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bishabosha opened this issue Oct 23, 2020 · 2 comments · Fixed by #18920
Closed

user defined anonymous PolyFunction causes crash at ElimPolyFunction, GenBCode #10075

bishabosha opened this issue Oct 23, 2020 · 2 comments · Fixed by #18920
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@nicolasstucki
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area:polyfunction area:typer itype:bug itype:crash

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@bishabosha
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Minimized code

val foo = new PolyFunction {}

Output (click arrow to expand)

Exception in thread "main" java.util.NoSuchElementException: head of empty list
	at scala.collection.immutable.Nil$.head(List.scala:629)
	at scala.collection.immutable.Nil$.head(List.scala:628)
	at dotty.tools.dotc.transform.ElimPolyFunction.functionTypeOfPoly(ElimPolyFunction.scala:48)
	at dotty.tools.dotc.transform.ElimPolyFunction.transform(ElimPolyFunction.scala:34)
	at dotty.tools.dotc.core.Denotations$SingleDenotation.goForward$1(Denotations.scala:803)
	at dotty.tools.dotc.core.Denotations$SingleDenotation.current(Denotations.scala:852)
	at dotty.tools.dotc.core.Denotations$SingleDenotation.goForward$1(Denotations.scala:823)
	at dotty.tools.dotc.core.Denotations$SingleDenotation.current(Denotations.scala:852)
	at dotty.tools.dotc.core.Denotations$SingleDenotation.goForward$1(Denotations.scala:823)
	at dotty.tools.dotc.core.Denotations$SingleDenotation.current(Denotations.scala:852)
	at dotty.tools.dotc.core.Types$NamedType.computeDenot(Types.scala:2043)
	at dotty.tools.dotc.core.Types$NamedType.denot(Types.scala:2006)
	at dotty.tools.dotc.ast.Trees$DenotingTree.denot(Trees.scala:265)
	at dotty.tools.dotc.ast.Trees$Tree.symbol(Trees.scala:154)
	at dotty.tools.dotc.ast.Trees$.dotty$tools$dotc$ast$Trees$Instance$TreeAccumulator$$_$localCtx$2(Trees.scala:1395)
	at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.foldOver(Trees.scala:1478)
	at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.traverseChildren(Trees.scala:1511)
	at dotty.tools.dotc.transform.CapturedVars$CollectCaptured.traverse(CapturedVars.scala:69)
	at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1510)
	at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1510)
	at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.fold$1(Trees.scala:1385)
	at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.apply(Trees.scala:1387)
	at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.foldOver(Trees.scala:1420)
	at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.traverseChildren(Trees.scala:1511)
	at dotty.tools.dotc.transform.CapturedVars$CollectCaptured.traverse(CapturedVars.scala:69)
	at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1510)
	at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1510)
	at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.foldOver(Trees.scala:1475)
	at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.traverseChildren(Trees.scala:1511)
	at dotty.tools.dotc.transform.CapturedVars$CollectCaptured.traverse(CapturedVars.scala:69)
	at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1510)
	at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1510)
	at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.fold$1(Trees.scala:1385)
	at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.apply(Trees.scala:1387)
	at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.foldOver(Trees.scala:1482)
	at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.traverseChildren(Trees.scala:1511)
	at dotty.tools.dotc.transform.CapturedVars$CollectCaptured.traverse(CapturedVars.scala:69)
	at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1510)
	at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1510)
	at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.foldOver(Trees.scala:1479)
	at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.traverseChildren(Trees.scala:1511)
	at dotty.tools.dotc.transform.CapturedVars$CollectCaptured.traverse(CapturedVars.scala:69)
	at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1510)
	at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1510)
	at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.fold$1(Trees.scala:1385)
	at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.apply(Trees.scala:1387)
	at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.foldOver(Trees.scala:1486)
	at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.traverseChildren(Trees.scala:1511)
	at dotty.tools.dotc.transform.CapturedVars$CollectCaptured.traverse(CapturedVars.scala:69)
	at dotty.tools.dotc.transform.CapturedVars$CollectCaptured.runOver(CapturedVars.scala:72)
	at dotty.tools.dotc.transform.CapturedVars.prepareForUnit(CapturedVars.scala:79)
	at dotty.tools.dotc.transform.MegaPhase.prepUnit(MegaPhase.scala:1039)
	at dotty.tools.dotc.transform.MegaPhase.prepUnit(MegaPhase.scala:1039)
	at dotty.tools.dotc.transform.MegaPhase.transformUnit(MegaPhase.scala:446)
	at dotty.tools.dotc.transform.MegaPhase.run(MegaPhase.scala:459)
	at dotty.tools.dotc.core.Phases$Phase.runOn$$anonfun$1(Phases.scala:296)
	at scala.collection.immutable.List.map(List.scala:246)
	at dotty.tools.dotc.core.Phases$Phase.runOn(Phases.scala:297)
	at dotty.tools.dotc.Run.runPhases$4$$anonfun$4(Run.scala:180)
	at dotty.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at dotty.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1323)
	at dotty.tools.dotc.Run.runPhases$5(Run.scala:190)
	at dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:198)
	at dotty.runtime.function.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:12)
	at dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:64)
	at dotty.tools.dotc.Run.compileUnits(Run.scala:205)
	at dotty.tools.dotc.Run.compileUnits(Run.scala:147)
	at dotty.tools.repl.ReplCompiler.runCompilationUnit(ReplCompiler.scala:151)
	at dotty.tools.repl.ReplCompiler.compile(ReplCompiler.scala:161)
	at dotty.tools.repl.ReplDriver.compile(ReplDriver.scala:233)
	at dotty.tools.repl.ReplDriver.interpret(ReplDriver.scala:196)
	at dotty.tools.repl.ReplDriver.loop$1(ReplDriver.scala:129)
	at dotty.tools.repl.ReplDriver.runUntilQuit$$anonfun$1(ReplDriver.scala:132)
	at dotty.tools.repl.ReplDriver.withRedirectedOutput(ReplDriver.scala:151)
	at dotty.tools.repl.ReplDriver.runUntilQuit(ReplDriver.scala:132)
	at dotty.tools.repl.Main$.main(Main.scala:6)
	at dotty.tools.repl.Main.main(Main.scala)
@bishabosha bishabosha changed the title new PolyFunction causes crash at ElimPolyFunction new empty PolyFunction causes crash at ElimPolyFunction Oct 23, 2020
bishabosha added a commit to dotty-staging/dotty that referenced this issue Oct 30, 2020
@bishabosha
fix scala#10075: do not replace Polyfunction without apply
55e1a5f
@bishabosha
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more cases also crash but for different reasons:

