Invalid PolyFunction refinements #18302
Description
Compiler version
3.4.0-RC1-bin-20230726-97677cc-NIGHTLY
Issue
We are not restricting the signatures of the user-written (in source or macro) refinements of PolyFunction. We should restrict and check that those refinements are valid
Example 1
def test = polyFun(1)
def polyFun: PolyFunction { def apply(x: Int): Int } =
new PolyFunction { def apply(x: Int): Int = x + 1 }Works but is outside of the current spec of PolyFunction. These should be supported at some point. We should probably emit an error now and allow it once we update the spec.
Example 2
def test = polyFun(1)(2)
def polyFun: PolyFunction { def apply(x: Int)(y: Int): Int } =
new PolyFunction:
def apply(x: Int)(y: Int): Int = x + yThis is not supported by the spec and is not intended to be supported. It currently crashes the compiler with
java.util.NoSuchElementException: head of empty list
Exception in thread "main" java.lang.AssertionError: assertion failed
at scala.runtime.Scala3RunTime$.assertFailed(Scala3RunTime.scala:11)
at dotty.tools.dotc.core.TypeErasure$.functionType$1(TypeErasure.scala:569)
at dotty.tools.dotc.core.TypeErasure$.eraseRefinedFunctionApply(TypeErasure.scala:572)
at dotty.tools.dotc.core.TypeErasure.dotty$tools$dotc$core$TypeErasure$$apply(TypeErasure.scala:658)
at dotty.tools.dotc.core.TypeErasure.eraseResult(TypeErasure.scala:881)
at dotty.tools.dotc.core.TypeErasure.eraseInfo(TypeErasure.scala:815)
at dotty.tools.dotc.core.TypeErasure$.transformInfo(TypeErasure.scala:275)
at dotty.tools.dotc.transform.Erasure.transform(Erasure.scala:97)
exception while retyping @SourceFile("tests/run-custom-args/erased/erased-15.scala") final module class
erased-15$package() extends Object() {
private def writeReplace(): AnyRef =
new scala.runtime.ModuleSerializationProxy(classOf[erased-15$package.type])
def test: Int = polyFun.apply(1)(2)
def polyFun: (x: Int) => (y: Int) => Int =
{
final class $anon() extends Object(), PolyFunction {
def apply(x: Int)(y: Int): Int = x.+(y)
private val $outer: erased-15$package
final def erased-15$package$_$$anon$$$outer: erased-15$package = $outer
}
new Object with PolyFunction {...}():((x: Int) => (y: Int) => Int)
}
} of class TypeDef # -1
An unhandled exception was thrown in the compiler.
Please file a crash report here:
https://github.com/lampepfl/dotty/issues/new/choose
while compiling: tests/run-custom-args/erased/erased-15.scala
during phase: MegaPhase{elimErasedValueType, pureStats, vcElideAllocations, etaReduce, arrayApply, elimPolyFunction, tailrec, completeJavaEnums, mixin, lazyVals, memoize, nonLocalReturns, capturedVars}
mode: Mode(ImplicitsEnabled)
library version: version 2.13.10
compiler version: version 3.4.0-RC1-bin-SNAPSHOT-nonbootstrapped-git-c04d2db
settings: -classpath /Users/nicolasstucki/Library/Caches/Coursier/v1/https/repo1.maven.org/maven2/org/scala-lang/scala-library/2.13.10/scala-library-2.13.10.jar:/Users/nicolasstucki/GitHub/dotty/library/../out/bootstrap/scala3-library-bootstrapped/scala-3.4.0-RC1-bin-SNAPSHOT-nonbootstrapped/scala3-library_3-3.4.0-RC1-bin-SNAPSHOT.jar -d t/out
tree: PackageDef(object <empty>)
tree position: tests/run-custom-args/erased/erased-15.scala:1:0
tree type: <empty>.type
symbol: package <empty>
symbol definition: final lazy module object <empty>: <empty> (a Symbol)
symbol package: <root>
symbol owners:
call site: package <empty> in module class <empty>
== Source file context for tree position ==
-- Error: tests/run-custom-args/erased/erased-15.scala:1:0 ---------------------
1 |def test = polyFun(1)(2)
|^
2 |def polyFun: PolyFunction { def apply(x: Int)(y: Int): Int } =
3 | new PolyFunction:
4 | def apply(x: Int)(y: Int): Int = x + y
at dotty.tools.dotc.core.Denotations$SingleDenotation.goForward$1(Denotations.scala:830)
at dotty.tools.dotc.core.Denotations$SingleDenotation.current(Denotations.scala:876)
at dotty.tools.dotc.core.Symbols$Symbol.recomputeDenot(Symbols.scala:122)
at dotty.tools.dotc.core.Symbols$Symbol.computeDenot(Symbols.scala:116)
at dotty.tools.dotc.core.Symbols$Symbol.denot(Symbols.scala:109)
at dotty.tools.dotc.core.Symbols$.toDenot(Symbols.scala:496)
at dotty.tools.dotc.core.SymDenotations$ClassDenotation.paramAccessors$$anonfun$1(SymDenotations.scala:2392)
at dotty.tools.dotc.core.Scopes$Scope.filter(Scopes.scala:102)
at dotty.tools.dotc.core.SymDenotations$ClassDenotation.paramAccessors(SymDenotations.scala:2392)
at dotty.tools.dotc.core.Contexts$Context.superCallContext(Contexts.scala:408)
at dotty.tools.dotc.typer.Typer.typedClassDef(Typer.scala:2626)
at dotty.tools.dotc.transform.Erasure$Typer.typedClassDef(Erasure.scala:1043)
