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Matching against an extractor with no arguments crashes the compiler #5078

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scabug opened this issue Oct 15, 2011 · 2 comments
Closed

Matching against an extractor with no arguments crashes the compiler #5078

scabug opened this issue Oct 15, 2011 · 2 comments
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@scabug scabug commented Oct 15, 2011

Define an extractor object that has a no-args unapply method, then try to match against it. Whatever expression you write on the left-hand side of the match (even if this expression refers to not declared symbols!), the compiler will crash.as follows:

scala> object Foo { def unapply(): Option[Int] = Some(42) }
defined module Foo

scala> val Foo(x) = WHATEVER
<console>:11: error: not found: value WHATEVER
       val Foo(x) = WHATEVER
                    ^
scala.MatchError: ()Option[Int] (of class scala.tools.nsc.symtab.Types$MethodType)
	at scala.tools.nsc.typechecker.Typers$Typer.freshArgType$1(Typers.scala:2510)
	at scala.tools.nsc.typechecker.Typers$Typer.doTypedApply(Typers.scala:2528)
	at scala.tools.nsc.typechecker.Typers$Typer.doTypedApply(Typers.scala:2500)
	at scala.tools.nsc.typechecker.Typers$Typer.typedApply$1(Typers.scala:3371)
	at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:4104)
	at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:4271)
	at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$typedPattern$1.apply(Typers.scala:4369)
	at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$typedPattern$1.apply(Typers.scala:4369)
	at scala.tools.nsc.typechecker.Contexts$Context.withImplicitsDisabled(Contexts.scala:156)
	at scala.tools.nsc.typechecker.Typers$Typer.typedPattern(Typers.scala:4369)
	at scala.tools.nsc.typechecker.Typers$Typer.typedCase(Typers.scala:1941)
	at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$typedCases$1.apply(Typers.scala:1975)
	at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$typedCases$1.apply(Typers.scala:1974)
	at scala.collection.immutable.List.loop$1(List.scala:117)
	at scala.collection.immutable.List.mapConserve(List.scala:133)
	at scala.tools.nsc.typechecker.Typers$Typer.typedCases(Typers.scala:1974)
	at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:4003)
	at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:4271)
	at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:4344)
	at scala.tools.nsc.typechecker.Typers$Typer.computeType(Typers.scala:4421)
	at scala.tools.nsc.typechecker.Namers$Namer.typeSig(Namers.scala:1207)
	at scala.tools.nsc.typechecker.Namers$Namer$$anonfun$typeCompleter$1.apply(Namers.scala:551)
	at scala.tools.nsc.typechecker.Namers$Namer$$anonfun$typeCompleter$1.apply(Namers.scala:549)
	at scala.tools.nsc.typechecker.Namers$$anon$1.complete(Namers.scala:1385)
	at scala.tools.nsc.typechecker.Namers$$anon$1.complete(Namers.scala:1381)
	at scala.tools.nsc.symtab.Symbols$Symbol.info(Symbols.scala:727)
	at scala.tools.nsc.symtab.Symbols$Symbol.initialize(Symbols.scala:839)
	at scala.tools.nsc.symtab.Symbols$Symbol.annotations(Symbols.scala:73)
	at scala.tools.nsc.typechecker.Typers$Typer.addGetterSetter(Typers.scala:1342)
	at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$13.apply(Typers.scala:1510)
	at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$13.apply(Typers.scala:1510)
	at scala.collection.TraversableLike$$anonfun$flatMap$1.apply(TraversableLike.scala:200)
	at scala.collection.TraversableLike$$anonfun$flatMap$1.apply(TraversableLike.scala:200)
	at scala.collection.LinearSeqOptimized$class.foreach(LinearSeqOptimized.scala:59)
	at scala.collection.immutable.List.foreach(List.scala:45)
	at scala.collection.TraversableLike$class.flatMap(TraversableLike.scala:200)
	at scala.collection.immutable.List.flatMap(List.scala:45)
	at scala.tools.nsc.typechecker.Typers$Typer.typedTemplate(Typers.scala:1510)
	at scala.tools.nsc.typechecker.Typers$Typer.typedModuleDef(Typers.scala:1320)
	at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:3913)
	at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:4271)
	at scala.tools.nsc.typechecker.Typers$Typer.typedStat$1(Typers.scala:2100)
	at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$24.apply(Typers.scala:2184)
	at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$24.apply(Typers.scala:2184)
	at scala.collection.immutable.List.loop$1(List.scala:117)
	at scala.collection.immutable.List.mapConserve(List.scala:133)
	at scala.tools.nsc.typechecker.Typers$Typer.typedStats(Typers.scala:2184)
