotty.tools.dotc.typer.Namer.cookedRhsType$1(Namer.scala:2150) at dotty.tools.dotc.typer.Namer.lhsType$1(Namer.scala:2151) at dotty.tools.dotc.typer.Namer.inferredResultType(Namer.scala:2162) at dotty.tools.dotc.typer.Namer.inferredType$1(Namer.scala:1808) at dotty.tools.dotc.typer.Namer.valOrDefDefSig(Namer.scala:1814) at dotty.tools.dotc.typer.Namer$Completer.typeSig(Namer.scala:823) at dotty.tools.dotc.typer.Namer$Completer.completeInCreationContext(Namer.scala:990) at dotty.tools.dotc.typer.Namer$Completer.complete(Namer.scala:859) at dotty.tools.dotc.core.SymDenotations$SymDenotation.completeFrom(SymDenotations.scala:175) at dotty.tools.dotc.core.Denotations$Denotation.completeInfo$1(Denotations.scala:190) at dotty.tools.dotc.core.Denotations$Denotation.info(Denotations.scala:192) at dotty.tools.dotc.core.SymDenotations$SymDenotation.ensureCompleted(SymDenotations.scala:393) at dotty.tools.dotc.typer.Typer.retrieveSym(Typer.scala:3443) at dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:3468) at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:3580) at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3658) at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3662) at dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:3684) at dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:3730) at dotty.tools.dotc.typer.Typer.typedBlockStats(Typer.scala:1427) at dotty.tools.dotc.typer.Typer.typedBlock(Typer.scala:1431) at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:3504) at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:3581) at dotty.tools.dotc.typer.ProtoTypes$FunProto.$anonfun$7(ProtoTypes.scala:534) at dotty.tools.dotc.typer.ProtoTypes$FunProto.cacheTypedArg(ProtoTypes.scala:457) at dotty.tools.dotc.typer.ProtoTypes$FunProto.typedArg(ProtoTypes.scala:535) at dotty.tools.dotc.typer.Applications$ApplyToUntyped.typedArg(Applications.scala:1007) at dotty.tools.dotc.typer.Applications$ApplyToUntyped.typedArg(Applications.scala:1007) at dotty.tools.dotc.typer.Applications$Application.addTyped$1(Applications.scala:688) at dotty.tools.dotc.typer.Applications$Application.matchArgs(Applications.scala:756) at dotty.tools.dotc.typer.Applications$Application.init(Applications.scala:574) at dotty.tools.dotc.typer.Applications$TypedApply.<init>(Applications.scala:882) at dotty.tools.dotc.typer.Applications$ApplyToUntyped.<init>(Applications.scala:1006) at dotty.tools.dotc.typer.Applications.ApplyTo(Applications.scala:1270) at dotty.tools.dotc.typer.Applications.ApplyTo$(Applications.scala:434) at dotty.tools.dotc.typer.Typer.ApplyTo(Typer.scala:145) at dotty.tools.dotc.typer.Applications.simpleApply$1(Applications.scala:1079) at dotty.tools.dotc.typer.Applications.realApply$1$$anonfun$2(Applications.scala:1189) at dotty.tools.dotc.typer.Typer$.tryEither(Typer.scala:118) at dotty.tools.dotc.typer.Applications.realApply$1(Applications.scala:1204) at dotty.tools.dotc.typer.Applications.typedApply(Applications.scala:1244) at dotty.tools.dotc.typer.Applications.typedApply$(Applications.scala:434) at dotty.tools.dotc.typer.Typer.typedApply(Typer.scala:145) at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:3496) at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:3581) at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3658) at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3662) at dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:3711) at dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:3730) at dotty.tools.dotc.typer.Typer.typedClassDef(Typer.scala:3160) at dotty.tools.dotc.typer.Typer.typedTypeOrClassDef$1(Typer.scala:3484) at dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:3488) at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:3580) at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3658) at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3662) at dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:3684) at dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:3730) at dotty.tools.dotc.typer.Typer.typedPackageDef(Typer.scala:3293) at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:3530) at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:3581) at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3658) at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3662) at dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:3773) at dotty.tools.dotc.typer.TyperPhase.typeCheck$$anonfun$1(TyperPhase.scala:47) at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15) at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10) at dotty.tools.dotc.core.Phases$Phase.monitor(Phases.scala:507) at dotty.tools.dotc.typer.TyperPhase.typeCheck(TyperPhase.scala:53) at dotty.tools.dotc.typer.TyperPhase.