Lazy enums. #5034

sir-wabbit · 2018-08-26T20:20:33Z

It would be great if there were lazy enums with the following encoding:

// Or maybe just by-name parameters?
lazy enum LazyList[+A] {
  case :: (head: => A, tail: LazyList[A])
  case Nil 
}
// >>>
sealed trait LazyList[+A]
object LazyList {
  final class :: [A](_head: => A, _tail: => LazyList[A]) extends LazyList[A] {
    lazy val head: A = _head
    lazy val tail: LazyList[A] = _tail
  }
  final case object Nil extends LazyList[+A]
  // plus *lazy* unapply that doesn't immediately evaluate head or tail
}

But in the meantime, here is a crash:

lazy enum i0

Exception in thread "main" java.lang.AssertionError: assertion failed: illegal flagset combination: lazy abstract <enum> and sealed
	at dotty.DottyPredef$.assertFail(DottyPredef.scala:38)
	at dotty.tools.dotc.core.Flags$FlagSet$.$bar$extension(Flags.scala:26)
	at dotty.tools.dotc.ast.DesugarEnums$.addEnumFlags(DesugarEnums.scala:74)
	at dotty.tools.dotc.ast.desugar$.classDef(Desugar.scala:629)
	at dotty.tools.dotc.ast.desugar$.defTree(Desugar.scala:773)
	at dotty.tools.dotc.typer.Namer.expand(Namer.scala:419)
	at dotty.tools.dotc.typer.Namer.index$$anonfun$1(Namer.scala:683)
	at scala.compat.java8.JProcedure1.apply(JProcedure1.java:18)
	at scala.compat.java8.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.immutable.List.foreach(List.scala:389)
	at dotty.tools.dotc.typer.Namer.index(Namer.scala:683)
	at dotty.tools.dotc.typer.Namer.recur$1(Namer.scala:462)
	at dotty.tools.dotc.typer.Namer.indexExpanded(Namer.scala:479)
	at dotty.tools.dotc.typer.Namer.index(Namer.scala:452)
	at dotty.tools.dotc.typer.FrontEnd.enterSyms$$anonfun$1(FrontEnd.scala:54)
	at scala.compat.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:12)
	at dotty.tools.dotc.typer.FrontEnd.monitor(FrontEnd.scala:34)
	at dotty.tools.dotc.typer.FrontEnd.enterSyms(FrontEnd.scala:56)

AE-2251401fe4c14de0510247ea75752a42fcfb237a

The text was updated successfully, but these errors were encountered:

…zy instead of crash

allanrenucci · 2018-11-22T15:19:42Z

Crashes for erased enum as well

Fixes scala#5034

nicolasstucki · 2019-01-18T15:22:59Z

https://github.com/lampepfl/dotty/blob/master/tests/pending/fuzzy/AE-2251401fe4c14de0510247ea75752a42fcfb237a.scala

Prevents the compiler from crashing, and returns error instead

bishabosha · 2019-11-05T12:51:02Z

this still crashes with the same error:

lazy enum i0 { case A }

BluePat · 2019-11-09T03:11:17Z

Well, is help wanted for this issue? Glad to contribute. Or at least try to tackle it.

bishabosha · 2019-11-09T10:45:35Z

@BluePat PR's are always welcome :), at the very least there should should a sensible user facing error before the assertion crash, probably before/in addEnumFlags

allanrenucci · 2019-11-09T10:53:30Z

@BluePat There are two stale PRs #5525, #6674. Make sure your fix addresses the comments in these PRs.

BluePat · 2019-11-10T08:58:09Z

@bishabosha, @allanrenucci, thanks for the tips. I'll take them into consideration.

sir-wabbit · 2019-12-13T05:07:26Z

Same crash:

erased enum

sir-wabbit · 2019-12-20T02:56:09Z

Similar crash:

