Crash when both sequence and product match are possible

[SrTobi]

Compiler version

3.3.1

Minimized code

object Test:
  class Custom extends scala.Product1[String]:
    def length: Int = ???
    def apply(i: Int): Boolean = ???
    def drop(n: Int): scala.Seq[Boolean] = ???
    def toSeq: scala.Seq[Boolean] = ???

    def canEqual(that: Any): Boolean = ???

    val _1: String = ???
    val _2: String = ???
    val _3: Seq[String] = ???

  class Unapplied:
    def isEmpty: Boolean = ???
    def get: Custom = ???

  object A:
    def unapplySeq(i: Int): Unapplied = ???

  val A(rest: _*) = 1

Note that the compiler doesn't crash, when A.unapplySeq returns Custom directly!

Output (click arrow to expand)

scala: ## Exception when compiling 8 sources to /home/<removed>/target/scala-3.3.1/classes
java.lang.AssertionError: assertion failed
scala.runtime.Scala3RunTime$.assertFailed(Scala3RunTime.scala:11)
dotty.tools.dotc.transform.PatternMatcher$Translator.unapplyProductSeqPlan$1(PatternMatcher.scala:317)
dotty.tools.dotc.transform.PatternMatcher$Translator.$anonfun$11(PatternMatcher.scala:373)
dotty.tools.dotc.transform.PatternMatcher$Translator.letAbstract(PatternMatcher.scala:114)
dotty.tools.dotc.transform.PatternMatcher$Translator.unapplyPlan$1$$anonfun$1(PatternMatcher.scala:374)
dotty.tools.dotc.transform.PatternMatcher$Translator.letAbstract(PatternMatcher.scala:114)
dotty.tools.dotc.transform.PatternMatcher$Translator.unapplyPlan$1(PatternMatcher.scala:385)
dotty.tools.dotc.transform.PatternMatcher$Translator.patternPlan(PatternMatcher.scala:422)
dotty.tools.dotc.transform.PatternMatcher$Translator.caseDefPlan(PatternMatcher.scala:458)
dotty.tools.dotc.transform.PatternMatcher$Translator.matchPlan$$anonfun$1$$anonfun$1(PatternMatcher.scala:465)
scala.collection.immutable.List.foldRight(List.scala:352)
dotty.tools.dotc.transform.PatternMatcher$Translator.matchPlan$$anonfun$1(PatternMatcher.scala:465)
dotty.tools.dotc.transform.PatternMatcher$Translator.letAbstract(PatternMatcher.scala:114)
dotty.tools.dotc.transform.PatternMatcher$Translator.matchPlan(PatternMatcher.scala:466)
dotty.tools.dotc.transform.PatternMatcher$Translator.translateMatch(PatternMatcher.scala:1052)
dotty.tools.dotc.transform.PatternMatcher.transformMatch(PatternMatcher.scala:48)
dotty.tools.dotc.transform.MegaPhase.goMatch(MegaPhase.scala:804)
dotty.tools.dotc.transform.MegaPhase.transformUnnamed$1(MegaPhase.scala:371)
dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:442)
dotty.tools.dotc.transform.MegaPhase.mapValDef$1(MegaPhase.scala:239)
dotty.tools.dotc.transform.MegaPhase.transformNamed$1(MegaPhase.scala:244)
dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:440)
dotty.tools.dotc.transform.MegaPhase.loop$1(MegaPhase.scala:453)
dotty.tools.dotc.transform.MegaPhase.transformStats(MegaPhase.scala:453)
dotty.tools.dotc.transform.MegaPhase.transformUnnamed$1(MegaPhase.scala:364)
dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:442)
dotty.tools.dotc.transform.MegaPhase.transformNamed$1(MegaPhase.scala:260)
dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:440)
dotty.tools.dotc.transform.MegaPhase.loop$1(MegaPhase.scala:453)
dotty.tools.dotc.transform.MegaPhase.transformStats(MegaPhase.scala:453)
dotty.tools.dotc.transform.MegaPhase.mapPackage$1(MegaPhase.scala:384)
dotty.tools.dotc.transform.MegaPhase.transformUnnamed$1(MegaPhase.scala:387)
dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:442)
dotty.tools.dotc.transform.MegaPhase.loop$1(MegaPhase.scala:453)
dotty.tools.dotc.transform.MegaPhase.transformStats(MegaPhase.scala:453)
dotty.tools.dotc.transform.MegaPhase.mapPackage$1(MegaPhase.scala:384)