$anonfun$4(TyperPhase.scala:99) at scala.collection.Iterator$$anon$6.hasNext(Iterator.scala:479) at scala.collection.Iterator$$anon$9.hasNext(Iterator.scala:583) at scala.collection.immutable.List.prependedAll(List.scala:152) at scala.collection.immutable.List$.from(List.scala:685) at scala.collection.immutable.List$.from(List.scala:682) at scala.collection.IterableOps$WithFilter.map(Iterable.scala:900) at dotty.tools.dotc.typer.TyperPhase.runOn(TyperPhase.scala:98) at dotty.tools.dotc.Run.runPhases$1$$anonfun$1(Run.scala:343) at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15) at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10) at scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1323) at dotty.tools.dotc.Run.runPhases$1(Run.scala:336) at dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:384) at dotty.tools.dotc.Run.compileUnits$$anonfun$adapted$1(Run.scala:396) at dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:69) at dotty.tools.dotc.Run.compileUnits(Run.scala:396) at dotty.tools.dotc.Run.compileSources(Run.scala:282) at dotty.tools.dotc.Run.compile(Run.scala:267) 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.MixedAnalyzingCompiler.$anonfun$compile$7(MixedAnalyzingCompiler.scala:196) at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23) at sbt.internal.inc.MixedAnalyzingCompiler.timed(MixedAnalyzingCompiler.scala:252) at sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4(MixedAnalyzingCompiler.scala:186) at sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4$adapted(MixedAnalyzingCompiler.scala:166) at sbt.internal.inc.JarUtils$.withPreviousJar(JarUtils.scala:241) at sbt.internal.inc.MixedAnalyzingCompiler.compileScala$1(MixedAnalyzingCompiler.scala:166) at sbt.internal.inc.MixedAnalyzingCompiler.compile(MixedAnalyzingCompiler.scala:214) at sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1(IncrementalCompilerImpl.scala:542) at sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1$adapted(IncrementalCompilerImpl.scala:542) at sbt.internal.inc.Incremental$.$anonfun$apply$3(Incremental.scala:182) at sbt.internal.inc.Incremental$.$anonfun$apply$3$adapted(Incremental.scala:180) at sbt.internal.inc.Incremental$$anon$2.run(Incremental.scala:458) at sbt.internal.inc.IncrementalCommon$CycleState.next(IncrementalCommon.scala:117) at sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:56) at sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:52) at sbt.internal.inc.IncrementalCommon.cycle(IncrementalCommon.scala:263) at sbt.internal.inc.Incremental$.$anonfun$incrementalCompile$8(Incremental.scala:413) at sbt.internal.inc.Incremental$.withClassfileManager(Incremental.scala:500) at sbt.internal.inc.Incremental$.incrementalCompile(Incremental.scala:400) at sbt.internal.inc.Incremental$.apply(Incremental.scala:208) at sbt.internal.inc.IncrementalCompilerImpl.compileInternal(IncrementalCompilerImpl.scala:542) at sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileIncrementally$1(IncrementalCompilerImpl.scala:496) at sbt.internal.inc.IncrementalCompilerImpl.handleCompilationError(IncrementalCompilerImpl.scala:332) at sbt.internal.inc.IncrementalCompilerImpl.compileIncrementally(IncrementalCompilerImpl.scala:433) at sbt.internal.inc.IncrementalCompilerImpl.compile(IncrementalCompilerImpl.scala:137) at sbt.Defaults$.compileIncrementalTaskImpl(Defaults.scala:2443) at sbt.Defaults$.$anonfun$compileIncrementalTask$2(Defaults.scala:2393) at sbt.internal.server.BspCompileTask$.$anonfun$compute$1(BspCompileTask.scala:41) at sbt.internal.io.Retry$.apply(Retry.scala:47) at sbt.internal.io.Retry$.apply(Retry.scala:29) at sbt.internal.io.Retry$.apply(Retry.scala:24) at sbt.internal.server.BspCompileTask$.compute(BspCompileTask.scala:41) at sbt.Defaults$.$anonfun$compileIncrementalTask$1(Defaults.scala:2391) at scala.Function1.$anonfun$compose$1(Function1.scala:49) at sbt.internal.util.$tilde$greater.$anonfun$$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:539) at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264) at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136) at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635) at java.base/java.lang.Thread.run(Thread.java:840)``` ```