Crash on funky EmptyTuple extractor #13977

LPTK · 2021-11-19T04:25:02Z

Compiler version

3.1.0

Minimized code

class Token
class AST

extension [A] (self: A => Unit)
  def unapply(input: A): EmptyTuple = { self(input); EmptyTuple }

var cur = List.empty[Token]

val accept: List[Token] => Unit =
  cur = _

def block(ts: List[Token]): (AST, List[Token]) =
  cur match
    case t :: accept() => ???
    case _ => ???

https://scastie.scala-lang.org/NYbsLZAiTvCvZ6jyWthm0Q

Output (click arrow to expand)

java.lang.AssertionError: assertion failed
	at scala.runtime.Scala3RunTime$.assertFailed(Scala3RunTime.scala:11)
	at dotty.tools.dotc.transform.PatternMatcher$Translator.unapplyPlan$3$$anonfun$2(PatternMatcher.scala:348)
	at dotty.tools.dotc.transform.PatternMatcher$Translator.letAbstract(PatternMatcher.scala:107)
	at dotty.tools.dotc.transform.PatternMatcher$Translator.unapplyPlan$1(PatternMatcher.scala:366)
	at dotty.tools.dotc.transform.PatternMatcher$Translator.patternPlan(PatternMatcher.scala:401)
	at dotty.tools.dotc.transform.PatternMatcher$Translator.matchArgsPatternPlan$1(PatternMatcher.scala:261)
	at dotty.tools.dotc.transform.PatternMatcher$Translator.matchArgsPatternPlan$1(PatternMatcher.scala:261)
	at dotty.tools.dotc.transform.PatternMatcher$Translator.matchArgsSelectorsPlan$2(PatternMatcher.scala:255)
	at dotty.tools.dotc.transform.PatternMatcher$Translator.matchArgsSelectorsPlan$1$$anonfun$1(PatternMatcher.scala:254)
	at dotty.tools.dotc.transform.PatternMatcher$Translator.letAbstract(PatternMatcher.scala:107)
	at dotty.tools.dotc.transform.PatternMatcher$Translator.matchArgsSelectorsPlan$2(PatternMatcher.scala:254)
	at dotty.tools.dotc.transform.PatternMatcher$Translator.matchArgsSelectorsPlan$1$$anonfun$1(PatternMatcher.scala:254)
	at dotty.tools.dotc.transform.PatternMatcher$Translator.letAbstract(PatternMatcher.scala:107)
	at dotty.tools.dotc.transform.PatternMatcher$Translator.matchArgsSelectorsPlan$2(PatternMatcher.scala:254)
	at dotty.tools.dotc.transform.PatternMatcher$Translator.matchArgsPlan$1(PatternMatcher.scala:266)
	at dotty.tools.dotc.transform.PatternMatcher$Translator.unapplyPlan$1(PatternMatcher.scala:329)
	at dotty.tools.dotc.transform.PatternMatcher$Translator.patternPlan(PatternMatcher.scala:401)
	at dotty.tools.dotc.transform.PatternMatcher$Translator.patternPlan$$anonfun$1(PatternMatcher.scala:381)
	at dotty.tools.dotc.transform.PatternMatcher$Translator.letAbstract(PatternMatcher.scala:107)
	at dotty.tools.dotc.transform.PatternMatcher$Translator.patternPlan(PatternMatcher.scala:381)
	at dotty.tools.dotc.transform.PatternMatcher$Translator.caseDefPlan(PatternMatcher.scala:437)
	at dotty.tools.dotc.transform.PatternMatcher$Translator.matchPlan$$anonfun$2$$anonfun$1(PatternMatcher.scala:444)
	at scala.collection.immutable.List.foldRight(List.scala:352)
	at dotty.tools.dotc.transform.PatternMatcher$Translator.matchPlan$$anonfun$1(PatternMatcher.scala:444)
	at dotty.tools.dotc.transform.PatternMatcher$Translator.letAbstract(PatternMatcher.scala:107)
	at dotty.tools.dotc.transform.PatternMatcher$Translator.matchPlan(PatternMatcher.scala:445)
	at dotty.tools.dotc.transform.PatternMatcher$Translator.translateMatch(PatternMatcher.scala:1019)
	at dotty.tools.dotc.transform.PatternMatcher.transformMatch(PatternMatcher.scala:41)
	at dotty.tools.dotc.transform.MegaPhase.goMatch(MegaPhase.scala:779)
	at dotty.tools.dotc.transform.MegaPhase.transformUnnamed$1(MegaPhase.scala:369)
	at dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:429)
	at dotty.tools.dotc.transform.MegaPhase.mapDefDef$1(MegaPhase.scala:249)
	at dotty.tools.dotc.transform.MegaPhase.transformNamed$1(MegaPhase.scala:252)
	at dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:427)
	at dotty.tools.dotc.transform.MegaPhase.transformStat$2(MegaPhase.scala:437)
	at dotty.tools.dotc.transform.MegaPhase.recur$1(MegaPhase.scala:442)
	at dotty.tools.dotc.transform.MegaPhase.recur$1(MegaPhase.scala:442)
	at dotty.tools.dotc.transform.MegaPhase.recur$1(MegaPhase.scala:442)
	at dotty.tools.dotc.transform.MegaPhase.recur$1(MegaPhase.scala:442)
	at dotty.tools.dotc.transform.MegaPhase.recur$1(MegaPhase.scala:442)
	at dotty.tools.dotc.transform.MegaPhase.recur$1(MegaPhase.scala:442)
	at dotty.tools.dotc.transform.MegaPhase.recur$1(MegaPhase.scala:442)
	at dotty.tools.dotc.transform.MegaPhase.recur$1(MegaPhase.scala:442)
	at dotty.tools.dotc.transform.MegaPhase.recur$1(MegaPhase.scala:442)
	at dotty.tools.dotc.transform.MegaPhase.recur$1(MegaPhase.scala:442)
	at dotty.tools.dotc.transform.MegaPhase.transformStats(MegaPhase.scala:442)
