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Inline unapply with leading contextual parameter used as extractor crashes compiler #12991

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#16358
#15583
Closed
Inline unapply with leading contextual parameter used as extractor crashes compiler#12991
#16358
#15583
Assignees
nicolasstucki
Labels
area:inlineitype:bugitype:crash
Milestone
 
3.3.0
@prolativ

Description

@prolativ
prolativ
opened on Jul 1, 2021

Compiler version

3.0.1-RC2

Minimized code

object Foo:
  inline def unapply(using String)(i: Int): Some[Int] = Some(i)

given String = ""

val i = 10 match
  case Foo(x) => x

Output (click arrow to expand)

Exception in thread "main" java.util.NoSuchElementException: head of empty list
	at scala.collection.immutable.Nil$.head(List.scala:662)
	at scala.collection.immutable.Nil$.head(List.scala:661)
	at dotty.tools.dotc.typer.Inliner.computeParamBindings(Inliner.scala:522)
	at dotty.tools.dotc.typer.Inliner.inlined(Inliner.scala:745)
	at dotty.tools.dotc.typer.Inliner$.inlineCall(Inliner.scala:153)
	at dotty.tools.dotc.typer.Inliner$.$anonfun$4(Inliner.scala:207)
	at dotty.tools.dotc.ast.tpd$.DefDef(tpd.scala:285)
	at dotty.tools.dotc.typer.Inliner$.inlinedUnapply(Inliner.scala:208)
	at dotty.tools.dotc.typer.Typer$$anon$1.transform(Typer.scala:1588)
	at dotty.tools.dotc.typer.Typer.caseRest$1(Typer.scala:1615)
	at dotty.tools.dotc.typer.Typer.typedCase(Typer.scala:1633)
	at dotty.tools.dotc.typer.Typer.typedCases$$anonfun$1(Typer.scala:1563)
	at dotty.tools.dotc.core.Decorators$ListDecorator$.loop$1(Decorators.scala:92)
	at dotty.tools.dotc.core.Decorators$ListDecorator$.mapconserve$extension(Decorators.scala:108)
	at dotty.tools.dotc.typer.Typer.typedCases(Typer.scala:1565)
	at dotty.tools.dotc.typer.Typer.$anonfun$20(Typer.scala:1555)
	at dotty.tools.dotc.typer.Applications.harmonic(Applications.scala:2186)
	at dotty.tools.dotc.typer.Applications.harmonic$(Applications.scala:316)
	at dotty.tools.dotc.typer.Typer.harmonic(Typer.scala:106)
	at dotty.tools.dotc.typer.Typer.typedMatchFinish(Typer.scala:1555)
	at dotty.tools.dotc.typer.Typer.typedMatch(Typer.scala:1511)
	at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2709)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2758)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2823)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2827)
	at dotty.tools.dotc.typer.Namer.typedAheadExpr$$anonfun$1(Namer.scala:1394)
	at dotty.tools.dotc.typer.Namer.typedAhead(Namer.scala:1381)
	at dotty.tools.dotc.typer.Namer.typedAheadExpr(Namer.scala:1394)
	at dotty.tools.dotc.typer.Namer.typedAheadRhs$1$$anonfun$1(Namer.scala:1546)
	at dotty.tools.dotc.typer.PrepareInlineable$.dropInlineIfError(PrepareInlineable.scala:225)
	at dotty.tools.dotc.typer.Namer.typedAheadRhs$2(Namer.scala:1546)
	at dotty.tools.dotc.typer.Namer.rhsType$1(Namer.scala:1554)
	at dotty.tools.dotc.typer.Namer.cookedRhsType$1(Namer.scala:1581)
	at dotty.tools.dotc.typer.Namer.lhsType$1(Namer.scala:1582)
	at dotty.tools.dotc.typer.Namer.inferredType$1(Namer.scala:1593)
	at dotty.tools.dotc.typer.Namer.valOrDefDefSig(Namer.scala:1602)
	at dotty.tools.dotc.typer.Namer$Completer.typeSig(Namer.scala:699)
	at dotty.tools.dotc.typer.Namer$Completer.completeInCreationContext(Namer.scala:826)
	at dotty.tools.dotc.typer.Namer$Completer.complete(Namer.scala:727)
	at dotty.tools.dotc.core.SymDenotations$SymDenotation.completeFrom(SymDenotations.scala:167)
	at dotty.tools.dotc.core.Denotations$Denotation.completeInfo$1(Denotations.scala:188)
	at dotty.tools.dotc.core.Denotations$Denotation.info(Denotations.scala:190)
	at dotty.tools.dotc.core.SymDenotations$SymDenotation.ensureCompleted(SymDenotations.scala:369)
	at dotty.tools.dotc.typer.Typer.retrieveSym(Typer.scala:2637)
	at dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:2662)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2757)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2823)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2827)
	at dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:2849)
	at dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:2899)
	at dotty.tools.dotc.typer.Typer.typedClassDef(Typer.scala:2354)
	at dotty.tools.dotc.typer.Typer.typedTypeOrClassDef$2(Typer.scala:2683)
	at dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:2687)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2757)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2823)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2827)
	at dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:2849)
	at dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:2899)
	at dotty.tools.dotc.typer.Typer.typedPackageDef(Typer.scala:2477)
	at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2728)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2758)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2823)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2827)
	at dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:2943)
	at dotty.tools.dotc.typer.FrontEnd.liftedTree1$1(FrontEnd.scala:79)
	at dotty.tools.dotc.typer.FrontEnd.typeCheck$$anonfun$1(FrontEnd.scala:84)
	at dotty.tools.dotc.typer.FrontEnd.monitor(FrontEnd.scala:43)
	at dotty.tools.dotc.typer.FrontEnd.typeCheck(FrontEnd.scala:85)
	at dotty.tools.repl.REPLFrontEnd.runOn(ReplFrontEnd.scala:23)
	at dotty.tools.dotc.Run.runPhases$4$$anonfun$4(Run.scala:205)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1323)
	at dotty.tools.dotc.Run.runPhases$5(Run.scala:216)
	at dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:224)
	at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.scala:18)
	at dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:67)
	at dotty.tools.dotc.Run.compileUnits(Run.scala:231)
	at dotty.tools.dotc.Run.compileUnits(Run.scala:172)
	at dotty.tools.repl.ReplCompiler.runCompilationUnit(ReplCompiler.scala:152)
	at dotty.tools.repl.ReplCompiler.compile(ReplCompiler.scala:162)
	at dotty.tools.repl.ReplDriver.compile(ReplDriver.scala:249)
	at dotty.tools.repl.ReplDriver.interpret(ReplDriver.scala:212)
	at dotty.tools.repl.ReplDriver.loop$1(ReplDriver.scala:146)
	at dotty.tools.repl.ReplDriver.runUntilQuit$$anonfun$1(ReplDriver.scala:149)
	at dotty.tools.repl.ReplDriver.withRedirectedOutput(ReplDriver.scala:168)
	at dotty.tools.repl.ReplDriver.runUntilQuit(ReplDriver.scala:149)
	at dotty.tools.repl.ReplDriver.tryRunning(ReplDriver.scala:115)
	at dotty.tools.repl.Main$.main(Main.scala:6)
	at dotty.tools.repl.Main.main(Main.scala)

The code compiles successfully if we either make unapply non-inlined or put the contextual parameter at the end instead.

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