	at scala.tools.nsc.typechecker.Typers$Typer.typedTemplate(Typers.scala:1512)
	at scala.tools.nsc.typechecker.Typers$Typer.typedModuleDef(Typers.scala:1320)
	at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:3913)
	at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:4271)
	at scala.tools.nsc.typechecker.Typers$Typer.typedStat$1(Typers.scala:2100)
	at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$24.apply(Typers.scala:2184)
	at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$24.apply(Typers.scala:2184)
	at scala.collection.immutable.List.loop$1(List.scala:117)
	at scala.collection.immutable.List.mapConserve(List.scala:133)
	at scala.tools.nsc.typechecker.Typers$Typer.typedStats(Typers.scala:2184)
	at scala.tools.nsc.typechecker.Typers$Typer.typedTemplate(Typers.scala:1512)
	at scala.tools.nsc.typechecker.Typers$Typer.typedModuleDef(Typers.scala:1320)
	at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:3913)
	at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:4271)
	at scala.tools.nsc.typechecker.Typers$Typer.typedStat$1(Typers.scala:2100)
	at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$24.apply(Typers.scala:2184)
	at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$24.apply(Typers.scala:2184)
	at scala.collection.immutable.List.loop$1(List.scala:117)
	at scala.collection.immutable.List.mapConserve(List.scala:133)
	at scala.tools.nsc.typechecker.Typers$Typer.typedStats(Typers.scala:2184)
	at scala.tools.nsc.typechecker.Typers$Typer.typedTemplate(Typers.scala:1512)
	at scala.tools.nsc.typechecker.Typers$Typer.typedModuleDef(Typers.scala:1320)
	at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:3913)
	at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:4271)
	at scala.tools.nsc.typechecker.Typers$Typer.typedStat$1(Typers.scala:2100)
	at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$24.apply(Typers.scala:2184)
	at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$24.apply(Typers.scala:2184)
	at scala.collection.immutable.List.loop$1(List.scala:117)
	at scala.collection.immutable.List.mapConserve(List.scala:133)
	at scala.tools.nsc.typechecker.Typers$Typer.typedStats(Typers.scala:2184)
	at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:3906)
	at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:4271)
	at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:4331)
	at scala.tools.nsc.typechecker.Analyzer$typerFactory$$anon$3.apply(Analyzer.scala:94)
	at scala.tools.nsc.Global$GlobalPhase.applyPhase(Global.scala:329)
	at scala.tools.nsc.typechecker.Analyzer$typerFactory$$anon$3$$anonfun$run$1.apply(Analyzer.scala:86)
	at scala.tools.nsc.typechecker.Analyzer$typerFactory$$anon$3$$anonfun$run$1.apply(Analyzer.scala:86)
	at scala.collection.Iterator$class.foreach(Iterator.scala:660)
	at scala.collection.mutable.ListBuffer$$anon$1.foreach(ListBuffer.scala:316)
	at scala.tools.nsc.typechecker.Analyzer$typerFactory$$anon$3.run(Analyzer.scala:86)
	at scala.tools.nsc.Global$Run.compileSources(Global.scala:953)
	at scala.tools.nsc.interpreter.IMain$ReadEvalPrint.compileAndSaveRun(IMain.scala:756)
	at scala.tools.nsc.interpreter.IMain$ReadEvalPrint.compile(IMain.scala:731)
	at scala.tools.nsc.interpreter.IMain$Request.compile(IMain.scala:873)
	at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:576)
	at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:543)
	at scala.tools.nsc.interpreter.ILoop.reallyInterpret$1(ILoop.scala:694)
	at scala.tools.nsc.interpreter.ILoop.interpretStartingWith(ILoop.scala:745)
	at scala.tools.nsc.interpreter.ILoop.command(ILoop.scala:651)
	at scala.tools.nsc.interpreter.ILoop.processLine$1(ILoop.scala:542)
	at scala.tools.nsc.interpreter.ILoop.loop(ILoop.scala:550)
	at scala.tools.nsc.interpreter.ILoop.process(ILoop.scala:822)
	at scala.tools.nsc.MainGenericRunner.runTarget$1(MainGenericRunner.scala:67)
	at scala.tools.nsc.MainGenericRunner.process(MainGenericRunner.scala:80)
	at scala.tools.nsc.MainGenericRunner$.main(MainGenericRunner.scala:89)
	at scala.tools.nsc.MainGenericRunner.main(MainGenericRunner.scala)
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@scabug scabug commented Oct 15, 2011

Imported From: https://issues.scala-lang.org/browse/SI-5078?orig=1
Reporter: Eugene Burmako (xeno.by)

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@scabug scabug commented Oct 15, 2011

Commit Message Bot (anonymous) said:
(extempore in r25834) Harden the typer against surprise unapply types.

Closes #5078, no review.

@scabug scabug closed this Oct 15, 2011
@scabug scabug added the quickfix label Apr 7, 2017
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