enum A
sealed abstract case

Stack trace

-- [E040] Syntax Error: testing/Test.scala:2:0 ---------------------------------
2 |sealed abstract case
  |^^^^^^
  |'{' expected, but 'end of statement' found
-- [E040] Syntax Error: testing/Test.scala:2:20 --------------------------------
2 |sealed abstract case
  |                    ^
  |                    an identifier expected, but eof found
-- Error: testing/Test.scala:2:7 -----------------------------------------------
2 |sealed abstract case
  |       ^^^^^^^^
  |       abstract modifier cannot be used for objects
exception occurred while typechecking testing/Test.scala
exception occurred while compiling testing/Test.scala
java.lang.AssertionError: assertion failed: illegal flagset combination: sealed case abstract <enum> and <stable> <enum> while compiling testing/Test.scala
Exception in thread "main" java.lang.AssertionError: assertion failed: illegal flagset combination: sealed case abstract <enum> and <stable> <enum>
	at dotty.DottyPredef$.assertFail(DottyPredef.scala:17)
	at dotty.tools.dotc.core.Flags$given_bits_of_FlagSet$.$bar(Flags.scala:40)
	at dotty.tools.dotc.ast.untpd$Modifiers.$bar(untpd.scala:216)
	at dotty.tools.dotc.ast.DesugarEnums$.expandSimpleEnumCase(DesugarEnums.scala:307)
	at dotty.tools.dotc.ast.DesugarEnums$.expandEnumModule(DesugarEnums.scala:284)
	at dotty.tools.dotc.ast.desugar$.moduleDef(Desugar.scala:886)
	at dotty.tools.dotc.ast.desugar$.defTree(Desugar.scala:1187)
	at dotty.tools.dotc.typer.Namer.expand(Namer.scala:484)
	at dotty.tools.dotc.typer.Namer.index$$anonfun$1(Namer.scala:765)
	at dotty.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at dotty.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.immutable.List.foreach(List.scala:305)
	at dotty.tools.dotc.typer.Namer.index(Namer.scala:765)
	at dotty.tools.dotc.typer.Namer$ClassCompleter.completeConstructor(Namer.scala:1133)
	at dotty.tools.dotc.typer.Namer$ClassCompleter.completeInCreationContext(Namer.scala:1208)
	at dotty.tools.dotc.typer.Namer$Completer.complete(Namer.scala:843)
	at dotty.tools.dotc.core.SymDenotations$SymDenotation.completeFrom(SymDenotations.scala:258)
	at dotty.tools.dotc.core.Denotations$Denotation.completeInfo$1(Denotations.scala:185)
	at dotty.tools.dotc.core.Denotations$Denotation.info(Denotations.scala:187)
	at dotty.tools.dotc.core.Types$NamedType.info(Types.scala:1930)
	at dotty.tools.dotc.core.Types$NamedType.withDenot(Types.scala:2284)
	at dotty.tools.dotc.core.Types$TypeRef$.apply(Types.scala:2473)
	at dotty.tools.dotc.core.Types$NamedType$.apply(Types.scala:2447)
	at dotty.tools.dotc.core.Types$Type.select(Types.scala:1377)
	at dotty.tools.dotc.typer.Typer.loop$2(Typer.scala:299)
	at dotty.tools.dotc.typer.Typer.findRefRecur$1(Typer.scala:345)
	at dotty.tools.dotc.typer.Typer.findRef(Typer.scala:348)
	at dotty.tools.dotc.typer.Typer.typedIdent(Typer.scala:399)
	at dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:2098)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2176)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2213)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2225)
	at dotty.tools.dotc.typer.Typer.typedType(Typer.scala:2335)
	at dotty.tools.dotc.typer.Typer.typedValDef(Typer.scala:1585)
	at dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:2103)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2176)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2213)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2225)
	at dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:2247)
	at dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:2291)
	at dotty.tools.dotc.typer.Typer.typedPackageDef(Typer.scala:1910)
	at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2150)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2177)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2213)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2225)
	at dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:2333)
	at dotty.tools.dotc.typer.FrontEnd.liftedTree1$2(FrontEnd.scala:78)
	at dotty.tools.dotc.typer.FrontEnd.typeCheck$$anonfun$1(FrontEnd.scala:83)
	at dotty.runtime.function.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:12)
	at dotty.tools.dotc.typer.FrontEnd.monitor(FrontEnd.scala:42)
	at dotty.tools.dotc.typer.FrontEnd.typeCheck(FrontEnd.scala:84)
	at dotty.tools.dotc.typer.FrontEnd.runOn$$anonfun$3(FrontEnd.scala:114)
	at dotty.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at dotty.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.immutable.List.foreach(List.scala:305)
	at dotty.tools.dotc.typer.FrontEnd.runOn(FrontEnd.scala:114)
	at dotty.tools.dotc.Run.runPhases$4$$anonfun$4(Run.scala:161)
	at dotty.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at dotty.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1323)
	at dotty.tools.dotc.Run.runPhases$5(Run.scala:171)
	at dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:179)
	at dotty.runtime.function.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:12)
	at dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:65)
	at dotty.tools.dotc.Run.compileUnits(Run.scala:186)
	at dotty.tools.dotc.Run.compileSources(Run.scala:123)
	at dotty.tools.dotc.Run.compile(Run.scala:106)
	at dotty.tools.dotc.Driver.doCompile(Driver.scala:36)
	at dotty.tools.dotc.Driver.process(Driver.scala:189)
	at dotty.tools.dotc.Driver.process(Driver.scala:158)
	at dotty.tools.dotc.Driver.process(Driver.scala:170)
	at dotty.tools.dotc.Driver.main(Driver.scala:197)
	at dotty.tools.dotc.Main.main(Main.scala)

allanrenucci · 2020-01-02T10:40:44Z

Fixed in #7850

Blaisorblade added itype:crash exp:novice labels Aug 27, 2018

skvithalani added a commit to skvithalani/dotty that referenced this issue Aug 31, 2018

Fix scala#5034:Attempt to throw proper error when enum is declared la…

663d580

…zy instead of crash

allanrenucci mentioned this issue Nov 22, 2018

Allowed modifiers for enums and enum cases #5495

Closed

allanrenucci added a commit to dotty-staging/dotty that referenced this issue Nov 27, 2018

Fix scala#5495: Reject invalid modifiers on enums

b6c58f1

Fixes scala#5034

allanrenucci mentioned this issue Nov 27, 2018

Fix #5495: Reject invalid modifiers on enums #5525

Closed

allanrenucci added a commit to dotty-staging/dotty that referenced this issue Nov 27, 2018

Fix scala#5495: Reject invalid modifiers on enums

0f49528

Fixes scala#5034

allanrenucci added a commit to dotty-staging/dotty that referenced this issue Nov 27, 2018

Fix scala#5495: Reject invalid modifiers on enums

ae53967

Fixes scala#5034

machadoit added a commit to machadoit/dotty that referenced this issue Jun 12, 2019

Fix scala#5034: Add error on lazy enum

0578241

Prevents the compiler from crashing, and returns error instead

machadoit added a commit to machadoit/dotty that referenced this issue Jun 12, 2019

Fix scala#5034: Add error on lazy enum

78b380b

Prevents the compiler from crashing, and returns error instead

allanrenucci closed this as completed Jan 2, 2020

bishabosha mentioned this issue Jan 15, 2020

Enum Improvements Epic #7501

Closed

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Lazy enums. #5034

Lazy enums. #5034

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Lazy enums. #5034

Lazy enums. #5034

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