dotty.tools.dotc.transform.MegaPhase.transformUnnamed$1(MegaPhase.scala:387)
dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:442)
dotty.tools.dotc.transform.MegaPhase.transformUnit(MegaPhase.scala:469)
dotty.tools.dotc.transform.MegaPhase.run(MegaPhase.scala:481)
dotty.tools.dotc.core.Phases$Phase.runOn$$anonfun$1(Phases.scala:327)
scala.collection.immutable.List.map(List.scala:246)
dotty.tools.dotc.core.Phases$Phase.runOn(Phases.scala:331)
dotty.tools.dotc.Run.runPhases$1$$anonfun$1(Run.scala:246)
scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1321)
dotty.tools.dotc.Run.runPhases$1(Run.scala:262)
dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:270)
dotty.tools.dotc.Run.compileUnits$$anonfun$adapted$1(Run.scala:279)
dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:67)
dotty.tools.dotc.Run.compileUnits(Run.scala:279)
dotty.tools.dotc.Run.compileSources(Run.scala:194)
dotty.tools.dotc.Run.compile(Run.scala:179)
dotty.tools.dotc.Driver.doCompile(Driver.scala:37)
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$sp.scala:18)
sbt.internal.inc.MixedAnalyzingCompiler.timed(MixedAnalyzingCompiler.scala:248)
sbt.internal.inc.MixedAnalyzingCompiler.$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$5(Incremental.scala:180)
sbt.internal.inc.Incremental$.$anonfun$apply$5$adapted(Incremental.scala:178)
sbt.internal.inc.Incremental$$anon$2.run(Incremental.scala:464)
sbt.internal.inc.IncrementalCommon$CycleState.next(IncrementalCommon.scala:116)
sbt.internal.inc.IncrementalCommon$$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$8(Incremental.scala:419)
sbt.internal.inc.Incremental$.withClassfileManager(Incremental.scala:506)
sbt.internal.inc.Incremental$.incrementalCompile(Incremental.scala:406)
sbt.internal.inc.Incremental$.apply(Incremental.scala:172)
sbt.internal.inc.IncrementalCompilerImpl.compileInternal(IncrementalCompilerImpl.scala:534)
sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileIncrementally$1(IncrementalCompilerImpl.scala:488)
sbt.internal.inc.IncrementalCompilerImpl.handleCompilationError(IncrementalCompilerImpl.scala:332)
sbt.internal.inc.IncrementalCompilerImpl.compileIncrementally(IncrementalCompilerImpl.scala:425)
sbt.internal.inc.IncrementalCompilerImpl.compile(IncrementalCompilerImpl.scala:137)
org.jetbrains.jps.incremental.scala.local.SbtCompiler.$anonfun$doCompile$3(SbtCompiler.scala:87)
scala.util.Try$.apply(Try.scala:210)
org.jetbrains.jps.incremental.scala.local.SbtCompiler.doCompile(SbtCompiler.scala:85)
org.jetbrains.jps.incremental.scala.local.SbtCompiler.compile(SbtCompiler.scala:17)
org.jetbrains.jps.incremental.scala.local.LocalServer.doCompile(LocalServer.scala:50)
org.jetbrains.jps.incremental.scala.local.LocalServer.compile(LocalServer.scala:28)
org.jetbrains.jps.incremental.scala.remote.Main$.compileLogic(Main.scala:210)
org.jetbrains.jps.incremental.scala.remote.Main$.$anonfun$handleCommand$1(Main.scala:193)
org.jetbrains.jps.incremental.scala.remote.Main$.decorated$1(Main.scala:180)
org.jetbrains.jps.incremental.scala.remote.Main$.handleCommand(Main.scala:190)
org.jetbrains.jps.incremental.scala.remote.Main$.serverLogic(Main.scala:163)
org.jetbrains.jps.incremental.scala.remote.Main$.nailMain(Main.scala:103)
org.jetbrains.jps.incremental.scala.remote.Main.nailMain(Main.scala)
jdk.internal.reflect.GeneratedMethodAccessor9.invoke(Unknown Source)
java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
java.base/java.lang.reflect.Method.invoke(Method.java:568)
com.facebook.nailgun.NGSession.runImpl(NGSession.java:312)
com.facebook.nailgun.NGSession.run(NGSession.java:198)
           

[SrTobi]

Related issues: #19220, #19221