at dotty.tools.dotc.typer.Typer.typedTypeOrClassDef$1(Typer.scala:3087)
at dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:3091)
at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:3166)
at dotty.tools.dotc.typer.ReTyper.typedUnadapted(ReTyper.scala:174)
at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3243)
at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3247)
at dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:3269)
at dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:3315)
at dotty.tools.dotc.transform.Erasure$Typer.typedStats(Erasure.scala:1054)
at dotty.tools.dotc.typer.Typer.typedPackageDef(Typer.scala:2861)
at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:3133)
at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:3167)
at dotty.tools.dotc.typer.ReTyper.typedUnadapted(ReTyper.scala:174)
at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3243)
at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3247)
at dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:3359)
at dotty.tools.dotc.transform.Erasure.run(Erasure.scala:144)
at dotty.tools.dotc.core.Phases$Phase.runOn$$anonfun$1(Phases.scala:327)
at scala.collection.immutable.List.map(List.scala:246)
at dotty.tools.dotc.core.Phases$Phase.runOn(Phases.scala:331)
at dotty.tools.dotc.Run.runPhases$1$$anonfun$1(Run.scala:246)
at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
at scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1321)
at dotty.tools.dotc.Run.runPhases$1(Run.scala:262)
at dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:270)
at dotty.tools.dotc.Run.compileUnits$$anonfun$adapted$1(Run.scala:279)
at dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:67)
at dotty.tools.dotc.Run.compileUnits(Run.scala:279)
at dotty.tools.dotc.Run.compileSources(Run.scala:194)
at dotty.tools.dotc.Run.compile(Run.scala:179)
at dotty.tools.dotc.Driver.doCompile(Driver.scala:37)
at dotty.tools.dotc.Driver.process(Driver.scala:197)
at dotty.tools.dotc.Driver.process(Driver.scala:165)
at dotty.tools.dotc.Driver.process(Driver.scala:177)
at dotty.tools.dotc.Driver.main(Driver.scala:207)
at dotty.tools.dotc.Main.main(Main.scala)
Example 3
import scala.reflect.Selectable.reflectiveSelectable
def test = polyFun.foo(1)
def polyFun: PolyFunction { def foo(x: Int): Int } =
new PolyFunction { def foo(x: Int): Int = x + 1 }Not in the spec. Crashes the compiler with
java.util.NoSuchElementException: head of empty list
Exception in thread "main" java.util.NoSuchElementException: head of empty list
unhandled exception while running MegaPhase{elimErasedValueType, pureStats, vcElideAllocations, etaReduce, arrayApply, elimPolyFunction, tailrec, completeJavaEnums, mixin, lazyVals, memoize, nonLocalReturns, capturedVars} on Test.scala
An unhandled exception was thrown in the compiler.
Please file a crash report here:
https://github.com/lampepfl/dotty/issues/new/choose
while compiling: Test.scala
during phase: MegaPhase{elimErasedValueType, pureStats, vcElideAllocations, etaReduce, arrayApply, elimPolyFunction, tailrec, completeJavaEnums, mixin, lazyVals, memoize, nonLocalReturns, capturedVars}
mode: Mode(ImplicitsEnabled)
library version: version 2.13.10
compiler version: version 3.4.0-RC1-bin-SNAPSHOT-nonbootstrapped-git-c04d2db
settings: -classpath /Users/nicolasstucki/Library/Caches/Coursier/v1/https/repo1.maven.org/maven2/org/scala-lang/scala-library/2.13.10/scala-library-2.13.10.jar:/Users/nicolasstucki/GitHub/dotty/library/../out/bootstrap/scala3-library-bootstrapped/scala-3.4.0-RC1-bin-SNAPSHOT-nonbootstrapped/scala3-library_3-3.4.0-RC1-bin-SNAPSHOT.jar -d t/out
tree: EmptyTree
tree position: :<unknown>
tree type: <notype>
symbol: val <none>
call site: package <root> in module class <root>
== Source file context for tree position ==
at scala.collection.immutable.Nil$.head(List.scala:662)
at scala.collection.immutable.Nil$.head(List.scala:661)
at dotty.tools.dotc.transform.ElimPolyFunction.functionTypeOfPoly(ElimPolyFunction.scala:50)
at dotty.tools.dotc.transform.ElimPolyFunction.transform(ElimPolyFunction.scala:36)
at dotty.tools.dotc.core.Denotations$SingleDenotation.goForward$1(Denotations.scala:830)
at dotty.tools.dotc.core.Denotations$SingleDenotation.current(Denotations.scala:876)
at dotty.tools.dotc.core.Denotations$SingleDenotation.goForward$1(Denotations.scala:847)
at dotty.tools.dotc.core.Denotations$SingleDenotation.current(Denotations.scala:876)
at dotty.tools.dotc.core.Denotations$SingleDenotation.goForward$1(Denotations.scala:847)
at dotty.tools.dotc.core.Denotations$SingleDenotation.current(Denotations.scala:876)