	at dotty.tools.dotc.transform.MegaPhase.transformUnnamed$1(MegaPhase.scala:362)
	at dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:429)
	at dotty.tools.dotc.transform.MegaPhase.transformNamed$1(MegaPhase.scala:256)
	at dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:427)
	at dotty.tools.dotc.transform.MegaPhase.transformStat$2(MegaPhase.scala:437)
	at dotty.tools.dotc.transform.MegaPhase.recur$1(MegaPhase.scala:442)
	at dotty.tools.dotc.transform.MegaPhase.recur$1(MegaPhase.scala:442)
	at dotty.tools.dotc.transform.MegaPhase.transformStats(MegaPhase.scala:442)
	at dotty.tools.dotc.transform.MegaPhase.mapPackage$1(MegaPhase.scala:382)
	at dotty.tools.dotc.transform.MegaPhase.transformUnnamed$1(MegaPhase.scala:385)
	at dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:429)
	at dotty.tools.dotc.transform.MegaPhase.transformUnit(MegaPhase.scala:448)
	at dotty.tools.dotc.transform.MegaPhase.run(MegaPhase.scala:460)
	at dotty.tools.dotc.core.Phases$Phase.runOn$$anonfun$1(Phases.scala:308)
	at scala.collection.immutable.List.map(List.scala:246)
	at dotty.tools.dotc.core.Phases$Phase.runOn(Phases.scala:309)
	at dotty.tools.dotc.Run.runPhases$4$$anonfun$4(Run.scala:261)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1323)
	at dotty.tools.dotc.Run.runPhases$5(Run.scala:272)
	at dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:280)
	at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.scala:18)
	at dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:68)
	at dotty.tools.dotc.Run.compileUnits(Run.scala:289)
	at dotty.tools.dotc.Run.compileSources(Run.scala:222)
	at dotty.tools.dotc.Run.compile(Run.scala:206)
	at dotty.tools.dotc.Driver.doCompile(Driver.scala:39)
	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$7(MixedAnalyzingCompiler.scala:192)
	at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
	at sbt.internal.inc.MixedAnalyzingCompiler.timed(MixedAnalyzingCompiler.scala:247)
	at sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4(MixedAnalyzingCompiler.scala:182)
	at sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4$adapted(MixedAnalyzingCompiler.scala:163)
	at sbt.internal.inc.JarUtils$.withPreviousJar(JarUtils.scala:239)
	at sbt.internal.inc.MixedAnalyzingCompiler.compileScala$1(MixedAnalyzingCompiler.scala:163)
	at sbt.internal.inc.MixedAnalyzingCompiler.compile(MixedAnalyzingCompiler.scala:210)
	at sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1(IncrementalCompilerImpl.scala:528)
	at sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1$adapted(IncrementalCompilerImpl.scala:528)
	at sbt.internal.inc.Incremental$.$anonfun$apply$5(Incremental.scala:175)
	at sbt.internal.inc.Incremental$.$anonfun$apply$5$adapted(Incremental.scala:173)
	at sbt.internal.inc.Incremental$$anon$2.run(Incremental.scala:459)
	at sbt.internal.inc.IncrementalCommon$CycleState.next(IncrementalCommon.scala:116)
	at sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:56)
	at sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:52)
	at sbt.internal.inc.IncrementalCommon.cycle(IncrementalCommon.scala:263)
	at sbt.internal.inc.Incremental$.$anonfun$incrementalCompile$8(Incremental.scala:414)
	at sbt.internal.inc.Incremental$.withClassfileManager(Incremental.scala:501)
	at sbt.internal.inc.Incremental$.incrementalCompile(Incremental.scala:401)
	at sbt.internal.inc.Incremental$.apply(Incremental.scala:167)
	at sbt.internal.inc.IncrementalCompilerImpl.compileInternal(IncrementalCompilerImpl.scala:528)
	at sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileIncrementally$1(IncrementalCompilerImpl.scala:482)
	at sbt.internal.inc.IncrementalCompilerImpl.handleCompilationError(IncrementalCompilerImpl.scala:332)
	at sbt.internal.inc.IncrementalCompilerImpl.compileIncrementally(IncrementalCompilerImpl.scala:420)
	at sbt.internal.inc.IncrementalCompilerImpl.compile(IncrementalCompilerImpl.scala:137)
	at sbt.Defaults$.compileIncrementalTaskImpl(Defaults.scala:2357)
	at sbt.Defaults$.$anonfun$compileIncrementalTask$2(Defaults.scala:2314)
	at sbt.internal.io.Retry$.apply(Retry.scala:46)
	at sbt.internal.io.Retry$.apply(Retry.scala:28)
	at sbt.internal.io.Retry$.apply(Retry.scala:23)
	at sbt.internal.server.BspCompileTask$.compute(BspCompileTask.scala:31)
	at sbt.Defaults$.$anonfun$compileIncrementalTask$1(Defaults.scala:2310)
	at scala.Function1.$anonfun$compose$1(Function1.scala:49)
	at sbt.internal.util.$tilde$greater.$anonfun$$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$2.call(CompletionService.scala:64)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)