val foo = new PolyFunction {} // error
val bar = new PolyFunction { def bar = 23 } // error
val baz = new PolyFunction { def apply = 23 } // error
val qux = new PolyFunction { def apply[T] = 47 } // error

@bishabosha bishabosha mentioned this issue Jan 9, 2021
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@bishabosha bishabosha assigned nicolasstucki and unassigned smarter Nov 6, 2023
@bishabosha
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@nicolasstucki these still crash, I changed assignment because you made changes to PolyFunction recently

@bishabosha bishabosha changed the title new empty PolyFunction causes crash at ElimPolyFunction user defined anonymous PolyFunction causes crash at ElimPolyFunction Nov 6, 2023
@bishabosha bishabosha changed the title user defined anonymous PolyFunction causes crash at ElimPolyFunction user defined anonymous PolyFunction causes crash at ElimPolyFunction, GenBCode Nov 6, 2023
nicolasstucki added a commit to dotty-staging/dotty that referenced this issue Nov 14, 2023
@nicolasstucki
Disallow use of PolyFunction trait in class parents
9af3c6d 
Users should only write lambdas.

Fixes scala#10075
@nicolasstucki nicolasstucki mentioned this issue Nov 14, 2023
Merged
nicolasstucki added a commit to dotty-staging/dotty that referenced this issue Nov 15, 2023
@nicolasstucki
Disallow use of PolyFunction trait in class parents
1b4b390 
Users should only write lambdas.

Fixes scala#10075
nicolasstucki added a commit to dotty-staging/dotty that referenced this issue Nov 20, 2023
@nicolasstucki
Disallow use of PolyFunction trait in class parents
63b31ac 
Users should only write lambdas.

Fixes scala#10075
smarter added a commit that referenced this issue Nov 23, 2023
@smarter
Disallow extending PolyFunction in user code (#18920)
00e9e6b 
The `PolyFunction` trait should only be used for compiler generated
encoded lambdas.

Any other use case that was allowed before was accidental. In the
future,
we might consider supporting these if there is a good use case. This
would
probably require a SIP.

Fixes #10075
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Disallow use of PolyFunction in user code dotty-staging/dotty
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@smarter @OlivierBlanvillain @nicolasstucki @bishabosha