at dotty.tools.dotc.core.Types$NamedType.computeDenot(Types.scala:2425)
at dotty.tools.dotc.core.Types$NamedType.denot(Types.scala:2388)
at dotty.tools.dotc.ast.Trees$DenotingTree.denot(Trees.scala:256)
at dotty.tools.dotc.ast.Trees$Tree.symbol(Trees.scala:145)
at dotty.tools.dotc.ast.tpd$.localOwner(tpd.scala:609)
at dotty.tools.dotc.ast.tpd$.localCtx(tpd.scala:613)
at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.foldOver(Trees.scala:1745)
at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.traverseChildren(Trees.scala:1791)
at dotty.tools.dotc.transform.CapturedVars$CollectCaptured.traverse(CapturedVars.scala:74)
at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1790)
at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1790)
at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.fold$1(Trees.scala:1654)
at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.apply(Trees.scala:1656)
at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.foldOver(Trees.scala:1687)
at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.traverseChildren(Trees.scala:1791)
at dotty.tools.dotc.transform.CapturedVars$CollectCaptured.traverse(CapturedVars.scala:74)
at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1790)
at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1790)
at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.foldOver(Trees.scala:1742)
at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.traverseChildren(Trees.scala:1791)
at dotty.tools.dotc.transform.CapturedVars$CollectCaptured.traverse(CapturedVars.scala:74)
at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1790)
at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1790)
at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.fold$1(Trees.scala:1654)
at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.apply(Trees.scala:1656)
at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.foldOver(Trees.scala:1749)
at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.traverseChildren(Trees.scala:1791)
at dotty.tools.dotc.transform.CapturedVars$CollectCaptured.traverse(CapturedVars.scala:74)
at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1790)
at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1790)
at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.foldOver(Trees.scala:1746)
at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.traverseChildren(Trees.scala:1791)
at dotty.tools.dotc.transform.CapturedVars$CollectCaptured.traverse(CapturedVars.scala:74)
at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1790)
at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.apply(Trees.scala:1790)
at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.fold$1(Trees.scala:1654)
at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.apply(Trees.scala:1656)
at dotty.tools.dotc.ast.Trees$Instance$TreeAccumulator.foldOver(Trees.scala:1755)
at dotty.tools.dotc.ast.Trees$Instance$TreeTraverser.traverseChildren(Trees.scala:1791)
at dotty.tools.dotc.transform.CapturedVars$CollectCaptured.traverse(CapturedVars.scala:74)
at dotty.tools.dotc.transform.CapturedVars$CollectCaptured.runOver(CapturedVars.scala:77)
at dotty.tools.dotc.transform.CapturedVars.prepareForUnit(CapturedVars.scala:84)
at dotty.tools.dotc.transform.MegaPhase.prepUnit(MegaPhase.scala:1095)
at dotty.tools.dotc.transform.MegaPhase.prepUnit(MegaPhase.scala:1095)
at dotty.tools.dotc.transform.MegaPhase.prepUnit(MegaPhase.scala:1095)
at dotty.tools.dotc.transform.MegaPhase.transformUnit(MegaPhase.scala:468)
at dotty.tools.dotc.transform.MegaPhase.run(MegaPhase.scala:481)
at dotty.tools.dotc.core.Phases$Phase.runOn$$anonfun$1(Phases.scala:327)
at scala.collection.immutable.List.map(List.scala:246)
at dotty.tools.dotc.core.Phases$Phase.runOn(Phases.scala:331)
at dotty.tools.dotc.Run.runPhases$1$$anonfun$1(Run.scala:246)
at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
at scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1321)
at dotty.tools.dotc.Run.runPhases$1(Run.scala:262)
at dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:270)
at dotty.tools.dotc.Run.compileUnits$$anonfun$adapted$1(Run.scala:279)
at dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:67)
at dotty.tools.dotc.Run.compileUnits(Run.scala:279)
at dotty.tools.dotc.Run.compileSources(Run.scala:194)
at dotty.tools.dotc.Run.compile(Run.scala:179)
at dotty.tools.dotc.Driver.doCompile(Driver.scala:37)
at dotty.tools.dotc.Driver.process(Driver.scala:197)
at dotty.tools.dotc.Driver.process(Driver.scala:165)
at dotty.tools.dotc.Driver.process(Driver.scala:177)
at dotty.tools.dotc.Driver.main(Driver.scala:207)
at dotty.tools.dotc.Main.main(Main.scala)