nicolasstucki · 2021-11-19T07:39:30Z

Might be related to #13969

nicolasstucki · 2021-11-19T07:42:43Z

Side note: the code above seems to have a side effects in the unapply. The unapplies are assumed to be pure for optimizations.

dwijnand · 2021-11-19T11:17:00Z

Duplicate of #13960

dwijnand · 2021-11-19T11:17:26Z

I'll pull your case, as an interesting variant.

LPTK · 2021-11-19T12:14:03Z

The unapplies are assumed to be pure for optimizations.

But how can anyone have any fun when all the unapplys are pure? 😞

dwijnand · 2021-11-19T14:07:35Z

Pedantically (I think I've seen Martin make this point in the past), unapply must be idempotent, not strictly pure.

LPTK · 2021-11-19T14:17:44Z

Pedantically I'm not sure what idempotent would mean in this context. Calling unapply on the result of unapply does not make much sense. What unapply should arguably be is referentially transparent – so it can use caches, force lazy vals, etc., but in any case it should produce the same results on the same values.

dwijnand · 2021-11-20T09:41:13Z

Yes, my bad, it must be referentially transparent.

LPTK added itype:bug itype:crash labels Nov 19, 2021

dwijnand marked this as a duplicate of #13960 Nov 19, 2021

dwijnand closed this as completed Nov 19, 2021

dwijnand mentioned this issue Nov 19, 2021

compiler throws AssertionError when Product Match zero-arity #13960

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Crash on funky EmptyTuple extractor #13977

Crash on funky EmptyTuple extractor #13977

LPTK commented Nov 19, 2021

nicolasstucki commented Nov 19, 2021

nicolasstucki commented Nov 19, 2021 •

edited

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dwijnand commented Nov 19, 2021

dwijnand commented Nov 19, 2021

LPTK commented Nov 19, 2021

dwijnand commented Nov 19, 2021

LPTK commented Nov 19, 2021

dwijnand commented Nov 20, 2021

Crash on funky EmptyTuple extractor #13977

Crash on funky EmptyTuple extractor #13977

Comments

LPTK commented Nov 19, 2021

Compiler version

Minimized code

Output (click arrow to expand)

nicolasstucki commented Nov 19, 2021

nicolasstucki commented Nov 19, 2021 • edited Loading

dwijnand commented Nov 19, 2021

dwijnand commented Nov 19, 2021

LPTK commented Nov 19, 2021

dwijnand commented Nov 19, 2021

LPTK commented Nov 19, 2021

dwijnand commented Nov 20, 2021

nicolasstucki commented Nov 19, 2021 •

edited

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